Investigations on TiN, TiC and Ti(CN) obtained by chemical vapor deposition

Abstract
The paper presents the results of the chemical vapour deposition (CVD) of TiN, TiC and Ti(CN) using TiCl₄, H₂, N₂ and CH⁴ as educts. The influence of the deposition conditions like temperature, total pressure and composition of the reaction gases on the deposition process is studied and a model for the deposition rate is proposed. The deposition process of TiN, TiC and Ti(CN) up to a TiCl₄ partial pressure of 3.8 kPa can well be described by a power law of first order. Reducing the total pressure results in an increased deposition rate, higher apparent activation energy, lower depletion of the reaction gas and more uniform coatings. The composition of TiN and TiC films is not stoichiometric with respect to N and C (TiN_0.6, TiC_0.7) and independent of the deposition conditions. The composition of Ti(CN) can be changed by varying the reaction temperature, which allows to deposit graded layers. Ceramics coated with TiN and Ti(CN) achieve the lowest value of electrical resistivity (34 µohm.cm) at a layer thickness of 11 µm. For TiC a 25 µm layer is needed in order to achieve a minimum value of 209 µohm.cm.