EXCIMER-LASER ABLATION AND ACTIVATION OF SIOX AND SIOX-CERAMIC COUPLES FOR ELECTROLESS COPPER PLATING

A XeCl (4.0 eV photon energy) pulsed excimer laser was used to study the ablation behavior of substoichiometric silicon oxide (SSO), SiO(x) with x approximately 1.0. The SSO ablation rate was quite high and its ablation threshold quite low (less-than-or-equal-to 0.3 J/cm2), thereby making it an interesting material for pulsed laser patterning without the use of deep-UV radiation. Surface activation, as illustrated by subsequent copper deposition by the electroless process, was observed along well-defined narrow (approximately 10-20 mum) lines just beyond the edges of ablated trenches in SSO deposited on XeCl-transparent fused silica substrates. When a thin layer of SSO was deposited on polycrystalline Al2O3 or AlN substrates and subsequently laser treated, surface activation of these ceramics occurred on the laser-irradiated regions at much lower fluences and with fewer exposures than are required to activate the bare ceramic substrates. In both types of experiment, activation is believed to result from redeposition of elemental silicon, an ablation product.