Bonded Wafer Interface Scanning for Accurate Seal Path Positioning

The patent applies preliminary action by determining the precise interface position between bonded wafers before the thinning process begins. Using radiation sources and sensors, the system scans through the bonded wafer structure to detect the exact location of the interface between first and second wafers. This advance detection allows for proper seal path formation that prevents gaps from causing damage during subsequent thinning operations, thereby resolving the contradiction between achieving good bonding quality and preventing gap-induced damage.

The patent replaces traditional mechanical or optical microscopy methods with a radiation-based detection system. Radiation sources emit radiation that passes through the bonded wafer structure, and radiation sensors detect the radiation intensity variations. The interface position is determined by identifying the location where radiation intensity changes occur, corresponding to the boundary between different wafer materials. This substitution significantly improves measurement accuracy while maintaining automated operation, resolving the contradiction between process simplicity and manufacturing precision.

The patent implements a multi-functional measurement system where the radiation source and sensor array can detect interface positions at multiple locations simultaneously. The system scans through the bonded wafer structure using radiation that penetrates the material, and sensors detect intensity variations to identify interface positions. This universal approach can determine positions of multiple interfaces (between first and second wafers, and between second and third wafers) using the same radiation-based methodology, improving efficiency and reducing the relative complexity burden compared to performing multiple separate measurements.