[labnetwork] Diced Samples Glued to UV Release Tape

[N P VAMSI KRISHNA]

Dear Sa’ad,
I had seen this problem and lost a few good processed wafers.
The reason I found is overexposure to UV. If you are using EVG 620 or any
MJB tool, please expose the wafers for 90-100 mJ/Cm2 only. If you are using
any direct UV bulb, make sure you are exposing for a very brief period of
time and also the bulb or the stage is not very hot.

The best way to recover the dies which are cemented to the tape is by
dipping the whole diced wafer in PG remover solution for about 12 hours.
After that you can remove the tape very easily. However, you might see a
glue stain at the back of the wafer. Try to ash it for about 5 min and your
devices will work.

Thanks & best regards,
vamsi


On Fri, May 17, 2019 at 5:31 AM Paolini, Steven <
spaolini at cns.fas.harvard.edu> wrote:

> Sa’ad,
>
>   Are you applying your tape manually on the hotplate at temperature? If
> so, UV tape adhesive will cross link at higher temperatures than your UV
> source delivers. Another possibility is overexposure. Best way to handle it
> is with a D.O.E using different exposure times. You will find that the
> window between underexposing and overexposing is fairly generous. I do
> suspect the elevated temperature on the hotplate being the root cause if
> that’s what you’re doing.
>
>   I hope this helps,
>
>     Steve (Equipment Dood)
>
>
>
> Steve Paolini
>
> Principal Equipment Engineer
>
> Harvard University Center for Nanoscale Systems
>
> 11 Oxford St.
>
> Cambridge, MA 02138
>
> 617- 496- 9816
>
> spaolini at cns.fas.harvard.edu
>
> www.cns.fas.harvard.edu
>
>
>
> *From:* labnetwork-bounces at mtl.mit.edu <labnetwork-bounces at mtl.mit.edu> *On
> Behalf Of *Hassan, Sa'ad
> *Sent:* Thursday, May 16, 2019 1:40 PM
> *To:* labnetwork at mtl.mit.edu
> *Subject:* [labnetwork] Diced Samples Glued to UV Release Tape
>
>
>
> Hello All,
>
>
>
> As part of the last step of processing, I take wafers (Si and SiC), with
> photoresist on top,  dice them, die expand them on a hotplate at 55 degrees
> Celsius. And finally UV release the tape. I’ve noticed that sporadically,
> rather than the tape losing  adhesion, the opposite happens: the die end up
> cemented to the tape. Has anyone experienced anything like this before?
>
>
>
> Cheers,
>
> Sa’ad
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> labnetwork at mtl.mit.edu
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>


-- 
--
Thanks & Best Regards,
-----------------
*N.P.Vamsi Krishna*
Center for Nano Science and Engineering,
Indian Institute of Science (IISc), Bangalore.
INDIA-560012
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