[mems-talk] Turning Si surface hydrophobic

[Ned Flanders]

Hi,

Your problem, if I understand correctly, is that of making silica
(thermally oxidized silicon) hydrophobic - and I imagine that just
etching that SiO2 would be out of the question, correct?

Nanostructuring the surface (with a laser beam, for instance) will not
necessarily make it hydrophobic. It may, in fact, make it hydrophilic.
It's somewhat of a long story about why, but suffice it to say that
nano (and micro) structured surface will become more hydrophobic or
more hydrophilic, depending on what they were to begin with.

Also, nanostructured surfaces, espeically glass, tend to adsorb all
sorts of stuff, and the surface tension will change drastically during
just a few months. You should look into coating that silica with some
other material, perhaps with ALD.


cheers

m

On 11/17/09, Miyakawa, Natsuki <Natsuki.Miyakawa at eads.net> wrote:
> Dear all,
>
> Does anyone of you know some methods to turn the surface of thermally oxidized Si hydrophobic (say contact angle > 70°)? The hydrophobisity should be long-term stable (> years @ room temperature), thermally stable (> 1h @ 800-900°C), and chemically stable (esp. under alkaline conditions).
>
>
> Thank you!
>
> Natsuki