You may be sputtering the copper/nickle a bit with the oxygen being consumed by
the formation of oxides.  I would turn up the pressure to reduce sputtering.  In
our March RIE we use 200-400mTorr for polymer etching.

-Michael


>>> "Hakemi, Ghazal [SAS]"  1/20/2009 10:25 AM >>>
Dear MEMSNet colleagues,

I am currently having an RIE issue.
I am using Cu (copper) hard mask to etch patterned polymer with oxygen gas, but
the etch rate is very low.
When I try to etch the same material with Au mask it works fine (high etch
rates).
The same has happened when using Ni (nickel) hard mask and oxygen gas.

Is this some sort of catalytic reaction? If so, can anybody explain a bit more
in detail (just the principle, no mathematical models).

Thank you.

Ghazal Hakemi