Laser-Induced Surface Activation of Aluminum Oxide for Electroless Deposition

Abstract

ABSTRACTA new process for writing a copper pattern into alumina or sapphire substrates is presented. This process employs in sequence ultraviolet laser irradiation and electroless deposition of copper. The laser irradiation activates the substrate and copper is deposited in the activated region when the substrate is immersed in the electroless solution. The laser-activation can be performed months in advance to the deposition.A small amount of metallic aluminum is left on the surface of laser irradiated alumina substrates. The presence of this metallic aluminum appears to play a very important role in the laser surface activation process. In addition to aluminum cluster formation there must be other activation centers that promote copper deposition in laser treated alumina substrates. These catalytic centers are much weaker that the aluminum clusters and have been tentatively identified as surface defects.