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.