Properties of SiN films deposited by photo CVD and memory characteristics of MNOS structure

Silicon nitride (SiN) film was deposited at substrate temperature of 100–400°C using a photo CVD technique with NH3 and SiH2Cl2 gases and ultraviolet (UV) light from a low-pressure mercury lamp. Based on ESCA analysis, it has been clarified that the film is relatively Si-rich, that the binding energy of Si2p changes from SiN bond to SiNO bond at the oxygen content of 23 percent and that the film deposited at 100°C changes from SiN to SiO2 structure after the deposition. In the measurement of I–V characteristics using metal-SiN-Si (MNS) structure, the film leakage current was small, but the film deposited at high-substrate temperature had a large leakage current although the interface characteristics improved. From the characteristics as a nonvolatile memory using a metal-SiN-SiO2-Si (MNOS) structure, it has been found that the SiN film deposited by the photo CVD method is useful for memory devices and the electron trap density increases with deposition temperature.