In order to accomplish reliable mechanical design of MEMS, the infuences of surface roughness and octadecyltrichlorosilane (OTS) self-assembled monolayers (SAMs) on the mechani- cal properties of micromachined polysil...In order to accomplish reliable mechanical design of MEMS, the infuences of surface roughness and octadecyltrichlorosilane (OTS) self-assembled monolayers (SAMs) on the mechani- cal properties of micromachined polysilicon flms for MEMS are investigated. Surface efect on the fracture properties of micromachined polysilicon flms is evaluated with a new microtensile testing method using a magnet-coil force actuator. Statistical analysis of the surface roughness efects on the tensile strength predicated the surface roughness characterization of polysilicon flms being tested and the direct relation of the mechanical properties with the surface roughness features. The fracture strength decreases with the increase of the surface roughness. The octadecyltrichlorosi- lane self-assembled monolayers coating leads to an increase of the average fracture strength up to 32.46%. Surface roughness and the hydrophobic properties of specimen when coated with OTS flms are the two main factors infuencing the tensile strength of micromachined polysilicon flms for MEMS.展开更多
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...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.展开更多
基金Project supported by Program for New Century Excellent Talents in University,the National Natural Science Founda-tion of China(Nos.50135040and50475124),the Excellent Young Teachers Program of MOE of China,the Foundation forthe Author of National Excellent Doctoral Dissertation of China(No.200330)and the National Basic Research Programof China(No.2004CB619305).
文摘In order to accomplish reliable mechanical design of MEMS, the infuences of surface roughness and octadecyltrichlorosilane (OTS) self-assembled monolayers (SAMs) on the mechani- cal properties of micromachined polysilicon flms for MEMS are investigated. Surface efect on the fracture properties of micromachined polysilicon flms is evaluated with a new microtensile testing method using a magnet-coil force actuator. Statistical analysis of the surface roughness efects on the tensile strength predicated the surface roughness characterization of polysilicon flms being tested and the direct relation of the mechanical properties with the surface roughness features. The fracture strength decreases with the increase of the surface roughness. The octadecyltrichlorosi- lane self-assembled monolayers coating leads to an increase of the average fracture strength up to 32.46%. Surface roughness and the hydrophobic properties of specimen when coated with OTS flms are the two main factors infuencing the tensile strength of micromachined polysilicon flms for MEMS.
基金Project supported by the Micro/Nano Science and Technology Center Science Founation of Jiangsu Province (Nos.BK2002147 and 02KJA460001) the Excellent Young Teachers Program of MOE of China and the National Natural ScienceFoundation of China (No. 50135040).
文摘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.
