Optical coatings for excimer laser applications

Abstract

radiation a prominent role in optics to provide high resolution. Mainly excimer lasers show potentials for future applications like ultra-precision machining and measurement, minimal invasive brain-, vascular-, and eye surgery, components for data communication, and large-scale integrated (LSI) electronic devices. For the engineer, the main challenge is to provide efficiency. In order to take advantage of the expensively generated UV photons, efficient optical components are required with extreme technical demands. Efficient UV optics can only be realized by dielectric coatings, hence stable coatings belong to the most important issues to improve efficiency. Optical lithography is the technology driver in the development of optical components and coatings for shorter and shorter wavelengths. Investigations have been concentrated on the excimer laser wavelengths 248nm, 193nm, and 157nm. Now, considerably shorter wavelengths of about 13.5nm are becoming important for the so-called Next Generation Lithography. In this short overview, first of all the basic interaction mechanisms of UV photons with dielectrics are reviewed. Then, results achieved at coatings for deep ultraviolet (DUV, 248nm and 193nm) and vacuum ultraviolet (VUV, 157nm-50nm) are presented. Finally, a preview for applications in the extreme ultraviolet (XUV: 50nm-1nm) will be given. The primary repositories of information in the UV-coating field are the annual proceedings of the "Boulder Conference on Laser-Induced Damage in Optical Materials", the SPIE and OSA conferences, and the SEMATECH Meetings. Recently published review articles which include detailed references can be found in [1]. © 2005 Springer-Verlag Berlin Heidelberg.