STUDY ON EVALUATION METHOD OF RESIDUAL STRESS AND JOINT RELIABILITY OF SEMICONDUCTOR DEVICE BASED ON ULTLASONIC MEUREMENT TECHNOLOGY

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The purpose of this study is to establish the technique for the evaluation of the residual stress and the reliability of the microjoints of the semiconductor device by using the surface acoustic wave velocity measured by the acoustic microscope. First, the method of the stress evaluation of the resin packaged device by the surface acoustic wave velocity was examined. Next, we proposed the method of measuring the elastic modulus of the TiN thin film used as a barrier metal of the semiconductor. Finally, the characteristic on thermal stress and the reliability of the microjoints of the semiconductor device were examined based on the numerical analysis results. The main results obtained are as follows:(1)The surface acoustic wave velocity is measured in high accuracy under the tensile and the compressive load. As a result, the acoustoelasticity coefficient of the resin material was calculated. Moreover, it is clear that the stress of the test specimen with stress distribution could be mea … More sured. And, we proposed the residual stress evaluation method by the surface acoustic wave velocity measured by the acoustic microscope.(2)The surface acoustic wave velocity of the test specimen which deposits the TiN thin film on the substrate depends on the surface acoustic wave velocity of the substrate. Therefore, the surface acoustic wave velocity only of thin film cannot be measured. Therefore, the surface acoustic wave velocity only of thin film could be calculated by arranging the experimental result by the simple equation calculated from the elasticity theory. Moreover, we proposed the technique for reversely analyzing the elastic modulus of thin film.(3)To clarify the property of the thermal stress generated by mounting, the influence of various parameters on the thermal stress was examined by the elasticity theory and the numerical analysis. A basic knowledge to improve the joint stability further was obtained from the result of the above. Moreover, the peel strength of the adhesive was calculated by using a critical energy release rate. From result of the above, it become clear that the joint stability is secured when peel length is short. Less