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Browse Prior Art Database

Self Aligned Contact Stud for Planar Double-poly Bipolar Transistor

IP.com Disclosure Number: IPCOM000121222D
Original Publication Date: 1991-Aug-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 2 page(s) / 107K

Publishing Venue

IBM

Related People

Warnock, J: AUTHOR

Abstract

Disclosed is a process which provides a self-aligned metal contact stud to a planarized double-poly bipolar transistor. The metal is self-aligned to the emitter and to the extrinsic base edge, providing a density improvement and avoiding a difficult S-stud etch.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Self Aligned Contact Stud for Planar Double-poly Bipolar Transistor

      Disclosed is a process which provides a self-aligned
metal contact stud to a planarized double-poly bipolar transistor.
The metal is self-aligned to the emitter and to the extrinsic base
edge, providing a density improvement and avoiding a difficult S-stud
etch.

      The technique to be described provides a self-aligned metal
contact stud to the emitter and base of a double-poly bipolar device,
which has been planarized according to a procedure which has already
been described in [*].  The metal is deposited by a CVD process
(i.e., CVD tungsten) which can be used to simultaneously fill the
collector trench contact.  These metal contact studs then replace the
conventional tungsten vias formed by etching through a thick
planarized passivating oxide to form contacts to the device, followed
by tungsten fill and planarization.  The scheme provides the
following advantages over metallization schemes presently practiced:
      1) The tungsten stud ends up being self-aligned to the emitter
opening and to the extrinsic base edge.  This allows the achievement
of higher densities than is attainable with current stud/metal
processes.
      2) The contact/stud etch is extremely simple, and no special
etch stop is required.  This simplifies the FEOL/BEOL interface
considerably.
      3) After the definition of the self-aligned stud, the wafer
surface is planar, and a conventional thick metal can be patterned
without an intervening dielectric.  Also, the metal need not overlap
the contact holes, which have been filled with tungsten.

      The process assumes a planar double-poly self-aligned bipolar
process [*], with the diel...