Deposition parameter studies and surface acoustic wave characterization of PECVD silicon nitride films on lithium niobate

Silicon nitride films were deposited by a plasma enhanced chemical vapor deposition technique using silane-ammonia as the reactant gas mixture. The influence of the process parameters such as flow ratio of the reactant gases, pressure, substrate temperature, RF power, time of deposition and electrode spacing on the deposition and etch rates were investigated. From the matrix of deposition conditions, the deposition parameters for high quality films applicable to surface acoustic wave (SAW) technology were found. Experimental results on the acoustic loss, reflectivity and velocity dispersion for the fabricated devices are presented.>