Chandra Mohan Jha
cmjha at stanford.edu
Wed Jun 11 17:09:05 PDT 2008
Yes we are working together on the same project.
From: Mary Tang [mailto:mtang at stanford.edu]
Sent: Wednesday, June 11, 2008 3:50 PM
To: Cathy Chiang; cmjha at stanford.edu
Cc: specmat at snf.stanford.edu; Nancy Latta
Subject: Re: Lithography developer
Hi Cathy --
Are you collaborating by any chance with Chandra Ja in the Kenney Lab?
I understand he is considering etching 1-3 microns of AlN deposited at
Berkeley as well. Could you please coordinate between the two of you to
get more information from your collaborators at Berkeley?
I've contacted Sia Parsa, who's my counterpart at Berkeley. He did not
have a lot of specific information about processing of AlN and so
suggested contacting the researchers who use this film at Berkeley. So,
I think there are a couple of processing issues that you should check
with your Berkeley counterparts:
1. The AlN etches somewhat in basic solutions, such as developer.
However, Sia did not know if wet etch patterning of AlN could be done.
If AlN can be appropriately patterned with wet etching, then this would
be the easiest method. However, you'd have to bias your mask if you
want to define 10 micron lines in 3 micron films.
2. Alternatively, AlN could be plasma etched in the p5000etch metal
chamber, if it can be demonstrated that the AlN is CMOS clean. The
machine at Berkeley is considered by Sia to be CMOS clean, but they do
not have data and processing is allowed on Pt-film coated wafers (which
is not really CMOS clean.) So, Sia could not say if the materials from
this system could be considered clean for SNF. If your counterparts
have any data on trace metal contamination on AlN films deposited in the
Berkeley Microlab AMS, it would be greatly appreciated. If not, then we
would require that a study be made. This could be done either at the
SNL (Rich Chin or Ann Marshal would be the contacts there) or at Evans
Analytical Group, a commercial provider of analytical services.
Typically, TXRF is used for contamination studies on surfaces, but a
bulk film technique might be more appropriate in this case. Usually,
these techniques will detect a spectrum of metal contaminants -- the
contaminants of interest would likely be Pt (since it is introduced to
the system) and any likely contaminants from the chamber or deposition
tool itself. Please check out the Evans Analytical website, which has a
lot of good information about different analytical methods.
Please work with Chandra to find out this information from your
collaborators. It would also be helpful to know if you plan to pattern
your wafers here at SNF or at Berkeley. If you want to use the CD-30
developer here, you should check the compatibility with the resist you
plan used here.
I suggest that you might consider coming to the next Process Clinic --
staff and SpecMat members will be on hand to help with processing and
materials questions. This will be 2-4 pm next Monday afternoon, in the
open cubicle area next to Maureen's office.
Cathy Chiang wrote:
> Hi Mary,
> Sorry but one more bother, do you know with what machine we can do AlN
> etch in SNF?
> Thank you very much,
> Quoting Cathy Chiang <cfchiang at stanford.edu>:
>> Hi Mary,
>> Thank you for the fast response. Yes, we collaborate with Berkeley and
>> will deposit AlN from their microlab. They use Shipley CD-30 to
>> pattern the feature. In our application, the thickness of AlN is
>> around 1-3 microns. And the feature size will be >200 microns with a
>> minimum line width >10 microns. Attached is the MSDS of Shipley CD-30.
>> Sorry that I have not got an updated version of the MSDS from the
>> company sales representative.
>> Thank you sincerely,
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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