单晶硅纳米梁杨氏模量的弯曲测试

为研究纳米梁的力学特性,采用SOI晶圆制备了硅双端固支梁纳米梁,利用典型的原子力显微镜（AFM）弯曲测试方法测试了硅纳米梁〈100〉晶向的杨氏模量.AFM悬臂探针定位在纳米梁的中点处向下移动,纳米梁受到挤压发生弹性形变,形变过程存在一个最大形变点,在该点后,纳米梁被挤压在SOI硅片底层硅上.最大形变前的测试数据用于计算力-位移曲线斜率,最大形变后的测试数据用于计算探针的灵敏度,其实验值分别为0.792N/m和81.83nm/V.最终得到的杨氏模量为104GPa,该值小于体硅的杨氏模量,表面应力和缺陷可能是导致实验值偏小的原因.

Bending Test of Young's Modulus of Crystalline Silicon Nano-Beam

To study the mechanical performance of the nano-beams, double-clamped silicon nano-beams were fabricated based on silicon-on-insulator (SOI) wafer. The Young's modulus of silicon nano-beam on (100) direction was measured by bending test method using an atomic force microscope (AFM). AFM cantilever probe is put at the centre of beam and presses the beam, and then the beam begins to bend. There is a turning point in the process of bending. After the point, the beam is pressed on the bottom silicon of SOI wafer. The data before turning point can be used to calculate the slope of force-displacement curve and the data after turning point to calculate the probe sensitivity. The experimental values are 0. 792 N/m and 81. 83 nm/V, respectively. The final measured Young's modulus is 104 GPa, which is smaller than that of bulk silicon. Surface stress and defects are considered as the reasons which affect the Young's modulus of the nano-beam.