New Chemical Request: Perfluorooctyl-trichloro-silane

Mary Tang mtang at stanford.edu
Thu Feb 16 16:24:42 PST 2006


Hi Neville --

I'm writing on behalf of SpecMat.   In principle, this chemical is 
approved for use in SNF with one condition and one suggestion.

Condition:  The dessicator should be dedicated for this purpose (to 
minimize the possibility of cross-contamination to other processes.)  
Please work with Mahnaz to obtain, label, and find a place for a 
dedicated dessicator (Mahnaz, do you want to use the same one that's there?)

Suggestion:  Have you considered using the tri-ethoxy version of your 
chemical?  (See Petrarch/United Chemical Technology website:  
http://www.unitedchem.com/PDF/Surface_Modifying.pdf)  The reason is that 
the chlorosilanes tend to react quickly with moisture (even in the air) 
and over time will polymerize into nice particles if stored in pure or 
concentrated solution.  Also, the byproduct of reaction is HCl.  At the 
volumes you are using (100 microliters), this isn't likely to be a 
problem, but something to consider if you should ever decide to scale 
up.  The triethoxy version is less hygroscopic and the byproduct is 
alcohol.  I am not sure of the vapor pressure of the triethoxy material, 
but I would imagine it is similar to the stuff you're using.  Again, the 
triethoxy material is not a SpecMat requirement, but just a suggestion. 

Mary


Neville Mehenti wrote:

> Hello,
> I would like to make a request to bring a new chemical into the 
> cleanroom for use in a process.
> Below this email is the requested information for this new chemical 
> request, as outlined on the SNF website.
> Please let me know if there is a problem or if you would like any more 
> information.
> Thanks very much and hope to hear from you soon.
> Regards,
> Neville
>
> 1.  Name: Neville Mehenti; Coral: mehenti; Tel: (650)723-1669; Email: 
> nmehenti at stanford.edu, PI: Prof. Stacey F. Bent
>
> 2.  Full Name: 1H,1H,2H,2H-Perfluorooctyl-trichloro-silane (CAS 
> 78560-45-9)
> The MSDS is attached with this email as a pdf file.
>
> 3.  Manufacturer:  Sigma-Aldrich
> 3050 Spruce Street, St. Louis, MO 63103; Tel: 314.771.5765; Website: 
> http://www.sigmaaldrich.com/
>
> 4.  The reason I am requesting to bring this material into the lab is 
> because I am looking to spin thin (10-20 microns) silicone membranes 
> on a silicon-photoresist mold, and then peel them off to serve as 
> components for microfluidic devices.  I have been using 
> polydimethylsiloxane (PDMS) as the membrane material, but the 
> membranes are not strong enough to resist tearing or stretching upon 
> removal from the mold.  I have found that treatment of these molds by 
> exposing them to this requested chemical under vacuum allows for 
> easier release of the membrane from the mold with minimal stretching.  
> By silanizing the silicon-photoresist mold with this chemical, the 
> surface of the mold is effectively "teflonized," thus preventing any 
> strong interaction between the PDMS and the mold.  I would prefer to 
> do this process at the fab so that my molds remain in a clean 
> environment (since I have had particulate problems when silanizing in 
> my normal lab and this creates several problems with the resulting 
> membranes).
>
> 5.  I plan on using this chemical only in the desiccator above the 
> Headway.  I will place my silicon photoresist molds along with a small 
> volume (~100 microliters) of the chemical in the desiccator and pull 
> house vacuum on it for one hour, thus forming silane vapor which will 
> subsequently react to the native oxide on the mold.  I will then spin 
> PDMS on these molds using the Headway, and they will then require no 
> further processing within SNF.
>
> 6.  For each time I silanize my molds, I will be using ~100 
> microliters of this chemical, which is in liquid form.  Only a small 
> fraction of this volume will be vaporized to properly silanize the 
> surface of my molds.
>
> 7.  I will carefully bring in the appropriate volume (~100 
> microliters) of the chemical into SNF each time I need to use it.  The 
> chemical will be stored in a labelled 1-ml glass vial, and will be 
> brought in within a larger vial as a secondary container.  When placed 
> in the desiccator, I will remove the cap from the vial and place the 
> vial in one of my beakers (in order to stabilize the vial from falling 
> due to a bump or rapid pressure changes).
>
> 8.  After the silanization process, I will put the cap back on the 
> vial, and place this vial back in the secondary container.  These 
> vials will be removed from the fab and I will dispose of it properly 
> within my regular lab as hazardous waste. 



-- 
Mary X. Tang, Ph.D.
Stanford Nanofabrication Facility
CIS Room 136, Mail Code 4070
Stanford, CA  94305
(650)723-9980
mtang at stanford.edu
http://snf.stanford.edu





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