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US 7,001,820 B1Granted
Heterojunction bipolar transistor and method for fabricating the same
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorsKenichi Miyajima, Akiyoshi Tamura, Keiichi Murayama
Life of this patent
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Abstract
The following layers are successively formed on a heavily-doped n-type first subcollector layer: a heavily-doped n-type second subcollector layer made of a material having a small band gap; an i-type or a lightly-doped n-type collector layer; a heavily-doped p-type base layer; an n-type emitter layer made of a material having a large band gap; a heavily-doped n-type emitter cap layer; and a heavily-doped n-type emitter contact layer made of a material having a small band gap. Alloying reaction layers are formed under an emitter electrode, a base electrode and a collector electrode.
Claims10
A method for fabricating a heterojunction bipolar transistor, comprising the steps of:
- successively forming, on the principal surface of a semi-insulating substrate, a heavily-doped n-type first subcollector layer, a heavily-doped n-type second subcollector layer made of a material having a smaller band gap than the first subcollector layer, an i-type or a lightly-doped n-type collector-layer-forming film, a heavily-doped p-type base-layer-forming film, an n-type emitter-layer-forming film made of a material having a larger band gap than the base-layer-forming film, a heavily-doped n-type emitter-cap-layer-forming film, and a heavily-doped n-type emitter-contact-layer-forming film made of a material having a smaller band gap than the emitter-cap-layer-forming film;
- patterning the emitter-contact-layer-forming film and the emitter-cap-layer-forming film to expose a base electrode formation region of the emitter-layer-forming film, thereby forming an emitter contact layer and an emitter cap layer;
- patterning the emitter-layer-forming film, the base-layer-forming film and the collector-layer-forming film to expose a collector electrode formation region of the second subcollector layer, thereby forming an emitter layer, a base layer and a collector layer;
- forming an emitter electrode made of one or a plurality of conductive layers on an emitter electrode formation region of the emitter contact layer;
- forming a base electrode made of one or a plurality of conductive layers on the base electrode formation region of the emitter layer;
- forming a collector electrode made of one or a plurality of conductive layers on the collector electrode formation region of the second subcollector layer;
- and
- forming, by heat treatment, a first alloying reaction layer, a second alloying reaction layer and a third alloying reaction layer in a part of the emitter contact layer located under the emitter electrode, a part of the emitter layer located under the base electrode and a part of the second subcollector layer located under the collector electrode, respectively.
5 more elements
A method for fabricating a heterojunction bipolar transistor, said method comprising the steps of:
- successively forming, on the principal surface of a semi-insulating substrate, a heavily-doped n-type first subcollector layer, a heavily-doped n-type second subcollector layer made of a material having a smaller band gap than the first subcollector layer, an i-type or a lightly-doped n-type collector-layer-forming film, a heavily-doped p-type base-layer-forming film, an n-type emitter-layer-forming film made of a material having a larger band gap than the base-layer-forming film, a heavily-doped n-type emitter-cap-layer-forming film, and a heavily-doped n-type emitter-contact-layer-forming film made of a material having a smaller band gap than the emitter-cap-layer-forming film;
- patterning the emitter-contact-layer-forming film, the emitter-cap-layer-forming film and the emitter-layer-forming film to expose a base electrode formation region of the base-layer-forming film, thereby forming an emitter contact layer, an emitter cap layer and an emitter layer;
- patterning the base-layer-forming film and the collector-layer-forming film to expose a collector electrode formation region of the second subcollector layer, thereby forming a base layer and a collector layer;
- forming an emitter electrode made of one or a plurality of conductive layers on an emitter electrode formation region of the emitter contact layer;
- forming a base electrode made of one or a plurality of conductive layers on the base electrode formation region of the base layer;
- forming a collector electrode made of one or a plurality of conductive layers on the collector electrode formation region of the second subcollector layer;
- and
- forming, by heat treatment, a first alloying reaction layer, a second alloying reaction layer and a third alloying reaction layer in a part of the emitter contact layer located under the emitter electrode, a part of the base layer located under the base electrode and a part of the second subcollector layer located under the collector electrode, respectively.
5 more elements
Dependencies are inferred from the claim text.