Computational Fluid Dynamics simulation of the ALD of alumina from TMA and H2O in a commercial reactor

Abstract

OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. This is an author-deposited version published in : http://oatao. Introduction Atomic Layer Deposition (ALD) is a deposition technique, derived fromChemical Vapor Deposition (Johnson et al., 2014), able to deposit highly conformal and uniform material films onto a substrate. ALD is based on the sequential exposure of a surface to two reactants, with which the surface reacts through self-terminating reactions (Johnson et al., 2014;Puurunen, 2005;George, 2010), inside a reactor chamber. The self-limiting nature of the surface reactions in the Atomic Layer Deposition (ALD) process ensures a high control over the deposited material film thickness down to the monolayer level (George, 2010). High uniformity and conformity of the deposited film can thus be achieved under optimized conditions (George, 2010). These characteristics make ALD a favorable tool to produce ultra-thin films for a variety of applications * Corresponding author. E-mail address: brigitte.caussat@ensiacet.fr (B. Caussat).in microelectronics, optoelectronics, catalysis, renewable energy and more (Johnson et al., 2014). However, ALD is a complex technique since it depends on the nature of the reactants and on the process conditions, and for this reason, research regarding the surface reactions and growth mechanisms is still ongoing. One of the most studied ALD processes is the deposition of Al 2 O 3 films from tri-methyl aluminum (Al(CH 3 ) 3 , TMA) and H 2 O vapor

Investigation of the initial deposition steps and the interfacial layer of Atomic Layer Deposited (ALD) Al2O3 on Si

“…This process recipe has been studied before [13] and yields a steady state growth per cycle of ~0.1 nm/cycle. For more information about the deposition mechanisms and the process setup, the reader is referred to our previous works [13,14].…”

“…Al2O3 is a favor-able candidate to replace SiO2 as a dielectric layer as it has a higher dielectric constant and has a similar band gap [4]. A great number of works has been published on this ALD process, dealing with the de-position process [5][6][7], reaction mechanisms [8][9][10], reaction kinetics [11][12][13], as well as the ALD reactor dynamics [13][14][15].…”

Ιn situ N2-NH3 plasma pre-treatment of silicon substrate enhances the initial growth and restricts the substrate oxidation during alumina ALD

“…More information on the reactor geometry and process setup is available in our previous works. 13,14 The TMA pulse time was set to 0.025 s, while the water pulse was of 0.1 s. The two reactant exposures were separated by an Ar purging step of 5 s. The pulsing and purging times being set, the isolation valve of the capacitance manometer was closed and the process was initiated. The number of cycles used varied from 5 to 75.…”

“…The deposition of Al2O3 films, using trimethyl aluminum (Al(CH3)3, TMA) and H2O vapor as metal precursor and oxidant source, respectively, 3 is one of the most studied ALD processes. Works published on this ALD process revealed important aspects of the deposition process [5][6][7] , reaction mechanisms [8][9][10][11] , reaction kinetics 12,13 , as well as the ALD reactor dynamics [13][14][15] . However, despite the numerous studies available, uncontrolled phenomena still occur in this process.…”

“…We previously reported on the reactor behavior, process dynamics, as well as the reaction kinetics during the ALD 6 ideal regime. 13,14 We characterize the films by STEM, to study both the Al2O3 deposition rate and the Si oxidation evolution between 0 and 75 cycles. We use theoretical results from the literature to explain the enhanced deposition rate and the surface mechanisms in the case of the N2-NH3 pretreated Si.…”