Focussed excimer laser beams: A technique for selective micropatterning

Abstract

Focussed excimer laser micropatterning techniques are proving indispensable to researchers because of their ability to selectively perform ablation processes in highly localized areas without a mask. A typical system includes an excimer source operating at 193, 248, or 308 nm and an optical delivery system which simultaneously focusses the excimer laser light and permits real time viewing of the ablation process. The addition of a programmable stage allows a sample to be moved across the focussed beam for the generation of a variety of patterns covering areas as small as a few square microns to entire substrates. The importance and usefulness of this technique has been reported in such diverse fields as microelectronics packaging, semiconductor technology, optoelectronics, and high temperature superconductor research. Examples show how this micropatterning technique can be used in packaging to selectively remove either dielectric or metallic materials with no damage and to produce novel structures in a single processing step. The repair of electrical shorts and opens in complex microprocessors is discussed as well as applications to failure analysis. Finally several results are described showing the microfabrication of features as small as 1 pm in Hi-Tc superconductors to custom transmission lines.