[labnetwork] How do you handle PDMS in a cleanroom environment?

Thu Nov 26 11:03:54 EST 2015

Hi Leif --

At SNF, we do allow PDMS in the cleanroom, with certain restrictions.

1.  It must be of the Sylgard 182 or 184 or similar variety, where there 
no volatile organics (i.e., no RTV's.)
2.  Mixing and degassing are done outside of the cleanroom (we have a 
Thinky mixer in a prep area outside the cleanroom).  This is to prevent 
uncured silicone oils from migrating everywhere -- as others have noted, 
extremely careful handling is required, but not a skill most of our 
students have acquired.  If they spill the mixed PDMS, it will self-cure 
within a day.
3.  Uncured PDMS is allowed only in the manual spin coat station (the 
one that can be lined with foil, for quick cleanup) and on the adjacent 
hot plates, when covered with foil.
4.  Cured PDMS is allowed only in certain tools -- generally, those that 
run at low temperatures and are not used for front-end device processing.

We've been able to control it, for the most part, because up to now, 
it's been a small population of researchers using this.  But because of 
increased interest, we are trying to create establish more processes and 
create more work spaces outside the cleanroom, where students can spin 
coat, UV or plasma treat, bond, etc.

Mary

__
Mary X. Tang, Ph.D.
Lab Manager
Stanford Nanofabrication Facility
Paul G. Allen Building
Stanford, CA.  94305
mtang at stanford.edu
(650)723-9980
http://snf.stanford.edu

On 11/25/2015 8:31 AM, Vito Logiudice wrote:
> Hi Leif,
>
> Based on some past experience with PDMS I agree with the concerns 
> expressed by your engineers. If PDMS is handled carefully and 
> conscientiously by your end users then possible damage can be 
> contained or at least limited should it come into contact with any of 
> your equipment. The problem many of us face in an academic setting 
> however is the vast diversity of people whom use our facilities. A 
> minority of these individuals tend to be 
> inexperienced/disorganized/messy/self-absorbed and it is these people 
> whom will possibly wreak havoc should you allow them to work with PDMS 
> in your cleanroom. I recall slipping on a large glob of uncured PDMS 
> that had been dropped on the floor of the cleanroom by one of these 
> “challenging users" at another site.
>
> Another concern may be the outgassing of silicone over time and its 
> possible effects on other people’s work. I’m not an expert in this 
> particular field but for instance, the use of silicone caulking was 
> strictly forbidden during the construction of our cleanroom here. 
> Hopefully Jack Paul of HDR Architecture will be able to share some 
> insights in this regard (HDR designed our facility).
>
> For what it’s worth we do not currently allow PDMS in the cleanroom at 
> all. Should a well-justified argument for introducing it be made in 
> the future, I would likely insist on only allowing cured PDMS in the 
> cleanroom and only in well-defined, possibly isolated, areas. Uncured 
> work would only be permitted in a satellite (non-cleanroom) lab.
>
> Best regards,
> Vito
> --
> Vito Logiudice P.Eng.
> Director of Operations, Quantum NanoFab
> University of Waterloo
> Lazaridis QNC 1207
> 200 University Avenue West
> Waterloo, ON           Canada N2L 3G1
> Tel.: (519) 888-4567  ext. 38703
> Email: vito.logiudice at uwaterloo.ca <mailto:vito.logiudice at uwaterloo.ca>
> Website: https://fab.qnc.uwaterloo.ca
>
>
> From: <labnetwork-bounces at mtl.mit.edu 
> <mailto:labnetwork-bounces at mtl.mit.edu>> on behalf of Leif Johansen 
> <lej at danchip.dtu.dk <mailto:lej at danchip.dtu.dk>>
> Date: Wednesday, November 25, 2015 at 3:58 AM
> To: "labnetwork at mtl.mit.edu <mailto:labnetwork at mtl.mit.edu>" 
> <labnetwork at mtl.mit.edu <mailto:labnetwork at mtl.mit.edu>>
> Subject: [labnetwork] How do you handle PDMS in a cleanroom environment?
>
> Dear Lab Network,
>
> I have a dilemma. Polydimethylsiloxane (PDMS) is a promising material 
> for soft lithography, and a lot of our users have a strong wish to 
> process this material in our lab – especially for making nanoimprint 
> stamps . However, before being cured, PDMS is basically a silicone 
> oil, and all our front end engineers (plasma chambers, lithography 
> etc. ) are really scared about this substance ending up in their 
> equipment. Our back end engineers (especially the wire bonding 
> engineer) is also strongly opposed to the introduction of PDMS into 
> the back end lab.
>
> Are there any experience out there in the community on how to handle 
> PDMS in a cleanroom environment?
>
> Best regards,
>
> Leif
>
> *Leif S. Johansen ***
>
> Head of Operations
>
> DTU Danchip
>
> *Technical University of Denmark***
>
> 	
>
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>
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>
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>
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>
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>
>
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