| 题名 | 深紫外光刻投影物镜热像差仿真研究 |
| 作者 | 骆聪 |
| 学位类别 | 博士 |
| 答辩日期 | 2015-05 |
| 授予单位 | 中国科学院大学 |
| 导师 | 巩岩 |
| 关键词 | 投影物镜 热像差 有限元分析 红外像差补偿 Zernike多项式 |
| 其他题名 | Simulation Research on Thermal Aberrations of DUV Lithography Projection Objective |
| 学位专业 | 光学工程 |
| 中文摘要 | 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（SiO2）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。 |
| 英文摘要 | Following the decreasing trends of the dimensions of integrated circuits (IC), the lithography technology asks for increasing resolution which indicates CD (critical dimension) of projection lens and that claims the reduction of system aberrations. Aberrations of a DUV (deep ultraviolet) lithography projection lens come from two sides: the assembly residual aberrations and thermal aberrations caused by energy absorption while the latter is more remarkable. For the truth that the thermal aberrations occurs during working hours and change with exposure time, the traditional ways for aberrations compensation is useless and the only method is real-time compensation. To study the thermal aberrations, the thesis has modeled the DUV projection lens for thermal analysis; the solution has been done to get thermal aberrations and based on which a compensation scheme is proposed. The contents and innovations are as follows: 1. Models for thermal analysis are established; On the basis of the available project lens system and its mechanical supporting structure, the model for thermal aberrations analysis is established which consists of module for light intensity distribution calculation, FEA (finite element analysis) module for thermal-structure calculation and module for system aberration analysis, and during the full solving process the influence of illuminating conditions and printing conditions are both taken into consideration. 2. Thermal aberrations under different illumination conditions are analyzed; The traditional exposure way for lithography projection lens is Top-Hat style, while diverse off-axis exposure conditions of dipole, quadrupole and circular patterns are common employed to get higher resolution and larger focal depth, and all the four illuminating ways are set respectively to get the different thermal aberrations distributions. 3. Fast thermal aberrations calculating model is established; The heat conduction for single lens is derived theoretically to get the linear relation of lens temperature rising and surface strain towards the intensity distribution, based on which an algorithm for fast calculation of lens temperature and strain fields is proposed using a polynomial decomposition method on the intensity distribution; then the linear transforming relation between the temperature field in the middle surface of lens L20 and the system thermal aberrations is obtained using sensitivity matrix; by combining the two linear relations, the fast calculation algorithm is founded. 4. Compensation scheme is proposed and simulation experiment is accomplished; The compensation scheme is proposed according to the results of thermal aberrations analysis. The project utilizes CO2 laser, scanning mirror and reflector operating on the pupil lens to match the compensation targets which takes the advantage of the high absorption property of SiO2 towards CO2 laser. The simulation experiment shows that the compensation scheme is effective for kinds of aberrations, and the dynamic range meets the demand of thermal aberrations compensation which is about 1.5λ, though the precision and the algorithm for scanning mirror expects to be improved. |
| 公开日期 | 2015-12-24 |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.ciomp.ac.cn/handle/181722/48880]  |
| 专题 | 长春光学精密机械与物理研究所_中科院长春光机所知识产出 |
| 推荐引用方式 GB/T 7714 | 骆聪. 深紫外光刻投影物镜热像差仿真研究[D]. 中国科学院大学. 2015. |
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