Patent EP0408252A2 successfully refreshed from Google Patents.
EP0408252A2
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EP
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Heterojunction bipolar transistor
Assignee: AT&T Inc
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Filing: 1990-07-05
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Granted: —
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Expires: 2010-07-05
Abstract
Abstract A scalable and relatively easily manufacturable heterojunction bipolar transistor (HBT) comprises a thin (exemplarily 5-25 nm) emitter layer (15) that serves as an etch stop layer and that furthermore passivates the extrinsic base region. The portion of the emitter layer that overlies the extrinsic base region is essentially fully depleted at all bias voltages in the normal operating range of the transistor. Base contact is established through the emitter layer, exemplarily by means of a metallized region (16) on the emitter layer. A novel technique for carbon doping is also disclosed. Use of the novel technique makes possible a further embodiment of the inventive HBT, wherein base contact is made by means of Be implantation into the emitter layer.
Inventors
- 👤 Leda Maria Lunardi
- 👤 Roger John Malik
- 👤 Robert William Ryan
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-05 15:20
CPC Classifications
H; H10; H10D; H10D10/00; H10D10/80; H10D10/821; H10D10/891; H10D10/01; H10D10/021; H10D62/00; H10D62/80; H10D62/82; H10D62/824; H10D62/826; H10P; H10P32/00
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
220 words
An article comprising a heterojunction bipolar transistor comprising a semiconductor body comprising an emitter region, a collector region, and a base region (14) between the emitter and the collector regions, and further comprising means for making electrical contact with the emitter, base, and collector regions, respectively, with the emitter region comprising first semiconductor material that has a larger bandgap than the base region material and is of the opposite conductivity type from the base region material, the emitter region and base region being epitaxial with each other and with the collector region, associated with the transistor are bias voltages within a normal operating range of the transistor, associated with the emitter region being an emitter stripe width W, associated with the base region being an "extrinsic" base region; CHARACTERIZED IN THAT a) the emitter region comprises a layer (15) of first semiconductor material that overlies substantially all of the base region, the thickness of the layer chosen such that the portion of the layer that overlies the extrinsic base region is substantially fully depleted of conduction electrons at all bias voltages within the normal operating range of the transistor; and b) the means for making electrical contact to the base region comprise a region on the layer of first semiconductor material that provides an ohmic contact with the base region.
Claim 2
Dependent Claim
220 words
An article comprising a heterojunction bipolar transistor comprising a semiconductor body comprising an emitter region, a collector region, and a base region (14) between the emitter and the collector regions, and further comprising means for making electrical contact with the emitter, base, and collector regions, respectively, with the emitter region comprising first semiconductor material that has a larger bandgap than the base region material and is of the opposite conductivity type from the base region material, the emitter region and base region being epitaxial with each other and with the collector region, associated with the transistor are bias voltages within a normal operating range of the transistor, associated with the emitter region being an emitter stripe width W, associated with the base region being an "extrinsic" base region; CHARACTERIZED IN THAT a) the emitter region comprises a layer (15) of first semiconductor material that overlies substantially all of the base region, the thickness of the layer chosen such that the portion of the layer that overlies the extrinsic base region is substantially fully depleted of conduction electrons at all bias voltages within the normal operating range of the transistor; and b) the means for making electrical contact to the base region comprise a region on the layer of first semiconductor material that provides an ohmic contact with the base region.
Claim 3
Dependent Claim
26 words
The article of claim 1, wherein the thickness of the layer of first material is in the range 5-25 nm, and wherein W ≦ 1 µm.
Claim 4
Dependent Claim
27 words
The article of claim 1, wherein the layer of first material serves as a base surface passivation layer and contactingly covers substantially all of the base region.
Claim 5
Dependent Claim
51 words
The article of claim 1, wherein the first layer material is selected from the group consisting of doped AlGaAs, AlGaSb, InP, InAlAs, GaAsP, Si, GaP, GaAs, and CdTe, and wherein the base region material is selected from the group consisting of doped GaAs, InGaAs, AlGaAs, GaSb, SiGe, Si, Ge, and HgTe.
Claim 6
Dependent Claim
19 words
The article of claim 1, wherein the region on the layer of first semiconductor material is a metallized region.
Claim 7
Dependent Claim
26 words
The article of claim 1, wherein the base region is carbon doped, and wherein the region on the layer of first semiconductor material comprises Be-implanted material.
Claim 8
Independent Claim
219 words
A method of producing an article comprising a heterojunction bipolar transistor comprising a semiconductor body comprising an emitter region, a collector region, and a base region between the emitter and collector regions, and further comprising means for making electrical contact with the emitter, base and collector regions, respectively; the method comprising a) providing a semiconductor substrate with a multiplicity of semiconductor layers thereon, the multiplicity comprising, in sequence, a collector layer of a first conductivity type, a base layer of a second conductivity type, an emitter layer of the first conductivity type, and at least one further layer on the emitter layer, the material of the emitter layer chosen to have a larger bandgap than the material of the base layer; b) removing the at least one further layer in selected regions, thereby exposing selected portions of the emitter layer in the semiconductor body; and c) providing the means for making electrical contact with the emitter, base and collector regions; CHARACTERIZED IN THAT the method further comprises d) removing selected portions of the emitter layer and of the base layer such that the emitter layer covers substantially all of the base layer in the semiconductor body; and e) step c) comprises causing the formation of an ohmic contact between a region on the emitter layer and the base region.
Claim 9
Independent Claim
219 words
A method of producing an article comprising a heterojunction bipolar transistor comprising a semiconductor body comprising an emitter region, a collector region, and a base region between the emitter and collector regions, and further comprising means for making electrical contact with the emitter, base and collector regions, respectively; the method comprising a) providing a semiconductor substrate with a multiplicity of semiconductor layers thereon, the multiplicity comprising, in sequence, a collector layer of a first conductivity type, a base layer of a second conductivity type, an emitter layer of the first conductivity type, and at least one further layer on the emitter layer, the material of the emitter layer chosen to have a larger bandgap than the material of the base layer; b) removing the at least one further layer in selected regions, thereby exposing selected portions of the emitter layer in the semiconductor body; and c) providing the means for making electrical contact with the emitter, base and collector regions; CHARACTERIZED IN THAT the method further comprises d) removing selected portions of the emitter layer and of the base layer such that the emitter layer covers substantially all of the base layer in the semiconductor body; and e) step c) comprises causing the formation of an ohmic contact between a region on the emitter layer and the base region.
Claim 10
Dependent Claim
38 words
Method of claim 7, wherein step a) comprises heating a carbon member such that a portion of the carbon sublimes, with some of the sublimated carbon being incorporated into at least one of the multiplicity of semiconductor layers.
References Cited (Backward Citations)
No citation records indexed.
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