I am trying to etch silicon using a TRION DRIE etcher. I am using a SF6/O2
/Ar/He chemistry for the etch. I am using 5.6um of SPR 220-7 positive
photoresist for as the etch mask. After the etching is completed, I see
minute pinholes (pits) on the silicon surface which was masked by the
photoresist. I have checked my photomask and it does not have any
pinholes.Did anyone have a similar experiance with this photoresist for DRIE
? What could be a possible reason for these pits on the silicon surface
masked by the resist ? I am etching for 7 and a half minutes at 50W rie and
3000w icp power to etch 20um of silicon.

Also, I am not doing any post exposure bake or hardbake of the resist.

Thank you,
Bhargav. - UTA