Development of a model for high precursor conversion efficiency pulsed-pressure chemical vapor deposition (PP-CVD) processing

Abstract

A model of the movement of precursor particles in the unsteady Pulsed-Pressure Chemical Vapour Deposition (PP-CVD) process is developed to study the high conversion efficiencies observed experimentally in this process. Verification of the modelling procedures was conducted through a study of velocity persistence in an equilibrium gas and through Direct Simulation Monte Carlo (DSMC) simulations of unsteady self-diffusion processes.The model results demonstrate that in the PP-CVD process the arrival time for precursor particles at the deposition surface is much less than the reactor pump-down time, resulting in high precursor conversion efficiencies. Higher conversion efficiency was found to correlate with smaller size solvent molecules and moderate reactor peak pressure.

Scale-up design for industrial development of a PP-MOCVD coating system

“…PP-MOCVD is distinguished from other MOCVD approaches in that it does not use a steady flow of carrier gas to transport low volatility precursor to the substrate [21]. The expansion of the precursor and solvent vapour into the evacuated reactor volume results in a well-mixed reactor condition [22], which in turn can result in mass-transport limited growth and potentially high deposition efficiency, sufficient thickness, and reasonable processing time [23]. The well-mixed reactor condition means that a relatively simple modelling approach to the deposition kinetics can be considered [20].…”

Process-Induced Nanostructures on Anatase Single Crystals via Pulsed-Pressure MOCVD

“…At high temperatures (>500 • C) the reactor works in the mass-transport controlled regime with high precursor-arrival rate to the substrate surface during the peak of the pressure pulse [20]. The pulsed-pressure cycle is typically 6 seconds with less than 0.5 seconds of pressure rise, and 5 seconds of pump-down [21]. The pp-MOCVD process reduces the reactor and substrate geometry effects on the deposition, making it a versatile technique to coat 3D objects.…”

Multi-Species Fluxes for the Parallel Quiet Direct Simulation (QDS) Method

“…Pulsed Pressure CVD (PP-CVD) is a novel CVD technique conceived by Versteeg et al [5] which has demonstrated improved film quality and substrate conformity over traditional CVD methods [6], as well as demonstrating high precursor conversion efficiency [7]. A heavy reactive molecule at low mole fraction in an inert carrier vapour is injected into an evacuated chamber ( Figure 1).…”