The mechanism for the effect you are talking about is a gold-silicon eutectic interaction.
The "recipe" for this is not complicated - to get the effect to occur, you will simply
need to heat the substrate to >363ºC (the eutectic point).

At this point, the elevated temperature will cause interdiffusion between silicon and
gold, and when the local proportion of gold and silicon reach the appropriate point, the
combination will liquefy - this liquid will be able to mechanically bind the gold layer to
the silicon layer.

The higher a temperature you use, the broader the range of Si-Au proportions that will
melt.  However, you also run the risk of all of the material becoming a gold-silicon
alloy, or of the gold to diffuse completely into the silicon substrate.

Best Regards,
Chad Brubaker

EV Group
invent * innovate * implement
Senior Process Technology Engineer - Direct: +1 (480) 305 2414, Main: +1 (480) 305 2400
Fax: +1 (480) 305 2401
Cell: +1 (602) 321 6071
E-Mail: C.Brubaker@EVGroup.com, Web: www.EVGroup.com

-----Original Message-----
From: mems-talk-bounces@memsnet.org [mailto:mems-talk-bounces@memsnet.org] On Behalf Of
Moshe
Sent: Saturday, May 10, 2008 11:41 AM
To: mems-talk@memsnet.org
Subject: [mems-talk] Gold evaporation coating on silicon - thermal treatmentfor adhesion

Last week I asked about an adhesion coating achieved
between gold and silicon.

Since then I've heard about a  different way to achieve that.

I talked about thermal treatment so the gold coating
absorb to the silicon, at that way the adhesion obtain
with no third layer.

The general thermal treatment recipe is heating to 400
Celsius degrees for few hours in inert environment.
Has anyone done that before?

Whet is the exact recipe for this treatment ?