Fishing – trapping – and vermin destroying
Patent
1994-03-31
1994-12-27
Hearn, Brian E.
Fishing, trapping, and vermin destroying
437162, 437164, 437909, 148DIG11, 148DIG124, H01L 21265
Patent
active
053765648
ABSTRACT:
On manufacturing a bipolar transistor, a field silicon oxide layer (7) having a beaked edge portion (bird's beak portion) is formed by a heat oxidation process using a silicon nitride film (5) as an oxidation mask. In this event, an edge of the nitride film is boosted up as a boosted portion by an upper part of the beaked edge portion. The upper part of the beaked edge portion is etched to form an undercut portion under the boosted portion. The undercut portion is filled with a base leading polysilicon (10) having impurities. On forming an insulator film (11) on the base leading polysilicon in a heated atmosphere, an outer base region (14) is formed in an epitaxial layer (3) by making the impurities diffuse from the base leading polysilicon towards the epitaxial layer in the heated atmosphere. Between the epitaxial layer and an edge portion of a nonboosted portion of the nitride film, a silicate glass (12) containing impurities is buried. The silicate glass (12) containing impurities is buried under the nitride film through an opening to form an inner base region (13) on the inside of the outer base region by diffusion of the impurities. The silicate glass is removed except an edge portion thereof which forms a link base region (15) by diffusion of the impurities. A hole of an insulator spacer (16) formed in the opening is filled with an emitter leading polysilicon (17) having impurities used in forming an emitter region (19) by diffusion.
REFERENCES:
patent: 5089430 (1992-02-01), Owada et al.
patent: 5162244 (1992-11-01), Lim
patent: 5227317 (1993-07-01), Owada et al.
By K. Ueno et al., "A Sub-40 PS ECL Circuit at a Switching Current of 1.28 MA", IEEE, 1987, pp. 371-374.
Hearn Brian E.
NEC Corporation
Nguyen Tuan
LandOfFree
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