ポリシリコン薄膜のヤング率の有限要素解析(<特集>マイクロマテリアル)

概要

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The Young's modulus of a polysilicon thin microelement was evaluated using the previously developed mechanical testing system for thin tensile microelements. The tested part of the specimen is 250μm in length, 10μm in width, 3.8μm in thickness. The Young's modulus of the tested polysilicon thin film was 133±10GPa. To analyze the effect of the crystal orientations and the grain size on the Young's modulus, two-dimensional finite element models in plain strain condition were developed using a Voronoi structure. The number of grains in a model of a 10μm square area was changed from 23 to 1200. The crystal orientation of the film was analyzed by means of an electron back-scattering dif-fraction pattern (EBSP) method. The front surface of the film did not have the oriented structure. Therefore, random crystal orientation was given to each grain of the FEM models. When the number of grains increased, the Young's modulus converged on about 170GPa and its scatter caused by the different sets of the random orientation was reduced. However, the Young's modulus obtained by the FEM analysis was larger than the value obtained by the tensile tests.
2005-10-15