垂直式CVD反應器內暫態流場之數值模型

Abstract

本論文以數值方法討論在一大尺寸的垂直式化學氣相沉積(Chemical Vapor Deposition簡稱CVD)反應器內，晶座的加熱及旋轉對暫態速度 場和溫度場所產生的影響。暫態連續、動量及能量等統禦方程式是建 立在非正交曲線座標及非交錯式安排的網格點上，利用有限體積法將 方程式離散化，再以 SIMPLE的數值方法求解速度和壓力方程式。 當晶座固定不動，此時加熱晶座將產生浮力效應而在晶座上方生 成一個順針方向旋轉的較大迴流，因而大大降低了晶座表面上的熱傳 量且造成較不均勻的熱傳，若將晶座維持在高溫(937K)來檢視由晶座 旋轉所造成之效應，結果顯示在晶座邊緣和反應器壁間會產生一個逆 時針方向旋轉的較小迴流，這會將原先因浮力造成的迴流往上推並減 低了晶座上方的邊界層厚度，增強了晶座表面的熱傳。此類流場的行 為與 Richardson number(Gr/Re2)與Rotational number(Rn)等無因 次參數有關。在完全相同的操作條件下有可能會出現多重的穩態解， 其解將取決於流場的起始條件及操作的程序等因素。

This study is concerned with numerical method to study the transient flow structures as well as the temperature fields int he large-size vertical CVD reactors and find out how they are influenced by the heating and rotation of the susceptor. the unsteady Navier-Stokes equations along with the continuity and energy equations are constructed on curvilinear coordinates and non-staggered grids. Equations are discretized using finite-volume method. The system of discretized equations are solved by the SIMPLE-type algorithm. The results show that the susceptor heating may cause a large-size clockwise recirculation abov the susceptor and reduce the heat transfer. Rotation of the susceptor at a high susceptor temperature 973 K leads to the formation of a small-size counter-clockwise eddy near the reactor wall, reducing the boundary layer thickness and enhances the heat transfer. The flow behavior can be related to the Richardson number G4/Re2 and rotational number Rn. Multiple solutions may arise for hte same operation parameters when steady state is approached. Therefore, the final flow field depends on the initial condition, operation procedure etc.