Dear all, Sample: AlGaN/GaN (2um) on Silicon substrate (500um) Size: 1.4cmx1.4cm pieces At some point of my process line I have Ti/Al/Ti/Au contact on the top side. After that, I had to deposit PECVD 12um oxide on the back side to have pockets for Si etch (SiO2 acts as masking layer for anisotrpic Si etch- Bosch process). After I dip it in BOE soltion, the top contacts wash away :( . Any solution or suggestion? Muhammad Qazi Dept of EE University of South Carolina