Post-Bonding Crack-Induced Di-Cantilever Bending (PBC-DCB): A Novel Method for Quantitative Evaluation of Bonding Strength for Wafer-to-Wafer and Die-to-Wafer Hybrid Bonding

To address the challenge of characterizing bonding strength in hybrid bonding, this paper proposes a method based on post-bonding crack-induced di-cantilever bending (PBC-DCB). The commonly used industrial blade insertion (BI) method only measures the edge strength of wafer-to-wafer samples via bevel geometry, failing to characterize the wafer center or die-to-wafer samples (as they lack a bevel) and exhibiting limited accuracy due to irregular crack edges. This study develops a di-cantilever beam test initiated by a specially prepared post-bonding notch. By deriving the relationship between load-displacement and bonding strength based on fracture mechanics and optimizing sample preparation and testing parameters, quantitative measurement of interface fracture strength is achieved. Experimental results show the method has a deviation < 5% from BI with better repeatability, verifying its reliability. It successfully distinguishes bonding strength between wafer center and edge and reveals that SiCN dielectric layers have 17.34% higher strength and better uniformity than SiO₂. This provides a reliable testing tool for hybrid bonding quality and process optimization, with broad prospects in industrial production and scientific research.