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Table 2: Foil release vs. debonding temperature
and time parameter setting [3].
Results
Warpage improvement has been
observed in all the samples processed.
The significant observations are as
observed in Figure 6 and Table 3:
• For contactless transport, increasing
temperature from the warpage adjust
temperature leads to increased
improvement on the warpage.
Figure 3: Heat map of the 300mm chucks at 150ºC, 185ºC, 200ºC, and 240ºC. • The pick-and-place method shows
reduced impact on warpage at higher
temperatures and thinner wafers.

Table 1: Initial warpage on wafers at different Figure 4: Process flow of the experimentation.
temperatures.
Parameters. The experimentation will
have three parameters: 1) Warpage adjust Table 3: Warpage impact of the experimentation.
temperature: 150ºC, 170ºC and 200ºC;
2) Wafer thickness; and the 3) Wafer
handling method. The handling method It was also observed that the heat
is the technique used to transport the dissipation is very uniform during
wafer to different chucks. Wafer transport contactless transport from hot to
is critical in three areas of processing as cool chucks, compared to a pick-
shown in Figure 4. and-place method. In pick-and-place,
Contactless transport, as the name the end effector affecting the wafer
itself implies, is transportation without temperature before cooling is very
contact. Examples of this method are evident in Figure 7.
the Bernoulli handling and AirCushion
system. For this experiment, the Summary
contactless transport utilizes ERS’ The chip-first type FO can benefit from
AirCushion and TriTemp slide system. thermal treatment to reduce warpage. A
For pick-and-place, a conventional end- Figure 5: Simple end-effector for semiconductor contactless handling method during the
effector was utilized (see Figure 5). automated machines. debonding and warpage adjustment process

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36 Chip Scale Review January • February • 2020 [ChipScaleReview.com]