The AW300™ Series is a high-capacity, high throughput automated C-SAM® system designed to deliver maximum sensitivity for the evaluation of bonded wafers in applications such as SOI, MEMS and others. Since the materials used in these applications are very transparent to ultrasound, Sonoscan uses proprietary high acoustic frequency lenses, which are designed in-house, to obtain the most detailed images. The AW300 Series can detect voids smaller than 5 microns in diameter between two wafers and delamination with the separation between the wafers as thin as 200 Angstroms.
The system is designed to handle wafers bonded by virtually any method, including direct fusion, anodic, glass frit and epoxy bonding. For direct bond techniques, users of the system have found that yields can be significantly improved by inspecting at three production stages—after initial bonding by Van der Waals forces, after annealing and after thinning.
The AW300 Series delivers fully automated inspection. 300mm wafers are loaded via an EFEM with up to two wafer carrier loadports. A robotic arm transfers the wafer first to the aligner and then to one of the two vacuum assisted scan stages for acoustic inspection. The entire wafer area is scanned using Sonoscan’s proprietary Waterfall Transducer™, which provides non-immersion scanning and reduces the risks of contamination and false bond indications. If inspection is performed after metallization has been applied, the acoustic image can be overlaid onto a wafer map. This method relates void, bond and other defects to the individual die.
After completing the scan of each bonded wafer pair, the wafer is placed in the wafer dryer to remove excess water. While drying, Sonoscan’s automated analysis software analyzes the data. Based on your chosen accept/reject criteria, the bonded wafer is either categorized as “acceptable” or “rejected.” At the same time this is occurring, thanks to the staging areas, a second wafer pair is already being processed in the same way. By minimizing time between scans, the AW300 Series helps maximize throughput.
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