Extended finite element analysis of plastic and fracture behaviors of SiC-based multi-layer thin films system

摘要

The interfacial mechanics of silicon oxycarbide (SiCO) thin films is a key factor for its applications as low dielectric constant (low K) materials, and it is very challenging for current experimental technologies to investigate the interfacial fracture of the materials system. In this work, nano-indentation induced plastic behavior and fracture properties of SiCN/SiCO/SiCN low K system are evaluated and predicted by extended finite elements method. To improve the accuracy of the model, an interfacial layer is added at the SiCO/SiCN and SiCN/Si substrate interfaces of the system. Based on the improved model, the calculated load - displacement curves consist nicely with the experimental data in all the indentation stages, and the mechanical behavior relating to interfacial delamination is successfully captured. Moreover, the indentation-dependent of Young's modulus and hardness are predictied, and the plastic properties of the films are obtained by calculating stress-strain relationship. The crack propagation paths and the calculated energy release rates are comparable to the experimental results.