在高数值孔径光学光刻中,成像光入射角分布在较大范围内,传统的单底层抗反膜不足以控制抗蚀剂衬底界面反射率(衬底反射率)。考虑照明光源形状以及掩模的影响,提出了一种新的双层底层抗反膜优化方法,依据各级衍射光光强求衬底反射率的最小权重平均值来配置膜层。针对传统掩模、衰减相移掩模以及交替相移掩模的情况,用该方法优化双层底层抗反膜。结果表明,如果成像时进入物镜光瞳的高阶光越多,高阶光光强越大,则掩模对底层抗反膜优化的影响越大。在某些成像条件下,如使用交替相移掩模实现成像,有必要在底层抗反膜优化中考虑掩模的影响。

In hyper numerical aperture lithography, the incident angle of imaging rays varies in a wide range. Conventional single bottom antireflective coatings (BARC) cannot control reflectivity (substrate reflectivity) at the resist-substrate interface. A novel dual BARC optimization method is developed by taking into account light source shape and mask diffraction for specific applications. A weighted average of the substrate reflectivity for the 0st order as well as a higher order is used when optimizing the dual BARC. BARC structures are optimized with the new method in the cases of binary mask, attenuated phase-shift mask and altering phase-shift mask. The results show that, the higher diffraction orders are captured by the objective lens (or larger the intensity of high orders is), more noteworthy the influence of mask is for BARC optimization. In some cases, such as imaging with altering phase-shift mask, it is indispensable to take the mask into account in BARC optimization.