Effect of ion-bombardment on the deposition of a-CN x:H films in CH 4/N 2 r.f. plasma

Abstract

The effect of ion-bombardment on the deposition rate and the optical properties of hydrogenated amorphous carbon nitride (a-CN x :H) films in CH 4/N 2 r.f. (13.56 MHz) plasma at 1.0 Torr, has been measured to study the deposition mechanism of the a-CN x :H film. In order to avoid the ion-bombardment, the growing film surface was protected with a concave shaped glass plate placed on a substrate surface. Inside the glass plate (without ion-bombardment), the a-CN x :H film was able to be deposited in CH 4/N 2 plasma, while in pure CH 4 plasma no film deposition occurred. In the a-CN x :H film deposition without ion-bombardment, the neutral radical such as ground state CN radical generated in the CH 4/N 2 plasma, was speculated to play an important role. In the Fourier transform infrared spectra of the a-CN x :H films, the absorption intensities at 2800–3000 cm −1 band associated with CH bond and also at 2246 cm −1 peak maybe associated with CN (nitrile) structure, were greater in the a-CN x :H films without ion-bombardment than in those with ion-bombardment.