Method and apparatus for debonding temporarily bonded wafers in wafer-level packaging applications
An apparatus for debonding a wafer from a bonded wafer stack is disclosed. The apparatus includes a flashlamp, a flashlamp control unit, and a wafer debonding unit. A processed wafer can be debonded from a bonded wafer stack by applying light pulses from the flashlamp. The flashlamp is controlled by the flashlamp control unit that includes a capacitor bank, a power supply for charging the capacitor bank, an IGBT-based switching device, and a frequency controller. The wafer debonding unit includes a debonding vacuum table, a wafer feeding robot for conveying the bonded wafer stack to the debonding vacuum table, a set of suction cups for applying vacuum to the bonded wafer stack when light pulses are being emitted by the flashlamp to debond the processed wafer from the bonded wafer stack.
1. An apparatus for debonding a wafer from a bonded wafer stack, said apparatus comprising:
a flashlamp for emitting light pulses to debond a processed wafer from a bonded wafer stack;
a flashlamp control unit for controlling said flashlamp, wherein said flashlamp control unit includes
a capacitor bank;
a power supply for charging said capacitor bank;
an IGBT-based switching device; and
a frequency controller; and
a wafer debonding unit includes:
a debonding vacuum table for holding down said bonded wafer stack;
a wafer feeding robot for transporting said bonded wafer stack to and from said debonding vacuum table; and
a vacuum gripper for removing said carrier from said bonded wafer stack after said light pulses have been emitted by said flashlamp to debond said processed wafer from said bonded wafer stack.
2. The apparatus of claim 1 , wherein said wafer debonding unit further includes a plurality of suction cups.
3. The apparatus of claim 1 , wherein said flashlamp receives charges from said capacitor bank via said IGBT-based switching device while said IGBT-based switching device is being switched on-and-off repeatedly by said frequency controller in order to modulate the flow of said charge from said capacitor bank to said flashlamp, which in turn switches said flashlamp on and off.
4. The apparatus of claim 1 , wherein said capacitor bank is switched by a silicon controlled rectifier (SCR) switching device.
5. The apparatus of claim 1 , wherein said bonded wafer stack includes a wafer attaching to a carrier via a light absorbing layer and an adhesive layer.