Hi Markus,

Thanks so much for your response.

I guess you are right although I did not measure the
AFM roughness. My wafers are being ion exchanged in
salt melt at 320 deg C with a Ti mask on it. After in
exchange the mask is stripped off and the wafer is
diced into device size. All the process will cause the
surface roughness, especially because of the mask. But
my device are patterned on the surface of the wafer to
depth about 6 micron. I suspect the further surface
process will ruin the pattern.

My wafer size is about 2cm*2cm, which is thought to be
too small for the EV501 bonder we have in the
cleanroom. Also my substrate is very thick--2mm. It is
an new optical glass especially for in-exchange. It
contains mainly SiO2, Na2O, K2O and ZnO.

Thanks again for all your help.

Best,
Helen

--- "Gabriel, Markus"  wrote:
> Hi Helen,
>
> in most cases room temperature bonding fails or
> results in a poor yield
> because of the wafer roughness. Have you measured
> the AFM roughness? It
> should be in the range of 0.5 nm. An CMP process
> might help to get the
> required roughness.
> Thickness of the wafer can influence the bonding
> result, especially if your
> wafers have structures.
>
> Are you talking about Pyrex glass or quartz when you
> say silicate glass ?
>
> Markus.
>
>
> SUSS MicroTec
> Business Field MEMS
> Markus Gabriel
> Schleissheimer Str. 90
> 85748 Garching
> Germany
> Fon   +49 89 32007 - 313
> Fax   +49 89 32007 - 390
> email [email protected]
> http://www.suss.com/mems
>
>
>
>
> Hi All,
>
> I am trying the glass-glass direct bonding on my
> wafer
> (silicate glass). I
> read about the precess consisting of
>
> (1) hydrphilization: with H2SO4:H2O2, or
> H2O2:NH4OH:H2O
> (2) bonding: light pressaure applied in the center
> of
> the wafer, achieve
>         bonding across the whole wafer at room
> temperature
> (3) annealing: 350 deg C for hours to stabilize the
> bonding
>
> I tried but failed. Does anyone have success in
> glass-glass direct
> bonding? My questions are:
> what is the ratio of the mixture for
> hydrophilization?
> Is that very critical?
> What is the proper pressure to apply?
> Has any one achieve the bonding using EV bonder? Can
> you tell me some more
> about the process? Does the wafer size and thickness
> matter?
>
> Thanks so much for your help.
>
> Best,
> Helen
>
>
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