Does anyone have actual etch rate data for various recipes?
I don't have numbers available right now, but my past
experience using the ASE process in STS etchers is that
nitride and Si etch at essentially the same rate, while any
oxide is much much slower.  In fairness, the nitride films
in my experiments were always pretty thin, and I never tried
very hard to calculate an exact etch rate for them.  My
point however is that nitride is not a good stopping layer,
nor will exposed nitride features survive very well, in an
SF6 silicon etch.

BTW- the rate of oxides is highly dependent on the
densification, so CVD oxide etches faster than thermal oxide
for example.

Hope these comments help...

Marc Straub
Solidus Technologies, Inc.
Colorado Springs, CO  USA


-----Original Message-----
From: Brent Garber [mailto:garber@engr.uconn.edu]
Sent: Friday, April 02, 2004 2:59 PM
To: General MEMS discussion
Subject: Re: [mems-talk] SF6 isotropic etch


Yao,

The Si02 and Si3N4 will etch much, much, slower than the Si
in SF6, but uit will
etch them all.

Brent

Qing Yao wrote:

> Hi,
>
> I need to do SF6 isotropic dry etch of single crystal Si.
I was wondering if
> Silicon Nitride and Silicon Dioxide will also be etched in
this process. If
> so, does SF6 has good selectivity to them? I heard that
people can use
> Silicon Nitride or Silicon Dioxide as mask in BOSCH
process (DRIE). So I
> guess SF6 does have good selectivity to them. But I am not
sure. Please let
> me know if you have any information about this. Thanks!
>
> Best Regards,
>
> Qing Yao
> ___________________
> M&IE @ UIUC
>
> _______________________________________________
> MEMS-talk@memsnet.org mailing list: to unsubscribe or
change your list
> options, visit
http://mail.mems-exchange.org/mailman/listinfo/mems-talk
> Hosted by the MEMS Exchange, providers of MEMS processing
services.
> Visit us at http://www.memsnet.org/