Thanks for the response. Did you mean diluting PDMS (after mixture) with
solvent like toluene?

Another question is will diluted PDMS be firmed after staying for several
day? Or the solvent will prevent PDMS from polymerization? According to
previous experience, PDMS will be completely dried within two says.

Yun-Ching

-----Original Message-----
Try to dilute your PDMS first. After pouring it, stay in the vacumn for at
least several days.

On Tue, Jul 13, 2010 at 3:38 PM, Yun-Ching Chang  wrote:

> Dear MEMS experts,
>
> I am trying to fabricate nanopillars by PDMS. I first make a silicon
master
> with nano holes. The holes are in depth of 1.5 um and diameter of 200 nm.
I
> try to fill these holes with PDMS.
>
> PDMS (Sylgard 184) is prepared by the conventional method and poured onto
> the template. After peeling off, I found the pillars are much shorter than
> they should be, only 200 nm at most. Actually, they look much like in
> spherical, but cylindrical shape.
>
> I also observe the cross-section of the master after the release. It seems
> there is no residue PDMS inside the master. I am thus wondering if PDMS is
> succesfully filled into the hole.
>
> Is that because of the surface tension that makes PDMS stopped from
filling
> into the holes? I've tried silization for surface treament and degassing
for
> pulling out the bubble. But they didn't seem much different from the
> previous work.
>
> Does anyone have similar experience on this?
>
> Experience on PDMS nanopillars in general is welcome as well.
>
> Thank you,
>
> Yun-Ching
> Penn State Univ.