WO2000060645A2

WO2000060645A2 - Dual cmp pad conditioner

Info

Publication number: WO2000060645A2
Application number: PCT/US2000/008340
Authority: WO
Inventors: Albert H. Liu; Landon Vines
Original assignee: Koninklijke Philips Electronics N.V.
Priority date: 1999-04-01
Filing date: 2000-03-29
Publication date: 2000-10-12
Also published as: KR20010071353A; WO2000060645A3; CN1362907A; EP1190455A2; JP2002540972A; AU4044400A

Abstract

According to an example embodiment, the present invention is directed to a CMP polishing apparatus (100) having at least two conditioning arms (110+120) for use in conditioning a polishing pad (150). The CMP polishing apparatus includes a first pad conditioner (130) configured and arranged both to dispense slurry and to condition the pad. A second pad conditioner (140) is configured and arranged both to clean a portion of the polishing pad (150) and to dispense cleaning chemicals. Benefits of using this embodiment include enhanced pad cleaning, better slurry dispense, improved wafer quality, and faster production.

Description

DUAL CMP PAD CONDITIONER

Field of the Invention

The present device relates generally to semiconductor devices and their fabrication

and, more particularly, to semiconductor devices and tools for their manufacture involving

chemical-mechanical polishing (CMP).

Background of the invention

The electronics industry continues to rely upon advances in semiconductor

manufacturing technology to realize higher- functioning devices while improving reliability

and cost. For many applications, the manufacture of such devices is complex, and

maintaining cost-effective manufacturing processes while concurrently maintaining or

improving product quality is difficult to accomplish. As the requirements for device

performance and cost become more demanding, realizing a successful manufacturing process

becomes more difficult.

A byproduct of the increased complexity of semiconductor devices includes uneven

device surfaces, which become more prominent as additional levels are added to multilevel-

interconnection schemes and circuit features are scaled to submicron dimensions. Typically,

each level within the device is patterned, resulting in a surface with varied "step-heights"

where metal forming the pattern remains on the surface.

Planarization is a term describing the surface geometry of a semiconductor device.

Complete planarization occurs when the surface of the dielectric is flat, as in a plane. No

planarization occurs when the surface of the dielectric directly models the "step-height"

surface of the metal pattern in the layer underneath. The degree of planarization refers to the degree to which the varied surface geometry can be "planarized," or smoothed out into a

planar surface. Varied surface geometry is often undesirable. Therefore, as additional layers

are formed within devices, the required degree of planarization increases.

A commonly used new planarization process in semiconductor device manufacturing

is chemical-mechanical polishing, or CMP. CMP is useful in the planarization of silicon

wafers and of VLSI circuits between different manufacturing processes. CMP is a popular

planarization method, due in part to its usefulness in the global planarization of

semiconductor devices. Traditional planarization processes are restricted to effecting local

planarity or topographical variation on a small scale, whereas CMP is often useful on a global

scale greater than ten microns.

In one application, a CMP process involves securing a semiconductor wafer to a wafer

holder with the wafer located face-down on a polish pad. Both the polish pad and the wafer

holder rotate. A slurry, typically a colloidal silica that is a suspension of SiO, particles, is

applied to the process. The particle size typically varies from 100 angstroms to 3 microns.

The slurry is generally applied using a wand feeding to the wafer holder and pad. The rate of

removal of material from the wafer is a combination of chemical and mechanical rates. The

mechanical removal rate is roughly proportional to the pressure and the relative velocity of

the wafer. The chemical removal rate is a function of the size of the slurry particles and the

solution pH, wherein the maximum removal rate is generally obtained using a slurry having a

pH of about 11.5.

In addition to the use of slurry in the CMP process, a conditioner is also typically used

for conditioning the polish pad. The conditioner aids in the CMP polishing process and

contributes to the longevity of the pad. Another need in the CMP process is for adequately

and efficiently cleaning the pad and the wafer itself. In clean room environments, it is important to maintain a CMP process that produces as few contaminants as possible. Since

the slurry particle size ranges in the sub-3 micron range, clean-up is difficult and thus of high

importance. In addition, it is helpful to prevent the byproduct resulting from the polishing of

each wafer from accumulating on the pad and reaching additional wafers.

The traditional method for conditioning the pad and dispensing slurry is to use two

separate mechanical components: a slurry dispense wand and a pad conditioner assembly.

There are disadvantages in using two separate components. For instance, separate

components take up more space in the apparatus. Also, the slurry cannot be spread uniformly

across the pad and may accumulate in the pad conditioning head. The non-uniform

distribution of slurry distribution hinders the polishing process. In addition, the reaction

byproduct cannot be thoroughly removed from the pad. When more than one wafer is

processed at once, inadequate cleaning of the pad results in the reaction byproduct and other

materials from one wafer coming into contact with other wafers. These disadvantages may

result in, for example, long arc style scratches, shallow micro-scratches, inter-die thickness

variation, and residual slurry particles. These disadvantages ultimately result in a significant

yield lost and in reliability problems due in part to possible metal stringers in the shallow

scratch area and surrounding residual slurry particles.

Summary of the Invention

The present invention is directed to a method and apparatus for improving the CMP

process, the improvements including but not limited to enhanced pad cleaning and

conditioning, better slurry dispense, improved wafer quality, and faster production. The

present invention is exemplified in a number of implementations and applications, some of

which are summarized below. According to an example embodiment, the present invention includes a CMP

polishing apparatus having at least two conditioning arms for uses including the conditioning

of a polishing pad. The CMP polishing apparatus includes a first pad conditioner configured

and arranged both to dispense slurry and to condition the pad. A second pad conditioner is

configured and arranged both to clean a portion of the polishing pad and to dispense cleaning

chemicals.

According to another example embodiment, the present invention is directed to a

method for conditioning a CMP polishing pad in a CMP polishing apparatus. The CMP

apparatus includes at least two conditioning arms. Slurry is dispensed and the pad is

conditioned using a first pad conditioner coupled to one of the conditioning arms. A portion

of the polishing pad is cleaned using a second pad conditioner coupled to another of the

conditioning arms.

According to yet another example embodiment, the present invention is directed to a

method for CMP, wherein the CMP apparatus includes a polishing pad and at least two

conditioning arms for each semiconductor wafer to be processed. A first semiconductor

wafer is coupled to the CMP apparatus. The pad is conditioned using a first pad conditioner

coupled to a first conditioning arm. A slurry is supplied by way of the first pad conditioner.

Using a second pad conditioner coupled to a second conditioning arm, a first cleaning

material is supplied by way of the second pad conditioner, and a portion of the polishing pad

is cleaned.

According to still another example embodiment, the present invention is directed to a

CMP polishing apparatus having a polishing pad. The apparatus includes means for both

conditioning the polishing pad and supplying slurry, and means for both conditioning the pad

and supplying cleaning material. The above summary of the present invention is not intended to describe each

illustrated embodiment or every implementation of the present invention. The figures and

detailed description which follow more particularly exemplify these embodiments.

Brief Description of the Drawings

The invention may be more completely understood in consideration of the following

detailed description in connection with the accompanying drawings, in which:

FIG. 1 shows an arrangement for a CMP process for polishing a semiconductor wafer,

according to an example embodiment of the present invention;

FIG. 2 shows an arrangement for a CMP process for polishing two semiconductor

wafers, according to another example embodiment of the present invention; and

FIG. 3 shows an arrangement for a CMP process for polishing a semiconductor wafer,

according to another example embodiment of the present invention.

While the invention is amenable to various modifications and alternative forms,

specifics thereof have been shown by way of example in the drawings and will be described

in detail. It should be understood, however, that the intention is not to limit the invention to

the particular embodiments described. On the contrary, the intention is to cover all

modifications, equivalents, and alternatives falling within the spirit and scope of the invention

as defined by the appended claims.

Detailed Description

According to an example embodiment, the present invention makes possible the use

of a single apparatus both for supplying slurry and for conditioning the pad in a CMP process.

In addition, a single apparatus may be used both for supplying cleaning material and for conditioning the pad in the CMP process. The use of these apparatuses displaces the need for

a dispensing wand for the dispense of materials including slurry and cleaning materials, such

as de-ionized water and other materials used in conventional CMP processes.

Referring now to FIG. 1, and according to another example embodiment, the present

invention is directed to an apparatus 100 for CMP. The apparatus 100 has at least two

conditioning arms 110 and 120 for uses including the conditioning of a polishing pad 150.

The polishing pad 150 is configured and arranged to rotate. In addition, conditioning arms

110 and 120 are configured and arranged to move in a direction generally tangential to the

rotation of the polishing pad 150. The CMP polishing apparatus 100 includes a first pad

conditioner 130 configured and arranged both to dispense slurry and to condition the pad. A

second pad conditioner 140 is configured and arranged to clean a portion of the polishing pad

and to dispense cleaning materials. A wafer holder 160 is configured and arranged to hold a

semiconductor wafer face-down on the polishing pad 150.

The first pad conditioner 130 and the second pad conditioner 140 may be configured

to condition and clean in a number of ways. For instance, the pad conditioners may include

rotating means, such as bearings, wheels, and bushings. For effecting rotation, the rotating

means may be coupled to devices such as gears, belts, pulleys, and direct drives. In addition,

the pad conditioners may comprise a shower head type design, allowing material to be added

uniformly over the CMP pad. The pad conditioners may also contain items such as brushes

or grids for contacting the pad and aiding in conditioning, cleaning, and disbursement of

materials such as cleaning materials or slurry.

In another example embodiment, cleaning or polishing materials are supplied to the

pad conditioners using supply lines coupled to the pad conditioners. Such supply lines may

include, for example, flexible tubing of plastic, metal, or other suitable material. The supply lines may be coupled to the pad conditioners in an appropriate manner, such as using fixed or

flexible couplings. In addition, multiple fluids may be supplied to an individual pad

conditioner. For example, such multiple fluids may be supplied individually, pre-mixed,

mixed in the pad conditioner itself, or mixed in the supply lines using devices such as mixing

tubes.

FIG. 2 shows an apparatus 200 for CMP, according to another example embodiment

of the present invention. FIG. 2 includes all of the embodiments illustrated by FIG. 1, and

adds the ability to perform the CMP process on an additional semiconductor wafer. The

apparatus 200 has at least two additional conditioning arms 210 and 220 for use including

conditioning of the polishing pad 150. The additional conditioning arms 210 and 220 are

configured and arranged to move in a direction generally tangential to the rotation of the

polishing pad 150. The CMP polishing apparatus 200 includes a third pad conditioner 230

configured and arranged both to dispense slurry and to condition the pad. A fourth pad

conditioner 240 is configured and arranged to clean a portion of the polishing pad and to

dispense cleaning chemicals. A second wafer holder 260 is configured and arranged to hold a

second semiconductor wafer face-down on the polishing pad 150. In addition, at least one of

the pad conditioners and the wafer holder may further be configured and arranged to rotate.

FIG. 3 shows an apparatus 300 for CMP, according to another example embodiment

of the present invention. The apparatus 300 has at least two conditioning arms 310 and 320

for use including the conditioning of a polishing belt 350. The polishing belt 350 is

configured and arranged to move relative to the conditioning arms. In addition, the

conditioning arms are configured and arranged to move in a direction generally perpendicular

to the movement of the belt. The CMP polishing apparatus 300 includes a first belt

conditioner 330 configured and arranged both to dispense slurry and to condition the belt. A second belt conditioner 340 is configured and arranged to clean a portion of the polishing belt

and to dispense cleaning materials. A wafer holder 360 is configured and arranged to hold a

semiconductor wafer face-down on the polishing belt 350. In addition, at least one of the belt

conditioners and the wafer holder may further be configured and arranged to rotate.

According to another example embodiment, the present invention is directed to a

apparatus has at least two conditioning arms. Slurry is dispensed and the pad is conditioned

using a first pad conditioner coupled to one of the conditioning arms. A portion of the

polishing pad is cleaned using a second pad conditioner coupled to another of the

conditioning arms.

For instance, referring to FIG. 1, a semiconductor wafer is attached to a wafer holder

160, and is held face-down against a polishing pad 150. The polishing pad is caused to rotate,

as shown by arrow 170. Conditioning arm 110 is moved in a direction about generally

tangential to the rotation of the polishing pad 150, which is depicted with arrow 180 in FIG.

1. Pad conditioner 130 is used to dispense slurry for the CMP process to be performed on the

wafer, and to condition the pad 150. Conditioning arm 120 is also moved in a direction about

generally tangential to the rotation of the polishing pad 150, as depicted with arrow 190 in

FIG. 1. Pad conditioner 140 is used to dispense cleaning materials, remove any excess slurry,

used slurry, and reaction byproduct, and to condition the pad. In addition, at least one of the

pad conditioners and the wafer holder may further be configured and arranged to rotate.

In another example embodiment, and referring to FIG. 2, two semiconductor wafers

are processed in a CMP apparatus. A second semiconductor wafer is attached to a wafer

holder 260, and is held face-down against a polishing pad 150. The polishing pad is caused

to rotate as shown by arrow 170. As in the preceding example embodiment, conditioning arm 110 is moved in a direction about generally tangential to the rotation of the polishing pad 150,

which is depicted with arrow 180 in FIG. 1. Pad conditioner 130 is used to dispense slurry

for the CMP process to be performed on the wafer, and to condition the pad 150.

Conditioning arm 120 is also moved in a direction about generally tangential to the rotation

of the polishing pad 150, as depicted with arrow 190 in FIG. 1. Pad conditioner 140 is used

to dispense cleaning materials, remove excess slurry, used slurry, and reaction byproduct, and

to condition the pad. Pad conditioner 140 may, for example, remove these materials and

thereby prevent about all them from reaching the second wafer attached to wafer holder 260.

The second semiconductor wafer is processed similarly to the first. Conditioning arm

210 is moved in a direction about generally tangential to the rotation of the polishing pad 150,

which is depicted with arrow 280 in FIG. 2. Pad conditioner 230 is used to dispense slurry

for the CMP process to be performed on the second wafer, and to condition the pad 150.

Conditioning arm 220 is also moved in a direction about generally tangential to the rotation

of the polishing pad 150, as depicted with arrow 290 in FIG. 2. Pad conditioner 240 is used

to condition the pad. Pad conditioner 240 may remove this material such that about all of the

material is prevented from reaching the first wafer held by the first wafer holder 160. In

addition, at least one of the pad conditioners and the wafer holder may further be configured

and arranged to rotate.

In another example embodiment, and according to FIG. 3, the present invention is

directed to a method for conditioning a CMP polishing belt in a CMP. A semiconductor

wafer is attached to a wafer holder 360, and is held face-down against a polishing belt 350.

The polishing belt is caused to move as shown by arrow 370 in FIG. 3. Conditioning arm

310 is moved in a direction about generally perpendicular to the polishing belt 350, which is depicted with arrow 380 in FIG. 3. Pad conditioner 330 is used to dispense slurry for the

CMP process to be performed on the wafer, and to condition the belt 350. Conditioning arm

320 is also moved in a direction about generally perpendicular to the movement of the

polishing belt 350, as depicted with arrow 390 in FIG. 3. Pad conditioner 340 is used to

dispense cleaning materials, remove any excess slurry, used slurry, and reaction byproduct,

and to condition the belt. Again, at least one of the pad conditioners and the wafer holder

may further be configured and arranged to rotate.

The disclosed methods of CMP have many advantages. For instance, the distribution

of the slurry may be made more uniform. In addition, excessive slurry, used slurry, and the

reaction byproduct can be completely removed from the pad. The removal of these materials

is particularly advantageous because, when this process is used with multiple semiconductor

wafers, the materials can be removed prior to their reaching another wafer.

Many other beneficial results occur using various embodiments of the invention

described herein. For instance, results may include more thorough conditioning of the pad

and better cleaning of the pad after polishing processes. The life for the pad and the

conditioner grid are extended, which results in lowering the die cost and increasing the

profitability. The polish rate becomes more uniform. The occurrence of scratches, such as

long-arc type scratches and shallow micro-scratches, is reduced. In addition, residue slurry is

reduced, decreasing particle defects as a result of such residue, which results in lowering the

defect density, increasing the die sort yield and improving the die reliability. Additional

capabilities are also provided, including the use of multiple chemicals with each individual

conditioning pad.

Skilled artisans will recognize that the above-discussed example embodiments may be

implemented by modifying commercially-available equipment. Examples of such equipment include MIRRA and 6DS SP, respectively manufactured by Applied Material and

Strausbaugh.

While the present invention has been described with reference to several particular

example embodiments, those skilled in the art will recognize that many changes may be made

thereto. Fox example, many features of the above embodiments are combinable in a single

conditioner arrangement and/or conditioning process. Such changes do not depart from the

spirit and scope of the present invention, which is set forth in the following claims.

Claims

What is claimed is:

1. A CMP polishing apparatus having at least two conditioning arms and a polishing

pad, the CMP polishing apparatus comprising:

a first pad conditioner configured and arranged to dispense slurry and to condition the

pad; and,

a second pad conditioner configured and arranged to clean and condition a portion of

the pad and to dispense cleaning materials.

2. A CMP polishing apparatus, according to claim 1 , wherein the first pad conditioner is

implemented in place of a wand for dispensing of materials including slurry and cleaning

materials.

3. A CMP polishing apparatus, according to claim 1, wherein the pad conditioners

include a head adapted to shower materials through holes in the head.

4. A CMP polishing apparatus, according to claim 1, wherein at least one of the pad

conditioners includes means for rotation.

5. A CMP polishing apparatus, according to claim 1, wherein at least one of the pad

conditioners include means for cleansing.

6. A CMP polishing apparatus, according to claim 5, wherein the means for cleansing

includes at least one brush.

7. A CMP polishing apparatus, according to claim 5, wherein the means for cleansing

includes at least one grid conditioner.

8. A CMP polishing apparatus, according to claim 1, wherein at least one of the

conditioning arms include means for supplying fluid or gas agent.

9. A CMP polishing apparatus, according to claim 1, wherein at least one of the

conditioning arms include means for supplying at least two different fluids or gases.

10. A CMP polishing apparatus, according to claim 1, wherein the polishing pad includes

a belt.

11. A CMP polishing apparatus, according to claim 1 , wherein the polishing pad includes

a disk.