Measuring the thin film elastic modulus with a magnetostrictive sensor

This paper reports on the measurement of the thin film Young's modulus for Au, Cr, Cu, Al and SiC materials by a magnetostrictive sensor. Young's modulus of these films was determined by monitoring the sensor's resonant frequency, both before and after deposition. By measuring the film thickness, this frequency shift can be directly related to the film elastic modulus. All thin films were sputter deposited at room temperature with various thicknesses. The determined Young's modulus values were comparable to those found in the literature. An error analysis was performed and parameters such as film thickness and film density were found to dominate the measurement technique. The measurement error was also found to decrease as film thickness increased and was negligible (similar to 6% or less) for films 0.1 mu m thick or greater. The error was also found to be approximately half of that reported by competing techniques. The technique was found to be simple, quick and inexpensive to employ in assessing the thin film elastic properties of both metals and ceramics.