Mechanical behavior of freestanding Mo thin films for RF-MEMS devices

Radio frequency microelectromechanical systems (RF-MEMS) are an attractive solution for wireless telecommunication applications. Freestanding films play an important role in RF-MEMS devices. For the successful commercialization of RF-MEMS devices, however, it is necessary to evaluate the mechanical reliability of freestanding films. The first step in the evaluation is to characterize the mechanical behavior of the films. This study focuses on freestanding Mo thin films. Mo test structures with a thickness of 960 nm were fabricated using sputtering deposition and patterned using a surface and bulk micromachining process. The strip-bending test was used to measure the stress-strain relation of the freestanding Mo thin films. The measured elastic modulus, initial stress, and yield strength of Mo thin films are reported.