Karolina,

Many thanks for your reply. The roughening of the silicon surface that
we see is not burnt resist. Except for the HF vapor etch our process
is robust and the PR is not burnt during DRIE. In fact, the silicon
surfaces look clean and shiny before the HF vapor etch  as far as can
be seen in a microscope.

Since I wrote the first e-mail we have studied the fabricated devices
in SEM and we can confirm that there is a roughness on the front side
silicon after the HF vapor etch. There is no roughening on the
scalloped sidewalls nor on exposed silicon handle layer silicon below
the BOX or the polished backside silicon.

Right now I am thinking that it might have something to witht the
Aluminum deposition or etching.

best,

Sven


On Fri, Apr 30, 2010 at 8:36 PM, Karolina  wrote:
> Dear Sven,
>
>  I exclude the polymer layer C4F8.
> I think it might be the photoresist that remained after one of the earlier
> step you had performed before HF etching. The remained PR has been become
> black on the front side.
> It could be not stripped well,
>  Maybe the PR was burned during DRIE?
>
> Best Regards.
>
>  Karolina