Photo resist thin films have mainly been used and investigated for versatile applications of micro electronic mechanical systems because of its outstanding aspect ratio and attainable film thickness. An accurate structure properties derived from validated material characterization is required in engineering applications. In this work, dynamic responses of photo resist thin films are tested by a nanoindentation in association with a dynamic mechanical analysis, where the thin film is coated on a silicon wafer by spin coating. The results show that the storage modulus of the photo resist thin film remains constant at the beginning and then increases as the indentation depth increases. Meanwhile, the loss modulus increases as the indentation depth increases. Varying the film thickness shows that the substrate effect plays an important role in determining the dynamic properties of thin films. However, the results agree well with the bulk material when the amplitude of nanoindentation is relatively small. It illustrates the dynamic mechanical analysis can be an efficient method to characterize the viscoelastic properties of thin films, but proper attention on the test parameters is needed.

This work uses nanoindentation and nanoscratch to measure the mechanical properties of evaporation copper thin films. The thin film is deposited on a silicon wafer substrate by using the physical vapor deposition method provided by a resistive heating evaporator. The mechanical properties are then determined by indentation test and lateral force test produced by nanoindenter and nanoscratch. The results show that, as the copper thin film is 500nm in thickness and the indentation depth increases from 100nm to 400nm, the Young’s modulus increases from 151GPa to 160GPa while the hardness increases from 2.8GPa to 3.5GPa. Moreover, both the Young’s modulus and the hardness decrease as the thickness of the thin film increases. Besides, the nanoscratch results show that the friction factor also increases as the scratch depth increases, and a thinner film thickness makes a larger friction factor. The results represent the substrate has a significant effect on the mechanical properties of the thin films.

In this paper, the imperfect tip effect of the Ti film on Si substrate on nanoindentation with Berkovich probe tip was investigated with the finite element method (FEM). In the literature, we found the effects of tip deformation and tip radius on nanoindentation were investigated frequently, but the imperfect centerline of tip has never been studied. In this work, at first, the Ti film on Si substrate was conducted with a high-resolution nanomechanical test The Young's modulus ofTi films can be obtained by using the Oliver and Pharr method while the nanoindentation depth is smaller than 20% of the film thickness for avoiding the substrate effect. Second, the FEM was employed to determine the yield stress of thin films because it cannot be found from nanoindentation. Finally, the load-depth of nanoindentation was compared between the experimental data and numerical results. The results show while choosing the suitable yield stress of films, the load-depth curves of numerical simulation were very close to the experimental curves with the imperfect effect being ignored. Moreover, it is concluded while the imperfect angles of tip were considered that the larger imperfect angles l e,1 or e" the smaller displacement on nanoindentation.

This work presents a comparison of numerical simulation and experiment of nanoindentation testing. A commercial finite element code ANSYS is adopted in the numerical simulation, in which elastic-plastic properties are considered. A PMMA specimen and a three side pyramidal Berkovich probe tip is used in the indentation tests. While the elastic-linear workhardening properties are adopted, the numerical results agree well with the experimental data for different indentation loads. It proves the numerical simulation can be used in the small scale analysis.

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