I did bake the sample before applying the resist at 120deg for 10  min
in the oven to remove moisture before applying the resist. That also
helped a lot to make the resist stick better.

Karin

>
>
>
>>Dear friends,
>>
>>I want to etch 250nm of SiN without attack the GaAs substrate. I tried the
>>wet etch using HF and photoresist as the etch mask. But the PR all peeled
>>off during the etching even after hard baked. I am wondering if anyone has
>>a suggestion on the etch of SiN.
>>
>>Thank you very much,
>>
>>Zhiyan
>>
--

Dipl.-Ing. Karin Buchholz
Walter Schottky Institut
Technische Universitaet Muenchen