Roughness an inherent property of PECVD film, however, it is worse when
deposited over evaporated metal since the metal itself has some roughness.  The
pinholes are also inherent in PECVD film, and the severity is increased by
pinholes in the Au.

You may want to try a reduced deposition rate, lower pressure, lower gas flow,
or reduced power to improve the step coverage of the PECVD.

Dan

-----Original Message-----
From: mems-talk-bounces@memsnet.org [mailto:mems-talk-bounces@memsnet.org] On
Behalf Of Javier Sesé
Sent: Thursday, January 24, 2008 9:42 AM
To: General MEMS discussion
Subject: [mems-talk] PECVD oxide on gold


  We are fabricating a microcoil using two metal layers and PECVD oxide for
electrical insulation. The metal layers are gold deposited using e-beam
evaporation with a few nm of Cromium for adhesion. We found that the PECVD oxide
that grows on top of gold is VERY ROUGH (tipically a roughness of 50nm for a
200nm thick layer). Further it is plenty of pinholes. Does anyone know the
reason?

We use N2O and 5%SiH4 95%He as precursor gases, deposition temperature is
T=300ºC



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