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US5248385A
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Process for the homoepitaxial growth of single-crystal silicon carbide films on silicon carbide wafers
Assignee: United States, NATIONAL AERONAUTICS AND SPACE ADMIN, Administrator of
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Filing: 1991-06-12
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Granted: 1993-09-28
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Expires: 2011-06-12
Abstract
Abstract The invention is a method for growing homoepitaxial films of SiC on low-tilt-angle vicinal (0001) SiC wafers. The invention proposes and teaches a new theoretical model for the homoepitaxial growth of SiC films on (0001) SiC substrates. The inventive method consists of (1) preparing the growth surface of SiC wafers slightly off-axis (from less than 0.1° to 6°) from the (0001) plane, (2) subjecting the growth surface to a suitable etch, and then (3) growing the homoepitaxial film using conventional SiC growth techniques.
Inventors
- 👤 J. Anthony Powell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 07:54
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/20; H10P14/00; H10P14/20; H10P14/24; H10P14/29; H10P14/2901; H10P14/2902; H10P14/2904; H10P14/2926; H10P14/34; H10P14/3402; H10P14/3404; H10P14/3408; H10P14/3438; H10P14/3441; H10P14/3442; H10P14/3444; H10P14/36; H10P14/3602; H10P52/00; H10P95/00; H10P95/70; Y; Y10; Y10S; Y10S117/00; Y10S117/901; Y10S117/902; Y10S148/00; Y10S148/148; Y10S438/00; Y10S438/931
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
96 words
A method of producing a device quality silicon carbide film on a silicon carbide substrate of the same polytype comprising: homoepitaxially depositing a film of a SiC polytype on a specially prepared planar surface of a SiC substrate, wherein the planar surface can have any non-zero inclination relative to a basal plane from less than 0.1° to about 6° and wherein the planar surface has been subjected to a suitable pregrowth etch that eliminates all surface features that can act as sites of heterogeneous nucleation of a polytype different from the substrate during subsequent film growth.
Claim 2
Independent Claim
96 words
A method of producing a device quality silicon carbide film on a silicon carbide substrate of the same polytype comprising: homoepitaxially depositing a film of a SiC polytype on a specially prepared planar surface of a SiC substrate, wherein the planar surface can have any non-zero inclination relative to a basal plane from less than 0.1° to about 6° and wherein the planar surface has been subjected to a suitable pregrowth etch that eliminates all surface features that can act as sites of heterogeneous nucleation of a polytype different from the substrate during subsequent film growth.
Claim 3
Dependent Claim
18 words
A method according to claim 1 wherein the polytype of both the substrate and the film is 6H-SiC.
Claim 4
Dependent Claim
32 words
A method according to claim 1 wherein the suitable pregrowth etch consists of heating the planar substrate in an HCl/H 2 mixture to a temperature of between 1300° C. and 1450° C.
Claim 5
Dependent Claim
40 words
A method according to claim 1 wherein the temperature of the etch is between 1300° C. and 1450° C., the time of the etch is between 2 min and 60 min, and the HCl concentration is between 2% and 5%.
Claim 6
Dependent Claim
40 words
A method according to claim 1 wherein the temperature of the etch is between 1350° C. and 1400° C., the time of the etch is between 10 min and 30 min, and the HCl concentration is between 3% and 4%.
Claim 7
Dependent Claim
37 words
A method according to claim 1 wherein the temperature of the etch is about 1350° C., the time of the etch is between 20 min and 30 min, and the HCl concentration is between 3% and 4%.
Claim 8
Dependent Claim
18 words
A method according to claim 1 wherein the substrate is a wafer cut from a single-crystal SiC boule.
Claim 9
Dependent Claim
19 words
A method according to claim 1 wherein the planar surface of the substrate is prepared by polishing said surface.
Claim 10
Dependent Claim
20 words
A method according to claim 1 wherein including the step of fabricating one or more electronic devices on the film.
Claim 11
Independent Claim
178 words
A method of producing a single-crystal SiC film homoepitaxially deposited on a single-crystal SiC substrate, wherein the film is characterized by a smooth surface morphology, substantially uniform thickness, and a low, device-quality defect level, said method comprising: lapping and polishing a SiC substrate crystal to expose a planar surface that is inclined in any direction by any non-zero angle in the range from less than 0.1° to about 6° with respect to a basal plane; subjecting the planar surface of the substrate to a pregrowth etch in an HCl/H 2 mixture at a temperature in the range 1300° to 1450° C.; heating the substrate in a growth chamber; introducing a carrier gas, a vaporized silicon-containing material and a vaporized carbon-containing material into the growth chamber while providing sufficient energy to create surface diffusion of silicon and carbon species at the substrate planar surface and establish a homoepitaxial growth of single-crystal SiC; and maintaining the carrier gas, silicon-containing material and carbon containing material flows and the energy levels for a time sufficient to grow a film of desired thickness.
Claim 12
Independent Claim
178 words
A method of producing a single-crystal SiC film homoepitaxially deposited on a single-crystal SiC substrate, wherein the film is characterized by a smooth surface morphology, substantially uniform thickness, and a low, device-quality defect level, said method comprising: lapping and polishing a SiC substrate crystal to expose a planar surface that is inclined in any direction by any non-zero angle in the range from less than 0.1° to about 6° with respect to a basal plane; subjecting the planar surface of the substrate to a pregrowth etch in an HCl/H 2 mixture at a temperature in the range 1300° to 1450° C.; heating the substrate in a growth chamber; introducing a carrier gas, a vaporized silicon-containing material and a vaporized carbon-containing material into the growth chamber while providing sufficient energy to create surface diffusion of silicon and carbon species at the substrate planar surface and establish a homoepitaxial growth of single-crystal SiC; and maintaining the carrier gas, silicon-containing material and carbon containing material flows and the energy levels for a time sufficient to grow a film of desired thickness.
Claim 13
Dependent Claim
40 words
A method according to claim 10 wherein the temperature of the etch is between 1300° C. and 1450° C., the time of the etch is between 2 min and 60 min, and the HCl concentration is between 2% and 5%.
Claim 14
Dependent Claim
40 words
A method according to claim 10 wherein the temperature of the etch is between 1350° C. and 1400° C., the time of the etch is between 10 min and 30 min, and the HCl concentration is between 3% and 4%.
Claim 15
Dependent Claim
33 words
A method according to claim 10 wherein the temperature of the etch is about 1350° C., the time of the etch is 25 min, and the HCl concentration is between 3% and 4%.
Claim 16
Dependent Claim
25 words
A method according to claim 10 wherein the growth temperature is maintained at a temperature on the order of about 1350° C. to 1700° C.
Claim 17
Independent Claim
13 words
A method according to claim wherein the carrier gas is H 2 .
Claim 18
Dependent Claim
37 words
A method according to claim 10 wherein the carrier gas is H 2 , the Vaporized silicon-containing material is a SiH 4 source gas and the vaporized carbon-containing material is a C 3 H 8 source gas.
Claim 19
Dependent Claim
23 words
A method according to claim 10 including the step of introducing dopants into the growth chamber during epitaxial growth of the single-crystal SiC.
Claim 20
Dependent Claim
8 words
The product produced by method of claim 1.
References Cited (Backward Citations)
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US4664944A
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-09-27 | 1997-03-29 | 1997-09-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-09-27 | 2001-03-29 | 2001-09-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-09-27 | 2005-03-29 | 2005-09-28 | $7700.00 | Window Closed / Lapsed |