Measurement of Mechanical Properties in Small Dimensions by Microbeam Deflection

Abstract

AbstractIn this paper, we describe a technique for measuring elastic and plastic properties of thin films by microbeam deflection. The test procedure is similar to a macroscopic bending test where an external load is applied to a beam and its bending measured. Silicon oxide microbeams were made by different growth, lithography and etching techniques. The beams were then deflected with a nanoindenter, while the applied load and the displacement of the beam were recorded. Young's modulus was determined from the initial linear load-displacement behavior. Some beams were notched using a focused ion beam technique and loaded until brittle fracture occurred. These measurements permit the determination of the fracture toughness of the beam materials. In order to study plastic deformation in thin Ag films, the method was extended by depositing films onto the beams and measuring the behavior of the beam/film composite. Yielding of the Ag film was seen as a deviation from the linear-elastic behavior of the beam.