基于傅里叶合成技术的光刻照明系统研究  

Lithography Illumination System Based on Fourier Synthesis Technology

作　　者：李慧 吴晓斌 韩晓泉 马赫 沙鹏飞 Li Hui;Wu Xiaobin;Han Xiaoquan;Ma He;Sha Pengfei(R&D Center of Optoelectronic Technology,Institute of Microelectronics of the Chinese Academy of Sciences,Beijing 100029,China)

机构地区：[1]中国科学院微电子研究所光电技术研发中心,北京100029

出　　处：《中国激光》2023年第6期105-112,共8页Chinese Journal of Lasers

基　　金：国家自然科学基金面上项目(6207012724)。

摘　　要：离轴照明技术是光刻工艺中提高成像分辨率的关键技术之一。本文提出了一种基于傅里叶合成技术的照明系统,该系统能够实现任意照明模式,并可以提高成像数值孔径,同时具有灵活高效、能量利用率高、易于实现等优点。本课题组通过计算仿真和搭建的实验装置验证了傅里叶合成技术实现任意照明模式的可行性,掌握了傅里叶照明系统所需的数值孔径合成方法,实现照明所需的发散度。基于优化的照明程序版图在实验中实现了圆盘、二级、四极、环形等照明模式,这些照明模式光强分布较均匀且照明形状无畸变。当MEMS二维振镜的扫描角度为±1°且选用收集镜成像倍率为10时,在收集镜上可以实现最大扫描照明尺寸超过30 mm,焦点面上的4×NA值超过0.6,这一结果可以匹配当前及下一代光刻工艺及掩模检测应用的照明需求。Results and Discussions The Fourier synthesis illumination device composed of MEMS and off-axis ellipsoidal mirrors can achieve various illumination patterns such as disk,dipole,quadrupole,and annular and the illumination area size(representing the partial coherent factor)and spacing of the illumination area can be adjusted.The tested illumination profile has no distortion and the illuminating intensity distribution is relatively uniform.When the MEMS scanning angle is±1°and the magnification of the ellipsoidal condenser is 10(i.e.,with an object distance of 1 m),the maximum illumination diameter can reach>30 mm on the condenser,and the 4×NA on the ellipsoid focal surface can reach>0.6.Moreover,the illumination area on the surface to be detected located at the imaging focal point of the ellipsoidal mirror was tested,and all scanning rays were concentrated in the same area on the surface to be detected.Neither the scanning mode nor scanning angle influences the position of the overlapping area.Ellipsoidal mirrors with different magnifications can be used to adjust the size of the illumination area on the surface,and the actual magnification of the illumination area is basically consistent with the theoretical value.Objective Off-axis illumination is an important resolution enhancement technology in lithography,and it can effectively enhance both resolution and the focal depth of the lithography tool.Conventional off-axis illumination methods,such as those using pupil filters,have the disadvantage of serious energy loss.Moreover,realizing a few special illumination patterns is difficult using transmission elements represented by an axicon,and diffractive elements have the problem that a single diffractive element corresponds to only one illumination pattern.In the EUV spectral band,because optical materials intensely absorb EUV radiation,the transmission elements and transmission type diffraction optical elements cannot be used.In the present study,we investigate an illumination system based on Fourier synthesis

关 键 词：傅里叶光学 傅里叶合成 光刻工艺 离轴照明 椭球收集镜 角度扫描 

分 类 号：O435.1[机械工程—光学工程]