Finite Element Analysis Of Mechanical Behavior Of Thin Film Post-buckling

The structure of thin film/substrate and multilayer films/substrate play important roles in information science and engineering. The thin film and substrate are usually subjected in the residual stress, external applied stress, temperature and electromagnetic fields. In the applying of these fields, the first type of damage of the film is fracture, the second type is buckling and delamination. The deformation and damnification of the film in nanometer scale directly affect the property and life of the electronic device. So it is essential and urgent to study and simulate the mechanical behavior of film buckling, buckling propagation and post-buckling of the film/substrate as a basic structure, which is of great significance to predict the life of the microelectronic devices.This paper summarized some typical experimental and numerical research results of the buckling and delamination of the films referred to the literatures. The quoted theoretic analysis and numerical simulation of the two ordinary models of buckling driven delamination such as straight-side buckling and circle buckling were introduced in this paper. Some usefull conclusion through the corresponding comparative analysis provided the basis for follow-up simulation work.This paper firstly introduced the contact pair to couple the nodes between shell and solid element which was used to simulate the film and substrate using the finite element method. After created the reasonable three dimension finite element model of circle buckling, the author studied the mechanical response of the post-buckling of the film under different ways of loading, different film thickness and different Young's modulus parameter of substrate. It is found that the loading ways greately influenced the stress distribution of the buckling film and so affected the buckling propagation of the film.The Von mises stress, nomal stress and shear stress are all decreased as the thickness of the film and the Young's modulus of the substrate increased, which suggested that the trend of buckling propagation of the film was weakening. So the film is not easy to delaminate and propagate from the substrate furtherly.In addition, the paper also established a typical model of buckling—straight-side buckling, which was formed in the early stages of buckling, discussed the stress distribution of buckling part of the film under axial compression loads, and explained the behavior of further expansion of the buckling from the view point of the energy release rate. Analysis and calculations showed that with the increase of additional load, the energy release rate of the crack front of the straight-side buckling will be gradually increased. Due to the energy release rate of the bending front is greater than that of the straight edge, the buckling expansion will move forward along the bending front. The bending curvature of the front will gradually increase accompanying expansion but the increase of bending curvature led to the energy release rate gradually decreases, and so the trend of expansion may slowly weakened until increase additional load, further expansion will be went on. This process made a good explanation of propagation mechanism of the straight-side buckling.