EP0057024A1
Expired / Lapsed
EP
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Semiconductor device having a safety device
Assignee: Koninklijke Philips NV
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Filing: 1982-01-12
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Granted: —
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Expires: 2002-01-12
Abstract
Abstract Semiconductor device having a safety device (4) comprising an improved lateral bipolar transistor structure (5). The improvement is obtained by incorporating an auxiliary field effect transistor (6) which has the emitter (8) as source zone and the collector (9) as drain zone and in which the threshold voltage of the auxiliary field effect transistor is lower than the avalanche breakdown voltage of the collector- base junction of the lateral transistor. As a result of this the lateral transistor switches sooner, at a lower voltage, to the readily conductive on-state.
Inventors
- 👤 Hendrik Cornelis De Graaff
- 👤 Wilhelmus Gerlachus Voncken
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-31 22:01
CPC Classifications
H; H10; H10D; H10D89/00; H10D89/60; H10D89/601; H10D84/00; H10D84/01; H10D84/0123; H10D84/0126; H10D84/0144; H10D84/02; H10D84/03; H10D84/038; H10D84/40; H10D84/401; H10D84/403; H10D84/409
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
347 words
A semiconductor device comprising at least one circuit element and having a semiconductor body, in which said semiconductor body comprises at least a first and a second electrode, which first electrode is connected to the said circuit element, in which a safety device is provided between the said first and second electrode so as to protect the first electrode from excess voltages above a previously determined value with respect to the voltage of the second electrode, which safety device comprises a lateral bipolar transistor having an emitter zone and a collector zone of a first conductivity type which adjoin a surface of the semiconductor body in laterally separated places and having an adjoining base region of a second conductivity type which forms a first and a second p - n junction with the said emitter zone and collector zone respectively, an insulating layer being present on the said surface of the semiconductor body, the base region between the said emitter zone and collector zone adjoining the insulating layer, the insulating layer separating first, second and third conductive layers from the said semiconductor body, the first electrode comprising layer which is connected to the said collector zone, the second electrode comprising the second conductive layer which is connected to the said emitter zone and the third conductive layer extending above the said base region between the said emitter zone and collector zone, and the said second junction having a breakdown voltage which is higher than the collector-emitter voltage of the lateral bipolar transistor in the conductive state of said transistor, characterized in that the said first and third conductive layers are conductively connected together and both belong to the said first electrode, the third conductive layer forming a gate electrode of an auxiliary field effect transistor structure which furthermore comprises the emitter zone as source region and the collector zone as drain region, the said auxiliary field effect transistor structure having a threshold voltage which is lower than the said breakdown voltage of the second junction and which is preferably at least equal to the said collector-emitter voltage.
Claim 2
Dependent Claim
347 words
A semiconductor device comprising at least one circuit element and having a semiconductor body, in which said semiconductor body comprises at least a first and a second electrode, which first electrode is connected to the said circuit element, in which a safety device is provided between the said first and second electrode so as to protect the first electrode from excess voltages above a previously determined value with respect to the voltage of the second electrode, which safety device comprises a lateral bipolar transistor having an emitter zone and a collector zone of a first conductivity type which adjoin a surface of the semiconductor body in laterally separated places and having an adjoining base region of a second conductivity type which forms a first and a second p - n junction with the said emitter zone and collector zone respectively, an insulating layer being present on the said surface of the semiconductor body, the base region between the said emitter zone and collector zone adjoining the insulating layer, the insulating layer separating first, second and third conductive layers from the said semiconductor body, the first electrode comprising layer which is connected to the said collector zone, the second electrode comprising the second conductive layer which is connected to the said emitter zone and the third conductive layer extending above the said base region between the said emitter zone and collector zone, and the said second junction having a breakdown voltage which is higher than the collector-emitter voltage of the lateral bipolar transistor in the conductive state of said transistor, characterized in that the said first and third conductive layers are conductively connected together and both belong to the said first electrode, the third conductive layer forming a gate electrode of an auxiliary field effect transistor structure which furthermore comprises the emitter zone as source region and the collector zone as drain region, the said auxiliary field effect transistor structure having a threshold voltage which is lower than the said breakdown voltage of the second junction and which is preferably at least equal to the said collector-emitter voltage.
Claim 3
Dependent Claim
41 words
A semiconductor device as claimed in Claim 1, characterized in that the said circuit element comprises a field effect transistor structure which comprises source and drain regions of the first conductivity type, a thin gate insulation layer and a gate electrode.
Claim 4
Dependent Claim
75 words
A semiconductor device as claimed in Claim 1 or 2, characterized in that above the said base region between the collector zone and the emitter zone of the safety device the insulating layer forms a thick gate insulation layer the thickness of which exceeds that of the said thin gate insulation layer of the circuit element and is at most equal to the thickness of the insulating layer below the first and second conductive layers.
Claim 5
Dependent Claim
65 words
A semiconductor device as claimed in Claims 2 and 3, characterized in that the gate electrode of the circuit element comprises a fourth conductive layer which is covered at least partly with an insulating layer, said insulating layer also having a portion which is present between the third conductive layer and the base region, said portion forming a sub-layer of the thick gate insulation layer.
Claim 6
Dependent Claim
37 words
A semiconductor device as claimed in Claim 3 or 4, characterized in that the said gate insulation layer of the safety device comprises at least a sub-layer obtained by thermal oxidation and a sub-layer obtained by deposition.
Claim 7
Dependent Claim
70 words
A semiconductor device as claimed in one or more of the preceding Claims, characterized in that outside the area occupied by the circuit element and outside the area occupied by the safety device a more highly doped zone of the second conductivity type which adjoins the insulating layer is present at least locally below said layer, said zone being more highly doped than an adjoining part of the semiconductor body.
Claim 8
Dependent Claim
48 words
A semiconductor device as claimed in Claim 6, characterized in that the base reginn between the emitter zone and collector zone has a surface-adjoining more highly doped zone of the second conductivity type which is provided simultaneously with the more highly doped zone mentioned in the preceding Claim.
Claim 9
Dependent Claim
45 words
A semiconductor device as claimed in one or more of the preceding Claims, characterized in that the base region has a collector zone-adjoining more highly dope'd zone of the second conductivity type which is more highly doped than an adjoining part of the base region.
Claim 10
Dependent Claim
43 words
A semiconductor device as claimed in one or more of the preceding Claims, characterized in that the threshold voltage of the auxiliary field effect transistor is at least equal to the supply voltage to be applied to the semi- conductor device during operation.
Claim 11
Dependent Claim
51 words
A semiconductor device as claimed in one or more of the preceding Claims, characterized in that the threshold voltage of the auxiliary field effect transistor is substantially equal to the threshold voltage for parasitic channel formation in regions of the surface of the semi- conductor body not occupied by circuit elements.
Claim 12
Dependent Claim
51 words
A semiconductor device as claimed in one or more of the preceding Claims, characterized in that the threshold voltage of the auxiliary field effect transistor is at least equal to the threshold voltage for parasitic channel formation in regions of the surface of the semiconductor body not occupied by circuit elements.
References Cited (Backward Citations)
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