Mechanical Properties of Heat-treated CZ–Si Wafers from Brittle to Ductile Temperature Range

Four point bending tests were performed on heat-treated CZ–Si wafers at various temperatures. The fracture stress at room temperature does not change with heat treatments if the wafer has surface-denuded zones. However, the yield stresses of wafers at 700°C are remarkebly lowered by such treatments. The heat-treated CZ wafers are deformed plastically at relatively low temperatures and deformation twins appear in such low temperature plastic deformation. Their appearance is closely related to deformation temperature, strain rate and the presence of the thermally induced defects.