Diffusion barrier properties of metallorganic chemical vapor deposited NbNxOyCz films for Cu metallization

Amorphous NbNxOyCz films were deposited on SiO2 by metallorganic chemical vapor deposition using ethylimidotris(diethylamido)niobium(V) [NEt=Nb(NEt2)3] source with and without ammonia (NH3) at various temperatures. The diffusion barrier properties of NbNxOyCz films for Cu metallization were investigated. Both deposition temperature and resistivity of the film was found to decrease drastically upon the addition of NH3. The activation energy for the surface reaction was measured to be 0.71±0.05 eV in the temperature range of 500–600 °C and decreased to 0.23±0.04 eV by adding 20 sccm NH3 in the temperature range of 300–425 °C. The NbNxOyCz films were found to be nearly amorphous. The concentration of C in films was reduced significantly and the concentration ratio of N to Nb was varied from 1.67 to 1.1 by using NH3 as a reactant gas. Fifty-nanometer-thick NbNxOyCz film was found to effectively prevent the penetration of Cu into the substrate in samples annealed at 600 °C for 1 h. The barrier failure mechanism in NbNxOyCz is the diffusion of Cu through the barrier layer with the formation of niobium silicide.