Abstract

Microstructuring with, for example, excimer lasers is going to become a well established tool for industrial manufacturing. For these lasers typical optical set-ups are based on a mask projection technique. In some applications, however, the mask transmission is very small due to a small ratio of the hole pattern area to the whole illuminated area of the mask. For instance, in electronic industries the vias that have to be drilled on high packed multilayer boards have an integral cross-section of about one percent of the mask’s area. To increase the process efficiency, the reflected part of the laser beam can be used to irradiate the mask several times by means of an adequate illumination system. Further, the quality of the laser-induced structures is determined by the homogeneity and the beam divergence on the target surface.

© 1998 IEEE