Improvement of flatness of EUVL mask substrate by numerically controlled plasma chemical vaporization machining

Abstract

Extreme ultraviolet lithography(EUVL) is developed as a next generation′s semiconductor device fabrication technology. In the EUVL system, the reflective optics is used, and flatness of 50 nmp–v or less is demanded to the mask substrate. This performance cannot be achieved by conventional mechanical machining method. For this request, we are proposing to apply the numerically controlled plasma CVM as a fabrication method for mask substrate. In this paper, we report the machining characteristic of quartz glass that is one of the mask substrate materials.