小角X射线散射中宇宙线噪声去除方法  

Cosmic Ray Rejection in Small Angle X-Ray Scattering

作　　者：赵晋 王成龙 喻虹[1,2,3] Zhao Jin;Wang Chenglong;Yu Hong(Key Laboratory for Quantum Optics,Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences,Shanghai 201800,China;Zhangjiang Laboratory,Shanghai 201210,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院上海光学精密机械研究所量子光学重点实验室,上海201800 [2]张江实验室,上海201210 [3]中国科学院大学,北京100049

出　　处：《光学学报》2024年第7期284-292,共9页Acta Optica Sinica

基　　金：项目受张江实验室支持。

摘　　要：针对小角X射线散射(SAXS)测量图样中的宇宙线提出一种去除方法,以纳米结构的周期信息为物理先验计算得到周期性散射信号的坐标信息,对各光斑级次有效信号区域内的宇宙线进行检测并去除。数值模拟了含宇宙线的SAXS测量图样序列,测试该方法对SAXS测量图样序列宇宙线的检测和去除效果,并与现有的宇宙线去除方法进行对比。计算不同曝光时间下去噪前和各方法去噪后SAXS测量图样的评价指标,可以说明该方法对于SAXS测量图样中的宇宙线具有良好的去除效果,并能在长曝光条件下获得明显的信噪比增益。Objective Small angle X-ray scattering(SAXS)is a powerful tool to measure structural features on the order of 1‒100 nm.Due to high measurement accuracy and strong penetrability,SAXS attracts much attention to characterizing the complex three-dimensional(3D)structure information of periodic nanostructures in integrated circuit(IC)and has been successfully applied to high aspect ratio(HAR)structures,such as 3D-NAND and DRAM.SAXS for IC inline metrology is mostly based on compact X-ray sources.Limited by the brightness of compact X-ray sources,SAXS measurement requires a long exposure time to improve the signal-to-noise(SNR)of SAXS signals.Since the integration effect of long exposure time,numerous cosmic rays are inevitably introduced in the SAXS measurement pattern.As a typical kind of noise that is not correlated with SAXS signals,cosmic rays appear in SAXS patterns randomly and cause signal distortion,which has a negative effect on nanostructure information extraction.However,for lack of making full use of the signal s periodicity information,present cosmic ray rejection algorithms cannot accurately identify and remove the cosmic rays that have a real influence on SAXS signals in the measurement pattern.A new cosmic ray rejection method is needed for SAXS measurement patterns of periodic nanostructures,which will help improve the SNR of SAXS patterns and the performance of nanostructure information extraction.Methods We propose a cosmic ray rejection method for the SAXS measurement pattern of periodic nanostructure.First,a pattern sequence including many short exposure SAXS measurement patterns of periodic nanostructure samples is generated in the same measurement conditions.Then,the coordinates of the periodic scattering signals are calculated by taking the periodic information of the nanostructure as physical prior,and cosmic rays existing in the effective signal area for each diffraction order in each scattering pattern are identified.After removing the abnormal frames influenced by cosmic rays from the pat

关 键 词：X射线光学 小角X射线散射 周期性纳米结构 宇宙线 去噪 

分 类 号：O434.19[机械工程—光学工程]