Laser-Enhanced Plating and Etching: Mechanisms and Applications

We have developed experimental electroplating, electrodeless plating, and etching techniques that use a focused laser beam to define the localized plating or etching region. Enhancements in plating (etching) rates up to ≈103to 104, compared to background rates, have been observed in the region of laser irradiation. A thermal model has been developed to describe the observed effects over the entire overpotential (polarization) curve. In the low overpotential region the enhancement is dominated by the increase in the local charge-transfer kinetics due to the local increase in temperature produced by absorption of the laser energy by the cathode (anode). At higher overpotentials, in the mass-transport-limited region, the main enhancement occurs due to hydrodynamic stirring caused by the large local temperature gradients. Examples of gold, nickel, and copper electroplating are described to illustrate the value of this technique for micron-sized circuit personalization and repair. Additional examples of electroless laser-enhanced plating and exchange plating are also described.