Tough problem. There are some chemical strippers that claim to remove the
polymer residue but that would depend on how bad it is. I have tried rie with
oxygen and cf4 with mixed results that were promising but it doesn't
completely remove without etching some silicon. Do you have the capability to
run the wafers into a furnace at around 1000 C? This might carbonize the
material and allow you to wet clean with Sulfuric/Peroxide. Bob Henderson