CA2191457A1 - Method and apparatus for producing thin films - Google Patents

Abstract

To deposit a film on a substrate (22) by plasma-enhanced chemical vapor deposition at temperatures sub-stantially lower than conventional thermal CVD temper-atures, a substrate is placed within a reaction chamber (12) and a first gas is excited upstream of the substrate to generate activated radicals of the first gas. A second gas is supplied proximate the substrate to mix with the activated radicals of the first gas and the mixture pro-duces a surface reaction at the substrate to deposit a film.
Rotation of the substrate draws the gas mixture down to the substrate surface in a laminar flow (29) to reduce re-circulation and radical recombination. Another method utilizes a gas-dispersing showerhead (298) that is biased with RF energy to form an electrode which generates ac-tivated radicals and ions in a concentrated plasma close to the substrate surface.

Description

5 7, ~
~VO 9~33867 PCT/US94113641 Method and apparatus for produc~ng th~n f~lms FIF.~n OF 'I'HI~ vF~ oN
This invention relates generally to rl~r~- ' ' chemical vapor deposition (PECVD) for applying a film coating to a substrate, and more specifically to PECVD conducted at a low effective deposition i , at the substrate surface. ~ven more specifically, the invention relates to deposition of titanium containing films using low t~ ,.t; CVD.

12~\('~('~R-)UND OF T~E INVEN~ON
In the formation of integrated circuits (IC's), thin films containmg metal and metalloid dements are often deposited upon the surface of a substrate, such as a ' wafer. Thin films are derosited to provide conductive and ohmic contacts in the circuits and between the various devices of an IC. For example, a desired thin film might be applied to the exposed surface of a contact or via hole on a ! ' ' wafer, with the film passing through the insulative SUBSTITUTE SHEET (~LILE 26) a ~ 5 7. ~'

-2- PCI/IJS9~/136~1 Iayers on the wafer to provide plugs of conductive material for the purpose of making across the insulating layers.
One well known process for depositing thin metal films is chemical vapor deposition (CVD) in which a thin film is deposited using chemical reactions bet veen various deposition or reactant gases at the surface of the substrate. In CVD, reactant gases are pumped into proximity to a substrate inside a reaction chamber, and the gases ' , '~, react at the substrate surface resulting in one or more reaction by-products which forln a film on the substrate surface. Any by-products remaining after the deposition are removed from the chamber. While CVD is a useful technique for depositing films, many of the traditional CVD
processes are basically thermal processes and require t. .,~ in excess of 1000C in order to obtain the neceSsary reactions. Such a deposition is often far too high to be practically useful in IC fabrication due to the effects that high i . have on various other aspects and layers of the electrical devices making up the IC.
P~li~ l~ly, certain aspects of IC ~ r ' degraded by exposure to the high: I normally related to traditional thermal CVD
processes. For example, at the device level of an IC, there are shallow diffusions of ~ dopants which for~n the junctions of the electrical devices within the IC. The dopants are often initially diffused using heat during a diffusion step, and therefore, the dopants will continue to diffuse when the IC is subjected to a high ~ during CVD. Such furher diffusion is I ' ' ' because it causes the junction of the device to shift, and thus alters the resulting electrical " f' ' ;`1 i' ` 0f the IC. T~herefore, for cerain IC devices, exposing the substr_te SUE'STITUTE SHEET (RULE 26) a~ 57.~
~WO 95133867 PCTIUS94/13641 ~3~
to processing i r ' ~ of above iO0C is avoided, aud the upper ~ r limit may be as low as 650C for other more i . sensitive devices.
r.; such i I limitations may become even more severe if thermal CVD is performe(i after metal , or wiring has been applied to the IC. For e~ample, many IC's utilize aluminum as an metal. However, various I ' ' ' voids and extrusions occur in aluminum when it is subjecte~i to high processing Therefore, once ~ aluminum has been deposited onto an IC, the maximum to which it can be e~pose(i is 31r ' ' 1y 500C, and the preferred upper; . limit is 400C. Therefore, as may be 3~r ' i~ it is desirable during CVD processes to maintain low deposition i r ' whenever possible.
Cr--, 'y, the upper L~ h ldLul~ limit to which a substrate must be expose(i precludes the use of some tra~iitional thermal CVD processes which might otherwise be very useful in fabricdting IC's. A good example of one such useful process is the chemical vapor deposition of titanium. Titanium is typically used to provide ohmic contact between the silicon contacts of an IC device and a metal , Titanium may be depositei from TiBr4, TiCI4 or Til~ by using CVD methods such as I ' pyrolysis or hydrogen reduction.
However, the ~ necessary for these thermal processes are in excess of 1000C, and such a deposition ~ r is much to high to be practically useful in IC f~i)rir~tirn Therefore, the deposition of titanium and titanium-containing films presents a problem in formation of integrated circuits.
SUBSTITUTE SHEET (RULE 26 11 4 5 7. ~
Wl~ 95133867 PCTIUS9-1/136 There are low i , physical techniques available for depositing titanium on I r ' sensitive substrates. Sputtering is one such technique involving the use of a target of layer material and an ionized plasma.
To sputter deposit a film, the target is electrically biased and ions from the plasma are attracted to the target to bombard the target and dislodge target material particles. Tbe particles then deposit themselves ~,u~ul~ ,ly as a film upon the substrate. Titanium may be sputtered, for example, over a silicon substrate after various contacts or via openings are cut into a level of the substrate. The substrate might then be heated to about 800C to allow the silicon and titanium to alloy and form a layer of titanium silicide (TiSiz). After the deposition of the titanium layer, the excess titanium is etched away from the top surface of the substrate leaving TiSiz at the bottom of each contact or via. A metal is then deposited directly over the TiSil.
While physical sputtering provides deposition of a titanium film at a lower t.,~ ulC;, sputtering processes have various drawbacks. Sputtering normally yields very poor step coverage. Step coverage is defined as the ratio of film thickness on the bottom of a contact on a substrate wafer to the film thickness on the sides of the contact or the top surface of the substrate. f . '~" to sputter deposit a l,.cd~ ' amount of titanium at the bottom of a contact or via, a larger amount of the sputtered titanium must be deposited on the top surface of the substrate or the sides of the contact. For example, in order to deposit a 200A film at the bottom of a contact using sputtering, a 600A to loooA film layer may have to be deposited onto the top surface of the substrate or the sides of the SUBSTITUTE SHEET (RULE 26) 2 ~ 5 7. ~
~VO 95/33867 . PCT/US94/13641 contact. Since the excess titanium has to be etched away, sputtering is wasteful and costly when depositing layers containing titanium.
r, i~ , the step coverage of the contact with sputtering techniques decreases as the aspect ratio of the contact or via increases. The aspect ratio of a contact is defined as the ratio of contact depth to the width of the contact. Therefore, a thicker sputtered film must be deposited on the top or sides of a contact that is narrow and deep (high aspect ratio) in order to obtain a particular film thickness at the bottom of the contact than would be necessary with a shallow and wide contact (low aspect ratio). In other words, for smaller device dimensions in an IC, ~ r ~ g to high aspect ratio contacts and vias, sputtering is even more inefficient and wasteful. The decreased step coverage during sputter deposition over smaller devices results in an increased amount of titanium that must be deposited, thus increasing the arnount of titanium applied and etched away, increasing the titanium deposition time, and increasing the etching time that is necessary to remove excess titanium. Accordingly, as IC device geometries continue to shrink and aspect ratios increase, deposition of titanium-containing layers by sputtering becomes very costly.
On the other hand, using a CVD process for depositing a titanium-containing film layer may be ~ ' with nearly 100% step coverage. That is, the film thickness at the bottom of the contact would d~ y equal the thickness on the top surface almost regardless of the aspect ratio of the contact or via being filled. However, as discussed above, the L.l~d~Ul~,D necessary for such CVD processes are too high and would degrade other aspects of the IC.

C~ , it would be desir-able to achieve titanium CVD at a ~ less SUBSTITUTE SHEET (RULE 26) 2 ~ 4 5 7~ ~:
WO 95/33867 -6- PC'r/US94/136.11 than 800C, and preferably less than 650C. Further, it is generally desirable ho reduce the deposition i . for any CVD process which is utilized to deposit a film in IC fabrication.
One approach which has been utilized in CVD processes to lower the reaction i is to ionize one or more of the reactant gases. Such a technique is generally referred to as plasma enhanced chemical vapor deposition (PECVD). While it has been possible with such an approach to somewhat lower the deposition h r ' _~ the high sticking coefficient of the ionized plasma particles degrades the step coverage of the film. That is, ions of the reactant gases are highly reactive and have a tendency to contact and stick to the walls of the vias or contacts in the substrahe. The ion particles do not migrate du....w~.~ to the bottom surface of the contact where the coating is desired but rather non-conformally coat the sides of the contact. This results in increased material usage, deposition timeS and etch times. Therefore, PECVD using ionized reactant gases has not been a completely adequate solution to lowering traditional high CVD i r ' and achieving good step coverage and film ~J..~rllll''~ y.
Additionally, when using a CVD process to apply a film, it is desirable to uniformly deposit the film. To do so, such as to apply a uniform film of tungsten (W), for example, a uniform supply of reactant gases must be supplied across the surface of the substrate and the spent gases and reaction by-products should be removed from the surface being coated. In this respect, prior art CVD
processeS have again performed with limited success. Specifically, in known CVD
processes, turbulence in the flow of reaction gases inhibits the efficiency and uniformity of the coating process and aggravah~s the deposition and migration of SUBSTITUTE SHEET (RULE ~6) 2 ~ ~ ~ 4 5 ~
~WO 95133867 PCT/US941136 11 within the reaction chamber. In tungsten CVD processes, tungsten k n~ (WF6) is employed as a reactant gas. Tungsten 1. -ll,....i~r is very costly and thus, when reactant gas utilization efficiency is low, as it is in prior art CVD processes, the overall process costs are S;V~url~la~ increased. Accordingly, there is a need for CVD processes which have improved gas flow and reduced gas flow turbulence to more efficiently and more uniformly supply reaction gases to amd remove reaction by-products from the surfaces of the substrate being coated.
Therefore, CVD processes which may be , ' ' at lower effective 1~ are desired. It is further desirable to have a low deposition which provides good step coverage. It is still further desirable to have a PECVD process which produces uniform film thickness and effective utilization of reactant gases. Accordingly, the present invention addresses these objectives and the ' v Of the various CVD and PECVD
processes currently available. Further, the present invention, ~uti~,lLul.y addresses the difficulties associated with depositing titanium and titanium-containing films using CVD.

c ~ofth~r The CVD ..y --~ and methods of the present invention overcome or obviate the high t~ d~L~Iv and gas flow drawbacks associated with many of the currently available thermal CVD and PECVD -1~ and processes. Specifically, the present invention achieves deposition of a titanium-containing film at a substantially lower ~ l r. as compared to traditional thermal CVD processes. Further, in doing so, the invention does not . I

.

SUBSTITUTE SHEET (RULE 26) ~ ~7~57~
wo 95/338G7 --8-- Pcr/[lss the ~.~..r.... ~ of the resulting film layer, and makes efficient use of the activated and reactant gases while reducing gas turbulence at the substrate surface.
The low i , deposition of the present invention is r~ 1 in two altemative methods. The first method utilizes the upstream, remote generation of a plasma. The plasma is pumped dowrl to a substrate by a rotating susceptor and is ~ ' ' as it travels to the substrate, so that '~, activated gas radicals are present. The gas radicals combine with unexcited reactant gases to deposit a film layer on the substrate by CVD
techniques. The pumping of the rotating susceptor minimizes gas particle ,~ ;,~. l.-;j, .~ and collisions to yield a useful percentage of radicals.
The second method utilizes an RF ~I.u. . ' ' design which yields a ' plasma very close to the substrate surface. All of the gases, both plasma and reactant gases, are passed through the RF ~ u.._~h~ii electrode and are excited. Since the susceptor acts as another electrode, the RE~ sl.u.._.l.~d and the susceptor form a parallel plat~ electrode f uf~ 'ig, ~ With the RF electrode method, the plasma gases utilized in the chemical vapor deposition at the substrate contains a miJ.~ture of both ions and sdicals which contribute energy to the surface reaction.
More specifcally, one CVD pro~ess of the preserlt invention utilizes a plasma source to geneste, upstream of a substste wafer, a gas plasma containing various eJfcited particles of the gas, including charged ions and excited, ' radicals, as well as free electrons. The excited particles of the plasma gas, and 1 ' ~,~, the excited radical particles are brought to the surface before they have ha~ a charlce to ~mbine to fûrm neutral mûlecules. The SLI~STITUTE SHEET (RULE 26) 4 5 7 ~
~WO 95/33867 PCT/13594/13641 excited radicals chemically react with one or more reactant gases to form a thin film on a substrate. The excited radicals supply energy to the surface reaction such that CVD may be used in accordance with the principles of the present inventiOn at h r ~ lower than those required with traditional CVD methods.
To prevent the particle sticking and the reduced layer . ' ' ~, associated with traditional PECVD using ionized particles, the upstream method of the present invention utilizes I ' '~",1~ uh~l~ activated radicals at the substrate surface which yield conformal, uniform films. However, the lifetime of such activated gas radicals is short as they seek to recombine into a low energy, stable molecular structure. As mentioned above, the present invention provides efficient use of the activated gas radicals by bringing the radicals to the substrate surface before a significant number of them are able to recombine to form the original, stable gas molecules. For efficient delivery of the radicals, the present invention utilizes a rotahng susceptor which supports and rotates the substrate and creates a downward pumping action in the direction of the substrate. The rotating susceptor pumps the radicals to the substrate surface.
A reactant gas or gases are introduced into the deposition region above the substrate surface to mix with the activated gas radicals. The downward pumping action of the rotating susceptor ! ' ' ly draws the mixture of radicals and reactant gases toward the substrate surface. At the substrate surface, the mixture of radicals and reactant gases flows radially outward from the center of the substrate in a substantially uniform laminar flow pattern and the excited SU8STITUT~E~SlHE!E~T~(R~UILE 26) ~95/33867 2 ~ ~ ~ 4 ~ 7 ~ PCI/IJS9~1136.~1 ' radicais reæt wiLh the redctant gas particles in a surfæe reaction which r3ults in a film layer being deposited upon the substrate surface.
The activated radicals suppiy energy to the surface reaction and ~hereby reduce the required energy, such as thermal energy, that is necessary for the chemical reaction to talce plæe at the substrate surface. Therefore, the deposition takes place at a substantiaily lower t~lllL~ldlUlG than the t~ ~ll~ldLUlG
requirGd by traditional CVD processes. For e~ample, the deposition of a titanium-containing layer using the present invention may be ~ fri at 600C or below versus 1000C for some traditional thermal CVD processes.
The unique pumping ætion and laminar flow of gases created by the rotating susceptor ensures a useful density of radicals at the substrate surface. For e~ample, by using a gas flow of between 500 to 50,000 sccm (standard cubic centimeterS per minute), a susceptor ~otation-rate of~o 1,000 rpm, a reaction ." i;,, r~
chamber pressure between~5 and 10 Tor~, and a reactant gas flow rate between I
to 20 sccm, the present invention has yielded thin fLims from CVD techni~ues at ~ ldLl~lGa below 650C. The upstream plasma may be excited using either an RF signal or a micmwave signal. Accordingly, the invention has been found to yield desirable results when the plasrna is excited at frequencies as high as 2.54 GHz and as low as 13.56 i~Hz.
The larninar pattern created by the roLating suscep~or minimizes gas particle IG~,III,UIdliUIIS and subsequent radical ~ at the substrate surface, and therefore, there are more ætivated radicals available at the substrate surface for the low ~ r CVD process. Additionaily, in the method of tbe present invention, increasing the mtation rate of the susceptor increases tile SUBSTITUTE SHEET (RULE 26) .. . , .. .... . _ _ ... _ 5 7. ~
~WO 95/33867 -11- PCI/US94113641 deposition rate at the substrate surfaoe. Due to the unique C..~ ;n.l of activated radicals and the laminar flow produoed by the pumping action of the rotating susoeptor, the deposition rate of the present invention incr beyond what might be achieved solely due to the increase in molecular reactants at the substrate surfaoe resulting from an increased pumping action. That is, imcreasing the rotation rate of the susceptor a~ ,' ' more than merely drawing reactant gases toward the substrate at a higher rate; it further minimizes ' of radicals thus providing more available radicals at the substrate surface. This in the delivery of radicals to the substrate surfaoe is an important a.l~. in PECVD prooesses. It allows the majority of the radicals formed upstream or remotely from the substrate to be carried to the substrate surface so that they take place in the surface deposition reaction without a large amount of radical ' ~ loss. This; ' and the subsequent increased energy at the surface reaction, in tum, allows the reaction to take plaoe at even lower deposition For the RF electrode plasma generation method of the present invention, the plasma gas is delivered proximate the surfaoe of the substrate utiiizing a gas-dispersing ~llu.. h~ which is biased with RF energy to act as an electrode. A susceptor supporting a substrate acts as another parallel electrode.
The RF showerhead/electrode generates a ~ ' plasma very close to the surfaoe of the substrate while a gas delivery cylinder attached to the ~ h~
ensures uniform gas flow to the plasma. The prw~imity of the plasma to the substrate ensures an ample density of activated radicals and ions for the surfaoe reaction. That is, a: ' of both gas ~adicals and gas ions is utilized in tbe SUi3STiTUTE SHEET ~RULE 26) 2 19~4~7 C.

u.._.l.~/electrode method. Utilizing the ~ v.._.}l~d/electrode~ a spacing of less than 1~ between the generated plasma and the substrate is possible yielding desirable CVD films. r, the RFi i~llu.._~}l~d/electrode method keeps the plasma . ' belûw the ~;~u.. ' ' and clûse to the substrate for efficient deposition. The RF ~hv.._~ ad has been utilized at RF frequencies from 13.56 MEIz to as low as 450 KH~.
While the present invention may be utilized with a number of different plasma gases and reactant gases, the invention has been found to be L '.y useful for depositing tit~nium-containing films, such as pure titanium ~Ti), titanium nitride CliN) and/or titanium silicide (TiSi~ films onto a substrate utili2~ing plasma containing radicals and ions of hydrogen and nitrogen and/or ~' ~ ' titanium . ' ' ' (riCI~) and ammonia (NH3). A diluent such as argon might be mixed with the plasma gas. Further, different plasma gases besides H2, N2 and NH3 might be used in accordance with the principles of the present invention to supply radicals and ions to the surface reaction according to the present invention.
In a specific i b~ ' t, the invention has been found useful for depositing titanium films over aluminum layers on a substrate. Deposition t r ~ in accordance with the invention are low enough that the aluminum layer is not damaged by reflow during the deposition.
In another specific i b~ ' t, the invention has been found useful for producing selective deposition of titanium over a substrate having a field oxide (silicon oxide) layer patterned with vias into a lower silicon layer. Under certain SUBSTITUTE SHEET (RULE 26) ~945~ ~
~wo 95/33867 PcrrlJss4/l364 conditions, it has been found that titanium deposits only on the silicon layers in the vias without sigificant deposition on the field o~ide.
In accordance with various hardware ~ ~ " of the invention, the plasma may be created using energy from various energy sources imcluding microwave and radio frequency (RF) sources. One hardware ~ ~ ~ " utilizes a ~hv.. ~/electrode which is biased with RF energy to create a plasma. One possible upstream plasma: ' ' utilizes a commercially available plasma source with an RF coil ~u~ a pla8ma region. Still another ~...1,l~ ' utilizes an upstream microwave plasma source which remotely excites a plasma with microwave energy. The remote plasma is then pumped along a tube whereby activated radicals are formed. After exiting the tube and entering the deposition chamber, the radicals are mixed with reactant gases and drawn to the substrate surface by the rotating susceptor.
The invention and the particular advantages and features of the present invention will now be described in detail below with reference to tbe P . ~ drawings.
Bri~ De~rr~v~ion of tbe Dra~
Fig. 1 is a side view and partial cross-section of one b~ ' of an upstream pl~.. ; ' ' deposition chamber used to practice the methods of the present invention using microwave energy.
Fig. lA is a view of an altemative ~ b. ' of an upstream p~ n m ~ ~ deposition chamber using microwave energy.

SUBSTITUTE SHEET ~RULE 26) ~v ~y~i ~r~A~ nt~ U;~ ____ ,Y9~ 0 ~O "_ _ 51~3 4~ 6~ +4y 5~J ~ 3~J944~ 5 0 y, " ' ' ' 2~9457'i-Fi~. 2 is a side vsew and partial cross-section of one P ~ orll..,f 1 of deposition chamber used to practice the methods of the psesent invention using an RF showerhead~esectrode.
Fig. 2A is a more detaiied view of the ~ lf~ of Fig. 2.
- Fi~. ~B is asl alterr~a~ e cll~bud.Lll,,~ of the cr~ of Fis,~. 2.
Pig. 3 is a side Yiew and partial Lross-sectiorl of a second J~ of an upssrcatn plasma~nha~ed deposition cslamber using RF
energy.
Figs. 4A and 4B ase Aslherlius funcîion gsapshs of the necessary activ~don esler~y fo~ deposilion without and witsl the upstream activa~ed radicals of the prQen~ invendosl, ~Q~ ,L~.
Fig. S are graphs os~ deposi~on rate increase as a s~unc~ion of ro~tion rate isscrease wi~t and ~itslout the upstreat~ artiva[ed radicals~

I~tt!C~
Fiy. 6 is a ~ Lutv~ u~;.~h showin~ sekctive deposition of ~i anium f~l~s onto vias par~ernerl i~ a silicon oxsde layer overlying a silicosl su~strate.
Dehiled De~s~riDtion o~ th~ In~entson The presetst irlvesldon islcllsdes both ~ethods and A~ for "",~ lo~Y t~ CvD utilizing acdvated gas radicals assd/or acffYated gas radicals Aand iOslS. Proper use of the a~livated iorls alsd radicals, and a resultaslt low r~ CV'D rnethod, requires a useful derlsiry of radicals as /or ions at the substrate surface. A rotatir~ susceptur is us~d in accv.~e with the present islYer~tion vhich totatQs a substrate inside of a dcposition charnber and draws activated gas radicals down to the surface of the substrate. The radicals A~,ENDED SHEET

2 ~ Q ~ 4 5 7 ~WO 95/33867 PCTIUS94/13641 and reactant gases ta'~e pa~;t in a surface reaction on the substrate to deposit a film.
The activated, I,ll~UE,., ' radica'ls and charged ions contribute energy to the surface reaction such that the flm is deposited upon the substrate surface in a chemica'~ vapor tec'nnique at ' "y lower . than are possible with thermal CVD techniques. Also, because the ions and radicals a~;e activated by the plasma, less thermal energy is required to complete the surface reaction.
Prefera'oly, in the upstream plasma generation, r ~ ' ''!~
radica'ls are present at the substrate surface to participate in the low i surface reaction. The laminar gas flow created by the susceptor reduces collisions and tne subsequent ,~ 1 - -';..--- of the activated radicals into stable molecules so that a useful density of the radicals are delivered to the substrate surface to take place in the surface reaction and subsequent film formation. With the RF
Jl,u.._ll.~/electrode method, the plasma may be generated very close to the substrate, as discussed further I ' -' .., thus enhancing the efficient use of the activated ions and radicals. The present invention yields a CVD technique that may be '~rv 1-1;`h~ at very low I . compared with the traditional thermal CVD techniques thus making it practical for integrated circuit fabrication requiring low deposition i r ' ~. r~ VI~ the inventive method achieves improved step coverage and film; ' ' ~ over sputter deposition techniques and other CVD techniques. The invention may be utilized to deposit various different films by a low t~ ul~ CVD; however, it is ,u~ ,ul~uly useful in depositing titanium-containing films such as titanium nitride (TiN) at low and especially pure titanium metal.
SUBSTITUTE SHEET (RULE 26) 2 ~ ~ ~ 4 5 7 ~

Fig. I shows one ~ ,, ' of an upstreain plasma source with a rotating susceptor for practicing the upstream p~ J CVD of the present invention. The . ~ of Fig. 1 utilizes a microwave plasma source for generating an upstreain reactant gas plasma from which the necessary activated radicals are drawn. A reactor 5 includes a chamber housing 10 enclosing a reaction space 12. The housing 10 may be controUably vacuumed to a desired intemal deposition pressure for practicing the invention. Plasma gases to be e~cited, such as, for example, hydrogen gas (H~), nitrogen gas (N2), and/or ammonia (NH3) are introduced into space 12 through a qua}tz tube 14. Plasma tube 14 is ~shaped and has a long portion 16 which extends generally horizontally until it reaches a 90 bend 15. After ahe 90 bend 15, a smaU straight section 18 extends vertically downward and has an ouaet end 19 which opens into space 12.
Housing 10 also contains a rotating susceptor 20 which rotates on a shaft 21 coupled to a motor (not shown), such that the speed of the rotation may be adjusted. Susceptor 20 supporls a substrate 22 in ahe reaction space 10. A
t~ control device (not shown) is coupled to susceptor 20 which is used to heat substrate æ to ahe desired ~ . An example of a suitable reactor, including a rotating susceptor, for practicing the methods of the invention is ahe Rotating Disk Reactor available from Materials Research Corporation (MRC) of Phoenix, Ariwna.
A microwave energy source 24 is coupled to plasma tube 14 alrough a microwave waveguide 26. The waveguide 26 propagates microwave energy 27 from source 24 to tube 14 to define an excitation region 28 within ahe tube 14. Plasma gases a~e introduced into tube 14 at end 13 and tiavel along the SUBSTITUTE SHEET (RULE 26) 4 5 7 ~
~WO 95133867 PCT/US9~/136.11 length of the tube 14 passing through region 28, wherein the microwave energy 22 is absorbed by the gases to excite the gases to form a plasma. The plasma generated in tube 14 contains various activated particles including ions and activated, .,I.~ dl radicals. For example, if hydrogen gas (H2) is introduced into tube 14, a hydrogen plasma containing free electrons (e~), hydrogen ions (H+) and ,h~,~ 1, activated hydrogen radicals (H*) is produced, while nitrogen gas (N2) yields electrons, nitrogen ions (N-) and activated radicals (N*). Ammonia gas (NH3) might also be utilized to produce radicals of hydrogen H* and nitrogen N*. However, as discussed in greater detail below, NH3 reacts with some reactant gases, such as (TiCI~), to form an undesired adduct. Therefore, preferably pure H2 and/or N2 are excited and utilized to achieve low ~ CVD.
Utilizing hydrogen (H2) as the plasma gas, generation of the plasma results in generation of radicals H* as well as ionization as follows:
Hl -- 2H+ + 2e~ ~lonization) (EQI) As the excited gas plasma travels along the horizontal section of tube 34, ' ~ occurs according to equation 2 below as the plasma is, and additional hydrogen radicals H~ are created through a ~ ' of hydrogen ions and free electrons.
H+ + e- -- H' (~ n) (EQ2) As time progresses, a second ,~ may occur according to equation 3. The second 1~ ;"" yields inactive, stable hydrogen gas molecules which will not contribute reaction energy to the surface reaction.

SUBSTITUTE SHEET (RULE 26) ~9~57 2, WO 9~133867 PCTIUS9~1136 Tberefore, it is important to deliver the activated radicals to a surface 23 of substrate 22 before they recombine.
H~ + H~ -- H~ (EQ3) The hydrogen radicals Hi~ and any other remaining gas particles of the plasma travel around the 90 bend 15 of the tube 14 and are drawn ~' n...~Jly along vertical section 18 and out into the reaction space 12 through outlet 19 by the rotation of susceptor 20. Rotating susceptor 20 generates a downward pumping action in the direction of substrate 22. The pumping action creates a laminar flow of gases over the wafer surface 23 as illustrated by arrows 29.
Preferably, susceptor 20 is operated to achieve matched gas flow conditions. In a matched gas flow, the rate of gas flow in a downward direction indicated by Q-l equals the rate of gas flow in a horizontal direction designated by Q-2. When these two gas flow rates are equal, matched flow occurs. An additional discussion of matched flow is disclosed in the pending application entitled "A Method For Chemical Vapor Deposition Of Titanium-Nitride Films At Low T, ~ r~ 7 Serial No. 08/131,900, filed October 5, 1993, which application is I ' herein by reference.
For an efficient CVD reaction according to the principles of the present invention, it is desirable that the plasma gas reaching the substrate 22 contain a large percentage of radicals, and preferably 80% or more activated radicals by, -",~ Such a high radical ~'Jl ~ II requires drawing the plasma gas down to the substrate 22 with minimal .~.,."l.: -ti.",~ Ma~imum utilization of radicals is ~ ~~ .' ' ' by the laminar flow created by the rotating SUBSTITUTE SHEET (RULE 26) 4 5 7 ~
~VO 95r33867 PCT/IIS94113641 susceptor 20. It has been determined through ~ ;.. that the laminar flow pattem of the susceptor 20 minimizes the, t ;, ~ o of the gas reactants and ~uLi~,ulall~ minimizes IC~,;l.,UIdliUll of the activated gas radicals at the substrate surface 23. The minimized in turn, minimizes gas pha~e collisions of the activated radicals, and hence, reduces the rate at which the radicals recombine to form stable molecules. That is, the amount of of H* into H2 according to equation 3 above is reduced. As a result, there is a greater density of useful activated radicals available at the substrate surface 23 to supply energy to the chemical surface reaction and to reduce the thermal energy required in the chemical vapor deposition of the film.
Thereby, the present invention effectively reduces the deposition When gas radicals are introduced into space 12, the reactant ga~es are introduced such as through a vertically adjustable ~LU.._.II.,dd 30 shown in Fig. 1. For example, to deposit a titanium-containing film, a titanium tetrahalide gas such as titanium t~ rh1nn~l~ (TiC14), titanium t~lldblullud~ (TiBr,), or titanium tetraiodide (Til,), and preferably TiC14, is ihlLI. ' ' For a pure titanium layer, H2 might be excited into a plasma and TiCI4 might be introduced into the reaction space 12. A mixture of H# and TiC3~ might then occur in space 12 generally above susceptor 20 and substrate 22. The pumping action of susceptor 20 would draw the mixture down to substrate surface 23 in a laminar flow and the activated H* and TiCI~ should react at surface 23 to deposit a thin film on the substrate 22. Hydrogen radicals Hi' should supply energy to the surface reaction according to equation 4.
4H~ + TiCL~ Ti + 4HCI (EQ4) SUeSTlTUTE SHEET ~RULE 26) 2 ~ ~ ~ 4 ~
Wo gsl33867 PCrNSg411364 The reaction should yield a film of titanium Crl) upon the substrate surface 23 and l~ acid (HCI) which might be removed through the appropriate exhaust port 32. The energy contributed to the reaction of equation 4 by the activated radicals should achieve a CVD filrn at reduced deposition i . ' While the example of the invention described l..le.r.~vvc might yield a layer of pure titanium upon the substrate 22, various other rnaterial layers might also be deposited according to the principles of the present invention containing titanium or contau~ing other desirable elements. For example, titanium nitride (TiN) might be deposited by ...l-~ ' hydrogen (H2) and nitrogen (N2) into the r3r~ ~ , tube 14 to yield HY and N* radicals. Further, ammonia gas (NH3) may be excited and ~' -- ' into a plasma containing H*
amd N* radicals. Similar to the . c~ ;- - of the hydrogen gas plasma particles, the NY radicals will eventuaUy combine into nitrogen molecules (N2) unless quicldy drawn down to the surface of the substrate 23. As a fur~her example, titanium silicide CliSi2) might also be deposited according to the principles of the present invention. In such a case, silane gas (SiH~) might be introduced with the titanium-containing gas (e.g. TiCL,) into the reaction space 12.
Additionally, tungsten (W) may be deposited using the apparatus of Fig. l and the method described. E~amples of chemical reactions for producing titanium nitride and titanium silicide are given below in equations 5 and 6, ~
TiCI4 + N* + 4H* -- TiN + 4HCI (EQ5) TiCI, + 2SiH~ + 4H* -- TiSi2 + 4HCI + 4H~ (EQ6) SU~STITUTE SHEET ~RULE 26) 2 ~45~
~WO 95/33867 -2 1- PCT/lJSg4/13641 The microwave plasma deposition apparatus of Fig. 1 waD used to deposit a layer of tungsten and several tests were made to determine the viability of the method. Hydrogen was passed through quartz tube 14. An e~ccited plasma was ignited in the vicinity of region 28 and travelled du..,.Dtl through tube 14 into reaction space 12. As the plasma travelled along quartz tube 14, it was ' ' du....D,i~ of the microwave excitation region 28 indicating that of the excited plasma particles had occurred, such as according to equation 2 above to yield additional hydrogen radicals. The hydrogen radicals were ' . '~, drawn down to substrate surface 23 by rotating susceptor 20.
, tungsten k n .. ~ (WF6) was introduced through a gas port 29. A deposition reaction occurred according to Equation 7, below, to deposit a layer of tungsten onto substrate 22.
WF6 + 6H* -- W + 6HF (EQ7) To verify that hydrogen radicals were actually reaching the substrate surface 23 and . b~ ~ to the CVD process, an activation energy ~
was made. Specifically, the tungsten deposition rate was measured as a function of substrate l r ' C. The III~DUI~ ' were made both with the microwave power turned off and no plasma and with the microwave power turned on to create a plasma and hydrogen radicals. The data measured is shown plotted in Figs. 4A
and 4B as a l~lgl~ntl-~ir Arrhenius function, i.e., plotted as In (k) versus 1/T, where lc is the reaction rate constant and T is absolute i , c:. The process SU~STITUTE SHEET ~RULE 26) A ~ JJ~ 3 a ~Q1457 ~

and deposition parameters for both the non-plasma and plasma depositions illustrated by Figs. 4A and 4B, ~ y, were as follows:

H~ rate = 2,000 sccm WFD rate = 225 sccm Pressure =l~ Torr) ~ ~ -Rotation rate of susceptor = 30 RPM
A Microwave Power = 900 Watts From the experiments, and the resulting Arrhenius functions, the activation energy, ED. was calculated. Fig. 4A is a plot of the activa[ion energy for tungsten (W) deposition without a plasma, while Fig. 4B is an activation energy plot with a micro~vave piasma. For the thermal process, ti~at is, with the microwave power rurned off, E~ = 67.1 kJ/mole-degree K However, when the microwave power was tumed on to create a plasma, the activation energy necessary for the deposition proccss was oniy ED = 63.2 k:~/mole-degree K The decrease in activation energy ED between the plasma and non-plasma deposition processcs, indicates that activated hydrogen radicals are reaching the substrate surface and ~Jdl~ JdLillg in the surface re~ction according to the principles of the present inYention. The decreased activation energy necessary when utilizing the activated radicals results in a decrease in the deposition ~ dLUL~ necessary for the CVD process. As discussed above, a lower deposition tC~llpCIdlulc is desirable for integrated circuit fabrication of temperature-sensitive circuits requiring deposition Lelll!1C~d~UI~ below 650'C.
The deposition rate of nungsten was also plotted as a function of the susceptor rotation rate or substrate rotation rate. Fig. S illustrates that the deposition rate for the thermal process increased with increasing rotation. rate as expected. This is due to the fact that the molecular reactants are being pumped to ~ L_~ ' v i --- . ~ lj ,j~ . ij,._i -__-_i,_ ~ 'bL-I_ ~r~Li L~V ~ 44i 5~

3 4 ~ 7 the rotatirlg substrate surface at a higher rate. However, f~r the upstrea~ radicai assisted pr~3cess of the present iriYention, the deposition rate increased much more dratnatically as the rotalion rate increased. That is, ther~ is an effect beyond the basic pumping of reactants caused by the r~3tating substrate which produces the increase~ deposi~ion rate. With the upstrearn plasr~a ~ethod of the present invention, it was d~tertnir.ed that the larlir~ar gas flow pattern proYided by the rotatirlg susceptor rnir~imizes the gas phase collisiorls, and thus riP~uces the rate at which the necessar,Y activat~d hydrogen radicals H~ recombine to f~rm hydrogen molecules H1. The efficient d~liver,Y o~ radicals to the substr te s rface in the upstrearn method ef the pr sen~ inYenticn is ar~ important . ~.3i~3~ ,u, in plastna-er.hanced CVD. A majoriy of the actiYateCi radicals are canied to t3le substrate su3rfac~3 to ta'~e place irl ti~ sudace depositio~ reacIion. Therefore, not en~y do the activated radicals contri~ute energy ar3d lower the ~epo5ition 1 , but also the hi~h der~sity of radi~als d~ivere3d to t~e substrate by the larninar gas flow of suscep~or 2~ further r~duces the de?ositiorl t~ dtulc below the i.~ c~i,,~lly iigh ~ of thennal CVD ,~ni~ c Fig. lA shows arl alternatlYe CY~3 Ci~ which utilizes ar3 upstream Illil~LUn~ , source to generate actiYated gas 3adicals. ~ reactor 100 irlcludes ~ chamier housing 10~ erlclosing reactio3l space 104. Li3~e teacwr 5 of Fig. 1, ~e ~ousir3g may be controlla~31y vacuurn~d to a desired ~nterl~al depositior pre sure. Plas~a gases are iD31rOdUCed in~ a vert~3cal quart2 tube 106. A
microwaYe wave ~ide strucPlre 108 is coup~ed to tluar~z tube 106. Wave guid~
structure 10~ in~iudes a hor~ontal section 110 which includ~s a r~icr~wave sourc~
11~. An an~led waveguide section 114 cormects borizo~al section 110 to t ~.~END.~ SEiEET

2~'I4gi7 ~ ~

~ertical waveguidc seclior~ 116. Quartz Nbe 106 ex~ends through an opening ~not shown~ in rhe angled section 114 and extends throu~h section 114 and vertical section 116 whcreupon it ~tends through a top cover plate lS of housing 102.
Quart~ tube I06 extends throu~h p~ate 118 and tcrminat~s at an outlct erld 120 abo~e a-g~s dispersing ~IIU~ LC~d 12 Showerhead 122 is attached co a quartz inswlasor ring 124 which connecrs rhe ~ 122 to the cover 115 of reactor housing 102. Also dispot;ed abo~e ~1..J.._.~ læ and adjaccn~ the outlet end 120 of quare tube 106 is a reactanr ~as L]alo or dispersion rin~ 128 which has a pluralit)~ of openings for dispersing reactant gas. A source line 130 is connc~red to ring 128 for deliver~ing a reactant gas such as T;CIIL to the ring 12~.
The micrawave source 112 within waYe guide section 110 r~ay be a magne~n or a~y olher suitablc sourc~ whir h generates en~rgy ar rnicrowave r,. ~ s For exaI:~pl~, a coaxial waveguide adap~er (nat shown~ mi~ht ~e attached onto one end of horizontal wavegu~de section 110 ~o ~erlerate the necessary microwavc energy.
~ e upstr~ar~ microwave plasma soutce and r~eactor 100 of Fig. lA
operales somewh2t sim~larly to reacwr 5 in Fi~. 1. That is, a plasma ~2s sr~h as ~ydroge~, nitrogen andlor ammor~i2 is irltroduced in~o quar~z tube 106 and travels along the qua~z tube 106 and through the microwave wa~eguidr~ suucture 108 such that the gases are excitcd into a plasma withirl a section or area of tul:e 10~.
A routin~ susceptor 132 supports a rubstrate I34 below slw.. .l.~ad 122 and halo 128. Si~ilar to the rotating susceptor of Fig. 1, suscc-ptor 132 is coupled to a C contro~ devtce (not showrl1 wbich hears substrate 134 to a dcsire~' r' `''1'~ Ulc7 susceptor 13~ is coupl~d by sha~t 134 to a motor (not AA~ENC,CD SHEET

~ "399446.r~: R I :~
a ~19~457 ~i shown) such that the r~tatian of susceptor 132 may bc set as desired. The rotaring susceptor pumps the activated radicais from erld 120 of quartz tu'oe 106 arld from reactan~ gas from ring 128 through ~I.u~._Ll.e~i 122 ~o rcact and deposit a filrn layer onîo substrate 134. Preferably, the majoriy of activaoed plasrna particks reaching substrate 134 ar~ activated radica~s which contribute ~ncrgy ~o the surface reaclion to acilieve low ~ e CYD. The remainirl~ narl-utili~ed gases are exhaustcd through an exhaust port 138 While the laminar gas flow of a rotatirlg susceptor in :,,."I.. ,~;.,~\
with an upstream plasrLa source yieids desirab~e radicai densities, a mcrhod of low ~Clalulc CVD of litar~ m has also beerl achieved using a gas dispcrsing ~llU ~.h~i biased as arl RF ekctrode in order ta gcncrate a plasma of iorls and radicals closc ~o the substratc such that bo~h iorls and radicais comribute to thc iow t~ .I, wrface reactions. AccordiLgly, Fig. 2 shows a prcferred ~ "I.u.~
o~ a CVD reactor for achieYi~g low ~ A~ C deposi~ion using acdvared ra~icais and iorLs in ~ornl*~nrr with the principles of ~e prese~t invention. Refcrr,ng to Fig. 2, the r~actor 40 includes a dcposition chamber housing 42 and housin~ cover 43 which d~fincs a reaaion space 44. E~ousi~g 4~ also encloses a rotatirlg susceplor 46 which supports a substrate 48 in spac~ 44. Sirnilar to the reac~or of Fig. 1, reactor 40 rnay be selecdYely cYacuated ~o various dif~cr~rlt internai pressures~ whiie susceptor 46 is coupled ~o adjustable heat and rotational colltrols ~or heating a~ MUtirlg substrate 48 at various 1~."~ and speeds, Exteuding dowrlwardly from the ~op of housing 42 is a cylinder assembly 50 which is attached to a ~Lo~ ~d 52. Showerhead 5~ ~s suspen~d ~E~'.D S~EET

2 ~ ~ ~ 4 ~ ~ -above subsrrate 48. The gases ~o be excited into a plasma are introduced through a gas injection ring 54 into cylinder assembly 50 through a plurality of ring holes 56. Ring 54 is coMected to a plasma gas supply by line 55. Showerhead 52 is coupled to an RF power source 57 by feedline assemb~y 58 which extends through cylinder assembly 50 to allu..~ d~ 52. Cylinder assembly includes a cylinder 51, and insulator ring 60 which separates cylinder 51 and allu..~ d~ 52 for reasons discussed IICL~;IIb~h~W~ Irl one embodiment of the reactor 40, cylinder 51 is electrically grounded. The RF energy biases showerhead/electrode 52 so that it acts as an electrode and has an associated RF field. Showerheadlelectrode 52 is preferably dyylù~illldtely~l~o 2s inche~ thick and contains approximately 300-600 dispersion holes 62. The gases introduced through plasma gas injection ring 54 flow downwardly in cylinder 51. ~he RF field created by the biased ~I.u.._ll. dd/electrode 52 excites the gases so that a plasma is created be~ow the lower surface 53 of ~IIu~.ll-dd/electrode 52. Preferably, the showerhead dispersion holes 62 are .~ ,c;"l~ I somewhat smaller than the gas dispersion holes of traditional gas allO~._lllcdds to preYent creation of a plasma in the holes 62 which results in deposition in the holes and subsequent bUllllJdldlll~ of the substrate 48. F~LIIcl~-ule, the smaller holes 62 of the showerhead 52 prevent formatiorl of a plasma above ~l~u.._.ll~ld 52 inside of cylinder 51 thus ;"~ the plasma below ~I-u~ i/electrode 52 and close to substrate 48.
The allu.. ' 1 holes 62~ in a preferred rlllllO.I""~ ,I, are ~ . n~ l to be dyy., ~ 'yl~/32 of an inch) wide. Cylinder 51 preferably has the same diameter as ~llu.._ll.cd~/electrode 52 to spread the plasma and reactant gases over the entire allu.. I.cdd 52.

. . _ . . _ . , ., _ _ _ .

2 ~ , 7 C

The reactant gases. such as TiCI, are introduced through a ring 66 which is generally concentric with ring 54 and is coMected to a reactant gas source by line 64. The gas flow from injector rings 54 and 66 develops within the length of the cylinder 51 as the gases travel to the ~I~u..~ dl/electrode 52.
Utilizing the rotating susceptor 46, the cylinder S l. and ~I~u .. _ll~ /elec~rode 52.
it is preferable for the velocity p~ofile of the incoming plasma gases passing hrough ~llu.._l;lca~ 52 to be fully developed before it reaches the rotating ~ 3 ~
substrate 48. The sllu.. lll~âd/electrode 52 is spaced betwee~.25 to 4 inches) from the substrate 48 tû ensure that the plasma is close to the substrate 48.
Preferably, the spacing is under,~,(1 inch¦ and in a preferred ~Illbo~illl..l~ is ~,u,uluAillld~cly 20 millim.~n ~ As the gases pass through the ~llu.._~ a~/electrode 52, the pressure drop across the :~;IU~ d/electrode 52 flattens out the velocityprofile of the gases. That is. the gas tends to have the same velocity at the center of tbe ~IIù..~ di/electrode 52 as around the periphery, This is desirable for uniform deposition of a film on substrate surface 49. The plasma gases pass through showerhead/electrode 52 and are excited into a plasma proximate the bottom side 53 of ~llu.._lllcdd/electrode 52. As mentioned above, it has been found tbat an RF plasma may be excited with RF erlergy as low as 450 KHz and as high as 13.56 MHz and the invention does not seem to be ~ Liuul frequency sensitive.
If susceptor 46 is rotated with the deposition ~ JI~ of Fig, 2, the pumping effect of the rotating susceptor 46 takes place below the ~IIU ~ ,d/electrûde 52. In the ~lllUOdill~ll~ of the present invention as shown in Fig. 2, the unique use of ~llu.._lllc,~J/electrode 52 in very close proximiry to . . ., .. _ ., .. . _ , .. .

2 ~ 7~

substrate 4g produces a concentraled plasma with a large density of useful gas radicals and ions proximate the substrate surface 49. With the RF
~IIu.._.I.f d~/electrode ~ of Fig. 2, it has been discûvered that there does not seem to be a noticable r"~ f "~ ~1 gained in rotating the susceptor 46 faster than dL~LJlV~illldL~iy 100 rpm. It was also found, howeYer, that a rotation rate of 0 rpm, although not drastically affecting the deposition rdte, lowers the uniformity of the reactant and plasma gas flow and the s~lhsf~fl~lPnt deposition.
Generally, a substrate rotation rate between 0 and 2,000 rpm might be utilized with the deposition . o~ utilizing an RF ~llu~ l,.,dd/electrode.
As illustra~ed further ll.~ f, a susceptor rotation rate of dlJIJlu~ ldt~ly 100 rpm has proven ~o be sufhcient for deposition. While it is preferable to utilize only radicals in the upstream plasma generation merhods, both radicals and ions are present during the deposition using RF ~llu~ ,df'electrode 52. That is, both ions and radicals supply energy to the surface reaction While it is generally not desirdble to use only ions due to their tendency to stick to contact and via surfaces and produce non-conformal films, some ion ~ù~llbd~d~ lt of the substrate 4g is beneficial because it supplies additional energy to the growing film layer on the surface 49 of the substrate 48. However, too much ion bulllb~ L
of substrate 48 may damage the integrated circuit devices of the substrate 48 and may lead to poor film conFormaliy. ThereFore, the deposition parameters and showerhead spacing are choserl as illustrdted herein to achieve a useful mixture of radicals and ions. As discussed above, for the ~ lf ll of Fig. 2, the spacing ~ _5~~~
is und~(l inch)and preferably d~J~lU~ ly 20mm.

If:C~. ~oPl:EPA~ C~ ; Ll~ 9Li: 20:''U, _ ~ bll3 4"1 f'~L;9-- +43 ~9 '>:3994~L;~ 7 1 4 5 7~ ~

T~e reactant gases, 6uch as TiCI~, Pre i~troduced ~nto cylinder 51 through anothe~ gas rin~, 66. The reactant gases travel dow~ the length of cyl~nder 51 and are also excited by the RF field created by 51lu..~ d/eleclrode 52, as they pass through the operf~llgs 62 of shu.. .h ~i 52. The reactan~ gas travels to the surface of substrate 48 along witb the radicals and ~orls of th~ excited plasma.
~he radicals. ions and ~ci~ed reactant gas particles react at the surface of substrate 48 to de~osit a fiim such as a titani~ contain3ng fllm, upon substrate

4~.
Because of the L~lose spacing of the .I~.. .l.c~d~elec~ode 52 from substrate 48 ir~ witE~ cyiirlder ~1, the gas rni~uTe ~ rntin-c 6~
ernana~ing from sE~owerhead 52 are close to the substrate 48 to p~vide efflcient deposition ar~d r~duce the arnount of S~as mixture wbich oypasses tile substrate d,8.
lhat is, t~e boundary layer of gas7 which is defuteLi as the volume or space below the gas ~ 65 which is stagnL~ or ~on-moving with respect to the susL eptor 46, is very small. Th~refore, a large percenrage of th~ radicals, ions i reactant gas par~icles are being utilizeLi in the surface r~action, and au,u.d...t~l~, the efficiency of th~ Cvr~ process anLI rhe d~position rate are increased.
Witn tbe ~L.u.. ~;~l/electrode S2 æling as ar~ electrode, a mOre uniform plasTna ir. ger~erated at substrate 48, tberefore enhanciTIg the uniformity of raLiicai a3~d ion densiy at the substrate 48 and the unifo3mity of the deposited film.
~n the RF ~lu,..~ electrode ~ rl_ - of Fi~s. 2, 2A and 2B the d~posit30n ra~e r~aches a ma~imum when rhe ~otation r~te ls rnatched to the ~lEi~E~ SH~ET

~ . . t~ A~ ~HL~ -~--u- L~ ~ ~3~1~44.1j.5 ~
2 ~ 5 7 ~irlcoming plaslna Llnd r~actatl~ ~s flow. i.e.. matched 8aS flow. Acccrlingly, it is desi~able to acl~ievo ma~ched flow when susceptor 46 rotates.
Fig. 2A discloses an RF ~I.u.. .ll~e~ecnode ~n,,~ sirnilar to the ~ of Fig. 2 e~cept in greater detail. Wberever possible sirLIilar ~eferenc~ r~nerals wi~l be utilized bet~veen Fi~s. 2 and 2A. Ihe ~ JU of Fig. 2A is similar to a strucrure disclosed within pending U. S. pater~ ~pF~ir~tion Serial No. 08/166,745 ~he disclosure of which is fully i~cuLIJul~led herein by r!ferer~ce.
In Fig. 2A, ~her~ is shol~m in break-away a por~ion of CV~
deposition ch Tnber housing 42, to which is mounted the RF sbowerheadlelectrode appara~us 1~2 used to practice the low ~ r deposition of the pres~tL~
invention. It will be app}eciated by persons ski}led in the art that certaiD feamres to be desc~ibed may pertain to orle or more~ but less than all. ~ b~~ of the iDvention. In Fig. 2A, tbe ~ILu..~ i/electrode S2 includes an RF linc s~eLn 144 mourlted there~o. As will bc discussed in nlrther d~tail, tbe RF lis~e stem 144 is one of several ...."~ making up ~e RF feedline assembly 58. llle feedliDe assembly 58 ~Iso acts as a heat pipe to ~ûndllc~ heat away frorn ~Lu.. ,l e~llekc~rode 52 as is also discussed further L.,~ 'vw. Preferably, line stem 144 is ~nachined ~"",~ lly into and is integral wi~h upper surface 146 of showerhead/electrode 52 to increase ~he RF signal contu~tion and heat c~n~ n cff}ciency. RF lirle 148 c~mprises lir~ stem 144 d an additional length of mbirle 150 welded the~eto to achieve the d~sired û~rerall length of the RF line 148 ~e weld is ~ at 149. Preferablv, ~llu.._~ d/elecr~odc 52 and integral line stem 144 are madc of Nickel-200, while RF lirle tubing 1~0 is made of a highly ~lEi l~'3 S~ T

2 ~ 9 11 b~ ~ 7 ~ -conductive ma[erial such as 6061-T6 aluminum However, it will be appreciated by persons skilled in the ~rt that other materials can be used for the RF Line 150, such as nickel 200. In one embodiment, the RF line 148 is made of aluminum coated wi~h nickel to prevent an RF plasma from forming within said cylinder 51 of the cylinder assembly 50 during the plasma-enhanced CVD reactions of the present invention. Preferably, the allu~ cd i/electrode is approximatelyl(O 25 inches)thick.
Showerhead/electrode 52 is perforated with a pattern of gas dispersion holes 62 to distribute ~he reactant and plasma gdses evenly during CVD
processing. .~s shown in Fig. 2A, upstdnding RF line stem 144 is provided with a ui~ul~lrtl~llLidl shoulder flange 152 adjacent and pardllel to showerhead/electrode 52. The flange 152 is spaced above allu~ l/electrode upper surfdce 146 and perrnits the gas dispersion hole pattern to extend beneath the shoulder flange 152, thereby Illi~l;llli~illU gas flow disrurbances. FUILI~IIIIVIC~ the flange 152 aids in the conduction of the RF energy along line 148 to showerhedd/electrode 52, assists in cooling allu.~.,lll,,d:i/electrode 52, and provides mechanical support for ceramic isolator tubes 154, 156. An alterndtive ~I'lo~ " of the showerhead electrode C~ UIAIj..l~ elimindtes the flange 152 as shown in Fig. 2B.
The RF al~u~ ~i/electrode apparatus 142 of Fig. 2A further includes first and second ceramic isolator tubes 154, 156, IcaLJC~Li~ly, which are concentric with and surround at ~east a portion of RF line 148. As shown, ceramic isolator tubes 154, 156 are supported by ,ilcuullrclcllLidl shoulder flange 152. Tubes 154, 156 are preferably forrned of alumind (99 7% Al2O3) which is reddily commercially available such as from Coors Ceramics of Golden, Colorado.

_ _ . _, . , . _, , ., . , . .. ., .... , .. ... . ...... , ,, .. , .. . . _ _ , . . . .

r .VOI~:EPA~ E:`IC~ 1_03 ,__ :,79-1'7-95: 20 "4 . ~ 3 4_1 7')1;9 +49 89 23'.39446~i 7"(l . 2~4~7~
-~2 -One functiorl Oe thcse Isolator tubes 154, 156 Is to preven~ RF plasraa f}om forr~ around the ~F line 148 during CVr~ processing by isolating ~he R~ e 148 from the plasr~a arld reactant gases in t~e cylinder assel4bly 50. As rnay be ap~reciate~, it is desirable to preYerlt the formation of any plasrla within thecylin~er assembly 50 in order to .UIl~.d~ the plasrna below ~u.. ' - - '/electrode 52. 'rherefore, tne isolator rubes lS4, 156 operate ~o prev~nt the formation of such a plasma inside of the cylinder asscmbly 50.
Additionally, ard as described more ~lly below, the isolator tubes 154, 15~ aid in preYcnting elcc;rical shor~in~ oetween gas dtstributor cover 158 (which is at ~round poteraial) and RF line 148 at tne locatiorl whete RF li~e 148 passes through ~s distribu~or coYer 158. Gas dis[rib~or cos~er 158 is mounted ~o housing 42 by mcalls of a plurality of 5crews 150. As shown in the Fi~. ZA, gas irijection rirlgs or halos such as rings 54, 66 (shown in phantom~ are loca~ed slightly below gas disrr;~,utor coYcr 158 and supply the CVD ~eactlor~ and plasrna gases ~o the inside o~ cylintcr asscr~bly 50. Gas injection n~lgs 54~ 66 tray betwo o~ a pluraliy of concentric tin~s ~o~ iul.~.~uci~ nurlcrous ~eachnt ~as3.
A seal preYents vacuum Ical~s at the location where RF line 148 passes through gas distr~butor coYer 158. ~his is ~ d by means o~ a shaft 5cal and a flan~e s~al. As shown irl t~e Figurc 2A, a cerarnic sc 1 plate 160 is prcssed dow~ v'ly by two stainless stcel clamps 162. Clarnps 162 are bias~
agamst distributor coYer 158 by spri~ h~ lCw assemblies 164 to obtain a r~ dow~wrrd force orl d~e seal c,~ . ."~ to illsure proper seali~g, to n..lr tolcranc~ staclcs in thc scal ~UI~IIJVU~ and to ~aEce up ,1.".. .~
cha~g3 due ~o therrnal expansion which rnay occur during C~ /L' ~, S~al ~,E~5E~ S'n~T

liY~-.S'ON:EPA-blUh'`iCilFN 03 :29~ 5 ~ 51;3 4'>1 7~6~ +49 8Y '~399446F:~
a ~

plate 160 presses downwardly on a stainless s~eel ferrule 166 which in null presses down on an 0-ring I68 seate~t in ceramic seat body 170. The dcwnward ~otce cxcrted ~y clamps 162 on seal plate 160 also fotces seal body 170 ivwl~ 31~11y against gas dist~ibutor cover 158, which compresses ttle O-rinE 172 located betweer. seal body 170 and gas distri~utor cover 158. It should be noted t~t seal body 1~0 tlas a d~,~u aldly exterldin~ a~ular llange 114 which surroullds Rl~ tine 148 over the ~ntirc lerlg~h of i~ whjch passes through ~as disuibutor coYer 158.The lower end 176 of armular flange 174 cxte~ds doY~nWardly to a poi ~ where i~
meets c~ramic isola~or tube 154. ~.s shown, the outer c~ratnic isolator tube 156~xtends further upward than isolator ~be 154, such tha~ there is rlo direct linebetween gas distribu~or coYer 158 and R~ line 148. This prcve~ts atcirlg ~vhen the I~F line 148 is used to power ~ Ielcc~de 52.
T~c ~F line 148 a~so fu3lcticrLs as a hcat pipe stlucture. Wi~
respect to hea~ pipe struc~ur~s, such dcYic~s arc Imown ~er se, and iri the preserlt inYention, the heat pipe str~cture is used to Carr,Y off heat frorn the ,ho.. ' '~electrode 52 gcnerated ~y Mdiarlt energy from the heated suscep~or 46, as well as by the RF ener~ applicd to the ~l,o.. ' ~J~ .v~c. The c~rlîer space 178 of RF line 148 is proYided wit~ a felt or other suitable capillary wic~ing material liner ~rLot shown). Space 178 is scaled with a liquid (e.g., ace~rle) thereirl undtr i~s own vapor pressure that ent~rs the pores of the capillaty material wetti~g all intetnal surfaces of RF lit~e I48. By appl,Y~ng heat at ar~ point along the leng~ of the RF lirle, the liSuid at that pOint boils and e~crs a Yapor s~ate.
When that ~apperls, ~he li~uid in the wicking material picks up rhe later~t heat of "~1~'' ;'~1;- '1. a~d the va~or, which therL is at a hi~er pressure, moYes insidc the A~,E~D'~ S'.~'~T

~C~.VC~ PA-~lUF.NCHE:'l oa ~9-12-95 70:25 . ~ 3 4''1 ~369~ +~9 89 2:3~35~4*81;.11~
2 ~

sealed pip~ to a cooler iocation where it condenses and re-enters the lin~r. Thus, the vapo~ giYes up its latent heat of ~ l and moves heat from the ~inpu~"
to the "output' end af the heat pipe structure. As a genera3 frrltne of referenc~, heat rnay be movt~d along a h~at pip~ at a Mte of A~ O~ t !y SOO mph.
With reference ~o the speeific ~,,.,r;~.,.~ri,", utiiized in Fl~. 2A, the "Irlput~ end af t~e heat pipe structure is the end u,hich ~s aff~ed to ~L~ ~felectrode ~2. The 'output" erld is the upper end shawn in the Fig. 2A
which has a liquid-cooling jacket 180 sealed r~round it. The seal is ~ffectcd by O-ring shaft seals I82 arld 183. Cooling jacket 180 is preferab~y a polymetie rnaterial and is pravided with TEFLON ~ fittings 184 and lg5 whieh COnnect 'rE~ LON tubing 1~6 to coolirlg ~acket 180. A suitable cooling liquid.
such as water, flows through tubing 186 and coolin~ Jacket 180 to catry heat away frarn RF line 148. This pemlits dir~et contac~ of the cooling liquid wirh the lU:
line 118 for efficient canduetiotl of heat from tbe line i48. ~dditionally, with this .,..r~ ...AI;..,l at nO tirne is the CVD reaeror ch~nber exposed to the possibility of r~ internal eoolant ~eak, nor is there any c~trosive effect ot~ metal tubing ~y RF
earrying liquid. As sta~ed, t31e fluid which passes throu~h TEFLON tubing 186 and earries the heat a~ay fr~m the RF line 148 rnay b~ ~ater, althou~h a variey of fluids can be ~sed depending on the heal to be condueted away from the lin~
148. RF line ~48 also includes a cap 188 which is we3ded irl piace and 31as a fill tub~ 190 for Flling the inr~rnal space 178 with the desired fl~ud. A snitable e.~nm~i~lly availaele heat pipe may be oblamed from Th~rmocore Inc., of Lancaster, PA.

A~Ei~aEa Sl l~:ET

~EY.YO~i:EPA-~!l,'ENCi~' oa :28-12~ : 2Q:25 . _ 5la 4 ~ 6~ ~,L9 8~3 "3994_.~;5 .~"a L

As shown in Fig. 2A, an alur~unum cylinder 51 is u~ilized ~o var~Y
the shu..~ d/e~ectrode substrate spacing(s). S11V.._.I...aCUeL~ILVdL 52 is fsstened to cylin~er 51 by ~neans of screws 192, whtch are preferabLy ~nade of a material tha~ does not corrode in t~e prese~ce of an RE~ plasrna. One such material is Hastelloy C-22, which Ls a tradç name of Halles Tntrm~ri~n~l of Kokoma. IN Suitable screws made of this material arç available from Pinnacle Mfg. of Tempe. A~. Quari2 rin3 60 elsctrica~ly isolares all...._.;.~/electrL~de 52 from alumirtum cylinder 51. A suiabls quaiiry quartz for ring 60 is Quare TO8-;E
available fron~ Hereaus Amersil in Tempe. Arizona. Screws 1,2, which are at ~round pokntial, are isola~ed from the ;,ho~._.h~ l.u~ 52 by ~ vo ;~,t~ ceramic isolator sleeves 194 and 196. Q~L~tz is used for isolator ring 60 bçcause of its si~nificant resistanc~ ~o thern~l shock. This can be imporra~t sir,c~ the RF sho.. ' '~electrode 5~ below qUartz ring 60 becornes heated t~ a higher i ~ . and more rapidly rhan aluminum cylinder S1 above quart~ ri~
60, th~s inducing thermal shock and stress in ring 60. Screws 198, which inay be raade of the same maurial as screws 1~2, are utiliz~d to at~ aluminum cylinder S1 to housin~ 4~. As disc~ssed above, various length cylinders 51 migh; be Utiii2ed to vary the showerhead/eleetrode to-substrat~ spacing. It ~s preferable ~hat the length of cylinder 51 be chosen to position showerhead/electr~de 52 ~ithin 1 inch of susceptor 46.
RF energy is conducted to ~ .h~i~electrode 5~ by RF teedliZle at~sembl~ 58 cc .~JL;aL~; stem 144 and tube 1~0. Isolator tubes 154, 156 are needed to electncally isolate ar~d preYerlt arculg be~Leen tubulg 150 arld any parts o~ the rQetal housiuj~ 47. including dislr~but4r cover 158. F li,.. ,..r..c. tbe ~EA~'~E~ S~EET

t~'.VOl'i:E~'A~ C~ I 03 ~ :29~ 96: `'0:'~7: _ 51~ 4_1 ~"69~ ~49 8Y 2.3994465.i~
- 2~8~4~7~
--3~ -apparatus includ~s a seal aro~d tubing 150 at the location where it passes through distributor cover I58 as described l.~.c..~.vc and shown in Fig 2A.
R~ er,ergy is supplicd througLt a shielded ~F supplying cable 200 which is conrlected to ~t RF power source 57 (not shown in Fig. 2A) and has a UHF co~nector 2Q2 at oCIe end. Corlnector 202 ~nates with another U~IF
connector 204, which tn turn is coupled via a Iength af 12 auge wire 206 to a stainless stee~ shaft col~ar 208 mounted ac the upper end of RF line 148. With this ~",., .~...". ..~ thcre is trinimal resistance to the flow of RF ctlrrent. The seg~cnt of RF line 148 whtch is expased above shaft coL~ar 208 is isolated from the grounded rfletal shieldir~g 210 by a po~yrner cap 212. T~c apparatus is believed to be capable of deliYering 250-300 vatts of RF ~owcr a~ 450 KXz to 13.56 ~Iz.
~ ig. 213 shows an alternadve ~ of t~te R~:
showerhead/el~trode ~ o t~ r:.-.. utilized to practice the present invention. The CVD apparams 220 of Fi~. 2~ operateS sirnilarly to the ~ , shown in Figs. 2 and 2A. Ihat is, an RF ,Iw.. L~ilelectrodc 2Z2 is biased by an ~F
feedlirle assembly 224 wbile plasma and reactant gases are putrlped through a cylinder assembb 226 to a substrate ZZ8 on susceptor 230. ~Iow~Yer, the ~..,h.,.'..,...l of Fig. 2~3 e~itrlir~ates the metal cylinder 51 attd insulator ring 60 of Figs. 2 ar~d 2A while pt~ver~ting electrical arcitlg u}sioe of 2he cyli~er asse~bly 226 pro~ima~c Ihe RF line and ~re~entirle che undesired formation Oe plasma wichin che cyl~der ass~mbly 226 when the ~IIU.._ ' 222 is biased as an ~le trode. The ~ r of Fig. 2B utilizes a ~ousiDs, such as or~e si~ilar co housing 42 of Fig. 2, which includ~s a housing co~ 232 and includes æn RF
supply assembLy 234, a heat pipc assembly 236 with c~oling j~ck~t 237 and A~.'E3~'C'D SH~E~

~V,V~N:EPA-MUE~ICHESI 03 ~a~ 20:'~6 ~__ E;L3 4_1 7~ 14~! 8~ 6~
2 I 9 'il 4 5 7 ,A

asscciat~d fluid supply lincs and a gas distrioutor cover 23g with a sealirlg assembly 24L a l gen~rally sir~ilar to the rcspe~tive ~ r,,~r.d~ of Fig. 2.
Howe~er, the cylilLder ~ssembly ~26 dces Llo~ include a r~etal cylirldcr 51 and Lnsulatcr rirlg 60 as showrl in Fig. 2. Rather, a cyl~nder 238 rnade of an insulatilLg rn teria~ such as quarrz surrGunds the ~F feed line assembly 224.
CyiiDder 238 is prefet~bly formlllatcd out of a ,ugh qualiy quartz such ~s Quart~ 1'08-E avaiJable f~om H~rea~s Arners~, as rltiorlcd above.
Quartz cylinder 238 is supported by a rlickel ~1.u ~ .3~electrode 2æ. made of a coriductive m~tal such as Nickel-2C0, without the us~ of scrcws or othcr fasteners rhat are utiii~ed within the P ~ 7 ~ , sf Figs. 2 and 2A. Spe~ifically, a stepp~d bore 24û is forrned withirl housing cover 232 to receivc an upper crld 242 of cylinder 238. ~rings 243, 244 are placed at th~ iL~ ace betwecn stepyed bore 240 a~d cylinder 238 to ~CrrrL a sc~l at Lhe Lnterface. At the ~ower c~d 246 of cylind~r 738, an a~ular rlotch 248 LS formed in cylillder 238 to ~eceive a periphcra3 edge 250 of rhe ~llo n ~Lea~electrode æ2. Ihe notch 248 of cylirlder 238 resrs upon tle peripheral edge 250 of ~llùv~ ' ~elect~de 222.
S31o..~ dlcleAIrode 222 irlclu~cs a stern 252 which is attached to ~F lirle tl ~Lng 254, such æ by a weld ~t 255, to f~tL a unitary ~F line 25~ ' line 25 frictionally hdd and suppo~ted at its top end by collar 25~ s~2~lar to collar 208 o~
Fig. 2~ l~e RF lirle, in turn, supports al~ù,. ' ~electrode 222 aboYc susceptor 23U. Showerhcad/electrode 222. in turn, suppor~s the cylinder 238 wirh~n the cylir~der ~ssembly 226 by ~butting agaiDst cylind~ 238 at notch 2~8 u~
holding i~ i~ bore 24û Ihe interface ~erween al~u..~ 3J~.J/elenrode peripher2i edge 250 and cyli~dcr notch 248 is realcd by a r.~ ~ ~ring 2~ which is ~,~',ENCED Sh'EET

2 ~457 C

coll~ a~ between shelf 248 and a similar ~.OIIt~ JVlldillg annular nofch 260 formed in peripheral edge 250 of the showerhead/electrode 222. Similar to the ~IllI,o~ el.~ of Figs. 2 and 2A, a p~urality of gas halos or rings 262. 264 introduce the necessary plasma and reactant gases into cylinder 238.
The r~ of Fig. 2B eliminaoes the need for metal screws to attach the cylinder 238 to the housing cover 232 and the ~llu~ i/e~ectrode 222 to the cylinder 238. This further reduces the possibility of arcing inside of cylinder 238 because of the reduced metal proximate the biased RF
showerhead/electrode 222. Furthermore~ it is not necessary to utilize ceramic isolator sleeves at the ~llu..~lll~d peripheral edge 250.
Accordingly, the RF showerhead/electrode 222 has also been modified. Showerhead/electrode 222 includes a stem 252 without a flange.
Instead, a slight ridge 266 is formed around stem 252, and as shown in Fig. 2A.
ridge 266 supports a generally circular ceramic tray 268 which is formed from a ceramic material, such as alumina (99.1% Al,03), similar to the ceramic isolator sleeves 154, 156 shown in Fig. 2~. Ceramic tray 268 is supported by ridge 266, and in tum, supports isolator sleeves 270, 211. ~solator sleeves 2?0, 271 are also preferably made of a ceramic insulator material similar to that used for sleeves 154, 150 of Fig. 2A. As wirn the r~ ;ll, "l~ used to practice the present i~vention which are discussed above, preferably the holes of ~l~u~ h~d/electrode . c ~q~
22 are d~ T(1132 (0.0313) inches~in diameter to prevent the formation of a plasma inside cylinder 238 and to confine the plasrna gencrally below the ~l-u~ i/electrode 222 and above the susceptor 230. The ~:...bo~ ,.d of Fig.

2B utilizes quartz cylirlder 238 and eliminates tbe metal attachment screws . .
.. ... . . _ . , _ . .

2 ~ ~ ~1 4~ ~

proximate ~llow~ dilelectrode 222 which helps to prevent the formation of a plasma within cylinder 238 and to prevent arcing between the RF line 256 and ~I-v..~ dd/electrode 2æ and any of the ~ul-uull Lillg metal. A layer of insularion 272 may be placed atop gas distributor cover 239 to prevent contact by an operator; because the gas distribulor cover 239 becomes very hot during operation.
Numerous deposition runs have been made utilizing the RF
electrode/showerhead ~ of Figs. 2 and 2A to illustrate the viability of the presen~ invention. SpecificaLLy, a layer of titanium ni~ride was deposited upon a substrare wafer at d~JlV~ l)/ a L~ .,.diUlc of 400 C. This is c~lhct~nti~lly lower than the substrate tClll~CldLule which is ordinarily required for ther~nal CVD
processes to take place, which may be well over l,000C. For exampLe, a layer of titanium nitride was deposited using ammonia gas (NH3) and nitrogen gas (~2) with the parameters listed below and the results shown in Table 1. The ~.",t;~",,,i;.~.. of the present invention utilizes plasma gas fLows between 500 and

5,000 Sccm (50 to 500 sccm for NH3) while a reactant gas fLow, such as TiCI~, between .5 and 10 sccm is desired. The reaction space 4~L should be evacuated c~ 13~
betwe~(5 to 10 Tor~.

2 ~4~29~ .
sl33s67 PCr/llS91/13641 De~osition Parameters for Ta~le No. I

TiCI, (sccm) 10 NH3 (sccm~ 500 N2 (sccm) 500 RF Power (watts) 250 ¢~ 450 KHz ReactionCha~nberPressure~rr~ (~ (1 r~
Susceptor Rotation Rate (rpm) 100 Substrate Temp. (C) 400 TABLE NO. 1 WAFER NO.

Re3ults and Additional 1 2 3 4 5 6 Deposition Parameters TiN layer thickness (A) 800 698 608 545 723 910 Deposition Rate (A/min) 400 348 304 272 241 303 Layer Resistivity (~i7 ~m) 1519 1194 970 940 lC21 1284 Deposition Time (sec) 120 120 120 120 180 180 Susceptor Temp (C) 414 471 457 461 462 475 Wafers 1-3 were silicon, while wafers 4-6 were thermai o~ide wafers having a thin layer of silicon dio~ide on the surface. This was done to erlsure that the process of the present invention may be utilized in a broad range of CVD d~ ,dliUII;~ for both silicon wafers and oxide wafers. Each of tne substrate wafers of Table 1 were also given arl RF plasma ammonia (NH3) anneal irl the apparatus of Fig. 2 at 250 Watts for d~ Iu~dllld~lr 120 seconds with a gas ~G ~
.". of 5,000 sccm of NH3 at a pressure o~ Tord. The rotation rate of the susceptor during the anneal was d~lU~illl~LL~lr 100 rpm. The NH3 RF plasma improYe3 the film ~uality of the deposited TiN film as discussed further h~,lci~lbluw .
SVBST TUrE S~ RU~ 26 2 ~ 7 ~
95/33867 PCI~/US94/ 136~ 1 The RF plasma ~ ude/~l~u..~ cdd configuration, in accordance with the principles of the present invention, may be utilized to deposit a titanium nitride (TiN) layer on a substrate utilizing both nitrogen gas (N,) and hydrogen gas (H2) instead of ammonia gas (NH3). The various film results and deposition parameters for the Hl and Nl low klll~dLulc deposition of TiN are given below in Table Nos. 2, 3, 4 and 5~ at increasing deposition tc~ dlUlC~ for increasing table numbers.
De~osition Parameters for T~l-le No. 2 TiCI~ (sccm) lû
Hl (sccm) 500 N~ (sccm) 500 RF Power (watts) 250 e? 450 KHz Reaction Chamber Pressure ~ 3~ ( l ru . . ) Susceptor Rotation Rate (rpm) 100 Substrate Temp. (CC) 400 Deposition Time (seconds) 180 TABLE NO. 2 Results and TiN layer Deposition Layer Susceptor Additional thickness (A) Rate (Almin) Resistivity Temp (C) Paramet~rs (~ cm) WAFER NO.

3 l22l 407 4118 488 5 læ7 409 855 470

6 1224 408 4478 460

7 1141 380 3982 460

8 1348 449 4658 460

9 1400 487 3449 460

10 1 106 389 4501 460 SUESTiTUTE SHEET (RULE 2~) 2 9 ~ ~ 4 5 ~ C - -867 PCT/U59~1136 Wafers I and 2 of Table No. 2 werc silicon, while the remaining wafers 3-10 were thermal o~ide. Wafers 6-10 receiYed a 250 WaK RF plasma anneai for 120 seconds at an NH3 gas rate of 5,000 sccm, at an internal pressure f~?(3 Torr) P~
(wafer 6 was done aS(5 Torr)), and a susceptor rotation ratc of 100 rpm.
Table No. 3 illustrates the results of deposition runs utilizing a substrate ~.ll~clulc of 450C, but . ~ the same gas and deposition par~uneters as were used in the deposition runs of Table No. 2. Wafer I and 2 were silicon while wafers 3-8 were therrnal o~ide. The results are as follows with wafers 6-8 of Table No. 3 receiving a 120 second RF plasma ammonia anneal at 5000 sccm~5 Torr) and a 100 rpm rotation rate with a power level of 250 WaKs.
TARr l~ NO. 3 WAFER NO.

Results and 1 2 3 4 S 6 7 8 Additional Parameters TiN layer 996 1009 1064 1488 1562 1444 1381 1306 thicl~ness (A) Deposition 332 336 355 496 521 481 454 435 Rate (A/min) Layer 640 607 666 815 821 7121 5812 6363 Resistivity ~n -cm) Susceptor 518 519 521 524 521 522 524 523 Temp (C) SUbSTlTUTE Sl IEET (RULE 26) ~WO 9~/33867 PCT/US94/13641 The low i , TiN deposition was repeated with the substrate at 500C and the results are tabulated according to Table No. 4 below.

Wafer I was silicon a~ld wafe}s 2-7 were thermal oxide.

TART.T''. NO. 4 WAFER NO.

Res~alts and 1 2 3 4 5 6 7 Additional Parameters TiN layer 990 1086 1034 1092 1004 1001 1004 thichless (A) reposition 330 362 345 364 335 334 335 Rate (Almra) Layer 578 687 700 786 1892 1840 1886 Resistivity ~n -cm) Susceptor 579 590 597 595 591 593 594 Temp (C) Wafers 1-4 in Table No. 4 were not annealed, while wafers 5-7 were annealed using a similar RF plasma NHI anneal process and the parameters used for the deposition runs referenced in Table No. 3.
Similarly with a substrate ~ --r. of 600C, the CVD process of the present invention was used to deposit TiN wit71 the results shown in Table No. 5 below, with wafers I and 2 being silicon and wafers 3-8 being t'aermal oxide.

SA, ~
SUBSTITUTE SHEET (RULE 26) ~i;o ss/33~67 ~ 4 ~ 7 Y~NS~/t~G1, TAR~.F NO. 5 WAFER NO.

Results and 1 2 3 4 5 6 7 8 Additional Parameters TiN layer 657 822 740 768 767 765 713 910 thiclcness (A) Deposition 219 274 247 263 256 255 258 303 Rate (A/min) Layer 391 254 432 543 471 949 973 2710 Resistivity cm) SL~sceptor 650 650 650 650 650 650 650 650 Temp ( C~
Again, an RF plasma NH3 anneal wa3 performed on substrate wafers 6-8 of Table No. 5 similar to the anneal step of tables 3 and 4 except at a ?~
pressure of il~l Torr) instead o~(5 TorrJ. Therefore, the deposition of TIN using the low ~ Aiul~ CVD process of the present invention may be A( I IJ"~ i at various ~,~ ALul~s lower than the t~ Uuc;~ necessary for traditional therrnal CVD.
While titanium nitride may be deposited with the present invention, it may also be desirable to deposit simply a layer of pure htanium. For example, a titanium layer might be deposited upon a silicon wafer which then reacts v.~ith the titanium to form a film of titanium silicide (TiSi~). To this end7 the present invention may also be used to deposit a layer of titanium.
Table No. 6 below sets forth the results and parameters of a deposition run which resulted in a deposited film of A~ Jlu~ u~ ly 84% titanium SUBSTITUTE SHEET (RU~E 26) ~095/33867 2 ~ 4 5 7 C pCrruS9~/136-l1 on a thermal o~ide wafer at 650C. This was an e~cellent result for such low ~ chemical ~apor deposition. The deposition run of Table 6 was performed according to the following deposition rA~m t~r~, with the RF
~llu.._lh~d/electrode ...~ ,.... of Fig. ~.
Derosition Parameters for TAhle No. 6 TiCI~ (sccm) 10 H2 (sc~m) 500 RF Power (watts) 250 ~ 450 KHz ReactionChamberPressure jl-T{trr~ (~ l33 (1T~i) Susceptor Rotation Rate (rpm) 100 Derosition time (sec) 2700 Substrate Temperature (C) 565 TARr F NO. 6 WAFER NO.
Results and Additional Parameters Ti layer 1983 thic~ness (A) Derosition 44 Rate (A/min) Layer 9~9 Resistivity ~n -cm) Susceptor o51 Temp ( C) The substrate wafer of Table No. 6 was not annealed.
Additional Ti-layer derosition runs were made according to the Table No. 7 parameters below with the following results shown in lable No. 7:
SU~STITUTE SHEET (RULE 26~

2 ~ 457 C
~9S133867 PC.~`lU594/1i611 D~ihr~n Parameters for Table No. 7 TiCl~ (sccm) 10 EII (sccm) 500 RF Power (watts) 250 ~ 450 KHz Reaction Chamber Pressure j~85~ 3 ( C ~^l T~
Suscepior Rotation Rate (rpm) 100 Deposition time (sec) 120 (wafer 7 for 180 sec) Substrate Temperature (C) 565 Susceptor Temperature (C) 650 TABLF NO. 7 Results and TiN 1ayer Deposition Rate Layer Resistivity Additional thickness (A) (A/min) (~n-cm Parameters WAFER NO.
134.8 67.4 2116.1 2 466.2 233.1 1767.8 3 209.2 104.6 761.8 4 100.8 50.4 5 194.04 97.0 6 154.98 77.5 7 1 15.92 38.6 1001.4 8 114.7 57.3 371.6 9 152.5 76.2 321.6 39.06 19.5 1 1 41.6 20.6 12 50.4 25.2 Wafers 1-3 and 7-9 of Table 7 were silicon while the remaining wafers were thermal oxide. None of the wafers of Table No. 7 received an RF
plasma anneal of NH3.
Since a benefit of chemical vapor deposition of titanium-contairing films is improved step coverage and film r~nfonn~iity over the physical deposition SUbSTlTUTE SHEET (RULE 26) 2 ~ ~ ~ 4 5 7 -- -951338C7 PCrtUS9~/13641 techniques, seve~al of the film layers deposited according to the present invention were tested to measure ~ r.,.."A~ and step coverage. The layers tested for ~ l.oliL~ and step coverage were deposited according to the parameters of Table No. 8 ~vith the resulS shown in Table No. g below. The film conformality and step coverage of the film layers deposited according to the parameters belo~v were very good.

De~osition pA~ml~t~S for C~ r~" ",AT;I ~ and Ste~ Cov~ ~e Deposition Runs of ~able 8 TiCl (sccm) lO
H2 (sccm) 500 N2 (sccm) 500 RF Power (watts) 250 ~ 450 KHz Reactor Chamber Pressure ~o~~ r~
Susceptor Rotation rate (rpm) lO0 Substrate Temperature (C) 450 Susceptor Temperature (C) 520 TABLE NO. 8 WAFER NO.
Results and l 2 Addition-1 Parameters TiN layer 586 2423 thic~ness ~A) Deposition 362 3r~4 Rate (A/min) Layer _ _ Resistivity cm) Susceptor 520 520 Temp (~C) SUBSTITUTE SHEET (RULE Z6 4 ~ 7 ~wo None of the wafers used in Tabk 8 and tested for step coverage were annealed with an ~F plasma of NH3.
As illustrated above a layer of titanium nitride (TiN) may be deposih~d in accordance with the principles of the present invention without utilizing ammonia gas (NH3). Instead, a mixture of H2 and N2 gases is used. Low h r ' e deposition of titanium nitride using TiCLt, N2 and H2 i5 desirable because it reduces a within the reaction chamber that are formed by the chemical reactions of TiC~ and NH3. More specifically, TiCI~ reacts with NH3 at r \~ c~ below 120C to form a yellow powdery adduct, and to prevent the adduct from forlning it was necessary in the past to heat the reaction chamber walls to at least 150'C. Since it is now possible to deposit a layer of titanium nitride at low t~ r ~1 using TiClt, N2, and H2 chemistry instead of NH3, it is no longer necessary to remove a deposited adduct or ho heat tbe reaction chamber walls, thus greatly reducing the cost of CVD systems.
According to the deposition parameters of Table No. 9, a layer of titanium nitride was deposited upon several thermal o~:ide substrates using a reaction chamber with unheated walls and a gas mixture of H2/N2. After the deposition of the films, the reacdon chamber was inspected and there wa3 no evidence of a yellow adduct found. None of the wafers of Table No. 9 were annealed with an RF NH3 anneal.

'! t~f ~ r ~ . 4' ~ ~:
SUBSTITUTE SHEET (RULE 26) '` 2~9~4~7,C
~0 95/33867 PCT/US9 P;3r~m~l~rs for Adduct Test of T~hle No. 9 TiCI. (sccm) 10 N2 (sccm) 500 ~2 (sccm) 500 RF Power (watts) 250 62 450 KHz Reaction chamber pressurei~To~ 3 ('~ T~ ) Susceptor Rotation rate (rpm) 100 Substrate Temp. (C) 450 Deposition time (sec) 95 Susceptor Temperature (C) .1 ~, 520 T~Rr F NO. 9 Rults and TiN layer Deposition Layer Susceptor Additional thickness (A) Rate (A/min) Resistivity Temp (~C) Parameters (~n-cm) WAFER NO.

2 132 83 æl8 523 6 160 101 '~05 523 g 195 123 689 519 Further deposition rurls were made utilizing the I ~"r~ ". of Fig. 2 wherein the plasma and reactant gas flows were adJusted, a3 well as the internal deposition prsure of the reaction space 44. For example, the deposition runs shown in Fig. 10 utili~ed a higher flow rate of H~ and an increased deposition pressure fron~ (1 To.q to 5 Torr~. ~urther, Argon was mi~ed witn the H~ for some of the deposition runs.

SU8STITUTE SHEET (~ULE 26 2 ~ ~ ~ 4 5 7 95t33867 PCTIUS9~/136~11 ~neters for Table 10 TiCl~ (sccm) 10 H7 (sccm) 5,000 (wafers 1-4); 3,750 (wafers 5-9) Argon (slm) 0.5 (wafers 5-9) RF Power (watts) 250 6~ 450 KEIz Reaction Chamber Pressure l (Torr) 5 Susceptor Rotation rate (rpm) 100 Deposition time (sec) 300 (600 for wafer 9) Substrate Temp. ('C) 565 Susceptor Temperature (CC) d~ GL~I~ 650 TARr.F, 10 = ~
Results and TiN layer Deposition Rate Layer Additional thic~ness (A) (A/n7in) Resistivity Parameters (/112-cm) WAFER NO.
798 159.0 53.84 2 1076 215.0 32.66 3 43.4 9. 1 216. 1 4 89.5 17.9 377. 1 5 912.2 182.5 89.23 6 1082 216.5 25.7 7 656.5 131.3 212.7 8 577.1 115.4 211.3 9 1302 130.2 170.1 In Table 10, the flow of Hl was increased to 5,000 sccm for wafers ~ r~;
1-4 ~nd to 3,750 sccm for wafers 5-9. The deposition pressure was increased t~
Torr~ For wafers 5-9, a flow of 0.5 standard liters per minute (slm) of Argon was utilized with the Hl as a diluent. In Table 10, wafers 1-2 and 5-6 were silicon, while wafers 3~ and 7-9 were thermal oxide.
Table ll shows additional runs made with the increased H~ flow and increased deposition pressure.

SUESTlTUTE SHEET (RULE 26) 2 ~9 ~457 ~
~095~33867 PfL'T/~15941136JI

Derlosifi-)n Par~m~-f~ fnr T~htP No 11 rlcl, (sccm) 10 Hl (sccm) 3,750 Argon (slm) 0.5 RF Power (watfs) 250 ~ 450 KHz Reac ian Chamber Pressure l~rorr) 51 ~ P~ L 5 rc~f) Susceptor Rofation Rate (rpm) 100 Deposi ion time (sec) 3J0 (wafers 9-12 600 seconds) Substra e Temperature (~C) 565 Susceptor Tempera ure (C) 650 TART F NO. 11 Results and TiN layer Deposifion Rafe Layer Resisfivify Addi ional fhickness (A) (A/min) Gun-cm) Parameters WAFER NO.
889.6 177.9 54 03 2 399 4 7'~.9 35 ?1 3 510.3 102.1 233.4 4 458.6 91.7 274.1 5 466.2 93.2 281 0 6 385 6 77.1 280.1 7 347.8 69 6 545.1 9 792.5 79.3 314.1 10 948 8 94.9 203.5 1 1 749.7 75.
12 7144 71.4 I ~ ~t~ ~ ~ f ~
The change in deposifion pressure fron~(1 Torr to 5 Torr)produced a more sfable and symmefric plasma. Addifionally, the increased hydrogen flow wifh the addi ion of a small flow of argon increased the sf~abilify of the plasma flow as well as fhe plasma intensify. An argon flow of ~10 slm is preferat~le.

SUBSTITUTE SHEET (RULE 26~

~WO 95/33867 2 7 !~ ~ 4 ~ 7 PCT/US94113641 Wafers 1-2 were silicon, while wafers 3-lO were thermal oxide. Wafers 11 and 12 were ~ululJllu*~llo-silicate glass, available from Thin Films, Inc. of Freemont, California. None of the wafers of either Table 10 or 11 were annealed with a NH3 plasma anneal.
Wafers 11 and 12 had field oxide (silicon oxide) top layers, patterened with silicon contacts (i.e., vias through the field oxide to a lower silicon layer). Selective deposition was observed in wafer number 11 after processing in the manner described above. Fig. 6 shows deposition at the bottoms of silicon contacts (vias), but no deposition onto the oxide field. Selective deposition has been repeated and ;~ ly verified using the identified parameters. A selective deposition process can be used in place of multiple process steps to form vias. Selective deposition may be a result of different nucleation times for silicon and silicon oxide -- nucleation occurs rapidly on silicon, but only after d,uyl~ 'y 30 seconds on silicon oxide. Although the process applied to wafer 11 r m for longer than the normal 30 second nucleation time of silicon oxide, nucleatiûn apparently did not occur over silicon oxide, possibily due to an instability in the plasma. High process pressures appear to be important for producing the selective effect.
Table 12 shows additional deposition runs at a susceptor i .
of 450C.

SUBSTITUTE SHEET (RULE 26) ~ ~9~457 ~, De~n~itinn P~r~m^t~rs for T~h1~ No. 12 TiCI, (sccm) 5 H2 (sccm) 3,750 Argon (slm) 0.3 RF Power (watts) 250 6~ 450 KHz Reaction Chamber Pressu}el(To.l) 5 1 (~ (5 T~ ~) Susceptor Rotation Rate (rpm) 100 Deposition time (sec) 180 Substrate Temperature (C) dLJ~U~llld~ly 400C
Susceptor Temperature (C) 450 T~BLF, NO. 1~

WAFER NO.
Results and 1 2 3 4 5 6 7 Additional Parameters TiN layer 242 222 210 241 168 136 150 thic~ness (A) Deposition 80.7 74.0 70.0 80.3 56.~ 45.3 50.0 Rate (A/min) Layer 66.0 554.0 494.0 714.0 484.0 0.1 0.1 Resistivity ~n -cm~
Wafers I ~ were silicon, wafer 5 was thermal oxide w~ile wafers 6 and 7 were dn aluminum alloy containing aluminum silicon and copper. Runs 6 and 7 of Table 12 illustrate the viability of depositing a titanium-contair ing film on aluminum using the present invention. The deposition runs of Table 12 utiii~ed a lower flow of reactant gas than the runs of Table 11, i.e., 5 sccm of TiCl~.
Good adhesion between the aluminum and titanium layers was obtained by ",; ,; ";,;"o the corrosion of the aiuminum layer. Corrosion is iargely a result of e~posure of the aluminum layer to chlorine ions (C~) released from SubsTlTuTE SHEET (RULE 26) ~WO 9~/33867 2 ~ ~ ~ 4 5 7 PCT/US94/13641 titanium trtr~.~hl~lri-l~ (TiCI~) during deposition. By reducing the flow rate of titanium i ' ', the corrosion of the aluminum layer is reduced and adhesion is improved. Reduced tit~nium ' ' ' flow also reduces ~e deposition rate, aUowing dissociated titanium atoms addi~tional time to locate stable sites in the underlying aluminum layer. This additional time is ~uLi.,uLI~ needed due to the low the~mal energy and reduced thermal motion of the titanium atoms at reduced process i The deposition runs of Table 13 were made at further reduced TiCI4 flow rates. All of the wafers of Table 13 were thermal oxide. None of the wafers of Table 12 or 13 were annealed with. an NH3 RF anneal.

,v ~ u ~J.~
SUESTITUTE SHEET (RULE 26) ~Y095/33867 ~ 4 5 7 ~ pC~/USg~113641 --ss--De~ n P~r~ml~trr~ for T~hle No. 1~
TiCI~ (sccm) wafers 1-2, 4 sccm; 3-4, 3 sccm; 5~, 2 sccm; and wafer 7 at 1 sccm H2 (sccm) 3,750 RF Power (watts) 250 G~ 450 K~Iz Reaction Chamher Pressure ~Fer~5t (Pu~ o~ -) Susceptor Rotation Rate (rpm) 100 Deposiion time (sec) 300 (wafers 1 and 2 at 180 and 240, SubstQte TempeQture (C) d~ U~l~ld~ly 400C
Susceptor TemDeQture (C) 450 TABLE NO. 13 WAFER NO.
Resuits and 1 2 3 4 5 6 7 Additional Parameters TiN layer 89 132 158 149 158 166 107 thichless (A) Deposiion 30 33 32 32 32 33 21 Rate A/min) Layer 259 239 199 199 190 208 482 Resisivity ~n -cm) icr~ ir~n of Results from DeDositio~ ~lmc Titanium films have ben deposited utili~ing the parameters and appaQtuses discussed above at Qte3 Qnging from 30 A~min. measured by mass g~in and by waYe dispersive ~-Qy nuul~li~ (WDXRF). It has been found that the deposition Qte is directly IJIU~UIIiUlldl to the deposition ~.ll~dlU~t: and to the T;CI~ al pressure. Film resistivity increases from 120 to 150 ~n -cm a3 the deposiion ~~ Lulc is decreased from 550 C to 450 C. Titanium films . .
SUE,S~ITUTE SH'ET (RULE 26) a~
~WO 95133867 PCT/US94/13641 deposited at 550C onto thermally grown oxide were analyzed by Rutherford Back Scatter S~ y (RBS) and found to be elemental titanium. The only impurity that is detectable by RBS is oxygen. Auger Electron Sp~l-u~u~7y (AES) depth profiling was performed to identify low level c~ ;.... The AES
profiles indicate a bulk chloride content of 0.1%. Chloride was also measured by WDX~cF, which indicated a bulk I of 0.45%.
Films were also deposited at 550 C onto non-deglazed silicon substrates. These films were analyzed by RE',S and found to have formed a silicide during the deposition process. No post deposition anneal had been performed.
The ~ y of the in-situ silicided titanium is TiSi2 but 0.5% chloride was detected. AES depth profiling confirmed the ' y of the in-situ silicide, as well as the bulk chlorine content of 0.5%. The AES profiles indicate a low level of oxygen in the silicide, but there is no evidence of an oxygen peak at the silicon/TiSi, interface. This indicates that the native oxide has been removed by the CVD-Ti process.
Titanium films were deposited at 550 C onto patterned bu., r' I' ' silicate glass (E,PSG) in order to observe film Cullr.,....~i~y. All contacts were I~Lm to 0.35~m (aspect ratios varied from 1.0 to 2.9). The titanium films were found to be conformal for all aspect ratios. Film thicknesses of up to lSoo A were deposited and cross sections were observed by a scanning electron microscope (SEM). There was no evidence of overhang formation at the contact openings. Overhang formation is a r I problem with line of sight deposition processes such as sputtering. This problem has been well ~' ' ~ . .
SUBSTITUTE SHEE~ ~RULE 26) ~ ~ 9 1 ~ 5 7 ~WO 95133867 PCTIUS94/136-11 for both ~ iùl~l and collimated sputtering, and the conformal nature of the CVD-Ti pro~ess represents a significant advantage over sputtering technology.
A ~ I of the electrical properties obtained with CVD-Ti and sputtered-Ti was made using the electrical test structures described above. Contact resistance were made using K~lvin structures with contact sizes wbich varied from 0.35~m to O.oO~Lm. In order to deposit 100 A of titanium at the bottoms of the 0.35~Lm contacts, 900 A of sputtered-Ti was deposited compared to 200 A of CVD-Ti. The CVD-Ti and sputtered-Ti films provided equivalent contact resistance for all contact sizes. However, the smaller conhcts had a much higher probe yield with the CVD-Ti contact layer. For 0.35~m contacts the yield for the CVD-Ti contact layer was double that of the sputtered-Ti layer. The i~ u._ in yield indicates that the CVD-Ti process provides more uniform and repeatable results over the surface of the wafer, and suggests that the process may overcome minor contact to contact variations that are created by the contact etch and contact cleaning processes. This assertion is supported by the AES results reported above which showed that no residual native oxide was detected at the silicon/TiSi2 interface after CVD-Ti and in-situ ~ inn A more severe cnm~ nn of the two contact layers was made using chains of 10,000 contacts. Ag~un the results were similar for the larger contacts.
However at 0.35~m The CVD contact layer produced superior results. The CVD-Ti contact layer provides contact chain resistance values that are two orders of magnitude lower than those obtained with the sputtered-Ti layer. r.,l;~ , the probe yield for the CVD-TI layer was five times bigher than that for the sputtered hyer.

SUBSTITUTE SHEET (RULE 26) 4 ~ 7 C
WO 95/33867 PCT/I)S9-11136 11 Leakage current for CVD-Ti and sputtered-Ti were similar. This indicates that the in-situ silicidation provided by the CVD-Ti process does not cause junction damage. This is confirmed by SEM cross sections which were performed on the samples after completing the electrical 11~UI~ 11.~11L7 The cross sections confirm that the silicide formed during the CVD-Ti process at the bottoms of the contacts is uniform.
In conclusion, titanium films have been deposited by chemical vapor deposition at i . of 450 C to 550 C. The titanium is fully converted to TiSi2 during the deposition process for depositions onto silicon surfaces.
DPrcifinnc were conformal with no evidence of titanium overhangs at contact openings. Contact resistance and junction leakage , indicate that the CVD-Ti process provides equivalent dectrical I ' to sputtered-Ti for low aspect ratio features. For higher aspect ratio features the CVD-Ti process provides superior contact resistance and yield. The improvement in electrical y~l is due to the conforma'l nature of the CVD-Ti, the removal of the residua'l native oxide from the contact bottom, and formation of a uniform TiSi2 layer at the contact bottom.
Figure 3 shows another; ' ' of a deposition chamber with an upstream RF plasma source which might be utilized to generate the necessary radicals for an upstream plasma low h..~ lc; PECVD process utilizing a rotating susceptor as discussed and disclosed hereinabove with respect to the upstream plasma generafion utilized by the ~....I;~..,~Ii.~.~ of Fig. 1. Specifica'lly, a deposition chamber 280 is attached to an RF p asma source 282. A suitable source is a cn~~lPrri~lly available RF source available from Protofech Research, SU~STITUTE SHEET (RULE 26) Inc., of Tempe, Arizona. RF plasma source 282 includes a housing 284 which forms a plasma generating region 286 therein. The plasma gases to be excited, such as H2, N2, and/or NH3 are introduced through gas input lines 287, 288 and gas rings 289, 290, ~ y Within region 286, the plasma gases are excited by an RF field generated by RF coil 292 which is connected to an RF source 294.
RF energy of, for example, ~ , 13.56 MHz is delivered to t'ne gases within region 286 to create a gas plasma containing free electrons, ions and radicals of the plasma gas. As the excited gases are drawn down the length of pl~,.." g~ g region 286, gas particles combine until preferably an abundance of radicals remain. The radicals are drawn down through a deposition region 296.
The react~nt gases, such as TiCI~, are introduced into the deposition region 296 by a vertically adjustable gas ~I~u..~ ~l 298, and the reactant gases and activated radicals are drawn down to substrate 300 by rotating susceptor 302 and combine to form a film layer on substrate 300. The substrate 300 heated as discussed above and similar pressures, susceptor rotation rates and gas flow rates for the examples discussed above might be utilized with the RF plasma source of Fig. 3.
Accordingly, a film, such as a titanium-containing film, may be deposited at substantially lower i I than achieved with traditional thermal CVD
processes.
While the present invention has been illustrated by the description of . ' ~ ' thereof, and while the ~ ' ' have been described in c<",~;.l. .,.1.'~ detail, it is not the intention of Applicants to restrict or in any way Iimit the scope of the appended claims to such detail. Additional advantages and ~ will readily appear to those skilled in the art. For example, the lûw . . . r A ~
SU~STITUTE Sl li~-ET (RULE 26) 2 ~ ~ ~ 4 5 7 - -s/338~7 PCT/US9~/136 LCIII~d~UlC CVD technique of the present invention may be utilized to deposit other films besides the titanium-containing films discussed in extensive detail herein. FulLc~ o~, activated radicals of gase3 other than 1I2~ Nz and/or NH3 might dlSO be utiiized to lower the deposition ~ll~ldLUlC. jThe invention in its broader dspects is therefore not limited to the specific details, IC~IC~CII~Li~
apparatus and method, and illustrative example show~ and described.
Accordingly, departures may be made from such detdils without departing from the spirit or scope of Applicants' general inventive concept.
/What is claimed is:

/ ,,/ _ .

SUBSTIi i~E Si !E-T (RU' ~ 26!

Claims (30)

CLAIMS:

1. A method of depositing a film on a substrate by plasma chemical vapour deposition comprising:
providing a substrate inside a chemical vapour deposition reaction chamber;
heating the substrate;
supplying a first gas into the reaction chamber;
exciting the first gas to form a plasma; and supplying a second gas into the reaction chamber, CHARACTERISED IN THAT
the first gas plasma includes activated radicals of the first gas, the second gas is a titanium-containing gas and the radicals mix with the second gas, the method comprising:
rotating the substrate to draw a mixture of the radicals and the second gas to a surface of the substrate such that the radicals react with the second gas in a surface reaction to deposit a titanium-containing film on the substrate surface.

2. A method of Claim 1 wherein the step of exciting the first gas forms ions thereof which supply energy to the surface reaction.

3. A method of Claim 1 or Claim 2 wherein the step of exciting the first gas includes generating activated radicals thereof with an RF energy source.

4. A method of any preceding Claim wherein the step of exciting the first gas includes generating activated radicals thereof with a microwave energy source.

5. A method of Claim 4 wherein the first gas is excited with the microwave energy source remotely from the substrate, the first gas producing additional radicals as it is drawn to the substrate.

6. A method of Claim 5 wherein the first gas is excited in one end of a quartz tube and drawn through the tube to the substrate.

7. A method of Claim 1 including exciting the second gas such that the gas mixture drawn to the rotating substrate comprises first gas radicals and the excited second gas.

8. A method of Claim 3 comprising directing the first gas through an RF field region surrounded by an RF
coil and located upstream of the substrate to excite the first gas and form radicals.

9. A method of Claim 8 comprising supplying the second gas downstream from said RF field region so that the second gas is not excited by the RF field.

10. A method of Claim l wherein the substrate is rotated at a rate between 0 and 2,000 rpm.

11. A method of Claim 3 comprising:
directing the first gas through a gas-dispensing showerhead proximate the substrate, the showerhead having a plurality of openings;
biasing the showerhead with the RF energy source to make the showerhead an RF electrode having an associated RF field; and passing the first gas through the openings of the showerhead and through the RF field to excite the first gas to form radicals and ions which react with the second gas at the substrate surface to deposit a film thereon.

12. A method of Claim 11 comprising:
passing the first gas through a cylinder coupled to the showerhead above the substrate to establish a predetermined first gas flow before passing the first gas through the showerhead, to produce a uniform flow of radicals and ions to the substrate.

13. A method of Claim 11 wherein the showerhead is positioned approximately 25mm (1 inch) or less from the substrate.

14. A method of Claim 11 including exciting the second gas with the RF field such that a gas mixture is formed comprising first gas radicals and excited gas particles of the second gas.

15. A method of Claim 11 wherein the substrate rotated at a rate between 0 and 50,000 rpm.

16. A method of Claim 1 or Claim 11 wherein the first gas is selected from hydrogen, nitrogen, ammonia and mixtures thereof.

17. A method of Claim 1 or Claim 11 wherein the first gas is selected from a group consisting of a combination of gases including any two of hydrogen, nitrogen and ammonia.

18. A method of any preceding Claim wherein a diluent gas is mixed with the first gas.

19. A method of Claim 17 wherein the diluent gas comprises argon.

20. A method of Claim 1 or Claim 11 wherein the substrate is heated to between 200°C and 800°C during deposition of the film.

21. A method of Claim 1 or Claim 11 comprising maintaining the pressure inside the reaction chamber between 67 and 2000 Pa (0.5 and 15 Torr).

22. A method of Claim 1 or Claim 11 wherein the first gas is supplied at a rate between 50 and 50,000 sccm.

23. A method of Claim 1 or Claim 11 wherein the second gas is supplied at a rate between 1 and 20 sccm.

24. A method of Claim 1 or Claim 11 wherein the substrate is rotated at a rate sufficient to produce a laminar flow of the first and second gas mixture over the substrate to reduce gas recirculations and recombinations of the activated radicals.

25. A method of Claim 1 wherein the substrate includes an oxidized layer overlying a semiconductor layer, the oxidized layer including at least one via through which said semiconductor layer is exposed, and the chemical vapour deposition reaction chamber includes an RF energy source and RF electrodes forming an RF
field, comprising:
directing the first gas through the RF field to excite the first gas to form activated radicals and ions thereof and mixing the second gas with the first gas radicals and ions, the rotation of the substrate drawing a mixture of the first gas radicals and ions and the second gas to a surface of the substrate, the radicals and ions of the first gas reacting with the second gas in a surface reaction to cause deposition of titanium onto the semiconductor layer through the at least one via, without causing deposition onto the oxidized layer.

26. Apparatus for depositing a film on a substrate by chemical vapour deposition comprising:
a reaction chamber for receiving a substrate;
means for heating a substrate in the reaction chamber;
a first gas supply;
a passage connecting the first gas supply to the reaction chamber, the passage defining an outlet which directs the first gas proximate a substrate in the reaction chamber;
an energy source coupled to the passage upstream of said outlet for generating a plasma in the passage by exciting the first gas to form activated radicals thereof;
a susceptor within the reaction chamber for supporting a substrate; and a second gas supply coupled to the reaction chamber to direct a second gas proximate the substrate, CHARACTERISED IN THAT
the second gas is a titanium-containing gas, and the susceptor is rotatable to draw the radicals through the passage into the chamber and proximate the substrate to mix with the second gas, and to draw said mixture over the substrate such that the gases chemically react to deposit a titanium-containing film on the substrate:
surface.

27. Apparatus of Claim 26 wherein the passage includes a quartz tube, the energy source generating microwave energy and being coupled to the tube to generate the activated radicals of the first gas.

28. Apparatus of Claim 27 wherein the quartz tube is generally vertical such that the first gas radicals are drawn vertically downward to the substrate.

29. Apparatus of Claim 27 wherein the quartz tube is generally horizontal and includes a vertical portion defining said outlet, such that the first gas radicals are drawn horizontally along the tube and then downward through the vertical portion to the substrate.

30. Apparatus of Claim 26 wherein the energy source generates RF energy.