Mark--

A few notes:

1. Hopefully you don't break vacuum after depositing the seed layer,
as exposure to air oxidizes the seed layer, rendering it useless.

2. The vacuum should be good,
with a pressure in below 9e-7 Torr at the start of evaporation
to avoid oxygen contamination of the film.

3. ~100 A of Ti should be a good seed layer.
Another one to try is ~100 A of Cr.

4. Both the adhesion layer and Ag source should be evaporated awhile
before opening the shutter to allow oxide at the surface to sublimate off
the source
and not contaminate the film.

5. 5-10 um is very thick for an evaporated film.
The film is probably in tensile stress, which varies with deposition
conditions.
My guess is that you are evaporating the Ag at 5-10 A/s or faster, doing it
continuously.
Lowering the evaporation rate will reduce the tensile stress.
Stopping the evaporation periodically, say every 10 min for 5 min,
will allow the wafers to cool. This gives less stress due to
thermal-expansion-rate mismatch.

    --Kirt Williams, Ph.D.    consultant

----- Original Message -----
From: Mark Leonard 
To: 
Sent: Tuesday, August 05, 2003 6:23 AM
Subject: [mems-talk] Ag adhesion


> Hi
>
> We are having a few problems with a e-beam evaporated film of Ag, ~5-10
microns thick. We have tried putting a seed layer of Ti down onto glass and
Si but the Ag film just comes away from the Ti. Can anyone suggest a better
seedlayer onto glass or Si before we deposit the Ag
>
> Many thanks
>
> Mark Leonard
> Electrical, Electronic and Computer Eng,
> Mountbatten Building,
> Heriot Watt University
> Riccarton
> Edinburgh EH14 4AS
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