為了減少半導體薄膜塗佈製程中工作流體如光阻液的使用量，以及增進對旋轉塗佈過程中不穩定手指狀生成機制的瞭解，本文採用流體可視化實驗方法，記錄流體擴張過程中的歷史軌跡，從中可觀察到發現科氏力會使不穩定手指狀流偏離徑向，在轉動的反方向產生一個偏角的位移，實驗結果顯示此偏角之大小會隨著液膜擴張、邦德數 (Bond number) 和轉動雷諾數 (rotational Reynolds number)而改變，此結果與無因次參數分析相吻合，而最大偏角會出現當薄膜厚度接近艾克曼邊界厚度(Ekman Boundary layer) ，且角度的偏移會改變不穩定手指狀的形狀，使得最大塗佈面積增加。從無因次臨界半徑、邦德數及轉動雷諾數的關係圖中，可發現於高邦德數(Bo >500)的流體會因科氏力的作用，使流體趨於不穩定，但反而會使低邦德數(Bo<100)的流體變得更加穩定。此外，透過作用力之間的平衡關係，可得到一系列的特徵長度，利用特徵長度可成功簡化流場之變數，並探討不穩定手指狀之生成機制。 The effect of Coriolis force on the rivulet (fingering) instability, the onset of rivulet phenomena during spin coating, is investigated by flow visualization experiments incorporating with dimensional analysis. And a scaling law is provided to discover the forces relation during coating process. This study demonstrates that the Coriolis force do affect significantly the critical radius of rivulet instability, the deflection angle of instability rivulet and the maximum attainable radius of the coating films. From the onset of the effect of Coriolis force, the finger’s deflection angle increases rapidly with rotational Reynolds number Reω. The strongest effect of Coriolis force is seen to appear while the film height is closed to the Ekman boundary layer. For the cases of low Bond number, the effect of Coriolis force is a stabilizing factor, and the dimensionless critical radius increases slightly with increasing Reω. The finger’s base area develops into a triangular-like shape due to the changing of finger’s deflected angle. It results in the merging together of fingers, which in turn leads to the increase of maximum attainable radius. Finally, the scaling law successful provides several characteristic length scales which are balanced by the Coriolis force with the surface tension and the viscous force with the surface tension.
