Dear Martin (and all at mems edg)
I am looking for membranes that are 2mm in dia with silicon nitride
membranes of 1 to 2um or preferably a bit thicker at 10um of Si.
The membrane material is not that important, so long as it is
circular and has low damping for use in a travelling wave
piezomotor.
The circularity should be fairly good. However, i am considering
using a compensated KOH etch, as Gleb Vdovin of Delft did to
make 10mm mirrors - this would need some testing and will be
quasi circular.
Many thanks to everyone who has replied, I will pass the ideas on
if anyone else is interested later.

Phil Rayner

On 2 Feb 99, at 10:42, martin.walker@oxinst.co.uk wrote:

From:                   martin.walker@oxinst.co.uk
Date sent:              Tue, 2 Feb 1999 10:42:29 +0000
To:                     p.j.rayner@cranfield.ac.uk
Copies to:              mems-cc@ISI.EDU

> Hi
>
> Can you give us a bit more information?  What size of membrane is required
> (thickness, diameter)?  Do you mean that you are using silicon as the
> support material?  There were some papers a while back in the Journal of
> Micromechanics and Microengineering about silicon nitride membranes.  As I
> recall, these were produced by PECVD of nitride on both sides of a silicon
> wafer, followed by patterning of the nitride on one side, which was then
> used as a mask for KOH etching of the silicon.  The resultant membranes were
> used in experiments on direct-write e-beam patterning, using very high
> acceleration voltages (~400KeV).  The membranes were sufficiently thin to
> avoid any back-scattering of the electrons.  This work was done by Prof.
> Broers and co-workers at Cambridge University Engineering Department.
>
> Hope this helps.
>
> Martin Walker
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> Plasma Technology, Oxford Instruments
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> URL http://www.oxfordplasma.com/
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