调节力对偏心调节机构中透镜面形的影响

Effect of Adjusting Force on Surface Figure of Lens in Eccentric Adjusting Mechanism

针对深紫外光刻投影物镜的像质补偿要求,对偏心调节时的透镜进行受力分析,基于柔度矩阵法设计了一种柔性多弹片透镜支撑结构,研究了透镜面形随调节力的变化规律,采用有限元法分析了调节力与透镜面形峰谷(PV)值、均方根(RMS)值和Fringe Zernike多项式系数之间的关系。计算结果表明:调节时通过降低调节力的大小,可以控制面形劣化程度。采用具有吸收调节力功能的柔性支撑结构后,在50N的驱动力偏心调节时,透镜上表面面形PV值和RMS值分别为2.704nm和0.528nm,透镜下表面面形PV值和RMS值分别为2.984nm和0.571nm。透镜面形的PV值、RMS值及Fringe Zernike多项式系数随调节力线性变化,但是调节力不会改变各种像差的性质,它引入的透镜像差主要为像散。

For aberration compensation requirement of projection objective lens in deep ultraviolet lithography,the stress analysis of the lens in eccentric adjusting is carried out.A kind of lens supporting with multi-flexure is designed based on compliance matrix method.Regularity between the adjusting force and the surface figure of the lens is investigated.Relationship among the adjusting force,the peak valley（PV）value,the root mean square（RMS）value and Fringe Zernike coefficients of the lens are analyzed using the finite element method.The results show that the aberration can be restricted by reducing the adjusting force.By using flexible support mechanism for absorbing adjusting force,the PV value and RMS value of the upper surface of the lens are 2.704 nm and 0.528 nm,the lower surface are 2.984 nm and 0.571 nm respectively in full stroke eccentric adjusting.The PV value,the RMS value and Fringe Zernike coefficients of the lens vary linearly with the adjusting force.The adjusting force does not change the nature of the aberration.The aberration is mainly astigmatism.