Hello Dlee,

For glass to glass direct bonding, there are some requirements beyond what
is needed for anodic bonding. The main factors are:
 1. Low surface microroughness - microroughness RMS of 5 A or less is
typically used as the requirement for Si-Si bonding, glass should be
similar.
 2. Contamination-free surface - wet chemical cleaning can be done before
bonding to prepare the surfaces
 3. Bring wafers together in a controlled manner to prevent trapped air
pockets - Initiate the bond at one spot (either the flat/edge or center).
Manually, this can be done with tweezers, or applying force by hand to one
spot with a pin or rod. In bonding equipment, separation flags can be used
to keep a small gap between the wafers until a force is applied to the wafer
center, initiating the bond, then the flags are removed, allowing the bond
to propagate out to the wafer edge.

A good reference that discusses all the above in more detail is
"Semiconductor Wafer Bonding" by Tong and Gosele.

Best Regards,

Josh Palensky
EV Group, Inc
(602) 437-9492

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Message: 3
From: "Dlee Li" 
To: [email protected]
Date: Thu, 23 May 2002 20:22:58 +0000
Subject: [mems-talk] Glass-Glass thermal bonding
Reply-To: [email protected]

Hi, folks
I am doing Pyrex 7740 glass to glass thermal bonding. I know this will be
tougher compared with silicon to glass anodic bonding. anyone has sucessfull

working experiences? please share these kinds of information with me.

Thanks!
Dlee
research assistant
Mechanical Enigneering Department
University of Texas At Austin
512-2323521 (o)