深紫外光刻投影物镜热像差仿真研究

发布时间：2018-01-03 11:35

本文关键词：深紫外光刻投影物镜热像差仿真研究　出处：《中国科学院研究生院(长春光学精密机械与物理研究所)》2015年博士论文　论文类型：学位论文

【摘要】：随着集成电路芯片线宽的持续减小,光刻工艺对投影物镜分辨率的要求不断提高,而分辨率的提高则意味着投影物镜像差的减小。对于一台工作中的深紫外光刻投影物镜,它的像差由两部分构成:物镜装调完成后的残余像差和物镜工作时产生的热像差,其中热像差对光刻效果的影响更为显著。而且由于热像差出现于工作过程中,且随着曝光时间的延长逐渐变化,导致被动补偿的方式无法消除热像差,只能在投影物镜工作时对其进行实时补偿。为了研究投影物镜的热像差特性,本论文建立了深紫外光刻投影物镜的热分析模型,并完成了对系统热像差的求解,根据求解结果设计了一种像差补偿方案。论文的主要工作内容及创新点如下:1.建立了深紫外光刻投影物镜热分析模型;根据现有投影物镜的光学/机械设计方案,建立了深紫外光刻投影物镜热像差求解模型,模型包括了光强度计算模块、热/结构有限元计算模块以及光学系统像差求解模块,且在模型中考虑了照明形式与工作时序等因素对热像差求解的影响。2.分析了光刻投影物镜在不同照明条件下的热像差特性;光刻投影物镜的传统照明方式为Top-Hat型,但是为了实现更高的分辨率和更大的焦深,投影物镜工作时经常采用偶极照明、四极照明和环形照明等离轴照明方式,本文利用建立的热像差分析模型计算了四种照明方式下投影物镜的热像差特性。3.建立了投影物镜热像差快速计算模型;对单个透镜的热传递过程进行了理论推导,证明温度变化、面形变化与透镜中的光强分布之间存在线性变换关系,根据这一关系建立了基于光强分解的透镜温度/应变快速计算方法;然后利用灵敏度矩阵在透镜L20中心面温度分布与投影物镜热像差之间建立了线性变换关系;最后将上述两个线性变换关系结合,实现了投影物镜热像差的快速计算。4.设计了投影物镜热像差补偿方案,并进行了仿真验证;以分析得到的热像差特性为依据设计了投影物镜的热像差补偿方案。此方案利用了透镜材料(Si O2)对CO2激光的高吸收特性,采用CO2激光器、振镜和反射镜组实现了在孔径光阑处对系统像差进行补偿的设计要求。经仿真验证,所设计方案可以实现对各类像差的补偿,其补偿范围可以达到补偿热像差所要求的1.5λ,但是补偿精度与扫描算法尚需改进。
[Abstract]:With the continuous decrease of the linewidth of integrated circuit chip, the resolution of projection objective is required by lithography technology. The improvement of resolution means that the projection image difference is reduced. For a working deep ultraviolet lithography projection objective lens. Its aberration is composed of two parts: the residual aberration after the objective lens is set up and the thermal aberration produced when the objective lens is in operation, in which the thermal aberration has a more significant effect on the lithography effect. Moreover, the thermal aberration appears in the working process. With the extension of exposure time, the passive compensation method can not eliminate the thermal aberration, so it can only be compensated in real time when the projective objective lens works. In order to study the thermal aberration characteristics of the projection objective lens. In this paper, the thermal analysis model of deep ultraviolet lithography projection objective lens is established, and the thermal aberration of the system is solved. According to the solution result, a scheme of aberration compensation is designed. The main work and innovation of this paper are as follows: 1. The thermal analysis model of deep ultraviolet lithography projection objective is established. According to the existing optical / mechanical design of projection objective, the thermal aberration solution model of deep ultraviolet lithography projection objective is established. The model includes light intensity calculation module. Thermal / structural finite element calculation module and optical system aberration solution module. In the model, the influence of illumination form and working time sequence on the thermal aberration solution is considered. 2. The thermal aberration characteristics of the lithographic projection objective lens under different illumination conditions are analyzed. The traditional illumination mode of lithographic projection objective is Top-Hat type, but in order to achieve higher resolution and greater focal depth, dipole illumination is often used when projecting objective lens works. Four pole lighting and ring lighting off-axis lighting mode. In this paper, the thermal aberration characteristics of projection objective lens under four illumination modes are calculated by using the established thermal aberration analysis model. The fast calculation model of thermal aberration of projection objective lens is established. The heat transfer process of a single lens is theoretically deduced, and it is proved that there is a linear transformation relationship between the temperature change, the surface shape change and the light intensity distribution in the lens. According to this relation, a fast calculation method of lens temperature / strain based on light intensity decomposition is established. Then the linear transformation relationship between the temperature distribution of the L20 central plane and the thermal aberration of the projection objective is established by using the sensitivity matrix. Finally, combining the above two linear transformation relations, the fast calculation of thermal aberration of projection objective lens is realized. Finally, the compensation scheme of thermal aberration of projection objective lens is designed and verified by simulation. Based on the analysis of the thermal aberration characteristics, the thermal aberration compensation scheme of the projection objective lens is designed. The scheme utilizes the high absorption characteristic of the lens material (SiO2) to the CO2 laser, and adopts the CO2 laser. The system aberration compensation is realized in the aperture apertures. The simulation results show that the designed scheme can compensate all kinds of aberrations. The compensation range can reach 1.5 位 of thermal aberration compensation, but the compensation accuracy and scanning algorithm need to be improved.
【学位授予单位】：中国科学院研究生院(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】：2015
【分类号】：TN305.7

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