化學機械研磨之數值與實驗模擬研究

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Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/1805

Title:	化學機械研磨之數值與實驗模擬研究
Authors:	傅明南;Ming-Nan Fu
Contributors:	機械工程研究所
Keywords:	化學機械研磨;晶圓載具;研磨墊;研磨液;移除率;非均勻性;CCD 攝影機;灰階度;Chemical mechanical polishing;Slurry;Wafer carrier;Polishing pad;Removal rate;Nonuniformity;CCD camera;Gray scale
Date:	2000-10-01
Issue Date:	2009-09-21 11:32:12 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	研磨墊間極小的間隙內對晶片上的薄膜進行均勻性的研磨動作。而本論文的研究是著重在化學機械研磨製程流場的研究，包括數值模擬及實驗研究兩部份。首先，於數值模擬方面；提出三維流場模擬研磨液在化學機械研磨製程的流動特性。由於研磨速率與研磨液在晶圓表面上的剪應力有關，因此，可利用電腦模擬出化學機械研磨流場變化的剪應力分析晶圓表面上的移除率及非均勻性。結果顯示在晶圓表面上的剪應力及非均勻性與現今之移除率及非均勻性的實驗數據有相同趨勢，而且此結果更符合使用較硬研磨墊的研磨情況，本文的貢獻在於首次預測出在相同旋轉速度當晶圓尺寸較大時而非均勻性較小，這說明為何12吋晶圓可用較高的旋轉速度。至於實驗研究方面；本文的貢獻在於首次提出一研磨液注入位置與注入流量的通用最佳化，本最佳化方法適用於研究CMP製程中各種操作參數性能，建立四個不同操作參數分別為研磨墊轉速、研磨液注入位置、晶圓轉速、研磨液質量流率個別參數之影響。並量測研磨液在不同注入位置與不同轉速下進入間隙的量與分佈，並找出最佳的注入位置與注入量。並製作一CMP流場模擬機，使用一玻璃圓盤取代晶圓如此便能作流場觀測及影像處理，至於研磨墊則使用Rodel SUBA 400及Rodel POLITEX DG等兩種研磨墊，而光源則使用汞弧燈，並使用CCD攝影機取像，另將採用灰階度（Gray Scale）方法將CCD影像圖由影像擷取軟體處理。結果顯示在最佳注入位置與注入量，有較高移除率及較低非均勻性；並與上述電腦數值模擬比較，顯示兩者有相同趨勢結果，進而顯示在軟的研磨墊較硬的研磨墊之移除率為低，但其非均勻性較低。 Slurry is often used in CMP process as a polishing additive. The wafer carrier applies certain pressure on the wafer toward the pad. The slurry injected on the pad will be dragged into the narrow gap between the wafer and pad by the rotation of pad and wafer carrier during the polishing process. The dissertation primarily focuses on the study of the slurry transports on the pad surface and in the region between the pad and wafer. Both numerical simulation and experimental study are included in the work. First part is the numerical simulation. We present a three-dimensional fluid dynamics simulation for chemical mechanical planarization (CMP) processes. The slurry shearing stress on the wafer surface is usually considered to be closely related to the polishing rate. To our knowledge, this is the first work to address the wafer-scale removal rate and nonuniformity based on flow simulation. The simulation results for the trends of wafer-scale-averaged slurry shearing stress and nonuniformity agree with those of existing removal rates and nonuniformity data. The present simulation can be used to analyze or predict the characteristics of removal rate and nonuniformity in the CMP processes particular in those hard pad materials. The present predictions show that the nonuniformity value decreases with increasing wafer diameter for a fixed set of pad and wafer rotation speeds. This may explain why the recent CMP work for 12-inch wafer may operate at a high pad rotation speed. Again, the present experimental study is the first work to investigate the theological properties of the slurry between the pad and wafer by an optical technique to find out the optimum condition for slurry injection position and injection rate so that a high removal rate and uniformity can be obtained. The four chosen working parameters of the CMP include the pad rotation speed, slurry injection position, wafer rotation speed, and slurry mass flow. A CMP simulator will be used to study the slurry transports on the surface of pad and in the gap between the wafer and pad. A glass wafer that is transparent to visible light will be used instead of silicon wafer. A Rodel Suba 400 pad with 27” diameter and a Rodel Politex DG pad with 22” diameter will be used as the polishing pad. Commercially available slurry will be used. In the slurry, there are a lot of nano-particles, which will reflect the light imposed. A mercury-arc lamp with wavelength of 4046.56 Å will be used as the light source. A CCD camera will be used to capture the resulting reflected light from the slurry in the inter-pad-wafer region. By the use of image processing technique, a 256 gray-scale-level image of the slurry flow can be generated. The simulation results of wafer-scale-averaged slurry shearing stress and nonuniformity also agree in trend with the data of mean gray scale and nonuniformity for a 200 mm wafer. The present flow diagnostics technique can be further used for the optimization of slurry injection rate and injection position to obtain a higher removal rate as well as a low nonuniformity.
Appears in Collections:	[Graduate Institute of Mechanical Engineering] Electronic Thesis & Dissertation

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