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.

Abstract: An electrostatic corrector with a rectilinear optical axis has two corrective parts, which are arranged one behind the other along the optical axis and which have respective quadrupole fields and superimposed circular lens fields. The astigmatic intermediate image of one cross-section that is created by an axis point lies in one corrective part and the astigmatic intermediate image of the other cross-section, which is perpendicular to the first cross-section, lies in the other corrective part. An object of the invention is to eliminate the chromatic aberration of particle lenses. To achieve this, an electrostatic corrector is used, which includes two corrector units having similar instrumental construction, with each of the two corrector units having input and output sides on which two additional electrostatic quadrupoles are located. The two corrector units represent the axial paths in a telescopic manner in a 1:1 representation.

Abstract: An electrostatic corrector for eliminating the chromatic aberration of particle lenses, includes a corrector having a straight optical axis and an electrostatic quadrupole for allocating to the objective lens. Two corrector pieces are positioned behind the quadrupole, along the optical axis in the direction of radiation. Each corrector piece has three electrical quadrupole fields with an overlying circular lens field. The quadrupole fields, however, are rotated 90° about the optical axis in relation to each other. This arrangement is adjusted so that the astigmatic first image of one sectional view lies in one corrector piece and the astigmatic first image perpendicular thereto, of the other sectional view, lies in the other corrector piece, with another electrostatic quadrupole being located on the output side.

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.

Abstract: An optical particle corrector with a straight optical axis for eliminating color and aperture aberrations in optical particle lenses includes multipole elements in the form of electric and/or magnetic quadrupole and octupole elements. There are at least twelve quadrupole elements and ten octupole elements, in which three quadrupole elements and two octupole elements are assembled into a group. These groups are arranged successively along the straight optical axis, in which a first symmetrical plane is defined between the first and second groups, a second symmetrical plane is defined between the second and third groups and a third symmetrical plane is defined between the third and fourth groups. The multipole elements from one group to another correspond to each other in pairs, in which the multipole elements of the corresponding following group are positioned in reverse order along the straight optical axis in comparison with the corresponding multipole elements of the preceding group.

Abstract: An electron-optical lens arrangement with an axis that can be substantially displaced, and useful for electron lithography, includes a cylinder lens and a quadrupole field. The plane of symmetry of the quadrupole field extends in the mid-plane of the gap pertaining to the cylinder lens. The focussing level of the quadrupole is oriented in the direction of the gap. The amount of the focussing refractive power belonging to the cylinder lens is twice as high as the amount of the quadrupole. A deflection system for the charged particles is connected upstream in the level of the gap pertaining to the cylinder lens and several electrodes or pole shoes, which generate a quadrupole field are provided in the direction of the gap pertaining to the cylinder lens. The electrodes or pole shoes can be individually and, preferably, successively excited and the quadrupole field can be displaced according to the deflection of the particle beam, so that the particle beam impinges upon the area of the quadrupole field.

Abstract: The invention relates to an electrostatic corrector based on an electrostatic corrector with a rectilinear optical axis (1) and two corrective parts (8, 9), which are arranged one behind the other along the optical axis and have respective quadrupole fields and superimposed circular lens fields. The astigmatic intermediate image of one cross-section that is created by an axis point lies in one corrective pan and the astigmatic intermediate image of the other cross-section, which is perpendicular to said first cross-section, lies in the other corrective part. The aim of the invention is to eliminate the chromatic aberration of particle lenses. To achieve this, the invention provides a corrector comprising two corrective units with a similar instrumental construction, each having one of the corrective parts, on whose respective input and output sides two additional electrostatic quadrupoles are located. Said corrective units represent the axial paths in a telescopic manner in a 1:1 representation.

Abstract: The invention relates to a particle beam system comprising a particle source (1), a mirror corrector (9, 21 to 25), and an objective lens (16). The mirror corrector comprises an electrostatic mirror (9) and a magnetic beam deflector (21, 22, 23, 24, 25), which is arranged between the particle source (1) and the electrostatic mirror (9) as well as between the electrostatic mirror (9) and the objective lens (16). The magnetic beam deflector (21, 22, 23, 24, 25) is free from dispersion for each single pass. The magnetic beam deflector (21, 22, 23, 24, 25) also comprises quadrupoles and/or quadrupole components, which are provided in such a manner that a maximum of two planes, which are conjugated with regard to the diffraction plane (28) of the objective lens (16), occur on the entire path length between the first outlet from the magnetic beam deflector (21, 22, 23, 24, 25) and from the objective lens (16).

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.

Abstract: The invention relates to an electron energy filter with magnetic deflection regions and a substantially W-shaped beam path. The energy filter has at least four magnetic deflection regions, that are respectively separated from each other by drift paths in the space free from magnetic fields. The whole filter is thus symmetrical with respect to a midplane (M). The total deflection angle in the first and last deflection region is at least 135°, and all the deflection regions together effect a deflection of the optical axis through an angle between 90° and 210°, preferably through 180°. The energy filter has a large Helmholtz length that is greater than double the average value of the deflection radii in the deflection regions.

Abstract: The invention relates to an electron-optical corrector for elimanting third-order aberrations, such as spherical aberrations, field curvature and off-axis astigmatism; said corrector being devoid of third-order off-axis coma, third-order distrortion and first-order chromatic aberration of the first degree. The corrector has a construction which is symmetrical about the central plane in the direction of the linear optical axis. A hexapole S1 of length l1is first positioned in the direction of the beam path, followed by a circular lens Rl, a hexapole S2 of length l2 and subsequently a circular lens R2 which is followed by a third hexapole S3 with the same strength with the same strength of the hexapole Sl and double the length of the latter 13=213.

Abstract: The invention relates to an electron energy filter with magnetic deflection regions and a substantially W-shaped beam path. The energy filter has at least four magnetic deflection regions, that are respectively separated from each other by drift paths in the space free from magnetic fields. The whole filter is thus symmetrical with respect to a midplane (M). The total deflection angle in the first and last deflection region is at least 135°, and all the deflection regions together effect a deflection of the optical axis through an angle between 90° and 210°, preferably through 180°. The energy filter has a large Helmholtz length that is greater than double the average value of the deflection radii in the deflection regions.

Abstract: The invention relates to an electron energy filter for electron microscopes as well as to an electron microscope equipped with such a filter. The filter comprises three sector magnets with the deflection field in the first sector magnet being homogeneous. The deflection field in each of the two other sector magnets is an inhomogeneous gradient field. To generate the gradient field, the pole pieces of the two other sector magnets have the form of segments of truncated double cones. The electron beam passes the first homogeneous sector magnet twice. Multipole elements are arranged in front of, behind and between the three sector magnets. The filter has a large dispersion also for high-energy electrons while at the same time providing a compact configuration. All second-order aberrations and the significant second-rank aberrations are corrected by means of the multiple elements.

Abstract: An imaging symmetrical energy filter (of the .OMEGA.-type) comprising two pairs of sector magnets (1), (2), (3), (4) for an electron microscope. The second-order chromatic aberration is corrected by arranging the two pairs of sector magnets {(1),(4) and (2),(3)} further apart. This enables suitable arrangement of the coils to generate correction hexapole fields, so that the chromatic error is even completely eliminated. Moreover, correction of the third-order aperture aberration is also possible by constructing the hexapole coil (9) in the symmetry plane also as an octupole coil. Further correction of this third-order aberration is achieved by applying an octupole field (5) directly at the entrance of the first sector magnet (1) and an octupole field (13) directly at the exit of the fourth sector magnet (4).

Abstract: An electron beam apparatus is provided with an energy selective device which enables spectrometric measurements together with imaging. The energy selective device has its main electron beam trajectory in a plane outside the optical axis of the electron beam apparatus, thereby substantially reducing the overall length of the apparatus. Preferably the energy selective device has double symmetry such that the energy dispersion has a maximum value in a central plane of symmetry where a selective slit can be introduced. Full symmetry facilitates full compensation of optical aberrations in the device. Adding quadruples in a second plane of symmetry enables imaging of spectra at a location outside the device.

Abstract: The invention relates to an imaging system for charged particles having a correction unit for correcting an objective lens. The correction unit essentially includes a beam deflector and a mirror which reflects the incoming particle beam. A first symmetry plane of the deflector is imaged in the mirror. The mirror images this first symmetry plane at an imaging scale of 1:1 in a second symmetry plane of the deflector. At the same time, the symmetry planes are either intermediate image planes or diffraction planes. With the high symmetry of the imaging system, the condition is achieved that the aberrations of the second order caused by a one-time passthrough through the deflector are cancelled after the second passthrough. The mirror can be so adjusted that its negative chromatic aberration compensates for the chromatic aberration of the objective lens and the other lenses. The spherical aberration can be compensated independently thereof with the aid of a hexapole which is centered in a diffraction plane.

Abstract: An energy selecting filter comprising a structure of four hemispheres to be transpassed successively by a beam of charged particles to be filtered. The structure is symmetrically with respect to a plane of symmetry in which the energy selecting element, such as slit or a knife-edge is introduced. In a charged particle beam apparatus such as a high resolution electron microscope the energy spread introduced by a source can adjustable be reduced to below for example 0,1 eV without introducing any beam deviation at the cost of only a small lengthening of the apparatus.

Abstract: A correction system for a high resolution charged particle beam apparatus provided with two hexapoles enclosing a telescopic round-lens system with two lenses which are arranged so that outer focal points of the lenses are coincident with nodal points which coincide with center points of the hexapoles. An additional coma-free round-lens doublet is added for imaging a coma-free plane of a lens to be corrected into a center plane of a first hexapole of the system. For both round-lens doublets the spacing between of the two lenses preferably equals 2f, f being the focal length of each lens.

Abstract: An electron beam generator or electron gun has a line-shaped cathode with a flattened tip as an electron source, a slotted diaphragm disposed in the plane of the cathode tip, and a double anode having two electrodes also fashioned as slotted diaphragms. The voltage potentials of the three slotted diaphragms, and their respective distances to the cathode, are selected such that a stigmatic virtual electron source at infinity is obtained.

Abstract: The invention relates to an imaging corrector of the Wien type which is especially suitable for use in an electron microscope. The corrector includes an arrangement of at least eight electrodes and at least eight magnetic poles and is mounted between two electron lenses. The corrector simultaneously corrects the chromatic and spherical aberrations especially of electron lenses of low-voltage electron microscopes. The corrector begins and ends at intermediate image planes and has an intermediate image plane in its center. The intermediate image plane at the center coacts with two symmetry planes located between the intermediate image planes for the desired imaging characteristics. All chromatic and spherical aberrations for electrons of any desired energy can be corrected with two of the correctors coacting with a thick telescopic round lens disposed therebetween.