氧化物材料的氧环境扫描电镜分析
摘要
本论文提出氧环境扫描电子显微分析方法，以减轻和补偿非导电氧化物类样品在电子束辐照作用下的表面充电现象。
在常规扫描电子显微镜（SEM）中引入一定的氧气(样品室真空度仍维持在2×10-3( 4×10-2 Pa)，直接观察和分析非导电样品，而不需要在样品表面镀导电膜。同时不改变扫描电子显微镜原有的电子光学系统和探测系统。
本工作搭建了扫描电子显微镜的氧气输送和控制装置。采用pA-电流表测量吸收电流信号，评价Al2O3、Cu/SiO2、用Y2O3稳定的ZrO2(YS-ZrO2)等氧化物表面的充电现象，以及氧环境的充电补偿作用。此外，通过样品加热和改变电镜的成像参数等方法，减轻非导电样品表面的充电效应。
在10-3～10-2 Pa的氧环境中观察到Al2O3和Cu/SiO2样品表面的充电现象得到明显减轻。对YS-ZrO2样品加热到230℃，使其表面充电得到改善。
本文讨论了在电子束辐照下，Al2O3、SiO2、YS-ZrO2等氧化物材料的充电机制，以及氧环境的充电补偿机制。电子束轰击造成表面电子受激解吸和电子束对内部缺陷的调制是充电的主要原因。对于样品表面电子受激解吸造成的充电可通过氧环境提供补偿,氧环境主要是通过及时补充氧空位、修复能带扭曲起作用的； 对于电子束调制内部缺陷造成的充电可通过加热试样减轻缺陷浓度来补偿。
氧环境扫描电子显微分析是针对氧化物类非导电材料直接成像和分析的一种新颖而实用的方法。
In order to reduce and compensate charge phenomena at the surface of non-conductive oxide materials under the electron irradiation, oxygen environmental scanning electron microscopy (SEM) is offered in this thesis.
Introduce oxygen environment in general SEM (sample chamber in high vacuum of 2×10-3( 4×10-2 Pa), and directly observe and analyze materials (no conductive films), simultaneously, keep original electron optical and detecting system unchanged.
In this work the devices of feeding and controlling oxygen are set up. Absorbable current is measured with a PA meter in order to estimate charge phenomena of non-conductive oxide materials (for example Al2O3、Cu/SiO2、YS-ZrO2 etc) and charge compensation in oxygen environmental SEM. Heating specimen and changing imaging parameter are performed to reduce charge phenomena.
For Al2O3 and Cu/SiO2, a strong charge reduction is observed in oxygen environment of 10-3～10-2 Pa; Charge phenomena of YS-ZrO2 are reduced through heating to 230℃.
The mechanisms of charge and charge compensation are discussed: We suggest electron stimulated desorption (ESD) at the surface and inner defects induced by the electron beam bombardment are main reasons of charge. The charge related to ESD can be compensated by oxygen environment, oxygen environment works mainly through making up oxygen vacancy and repairing energy band distortion in time. Heating the sample and reducing defect concentration can reduce the charge related to inner defects.
Oxygen environmental scanning electron microscopy is a new and practical method for directly observing and analyzing non-conductive oxide materials.
在常规扫描电子显微镜（SEM）中引入一定的氧气(样品室真空度仍维持在2×10-3( 4×10-2 Pa)，直接观察和分析非导电样品，而不需要在样品表面镀导电膜。同时不改变扫描电子显微镜原有的电子光学系统和探测系统。
本工作搭建了扫描电子显微镜的氧气输送和控制装置。采用pA-电流表测量吸收电流信号，评价Al2O3、Cu/SiO2、用Y2O3稳定的ZrO2(YS-ZrO2)等氧化物表面的充电现象，以及氧环境的充电补偿作用。此外，通过样品加热和改变电镜的成像参数等方法，减轻非导电样品表面的充电效应。
在10-3～10-2 Pa的氧环境中观察到Al2O3和Cu/SiO2样品表面的充电现象得到明显减轻。对YS-ZrO2样品加热到230℃，使其表面充电得到改善。
本文讨论了在电子束辐照下，Al2O3、SiO2、YS-ZrO2等氧化物材料的充电机制，以及氧环境的充电补偿机制。电子束轰击造成表面电子受激解吸和电子束对内部缺陷的调制是充电的主要原因。对于样品表面电子受激解吸造成的充电可通过氧环境提供补偿,氧环境主要是通过及时补充氧空位、修复能带扭曲起作用的； 对于电子束调制内部缺陷造成的充电可通过加热试样减轻缺陷浓度来补偿。
氧环境扫描电子显微分析是针对氧化物类非导电材料直接成像和分析的一种新颖而实用的方法。
In order to reduce and compensate charge phenomena at the surface of non-conductive oxide materials under the electron irradiation, oxygen environmental scanning electron microscopy (SEM) is offered in this thesis.
Introduce oxygen environment in general SEM (sample chamber in high vacuum of 2×10-3( 4×10-2 Pa), and directly observe and analyze materials (no conductive films), simultaneously, keep original electron optical and detecting system unchanged.
In this work the devices of feeding and controlling oxygen are set up. Absorbable current is measured with a PA meter in order to estimate charge phenomena of non-conductive oxide materials (for example Al2O3、Cu/SiO2、YS-ZrO2 etc) and charge compensation in oxygen environmental SEM. Heating specimen and changing imaging parameter are performed to reduce charge phenomena.
For Al2O3 and Cu/SiO2, a strong charge reduction is observed in oxygen environment of 10-3～10-2 Pa; Charge phenomena of YS-ZrO2 are reduced through heating to 230℃.
The mechanisms of charge and charge compensation are discussed: We suggest electron stimulated desorption (ESD) at the surface and inner defects induced by the electron beam bombardment are main reasons of charge. The charge related to ESD can be compensated by oxygen environment, oxygen environment works mainly through making up oxygen vacancy and repairing energy band distortion in time. Heating the sample and reducing defect concentration can reduce the charge related to inner defects.
Oxygen environmental scanning electron microscopy is a new and practical method for directly observing and analyzing non-conductive oxide materials.
引文
1 姚骏恩. 电子显微镜的现状与展望. 电子显微学报. 1998,17(6):767～776
2 J.Cazaux. Electron-and X-ray-induced Electron Emissions from Insulator. Polymer International. 2001,50: 748～755
3 J.Cazaux, C.L.Gressus. Phenomena Relating to Charging in Insulators: Microscopic Effects and Microscopy Cause. Scanning Microscopy. 1991, 5(1): 17～27
4 J.Cazaux. About the Charge Compensation of Insulating Samples in XPS. Journal of Electron Spectroscopy and Related Phenomena. 2000, 113 (1):15～33
5 J.Cazaux. About the Secondary Electron Yield and the Sign of Charging of Electron Irradiated Insulators. The European Physical Journal. Applied Physics. 2001,15:167～172
6 M.Belhaj, S.Odof, K.Msellak, O.Jbara. Time-dependent Measurement of the Trapped Charge in Electron Irradiated Insulators: Application to Al2O3-sapphire. Journal of Applied Physics. 2000,88(5):2289～2294
7 N.Dammak, F.Trigui, T.Temga, A.Kallel, Z.Fakhfakh, D.Treheux. Study of Charging Phenomena in MgO Single Crystal: Effect of Polishing, Annealing Temperature and Crystallographic Orientation. Journal of the European Ceramic Society. 2002,22(7):1149～1154
8 S.J.Stowe, V.N.E.Robinson. Use of helium gas to reduce beam scattering in high vapour pressure scanning electron microscopy applications. Journal of Scanning Microscopy. 1998,22(1):57～60
9 J.K.Lee, J.T.L.Thong, W.K.Wong. Reduction of Charging Effects Using Pseudo-random Scanning in the Scanning Electron Microscope. Journal of Scanning Microscopies. 2000,22(2):112～113
10 H.Johansen, W.Erfurth, S.Gogoll, E.Stenzel, M.Reichling, E.Matthias. Scanning Electron Microscopy Imaging of Microcracks and Charging Phenomena on a Laser-damaged CaF2 Surface. Journal of Scanning Microscopy. 1997,19(6):416～425
11 Z.G.Song, C.K.Ong, H.Gong. Secondary and Backscattered Electron Yields of Polymer Surface under Electron Beam Irradiation. Applied Surface Science. 1997,119(1～2):169～175
12 H.Johansen, G.Kaestner. Surface Quality and Laser-damage Behaviour of Chemo-mechanically Polished CaF2 Single Crystals Characterized by Scanning Electron Microscopy. Journal of Materials Science. 1998,33(15):3839～3848
13 D.J.Miller. Artifacts of Specimen Charging in X-ray Microanalysis in the Scanning Electron Microscope. Ultramicroscopy. 1991,35(3～4):357～366
14 M.Asadi, F.W.Preston. Characterization of the Jet Perforation Crushed Zone by SEM and Image Analysis. SPE Formation Evaluation. 1994,9(2):135～139
15 F.M.Roche, S.D.Bocus, P.Girard. Effect of Well and Substrate Parameters on the Latchup Degradation of CMOS Structures during E-beam Voltage Contrast Measurements. Microelectronic Engineering. 1991,15(1～4):113～116
16 M.Toth, M.R.Phillips. Effects of Space Charge on Contrast in Images Obtained Using the Environmental Scanning Electron Microscope. Journal of Scanning Microscopies. 2000,22(5):319～325
17 S.A.M.Refaey, G.Schwitzgebel, O.Schneider. Electrochemical Impedance Studies on Oxidative Degradation, Overoxidative Degradation, Deactivation and Reactivation of Conducting Polymers. Synthetic Metals. 1999,98(3):183～192
18 P.Roschger, J.Eschherger, H.J.Plenk. Formation of Ultracracks in Methacrylate-embedded Undeclacified Bone Samples by Exposure to Aqueous Solutions. Cells and Materials. 1993,3(4):361～365
19 J.Y.Liu. High-resolution and Low-voltage FE-SEM Imaging and Microanalysis in Materials Characterization. Materials Characterization. 2000,44(4):353～363
20 W.K.Chim, D.S.H.Chan, T.S.Low, J.C.H.Phang, K.S.Sim, K.L.Pey. Modelling Techniques for the Quantification of Some Electron Beam Induced Phenomena. Scanning Microscopy. 1992,6(4):961～978
21 J.M. Preben, J.W. He. Electron Beam Induced Charging of Cu/MgO Interface. Nuclear Instruments and Methods in Physics Research. 1986,B 17:137～140
22 S.M.Rowland, R.M.Hill, L.A.Dissado. Censored Weibull Statistics in the Dieletric Breakdown of Thin Oxide Films. Journal of Physics. C: Solid State Physics. 1986,19:6263～6285
23 L.Reimer. Scanning Electron Microscopy. Springer. 1998:120～134
24 J.Cazaux, P.Lehuede. Some Physical Descriptions of Charging Effects of Insulators under Incident Particle Bombardment. Journal of Electron Spectroscopy and Related Phenomena. 1992,59:49～71.
25 S.Ichmura, H.E.Bauer, H.Seiler, S.Hofmann. Surf. Interface Anal. 1989, 14:250
26 K.Kanaya, N.Ichise, K.Adachi, K .Yonehara, Y.Muranaka. Observation on Charging Effects of Non-conductive and Uncoated Materials by Ion Beam Pre-bombardment in Scanning Electron Microscopy. Micron and Microscopia Acta. 1992,23: 319～325
27 陈文雄, 徐军, 张会珍. 扫描电镜的最新发展-低电压扫描电镜(LVSEM)和扫描低能电镜(SLEEM). 电子显微学报. 2001,20(4):258～262
28 邵曼君. 环境扫描电镜及其应用. 物理. 1998,27（1）:48－52
29 王宝锋, 赵忠扬. 环境扫描电镜及其在石油技术中的应用. 油田化学. 1999,16（3）:278－281
30邵曼君. 环境扫描电镜原位研究纯Fe表面氧化过程. 金属学报. 2000,36（3）:230－234
31 余健业, 谢信能, 刘廷壁, 邵曼君, 黄兰友. 高温环境扫描电镜 (KYKY1500)Ⅰ.成像原理及仪器特点. 电子显微学报. 1997,16(1):57～64
32 邵曼君, 赵万敏, 肖骅昭, 段岳, 余健业, 黄兰友. 高温环境扫描电镜(KYKY1500)Ⅱ.调试与应用. 电子显微学报. 1997,16(1):65～70
33洪健, 徐正. 环境扫描电镜在生物学上的应用. 杭州电子工业学院学报. 2000,20(3):48～52
34 李春艳, 杜海燕, 董向红等. 环境扫描电子显微镜中的电子传输. 电子显微学报. 2001,20(4):287～288
35 段岳, 邵曼君. 绝缘样品在KYKY-1500环境扫描电镜中的直接观察. 化工冶金. 1996,17(1):66～70
35 邵曼君, 段岳, 李惠君, 李竹川. 纯铁、镍氧化晶须生长的动态环境扫描电镜研究. 电子显微学报. 1996, 15(6):540
37 L.Reimer. Electron-Specimen Interaction and Image Formation in LVSEM. Electron Microscopy. 1992,1:9～17
38 H.S.Guo, W.Maus-Friedrichs, V.Kempter. Charging Phenomena and Charge Compensation in AES on Metal Oxide and Silica. Surface and Interface Analysis. 1997, 25:390～396
39 H.S.Guo, W.Maus-Friedrichs, V.Kempter. Charge Trapping and Charge Compensation during AES on SiO2. Journal of Applied Physics. 1999, 86:2337～2341
40 H.S.Guo, W.Maus-Friedrichs, V.Kempter. The Relation between Preexisting Defects and Charging-up in 9mol% Y2O2-ZrO2 Studied by AES. Chinese Physics.2000,9(3):225～232
41 H.S.Guo, W.Maus-Friedrichs, V.Kempter, J.X.Shi. A Study of the Charging Phenomena during Electron Irradiation of Sintered Si3N4. Nuclear Instruments and Methods in Physics Research. 2001,B 173: 463～469
42郭汉生，史佳新. 俄歇电子能谱实验中Al2O3的荷电现象及其消除办法. 2000年材料科学与工程新进展. 冶金工业出版社. 2001:1843－1846
43史佳新, 吉 元, 徐学东, 肖卫强, 张隐奇, 郭汉生. 氧环境扫描电镜对氧化物的荷电补偿.( 北京工业大学学报. 2003, 29(2)，待发表)
44 Y.Ji, H.S.Guo, X.D.Xu, J.X.Shi. A Preliminary Study of Oxygen Environmental SEM: Application on Oxides. (Accepted by Journal of Trace and Microprobe Techniques)
2 J.Cazaux. Electron-and X-ray-induced Electron Emissions from Insulator. Polymer International. 2001,50: 748～755
3 J.Cazaux, C.L.Gressus. Phenomena Relating to Charging in Insulators: Microscopic Effects and Microscopy Cause. Scanning Microscopy. 1991, 5(1): 17～27
4 J.Cazaux. About the Charge Compensation of Insulating Samples in XPS. Journal of Electron Spectroscopy and Related Phenomena. 2000, 113 (1):15～33
5 J.Cazaux. About the Secondary Electron Yield and the Sign of Charging of Electron Irradiated Insulators. The European Physical Journal. Applied Physics. 2001,15:167～172
6 M.Belhaj, S.Odof, K.Msellak, O.Jbara. Time-dependent Measurement of the Trapped Charge in Electron Irradiated Insulators: Application to Al2O3-sapphire. Journal of Applied Physics. 2000,88(5):2289～2294
7 N.Dammak, F.Trigui, T.Temga, A.Kallel, Z.Fakhfakh, D.Treheux. Study of Charging Phenomena in MgO Single Crystal: Effect of Polishing, Annealing Temperature and Crystallographic Orientation. Journal of the European Ceramic Society. 2002,22(7):1149～1154
8 S.J.Stowe, V.N.E.Robinson. Use of helium gas to reduce beam scattering in high vapour pressure scanning electron microscopy applications. Journal of Scanning Microscopy. 1998,22(1):57～60
9 J.K.Lee, J.T.L.Thong, W.K.Wong. Reduction of Charging Effects Using Pseudo-random Scanning in the Scanning Electron Microscope. Journal of Scanning Microscopies. 2000,22(2):112～113
10 H.Johansen, W.Erfurth, S.Gogoll, E.Stenzel, M.Reichling, E.Matthias. Scanning Electron Microscopy Imaging of Microcracks and Charging Phenomena on a Laser-damaged CaF2 Surface. Journal of Scanning Microscopy. 1997,19(6):416～425
11 Z.G.Song, C.K.Ong, H.Gong. Secondary and Backscattered Electron Yields of Polymer Surface under Electron Beam Irradiation. Applied Surface Science. 1997,119(1～2):169～175
12 H.Johansen, G.Kaestner. Surface Quality and Laser-damage Behaviour of Chemo-mechanically Polished CaF2 Single Crystals Characterized by Scanning Electron Microscopy. Journal of Materials Science. 1998,33(15):3839～3848
13 D.J.Miller. Artifacts of Specimen Charging in X-ray Microanalysis in the Scanning Electron Microscope. Ultramicroscopy. 1991,35(3～4):357～366
14 M.Asadi, F.W.Preston. Characterization of the Jet Perforation Crushed Zone by SEM and Image Analysis. SPE Formation Evaluation. 1994,9(2):135～139
15 F.M.Roche, S.D.Bocus, P.Girard. Effect of Well and Substrate Parameters on the Latchup Degradation of CMOS Structures during E-beam Voltage Contrast Measurements. Microelectronic Engineering. 1991,15(1～4):113～116
16 M.Toth, M.R.Phillips. Effects of Space Charge on Contrast in Images Obtained Using the Environmental Scanning Electron Microscope. Journal of Scanning Microscopies. 2000,22(5):319～325
17 S.A.M.Refaey, G.Schwitzgebel, O.Schneider. Electrochemical Impedance Studies on Oxidative Degradation, Overoxidative Degradation, Deactivation and Reactivation of Conducting Polymers. Synthetic Metals. 1999,98(3):183～192
18 P.Roschger, J.Eschherger, H.J.Plenk. Formation of Ultracracks in Methacrylate-embedded Undeclacified Bone Samples by Exposure to Aqueous Solutions. Cells and Materials. 1993,3(4):361～365
19 J.Y.Liu. High-resolution and Low-voltage FE-SEM Imaging and Microanalysis in Materials Characterization. Materials Characterization. 2000,44(4):353～363
20 W.K.Chim, D.S.H.Chan, T.S.Low, J.C.H.Phang, K.S.Sim, K.L.Pey. Modelling Techniques for the Quantification of Some Electron Beam Induced Phenomena. Scanning Microscopy. 1992,6(4):961～978
21 J.M. Preben, J.W. He. Electron Beam Induced Charging of Cu/MgO Interface. Nuclear Instruments and Methods in Physics Research. 1986,B 17:137～140
22 S.M.Rowland, R.M.Hill, L.A.Dissado. Censored Weibull Statistics in the Dieletric Breakdown of Thin Oxide Films. Journal of Physics. C: Solid State Physics. 1986,19:6263～6285
23 L.Reimer. Scanning Electron Microscopy. Springer. 1998:120～134
24 J.Cazaux, P.Lehuede. Some Physical Descriptions of Charging Effects of Insulators under Incident Particle Bombardment. Journal of Electron Spectroscopy and Related Phenomena. 1992,59:49～71.
25 S.Ichmura, H.E.Bauer, H.Seiler, S.Hofmann. Surf. Interface Anal. 1989, 14:250
26 K.Kanaya, N.Ichise, K.Adachi, K .Yonehara, Y.Muranaka. Observation on Charging Effects of Non-conductive and Uncoated Materials by Ion Beam Pre-bombardment in Scanning Electron Microscopy. Micron and Microscopia Acta. 1992,23: 319～325
27 陈文雄, 徐军, 张会珍. 扫描电镜的最新发展-低电压扫描电镜(LVSEM)和扫描低能电镜(SLEEM). 电子显微学报. 2001,20(4):258～262
28 邵曼君. 环境扫描电镜及其应用. 物理. 1998,27（1）:48－52
29 王宝锋, 赵忠扬. 环境扫描电镜及其在石油技术中的应用. 油田化学. 1999,16（3）:278－281
30邵曼君. 环境扫描电镜原位研究纯Fe表面氧化过程. 金属学报. 2000,36（3）:230－234
31 余健业, 谢信能, 刘廷壁, 邵曼君, 黄兰友. 高温环境扫描电镜 (KYKY1500)Ⅰ.成像原理及仪器特点. 电子显微学报. 1997,16(1):57～64
32 邵曼君, 赵万敏, 肖骅昭, 段岳, 余健业, 黄兰友. 高温环境扫描电镜(KYKY1500)Ⅱ.调试与应用. 电子显微学报. 1997,16(1):65～70
33洪健, 徐正. 环境扫描电镜在生物学上的应用. 杭州电子工业学院学报. 2000,20(3):48～52
34 李春艳, 杜海燕, 董向红等. 环境扫描电子显微镜中的电子传输. 电子显微学报. 2001,20(4):287～288
35 段岳, 邵曼君. 绝缘样品在KYKY-1500环境扫描电镜中的直接观察. 化工冶金. 1996,17(1):66～70
35 邵曼君, 段岳, 李惠君, 李竹川. 纯铁、镍氧化晶须生长的动态环境扫描电镜研究. 电子显微学报. 1996, 15(6):540
37 L.Reimer. Electron-Specimen Interaction and Image Formation in LVSEM. Electron Microscopy. 1992,1:9～17
38 H.S.Guo, W.Maus-Friedrichs, V.Kempter. Charging Phenomena and Charge Compensation in AES on Metal Oxide and Silica. Surface and Interface Analysis. 1997, 25:390～396
39 H.S.Guo, W.Maus-Friedrichs, V.Kempter. Charge Trapping and Charge Compensation during AES on SiO2. Journal of Applied Physics. 1999, 86:2337～2341
40 H.S.Guo, W.Maus-Friedrichs, V.Kempter. The Relation between Preexisting Defects and Charging-up in 9mol% Y2O2-ZrO2 Studied by AES. Chinese Physics.2000,9(3):225～232
41 H.S.Guo, W.Maus-Friedrichs, V.Kempter, J.X.Shi. A Study of the Charging Phenomena during Electron Irradiation of Sintered Si3N4. Nuclear Instruments and Methods in Physics Research. 2001,B 173: 463～469
42郭汉生，史佳新. 俄歇电子能谱实验中Al2O3的荷电现象及其消除办法. 2000年材料科学与工程新进展. 冶金工业出版社. 2001:1843－1846
43史佳新, 吉 元, 徐学东, 肖卫强, 张隐奇, 郭汉生. 氧环境扫描电镜对氧化物的荷电补偿.( 北京工业大学学报. 2003, 29(2)，待发表)
44 Y.Ji, H.S.Guo, X.D.Xu, J.X.Shi. A Preliminary Study of Oxygen Environmental SEM: Application on Oxides. (Accepted by Journal of Trace and Microprobe Techniques)