A transmission electron microscope includes an electron beam source emitting an electron beam and an illumination optical system for directing the emitted electron beam at a sample. The illumination optical system has a first condenser lens, a second condenser lens, a third condenser lens, a fourth condenser lens, an objective lens, and a condenser aperture disposed at the position of the second condenser lens. The third condenser lens and the fourth condenser lens cooperate to make the position of the condenser aperture and a sample plane conjugate to each other. The first condenser lens and the second condenser lens cooperate to make the electron beam source and a front focal plane of the objective lens conjugate to each other while the conjugate relationship between the position of the condenser aperture and the sample plane is maintained by the third and fourth condenser lenses.

A charged particle beam system is disclosed, comprising: a charged particle beam generator for generating a beam of charged particles; a charged particle optical column arranged in a vacuum chamber, wherein the charged particle optical column is arranged for projecting the beam of charged particles onto a target, and wherein the charged particle optical column comprises a charged particle optical element for influencing the beam of charged particles; a source for providing a cleaning agent; a conduit connected to the source and arranged for introducing the cleaning agent towards the charged particle optical element;
wherein the charged particle optical element comprises: a charged particle transmitting aperture for transmitting and/or influencing the beam of charged particles, and at least one vent hole for providing a flow path between a first side and a second side of the charged particle optical element,
wherein the vent hole has a cross section which is larger than a cross section of the charged particle transmitting aperture. Further, a method for preventing or removing contamination in the charged particle transmitting apertures is disclosed, comprising the step of introducing the cleaning agent while the beam generator is active.

Systems and methods for automated alignment of cathodoluminescence (CL) optics in an electron microscope relative to a sample under inspection are described. Accurate placement of the sample and the electron beam landing position on the sample with respect to the focal point of a collection mirror that reflects CL light emitted by the sample is critical to optimizing the amount of light collected and to preserving information about the angle at which light is emitted from the sample. Systems and methods are described for alignment of the CL mirror in the XY plane, which is orthogonal to the axis of the electron beam, and for alignment of the sample with respect to the focal point of the CL mirror along the Z axis, which is coincident with the electron beam.

The invention provides a multi-pole deflector for a charged particle beam, and a charged particle beam imaging apparatus. The deflector includes a plurality of poles, including at least two pairs of poles, each pole in each pair of poles including a main body constructed in the form of a circular arc-shaped section and a protrusion projecting from an radial inner side of the main body. respective two main bodies of each pair of poles are arranged concentrically and diametrically opposite, and the at least two pairs of poles at least partially encompass and delimit a through-hole thereamong, which opens axially and is configured to receive and to pass therethrough the charged particle beam; and the at least two pairs of poles cooperate to generate respective secondary deflection fields distributed within the through-hole and across an internal space defined within the through-hole, respectively, and the secondary deflection fields are synthesized by combination of vectors into a resultant deflection field of the deflector which is distributed within and across the through-hole and is configured to deflect the charged particle beam passing therethrough.

A multi-beam apparatus for observing a sample with high resolution and high throughput and in flexibly varying observing conditions is proposed. The apparatus uses a movable collimating lens to flexibly vary the currents of the plural probe spots without influencing the intervals thereof, a new source-conversion unit to form the plural images of the single electron source and compensate off-axis aberrations of the plural probe spots with respect to observing conditions, and a pre-beamlet-forming means to reduce the strong Coulomb effect due to the primary-electron beam.

A charged particle assessment tool includes: an objective lens configured to project a plurality of charged particle beams onto a sample, the objective lens having a sample-facing surface defining a plurality of beam apertures through which respective ones of the charged particle beams are emitted toward the sample; and a plurality of capture electrodes adjacent respective ones of the beam apertures and configured to capture charged particles emitted from the sample.

The present disclosure aims at proposing a multi-beam irradiation device capable of correcting off-axis aberrations. In order to achieve the above object, a beam irradiation device is proposed, which includes a beam source which emits a plurality of beams; an objective lens (17) which focuses a beam on a sample; a first lens (16) which is arranged such that a lens main surface is positioned at an object point of the objective lens and deflects a plurality of incident beams toward an intersection point of a lens main surface of the objective lens and an optical axis; a second lens (15) which is arranged closer to a beam source side than the first lens and focuses the plurality of beams on a lens main surface of the first lens; and a third lens (14) which is arranged closer to the beam source side than the second lens and deflects the plurality of beams toward an intersection point of a lens main surface of the second lens and the optical axis.

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 system for generating an electron beam array, comprising a light source, a first substrate having a plurality of plasmonic lenses mounted thereon, the plasmonic lenses configured to received light from the light source and produce an electron emission, and a plurality of electrostatic microlenses configured to focus the electron emissions into a beam for focusing on a wafer substrate. A light source modulator and digital micro mirror may be included which captures light from the light source and projects light beamlets on the plasmonic lenses.

Systems and methods of mitigating Coulomb effect in a multi-beam apparatus are disclosed. The multi-beam apparatus may include a charged-particle source configured to generate a primary charged-particle beam along a primary optical axis, a first aperture array comprising a first plurality of apertures having shapes and configured to generate a plurality of primary beamlets derived from the primary charged-particle beam, a condenser lens comprising a plane adjustable along the primary optical axis, and a second aperture array comprising a second plurality of apertures configured to generate probing beamlets corresponding to the plurality of beamlets, wherein each of the plurality of probing beamlets comprises a portion of charged particles of a corresponding primary beamlet based on at least a position of the plane of the condenser lens and a characteristic of the second aperture array.