Analysis of Residual Stress at the Interface of Epoxy-Resin/Silicon-Wafer Composites During Thermal Aging

During the thermal aging process of epoxy resin, microcracks, interfacial delamination, and warpage are the key factors leading to semiconductor device damage. Here, epoxy-resin specimens (EP-Ss) and epoxy-resin/silicon-wafer composites (EP-SWs) were prepared to analyze the distribution of residual stress (RS) in epoxy resin and its thermal aging process changes. The uniaxial tensile approach and Raman spectroscopy (RAS) showed that the peak shift of aliphatic C-O in EP-Ss was negatively correlated with the external stress, and that the stress correlation coefficient was -2.76 x 10-2 cm-1/MPa. Then, RAS was used to evaluate the RS distribution of EP-SWs, obtaining a high-resolution stress-distribution image of 50 x 50 pixels and revealing a strong stress concentration at the interface between the epoxy resin and the silicon wafer. Additionally, Fourier transform infrared spectroscopy (FTIR), Differential scanning calorimetry (DSC), Field-emission scanning electron microscopy (FE-SEM), and RAS were used to analyze the chemical composition, molecular structure, interfacial microstructure, and RS of the epoxy resin during the thermal aging process. With the increase in the thermal aging time, the epoxy resin underwent secondary curing, the RS at the interface changed from tensile stress to compressive stress, and cracks were formed. The results illuminate the effect of the thermal aging process on the interface-failure mechanism of composite materials, aiding in the reliability evaluation and safety design of semiconductor devices.