基于瞳面干涉的自参考干涉仪的研制
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摘要
为了用更简单的光学器件使对准标记产生的衍射光实现重叠干涉,同时能够降低对准系统的加工和装调难度,设计了基于瞳面干涉的自参考干涉仪系统。首先,对当前光刻机所使用的对准技术展开研究,以光栅衍射原理和偏振光学为理论基础,提出了用Koster棱镜作为合光器件的自参考干涉仪,最后使用线阵CCD收集信号并将数据用计算机做后续的位置信息处理。由于自参考干涉仪测量系统是以光栅的栅距作为测量基准,而不是使用激光波长,故测量系统受环境因素造成的测量误差影响较小。实验结果表明:系统分辨率为0.2 nm,使得该系统可以达到纳米级分辨率。证明了所设计的干涉仪可用于目前前道光刻机的对准系统,实现纳米级精度的对准测量,从而使光刻设备的套刻精度满足最新工艺节点的要求。
In order to achieve the overlapping interference of the diffracted light which produced by the alignment marks and while reducing the difficulty of processing and assembly of the alignment system,a self-referencing interferometer based on interfering in the pupil plane is designed.First,the current alignment technique for lithography machines was researched.Then after based on the theory of grating diffraction and polarization optics,a new miniature nanometer interferometer using grating Doppler Effect is developed,which is using the koster prism as the combined beam device.Finally linear CCD was used for collecting the interference signal and the signal was processed by the computer.As the measurement standard of self-referencing interferometer measurement system is grating pitch,not the laser wavelength,measurement system reduces environment influence on measurement accuracy.Experimental results indicate that the precision of the system' s scale setting up is 0.2nm,and it is obvious that the measuring precision of measurement is within nano.Through experiments,it proved that the interferometer can be used for the alignment system of the front channel lithography machine.Nano scale precision can be achieved for the alignment measurement,so the overlay accuracy of the lithography will be meet the requirements of the latest process node.
In order to achieve the overlapping interference of the diffracted light which produced by the alignment marks and while reducing the difficulty of processing and assembly of the alignment system,a self-referencing interferometer based on interfering in the pupil plane is designed.First,the current alignment technique for lithography machines was researched.Then after based on the theory of grating diffraction and polarization optics,a new miniature nanometer interferometer using grating Doppler Effect is developed,which is using the koster prism as the combined beam device.Finally linear CCD was used for collecting the interference signal and the signal was processed by the computer.As the measurement standard of self-referencing interferometer measurement system is grating pitch,not the laser wavelength,measurement system reduces environment influence on measurement accuracy.Experimental results indicate that the precision of the system' s scale setting up is 0.2nm,and it is obvious that the measuring precision of measurement is within nano.Through experiments,it proved that the interferometer can be used for the alignment system of the front channel lithography machine.Nano scale precision can be achieved for the alignment measurement,so the overlay accuracy of the lithography will be meet the requirements of the latest process node.
引文
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[2]杨向荣,张明,王晓临,等.新型光刻技术的现状与进展[J].材料导报,2007,21(5):102-104.YANG X R,ZHANG M,WANG XL,et al.Current status and development of emerging photoetching technology[J].Materials Review,2007,21(5):102-104.
[3]梁友生,周金梅,曹益平,等.100 nm线宽的掩模硅片自动对准算法[J].电子工业专用设备,2004(116):63-67.LIANG Y SH,ZHOU J M,CAO Y P.An automatic alignment algorithm for 100 nm CD reticle-wafer[J].Equipment for Electronic Products Manufacturing,2004(116):63-67.
[4]程晓辉,赵洋,李达成.光学纳米测量方法及发展趋势[J].光学技术,1999(3):73-77.CHEN X H,ZHAO Y,LI D CH.Review on optical nanometrology[J].Optical Technique,1999(3):73-77.
[5]王国超,颜树华,高雷,等.光栅干涉位移测量技术发展综述[J].激光技术.2010,34(5):661-664.WANG G CH,YAN SH H,GAO L,et al.Development of displacement measurement technologies based on grating interferometry[J].Laser technology,2010,34(5):661-664.
[6]姚启钧.光学教程(第四版)[M].北京:高等教育出版社,2008.YAO Q J.Optical tutorials[M].(4th ed)Beijing:Higher Education Press,2008.
[7]姚汉民,胡松,邢廷文.光学投影曝光微纳加工技术[M].北京:北京工业大学出版社,2006.YAO H M,HU S,XING T W.Optical projection exposure micro-nano processing technology[M].Beijing:Beijing University of Technology Press,2006.
[8]苏绍璟.大量程纳米级光栅位移测量理论及关键技术研究[D].长沙:国防科学技术大学,2001.SU SH J.Research on theory and key technologies of Long-range displacement measuring with nanometer resolution by grating[D].Changsha:National University of Defense Technology,2001.
[9]HAN B.Recent advancements of moire and microscopic moire interferometry for thermal deformation analyses of microelectronics devices[J].Experimental Mechanics,1998,38:278-288.
[10]POST D.Moire interferometry at VPI&SU[J].Experimental Mechanics,1983,23:203-210.
[11]吕海宝.激光光电检测[M].长沙:国防科技大学出版社,1999:131-154.LV H B.Laser photoelectric detection[M].Changsha:National University of Defense Technology Press,1999:131-154.
[12]侯国章.测试与传感技术[M].哈尔滨:哈尔滨工业大学出版社,1998:141-154.HOU G ZH.Sensor and measurement technology[M].Harbin:Harbin Institute of Technology Press,1998:141-154.
[13]何树荣,肖宗扬.CCD直接细分光栅位移传感器的研究[J].光学技术,1999(3):1-3.HE SH R,XIAO Z Y.Study of displacement sensor using CCD to subdivide grating directly[J].Optical Technique,1999(3):1-3.
[14]刘玉圣,范光照,陈叶金.高精度衍射光栅干涉仪的研制[J].计量测试与检定,2006,16(2):1-3.LIU Y SH,FAN G ZH,CHEN Y J.A research on diffraction grating interferometer with high accuracy[J].Metrology Test Technology&Verification,2006,16(2):1-3.
[15]陈晓怀,杜国山,程真英.光栅测量系统的误差研究[J].电子测量与仪器学报,2012,26(3):187-191.CHEN X H,DU G SH,CHENG ZH Y.Research on dynamic error of grating measurement system[J].Journal of Electronic Measurement and Instrument,2012,26(3):187-191.