SIZE EFFECT ON THE BENDING AND TENSILE STRENGTH OF MICROMACHINED POLYSILICON FILMS FOR MEMS

• 来源期刊: 固体力学学报(英文版)
• 学科: 工学
• 年，卷（期）: 2004,（3）
• 页码范围: 203-208
• 页数: 6页
• 分类号: TB34
• 语种: 中文

摘要

The bending strength of microfabricated polysilicon beams was measured by beam bending using a nanoindenter. Also, the tensile strength of microfabricated polysilicon thin ?lms was measured by tensile testing with a new microtensile test device. It was found that the bending strength and tensile strength of polysilicon microstructures exerts size e?ect on the size of the specimens. In such cases, the size e?ect can be traced back to the ratio of surface area to volume as the governing parameter. A statistical analysis of the bending strength for various specimen sizes shows that the average bending strength of polysilicon microcantilever beams is 2.885 ± 0.408 GPa. The measured average value of Young's modulus, 164 ± 1.2 GPa, falls within the theoretical bounds. The average fracture tensile strength is 1.36 GPa with a standard deviation of 0.14 GPa, and the Weibull modulus is 10.4 -11.7, respectively. The tensile testing of 40 specimens on failure results in a recommendation for design that the nominal strain be maintained below 0.0057.