John,

The primary problem involved with the existence of the buried oxide (BOX) when
it comes to anodic bonding is that, in the standard configuration (i.e.
"silicon" on heated grounding surface, Pyrex on top, negative potential provided
via non-grounded top heating surface - the setup used for an EVG520), the BOX
becomes a resistor in the DC circuit from negative potential to ground.

This will prevent the flow of current, and likewise the flow of Na ions, in the
Pyrex, which is the true driving force of an anodic bond. The best way to defeat
this is if you can get a direct grounding contact to the bonding layer of
silicon.

With regards to the released structures, your best bet is to pattern the glass
with cavities that correspond to the structures.  Otherwise, the electrostatic
force may cause these structures to bow upward and bond with the glass.

Best Regards,
Chad Brubaker

EV Group       invent * innovate * implement
Technology - Tel:  480.727.9635, Fax:  480.727.9700  e-mail:
[email protected], www.EVGroup.com