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Self-Aligned Bipolar Semiconductor Devices With Self-Aligned Silicide On Poly-Silicon

IP.com Disclosure Number: IPCOM000102783D
Original Publication Date: 1990-Jan-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 53K

Publishing Venue

IBM

Related People

Chen, TC: AUTHOR [+3]

Abstract

Described is a double-polysilicon self-aligned bipolar semiconductor device with self-aligned silicide on both the emitter polysilicon and on the extrinsic-base polysilicon. The silicide on the extrinsic-base polysilicon reduces the extrinsic-base poly sheet resistance, allowing the double-poly self-aligned bipolar device structure to be scaled down to the sub-0.5mm dimensional range.

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Self-Aligned Bipolar Semiconductor Devices With Self-Aligned Silicide On Poly-Silicon

      Described is a double-polysilicon self-aligned bipolar
semiconductor device with self-aligned silicide on both the emitter
polysilicon and on the extrinsic-base polysilicon. The silicide on
the extrinsic-base polysilicon reduces the extrinsic-base poly sheet
resistance, allowing the double-poly self-aligned bipolar device
structure to be scaled down to the sub-0.5mm dimensional range.

      Fig. 1 illustrates the double-poly self-aligned bipolar device
commonly used in the industry.  In scaling down this device, the
oxide/p+ poly stack thickness is reduced in order to minimize the
base implant shadowing effect and to facilitate the etching of the
smaller emitter opening.  In reducing the p+ poly thickness, concern
is always present in the increase in its sheet resistance.

      The concept described herein proposes to form a thin silicide
layer, such as TiSi2, on the p+ polysilicon region self-aligned to
the n+ polysilicon emitter edge, as shown in Fig. 2.  The silicide is
also formed on the n+ polysilicon emitter layer as well as on the n+
reach through region.

      The self-aligned silicide on the p+ poly can be achieved by
simply etching the oxide on the p+ poly following n+ poly patterning.
The silicide can be very thin, for its purpose is to allow the p+
poly layer to become very thin also and yet the silicide/ poly
combined sheet resistance remains reason...