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Etching of sapphire assisted by copper-vapour laser radiation

An experimental investigation is reported of the etching of sapphire assisted by copper-vapour laser radiation (λ =510 nm, pulse duration 10 ns, repetition rate 8 kHz). Sapphire was etched by irradiation, with a focused laser beam, of the interface between sapphire and an absorbing liquid. Self-modulation of the etching channel depth was observed during scanning with a laser beam. A study was made of the dynamics of formation of etching channels and of the reasons for self-modulation. The etching rate reached 2 mm s-1 (0.3 μm pulse-1) and the spatial resolution of the etch pattern was about 3 μm. Copper was reduced on the etched sapphire surface from a solution suitable for chemical electroless copper plating. The resultant copper film adhered well (18 N mm-2) to the sapphire surface.