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Process to Reactively Etch Al2O3 for Thin Film Head Fabrication

IP.com Disclosure Number: IPCOM000103508D
Original Publication Date: 1990-Dec-01
Included in the Prior Art Database: 2005-Mar-18
Document File: 1 page(s) / 70K

Publishing Venue

IBM

Related People

Chen, MM: AUTHOR [+3]

Abstract

Wet chemical etching in phosphoric acid or other etchants has been a common practice to open via holes through Al2O3 films with thicknesses of several micrometers. Because of the relatively large via hole dimension, the chemical etching process is satisfactory in spite of the inherent concern of etch undercut and windage control associated with the process. However, as the device size shrinks, the limitations of the chemical etching start to be a concern. Demand of better control on the etched dimension increases with the device size reduction. There are also other novel device structures which require an anisotropic Al2O3 etching process with good dimension control, small undercut, good etch selectivity with respect to underlying materials and no material build-up at the side walls of the etching mask.

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Process to Reactively Etch Al2O3 for Thin Film Head Fabrication

      Wet chemical etching in phosphoric acid or other etchants has
been a common practice to open via holes through Al2O3 films with
thicknesses of several micrometers.  Because of the relatively large
via hole dimension, the chemical etching process is satisfactory in
spite of the inherent concern of etch undercut and windage control
associated with the process.  However, as the device size shrinks,
the limitations of the chemical etching start to be a concern. Demand
of better control on the etched dimension increases with the device
size reduction.  There are also other novel device structures which
require an anisotropic Al2O3 etching process with good dimension
control, small undercut, good etch selectivity with respect to
underlying materials and no material build-up at the side walls of
the etching mask. Ion milling by high energy argon ions is a good
candidate for this purpose.  The ion milling technique, although
meeting most of the criteria, has its limitations such as lower rate,
poor etch selectivity and edge build-up.

      The etch rate of Al2O3 and etch selectivity of Al2O3 to
permalloy can be enhanced by etching Al2O3 films in a reactive plasma
with a mixture of argon and fluorocarbon gases.  The etching system
used in this experiment is an ECR-RF hybrid plasma reactor.  The etch
rate enhancement can be shown by etching Al2O3 films in a system with
the following conditions: total...