應用曝光模擬系統以環形偏軸照明降低孤立線與密集線線寬偏差

Application of Exposure Simulation System to Reduce Isolated-Dense Bias by Using Annular Off-Axis Illumination

石宜男(Yi-Nan Shih)

指導教授 ： 陳念波

元智大學/電機通訊學院/電機工程學系/碩士(2007年)

摘要

當光學微影製程的最小圖形被推向比曝光波長還小的尺寸時，光學鄰近效應是一個最嚴重的問題。解決這問題的方法是使用光學鄰近修正或相位移光罩。然而，光學鄰近修正技術之關鍵取決於大量的光罩資料，而且製造零缺陷的相位移光罩不容易。雖然有不少人已經提出光學鄰近修正的方法以修正臨界尺寸誤差，但是光罩廠有製造光罩和檢驗光罩的困難。所以，如果可能的話較傾向不要用複雜的修正方法去減少臨界尺寸的變異。孤立線與密集線線寬偏差在 0.13 微米製程表現度的評估上變成關鍵的參數。為了改善解析度及聚焦深度，我們研究環形偏軸照明方法。將環形偏軸照明條件的最佳化以減少孤立線與密集線線寬偏差是必要的。照明的方法，投影透鏡的數值孔徑，相擾度可以改變孤立線與密集線線寬偏差。最後，在這照明方式的模擬分析，最佳的光學參數被選擇以獲得更高解析度及足夠的聚焦深度，尋找最佳製程條件以減少孤立線與密集線線寬偏差是有可能的。面對眾多的微影製程變因，不同製程相關參數之最佳化，將是微影製程成像技術成敗的關鍵。以電腦模擬配合田口實驗計劃法可經濟而有意義地面對眾多的變因進行研究。

關鍵字

光學鄰近效應 ； 孤立線與密集線線寬偏差 ； 環形 ； 偏軸照明

並列摘要

As the optical lithography is pushed into the smaller feature size below the exposure wavelength, the optical proximity effect (OPE) is one of the most serious problems. The way to solve this problem is to use optical proximity correction (OPC) or phase shift mask (PSM). However, the OPC technique crucially depends on the huge amount of mask data, and it is difficult to make the PSM with zero defects. Although many OPC methods have been proposed to correct critical dimension (CD) errors, mask makers have the difficulty in the mask fabrication and inspection. Therefore, it is preferable to reduce the CD variation without complicated correction methods, if possible. Isolated-Dense bias (IDB) is becoming a critical parameter in the evaluation of 0.13 μm process performance. In order to improve the resolution and the depth of focus (DOF), we investigated the annular off-axis illumination (OAI) method. Optimization of OAI conditions to reduce the IDB is essential. The methods of illumination, the numerical aperture (NA) of the projection lens, the degree of coherence (Sigma, σ) could change IDB. Finally, on the basis of the simulation analysis of the illumination method, the optimum optical parameters are selected to obtain the high resolution and enough DOF to reduce IDB value. Facing with many parameters in the lithography processes, the optimization is performed with the aid of Taguchi method. The method allows us to efficiently study the interaction among the parameters and obtain the optimal values.

並列關鍵字

optical proximity effect ； isolated dense bias ； annular ； off-axis illumination

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