US3569698A - Particle-beam apparatus provided with a phase-shifting foil which corrects for wave aberrations - Google Patents

Particle-beam apparatus provided with a phase-shifting foil which corrects for wave aberrations Download PDF

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Publication number
US3569698A
US3569698A US834316A US3569698DA US3569698A US 3569698 A US3569698 A US 3569698A US 834316 A US834316 A US 834316A US 3569698D A US3569698D A US 3569698DA US 3569698 A US3569698 A US 3569698A
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United States
Prior art keywords
foil
particle
beams
phase
axis
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Expired - Lifetime
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US834316A
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English (en)
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Karl-Heinz Herrman
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Siemens AG
Siemens Corp
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Siemens Corp
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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
    • H01J37/153—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
    • H01J37/26—Electron or ion microscopes; Electron or ion diffraction tubes
    • H01J37/261—Details
    • H01J37/263—Contrast, resolution or power of penetration
    • 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
    • H01J37/266—Measurement of magnetic or electric fields in the object; Lorentzmicroscopy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
    • H01J2237/153—Correcting image defects, e.g. stigmators
    • H01J2237/1534—Aberrations
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
    • H01J2237/26—Electron or ion microscopes
    • H01J2237/2614—Holography or phase contrast, phase related imaging in general, e.g. phase plates

Definitions

  • a particle-beam apparatus has a beam axis and a [54] PARTICLE-BEAM APPARATUS PROVIDED WITH A PHASE-SHIFTING FOIL WHICH CORRECTS 3,213,277 10/1965 Hoppe beam generator for issuing particle beams along the axis including a primary beam coincident with the axis.
  • An electronoptical lens for focusing an image on an image plane causes wave aberrations that shift the respective phases of the particle beams.
  • a foil is disposed in the path of the beams and shifts the phases of the beams with respect to the phase of the primary beam in dependence upon their respective radial distances from the axis so that the phases are shifted to correct for the shift caused by the wave aberrations.
  • the foil has concentric discontinuities in its thickness at which the phase-shifting effect of the foil decreases in steplike fashion in radial distance, by values which correspond to whole number multiples of the wavelength of the particle beam, each adjacent pair of the discontinuities enclosing an annular foil portion having a thickness which increases continuously in radial direction.
  • My invention relates to particle beam apparatus of the type used for studying a specimen. for example. an electron microscope.
  • One such microscope is described with regard to construction and operation in an article which I coauthored. namely ELMISKOP lOl a new High-Power Electron Microscope, Siemens Review, Vol. 36, No. 2, Feb. 1969, pages 57 to 67.
  • a beam generator issues beams along a beam axis, the beams being diffracted in the specimen.
  • the beam axis extends through an objective lens and through a phase-correcting foil having a phase-shifting characteristic that varies as a function of the radial distance from the beam axis.
  • the objective lens causes wave aberrations which are responsible for undesirable shifts in the respective phases of the beams with respect to the phase of a primary beam coincident with the beam axis.
  • the foil corrects for the path-dependent phase-shift of the diffracted beams that is due to the aberration of the objective lens, to give all diffracted beams an overall phase-shift of a predetermined value, and so provide the phase condition for achieving a sharp contrast in an image plane.
  • the foil is arranged in the rear focal plane of the objective lens. Wave aberration and its influence on diffracted beams is also considered in the copending U.S. application of Karl Josef Hanssen, entitled: Corpuscular Ray Device for Phase or Amplitude Specimen with a Phase-Rotating Foil, Ser. No. 595,793, filed NOW/'21, 1966 which is now Pat. No. 3,469,096.
  • equation (2 is replaced by the following relationship:
  • Equation (2 is replaced by:
  • W F is the wave aberration of the foil
  • W L is the wave aberration of the lens in accordance with equation (6 and W is the necessary total aberration through the projection system.
  • FIG. 1 is a plot of wave aberration W (r against radial distance r of thediffracted beam from the primary beam.
  • the invention consists in a particle beam apparatus of the type used for studying the phase or amplitude characteristics of specimen, in which a beam generator issues beams along a beam axis including a primary beam coincident with the beam axis, the beams being diffracted in the specimen.
  • the axis of the beam extends through an electron-optical lens and through a phase-correcting foil having a phase-shifting characteristic that varies as a function the radial distance from the beam axis in such a manner that the path-dependent phaseshift of the diffracted beams due to the aberration of the lens is corrected to give all diffracted beams an overall phase-shift of a predetermined value with respect to the phase of the primary beam and so provide the phase condition for obtaining a good contrast image in the image plane.
  • the foil is provided with concentric discontinuities in its thickness at which the phase-shifting effect of the foil decreases in steplike fashion in the radial direction, by values which correspond to whole number multiples of the wavelength of the particle beam, and wherein each neighboring pair of discontinuities encloses an annular foil-portion whose thickness increases continuously in the radial direction.
  • the electron-optical lens may be the objective lens, in which case the correcting foil is adapted to shift the phase of diffracted beams to satisfy the phase-conditions for a contrastrich projection in the image plane.
  • the periodic nature of the phase-shifting corrections necessary in accordance with the equations (2 to in conjunction with (7 by whole number multiples of the corpuscular beam wavelength, enables the maximum required thickness of a phase-correcting foil for compensating the wave aberration of a given lens to be considerably reduced.
  • it has proved particularly expedient if each of the discontinuities lies at a radial distance from the axis of the primary beam, at which the minimum thickness of the annular foil portion surrounding that discontinuity has a thickness corresponding to the minimum thickness of the foil portion immediately surrounded by that discontinuity.
  • FIG. 1 is a plot of wave aberration W (r) against radial distance r of the diffracted beam from the primary beam;
  • FIG. 2 is a graphical representation of the curve a of FIG. 1 on an enlarged scale, indicating how the required steplik discontinuities can be derived;
  • FIG. 3 is a radial cross section of a foil according to the invention which corresponds to the representation of FIG. 2.
  • FIG. 4 is a broken-out view of a microscope column in which is illustrated, in section, an imaging lens provided with an associated phase-shifting foil according to the invention.
  • a given lens excitation i.e. a certain defocusing z
  • equation (2) to (5) give a technically possible inner annular portion thickness of the foil, for n o.
  • the curve a in FIG. 1 is particularly favorable, since it possesses a producible thickness d,,, (see FIG. 2). If the foil thickness then varies with radial distance in a regular manner, the cross section indicated by shading in FIG. 1 would be required, laying between the curve a and the broken line at k /4. with increasing distance r, the foil thickness would then increase very rapidly. For this reason, a discontinuity in the foil thickness is provided at those curve positions whose ordinate value differ from the broken line in each case by a value n).
  • each discontinuity in the foil thickness being at a value which corresponds to a phase-shift by k
  • FIG. 3 the thickness d is plotted against the distance r from the axis of the primary beam.
  • the innermost annular portion of the foil which surrounds an aperture 2 through which the primary beam can pass, has a minimum at l, and then increases with increasing distance r.
  • the second annular portion 3 surrounding the innermost portion commences with a minimum thickness equal to that of the innermost portion, and increases to a thickness equal to the maximum thickness of the innermost portion, and actually corresponds to the section of curve a between (3/4k +d,,,) and (7/4). d,,,).
  • the thickness of the foil, and also the difference in thickness of the various areas are limited.
  • the distribution of particles in the phase-correcting foil can be kept so low that they have no significant adverse influence upon the contrast in the image.
  • FIG. 4 a region of an objective lens of an electronmicroscope is shown.
  • the microscope column 1 of the microscope is partly broken out in order to show the specimen stage and the objective lens.
  • the objective lens comprises the lens winding 2 which develops a magnetic flux that closes over the iron core 3 and the lens gap 4.
  • the phase-shifting foil 7 is held in the lens gap between the pole shoes 5 and 6 of the objective lens by a holding rod 8, which is connected to an operating knob 9 disposed outside the microscope. This permits the phase-shifting foil 7 to be centered during the operation of the microscope without breaking the vacuum.
  • the specimen is situated at the lower end of the specimen cartridge 10 which is inserted into a specimen-shifting table 11.
  • the invention can be employed in any particle beam instrument in which certain phase conditions must be fulfilled for the contrast-rich reproduction of specimen or object structures.
  • the correction obtained can be applied for compensating the aperture error of any lens, and is not limited to use with an objective lens,
  • a correcting foil can be allotted to any lens along the beam path, for example, to a fine beam lens in a raster scan microscope, in whose image plane the object lies.
  • the object for this lens is, as is known, the crossover in front of the cathode.
  • the required foil shape can be manufactured by introducing a thin particle-beam-permeable foil into a hydrocarbon atmosphere, where itis irradiated in areawise fashion by means of an electron-beam, with intensities and/or times selected so as to grow a carbon layer whose distribution over the foil cross section gives the desired variations in the phase-shifting effect across the foil.
  • a carbon layer having any distribution, preferably constant, can be applied to the foil surface and .the coated foil introduced into an oxygen atmosphere where it is irradiated in areawise fashion by means of an electron-beam, with intensities and/0r times selected such that decomposition of the carbon layer produces the required distribution over the foil surface.
  • a particle-beam apparatus having a beam axis comprising beam generating means for issuing particle beams along said axis including a primary beam coincident with said axis, parti cle-beam-optical lens situated about said axis for focusing an image in an image plane, said lens causing wave aberrations that shift the respective phases of said particle beams, and foil means disposed in the path of said beams for shifting said phases of said beams with respect to the phase of said primary beam in dependence upon their respective radial distances from said axis so that said phases are shifted to correct for said shift caused by said wave aberrations, said foil means having concentric discontinuities in its thickness at which the phaseshifting effect of the foil decreases in steplike fashion in a radial direction, by values which correspond to whole number multiples of the wavelength of the particle beam, each adjacent pair of said discontinuities enclosing an annular foil portion having a thickness which increases continuously in radial direction.
  • a particle-beam apparatus comprising means for accommodating a specimen before said foil means in the path of said beams, the latter being defracted by the specimen, said particle-beambptical lens being an objective lens, and said foil means being a foil disposed in said lens and shifting the phase of said defracted beams so that said image is focused in said image plane with sharp contrast.
  • a particle-beam apparatus comprising means for accommodating a specimen before said foil means in the path of said beams, said particlebeam-optical lens being a high resolution lens disposed so that its image plane is coincident with the specimen locality, said foil means being a foil disposed in said lens.

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  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Electron Sources, Ion Sources (AREA)
  • Lenses (AREA)
US834316A 1968-06-28 1969-06-18 Particle-beam apparatus provided with a phase-shifting foil which corrects for wave aberrations Expired - Lifetime US3569698A (en)

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DE (1) DE1807277A1 (enrdf_load_stackoverflow)
GB (1) GB1203705A (enrdf_load_stackoverflow)
NL (1) NL6900965A (enrdf_load_stackoverflow)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3857034A (en) * 1970-08-31 1974-12-24 Max Planck Gesellschaft Scanning charged beam particle beam microscope
US3869611A (en) * 1969-09-19 1975-03-04 Siemens Ag Particle-beam device of the raster type
USRE29500E (en) * 1970-08-31 1977-12-20 Max-Planck-Gesellschaft Zur Forderung Der Wissenschaften E.V. Scanning charged beam particle beam microscope
US20020148962A1 (en) * 2001-02-09 2002-10-17 Jeol Ltd. Lens system for phase plate for transmission electron microscope and transmission electron microscope
US20100117772A1 (en) * 2007-03-06 2010-05-13 Koninklijke Philips Electronics N.V. Electromagnetic system for biosensors
US20110133084A1 (en) * 2008-09-30 2011-06-09 Isao Nagaoki Electron microscope
US20140124664A1 (en) * 2010-12-28 2014-05-08 Hitachi High-Technologies Corporation Device for correcting diffraction aberration of electron beam
WO2015111049A1 (en) * 2014-01-21 2015-07-30 Ramot At Tel-Aviv University Ltd. Method and device for manipulating particle beam
US20160189916A1 (en) * 2014-12-17 2016-06-30 Applied Materials Israel Ltd. Scanning charged particle beam device having an aberration correction aperture and method of operating thereof
EP3067912A1 (en) * 2015-03-12 2016-09-14 JEOL Ltd. Phase plate, method of fabricating same, and electron microscope

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3213277A (en) * 1961-07-15 1965-10-19 Siemens Ag Apertured correcting diaphragm to reduce astigmatism in electron lens system
US3469096A (en) * 1965-11-19 1969-09-23 Hanssen Karl Josef Corpuscular-ray device for phase or amplitude specimens with a phaserotating foil

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3213277A (en) * 1961-07-15 1965-10-19 Siemens Ag Apertured correcting diaphragm to reduce astigmatism in electron lens system
US3469096A (en) * 1965-11-19 1969-09-23 Hanssen Karl Josef Corpuscular-ray device for phase or amplitude specimens with a phaserotating foil

Cited By (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3869611A (en) * 1969-09-19 1975-03-04 Siemens Ag Particle-beam device of the raster type
US3857034A (en) * 1970-08-31 1974-12-24 Max Planck Gesellschaft Scanning charged beam particle beam microscope
USRE29500E (en) * 1970-08-31 1977-12-20 Max-Planck-Gesellschaft Zur Forderung Der Wissenschaften E.V. Scanning charged beam particle beam microscope
US20020148962A1 (en) * 2001-02-09 2002-10-17 Jeol Ltd. Lens system for phase plate for transmission electron microscope and transmission electron microscope
US6744048B2 (en) * 2001-02-09 2004-06-01 Jeol Ltd. Lens system for phase plate for transmission electron microscope and transmission electron microscope
US20100117772A1 (en) * 2007-03-06 2010-05-13 Koninklijke Philips Electronics N.V. Electromagnetic system for biosensors
US8237434B2 (en) * 2007-03-06 2012-08-07 Koninklijke Philips Electronics N.V. Electromagnetic system for biosensors
US20110133084A1 (en) * 2008-09-30 2011-06-09 Isao Nagaoki Electron microscope
EP2333809A4 (en) * 2008-09-30 2012-04-25 Hitachi High Tech Corp Electron microscope
US8426811B2 (en) * 2008-09-30 2013-04-23 Hitachi High-Technologies Corporation Electron microscope
US20140124664A1 (en) * 2010-12-28 2014-05-08 Hitachi High-Technologies Corporation Device for correcting diffraction aberration of electron beam
US9123501B2 (en) * 2010-12-28 2015-09-01 Hitachi High-Technologies Corporation Device for correcting diffraction aberration of electron beam
KR101591154B1 (ko) * 2010-12-28 2016-02-02 가부시키가이샤 히다치 하이테크놀로지즈 회절 수차 보정기를 적용한 하전 입자 빔 현미경
WO2015111049A1 (en) * 2014-01-21 2015-07-30 Ramot At Tel-Aviv University Ltd. Method and device for manipulating particle beam
CN106104744A (zh) * 2014-01-21 2016-11-09 拉莫特特拉维夫大学有限公司 用于调节粒子波束的方法与装置
US20160343536A1 (en) * 2014-01-21 2016-11-24 Ramot At Tel-Aviv University Ltd. Method and device for manipulating particle beam
EP3097577A4 (en) * 2014-01-21 2017-09-20 Ramot at Tel-Aviv University Ltd. Method and device for manipulating particle beam
US9953802B2 (en) * 2014-01-21 2018-04-24 Ramot At Tel-Aviv University Ltd. Method and device for manipulating particle beam
CN106104744B (zh) * 2014-01-21 2019-04-16 拉莫特特拉维夫大学有限公司 用于调节粒子波束的方法与装置
US10497537B2 (en) 2014-01-21 2019-12-03 Ramot At Tel-Aviv University Ltd. Method and device for manipulating particle beam
EP3754689A1 (en) * 2014-01-21 2020-12-23 Ramot at Tel-Aviv University Ltd. Method and device for manipulating particle beam
US20160189916A1 (en) * 2014-12-17 2016-06-30 Applied Materials Israel Ltd. Scanning charged particle beam device having an aberration correction aperture and method of operating thereof
EP3067912A1 (en) * 2015-03-12 2016-09-14 JEOL Ltd. Phase plate, method of fabricating same, and electron microscope

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Publication number Publication date
GB1203705A (en) 1970-09-03
DE1807277B2 (enrdf_load_stackoverflow) 1970-09-17
DE1807277A1 (de) 1970-01-08
NL6900965A (enrdf_load_stackoverflow) 1969-12-30

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