高数值孔径光刻成像中顶层抗反膜的优化

高数值孔径光学光刻中,成像光分布在较大的入射角范围内,传统顶层抗反膜优化方法只对垂直光来减小光刻胶上表面反射率,难以保证光在整个入射角范围实现反射率最小。提出全入射角范围顶层抗反膜优化方法,即在入射角范围内实现光刻胶-顶层抗反膜-空气(或浸没液体)界面的最小平均反射率,并优化顶层抗反膜参量。结果表明,该方法能减小薄膜干涉引起的成像线宽(CD)变化,有效控制成像摆效应,增大顶层抗反膜透射率,提高横电和横磁偏振光透射率之比,从而提高扫描曝光系统的生产率,进一步改善成像衬比度。

Optimization of Topside Antireflective Coatings for Hyper Numerical Aperture Lithography

In hyper numerical aperture(NA)lithography,the incident angle of imaging rays varies in a wide range.Conventional topside antireflective coatings(TARC)optimization methods,minimize the reflectivity only for normal incident light,but are insufficient to suppress the reflectivity in the whole incident angles range of the incoming imaging rays for hyper-NA lithography.A novel TARC optimization method is developed,and the average reflectivity at the resist/TARC/air(or immersion fluid)interface is calculated over the whole range of incident angles that NA determines.Optimal design of TARC structure is carried out to minimize the reflectivity.The results show that,with this method,the thin-film interference effects which cause remarkable line width fluctuation can be reduced,the swing curve effect is controlled,the transmittance of TARC and the ratio of transmittance of TE to that of TM waves are increased,so that the scanner throughput and image contrast,can be improved.