Properties of LPCVD titanium nitride for ULSI metallization

Summary form only given. A report is presented on a low-temperature CVD process (TiCl₄+NH₃) for deposition of conformal films, as an alternative to sputtering. Studies have been carried out at pressures of 100-300 mtorr and temperatures of 450-700°C on silicon wafers with a NH₃/TiCl₄ ratio of 20:1. Deposition rates as high as 1000 Å/min have been observed. Film resistivities as low as 80-Ω-cm have been seen for the thinnest films (~500 Å). The resistivity increases as the films grow thicker, apparently due to a decrease in their density. The films contain small amounts of chlorine (<4%), oxygen (<6%), and hydrogen (<11%), and have Ti/N ratios close to one. They are crystalline with columnar crystals and are adherent. Contact resistance measurements on p⁺ contacts annealed at 500°C gave values of 2-3×10^-6 Ω-cm². Multicontact diodes, under the same conditions, showed less than 1-μA leakage at 10-V reverse bias