Yilei: You can first use 100% oxygen plasma to remove polymer then follow with H2SO4+H2O2 wet bath at 100 degrees C rinse with di water then place in HF solution for removal of SIO2 remaining mask. Bob Henderson -----Original Message----- From: yilei zhangSubject: [mems-talk] residues on RIE etched sio2 Hello colleagues: I used rie (10% O2, 90% CF4) to etch silicon with a polymer layer and a sio2 mask, but found the left sio2 cannot be further etched away with HF. I searched the archive and found the RIE may generate a polymer layer or fluorocarbon, and a layer of fluorinated si. I want to know is there any way to remove the left sio2 mask? Thanks. Regards, Yilei Zhang