Browse Prior Art Database

Multiple Base Isolation in a Common Collector Bed

IP.com Disclosure Number: IPCOM000041285D
Original Publication Date: 1984-Jan-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 2 page(s) / 60K

Publishing Venue

IBM

Related People

Hengst, HJ: AUTHOR [+3]

Abstract

A technique for high density integration of common collector devices using an oxide trench isolation is disclosed. A multi-element device having a common collector bed, as shown in Fig. 1, includes a base diffusion 10, a cross-hatched oxide isolation trench 12, emitter diffusions 14 and a collector reach-through diffusion 16. The oxide isolation trench 12 is shown extending completely around the area of interest and across the base diffusion 10. The trench 12 extends through the base diffusion 10 down to the collector (not shown) in the region 18, thereby forming two electrically isolated portions of the original base diffusion 10. The base metallization 20, is also shown. In addition, other circuit elements 22 may also be formed within the area defined by the oxide isolation trench 12. In Fig.

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Multiple Base Isolation in a Common Collector Bed

A technique for high density integration of common collector devices using an oxide trench isolation is disclosed. A multi-element device having a common collector bed, as shown in Fig. 1, includes a base diffusion 10, a cross-hatched oxide isolation trench 12, emitter diffusions 14 and a collector reach-through diffusion 16. The oxide isolation trench 12 is shown extending completely around the area of interest and across the base diffusion 10. The trench 12 extends through the base diffusion 10 down to the collector (not shown) in the region 18, thereby forming two electrically isolated portions of the original base diffusion 10. The base metallization 20, is also shown. In addition, other circuit elements 22 may also be formed within the area defined by the oxide isolation trench 12. In Fig. 2, a circuit formed by the layout of Fig. 1, with the circuit elements 26 being Schottky barrier diodes, is shown. The density improvement over the prior art of individual base diffusions in a common collector bed is approximately 22%. Using a trench to physically isolate the base diffusion, as opposed to electrical isolation, improves AC cross-coupling by a factor of two. Other advantages, in addition to density and AC cross-coupling, are reduced collector-base capacitance and lower leakage.

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