A charged particle beam device is described, which includes: a beam source configured to generate a charged particle beam propagating along an optical axis (A); an aperture device with a plurality of apertures configured to create a plurality of beamlets from the charged particle beam; and a field curvature corrector. The field curvature corrector includes: a first multi-aperture electrode with a first plurality of openings having diameters that vary as a function of a distance from the optical axis (A); a second multi-aperture electrode with a second plurality of openings; and an adjustment device configured to adjust at least one of a first electrical potential (U1) of the first multi-aperture electrode and a second electrical potential (U2) of the second multi-aperture electrode. Further, a field curvature corrector and methods of operating a charged particle beam device are described.

A low voltage scanning electron microscope is disclosed, which includes: an electron source configured to generate an electron beam; an electron beam accelerator configured to accelerate the electron beam; a compound objective lens configured to converge the electron beams accelerated by the electron beam accelerator; a deflection device arranged between the inner wall of the magnetic lens and the optical axis of the electron beam and configured to deflect the electron beam; a detection device comprising a first sub-detection device for receiving secondary and backscattered electrons from the specimen, a second sub-detection device for receiving backscattered electrons, and a control device for changing the trajectories of the secondary electrons and the backscattered electrons; an electrostatic lens comprising the second sub-detection device, a specimen stage, and a control electrode for reducing the moving speed of the electron beam and changing the moving directions of the secondary and the backscattered electrons.

An aberration corrector includes: a first multipole, a second multipole, a third multipole, and a fourth multipole arranged along an optical axis A; a first transfer lens system arranged between the first multipole and the second multipole; a second transfer lens system arranged between the second multipole and the third multipole; and a third transfer lens system arranged between the third multipole and the fourth multipole, wherein each of the first multipole, the second multipole, the third multipole, and the fourth multipole generates a three-fold symmetric field.

An optical characterization system utilizing a micro-lens array (MLA) is provided. The system may include an electron source and a MLA including a micro-deflection array (MDA). The MDA may include an insulator substrate and a plurality of hexapole electrostatic deflectors disposed on the insulator substrate. The MDA may further include a plurality of voltage connecting lines configured to electrically couple the plurality of hexapole electrostatic deflectors to one or more voltage sources. The MDA may be configured to split a primary electron beam from the electron source into a plurality of primary electron beamlets. The system may be configured to focus the plurality of primary electron beamlets at a wafer plane.

A method of operating a charged particle beam device is disclosed, including passing each of a plurality of beamlets through a deflector and a scanner, in that order. Each of the beamlets is focused with an objective lens on a sample to form a plurality of focal spots, forming an array. A first beamlet is focused on a first spot and a second beamlet is focused on a second spot. In a centered configuration of the device, each of the plurality of beamlets is directed by the deflector toward a coma free point. In a beamlet-displaced configuration of the device, the scanner is scanned such that the first beamlet passes through an acceptable aberrations point, the first beamlet scanning a displaced first field of view; and the first spot is displaced from the regular first focal spot to a displaced first focal spot.

A method of operating a charged particle beam device is disclosed, including passing each of a plurality of beamlets through a deflector and a scanner, in that order. Each of the beamlets is focused with an objective lens on a sample to form a plurality of focal spots, forming an array. A first beamlet is focused on a first spot and a second beamlet is focused on a second spot. In a centered configuration of the device, each of the plurality of beamlets is directed by the deflector toward a coma free point. In a beamlet-displaced configuration of the device, the scanner is scanned such that the first beamlet passes through an acceptable aberrations point, the first beamlet scanning a displaced first field of view; and the first spot is displaced from the regular first focal spot to a displaced first focal spot.

A low voltage scanning electron microscope is disclosed, which includes: an electron source configured to generate an electron beam; an electron beam accelerator configured to accelerate the electron beam; a compound objective lens configured to converge the electron beams accelerated by the electron beam accelerator; a deflection device arranged between the inner wall of the magnetic lens and the optical axis of the electron beam and configured to deflect the electron beam; a detection device comprising a first sub-detection device for receiving secondary and backscattered electrons from the specimen, a second sub-detection device for receiving backscattered electrons, and a control device for changing the trajectories of the secondary electrons and the backscattered electrons; an electrostatic lens comprising the second sub-detection device, a specimen stage, and a control electrode for reducing the moving speed of the electron beam and changing the moving directions of the secondary and the backscattered electrons.

A multi-beam inspection apparatus including an improved source conversion unit is disclosed. The improved source conversion unit may comprise a micro-structure deflector array including a plurality of multipole structures. The micro-deflector deflector array may comprise a first multipole structure having a first radial shift from a central axis of the array and a second multipole structure having a second radial shift from the central axis of the array. The first radial shift is larger than the second radial shift, and the first multipole structure comprises a greater number of pole electrodes than the second multipole structure to reduce deflection aberrations when the plurality of multipole structures deflects a plurality of charged particle beams.

A multi-beam apparatus for observing a sample with high resolution and high throughput is proposed. In the apparatus, a source-conversion unit forms plural and parallel images of one single electron source by deflecting plural beamlets of a parallel primary-electron beam therefrom, and one objective lens focuses the plural deflected beamlets onto a sample surface and forms plural probe spots thereon. A movable condenser lens is used to collimate the primary-electron beam and vary the currents of the plural probe spots, a pre-beamlet-forming means weakens the Coulomb effect of the primary-electron beam, and the source-conversion unit minimizes the sizes of the plural probe spots by minimizing and compensating the off-axis aberrations of the objective lens and condenser lens.

A multi-beam apparatus for observing a sample with high resolution and high throughput is proposed. In the apparatus, a source-conversion unit changes a single electron source into a virtual multi-source array, a primary projection imaging system projects the array to form plural probe spots on the sample, and a condenser lens adjusts the currents of the plural probe spots. In the source-conversion unit, the image-forming means is on the upstream of the beamlet-limit means, and thereby generating less scattered electrons. The image-forming means not only forms the virtual multi-source array, but also compensates the off-axis aberrations of the plurality of probe spots.