A Thermochemical Process Using Expanding Plasma for Nitriding Thin Molybdenum Films at Low Temperature

The mechanical and chemical properties of transition metal nitrides are very attractive for numerous industrial applications. Thin nitride films are expected to be good diffusion barrier in microelectronic devices. Nitrogen diffuses into the whole thickness of the molybdenum film heated at low temperature and exposed to expanding plasma of (Ar-N2-H2) compared with pure N2 plasma. NHx species in the plasma are produced by different homogeneous or heterogeneous reactive mechanisms that results in an expansion of the plasma compared with pure N2 plasma. NHx species and probably H atoms improve the transfer of nitrogen into the metal by preventing the formation of MoO2 oxides which act as a barrier of diffusion for nitrogen.