Epoxy-novolak thick film resists are of interest for applications where the resist pattern remains in the device serving as
mechanical alignment aids, micro channels or protection layers. For these applications, good mechanical properties are of
interest. Unfortunately mechanical strength comes with high cross-linking density and, therefore, high tensile stress. We
report here on a comparison of three commercially available thick film resists with respect to the following criteria:
thickness and uniformity on high topography wafers, i-line photo speed, adhesion on Si3N4, hardness and plasticity, glass
transition temperature and wafer warp. The three resists (2 types of SU-8 [MicroChem Corp.] and one type of TMMR
[Tokyo Ohka Co., LTD]) show different behavior as a result of the different solvent, photo-acid-generator (PAG) and
polymer properties, and trade-offs have to be made depending on the applications.