To all,

does anyone know, what could cause adhesion problems of photoresist on SiO2
after etching in TMAH?
I oxidize a Si-wafer (double polished) and pattern the SiO2 on the backside.
Then I etch it in TMAH. If I want to pattern the
same SiO2 on the frontside, the HF undercuts the photoresist even with the
use of HMDS as an adhesion promoter.
It is the same procedure than the backside. Thanks for your help.
-Andreas