request to use PDMS in P5000
mtang at stanford.edu
Wed Jan 4 07:47:15 PST 2006
Hi Alissa, Jim --
I think I have this information somewhere, from a previous request. As
I vageuly recall, PDMS (Dow Corning Sylgard 182 or 184) is based on a
Pt-catalyzed reaction, although very little Pt is actually present.
Other metals and impurities, such as sulfur, will prevent
polymerization. So, other than the Pt, PDMS is actually pretty clean --
although perhaps not by electronics-grade standards, it's cleaner than
your ordinary plastics. I'll see if I can find the info. I think that
Claudia Richter provided it, so I'll also check with her.
Just on a side note, I'm personally less concerned about the potential
contamination than the process flow itself (Alissa, perhaps you've got
experience or references on this already.) 500 microns of PDMS is
pretty thick... It's got a high thermal expansion coefficient, so I'm
not entirely sure that you could put 0.5 microns of Al on it without
having it peel off due to stress differences, even with an adhesion
layer (although having thin lines might help). I think Claudia or
Neville Mehenti may have experience in depositing metals on PDMS in our
lab (although I'm pretty sure they would have used metalica or
innotec.) By the way, does your request entail using gryphon for Al
Also, PDMS is a darn good insulator -- I think the Al etch rates and
profiles may be very different than they would be on silicon due to
differences in plasma behavior (at least, I understand that P5000
etching of films on quartz is very different from etching on silicon.)
I would suggest that if you have problems, a thinner PDMS layer (tens of
microns -- you may have to dilute and spin coat) might help.
Constrained PDMS (by adhesion at the Si/PDMS interface) won't expand as
much and electronic effects on plasma *might* be reduced.
Again, I'll if I still have the purity info, and if not, I'll drop a
note to Claudia. I think that Dow provided this info to Claudia (or
whomever it was who gave it to me) so you might try asking them.
Jim McVittie wrote:
>During the overetch, the Al etch chamber will be contaminated by the
>decomposition products of the PDMS. So the important question what is in
>PDMS and is it a problem to other users of the chamber. My concern is
>what metals at in PDMS and at what level. Can you find a purity analysis
> Thanks, Jim
>"Alissa M. Fitzgerald" wrote:
>> Part 1.1 Type: Plain Text (text/plain)
>> Encoding: 7bit
Mary X. Tang, Ph.D.
Stanford Nanofabrication Facility
CIS Room 136, Mail Code 4070
Stanford, CA 94305
mtang at stanford.edu
More information about the specmat