>
> I am looking for a mask material for use with planar etchant consisting
> of hydrofluoric ; nitric; acetic acid ( 8% HF / 75% HNO3 / 17% CH3OOH )
> on [100] Si.  I am trying to define features which are 300 microns deep
> so I need a selectivity x achievable thickness product equal to this.
> Any help would be greatly appreciated.
>
> >Pete
>
>

We etched up to about 200 microns with a Cr/Au on top of an thermal
oxide mask. Sintering at about 300 C improved adhesion. Pinhole problems
are reduced a lot by the underlying oxide. I also guess that a silicon
nitride mask will work.

Alexander Hoelke
Center for Microelecronic Sensors and MEMS
University of Cincinnati