Abstract:
A corrector (1) for the axial and off-axial beam path of a particle-optical system, comprises a first (10) and a second (20) correction piece, which are disposed one behind the other in the beam path (2) on an optical axis (3). Each correction piece (10, 20) comprises four successive multipole elements (11, 12, 13, 14; 24, 23, 22, 21) disposed symmetrically with respect to a center plane (5) and with the following fields: wherein the first (11; 24) and the fourth (14; 21) multipole elements of the multipole elements (11, 12, 13, 14; 24, 23, 22, 21) are used to generate quadrupole fields (11′, 14′; 24′, 21′) and the second (12; 23) and third (13; 22) are used to generate octupole fields (12′″, 13′″; 23′″,22′″) and quadrupole fields (12′, 13′; 23′,22′), wherein the latter are superposed magnetic (12′, 13′; 23′, 22′) and electric fields (12″, 13″; 23″, 22″), wherein the quadrupole fields (11′, 12′, 13′, 14′; 24′, 23′, 22′, 21′) of all four multipole elements (11, 12, 13, 14; 24, 23, 22,21) are rotated from one to the next through 90°. An astigmatism of third order is corrected by a central multipole element disposed in the center plane and generating an octupole field.
Abstract:
An electron beam apparatus has a primary beam directed onto a point of a specimen to generate emerging secondary electrons that proceed to a detector after traversing an electrical extraction field. The extraction field is provided between electrodes arranged in a plane perpendicular to the optical axis of the electron beam device and a magnetic field is provided perpendicular to the electrical extraction field to compensate for the forces of the extraction field exerted on the primary beam yet to promote extraction of the secondary electrons.
Abstract:
According to the invention, the image contrast in electron optics can be improved without causing aberrations that are no longer tolerable by using, for production and correction of the at least one anamorphic image, quadrupole fields before and after this image whose extent in the direction of the optical axis is equal to at least twice their focal length, and wherein at least one of the axial rays, by an appropriate choice of the magnification M of the intermediate image, enters the quadrupole field before the at least one anamorphic image at a slope 1/M such that a length of the anamorphic image is achieved at which any aberrations caused are still within a tolerable range. The invention also relates to devices for implementing this method.
Abstract:
In a high resolution imaging system for close inspection of sub-micrometer structures, a scanning electron microscope includes a detector objective essentially composed of an immersion lens and an annular detector which is arranged between a source side electrode lying at a positive potential and a middle electrode of the immersion lens which likewise lies at a variable positive potential and is arranged concentrically relative to a beam axis of a scanning microscope. The middle electrode and the source side electrode are preferrably formed as truncated cones. The two-stage deflection element for positioning the primary electron beam on the specimen is preferrably integrated into the source side electrode of the immersion lens, the source side electrode being composed of an annular diaphragm and a hollow cylinder.
Abstract:
The invention relates to a method for producing image contrast by phase shifting in the electron optics, wherein, from an intermediate image (5), an anamorphic image (6, 6′) of the axial rays (xα, yβ) is produced by quadrupole fields (Q1′, Q2′, Q3′; Q11′, Q12′, Q13′) with simultaneous passage through zero of the field rays (xγ, yδ) in at least one diffraction intermediate image plane (8, 8′), where a relative phase shift between a region (14) around the electron beam of zeroth order of diffraction (13) and the electron beams of higher orders of diffraction (15) is caused by a magnetic or electric field (9, 9′), and thereafter the at least one anamorphosis of the beam path produced is corrected again by further quadrupole fields (Q4′, Q5′; Q13′, Q14′, Q15′). According to the invention, the image contrast can be further improved without causing aberrations that are no longer tolerable by using, for production and correction of the at least one anamorphic image (6, 6′), quadrupole fields (Q2′, Q4′; Q12′, Q14′) before and after this image (6, 6′) whose extent in the direction of the optical axis (10) is equal to at least twice their focal length, and wherein at least one of the axial rays (xα, yβ), by an appropriate choice of the magnification M of the intermediate image (5), enters the quadrupole field (Q2′, Q12′) before the at least one anamorphic image (6, 6′) at a slope 1/M such that a length (7) of the anamorphic image (6, 6′) is achieved at which any aberrations caused are still within a tolerable range. The invention also relates to devices for implementing this method.
Abstract:
A corrector (1) for the axial and off-axial beam path of a particle-optical system, comprises a first (10) and a second (20) correction piece, which are disposed one behind the other in the beam path (2) on an optical axis (3). Each correction piece (10, 20) comprises four successive multipole elements (11, 12, 13, 14; 24, 23, 22, 21) disposed symmetrically with respect to a center plane (5) and with the following fields: wherein the first (11; 24) and the fourth (14; 21) multipole elements of the multipole elements (11, 12, 13, 14; 24, 23, 22, 21) are used to generate quadrupole fields (11′, 14′; 24′, 21′) and the second (12; 23) and third (13; 22) are used to generate octupole fields (12′″, 13′″;23′″,22′″) and quadrupole fields (12′, 13′; 23′,22′), wherein the latter are superposed magnetic (12′, 13′; 23′, 22′) and electric fields (12″, 13″; 23″, 22″), wherein the quadrupole fields (11′, 12′, 13′, 14′; 24′, 23′, 22′, 21′) of all four multipole elements (11, 12, 13, 14; 24, 23, 22,21) are rotated from one to the next through 90°. An astigmatism of third order is corrected by a central multipole element disposed in the center plane and generating an octupole field.
Abstract:
In a corpuscular-optical beam path, the generation of short electron pulses with steep leading edges is to be effected without a probe movement in the probe plane taking place. For this purpose, the particle beam blanking system comprises at least two deflection systems and a knife edge arranged between two deflection systems in an intermediate image plane, the operating parameters of the deflection systems and the knife edge being matched to the energy distribution of the particles in such a fashion that shifting of the particle beam in the probe plane disappears.
Abstract:
A corrective for eliminating the third-order aperture aberration and the first-order, first-degree axial chromatic aberration includes two correction pieces, which are arranged one behind the other in the direction of the optical axis, in which each correction piece has a plurality of quadrupole fields (QP) and at least one octupole field (OP.) Each correction piece is constructed such that it is symmetrical with respect to its central plane (S, S′) with each correction piece having an uneven number of at least five quadrupole fields (QP) and at least one octupole field (OP). Each correction piece is further constructed so that it is symmetrical with respect to its central plane. The central quadrupole field is arranged so that it is centered with respect to the central plane of the correction piece and is electromagnetic. The quadrupole fields of the two correction pieces are antisymmetrical and a transfer lens system is arranged such that it is symmetrical with respect to the central plane of the corrective between the correction pieces. The transfer lens system has two round lenses and the setting of the transfer lens system takes place so that the two round lenses image the central plane of the two correction pieces anamorphically onto one another, in which the enlargement in one main section is the reciprocal of the enlargement in the other main section and with an octupole field superimposed on the central quadrupole field.
Abstract:
A corrective for eliminating the third-order aperture aberration and the first-order, first-degree axial chromatic aberration includes two correction pieces, which are arranged one behind the other in the direction of the optical axis, in which each correction piece has a plurality of quadrupole fields (QP) and at least one octupole field (OP.) Each correction piece is constructed such that it is symmetrical with respect to its central plane (S, S′) with each correction piece having an uneven number of at least five quadrupole fields (QP) and at least one octupole field (OP). Each correction piece is further constructed so that it is symmetrical with respect to its central plane. The central quadrupole field is arranged so that it is centered with respect to the central plane of the correction piece and is electromagnetic. The quadrupole fields of the two correction pieces are antisymmetrical and a transfer lens system is arranged such that it is symmetrical with respect to the central plane of the corrective between the correction pieces. The transfer lens system has two round lenses and the setting of the transfer lens system takes place so that the two round lenses image the central plane of the two correction pieces anamorphically onto one another, in which the enlargement in one main section is the reciprocal of the enlargement in the other main section and with an octupole field superimposed on the central quadrupole field.
Abstract:
The invention is directed to a corrector for correcting energy-dependent first-order aberrations of the first degree as well as third-order spherical aberrations of electron-optical lens systems. The corrector includes at least one quadropole septuplet (S1) having seven quadrupoles (Q1 to Q7). The quadrupoles are mounted symmetrically to a center plane (ZS) so as to permit excitation along a linear axis. The corrector furthermore includes at least five octopoles (O1 to O7) which can be excited within the quadrupole septuplet. In an advantageous embodiment, two quadrupole septuplets are mounted in series one behind the other. The quadrupole fields of the two quadrupole septuplets are excited antisymmetrically to a center plane lying between the two quadrupole septuplets. With such a system, all geometric third-order aberrations and additional energy-dependent first-order aberrations of the third degree and geometric fifth-order aberrations of a lens system can be corrected in addition to the axial and off-axial first-order chromatic aberrations of the first degree.