An adjustable magnetic field free objective lens for a charged particle microscope is disclosed herein. An example charged particle microscope at least includes first and second optical elements arranged on opposing sides of a sample plane, a third optical element arranged around the sample plane, and a controller coupled to control the first, second and third optical elements. The controller coupled to excite the first and second optical elements to generate first and second magnetic lenses, the first and second magnetic lenses formed on opposing sides of the sample plane and oriented in the same direction, and excite the third optical element to generate a third magnetic lens at the sample plane that is oriented in an opposite direction, where a ratio of the excitation of the third optical element to the excitation of the first and second optical elements adjusts a magnetic field at the sample plane.

A scanning electron microscope having an electron column positioned to direct an electron beam onto a sample the electron column having a vacuum enclosure; an electron source; and an electromagnetic objective lens positioned within the vacuum enclosure, the electromagnetic objective lens including a housing having an entry aperture at top surface thereof and an exit aperture at bottom thereof; an electromagnetic coil radially positioned within the housing; a light objective positioned within the housing and comprising a concave minor having a first axial aperture and a convex minor having a second axial aperture; an electron beam deflector positioned within the housing and comprising a first set of deflectors and a second set of deflectors positioned below the first set of deflectors, wherein the second set of deflectors is positioned below the first axial aperture and the first set of deflectors is positioned

An object is to provide a multipole unit capable of achieving both high positional accuracy and ease of assembling and preventing a decrease in the transmission rate of the magnetic flux. A multipole unit 109a includes a pole 1 that is made of a soft magnetic metal material, a shaft 2 that is made of a soft magnetic metal material and is magnetically connected to the pole, and a coil 3 that is wound around the shaft 2. The pole 1 is provided with a first fitting portion JP1 that forms a first recessed portion or a first protruding portion. The shaft 2 is provided with a second fitting portion JP2 that forms a second protruding portion or a second recessed portion. The first fitting portion JP1 and the second fitting portion JP2 are fitted with each other such that the pole 1 and the shaft 2 are physically separated from each other.

A charged particle beam device capable of generating an image having uniform image quality in a field of view is provided. The charged particle beam device includes: a beam source configured to irradiate a sample with a charged particle beam; a diaphragm including an opening used for angle discrimination of secondary charged particles emitted from the sample; a first detector provided closer to the sample than the diaphragm, and configured to detect a part of the secondary charged particles; a second detector provided closer to the beam source than the diaphragm, and configured to detect secondary charged particles passing through the opening; an image generation unit configured to generate an image based on a first signal output from the first detector or a second signal output from the second detector; and a composite ratio calculation unit configured to calculate a composite ratio for each position in a field of view based on the first signal or the second signal with respect to a calibration sample that is a sample having a flat surface. The image generation unit generates a composite image by synthesizing the first signal and the second signal with respect to an observation sample using the composite ratio.

This invention provides a charged particle source, which comprises an emitter and means fo generating a magnetic field distribution. The magnetic field distribution is minimum, about zero, or preferred zero at the tip of the emitter, and along the optical axis is maximum away from the tip immediately. In a preferred embodiment, the magnetic field distribution is provided by dual magnetic lens which provides an anti-symmetric magnetic field at the tip, such that magnetic field at the tip is zero.

An electron beam system for wafer inspection and review of 3D devices provides a depth of focus up to 20 microns. To inspect and review wafer surfaces or sub-micron-below surface defects with low landing energies in hundreds to thousands of electron Volts, a Wien-filter-free beam splitting optics with three magnetic deflectors can be used with an energy-boosting upper Wehnelt electrode to reduce spherical and chromatic aberration coefficients of the objective lens.

A charged particle beam device capable of generating an image having uniform image quality in a field of view is provided. The charged particle beam device includes: a beam source configured to irradiate a sample with a charged particle beam; a diaphragm including an opening used for angle discrimination of secondary charged particles emitted from the sample; a first detector provided closer to the sample than the diaphragm, and configured to detect a part of the secondary charged particles; a second detector provided closer to the beam source than the diaphragm, and configured to detect secondary charged particles passing through the opening; an image generation unit configured to generate an image based on a first signal output from the first detector or a second signal output from the second detector; and a composite ratio calculation unit configured to calculate a composite ratio for each position in a field of view based on the first signal or the second signal with respect to a calibration sample that is a sample having a flat surface. The image generation unit generates a composite image by synthesizing the first signal and the second signal with respect to an observation sample using the composite ratio.

This invention provides a charged particle source, which comprises an emitter and means for generating a magnetic field distribution. The magnetic field distribution is minimum, about zero, or preferred zero at the tip of the emitter, and along the optical axis is maximum away from the tip immediately. In a preferred embodiment, the magnetic field distribution is provided by dual magnetic lens which provides an anti-symmetric magnetic field at the tip, such that magnetic field at the tip is zero.

A beam deflector includes a magnetic-flux-guiding structure which has an opening through which a beam axis extends, and at least two coils arranged at the magnetic-flux-guiding structure so that they produce a magnetic field B.sub.1 having lines passing through the two coils in succession, leave the magnetic-flux-guiding structure at a first location on a first side in relation to the beam axis, cross the beam axis at a second location which is arranged at a distance along the beam axis from the magnetic-flux-guiding structure, re-enter into the magnetic flux-guiding structure at a third location on a second side lying opposite the first side, and extend around the opening from the third location to the first location within the magnetic-flux-guiding structure.

A particle beam system includes: a multi-beam particle source configured to generate a multiplicity of particle beams; an imaging optical unit configured to image an object plane in particle-optical fashion into an image plane and direct the multiplicity of particle beams on the image plane; and a field generating arrangement configured to generate electric and/or magnetic deflection fields of adjustable strength in regions close to the object plane. The particle beams are deflected in operation by the deflection fields through deflection angles that depend on the strength of the deflection fields.