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.