基于宽带高次谐波的掩模版缺陷检测(特邀)  

Mask Blank Inspection with Multi-wavelength High Harmonic Source(Invited)

作　　者：李滢潇 曾志男 LI Yingxiao;ZENG Zhinan(State Key Laboratory of High Field Laser Physics,Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences,Shanghai 201800,China;Center of Materials Science and Optoelectronics Engineering,University of Chinese Academy of Sciences,Beijing 100049,China;Zhangjiang Lab,Shanghai 200120,China)

机构地区：[1]中国科学院上海光学精密机械研究所、强场激光物理国家重点实验室,上海201800 [2]中国科学院大学材料科学与光电子工程中心,北京100049 [3]张江实验室,上海200120

出　　处：《光子学报》2024年第6期92-100,共9页Acta Photonica Sinica

基　　金：国家自然科学基金(No.91950203)。

摘　　要：使用严格的时域有限差分法研究高次谐波光源的检测能力,探索不同波长光源的检测潜力。在综合考虑散射光效率和入射光光强的前提下,与光化波长检测相比,较长波长的光源如38 nm对直径小于10 nm的表面缺陷具有更好的检测能力。此外,38 nm波长光源对极紫外掩模版具有较好的穿透能力,可用于相位缺陷的检测。特别是对于具有特定高度和宽度的缺陷,如高度为7~20 nm,宽度为20~80 nm的浅层缺陷,38 nm波长光源具有较为可观的检测能力。该研究可为掩模版缺陷检测装置检测能力的提升提供指导。The fabrication of defect-free Extreme Ultraviolet(EUV)lithography mask blanks for future nodes remains a pressing challenge,driving the demand for high-sensitivity mask inspection tools for smaller defects.A typical EUV lithography mask blank is composed of more than 40 molybdenum/silicon(Mo/Si)bilayers coated on low thermal expansion glass,even minor imperfections in the EUV mask blank may lead to significant negative effects on the printing process.Such imperfections also called defects can be generally categorized into two types:amplitude defects and phase defects,posing extreme difficulty for non-EUV inspection systems.Therefore,in recent years,Actinic Blank Inspection(ABI)tools utilizing Microscopic Scattering Dark-field Imaging(MS-DFI)system have gained prominence;however,challenges for smaller nodes persist.These have spurred exploration of alternative sources,notably the High-Harmonic Generation(HHG)source.This work investigated the detection capabilities with HHG source using the rigorous finite-difference time-domain(FDTD)method.Normalized scattering signal intensity of different orders of HHG source are compared in order to identify the wavelength promising for enhanced detectability.The wavelength range we choose is 13.5~38 nm(i.e.,59~21th order).To investigate the basic features of different defects,three structural models have been employed.Surface defect model refer to the amplitude defect.Phase defects are divided into two categories:shallow defect model and deep defect model.The simulation results indicate that for surface defect,defects with specific diameters exhibit pronounced signals at wavelengths distinct from 13.5 nm.For defects below 10 nm,the scattering signal intensity of all wavelengths diminishes with decreasing defect size.However,the decline rate for sources around 30 nm is much slower than that for 13.5 nm,their intensity can be even higher for a defect of 2 nm diameter than that of 13.5 nm.The example is the 38 nm wavelength source:as the defect diameter decreases,the normalized

关 键 词：高次谐波 极紫外光刻 暗场成像 缺陷检测 有限时域差分法 

分 类 号：TN305.7[电子电信—物理电子学]