dear shankar, reason is the sme as discussed earlier. manish hooda ----- Original Message ----- From: "Shankar Dutta"To: Sent: Saturday, September 09, 2006 12:55 PM Subject: [mems-talk] DRIE etching > we are trying to do a DRIE etching (~15-20 micron deep) for comb like structure. the masking layer is 0.3micron oxide layer. we patterned the oxide layer by BOE etchant. after that we performed the DRIE experiment. but surprisingly we find some scalopes in etched area, as if it does some isotropic etching. is this problem related to paterning of oxide layer with BOE.