Hafizah,

I agree with the plasma treatment approach. Oxygen plasma can also be used. Two
things to consider. First, the bond area needs to be flat so you will need to
CMP if you have metal runners under the bond surface. Second, the optimum plasma
process window for oxygen plasma SiO2 bonding is more narrow than for bare
silicon. You may need to experiment a little with process power and time.

Dan Chilcott

-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of Nor Hafizah Ngajikin
Sent: Wednesday, June 24, 2009 11:13 PM
To: [email protected]
Subject: [mems-talk] Sio2 SiO2 wafer bonding

Hi,

I tried to bond SiO2 SiO2 at 300o celcius with 1 bar pressure. It sticks for two
days. After that, the bonding seems weaken and that two wafer start to separate.

I have CrAu film below the SiO2 in both wafer. That is the reason why i need to
lower the temperature.

Could anyone suggest the suitable method to increase the bonding strengh.

Thanks

hafizah