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Analysis of Wafer Abrasive-Free Polishing Process
Lin, Kun Lung
|關鍵字:||CMP;化學機械研磨;Polishing pad;Mass Transport;abrasive-free polishing(AFP);Reynolds equation;研磨墊;質量傳遞;無磨粒拋光;雷諾方程式||出版社:||機械工程學系||摘要:||
無磨粒化學機械研磨(Abrasive-Free Polishing, AFP)不同於一般化學機械研磨(Chemical Mechanical Polishing, CMP)的平坦化技術，其主要避免磨粒(Abrasive)於動態研磨中進行機械性磨耗而導致刮痕缺陷。本研究主要針對無磨粒化學機械研磨中之磨漿液動及化學反應建立理論模式與模擬分析。我們利用無因次化(Dimensionless Groups)數學模式建立二維理論架構，再經數值模擬分析磨漿流體的運動軌跡及氧化劑濃度隨流場對流擴散的分佈，其中考慮液體薄膜流經晶圓與研磨墊間的平衡問題，再依化學動力學(Chemical Kinetics)之速率定律(Reaction Rate Law)來推導磨漿化學反應的部分。
AFP對銅膜進行移除製程，其表面受化學與機械的作用可區分兩個階段。第一階段是氧化劑(Oxidizer)隨磨漿(Slurry)流場探討質量傳遞(Mass Transport)問題且與銅膜(Copper Film)進行反應使得部份形成為鈍化層(Reacted Layer)，第二階段是利用機械磨耗對銅膜層與鈍化層同時進行移除動作。我們分析磨漿成分、擴散速率、化學反應速率參數等化學性質對晶圓銅膜移除率及平坦化的影響。本文亦對晶圓載具的集中負載與研磨墊轉速，在分別不同的參數對移除率作探討。
Abrasive-Free Polishing (AFP) , which mainly focuses on avoiding shear marks caused by mechanical abrasion from abrasives during the dynamic polishing process, is a planarization technology which is quite different from ordinary Chemical Mechanical Polishing (CMP). The purpose of this study is to establish a theoretical model and simulation analysis for slurry hydrodynamics and chemical reactions during AFP and CMP. We constructed a two-dimensional model of dimensionless form to analyze the motion of slurry fluid and the distribution of oxidizer concentration caused by convection and diffusion in the flow field. During the process, the problems associated with liquid film between the wafer and the polishing pad were included into consideration. Reaction rate law of chemical kinetics was then applied to take the chemical reactions of the slurry into account.
When AFP was used for the removal process of copper film, the chemical and mechanical effects on the surface can be classified into two stages. The first stage involves mass transport with the oxidizer in the slurry flow field as well as part of the copper film reacting with the oxidizer forming reacted layer. The second stage is to remove the copper film layer and reacted layer simultaneously with mechanical abrasion. We analyzed the effects of the chemical properties, such as the content of slurry, diffusion rate, parameters of chemical reaction rate, on the removal rate of copper film and planarization of the wafer. The effects on removal rate due to the down force acting on the wafer and the rotation speed are also discussed in detail.
|Appears in Collections:||機械工程學系所|
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