Characterization and Cu Electroless Plating of Laser-drilled Through-Wafer via-holes in GaN/Al2O3

Abstract

GaN on Al2O3 was drilled with a high power Nd:YAG laser. Micro-Raman spectroscopy showed that the induced damage was nominal at about 15 μm from the edge of the drilled through-wafer via-holes. Cu plating was accomplished using an electroless plating technique. FIB was employed to expose the interface between electrolessly plated Cu and GaN on the sidewall of the drilled holes, followed by SEM/EDX to confirm that the sidewall of the drilled holes was successfully covered with Cu. Cu electroless plating after laser drilling has the potential to simplify device layout and improve device integration.