Abstract—This work studies the fundamental operation behaviour of the nano thin film manufacturing process called atomic layer deposition. This attractive key-enabling nanotechnology is well known to deposit ultrathin, uniform, conformal and pinhole-free nano-films on complex topography. It is used in microelectronics, solar cells, food packaging, fuel cells, and water purification systems, among other applications. However, the technology is facing an impasse in providing detailed information on the understanding of the ALD process. With numerical simulations, this study investigates the internal mechanical behaviour and the growth rates in the Al2O3 thin film ALD process influenced at temperatures of 200°C and 250°C. TMA and O3 precursors with argon gas as the purge substance are used to examine an arbitrary Gemstar 6 ALD reactor. The governing laws of the conservation of mass, momentum, energy, species, and kinetic chemical reactions are analysed in a continuum domain, by using the software ANSYS Fluent and ChemkinPro. The results were validated by available literature and good agreement was achieved.