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Figure 5: a) (left) Chemical resistance; and b) (right) Thermal resistance of SELFA.
using pre-UV. The resin in the adhesive
is chemically bonded and makes a
three-dimensional network by use of the
405nm UV irradiation. This chemical
networking improves the stability of the
adhesive and prevents delamination.
Thermal resistance was evaluated by
observing the delamination behavior
of the wafer/SELFA/glass structure
during and after heating. Figure
5b shows the evaluation scheme
of the thermal resistance and the
appearance of the wafer/SELFA/glass
structure after evaluation. Thermal
resistance was evaluated after pre-UV
irradiation. Two thermal conditions
were prepared as follows: 1) hot plate,
and 2) reflow, which were set up as
simulations of thermal processes,
such as redistribution layer (RDL)
curing and soldering, respectively.
Delamination was not observed after
3 cycles at 220°C x 2hr treatment on
the hot plate in atmosphere. Likewise,
delimitation was not observed after 10
cycles at 260°C x 5min treatment in
the reflow process. Delamination was
Figure 6: a) (top) Appearance of a 20µm-thick wafer; and b) (bottom) Several types of wafers after glass debonding. prevented because outgassing from
an additional planarization process. tape against solvents and conditions SELFA was decreased by using thermal
This TTV value is the same as for the used in wet processing. The weight resistant material for the acrylic resin,
other temporary bonding materials [9]. loss values of SELFA were <2% in any base film, low polarity component, and
No edge crack was observed from the of the conditions we evaluated. This the gas generator, which are stable in
wafer edge. means that the new tape is stable in high temperature, such as <260°C. The
Chemical resistance was evaluated these solvents and can safely support combination test of hot plate and reflow
by measuring the weight loss of SELFA wafers in wet processes. This chemical was also evaluated. Delamination
in several solvents. Figure 5a shows resistance is enabled by chemical was not observed after continuous
the chemical resistance of the new crosslinking of the adhesion layer by treatment of 220°C x 2hr on a hot plate

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