Dear all,

I'd like to ask you a question about SiO2 etching, I know somebody
already discussed it, but my situation is slightly different. I have a
silicon wafer covered with 300nm thick oxide deposited by CVD and I need
to etch a high resolution pattern on it (minimum feature 110nm). We have
an STS ICP etching system. I can feed Ar, H, SF6, CF4, C4F8, CH4, and O2
in the chamber. CF4 and C4F8 are on the same gas line, so I cannot use
them at the same time (e.g. for passivation purposes).
I would need good sidewall verticality, also the pattern is defined by
photoresist, so the recipe should be able to avoid burning it (I guess
this automatically excludes O2). Most of the literature deals with CH3
recipes in this case, but the problem is I don't have it. The ICP can
run a process between -5C and 50C, it has a maximum RF power of 1000W
for the coil and 1000W for the plate. The pressure limit is 5mTorr.

Thank you very much!

Renzo