深紫外光刻投影物镜温度特性研究

Research on Temperature Distribution of Deep Ultraviolet Lithographic Projection Objective

透镜材料对激光能量的吸收导致深紫外光刻投影物镜温度升高,产生热像差。离轴照明模式下,温度呈非对称分布,研究温度场对热像差的仿真预测和补偿具有十分重要的意义。提出了温度分布函数模型描述4种照明模式下物镜的三维温度分布;研究了温度的时间特性,并通过计算预测了光刻物镜的热稳态温度值以及达到稳态所需的时间。结果表明,利用该温度分布模型描述多种常见照明模式下投影物镜的空间温度分布,平均拟合误差约为10-3℃量级;通过温度时间关系函数预测热稳态温度的误差约为10-4℃,时间误差不超过3min。通过该温度分布模型计算得到的热像差结果与基于SigFit的仿真结果一致,但计算效率提升了三个数量级。

As for the deep ultraviolet（UV）lithographic projection objective,the laser energy absorbed by the lens material causes temperature rise,which induces thermal aberration.Under the off-axis illumination mode,the temperature distribution is non-symmetric,and thus the research on the temperature distribution is significant for thermal aberration simulation,prediction and compensation.A temperature distribution function model is proposed to describe the three-dimensional temperature distribution of the lens in four illumination modes.Simultaneously,the relationship between temperature and exposure time is studied,and the temperature at the thermal steady state and the consumed time to get steady is calculated.The results show that the temperature distribution models perform well for describing the spatial temperature distribution of projection lens under several commonly used illumination modes with an average fitting error of about 10^-3℃.The error of thermal steady temperature predicted via the relationship between temperature and time is about 10^-4℃,and the time error is less than 3 min.The thermal aberration results calculated by the proposed model agree with the simulation results by SigFit,while the time cost shows a decrease of three orders of magnitude.