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

Abstract

Among transition metal nitrides, molybdenum nitrides have been much less studied even though their mechanical properties as well as their electrical and catalytic properties make them very attractive for many applications. The δ-MoN phase of hexagonal structure is a potential candidate for an ultra-incompressible and hard material and can be compared with c-BN and diamond. The predicted superconducting temperature of the metastable MoN phase of NaCl-B1-type cubic structure is the highest of all refractory carbides and nitrides. The composition of molybdenum nitride films as well as the structures and properties depend on the parameters of the process used to deposit the films. They are also strongly correlated to the electronic structure and chemical bonding. An unusual mixture of metallic, covalent and ionic bonding is found in the stoichiometric compounds.

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

“…No preferential orientation is observed in TiN films made by pulsed laser irradiation in N 2 ambient [23]. Such effects have been observed in Mo 2 N films since the excess of nitrogen in the structure leads to either crystallites orientation or amorphous structure [36]. Before it crystallizes, the TiN phase with amorphous structure is already formed at 600 • C. Nitrogen species produced in (Ar-N 2 -H 2 ) plasma react at the surface as well as H species reducing TiO 2 compounds.…”

Formation of a Mo2N skin layer in columnar-structural Mo films using NH3 plasma nitridation as the Se diffusion-barrier layer

“…However, the solubility of N in Mo is rather low, and a high temperature is typically required for the direct nitridation of Mo with N 2 gas due to strong N-N triple bonds [23,24]. The use of NH 3 could lower the nitridation temperature of Mo due to the reactivity of NH 3 at relatively low temperature, and Mo 2 N phase could be formed in the low-temperature condition [24].…”

Correlation between mechanical and microstructural properties of molybdenum nitride thin films deposited on silicon by reactive R.F. magnetron discharge

“…However, the number of peaks was changed, which indicates a change in the crystalline phase of γ-Mo 2 N, something that could be assigned to the formation of hexagonal MoN and the B1-MoN phases [16,26]. The B1-MoN phase is also known as cubic metastable ζ-MoN phase [9,27,28]. The XRD pattern exhibits weak peaks at 2θ = 47.8°, 54.7°and 56.4°, which correspond to undesirable polychromatic substrate reflections.…”

“…Mo-N thin films were also considered for wear protective coatings [7] and as diffusion barriers for aluminum in ultra-large-scale integrated circuits (ULSI) [8]. Various techniques are used to deposit Mo-N coatings [9], vacuum-arc evaporation [10], plasma-enhanced chemical vapor deposition (PECVD) [11], cathodic arc PVD [6] and nitride layers by ion implantation [12]. And among these techniques, DC and R.F.…”

“…And among these techniques, DC and R.F. magnetron sputtering are the most versatile processes allowing deposition of films with high quality even at low substrate temperatures [9]. The equilibrium phase diagram of molybdenum-nitrogen proposed by Jehn [13], enriched by computed phases of nonstoichiometric transition metal nitrides Mo 3 N 2 [14], shows three stable phases: the tetragonal β-Mo 2 N phase at low temperature, the cubic γ-Mo 2 N phase stable at high temperature and the hexagonal δ-MoN phase up to 50 at.% nitrogen concentration.…”