request to use PDMS in P5000/gryphon

Mary Tang mtang at stanford.edu
Mon Jan 16 11:52:01 PST 2006


Hi again --

After thinking a bit more, I think I'll email Alissa directly with my 
concerns and let her handle it with her client.  I do believe we should 
respect that contractor-client relationship...

M

Mary Tang wrote:

> Hi SpecMat'ers --
>
> First, I think this fellow doesn't understand the intellectual 
> property policies at SNF (it appears on the Agreement Form which I 
> presume he signed or is thinking of signing.)  Second, I can't help 
> but think that there must be a few sketchy issues with their process 
> flow, or they wouldn't want this done here (maybe I'm naive, but don't 
> they have P5000 Al etchers at Applied?)
>
> Sorry, this whole thing annoys me, because I can't help but think that 
> Alissa and her crew should know this (although, admittedly, I don't 
> think I've ever seen a SpecMat request from AMF & Assoc., so perhaps 
> not?)  Also, we've already provided lots of information about 
> processing PDMS to AMF so it might be nice if they read it through and 
> thought about it.  I'd like craft a polite response, and will send it 
> around for your approval/disapproval, OK?
>
> Thanks,
>
> Mary
>
> David_Eaglesham at amat.com wrote:
>
>>
>> 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 not the intended recipient and have received this message in 
>> error, any use or distribution is prohibited.
>>
>>
>>
>>     
>>
>>
>> *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
>> > > >
>> > >
>> > >
>> > >
>> > >
>> >
>> >
>> >
>>
>>
>
>


-- 
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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