Effect of retention time in vacuum on analytical values by EPMA for oxygen contents and S/Mo ratio of molybdenum disulfide sputtered films

Molybdenum disulfide films with three kinds of density (4.3, 3.7, and 2.6 g/cm 3 ) have been prepared on SUS440C steel rollers by radio-frequency sputter deposition. The effects of the evacuation times on the analytical values by electron probe microanalysis (EPMA) for films have been investigated. The compositions of films were influenced by the evacuation times in EPMA equipment In all specimens, the oxygen content decreased with lengthening the evacuation time, and the S/Mo ratio increased. The oxygen content of a film with density of 3.7 g/cm was the fewest. For a result of depth profiles using secondary ion mass spectroposcopy, hydrogen and oxygen contents within this film were the fewest. Desorbed gas species from films have been measured using thermal desorption spectroscopy system. Sulfur, hydrogen sulfide, and water were observed when a film was heated in the vacuum. Thus we suggested the following. The chemical reaction between molybdenum disulfide film and water in a film forms sulfur, hydrogen sulfide, and molybdenum oxide. The oxide remains in the film, and the sulfur or hydrogen sulfide is desorbed. This reaction is generated in the temperature rise of films by EPMA analysis, if the water is included in a film. The amount of desorbed gases was the least for a film with a density of 3.7 g/cm 3 .