Low-Temperature Deposition of TiN by Plasma-Assisted Atomic Layer Deposition

Abstract

Titanium nitride () films were deposited by a plasma-assisted atomic layer deposition (PA-ALD) process, based on precursor dosing and remote plasma exposure, at temperatures ranging from 100 to . The plasma, the PA-ALD process, and the resulting material properties were extensively investigated. The plasma was studied by optical emission spectroscopy and Langmuir probe, revealing an ion density of and an electron temperature of 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 . film growth was studied by in situ spectroscopic ellipsometry, revealing self-limiting surface reactions for the complete temperature range. At the growth rate of was found to be significantly lower than the growth rate of at . The stoichiometry of the films varied with the plasma exposure time, while the Cl content was mostly affected by the deposition temperature ( at to at ). Resistivities as low as were obtained at a temperature of , while at a fair resistivity of was reached. These results show that PA-ALD with and plasma is well suited for low-temperature deposition of high-quality films.