Fishing – trapping – and vermin destroying
Patent
1987-02-24
1988-03-15
Hearn, Brian E.
Fishing, trapping, and vermin destroying
437944, 437238, 437203, 437 24, 437 22, 437133, 357 34, 357 16, 156656, H01L 21265
Patent
active
047313404
ABSTRACT:
A dual lift-off technique is used to provide self-alignment of the emitter area, the emitter contact, and the base contact of a heterojunction, bipolar transistor. A photoresist pattern which defines an emitter adjacent a base contact is formed on a suitable heterojunction bipolar semiconductor wafer. A base contact is formed by etching through the first semiconductor to the heterojunction and depositing metal on the second semiconductor. Dielectric is then deposited on the base contact. The photoresist is then lifted off with its dual covering of dielectric and metal. The emitter contact metal can then be deposited without requiring critical alignment because the base contact is covered with dielectric.
REFERENCES:
patent: 4090006 (1978-05-01), Havas et al.
patent: 4380774 (1983-04-01), Yoder
patent: 4448800 (1984-05-01), Ehara et al.
Kroemer, H. "Heterostructure Bipolar . . . " Proceedings of the IEEE vol. 70, #1, Jan. 1982, pp. 13-25.
Asbeck Peter M.
Chang Mau-Chung F.
Hamann H. Fredrick
Hearn Brian E.
Malin Craig O.
McAndrews Kevin
Rockwell International Corporation
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