顏家鈺Yen, Jia-Yush臺灣大學:機械工程學研究所陳聯聖Chen, Lien-ShengLien-ShengChen2010-06-302018-06-282010-06-302018-06-282008U0001-1107200812575500http://ntur.lib.ntu.edu.tw//handle/246246/187377在本論文中，作者設計並實現了一套應用於製造大面積微米級週期性干涉條紋的複雜伺服系統。此系統主要包含了兩大子系統。其一為一個光源操控系統，此子系統是用來消除掉干涉用雷射光源與晶圓載台所在光學桌在長時間運作下之相對漂移。此系統利用廣泛採用的光束位置與角度解析法，分別量測出入射光在自訂平面上的位置與角度，並加以控制。實驗結果證實了此系統對低頻光束漂移的控制性能，在60秒的運作時間中，此系統可保證1.3 μrad的光源角度不穩定性以及0.16 μm的光源位置不穩定性(1標準差)。配合在文獻中提及的分析方法，此系統可保證干涉光所形成的條紋週期在此段時間內的不穩定性小於4.22 nm(1標準差)。另外一個重要的子系統為晶圓定位系統。此系統包含了一套雙致動器系統以及一套具有高頻寬及高精確度的雷射干涉儀量測系統。致動器包含了兩個交疊的線性定位平台以及一個三軸壓電致動高頻寬精密定位平台。由線性定位平台提供長行程但精確度僅到μm等級的定位，接著再由壓電平台將晶圓載台根據雷射干涉儀輸出的位置誤差微調到位。系統性能主要由兩個因素所決定：平均定位精準度以及穩態殘餘震動。作者簡單地研究了壓電致動載台之共振頻以及其與載重之關連性，並解釋壓電平台穩定性的限制。在此系統中使用的特殊伺服架構，包含了一以硬體實現之高速嵌入式伺服系統以及一以軟體實現、頻寬較低但由高精度雷射干涉儀作位置回饋的伺服系統。此干涉儀之位置訊號先經過一特定的濾波器後才送入伺服系統中，以避免系統對高頻的震動做出錯誤反應。軟體實現之伺服系統的頻寬以及濾波器的截止頻率均經過設計以達到最佳效能。實驗證實了小於5 nm之X及Y軸的平均定位誤差，以及小於100 nrad的平均旋轉角度誤差。殘餘不穩定性則證實了在20 nm(X、Y)以及310 nrad(θ)以內(1標準差)。此外，本論文討論一種出現在此應用中，且對本系統有極大影響的誤差。此誤差為光學座標系統與晶圓定位用座標系統之夾角，本論文提出一量測並修正此誤差的方式。根據量測結果發現，此誤差角度達到3478.50 μrad的平均值，量測誤差之上限估計為24.92 μrad。際使用1025 nm及551 nm週期的曝光及條紋接合實驗結果以顯微儀器如光學顯微鏡觀察，可觀察到條紋錯位程度的改善。首先檢視了在兩次曝光區域的交界處並且實際觀察因定位誤差造成的條紋錯位。接著在兩次曝光疊合的區域觀察到因曝光能量過多而使條紋對比度嚴重下降的結果，因此採用能儘量達成「零疊合區」並又同時能使條紋保持連續性的方式來進行曝光區的接合。本論文最後並呈現了成功在整片四吋晶圓上佈滿1025 nm週期性干涉條紋的結果。In this thesis, we have designed and implemented a complex servo system for stitching interference gratings over large area which mainly included two sub-systems. One of them is the so-called beam steering system, which eliminates low frequency position and angle drifting of the incoming beam. Experimental results have shown less than 1.3 μrad beam angle instability and 0.16 μm position instability during sixty seconds time duration (1σ). And combined with analysis given in existed literature, 4.22 nm of fringe period variation (1σ) during this period is guaranteed.he other sub-system which has even more crucial influence on stitching results is the wafer positioning system. We have implemented a dual-stage actuating system, in which one is responsible for long stroke coarse positioning over a two dimensional plane (the motor stages) and the other one (the PZT stage) provides short-range high-bandwidth fine precision positioning. Performance is found to be limited by two factors: positioning accuracy and steady state residual instability. A brief study of how external loads of the PZT stage influence its resonant frequency and therefore have impacts on stage instability is initiated. Special servo architecture used in this system is introduced, in which a high-bandwidth controller is running in the front end and a servo system based on global high-accuracy interferometer measurement is running in back end. The high-update-rate signal is processed by a digitally-implemented low-pass filter to avoid over-reacting of the PZT stage. The design process of this filter and the fine servo rate of the PZT stage are described. Experimental challenges are initiated to verify system performance. Averaged positioning errors are found to be less than 5 nm in two linear axes and 100 nrad in rotational axis, and steady-state instabilities are less than 20 nm in X- and Y-directions and 310 nrad in θ-direction respectively, 1σ. Also, a special angular error due to error-alignment of optical and positioning coordinate axes is explained, and a measurement and correction method is proposed. The average measurement result of this angle is 3478.50 μrad with 24.92 μrad error bound.xposure and fringe-stitching experiments with both 1025 nm and 551 nm fringe period are executed and experimental results are observed by employing micrographic tools. Positioning errors can be observed directly in micrographs near stitching edges and greatly improved with the wafer positioning system. Overlapping area of exposures has to be minimized since contrast loss is severe in these areas. Optimal “zero-overlapping” step sizes in X- and Y-directions are found experimentally.inally, full four inch wafer fringe-stitching with 1025 nm grating period is initiated successfully and results are present.Abstract ...............................................IIIable of Contents ........................................Vist of Figures .........................................IXist of Tables ..........................................XVhapter 1 Introduction...................................1.1 Motivations......................................1.2 Fabrication Methods and Literature Review........3.3 System Implementation Concept....................8.4 Contributions and Thesis Structure..............14hapter 2 Beam Steering / Stabilization System..........17.1 Beam Stability Requirements Analysis............18.2 Concepts of Steering the Laser Beam.............23.3 System Architecture and Setup...................29.4 Control Strategies..............................32.4.1 Iterative Converging Method.....................38.4.2 Servo Rate and PSD Signal Filtering.............40.4.3 Servo Routines..................................46.5 Experiments.....................................50hapter 3 Wafer Positioning System......................57.1 System Architecture.............................58.1.1 Actuators and Assembly..........................58.1.2 Wafer and Interferometer Mirror Holding Device..62.1.3 Laser Interferometer Measurement System.........65.2 A Study on PZT Stage Stability versus External Loads....................................................71.3 Servo System Design and Servo Routines..........83.4 Performance Evaluation and Discussion...........89hapter 4 Experimental Results and Discussion..........101.1 Verification of Grating Stitching..............101.2 Impact of Exposure Area Overlapping on Grating Contrast................................................105.3 Path Planning and Full-Wafer Stitching.........109hapter 5 Conclusions and Future Works.................113eference...............................................11511973110 bytesapplication/pdfen-US干涉微影術干涉條紋接合光源操控晶圓定位伺服系統大面積週期性微結構interference lithographyinterference fringe stitchingbeam steeringwafer positioningservo systemlarge area periodic microstructuresthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/187377/1/ntu-97-R95522810-1.pdf