Controlled fluoridation of amorphous carbon films deposited at reactive plasma conditions

A study of the correlations between plasma parameters, gas ratios, and deposited amorphous carbon film properties is presented. The injection of a C₄F₈/Ar/N₂ mixture of gases was successfully used in an inductively coupled plasma system for the preparation of amorphous carbon films with different fluoride doping at room-temperature, using silicon as a substrate. This coating was formed at low-pressure and low-energy using an inductively coupled plasma process. A strong dependence between the ratios of gases during deposition and the composition of the substrate compounds was shown. The values of ratios between Ar (or Ar+N₂) and C₄F₈ - 1:1 and between N₂ and Ar - 1:2 in the N₂/Ar/C₄F₈ mixture were found as the best for low fluoridated coatings. In addition, an example of improving the etch-passivation in the Bosch procedure was described. Scanning electron microscopy with energy dispersive spectroscopy options, X-ray diffraction, and X-ray reflectivity were used for quantitative analysis of the deposited films.