Hi Lihuan,

Both SiO2 and Si3N4 can be etched with SF6 as the F source. However,
it's impractical to suggest starting conditions without knowing additional
constraints such as degree of anisotropy, profile requirements, etc.
- Nominally, SiN will etch in low ion energy regimes whereas SiO requires
higher ion energies - however, this also tends to be reflected in the etch
profile seen in F plasmas without passivation components (SiN often
will be isotropicly etched).

Therefore additional information that would help would be:

- Profile and CD requirements
- Film thicknesses (SiN, SiO and resist)
- Whether substrates are actively cooled (or whether you're using small
parts of a wafer on a carrier).

Apologies for answering a question with a question (a few questions that
is)
but this will help in answering you. On a practical front, have you
contacted
the vendor?

Good luck, Andy

Message text written by General MEMS discussion
>
Dear experts,

We only have the following gases available in our Oxford plasma lab ICP
etching system, SiCl4, Cl2, CH4, H2, SF6, O2, Ar and N2.  I want to etch
both SiO2 and Si3N4 (seperately, selectivey not needed, layers were CVD
grown on III-V, say GaAs substrates) with a acceptable etch rate, say
>50nm/min (preferably >100nm/min).  I prefer to use resist as mask.  Can
anybody give me a receipe such that I have something to start
optimzation with?  Thanks a lot.

Best regards,

Lihuan


--
Lihuan Song
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