Experimental Research On Buckling Of Thin Films In Nano Scale

In this paper, the research work is to measure and characterize the mechanical properties of thin film materials with 150nm thickness. Recently great interest has been paid to the delamination and buckling of thin films deposited on substrates for their wide application. Investigation of thin film buckling is important for life predition of MEMS device since delamination and buckling is the chief demage mechanism.This paper focuses on the process of buckling of thin compressed titanium films deposited on an organic glass substrate utilizing an optical microscope. In order to simulate the films at work and to produce regular buckle mode external uniaxial compression is exerted to specimen. The digital image correlation method is proposed in this paper to calculate the inevitable overall displacement of observation field caused by external loading, hence this factor could be offset digitally and the deformation of buckles could be singled out.With the new method this paper analyzes two typical buckling modes: straight-sided wrinkle and circular blister. The analysis result of the straight-sided wrinkle is consistent with a well-known model (proposed by JW. Hutchinson) while the result of the circular blister is original. This success confirms the theoretical proposition that"sub-critical"defects can be used to indicate the overall displacement of the substrate in the process of loading. It is believed that the same method could be used to investigate other problems associated with thin film buckling. Furthermore, simplified DICM could realize the adjustment of observation field in real time so that a specified region could be tracked in the process of buckling driven by external loading and residual stress.In order to eliminate the rigid movement of observation field fundamentally our research group designs a new loading device driven by two matching piezocrystal sticks. In principle the symmetrically movement of clamps can guarantee the specimen deform symmetrically, therefore minimize the rigid movement of observation field. This paper hammers at the experimental proof-test of this symmetric loading device. Digital image correlation method is applied to measure the movement of the fringes of the clamps in the process of loading. We find that the symmetry performance varies under different pretightening force, so it's crucial to...