A First-Principles Study of Deposition of Iridium Coating on Mo (1 1 0) Surface by Atomic Layer Deposition

The reaction process of deposition of Iridium coating on Mo (1 1 0) surface by atomic layer deposition (ALD) was studied theoretically by using the density functional theory and periodical slab model. The results indicated that the whole ALD reaction cycle of iridium deposition can be divided into two half-reaction processes, that the half reaction I was the reaction between iridium precursor (Ir(acac)(3)) and oxygen atom on Mo cluster, causing the chemical bond length of Ir-C to stretch and that of Mo-O to shorten, and forming a ring-like skeleton structure of transition state Mo-O-C-Ir, which was approximately a planar structure and presenting a fresh and active surface of (CH3)(2)*Ir-Mo-Ir(CH3)(2)*; In the half-reaction II, the oxygen atoms react with -(CH3)(2)* active group of (CH3)(2)*Ir-Mo-Ir(CH3)(2)* surface, causing the chemical bond length of Ir-C to stretch and that of O-O to shorten, forming a ring-like skeleton structure of transition state O-C-Ir-C, which was also approximately a planar structure and presenting a fresh and active O*-Ir-Mo-Ir-O* surface eventually. Furthermore, the by-products of every surface reaction were released in the form of CO2 and H2O. The experiment result shown that the surface of iridium coating deposited by ALD at 300 degrees C was flat and smooth, and the preferred growth crystal plane was (111). The theoretical conclusion was in good agreement with the experimental results.