Chris
Remember that the nanospec software assumes a certain model for
the film it is trying to measure. For example, If it assumes a single
homogeneous weakly absorbing film, and the sample is actually not
homogeneous, and/or has multiple layers, and/or is very absorbing, then
the measurements may not make sense. If the SU-8 is very thick, maybe
the upper part of the film was more exposed than the bottom part, or if
it had multiple reflections, etc., then the film Cauchy coefficients may
not be uniform across the film. It is pure speculation on my part, but
may be worth thinking about if you keep having puzzling results...
Also, you may want to contact Nanometrics customer support.
Regards,
Pierre x286
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Christopher Blanford
Sent: November 4, 2004 03:59
To: General MEMS discussion
Subject: Re: [mems-talk] SU-8 Cauchy coefficients
Lidia -
I did some ellipsometry a couple years back with uncrosslinked SU-8 on
a silicon wafer. The measurements were taken by variable-angle
measurements for a half-dozen or so wavelengths. Here are the Cauchy
parameters I got from the data fitting:
n
A 1.6224
B 1.156E-05
C 6.810E-04
k
A 0
B 0
C 1.171E-05
The fit wasn't excellent, so I would use these values as a guide or a
starting point only.
Chris
On Wednesday, November 3, 2004, at 10:14 pm, Lidija Malic wrote:
> Hi everyone,
> I am trying to measure the thickness of the SU-8 films using NANOSPEC
> tool, and I need to enter the cauchy coefficients for SU-8. Does
> enyone know these, or if anyone has a suggestion of how else I can
> measure the deposited film thickness, since right know the values that
> I have measured do not make any sense.
> Thank you all,
> Lidia
--
Christopher F. Blanford
Inorganic Chemistry Laboratory, South Parks Road, Oxford, OX1 3QR, UK
Phone: +44 (0)1865 282612; Fax: +44 (0)1865 272690
PGP keyID: 8D830BC9 http://pgp.mit.edu/
_______________________________________________
[email protected] mailing list: to unsubscribe or change your list
options, visit http://mail.mems-exchange.org/mailman/listinfo/mems-talk
Hosted by the MEMS Exchange, providers of MEMS processing services.
Visit us at http://www.memsnet.org/
