US5399883A
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High voltage silicon carbide MESFETs and methods of fabricating same
Assignee: Intellectual Ventures Holding 81 LLC
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Filing: 1994-05-04
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Granted: 1995-03-21
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Expires: 2014-05-04
Abstract
Abstract A high voltage silicon carbide MESFET includes an electric field equalizing region in a monocrystalline silicon carbide substrate at a face thereof, which extends between the drain and gate of the MESFET and between the source and gate of the MESFET. The region equalizes the electric field between the drain and gate and between the source and gate to thereby increase the breakdown voltage of the silicon carbide MESFET. The first and second electric field equalizing regions are preferably amorphous silicon carbide regions in the monocrystalline silicon carbide substrate. The amorphous regions are preferably formed by performing a shallow ion implantation of electrically inactive ions such as argon, using the source and drain electrodes and the metal gate as a mask, at a sufficient dose and energy to amorphize the substrate face. A third amorphous silicon carbide region may be formed at the face, adjacent and surrounding the MESFET to provide edge termination and isolation of the MESFET. The third amorphous silicon carbide region may be formed during the same shallow implant described above or may be formed in a separate deep implant. The lateral silicon carbide MESFET may be formed in an epitaxial region of second conductivity type on a substrate of first conductivity type, or in an implanted region of second conductivity type in a substrate of first conductivity type.
Inventors
- 👤 Bantval J. Baliga
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 12:31
CPC Classifications
H; H10; H10D; H10D64/00; H10D64/118; H10D12/00; H10D12/01; H10D12/031; H10D30/00; H10D30/01; H10D30/061; H10D30/80; H10D30/87; H10D62/00; H10D62/10; H10D62/13; H10D62/149; H10D62/161; H10D62/80; H10D62/83; H10D62/832; H10D62/8325; Y; Y10; Y10S; Y10S438/00; Y10S438/931
Claims Analysis
Total Claims: 35
Claim 1
Independent Claim
65 words
A silicon carbide field effect transistor comprising: a monocrystalline silicon carbide substrate; spaced apart source and drain regions in said monocrystalline silicon carbide substrate, extending to a face thereof; a gate on said face between said spaced apart source and drain regions; and an amorphous silicon carbide region in said monocrystalline silicon carbide substrate, at said face, and extending between said drain and said gate.
Claim 2
Dependent Claim
65 words
A silicon carbide field effect transistor comprising: a monocrystalline silicon carbide substrate; spaced apart source and drain regions in said monocrystalline silicon carbide substrate, extending to a face thereof; a gate on said face between said spaced apart source and drain regions; and an amorphous silicon carbide region in said monocrystalline silicon carbide substrate, at said face, and extending between said drain and said gate.
Claim 3
Dependent Claim
35 words
A silicon carbide field effect transistor according to claim 1 further comprising a second amorphous silicon carbide region in said monocrystalline silicon carbide substrate, at said face, and extending between said source and said gate.
Claim 4
Dependent Claim
38 words
A silicon carbide field effect transistor according to claim 2 further comprising a third amorphous silicon carbide region in said monocrystalline silicon carbide substrate, at said face, adjacent and surrounding said source and drain regions and said gate.
Claim 5
Dependent Claim
33 words
A silicon carbide field effect transistor according to claim 3 wherein said third amorphous silicon carbide region is thick compared to said amorphous silicon carbide region and said second amorphous silicon carbide region.
Claim 6
Dependent Claim
21 words
A silicon carbide field effect transistor according to claim 1 wherein said amorphous silicon carbide region includes electrically inactive ions therein.
Claim 7
Dependent Claim
34 words
A silicon carbide field effect transistor according to claim 3 wherein said amorphous silicon carbide region, said second amorphous silicon carbide region and said third amorphous silicon carbide region include electrically inactive ions therein.
Claim 8
Dependent Claim
18 words
A silicon carbide field effect transistor according to claim 6 wherein said electrically inactive ions are argon ions.
Claim 9
Dependent Claim
25 words
A silicon carbide field effect transistor according to claim 1 wherein said gate comprises a metal gate directly on said face, to provide a MESFET.
Claim 10
Dependent Claim
80 words
A silicon carbide field effect transistor according to claim 8 further comprising: a source electrode on said face electrically contacting said source region, and a drain electrode on said face electrically contacting said drain region, said source electrode, said drain electrode and said metal gate all comprising titanium, such that said source electrode and said drain electrode form ohmic contacts with said source region and said drain region, respectively, and said metal gate forms a rectifying contact with said face.
Claim 11
Dependent Claim
59 words
A silicon carbide field effect transistor according to claim 1 wherein said monocrystalline silicon carbide substrate is doped at a predetermined dopant charge between said spaced apart source and drain regions, said predetermined dopant charge being equal to the product of the dielectric constant of said monocrystalline silicon carbide substrate and the breakdown electric field strength of silicon carbide.
Claim 12
Dependent Claim
89 words
A silicon carbide MESFET comprising: a monocrystalline silicon carbide substrate; spaced apart source and drain regions in said monocrystalline silicon carbide substrate, extending to a face thereof; a metal gate directly on said face between said spaced apart source and drain regions; and electric field equalizing means, in said monocrystalline silicon carbide substrate, at said face, and extending between said drain and said metal gate, for equalizing the electric field between said drain and said metal gate to thereby increase the drain breakdown voltage of said silicon carbide MESFET.
Claim 13
Dependent Claim
89 words
A silicon carbide MESFET comprising: a monocrystalline silicon carbide substrate; spaced apart source and drain regions in said monocrystalline silicon carbide substrate, extending to a face thereof; a metal gate directly on said face between said spaced apart source and drain regions; and electric field equalizing means, in said monocrystalline silicon carbide substrate, at said face, and extending between said drain and said metal gate, for equalizing the electric field between said drain and said metal gate to thereby increase the drain breakdown voltage of said silicon carbide MESFET.
Claim 14
Dependent Claim
57 words
A silicon carbide MESFET according to claim 11 further comprising second electric field equalizing means, in said monocrystalline silicon carbide substrate, at said face, and extending between said source and said metal gate, for equalizing the electric field between said source and said metal gate to thereby increase the source breakdown voltage of said silicon carbide MESFET.
Claim 15
Dependent Claim
55 words
A silicon carbide MESFET according to claim 12 wherein said electric field equalizing means and said second electric field equalizing means comprise first and second amorphous silicon carbide regions in said monocrystalline silicon carbide substrate at said face, extending between said drain and said metal gate and between said source and said metal gate, respectively.
Claim 16
Dependent Claim
37 words
A silicon carbide MESFET according to claim 13 further comprising a third amorphous silicon carbide region in said monocrystalline silicon carbide substrate, at said face, adjacent and surrounding said source and drain regions and said metal gate.
Claim 17
Dependent Claim
23 words
A silicon carbide MESFET according to claim 14 wherein said first, second and third amorphous silicon carbide regions include electrically inactive ions therein.
Claim 18
Dependent Claim
78 words
A silicon carbide MESFET according to claim 11 further comprising: a source electrode on said face electrically contacting said source region, and a drain electrode on said face electrically contacting said drain region, said source electrode, said drain electrode and said metal gate all comprising titanium, such that said source electrode and said drain electrode form ohmic contacts with said source region and said drain region, respectively, and said metal gate forms a rectifying contact with said face.
Claim 19
Dependent Claim
57 words
A silicon carbide MESFET according to claim 11 wherein said monocrystalline silicon carbide substrate is doped at a predetermined dopant charge between said spaced apart source and drain regions, said predetermined dopant charge being equal to the product of the dielectric constant of said monocrystalline silicon carbide substrate and the breakdown electric field strength of silicon carbide.
Claim 20
Dependent Claim
175 words
A silicon carbide MESFET comprising: a monocrystalline silicon carbide substrate including a first monocrystalline silicon carbide region of first conductivity type, and a second monocrystalline silicon carbide region of second conductivity type on said first monocrystalline silicon carbide region, said second monocrystalline silicon carbide region having a face opposite said first monocrystalline silicon carbide region; spaced apart source and drain regions in said second monocrystalline silicon carbide region, extending to said face; a metal gate directly on said face between said spaced apart source and drain regions; a first amorphous silicon carbide region in said second monocrystalline silicon carbide region, at said face, and extending between said drain and said metal gate; a second amorphous silicon carbide region in said second monocrystalline silicon carbide region, at said face, and extending between said source and said metal gate; and a third amorphous silicon carbide region in said second monocrystalline silicon carbide region, adjacent and surrounding said MESFET, and extending from said face, through said second monocrystalline silicon carbide region and into first monocrystalline silicon carbide region.
Claim 21
Dependent Claim
175 words
A silicon carbide MESFET comprising: a monocrystalline silicon carbide substrate including a first monocrystalline silicon carbide region of first conductivity type, and a second monocrystalline silicon carbide region of second conductivity type on said first monocrystalline silicon carbide region, said second monocrystalline silicon carbide region having a face opposite said first monocrystalline silicon carbide region; spaced apart source and drain regions in said second monocrystalline silicon carbide region, extending to said face; a metal gate directly on said face between said spaced apart source and drain regions; a first amorphous silicon carbide region in said second monocrystalline silicon carbide region, at said face, and extending between said drain and said metal gate; a second amorphous silicon carbide region in said second monocrystalline silicon carbide region, at said face, and extending between said source and said metal gate; and a third amorphous silicon carbide region in said second monocrystalline silicon carbide region, adjacent and surrounding said MESFET, and extending from said face, through said second monocrystalline silicon carbide region and into first monocrystalline silicon carbide region.
Claim 22
Dependent Claim
70 words
A silicon carbide MESFET according to claim 18 wherein said first monocrystalline silicon carbide region comprises: a first monocrystalline silicon carbide portion adjacent said second monocrystalline silicon carbide region; and a second monocrystalline silicon carbide portion opposite said second monocrystalline silicon carbide region, said second portion being more highly doped than said first portion; and wherein said MESFET further comprises an electrode on said second portion, opposite said first portion.
Claim 23
Dependent Claim
58 words
A silicon carbide MESFET according to claim 19 wherein said second monocrystalline silicon carbide portion is a monocrystalline silicon carbide substrate, wherein said first monocrystalline silicon carbide portion is an epitaxial silicon carbide layer of said first conductivity type and wherein said second monocrystalline silicon carbide region is an epitaxial silicon carbide layer of said second conductivity type.
Claim 24
Dependent Claim
33 words
A silicon carbide MESFET according to claim 18 wherein said first amorphous silicon carbide region, said second amorphous silicon carbide region and said third amorphous silicon carbide region include electrically inactive ions therein.
Claim 25
Dependent Claim
16 words
A silicon carbide MESFET according to claim 21 wherein said electrically inactive ions are argon ions.
Claim 26
Dependent Claim
78 words
A silicon carbide MESFET according to claim 18 further comprising: a source electrode on said face electrically contacting said source region, and a drain electrode on said face electrically contacting said drain region, said source electrode, said drain electrode and said metal gate all comprising titanium, such that said source electrode and said drain electrode form ohmic contacts with said source region and said drain region, respectively, and said metal gate forms a rectifying contact with said face.
Claim 27
Dependent Claim
50 words
A silicon carbide MESFET according to claim 18 wherein said second monocrystalline silicon carbide region is doped at a predetermined dopant charge, said predetermined dopant charge being equal to the product of the dielectric constant of said monocrystalline silicon carbide substrate and the breakdown electric field strength of silicon carbide.
Claim 28
Dependent Claim
182 words
A silicon carbide MESFET comprising: a monocrystalline silicon carbide substrate including a first monocrystalline silicon carbide region of first conductivity type, and a second monocrystalline silicon carbide region of second conductivity type in said first monocrystalline silicon carbide region, at a face thereof, said second monocrystalline silicon carbide region defining a junction with said first monocrystalline silicon carbide region, said junction extending adjacent said face; spaced apart source and drain regions in said second monocrystalline silicon carbide region, extending to said face; a metal gate directly on said face, between said spaced apart source and drain regions; a first amorphous silicon carbide region in said second monocrystalline silicon carbide region, at said face, and extending between said drain and said metal gate; a second amorphous silicon carbide region in said second monocrystalline silicon carbide region, at said face, and extending between said source and said metal gate; and a third amorphous silicon carbide region adjacent and surrounding said MESFET, and extending from said second monocrystalline silicon carbide region, across said junction and to said first monocrystalline silicon carbide region at said face.
Claim 29
Dependent Claim
182 words
A silicon carbide MESFET comprising: a monocrystalline silicon carbide substrate including a first monocrystalline silicon carbide region of first conductivity type, and a second monocrystalline silicon carbide region of second conductivity type in said first monocrystalline silicon carbide region, at a face thereof, said second monocrystalline silicon carbide region defining a junction with said first monocrystalline silicon carbide region, said junction extending adjacent said face; spaced apart source and drain regions in said second monocrystalline silicon carbide region, extending to said face; a metal gate directly on said face, between said spaced apart source and drain regions; a first amorphous silicon carbide region in said second monocrystalline silicon carbide region, at said face, and extending between said drain and said metal gate; a second amorphous silicon carbide region in said second monocrystalline silicon carbide region, at said face, and extending between said source and said metal gate; and a third amorphous silicon carbide region adjacent and surrounding said MESFET, and extending from said second monocrystalline silicon carbide region, across said junction and to said first monocrystalline silicon carbide region at said face.
Claim 30
Dependent Claim
70 words
A silicon carbide MESFET according to claim 25 wherein said first monocrystalline silicon carbide region comprises: a first monocrystalline silicon carbide portion adjacent said second monocrystalline silicon carbide region; and a second monocrystalline silicon carbide portion opposite said second monocrystalline silicon carbide region, said second portion being more highly doped than said first portion; and wherein said MESFET further comprises a contact on said second portion, opposite said first portion.
Claim 31
Dependent Claim
58 words
A silicon carbide MESFET according to claim 26 wherein said second monocrystalline silicon carbide portion is a monocrystalline silicon carbide substrate, wherein said first monocrystalline silicon carbide portion is an epitaxial silicon carbide layer of said first conductivity type and wherein said second monocrystalline silicon carbide region is an implanted silicon carbide region of said second conductivity type.
Claim 32
Dependent Claim
33 words
A silicon carbide MESFET according to claim 25 wherein said first amorphous silicon carbide region, said second amorphous silicon carbide region and said third amorphous silicon carbide region include electrically inactive ions therein.
Claim 33
Dependent Claim
16 words
A silicon carbide MESFET according to claim 28 wherein said electrically inactive ions are argon ions.
Claim 34
Dependent Claim
78 words
A silicon carbide MESFET according to claim 25 further comprising: a source electrode on said face electrically contacting said source region, and a drain electrode on said face electrically contacting said drain region, said source electrode, said drain electrode and said metal gate all comprising titanium, such that said source electrode and said drain electrode form ohmic contacts with said source region and said drain region, respectively, and said metal gate forms a rectifying contact with said face.
Claim 35
Dependent Claim
50 words
A silicon carbide MESFET according to claim 25 wherein said second monocrystalline silicon carbide region is doped at a predetermined dopant charge, said predetermined dopant charge being equal to the product of the dielectric constant of said monocrystalline silicon carbide substrate and the breakdown electric field strength of silicon carbide.
References Cited (Backward Citations)
US5270244A
Cited
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1998-03-20 | 1998-09-19 | 1999-03-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-03-20 | 2002-09-19 | 2003-03-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-03-20 | 2006-09-19 | 2007-03-21 | $7700.00 | Window Closed / Lapsed |