Dear all:

I'm a beginner of MEMS field.

After e-beam lithography with 100nm PMMA,
I would like to etch silicon DRY oxide less than 80nm height.
The size of the pattern of e-beam lithography is 200~300nm.
I also hope the slop of the echted wall is NEGATIVE.

Could you recommend any CONTROLLABLE chemical(wet) methods for this work?
I heard the normal HF have a fast etch rate.
Any comments are welcomed.

Thanks in advance.

S. Lee / Graduate Student