Multiscale Computational Fluid Dynamics: Methodology and Application to PECVD of Thin Film Solar Cells

Abstract

This work focuses on the development of a multiscale computational fluid dynamics (CFD) simulation framework with application to plasma-enhanced chemical vapor deposition of thin film solar cells. A macroscopic, CFD model is proposed which is capable of accurately reproducing plasma chemistry and transport phenomena within a 2D axisymmetric reactor geometry. Additionally, the complex interactions that take place on the surface of a-Si:H thin films are coupled with the CFD simulation using a novel kinetic Monte Carlo scheme which describes the thin film growth, leading to a multiscale CFD model. Due to the significant computational challenges imposed by this multiscale CFD model, a parallel computation strategy is presented which allows for reduced processing time via the discretization of both the gas-phase mesh and microscopic thin film growth processes. Finally, the multiscale CFD model has been applied to the PECVD process at industrially relevant operating conditions revealing non-uniformities greater than 20% in the growth rate of amorphous silicon films across the radius of the wafer.

Multiscale Eulerian CFD of Chemical Processes: A Review

“…In the sequential coupling approach, model parameters required in the macroscale CFD were evaluated at smaller scales or vice versa. [13] KMC-CFD PECVD wafer Pozzetti, 2018 [99] DEM-VOF Three-phase flows with particles Da Rosa, 2018 [34] PBE-CFD Tubular crystallizer Qi, 2007 [100] EMMS-CFD Fluidized beds Li, 2018 [87] CSD-CFD Fluidized beds…”

“…Crose et al (2017) [13] developed a multiscale CFD framework in the plasma-enhanced chemical vapor deposition (PECVD) of thin-film solar cells. A macroscopic gas-phase transient 2D CFD model with plasma chemistry and transport phenomena was solved to calculate the pressure, velocity, temperature, and species concentration.…”

“…The multiscale CFD was capable of predicting the codependent behavior of the macroscopic gas phase and the microscopic thin-film growth rate. Using three user-defined functions (UDFs), including gas-phase reaction rates, an electron density profile in the gas phase, and a hybrid kinetic Monte Carlo (KMC) algorithm on the wafer surface, the macro-and microscale models were coupled at each time step [13]. The multiscale computing was parallelized within a message-passing interface (MPI) architecture to reduce the computational time.…”

“…Multiscale simulations cover quantum mechanics, molecular dynamics (MD), coarse-grained particle dynamics, and continuum mechanics [4,5]. Multiscale modeling in science and engineering couples several methods that produce the best predictions at each scale [6], which can then be applied to materials engineering [7], computational chemistry [8], systems biology [9,10], molecular biology [11], drug delivery [12], semiconductor manufacturing [13], reaction engineering [14], fluid flow [5,15], and process engineering [2,16,17].…”

Numerical Simulation Applied to PVD Reactors: An Overview

“…Crose et al [92] developed a multiscale CFD simulation model to study the PECVD of thin-film solar cells. In the manufacture of thin silicon films for solar cells and in the microelectronics industry, the commonly used method is PECVD because it has moderate operating temperatures and the costs associated with the process are low.…”