A low-temperature process with good step coverage of silicon nitride (SiN) formed by low-pressure chemical vapor deposition (LPCVD) has been successfully developed by using hexachlorodisilane (HCD). HCD-SiN showed a higher deposition rate than the conventional LPCVD technique performed at temperatures above 700 degrees C. SiN films can be deposited down to 250 degrees C using HCD. Deposition characteristics, film composition, and film properties under integrated circuit fabrication processes are measured mainly in terms of deposition temperature dependence. A low-k HCD-SiN film, formed at 450 degrees C with a permittivity of 5.4, was applied on Cu films as an oxidation and diffusion barrier layer. The film shows excellent barrier properties and is advantageous for realizing high-performance very large scale integrated devices with Cu interconnects.