The present invention relates to a charged particle beam apparatus enabling a selection of a charged particle beam in a specified energy range by symmetrically arranging cylindrical electrostatic lenses deflecting a path of the charged particle beam and disposing an energy selection aperture between the cylindrical electrostatic lenses. Since an integral structure in which a central electrode and a plurality of electrodes that are arranged at a front portion and a rear portion in relation to the central electrode of a monochromator are fixed to each other through insulator, is applied, a mechanism for adjusting an offset with respect to an optical axis is simplified as compared to the case of separately providing the lenses at the front portion and the rear portion, respectively, and a secondary aberration is canceled in an exit plane due to symmetry of an optical system.

Electrostatic lenses for focusing a beam of charged particles, and in particular an electron beam, are used especially in the electron guns of electron microscopes or electron-beam lithography apparatuses. The present disclosure improves the possibilities for focusing the particle beam, in particular an electron beam emitted by a cathode. The lens comprises at least one conducting electrode having at least one through-opening for the passage of an electron beam. Different electric fields are set up upstream and downstream of the opening. The passage opening is at least partially closed by a planar or curved thin membrane of semi-conducting material that is transparent to electrons and has a high dielectric permittivity. Structuring the membrane (holes or thickened portions of electrodes deposited on the membrane) makes it possible to correct lens aberration defects.

A selectively configurable system for directing an electron beam with a limited energy spread to a sample includes an electron source to generate an electron beam having an energy spread including one or more energies, an aperture having an on-axis opening and an off-axis opening, a first assembly of one or more electron lenses with selectively configurable focal powers positioned to collect the beam from the source and direct the beam to the aperture, a second assembly of one or more selectively configurable electron lenses positioned to collect the beam, a sample stage, and an electron inspection sub-system including electron optics positioned to direct the beam onto one or more samples. The first assembly includes an off-axis electron lens for interacting with the beam at an off-axis position and introducing spatial dispersion to the beam when configured with a nonzero focal power, thus filtering the energy spread.

An electron energy loss spectrometer for electron microscopy is disclosed having an electrically isolated drift tube extending through the bending magnet and through subsequent optics that focus and magnify the spectrum. An electrostatic or magnetic lens is located either before or after or both before and after the drift tube and the lens or lenses are adjusted as a function of the bending magnet drift tube voltage to maintain a constant net focal length and to avoid defocusing. An energy selecting slit is included in certain embodiments to cleanly cut off electrons dispersed outside the energy range incident on the detector, thereby eliminating artifacts caused by unwanted electrons scattering back into the spectrum.

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.

A scanning electron microscope (SEM) with a swing objective lens (SOL) reduces the off-aberrations to enhance the image resolution, and extends the e-beam scanning angle. The scanning electron microscope comprises a charged particle source, an accelerating electrode, and a swing objective lens system including a pre-deflection unit, a swing deflection unit and an objective lens, all of them are rotationally symmetric with respect to an optical axis. The upper inner-face of the swing deflection unit is tilted an angle to the outer of the SEM and its lower inner-face is parallel to the optical axis. A distribution for a first and second focusing field of the swing objective lens is provided to limit the off-aberrations and can be performed by a single swing deflection unit. Preferably, the two focusing fields are overlapped by each other at least 80 percent.

To improve the efficiency of generation of chromatic aberrations of an energy filter for reducing energy distribution. Mounted are an energy filter for primary electrons, the energy filter having a beam slit and a pair of a magnetic deflector and an electrostatic deflector that are superimposed with each other. An electron lens is arranged between the beam slit and the pair of the magnetic deflector and the electrostatic deflector.

Optical corrector modules for charged particle columns can include at least one split multipole that includes two multipoles separated by a distance less than 10 mm. Each of the individual multipoles may include at least two electrodes positioned to partially define a beam path through the multipole. Each of the electrodes can include a first surface that faces upstream of a charged particle beam when used in the charged particle column and a second surface that faces downstream of the charged particle beam when used in the charged particle column. The thickness between the first surface and the second surface for each of the electrodes may be less than 10 mm. The split multipoles may be electrostatic and may correspond to hexapoles.

A decelerating electrode of an energy filter includes an electrode pair that has an opening and a cavity portion provided in a rotationally symmetrical manner with the center of the opening as the optical axis. Voltages with electric potentials that are substantially the same as that of a charged particle beam are independently applied to both sides of the decelerating electrode. When an electrical field protrudes into the cavity portion, a saddle point having the same electric potential as that of incident charged particles is formed inside the decelerating electrode. The saddle point acts as a high pass filter for incident charged particles at an energy resolution of 1 mV or less. By analyzing charged particles which have been energy-separated, it is possible to measure the energy spectrum and E at the high resolution of 1 mV or less and to obtain an SEM/STEM image with a high resolution.

Foil lens correctors, charged particle microscope systems including the same, and associated methods. In an example, a foil lens corrector is configured to generate an offsetting spherical aberration in a charged particle beam and includes a graphene foil. In an example, a CPM system includes a charged particle source and a foil lens corrector including a graphene foil. In an example, a method of operating a CPM system includes directing a charged particle beam to a specimen and operating a foil lens corrector to generate an offsetting spherical aberration in the charged particle beam. In an example, the charged particle beam is incident upon a foil of the foil lens corrector with a foil landing energy that is at least 5 keV and at most 80 keV and such that the charged particle beam is transmitted through the foil with a transmission ratio that is at least 20%.