Irreversible deformation of microns thick single crystal silicon in a temperature range of 350–500°C

Single crystal silicon (SCS) beam showed plastic deformation in a temperature range of 350-500°C, when it was in a size of 2-μm thick. SCS beams made from a top layer of SOI wafer were first elastically buckled by compressive force applied from free end of the beam in a longitudinal direction. Then the beams were kept at an elevated constant temperature for 1 hour in air. After releasing the applied force at room temperature, residual bent profile was evaluated using a laser profiler. Plastic hinge, i.e. localized plastic deformation, was observed for beams bent at 350-500°C but not at 300°C. We further demonstrated that a permanently deformed out-of-plane microstructure was obtained by applying hot air flow to a SCS planer film.