Morphology and preferred orientation of titanium nitride plates prepared by chemical vapour deposition

Thick titanium nitride (TiN_x; x = 0.74-1.0) plates (up to 2 mm thick) were prepared by chemical vapour deposition using TiCl₄, NH₃ and H₂ as source gases at a total gas pressure, P_tot, of 4 kPa, deposition temperatures, T_dep, from 1373-1873 K, and NH₃/TiCl₄, m_N/Ti, gas molar ratio from 0.17-1.74. The effects of deposition conditions on morphology, preferred orientation and composition of CVD-TiN_x plates were investigated. Surface morphology changed from faceted to nodular texture with increasing m_N/Ti and T_dep. The faceted and nodular deposits showed columnar and shell-like fracture cross-sections, respectively. The composition (x = N/Ti) increased with increasing m_N/Ti and T_dep below m_N/Ti = 1.0, and was constant above m_N/Ti = 1.0. Three kinds of preferred orientations were observed: (100) orientation at low T_dep, (110) orientation at intermediate T_dep and low m_N/Ti, and (111) orientation at high T_dep and high m_N/Ti. This tendency is discussed thermodynamically, and explained as being due to changes in the degree of supersaturation in the gas phase.