If your Cr deposition is not clean then you'll have adhesion problems.  I
start the Cr heating and before opening the shutter I watch the pressure.
It will rise and then fall back to or below the base pressure.  That way I
know I'vegotten rid of surface contamination and any oxide layer on the Cr
surface.  Only then do I expose the substrate for deposition.  You should
also use chunks of Cr that are as large as your crucible size will allow.
When I started working in this facility they were depositing Cr from a
powder source charge and were having adhesion problems.  With powder you
never get to uncontaminated Cr because you're always exposing surfaces that
have seen atmosphere.  Also remember that the Cr is an adhesion layer and
thicker is not better.  50 to 100 angstroms is plenty.  You'll have much
less adhesion problems if you can deposit the Cr and then deposit the gold
without breaking vacuum.
Milan

-----Original Message-----
From: usual_suspects [mailto:[email protected]]
Sent: Wednesday, October 01, 2003 8:01 PM
To: [email protected]
Subject: [mems-talk] depositing gold layer using e-beam evaporater


currently im having problems getting a good contact
for gold layer with silicon coated with chromium as it
peel off easily.i deposited the gold layer using
e-beam evaporater and it started well but when i tried
to pick up the wafer, the gold layer deposited on it
seems to peel off very easily. Is there any way to
make a better contact for the gold layer and silicon
coated with chromium or will just annealing do the job
of making the gold layer stick better. Thankx

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