Greetings -

We use the DRIE step to partially etch dicing lines at the same time as
we do our through-wafer etch. Our membranes are only .5 mm x .5 mm. We
determined that in the 90 minutes it takes to etch through the 250
micron thick wafer for the pockets, 8 micron wide dicing lines etch
about half way through the wafer. The dicing lines do not extend to the
edge of the wafer, so after the deep etch and subsequent solvent and O2
ashing clean up steps, we nick the edges of the wafer with a scribe to
start separating the die.

I have also heard of people pre-dicing partway through the wafer with
the dicing saw before the DRIE step.

On one occasion we just blocked the water cooling flow off and directed
the water flow from one of the supply tubes to just flood the wafer
chuck and not spraying directly on the wafer. It's perhaps hard on the
blade, but it did produce some unbroken die.

Good luck,

Jim
On Jul 6, 2004, at 10:00 AM, Mahavir Sanghavi wrote:

> Hi all,
>
> I am looking for a way to dice my silicon wafer with deep etched
> pockets with a micron thick 8 mm by 8 mm silicon nitride membrane on
> one side. I tried to use the wax to fill in the cavities and dice.
> But, I observed the membranes break. Our dicing saw uses a high
> pressure water stream to cool the diamond blade. I would appreciate if
> anyone has any suggestions.
>
> Thanks in advance,
> -Mahavir Sanghavi
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-Jim Beall
303-497-5989