Hello,

I have a process with PECVD silicon nitride layer on Al metal pads.

 I would like to pattern the PECVD nitride layer to reveal part of the metal
pads and connect to them electrically by evaporation of another Al layer on top.

The patterning of the PECVD nitride is done by RIE with a chemistry of CHF3.
This etching method is known to leave a residual polymeric layer that might act
as a buffer between the two Al layers resulting in a bad electrical contact or
no contact at all.

Could anyone explain this phenomenon?

What is the nature of the residual layer and how can it be avoided?

Thank you,

Golda