request to use PDMS in P5000/gryphon

David_Eaglesham at amat.com David_Eaglesham at amat.com
Mon Jan 16 09:25:26 PST 2006


Mary,

thanks for this response.  Applied Materials is the end customer. 
Fitzgerald Associates are under NDA with us wrt the process flow.  I would 
like you to assume that you are bound by the same confidentiality clause, 
but I would also like to minimise the amount of unneccessary circulation 
of confidential information around the system.  If the full flow needs to 
be disclosed do I assume that you can sign off an NDA making Stanford 
liable for subsequent leakage of IP? 

In the meantime, I would like to proceed down a path of addressing the 
sources of concern for your other users.  I think you have two sources of 
concern with any proposed process: cross-contamination and particulate 
generation.  For contamination purposes Alissa should be able to provide 
you with a data-sheet.  As your earlier emails hint, the particulate issue 
is harder to judge.  Can you give us a baseline D0 that your users are 
expecting so that we can measure particle-adders before and after the 
process and ensure that we re-establish baseline defectivity before we 
release it back to your other users?  Can we do the same for the metal-dep 
step?


David Eaglesham
Managing Director, Advanced Technologies,
Applied Materials

The content of this message is Applied Materials Confidential.  If you are 
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Mary Tang <mtang at stanford.edu> 
01/14/2006 11:13 PM

To
"Alissa M. Fitzgerald" <amf at amfitzgerald.com>
cc
specmat at snf.stanford.edu, David Eaglesham/APPLIED MATERIALS at AMAT
Subject
RE: Re: request to use PDMS in P5000/gryphon






 


Hi Alissa --

Apologies for the many emails.  What would be extremely helpful is a
reasonably detailed process flow, from the point your devices diverge from
"normal" or "accepted" processing through to the point where it becomes
normal/accepted again.  The standard request form appears on the website
(http://snf.stanford.edu/Materials/NewMatProc.html).

In addition, we do expect a certain degree of "due diligence" on the part 
of
the requestor to provide information and insight as to how the process
proposed may affect equipment or the work of others, since the requestor 
is
generally in a better position to understand these issues than SpecMat. 
(Please understand, although it may feel like it, the aim of SpecMat is 
not
to make things difficult, but to ask the obvious questions to help ensure
that someone's new process doesn't end up messing up someone else's work.)

Thus, some general idea of the kinds of experiments or precautions you 
might
take (or would like help with from staff) would be appreciated. Certainly,
SpecMat will have all sorts of suggestions and questions to add --  but
it's like an IRS audit -- although it sounds intidimating, with documents
in order and a clear rationale, there shouldn't be any problem, especially
for experienced, knowledgeable labmembers such as you and your staff.

So, in short, the information requested is:
1.  detailed process flow, with a list of equipment to be used (is there 
any
equipment after P5000 Al etch?), including wet benches.
2.  Purity information, if available.  If not, SpecMat may be able to
suggest either alternative formulations that are electronic grade or
methods of analysis.
3.  Suggestions, comments, concerns you may have for the process flow.

I hope this helps...

Mary

Quoting "Alissa M. Fitzgerald" <amf at amfitzgerald.com>:

> Hello SpecMat,
>
> Regarding my requests, I need to understand what further information is
> required to help move this decision process forward.
>
> I am going to acquire data sheets from Dow on chemical composition as
> requested by Mary.
>
> It seems that the main concern is not PDMS cleanliness, but the
> possibility
> of metal peeling off the PDMS in the chamber and creating particles that
> are
> hard to clean out.  Is this a concern for both the P5000 and the 
Gryphon?
>
> Our priority is for approval to go into the P5000.  As far as the
> Gryphon,
> one option would be for us to do metallization at an outside vendor and
> then
> provide TXRF data to demonstrate it is clean enough to come back in to
> the
> lab.  That way we can dodge the need to get approval for PDMS in 
Gryphon.
>
> What other information is needed to help you make the decision?  How
> shall
> we best gather that information?  Do preliminary tests need to be done??
> If
> so, what are they?  Would it help for me to hunt around for literature
> examples, or get testimonials from other fabs working with this 
material?
> Would you prefer to constrain the thickness of the PDMS allowed in the
> chamber to address metal peeling concerns?
>
> I need to emphasize that we need a decision on whether PDMS can go in 
the
> P5000 *before* we start processing.  I can not start to burn the 
client's
> budget on a certain process path and then be unable to finish that path
> because Spec Mat eventually decided to deny the request.
>
> Please let me know your thoughts.
>
> Best regards,
> Alissa
>
> > -----Original Message-----
> > From: Ed Myers [mailto:edmyers at stanford.edu]
> > Sent: Thursday, January 05, 2006 10:17 AM
> > To: specmat at snf.stanford.edu
> > Cc: Alissa M. Fitzgerald
> > Subject: Fwd: Re: request to use PDMS in P5000/gryphon
> >
> > All,
> >
> > A number of good points have been made during the
> > discussions.  Alissa is correct in her recognition of
> > increased requests for PDMS.  It would benefit our community
> > if SpecMat could categorized PDMS in to one of our
> > contamination classifications.  The question being if it
> > needs to be gold contaminated or we can place it in either
> > Semiclean or SemicleanB, since I don't think Clean is
> > appropriate.  We will need to understand the differences
> > between the many different variations of PDMS.  I'll work
> > with Mary and see what we can find with regards to trace
> > elements and the chemical and thermal stability of the PDMS.
> >
> > The more pressing mater is to respond to Alissa's request.
> > From trace element contamination, Mary's memory seems to
> > indicate Alissa's requests are reasonable.  I am very
> > concerned about whether the process is manufacturable.
> > Various concerns have been expressed over a number of the
> > process steps.  These concerns include the ability to expose
> > 0.7um features due to surface undulations in the PDMS,
> > adhesion of the Al to the PDMS and the potential for the Al
> > to peel at numerous locations including the Gryphon
> > deposition chamber, P5000 and resist strip and the influence
> > of the PDMS on the etch process in the P5000.
> >
> > As a proposal why don't we let Alissa get started on her PDMS
> > casting and lithographic process development.  I would
> > recommend starting with Al deposition from the Innotec.  The
> > Innotec should be the most compatible deposition tool, since
> > the wafer heating will be the lowest.  If she is able to get
> > satisfactory patterns, we will be at a decision node where we
> > either let the Innotec film in to the P5000 or we allow the
> > PDMS in to the Gryphon.
> >
> > Let's get another iteration of comments and try to resolve
> > the request this week.
> >
> > Ed
> >
> >
> >
> >
> > >Hello SpecMat'ers --
> > >
> > >I don't know how hot the gryphon can get, but do think that
> > outgassing
> > >is likely lot less of a problem for PDMS than for photoresist or
> > >polyimide tape, if temperatures remain fairly low -- and if the PDMS
> > >has been sufficiently cured.  Again, I'm not sure of the
> > purity, but I
> > >think the data exists somewhere...
> > >
> > >Mary
> > >
> > >Alissa M. Fitzgerald wrote:
> > >
> > >>Hi Mary, Jim,
> > >>
> > >>Thanks for the info.  Based on your information, and Jim's
> > most recent
> > >>email, does this mean it is approved for use in the P5000?
> > (Also, as
> > >>a side note, based on the number of inquiries I get regarding PDMS,
> > >>SpecMat may want to consider and publicize a general policy with
> > >>regards to this material.  I think it's an important
> > material that is
> > >>gaining popularity in MEMS, esp. with regards to medical
> > and biotech
> > >>applications.)
> > >>
> > >>The process is aggressive and experimental.  Honestly, I am
> > not sure
> > >>this it is going to work, but the customer is interested in
> > trying it
> > >>out. We may need to start with different PDMS thickness,
> > bigger CD's, etc.
> > >>We will need permission to put PDMS in the gryphon, too.
> > We need to
> > >>use aluminum.
> > >>
> > >>Regards,
> > >>Alissa
> > >>
> > >>
> > >>
> > >>>-----Original Message-----
> > >>>From: Mary Tang [mailto:mtang at stanford.edu] Sent:
> > Wednesday, January
> > >>>04,
> > >>>2006 7:47 AM
> > >>>To: Jim McVittie
> > >>>Cc: Alissa M. Fitzgerald; SpecMat at snf.stanford.edu
> > >>>Subject: Re: request to use PDMS in P5000
> > >>>
> > >>>Hi Alissa, Jim --
> > >>>
> > >>>I think I have this information somewhere, from a previous
> > request.
> > >>>As I vageuly recall, PDMS (Dow Corning Sylgard 182 or 184)
> > is based
> > >>>on a Pt-catalyzed reaction, although very little Pt is
> > actually present.
> > >>>Other metals and impurities, such as sulfur, will prevent
> > >>>polymerization.  So, other than the Pt, PDMS is actually
> > pretty clean
> > >>>-- although perhaps not by electronics-grade standards,
> > it's cleaner
> > >>>than your ordinary plastics.  I'll see if I can find the info.  I
> > >>>think that Claudia Richter provided it, so I'll also check
> > with her.
> > >>>
> > >>>Just on a side note, I'm personally less concerned about the
> > >>>potential contamination than the process flow itself
> > (Alissa, perhaps
> > >>>you've got experience or references on this already.) 500
> > microns of
> > >>>PDMS is pretty thick...  It's got a high thermal expansion
> > >>>coefficient, so I'm not entirely sure that you could put
> > 0.5 microns
> > >>>of Al on it without having it peel off due to stress
> > differences, even with an adhesion layer
> > >>>(although having thin lines might help).   I think Claudia
> > or Neville
> > >>>Mehenti may have experience in depositing metals on PDMS
> > in our lab
> > >>>(although I'm pretty sure they would have used metalica or
> > >>>innotec.)  By the way, does your request entail using
> > gryphon for Al
> > >>>deposition?
> > >>>
> > >>>Also, PDMS is a darn good insulator -- I think the Al etch
> > rates and
> > >>>profiles may be very different than they would be on
> > silicon due to
> > >>>differences in plasma behavior (at least, I understand that P5000
> > >>>etching of films on quartz is very different from etching on
> > >>>silicon.) I would suggest that if you have problems, a
> > thinner PDMS
> > >>>layer (tens of microns -- you may have to dilute and spin
> > coat) might help.
> > >>>Constrained PDMS (by adhesion at the Si/PDMS interface)
> > won't expand
> > >>>as much and electronic effects on plasma *might* be reduced.
> > >>>
> > >>>Again, I'll if I still have the purity info, and if not,
> > I'll drop a
> > >>>note to Claudia.  I think that Dow provided this info to
> > Claudia (or
> > >>>whomever it was who gave it to me) so you might try asking them.
> > >>>
> > >>>Mary
> > >>>
> > >>>Jim McVittie wrote:
> > >>>
> > >>>
> > >>>
> > >>>>Hi Alissa,
> > >>>>
> > >>>>During the overetch, the Al etch chamber will be
> > contaminated by the
> > >>>>decomposition products of the PDMS. So the important
> > >>>question what is
> > >>>
> > >>>>in PDMS and is it a problem to other users of the chamber.
> > >>>My concern
> > >>>
> > >>>>is what metals at in PDMS and at what level. Can you find
> > a purity
> > >>>>analysis for PDMS?
> > >>>>
> > >>>>   Thanks, Jim
> > >>>>
> > >>>>"Alissa M. Fitzgerald" wrote:
> > >>>>
> > >>>>
> > >>>>
> > >>>>
> > >>>>>  Part 1.1    Type: Plain Text (text/plain)
> > >>>>>          Encoding: 7bit
> > >>>>>
> > >>>>>
> > >>>>>
> > >>>>
> > >>>>
> > >>>--
> > >>>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
> > >>>
> > >>>
> > >>>
> > >>>
> > >>
> > >>
> > >>
> > >
> > >
> > >--
> > >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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