Numerical Simulation of the Transport of Gas Species in the PVT Growth of Single-Crystal SiC

Abstract

Single-crystal silicon carbide (SiC) is an important semiconductor material for the fabrication of power and radio frequency (RF) devices. The major technique for growing single-crystal SiC is the so-called physical vapor transport (PVT) method, in which not only the thermal field but also the fluid-flow field and the distribution of gas species can be hardly measured directly. In this study, a multi-component flow model is proposed that includes the inside and outside of a growth chamber and a joint between the seed crystal holder and crucible which allows exchanges of the gas species. The joint is simulated as a thin porous graphite sheet. The Hertz-Knudsen equation is used to describe the sublimation and deposition. The convection and diffusion are described by the Navier–Stokes equations and mixture-averaged diffusion model, in which the Stefan flow is taken into account. The numerical simulations are conducted by the finite element method (FEM) with a multi-physics coupled model, which is able to predict the fluid flow field, species distribution field, crystal growth rate, and evolution of the molar concentration of dopant gas. Using this model, the effects of several experimental conditions on the transport of gas species and the growth rate of single-crystal SiC are analyzed.