CMP製程終點檢測系統之研究與應用

Abstract

在半導體製程技術進入毫微米製程之後，晶圓所需求的平坦度非常的重要，而化學機械研磨（Chemical Mechanical Polishing；CMP）是少數能提供全面性表面平坦化（Global Surface Planarization）的重點技術之一。然而在實用階段上，這項技術還受限於一些製程系統整合上的問題，其中有效的即時製程終點檢測系統（In-situ Endpoint Detection System）是影響CMP製程成效的重要關鍵。若未能有效地監測CMP運作，便無法避免晶圓產生研磨過度或不足的情況發生。本研究經評估後考慮採用雷射位移計裝設在CMP研磨機台特定機構上直接偵測晶圓研磨時的振動訊號，並使用快速傅立葉轉換法（Fast Fourier Transform；FFT）將振動訊號轉換成頻譜而加以解析。從偵測晶圓表面情況與振動頻譜間兩者的關係，歸納出晶圓研磨時產生的各種頻譜所代表的意義，進而發展出一即時CMP製程終點檢測系統。本研究利用系統參數分析，建立敏感、穩定的信號觀測機制，藉助CMP模擬機台與半導體工業級CMP機台實際擷取信號數據與實際研磨成品測試資料，驗證出本研究所規劃與建立系統的實用與可靠性。

In the time when semiconductor production has been promoted into nano process, it is very highly important for achieving planarization of the wafer surface. Up to now, only Chemical Mechanical Polishing（CMP）is the new technical solution to achieve global surface planarization in wafer production. However, this latest technology is still limited to the integration problem in production system. The most obviously of all, it need one efficient In-situ Endpoint Detection System to monitor CMP operation to avoid polishing over or not polishing completely. After evaluation, this research is considered to use laser displacement sensor on CMP to detect small vibrations of the polishing head and furthermore to use Fast Fourier Transform (FFT) to find the spectrum of vibrations for further analysis. Based on this analysis for realizing the related link between wafer surface and spectrum, we can determine polishing events. Accordingly, to develop In-situ Endpoint Detection System is the goal of this research.