高数值孔径投影光刻物镜像质补偿策略与偏振像差研究

发布时间：2018-03-01 20:29

本文关键词： 投影光刻物镜高数值孔径公差像质补偿偏振像差　出处：《中国科学院长春光学精密机械与物理研究所》2017年博士论文　论文类型：学位论文

【摘要】：用于制造大规模集成电路的核心设备是光刻机,光刻机的核心部件是投影光刻物镜。为了将掩模图形近似完美地投影到光刻胶上,光刻物镜的像质必须满足极其苛刻的指标要求。如果在光刻物镜的加工制造过程中采取最优的像质补偿策略,则可以在确保各项像质指标的同时,降低多方面的公差要求,进而最大程度地降低投影光刻物镜的制造成本。集成电路节点的推进促使光刻物镜的数值孔径(NA)不断增大,当NA增大到一定程度时,成像光束的偏振态对成像质量的影响变得不可忽略,物镜的像质评价中除了标量像差外,还需要考虑偏振像差。本文针对国内关于极大规模集成电路的产业化需求,开展了面向45 nm节点的深紫外波段NA 1.35浸没式投影光刻物镜的像质补偿策略与偏振像差研究,主要包括以下研究内容:一、投影光刻物镜的成像理论。研究了投影光刻物镜的标量成像理论和矢量成像理论,由于矢量成像理论考虑了成像光束的偏振状态和物镜的偏振像差,所以其更能准确地描述高NA投影光刻物镜的成像性能。本文综合考虑了波像差、畸变、偏振像差(二向衰减和延迟)后,建立了更为全面的像质评价方法。二、像质补偿策略。针对光学材料公差、元件制造公差以及装配公差引起的光刻物镜的波像差与畸变的劣化,本文系统地研究了多种像质补偿方法,包括光学复算、计算机辅助装调、面形精修、变形镜和热补偿。其中,元件间隔的复算用来补偿一维材料公差和加工公差,元件旋转角度的复算用来补偿二维公差如折射率均匀性公差和面形公差,计算机辅助装调主要补偿装配公差,面形精修用来补偿残余的高阶像差,变形镜技术和热补偿技术相结合可以补偿热像差。本文为各种像质补偿方法建立了数学模型,编写了相应的程序,并在NA1.35的光刻物镜上进行了仿真。仿真结果表明,本文的像质补偿策略可将物镜的波像差与畸变补偿至设计水平。三、偏振像差。本文定量地分析了NA 1.35投影光刻物镜的偏振像差,研究了偏振像差在光学系统中的分布规律,并推导出了一种新的多项式,即视场-方向泽尼克多项式,对其进行描述。该多项式是视场坐标和出瞳坐标的函数,能同时表征偏振像差在视场与出瞳上的分布规律,并且各项在单位圆视场和单位圆光瞳上是正交的。视场-方向泽尼克多项式不仅适用于旋转对称的光学系统,也适用于M-fold光学系统。为验证该多项式的正确性,分别用光刻物镜和显微物镜做了仿真,仿真结果与理论推导结果完全一致。本文的研究成果可为高NA投影光刻物镜的研发提供一些有益的指导。
[Abstract]:The core device used in the manufacture of large scale integrated circuits is the lithography machine, the core component of which is the projection lithography objective lens. The image quality of the lithographic objective must meet the extremely harsh requirements. If the optimal image quality compensation strategy is adopted in the manufacturing process of the lithographic objective lens, it can ensure the various image quality indexes and reduce the tolerance requirements in many aspects. Thus, the manufacturing cost of projection lithography objective lens is minimized. The advance of integrated circuit node causes the numerical aperture of lithography objective lens to increase continuously, when na increases to a certain extent, The influence of the polarization state of the imaging beam on the imaging quality can not be ignored. Besides the scalar aberration, the polarization aberration should also be considered in the image quality evaluation of the objective lens. The image quality compensation strategy and polarization aberration of NA1.35 immersion lithographic objective lens for 45 nm node are studied. The main contents are as follows: 1. The imaging theory of projection lithography objective lens. The scalar imaging theory and vector imaging theory of projection lithography objective lens are studied, because the polarization state of the imaging beam and the polarization aberration of the objective lens are considered in the vector imaging theory. Therefore, it can more accurately describe the imaging performance of high na projection lithography objective lens. After considering wave aberration, distortion, polarization aberration (two direction attenuation and delay), a more comprehensive image quality evaluation method is established in this paper. Aiming at the deterioration of wave aberration and distortion caused by optical material tolerance, component manufacturing tolerance and assembly tolerance, this paper systematically studies various methods of image quality compensation, including optical complex calculation. Computer-aided adjustment, surface finishing, deformable mirrors and thermal compensation. The combination of element spacing is used to compensate for one-dimensional material tolerances and machining tolerances, The complex calculation of the rotation angle of the element is used to compensate two dimensional tolerances such as refractive index uniformity tolerance and plane shape tolerance, the computer-aided adjustment mainly compensates the assembly tolerance, and the plane shape refinement is used to compensate the residual higher-order aberrations. Thermal aberration can be compensated by the combination of deformable mirror technology and thermal compensation technique. In this paper, mathematical models of various image quality compensation methods are established, corresponding programs are compiled and simulated on NA1.35 lithography objective lens. The simulation results show that, The image quality compensation strategy in this paper can compensate the wave aberration and distortion of the objective lens to the design level. Thirdly, the polarization aberration. In this paper, the polarization aberration of the na 1.35 projection lithography objective lens is quantitatively analyzed, and the distribution of the polarization aberration in the optical system is studied. A new polynomial, the field-of-view Zehnik polynomial, is derived and described. The polynomial is a function of the field of view and the pupil coordinate, and can represent the distribution of polarization aberration in both the field of view and the pupil at the same time. All items are orthogonal in unit circle field of view and unit circle pupil. Field of view and directional Zehnik polynomials are suitable not only for rotationally symmetric optical systems, but also for M-fold optical systems. The simulation results are in good agreement with the theoretical results. The research results in this paper can provide some useful guidance for the research and development of high na projection lithography objective lens.
【学位授予单位】：中国科学院长春光学精密机械与物理研究所
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TN405;O436.3

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