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Patent US5670801A successfully refreshed from Google Patents.
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US5670801A Expired / Lapsed US ⏱️ 0.0 years remaining

Heterojunction bipolar transistor

Assignee: Mitsubishi Electric Corp
•
Filing: 1996-01-03
•
Granted: 1997-09-23
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Expires: 2016-01-03
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Abstract

Abstract A method of fabricating a semiconductor device includes producing a collector layer, a base layer, and an emitter layer on a semiconductor substrate; producing a dummy emitter electrode on a region of the emitter layer; forming a first resist except where the dummy emitter electrode is present; completely removing the dummy emitter electrode to expose the surface of the emitter layer; depositing an emitter electrode material on the first resist and the emitter layer that is exposed by the removal of the dummy emitter electrode; forming a mask on a region of the emitter electrode material film where an emitter electrode is later produced; and etching the emitter electrode material film using the mask; and removing the first resist, thereby producing an emitter electrode layer, a peripheral side part extending upward from the bottom part, and an upper fringe part protruding outward from the peripheral side part perpendicular to the peripheral side part. A minute emitter electrode is produced without employing vacuum evaporation and lift-off techniques that can cause burrs on the emitter electrode. Since a refractory metal can be employed as the emitter electrode material, a highly-reliable emitter electrode is produced with high stability.

Inventors

  • 👤 Hirofumi Nakano

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-28 23:48
CPC Classifications
H; H10; H10D; H10D10/00; H10D10/01; H10D10/021; H10D10/80; H10D10/821; H10D64/00; H10D64/60; H10D64/62; H10W; H10W20/00; H10W20/40; H10W20/41; H10W20/43; H10W20/432; H10W20/482; H10W20/483; H10D62/00; H10D62/80; H10D62/85

Claims Analysis

Total Claims: 9
Claim 1
Independent Claim 126 words
A semiconductor device comprising: a laminated semiconductor structure comprising a collector layer, a base layer, and an emitter layer disposed on a semiconductor substrate; an emitter electrode disposed on the emitter layer and comprising a planar bottom part that contacts the emitter layer, a peripheral side part extending upward from the bottom part, and an upper fringe part protruding outward from the peripheral side part in a direction perpendicular to the peripheral side part, wherein the planar bottom part, the peripheral side part, the upper fringe part comprise a conductive material united in one body; base electrodes contacting the base layer at opposite sides of the emitter electrode and self-aligned with the planar bottom part of the emitter electrode; and collector electrodes contacting the collector layer.
Claim 2
Dependent Claim 126 words
A semiconductor device comprising: a laminated semiconductor structure comprising a collector layer, a base layer, and an emitter layer disposed on a semiconductor substrate; an emitter electrode disposed on the emitter layer and comprising a planar bottom part that contacts the emitter layer, a peripheral side part extending upward from the bottom part, and an upper fringe part protruding outward from the peripheral side part in a direction perpendicular to the peripheral side part, wherein the planar bottom part, the peripheral side part, the upper fringe part comprise a conductive material united in one body; base electrodes contacting the base layer at opposite sides of the emitter electrode and self-aligned with the planar bottom part of the emitter electrode; and collector electrodes contacting the collector layer.
Claim 3
Dependent Claim 14 words
The semiconductor device of claim 1 wherein the emitter electrode comprises a refractory metal.
Claim 4
Dependent Claim 27 words
The semiconductor device of claim 1 further including an air-bridge wiring connected to the emitter electrode inside the upper fringe part and including the planar bottom part.
Claim 5
Dependent Claim 28 words
The semiconductor device of claim 1 further including an air-bridge wiring comprising the same material as the emitter electrode and united with the emitter electrode in one body.
Claim 6
Dependent Claim 30 words
The semiconductor device of claim 4 wherein the united emitter electrode and air-bridge wiring comprises a lower layer of a refractory metal and an upper layer of a another metal.
Claim 7
Dependent Claim 32 words
The semiconductor device of claim 1 wherein the emitter layer protrudes upward from a region of the base layer and the planar bottom part of the emitter electrode covers the emitter layer.
Claim 8
Dependent Claim 21 words
The semiconductor device of claim 6 wherein the emitter layer is self-aligned with the planar bottom part of the emitter electrode.
Claim 9
Dependent Claim 63 words
The semiconductor device of claim 6 wherein the emitter layer comprises a lower part disposed on the base layer and an upper part smaller than the lower part and disposed on and within the lower part, and a difference in level is produced at a boundary between the upper part and the lower part on the peripheral side surface of the emitter layer.

References Cited (Backward Citations)

US4611388A Cited
JPH05198586A Cited
US5268315A Cited
US5436497A Cited
US5411632A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 2000-09-22 2001-03-24 2001-09-23 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 2004-09-22 2005-03-24 2005-09-23 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 2008-09-22 2009-03-24 2009-09-23 $7700.00 Window Closed / Lapsed

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