薄膜/基質系統中殘餘應力的邊際效應

The Edge Effects on the Residual Stresses in a Thin Film/Substrate System

井民安(Min-An Jing)

指導教授 ： 余念一

元智大學/工程學院/機械工程學系/碩士(2004年)

摘要

在薄膜長成過程，不協調的應變可由於薄膜與基質的熱膨脹係數不協調所產生，不但導致晶格的不協調與差排的移動而且也造成殘餘應力的發生。本研究執行有限元素分析並發展一可析解模型探討薄膜邊際效應在一個薄膜/基質系統中對殘餘應力的分佈。現存的解析解模型包含了許多的假設與近似估計，因此在磊晶/晶圓系統的殘餘應力上提供了不正確的預測值，特別在靠近薄膜邊的區域。所以發展一個估計薄膜/基質系統中殘餘應力的邊際效應的有效模式是我們目前的工作。
目前的有限元素分析結果被用來與現存的解析與有限元素結果驗證。我們得知薄膜的殘餘應力是一個薄膜、基質的材料性質與幾何尺寸的函數。在距離薄膜邊際一定距離以外的基質的應力是均勻的。薄膜與基質兩者的應力在薄膜邊際變化極為顯著。

關鍵字

薄膜 ； 基質

並列摘要

During an epitaxial process, misfit strains due to the mismatch of coefficient of thermal expansion (CTE) are developed in the film and the substrate, leading to lattice mismatch and dislocation movement as well as residual stresses. A finite element analysis (FEA) and an analytic model are presented to study the film-edge effects on the residual stress distribution in a thin film/substrate system. The existing analytical models involve many assumptions and approximations and therefore, provide inaccurate predictions on the residual stress distribution in an epilayer/wafer system, particularly in the area near the film edge. Therefore developing an effective model for estimating the edge effects on the residual stresses in a thin film/substrate system is the immediate objective of the present work.
The results obtained by the present FEA and the analytic model are benchmarked with those obtained by the existing analytical and computational works. It is concluded that residual film stresses are functions of material properties and geometry of film and substrate. The stresses in the substrate are uniform outside a certain distance from the film edge. Both the film and the substrate stresses vary significantly near the film edge.

並列關鍵字

thin film ； substrate

參考文獻

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