US3833811A - Scanning electron microscope with improved means for focusing - Google Patents

Scanning electron microscope with improved means for focusing Download PDF

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Publication number
US3833811A
US3833811A US00377524A US37752473A US3833811A US 3833811 A US3833811 A US 3833811A US 00377524 A US00377524 A US 00377524A US 37752473 A US37752473 A US 37752473A US 3833811 A US3833811 A US 3833811A
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United States
Prior art keywords
specimen
scanning
electron
electron microscope
improvement
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Expired - Lifetime
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US00377524A
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English (en)
Inventor
H Koike
S Sakurai
K Ueno
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Jeol Ltd
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Jeol Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/02—Details
    • H01J37/04—Arrangements of electrodes and associated parts for generating or controlling the discharge, e.g. electron-optical arrangement, ion-optical arrangement
    • H01J37/153—Electron-optical or ion-optical arrangements for the correction of image defects, e.g. stigmators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/02—Details
    • H01J37/21—Means for adjusting the focus
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/26—Electron or ion microscopes; Electron or ion diffraction tubes
    • H01J37/28—Electron or ion microscopes; Electron or ion diffraction tubes with scanning beams

Definitions

  • ABSTRACT A scanning electron microscope for observing a transmitted electron scanning image of a specimen incorporating a means for detecting electron beams transmitted in more than one direction separately and a means for displaying scanning images corresponding to said detected beams, thus facilitating the focusing adjustment of the condenser lens system incorporated in said scanning electron microscope.
  • This invention relates in general to a scanning electron microscope and in particular to a means for monitoring the focusing condition of the electron beam irradiating the specimen under examination.
  • An advantage of this invention is to facilitate adjustment of the condenser lens excitation current for optimum beam focus. Another advantage of this invention is to facilitate adjustment of the stigmator.
  • FIG. 1 is a schematic diagram showing one embodiment according to the invention.
  • FIG. 2 is a schematic drawing showing the images displayed on the screens of the cathode-ray tubes shown in FIG. 1;
  • FIG. 3 is a schematic drawing showing the electron beam path near a specimen for explaining the invention
  • FIG. 4 is a schematic diagram showing another embodiment according to the invention.
  • FIG. 5 is a schematic drawing showing the image displayed on the screen of the cathode-ray tube shown in FIG. 4;
  • FIGS. 6, 7, 8 and 9 are schematic diagrams showing further embodiments according to the invention.
  • FIG. is a schematic drawing showing the image displayed on the screen of the cathode-ray tube shown in FIG. 9.
  • a thin specimen 1 is arranged in an evacuated column 2 of a scanning electron microscope.
  • the specimen 1 is irradiated by an electron beam EBl generated by an electron gun 3.
  • Excitation current supply sources 4 and 5 control the focal length of condenser lenses 6 and 7 to focus the electron beam EBl on the specimen surface.
  • An excitation current supply source 8 energizes and controls a stigmator 9 in order to correct lens astigmatism.
  • Scanning coils 10X and 10Y scan the electron beam EBl over the desired area of the specimen surface.
  • a signal generator 11 energizes the scanning coils 10X and NY and controls the amount of scan.
  • Beam detectors l2 and 13 detect the electrons transmitted through the specimen 1.
  • the aperture plates 12a and 13a are arranged to pass only the transmitted electrons which pass along the optical axis and at a certain angle a, respectively.
  • the detected electron output signals after being amplified by amplitiers l6 and 17, are applied to the control grids of cathode-ray tubes 14 and 15, respectively.
  • the electronbeams of said CRTs are scanned by scanning coils 14X, 14Y and 15X, 15Y and, since these scanning coils are energized and controlled by the same scanning signal generating source 11 as scanning coils 10X and lOY, the scanning of the signals synchronizes with the scanning of the electron beam EBl.
  • scanning images corresponding to electron beams BB2 and EB3 are displayed on the respective cathode-ray screens 14s and 15s.
  • FIG. 3 shows schematically the electron beam path in the vicinity of the specimen 1 under the condition that the electron beam is improperly focussed by a condenser lens (not shown) on a plane 18 above the specimen.
  • the electrons which pass straight through the specimen along the optical axis 19 are detected by a detector A (not shown) and the electrons which pass through the specimen at angle a, with respect tosaid optical axis are detected by a second detector B (also not shown), said detectors corresponding to detectors 12 and 13 described in FIG. 1.
  • detector A detects the electrons carrying information pertaining to a minute area 20 of the specimen while detector B detects the electrons carrying information pertaining to a second minute area 21 of said specimen.
  • the transmitted beams move to positions as shown by the broken lines with the result that detector B now detects the electrons carrying information pertaining to said area 20.
  • the respective detector brightness modulation output signal is virtually the same.
  • Angle a in this case. is less than 10' rad which is not large enough to separate elastic and inelastic electrons in the'specimen.
  • FIG. 4 shows another embodiment of this invention in which only one cathode-ray tube is used to display the two images.
  • This is made possible by incorporating a switching circuit 23 between the output circuit of amplifiers l6 and. 17 and the control grid of the single cathode-ray tube 22, said switching circuit being synchronized with the scanning signal generator 11.
  • a switching circuit 23 between the output circuit of amplifiers l6 and. 17 and the control grid of the single cathode-ray tube 22, said switching circuit being synchronized with the scanning signal generator 11.
  • FIG. 6 shows a variation of the embodiment described in FIG. 4.
  • the means differ, however.
  • a mechanical vibrating means 24 is incorporated in conjunction with an aperture plate 25.
  • the two detectors 26 and 27 are arranged symmetrically with respect to the microscope optical axis.
  • FIG. 7 achieves the same object as the embodiment described in FIG. 6 using one wide window detector 28 instead of two smaller detectors, and an aperture plate 27 with single aperture 270 instead of two apertures.
  • FIG. 9 schematically illustrates the essential part of an embodiment designed to facilitate adjustment of the stigmator lens as the focusing lenses.
  • a plurality of detectors and apertures in this case six detectors 32, 33, 34, 35, 36 and 37 and six apertures 32a, 33a, 34a, 35a, 36a and 37a are symmetrically arranged about the optical axis 19 below the specimen 1.
  • the output signals of the respective detectors after being amplified by amplifiers 32c, 33c, 34c, 35c, 36c and 37c are applied to a switching circuit 38, the output of which is applied to the brightness control grid of the cathode-ray tube 22.
  • the switching circuit 43 is synchronized with the scanning signal generator 11. i
  • D D and D are equal as shown in FIG. 10. Further, if the condenser iens system is also correctly adjusted, D D and D are equal and zero.
  • FIG. 8 A further alternative on the embodiment shown in FIG. 7 is shown in FIG. 8.
  • a deflecting coil 30 energized by a deflecting current source 31 synchronized with the scanning signal generator 11 replaces the previously described switching and vibrating means, etc.
  • the intensity of the output current of the deflecting current source 31 in two or more steps in turn, the transmitted electron beams having different angles with respect to the optical axis are passed through the aperture 12a and detected by the detector 12. Accordingly, either a stationary or vibrating image will appear on the cathode-ray tube 22 according to whether or not the condenser lens system is correctly or incorrectly adjusted.
  • a scanning electron microscope incorporating an electron gun for generating an electron beam, an electron lens system for focusing the said beam on the surface of a thin specimen, a scanning means for scanning the beam over the specimen surface, the improvement comprising a detecting means for separately detecting the electrons transmitted through the specimen in different substantially discrete directions and a display means for simultaneously displaying the scanning images corresponding to the output signals of said detecting means, said display means enabling the observation of the positional difference of the said detectors when the electron beam is out of focus whereby the focus can be corrected by observing said display means.
  • said detecting means comprises two or more electron detectors arranged below the specimen such that the respective detectors detect the electrons transmitted through the specimen in different directions.
  • said detecting means comprises one electron detector arranged below the specimen, an aperture plate arranged above said detectors below the specimen and a means for vibrating said aperture plate.
  • said detecting means comprises two or more electron detectors arranged below the specimen, an aperture plate arranged over said two or more detectors below the specimen and a means for vibrating said aperture plate.
  • said detecting means comprises one electron detector arranged below the specimen and a deflecting means for alternatively deflecting the electron beam so as to vary the direction of the transmitted electron beam detected by said detector.
  • said display means comprises two or more cathode-ray tubes for displaying images corresponding to the respective directions of the transmitted electron beams.

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  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Analysing Materials By The Use Of Radiation (AREA)
  • Electron Sources, Ion Sources (AREA)
US00377524A 1972-07-11 1973-07-09 Scanning electron microscope with improved means for focusing Expired - Lifetime US3833811A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP47069360A JPS521869B2 (xx) 1972-07-11 1972-07-11

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US3833811A true US3833811A (en) 1974-09-03

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US00377524A Expired - Lifetime US3833811A (en) 1972-07-11 1973-07-09 Scanning electron microscope with improved means for focusing

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US (1) US3833811A (xx)
JP (1) JPS521869B2 (xx)
DE (1) DE2335304B2 (xx)
FR (1) FR2192374B1 (xx)
GB (1) GB1442177A (xx)

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3914606A (en) * 1973-03-12 1975-10-21 Jeol Ltd Electron detector
US3917946A (en) * 1972-04-12 1975-11-04 Philips Corp Electron-optical device for the recording of selected diffraction patterns
US4097740A (en) * 1975-09-19 1978-06-27 Siemens Aktiengesellschaft Method and apparatus for focusing the objective lens of a scanning transmission-type corpuscular-beam microscope
US4379230A (en) * 1979-09-05 1983-04-05 U.S. Philips Corporation Automatic beam correction in a scanning transmission electron microscope
US4698503A (en) * 1985-01-23 1987-10-06 Hitachi, Ltd. Focusing apparatus used in a transmission electron microscope
US4737640A (en) * 1985-04-10 1988-04-12 Hitachi, Ltd. Electron microscope
US4788425A (en) * 1986-10-08 1988-11-29 Hitachi, Ltd. Optical axis adjusting apparatus for electron microscope
US4975578A (en) * 1989-04-17 1990-12-04 The Research Foundation Of State University Of Ny Method and apparatus for determining distribution of mass density
US5393977A (en) * 1992-06-03 1995-02-28 Hitachi, Ltd. Charged particle beam apparatus and it's operating method
US5650621A (en) * 1993-06-21 1997-07-22 Hitachi, Ltd. Electron microscope
US20080048117A1 (en) * 2006-08-22 2008-02-28 Hitachi High-Technologies Corporation Scanning Electron Microscope
US20080099677A1 (en) * 2006-10-30 2008-05-01 Hitachi, Ltd. Method for measuring information transfer limit in transmission electron microscope, and transmission electron microscope using the same
CN102169790A (zh) * 2011-03-29 2011-08-31 北京航空航天大学 电子显微镜的第一聚光镜
CN102184828A (zh) * 2011-03-29 2011-09-14 北京航空航天大学 电子显微镜的第二聚光镜
US20170125209A1 (en) * 2015-11-02 2017-05-04 Fei Company Charged particle microscope with vibration detection / correction

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL7804039A (nl) * 1978-04-17 1979-10-19 Philips Nv Elektronenmikroskoop met stigmator.
JPS5613649A (en) * 1979-07-12 1981-02-10 Akashi Seisakusho Co Ltd Correcting method and device for astigmatism in scanning type electron microscope and the like
NL8304217A (nl) * 1983-12-07 1985-07-01 Philips Nv Automatisch instelbare electronenmicroscoop.
SE446954B (sv) * 1985-03-12 1986-10-20 Uponor Ab Sett vid extrudering av ett dubbelveggigt plastror samt extruderingsverktyg for utovning av settet
DE3720560C1 (de) * 1987-06-22 1988-09-15 Bekum Maschf Gmbh Coextrusionskopf

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2627589A (en) * 1950-10-30 1953-02-03 Rca Corp Focusing of electron optical apparatus
US3180986A (en) * 1961-08-17 1965-04-27 Engineering Lab Measuring systems for electron diffraction patterns
US3225192A (en) * 1962-12-28 1965-12-21 Hitachi Ltd Apparatus for producing electron microscope and diffraction images separately and simultaneously on the image plane
US3502870A (en) * 1967-07-05 1970-03-24 Hitachi Ltd Apparatus for simultaneously displaying a plurality of images of an object being analyzed in an electron beam device
US3576438A (en) * 1969-04-28 1971-04-27 Bell Telephone Labor Inc Focus monitor for electron microscope including an auxiliary electron gun and focusing lens
US3626184A (en) * 1970-03-05 1971-12-07 Atomic Energy Commission Detector system for a scanning electron microscope

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1058037A (en) * 1964-11-03 1967-02-08 Jeol Ltd Electron beam apparatus

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2627589A (en) * 1950-10-30 1953-02-03 Rca Corp Focusing of electron optical apparatus
US3180986A (en) * 1961-08-17 1965-04-27 Engineering Lab Measuring systems for electron diffraction patterns
US3225192A (en) * 1962-12-28 1965-12-21 Hitachi Ltd Apparatus for producing electron microscope and diffraction images separately and simultaneously on the image plane
US3502870A (en) * 1967-07-05 1970-03-24 Hitachi Ltd Apparatus for simultaneously displaying a plurality of images of an object being analyzed in an electron beam device
US3576438A (en) * 1969-04-28 1971-04-27 Bell Telephone Labor Inc Focus monitor for electron microscope including an auxiliary electron gun and focusing lens
US3626184A (en) * 1970-03-05 1971-12-07 Atomic Energy Commission Detector system for a scanning electron microscope

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3917946A (en) * 1972-04-12 1975-11-04 Philips Corp Electron-optical device for the recording of selected diffraction patterns
US3914606A (en) * 1973-03-12 1975-10-21 Jeol Ltd Electron detector
US4097740A (en) * 1975-09-19 1978-06-27 Siemens Aktiengesellschaft Method and apparatus for focusing the objective lens of a scanning transmission-type corpuscular-beam microscope
US4379230A (en) * 1979-09-05 1983-04-05 U.S. Philips Corporation Automatic beam correction in a scanning transmission electron microscope
US4698503A (en) * 1985-01-23 1987-10-06 Hitachi, Ltd. Focusing apparatus used in a transmission electron microscope
US4737640A (en) * 1985-04-10 1988-04-12 Hitachi, Ltd. Electron microscope
US4788425A (en) * 1986-10-08 1988-11-29 Hitachi, Ltd. Optical axis adjusting apparatus for electron microscope
US4975578A (en) * 1989-04-17 1990-12-04 The Research Foundation Of State University Of Ny Method and apparatus for determining distribution of mass density
US5393977A (en) * 1992-06-03 1995-02-28 Hitachi, Ltd. Charged particle beam apparatus and it's operating method
US5650621A (en) * 1993-06-21 1997-07-22 Hitachi, Ltd. Electron microscope
US20080048117A1 (en) * 2006-08-22 2008-02-28 Hitachi High-Technologies Corporation Scanning Electron Microscope
US7772553B2 (en) * 2006-08-22 2010-08-10 Hitachi High-Technologies Corporation Scanning electron microscope
US20080099677A1 (en) * 2006-10-30 2008-05-01 Hitachi, Ltd. Method for measuring information transfer limit in transmission electron microscope, and transmission electron microscope using the same
US7732766B2 (en) * 2006-10-30 2010-06-08 Hitachi, Ltd. Method for measuring information transfer limit in transmission electron microscope, and transmission electron microscope using the same
CN102169790A (zh) * 2011-03-29 2011-08-31 北京航空航天大学 电子显微镜的第一聚光镜
CN102184828A (zh) * 2011-03-29 2011-09-14 北京航空航天大学 电子显微镜的第二聚光镜
CN102169790B (zh) * 2011-03-29 2012-07-04 北京航空航天大学 电子显微镜的第一聚光镜
CN102184828B (zh) * 2011-03-29 2013-02-06 北京航空航天大学 电子显微镜的第二聚光镜
US20170125209A1 (en) * 2015-11-02 2017-05-04 Fei Company Charged particle microscope with vibration detection / correction
US9875879B2 (en) * 2015-11-02 2018-01-23 Fei Company Charged particle microscope with vibration detection / correction

Also Published As

Publication number Publication date
FR2192374B1 (xx) 1977-05-13
JPS521869B2 (xx) 1977-01-18
GB1442177A (en) 1976-07-07
DE2335304B2 (de) 1975-07-10
JPS4928267A (xx) 1974-03-13
DE2335304A1 (de) 1974-01-31
FR2192374A1 (xx) 1974-02-08

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