We have had the same problem with bonding on top of 100nm SiO2. Our guess
was not only the ultrasonic force, but also discharge in the bonding system.
So make sure that everything is grounded.

Ciao
Daniel


-----Original Message-----
From: mems-talk@memsnet.org On Behalf Of mufei gong
Sent: Montag, 22. März 2010 16:38
To: mems-talk@memsnet.org
Subject: [mems-talk] wire bonder ruined my device

Dear all,

When I use an west bond 7400A Aluminum ultrasonic wirebonder , before I did
the wirebonding, the resistance between the two metal pads was >10 Mohm, but
after I did the wire bonding, the resistance dropped to a few hundred ohm to
a few kohm. the other ends of the two metal pads are separated by a 150 nm
trench of GaAs. This happened to 3 of my devices, and now I only have one
left...

does anyone know what might be the cause of this?