化學氣相反應室內高溫基板對於流場影響之研究

Abstract

化學氣相沉積技術為半導體薄膜成長的主要技術。薄膜成長的好壞取決於沉積反應的均勻度，因此，基板上的流場分布便相當重要。本文以實驗的方式，建立實體CVD腔體，配合流場可視化技術，改變進氣高度、進氣與基板溫度差、基板轉速，觀察在不同實驗條件下，流場的分布情形。實驗操作主要參數:多孔式噴灑頭直徑190mm，基板直徑152.4，方形反應腔尺寸為280mm，進氣流量為15slm，進氣高度為20mm、40mm，進氣與基板溫度差為0°C-500°C，基板轉速從0rpm-500rpm，腔體壓力為常壓。研究結果發現，增加基板轉速可有效抑制熱浮力效應，但基板轉速過高，在靠近壁面處與基板上產生旋轉渦流。降低進氣高度明顯降低熱浮力效應與旋轉效應，當進氣高度從40mm降為20mm時，基板上方不會出現熱浮力渦流與旋轉渦流。隨著基板溫度上升，氣體黏滯力也會上升，旋轉雷諾數下降，將降低旋轉效應對流場的作用力。

Chemical vapor deposition (CVD) is widely used for manufacturing semiconductor materials and thin-films. The flow field influences the uniformity in the deposition process. The study build a test chamber for gas flow visualization experiments. The investigated parameters, include the showerhead-to-disk temperature difference (0-500°C), disk rotational speeds (0-500rpm), and showerhead-to-disk height (20-40mm). The result shows that buoyancy-induced recirculation can be suppressed by disk rotation. When disk rotational speeds increase, vortexes form near the chamber wall and on the disk simultaneously. When showerhead-to-disk height reduces, buoyancy-induced flow and rotation-induced flow are suppressed. When showerhead-to-disk temperature increases, viscous force also increases. Therefore, the effect of rotation decrease.