bringing outside materials

Mary Tang mtang at
Thu Dec 4 17:05:27 PST 2003

Hi Yiching --

I defer to the other SpecMat members, but would say that your first request
is no problem.  The wafers should be pre-cleaned as usual, but can be
processed in the tylan tubes.

Your second request is no problem, if you plan to use the sts dep tool, as
this is "gold contaminated."  Since tylanbpsg and the balzers are "clean",
the wafers may pose more of a problem there.  In general, wafers processed
in an unqualified outside facility require a TXRF analysis for trace metals
(about $300 from Charles Evans, with 2-3 day turnaround) to ensure that
there is no serious contamination risk before bringing into a "clean" tool
at SNF.  John Shott (please correct me if I'm wrong) indicated that just
this time, that if the wafers are re-cleaned here, that he didn't think it
would be a problem for tylanbpsg (please doublecheck with him.)  I'm not
sure what the status of the balzers at this time is -- please check with Jim
McVittie and Maurice (use of this system is somewhat restricted.)

I'm going to be on vacation for a week -- if you have further questions,
please direct them to Jim or John.


Yiching Liang wrote:

> Hi-
> I am a new industry user at SNF, and I would like to obtain approval to
> bring in the following materials for processing in the SNF.
> 1. new blank wafers: these are 4" double-sided silicon wafers purchased
> from Siltronix. They are semiconductor quality. We would like to use
> them because they have better thickness uniformity than the ones at the
> SNF stock room. They are still sealed in original packaging/container.
> We would like to use them in "clean" equipment (Tylan tubes, drytek2,
> etc.)
> 2. partially processed wafers: these are the same type of wafers as
> above, except they have been through some processing. They were
> processed at the EPFL Center of MicroNanoTechnology in Switzerland
> ( We can provide a complete process log if
> necessary. All protocols have been followed to make sure they are kept
> very clean throughout the process. They have low-stress nitride
> deposited, then RIE etched as etch masks for a KOH etch. After the KOH
> etch, they have been decontaminated in H2O:H2O2:HCl for 30 minutes,
> although the ratio of chemicals (3:2:2) are slightly different from the
> SNF standard of 1:1:1.  After the decontamination, they have been rinsed
> in DI water, then RCA cleaned (H2O:H2O2:NH4OH at 5:1:1/75C/15min, and
> H2O:H2O2:HCl at 6:1:1/75C/15min). And that is the last process the
> wafers saw and have been kept in a closed wafer box since. We would like
> to bring them in to SNF to apply a top SiO2 coating: tylanbpsg, sts
> (PEVCD oxide), and maybe Balzer for sputtered SiO2. This is a one-time
> request (5 wafers max, probably 3) as we are transferring our
> prototyping from EPFL to SNF and would like to start with these wafers
> so that we do not have to introduce too many new variables at once. We
> will gladly follow any further cleaning procedures SNF requires.
> Thanks!
> Yiching
> Coral name: yiching
> --
> Yiching Liang
> R&D Engineer, IonWorks
> Molecular Devices
> 1311 Orleans Dr.
> Sunnyvale, CA 94089
> Direct: 408-548-6011
> Fax: 408-747-0965

Mary X. Tang, Ph.D.
National Nanofabrication Users' Network
Stanford Nanofabrication Facility
CIS Room 136, Mail Code 4070
Stanford, CA  94305
mtang at

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