Growth and tribological properties of amorphous hydrogenated carbon nitride produced by ion-beam technique

Abstract

Hydrogenated carbon nitride (HCN X ) films have been deposited on a variety of substrates using a 20 cm diameter r.f.-excited (13.56 MHz) ion gun and a four-axis substrate scanner. Mixtures of methane and nitrogen were used to generate various hydrocarbon and nitrogen-containing ions. The effects of r.f. power (99–600 W), N 2 /CH 4 gas mixture (0.2–3), total pressure, and ion energy (200–1750 eV) on the film deposition rate, chemical composition, and tribological properties have been systematically investigated. A quadrupole mass spectrometer and a total ion current measuring device were utilized to monitor the ion compositions of the gas mixtures of N 2 /CH 4 during the deposition for quality control and process optimization. The predominate ion species in the gas mixture of N 2 /CH 4 is CH + 3 , and as more nitrogen was added into the ion source with CH 4 , the ionic species of N + 2 , N + , NH + 4 , NH + 3 , NH + 2 , HCN + , CN + , and N 2 H + 2 were relatively increased. RBS and proton recoil techniques were used to analyze the as-deposited films. Unidirectional sliding friction experiments in UHV, humid air, and dry nitrogen were conducted to measure the coefficient of friction and wear behavior of these films. The tribological properties of HCN X films were compared with those of polycrystalline diamond (PCD) and diamond-like carbon (DLC) films studied previously. The correlation between the deposition parameters on the amorphous HCN X film growth rate, nitrogen content, and tribological properties is discussed.