Experimentally validated finite element model for mechanical and fracture characteristics of SiCN thin films under different loads

In this work, SiCN thin films were deposited on p-Si (100) substrate using a thermal Chemical Vapor Deposition (CVD) process. The mechanical behavior of the thin film was characterized using the nanoindentation technique, where the load was varied from 1 to 4 mN, to understand the influence of load variation on the load-displacement response. Additionally, an experimentally validated FE model, incorporating an elast-plastic material response of the thin film, was developed to understand localized stress distribution and fracture behavior. The fracture behavior is examined through two modes: (a) cracking and interfacial delamination during the nano-indentation test and (b) the peel test. The FE model revealed that in the case of the weak cohesive interface between SiCN and Si, the interfacial failure initiates at a critical displacement of 110 nm. During the peel test, it was observed that the critical fracture energy of the interface plays a significant role in the interface debonding. These finding highlights the strong dependence of the mechanical integrity of the SiCN thin film on the applied load.