深紫外光刻照明系统光束整形单元的设计

Design of beam shaping unit for deep ultraviolet lithographic illumination system

为了使曝光波长为193 nm的深紫外光刻系统能够制备曝光线宽为90 nm及以下节点的集成电路芯片,设计了采用环形照明模式且部分相干因子σ连续可调,能满足不同曝光线宽要求的光刻照明系统光束整形单元。首先,用几何光学定律和三角函数推导了轴锥镜移动距离与光束放大倍率之间的函数关系;根据对变倍凸轮的合理性和装调公差灵敏度的分析,确定了轴锥镜组参数的变化范围,完成了变倍镜组与轴锥镜组合的光束整形单元的设计。最后,在组合系统后面加入了可连续变倍的缩束系统,实现了σ的连续可调。设计结果显示,在环形照明模式下,归一化的环宽Δσ和外环直径σouter分别在[0.25,1]和[0.4,1]内连续可调,满足设计要求。

To manufacture the integrated circuit chips at 90 nm or below their nodes by using a 193 nm exposed wavelength deep ultraviolet lithography,a beam shaping unit for the lithographic illumination system was designed to achieve the annular illumination and the continuous adjustment of a partial coherent factor σ to meet the requirements of different exposed line widths.Firstly,the function relationships between the moving distance of axicon and the light beam magnification were deduced by using the laws of geometric optics and trigonometric functions,and the ranges of parameters of axicon were determined after analyzing the feasibility of zoom cam and the tolerance sensitivities.Then,the axicon and zoom lens were combined to implement the beam shaping unit.Finally,a kind of reducing scale zoom lens was designed to add into the combined system to achieve the continuously adjustment of the σ.The result shows that the normalized annular width Δσ and the outer diameter of annulus σouter can be adjusted continuously in the range of [0.25,1] and ,respectively,which meets the needs of design.