I am also looking for a recipe to etch 10um deep polymer with vertical wall profile(linewidth~8um with Al or NiCr mask, spacing~250um) with SF6/O2/CHF3 gas chemistry using "Oxford Plasmalab 80 plus" system. If any one has any kind of recipe or research paper please let me know. Michael D Martinwrote: I would increase flow rates to reach a pressure of 100-200mT and boost power to 250-350W. The white powder is likely sputtered silicon /silicon dioxide redeposition. You might consider running a cleaning cycle before processing. It's been our experience that this improves repeatability, particularly for a multiuser piece of equipment. Pramod Gupta 21084 Red Fir Court Cupertino, CA 95014 Phone: (408) 253-1646