Smooth 3-D shaping of thick resists by means of gray tone lithography

Abstract

This paper reports on the study of arbitrarily 3D shaping of negative and positive thick resists, using common technologies in standard IC fabrication. Particular emphasis is put on the design, manufacturing and use of half-tone transmission masks, required for UV-lithographic step in the fabrication process of mechanical, optical or electronics components. The original design and fabrication method, for so-called gray-tone reticles, were supported by experiments showing the main advantage of this new technology, the 3D structuring of thick resists in a single exposure step and also a high aspect ratio obtained of over 9:1. Experimental results are presented in SEM micrographs only for positive thick resists. Finally, by optimization of the lithographic process, interesting applications are shown.