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US5010035A Expired / Lapsed US ⏱️ 0.0 years remaining

Wafer base for silicon carbide semiconductor device

Assignee: University of California, San Diego
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Filing: 1988-05-13
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Granted: 1991-04-23
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Expires: 2008-05-13
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Abstract

Abstract A semiconductor device wafer base wherein devices may be fabricated in silicon carbide, the base having a compatible substrate and a beta silicon carbide overlay layer epitaxially related to the substrate, the beta silicon carbide layer being unpolytyped, single crystal, uncracked, without twins, and having integrated circuit quality surface morphology. Preferably, the substrate is a single crystal of titanium carbide, which is the same cubic lattice-type as beta silicon carbide with a lattice parameter different from that of beta silicon carbide by less than about 1%. Additionally, the thermal expansion coefficients of beta silicon carbide and titanium carbide are nearly the same, minimizing the creation of thermal stresses during cooling and heating. The beta silicon carbide is useful in fabricating semi-conductor devices for use at much higher temperatures than is silicon, and for use at high power levels, at high frequencies, and in radiation hardened applications. The device base may be fabricated by any suitable technique, including reactive deposition and chemical vapor deposition.

Inventors

  • 👤 Rointan F. Bunshah
  • 👤 James D. Parsons
  • 👤 Oscar M. Stafsudd

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-28 16:13
CPC Classifications
H; H10; H10D; H10D62/00; H10D62/80; H10D62/83; H10D62/832; H10D62/8325; Y; Y10; Y10S; Y10S148/00; Y10S148/148; Y10S438/00; Y10S438/931

Claims Analysis

Total Claims: 10
Claim 1
Independent Claim 55 words
A process for preparing a semiconductor device wafer base, comprising the steps of: furnishing a single crystal titanium carbide substrate; and depositing an overlay layer of beta silicon carbide onto said substrate, said overlay layer being a single crystal, epitaxially related to said substrate, unpolytyped, uncracked, without twins, and of integrated circuit quality surface morphology.
Claim 2
Dependent Claim 55 words
A process for preparing a semiconductor device wafer base, comprising the steps of: furnishing a single crystal titanium carbide substrate; and depositing an overlay layer of beta silicon carbide onto said substrate, said overlay layer being a single crystal, epitaxially related to said substrate, unpolytyped, uncracked, without twins, and of integrated circuit quality surface morphology.
Claim 3
Dependent Claim 11 words
The process of claim 1, wherein the overlay layer is doped.
Claim 4
Dependent Claim 22 words
The process of claim 1, wherein the temperature of the substrate during said step of depositing is at least about 1325° C.
Claim 5
Dependent Claim 20 words
The process of claim 1, wherein the temperature of the substrate during said step of depositing is about 1400° C.
Claim 6
Dependent Claim 76 words
A reactive evaporation process for preparing a semiconductor device wafer base, comprising the steps of: furnishing a vacuum system; placing a titanium carbide substrate into the vacuum system; introducing a flow of a carbon-containing gas into the vacuum system; evaporating silicon from a source within the chamber, whereby evaporated silicon atoms pass through the carbon-containing gas and react therewith, and the resulting reaction products are deposited in an overlay layer onto the surface of the substrate.
Claim 7
Dependent Claim 76 words
A reactive evaporation process for preparing a semiconductor device wafer base, comprising the steps of: furnishing a vacuum system; placing a titanium carbide substrate into the vacuum system; introducing a flow of a carbon-containing gas into the vacuum system; evaporating silicon from a source within the chamber, whereby evaporated silicon atoms pass through the carbon-containing gas and react therewith, and the resulting reaction products are deposited in an overlay layer onto the surface of the substrate.
Claim 8
Dependent Claim 11 words
The process of claim 5, wherein the carboncontaining gas is acetylene.
Claim 9
Dependent Claim 22 words
The process of claim 5, wherein the temperature of the substrate during said step of evaporating is at least about 1325° C.
Claim 10
Dependent Claim 20 words
The process of claim 5, wherein the temperature of the substrate during said step of depositing is about 1400° C.

References Cited (Backward Citations)

JPS63303896A Cited
US4923716A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1994-04-22 1994-10-22 1995-04-23 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1998-04-22 1998-10-22 1999-04-23 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 2002-04-22 2002-10-22 2003-04-23 $7700.00 Window Closed / Lapsed

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