hi Annabelle,

we used CHF3 and Ar for etching of SiO2/Si3N4, AZ1518 of 1.8µm in thickness was
used as etch mask; adding SF6 is also okay to increase the etch rate.The
selectivity was around 3-4 ( if SF6 is added the selectivity ´s getting a bit
higher).

regards,Onny
University of Kassel
D-34132 Kassel,Germany

> From: annabelle.gascon@polymtl.ca
> Date: Mon, 11 Jan 2010 11:53:37 -0500
> To: mems-talk@memsnet.org
> Subject: [mems-talk] Silicon nitride and oxide dry etching
>
> Hi,
>
> my sample is composed of 3 layers of 200 nm : low stress silicon nitride /
> annealed silicon oxide / low stress silicon nitride.  I want to etch those
> layers in one step with using reactive ion etching.  The resist I'm using is
> ZEP520A (300nm thick). The chemistry is based on CHF3, CF4 and Ar, but the
> etch rate of SiN and SiO2 is to slow compare to the etch rate of ZEP
> resist.  Does anyone has a recipe for silicon nitride and/or silicon oxide
> etching that is selective to resist ?
>
> Thank you for your help,
>
> Annabelle Gascon
> master student, École Polytechnique de Montréal