Void detection through silicon with infrared imaging
A bonded wafer pair is inspected between infrared illumination below and a camera above. Transmitted-light contrast reveals bond voids; regions are flagged on a map.
Void area and region positions are written to the wafer record. A non-conforming wafer is held; the bond map is displayed and the decision signal goes to the controller.
- 01 Seat
- 02 Transmission
- 03 Region analysis
- 04 Decide
The wafer pair seats on the open-centre support.
- Void area
- —
- Void regions
- —
Scenes are illustrative simulations; they are not customer references or performance guarantees.
Need
The bond interface lies beneath silicon layers and cannot be inspected directly in visible light. Layer thickness and surface structure create background variation in the transmission image.
Solution approach
SWIR illumination passes from beneath the support ring through a silicon structure with suitable transmission to the camera. Closed contrast regions are located in the background-corrected image; area and bond continuity are assessed by rule-based processing.
Process steps
- 01
Seat
The wafer pair seats on the open-centre support.
- 02
Transmission
Infrared light below transmits to the camera above.
- 03
Region analysis
Closed regions in interface contrast are measured.
- 04
Decide
The void map is recorded and handling permission is determined.
Related applications
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