Excimer Laser Micromachining and its Applications

Abstract

Non-conventional, non-contact type advanced machining process like laser based micro machining process is widely used in modern industries for producing components with geometrically complex profiles. Though laser based micro machining of polymer, by and large, is a cold ablation process, photo thermal process associated with the laser heating may affect the surface characteristics. This chapter starts with an introduction to various excimer laser sources and proceeds to micromachining application areas with specific reference to polymers. The study of excimer laser micromachining in different gaseous media, conducted by the authors is elaborated further. This study was conducted to ascertain the impact of purging with gases such as air, argon, nitrogen, helium and hydrogen during the laser ablation process. A negative photo resist , E-1020 obtained from M/s Cadmosil Chemical Pvt. Ltd, India was studied using 248 nm KrF excimer laser . The effect of gas purging on the ablation rate and surface characteristics of the polymer was studied. Amongst the gases used, hydrogen gas showed distinct results with respect to ablation rate and surface characteristics. It has been observed that hydrogen gas has enhanced both the ablation rate and the surface quality significantly. The role of hydrogen gas in enhancing the laser ablation rate may be attributed to the possible involvement of hydrogen gas in the laser assisted chemical reaction with polymer. Eximer laser micromachining process is characterized by a number of process parameters that determines efficiency, economy and quality of the whole process. In this chapter, the details of the experiment along with the results and observations, with areas for future study have been presented.