電鍍鎳膜及Ni3Sn4介金屬化合物之反算測定

隨著覆晶構裝技術的進步及晶片效率的提升，溫度問題逐漸成為一重要之議題。晶片工作時的高溫會使得具有不同熱膨脹係數(thermal expansion coefficient, CTE)之晶片與基板間造成變形，而變形產生的巨大應力會成為I/O連結處破壞的主因之一。數值方法的模擬常使用在這類構裝體之可靠度分析上，但欲準確預測應力分佈的情形，我們必須對建構起I/O連結處材料的機械性質有正確的掌握。凸塊底層金屬(under-bump metallization)由多層金屬薄膜組成，而金屬薄膜往往因為成長方式展現出與塊材不同之機械性質；此外，這些金屬薄膜在與銲錫凸塊回銲過程中亦會產生薄且脆之介金屬化合物(Intermetallic Compounds, IMC)。這些材料僅有數微米之厚度因此量測不易，但卻在構裝分析上佔有重要份量。有鑑於此，本文的目的即在發展出一套反算系統以偵測出以鎳為主之金屬薄膜及其介金屬化合物之機械性質。本文中，將建立起電鍍Ni/Si、Ni3Sn4/Ni/Si、Ni3Sn4/Ni Foil等多層結構試片，透過光學量測技術配合有限元素模型及遺傳演算法可同時得到待求材料之楊式模數(Young’s Modulus)及熱膨脹係數。而透過反算之結果，將從研究文獻、材料理論等多重角度做一佐証及統整。由於電鍍鎳模及Ni3Sn4因成長方式造成之差異均有可能在構裝中有著決定性的影響，因此透過本文，期望未來在構裝體的應力分析上能夠提供更充足的材料參數。

關鍵字

介金屬化合物；機械性質；反算方法

並列摘要

With the improvement of filpchip technique and chip efficiency, temperature problem is becoming an important issue. When chip is working, the high temperature easily causes the packaging to deform because chip and substrate have different thermal expansion coefficients (CTE), and the high stress resulting from the deformation will make I/O connections fracture. Numerical methods have been widely used to analysis the stress distribution and to predict the reliability of packaging, but only if the material properties of these connections are known can we predict the stress distribution very precisely. Under-bump metallization (UBM) consists of many metal thin films, and these metal films often exhibit different mechanical properties from those of their bulk materials. Furthermore, during reflow process, UBM will react with solder bump to form a hard and brittle material-intermetallic compound (IMC). UBM and IMC are equally important in reliability analysis, but they are so thin that their properties are difficult to be measured. Therefore, the objective of this study is to develop an inverse method to detect the mechanical properties of nickel film and nickel IMC. In this study, specimens having multi-layer structure, such as Ni/Si, Ni3Sn4/Ni/Si, Ni3Sn4/Ni Foil, were produced. By using optical measurement technique and inverse method, which includes finite element method (FEM) and genetic algorithm (GA), the Young’s modulus and CTE of the unknown material can be obtained simultaneously. The inversely calculated results of Ni and Ni3Sn4 were also verified by relevant literatures and material theories. Various growing conditions of electroplated nickel or Ni3SN4 will result in different mechanical properties, and that also causes different effects on packaging. Hence, this study was expected to offer more data about Ni and Ni3Sn4 for the stress analysis of packaging.

並列關鍵字

Intermetallic Compound ； Mechanical Properties,Inverse Method

參考文獻

[27] 蔡怡庭, “無鉛覆晶構裝中薄膜與介金屬化合物機械性質之測定,” 國立台灣大學應力學研究所博士論文, 2006

[2] Flip Chip Packaging Technology Solution. http://www.amkor.com

[3] D.T. Read, “Young’s Modulus of Thin Films by Speckle Interferometry,” Meas.Sci.Technol., Vol.9, pp.676-685, 1998

[4] Siliconware Precision Industries Co., Ltd, http://www.spil.com.tw/en/electrical.html

[5] M. Chinmulgund, R.B. Inturi, and J.A. Barnard, “Effect of Ar gas pressure on growth, structure, and mechanical properties of sputtered Ti, Al, TiAl, andTi3AL Films,” Thin Solid Films, Vol.270, pp.260-263, 1995

國際替代計量

電鍍鎳膜及Ni3Sn4介金屬化合物之反算測定

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