Browse Prior Art Database

Use of Silicate to Inhibit the Dissolution of Sputtered Alumina

IP.com Disclosure Number: IPCOM000104282D
Original Publication Date: 1993-Mar-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 1 page(s) / 28K

Publishing Venue

IBM

Related People

Lee, HPE: AUTHOR [+3]

Abstract

A process is described to inhibit the dissolution of sputtered alumina in an alkaline etch process by adding a small amount of sodium meta-silicate to the etching solution and to the photoresist developer solution.

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Use of Silicate to Inhibit the Dissolution of Sputtered Alumina

      A process is described to inhibit the dissolution of sputtered
alumina in an alkaline etch process by adding a small amount of
sodium meta-silicate to the etching solution and to the photoresist
developer solution.

      In making thin film magnetic heads, a Gallium-Indium (Ga-In)
eutectic is used as a thermal conducting medium on the back of the
wafer during alumina sputter deposition.  Removal of Ga-In after
sputter deposition of the alumina can be accomplished by the use of
an alkaline etchant, such as NaOH, for example.  To prevent
dissolution of the alumina during the etching process, a small amount
(0.1M, for example) of sodium meta-silicate (Na sub 2 Si0 sub 3) is
added to the NaOH.  The sodium meta-silicate reacts with the alumina
to form a monolayer of aluminum silicate on the surface, and this
blocks the attack of the hydroxide ion on the alumina while the NaOH
dissolves the Ga-In from the back of the wafer.  In addition, a small
amount of the sodium meta-silicate can be added to the photoresist
developer solution used in subsequent photolithography steps in the
process to prevent attack on the alumina in the structure.

Disclosed Anonymously.