Browse Prior Art Database

Chromic/Phosphoric Alternative Preclean

IP.com Disclosure Number: IPCOM000037524D
Original Publication Date: 1989-Mar-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Doane, LM: AUTHOR [+5]

Abstract

An improved aluminum preclean solution produces a better contact surface without contaminating the preclean bath and causing product corrosion problems.

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Chromic/Phosphoric Alternative Preclean

An improved aluminum preclean solution produces a better contact surface without contaminating the preclean bath and causing product corrosion problems.

Ammonium dichromate can be substituted for chromium trioxide in phosphoric acid/deionized water to render a solution that drastically reduces degradation of a photoresist while maintaining the contact resistance inherent with the use of chromium trioxide.

Chromium trioxide is used in conjunction with phosphoric acid and deionized water as a metal preclean prior to deposition of second level metal. The bath is used to form a chromium/phosphorus/aluminum/oxygen-containing surface following removal of or by reaction with the native oxide of aluminum. The effect of the metal preclean is improved contact resistance.

It has been determined that degradation of the photoresist occurs during exposure to the chromium trioxide/phosphoric acid bath leaving residue on the product comprised of residual resist, phosphorus and chromium (residual photoresist also contains sulfur). These residuals have been associated with corrosion of SFET product during temperature and humidity testing. The residuals may concentrate in the bath increasing the contamination of product processed subsequently.

If ammonium dichromate is substituted for chromium trioxide in the bath, interaction with the photoresist is drastically reduced if not eliminated. Ammonium dichromate (in phosphoric acid/deionized wate...