电子束品质评价方法综述

电子束品质评价方法综述
史丽娜，王鹏飞*，刘俊标，邓晨晖，殷伯华，韩  立*
（1.中国科学院电工研究所，北京 100190；2.中国科学院大学，北京 100049）

摘  要  电子显微类仪器广泛应用于微纳观测与精密加工领域，属于高端科学仪器。如何有效评价电子束品质是仪器开发者与使用者所关心的问题。然而，电子显微类仪器种类众多，根据应用的不同，电子束品质评价方法也有很大差异。因此，建立规范化的电子束评价方法，客观、准确和方便地评价电子束品质，是电子显微类仪器研制和应用方面的重要内容。本文基于电子显微类仪器中电子束性质，针对束流、束斑、束流密度和电子枪亮度等电子束品质参数，其中将束流和束斑定义作为直接评价参数，束流密度和电子枪亮度作为基本评价参数，分析了电子束评价参数不同测试方法的特点，从而对各种电子束评价方法进行分类归纳比较，同时将电子光学传递函数作为一种综合评价方法进行了总结分析。本文基于上述内容，可为建立规范化的电子束品质评价标准和测试方法提供参考依据。
关键词  电子显微类仪器；电子束品质；评价参数；测试方法
中图分类号：TN16  
文献标识码：A     doi:10.3969/j.issn.1000-6281.2024.06.013

Review of electron beam quality evaluation methods
SHI Lina1，2, WANG Pengfei1*, LIU Junbiao1，2, DENG Chenhui1, YIN Bohua1，HAN Li1，2*
（1. Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190；2. University of Chinese Academy of Sciences, Beijing 100083, China）

Abstract   Electron microscopy instruments are essential high-end scientific tools used for micro-nano observation and precision processing. Evaluating the quality of electron beams is a critical concern for both instrument developers and users. With the variety of electron microscopy instruments available, evaluation methods for electron beam quality can differ significantly depending on the applications. Thus, establishing a standardized method for evaluating electron beam quality is critical for the development and application of electron microscopy instruments. In this paper, we analyzed electron beam quality parameters such as beam current, beam spot, beam density, and electron gun brightness. We categorized beam current and beam spot as direct evaluation parameters, while beam density and electron gun brightness are defined as the basic evaluation parameters. We reviewed the characteristics of different test methods for these parameters, generalizing and comparing different evaluation methods. Additionally, we summarized and analyzed the electron optical transfer function as a comprehensive evaluation method. This paper aims to provide a reference for establishing standardized evaluation standards and testing methods of electron beam quality.
Keywords  electron microscopy instruments；electron beam quality；evaluation parameters；measurement methods

[1] ASKEW H J, JARVIS K L, JONES R T, et al. Electron beam lithography nanopatterning of plasma polymers [J]. Macromol Chem Phys, 2021, 222(12): 1-9.
[2] ENGEL A. Biological applications of the scanning transmission electron microscope [J]. Journal of Structural Biology, 2022, 214(2): 1-9.
[3] SUN C, LUX S F, MULLER E, et al. Versatile application of a modern scanning electron microscope for materials characterization [J]. J Mater Sci, 2020, 55(28): 13824-13835.
[4] 国家质量监督检验检疫总局计量司. JJF 1001-2011, 通用计量术语及定义 [S].北京: 中国质检出版社, 2011.
[5] 邹澎, 周晓萍, 马力. 电磁场与电磁波(第2版):电子信息学科基础课程系列教材[M]. 北京:清华大学出版社, 2016, 74-75.
[6] KRAUSE F F, SCHOWALTER M, OPPERMANN O, et al. Precise measurement of the electron beam current in a TEM [J]. Ultramicroscopy, 2021, 223: 1-11.
[7] MITCHELL D R G, NANCARROW M J B. Probe current determination in analytical TEM/STEM and its application to the characterization of large area EDS detectors [J]. Microsc Res Tech, 2015, 78(10): 886-893.
[8] 彭勇. 电子束焊接束流品质测试方法及系统研究 [D].南京：南京理工大学, 2013.
[9] 周琦, 刘方军, 关桥. 电子束流焦点和测量方法进展及分类 [J]. 焊接, 2004(1): 5-10.
[10] 邓晨晖, 王岩, 刘俊标,等. 荷电控制电子枪特性的测量 [J]. 真空科学与技术学报, 2020, 40(9): 847-852.
[11] BOK J, HORACEK M, KOLARIK V, et al. Measurements of current density distribution in shaped e-beam writers [J]. Microelectron Eng, 2016, 149: 117-124.
[12] GAVRILENKO V P, NOVIKOV Y A, RAKOV A V, et al. Measurement of the parameters of the electron beam of a scanning electron microscope [J]. Proceedings of SPIE - The International Socity for Optical Engineering, 2008, 7042: 1-12.
[13] KNOROVSKY G A, NOWAK-NEELY B M, HOLM E A. Microjoining with a scanning electron microscope [J]. Sci Technol Weld Join, 2006, 11(6): 641-649.
[14] RISHTON S A, BEAUMONT S P, WILKINSON C D W. Measurement of the profile of finely focused electron beams in a scanning electron microscope [J]. Journal of Physics E-Scientific Instruments, 1984, 17(4): 296-303.
[15] HUBER C, ORLOV S, BANZER P, et al. Corrections to the knife-edge based reconstruction scheme of tightly focused light beams [J]. Opt Express, 2013, 21(21): 25069-25076.
[16] YAMAZAKI K, NAMATSU H. Electron-beam diameter measurement using a knife edge with a visor for scattering electrons [J]. Jpn J Appl Phys Part 2 - Lett Express Lett, 2003, 42(5A): L491-L493.
[17] DANILATOS G D. Electron scattering cross-section measurements in ESEM [J]. Micron, 2013, 45: 1-16.
[18] REISGEN U, OLSCHOK S, DEVRIES J, et al. Accurate diagnostic of electron beam characteristics [J]. DVS-Berichte, 2014, 5(6): 40-45.
[19] SATO M, ORLOFF J. A method for calculating the current density of charged particle beams and the effect of finite source size and spherical and chromatic aberrations on the focusing characteristics [J]. J Vac Sci Technol B, 1991, 9(5): 2602-2608.
[20] BABIN S, GAEVSKI M, JOY D, et al. Automatic measurement of electron-beam diameter and astigmatism: Beametr [J]. Physics Procedia, 2008, 1(1):113-118.
[21] ZOTTA M D, NEVINS M C, HAILSTONE R K, et al. The Determination and Application of the Point Spread Function in the Scanning Electron Microscope [J]. Microsc Microanal, 2018, 24(4): 396-405.
[22] 第一机械工业部电器科学研究院. 电子束加工及其装置 译文集 [M]. 北京：第一机械工业部技术情报所, 1965.
[23] KOLEVA E, VUTOVA K, WOJCICKI S, et al. Use of radial distributions of the beam current density for evaluation of beam emittance and brightness [J]. Vacuum, 2001, 62(2-3): 105-111.
[24] DANILATOS G D. Foundations of environmental scanning electron microscopy [J]. Adv Electron Electron Phys, 1988, 71: 109-250.
[25] 丁德成. 微小尺寸电子注束斑的测量和分析 [D].成都：电子科技大学, 2016.
[26] 韩放达, 肖永顺, 常铭,等. X 射线源焦点尺寸测量方法和标准综述 [J]. 中国体视学与图像分析, 2014, 19(4): 321-329.
[27] 陈振生, 杨立才, 张玉林. 电子束曝光机束斑的自动测控系统 [J]. 微细加工技术, 1996(4): 16-22.
[28] 崔立夫, 罗瑞芳. 高斯光束参数简介及束腰的快速测量计算 [J]. 天津科技, 2018, 45(1): 27-31.
[29] ZHU X, MUNRO E, ROUSE J A, et al. Quantitative aberration assessment by a through focal analysis of pattern edge sharpness [J]. Proceedings of SPIE - The International Society for Optical Engineering, 1999, 3777: 35-46.
[30] International Organization for Standardization, ISO 11146-1:2021, Lasers and laser-related equipment - Test methods for laser beam widths, divergence angles and beam propagation ratios - Part 1: Stigmatic and simple astigmatic beams [S]. British, BSI Standards, 2021.
[31] BURGARDT P, PIERCE S W, DVORNAK M J. Definition of beam diameter for electron beam welding [J]. Los Alamos National Laborayory, 2016, 21655: 1-36
[32] 华中一, 顾昌鑫. 电子光学 [M]. 上海：复旦大学出版社, 1990.
[33] International Organization for Standardization, ISO 11146-2:2021, Lasers and laser-related equipment - Test methods for laser beam widths, divergence angles and beam propagation ratios - Part 2: General astigmatic beams [S]. British, BSI Standards, 2021.
[34] BRONSGEEST M S, BARTH J E, SWANSON L W, et al. Probe current, probe size, and the practical brightness for probe forming systems[J]. Journal of Vacuum Science & Technology B Microelectronics & Nanometer Structures Processing Measurement & Phenomena, 2008, 26(26):949 - 955.
[35] RIHACEK T, HORAK M, SCHACHINGER T, et al. Beam shaping and probe characterization in the scanning electron microscope [J]. Ultramicroscopy, 2021, 225: 1-9.
[36] GOLDENSHTEIN A, GOLD Y I, CHAYET H. Measuring the size and intensity distribution of SEM beam spot [J]. Proceedings of SPIE - The International Society for Optical Engineering, 1998, 3332: 132-137.
[37] BABIN S, GAEVSKI M, JOY D, et al. Technique to automatically measure electron-beam diameter and astigmatism: BEAMETR [J]. Journal of Vacuum Science & Technology B, Microelectronics and Nanometer Structures: Processing, Measurement, and Phenomena: An Official Journal of the American Vacuum Society, 2006, 24(6): 2956-2959.
[38] HANAI T, HIBINO M. Effect of the spherical aberration on electron probe size [J]. Journal of Electron Microscopy, 1984, 33(2): 116-122.
[39] OHO E, SASAKI T, ADACHI K, et al. Measurement of electron probe beam diameter by digital image processing [J]. Microscopy Research & Technique, 1985, 2(5): 463-469.
[40] MICHAEL J R, WILLIAMS D B. A consistent definition of probe size and spatial resolution in the analytical electron microscope [J]. Journal of Microscopy, 1987, 147: 289-303.
[41] LIDDLE J A, NAULLEAU P, SCHMID G. Probe shape measurement in an electron beam lithography system [J]. J Vac Sci Technol B, 2004, 22(6): 2897-2901.
[42] ZOTTA M D, NEVINS M C, HAILSTONE R K, et al. The determination and application of the point spread function in the scanning electron microscope [J]. Microsc Microanal, 2018, 24(4): 396-405.
[43] KOLEVA E, MLADENOV G, TODOROV D, et al. Electron beam characterization by a tomographic approach [J]. Journal of Physics Conference Series, 2016, 700(1): 1-9.
[44] ELMER J W, TERUYA A T. Fast method for measuring power density distribution of non-circular and irregular electron beams [J]. Sci Technol Weld Join, 1998, 3(2): 51-58.
[45] ELMER J W, TERUYA A T, OBRIEN D W. Tomographic imaging of noncircular and irregular electron beam current density distributions [J]. Weld J, 1993, 72(11): S493-S505.
[46] ELMER J W, TERUYA A T. An enhanced faraday cup for rapid determination of power density distribution in electron beams [J]. Weld J, 2001, 80(12): 288S-295S.
[47] WóJCICKI S, MLADENOV G. A new method of experimental investigation of high-power electron beam [J]. Vacuum, 2000, 58: 523-530.
[48] DILTHEY U, GOUMENIOUK A, BOHM S, et al. Electron beam diagnostics: a new release of the diabeam system [J]. Vacuum, 2001, 62: 77-85.
[49] PENGFEI F, YAJUN W, ZHIYONG M, et al. Electron beam diagnostics of power density by DIABEAM method [J]. Chinese Journal of vacuum science and technology, 2010, 30(2): 189-192.
[50] 严瑗, 钟伟杰, 张学渊, 等. 一种微米级电子束焦斑尺寸的光学测量装置及其方法: 中国, CN102538670A[P]. 20120704.
[51] HONG W J, XIN C Z, JING D, et al. Review on transmission electron microscopy cameras and single particle Cryo⁃EM data preprocessing flow [J]. Journal of Chinese Electron Microscopy Society, 2022, 41(6): 654-663.
[52] ZOTTA M, JOIS S, DHAKRAS P, et al. Direct measurement of the electron beam intensity profile via carbon nanotube tomography [J]. Nano Letters, 2019, 19: 4435-4441.
[53] BOK J, KOLARIK V, HORACEK M, et al. Modified knife-edge method for current density distribution measurements in e-beam writers [J]. J Vac Sci Technol B, 2013, 31(3): 6.
[54] SAWADA S I, HAMADA N. Energetics of carbon nano-tubes [J]. The European Physical Journal D, 1992, 4(11):331-333.
[55] TANG Z K, ZHANG L Y, WANG N, et al. Ultra-small single-walled carbon nanotubes and their superconductivity properties [J]. Synthetic Metals, 2001, 133(11): 689-693.
[56] ZHAO X, LIU Y, INOUE S, et al. Smallest Carbon Nanotube Is 3 Å in Diameter [J]. Physical Review Letters, 2004, 92(12): 1-3.
[57] SHIMOYAMA H, MARUSE S. Theoretical considerations on electron optical brightness for thermionic, field and T-F emissions [J]. Ultramicroscopy, 1984, 15(3): 239-254.
[58] GESLEY M, HOHN F. Emission distribution, brightness, and mechanical stability of the LaB6 triode electron gun [J]. Journal of Applied Physics, 1988, 64(7): 3380-3392.
[59] FRANSEN M J, OVERWIJK M H F, KRUIT P. Brightness measurements of a ZrO/W Schottky electron emitter in a transmission electron microscope [J]. Applied Surface Science, 1999, 146: 357-362.
[60] HANSZEN K J, LAUER R. Richtstrahlwertmessungen mit dem Zwei-Blendenverfahren an Elektronenstrahlern mit Kugelkathoden von 250 bis 1.5µm Durchmesser [J]. Zeitschrift für Naturforschung Section A, 1967, 22(2): 238-254.
[61] COOK B J. Brightness limitations in sources for static and ultra-fast high resolution electron microscopy [D]. Netherlands: Technische Universiteit Delft, 2013.
[62] REIMER L. Scanning electron microscopy: Physics of image formation and microanalysis [M]. Second Edition. New York: Springer-Verlag Berlin Heidelberg, 1998.
[63] SPEIDEL R, KURZ D. Directivity measurements of a beam generating system with field emission cathode [J]. Optik, 1977, 2: 173.
[64] 唐天同. 应用带电粒子光学引论 [M]. 西安：西安交通大学出版社, 1986.
[65] BOREMAN G D. Modulation transfer function in optical and electro-optical systems [J]. Russchemrev, 2001, 71(2): 159–179.
[66] 宋敏, 胡家升, 李叶芳,等. 测量CCD传递函数的实验系统 [J]. 中国激光, 1999(4): 40-44.
[67] WITTENSTEIN W, FONTANELLA J C, NEWBERY A R, et al. The definition of the OTF and the measurement of aliasing for sampled imaging systems [J]. Optica Acta International Journal of Optics, 1982, 29(1): 41-50.