Low-temperature deposition of TiN by plasma-assisted atomic layer deposition

Titanium nitride (TiN) films were deposited by a plasma-assisted at. layer deposition (PA-ALD) process, based on TiCl4 precursor dosing and remote H2-N2 plasma exposure, at temps. ranging from 100 to 400 DegC. The plasma, the PA-ALD process, and the resulting TiN material properties were extensively investigated. The plasma was studied by optical emission spectroscopy and Langmuir probe, revealing an ion d. of 109 cm-3 and an electron temp. of 3.5 eV just above the substrate. Under floating conditions there is thus a considerable ion flux towards the substrate per ALD cycle with a typical ion energy of .apprx.15 eV. TiN film growth was studied by in situ spectroscopic ellipsometry, revealing self-limiting surface reactions for the complete temp. range. At 100 DegC the growth rate of 0.3 A/cycle was found to be significantly lower than the growth rate of 0.6 A/cycle at 400 DegC. The stoichiometry of the films varied with the plasma exposure time, while the Cl content was mostly affected by the deposition temp. (2.1 atom % at 100 DegC to 0.07 atom % at 400 DegC). Resistivities as low as 71 mW cm were obtained at a temp. of 400 DegC, while at 100 DegC a fair resistivity of 209 mW cm was reached. These results show that PA-ALD with TiCl4 and H2-N2 plasma is well suited for low-temp. deposition of high-quality TiN films. [on SciFinder (R)]