Brad,

        Great input.  I was not quite able to bring the CV dot testing
to mind.  To qualify the silicon dioxide we used as a gate in MOS
devices we used CV dots.. There has to be stacks of technical papers on
Capacitance Voltage dots as testers for oxide integrity.

Bill Moffat

________________________________

From: mems-talk-bounces@memsnet.org on behalf of Brad Cantos
Sent: Sat 9/20/2008 9:08 AM
To: General MEMS discussion
Subject: Re: [mems-talk] how to test porosity of deposited layer ?

Kamlesh,

The type of test is related to the use of the film.  For example, if you are
making capacitors and want to test the quality of the film as a dielectric
layer, you might build the capacitors and stress test them.  If you are
interested in the film as a passivation layer and the quantity of pinholes
is important, one simple way is to immerse the substrate in a selective
etchant that will etch the underlying substrate but not the SiO2.  It may
take some time to etch, but pinholes will be fairly obvious when viewing in
an optical microscope.  This isn't a direct measure of porosity but may give
you some qualitative insight into the film.

Brad Cantos