dear friends, i am having patterned AL layer on si wafer. In my case, I have to etch si for 180 micron, but as Al layers is there, i am unable to mask it with Sio2 or Si3n4. i am using 30wt % KOH at 70-80C as Si etchat. So please suggest me propable solution in this case. with regard abhay joshi, university of pune india