US3849647A - Scanning electron microscope - Google Patents

Scanning electron microscope Download PDF

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Publication number
US3849647A
US3849647A US00327615A US32761573A US3849647A US 3849647 A US3849647 A US 3849647A US 00327615 A US00327615 A US 00327615A US 32761573 A US32761573 A US 32761573A US 3849647 A US3849647 A US 3849647A
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United States
Prior art keywords
lens
optical axis
electron beam
specimen
electron
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Expired - Lifetime
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US00327615A
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English (en)
Inventor
H Koike
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 or ion-optical arrangement
    • H01J37/10—Lenses
    • H01J37/14—Lenses magnetic
    • H01J37/141—Electromagnetic lenses
    • 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

  • microscopes of this type heretofore described, are incapable of permitting the observation of specimen variation with the passage of time; e.g., phase transformation changes in crystalline structure or the growth of the crystalline formation by heating or cooling the specimen.
  • microscopes of this type related to in the prior art are restricted in application.
  • An advantage of this invention is to remove this restriction by providing a scanning transmission electron microscope capable of displaying a scanning image produced by the transmitted electrons and its corresponding diffraction pattern simultaneously.
  • FIG. 1 is a schematic drawing of a scanning electron microscope according to this invention
  • FIG. 2 is a detailed schematic drawing showing the structural arrangement of the objective lens forming part of the lens system of the microscope shown in FIG.
  • FIG. 3 is a diagrammatic representation showing the beam path and magnetic field produced by the objective lens shown in FIG. 2;
  • FIG. 4 is a schematic diagram showing the electron beam path in the microscope described in FIG. 1;
  • FIG. 5 is a schematic diagram showing the electron optical system of another embodiment of this invention.
  • FIG. 6 is a schematic drawing showing another structural arrangement of the objective lens shown in FIG.
  • FIG. 7 is a schematic drawing showing still another structural arrangement of the objective lens shown in FIG. 2;
  • FIG. 8 is a schematic diagram showing an embodiment for displaying the diffraction pattern on a cahoderay tube.
  • FIG. 9 is a schematic diagram showing another embodiment for displaying the diffraction pattern on a cathode-ray tube.
  • an electron gun I generates an electron beam which is condensed and focused by condenser lenses 2 and 3 and an objective lens, 4 so as to irradiate a crystalline specimen held by the holder 5 which is supported by a specimen stage 5a with very small diameter electron beam.
  • the beam is made to scan over the specimen in a two-dimensional raster by means of deflecting coils 6 and their scanning current supply 7 and the objective lens 4.
  • the electron beam transmitted through and diffracted by the specimen is formed into a diffraction pattern on a fluorescent screen 8 by means of the magnetic field of the objective lens 4, said pattern being observed through a window 9 of an observation chamber 10.
  • the transmitted electrons which reach the center of the fluorescent screen 8 pass through a small aperture 11 and are detected by an electron detector 12.
  • the output signal from the detector 12 is supplied to the brightness control grid of a cathode-ray tube 13 via an amplifier 14. Since deflecting coils 15 forming part of the cathode-ray tube 13 are supplied with deflecting current from the same current supply source 7 as the deflecting coil 6, a conventional scanning microscope image can be displayed on the screen of the cathoderay tube 13.
  • Deflecting coils 16 attached to the upper part of the observation chamber 10 and their current supply 17' is utilized to deflect the electron beam so that the desired diffraction pattern spot passes through the aperture 11.
  • a means for moving the detector 12 and its aperture 11 mechanically may be used instead of deflecting coil 16 and its current supply 17.
  • FIG. 2 shows the structure of the objective lens 4 in detail.
  • the lens consists of an exciting coil 18, a yoke 19 and pole pieces 20 and 21 and a non-magnetic spacer 22.
  • the pole pieces 20 and 21 constitute a magnetic flux gap by means of the spacer 22.
  • a crystalline specimen 23 is located between the pole pieces 20 and 21 and the deflecting coil 6 for scanning the electron beam over the specimen is attached to the upper part of the pole piece 20.
  • the strength of the magnetic field along the optical axis is indicated by the distance of the line 24 from the axis in FIG. 3.
  • the electron beam path 25 in the above pole pieces are indicated in FIG. 3 in an exaggerated manner.
  • the magnetic field 24 is so strong in the area below the specimen that the center beam of the electrons transmitted through the specimen crosses the optical axis 26 at least twice; i.e., at points A and B shown in FIG. 3.
  • FIG. 4 is a schematic diagram showing the electron beam path in the microscope described in FIG. 1.
  • apparent lenses 4a, 4b and 4c are produced by the strong magnetic field 24 of the objective lens 4 as shown in FIG. 3.
  • the electron beam generated by the electron gun is condensed by the apparent lens 4a in addition to being condensed by condenser lenses 2 (not shown in FIG. 4) and 3 so as to minimize the crosssectional diameter of the electron on the specimen.
  • the beam is then deflected by deflecting coil 6 and the apparent lens 4a. Since the said deflecting coil 6 is located at the front focal point of the apparent lens 4a, the electron beam irradiates the specimen perpendicularly.
  • the electron beams 25b, 25c are diffracted by the specimen 23 while the center beam 25a remains undiffracted. These beams form a diffraction pattern at positions 27 and 28; i.e., at the positions where the center beam crosses the optical axis 26. In this case, if the crystalline structure is the same regardless of the scanning position the diffraction pattern formed on the screen 8 will remain stationary whenever the electron beam scans the specimen.
  • FIG. 5 is a schematic diagram showing the electron optical system of another embodiment of this invention.
  • two pairs of coils 6a and 6b are located above the front focal point of the apparent lens 4a so as to deflect the electron beam twice, thereby varying the angle at which the electron beam crosses the optical axis 26 at said front focal point of the apparent lens 4a. In this way, the beam approaches the specimens perpendicular to the surface thereof.
  • FIG. 6 is a schematic drawing showing another structural arrangement of the objective lens shown in FIG. 2.
  • an additional magnetic pole piece 29 is inserted between pole pieces and 21, resulting in a single magnetic flux path with two magnetic flux gaps. Since the crystalline specimen 23 is placed in the pole piece 29, the upper magnetic flux gap acts in the same way as the apparent lens 4a in FIG. 4 and the lower magnetic flux gap acts in the same way as the apparent lens 4b or the apparent lenses 4b and 4c in combination.
  • FIG. 7 is a schematic diagram showing still another structural arrangement of the objective lens shown in FIG. 2.
  • an exciting lens coil 30, yoke 31, magnetic pole pieces 32 and 33, including spacer 34 have been added to the original structure.
  • the magnetic field at the lower gap acts as an extra lens and the diffraction pattern is further enlarged.
  • the center of the electron beam transmitted through the specimen crosses the optical axis more than twice and the diffraction pattern can be formed at any of the planes where the electron beam crosses the optical axis.
  • the magnetic field strength in the upper gap is insufiicient, the magnetic field at the upper gap acts as the apparent lenses 4a and 4b and the magnetic field at the lower gap acts as the apparent lens 40.
  • FIG. 8 is a schematic diagram showing an embodiment for displaying the diffraction pattern on a cathode-ray tube.
  • a small electron detector 35 for example, a semiconductor detector, is located at the center of the plane 28 where the diffraction pattern is formed, so as to produce a signal for the scanning microscope image.
  • a second electron detector 36 complete with aperture 37, is arranged below the electron detector 35.
  • deflecting coils 38 for scanning the entire diffraction pattern over the aperture 37 are located between said detectors 35 and 36.
  • the signal produced by the detector 36 is supplied to the brightness control grid of a cathode-ray tube 39 via an amplifier 40.
  • the scanning current supply 41 is common to both deflecting coils 38 and deflecting coils 42 of the cathode-ray tube 39, the diffraction pattern is displayed on the cathode-ray tube 39.
  • FIG. 9 is a schematic diagram showing another embodiment for displaying the diffraction pattern on a cathode-ray tube in which an image pick-up tube 43 is used instead of the detector 36.
  • deflecting coils 38 are dispensed with the deflector coils 44 incorporated in the image pick-up tube being used in lieu.
  • the diffraction pattern formed on the plane 28 is displayed on the cathode-ray tube 39.
  • a scanning transmission electron microscope and electron diffraction device having a lens and deflection system defining an electron optical axis and comprising means for generating an electron beam directed along the optical axis, means for condensing said electron beam, an objective lens comprising a magnetic flux creating coil and associated pole pieces for creating a magnetic lens in the gap between the pole pieces, means for positioning a transmission specimen along the optical axis in the specimen plane within the gap between the pole pieces of the objective lens, the intensity of the magnetic flux in said gap being sufficient to form a first apparent lens just before the specimen plane and a second apparent lens thereafter, said objective lens system causing the electron beam to cross the electron optical axis at least twice after passing through the specimen plane, means comprising at least one deflection stage for deflecting the electron beam through a point on the front focal plane of the first apparent lens such that the beam scans the specimen substantially perpendicular thereto, a detecting means for detecting the transmitted electron beam, said detecting means being placed on any plane perpendicular to the optical axis where the
  • said display means for displaying the diffraction pattern consists of an electron detector and a deflecting means for scanning the diffraction pattern over said detector and a display tube for displaying the signal of said detector, said display tube being synchronized with said deflecting means.
  • a scanning transmission electron microscope having a lens and a deflection system defining an electron optical axis comprising means for generating an electron beam directed along the optical axis, means for condensing said electron beam, an objective lens consisting of a magnetic flux creating coil and associated pole pieces for creating a magnetic lens in the gap between the pole pieces, means for positioning a transmission specimen along the optical axis in a specimen plane within the gap between the pole pieces of the objective lens, the intensity of the magnetic flux in said gap being sufficient to form a first apparent lens before the specimen plane and a second apparent lens thereafter, said objective lens system causing the electron beam to cross the electron optical axis at least twice after passing through the specimen plane, means comprising at least one deflection stage for deflecting the described in claim 5 wherein said lens system consists of a single magnetic flux path.

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  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Analysing Materials By The Use Of Radiation (AREA)
US00327615A 1972-10-23 1973-01-22 Scanning electron microscope Expired - Lifetime US3849647A (en)

Applications Claiming Priority (1)

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JP47105931A JPS5138578B2 (enrdf_load_stackoverflow) 1972-10-23 1972-10-23

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US00327615A Expired - Lifetime US3849647A (en) 1972-10-23 1973-01-22 Scanning electron microscope

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US (1) US3849647A (enrdf_load_stackoverflow)
JP (1) JPS5138578B2 (enrdf_load_stackoverflow)
DE (1) DE2302689A1 (enrdf_load_stackoverflow)
GB (1) GB1422398A (enrdf_load_stackoverflow)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2371061A1 (fr) * 1976-11-12 1978-06-09 Siemens Ag Procede pour representer l'image de diffraction dans un microscope a balayage a transmission, a faisceau corpusculaire
US4427886A (en) 1982-08-02 1984-01-24 Wisconsin Alumni Research Foundation Low voltage field emission electron gun
US5457317A (en) * 1992-09-17 1995-10-10 Hitachi, Ltd. Electron microscope, a camera for such an electron microscope, and a method of operating such an electron microscope
WO2005022582A1 (en) * 2003-09-02 2005-03-10 Nanomegas Sprl A method for measuring diffraction patterns from a transmission electron microscopy to determine crystal structures and a device therefor
US20150144789A1 (en) * 2011-09-12 2015-05-28 Mapper Lithography Ip B.V. Vacuum chamber with base plate
US20150214004A1 (en) * 2014-01-24 2015-07-30 Carl Zeiss Microscopy Gmbh Method for preparing and analyzing an object as well as particle beam device for performing the method

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL175245C (nl) * 1977-05-26 1984-10-01 Philips Nv Elektronenmicroscoop met hulplens en elektromagnetische lens hiervoor.
JPS6080655U (ja) * 1983-11-08 1985-06-04 日本電子株式会社 電子顕微鏡のシヤツタ−装置

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2438971A (en) * 1946-10-31 1948-04-06 Rca Corp Compound electron objective lens
US3090864A (en) * 1960-06-18 1963-05-21 Kabushikikaisha Nihondenshi Ko Electron microscope
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
US3370168A (en) * 1964-01-14 1968-02-20 Hitachi Ltd Anode aperture plate for a television camera tube in an electron microscope comprising a stainless steel foil
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
US3508049A (en) * 1967-02-27 1970-04-21 Max Planck Gesellschaft Corpuscular-ray microscope with an objective lens which also forms a condenser-lens field
US3560739A (en) * 1968-03-26 1971-02-02 Otto Wolff Particle beam apparatus for selectively forming an image of a specimen or its diffraction diagram
US3660657A (en) * 1968-11-26 1972-05-02 Ass Elect Ind Electron microscope with multi-focusing electron lens

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2438971A (en) * 1946-10-31 1948-04-06 Rca Corp Compound electron objective lens
US3090864A (en) * 1960-06-18 1963-05-21 Kabushikikaisha Nihondenshi Ko Electron microscope
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
US3370168A (en) * 1964-01-14 1968-02-20 Hitachi Ltd Anode aperture plate for a television camera tube in an electron microscope comprising a stainless steel foil
US3508049A (en) * 1967-02-27 1970-04-21 Max Planck Gesellschaft Corpuscular-ray microscope with an objective lens which also forms a condenser-lens field
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
US3560739A (en) * 1968-03-26 1971-02-02 Otto Wolff Particle beam apparatus for selectively forming an image of a specimen or its diffraction diagram
US3660657A (en) * 1968-11-26 1972-05-02 Ass Elect Ind Electron microscope with multi-focusing electron lens

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
The Arizona 1McV Transmission Scanning Electron Microscope, Strojnik, Proceedings of 5th Annual SEM Symp., part 1, April, 1972. *

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2371061A1 (fr) * 1976-11-12 1978-06-09 Siemens Ag Procede pour representer l'image de diffraction dans un microscope a balayage a transmission, a faisceau corpusculaire
US4160162A (en) * 1976-11-12 1979-07-03 Siemens Aktiengesellschaft Method for the pictorial display of a diffraction image in a transmission-type, scanning, corpuscular-beam microscope
US4427886A (en) 1982-08-02 1984-01-24 Wisconsin Alumni Research Foundation Low voltage field emission electron gun
US5457317A (en) * 1992-09-17 1995-10-10 Hitachi, Ltd. Electron microscope, a camera for such an electron microscope, and a method of operating such an electron microscope
WO2005022582A1 (en) * 2003-09-02 2005-03-10 Nanomegas Sprl A method for measuring diffraction patterns from a transmission electron microscopy to determine crystal structures and a device therefor
US20070023659A1 (en) * 2003-09-02 2007-02-01 Sergeevich Avilov A Method for measuring diffraction patterns from a transmission electron microscopy to determine crystal structures and a device therefor
US7601956B2 (en) 2003-09-02 2009-10-13 Avilov Anatoly Sergeevich Method for measuring diffraction patterns from a transmission electron microscopy to determine crystal structures and a device therefor
US20150144789A1 (en) * 2011-09-12 2015-05-28 Mapper Lithography Ip B.V. Vacuum chamber with base plate
US9939728B2 (en) * 2011-09-12 2018-04-10 Mapper Lithography Ip B.V. Vacuum chamber with a thick aluminum base plate
US20150214004A1 (en) * 2014-01-24 2015-07-30 Carl Zeiss Microscopy Gmbh Method for preparing and analyzing an object as well as particle beam device for performing the method

Also Published As

Publication number Publication date
JPS4964365A (enrdf_load_stackoverflow) 1974-06-21
DE2302689A1 (de) 1974-05-09
GB1422398A (en) 1976-01-28
DE2302689B2 (enrdf_load_stackoverflow) 1979-02-08
JPS5138578B2 (enrdf_load_stackoverflow) 1976-10-22

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