The disclosure relates to apparatus and methods for manipulating charged particle beams. In one arrangement, an aperture assembly is provided that comprises a first aperture body and a second aperture body. Apertures in the first aperture body are aligned with apertures in the second aperture body. The alignment allows charged particle beams to pass through the aperture assembly. The first aperture body comprises a first electrode system for applying an electrical potential to an aperture perimeter surface of each aperture in the first aperture body. The first electrode system comprises a plurality of electrodes. Each electrode is electrically isolated from each other electrode and electrically connected simultaneously to the aperture perimeter surfaces of a different one of a plurality of groups of the apertures in the first aperture body.

The disclosure relates to charged-particle multi-beam columns and multi-beam column arrays. In one arrangement, a sub-beam defining aperture array forms sub-beams from a beam of charged particles. A collimator array collimates the sub-beams An objective lens array projects the collimated sub-beams onto a sample. A detector detects charged particles emitted from the sample. Each collimator is directly adjacent to one of the objective lenses. The detector is provided in a plane down-beam from the sub-beam defining aperture array.

A detector substrate (or detector array) for use in a charged particle multi-beam assessment tool to detect charged particles from a sample. The detector substrate defines an array of apertures for beam paths of respective charged particle beams of a multi-beam. The detector substrate includes a sensor unit array. A sensor unit of the sensor unit array is adjacent to a corresponding aperture of the aperture array. The sensor unit is configured to capture charged particles from the sample. The detector array may include an amplification circuit associated with each sensor unit in the sensor unit array and proximate to the corresponding aperture in the aperture array. The amplification circuit may include a Trans Impedance Amplifier and/or an analogue to digital converter.

A method of reducing aberration comprises separating charged particles of a beam based on energy of the charged particles to form beamlets, each of the beamlets configured to include charged particles at a central energy level; and deflecting the beamlets so that beamlets having different central energy levels are deflected differently. An aberration corrector comprises a dispersive element configured to cause constituent parts of a beam (e.g. a charged particle beam) to spread apart based on energy; an aperture array configured to form beamlets from the spread apart beam; and a deflector array configured to deflect the beamlets differently based on central energy levels of particles that form the beamlets.

A multi-beam electron-optical system for a charged-particle assessment tool, the system comprising: a plurality of control lenses, a plurality of objective lenses and a controller. The plurality of control lenses are configured to control a parameter of a respective sub-beam. The plurality of objective lenses are configured to project one of the plurality of charged-particle beams onto a sample. The controller controls the control lenses and the objective lenses so that the charged particles are incident on the sample with a desired landing energy, demagnification and/or beam opening angle.

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 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.

Disclosed herein is a substrate stack comprising a plurality of substrates, wherein: each substrate in the substrate stack comprises at least one alignment opening set; the at least one alignment opening set in each substrate is aligned for a light beam to pass through corresponding alignment openings in each substrate; and each substrate comprises at least one alignment opening that has a smaller diameter than the corresponding alignment openings in the other substrates.

An electrostatic device includes a top and a bottom silicon layer, around an insulating buried layer. A beam opening allows a beam of charged particles to travel through. The device is encapsulated in an insulating layer. One or more electrodes and ground planes are deposited on the insulating layer. These also cover the inside of the beam opening. Electrodes and ground planes are physically and electrically separated by micro-trenches and micro-undercuts that provide shadow areas when the conductive areas are deposited. Electrodes may be shaped as elongated islands and may include portions overhanging the top silicon layer, supported by electrode-anchors. Manufacturing starts from a single wafer including the top, buried, and bottom layers, or it starts from two separate silicon wafers. Manufacturing includes steps to form the top and bottom beam openings and microstructures, to encapsulate the device in an insulating layer, and to deposit electrodes and ground areas.

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.