Hello everyone,

I wanted to share another issue on my hands, which has to do with UV curable
dicing tape.

We currently use Adwill D-650 tape from LINTEC which is a low-tac PSA tape and
easily comes off with a 5-10 sec UV exposure. But something very peculiar
happened to my wafers last week. After exposing for 8 sec, the tape has somehow
gotten very tightly bonded (almost "fused") to the back-side of the wafer and is
impossible to take it off. More UV exposure (~ 40 sec) has not helped and
manually trying to remove it from the wafer has only broken the wafer. The tape
just doesnt want to come off.

This fusion to the back-side of wafer is very peculiar and never seen before. I
have checked and ruled out bad or expired tape as a reason, also very long
and/or very strong UV exposure is unlikely to have taken place but is a suspect.
What also remains suspicious is the condition of the back-side of the wafer,
which is bare silicon with through-wafer circular holes, i.e. a lot of area is
taken up by the holes. So a few questions:

 - Any experience or information on UV tape fusing with a silicon surface, so
much that it is impossible to remove?
 - Any information on residues (photoresist etc..) causing UV tape to bond very
aggressively to the wafer after UV exposure?
 - Can holes/topography cause the tape to be strongly bonded to the wafer after
UV exposure?
 - Finally, any ideas on reversing this "fusion" situation?

If anyone has any info or experience with similar situation, please let me know.

Thank you for your time and best regards,
Harshal.