A reduction–nitridation process of molybdenum films in expanding microwave plasma: Crystal structure of molybdenum nitrides

Molybdenum Nitride Films: Crystal Structures, Synthesis, Mechanical, Electrical and Some Other Properties

“…Jauberteau et al [34,[53][54][55] have prepared molybdenum nitride films from Mo films coated on Si (100) substrates in an expanding plasma reactor. The molybdenum coatings have been deposited by electron beam evaporation of a molybdenum target in pure Ar atmosphere at a pressure of 0.5 Pa on Si substrates heated at 673 K with a radiofrequency electrical discharge operating at 50 W. The deposition rates are typically equal to 0.02-0.25 nms…”

“…In their very recent paper [55], the authors have reported that the crystalline structure of molybdenum nitride films depends on the presence of both remaining oxides in the native molybdenum film and hydrogen species in the plasma. The high temperature γ-Mo2N phase is synthesized during a reduction-nitridation process where hydrogen species such as NHx (mainly NH3 molecules and NH2 radicals) react with the remaining oxides in the metal film.…”

“…This effect is related to an increase of grain size at high temperature, which deteriorates the mechanical properties. The formation of both high temperature γ-Mo2N phase and low temperature β-Mo2N phase in expanding plasma is also rather unexpected since it is a non-equilibrium process because the temperature of electrons is much larger than the temperature of heavy species [55]. The authors assumed that exothermic reactions occur at the surface of the substrate between hydrogen species produced in the plasma and the remaining oxides in the molybdenum film, which promote the formation of the high temperature γ-Mo2N phase.…”

Silicides and Nitrides Formation in Ti Films Coated on Si and Exposed to (Ar-N2-H2) Expanding Plasma

“…The expanding microwave plasma process has been successfully employed to carry out nitriding treatments on thin molybdenum films from 200 nm to 1 µm thick in (Ar-N 2 -H 2 ) plasma [24][25][26]. Nitrogen diffuses in the whole thickness of films even at low temperatures (400 • C).…”

“…Nitrogen diffuses in the whole thickness of films even at low temperatures (400 • C). The recent work has especially highlighted the role of hydrogen species produced in the plasma, on the crystallographic structure of Mo 2 N [26]. Hydrogen species as NH x promote the crystallization of the high temperature γMo 2 N phase to the detriment of the low temperature βMo 2 N phase during the reduction-nitridation process.…”