US4561008A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ballasted, gate controlled semiconductor device
Assignee: Fairchild Semiconductor Corp
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Filing: 1978-01-18
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Granted: 1985-12-24
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Expires: 1998-01-18
Abstract
Abstract A gate controlled semiconductor device comprises a cathode region having a current defocusing region associated therewith. The defocusing region is unmetallized but substantially completely surrounded by cathode metallization. The defocusing region comprises only a relatively small percentage of the total cathode region and conducts current during the on-state of the device. However, during turn-off of the device substantially all of the conducting plasma is forced to flow in the defocusing region.
Inventors
- 👤 Hans W. Becke
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 21:21
CPC Classifications
H; H10; H10D; H10D18/00; H10D18/60; H10D64/00; H10D64/20; H10D64/23; H10D64/233
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
183 words
A gate controlled semiconductor device comprising: a body of semiconductor material having first and second major opposing surfaces; an anode region having one type conductivity adjacent said second surface; a base region having a second type conductivity adjacent said anode region and forming a first PN junction at the interface therewith; a gate region having said one type conductivity adjacent said base region and forming a second PN junction at the interface therewith, said gate region extending to said first surface; a cathode region having said second type conductivity adjacent said first surface and extending into said gate region and forming a third PN junction at the interface therewith, said third PN junction terminating at said first surface; said cathode region including an integral defocusing portion, a cathode electrode overlying and electrically contacting said cathode region without contacting said defocusing portion; said defocusing portion being substantially completely surrounded by the portion of said cathode region which is contacted by said cathode electrode; and said base region extending through said anode region to said second surface in substantial vertical alignment with said defocusing portion.
Claim 2
Dependent Claim
183 words
A gate controlled semiconductor device comprising: a body of semiconductor material having first and second major opposing surfaces; an anode region having one type conductivity adjacent said second surface; a base region having a second type conductivity adjacent said anode region and forming a first PN junction at the interface therewith; a gate region having said one type conductivity adjacent said base region and forming a second PN junction at the interface therewith, said gate region extending to said first surface; a cathode region having said second type conductivity adjacent said first surface and extending into said gate region and forming a third PN junction at the interface therewith, said third PN junction terminating at said first surface; said cathode region including an integral defocusing portion, a cathode electrode overlying and electrically contacting said cathode region without contacting said defocusing portion; said defocusing portion being substantially completely surrounded by the portion of said cathode region which is contacted by said cathode electrode; and said base region extending through said anode region to said second surface in substantial vertical alignment with said defocusing portion.
Claim 3
Dependent Claim
238 words
A gate controlled semiconductor device comprising: a body of semiconductor material having first and second major opposing surfaces; an anode region having one type conductivity adjacent said second surface; a base region having a second type conductivity adjacent said anode region and forming a first PN junction at the interface therewith; a gate region having said one type conductivity adjacent said base region and forming a second PN junction at the interface therewith, said gate region extending to said first surface; a cathode region having said second type conductivity adjacent said first surface and extending into said gate region and forming a third PN junction at the interface therewith, said third PN junction terminating at said first surface; said cathode region including an integral defocusing portion; a cathode electrode overlying and electrically contacting said cathode region without contacting said defocusing portion; said defocusing portion being substantially completely surrounded by the portion of said cathode region which is contacted by said cathode electrode; said cathode region having the shape of a comb, said comb having a back and a plurality of finger portions extending therefrom; there being one of said defocusing portion associated with each of said fingers; each said defocusing portion comprising less than about thirty percent (30%) of the area of each of said fingers; and said base region extending through said anode region to said second surface in substantial vertical alignment with each said defocusing portion.
Claim 4
Dependent Claim
238 words
A gate controlled semiconductor device comprising: a body of semiconductor material having first and second major opposing surfaces; an anode region having one type conductivity adjacent said second surface; a base region having a second type conductivity adjacent said anode region and forming a first PN junction at the interface therewith; a gate region having said one type conductivity adjacent said base region and forming a second PN junction at the interface therewith, said gate region extending to said first surface; a cathode region having said second type conductivity adjacent said first surface and extending into said gate region and forming a third PN junction at the interface therewith, said third PN junction terminating at said first surface; said cathode region including an integral defocusing portion; a cathode electrode overlying and electrically contacting said cathode region without contacting said defocusing portion; said defocusing portion being substantially completely surrounded by the portion of said cathode region which is contacted by said cathode electrode; said cathode region having the shape of a comb, said comb having a back and a plurality of finger portions extending therefrom; there being one of said defocusing portion associated with each of said fingers; each said defocusing portion comprising less than about thirty percent (30%) of the area of each of said fingers; and said base region extending through said anode region to said second surface in substantial vertical alignment with each said defocusing portion.
Claim 5
Dependent Claim
28 words
A device as claimed in claim 1 wherein: said defocusing portion is completely surrounded by said portion of said cathode region which is contacted by said cathode electrode.
Claim 6
Dependent Claim
24 words
A device as claimed in claim 1 wherein: said defocusing portion is located about the two-dimensional geometrical center of gravity of said cathode region.
Claim 7
Dependent Claim
42 words
A device as claimed in claim 1 wherein: said cathode region has the shape of a comb, said comb having a back and a plurality of finger portions extending therefrom; there being one said defocusing portion associated with each of said fingers.
Claim 8
Dependent Claim
27 words
A device as claimed in claim 5 wherein: each said defocusing portion comprises less than about thirty percent (30%) of the area of each of said fingers.
Claim 9
Dependent Claim
25 words
A device as claimed in claim 1 wherein: said defocusing portion comprises less than about thirty percent (30%) of the area of said cathode region.
Claim 10
Dependent Claim
21 words
A device as claimed in claim 1 wherein: said cathode electrode overlies but is substantially electrically isolated from said defocusing portion.
References Cited (Backward Citations)
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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) | 1988-12-23 | 1989-06-24 | 1989-12-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-12-23 | 1993-06-24 | 1993-12-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-12-23 | 1997-06-24 | 1997-12-24 | $7700.00 | Window Closed / Lapsed |