Fishing – trapping – and vermin destroying
Patent
1991-01-14
1993-02-16
Chaudhuri, Olik
Fishing, trapping, and vermin destroying
437 32, 437 90, 437228, H01L 21265, H01L 2120
Patent
active
051871084
ABSTRACT:
A method of manufacturing a bipolar transistor includes selectively removing portions of a semiconductor layer on a semiconductor substrate photolithographically to form an isolation trench and first and second mesa regions surrounded and separated by the trench, and forming a first insulation film on inner walls of the trench. Then, a second insulation film is formed on the upper surfaces of the mesa regions, and a first polycrystalline silicon layer is formed on the first insulation film. Polycrystalline silicon is selectively grown from the first polycrystalline silicon layer onto the second insulation film to form a second polycrystalline silicon layer while leaving exposed a portion of the second insulation film. Then, a part of second insulation film is removed to expose the upper surface of the first mesa region so as to leave a gap between the exposed upper surface and the second polycrystalline silicon layer, while leaving the upper surface of the second mesa region covered by the remaining second insulation film. Polycrystalline silicon is deposited in the gap so as to connect the second polycrystalline silicon layer to the exposed upper surface. A third insulating film is formed covering upper and side surfaces of the second polycrystalline silicon layer. The exposed portion of the second insulating film on the second mesa region is then removed to expose a portion of the upper surface of the second mesa region. A base and an emitter are formed in the first mesa region.
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Chaudhuri Olik
OKI Electric Industry Co., Ltd.
Trinh Loc Q.
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