The material and electrical properties of plasma‐enhanced chemical vapor deposition fluorinated silicon nitride were studied. These films were deposited using SiH4‐NF3‐NH3‐N2chemistry. The concentration of fluorine in the films increases as the flow rate of NF3increases during the deposition. The refractive index of the films was found to decrease as the concentration of the fluorine increases. The properties of the films, such as wet etch rates in various etching solutions, the reactive‐ion etch rate, and the stress were measured. The concentration of SiH and NH bonds were also measured. Most of the material properties of the films were found to be strongly dependent on the concentration of fluorine in the films. It was also found that the refractive index of the fluorinated silicon nitride is determined by the concentration of fluorine. As a result, the refractive index of the fluorinated silicon nitride, which can be readily measured using an ellipsometer, is a useful monitor for process and quality control of film preparation in manufacturing. High resistivity and a frequency‐independent dielectric constant were also observed from the fluorinated silicon nitride. The material and electrical properties of fluorinated silicon nitride with a refractive index in the range from 1.70 to 1.80, which shows promise for device applications, have been studied in detail.