Debjani,

We have succesfully bonded Pyrex to both sides of single crystal silicon.
We use the following simple method with double-side-polished silicon:

Anodic Bonding:
Positive polarity on Silicon
Negative Polarity on Pyrex
Heat both materials to 450 degC then apply from 500 to 1000 Vdc
(Our bonding is done in the normal air environment of a cleanroom)

(1) Bond first Pyrex plate to Silicon.
(2) After allowing the structure to cool, it is dipped in
    buffered HF (BHF) for a few minutes to remove any new oxide layer.
(2) Flip bonded Si/Py over and place second Pyrex plate over the
    silicon, being sure to allow an exposed silicon surface for
    the next step.
(3) Place the positive electrode on the exposed silicon, and the
    negative electrode on the Pyrex, then bond as usual.

This has worked well for us.  We've noticed that the thinner the Pyrex the
harder it is for bonding to occur.

Good luck.

Nigel Rudra Sharma.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
email: [email protected]
voice: 206-685-6878
web site: http://lettuce.me.washington.edu/~micropump/
MicroFluidics Laboratory
University of Washington, Seattle, USA.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

On Mon, 12 Jul 1999, Debjani Pal wrote:

> Date: Mon, 12 Jul 1999 11:57:21 +0530 (IST:)
> From: Debjani Pal 
> To: [email protected]
> Subject: Can you help me?
>
>
> Hi,
>
> I am a graduate student, who has just started work on MEMS.
> My work needs bonding glass anodically to both sides of
> single-crystal silicon.We bonded glass to one side of the wafer and then
> tried bonding glass to the other side as well.
> But it does not work in spite of doubling the applied voltage.
> Any suggestions/references about this will be most welcome.
>
> Debjani
>
> Research Scholar (Semiconductor Group)
> Department of Physics                 Ph: (080)309-2316
> Indian Institute of Science           Fax:(080)334-1683
> Bangalore - 560012
>
>
>