超大数值孔径光刻中掩模保护膜优化及偏振像差研究

Study on Pellicle Optimization and Polarization Aberration Induced by Pellicle in Hyper Numerical Aperture Lithography

超大数值孔径(NA)光刻成像中,掩模保护膜上的入射光线入射角范围增大,用传统方法优化掩模保护膜难以增大斜入射光的透射率。基于薄膜光学原理提出一种新的掩模保护膜优化方法,确保光线在整个入射角范围内的平均透射率最大。利用琼斯矩阵方法探讨膜层的透射属性和相位特征,得到相应的琼斯光瞳来分析膜层带来的偏振像差。结果表明,对比传统的掩模保护膜优化方法,新方法能有效提高斜入射光线的透射率,减小膜层引起的偏振像差。新的掩模保护膜优化方法能为超大NA光刻成像的掩模保护膜设置提供必要的理论基础和技术支撑。

In hyper numerical aperture（NA） lithography imaging,the incident angle of imaging rays on pellicle varies in a wide range,so it is difficult to enhance the transmittance of oblique incidence employing the conventional pellicle optimization methods.A novel pellicle optimization method is developed based on the film optics theory,which maximizes the average transmittance within the whole incident angles range.The transmission properties and phase characteristics of pellicle are studied using Johns matrix representation.The corresponding Johns pupil is obtained to analyze the polarization aberration induced by pellicle.The results show that,compared with the conventional pellicle optimization methods,the novel method enhances the transmittance of oblique incidence and decreases the pellicle-induced polarization aberration more effectively.The novel method provides the essential theoretical basis and technical support for pellicle setting in hyper NA lithography imaging.