# US 5,704,987 A · Process for removing residue from a semiconductor wafer after chemical-mechanical polishing

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- Number: US 5,704,987 A
- Document ID: US5704987A
- Status: Granted
- Kind: A
- Application number: 08/588,943
- Filed: 1996-01-19
- Granted: 1998-01-06
- Earliest claimed: 1996-01-19
- Assignees: International Business Machines Corporation
- Inventors: Cuc Kim Huynh; Matthew Jeremy Rutten; Susan L. Cohen; Douglas Paul Nadeau; Robert Albin Jurjevic; James Albert Gilhooly
- Web page: https://patentgrep.com/patent/US5704987A

## CPC

- B24B 37/04: designed for working plane surfaces
- B08B 1/36: rotating about an axis orthogonal to the surface
- H10P 95/062: {involving a dielectric removal step}
- B24B: MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING (grinding of gear teeth B23F, of screw-threads B23G1/36; by electro-erosion B23H; abrasive or related blasting B24C; tools for grinding, buffing or sharpening B24D; polishing compositions C09G1/00; abrasives C09K3/14; electrolytic etching or polishing C25F3/00; grinding arrangements for use on assembled railway tracks E01B31/17); DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B08B: CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

A method for cleaning the surface of a semiconductor wafer by removing residual slurry particles adhered to the wafer surface after chemical-mechanical polishing is provided. The semiconductor wafer is subjected to a first polishing step using a basic aqueous solution of a nonionic polymeric surfactant comprising alkylphenoxypolyethoxyethanol, preferably nonylphenoxypolyethoxyethanol, at a concentration between about 30 to about 100 ppm and a quaternary ammonium hydroxide such as TMAH at a concentration between about 2.5% and about 6% by weight. A downforce of between about 0 and 2 psi (1.4.times.10.sup.5 dynes/cm.sup.2) is applied for at least 15 seconds. A second polishing step with an applied downforce of at least 4 psi is then employed while applying purified water. The method provides at least a ten fold reduction in the number of submicronic slurry particles remaining on the wafer surface and can be completed within a commercially acceptable amount of time. In addition, particles as small as 0.007 .mu.m can be removed. The method also provides a level of accuracy in the predictability of the number of residual particles remaining on the wafer surface.

## Claims

### Claim 1

A method for removing residual particles from a semiconductor wafer after chemical-mechanical planarization, said wafer being held in a wafer polisher by an oscillating carrier, comprising the steps of:
(a) pressing said semiconductor wafer against a rotating polishing pad with greater than 0 to about 2 psi (1.4.times.10.sup.5 dynes/cm.sup.2) of downforce while applying to said rotating polishing pad an aqueous solution having a pH greater than about 10 for a period of time sufficient to wet said semiconductor wafer surface, said aqueous solution comprising from about 30 to about 100 ppm of a nonionic polymeric surfactant comprising alkylphenoxypolyethoxyethanol characterized by the formula:
C.sub.n H.sub.2n+1 --C.sub.6 H.sub.4 --(OCH.sub.2 CH.sub.2).sub.m OH
wherein n is from 3 to 10 and m is from 8 to 15; and from about 2.5 to about 6% by weight of a quaternary ammonium hydroxide characterized by the formula: ##STR5## wherein R1, R2, R3, and R4 are each independently alkyl groups containing from 1 to 10 carbon atoms; and
(b) pressing said wafer against said rotating polishing pad with at least 4 psi of downforce while applying water.

### Claim 2 (depends on 1)

The method according to claim 1, wherein said aqueous solution has a pH greater than about 12.

### Claim 3 (depends on 1)

The method according to claim 1, wherein said alkylphenoxypolyethoxyethanol polymer comprises nonylphenoxypolyethoxyethanol, and wherein n is equal to 9.

### Claim 4 (depends on 1)

The method according to claim 1, wherein said alkylphenoxypolyethoxyethanol polymer is present at a level of about 50 ppm.

### Claim 5 (depends on 1)

The method according to claim 1, wherein said quaternary ammonium hydroxide is tetramethylammonium hydroxide, and wherein R.sub.1, R.sub.2, R.sub.3, and R.sub.4 are methyl groups.

### Claim 6 (depends on 1)

The method according to claim 1, wherein said quaternary ammonium hydroxide is present at a level of about 4.6% by weight.

### Claim 7 (depends on 1)

The method according to claim 1, wherein said time sufficient to wet said surface of said semiconductor wafer is at least 15 seconds.

### Claim 8 (depends on 1)

The method according to claim 1, wherein said residual particles are selected from the group consisting of inorganic materials, metals, and metal oxides.

### Claim 9 (depends on 1)

The method according to claim 1, wherein said residual particles comprise silicon dioxide.