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 vap or deposition technique using silane-ammonia as the reactant gas mixtu re. The influence of the process parameters such as flow ratio of the reactant gases, pressure, substrate temperature, RF power, time of dep osition and electrode spacing on the deposition and etch rates were in vestigated. From the matrix of deposition conditions, the deposition p arameters 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 p resented.