基于空间分光的纳米级调焦调平测量技术
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摘要
随着半导体制造步入1xnm技术节点时代,调焦调平系统的测量精度达到几十纳米。在纳米尺度范围内,集成电路(IC)工艺对调焦调平测量精度的影响很大。提出一种基于光学三角法和叠栅条纹法的调焦调平测量技术,利用空间分光系统将两组位相差为π的叠栅条纹同时成像到两个探测器上,通过归一化差分的方法计算硅片高度,可有效降低调焦调平测量技术对IC工艺的敏感度,尤其是IC工艺导致的光强变化的敏感性。实验结果表明,该系统测量重复性精度为8nm(3σ),线性精度为18nm(3σ)。当测量光强变化达90%时,该测量技术引起的线性精度变化为15nm(3σ);当光强变化为65%时,线性精度变化小于1nm(3σ)。
With the development of semiconductor manufacturing to 1xnm technological node,the measurement accuracy of the focusing and leveling system is down to several tens of nanometers.In the range of nanoscale,integrated circuit(IC)process plays an important impact on the measurement accuracy of the focusing and leveling system.A kind of focusing and leveling measurement technology based on optical triangulation and moiréfringes method is proposed.Two sets of moiréfringes withπphase difference are imaged onto two detectors using the spatial splitting system.The height of wafer is calculated by normalized differential method.The sensitivity of the system on the IC process,especially on the light intensity fluctuations is reduced.Experimental results show that the measurement repeatability of the system is 8nm(3σ)and the linear accuracy is 18nm(3σ).When the light intensity fluctuates 90%,the linear accuracy changes 15nm(3σ).When the light intensity fluctuates 65%,the linear accuracy changes less than 1nm(3σ).
With the development of semiconductor manufacturing to 1xnm technological node,the measurement accuracy of the focusing and leveling system is down to several tens of nanometers.In the range of nanoscale,integrated circuit(IC)process plays an important impact on the measurement accuracy of the focusing and leveling system.A kind of focusing and leveling measurement technology based on optical triangulation and moiréfringes method is proposed.Two sets of moiréfringes withπphase difference are imaged onto two detectors using the spatial splitting system.The height of wafer is calculated by normalized differential method.The sensitivity of the system on the IC process,especially on the light intensity fluctuations is reduced.Experimental results show that the measurement repeatability of the system is 8nm(3σ)and the linear accuracy is 18nm(3σ).When the light intensity fluctuates 90%,the linear accuracy changes 15nm(3σ).When the light intensity fluctuates 65%,the linear accuracy changes less than 1nm(3σ).
引文
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17 Cao Shaoqian,Bu Yang,Wang Xiangzhao,et al..Measurement technique for the Mueller matrix based on a single photoelastic modulator[J].Acta Optica Sinica,2013,33(1):0112006.曹绍谦,步扬,王向朝,等.基于单光弹调制器的米勒矩阵测量技术[J].光学学报,2013,33(1):0112006.
2 Paolo Alagna,Omar Zurita,Vadim Timoshkov,et al..Optimum ArFi light source bandwidth for 10nm node logic imaging performance[C].SPIE,2015,9426:942609.
3 Igor Bouchoms,Martijn Leenders,Jan Jaap Kuit,et al..Extending 1.35 NA immersion lithography down to 1xnm production nodes[C].SPIE,2012,8326:83260L.
4 Zeng Aijun,Wang Xiangzhao,Xu Deyan.Progress in focus and level sensor for projection lithography system[J].Laser&Optoelectronics Progress,2004,41(7):24-30.曾爱军,王向朝,徐德衍.投影光刻机调焦调平传感技术的研究进展[J].激光与光电子学进展,2004,41(7):24-30.
5 Shu Huer Hou,Edgar Huang,Aroma Tseng,et al..Improvement of the common DoF across field for hole-structure process layers[C].SPIE,2008,6924:692434.
6 Bernhard Liegl,Allen Gabor,Golin Brodsky,et al..Measuring layer-specific depth-of-focus requirement[C].SPIE,2008,6924:69244J.
7 Yasuhiro Hidaka,Kiyoshi Uchikawa,Daniel G Smith.Error analysis and compensation method of focus detection in exposure apparatus[J].J Opc Soc Am A,2009,26(1):10-18.
8 Takenobu Kobayashi,Yuji Kosugi.Surface position measuring method and apparatus:US,7668343B2[P].2010-02-23.
9 Theodorus Marinus Modderman,Gerrit Johannes Nijmeijer,Johannes Christiaan Maria Jasper.Off-axisleveling in lithographic projection apparatus:US,7206058B2[P].2007-04-17.
10 Arie Jeffrey Den Boef,Jozef Petrus Henricus Benschop,Ralph Brinkhof,et al..Level sensor,lithographic apparatus,and substrate surface positioning method:US,2013/0077079A1[P].2013-03-28.
11 J E van der Werf.Optical focus and level sensor for wafer steppers[J].J Vac Sci Technol B,1992,10(2):735-740.
12 Feng Jinhua,Hu Song,Li Yanli,et al..Nano focusing method based on moire fringe phase analysis[J].Acta Optica Sinica,2015,35(2):0212005.冯金花,胡松,李艳丽,等.基于叠栅条纹相位解析的纳米调焦调平方法[J].光学学报,2015,35(2):0212005.
13 Hu Jianming,Zeng Aijun,Wang Xiangzhao.Polarization modulation technology for a position sensor with grating imaging[J].Chinese J Lasers,2006,33(10):1397-1401.胡建明,曾爱军,王向朝.光栅成像位置传感器中的偏振调制技术[J].中国激光,2006,33(10):1397-1401.
14 Yan Wei,Li Yanli,Chen Mingyong,et al..Moiréfringe-based focusing-test scheme for optical projection lithography[J].Acta Optica Sinica,2011,31(8):0805001.严伟,李艳丽,陈铭勇,等.基于光闸叠栅条纹的纳米调焦调平方法[J].光学学报,2011,31(8):0805001.
15 Li Jie,Tang Feng,Wang Xiangzhao,et al..System errors analysis of grating lateral shearing interferometer[J].Chinese J Lasers,2014,41(5):0508006.李杰,唐锋,王向朝,等.光栅横向剪切干涉仪及其系统误差分析[J].中国激光,2014,41(5):0508006.
16 Tong Junmin,Zhou Shaolin,Zhao Lixin,et al..Angular measurement using moire interferometry for alignment of proximity lighography[J].Chinese J Lasers,2014,41(12):1208001.佟军民,周绍林,赵立新,等.接近式光刻对准中的叠栅干涉测角方法[J].中国激光,2014,41(12):1208001.
17 Cao Shaoqian,Bu Yang,Wang Xiangzhao,et al..Measurement technique for the Mueller matrix based on a single photoelastic modulator[J].Acta Optica Sinica,2013,33(1):0112006.曹绍谦,步扬,王向朝,等.基于单光弹调制器的米勒矩阵测量技术[J].光学学报,2013,33(1):0112006.