We have good results with oxide as a hard mask. Typical selectivities are
>60:1 using oxide. Better than that we have had great results using SU-8 from
Microchem corp. Initial results show a 40:1 selectivity pr:silicon and SU-8
formulations can range from 5-100 microns. It also seems to ash or strip
reasonably well at around 3 microns/minute. Bob Henderson