Browse Prior Art Database

High-Performance Bipolar Transistor With Metal-Silicide Collector Contact

IP.com Disclosure Number: IPCOM000120610D
Original Publication Date: 1991-May-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 2 page(s) / 72K

Publishing Venue

IBM

Related People

Dennard, RH: AUTHOR [+2]

Abstract

Disclosed is a high-speed bipolar structure with an improved contact to the buried subcollector using a metal silicide layer which is self- aligned to the edge of the base region.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 58% of the total text.

High-Performance Bipolar Transistor With Metal-Silicide Collector
Contact

      Disclosed is a high-speed bipolar structure with an
improved contact to the buried subcollector using a metal silicide
layer which is self- aligned to the edge of the base region.

      The subcollector process for conventional bipolar transistors
is difficult to scale because very low sheet resistance of the order
of 10 ohms/square is required for high-performance circuits.  A thick
subcollector layer is required, which, in turn, calls for deep
trenches for isolation.  Fig. 1 shows an improved bipolar structure
where a metal silicide layer, formed on the original surface of the
starting silicon wafer, is used to contact the buried collector
region very close to each edge of the active transistor.  The
improved conductivity of the metal silicide layer and the close
proximity of the contact should allow the heavily-doped n+ region to
be made thinner compared to the conventional subcollector.  Moreover,
only recessed-oxide or shallow- trench field regions (not shown) will
be required to isolate devices.  The transistor otherwise is very
similar to present high-performance double-polysilicon self-aligned
structures.

      A set of process steps to achieve the desired structure is
illustrated in Fig. 2.  The first part of the process is to deposit
and pattern a layer of refractory metal, such as tungsten, an
insulator layer, and another refractory metal layer on a p-doped
substra...