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Reactive Ion Etching of Deep Isolation Trenches using SF6/Cl2+O2

IP.com Disclosure Number: IPCOM000120941D
Original Publication Date: 1991-Jun-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 1 page(s) / 42K

Publishing Venue

IBM

Related People

Davis, PD: AUTHOR [+4]

Abstract

This article addresses the problem of etching deep silicon isolation trenches for bipolar transistors.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 99% of the total text.

Reactive Ion Etching of Deep Isolation Trenches using SF6/Cl2+O2

      This article addresses the problem of etching deep silicon
isolation trenches for bipolar transistors.

      The concept disclosed is that the controlled addition of oxygen
to the presently used chemistry results in etching up to ten micron
deep trenches with controlled geometry.

      This concept has been demonstrated in a typical planar design,
non-loadlock diode reactor, with an aluminum upper anode and an
aluminum lower cathode covered by a quartz pallet, upon which the
wafers are placed.

      Simply extending the etching time with similar gas mixtures,
but without O2, results in a negative profile of the trench, which is
unacceptable.

      Experiments in etching deep trenches confirm that the addition
of oxygen is the important variable in controlling trench profile.
SEM micrographs confirm that oxygen is the major element responsible
for the deposition required to passivate the trench sidewall.

      A process window around power and pressure is established to
provide excellent run to run stability.  The data accumulated to date
demonstrates this process yields a high silicon etch rate, good
uniformity, high selectivity (Si:SiO2) and a vertical profile making
it desirable for manufacturing.  The throughput using this 2.5%
SF6/7.5% Cl2/90% He+2.8% O2 process is over 50% greater than the
present process using similar gas mixtures without O2 .

      Disclosed ano...