光纤点衍射干涉仪波面参考源研究

	光纤点衍射干涉仪波面参考源研究
	代晓珂
学位类型	硕士
导师	金春水
	2014-11
学位授予单位	中国科学院大学
学位专业	光学
关键词	光学检测极紫外光刻波面参考源偏振控制
摘要	极紫外光刻技术(EUVL)是下一代光刻的主流技术。光刻物镜作为光刻机核心单元，为了满足光刻分辨率及临界尺寸控制的要求，其RMS波像差应小于λ/14 (对于极紫外光刻，λ=13.5nm)，即1 nm RMS。利用微孔或光纤衍射产生高质量球面波的点衍射干涉仪避免了对参考元件面形精度的依赖，可以满足如此高的检测精度，在极紫外光刻光学检测中占据了重要的位置。本文研究了提高点衍射干涉仪检测精度的方法，设计出集合光纤和微孔点衍射优点的波面参考源(WRS)，其衍射球面波在0.6数值孔径范围内非对称偏差不大于8.85E-5λ（λ=532nm），可以满足极紫外光刻物镜系统波像差检测精度要求。 (1) 明确了WRS的设计方向，前人对其光束准直系统和小孔对准系统已进行了充分的研究，本文在WRS中加入偏振控制系统以提高检测精度。首先对干涉光束偏振态的选择进行理论分析，得到圆偏振态的光束干涉不仅在干涉条纹对比度而且在衍射后球面波的误差分布方面都优于其它偏振态，因此需要对干涉光束的偏振态进行控制。利用光纤偏振控制器对光束偏振态进行控制：在对偏振控制器的原理分析基础上，提出了快速进行偏振态控制的算法，依据此算法设计了偏振态控制系统，并建立了偏振控制实验装置以验证算法的正确性，分析得出此方法控制的椭圆率误差不大于3.41%，实现在不对光束波前引入额外误差的基础上快速完成偏振态控制； (2) 对WRS的三个部分(光束准直系统、偏振控制系统和小孔对准系统)统筹分析：以最终衍射球面波非对称偏差不大于8.85E-5λ(λ=532nm)为指标，对WRS进行公差分析。在此基础上，采购实验器件，搭建出WRS。 WRS系统误差的标定对提高波像差检测精度有重大意义，设计了标定算法，以实际极紫外光刻两镜系统波像差原始数据模拟标定过程，通过多次模拟得到标定时关键实验器件的公差； (3) 利用设计搭建的WRS对物镜的波像差进行检测：先研究了基于此WRS的物镜波像差检测过程中的误差，提出误差的消除方法；而后搭建出另一套WRS，将它们与点衍射干涉仪的前置光路接合，分别作为参考和测试WRS，完成物镜波像差检测试验。
其他摘要	Extreme ultraviolet lithography (EUVL) is regarded as a main choice for next generation lithography. The wavefront aberration of lithography objective, which is the most important part of lithography machine, should be less than λ/14 RMS (for EUVL, λ=13.5 nm) or 1 nm RMS, in order to satisfy the need of lithography resolution and critical control dimension. Point diffraction interferometer which can produce nearly perfect spherical wavefront with pinhole or fiber is free from the precision of reference element, so it can meet the measurement accuracy for EUVL objective. Thus point diffraction interferometer has occupied a significant position in EUVL optical test. The method enhancing test accuracy of point diffraction interferometer has been studied in this paper. Then a new wavefront reference source (WRS) which gathers the advantage of pinhole and fiber diffraction has been designed. Analysis in theory indicates that in order to meet the need of EUVL objective wavefront test, the diffracted spherical wavefront of this new wavefront reference source should have a asymmetry error value of less than 8.85E-5λ (λ=532nm) when NA is less than 0.6. (1) First the problem of the design for WRS should be explored: because others have done a detailed study on optical collimation system and pinhole alignment system already, this paper emphasizes the study on polarization system. The choosing of polarization state for WRS has been analyzed in theory, then we find interference of circularly polarization light is better than other state of polarization on both contrast of interference fringes and the diffracted spherical wave error. Above all, we should design a polarization control system for WRS. The control of polarization is achieved by fiber polarization controller. Based on analysis on the fiber polarization controller, we’ve proposed an algorithm to control the polarization fast, and then a polarization control system is designed. Also we have done an experiment on polarization control to prove the algorithm correct, the error of polarization control is less than 3.41%, it means that we can realize the polarization control fast without introducing extra error to wavefront. (2) The three main element of WRS (optical collimation system、polarization control system and pinhole alignment system ) have been taken into account together. In order to meet the requirement that the asymmetry deviation of diffracted spherical wave must be less than 8.85E-5λ (λ=532 nm), the tolerance of the WRS should be analyzed. Based on the work above, we have established this WRS. What is of a great importance to enhance the test accuracy is to calibrate the WRS error. We have analyzed the calibration algorithm thoroughly, and then the simulation of calibration is carried out using the original data getting by testing two mirrors EUVL wavefront aberration. Thus the tolerance of some key device is got by simulating calibration repeatedly. (4) Point diffraction interferometer with this new WRS is used to test the optical objective wavefront aberration. First the error introduced by this WRS when test wavefront aberration is analyzed, then the method to eliminate this error is discovered. The other WRS is established, which will connect with the front optical part. Finally this two WRS are used to test the wavefront aberration.
语种	中文
文献类型	学位论文
条目标识符	http://ir.ciomp.ac.cn/handle/181722/44648
专题	中科院长春光机所知识产出
推荐引用方式 GB/T 7714	代晓珂. 光纤点衍射干涉仪波面参考源研究[D]. 中国科学院大学,2014.

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