You are right. It takes about 1000 degrees C to make a good fusion bond
between silicon and silicondioxide. You are also absolutely right about the
fracture on cooling. This is caused by differences in thermal expansion
coefficient between silicon and quatrz. The reason it works in BESOI is
due to the small thickness of the dioxide, usually under 1 micron . The
silicon dioxide is grown at similar temperatures, and are in fact stressfree at
this temperature, and under compressive stress at room temperature.

Is it nessesary to use quartz? If you can use borosilicate glass you can
make anodic bonding!

Hope to help :-)

Ole Sondergard
Danfoss A/S
DK-6430 Nordborg
Denmark
e-mail: [email protected]