Research on Evaluation of Adhesive Strength of Thin Film Based on Micromechanics

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1.Adhesive strength of thin diamond film was investigated based on the adhesion of microscopic nuclei appeared on the substrate in the initial stage of chemical vapor deposition. The microscopic adhesive strength of these individual nuclei was successfully evaluated by being scratched off in an electron microscope.2.The ultrasonic wave transmission has been examined in order to find the relation between the transmission of ultrasonic angle beam and the adhesive strength of thin film. By comparing the experimental results with the results obtained by theoretical models, the transmission of ultrasonic wave was revealed to be influenced by the character of shear stress transmission through the interface, which ensured that the ultrasonic angle beam technique presented here was able to evaluate quantitatively the adhesion of thin film.3.The adhesive strength has been examined in connection to a simple fracture test performed by a Vickers indentation testing machine on thin diamond film. The energy released due to the extension of interface cracks was evaluated by subtracting the energy required for the plastic deformation of the substrate from the total dissipated energy obtained from the load-displacement diagram during the indentation test. This result was compared with the result of fracture test of individual nuclei performed in 1.4.The adhesive strength of thin film obtained by the simple fracture test performed in 3 was compared with the evaluation result given by the ultrasonic angle beam in 2. In addition, by introducing the ab-initio molecular dynamics in which the state of electrons was taken into account, atomic scale adhesion of nuclei was further examined in connection to the ultrasonic transmission characteristics.