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Browse Prior Art Database

Surrounding-Collector Trench Bipolar Transistor With Minimized Base Resistance

IP.com Disclosure Number: IPCOM000121133D
Original Publication Date: 1991-Jul-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 3 page(s) / 92K

Publishing Venue

IBM

Related People

Wu, BS: AUTHOR

Abstract

Disclosed is a bipolar transistor built inside a trench to obtain a large effective emitter area without increasing the transistor size.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 60% of the total text.

Surrounding-Collector Trench Bipolar Transistor With Minimized Base
Resistance

      Disclosed is a bipolar transistor built inside a trench
to obtain a large effective emitter area without increasing the
transistor size.

      In the conventional bipolar circuit design, a typical approach
to increase conducting current is to utilize a larger emitter area
which ends up with a bigger transistor size and larger parasitic
capacitance.  By embedding the transistor into a trench (Fig. 1), the
structure disclosed here can conduct much more current than planar
structures (for the same transistor size) by simply increasing trench
depth and, meanwhile, maintain constant extrinsic base/collector
capacitance.  The surrounding collector of the structure disclosed
can reduce the collector resistance as well as transistor size
(because the isolation oxide between the base and collector regions
needed in conventional structure becomes obsolete here).  Therefore,
this trench bipolar structure is naturally suitable for power and
driver circuit applications.  By properly designing the doping
profiles (for example, reducing the current density at maximal
cut-off frequency), it can be useful in contemporary switching
circuit applications, too. As shown in Figs. 1 and 2, the purpose of
patterning a silicided base poly all around the edge of shallow
trench is to minimize the base resistance.

      The detailed processes are illustrated as follows:
      1.   Start with p...