Hi,

BOE etches Ti, maybe you can try a different metal.

AniL

QAZI, MUHAMMAD wrote:
> 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?