Atmospheric pressure chemical vapor deposition of TiN from tetrakis(dimethylamido)titanium and ammonia

Near stoichiometric titanium nitride (TiN) was deposited from tetrakis(dimethylamido)titanium (TDMAT) and ammonia using atmospheric pressure chemical vapor deposition. Experiments were conducted in a belt furnace; static experiments provided kinetic data and continuous operation uniformly coated 150-mm substrates. Growth rate, stoichiometry, and resistivity are examined as functions of deposition temperature (190-420 degrees C), ammonia how relative to TDMAT (0-30), and total gas-flow rate (residence time 0.3-0.6 s). Films were characterized by sheet resistance measurements, Rutherford Backscattering Spectrometry, and X-Ray Photoelectron Spectrometry. Films deposited without ammonia were substoichiometric (N/Ti < 0.6-0.75), contained high levels of carbon (C/Ti = 0.25-0.40) and oxygen (O/Ti = 0.6-0.9), and grew slowly. Small amounts of ammonia (NH3/TDMAT greater than or equal to 1) brought impurity levels down to C/Ti < 0.1 and O/Ti = 0.3-0.5. Ammonia increased the growth rates by a factor of 4-12 at temperatures below 400 degrees C. Films 500 Angstrom thick had resistivities as low as 1600 mu Omega-cm when deposited at 280 degrees C and 1500 mu Omega-cm when deposited at 370 degrees C. Scanning electron micrographs indicate a smooth surface and poor step coverage for films deposited with high ammonia concentrations.