垂直CVD反應爐內流場及熱傳之數值研究

Abstract

本篇論文在研究垂直單晶化學氣相沈積反應壚內流場及熱傳的三維暫態數值模擬。我們使用CFX4.2這套套裝軟體來解這些問題的方程式。我們集中注意在由於溫度不均而產生的慣性力和浮力在沿著整流板（Showerhead）和進氣管的幾何外型於反應爐內的流場分佈。在反應壚內理想的均勻進氣預測到的流場結果指出，在剛開始時浮力可以導致在晶圓邊緣上方產生一對稱的圓柱之渦流卷。這對渦流的大小及強度都在迅速地成長。當浮力與慣性力的比值提高時流場變得非常不軸對稱。然而，混合區和整流板在渦流場上也有很多的影響。當氣體經由一直的圓管進入時，由於一高速噴流導致一個大而弱的渦流卷。除此之外，浮力可以導致一個強的渦流卷佔滿了反應爐內，並當浮力和慣性力的比值增加時，亦可造成一個較強的渦流強度和許多的不對稱回旋流產生。最後我們注意在一彎的單管所造成不對稱的流場之探討。

A transient three-dimensional numerical simulation was carried out in the present study to investigate the flow and thermal characteristics in a model vertical single-wafer chemical vapor deposition reactor without considering the chemical reactions. The commercial software CFX4.2 was adopted to solve the governing flow equations. Attention was focused on the effects of the flow inertia and buoyancy due to the temperature nonuniformity along with the showerhead and geometry of the gas inlet pipe on the resulting flow pattern in the reaction chamber. The predicted results for the ideal case with a uniform gas flow at the inlet of the reaction chamber indicate that the buoyancy can induce an exisymmetric circular vortex roll near the dege of the wafer in the early transient. The vortex roll grows quickly in intensity and size. For a raise in the buoyancy-to-inertia ratio the flow becomes nonaxisymmetric. Moreover, the mixing chamber and showerhead were found to exert profound influences on the vortes flow pattern. When the gas enters the reaction chamber through a single straight circular pipe, the entraining effects of the high speed gas jet result in a large but weak circular vortex roll outside the jet. Besides, the buoyancy can induce strong vortex rolls which prevail in the reaction chamber. An increase in the buoyancy-to-intertia ratio in a higher vortex intensity and multiple asymmmetric flow recirculations may appear. Finally, it was noted that the bending of the inlet pipe cause some flow asymmetry.