Electrical properties of plasma polymerized thin films deposited at high substrate temperature

The authors successfully prepared thin dielectric films containing silicon nitride-type linkages by plasma polymerization of tetramethylsilane in the presence of ammonia. The content of silicon nitride-type inorganic linkage in the polymer film increased with an increase in the substrate temperature from 25°C to 200°C. The rate of deposition of film decreased with an increase in substrate temperature. The dielectric constant and dissipation factor decreased with an increase in frequency. The loss tangent and dielectric constant decreased with an increase in the film deposition temperature from 25°C to 200°C at all the frequencies with an exception at the highest frequency. This has been attributed to the higher silicon nitride content in the films deposited at higher temperatures. A gradual increase in dielectric constant and loss tangent was observed for the films with an increase in measurement temperature. Aging of the plasma deposited films, both in air and oil, improved the dielectric properties. The DC resistivity increased with an increase in film deposition temperature. From these results it is concluded that, in general, the dielectric properties of plasma polymerized films can be improved by increasing the deposition temperature from ambient (which is commonly used) to 200°C