水平處理器內加熱晶圓由浮力所驅動之混合對流渦漩流數值模擬研究

Abstract

本篇論文主要是在模擬水平處理器內，加熱八吋晶圓由浮力所驅動之空氣混合渦漩流。我們假設在矩形管道內底部晶圓保持等溫，採用CFD的商業套裝軟體CFX4.2來解三維暫態統御方程式，雷諾數 ( Reynolds number ) 的範圍從10到300 ，雷利數 ( Rayleigh number ) 由9萬到270萬 ，而且傾斜角由0度到4度。在流場穩定方面，底板傾斜與降低壓力的效應也有討論。主要的結果是在探討圓形的晶圓流場。但是一些方形晶圓的結果，亦有助於探討改變晶圓幾何對流場的影響。由本文所呈現出來的計算結果，顯示出在浮力與慣性力的比值超過某一個臨界值，在管道內就會產生迴流。繼續增加浮力與慣性力的比值，迴流的強度就會增強而且區域會擴大。若浮力與慣性力的比值超過第二個臨界值，那麼就會使下游的流體產生迴流。把明顯的二次流的關係找出來。再此，把迴流區域長度的關係找出來，再次強調傾斜晶圓與降低壓力，可以有效的降低渦流的強度。

Buoyancy driven mixed convection vortex air flow over an eight-inch heated wafer in a model horizontal processor is numerically simulated. The processor is approximated by a rectangular duct with the wafer at a given uniform temperature placed on its bottom. The governing three dimensional unsteady flow equations are solved by the commercial CFD software CFX4.2 for the Reynolds number ranging from 10 to 300, Rayleigh number from 90000 to 2700000 and tilting angle from 0。to 4。. Effects of the bottom plate tilting and pressure lowering on the stabilization of unstable vortex flow are also investigated. Results are mainly obtained for a circular wafer. But some results for a square wafer are also obtained to investigate the effects of the wafer geometry on the driven vortex flow. Results from the present computation show that as the buoyancy-to-inertia ratio exceeds certain critical level a reverse flow is induced in the duct. At increasing buoyancy-to-inertia ratio the reverse flow intensifies and grows in size. For the buoyancy-to-inertia ratio higher enough to exceed the second critical level, a downstream flow recirculation is also induced. Correlations for the appearance of these secondary flows are proposed. Moreover, the length of the reverse flow zone is correlated. It is also noted that the wafer inclination and pressure reduction can effectively weaken the vortex flow.