Tertiary Alkyl Halides As Growth Activator And Inhibitor For Novel Atomic Layer Deposition Of Low Resistive Titanium Nitride

A novel atomic layer deposition (ALD) that utilizes tertiary alkyl (tert-alkyl) halides as both growth activator and inhibitor is introduced and demonstrated for the deposition of a low resistive TiN film using TiCl4 and NH3. Among the alkyl halides, tert-butyl iodide is identified as a suitable material for both growth inhibition and growth activation without any incorporation of C impurity in the film. The electrical resistivity values of TiN thin films in activator-type and inhibitor-type ALD were significantly improved by 55% and 49%, respectively. The mechanism of the reduction in electrical resistivity is elucidated by means of theoretical approach and characterizations of TiN films. For activator-type ALD, tert-butyl iodide induces in situ ligand exchange with an adsorbed Ti precursor to form Ti-I bonds, leading to an increase in the reactivity with a NH3 reactant. For inhibitor-type ALD, the improvement of film conformality in a high aspect ratio (>22:1) substrate is exhibited. This study demonstrates that the effectiveness on the use of tert-alkyl halides in ALD deposition can serve as an important guideline for future studies of the growth activator and growth inhibitor to improve film properties, making the method widely applicable. (c) 2021 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).