Try plasma bonding.  Use capacitive plasma system to get planarity of
plasma power across wafer.  Lay wafers SiO2 side up on shelf.  Plasma at
about 1 Watt per square inch for 10 minutes Argon.  Place the wafers
together and the disturbed bonds on both surfaces cling to each other.

Bill Moffat

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Nor Hafizah Ngajikin
Sent: Wednesday, June 24, 2009 8:13 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.