Measurement of anisotropic fatigue life in micrometre-scale single-crystal silicon specimens

The fatigue life of micrometre-scale single-crystal silicon specimens was measured using the resonant vibration of a micromachined resonator device. Two kinds of identically shaped specimens oriented to ??110?? and ??100?? crystal directions on the (001) plane were tested. On the deflection-life relationship, the deflection amplitudes of the ??100?? oriented specimens were approximately 1.56 times higher than that of ??110?? oriented ones at the same fatigue life. Observation by scanning electron microscope showed that the fracture surfaces differed depending on the specimen orientation and deflection amplitude. The life-shortening effect of the surface roughness was also demonstrated.