Hi all,

here i have (110) silicon wafers coated with silicon nitride.
I patterned the silicon nitride and etched the wafers in KOH and obtained
silicon pieces of lateral size 20x70mm.

I need to pattern the silicon nitride on such silicon pieces.
I cleaned the silicon pieces with acetone/IPA then RCA1 and RCA2 to remove
any residue. I coated the silicon pieces with S1813 photoresist and tried
to pattern the silicon nitride with BHF. After sometime the PR is removed
from the silicon pieces.

I suppose the starting silicon pieces were not correctly cleaned. Any
suggestion on how to improve the cleaning ?

Best regards,
Andrea