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