On the Mechanism of Laser Enhanced Plating of Copper

Copper plating from sulfuric acid is enhanced under laser illumination. The mechanism of laser enhanced plating has been studied in terms of photoeffects and thermal effects. To distinguish between these two effects, the temperature of the electrode under illumination was monitored with a specially designed rotating disk electrode. Temperature dependence of the copper deposition reaction has also been studied and the activation energies for the kinetic and diffusion controlled deposition currents determined. The apparent charge transfer coefficient has been shown to be strongly temperature dependent. The enhancement in the plating rate under laser illumination is ascribed to temperature related processes, though some dependence on the optical properties of the electrode material has also been established. A model for an illuminated rotating disk electrode is presented.