Risk assessment of the crack propagation and delamination of the Cu-to-Cu direct bonded (CuDB) interface

This study is risk assessment of possibility of crack propagation at the CuDB interface using fracture mechanics approach. Finite element (FE) analysis and design of experiments (DOE) are used. A crack is assigned at the interface of the CuDB to mimic a small void. Initial crack location and dimensional variables (Initial crack length, Cu pad diameter and pitch, and TSV diameter and pitch) are varied to quantify the risk. The strain energy release rate (SERR) around the crack tip is calculated and compared with the critical SERR, obtained by experiments, to judge the possibility of crack propagation. Sensitivity analysis of design parameters is conducted. As a result, this study provides design recommendations that can minimize interfacial failure of the CuDB. In addition, this study explores various numerical modeling methodologies that can be implemented for efficient failure prediction of the interfaces.