US4422087A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Self-aligned short channel MESFET
Assignee: Xerox Corp
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Filing: 1980-06-03
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Granted: 1983-12-20
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Expires: 2000-06-03
Abstract
Abstract A MESFET with a relatively short channel and small source-to-gate and drain-to-gate spacing for minimal series resistance and maximum frequency response having no alignments or critical steps. In particular, a mask is used to define schottky metal as ohmic metal from the source/drain areas across a relatively undoped bare substrate to within a predetermined distance L of the schottky gate wherein the predetermined distance is a non-critical electrical short-circuit as to the surface of the bare substrate. Thus the source-to-gate and drain-to-gate distances are non-critical because the predetermined distance L can be as critically controlled as the single mask that defines it.
Inventors
- 👤 Ram S. Ronen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 11:50
CPC Classifications
H; H10; H10D; H10D64/00; H10D64/60; H10D64/64; H10D30/00; H10D30/80; H10D30/87
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
225 words
A solid state MESFET device including: a substrate layer; a source region, of a given doping concentration, formed in said substrate and having an outer surface extending along a surface of said substrate layer; a drain region, of a given doping concentration, formed in said substrate and having an outer surface extending along said surface of said substrate layer; the portion of said substrate layer extending from said source region to said drain region along said surface providing a channel region having an outer surface, said channel region having a doping concentration less than the doping concentrations of said source region and said drain region; the outer surfaces of said source region, said drain region and said channel region lying in a common plane; a Schottky gate contact to said channel region; a metallic drain contact contacting at least a portion of said outer surface of said drain region and a portion of said outer surface of said channel; a metallic source contact contacting at least a portion of the outer surface of said source region and a portion of said outer surface of said channel; said portions of the outer surface of said channel region in contact with said metallic contacts being short-circuited by such metallic contacts whereby the effective length of said channel region is determined by the distance between said metallic contacts.
Claim 2
Dependent Claim
225 words
A solid state MESFET device including: a substrate layer; a source region, of a given doping concentration, formed in said substrate and having an outer surface extending along a surface of said substrate layer; a drain region, of a given doping concentration, formed in said substrate and having an outer surface extending along said surface of said substrate layer; the portion of said substrate layer extending from said source region to said drain region along said surface providing a channel region having an outer surface, said channel region having a doping concentration less than the doping concentrations of said source region and said drain region; the outer surfaces of said source region, said drain region and said channel region lying in a common plane; a Schottky gate contact to said channel region; a metallic drain contact contacting at least a portion of said outer surface of said drain region and a portion of said outer surface of said channel; a metallic source contact contacting at least a portion of the outer surface of said source region and a portion of said outer surface of said channel; said portions of the outer surface of said channel region in contact with said metallic contacts being short-circuited by such metallic contacts whereby the effective length of said channel region is determined by the distance between said metallic contacts.
Claim 3
Dependent Claim
285 words
A solid state MESFET device including: a substrate layer; a source region, of a given doping concentration, formed in said substrate and having an outer surface extending along a surface of said substrate layer; a drain region, of a given doping concentration, formed in said substrate and having an outer surface extending along said surface of said substrate layer; the portion of said substrate layer extending from said source region to said drain region along said surface providing a channel region having an outer surface, said channel region having a doping concentration less than the doping concentrations of said source region and said drain region; the outer surfaces of said source region, said drain region and said channel region lying in a common plane; a Schottky gate contact to said channel region; a metallic drain contact having a first portion contacting at least a portion of said outer surface of said drain region and an extended portion contacting a portion of said outer surface of said channel region whereby the drain region is short-circuited to the end of said extended drain contact portion such that the effective drain/gate length is measured from the gate contact to said end of said extended drain contact portion nearest the gate contact; and a metallic source contact having a first portion contacting at least a portion of said outer surface of said source region and an extended portion contacting a portion of said outer surface of said channel region whereby the source region is short-circuited to the end of said extended source contact portion such that the effective source/gate length is measured from the gate contact to the end of the extended source contact portion nearest the gate contact.
Claim 4
Dependent Claim
285 words
A solid state MESFET device including: a substrate layer; a source region, of a given doping concentration, formed in said substrate and having an outer surface extending along a surface of said substrate layer; a drain region, of a given doping concentration, formed in said substrate and having an outer surface extending along said surface of said substrate layer; the portion of said substrate layer extending from said source region to said drain region along said surface providing a channel region having an outer surface, said channel region having a doping concentration less than the doping concentrations of said source region and said drain region; the outer surfaces of said source region, said drain region and said channel region lying in a common plane; a Schottky gate contact to said channel region; a metallic drain contact having a first portion contacting at least a portion of said outer surface of said drain region and an extended portion contacting a portion of said outer surface of said channel region whereby the drain region is short-circuited to the end of said extended drain contact portion such that the effective drain/gate length is measured from the gate contact to said end of said extended drain contact portion nearest the gate contact; and a metallic source contact having a first portion contacting at least a portion of said outer surface of said source region and an extended portion contacting a portion of said outer surface of said channel region whereby the source region is short-circuited to the end of said extended source contact portion such that the effective source/gate length is measured from the gate contact to the end of the extended source contact portion nearest the gate contact.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-12-19 | 1987-06-20 | 1987-12-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-12-19 | 1991-06-20 | 1991-12-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-12-19 | 1995-06-20 | 1995-12-20 | $7700.00 | Window Closed / Lapsed |