US5077590A
Expired / Lapsed
US
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High voltage semiconductor device
Assignee: Fuji Electric Co Ltd
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Filing: 1990-07-12
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Granted: 1991-12-31
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Expires: 2010-07-12
Abstract
Abstract The present invention relates to high voltage semiconductor devices with an integrated Zener diode used as a protective element against overvoltage. The Zener breakdown voltage can be increased while providing high operating voltage to the whole semiconductor device, by forming a region of lower impurity concentration around the cathode of the Zener diode. This lowers the current amplification factor of a parasitic transistor, enabling an increase in the Zener breakdown voltage without decreasing the withstand voltage of the whole semiconductor device.
Inventors
- 👤 Tatsuhiko Fujihira
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 19:09
CPC Classifications
H; H10; H10D; H10D8/00; H10D8/20; H10D8/25
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
190 words
In a semiconductor device including a semiconductor substrate of a first conductivity type, wherein an associated Zener diode is used as a protective element against overvoltage, the combination comprising: an anode region of a second conductivity type formed at a surface region of said substrate; a cathode region of a first conductivity type provided at a surface region within said anode region, said cathode and anode regions having an impurity concentration effective to comprise a Zener diode of desired characteristics; and a third region of a first conductivity type surrounding said cathode region and having an impurity concentration lower than said cathode region; whereby, the current amplification factor of a parasitic bipolar transistor inherently introduced by the basic structure of the Zener diode formed by said cathode region as an emitter region, said anode region as a base region and said substrate as a collector region is primarily determined by said lower impurity concentration of said third region, and the breakdown voltage of the Zener diode is primarily determined by the impurity concentration of said cathode and anode regions, so that the maximum operating voltage of the device is improved.
Claim 2
Dependent Claim
190 words
In a semiconductor device including a semiconductor substrate of a first conductivity type, wherein an associated Zener diode is used as a protective element against overvoltage, the combination comprising: an anode region of a second conductivity type formed at a surface region of said substrate; a cathode region of a first conductivity type provided at a surface region within said anode region, said cathode and anode regions having an impurity concentration effective to comprise a Zener diode of desired characteristics; and a third region of a first conductivity type surrounding said cathode region and having an impurity concentration lower than said cathode region; whereby, the current amplification factor of a parasitic bipolar transistor inherently introduced by the basic structure of the Zener diode formed by said cathode region as an emitter region, said anode region as a base region and said substrate as a collector region is primarily determined by said lower impurity concentration of said third region, and the breakdown voltage of the Zener diode is primarily determined by the impurity concentration of said cathode and anode regions, so that the maximum operating voltage of the device is improved.
Claim 3
Dependent Claim
30 words
A semiconductor device according to claim 1 in which the Zener diode includes: an anode electrode connected to said anode region; and a cathode electrode connected to said cathode region.
Claim 4
Dependent Claim
86 words
A semiconductor device according to claim 1 in which the Zener diode includes: one or more high impurity concentration regions of second conductivity type semiconductor material formed at the surface of the anode region surrounding the cathode region and coupled to the semiconductor substrate; an anode electrode connected to one said high impurity concentration region; and a cathode electrode connected to said cathode; whereby said one or more high impurity concentration regions suppress parasitic action between the Zener diode and elements adjacent to the Zener diode.
Claim 5
Dependent Claim
196 words
In a semiconductor device including a semiconductor substrate of a first conductivity type, wherein an associated bidirectional Zener diode is used as a protective element against a bidirectional overvoltage, the combination comprising: an anode region of a second conductivity type formed at a surface region of said substrate; two cathode regions of a first conductivity type provided at a surface region within said anode region, said cathode and anode regions having an impurity concentration effective to comprise a Zener diode of desired characteristics; and one or more third regions of a first conductivity type, each surrounding a cathode region and having an impurity concentration lower than said cathode regions; whereby, the current amplification factor of a parasitic bipolar transistor inherently introduced by the basic structure of the Zener diode formed by said cathode regions as an emitter region, said anode region as a base region and said substrate as a collector region is primarily determined by said lower impurity concentration of said third region, and the breakdown voltage of the Zener diode is primarily determined by the impurity concentration of said cathode and anode regions, so that the maximum operating voltage of the device is improved.
Claim 6
Dependent Claim
196 words
In a semiconductor device including a semiconductor substrate of a first conductivity type, wherein an associated bidirectional Zener diode is used as a protective element against a bidirectional overvoltage, the combination comprising: an anode region of a second conductivity type formed at a surface region of said substrate; two cathode regions of a first conductivity type provided at a surface region within said anode region, said cathode and anode regions having an impurity concentration effective to comprise a Zener diode of desired characteristics; and one or more third regions of a first conductivity type, each surrounding a cathode region and having an impurity concentration lower than said cathode regions; whereby, the current amplification factor of a parasitic bipolar transistor inherently introduced by the basic structure of the Zener diode formed by said cathode regions as an emitter region, said anode region as a base region and said substrate as a collector region is primarily determined by said lower impurity concentration of said third region, and the breakdown voltage of the Zener diode is primarily determined by the impurity concentration of said cathode and anode regions, so that the maximum operating voltage of the device is improved.
Claim 7
Dependent Claim
21 words
A semiconductor device according to claim 4 in which the Zener diode includes: a cathode electrode connected to each cathode region.
Claim 8
Dependent Claim
67 words
A semiconductor device according to claim 5 in which the Zener diode includes: one or more high impurity concentration regions of second conductivity type semiconductor material formed at the surface of the anode region surrounding the cathode regions and coupled to the semiconductor substrate; whereby said one or more high impurity concentration regions suppress parasitic action between the Zener diode and elements adjacent to the Zener diode.
References Cited (Backward Citations)
US4920445A
Cited
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