Visualization and Numerical Simulation of Rarefied Gas Flow in Vertical Low-Pressure CVD Reactors for Thin Film Formation of Semiconductors

Abstract

The paper investigates the flow characteristics of reactant gas on the silicon wafers in a vertical LPCVD (Low-Pressure Chemical Vapor Deposition) reactor by the flow visualization and the numerical simulation. The observation was made in a model reactor in a very low-pressure condition, which makes the observation quite difficult because of tracer seeding. The CFD code FLUENT was used for the numerical simulation. The results of the visualization and the numerical simulation showed that the gas flow was quite viscous and it received large resistance force from the wafers and the supporting lodes. Regardless of the low-pressure condition, the flow can be treated as continuous system and can be simulated well by the CFD code based on Navier-Stokes equation. It shows that the most of the field appeared to be laminar. For the establishment of the uniform flow pattern, twin counter-flow nozzles were better than a single nozzle. The flow was free from stagnant flow or re-circulating flow so that it appeared to be suited for the prevention of particle formations.