DLC Coatings by PI³D: Low-Voltage žersus High-Voltage Biasing

Abstract

Diamond-like carbon (DLC), in particular hydrogenated amorphous carbon (a-C:H) films have been formed on various conductive and dielectric materials by plasma immersion ion implantation and deposition (PI 3 D) processing. Effect of pulse voltage and other process parameters on the film properties was investigated. It was found that for conductive substrates, a low-voltage (≈ 1 kV), high repetition rate pulsing provides better overall film performance comparing to that obtained by applying higher voltages, which is also favourable for conformal treatment of 3D workpieces. However, short 1-2 µs, high-voltage 5-20 kV pulses are required for dielectric workpieces several millimeter thick. Good film adhesion was achieved by forming a Si-containing buffer layer using hexamethyldisiloxane (HMDSO) as a precursor and a low-voltage pulsing. Roughness and wettability of DLC coatings was found to be controlled by varying the bias specs and sample temperature. Very smooth films with average roughness less than 1Å were prepared at optimised process parameters.