I haven't tried this yet, but 2 interesting references discussing
bonding silicon to SiNx coated silicon are:

"Direct Wafer Bonding with Chemical Mechanical Polishing" by
Cheng-Qun Gui, ISBN 90-36512328, a thesis from the MESA Research
Institute at the Univ. of Twente, Enschede, the Netherlands.

"Wafer Bonding of Silicon Wafers Covered with Various Surface Layers"
Wiegand, et al., Sensors and Actuators 86 (2000) 91-95.

They both seem to indicate that polishing by CMP to reduce surface
roughness to <=0.4 nm RMS is required for bondability.  Gui tested
Si-Si, Si-SiNx, and SiNx-SiO2. The Gui thesis provides great detail
on the polishing processes used. The wafer bonding was a standard
process: preclean in H2SO4(1) + H2O(5)+30% H2O2(1) at 80 deg C for 20
min., followed by "standard wafer cleaning", spin dry, room
temperature contact and anneal 2 hours at 1000 deg C in nitrogen.

It seems that if you could get wafers polished, one of the custom
bonding shops could do a standard bond process for you.

Good Luck,

Jim Beall


>Hi Jamil,
>
>We, in Hymite, are also interested.
>I didn't find an SOI vendor who has the experience to do the bonding
>with SiN.
>
>If you have any interesting links to research works in that direction I
>would very much like to hear about it.
>
>Thanks,
>Lior Shiv, M.Sc. Phys.
>Team Leader
>Hermetic packaging
>
>Hymite A/S
>-----Original Message-----
>From: Jamil El-Ali [mailto:jea@mic.dtu.dk]
>Sent: 5. februar 2003 11:37
>To: General MEMS discussion
>Subject: JO: [mems-talk] Buried silicon nitride
>
>
>Hi All,
>I am interesting in obtaining some SOI wafers with a buried silicon
>nitride layer instead of an oxide layer. I have searched the net and it
>seems like there are some research in progress making such SOI wafers by
>nitrogen implantation, an alternative to the SIMOX process. Does anyone
>know if such SOI wafers are commercial available?
>
>I guess it should also be possible to fabricate buried nitride SOI wafer
>by standard bonding and cleaving, but I have not been able to find any
>information so far.
>
>Regards,
>
>Jamil El-Ali
>
>Jamil El-Ali
>Mikroelektronik centret, MIC


--

- Jim Beall

    beall@boulder.nist.gov
    Voice 303-497-5989
    Fax     303-497-3042
    National Institute of Standards and Technology
    Electromagnetic Technology Division
    325 Broadway, MC 814.03
    Boulder, CO 80305