Fwd: SiO2 nanospheres
mtang at stanford.edu
Tue Jan 12 08:06:15 PST 2010
Hi Carter ---
Sorry about that. To cut down on spam to SpecMat at snf, mail is accepted
only from registered addresses -- so I believe it only from your coral
login at snf or the address you forward to from the SNF computer are
considered legitimate addresses. If you email from anywhere else, it
may be rejected. You can talk to Maureen about setting up your
forwarding email appropriately.
As for your SpecMat request, I'm afraid we do not allow silica
microspheres to be spun up at the headway2 station. Nanoparticle
solutions have a tendency to aerosolize and then fly all over the place
-- and almost permanently stick to surfaces (benchtop, shields,
cassettes, wafers). We do allow latex particles at this station because
these are no worse than resist -- they will come off in sulfuric clean
or plasma ashing and so are not likely to cause lasting damage to other
people's work. However, metal, semiconducting, silica nanoparticles and
nanotubes in solution can potentially do serious damage to others' work.
If you are templating with silica nanospheres, spin coating will result
in only limited local self-assembly. You will need to make sure your
nanospheres are ionized/charged and diluted in nanopure water. If you
need self-assembly over the whole wafer, you might consider talking with
Chingmei Hsu in Yi Cui's lab, as she uses a Langmuir-Blodgett trough to
do whole wafers. Alternatively, you might consider spin-coating latex
spheres instead --- depending on your depth of etch, the selectivity of
resist to silicon is typically around 4:1 and can yield nicely vertical
pillars. Usha Raghuram and Mingliang Zhang have done some
characterization, I believe.
Lastly, we did have another spin coater located outside the lab for
spinning solutions of nanoparticles (like silica) other than latex.
However, this died just before shutdown and we haven't yet tried to
repair or replace it. We will, but it may be some weeks before it is
Carter Lin wrote:
> Hi Mary,
> I was trying to send the following email to specMat but was
> unsuccessful. Can you please tell me who will take care of my material
> Thank you
> ---------- Forwarded message ----------
> From: Carter Lin <carterlin at stanford.edu>
> Date: Mon, Jan 11, 2010 at 4:30 PM
> Subject: SiO2 nanospheres
> To: SpecMat at snf.stanford.edu
> Hi, SNF specMat staff, I'd like to bring the following chemicals into
> our cleanroom please.
> Name: Carter Lin
> Coral login: carterlin
> Phone: 617-259-7988
> Email: carterlin at stanford.edu
> PI: Bianxiao Cui, Chemistry department
> * SiO2 silica nanospheres 250nm diameter in water
> * SiO2 silica nanospheres 400nm diameter in water
> * SiO2 silica nanospheres 550nm diameter in water
> 3590 Route 9, Suite 107
> Cold Spring, NY 10516
> Phone: 1-845-208-7027
> Reason for request:
> To use the nanosphere as etch mask for Si wafers
> Process Flow:
> The nanosphere solution will be spincoated onto Si wafers in the
> headway station, then the Si substrate will be etched in lampoly. The
> nanosphere mask is then removed by HF.
> Amount and form
> All three type of nanospheres are in liquid form, each is 10ml.
> I will be storing my materials in SNF.
> The nanosphere mask will be removed by HF.
> Thank you
> Ziliang Lin / Carter Lin
> Applied Physics, Stanford University
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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