# US 10,479,938 B2 · Removing polysilicon

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- Number: US 10,479,938 B2
- Document ID: US10479938B2
- Status: Granted
- Kind: B2
- Application number: 16/018,437
- Filed: 2018-06-26
- Published: 2018-10-18
- Granted: 2019-11-19
- Earliest claimed: 2012-09-21
- Assignees: Micron Technology, Inc.
- Applicants: Micron Technology, Inc.
- Inventors: Jerome A. Imonigie; Prashant Raghu
- Web page: https://patentgrep.com/patent/US10479938B2

## CPC

- C09K 13/08: containing a fluorine compound
- C09K 13/00: Etching, surface-brightening or pickling compositions (for glass C03C15/00, {C03C25/66; for mortars, concrete, artificial or natural stone or ceramics C04B41/5338}; for metallic material C23F, C23G1/00, C25F1/00; {for semi-conductors H10P52/40})
- C09K 13/04: containing an inorganic acid
- C09K 13/06: with organic material
- H10B 41/27: the channels comprising vertical portions, e.g. U-shaped channels
- H10D 64/035: {comprising conductor-insulator-conductor-insulator-semiconductor structures}
- H10P 50/283: {by chemical means}
- H10P 50/642: {Chemical etching}
- H10P 50/667: {by liquid etching only}
- C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- H10B: ELECTRONIC MEMORY DEVICES
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

Methods include exposing polysilicon to an aqueous composition comprising nitric acid, poly-carboxylic acid and ammonium fluoride, and removing a portion of the polysilicon selective to an oxide using the aqueous composition.

## Claims

### Claim 1

A method, comprising:
exposing polysilicon to an aqueous composition comprising nitric acid, poly-carboxylic acid and ammonium fluoride; and
removing a portion of the polysilicon selective to an oxide using the aqueous composition;
wherein the aqueous composition comprises 60.6-70 wt % nitric acid.

### Claim 2 (depends on 1)

The method of claim 1, further comprising using the aqueous composition comprising a water content of less than 39 wt %.

### Claim 3 (depends on 1)

The method of claim 1, further comprising using the aqueous composition comprising 65-70 wt % nitric acid and 0.06-0.6 wt % ammonium fluoride.

### Claim 4 (depends on 3)

The method of claim 3, further comprising using the aqueous composition comprising poly-carboxylic acid at 0.4 wt % or less.

### Claim 5 (depends on 3)

The method of claim 3, further comprising using the aqueous composition further comprising hydrofluoric acid.

### Claim 6 (depends on 5)

The method of claim 5, further comprising using the aqueous composition comprising hydrofluoric acid at 0.08 wt % or less.

### Claim 7 (depends on 5)

The method of claim 5, further comprising using the aqueous composition comprising poly-carboxylic acid at 0.4 wt % or less.

### Claim 8 (depends on 7)

The method of claim 7, further comprising using the aqueous composition, wherein the poly-carboxylic acid is oxalic acid.

### Claim 9 (depends on 1)

The method of claim 1, wherein exposing the polysilicon to the aqueous composition comprises exposing a boron-doped polysilicon to the aqueous composition.

### Claim 10 (depends on 9)

The method of claim 9, wherein removing the portion of the polysilicon selective to the oxide comprises removing a portion of the boron-doped polysilicon selective to a silicon oxide or a silicon oxynitride.

### Claim 11 (depends on 1)

The method of claim 1, further comprising using the aqueous composition further comprising at least one component selected from a group consisting of a dye, a lubricant, a stabilizer, a buffer, a surfactant, a thickening agent, a preservative and an antimicrobial agent.

### Claim 12

A method, comprising:
forming an instance of polysilicon and forming an instance of oxide; and
removing a portion of the instance of polysilicon selective to the instance of oxide;
wherein removing the portion of the instance of polysilicon selective to the instance of oxide comprises exposing the instance of polysilicon to an aqueous composition comprising nitric acid, poly-carboxylic acid and ammonium fluoride, wherein the aqueous composition comprises a water content of less than 39 wt % and a nitric acid content of 60.6-70 wt %.

### Claim 13 (depends on 12)

The method of claim 12, wherein the poly-carboxylic acid is oxalic acid, and wherein exposing the instance of polysilicon to the aqueous composition further comprises exposing the instance of polysilicon to the aqueous composition comprising 65-70 wt % nitric acid, 0.06-0.6 wt % ammonium fluoride, and oxalic acid at 0.4 wt % or less.

### Claim 14 (depends on 13)

The method of claim 13, wherein exposing the instance of polysilicon to the aqueous composition further comprises exposing the instance of polysilicon to the aqueous composition further comprising hydrofluoric acid, and wherein the aqueous composition comprises a hydrofluoric acid content of 0.08 wt % or less.

### Claim 15 (depends on 12)

The method of claim 12, wherein exposing the instance of polysilicon to the aqueous composition further comprises exposing the instance of polysilicon to the aqueous composition consisting essentially of nitric acid, poly-carboxylic acid, ammonium fluoride, and water.

### Claim 16

A method, comprising:
exposing polysilicon to an aqueous composition comprising nitric acid, poly-carboxylic acid and ammonium fluoride, wherein the aqueous composition is devoid of hydrofluoric acid; and
removing a portion of the polysilicon selective to an oxide using the aqueous composition;
wherein the aqueous composition comprises 60.6-70 wt % nitric acid.

### Claim 17 (depends on 16)

The method of claim 16, further comprising exposing the polysilicon to the aqueous composition comprising a water content of less than or equal to 35 wt %.

### Claim 18 (depends on 17)

The method of claim 17, further comprising exposing the polysilicon to the aqueous composition comprising 65-70 wt % nitric acid and 0.06-0.6 wt % ammonium fluoride.

### Claim 19 (depends on 18)

The method of claim 18, further comprising exposing the polysilicon to the aqueous composition comprising poly-carboxylic acid at 0.4 wt % or less.

### Claim 20 (depends on 16)

The method of claim 16, further comprising exposing the polysilicon to the aqueous composition wherein the poly-carboxylic acid is oxalic acid.