Browse Prior Art Database

Self-Aligned Sub-Micron Trench Isolation

IP.com Disclosure Number: IPCOM000119345D
Original Publication Date: 1991-Jan-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 2 page(s) / 65K

Publishing Venue

IBM

Related People

Hsu, LL: AUTHOR [+3]

Abstract

This self-aligned trench isolation process produces submicron trenches which isolate p/n regions for advanced devices.

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This is the abbreviated version, containing approximately 85% of the total text.

Self-Aligned Sub-Micron Trench Isolation

      This self-aligned trench isolation process produces
submicron trenches which isolate p/n regions for advanced devices.

      In general, a complementary device needs separate masks to
generate p+, n+ ion implant regions to form sub-collectors or n-p
wells.  In order to prevent "cross talk" between n/p regions, deep
trench isolation is required to separate them.  The alignment of the
trench mask becomes very difficult when device dimension shrinks to
sub-micron region.

      This process requires only one mask to achieve p/n
implantations and provide trench isolation.  Since every level is
self-aligned, almost any conventional optical tool can do the job.

      The fabrication steps are outlined as follows:

      Fig. 1.   A conventional polyimide lift-off structure is used
to define p+ region by ion implantation.

      Fig. 2.   Deposit a layer of 1.0   -thick sputtered quartz
followed by a thin layer of sputtered A12O3 .

      Fig. 3.   Lift-off the original pattern and implant to define
the n+ region.

      Fig. 4.   Deposit another layer of 1.0   -thick sputtered
quartz.

      Fig. 5.   Coating the structure with a conventional planarizing
material.

      Fig. 6.   After the first stage of etch back and stop at the
surface of the second quartz.

      Fig. 7.   After the second stage of etch back, because quartz
is etched faster than the planarizing ma...