Hi all,
I think I might have found the answer. I was evaporating at low rates
(~1nm/s) before, I tried this time with 6-7 nm/s and the films look
good. I am also using tugsten coil to heat aluminum clips instead of
using a boat/crucible and this might have helped too (less heat). One
problem with this method is I cant do thicker films than 2 microns
presently but it is mostly an operational issue and can be solved.
Sachin

-----Original Message-----


Subject:
RE: [mems-talk] Aluminum evaporation issues
From:
"David Grove" 
Date:
Mon, 12 Jan 2004 16:57:37 -0800

To:
"General MEMS discussion" 


Have you solved your Al problem yet?

I've been thinking about it some and, though I wouldn't rule out an oxygen
leak, your problem sounds to me more like Al on Si Stranski-Krastanove (S-K)
growth. Basically the strain induced by the Al-Si lattice mismatch
eventually causes the film to switch from a monolayer by monolayer growth
mode to an island growth mode and the surface becomes increasingly rough
with additional Al (aka non-specular). Does your film need to be several
microns thick?

David A. Grove
Research Engineer
Luxel Corp.
www.luxel.com