EP0209986A2
Expired / Lapsed
EP
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Thyristors protected against overvoltage
Assignee: Westinghouse Electric Corp
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Filing: 1986-06-20
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Granted: —
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Expires: 2006-06-20
Abstract
Abstract Thyristor which is self-protected against an overvoltage byacavity formed in an auxiliary gate region and a process for making such a thyristor.
Inventors
- 👤 John Xavier Przybysz
- 👤 Vincent Andrew Toth
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-06 00:41
CPC Classifications
H; H10; H10D; H10D18/00; H10D18/211; H10P; H10P34/00; H10P34/40; H10P34/42
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
364 words
An overvoltage self-protected thyristor which comprises a body of semiconductor material having a top surface, a bottom surface and an edge portion extending between said top and bottom surfaces, characterized in that said thyristor has a cathode base region adjacent to a cathode emitter region, an anode base region adjacent to said cathode base region and an anode emitter region adjacent to said anode base region with a p-n junction between adjacent regions, said cathode emitter region being segmented and extending from said top surface into said body a predetermined first distance, said cathode base region extending from said top surface, where it surrounds said segments of said cathode emitter region, into said body a predetermined second distance, said predetermined second distance being greater than said predetermined first distance, at least one auxiliary gate region extending from said top surface into said body a distance less than said predetermined second distance and being spaced apart from said cathode emitter region and surrounded by said cathode base region within said thyrister, a p-n junction between said auxiliary gate region and said cathode base region, a first metal electrode disposed on and affixed to a portion of said top surface of said body in ohmic electrical contact with a portion of both said cathode emitter region and said cathode base region, a second metal electrode disposed on and affixed to a portion of said top surface of said body in ohmic electrical contact with said cathode base region, and a third metal electrode disposed on and affixed to a portion of said top surface of said body in ohmic electrical contact with a portion of both said auxiliary gate region and said cathode base region, said first, second and third metal electrodes being spaced apart from each other on said top surface, a fourth metal electrode disposed on and affixed to said bottom surface of said body in ohmic electrical contact with said anode emitter region, and walls of said auxiliary gate region forming a cavity within the auxiliary gate region, the cavity extending from the top surface of the body through said auxiliary gate region and into said cathode base region an empirically determined distance.
Claim 2
Dependent Claim
364 words
An overvoltage self-protected thyristor which comprises a body of semiconductor material having a top surface, a bottom surface and an edge portion extending between said top and bottom surfaces, characterized in that said thyristor has a cathode base region adjacent to a cathode emitter region, an anode base region adjacent to said cathode base region and an anode emitter region adjacent to said anode base region with a p-n junction between adjacent regions, said cathode emitter region being segmented and extending from said top surface into said body a predetermined first distance, said cathode base region extending from said top surface, where it surrounds said segments of said cathode emitter region, into said body a predetermined second distance, said predetermined second distance being greater than said predetermined first distance, at least one auxiliary gate region extending from said top surface into said body a distance less than said predetermined second distance and being spaced apart from said cathode emitter region and surrounded by said cathode base region within said thyrister, a p-n junction between said auxiliary gate region and said cathode base region, a first metal electrode disposed on and affixed to a portion of said top surface of said body in ohmic electrical contact with a portion of both said cathode emitter region and said cathode base region, a second metal electrode disposed on and affixed to a portion of said top surface of said body in ohmic electrical contact with said cathode base region, and a third metal electrode disposed on and affixed to a portion of said top surface of said body in ohmic electrical contact with a portion of both said auxiliary gate region and said cathode base region, said first, second and third metal electrodes being spaced apart from each other on said top surface, a fourth metal electrode disposed on and affixed to said bottom surface of said body in ohmic electrical contact with said anode emitter region, and walls of said auxiliary gate region forming a cavity within the auxiliary gate region, the cavity extending from the top surface of the body through said auxiliary gate region and into said cathode base region an empirically determined distance.
Claim 3
Dependent Claim
14 words
A thyristor according to claim 1, characterized in that the semiconductor material is silicon.
Claim 4
Dependent Claim
48 words
A thyristor of claim 1 or 2, characterized in that the cavity extends from that portion of the top surface of the body where said auxiliary gate region is exposed and free of any ohmic electrical contact through said auxiliary gate region and into said cathode base region.
Claim 5
Dependent Claim
30 words
A thyristor according to claim 1, 2 or 3, characterized in that the auxiliary gate region extends into the cathode base region a distance equal to the predetermined first distance.
Claim 6
Dependent Claim
50 words
A thyristor according to any of claims 1 to 4, characterized in that the empirical determined distance is such that a space charge region of the p-n junction between the cathode base region and the anode base region contact the bottom surface of the cavity at a predetermined break overvoltage.
Claim 7
Dependent Claim
92 words
A process for providing overvoltage self-protection in a thyristor having a cathode emitter region, a cathode base region, an anode base region, an anode emitter region and an auxiliary gate region disposed within said cathode base region and extending to a major surface of said thyristor, characterized by connecting a means for measuring the IV characteristic of the thyristor between the anode emitter and the cathode emitter of the thyristor and forming a cavity in said auxiliary gate region with a laser while continuing to monitor the IV characteristic of the thyristor.
Claim 8
Dependent Claim
92 words
A process for providing overvoltage self-protection in a thyristor having a cathode emitter region, a cathode base region, an anode base region, an anode emitter region and an auxiliary gate region disposed within said cathode base region and extending to a major surface of said thyristor, characterized by connecting a means for measuring the IV characteristic of the thyristor between the anode emitter and the cathode emitter of the thyristor and forming a cavity in said auxiliary gate region with a laser while continuing to monitor the IV characteristic of the thyristor.
Claim 9
Dependent Claim
15 words
A process according to claim 6, characterized in that the laser is an Excimer laser.
Claim 10
Dependent Claim
18 words
A process according to claim 7, characterized in that the Excimer laser has a krypton fluoride active medium.
Claim 11
Dependent Claim
21 words
The process of claim 7 or 8 characterized in that the cavity is formed in the presence of an argon atmosphere.
References Cited (Backward Citations)
No citation records indexed.
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