Analysis of Post-Bonding Crack-Induced Double Cantilever Bending (PDC-DCB) Method for Hybrid Bonding Strength Measurement

The quantitative measurement of bonding strength in hybrid bonding (HB) is an indispensable metrology for process and reliability evaluation. Methods currently used such as blade insertion (BI) and double cantilever bending (DCB) have suffered from a wafer edge-only capability and limited repeatability due to a lack of precise interface crack initiation. This study reports an improved DCB method by introducing a post-bonding crack (PBC) to avoid undesired cracking in a wafer substrate during DCB propagation. This method is firstly applied to measure the bonding strength of SiCN-SiCN under O₂ and N₂ activation. The test data shows that the bonding strengths are 3.53 J/m² and 2.93 J/m² with the deviations less than 3.84% and 1.84%. Based on the experimental data, finite element analysis (FEA) methods are used to simulate the crack propagation process of the PBC-DCB method. The results show that the bonding interface crack propagation can be accurately described by an optimized viscoelastic exponential model. The accuracy of simulation increased from 16.06% to 1.77%. Finally, it was found that the PBC-DCB method can solve the issue in conventional DCB where the crack may be initiated away from the target interface, therefore measuring the wrong interface. This advantage is further validated by simulations considering the offset of the PBC away from the bonding interface.