| Summary: | 碩士 === 中華大學 === 機械與航太工程研究所 === 92 === Chemical vapor deposition (CVD) is one of the important techniques used in the semiconductor processes. The flow structure and heat transfer effect in a CVD reactor have significant impact on the uniformity and growth rate of the thin film. In the present study, numerical simulations are performed to investigate the effects of gas inlet velocity, operating pressure, and reactor geometry on flowfield structures and heat transfer rates in a horizontal CVD reactor with single wafer. The governing equations are the three-dimensional (3-D), incompressible Navier-Stokes equations with ideal gas law and temperature dependent viscosity as well as conductivity. A 3-D, non-uniform and staggered grid is adopted with an implicit finite volume formulation in accordance with the SIMPLEC-type algorithm.
Numerical results show that a return flow is induced as the gas flows through a bottom heated horizontal CVD reactor, due to the interactions between buoyant and inertial forces. The return flow region decreases as the inlet gas velocity increases for constant pressure conditions. For different operating pressures, the return flow region is reduced with decreasing pressure, and hence the film deposition uniformity is improved effectively. Effects of the tilted top and bottom walls on flow structures are also investigated. The return flow region and thermal boundary layer decrease as the tilted angle increases. The effectiveness is more pronounce with bottom wall inclination. In addition, a baffle is added to the top wall at several different positions to investigate its effect on flow structures. The addition of the baffle affects the position of return flow structure, but has no improvement on the uniformity of thin layer.
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