SU-8: a low-cost negative resist for MEMS

TLDR

SU‑8 is a negative photoresist that can be produced with commercially available materials. The paper characterizes a home‑made negative photoresist developed by IBM. The authors prepared three blends and presented their optical and mechanical properties. The resist can be spun to thicknesses from 750 nm to several micrometers using a conventional spin coater, yields aspect ratios of ~15 for lines and ~10 for trenches when exposed with a standard UV aligner, and enables fabrication of highly integrated electromagnetic coils via copper electroplating.

Abstract

This paper describes the characterization of a home-made negative photoresist developed by IBM. This resist, called SU-8, can be produced with commercially available materials. Three blends were prepared for this article and some of its optical and mechanical properties are presented. One of its numerous advantages is the broad range of thicknesses which can be obtained in one spin: from 750 nm to with a conventional spin coater. The resist is exposed with a standard UV aligner and has an outstanding aspect ratio near 15 for lines and 10 for trenches. These ratios combined with the electroplating of copper allow the fabrication of highly integrated electromagnetic coils.