US20050279282A1

US20050279282A1 - Method and apparatus for processing a semiconductor substrate

Info

Publication number: US20050279282A1
Application number: US11/155,093
Authority: US
Inventors: Kun-Sang Park; Young-wook Park; Jin-gi Hong
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 2004-06-16
Filing date: 2005-06-16
Publication date: 2005-12-22
Also published as: KR100596488B1; KR20050119227A

Abstract

In a method of processing a semiconductor substrate, a source gas is primarily excited into a first plasma state having a first energy. The primarily excited source gas is provided to a process chamber. The excited source gas in the process chamber is secondarily excited into a second plasma state having a second energy higher than the first energy. The secondarily excited source gas contacts a semiconductor substrate to process the semiconductor substrate.

Description

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority under 35 USC § 119 to Korean Patent Application No. 2004-44265, filed on Jun. 16, 2004, the contents of which are herein incorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a method and an apparatus to process a semiconductor substrate. Embodiments of the present invention relate to a method of processing a semiconductor substrate using a source gas excited in plasma state and an apparatus to process a semiconductor substrate using a source gas excited in plasma state.
2. Description of the Related Arts
Generally, a semiconductor device may be manufactured by, for example, forming layers, patterns, and metal wiring. To form a highly integrated, high capacity semiconductor device, plasma energy states have been employed.
Generally, plasma is a phase of matter in which electrons, ions and neutrons coexist with an overall electrically neutral polarity. A source gas excited to a plasma state has a high reactivity supporting precise semiconductor substrate processing. To form a semiconductor structure of minute pattern or a high aspect ratio, a source gas excited to a plasma state has been used.
FIG. 1 (Prior Art) is a cross sectional view illustrating a conventional apparatus for processing a semiconductor substrate using plasma.
Referring to FIG. 1, a conventional apparatus 10 includes a process chamber 20, a chuck 32, a heater 34, a showerhead 40, a first gas supply line 52, a second gas supply line 54 and a high frequency power supply 60.
Process chamber 20 provides a space to receive a semiconductor substrate W for processing. Chuck 32 is located in process chamber 20 to support semiconductor substrate W. Heater 34 is built into chuck 32 to heat semiconductor substrate W. Showerhead 40 resides over semiconductor substrate W as positioned on chuck 32.
First and second gas supply lines 52 and 54, respectively, connect to showerhead 40. A source gas enters process chamber 20 via showerhead 40.
Power supply 60 provides high frequency power to showerhead 40 and thereby creates an electric field having a high potential difference within process chamber 20. The source gas, exposed to this electric field, becomes an excited source gas in a plasma state.
As described above, electrons, ions and neutrons coexist in the source gas when in a plasma state. The electrons in the source gas break molecular bindings of other source gases to excite other source gases into plasma state. As a result, process chamber 20 is filled with source gases excited into the plasma state. Molecules in the source gas, as excited into the plasma state, react with each other to form a layer on semiconductor substrate W.
Another conventional apparatus used to process a semiconductor substrate includes the above-mentioned conventional apparatus 10 and, further, a remote plasma generator. The remote plasma generator excites a source gas into plasma state. Showerhead 40 and high frequency power supply 60 excite a cleaning gas into plasma state. Thus, two conventional apparatuses have substantially similar elements except for a remote plasma generator.
To illustrate by example, a conventional method of forming a titanium nitride layer using conventional apparatus 10 is described.
A TiCl₄gas is provided to the process chamber 20 through first gas supply line 52. An NH₄gas enters process chamber 20 through second gas supply line 54. The TiCl₄gas and NH₄gas, being exposed to the high potential electric field within chamber 20, achieve an excited plasma state. The TiCl₄gas and NH₄gas in the excited plasma state react to form a titanium nitride layer on semiconductor substrate W and, as a byproduct, generate an HCl₄gas. In this method, process chamber 20 and semiconductor substrate W therein reach a temperature of no less than about 600° C.
This conventional method using plasma states uses significantly high reaction energies of the source gases as excited in the plasma state and significantly high thermal energies for successful processing. Unfortunately, under such high thermal energies desirable characteristics of a semiconductor device may deteriorate. When thermal energies are low, however, abnormal phases may be generated in the semiconductor device. For example, when the temperature of the deposition process is lowered the reaction ratio between the TiCl₄gas and NH₄gas undesirably reduces and larger amounts of chlorine molecules remain in the titanium nitride layer. This can cause corrosion of the titanium nitride layer and increase its resistance. As power from high frequency power supply 60 increases to increase reaction energies between the TiCl₄gas and NH₄gas, however, the reaction ratio between the TiCl₄gas and NH₄gas may not be increased to a desired level. Furthermore, an increase of power can cause undesirable etching of the titanium nitride layer.
Accordingly, lowering process temperature has been a desirable goal in manufacture of highly integrated, high capacity semiconductor devices.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide a method of processing and an apparatus to process a semiconductor substrate with high efficiency yet at a relatively lower processing temperature.
In a method of processing a semiconductor substrate in accordance with one embodiment of the present invention, a source gas is primarily excited into a first plasma state having a first energy. The primarily excited source gas enters a process chamber. The excited source gas in the process chamber is secondarily excited into a second plasma state having a second energy higher than the first energy. The secondarily excited source gas is applied to a semiconductor substrate to process the semiconductor substrate.
In a method of processing a semiconductor substrate in accordance with another embodiment of the present invention, a first source gas is primarily excited into a first plasma state having a first energy. The primarily excited first source gas enters a process chamber. The primarily excited first source gas in the process chamber is secondarily excited into a second plasma state having a second energy higher than the first energy. The secondarily excited first source gas is applied to a semiconductor substrate to primarily process the semiconductor substrate. A second source gas is primarily excited into a third plasma state having a third energy. The primarily excited second source gas enters the process chamber. The primarily excited second source gas in the process chamber is secondarily excited into a fourth plasma state having a fourth energy higher than the third energy. The secondarily excited second source gas is applied to the semiconductor substrate to secondarily process the semiconductor substrate.
In a method of processing a semiconductor substrate in accordance with still another embodiment of the present invention, a first source gas is primarily excited into a first plasma state having a first energy. The primarily excited first source gas enters a process chamber. The primarily excited first source gas in the process chamber is secondarily excited into a second plasma state having a second energy higher than the first energy. The secondarily excited first source gas is applied to a semiconductor substrate to primarily process the semiconductor substrate. A second source gas enters the process chamber. The second source gas is excited into a third plasma state having a third energy lower than the second energy. The excited second source gas is applied to the semiconductor substrate to secondarily process the semiconductor substrate.
In a method of processing a semiconductor substrate in accordance with still another embodiment of the present invention, a first source gas enters a process chamber. The first source gas in the process chamber is excited into a first plasma state having a first energy. The excited first source gas is applied to a semiconductor substrate to primarily process the semiconductor substrate. A second source gas is primarily excited into a second plasma state having a second energy. The primarily excited second source gas enters the process chamber. The primarily excited second source gas in the process chamber is secondarily excited into a third plasma state having a third energy higher than the second energy. The secondarily excited second source gas is applied to the semiconductor substrate to secondarily process the semiconductor substrate.
An apparatus for processing a semiconductor substrate in accordance with another embodiment of the present invention includes a process chamber to receive therein a semiconductor substrate. A source gas-supplying unit provides a source gas to the process chamber. A remote plasma-generating unit resides between the source gas-supplying unit and the process chamber to excite the source gas into a first plasma state having a first energy. A direct plasma-generating unit resides within the process chamber to further excite the excited source gas into a second plasma state having a second energy higher than the first energy.
According to certain embodiments of the present invention, source gas excitation into the plasma state supports precise semiconductor processing at a low temperature. Thus, semiconductor-processing efficiency remarkably improves and failure ratios in subsequent processes attenuate.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features and advantages of embodiments the invention will be apparent from the more particular description of preferred aspects of embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the like parts throughout the different views. The drawings are not necessarily to scale, with an emphasis instead upon illustrating principles of embodiments of the invention. In the drawings, the thicknesses of layers are exaggerated for clarity.
FIG. 1 is a cross sectional view illustrating a conventional apparatus for processing a semiconductor substrate using plasma.
FIG. 2 is a schematic cross sectional view illustrating an apparatus to process a semiconductor substrate in accordance with a first embodiment of the present invention.
FIG. 3 is a timing chart illustrating a method of processing a semiconductor substrate using the apparatus in FIG. 2.
FIG. 4 is a schematic cross sectional view illustrating an apparatus to process a semiconductor substrate in accordance with a second embodiment of the present invention.
FIG. 5 is a timing chart illustrating a method of processing a semiconductor substrate using the apparatus in FIG. 4.
FIG. 6 is a schematic cross sectional view illustrating an apparatus to process a semiconductor substrate in accordance with a third embodiment of the present invention.
FIG. 7 is a timing chart illustrating a method of processing a semiconductor substrate using the apparatus in FIG. 6.
FIG. 8 is a flow chart illustrating a method of processing a semiconductor substrate in accordance with a fourth embodiment of the present invention.
FIG. 9 is a flow chart illustrating a method of processing a semiconductor substrate in accordance with a fifth embodiment of the present invention.
FIG. 10 is a flow chart illustrating a method of processing a semiconductor substrate in accordance with a sixth embodiment of the present invention.
FIG. 11 is a flow chart illustrating a method of processing a semiconductor substrate in accordance with a seventh embodiment of the present invention.

DESCRIPTION OF THE EMBODIMENTS

Embodiments of the present invention now will be described more fully with reference to the accompanying drawings. As used herein, it will be understood that when a first element, e.g., a layer, a source, a region or a substrate, is referred to as being “on”, “onto”, “applied to”, or “contacts” in relation to a second element, the first element can be directly on, onto, applied, or contacting the second element or intervening elements therebetween may also be present.

Embodiment 1

FIG. 2 is a schematic cross sectional view illustrating an apparatus to process a semiconductor substrate in accordance with a first embodiment of the present invention.
In FIG. 2, an apparatus 100 in accordance with the present embodiment includes a process chamber 110, a chuck 120, a heater 130, a source-supplying unit 140, a direct plasma-generating unit 150, a remote plasma-generating unit 160 and a vacuum unit 170. In process, direct plasma-generating unit 150 and remote plasma-generating unit 160 operate in serially linked fashion.
Apparatus 100 may include a batch type chamber or single-substrate type chamber. In the present illustration, apparatus 100 includes a single type process chamber 110 but as will be understood and appreciated by those skilled in the art a batch type chamber can be substituted therefor.
Process chamber 110 may have a cylindrical shape and establish a processing space therein to receive a semiconductor substrate W. Chuck 120 supports semiconductor substrate W as positioned in the processing space. Heater 130 heats semiconductor substrate W and may be provided integrally relative to chuck 120. Additionally, a plurality of halogen lamps (not shown) may be provided, e.g., on an inner wall of process chamber 110, to heat process chamber 110.
An exhaust line 112 at one end of the inner wall of process chamber 110 connects to vacuum unit 170 by way of exhaust line 112. Vacuum unit 170 exhausts byproducts and non-reacted gases generated within camber 110 while processing semiconductor substrate W.
Direct plasma-generating unit 150 mounts at an upper face of process chamber 110 and includes a showerhead 152 and a radio frequency (RF) power source 154. Showerhead 152 lies opposite semiconductor substrate W when upon chuck 120. RF power source 154 couples to showerhead 152.
Source-supplying unit 140 provides source gas to process chamber 110 at showerhead 152. Source-supplying unit 140 includes a first source tank 141, a second source tank 142 and a source-supplying line 144. As may be appreciated, source-supplying unit 140 may include additional source tanks as employed in a particular semiconductor processing application.
Source-supplying line 144 extends from showerhead 152 and couples to remote plasma-generating unit 160. Source-supplying line 144, extending upstream from remote plasma-generating unit 160, diverges into a first diverged line 146 and a second diverged line 147. Alternatively, e.g., when source-supplying unit 140 includes additional source tanks, source-supplying line 144 may diverge into additional diverged lines, e.g., each corresponding to one source tank.
First diverged line 146 connects to first source tank 141. Second diverged line 147 connects to second source tank 142. Mass flow controllers 149 lie in series along first and second diverged lines 146 and 147, respectively.
Remote plasma-generating unit 160 includes a remote plasma-generating tube 162 and a microwave generator 164 with tube 162 located between first source-supplying line 144 and first and second diverged lines 146 and 147. Microwave generator 164 connects to remote plasma-generating tube 162.
A utility tank 180 supplies a purge or cleaning gas to process chamber 110 by connection to showerhead 152. Examples of the purge or cleaning gas include, but are not limited to, an inert gas, a hydrogen gas, and the like. Utility tank 180 connects to showerhead 152 through a utility line 182. An additional mass flow controller 149 lies along utility line 182. Alternatively, utility tank 180 may connect to showerhead 152 by way of source-supplying line 144.
A main controller (not shown) controls each mass flow controller 149. Persons skilled in the art are familiar with operation of such a main controller and further discussion thereof is omitted.
Different sources for processing semiconductor substrate W reside in first and second source tanks 141 and 142, respectively. In particular, a first source resides in first source tank 141 and a second source in second source tank 142. The first and second sources may be held in solid, liquid or gaseous states, but desirably discharged from first and second source tanks 141 and 142, respectively, in a gaseous state.
As described above, phases of the first and second sources may vary diversely in operation of apparatus 100 and persons skilled in the art will readily understand acceptable the phases of the first and second sources from the following illustrations without limiting implementation to particular examples shown herein.
The first and second sources may be diversely selected in processing semiconductor substrate W. For example, to form a silicon oxide layer on semiconductor substrate W, a silane (SiH₄) gas serves as the first source and an oxygen (O₂) gas serves as the second source. To form a titanium layer on semiconductor substrate W, a TiCl₄gas serves as the first gas and a hydrogen (H₂) gas serves as the second source. Also, to form a titanium nitride layer on the semiconductor substrate W, a TiCl₄gas serves as the first gas and an NH₄gas serves as the second source.
Other processes applicable semiconductor substrate W under embodiments of the present invention include but are not limited to a deposition process, an etching process, a photolithography process, a polishing process, and the like. Accordingly, first and second sources may be selected from a broad variety of materials accordingly to particular applications and processes as will be appreciated and understood by those skilled in the art, and in accordance with the variety of processes as disclosed in many known and available publications
FIG. 3 is a timing chart illustrating a method of processing a semiconductor substrate using the apparatus of FIG. 2.
In FIGS. 2 and 3, to form a titanium layer on semiconductor substrate W, for example, TiCl₄gas serves as the first source and hydrogen gas serves as the second source.
The TiCl₄gas originates from first source tank 141 and flows to remote plasma-generating tube 162 through mass flow controller 149. Microwave generator 164 applies microwave energy, e.g., of about 2 kW to about 2.8 kW at a frequency of about 0.05 GHz to about 2.45 GHz, to remote plasma-generating tube 162 to generate a first electric field with high potential difference in remote plasma-generating tube 162. The first electric field thereby excites the TiCl₄gas into a first plasma state having a first energy.
The TiCl₄gas having the first energy flows from remote plasma-generating tube 162 to showerhead 152 through source-supplying line 144. RF power source 154 applies RF energy, e.g., of about 50 W to about 2,000 W at a frequency of about 0.05 MHz to about 13.56 MHz, to showerhead 152 to generate a second electric field having a high potential difference in showerhead 152. The second electric field excites the TiCl₄gas, already at the first energy, into a second plasma state having a second energy higher than the first energy. The TiCl₄gas is thereby twice excited upon reaching the second energy.
The TiCl₄gas, at the second energy, contacts for a time T1 semiconductor substrate W. Heater 130 heats semiconductor substrate W at a temperature of below about 600° C. Conventionally, when semiconductor substrate W is heated at a temperature of no less than about 600° C., a layer on semiconductor substrate W is deteriorated due to the high thermal energy. The deteriorated layer may be deformed in a following process.
Preferably, semiconductor substrate W has a lower temperature. However, when processing semiconductor substrate W at a temperature of below about 150° C., a reaction ratio of the TiCl₄gas may undesirably decrease. Accordingly, processing semiconductor substrate W at a temperature of about 150° C. to about 550° C., more preferably about 200° C. to about 500° C., has been found desirable. Those skilled in the art will appreciate suitable selection of a processing temperature for semiconductor substrate W in relation to the energy of the TiCl₄gas.
Heater 130 heats the surroundings of semiconductor substrate W as well as semiconductor substrate W. Although illustrations of embodiments of the present invention focus on the temperature of semiconductor substrate W, it will be appreciated by persons skilled in the art that an inside temperature of process chamber 110 may be substantially similar to that of semiconductor substrate W.
Heated TiCl₄gas, having the second energy, is applied to a surface of semiconductor substrate W to absorb TiCl_x(x=1 to 4) on semiconductor substrate W. Vacuum unit 170 exhausts for a time T2 a non-reacted TiCl₄gas and byproducts from process chamber 110.
Hydrogen gas flows from second source tank 142 to remote plasma-generating tube 162 through mass flow controller 149. Microwave generator 164 applies a microwave energy, e.g., of about 2 kW to about 2.8 kW at a frequency of about 0.05 GHz to about 2.45 GHz, to remote plasma-generating tube 162 to generate a third electric field with a high potential difference in remote plasma-generating tube 162. The hydrogen gas is exposed to the third electric field and thereby excited into a third plasma state having a third energy. The third energy may be substantially similar to or different from the first energy. Also, in the present embodiment, the third energy is not necessarily related in sequence or magnitude to the first energy.
The hydrogen gas, having the third energy, flows from remote plasma-generating tube 162 to showerhead 152 through source-supplying line 144. RF power source 154 applies an RF energy, e.g., of about 50 W to about 2,000 W at a frequency of about 0.05 MHz to about 13.56 MHz, to showerhead 152, thereby generating a fourth electric field having a high potential difference in showerhead 152. The hydrogen gas, having the third energy, is exposed to the fourth electric field and excited therefrom into a fourth plasma state having a fourth energy higher than the third energy. In other words, the hydrogen gas is twice excited upon reaching the fourth energy. Here, the fourth energy is not necessarily related in sequence or magnitude relative to the second energy.
The hydrogen gas, having the fourth energy, contacts for a time T3 semiconductor substrate W. Heater 130 heats semiconductor substrate W at a temperature of below about 600° C. When semiconductor substrate W is heated at a temperature of no less than about 600° C., a layer on semiconductor substrate W is deteriorated due to the high thermal energy. Semiconductor substrate W is heated preferably at a temperature of about 150° C. to about 550° C., more preferably about 200° C. to about 500° C. A suitable temperature of semiconductor substrate W will be understood by persons skilled in the art in accordance with the energy of the hydrogen gas.
The heated hydrogen gas having the fourth energy reacts with TiClx (x=1 to 4) to generate an HCl gas. As a result, a titanium layer is formed on semiconductor substrate W. Vacuum unit 170 exhausts for a time T4 any non-reacted TiCl₄gas and byproducts from process chamber 110.
The process performed from time T1 to T4 corresponds to one cycle. When such cycle repeats a selected number of iterations, the thickness of the resulting titanium layer is precisely established in units of atomic layer.
Conventionally, a deposition process using plasma may be carried out at a temperature of no less than about 600° C. The temperature of semiconductor substrate W corresponds to a processing temperature at which deposition occurs. Accordingly, the temperature of semiconductor substrate W has great influence on characteristics of a layer so deposited.
According to the present embodiment, however, the temperature of semiconductor substrate W can be well below about 600° C. The potential reduction of reaction ratio between the sources, e.g., due to the decrease in temperature of semiconductor substrate W, may be compensated by increased of energies of the first and second sources.
Although a titanium layer formed by an atomic layer deposition (ALD) process is illustrated an a example embodiment of the present invention, persons skilled in the art will readily appreciate application of various embodiments of the present invention to, for example, an etching process, a photolithography process, a polishing process, and the like.

Embodiment 2

FIG. 4 is a schematic cross sectional view illustrating an apparatus for processing a semiconductor substrate in accordance with a second embodiment of the present invention.
In FIG. 4, apparatus 200 includes architecture and particular elements similar to those of apparatus 100, but with a modified remote plasma-generating unit. FIG. 4 includes similar reference numerals referring to such similar elements and further discussion of such similar elements is omitted.
In FIG. 4, an apparatus 200 in accordance with the present embodiment includes a process chamber 110, a chuck 120, a heater 130, a source-supplying unit 140, a direct plasma-generating unit 150, a remote plasma-generating unit 260 and a vacuum unit 170. In operation, e.g., during substrate W processing, direct plasma-generating unit 150 and remote plasma-generating unit 260 couple in serially linked fashion.
A source-supplying line 244 extending upstream from showerhead 152 diverges into a first diverged line 246 and a second diverged line 247. First diverged line 246 connects to first source tank 141. Second diverged line 247 connects to second source tank 142. Mass flow controllers 149 each lie along first and second diverged lines 246 and 247, respectively.
Remote plasma-generating unit 260 operates between first source tank 141 and showerhead 152. Remote plasma-generating unit 260 includes a remote plasma-generating tube 262 and a microwave generator 264. Remote plasma-generating tube 262 mounts along on first diverged line 246. Microwave generator 264 couples to remote plasma-generating tube 262.
In this particular embodiment, remote plasma-generating unit 260 applies to only first diverged line 246 and excites only the first source into a plasma state. Thus, remote plasma-generating unit 260 of this particular embodiment may have a scale and volume less than that of remote plasma-generating unit 160 in Embodiment 1.
FIG. 5 is a timing chart illustrating a method of processing a semiconductor substrate W using the apparatus of FIG. 4.
In FIGS. 4 and 5, a first source originates in first source tank 141 and flows to remote plasma-generating tube 262 by way of mass flow controller 149. Microwave generator 264 applies microwave energy to remote plasma-generating tube 262 and generates a first electric field having a high potential difference in remote plasma-generating tube 262. The first electric field excites the first source into a first plasma state having a first energy.
The first source, having the first energy, flows from remote plasma-generating tube 262 to showerhead 152 through source-supplying line 244. RF power source 154 applies RF energy to showerhead 152 and generates a second electric field having a high potential difference in showerhead 152. The first source, having the first energy but exposed to the second electric field, becomes excited into a second plasma state having a second energy higher than the first energy.
The first source, having the second energy, applies for a time T1 to semiconductor substrate W. Heater 130 heats semiconductor substrate W at a temperature of below about 600° C. Process temperature selection of semiconductor substrate W is illustrated and described in Embodiment 1 and any further illustrations and discussion with respect to temperature of semiconductor substrate W are omitted.
The heated first source, having the second energy, contacts a surface of the semiconductor substrate W and atoms in the first source absorb onto semiconductor substrate W. Vacuum unit 170 exhausts for a time T2 any non-reacted first source and byproducts from process chamber 110.
The second source flows from second source tank 142 to showerhead 152 through source-supplying line 244. RF power source 154 applies RF energy to showerhead 152 and generates a third electric field having a high potential difference in showerhead 152. The second source, having the second energy and exposed to the third electric field, moves to a third plasma state having a third energy lower than the second energy. Thus, the first source is twice excited into the second plasma state while the second source is once excited into the third plasma state. As a result, the third energy of the second source may be lower than the second energy of the first source.
The second source, having the third energy, contacts for a time T3 the semiconductor substrate. Heater 130 heats semiconductor substrate W at a temperature of below about 600° C. The temperature of semiconductor substrate W is illustrated and discussed in Embodiment 1 and any further illustrations or discussions thereof are omitted.
The heated second source, having the third energy, reacts with atoms of the first source and forms a layer on semiconductor substrate W. Vacuum unit 170 exhausts for a time T4 any non-reacted second source and byproducts from process chamber 110.
According to the present embodiment, the first source is twice excited and the second source is once excited. Accordingly, the remote plasma-generating unit may have a relatively reduced scale and a volume compared to that in Embodiment 1. Furthermore, the increased energy of the first source alleviates potential reduction of the reaction ratio between the sources, e.g., reduction due to decrease of the temperature of semiconductor substrate W. As a result, apparatus 200 of the present embodiment enjoys improved efficiency in semiconductor substrate processing.

Embodiment 3

FIG. 6 is a schematic cross sectional view illustrating an apparatus for processing a semiconductor substrate in accordance with a third embodiment of the present invention.
An apparatus 300 in accordance with the present embodiment includes elements substantially similar to those of apparatus 100 in Embodiment 1 except for a modified remote plasma-generating unit. Thus, similar reference numerals refer to similar elements and any further discussion of such similar elements will be omitted.
In FIG. 6, apparatus 300 in accordance with the present embodiment includes a process chamber 110, a chuck 120, a heater 130, a source-supplying unit 140, a direct plasma-generating unit 150, a remote plasma-generating unit 360 and a vacuum unit 170. In operation, e.g., during substrate W processing, direct plasma-generating unit 150 and remote plasma-generating unit 360 couple in serially linked fashion.
A source-supplying line 344 extends from showerhead 152 and diverges into a first diverged line 346 and a second diverged line 347. First diverged line 346 connects to first source tank 141. Second diverged line 347 connects to second source tank 142. Mass flow controllers 149 reside each along first and second diverged lines 346 and 347, respectively.
Remote plasma-generating unit 360 operates between second source tank 142 and showerhead 152. Remote plasma-generating unit 360 includes a remote plasma-generating tube 362 and a microwave generator 364. Remote plasma-generating tube 362 mounts along second diverged line 347. Microwave generator 364 couples to remote plasma-generating tube 362.
In the present embodiment, remote plasma-generating unit 360, as coupled only to second diverged line 347, excites only the second source into a plasma state. Accordingly, remote plasma-generating unit 360 of the present embodiment may have a scale and volume less than that of remote plasma-generating unit 160 of Embodiment 1.
FIG. 7 is a timing chart illustrating a method of processing a semiconductor substrate using the apparatus in FIG. 6.
In FIGS. 6 and 7, a first source flows from first source tank 141 to showerhead 152 by way of mass flow controller 149. RF power source 154 applies RF energy to showerhead 152 and generates a first electric field having a high potential difference in showerhead 152. The first electric field excites the first source into a first plasma state having a first energy.
The first source, having the first energy, contacts for a time T1 semiconductor substrate W. Heater 130 heats semiconductor substrate W at a temperature of below about 600° C. The temperature of semiconductor substrate W is illustrated and discussed in relation to Embodiment 1 and any further illustrations and discussion with respect to the temperature of semiconductor substrate W are omitted.
The first source, having the first energy, contacts a surface of semiconductor substrate W and atoms in the first source absorb onto semiconductor substrate W. Vacuum unit 170 exhausts for a time T2 any non-reacted first source and byproducts from process chamber 110.
The second source flows from second source tank 142 to remote plasma-generating tube 362. Microwave generator 364 applies microwave energy to remote plasma-generating tube 362 and generates a second electric field having a high potential difference in remote plasma-generating tube 362. The second source, being exposed to the second electric field, achieves a second plasma state having a second energy higher than the first energy therefor.
The second source, at the second energy, flows from remote plasma-generating tube 362 to showerhead 152 through source-supplying line 344. RF power source 154 applies RF energy to showerhead 152 and generates a third electric field having a high potential difference in showerhead 152. The second source, having the second energy and exposed to the third electric field, reaches a third plasma state having a third energy higher than the second energy. The second source is thereby twice excited in reaching the third plasma state.
The second source, having the third energy, contacts for a time T3 semiconductor substrate W. The second source, having the third energy, reacts with atoms of the first source to form a layer on semiconductor substrate W. Vacuum unit 170 exhausts for a time T4 any non-reacted second source and byproducts from process chamber 110.
According to the present embodiment, the second source is twice excited and the first source is once excited whereby remote plasma-generating unit may have a relatively reduced scale and volume as compared to that of Embodiment 1. Also, reaction ratio reduction, e.g., between the sources due to a decreased semiconductor substrate W temperature, is alleviated by the increased energy of the second source. As a result, apparatus 300 of the present embodiment offers improved semiconductor processing efficiency.

Embodiment 4

FIG. 8 is a flow chart illustrating a method of processing a semiconductor substrate in accordance with a fourth embodiment of the present invention.
In step S110 of FIG. 8, a source for processing a semiconductor substrate is excited into a first plasma state having a first energy. In step S120, the source having the first energy is provided to a process chamber. In step S130, the source having the first energy in the process chamber is excited into a second plasma state having a second energy higher than the first energy. In step S140, the source having the second energy is applied to a surface of the semiconductor substrate to process the semiconductor substrate.
The method of the present embodiment may be employed in a deposition process, an etching process, an ashing process, a photolithography process, a polishing process, and the like. Particularly, the method of the present embodiment may be employed in a plasma-enhanced chemical vapor deposition (PE-CVD) process, an atomic layer deposition (ALD) process, a chemically etching process, an etching process using ions, an etching process using ion collisions and side protection layers.
The source may include at least one gas. Also, the source may be diversely selected in accordance with various semiconductor substrate processes. For example, to form a silicon oxide layer on the semiconductor substrate, a silane (SiH₄) gas and an oxygen (O₂) gas may be selected as the source. To form a titanium layer on the semiconductor substrate, a TiCl₄gas and a hydrogen (H₂) gas may be selected as the source. To form a titanium nitride layer on the semiconductor substrate, a TiCl₄gas and an NH₄gas may be selected as the source. To form a tungsten layer on the semiconductor substrate, a WF₆gas and a hydrogen gas may be selected as the source. Also, to ash a photoresist film on the semiconductor substrate, an oxygen gas may be selected as the source.
Particularly, in step S110, the source may be excited into the first plasma state having the first energy using a remote plasma-generating unit. The remote plasma-generating unit applies, for example, microwave energy to the source to excite the source into the first plasma state having the first energy, e.g., microwave energy having about 2 kW to about 2.8 kW and a frequency of about 0.05 GHz to about 2.45 GHz. Also, when the source includes at least two gases, the gases may be sequentially provided to the remote plasma-generating unit.
Other energy sources, as well as a microwave source, may be used to excite the source into the first plasma state having the first energy as will be appreciated by those persons of skill in the art.
In step S120, the source having the first energy is provided, e.g., from outside the process chamber, to inside of the process chamber.
In step S130, the source having the first energy is excited into the second plasma state having the second energy using, for example, a direct plasma-generating unit. The direct plasma-generating unit applies, for example, RF energy to the source and excites the source into a second plasma state having the second energy. The RF energy may have about 50 W to about 2,000 W at a frequency of about 0.05 MHz to about 13.56 MHz. Other devices, e.g., as well as an RF energy device, may be used to excite the source into the second plasma state as will be appreciated by those skilled in the art.
In step S140, the source having the second energy contacts the surface of the semiconductor substrate in processing the semiconductor substrate. The semiconductor substrate is heated to a temperature of below about 600° C. When the semiconductor substrate is heated at a temperature of no less than about 600° C., a layer on the semiconductor substrate can deteriorate due to high thermal energy. The deteriorated layer may be undesirably deformed in a following process. Accordingly, the semiconductor substrate has preferably a lower temperature during processing. However, when the semiconductor substrate is heated at a temperature of below about 150° C., a reaction ratio of the source may be reduced. As a result, the semiconductor substrate is heated preferably at a temperature of about 150° C. to about 550° C., more preferably about 200° C. to about 500° C. A processing temperature of the semiconductor substrate may be selected by a person skilled in the art in accordance with the energy of the source.
The process chamber as well as the semiconductor substrate is heated. To suppress heat exchange between the process chamber and the semiconductor substrate, the process chamber may have a temperature substantially identical to that of the semiconductor substrate.
Generally, a deposition process using plasma has been carried out at a temperature of no less than about 600° C. The temperature of the semiconductor substrate corresponds to a processing temperature at which the deposition occurs and the temperature of the semiconductor substrate has a great influence on characteristics of a layer.
According to embodiments of the present embodiment, the temperature of the semiconductor substrate is below about 600° C. Increased source energy compensates for potential reduction of reaction ratio between the sources, e.g., due to the decrease of the temperature of the semiconductor substrate. As a result, precise semiconductor substrate processing is achieved.

Embodiment 5

FIG. 9 is a flow chart illustrating a method of processing a semiconductor substrate in accordance with a fifth embodiment of the present invention.
In step S210 of FIG. 9, a first source for processing a semiconductor substrate is excited into a first plasma state having a first energy. In step S215, the first source having the first energy is provided to a process chamber. In step S220, the first source having the first energy in the process chamber is excited into a second plasma state having a second energy higher than the first energy. In step S225, the first source having the second energy is then applied to a surface of the semiconductor substrate to process the semiconductor substrate. In step S230, a non-reacted first source and byproducts are exhausted from the process chamber.
In step S235, a second source for processing the semiconductor substrate is excited into a third plasma state having a third energy. In step S240, the second source having the third energy is provided to the process chamber. In step S245, the second source having the third energy is excited into a fourth plasma state having a fourth energy higher than the third energy. In step S250, the second source having the fourth energy is provided to the surface of the semiconductor substrate to process the semiconductor substrate. In step S255, a non-reacted second source and byproducts are exhausted from the process chamber. The above steps S210 to S255 may be repeated as indicated in S260.
As described above, the second energy is higher than the first energy and the fourth energy is higher than the third energy. The first energy and the third energy may be substantially similar to each other or different from each other. Also, the second energy and the fourth energy may be substantially similar to each other or different from each other. In the present embodiment, the first energy is not necessarily related in sequence or magnitude relative to the third energy and the fourth energy is not necessarily related in sequence or magnitude relative to the second energy.
The method of the present embodiment may be employed, for example, in a deposition process, an etching process, an ashing process, a photolithography process, a polishing process, and the like. In the present embodiment, the method is exemplarily employed in a deposition process for forming a titanium nitride layer by an ALD process.
To form the titanium nitride layer on the semiconductor substrate, a TiCl₄gas is used as the first source and an NH₄gas is used as the second source. The TiCl₄gas having the second energy is applied to the semiconductor substrate to absorb TiClx (x=1 to 4) on the semiconductor substrate. The semiconductor substrate is heated to a temperature of below about 600° C., preferably about 150° C. to about 550° C. The temperature of the semiconductor substrate is illustrated and discussed in relation to Embodiment 1 and need not be further illustrated and discussed here.
The NH₄gas having the fourth energy is provided to the surface of the semiconductor substrate. The NH₄gas is reacted with TiClx (x=1 to 4) to generate an HCl gas. As a result, a titanium nitride layer forms on the semiconductor substrate. The semiconductor substrate is heated to a temperature of below about 600° C., preferably about 150° C. to about 550° C. The temperature of the semiconductor substrate is illustrated in Embodiment 1 and need not be further detailed here.
By repeating steps S210 to S255, a titanium nitride layer is formed successively in units of atomic layer.
Increased energies of the first and second sources compensate for any reduction of the reaction ratio between the first and second sources, e.g., reduced reaction ratio due to decreased of the temperature of the semiconductor substrate. In this manner, a semiconductor substrate is precisely processed.

Embodiment 6

FIG. 10 is a flow chart illustrating a method of processing a semiconductor substrate in accordance with a sixth embodiment of the present invention.
The method of the present embodiment is substantially similar to that in Embodiment 5 except in regard to exciting a second source.
In FIG. 10, steps S310-330 correspond to steps S210-S230 of FIG. 9 as discussed above. In step S335, a second source is provided to the process chamber, but not excited into a plasma state.
In step S340, the second source is excited into a third plasma state having a third energy. In step S345, the second source having the third energy is applied to the surface of the semiconductor substrate to process the semiconductor substrate. In step S350, a non-reacted second source and byproducts are exhausted from the process chamber. In step S355, steps S310 to S350 may be repeatedly a selected number of times as desired.
The second energy is higher than the first energy and the third energy may be lower than the second energy. Here, the third energy may be substantially similar to or different from the first energy. In the present embodiment, the first energy is not necessarily related in sequence or magnitude relative to the third energy.
The method of the present embodiment may be employed, for example, in a deposition process, an etching process, an ashing process, a photolithography process, a polishing process, and the like. In the present embodiment, the method is exemplarily employed in a deposition process for forming a titanium nitride layer by an ALD process.
The reduction of the reaction ratio between the first and second sources, e.g., due to a decreased temperature of the semiconductor substrate, is compensated by an increased energy of the first source. Also, power used to increase the energy of the second source may be reduced relative to that of other embodiments. Thus, the remote plasma-generating unit may have a reduced scale volume for improved efficiency.

Embodiment 7

FIG. 11 is a flow chart illustrating a method of processing a semiconductor substrate in accordance with a seventh embodiment of the present invention.
The method of the present embodiment is substantially similar to that in Embodiment 5 except in regard to exciting a first source.
In step S410 of FIG. 11, a first source is provided to a process chamber. In step S415, the first source in the process chamber is excited into a first plasma state having a first energy. In step S420, the first source having the first energy is applied to a surface of the semiconductor substrate to process the semiconductor substrate. In step S425, a non-reacted first source and byproducts are exhausted from the process chamber.
In step S430, a second source is excited into a second plasma state having a second energy. In step S435, the second source having the second energy is provided to the process chamber. In step S440, the second source having the second energy is excited into a third plasma state having a third energy. In step S445, the second source having the third energy is applied to the surface of the semiconductor substrate to process the semiconductor substrate. In step S450, a non-reacted second source and byproducts are exhausted from the process chamber. The above steps S410 to S450 are repeated a selected number of times as desired.
The second energy may be higher than the first energy and the third energy may be lower than the second energy. The third energy may be substantially similar to or different from the first energy. In this embodiment, the first energy is not necessarily related in sequence or magnitude relative to the third energy.
The method of the present embodiment may be employed, for example, in a deposition process, an etching process, an ashing process, a photolithography process, a polishing process, and the like. In the present embodiment, the method is exemplarily employed in a deposition process for forming a titanium nitride layer by an ALD process.
Reduced reaction ratio between the first and second sources, e.g., due to decreased temperature of the semiconductor substrate, is alleviated by increased energy of the second source. Power for increasing the energy of the first source may be reduced relative to other embodiments and, therefore, the remote plasma-generating unit may have a reduced scale and volume for improved efficiency.
According to embodiments of the present invention, the source for processing the semiconductor substrate has increased energy and the semiconductor substrate is precisely processed at a relatively low temperature with error ratio in subsequent processes reduced.
Also, the power for increasing the energy of the source may be reduced so that efficiency of the process for processing the semiconductor substrate may be improved.
While embodiments of the present invention have been particularly shown and described by example, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A method of processing a substrate comprising:

providing a source in a first plasma state having a first energy to a process chamber;

exciting the source having the first energy in the process chamber into a second plasma state having a second energy higher than the first energy; and

applying the source having the second energy to the substrate.

2. The method of claim 1 wherein the process chamber is maintained at a temperature below about 600° C.

3. The method of claim 2 wherein the process chamber is maintained at a temperature of about 200° C. to about 500° C.

4. The method of claim 1 wherein the source is excited into the first plasma state having the first energy using a remote plasma-generating unit coupled to the process chamber, and the source having the first energy is excited using a direct plasma-generating unit within the process chamber.

5. The method of claim 1 wherein the source is excited into the first plasma state having the first energy by applying microwave energy to the source, and the source having the first energy is excited by applying a high frequency energy to the source having the first energy.

6. A method of processing a substrate comprising:

providing a first source in a first plasma state having a first energy to a process chamber;

exciting the first source having the first energy in the process chamber into a second plasma state having a second energy higher than the first energy;

applying the first source having the second energy to the substrate;

providing a second source in a third plasma state having a third energy to a process chamber;

exciting the second source having the second energy in the process chamber into a fourth plasma state having a fourth energy higher than the third energy; and

applying the second source having the fourth energy to the substrate;

7. The method of claim 6 wherein providing the first source, exciting the first source, applying the first source, providing the second source, exciting the second source and applying the second source are repeated.

8. The method of claim 6 wherein the first source is excited into the first plasma state having the first energy using a remote plasma-generating unit coupled to the process chamber, the first source having the first energy is excited using a direct plasma-generating unit, the second source is excited into the third plasma state having the third energy using the remote plasma-generating unit, and the second source having the third energy is excited using the direct plasma-generating unit.

9. The method of claim 6 wherein the first source is excited into the first plasma state having the first energy by applying a microwave energy to the first source, the first source having the first energy is excited by applying a high frequency energy to the first source having the first energy, the second source is excited into the third plasma state having the third energy by applying a microwave energy to the second source, and the second source having the third energy is excited by applying a high frequency energy to the second source having the third energy.

10. An apparatus to process a substrate comprising:

a process chamber having a space to process the substrate;

a source-supplying unit to supply a source to the process chamber;

a remote plasma-generating unit, arranged between the source-supplying unit and the process chamber, to excite the source into a first plasma state having a first energy; and

a direct plasma-generating unit arranged to excite in the process chamber the source having the first energy into a second plasma state having a second energy higher than the first energy.

11. The apparatus of claim 10 wherein the remote plasma-generating unit comprises:

a remote plasma-generating tube to receive the source from the source-supplying unit; and

a power source to apply energy to the remote plasma-generating tube to excite the source into the first plasma state having the first energy.

12. The apparatus of claim 11 wherein the power source comprises a microwave generator.

13. The apparatus of claim 10 wherein the direct plasma-generating unit comprises:

a showerhead arranged to receive the source having the first energy from the remote plasma-generating unit; and

a power source to apply an energy to the showerhead to excite the source having the first energy into the second plasma state having the second energy.

14. The apparatus of claim 13 wherein the power source comprises a radio frequency power source.

15. The apparatus of claim 10 wherein the source-supplying unit comprises:

a first source-supplying line to supply a first source; and

a second source-supplying line to supply a second source.

16. The apparatus of claim 15 wherein the remote plasma-generating unit is provided to at least one of the first and second source-supplying lines.

17. The apparatus of claim 10 further comprising a second source-supplying unit, connected to the direct plasma-generating unit, to provide a second source to the process chamber.

18. The apparatus of claim 10 further comprising a heater to heat the substrate.

19. The apparatus of claim 10 further comprising a chuck positioned in the process chamber to support the substrate.

20. The apparatus of claim 10 further comprising a vacuum unit coupled to the process chamber to exhaust byproducts generated in processing the substrate.