Optical system for rapid materials characterization with the transient grating technique: Application to nondestructive evaluation of thin films used in microelectronics

This letter describes a noncontact, automated means for nondestructively measuring the physical (elastic, thermal, electronic, optical) properties of bulk samples, surfaces, supported or unsupported thin films, and multilayer assemblies. The method, which is based on the transient grating technique, uses specially constructed beam-shaping optics to manipulate excitation and probe laser beams for initiating and detecting motions in a sample. We illustrate the approach by determining the thicknesses and mechanical properties of metal films commonly used in microelectronics.