Abstract: There is provided a beam alignment method capable of easily aligning an electron beam with a coma-free axis in an electron microscope. The method starts with tilting the electron beam (EB) in a first direction (+X) relative to a reference axis (A) and obtaining a first TEM (transmission electron microscope) image. Then, the beam is tilted in a second direction (?X) relative to the reference axis, the second direction (?X) being on the opposite side of the reference axis (A) from the first direction (+X), and a second TEM image is obtained. The reference axis is incrementally varied so as to reduce the brightness of the differential image between a power spectrum of the first TEM image and a power spectrum of the second TEM image.

Abstract: There is provided a beam alignment method capable of easily aligning an electron beam with a coma-free axis in an electron microscope. The method starts with tilting the electron beam (EB) in a first direction (+X) relative to a reference axis (A) and obtaining a first TEM (transmission electron microscope) image. Then, the beam is tilted in a second direction (?X) relative to the reference axis, the second direction (?X) being on the opposite side of the reference axis (A) from the first direction (+X), and a second TEM image is obtained. The reference axis is incrementally varied so as to reduce the brightness of the differential image between a power spectrum of the first TEM image and a power spectrum of the second TEM image.

Abstract: A chromatic aberration corrector and method of controlling this chromatic aberration corrector is offered. The corrector has first and second multipole lenses for producing quadrupole fields and first and second transfer lenses each having a focal length of f. The first and second multipole lenses are arranged on opposite sides of the first and second transfer lenses. The distance between the first multipole lens and the first transfer lens is f. The distance between the first transfer lens and the second transfer lens is 2f. The distance between the second transfer lens and the second multipole lens is f??. The corrector is so designed that the relationship, f>?>0, holds.

Abstract: The chromatic aberration corrector (100) has a first multipole element (110) for producing a first electromagnetic field and a second multipole element (120) for producing a second electromagnetic field. The first multipole element (110) first, second, and third portions (110a, 110b, 110c) arranged along an optical axis (OA) having a thickness and producing a quadrupole field in which an electric quadrupole field and a magnetic quadrupole field are superimposed. In the first and third portions (110a, 110c), the electric quadrupole field is set stronger than the magnetic quadrupole field. In the second portion (110b), the magnetic quadrupole field is set stronger than the electric quadrupole field. The second portion (110b) produces a two-fold astigmatism component that is opposite in sign to two-fold astigmatism components produced by the first portion (110a) and third portion (110c).

Abstract: The chromatic aberration corrector (100) has a first multipole element (110) for producing a first electromagnetic field and a second multipole element (120) for producing a second electromagnetic field. The first multipole element (110) first, second, and third portions (110a, 110b, 110c) arranged along an optical axis (OA) having a thickness and producing a quadrupole field in which an electric quadrupole field and a magnetic quadrupole field are superimposed. In the first and third portions (110a, 110c), the electric quadrupole field is set stronger than the magnetic quadrupole field. In the second portion (110b), the magnetic quadrupole field is set stronger than the electric quadrupole field. The second portion (110b) produces a two-fold astigmatism component that is opposite in sign to two-fold astigmatism components produced by the first portion (110a) and third portion (110c).

Abstract: An electron microscope is offered which facilitates aberration correction even during high-magnification imaging. The microscope has a spherical aberration corrector, a transfer lens system mounted between the corrector and an objective lens, an aperture stop mounted in a stage preceding the corrector so as to be movable relative to the optical axis, and an angular aperture stop mounted at or near the principal plane of the transfer lens system movably relative to the optical axis to adjust the angular aperture of the electron beam.

Abstract: An aberration corrector has two stages of multipole elements each of which has a thickness along the optical axis. Each multipole element produces a static electric or magnetic field of 3-fold symmetry and a static electromagnetic field of 2- or 3-fold symmetry superimposed on the static electric or magnetic field. In each of the multipole elements, the static electromagnetic field is so set that magnetic and electric deflecting forces on an electron beam accelerated by a given accelerating voltage substantially cancel out each other. Thus, chromatic aberration is corrected. Also, spherical aberration is corrected by the static electric or magnetic fields of 3-fold symmetry produced by the multipole elements.

Abstract: An electron microscope is offered which facilitates aberration correction even during high-magnification imaging. The microscope has a spherical aberration corrector, a transfer lens system mounted between the corrector and an objective lens, an aperture stop mounted in a stage preceding the corrector so as to be movable relative to the optical axis, and an angular aperture stop mounted at or near the principal plane of the transfer lens system movably relative to the optical axis to adjust the angular aperture of the electron beam.

Abstract: There is disclosed an electron beam system in which the third-order aberration S3 with two-fold symmetry is corrected. If a Cs corrector is operated, parasitic aberration S3 (third-order aberration S3 with two-fold symmetry) is produced. A corrective third-order aberration S3? with two-fold symmetry that cancels out the parasitic aberration S3 is produced within a multipole element to correct the parasitic aberration S3. The electron beam is tilted relative to the optical axis within the multipole element producing a hexapole field. The corrective third-order aberration S3? with two-fold symmetry is introduced in each electron forming the tilted electron beam.

Abstract: An aberration corrector has two stages of multipole elements each of which has a thickness along the optical axis. Each multipole element produces a static electric or magnetic field of 3-fold symmetry and a static electromagnetic field of 2- or 3-fold symmetry superimposed on the static electric or magnetic field. In each of the multipole elements, the static electromagnetic field is so set that magnetic and electric deflecting forces on an electron beam accelerated by a given accelerating voltage substantially cancel out each other. Thus, chromatic aberration is corrected. Also, spherical aberration is corrected by the static electric or magnetic fields of 3-fold symmetry produced by the multipole elements.

Abstract: An aberration for correcting higher-order aberrations with a relatively small number of components is by let N1 being the aberration order at a first location, S1 being the symmetry at the first location, N2 being the aberration order at a second location and S2 being the symmetry at the second location. The produced combination aberration satisfies the following condition set 1 as order=N1+N2?1 and symmetry=|S1+S2| or |S2?S1|. That is two aberration-correcting elements (aberration-introducing elements) corresponding to the first and second locations, respectively. An aberration satisfying the condition set 1 is corrected by making use of the produced combination aberration.

Abstract: An electron microscope has a spherical aberration correction system having transfer optics inserted between a spherical aberration corrector and the objective lens. The transfer optics consists of first and second lenses each of which is made of a magnetic lens. Electrons passing across a point located at distance r0 from the optical axis are made to enter the first lens within the multipole element. Electrons are made to enter the second lens at distance r1 of the incident point to the objective lens from the optical axis. The ratio M(=r1/r0) is greater than 1.

Abstract: An aberration for correcting higher-order aberrations with a relatively small number of components. Let N1 be the aberration order at a first location. Let S1 be the symmetry at the first location. Let N2 be the aberration order at a second location. Let S2 be the symmetry at the second location. The produced combination aberration satisfies the following condition set 1. order=N1+N2?1 symmetry=|S1+S2| or |S2?S1| That is, two aberration-correcting elements (aberration-introducing elements) corresponding to the first and second locations, respectively, are prepared. An aberration satisfying the condition set 1 is corrected by making use of the produced combination aberration.

Abstract: A chromatic aberration corrector has a relatively simple correction system capable of correcting the electron optical system of a transmission electron microscope for chromatic aberration. Furthermore, high-resolution imaging is enabled. The correction system uses a first multipole element for producing a quadrupole field to produce a concave lens effect. However, surplus two-fold astigmatism is left behind. This two-fold astigmatism is removed by inserting a second multipole element for producing a second quadrupole field. The first and second multipole elements are set to mutually opposite polarities. That is, the two-fold astigmatism is canceled out by combining the first and second multipole elements. A cylindrically symmetrical electron beam having spread can be corrected for chromatic aberration by the concave lens effect.

Abstract: There is disclosed an electron beam system in which the third-order aberration S3 with two-fold symmetry is corrected. If a Cs corrector is operated, parasitic aberration S3 (third-order aberration S3 with two-fold symmetry) is produced. A corrective third-order aberration S3? with two-fold symmetry that cancels out the parasitic aberration S3 is produced within a multipole element to correct the parasitic aberration S3. The electron beam is tilted relative to the optical axis within the multipole element producing a hexapole field. The corrective third-order aberration S3? with two-fold symmetry is introduced in each electron forming the tilted electron beam.

Abstract: An electron microscope has a spherical aberration correction system having transfer optics inserted between a spherical aberration corrector and the objective lens. The transfer optics consists of first and second lenses each of which is made of a magnetic lens. Electrons passing across a point located at distance r0 from the optical axis are made to enter the first lens within the multipole element. Electrons are made to enter the second lens at distance r1 of the incident point to the objective lens from the optical axis. The ratio M (=r1/r0) is greater than 1.

Abstract: Spherical aberration correction optics are offered which have an auxiliary function of determining control parameters easily and at any time while canceling deflecting and quadrupole fields in the instrument. The correction optics have a control unit for determining the parameters of the aberration correction optics and parameters for canceling the deflecting and quadrupole fields, a power supply for applying electric potentials or magnetic potentials to the aberration correction optics based on a signal from the control unit, and a period-varying circuit positioned between the control unit and the power supply to add a signal whose amplitude is varied continuously at frequency f with respect to real time t.

Abstract: Spherical aberration correction optics are offered which have an auxiliary function of determining control parameters easily and at any time while canceling deflecting and quadrupole fields in the instrument. The correction optics have a control unit for determining the parameters of the aberration correction optics and parameters for canceling the deflecting and quadrupole fields, a power supply for applying electric potentials or magnetic potentials to the aberration correction optics based on a signal from the control unit, and a period-varying circuit positioned between the control unit and the power supply to add a signal whose amplitude is varied continuously at frequency f with respect to real time t.

Abstract: A charged-particle beam instrument with an aberration corrector which comprises four stages of electrostatic quadrupole elements, two stages of magnetic quadrupole elements for superimposing a magnetic potential distribution analogous to the electric potential distribution created by the two central quadrupole elements of the four stages of electrostatic quadrupole elements on this electric potential distribution, and four stages of electrostatic octopole elements for superimposing an electric octopole potential on the electric potential distribution created by the four stages of electrostatic quadrupole elements.

Abstract: A spherical aberration corrector used in an electron microscope. The corrector has a spherical aberration correction optical system that permits the magnification to be varied. Rotational relation between two multipole elements within a plane perpendicular to the optical axis can be corrected without varying the phase angles of the multipole elements. A rotation-correcting lens is positioned within the focal plane of an electron trajectory formed between two axially symmetric lenses in the corrector to rotate electrons within a plane perpendicular to the optical axis.