You're right, PECVD is notorious for pinholes.  I've used PECVD SiN as an
intermetal dielectric, but it was 1000nm.  So you might try going thicker.

I also used SiON, and I believe that was successful as closer to 500nm.

If you must use PECVD SiN, you might try higher temperature and lower dep rate
to improve atom mobility at the surface. This might introduce film stress issues
though, so you might need to address that...

Dan

-----Original Message-----
From: [email protected] [mailto:mems-talk-
[email protected]] On Behalf Of nahid vahabi
Sent: Monday, April 29, 2013 3:49 PM
To: [email protected]
Subject: [mems-talk] Silicon Nitride shorting metal layers

Hello all,
I deposit a 250 nm PECVD SiN layer as the dielectric between two gold layers and
the metal layers seem to be short through the nitride each time. I increased the
nitride thickness to 400 nm and still the same. I gathered that PECVD nitride is
quite notorious for the pinholes so I multi-layered the nitride (6 times of 40
nm each) to get rid of pinholes. It worked only on 1 wafer and then the same
problem again. So I appreciate any comments on this and whether you think
changing the dielectric is a good option.

Thank you,
Nahid
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