Smooth polycrystalline ceramic substrates with enhanced metal adhesion by pulsed excimer laser processing

Abstract

Multishot pulsed XeCl (308 nm) excimer laser irradiation of commercial fine-grained polycrystalline alumina substrates is found to significantly improve their properties for metal film-bonding applications. A smoother surface finish is obtained, and the adhesion strength of subsequently deposited copper films to the laser-treated alumina surface is increased by a factor of 3–5 (200%–400%) under optimum laser conditions. Smoothing occurs when the alumina melts and undergoes molten flow before resolidifying. XPS measurements suggest that electrical activation of the near-surface region also may contribute to the enhanced copper adhesion.