Comparison between Ar+CH4 cathode and anode coupling chemical vapor depositions of hydrogenated amorphous carbon films

Abstract This research focuses on the comparison between cathode- and anode coupling deposition characteristics of hydrogenated amorphous carbon (a-C:H) using the capacitively coupled plasma (CCP) method. a-C:H films were fabricated by Ar+CH4 CCP chemical vapor deposition. The cathode and anode coupling depositions were simultaneously performed in a single CCP reactor. Compared to the anode coupling process, the cathode coupling process provides high-kinetic-energy ions impinging on the film surface. The cathode coupling process produced a-C:H films with a mass density of 1.75 g/cm3 and a hydrogen content of 36% at a deposition rate of 22.9 nm/min. By contrast, the anode coupling process resulted in a-C:H films with a mass density of 1.4 g/cm3 and a hydrogen content of 50% at a deposition rate of 10 nm/min. Raman spectroscopy shows that a-C:H films in the cathode coupling process have a highly disordered bonding, whereas a-C:H films in the anode coupling process have highly strained graphite.