This article describes a new negative-tone of photoresist, SU-8, for ultrathick layer applications. An aspect ratio of 10:1 has been achieved using near-ultraviolet lithography in a 200-mu m-thick layer. The use of this resist for building tall micromechanical. structures by deep silicon reactive-ion etching and electroplating is demonstrated. Using SU-8 stencils, etched depths of >200 mu m in Si and electroplated 130-mu m-thick Au structures with near-vertical sidewalls have been achieved.