A measurement system was newly developed to evaluate the mechanical properties of micro-sized materials at very low temperature ranging from -130°C to room temperature, using liquid nitrogen cooling. In this work, we conducted the fracture toughness tests of single crystal silicon films with thicknesses of about 1 μm at low temperature and found the temperature dependence on the fracture toughness, especially the drastically change between -20 and -50°C. A change of fracture behavior was also observed in the fracture specimens, from simple cleavage on the (110) surface at lower temperature to the (111) at higher. These results suggest that the transition of the fracture mode is similar to usual behavior that is variation from brittle failure to ductile observed over 600°C in bulk silicon.
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