结构光照明显微成像技术在集成电路掩模检测中的应用  

Photomask Inspection in Integrated Circuits Using Structured Illumination Microscopy

作　　者：魏鑫 刘泽旭[2,3] 张子怡 陈韫懿 杨文河 曹晶 林楠 Wei Xin;Liu Zexu;Zhang Ziyi;Chen Yunyi;Yang Wenhe;Cao Jing;Lin Nan(School of Microelectronics,Shanghai University,Shanghai 200444,China;State Key Laboratory of High Field Laser Physics,Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences,Shanghai 201800,China;Key Laboratory of Ultra-intense Laser Science and Technology(CAS),Shanghai 201800,China)

机构地区：[1]上海大学微电子学院,上海200444 [2]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 [3]超强激光科学与技术重点实验室(中国科学院),上海201800

出　　处：《光学学报》2024年第11期179-186,共8页Acta Optica Sinica

摘　　要：针对集成电路成熟制程下的掩模检测需求,设计了一种适用于该应用场景的透射式结构光照明显微(SIM)检测系统。SIM技术在频率域内利用空间混频将物体的高频信息载入到光学系统的探测通带,从而使分辨率突破衍射极限。采用数字微镜器件(DMD)控制干涉光束的空间分布强度和相位,利用四方向照明(0°、45°、90°和135°,每个方向上分别有三个相位)提高各向同性的分辨率,并可选取级次较高的衍射光在样品表面产生高频结构光,进一步提高样品的空间分辨率。相较于大数值孔径的光学检测系统,该系统结构简单、灵活度高、分辨率提高潜力大。实验验证系统使用不同级次衍射光的成像能力,并简要分析影响SIM分辨率的因素,为基于该系统的优化和改良提供理论依据。Objective Inspection technology and equipment are crucial in the manufacturing of integrated circuits(ICs),and photomask inspection is key in lithography for ensuring IC manufacturing with high reliability and yield.Advanced semiconductor manufacturing has entered the 5 nm mass-production era,as represented by smartphones.However,the demand for mature processes(28 nm and above)remains high.This process technology is cost effective and can be widely used in appliances,consumer electronics,automotive electronics,and 5G communication.Therefore,methods that satisfy the requirements of photomask inspection in mature processes must be identified.Various photomask inspection methods have been employed.E-beam inspection(e.g.,scanning electron microscopy)has high-resolution(subnanometer)and high-sensitivity but low-throughput.Optical inspection is widely adopted because of its acceptable sensitivity at high throughput and its nondestructive nature.Owing to the optical diffraction limit,the spatial resolution of conventional wide-field microscopy is limited by the wavelength and numerical aperture(NA)of the objective.To achieve high resolutions,high-NA objectives are used;however,their design is complex and costly.Methods Structured illumination microscopy(SIM)can overcome the diffraction limit by transferring the high-frequency information of samples into the detectable frequency range of the imaging system via frequency mixing.The principle of transmission SIM is illustrated in Fig.1.Illuminating samples with interference patterns enables previously inaccessible high-frequency components to be encoded into the observed image,thereby improving the spatial resolution.In this study,a digital micromirror device(DMD)was used to create illumination patterns and switch beams with a spatially controlled intensity and phase.Four-orientation illumination(0°,45°,90°,and 135°,with each orientation used in three phases)was used to obtain a near-isotropic resolution and resolution enhancement.The DMD is based on microelectromechan

关 键 词：显微 光学系统 衍射光栅 图像重构技术 空间光调制器 

分 类 号：O435[机械工程—光学工程]