Micro-Corrosion of Al-Cu Bonding Pads

Abstract

Aluminum metallization films with copper additions are found to exhibit highly localized pitting in the presence of moisture. Galvanic action of aluminum surrounding Al <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> Cu theta phase particles causes localized aluminum corrosion. The thin layer of aluminum hydroxide corrosion product on the bonding pad creates an effective barrier to high-quality wire bonding.