Surface reaction mechanism of atomic layer deposition of titanium nitride using Tetrakis(dimethylamino)titanium and ammonia

Abstract

Atomic layer deposition (ALD) is an excellent technology used for the preparation of various nanomaterials in microelectronics, energy, catalysis, optics and coatings. Titanium nitride (TiN) is an interesting member of the refractory transition metal nitrides family exhibiting chemical and thermal stability. Using density functional theory calculations, the reaction mechanisms of the ALD of TiN using tetra(dimethylamino)titanium (TDMAT) and ammonia as precursors was investigated. The results showed that the mechanism consisted of two reactions: the TDMAT reaction and NH3 reaction. In the TDMAT reaction, the precursor achieved the elimination of dimethylamine via a substitution reaction with the surface amino groups. In the NH3 reaction, the reaction process was complicated. They mainly included exchange reactions between the amino and dimethylamino ligands and coupling reactions forming bridged products and by-products, such as NH3 or HN(CH3)2. As a whole, all of these surface reactions were thermodynamically and kinetically favorable. All these insights into surface reactions of the ALD of TiN provided the guidance for precursor design and the ALD growth of other nitride and titanium-based compounds.