Physical and Barrier Properties of Plasma Enhanced Chemical Vapor Deposition α-SiC:N:H Films

In this work, we investigate the thermal stability and physical and barrier properties of three species of plasma enhanced chemical vapor deposition (PECVD) α-SiC:N:H silicon carbide films with different carbon and nitrogen contents and dielectric constants less than a value of 5.5. For comparison, one species of α-SiN:H film with a k value of 7.2 is also studied. It is found that the dielectric constant decreases with increasing content of carbon and decreasing content of nitrogen in the α-SiC:N:H film. All of the three species of α-SiC:N:H and the one species of α-SiN:H films are thermally stable at temperatures up to 500°C. However, degraded barrier capability and moisture resistance were observed for the α-SiC:N:H film with a k value of 3.5, which has a C/Si atomic ratio of 0.875. This is presumably due to the poorly crosslinked molecular structure and porosity enhancement caused by the abundant amount of carbon in the α-SiC:N:H film.