Poly (styrene-b-ethyleneoxide)

Mary Tang mtang at snf.stanford.edu
Fri Mar 19 15:54:35 PST 2004

Hi all --

The polymer is pretty inert (or at least each block is inert, and it's
likely that the block copolymer is as well).  Benzene is a carcinogen,
but is no worse that chlorobenzene, which is used as a solvent for many
resists used at the headway, which has particularly good exhaust.  The
headway is not really set up for flushing volumes of solvent, but if
only 10 ml are used, then I think it's OK (would you agree, Mahnaz?)

The only other concern I'd have is the post-spin incubation in a benzene
atmosphere.  It seems that you might want to have the chip placed next
to a small beaker of benzene and place these under a larger beaker -- I
think it would be a good idea to place these into a larger petri dish,
in order to contain any possible spills and drips.  I also think that it
would be better to do this incubation in one of the solvent hoods,
rather than at the headway spin bench (since that bench is polypro and
not really meant to be in contact with solvents.)  Vignesh -- is it OK
to transfer your chip from the headway to the solvent bench for
post-spin processing?

What do all you SpecMat'ers think?


Vignesh G Shankar wrote:

>      To the SpecMat Committee,
>      Subject: Approval to use Poly (styrene-b-ethyleneoxide)
>      1. Vignesh Gowrishankar
>      2. 650 736 0268
>      3. vigneshg at stanford.edu
>      4. Prof. Michael McGehee
>      5. Chemical: Poly (styrene-b-ethyleneoxide)
>      6. Will need benzene as solvent
>      7. "Homemade" at IBM Almaden
>      8.  unavailable
>      9. unavailable
> 10. I need to spin coat the block copolymer with benzene as my
> solvent, for which I need a powerful "fume hood" / exhaust.
> 11. This block copolymer self-assembles to give me the structures I
> need. Benzene is the only solvent that works for what I need.
> 12. Headway
> 13. 10 ml
> 14. Solution
> 15. Benzene will be the solvent for this block copolymer (PS-b-PEO)
> 16. MSDS for the individual blocks are available. They are attached
> 17. Will not need to store in SNF
> 18. Purity: unknown
> 19. not sure yet
> 20. not sure yet
> 21. Process Flow: Place Si piece on Headway, spin and flush with
> benzene. Stop spinner, drop a couple of drops of block-copolymer
> (PS-b-PEO) benzene solution and spin again to spin coat. Place Si
> pieces with spin coated samples in an atmosphere saturated with
> benzene (under an overturned beaker for e.g.) for a few hours.

Mary X. Tang, Ph.D.
Stanford Nanofabrication Facility
CIS Room 136, Mail Code 4070
Stanford, CA  94305
mtang at stanford.edu

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