薄膜機械特性及殘留應力之反算偵測(1/3)

薄膜特有的僅僅微米等級的厚度可能導致其行為迥異於塊 材， 因此以非破壞的方式測定薄膜的楊式模數、熱膨脹係數、蒲松 比以及其厚度等， 一直是個困難但卻極重要的問題。在本報告中， 成功地展示了一次同時測定此四個參數的能力。這新穎的方法包含 以數位式相移反射疊紋法的技術，記錄降溫狀態下晶圓翹曲值的斜 率。當中的實驗使用6 英吋的矽晶圓鍍上厚度為1 微米的鋁。並以 數值方式使用傳統三維有限元素法建立量得資料與其機械性質間 的摺積關係， 最佳化求解則使用了遺傳演算法。Nondestructive determination of Young’s modulus, coefficient of thermal expansion, Poisson ratio, and thickness of a thin film has long been a difficult but important issue as the film of micrometer order thick might behave differently from that in the bulk state. In this report, we have successfully demonstrated the capability of determining all these four parameters at one time. This novel method includes use of the digital phase-shifting reflection moiré (DPRM) technique to record the slope of wafer warpage under temperature drop condition. In the experiment, 1-um thick aluminum was sputtered on a 6-in silicon wafer. The convolution relationship between the measured data and the mechanical properties was constructed numerically using the conventional 3D finite element code. The genetic algorithm (GA) was adopted as the searching tool for search of the optimal mechanical properties of the film