durusmail: mems-talk: Cr-Au layer detached after baking
Cr-Au layer detached after baking
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Cr-Au layer detached after baking
Jie Zou
2008-06-17
 Hi Rick. Thanks a lot for your comments.

The underside is gold in color indeed. The delamination occurs everywhere
and starts from the edges.

All the deposition was done in vacuum and I used the Filament Evaporation
for the deposition.

I will repeat my process very carefully and check the photoresist issue. But
if it's the photoresist, I cannot explain why this didn't happen in the only
Au or only Cr case.

Do you think the oxide created by O2 plasma may hinder the adhesion although
we have a Cr layer for adhesion?


Thanks again.

All the best,
Jay


On Sun, Jun 15, 2008 at 7:35 PM, Rick Williston 
wrote:

> Jie Zou
>
> You didn't mention where the delamination is occuring or details about your
> deposition technique. If you break vacuum between the first Cr layer and the
> Au deposition, the adhesion could be severely impaired. Gold sticks well to
> most metals but not too well to oxides. Normally I would say look at the
> remaining layer and tell us the colour, but with 3nm this amount of Cr could
> be readily oxidized and be transparent, so I would look at the underside of
> the peeled metal and see if it's gold in colour or not.
>
> Even if you don't break vacuum, if there is a combination of long time
> between depositions, higher than normal pressure in vacuo or higher than
> normal outgassing of your gold target you could cause some semblance of the
> oxidation required (or other contamination).
> A lot of these same issues exist if the delamination can be shown to be
> under the bottom layer of Cr. But in this case the most common candidate is
> the lithography process, it may be inadequate and may have to be
> redeveloped. A thin organic layer of resist could be left if you have the
> wrong combination of either expired resist, improperly stored resist,
> uncalibrated or inadequate exposure, unclean or incorrect mask material,
> expired or improperly stored developer, chemicals, DI water, etc. or the
> part is left too long in air or inadequate storage after developing and
> before deposition.
>
> As you can see, there are lots of ways to go wrong so you have to make sure
> all of the logical candidates are ruled out and if you find any areas for
> improvement, then correct them and try again. A good start would be to
> consult the resist supplier and they can tell you what needs to be done
> correctly for their material to work properly. They are particularly
> sensitive to this as they frequently get blamed for a lot of process miscues
> so they have to have the answers ready.
>
> Good Luck,
> Rick Williston
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