US5409859A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of forming platinum ohmic contact to p-type silicon carbide
Assignee: North Carolina State University
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Filing: 1994-04-22
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Granted: 1995-04-25
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Expires: 2014-04-22
Abstract
Abstract A method and resulting ohmic contact structure between a high work function metal and a wide bandgap semiconductor for which the work function of the metal would ordinarily be insufficient to form an ohmic contact between the metal and the semiconductor. The structure can withstand annealing while retaining ohmic characteristics. The ohmic contact structure comprises a portion of single crystal wide bandgap semiconductor material; a contact formed of a high work function metal on the semiconductor portion; and a layer of doped p-type semiconductor material between the single crystal portion and the metal contact. The doped layer has a sufficient concentration of p-type dopant to provide ohmic behavior between the metal and the semiconductor material.
Inventors
- 👤 Robert C. Glass
- 👤 John W. Palmour
- 👤 Robert F. Davis
- 👤 Lisa S. Porter
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 16:10
CPC Classifications
H; H10; H10D; H10D62/00; H10D62/80; H10D62/83; H10D62/832; H10D62/8325; H10D64/00; H10D64/01; H10D64/011; H10D64/0111; H10D64/0115; H10D64/60; H10D64/62; Y; Y10; Y10S; Y10S148/00; Y10S148/148
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
83 words
A method of forming an ohmic contact between silicon carbide and platinum to produce an ohmic contact that can withstand annealing required for formation, the method comprising: forming a layer of doped p-type silicon carbide on a portion of single crystal silicon carbide in which the doped layer has a sufficient concentration of p-type dopant to provide ohmic behavior between silicon carbide and platinum; and depositing a layer of platinum on the doped layer to provide an ohmic contact to the silicon carbide.
Claim 2
Independent Claim
83 words
A method of forming an ohmic contact between silicon carbide and platinum to produce an ohmic contact that can withstand annealing required for formation, the method comprising: forming a layer of doped p-type silicon carbide on a portion of single crystal silicon carbide in which the doped layer has a sufficient concentration of p-type dopant to provide ohmic behavior between silicon carbide and platinum; and depositing a layer of platinum on the doped layer to provide an ohmic contact to the silicon carbide.
Claim 3
Dependent Claim
23 words
A method according to claim 1 wherein the step of forming the doped silicon carbide layer precedes the step of depositing the platinum.
Claim 4
Independent Claim
100 words
A method of forming an ohmic contact between silicon carbide and platinum to produce an ohmic contact that can withstand annealing required for formation, the method comprising: forming a layer of silicon carbide on a portion of single crystal silicon carbide; depositing a layer of platium on the silicon carbide layer; doping the silicon carbide layer thereby forming a doped p-type silicon carbide layer in which the doped layer has sufficient concentration of p-type dopant to provide ohmic behavior between silicon carbide and platinum wherein the step of doping the silicon carbide layer follows the step of depositing the platinum.
Claim 5
Independent Claim
100 words
A method of forming an ohmic contact between silicon carbide and platinum to produce an ohmic contact that can withstand annealing required for formation, the method comprising: forming a layer of silicon carbide on a portion of single crystal silicon carbide; depositing a layer of platium on the silicon carbide layer; doping the silicon carbide layer thereby forming a doped p-type silicon carbide layer in which the doped layer has sufficient concentration of p-type dopant to provide ohmic behavior between silicon carbide and platinum wherein the step of doping the silicon carbide layer follows the step of depositing the platinum.
Claim 6
Dependent Claim
22 words
A method according to claim 1 wherein the step of forming the layer of doped silicon carbide comprises high temperature ion implantation.
Claim 7
Dependent Claim
43 words
A method according to claim 4 wherein the step of high temperature ion implantation comprises implanting with an energy of 5 kV or higher, a dose of 4×10 13 cm -2 or higher, with the silicon carbide maintained at 400° C. or higher.
Claim 8
Dependent Claim
27 words
A method according to claim 4 and further comprising the step of annealing the ion implanted layer prior to the step of depositing the layer of platinum.
Claim 9
Dependent Claim
21 words
A method according to claim 6 comprising annealing the ion implanted layer at a temperature of at least about 1000° C.
Claim 10
Dependent Claim
26 words
A method according to claim 4 and further comprising the step of annealing the ohmic contact structure following the step of depositing the layer of platinum.
Claim 11
Dependent Claim
21 words
A method according to claim 8 comprising annealing the ohmic contact structure at a temperature of at least about 400° C.
Claim 12
Dependent Claim
14 words
A method according to claim 1 wherein the silicon carbide comprises the 6H polytype.
Claim 13
Dependent Claim
26 words
A method according to claim 1 wherein the silicon carbide is selected from the group consisting of the 3C, 2H, 4H, 6H, 8H and 15R polytypes.
Claim 14
Dependent Claim
58 words
A method according to claim 1 wherein the step of forming a layer of doped silicon carbide comprises forming a layer doped with a sufficient concentration of p-type dopant to reduce the width of the depletion region sufficiently at the interface between the platinum contact and the silicon carbide portion to allow carrier tunneling transport across the interface.
Claim 15
Dependent Claim
31 words
A method according to claim 1 wherein the step of forming a doped layer comprises forming a doped layer with a carrier concentration of at least 1×10 17 cm -3 .
Claim 16
Dependent Claim
31 words
A method according to claim 1 wherein the step of forming a doped layer comprises forming a doped layer with a carrier concentration of at least 5×10 18 cm -3 .
Claim 17
Dependent Claim
31 words
A method according to claim 1 wherein the step of forming a doped layer comprises forming a doped layer with a carrier concentration of at least 10 19 cm -3 .
Claim 18
Dependent Claim
21 words
A method according to claim 1 wherein the step of forming a doped layer comprises forming a layer doped with aluminum.
Claim 19
Dependent Claim
33 words
A method according to claim 16 wherein the step of forming a layer doped with aluminum comprises forming a layer with an atomic concentration of aluminum of between about 0.1 and 5 percent.
Claim 20
Dependent Claim
22 words
A method according to claim 1 wherein the step of forming a doped layer comprises forming a forming layer doped with boron.
Claim 21
Dependent Claim
24 words
A method according to claim 1 wherein the step of depositing a layer of platinum further comprises annealing the platinum to form platinum silicide.
Claim 22
Dependent Claim
22 words
A method according to claim 1 wherein the step of depositing a layer of platinum comprises depositing a layer of platinum silicide.
Claim 23
Dependent Claim
22 words
A method according to claim 20 wherein the step of depositing a layer of platinum silicide comprises sputter deposition of platinum silicide.
Claim 24
Independent Claim
96 words
A method of forming an ohmic contact structure between silicon carbide and platinum to produce an ohmic contact that can withstand annealing required for formation, the method comprising: implanting a portion of single crystal silicon carbide by high temperature implantation of dopant ions to form a doped layer of silicon carbide having a sufficient concentration of p-type dopant to provide ohmic behavior between silicon carbide and platinum; annealing the ion implanted layer; depositing a layer of platinum on the doped layer to provide an ohmic contact to the silicon carbide; and annealing the ohmic contact structure.
Claim 25
Independent Claim
96 words
A method of forming an ohmic contact structure between silicon carbide and platinum to produce an ohmic contact that can withstand annealing required for formation, the method comprising: implanting a portion of single crystal silicon carbide by high temperature implantation of dopant ions to form a doped layer of silicon carbide having a sufficient concentration of p-type dopant to provide ohmic behavior between silicon carbide and platinum; annealing the ion implanted layer; depositing a layer of platinum on the doped layer to provide an ohmic contact to the silicon carbide; and annealing the ohmic contact structure.
Claim 26
Dependent Claim
14 words
A method according to claim 22 wherein the silicon carbide comprises the 6H polytype.
Claim 27
Dependent Claim
60 words
A method according to claim 22 wherein the step of implanting to form a layer of doped silicon carbide comprises forming a layer doped with a sufficient concentration of p-type dopant to reduce the width of the depletion region sufficiently at the interface between said platinum contact and said silicon carbide portion to allow carrier tunneling transport across the interface.
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