# US 9,041,010 B2 · Wide band gap semiconductor wafers grown and processed in a microgravity environment and method of production

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- Number: US 9,041,010 B2
- Document ID: US9041010B2
- Status: Granted
- Kind: B2
- Application number: 13/904,918
- Filed: 2013-05-29
- Published: 2014-12-04
- Granted: 2015-05-26
- Earliest claimed: 2013-05-29
- Applicants: William F. Seng; Richard L. Glover
- Inventors: William F. Seng; Richard L. Glover
- Web page: https://patentgrep.com/patent/US9041010B2

## CPC

- C30B 30/08: in conditions of zero-gravity or low gravity
- C30B 9/10: Metal solvents
- C30B 19/02: using molten solvents, e.g. flux
- C30B 19/10: Controlling or regulating (controlling or regulating in general G05)
- C30B 29/36: Carbides
- C30B 33/02: Heat treatment (C30B33/04, C30B33/06 take precedence)
- H10D 48/01: Manufacture or treatment
- H10D 62/357: {of FETs}
- H10D 62/8325: {Silicon carbide}
- H10D 62/8503: {Nitride Group III-V materials, e.g. AlN or GaN}
- H10P 14/263: {using melted materials}
- H10P 14/265: {using solutions}
- H10P 14/2901: {Materials}
- H10P 14/2904: {Silicon carbide}
- H10P 14/3408: {Silicon carbide}
- H10P 14/3421: {Arsenides}
- C30B 29/40: AIIIBV compounds {wherein A is B, Al, Ga, In or Tl and B is N, P, As, Sb or Bi}
- H10D 8/60: Schottky-barrier diodes
- 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
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

Wide band gap semiconductor wafers with previously unattainable characteristics and the method of processing and producing the same are disclosed and claimed herein. Specifically, the application discloses and claims a method to process silicon carbide and other similar wide band gap semiconductors in a microgravity environment. The wafers are placed onto stackable containment systems that create an appropriate gap between each wafer to allow for homogeneous heating and processing. The resulting wide band gap semiconductors have unique molecular structures not attainable when wide band gap semiconductors with the identical chemical composition are produced in a standard 1 gravity environment.

## Claims

### Claim 1

A wide band gap semiconductor wafer comprising a silicon carbide (SiC) substrate, the silicon carbide substrate comprising atoms arranged into their preferred, lowest energy state and with an extremely low defect density, the SiC substrate comprising the following ranges of material characteristics:
a. a micropipe density of less than 0.01 cm−2;
b. a micropipe free area greater than 99%;
c. a basal plane dislocation density of less than 0.01 cm−2;
d. a basal plane dislocation free area greater than 99%; and
e. cumulative areal defects of less than 1% of wafer area.

### Claim 2 (depends on 1)

The wide band gap semiconductor wafer of claim 1 wherein the substrate is selected from the group consisting of Galium Arsenide (GaAs), Indium Phosphide (InP), Cadmium Telluride (CdTe) and Galium Nitride (GaN).

### Claim 3 (depends on 1)

The wide band gap semiconductor wafer of claim 1 further comprising a multi-element, integrated circuit, the circuit comprising more than 500 transistors with the circuit elements being inseparably engaged and electrically interconnected so that the resulting wafer is indivisible for the purposes of manufacture and incorporation into multiple commercially marketable products.

### Claim 4

A wide band gap semiconductor wafer comprising a silicon carbide (SiC) substrate and one or more epi layers, the silicon carbide substrate and the one or more epi layers comprising atoms arranged into their preferred, lowest energy state and with an extremely low defect density, the SiC substrate and the one or more epi layers comprising the following ranges of material characteristics:
a. a micropipe density of less than 0.01 cm−2;
b. a micropipe free area greater than 99%;
c. a basal plane dislocation density of less than 0.01 cm−2;
d. a basal plane dislocation free area greater than 99%; and
e. cumulative areal defects of less than 1% of wafer area.

### Claim 5 (depends on 4)

The wide band gap semiconductor wafer of claim 4 wherein the substrate is selected from the group consisting of Galium Arsenide (GaAs), Indium Phosphide (InP), Cadmium Telluride (CdTe) and Galium Nitride (GaN).

### Claim 6 (depends on 4)

The wide band gap semiconductor wafer of claim 4 wherein the one or more epi layers are selected from the group consisting of Galium Arsenide (GaAs), Indium Phosphide (InP), Cadmium Telluride (CdTe) and Galium Nitride (GaN).

### Claim 7 (depends on 4)

The wide band gap semiconductor wafer of claim 4 wherein either the substrate or the one or more epi layers can be selected from the group consisting of Galium Arsenide (GaAs), Indium Phosphide (InP), Cadmium Telluride (CdTe) and Galium Nitride (GaN) so that all possible substrate and epi layers permutations can be achieved.

### Claim 8 (depends on 4)

The wide band gap semiconductor wafer of claim 4 further comprising a multi element, integrated circuit, the circuit comprising more than 500 transistors with the circuit elements being inseparably engaged and electrically interconnected so that the resulting wafer is indivisible for the purposes of manufacture and incorporation into multiple commercially marketably products.

### Claim 9 (depends on 4)

The wide band gap semiconductor wafer of claim 4 wherein the SiC substrate is processed through to a high voltage switch with the resulting wafer being capable of being used in high voltage transmission lines and electrical motors.

### Claim 10 (depends on 6)

A method of growing and producing wide band gap semiconductor wafers in a microgravity environment, the method comprising the steps of:
a. providing a microgravity environment;
b. providing a substrate or an epi layer selected from the group consisting of Silicon Carbide (SiC), Galium Arsenide (GaAs), Indium Phosphide (InP), Cadmium Telluride (CdTe) and Galium Nitride (GaN) and placing the substrate or epi layer in a microgravity environment;
c. creating a saturated melt of the substrate or epi layer to be grown in an appropriate solvent;
d. controlling the melt temperature so it is brought down to below the liquidus line thus resulting in precipitation of a now supersaturated melt leaving the non-precipitated substrate or epi layer still dissolved in the melt; and
e. collecting the resulting substrate or epi layer claimed in one of claim 6.

### Claim 11 (depends on 6)

A method of growing and producing wide band gap semiconductor wafers in a microgravity environment, the method comprising the steps of:
a. placing a wide band gap semiconductor wafer produced via traditional methods in a microgravity environment, the wafer comprising atoms arranged in a lattice;
b. heating the wafer to a point where the atoms in the lattice begin to experience motility;
c. allowing absence of gravity and other perturbing forces to settle the wafer into its lowest energy state and lowest defect density whereupon defects which could have been caused by external forces are eliminated;
d. allowing the wafer to cool down to a point where the atoms no longer have motility resulting in the wafer being in its natural, lowest energy state; and
e. collecting the resulting wafer claimed in one of claim 6.