Hi all, I would like to protect the front side of my silicon wafer in a KOH wet etch process. (30% conc 85 C). I have an aluminum oxide thin film on the front side that needs to be protected from KOH. I also have Lpcvd silicon nitride as the etch stop from the backside (I am trying to make suspended silicon nitride membranes and the aluminum oxide thin film is supposed to be on the top of the membrane) . I have tried using brewer science's Pro-Tek B3 but am facing adhesion issues. I am contemplating using a mechanical clamp .Does anyone have any experience with such clamps for eg, the AMMT clamp? Also any alternative methods or suggestions about alternative clamp manufacturers would be greatly appreciated. Thank you Bhargav Nabar UT Arlington Nanofab.