> I want to mask HF etching with photoresist. Just now,
> somebody suggest me that
> for the same thickness of oxide I will etch. The photoresist
> could stand
> buffered HF, but for concentrated HF, it will not. Is it
> exactly the case?
> Could I be able to find some reference?

Stronger HF solutions tend to peel the photoresist off,
rather than etching it (indeed, I have sometimes measured an increase
in photoresist thickness after HF-base etches due to absorption).

Concentrated HF (49% by weight) that has been diluted more than about 3:1 by
volume
by H2O or NH4F (40% by weight), to make for example 10:1 HF or 5:1 BHF,
can be used with photoresist for at least a few minutes.

        --Kirt Williams Agilent Technologies