Nanotechnology fabrication has become a popular field to develop advanced and cutting-edge technologies. Per se, deposition processes are industrialized to achieve nano-thin films with absolute control over the film thickness, conformal and uniform film growth over complex structures, and with minimum to no defects or pinholes. Atomic layer deposition (ALD) has revealed itself as a possible candidate to achieve these requirements. The successful deposition of a solid film by ALD is depended on the self-limiting reactions to formulate the excellent characteristics of the end product. Though, a number of factors, often co-dependent with one another, hinders the performance of the process. These factors involves, but not limited to, mechanical, chemical, and material factors. For this study the interest involves the mechanical and mechanistic factors of geometry influences, fluid flow, mass transportation, and thermodynamic aspects have on the heterogeneous chemical reaction. Through industrial ALD process recipes, the transitional and recirculation phenomena observed in the Atomic Layer Deposition (ALD) thin film process revealed a significant effect on the effective formation and growth of the thin film on the substrate. Deformation, vorticity and the evolution thereof in a flow field play a critical role in the structure of such systems. Subsequently, topological fluid dynamics are used to analyse the two-dimensional numerical simulations of the backward-facing step (BFS) phenomena and the recirculation flow patterns typically found within a horizontal atomic layer deposition reactor. Focus is placed on investigating the saddle points in the resulting vortex shedding, eddy distortion and recirculation due to the BFS phenomena, with the intent of gaining insight into the effects of such recirculation, vortex shedding and eddy distortion on the thin film formation and growth in an ALD process. The topological analysis is conducted for various step heights utilized within the ALD thin film process. Secondly, the impact at various flow rates injected into the reactor is analysed and compared. Here the ramifications at different Reynolds numbers are tested along with the size implications of the recirculation phenomena within the ALD nano-thin film fabrication process. This is especially analysed for the effects of the transition of the mass transport, diffusion and convection that takes place between the kinetically controlled and dynamically controlled regime. The analysis of the flow structures is presented via the Lattice Boltzmann Method (LBM) and computational fluid dynamics are utilized on the continuum scale to investigate the growth, deposition rate, mass fraction, and surface coverage within investigate the thin film process.  Findings revealed close similarities to experimental studies.

 


The Topology Within Recirculating Flow in the Atomic Layer Deposition Thin Film Process

Division / Sponsors: 
Aerospace, Bioengineering, Applied Mechanics, Design Engineering Division, Advanced Energy Systems, Manufacturing Engineering Division, Noise Control and Acoustics, Nondestructive Evaluation, Diagnosis, and Prognosis (NDPD), Nuclear Engineering Division, Process Industries Division, Fluids Engineering, Heat Transfer, Materials, Microelectromechanical Systems, Safety Engineering and Risk Analysis, Computers & Information in Engineering


Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2020/volume/84478

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