Process condition dependence of mechanical and physical properties of silicon nitride thin films

This study uses a resonance method to determine Young's modulus (E), shear modulus (G), and Poisson's ratio (nu) of plasma-enhanced chemical vapor deposited silicon nitride (SiNxHy) thin films deposited under varying process conditions. The resonance method involves exciting the bending and torsional vibration modes of a microcantilever beam fabricated from a film. The E and G values can be extracted directly from the bending and torsional vibration modes, and the nu value can be determined from the calculated E and G values. The density (rho) of the films was determined using a quartz crystal microbalance method. In order to determine the validity of the resonance method, finite element modeling was used to determine its dependence on microcantilever beam dimensions. Over a deposition temperature range of 100-300 degrees C, measured E, G, and nu values varied within 54-193 GPa, 22-77 GPa, and 0.20-0.26 with changes in process conditions, respectively. Over the same deposition range, measured rho values varied within 1.55-2.80 g/cm(3) with changes in process conditions.