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.

A particle beam system includes: a particle source to generate a beam of charged particles; a first multi-lens array including a first multiplicity of individually adjustable and focusing particle lenses so that at least some of the particles pass through openings in the multi-lens array in the form of a plurality of individual particle beams; a second multi-aperture plate including a multiplicity of second openings downstream of the first multi-lens array so that some of the particles which pass the first multi-lens array impinge on the second multi-aperture plate and some of the particles which pass the first multi-lens array pass through the openings in the second multi-aperture plate; and a controller configured to supply an individually adjustable voltage to the particle lenses of the first multi-lens array and thus individually adjust the focusing of the associated particle lens for each individual particle beam.

A system is disclosed. In embodiments, the system includes an electron source and a micro-lens array (MLA) configured to receive one or more primary electron beams from the electron source and split the one or more primary electron beams into a plurality of primary electron beamlets. In embodiments, the system further includes a micro-stigmator array (MSA) including a plurality of dodecapole electrostatic stigmators, wherein the MSA is configured to eliminate at least one of fourth-order focusing aberrations or sixth-order focusing aberrations of the plurality of primary electron beamlets. In embodiments, the system further includes projection optics configured to receive the plurality of primary electron beamlets and focus the plurality of primary electron beamlets onto a surface of a sample.

A charged particle beam system includes a charged particle source that generates a first charged particle beam and a multi beam generator that generates a plurality of charged particle beamlets from an incoming first charged particle beam. Each individual beamlet is spatially separated from other beamlets. The charged particle beam system also includes an objective lens that focuses incoming charged particle beamlets in a first plane so that a first region in which a first individual beamlet impinges in the first plane is spatially separated from a second region in which a second individual beamlet impinges in the first plane. The charged particle beam system also includes a projection system and a detector system including a plurality of individual detectors. The projection system images interaction products leaving the first region within the first plane due to impinging charged particles onto a first detector and images interaction products leaving the second region in the first plane onto a second detector.

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.

An improved source conversion unit of a charged particle beam apparatus is disclosed. The source conversion unit comprises a first micro-structure array including a plurality of micro-structures. The plurality of micro-structures is grouped into one or more groups. Corresponding electrodes of micro-structures in one group are electrically connected and driven by a driver to influence a corresponding group of beamlets. The micro-structures in one group may be single-pole structures or multi-pole structures. The micro-structures in one group have same or substantially same radial shifts from an optical axis of the apparatus. The micro-structures in one group have same or substantially same orientation angles with respect to their radial shift directions.

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.

A scanning electron microscopy system is disclosed. The system includes a multi-beam scanning electron microscopy (SEM) sub-system. The SEM sub-system includes a multi-beam electron source configured to form a plurality of electron beams, a sample stage configured to secure a sample, an electron-optical assembly to direct the electron beams onto a portion of the sample, and a detector assembly configured to simultaneously acquire multiple images of the surface of the sample. The system includes a controller configured to receive the images from the detector assembly, identify a best focus image of images by analyzing one or more image quality parameters of the images, and direct the multi-lens array to adjust a focus of one or more electron beams based on a focus of an electron beam corresponding with the identified best focus image.

Systems and methods of reducing the Coulomb interaction effects in a charged particle beam apparatus are disclosed. The charged particle beam apparatus may comprise a charged particle source and a source conversion unit comprising an aperture-lens forming electrode plate configured to be at a first voltage, an aperture lens plate configured to be at a second voltage that is different from the first voltage for generating a first electric field, which enables the aperture-lens forming electrode plate and the aperture lens plate to form aperture lenses of an aperture lens array to respectively focus a plurality of beamlets of the charged particle beam, and an imaging lens configured to focus the plurality of beamlets on an image plane. The charged particle beam apparatus may comprise an objective lens configured to focus the plurality of beamlets onto a surface of the sample and form a plurality of probe spots thereon.

A multi-beam particle beam system includes a multi-aperture plate having a multiplicity of apertures. During operation, one particle beam of the plurality of particle beams passes through each of the apertures. A multiplicity of electrodes are insulated from the second multi-aperture plate to influence the particle beam passing through the aperture. A voltage supply system for the electrodes includes: a signal a generator to generate a serial sequence of digital signals; a D/A converter to convert the digital signals into a sequence of voltages between an output of the D/A converter and the multi-aperture plate; and a controllable changeover system, which feeds the sequence of voltages successively to different electrodes.