Hi Nicolas,

We have tried various methods of mounting samples to handling wafers for Bosch
processing and cryo.  The best method that we have found is using Shipley
HPR504 Photoresist to cover the handling wafer with a uniform 1 micron film
and then to take the sample and apply a uniform amount of IPA with a q-tip to
the back side.  You want just enough IPA as to cover the back side completely
but not enough to drip (you'll have to work fast to avoid evaporation).  Then
place the sample immediately onto the centre of the handling wafer and press
firmly to ensure good contact (2 pairs of tweezers seems to work well).  Then
The wafer and sample are baked at atmosphere (a vacuum oven will cause
bubbles in the resist) at 115 Celsius for at least 10 minutes.  This process
for 1/4 wafer SOI on 100mm handling wafers for Bosch processing has produced
identical results as to using full 100mm SOI wafers.  This process also
stands up to Cryo and at our current development with the Cryo process seems
to be producing the same results as full wafers (we are still investigating
this process to be able to say for sure).  As a note for Bosch processing if
possible make sure that the handling wafer has the same structure as the mask
of your sample to ensure repeatability.

Feel free to contact me directly if you want to discuss this further.
--
Shane McColman
Research Professional
NanoFab, University of Alberta
W 1-028 ECERF Building
Edmonton AB, Canada, T6G 2V4


On September 16, 2004 11:35 am, Nicolas Duarte wrote:
> This is a follow up question to a question asked a long time ago (I just
> joined the list).
> Back in February, Stefan mentioned that he used Aremco Crystal Bond 555 for
> bonding two wafers for use in DRIE for through wafer etches.  However when
> contacting Aremco they told me that the Crystal Bond series has no thermal
> conductivity.  A high thermal conductivity between the wafers is important
> for DRIE to achieve high anisotropy since a cool wafer temperature (20 deg
> C) has to be maintained.  Our machine also has the ability to do cryo
> etching, so the wafer must be at -110 deg C, making high thermal
> conductivity even more important.
>
> I have heard of a high thermal conductivity epoxy that is disolvable in
> acetone, however I can't seem to find out exactly what it is.  Any
> suggestions?
>
> Nicolas Duarte
>
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