# US 2025/0167006 A1 · Gallium oxide substrate and method of manufacturing gallium oxide substrate

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- Number: US 2025/0167006 A1
- Document ID: US20250167006A1
- Status: Published application
- Kind: A1
- Application number: 19/034,990
- Filed: 2025-01-23
- Published: 2025-05-22
- Earliest claimed: 2019-04-08
- Assignees: AGC Inc.
- Applicants: AGC Inc.
- Inventors: Yusuke HIRABAYASHI
- Web page: https://patentgrep.com/patent/US20250167006A1

## CPC

- H10P 52/00: Grinding, lapping or polishing of wafers, substrates or parts of devices
- H10P 90/129: {by polishing}
- C01G 15/00: Compounds of gallium, indium or thallium
- C30B 29/16: Oxides
- H10D 62/57: the imperfections being on the surface of the semiconductor body, e.g. the body having a roughened surface
- H10D 62/80: characterised by the materials
- H10P 54/00: Cutting or separating of wafers, substrates or parts of devices
- H10P 95/60: Mechanical treatments, e.g. by ultrasounds
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- C01G: COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F (metal hydrides {monoborane, diborane or addition complexes thereof} C01B6/00; salts of oxyacids of halogens C01B11/00; peroxides, salts or peroxyacids C01B15/00; thiosulfates, dithionites, polythionates C01B17/64; compounds containing selenium, or tellurium C01B19/00; binary compounds of nitrogen with metals C01B21/06; azides C01B21/08; {compounds containing nitrogen, other non-metals and metal C01B21/082}; metal amides C01B21/092; nitrites C01B21/50; {compounds of noble gases C01B23/0005}; phosphides C01B25/08; salts of oxyacids of phosphorus C01B25/16; carbides C01B32/90; compounds containing silicon C01B33/00; compounds containing boron C01B35/00; compounds having molecular sieve properties but not having base-exchange properties C01B37/00; compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites, C01B39/00; cyanides C01C3/08; salts of cyanamide C01C3/16; thiocyanates C01C3/20)
- C30B: SINGLE-CRYSTAL GROWTH (by using ultra-high pressure, e.g. for the formation of diamonds, B01J3/06); UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL (zone-refining of metals or alloys C22B); PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (casting of metals, casting of other substances by the same processes or devices B22D; working of plastics B29; modifying the physical structure of metals or alloys C21D, C22F); SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (for producing semiconductor devices or parts thereof H10); APPARATUS THEREFOR
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

A gallium oxide substrate includes first and second main surfaces. When measured data z0(r,θ) of height differences of points (r,θ,z) on the first main surface from a least square plane of the first main surface are approximated by a function z(r,θ)=Σanmznm(r,θ), a ratio of a first maximum height difference of a component of z(r,θ) obtained by summing terms anmznm(r,θ) with an index j of 4, 9, 16, 25, 36, 49, 64, and 81, when the second main surface is placed facing a horizontal flat surface, to a diameter of the first main surface is 0.39×10−4 or less, and a ratio of a second maximum height difference of a component of z(r,θ) obtained by summing terms anmznm(r,θ) with j of from 4 to 81, when an entire surface of the second main surface is adsorbed to a flat chuck surface, to the diameter is 0.59×10−4 or less.

## Claims

### Claim 1

A method of manufacturing a gallium oxide substrate comprising:
double-side polishing of a first main surface and a second main surface of the gallium oxide substrate simultaneously in opposite directions to each other, with a polishing slurry containing particles having a Mohs hardness of 7 or less.

### Claim 2 (depends on 1)

The method of claim 1, wherein
a 50% diameter in volume based cumulative fractions of a particle diameter distribution measured by a dynamic light scattering method of the particles contained in the polishing slurry is 1 μm or less.

### Claim 3 (depends on 1)

The method of claim 1, wherein
a polishing pressure is 9.8 kPa or less during a period of 50% or more of a first half of a period of the double-side polishing of the first main surface and the second main surface.

### Claim 4 (depends on 1)

The method of claim 1, wherein the first main surface is a {001}plane of the gallium oxide substrate.

### Claim 5 (depends on 1)

The method of claim 1, wherein the first main surface has an off angle with respect to a {001}plane of the gallium oxide substrate.

### Claim 6 (depends on 1)

The method of claim 1, further comprising first single-side polishing of the first main surface, without polishing the second main surface, and second single-side polishing of the second main surface, without polishing the first main surface, wherein the first single-side polishing second single-side polishing are performed prior to the double-side polishing.

### Claim 7 (depends on 6)

The method of claim 6, further comprising slicing a gallium oxide single crystal to form the gallium oxide substrate, wherein said slicing is performed prior each of the first single-side polishing second single-side polishing.

### Claim 8 (depends on 6)

The method of claim 6, wherein the second single-stage polishing is performed with particles with a smaller median diameter D50 and lower Mohs hardness than those of the first single-sided polishing.

### Claim 9 (depends on 6)

The method of claim 6, wherein the first single-side polishing is performed prior to the second single-side polishing, the first single-side polishing is performed using diamond particles, the second single-side polishing is performed using silica particle.

### Claim 10 (depends on 1)

The method of claim 1, wherein the particles of the polishing slurry are selected from the group consisting of TiO2 particles, ZrO2 particles, Fe2O3 particles, ZnO particles, and MnO2 particles.