Characteristics of chemically vapor deposited TiN films prepared using tetrakis-ethylmethyl-amido-titanium

Abstract

Low pressure chemical vapor deposition of TiN was studied with tetrakis-ethylmethyl-amido titanium (TEMAT) in a cold-wall-type vertical flow reactor with helium or ammonia. Thermal decomposition of the precursor under helium atmosphere yielded TiN films at substrate temperatures of 250 °C. On the contrary, the reaction of TEMAT with ammonia occurred even at 100 °C. The film growth rate increased with increasing deposition temperature and precursor mole fraction. However, deposition rate was greatly reduced in the system of ammonia/TEMAT compared to thermal decomposition probably due to a vigorous gas phase reaction in the latter case. For the case of thermal decomposition, the growth rate levels off at 325 °C and this behavior has been interpreted as a transition from surface reaction to gas phase mass transfer control. The resistivity of the films deposited under similar conditions decreased with increasing thickness. It was found that higher deposition temperature and ammonia addition produced films of lower resistivity. Air exposure of the films caused an increase in resistivity, probably by oxidation of the films. Surface morphology of the TiN films in an ammonia-free system was smoother than that in the ammonia system. Conformality of the films strongly depended on the deposition temperature, ammonia usage, and ammonia flow rate. Lowering the deposition temperature and ammonia flow rate improved the conformality. Barrier performance of the TiN films deposited under helium atmosphere to copper diffusion in the Cu/TiN/Si structure showed an evidence of copper diffusion even after annealing at 550 °C for 1 h.