Small structures with large excimer lasers

Abstract

Excimer lasers found their place in industrial manufacturing processes during the last years. The most prominent of these applications is microlithography where features smaller than 0.1μm are created. Besides this, a large variety of manufacturing processes with structure sizes between 10 and 100μm and sub-μm accuracy exist. Such an application is the manufacturing of nozzle plates for ink jet printers. The short wavelength of excimer lasers, mainly 248nm and 308nm, combined with the short pulse duration of 10-30 ns, leads to a clean removal of material ("cold ablation"), with only very limited thermal damage to the surrounding material. The beam of an excimer laser, however, has properties which seem to make these lasers unfit for this type of high precision material removal at a first glance. The beam is rectangular in shape, it has a non-uniform intensity distribution, and the divergence is large and is different in the two dimensions of the beam. Such a laser beam is impossible to focus to a small and well defined spot. © 2005 Springer-Verlag Berlin Heidelberg.