Mike,

I have experienced problems with freely suspended structures during DRIE, the
passivation/resist often fails resulting in etching away of structures.
Structures suspended on long thin springs are particularly susceptible.
I would also be interested in any publications about this effect.

Here's one reference I have found, which describes a heating effect, but not an
electric field effect:

Sensors & Actuators A 97-98 p. 691 (2002)

Regards,

Martin.


> -----Original Message-----
> From: Michael D Martin [mailto:michael.martin@louisville.edu]
> Sent: 23 June 2006 16:33
> To: mems-talk@memsnet.org
> Subject: Re: [mems-talk] DRIE - Heating Effects & influence on CMOS
>
> Yes, the influence of freely suspended structures in the DRIE (and in
> all plasmas) has a significant affect on the etch geometry. First, the
> suspended structures will heat more redilly in the plasma. Second, the
> local electric field geometry is distorted. The results of
> these affects
> are geometry and material dependant but frequently result in
> sputtering/excess etching around the high field regions.
> Essentially you
> loose selectivity to your masking layer.