QQ客服 官方微博 反馈留言

题名	基于Ptychography的极紫外光刻投影物镜波像差检测技术
作者	方伟
学位类别	硕士
答辩日期	2016
授予单位	中国科学院上海光学精密机械研究所
导师	唐锋
关键词	Ptychography PIE 相位恢复 波像差 光刻投影物镜 极紫外光刻
其他题名	Measurement of the Wavefront Aberration of Extreme Ultraviolet Lithography Projection Optics based on Ptychography
中文摘要	光刻技术是整个集成电路制作的关键工艺技术，光刻机是实现光刻的设备，投影物镜系统是光刻机里最昂贵和最复杂的分系统之一。投影物镜波像差是影响投影物镜成像质量的重要因素，为了实现高质量的光刻成像，必须对投影物镜的波像差进行高精度地检测和控制。投影物镜波像差检测技术有很多种，包括基于瞳面测量的Shack-Hartmann传感技术、点衍射干涉仪、剪切干涉仪，基于空间像测量的ROCS技术、AMAI-PCA技术，基于衍射成像的各种相位恢复技术等。每种波像差检测技术都有一定的优势和局限性。本文围绕基于相位恢复技术中的Ptychography技术进行极紫外光刻（EUVL）投影物镜波像差检测展开研究，主要工作有： 1.研究了三种基于衍射法的相位恢复技术：相干衍射成像（CDI）技术、扫描相干衍射成像（Ptychography）技术和强度传输方程（TIE）技术，及相应的相位恢复算法。CDI技术的代表性算法有GS算法、Fienup算法和Difference Map算法，这些算法通过输入面支撑约束（或振幅约束）和输出面振幅约束来完成算法的迭代更新。Ptychography技术是在CDI技术的基础上发展而来，其代表性算法有PIE算法、pPIE算法和ePIE算法，这些算法通过在标记面引入垂直于光轴方向的扫描过程使算法的迭代更新过程增加标记面交叠约束，新增的约束有效克服了CDI算法经常遇到的收敛停滞问题，因而使算法有更快的收敛速度和更高的恢复精度。TIE技术通过在观测面引入沿光轴方向的扫描得到数幅离焦像，求解观测面强度微分与相位之间的偏微分方程来恢复相位，该技术具有较快的计算速度和良好的恢复精度。 2.研究了利用Ptychography检测投影物镜波像差的具体实现方式，分析了应用Ptychography技术检测不同数值孔径投影物镜波像差所采用的光场传播公式、离散化条件及相应实验架构的设计，讨论了检测标记的通光率、复杂度及其与照明光波的配准对算法收敛性和波像差检测精度的影响。当NA<0.15时，选取傍轴近似下的菲涅尔衍射公式来描述标记面至观测面的光场传播过程，给出了采用单步傅里叶变换和双步傅里叶变换算法时的检测系统参数约束条件；当NA进一步增大时，通过分析，采用经典的角谱公式很难建立实际的实验系统，需要采用HNAA公式或者新的衍射场计算方法以适应实验条件。检测标记的通光率需要控制在45%~80%之间，增大标记图案的复杂性能够获得更好的收敛速度与检测精度，在计算过程中增加正向或逆向配准能够进一步提高波像差的恢复精度。 3.进行了基于Ptychography技术的成像系统波像差检测原理实验验证和极紫外光刻投影物镜波像差检测系统设计与仿真，论证了Ptychography技术应用于极紫外光刻投影物镜波像差检测的可行性。极紫外光刻投影物镜的数值孔径在0.25~0.33之间，采用Ptychography技术的波像差检测系统结构简单，对系统误差不敏感，有望成为一种实用的极紫外光刻机原位波像差检测手段。 4.基于Ptychography技术，提出了一种新的采用刀口标记的高精度PIE波像差检测技术。该技术将投影物镜像面汇聚光束看作PIE算法里的照明光波，将切割汇聚光束的刀口看作PIE算法里的标记函数，将不同方向下刀口的衍射图样看作PIE算法里的观测面振幅约束，通过光场传播过程中的能量守恒确定刀口分界线的位置，给出刀口函数，再利用PIE算法的不断迭代恢复照明函数，进而得到投影物镜的波像差。与Foucault刀口测试技术相比，该技术实现了波像差的定量检测；与现有的定量刀口测试技术相比，该技术无需采集一系列的阴影图，测量精度也不受刀口移动精度和阴影图采集密度的影响；与前述的基于Ptychography的波像差检测技术相比，该技术无需复杂的检测标记，很容易使光场传播公式满足实验架构参数限定条件，且算法收敛速度快。该技术有望成为一种新的定量刀口测试技术的实现方案和EUV投影物镜波像差检测技术的实现方案。
英文摘要	Optical lithography is the key technology of the whole manufacturing process of integrated circuit. It’s realized by a tool in which projection optics is one of the most expensive and complicated sub-systems. As a significant factor affecting imaging quality of lithography, the wavefront aberration of lithography projection optics should be measured and controlled accurately. There are many kinds of technologies for wavefront aberration measurement of projection optics, including technology based on pupil measurement like Shack-Hartmann sensor, point diffraction interferometer and shearing interferometer, technology based on aerial image measurement like ROCS (Reduced Optical Coherent Sum), AMAI_PCA (Aberration Measurement based on Principal Component Analysis of Aerial Image), and technology based on diffraction imaging like various phase retrieval approaches. Each technology has its own advantages and limitations. This research focuses on a study about measurement of wavefront aberration of Extreme Ultraviolet Lithography (EUVL) projection optics based on ptychography, which is a phase retrieval technique. The main work done in the thesis is as follows: 1.Three phase retrieval techniques and corresponding algorithms based on diffraction imaging are studied. These techniques include coherent diffraction imaging (CDI), scanning coherent diffraction imaging (ptychography) and transport of intensity equation (TIE). The representative algorithms of CDI are Gerchberg-Saxon (GS) algorithm, Fienup algorithm, and difference map. They completed their iterations and updating by support constraint (or modulus constraint) in the input plane and modulus constraint in the output plane. Ptychography is developed from CDI with representative algorithms as Ptychographic Iterative Engine (PIE), parallel PIE (pPIE), and extended PIE (ePIE). These algorithms introduce the scanning process perpendicular to the optical axis in the object plane to add the overlay constraint in the iterations and updating process. The new overlay constraint effectively overcomes the problem of stagnation which CDI algorithms often encounter and gives the algorithms faster convergence speed and higher retrieval accuracy. TIE introduces scanning process along the optical axis in the observation plane to acquire several defocus images, then solves the partial differential equation about the relation of differential intensity and phase in the observation plane to retrieve phase. This technique has fast calculation speed and high retrieval accuracy. 2.The implementation about the measurement of the wavefront aberration of projection optics in lithography based on ptychography are studied. The optical field propagation formulas, the conditions of discretion, and the design of experimental configurations with different systematic NA are analyzed. The effect of object’s transmittance, complexity and registration with the probe on the algorithm’s convergence and measurement accuracy are also discussed. When systematic NA is less than 0.15, the Fresnel diffraction formulas under paraxial approximation are selected to describe the optical field propagation from the object plane to the observation plane. The constraint conditions about configuration parameters using single-FFT formula and double-FFT formula to compute the diffraction process are given. As NA increases, the experimental system is difficult to setup by using classic angular spectrum formula, then HNAA and other formulas are used to satisfy the experimental conditions. The transmittance of the object should be set between 45% and 80%. Increasing the complexity of object pattern and adding the registration of object and probe into the iterative algorithm can improve the convergence speed and retrieval accuracy. 3.A optical prototype for the wavefront aberration measurement of imaging system based on ptychography is built. A system for the wavefront aberration measurement of EUVL projection optics is also designed and simulated. Both of their results validate the feasibility of wavefront aberration measurement of lithography optics based on ptychography. The numerical aperture of EUVL projection optics is between 0.25~0.33. Using ptychography to measure the wavefront aberration has advantages of simple experimental setup and non-sensitivity to systematic aberrations, and is expected to be a practical method of in-situ wavefront aberration measurement in the EUV lithography equipment. 4.A novel approach for wavefront aberration measurement based on ptychography using knife edge as object is proposed. This approach takes the converging light beam in the focus plane as the probe, the knife edge cutting the light beam as the object, the diffraction pattern under different direction of knife edge as the modulus constraint in the observation plane. The knife edge function is determined by the position of knife edge line which is confirmed by the law of energy conservation during the optical field propagation. The probe is retrieved during the iterative process of PIE algorithm, and the wavefront aberration of projection optics is then acquired. Compared with Foucault knife edge test, the technique enables the qualitative evaluation of wavefront aberration. As for existing qualitative knife edge test, the technique has no need of collecting a series of shadow patterns and the measurement accuracy is not affected by the accuracy of the knife edge movement and the collecting density of shadow patterns. By comparison with the technique of wavefront aberration measurement based on ptychography mentioned above, the technique has no need of sophisticated object, makes the optical field propagation formula meet the constraint requirements of configuration parameters more easily, and possesses faster convergence speed. The technique is expected to be a new method to implement qualitative knife edge test and wavefront aberration measurement of EUVL projection optics.
语种	中文
内容类型	学位论文
源URL	[http://ir.siom.ac.cn/handle/181231/16988]
专题	上海光学精密机械研究所_学位论文
推荐引用方式 GB/T 7714	方伟. 基于Ptychography的极紫外光刻投影物镜波像差检测技术[D]. 中国科学院上海光学精密机械研究所. 2016.

个性服务

查看访问统计

相关权益政策

暂无数据

收藏/分享

除非特别说明，本系统中所有内容都受版权保护，并保留所有权利。