Hi,

I have a possible solution to this but I offer no guarantees.

Deposit/grow your SiO2.

Use a Lift-off process to define your pattern and deposit the Cr/Au.  Remove the
unwanted metal in the lift-off to leave the pattern you require in the Cr/Au.

Then use the metal layer as a hard mask to dry etch the SiO2.  It may be
necessary to deposit slightly more Au than you require for your device as some
of it may be removed during the etch.  It should be possible to etch one micron
of SiO2 without producing too much underetch.

One advantage of this method is that you will have a self-aligned structure.
The SiO2 will always match your metal pattern.  If the process deposition is
early in the process when there is not much  topography on the wafers it should
be possible to get good results.  Another advantage is that you require only one
lithography stage.


It may also be possible to use a wet or dry etch to pattern the Cr/Au
satisfactorily.  The resist could then be left on to give some protection to the
metal during the SIO2 etch.


Hope it helps



Andy Scholes, Ph.D.
Utvecklingsingenjör
ACREO AB
SE 164 40 Kista
Sweden

www.acreo.se