Dear Carol,

        Which photoresist u are using for this and how much is the thickness of
the layer of PR. i expirienced that if u use 2.4 micron of PR thickness and
do hard back for 90 second at 120 degree celcius, it should work fine, or
else u can also go for UV bake prior to etching. of course u can go for Sio2
as hard mask.

with best wishes

Manish Hooda