# US 8,785,946 B2 · Low 1C screw dislocation 3 inch silicon carbide wafer

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- Number: US 8,785,946 B2
- Document ID: US8785946B2
- Status: Granted
- Kind: B2
- Application number: 13/776,784
- Filed: 2013-02-26
- Published: 2013-06-27
- Granted: 2014-07-22
- Earliest claimed: 2004-10-04
- Assignees: Cree, Inc.
- Applicants: Cree, Inc.
- Inventors: Adrian Powell; Mark Brady; Stephan G. Mueller; Valeri F. Tsvetkov; Robert T. Leonard
- Web page: https://patentgrep.com/patent/US8785946B2

## CPC

- C30B 23/00: Single-crystal growth by condensing evaporated or sublimed materials
- C30B 29/36: Carbides
- Y10T 428/21: Circular sheet or circular blank
- 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
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A high quality single crystal wafer of SiC is disclosed having a diameter of at least about 3 inches and a 1 c screw dislocation density from about 500 cm−2 to about 2000 cm−2.

## Claims

### Claim 1

A single crystal wafer of SiC having a diameter of at least about 3 inches and a 1 c screw dislocation density from about 55 cm−2 to about 2500 cm−2.

### Claim 2 (depends on 1)

A single crystal wafer of SiC according to claim 1 wherein the 1 c screw dislocation density is less than about 1500 cm−2.

### Claim 3 (depends on 1)

A single crystal wafer of SiC according to claim 1 wherein the 1 c screw dislocation density is less than about 1200 cm−2.

### Claim 4 (depends on 1)

A single crystal wafer of SiC according to claim 1 wherein the crystal has a polytype selected from the group consisting of the 3C, 4H, 6H, 2H, and 15R polytypes.

### Claim 5 (depends on 1)

A single crystal wafer of SiC according to claim 1 wherein the 1 c screw dislocation density is less than about 2000 cm−2.

### Claim 6 (depends on 1)

A single crystal wafer of SiC according to claim 1 wherein the wafer is less than about 5 inches in diameter.

### Claim 7

A high quality semiconductor precursor wafer comprising:
a single crystal silicon carbide wafer having a diameter of at least about 3 inches;
said wafer having the 4H polytype; and
said wafer having a 1 c screw density on its surface is from about 500 cm−2 to about 2500 cm−2.

### Claim 8 (depends on 7)

A high quality semiconductor precursor wafer according to claim 7 wherein said surface 1 c screw dislocation density represents a count of the 1 c screw dislocations on said surface following an etch that preferentially emphasizes 1 c screw dislocation defects.

### Claim 9 (depends on 8)

A high quality semiconductor precursor wafer according to claim 8 wherein said surface 1 c screw dislocation density represents a count of the total 1 c screw dislocations on said surface following an etch of the surface in molten potassium hydroxide.

### Claim 10

A high quality semiconductor precursor wafer comprising:
a single crystal silicon carbide wafer having a diameter of at least about 3 inches;
said wafer having the 4H polytype;
said wafer having a 1 c screw dislocation density on its surface is from about 500 cm−2 to about 2500 cm−2; and
a Group III-nitride layer on said surface of said silicon carbide wafer.

### Claim 11 (depends on 10)

A semiconductor precursor wafer according to claim 10 wherein said Group III-nitride layer is selected from the group consisting of GaN, AlGaN, AN, AlInGaN, InN, AlInN and mixtures thereof.

### Claim 12

A plurality of semiconductor device precursors comprising:
a single crystal silicon carbide wafer having a diameter of at least about 3 inches and a 1 c screw dislocation density on the surface is from about 500 cm−2 to about 2500 cm−2; and
a plurality of respective Group III-nitride epitaxial layers on some portions of said wafer.

### Claim 13

A semiconductor wafer comprising:
a single crystal silicon carbide substrate of at least about 3 inches and having a 1 c screw dislocation density is from about 500 cm−2 to about 2500 cm−2; and
a plurality of devices on said silicon carbide substrate, each said device comprising:
an epitaxial layer located on the substrate, said layer having a concentration of suitable dopant atoms for making the epitaxial layer a first conductivity type, and respective source, channel, and drain portions;
a metal oxide layer on said channel portion; and
and a metal gate contact on said metal oxide layer for forming an active channel when a bias is applied to said metal gate contact.

### Claim 14

A semiconductor wafer comprising:
a single crystal silicon carbide substrate of at least about 3 inches and having a 1 c screw dislocation density is from about 500 cm−2 to about 2500 cm−2; and
a plurality of devices on said silicon carbide substrate, each said device comprising:
a conductive channel on said substrate;
a source and a drain on said conductive channel; and
a metal gate contact between said source and said drain on said conductive channel for forming an active channel when a bias is applied to the metal gate contact.

### Claim 15

A semiconductor wafer comprising:
a single crystal silicon carbide substrate of at least about 3 inches and having a 1 c screw dislocation density is from about 500 cm−2 to about 2500 cm−2; and
a plurality of junction field-effect transistors positioned on said single crystal silicon carbide substrate.

### Claim 16

A semiconductor wafer comprising:
a single crystal silicon carbide substrate of at least about 3 inches and having a 1 c screw dislocation density is from about 500 cm−2 to about 2500 cm−2; and
a plurality of hetero-field effect transistors positioned on said single crystal silicon carbide substrate.

### Claim 17

A semiconductor wafer comprising:
a bulk single crystal silicon carbide substrate of at least about 3 inches and having a 1 c screw dislocation density of less than 2500 cm−2, said bulk single crystal having respective first and second surfaces opposite one another; and
a plurality of diodes positioned on said single crystal silicon carbide substrate.

### Claim 18

A single crystal wafer of SiC having a diameter between about 3 inches and about 5 inches and a 1 c screw dislocation density from about 500 cm−2 to about 2500 cm−2.

### Claim 19 (depends on 18)

A single crystal wafer of SiC according to claim 18 wherein the 1 c screw dislocation density is less than about 2000 cm−2.

### Claim 20 (depends on 18)

A single crystal wafer of SiC according to claim 18 wherein the 1 c screw dislocation density is less than about 1500 cm−2.

### Claim 21 (depends on 18)

A single crystal wafer of SiC according to claim 18 wherein the 1 c screw dislocation density is less than about 1200 cm−2.