Hi everybody.,

(1)I deposited about 2000 A of Silicon nitride .

(2) Did the pattern and  used PR as mask after the
development of PR (Shipley 1808 PR -developer 351) to
etch Si.Nitride.

(3) I did etching of Si.Nitride with Hf (Buffered HF)
for about 50 minutes.

(4) Then i removed  PR using acetone.

I surprised to find "NO" Silicon Nitride in the wafer.
HF completely etched Si.Nitride.

Is there any possibility of HF delaminating the PR and
etch complete Nitirde.

What is the maximum duration i can put in HF.

Thanks

Cheers.,
Bala.