Dear all
In my experiment, i had 0.1um nitride(PECVD)over 0.7m oxide layer.
 i have done nitride etching using CHF4 plasma in RIE system.After that at
time of oxide etching i have observed a gray colour film, which is not at
all getting etched in oxide etchant (EL18).
i have tried to etch it for a around 30 min (only 9 min are sufficient to
etch a oxide), but still a gray colour layer is present.
is it a oxytride layer. is there any chance of forming a oxynitride film.
if yes how to remove it?

Abhay joshi
Researcher,
university of Pune