Product Code: ICAL08_M501

Top Hat Laser Direct-write Processes in Semiconductor and Solar Cell Technology
Authors:
Frank Toennissen, LIMO Lissotschenko Mikrooptik Gmbh; Dortmund Germany
Oliver Homburg, LIMO Lissotschenko Mikrooptik GmbH; Dortmund Germany
Thomas Mitra, LIMO Lissotschenko Mikrooptik Gmbh; Dortmund Germany
Vitalij Lissotschenko, LIMO Lissotschenko Mikrooptik Gmbh; Dortmund Germany
Presented at ICALEO 2008

Direct laser patterning of various materials has found its way into several micro-system production lines like inkjet printing, solar cell technology, flat-panel display production, semiconductors and medical treatment. Typically, TEM00 single-mode solid state lasers and their higher harmonics are used, especially for machining of holes and trenches. The most prominent lasers are short pulse solid-state lasers based on Nd-doped gain materials and their harmonics @ 266, 355 and 532 nm. Traditionally, the original Gaussian beam profile is used. With optimised top hat optics the quality of the generated micro-structures - especially straightness and steepness of the edges - can be improved. Additionally, the process time can be reduced since for a top hat profile less energy is lost in the shoulders of the profile compared to a Gaussian one. Based on LIMOs unique production technology free-form refractive optics were developed which exhibit high efficiencies (> 98%) and inhomogeneities below 10 % (typically 5%). Such modules are available for all TEM00 lasers with wavelengths from 266 nm up to 10.6 µm with field dimensions starting from about 30 µm. Superior processing results obtained with these optics will be shown for the patterning of holes and trenches in various materials that are widely used in semiconductor technology and solar cell processing such as silicon, ceramics, insulators and transparent oxides.