TiN is among the candidates for thin film diffusion barriers on integrated circuit contacts. We have deposited titanium nitride (approximately TiN) and TiN+Sm films onto Ni substrates near room temperature by ion plating. Ti was e-beam evaporated in a chamber containing about 2.8 Pa (21 mTorr) of N2 in the vicinity of the substrate. A plasma was excited between the substrate and a gas source-tube near the substrate by a combination of electrons from the e-beam (or backscattered from the Ti melt) and from an electric field generated by a constant current power supply (usually set at 100 mA) connected with negative polarity to the substrate. Deposition rates were 0.5 μm/min and the film thicknesses were 2 μm. The films are crystalline, slightly burnt gold in color, and are less dense and have an order of magnitude higher electrical resistivity than TiN produced by CVD methods. The addition of at least 12 at. % Sm produced amorphous films. The diffusion of Ni through these films was measured by energy dispersive analysis in a SEM. The amorphous material showed substantially lower diffusivities. Values of D0 and Q, in the equation D=D0 exp (−Q/RT), were determined to be 0.82×10−7 cm2/s and 29 kcal/mol for crystalline TiN, and 0.56 cm2/s and 67.3 kcal/mol for amorphous TiN+12 at. % Sm films. Because of film variation in structure and composition, these values vary. However, there is still a large improvement in the diffusion barrier property of TiN films by using amorphous films containing Sm. Ni diffuses very slowly into amorphous TiN+Sm at temperatures up to 655 °C. One must increase the temperature to 765 °C in order to observe diffusion rates comparable to crystalline TiN at 590 °C.

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