Browse Prior Art Database

Dry Etching of A12o3 for VLSI Applications

IP.com Disclosure Number: IPCOM000102827D
Original Publication Date: 1990-Feb-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 40K

Publishing Venue

IBM

Related People

Chow, M: AUTHOR [+2]

Abstract

The Al2O3 thin film, due to its inherent low etch rate in fluorinate gases, is recently proposed to be used as a etch stop layer for dielectric materials such as oxide, nitride. After contacts are made through the dielectric by reactive ion etching and successfully landing at the Al2O3, the Al2O3 at the bases of the vias must be completely removed to ensure low contact resistances.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 95% of the total text.

Dry Etching of A12o3 for VLSI Applications

      The Al2O3 thin film, due to its inherent low etch rate in
fluorinate gases, is recently proposed to be used as a etch stop
layer for dielectric materials such as oxide, nitride. After contacts
are made through the dielectric by reactive ion etching and
successfully landing at the Al2O3, the Al2O3 at the bases of the vias
must be completely removed to ensure low contact resistances.

      The conventional way of removing Al2O3 by dipping in a wet PC
solution (hot H3PO4/H2O2) has resulted in an undercutting problem.
The undercutting is undesirable because it limits the design ground
rule.

      A high etch rate Al2O3 RIE process was developed by using a gas
mixture of C12/BC13/CCF4/Ar in a single wafer reactor.  The optimized
conditions are:  pressure 375 mtorr, power 485 watt, BC13 10 sccm,
C12 11 sccm, CCF4 13 sccm, Argon 15 sccm, electrode temperature 75oC
and electrode spacing about 1 cm.  The resulting Al2O3 etch rate is
1000 Ao/min with 11% 3 sigma uniformity.  The selectivity to oxide is
1.5 :1 and to resist is 1:2.  The poor selectivity to resist is due
to high electrode temperature which is necessary to maintain a
reasonable throughput.

      The overall etch rate is about 100 times higher than the etch
rate of native Al2O3 breaking-through step during the aluminum
etching in a batch tool.  This Al2O3 dry etching process is
considered to be very important for both Silicon and III-V
technologies...