Anisotropic fracture behavior of notched tensile single crystal silicon thin film specimens on microscale [MEMS material applications]

We investigated the fracture behaviors of single crystal silicon thin films on microscale, using single-edge-notched tensile specimens. We tested five specimen types with different surface orientations and tensile directions. The specimens' fracture behavior showed an obvious crystallography orientation dependency. When vertical {111} planes to the specimen surface exist, cracks propagate on the {111} - <112> cleavage system. When no vertical {111} planes exist, cracks propagate on inclined {111} - <112> cleavage system. We believe that this is because the minimum surface energy is on {111} planes.