EP0504875A2
Expired / Lapsed
EP
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Bipolar transistor and method of fabricating the same
Assignee: Hitachi Ltd
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Filing: 1992-03-19
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Granted: —
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Expires: 2012-03-19
Abstract
Abstract To eliminate misfit dislocation occurring in a hetero-interface and to provide a bipolar transistor capable of a high speed operation, the bipolar transistor is configured such that the energy band gap is progressively narrowing from part of an emitter layer (11) towards part of a collector layer (13) through a base layer (12).
Inventors
- 👤 Kenichi Shoji
- 👤 Akira Fukami
- 👤 Takahiro Nagano
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-31 08:25
CPC Classifications
H; H10; H10D; H10D10/00; H10D10/01; H10D10/021; H10D10/80; H10D10/821; H10D10/891; H10D62/00; H10D62/80; H10D62/83; H10D62/832; H10D62/834
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
132 words
A bipolar transistor including a collector region (13, 23) formed of a semiconductor having one conductivity type, a base region (12, 22) formed of a semiconductor having the other conductivity type and a base-collector junction formed between the base region and said collector region (13, 23) in the proximity of said collector region (13, 23), and an emitter region (11, 21) formed of a semiconductor having one conductivity type and an emitter-base junction formed between said emitter region and said base region (12, 22) in the proximity of said base region (12, 22), wherein an energy band gap of said emitter region (11, 21) and said base region (12, 22) near said base-emitter junction is narrowing along a direction of from said emitter region (11, 21) to said base region (12, 22).
Claim 2
Dependent Claim
136 words
A bipolar transistor including a collector region (13, 23) formed of silicon having one conductivity type, a base region (12, 22) formed of silicon having the other conductivity type and a collector-base junction formed between the base region and said collector region (13, 23) in the proximity of said collector region (13, 23), and an emitter region (11, 21) formed of silicon of one conductivity type and a base-emitter junction formed between the emitter region and said base region (12, 22) in the proximity of said base region (12, 22), wherein germanium exists in mixture in said emitter region (11, 21) and in said base region (12, 22) near said base-emitter junction, and the concentration of the germanium is increasing along a direction of from said emitter region (11, 21) to said base region (12, 22).
Claim 3
Dependent Claim
129 words
A bipolar transistor including a collector region (13, 23) of one conductivity type, a base region (12, 22) of the other conductivity type and a collector-base junction formed between said base region and said collector region (13, 23) in the proximity of said collector region (13, 23), and an emitter region (11, 21) of one conductivity type and a base-emitter junction formed between the emitter region and said base region (12, 22) in the proximity of said base region (12, 22), wherein said emitter region (11, 21) and said base region (12, 22) are formed of a silicon-germanium alloy, and the concentration of germanium is increasing in the proximity of said base-emitter junction along a direction of from said emitter region (11, 21) to said base region (12, 22).
Claim 4
Dependent Claim
40 words
A bipolar transistor according to Claim 3, wherein at least one element having a smaller lattice constant than silicon is contained in an area of from the surface of said emitter region (11, 21) to said base region (12, 22).
Claim 5
Dependent Claim
172 words
A bipolar transistor comprising a collector region (13, 23) having one conductivity type, a base region (12, 22) having the other conductivity type and a collector-base junction formed between said base region and said collector region (13, 23) in the proximity of said collector region (13, 23), and an emitter region (11, 21) having one conductivity type and a base-emitter junction formed between said emitter region and said base region (12, 22) in such a manner as to extend from the surface of said base region (12, 22) into said emitter region (11, 21), wherein a portion of said emitter region (11, 21) other than its peripheral portion and a portion of said base region (12, 22) adjacent thereto are formed of a silicon-germanium alloy, the rest of the portions of said emitter region (11, 21) and said base region (12, 22) are formed of silicon, and a germanium concentration in said alloy portion is increasing in a direction extending from said emitter region (11, 21) to said base region (12, 22).
Claim 6
Dependent Claim
33 words
A bipolar transistor according to Claim 5, wherein the portion of said collector region (13, 23) adjacent to said alloy portion of said base region (12, 22) is formed of a silicon-germanium alloy.
Claim 7
Dependent Claim
42 words
A bipolar transistor according to Claim 5 or Claim 6, wherein at least one element having a smaller lattice constant than silicon is contained in an area of from the surface of said emitter region (11, 21) said base region (12, 22).
Claim 8
Dependent Claim
33 words
A bipolar transistor according to Claim 7, wherein said element having a smaller lattice constant than silicon is at least one element selected from the group essentially consisting of carbon, boron and nitrogen.
Claim 9
Dependent Claim
153 words
A bipolar transistor comprising a collector region (13, 23) formed of silicon having one conductivity type, a base region (12, 22) formed of silicon having the other conductivity type and a collector-base junction formed between said base region and said collector region (13, 23) in the proximity of said collector region (13, 23), and an emitter region (11, 21) formed of silicon having one conductivity type and a base-emitter junction formed between said emitter region and said base region (12, 22) in such a manner as to extend from the surface of said base region (12, 22) into the inside, wherein germanium exists in mixture in said emitter region (11, 21) and in said base region (12, 22) near the portion spaced apart from an exposed end of said base-emitter junction, and a germanium concentration is increasing in a direction of from said emitter region (11, 21) towards said base region (12, 22).
Claim 10
Dependent Claim
40 words
A bipolar transistor according to Claim 9, wherein at least one element having a smaller lattice constant than silicon is contained in an area of from the surface of said emitter region (11, 21) into said base region (12, 22).
Claim 11
Independent Claim
211 words
A method of fabricating a bipolar transistor comprising the steps of: preparing a silicon substrate (20) having a first region (13, 23) of one conductivity type, a second region (12, 22) having the other conductivity type and a lower impurity concentration than said first region and a third region (11, 21) having the other conductivity type and a higher impurity concentration than said second region, in order named from the side of one of main planes of said substrate (20); forming a mask having a first window on said one main plane of said silicon substrate (20), and injecting germanium into at least said first region from said first window of said mask so as to form a silicon - germanium alloy region (24) the germanium concentration of which progressively increases away from said one plane inside said first region (13, 23); and widening said first window on said one main plane of said silicon substrate (20) into a second window greater than said first window, and then injecting an impurity exhibiting the first conductivity type from said second window into said first region so that a p-n junction defined with said first region forms a fourth region of one conductivity type positioned at said silicon - germanium alloy region (24).
Claim 12
Dependent Claim
43 words
A method of fabricating a bipolar transistor according to Claim 11, wherein said silicon - germanium alloy region (24) extends from the surface of said first region (13, 23) into said second region (12, 22) in said mask forming and germanium injecting step.
Claim 13
Dependent Claim
45 words
A method of fabricating a bipolar transistor according to Claim 11 or Claim 12, wherein at least an element having a smaller lattice constant than that of silicon is injected from said first window of said mask into at least said first region (13, 23).
Claim 14
Independent Claim
200 words
A method of fabricating a bipolar transistor comprising the steps of: preparing a silicon substrate (20) having a first region (13, 23) of one conductivity type, a second region (12, 22) having the other conductivity type and a lower impurity concentration than said first region and a third region (11, 21) having the other conductivity type and a higher impurity concentration than said second region, in order named from the side of one of main planes of said silicon substrate (20); forming a mask having a window on said one plane of said silicon substrate (20), and injecting germanium into at least said first region (13, 23) from said window of said mask so as to form a silicon - germanium alloy region (24) the germanium concentration of which is increasing away from said one main plane inside said first region (13, 23); and injecting an impurity exhibiting one conductivity type from said window of said mask on said one main plane of said silicon substrate (20) into said first region (13, 23) so that a p-n junction defined with said first region forms a fourth region of one conductivity type positioned at said silicon - germanium alloy region (24).
Claim 15
Dependent Claim
43 words
A method of fabricating a bipolar transistor according to Claim 14, wherein said silicon - germanium alloy region (24) extends from the surface of said first region (13, 23) into said second region (12, 22) in said mask forming and germanium injecting step.
Claim 16
Dependent Claim
42 words
A method of fabricating a bipolar transistor according to Claim 14 or Claim 15, wherein an element having a smaller lattice constant than that of silicon is injected from said window of said mask into at least said first region (13, 23).
References Cited (Backward Citations)
No citation records indexed.
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