EP0387010A2
Expired / Lapsed
EP
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Hetero-junction bipolar transistor
Assignee: Panasonic Holdings Corp
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Filing: 1990-03-06
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Granted: —
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Expires: 2010-03-06
Abstract
Abstract An object of the present invention is to suppress the surface recombination over the whole area of the external base of a hetero-junction bipolar transistor (HBT), to keep the current gain large, and to reduce the base contact resistance. The HBT of the invention has, as a surface protective film layer, a p-type semiconductor layer which has the higher portential of the energy conduction band than the base layer on an external base outside the junction between the mesa of the n-type emitter layer and the p-type base layer, and a base electrode thereon. Preferably, it has as a base contact layer a p-type semiconductor layer which shows reduced contact resistance with the base electrode on the surface protective layer comprising a p-type semiconductor layer. More preferabiy, it has a structure wherein a base electrode is formed on the base contact layer in contact with the projection part of the emitter electrode to the base contact layers A method of producing this HBT comprises at least the steps of forming an emitter mask on the portion to be an emitter on a multi-layer structure material having an n-type semiconductor layer for forming a collector, a p-type semiconductor layer or forming a base, and an n-type semiconductor layer for forming an emitter in this order from the substrate, and etching by using the emitter mask to form an emitter mesa and to expose a base layer; epitaxially forming as a surface protective film layer a p-type semiconductor layer which show the higher potential of the energy conduction band than the base layer on the external base outside the junction part between the emitter mesa and the base layer by using the emitter mask; and epitaxially forming a base electrode on the p-type surface protective film layer.
Inventors
- 👤 Masanori Inada
- 👤 Akira Ryoji
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-01 07:43
CPC Classifications
H; H10; H10D; H10D10/00; H10D10/01; H10D10/021; H10D10/80; H10D10/821; H10D64/00; H10D64/01; H10D64/011; H10D62/00; H10D62/80; H10D62/82; H10D62/824; H10D62/85; H10D62/852
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
86 words
A heterojunction bipolar transistor comprising: a base layer comprising a p-type semiconductor; a mesa of an emitter layer comprising an n-type semiconductor having the larger energy band gap than said base layer formed on said base layer; an epitaxially formed surface protective film layer of p-type semi-conductor which shows the higher potentiai of energy conduction band than said base on the external base layer outside the junction part between said emitter mesa and said base layer; and a base electrode formed on said surface protective film.
Claim 2
Dependent Claim
86 words
A heterojunction bipolar transistor comprising: a base layer comprising a p-type semiconductor; a mesa of an emitter layer comprising an n-type semiconductor having the larger energy band gap than said base layer formed on said base layer; an epitaxially formed surface protective film layer of p-type semi-conductor which shows the higher potentiai of energy conduction band than said base on the external base layer outside the junction part between said emitter mesa and said base layer; and a base electrode formed on said surface protective film.
Claim 3
Dependent Claim
47 words
A heterojunction bipolar transistor according to Claim 1, wherein the n-type emitter material is Al X Ga 1-X As, the p-type base material is Al Y Ga 1-Y As (Y <X), and the p-type surface protective film materiai is Al Z Ga 1-Z As (Z > Y).
Claim 4
Dependent Claim
57 words
A heterojunction bipolar transistor according to Claim 1, which further comprises: an emitter electrode covering the upper surface of the emitter mesa in an umbrella shape; and a base electrode which is in contact with the projection part of said emitter electrode to the p-type surface protective film and is formd on said p-type surface protective film.
Claim 5
Dependent Claim
112 words
A heterojunction bipolar transistor comprising: a base layer comprising a p-type semiconductor; a mesa of an emitter layer comprising an n-type semiconductor having the larger energy band gap than said base layer formed on said base layer; an epitaxially formed surface protective film of p-type semiconductor which shows the higher potential of energy conduction band than said base on the external base layer outside the junction part between said emitter mesa and said base layer; a base contact layer comprising a p-tpe semiconductor which shows the lower contact resistance with the base electrode and which is epitaxially formed on said surface protective film; and a base electrode on said base contact layer.
Claim 6
Dependent Claim
112 words
A heterojunction bipolar transistor comprising: a base layer comprising a p-type semiconductor; a mesa of an emitter layer comprising an n-type semiconductor having the larger energy band gap than said base layer formed on said base layer; an epitaxially formed surface protective film of p-type semiconductor which shows the higher potential of energy conduction band than said base on the external base layer outside the junction part between said emitter mesa and said base layer; a base contact layer comprising a p-tpe semiconductor which shows the lower contact resistance with the base electrode and which is epitaxially formed on said surface protective film; and a base electrode on said base contact layer.
Claim 7
Dependent Claim
52 words
A heterojunction bipolar transistor according to Claim 4, wherein the n-type emitter is Al X Ga 1-X As, the p-type base is Al Y Ga 1-Y As (Y <X), the p-type surface protective film layer is Al Z Ga 1-Z As (Z > Y), and the p-type base contact layer is GaAs.
Claim 8
Dependent Claim
66 words
A heterojunction bipolar transistor according to Claim 4, which further comprises: an emitter electrode covering the upper surface of the emitter mesa in an umbrella shape; and a base electrode formed on the base contact layer comprising a p-type semiconductor which shows the smaller contact resistance with the base electrode in contact with the projection part of said emitter electrode to said p-type surface protective film.
Claim 9
Dependent Claim
52 words
A heterojunction bipolar transistor according to Claim 6, wherein the n-type emitter is Al X Ga 1-X As, the p-type base is Al Y Ga 1-Y As (Y <X), the p- type surface protective film is Al Z Ga 1-Z As (Z > Y), and the base contact layer is p-type GaAs.
Claim 10
Dependent Claim
116 words
A heterojunction bipolar transistor comprising: a base layer comprising a p-type semiconductor; a mesa of an emitter layer comprising an n-type semiconductor having the larger energy band gap than said base layer formed on said base layer; an emitter electrode covering said emitter mesa in an umbrella shape; and a base electrode formed on the base layer in contact with the projection part of said emitter electrode to the base layer; and a surface protective film comprising a semiconductor material which shows the higher potential of energy conduction band than said base on the surface of the base layer lying between the junction part between said emitter mesa and said base layer and said base electrode.
Claim 11
Dependent Claim
116 words
A heterojunction bipolar transistor comprising: a base layer comprising a p-type semiconductor; a mesa of an emitter layer comprising an n-type semiconductor having the larger energy band gap than said base layer formed on said base layer; an emitter electrode covering said emitter mesa in an umbrella shape; and a base electrode formed on the base layer in contact with the projection part of said emitter electrode to the base layer; and a surface protective film comprising a semiconductor material which shows the higher potential of energy conduction band than said base on the surface of the base layer lying between the junction part between said emitter mesa and said base layer and said base electrode.
Claim 12
Dependent Claim
43 words
a heterojunction bipolar transistor according to Claim 8, wherein the n-type emitter is Al X Ga 1-X As, the p-type base is Al Y Ga 1-Y As (Y< X), and the surface protective film is Al Z Ga 1-Z As (Z > Y).
Claim 13
Independent Claim
145 words
A method of producing a heterojunction bipolar transistor, comprising the steps of: forming an emitter mask on the portion to be an emitter of a multi-layer structure material in which an n-type semiconductor layer for forming a collector layer, a p-type semiconductor layer for forming a base layer, and an n-type wide energy band gap semiconductor layer for forming an emitter layer are epitaxially formed in this order on a substrate material, carrying out etching by the use of said mask to form an emitter mesa and to expose said base layer; epitaxially forming as a surface protective film layer a p-type semiconductor layer having the higher potentiai of the energy conduction band than the base layer on the external base layer outside the junction part between the emitter mesa and the base layer; and forming a base electrode on said surface protective film layer.
Claim 14
Independent Claim
145 words
A method of producing a heterojunction bipolar transistor, comprising the steps of: forming an emitter mask on the portion to be an emitter of a multi-layer structure material in which an n-type semiconductor layer for forming a collector layer, a p-type semiconductor layer for forming a base layer, and an n-type wide energy band gap semiconductor layer for forming an emitter layer are epitaxially formed in this order on a substrate material, carrying out etching by the use of said mask to form an emitter mesa and to expose said base layer; epitaxially forming as a surface protective film layer a p-type semiconductor layer having the higher potentiai of the energy conduction band than the base layer on the external base layer outside the junction part between the emitter mesa and the base layer; and forming a base electrode on said surface protective film layer.
Claim 15
Dependent Claim
47 words
A method according to Claim 10, wherein n-type Al X Ga 1-X As is used as an emitter layer, p-type Al Y Ga 1-Y As (Y <X) as a base layer, and p-type Al Z Ga 1-Z As (Z > Y) as a surface protective film layer.
Claim 16
Dependent Claim
118 words
A method according to Claim 10, comprising the steps of: epitaxially forming a surface protective fiim layer comprising a p-type semiconductor; followed by coating the surface with photoresist to flatten, and then exposing the surface of the top part of said emitter mask by dry etching, selectively removing said emitter mask to form an opening of said photoresist with exposure of the surface of the top part of the emitter mesa, and forming an emitter electrode on said part; and vapor depositing base electrode metals by using said emitter electrode as a mask and forming said base electrode on said surface protective film in contact with the projection part of said emitter electrode to said surface protective film.
Claim 17
Dependent Claim
110 words
A method according to Claim 10, comprising the steps of: epitaxially forming a surface protective film layer comprising a p-type semiconductor; followed by vapor depositing base electrode metals by using said emitter mask as a mask on said surface protective film in contact with the projection part of said emitter mask to the surface protective film; and coating the surface with photoresist to flatten, exposing the surface of the top part of said emitter mask by dry etching removing said emitter mask to form an opening of said photoresist with exposure of the surface of the top part of the emitter mesa, and forming an emitter electrode on said part.
Claim 18
Independent Claim
171 words
A method of producing a heterojunction bipolar transistor, comprising the steps of: forming an emitter mask on the portion to be an emitter of a multi-layer structure material in which an n-type semiconductor layer for forming a collector layer, a p-type semiconductor layer for forming a base layer, and an n-type wide energy band gap semiconductor layer for forming an emitter layer are epitaxially formed in this order on a substrate material, carrying out etching by the use of said emitter mask to form an emitter mesa and exposing said base layer; epitaxially forming as a surface protective film layer a p-type semiconductor layer having the higher potential of the energy conduction band than the base layer on the external base layer outside the junction part between the emitter mesa and the base layer; epitaxially forming as a base contact layer a p-type semiconductor layer which shows the smaller contact resistance with the base electrode on said surface protective film layer; and forming a base electrode on said base contact layer.
Claim 19
Independent Claim
171 words
A method of producing a heterojunction bipolar transistor, comprising the steps of: forming an emitter mask on the portion to be an emitter of a multi-layer structure material in which an n-type semiconductor layer for forming a collector layer, a p-type semiconductor layer for forming a base layer, and an n-type wide energy band gap semiconductor layer for forming an emitter layer are epitaxially formed in this order on a substrate material, carrying out etching by the use of said emitter mask to form an emitter mesa and exposing said base layer; epitaxially forming as a surface protective film layer a p-type semiconductor layer having the higher potential of the energy conduction band than the base layer on the external base layer outside the junction part between the emitter mesa and the base layer; epitaxially forming as a base contact layer a p-type semiconductor layer which shows the smaller contact resistance with the base electrode on said surface protective film layer; and forming a base electrode on said base contact layer.
Claim 20
Dependent Claim
54 words
A method according to Claim 14, wherein n-type Al X Ga 1-X As is used as an emitter layer, p-type Al Y Ga 1-Y As (Y <X) as a base layer, p-type Al Z Ga 1-Z As (Z > Y) as a surface protective film layer, and p-type GaAs as a base contact layer.
Claim 21
Dependent Claim
131 words
A method according to Claim 14, comprising the steps of: epitaxially forming as a base contact layer a p-type semiconductor layer which shows the smaller contact resistance with the base electrode; followed by coating the surface with photoresist to flatten, and then exposing the surface of the top part of said emitter mask by dry etching, removing said emitter mask to form an opening of said photoresist with exposure of the surface of the top part of the emitter mesa, and forming an emitter electrode on said part by metal vapor deposition; and vapor depositing base electrode metals by using said emitter electrode as a mask and forming the base electrode on said base contact layer in contact with the projection part of said emitter electrode to said base contact layer.
Claim 22
Independent Claim
240 words
A method of producing a heterojunction bipolar transistor, comprising the steps of: forming an emitter mask on the portion to be an emitter of a multi-layer structure material in which an n-type semiconductor layer for forming a collector layer, a p-type semiconductor layer for forming a base layer, and an n-type wide energy band gap semiconductor layer for forming an emitter layer are epitaxially formed in this order on a substrate material, carrying out etching by the use of said emitter mask to form an emitter mesa and exposing said base layer; forming as a surface protective film layer a semiconductor layer having the higher potential of the energy conduction band than the base layer on the base layer outside the junction part between the emitter mesa and the base layer; coating the surface with photoresist to flatten, exposing the surface of the top part of the emitter mask by dry etching, removing said emitter mask to form an opening part of said photoresist, and forming an emitter electrode on said part; removing said surface protective film layer other than the projection part of said emitter electrode to said surface protective film by dry etching by using said emitter electrode as a mask; and forming a base electrode on the base layer in contact with the projection part of said emitter electrode to the base layer by vapor depositing base electrode metals by using said emitter electrode as a mask.
Claim 23
Independent Claim
240 words
A method of producing a heterojunction bipolar transistor, comprising the steps of: forming an emitter mask on the portion to be an emitter of a multi-layer structure material in which an n-type semiconductor layer for forming a collector layer, a p-type semiconductor layer for forming a base layer, and an n-type wide energy band gap semiconductor layer for forming an emitter layer are epitaxially formed in this order on a substrate material, carrying out etching by the use of said emitter mask to form an emitter mesa and exposing said base layer; forming as a surface protective film layer a semiconductor layer having the higher potential of the energy conduction band than the base layer on the base layer outside the junction part between the emitter mesa and the base layer; coating the surface with photoresist to flatten, exposing the surface of the top part of the emitter mask by dry etching, removing said emitter mask to form an opening part of said photoresist, and forming an emitter electrode on said part; removing said surface protective film layer other than the projection part of said emitter electrode to said surface protective film by dry etching by using said emitter electrode as a mask; and forming a base electrode on the base layer in contact with the projection part of said emitter electrode to the base layer by vapor depositing base electrode metals by using said emitter electrode as a mask.
Claim 24
Dependent Claim
46 words
A method according to Claim 17, wherein Al X Ga 1-X As is used as an n-type emitter, Al Y Ga 1-Y As (Y < X) as a p-type base , and Al Z Ga 1-Z As (Z > Y) as a surface protective film .
References Cited (Backward Citations)
JPS61193294A
Cited
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