Fabrication and characterization of PECVD silicon nitride for RF MEMS applications

Abstract

The structural, optical and electrical properties of plasma enhanced chemical vapor deposited silicon nitride layers are investigated, which have been used as a dielectric layer during RF MEMS fabrication. During growth, the gas ratio (SiH4/NH3) is varied between 0.33 and 0.5 and pressure is varied between 400 and 700 mTorr while deposition time is kept constant. The results in the films show differing properties. The thicknesses of the resultant films are between 150 to 220 nm with different gas flow ratios and pressures whereas the deposition time was kept constant. A Bruggeman effective medium approximation is utilized to model the refractive index of the films. Reflectance measurements w..