Mechanical and etching properties of dual ion beam deposited hydrogen-free silicon nitride films

The hydrogen-free silicon nitride (SiNx) films with x varying from 0 to 1.3 were prepared by sputtering a silicon target with concurrent nitrogen ion assisted at an energy of 250 eV. The composition and structure of the films were investigated by x-ray photoelectron spectroscopy (XPS) and infrared (IR) absorption. The etching rate of the silicon films in buffered hydrofluoric acid (BHF) at room temperature was zero and rose to 7 nm min-1 at x≥0.9. The mechanical and etching properties suggested that dual ion beam deposition SiNx films are potentially useful materials in microelectromechanical (MEMS) devices.