摘要
掩模吸收层厚度引起的散射效应会导致深紫外和极紫外光刻成像产生偏差。传统光刻模型建立在满足薄掩模近似的Hopkins成像理论上,但随着掩模上吸收层的高宽比增大,掩模厚度成为衍射计算中不可忽略的因素。为实现对空间像的精准预测,提出一种三维掩模成像模型,利用严格电磁学仿真生成的掩模衍射近场来修正Hopkins模型结果。严格电磁学仿真需要的计算开销可以通过一种基于旋转变换和仿真维度减少的快速掩模边沿近场生成方法来减少。因此,将三维掩模成像模型和快速衍射近场生成方法结合后可以快速构建精准的三维掩模光刻成像模型。
Objective Scattering caused by the thickness of the absorber layer of the mask leads to deviations in deep ultraviolet(DUV)and extreme ultraviolet(EUV)lithography.Traditional lithography models are based on Hopkins'method and the thin mask approximation,wherein diffracted waves from the mask satisfy the Fourier transform of the mask patterns.As the aspect ratio of the absorbing layer on the mask increases,the mask thickness becomes a non-negligible factor in diffraction calculation.Thick absorbers change the diffracted waves,particularly along the edges of the pattern.To accurately predict the aerial image,a 3D mask model is proposed to correct the Hopkin's model using the mask near fields generated via rigorous electromagnetic simulation,such as the finite-difference time-domain(FDTD)method.The computational cost of rigorous electromagnetic simulations can be reduced using a fast mask near-field generation method based on rotation transformation and dimension reduction.By combining a 3D mask model with a fast near-field generation method,an accurate 3D mask lithographic model can be rapidly constructed.The 3D mask model offers the advantages of less runtime and high accuracy when dealing with cases involving complex source and any-angle mask patterns.Methods First,a rotation transformation was applied to any given case.The source was decomposed by polarization,and each component of the source was rotated with the incident edge in such a way that the incident angle of the light remained unchanged on the vertical or horizontal incident edge.Next,a 2D FDTD simulation was implemented by reducing the dimension of the simulation area along the incident edge.This 2D FDTD simulation generates a 1D accurate electromagnetic wave distribution near the mask absorbers,with the 1D accurate wave distribution describing the diffracted wave on the line perpendicular to the incident edge.Subsequently,the FDTD-generated 1D wave distribution was expanded along the incident edge and used to modify the thin mask approximated results
作者
包涵
张涌
Bao Han;Zhang Yong(Shenzhen Institute of Advanced Technology,Chinese Academy of Sciences,Shenzhen 518055,Guangdong,China;SMIT,Shenzhen 518057,Guangdong,China)
出处
《光学学报》
EI
CAS
CSCD
北大核心
2023年第13期244-252,共9页
Acta Optica Sinica
基金
国家自然科学基金(12071460)
深圳市科技计划(CJGJZD20210408092806017)。
关键词
计算光刻
光学邻近矫正
三维掩模模型
时域有限差分法
computational lithography
optical proximity correction
three-dimensional mask model
finite-difference timedomain method
