Moiré-Based Nanoprecision Bonding Alignment System for Hybrid Integration

Wafer bonding alignment is one of the most important manufacturing processes in 3D integration, especially in high-density interconnection. A nanoprecision alignment system based on moiré fringes suitable for both optical transparent or opaque advanced wafers is proposed and named MoiréView. Moiré fringes are sensitive to gratings superposition status and beneficial for improving the accuracy into the nanoscale. The alignment system, which contains optical part, mechanical handling part, and signal process part, is developed to align bonding wafers without transparency requirements. The alignment operation includes optical system calibration, wafer position recognition, and wafer alignment. Using the moiré-based alignment method, we believe the system developed has sufficient potential to be a versatile and efficient method for high-density new-generation 3D integration.