# US 11,078,380 B2 · Hard abrasive particle-free polishing of hard materials

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- Number: US 11,078,380 B2
- Document ID: US11078380B2
- Status: Granted
- Kind: B2
- Application number: 15/645,777
- Filed: 2017-07-10
- Published: 2019-01-10
- Granted: 2021-08-03
- Earliest claimed: 2017-07-10
- Assignees: Entegris, Inc.; University of Florida Research Foundation, Inc.
- Applicants: Entegris, Inc.; University of Florida Research Foundation, Inc.
- Inventors: Rajiv K. Singh; Arul Arjunan; Deepika Singh; Chaitanya Ginde; Puneet N. Jawali
- Web page: https://patentgrep.com/patent/US11078380B2

## CPC

- C09G 1/02: containing abrasives or grinding agents {(abrasives as such C09K3/14; polishing of semi-conductors H10P52/40)}
- B24B 37/00: Lapping machines or devices; Accessories (B24B3/00 takes precedence)
- B24B 37/044: {characterised by the composition of the lapping agent}
- C09G 1/04: Aqueous dispersions (C09G1/02 takes precedence)
- C09K 3/1409: {Abrasive particles per se (preparation of diamond C01B32/25)}
- H10P 52/402: {of semiconductor materials}
- H10P 52/403: {of conductive or resistive materials}
- H10P 90/129: {by polishing}
- C09G: POLISHING COMPOSITIONS (French polish C09F11/00); SKI WAXES
- 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
- C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

A method of CMP includes providing a slurry solution including ≥1 per-compound oxidizer in a concentration between 0.01 M and 2 M with a pH from 2 to 5 or 8 to 11, and ≥1 buffering agent which provides a buffering ratio ≥1.5 that compares an amount of a strong acid needed to reduce the pH from 9.0 to 3.0 as compared to an amount of strong acid to change the pH from 9.0 to 3.0 without the buffering agent. The slurry solution is exclusive any hard slurry particles or has only soft slurry particles that have throughout a Vickers hardness <300 Kg/mm2 or Mohs Hardness <4. The slurry solution is dispensed on a hard surface having a Vickers hardness >1,000 kg/mm2 is pressed by a polishing pad with the slurry solution in between while rotating the polishing pad relative to the hard surface.

## Claims

### Claim 1

A slurry for chemical-mechanical polishing (CMP), comprising:
an aqueous medium;
at least one pre-compound permanganate oxidizer that includes an element in its highest oxidation state with a concentration between 0.01 M and 2.0 M;
a pH level from 8 to 11;
at least one buffering agent different from said per-compound oxidizer, the buffering agent comprising at least one of a surfactant and an alkali metal ion; and
particles of MnO2 having a Mohs hardness of ≤3,
wherein said slurry is exclusive of any particles that have a Mohs hardness >3.

### Claim 2 (depends on 1)

The slurry of claim 1, wherein said slurry further comprises transition metal ions in a concentration from 0.03 M to 1 M in addition to any transition metal ions that may be in said per-compound permanganate oxidizer.

### Claim 3 (depends on 1)

The slurry of claim 1, wherein said particles of MnO2 having a Mohs hardness ≤3 are particles formed in-situ by autocatalysis.

### Claim 4 (depends on 1)

The slurry of claim 1, wherein said buffering agent comprises said surfactant and at least 2 different valence states of Mn ions including said per-compound permanganate oxidizer chosen from +7, +4, +2, and +3.

### Claim 5 (depends on 1)

The slurry of claim 1, wherein said per-compound permanganate oxidizer comprises potassium permanganate or sodium permanganate.

### Claim 6

A slurry for chemical-mechanical polishing (CMP), comprising:
an aqueous medium;
at least one pre-compound permanganate oxidizer that includes an element in its highest oxidation state with a concentration between 0.01 M and 2.0 M;
a pH level from 2 to 5 or from 8 to 11;
at least one buffering agent different from said per-compound oxidizer, the buffering agent comprising at least one of a surfactant and an alkali metal ion; and
particles of MnO2 having a Mohs hardness of ≤3,
wherein said slurry is exclusive of any particles that have a Mohs hardness >3, and
wherein the buffering agent comprises a species having the formula RCHO, wherein R is a carbon containing group.