[mems-talk] ebeam evaporated metal's properties

[Matthew Coda]

Josh,

A couple things come to mind.

If your substrates substantially heated during the process then I'd say
there's a good chance that you're getting significant interdiffusion
between the Pt or Ti (I don't have a phase diagram in front of me but
I'd bet there's decent solubility in at least the Ti-Pt system), this
can cause a substantial rise in resistivity.

Second if your original model is using bulk resistivity then it assumes
large grain structures which have better (lower) resistance, evaporated
material will often have smaller grains and higher resistances though a
factor of 8 seems a little high for this to be the only reason.

Good luck,
Matt

-----Original Message-----
From: mems-talk-bounces at memsnet.org
[mailto:mems-talk-bounces at memsnet.org] On Behalf Of Josh
Sent: Sunday, July 01, 2007 2:32 AM
To: mems-talk at memsnet.org
Subject: [mems-talk] ebeam evaporated metal's properties

Dear all,

I met a problem of electrical resistivity rising. My measured resistance
of
metal layers (80 nm Pt or Au plus 20 nm Ti as adhesion) was 8 times
higher
than my calculation using literature data. I deposited them using e-beam
evaporator without breaking the vacuum.

My questions are:
(1) Is it normally? Any possible reason(s) for this variation? It is
highly
appreciated if you can provide any publication regarding this issue.
(2) Will the mechanical properties of the metal films, especially
specific
heat change also? what is the trend of possible change?