Dear All,

I am working on an RIE process to etch silicon oxide and nitride.  I
have 1um thick thermal oxide and 100nm LPCVD nitride on top of it.
I patterned my devices on nitride and metallized them using thermal
evaporation. (3 nm Cr as adhesion layer and 30 nm Au)
I performed RIE to etch all the nitride and approximately half of the
oxide.  At the end when I checked my samples, my patterns were gone.
Somehow RIE etched the Au and Cr as well. Besides the surface of the
oxide after RIE was very rough.

The process I am using:

Gas: pure SF6
RF power: 200 W
Pressure: 0.13 mBar
Flow rate: 40 sccm
Time: 10 minutes.

At the end of this process i etched a total of 650nm. (I suppose 100nm
nitride and 550 nm oxide)

I would appreciate if somebody could comment on the etching of the metals
during this rie process.

Should I have been able to use them as etch mask?

Thank you very much.

Anil