Robust Measurement of Bonding Strength for Wafer-to-Wafer 3D Integration

3D integration with wafer-to-wafer bonding is essential for advanced node devices to achieve high performance and reduction of power consumption. The bonding strength is a parameter to assure successive wafer bonding processes. However, there is no standardized measurement method for wafer bonding strength. The double cantilever beam method has been comprehensively used to measure bonding energy. The measurement is, however, typically taken manually at ambient condition, which causes significant variations due to water stress corrosion. In this study, the measurement in an inert atmosphere has been assessed. The propagation of the delamination has been suppressed when the measurement was conducted in an anhydrous atmosphere. In addition, the equipment with precise blade insertion has been used for eliminating manual operation. It has been unveiled that the delamination length varied depending on the measurement location due to the Young’s modulus of the measurement location at the wafer. These fundamental analyses give us insight into the most robust measurement method for wafer bonding strength.