[Fwd: Couple of requests from MEMS Exchange]
mcvittie at snf.stanford.edu
Tue Aug 31 10:48:23 PDT 2004
Regarding item #1, I have never intentionally etched silicon nitride with a
chlorine based process. While Mo etches best in an F based etch, it should etch at
a slower rate in a Cl based etch. I say this because the boiling points of MoF5
and MoCl5 are 35 C and 268C, respectively. Note that the boiling point of TiF4 is
284C and we often etch Ti is SF6 plasmas. If the requestor has a ref for nitride
etching in Cl2, we can look into doing it in the Pquest.
Regarding item #2, we have etched pieces in the Al chamber on the P5000. However,
we have not tried to mount 2 wafers onto 4. The mounting process uses
doublesided carbon tape to attach the pieces and resist to seal the edges. It is a
pain to get off all the tape residue after the etch. I am willing to try other
mounting methods but one does need good thermal contact between the carrier wafer
and pieces to get good etch results.
Mary Tang wrote:
> I think these are questions for Jim... and I've a couple more to add
> regarding logistics...
> 1. I don't believe that Nancy (and please correct me if I'm wrong, Nancy) is
> going to feel comfortable doing this etch on the pquest. Is there any chance
> that you or someone you feel is knowledgeable about the pquest could do this?
> If not, then I suggest that MEMS exchange try to find another site to do
> this. Nancy -- if this could be done here, could we get more info from the
> customer as to what the process requirements are? (I presume that Moly/C are
> pretty robust against Cl, but no idea how much, and it seems they are
> concerned if they want to avoid Fl... Is Moly/C a shiny reflective
> substrate? I mean, can we use the nanospec to measure nitride?)
> 2. Can smaller pieces be mounted on 4" wafers for processing in the P5000? I
> know this has been done, but gather that it's on a case-by-case basis? Are
> carbon dots acceptable? I think you had mentioned that your technical
> contacts at Applied used a certain adhesive... is this something that's been
> investigated here?
> Jim -- what do you think?
> Nancy Latta wrote:
> > Folks,
> > I sent these requests to Spec Mat a week ago. Any progress?
> > ------------------------------------------------------------------------
> > Subject: Couple of requests from MEMS Exchange
> > Date: Wed, 18 Aug 2004 09:36:01 -0700
> > From: Nancy Latta <latta at snf.stanford.edu>
> > To: specmat at snf.stanford.edu
> > Folks,
> > The MEMS Exchange people has asked me to ask about two etch proccesses;
> > 1) They have a customer that has nitride over Moly/carbon on a Si
> > substrate. They want to use a Cl process to etch the nitride and expose
> > the Moly/carbon. Any chance pquest can be used? They do not want to
> > use a flourine process.
> > 2) Another customer wants to etch Al/3%Ti off a SiC substrate. I need
> > to check about the cleanliness of the sputtered metals, but the first
> > problem is that the samples are 2 inch. They are suggesting that we
> > mount them to a 4 in wafer and use p5000.
> > Thanks for your reply,
> > -Nancy
> 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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