Elementary Surface Reaction Simulation of Aluminum Chemical Vapor Deposition from Dimethylaluminumhydride Based on Ab Initio Calculations: Theoretical Process Optimization Procedure (2)

Abstract

This work demonstrates how to develop a qualitative surface reaction model to an elementary surface reaction simulation of deposition for the quantitative examination of model validity. Chemical vapor deposition of Al (Al-CVD) from dimethylaluminumhydride (DMAH) is examined as an example of this method. The surface reaction model of DMAH was deduced from ab initio cluster model calculations and experimental measurements of reaction products. Rate constants of all the elementary reactions were estimated for an elementary reaction model. Transition-state theory enabled the calculation of rate constants using the activation energies obtained from ab initio calculations. Entropy terms, however, were estimated by using an empirical method to reduce the computational effort. This approach minimized the ab initio calculations required to form a reaction data set. Simulated deposition profiles were compared with experimental data for Al-CVD in a tube reactor. Good agreement between the results of simulations and experiments indicate the possibility of constructing surface-reaction data sets for CVD process simulations based on ab initio quantum-chemical calculations.

Metal-organic chemical vapor deposition of aluminium oxynitride from propylamine–dimethylaluminium hydride and oxygen: growth mode dependence and performance optimization

“…3, it can be seen that the amount of carbon contaminant in films, originating from incomplete oxidation and local formation of TMA is reduced with increase in deposition temperature. Compared to reported carbon content for ALD-grown Al 2 O 3 films using Al(mmp) 3 or TMA chemistry at deposition temperature of 300 C, much lower values are obtained for DMAH-induced AlO x N y films in our case, 25,27 and a similar phenomenon has been observed by Sugiyama et al [28][29][30][31] Based on their observations, the lower carbon content for DMAH-derived samples can be attributed to the existence of the following disproportionation reactions: Therefore, on the surface, DMAH decomposes to TMA [Al(CH 3 ) 3 ] and -CH 3 and -H. These components will react with each other to form TMA and CH 4 . Thus, CH 3 radicals on the surface will be removed as gaseous product Al(CH 3 ) 3 (TMA) and CH 4 , which leads to lower carbon content of the films.…”

Optimization of Al-CVD process based on elementary reaction simulation and experimental verification: From the growth rate to the surface morphology

“…The elementary reaction model is described in the literature [6]. In short, this model is Langmuir-Hinshelwood type mechanism; a DMAH monomer dissociatively adsorbs on the unoccupied site of Al surface using H -Al bond as an attractive site to the surface while a dimer cannot adsorb because of the lack of free H -Al bond.…”

“…2(a) where the deposition rate was overestimated. The overestimation at higher DMAH partial pressure is partly because we neglected the interaction between surface adsorbates in the elementary reaction modeling [6].…”

“…The authors call this approach ECONOMIX (Experiments COmputer kNOwledge MIXed) and have demonstrated a series of necessary procedure in theoretical process optimization, ECONOMIX, taking an example of CVD of Al using dimethyl-aluminum-hydride (DMAH: (CH 3 ) 2 AlH). Elucidation of reaction mechanism [5], estimation of rate constants and chemical kinetics simulation with obtained elementary reaction mechanism [6] enabled the estimation of deposition rate of Al in a tube reactor. Validity of the reaction data was checked through the comparison of estimated deposition rate with experimental data.…”

High‐Aspect‐Ratio Parallel‐Plate Microchannels Applicable to Kinetic Analysis of Chemical Vapor Deposition

“…D can be also determined accurately by an empirical method, considering the operative conditions (e.g., temperature and pressure) and geometrical information about the 3D feature (e.g., mean pore size and the structural complexity, such as the tortuosity factor) . However, k s is difficult to determine theoretically due to many uncertainties in the ab initio computational calculation of surface chemistry (e.g., a significant error in estimation of vibrational frequencies). Thus, k s is often estimated by order‐of‐magnitude .…”