# US 12,760,223 B2 · Silicon etching solution and method for producing silicon etching solution, method for treating substrate, and method for producing silicon device

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- Number: US 12,760,223 B2
- Document ID: US12760223B2
- Status: Granted
- Kind: B2
- Application number: 18/239,303
- Filed: 2023-08-29
- Published: 2024-02-29
- Granted: 2026-10-13
- Earliest claimed: 2022-08-30
- Assignees: Tokuyama Corporation
- Applicants: Tokuyama Corporation
- Inventors: Tatsuya Hitomi; Yoshiki Seike; Kohsuke Noro; Kohshiro Okimura
- Web page: https://patentgrep.com/patent/US12760223B2

## CPC

- C09K 13/04: containing an inorganic acid
- 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 13/02: containing an alkali metal hydroxide
- H10P 50/642: {Chemical etching}
- H10P 50/644: {Anisotropic liquid etching (H10P50/61 takes precedence)}
- H10P 50/667: {by liquid etching only}
- H10P 70/00: Cleaning of wafers, substrates or parts of devices
- H10P 70/15: {by wet cleaning only (H10P70/52 takes precedence)}
- H10P 70/20: {Cleaning during device manufacture}
- 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 silicon etching solution including an aqueous alkaline solution containing a hypohalite ion in a range of 0.05 mmol/L or greater and 5 mmol/L or less and having a pH of 12.5 or greater at 24° C.

## Claims

### Claim 1

A silicon etching solution consisting essentially of one or more alkaline compounds, a hypohalite serving as a supply source of hypohalite ions, and water,
wherein the silicon etching solution is an aqueous alkaline solution with a hypohalite ion concentration in a range of 0.05 mmol/L or greater and 5 mmol/L or less, and a pH of 12.5 or greater at 24° C.

### Claim 2 (depends on 1)

The silicon etching solution according to claim 1, wherein a content of each of metals Ag, Al, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, Pb, and Zn is 1 ppm by mass or less.

### Claim 3 (depends on 2)

The silicon etching solution according to claim 2, wherein the silicon etching solution is substantially free of metal.

### Claim 4

A silicon etching solution consisting essentially of one or more alkaline compounds, a hypohalite serving as a supply source of hypohalite ions, a quaternary ammonium ion, and water,
wherein the silicon etching solution is an aqueous alkaline solution with a hypohalite ion concentration in a range of 0.05 mmol/L or greater and 5 mmol/L or less, and a pH of 12.5 or greater at 24° C.

### Claim 5 (depends on 1)

A method for producing the silicon etching solution according to claim 1, the method comprising a mixing step of mixing a quaternary ammonium hydroxide, a quaternary ammonium salt of hypohalous acid, and water.

### Claim 6 (depends on 1)

A method for treating a substrate, the method comprising a step of bringing the silicon etching solution according to claim 1 into contact with a substrate having a Si surface to etch the Si surface.

### Claim 7 (depends on 6)

A method for producing a silicon device, the method comprising treating a substrate by the method according to claim 6.