[Fwd: Re: Lampoly recipe for silicon-rich nitride]

Mary Tang mtang at stanford.edu
Thu Sep 25 11:43:11 PDT 2008


Hi all --

This material was approved for etch on the lampoly ("trace" Er.)  OK for 
amtetcher as well?

Mary

-------- Original Message --------
Subject: 	Re: Lampoly recipe for silicon-rich nitride
Date: 	Thu, 25 Sep 2008 10:06:08 -0700
From: 	Aaron Hryciw <ahryciw at gmail.com>
To: 	Mary Tang <mtang at stanford.edu>
References: 
<4d36fb940809241236h456c4846r6385a3de53e53196 at mail.gmail.com> 
<Pine.LNX.4.44.0809242150030.25336-100000 at cis.Stanford.EDU>



Hi Mary –

So, Jim is suggesting that AMT would be best for this (NF3 via etch).  
My SRN etch-test wafers will be "clean," but since the actual device 
film I'll want to etch will contain a little less than 1% erbium (which 
is a non-standard metal), does this mean that AMT is completely out of 
the picture?  Is there some sort of decontamination procedure I could do 
after my etch, which would allow me to use this tool for the Er-doped films?

Cheers!

 – Aaron



On Wed, Sep 24, 2008 at 10:00 PM, Jim McVittie 
<mcvittie at cis.stanford.edu <mailto:mcvittie at cis.stanford.edu>> wrote:

    Aaron,

    Ok, since you do not care about how much Si you etch, the Lam is not
    automatically off the table. But I still would not go with the Lam since
    really do not have a nitride etch process in the Lam. If I was you, I
    would go with the P5000 since it is quick and uniform. The std oxide
    etch
    process process will work fine or you can use a nitride process. If you
    already know the AMT but not the P5000, then go with the AMT. THe
    via etch
    shouls work fine. I would timed etch since you have non-critical
    needs. If
    really want to use endpoint, I can probably it up for you,

           Jim

    On Wed, 24 Sep 2008, Aaron Hryciw wrote:

     > Hi Mary, Jim –
     >
     > The purpose of this etch will be to define silicon-rich nitride (SRN)
     > microdisks, the pillars of which will afterwards be defined by a
    TMAH etch.
     > As such, my tolerance for etching into the underlying Si is not too
     > critical, just so long as I punch through the SRN.  To answer your
     > questions:
     >
     > 1. What kind of film are you etching exactly? (Target composition and
     > > thickness.)
     > >
     >
     > The final process wafers will be:  1) SRN, ~49% Si, 51% N, and 2)
    SRN doped
     > with up to 1% Er.  In both cases, the film will be ~50 nm thick.
     >
     > 2. What feature size and what is your masking material (thickness
    and type
     > > of resist, whether there's a sacrificial mask.)
     > >
     >
     > For the first experiments, the features will be widely-spaced
    circles,
     > ranging from ~1 to 100 um in diameter.  The intended masking
    material is
     > Shipley 3612, patterned using the ASML (1 um thick? 1.6 um?
     with/without UV
     > cure? --> will test).  If necessary, however, a sacrificial mask
    (Cr?) could
     > certainly be used.
     >
     >
     > > 3. What are you stopping on and what is your tolerance for
    etching into
     > > this?
     > >
     >
     > I will be stopping on Si.  As mentioned above, so long as I
    manage to punch
     > through the SRN, the tolerance for etching into the underlying Si
    substrate
     > is quite large; for instance, I imagine I could etch a micron
    into the Si
     > without any problem.  Presumably, since the etch rate of Si
    should be much
     > larger than SRN, it should be detectable as a spike in Si-related
    byproducts
     > in the endpoint detection plots, correct?
     >
     > 4. What are your uniformity (and selectivity) requirements?
     > >
     >
     > I will have several dies on the wafer, each with the 1 to 100 um
    diameter
     > (roughly equally on a logarithmic scale) disks on them, and for the
     > experiments, I will be looking at single disks, so uniformity
    across the
     > wafer will also not be too much of an issue.  Even 10% or so
    should be
     > fine.  Since there is only a single masking/etching step, the
    only material
     > being etched is the SRN, so selectivity isn't really a problem,
    except
     > insofar as I can tell when I've reached the Si.  If endpoint
    detection is
     > not possible, and I have to go with a timed etch (after
    characterising the
     > process with test wafers), so be it!
     >
     > 5. I'm presuming that your substrates are 100 mm silicon rounds
    of standard
     > > thickness?
     > >
     >
     > Correct.
     >
     > Thanks again to both of you for all your help.
     >
     > Cheers!
     >
     >  – Aaron
     >
     >
     > On Wed, Sep 24, 2008 at 10:55 AM, Mary Tang <mtang at stanford.edu
    <mailto:mtang at stanford.edu>> wrote:
     >
     > > Hi Aaron --
     > >
     > > Jim is absolutely right -- my apologies, I think I confused
    yours with
     > > another project and didn't realize you were stopping on
    silicon. I don't
     > > know about this machine specifically, but silicon etches about
    an order of
     > > magnitude faster with SF6 than silicon nitride (stoichiometric).
     > >
     > > As I neglected to perform due diligence before by asking you a
    bunch of
     > > questions, I'm going to ask right now (and no doubt, Jim will
    have more.)
     > >
     > > 1. What kind of film are you etching exactly? (Target
    composition and
     > > thickness.)
     > > 2. What feature size and what is your masking material
    (thickness and type
     > > of resist, whether there's a sacrificial mask.)
     > > 3. What are you stopping on and what is your tolerance for
    etching into
     > > this?
     > > 4. What are your uniformity (and selectivity) requirements?
     > > 5. I'm presuming that your substrates are 100 mm silicon rounds
    of standard
     > > thickness?
     > >
     > > Again, sorry about that --
     > >
     > > Mary
     > >
     > >
     > > Jim McVittie wrote:
     > >
     > >> Hi,
     > >>
     > >> I just sent you a copy of a note I sent Mary. We never got
    great Nitride
     > >> results in our Lam. The other tools gave better results so we
    never push
     > >> the Lam to get a good niride process. I would NOT use the Lam
    to stop on
     > >> Si.  It is a Si etcher and not optimized to stop on Si. You
    need to use an
     > >> oxide etcher which has the polymer deposition which will slow
    down the
     > >> etch rate when you hit Si. SF6 is not a good chice since it
    loves to etch
     > >> etch Si. I can help you if you want to use the AMT or P5000.
     > >>
     > >>        Jim
     > >>
     > >>
     > >> On Wed, 24 Sep 2008, Aaron Hryciw wrote:
     > >>
     > >>
     > >>
     > >>> Hi Jim –
     > >>>
     > >>> I need an anisotropic etch recipe for silicon-rich nitride (SRN);
     > >>> ultimately, I'll need to etch through a 350-nm-thick SRN
    film, stopping
     > >>> on
     > >>> Si.  Mary suggested using the lampoly tool with a SF6-based
    chemistry,
     > >>> and
     > >>> said that you would likely be able to offer some advice as
    how best to
     > >>> proceed.  She said that recipe 99 (a "clean" recipe with SF6
    and Cl with
     > >>> no
     > >>> bias, for general chamber cleaning) might be a good place to
    start, and
     > >>> she
     > >>> also sent me a link to the standard nitride recipe (SF6 and
    He) for
     > >>> etching
     > >>> on the Lam1 tool in Berkeley's Microlab (although this is quite a
     > >>> different
     > >>> tool compared to SNF's).
     > >>>
     > >>> I'm going to ask Maurice for some dummy low-stress nitride
    (which are
     > >>> apparently quite Si-rich) to use as etch-test wafers, and I
    was hoping
     > >>> you
     > >>> could give me a few lampoly "rules of thumb" (pressures, RF
    power, bias,
     > >>> etc.) for anisotropic SF6-based etching which I could use as
    a starting
     > >>> point.  Many thanks!
     > >>>
     > >>> Cheers!
     > >>>
     > >>>  – Aaron
     > >>>
     > >>>
     > >>>
     > >>>
     > >>>
     > >>
     > >>
     > >>
     > >
     > >
     > > --
     > > Mary X. Tang, Ph.D.
     > > Stanford Nanofabrication Facility
     > > CIS Room 136, Mail Code 4070
     > > Stanford, CA  94305
     > > (650)723-9980
     > > mtang at stanford.edu <mailto:mtang at stanford.edu>
     > > http://snf.stanford.edu
     > >
     > >
     >
     >
     >

    --
    --------------------------------------------------------------
    Jim McVittie, Ph.D.                     Senior Research Scientist
    Allen Center for Integrated Systems     Electrical Engineering
    Stanford University                     jmcvittie at stanford.edu
    <mailto:jmcvittie at stanford.edu>
    Rm. 336, 330 Serra Mall                 Fax: (650) 723-4659
    Stanford, CA 94305-4075                 Tel: (650) 725-3640





-- 
Aaron Hryciw
Postdoctoral Scholar
Geballe Laboratory for Advanced Materials
Stanford University
476 Lomita Mall (04-490)
McCullough Building, Rm. 325
Stanford, CA 94305-4045

Tel.: (650) 723-5840
Fax.: (650) 736-1984

-- 
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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