Thanks to all for your information and advises. Following is a list of the
replies.
Regards,
Dr. Quanbo Zou
=================================
Dr. Quanbo Zou
MEMS Department
Institute of Microelectronics
11 Science Park Road
Singapore Science Park II
Singapore 117685
Tel: 65-7705905(O) 65-2642113(H)
Fax: 65-7731915
Email: quanbo@ime.org.sg
================================
1)
I saw some diffusion of chromium into gold for a 500degC anneal in air
of Cr/Au electrode structure on a quartz substrate. I didn't do any
measurements on the electrodes as they were all crooked on the edges
after the anneal.
Pedro Banda.
_____________________________________________
Dr. Pedro Banda
Microsystems Technology
Phone :+32 (0)16 281265 IMEC vzw
fax :+32 (0)16 281501 Kapeldreef 75
mailto: Pedro.Banda@imec.be 3001 Heverlee
http://www.imec.be Belgium
_____________________________________________
2)
Dear Zou Quanbo,
How did you cool down the sample after the heat treatment?
Regards,
Sonia.
-----
Sonia Garcia Blanco
Department of EE
University of Glasgow
G3 8PE
Glasgow
3)
US,
When I asked you about Cr/Au a few weeks back, you told me
that it is a rather unstable film. I see that your boys
are also having the same problem that I encountered before
the diffusion problem. Strange enough, heating a chrome/gold
film to about 75 to 100 C will change the resisitivity
and also the stress. I expected a less dramatic change since
it was deposited hot instead of our room temperature deposition.
Anyway, here is an interesting article from a website which
might help. It has something to do with gold recrystallization.
Yan
http://uffc.brl.uiuc.edu/uffc/vigaging91/agingmec.htm
4)
Did you look at it under a microscope? Has the appearance changed?
Often Cr will diffuse along the grain boundaries within Au films. If the
CR oxidizes, then it can spoil the film's low resistance.
Are you required to heat it for 2 hours? That is a very, very long time
for the film to withstand such high heat. Usually, for alloyed contacts,
heating is done only for 1/2 to 4 minutes.
Perry Skeath
SprayChip Systems Corp.
9841 Greenbelt Road, Suite 101
Seabrook MD 20706-6270
(301) 552-5570 voice
(301) 552-5573 fax
5)
Quanbo....
Perhaps there is a huge change in the residual stress within the gold
layer. That is what we have observed to happen with our stuctures
composed of gold/chromium/polysilicon. We believe there is a work
hardening that takes place when this multimoph structue is heated above
100 C or so in temperature. I breifly describe this heat treatment process
in a MEMS 2000 article. We believe this behavior is a crucial limitation
in MEMS reliability and ae currently working on developing a greater
understaning of the phenomenon.
David Miller,
University of Colorado
--------------------------------------------
e-mail: dcm@sprocket.colorado.edu
Web: http://ucsub.Colorado.EDU/~dcm/Home.html
6)
Hi, Quanbo,
We used Pt as a barrier layer. But it is Ti/Pt/Au on Pyrex 7740. We also
performed Si/glass bonding at 380 Centidegree. No problem with that.
Pls keep me posted with all your answers. Thanks.
helen
7)
Dear Quanbo Zou,
During the heat treatment, the gold probably form bigger grains, and
possible unconnected islands. This means that the Crohmium film alone
has to conduct the current from Au-island to Au-island. Which will show
as an increase in the resistance. This is only my guessing I hope it is
helpfull.
Yours sincerely
René Fléron
=================================
Dr. Quanbo Zou
MEMS Department
Institute of Microelectronics
11 Science Park Road
Singapore Science Park II
Singapore 117685
Tel: 65-7705905(O) 65-2642113(H)
Fax: 65-7731915
Email: quanbo@ime.org.sg
================================