Tuning the Mechanical Properties of SiO2 Thin Film Using Plasma Treatments for MEMS Applications

This study reports a novel method for tuning thin film mechanical properties by means of plasma surface modification. According to the experiment results, the formation of Si-N chemical bonds on the surface of SiO
₂
film will lead to an equivalent gradient residual stress; moreover, this gradient residual stress can be easily tuned by varying the conditions of NH
₃
plasma. These characteristics can be employed to tune the shape of micromachined beams for MEMS applications. In addition, the equivalent Young's modulus of SiO
₂
films can be changed by plasma treatment; the resonant frequencies of the micromachined beams can also be tuned.