Various applications of silicon nitride (SiNx) films prepared by catalytic chemical vapor deposition (Cat-CVD) as coating, passivation and insulating films are reviewed. Characteristic features of SiNx films by Cat-CVD are dense (low hydrogen content), low wet-etch rate, low oxygen or water-vapor transmission rate even when prepared at low temperatures below 300 degrees C and low stress. Therefore, SiNx films prepared by Cat-CVD are suitable as coating and passivation films for electronic devices, mechanical parts and plastic films. SiNx films prepared by Cat-CVD are, of course, also applicable as insulating films used in ultralarge-scale integrated circuits (ULSIs) and thin-film transistors (TFTs). These various applications are introduced, along with a summary of the fundamental properties of the SiNx films and a possible explanation as to why such dense films are obtained even at low temperatures. (c) 2005 Elsevier B.V. All rights reserved.