摘要
缺陷检测是基于金属膜层激发表面等离子体进行超衍射加工前的重要工艺流程,但目前先进空白晶圆缺陷检测设备光源多位于深紫外波段,恰好在KrF等深紫外光刻胶的感光范围内,检测带有该光刻胶的晶圆表面时易导致光刻胶感光而改性失效。针对此问题,笔者提出并设计了一种基于可见光波段的激光偏振暗场检测装置。该装置利用晶圆表面顶层银膜的偏振转换特性,通过调控入射光的偏振态与入射角,使微粗糙银膜表面的弱散射光偏振态与膜层表面颗粒的散射光偏振态产生差异,然后利用偏振器件对来自银膜表面的散射光进行部分滤除,有效提高了颗粒信号的信噪比。实验结果表明:所设计的装置在不影响光刻胶的同时还可以减少金属膜层表面散射所带来的缺陷误检。在对百纳米级颗粒进行检测时,由于使用了激光照明及高灵敏度的sCMOS作为探测器件,本装置单次曝光时间仅为150μs,是奥林巴斯公司基于白光的DSX1000暗场显微镜的4‰左右。通过抑制噪声,笔者采用该装置实测了均方根(RMS)粗糙度为3.4 nm的银膜表面上直径为61 nm的聚苯乙烯乳胶颗粒,结果显示,该装置在探测极限和探测效率上较DSX1000均有较大提升。
Objective Defect detection is an essential process for realizing superdiffraction fabrication based on metal film layer excitation surface plasmons.However,the light source of most existing advanced defect detection equipment operates in the deep ultraviolet band(DUV),which is within the light-sensitive range of DUV photoresists such as KrF.The overlap of working wavelengths between the defect detection equipment and the DUV photoresist can result in a loss of photoresist efficacy.Furthermore,to avoid the influence of the detection equipment's working wavelength on the photoresist when DUV equipment is used to detect particles on the surface of the film,it is necessary to tune the equipment's incident intensity several times.Moreover,the equipment parameters after tuning are only effective for a single film structure.It is necessary to retune equipment parameters when changing the thickness,material,and the number of film layers,which is time consuming and labor intensive.Therefore,a defect-detection device with a wide range of applications that avoids photoresist-sensitive bands must be developed to address this challenge.Methods In this study,visible laser polarization defect detection equipment consisting of three parts:polarization modulation,darkfield detection,and motion control(Fig.8),is theoretically and experimentally demonstrated.A more sensitive scientific CMOS(sCMOS)is used to detect particle scattering signals.The equipment utilizes the polarization conversion principle of a silver film on the top layer of the wafer surface.By modulating the polarization state and incident angle of the incident light,the scattered light polarization states on the slightly rough silver film surface and the particles on the film surface are different.On the receiving side,the light scattered from the surface of the silver film is partially filtered using a polarization detection device,which improves the signal-tonoise ratio of the particle signal to achieve defect detection.Based on the aforementioned principles,exper
作者
邓泉
赵泽宇
林鹤
刘玲
李夏楚秦
杨根森
罗先刚
Deng Quan;Zhao Zeyu;Lin He;Liu Ling;Li Xiachuqin;Yang Gensen;Luo Xiangang(State Key Laboratory of Optical Technologies on Nano-Fabrication and Micro-Engineering,Institute of Optics and Electronics,Chinese Academy of Sciences,Chengdu 610209,Sichuan,China;School of Optoelectronics,University of Chinese Academy of Sciences,Beijing 100049,China;School of Automation Engineering,University of Electronic Science and Technology of China,Chengdu 610054,Sichuan,China)
出处
《中国激光》
EI
CAS
CSCD
北大核心
2023年第22期90-100,共11页
Chinese Journal of Lasers
基金
国家自然科学基金(62005288)
国家重点研发计划(2021YFA1401000)。
关键词
测量
光学检测
散射测量
表面粗糙度
偏振调控
纳米颗粒
信噪比
measurement
optical inspection
scattering measurement
surface roughness
polarization manipulation
nano-particles
signal-to-noise ratio
