Feasibility of SiNx passivation films at low substrate temperatures prepared by catalytic chemical vapor deposition (Cat-CVD) is studied for ferroelectric nonvolatile random access memories (FRAMs). SiNx films were prepared at low substrate temperatures of 100 °C, 175 °C and 200 °C using Cat-CVD. Adjusting on flow rate ratio of SiH4/NH3, the refractive index of SiNx film, deposited at 175 °C and 200 °C, measured by ellipsometry is controlled around 2.0. SiNx films, with the refractive index around 2.0, deposited at only 200 °C show the following properties. 1) No oxidation during air exposure for 3 months was observed for the films. 2) Etching rate of the films in buffered HF is 20 nm/min. The dense SiNx film, which is resistive for oxidation in air exposure and dissolution in buffered HF, is prepared at 200 °C and the film is suitable to the passivation of ferroelectric capacitors.