Discussion on microstructure of chemical-vapor-deposited TiN films based on the calculated gaseous concentration distribution in the reactor

TiN films were chemical-vapor-deposited on the inner wall of a tubular reactor. Films deposited in the upstream region of the reactor consisted of small and sharp crystals with (11l)-preferred orientation or random orientation. On the other hand, films deposited in the downstream region or at lower partial pressure of TiCl₄ consisted of columnar crystals with (110)-preferred orientation, having polyhedral shapes on the surface. For the films deposited under different conditions at different axial positions, relationships were investigated among the temperature, the calculated concentrations on the substrate, and the degree of preferred orientation of the films. As a result, it was shown that formation of films with (110)-preferred orientation is related to the conditions of high temperature and low partial pressure of TiCl₄. Films deposited at the higher gas flow rate had lower degrees of (110)-preferred orientation. Decrease in partial pressure of TiCl₄ along the axial direction in the reactor was calculated to be smaller at higher gas flow rate, and provided suitable conditions for deposition of films having small and sharp crystals.