You might try a "high" pressure somewhat isotropic etch at the end of
your process. First you will have to remove the teflon like coating with
an oxygen plasma.

-Mike

>>> Jvaneisden@uamail.albany.edu 10/27/2003 6:05:20 PM >>>
Dear all,

We are trying to etch vias (3-10 um) to a depth of 5 um with sidewall
roughness under 30 nm. The mask we use is 1 um thermal oxide. I would
like to ask you all if there is any way the Bosch process can be
adapted, or if there is a gas chemistry we can use to do a RIE process
that gives us these smooth sidewalls. There should be little or no
mask
undercut.

We have tried running a Bosch like recipe using very little ICP power
and short cycles, which gave us too much sidewall roughness.
The available chemistries are CHF3, CF4, O2 and N2 on the dieletrics
chamber and SF6, C4F8, O2 and Ar on the Bosch chamber.

I would very much appreciate ideas and suggestions.

Regards,

Jobert van Eisden
Graduate student
SUNY Albany

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