A method of evaluating a region of a sample, the method comprising: positioning a sample within a vacuum chamber; generating an electron beam with a scanning electron microscope (SEM) column that includes an electron gun at one end of the column and a column cap at an opposite end of the column; focusing the electron beam on the sample and scanning the focused electron beam across the region of the sample, while the SEM column is operated in tilted mode, thereby generating secondary electrons and backscattered electrons from within the region; and during the scanning, collecting backscattered electrons with one or more detectors while applying a negative bias voltage to the column cap to alter a trajectory of the secondary electrons preventing the secondary electrons from reaching the one or more detectors.

The present invention enables an overlay error between processors to be measured from a pattern image, the SN ratio of which is low. To this end, the present invention forms a secondary electron image 200 from a detection signal of a secondary electron detector 107, forms a reflected electron image 210 from a detection signal of a reflected electron detector 109, creates a SUMLINE profile 701 that is obtained by adding luminance information in the reflected electron image along the longitudinal direction of a line pattern, and calculates an overlay error of a sample by using position information about an upper layer pattern detected from the secondary electron image and position information about a lower layer pattern that is detected by using an estimation line pattern 801 estimated on the basis of the SUMLINE profile from the reflected electron image.

Methods and systems for detecting charged particles from a specimen are provided. One system includes a first repelling mesh configured to repel charged particles from a specimen having an energy lower than a first predetermined energy and a second repelling mesh configured to repel the charged particles that pass through the first repelling mesh and have an energy that is lower than a second predetermined energy. The system also includes a first attracting mesh configured to attract the charged particles that pass through the first repelling mesh, are repelled by the second repelling mesh, and have an energy that is higher than the first predetermined energy and lower than the second predetermined energy. The system further includes a first detector configured to generate output responsive to the charged particles that pass through the first attracting mesh.

A method of, and a detector for, performing energy sensitive imaging of ionizing radiation are provided, including acquiring a first frame having a plurality of pixels, each pixel of the plurality having an energy of detection and a location; grouping, into a cluster, pixels of the plurality having an energy of detection above a predetermined threshold and a location along with at least one other pixel also having an energy of detection above the predetermined threshold and being within a predetermined distance of the location; summing the energy of detection of all pixels within the grouped cluster to determine a cluster energy; determining a location of the cluster based on a distribution and an intensity of the summed energy of detection; and generating an image of the cluster based on the determined cluster energy and the determined location of the cluster.

A charged particle beam apparatus includes a database that stores a to-be-used-in-calculation device model for use in estimation of a circuit of a sample and an optical condition under which a charged particle beam is applied to the sample, a charged particle beam optical system that controls the beam applied to the sample under the optical condition, a detector that detects secondary electrons emitted from the sample excited by the application of the beam and outputs a detection signal based on the secondary electrons, and a computing unit that generates a to-be-used-in-computation netlist based on the to-be-used-in-calculation device model, estimates a first application result when the beam is applied to the sample based on the to-be-used-in-computation netlist and the optical condition, and compares the first application result with a second application result when the beam is applied to the sample based on the optical condition.

Methods and apparatus determine offcut angle of a crystalline sample using electron channeling patterns (ECPs), wherein backscattered electron intensity exhibits angular variation dependent on crystal orientation. A zone axis normal to a given crystal plane follows a circle as the sample is azimuthally rotated. On an ECP image presented with tilt angles as axes, the radius of the circle is the offcut angle of the sample. Large offcut angles are determined by a tilt technique that brings the zone axis into the ECP field of view. ECPs are produced with a scanning electron beam and a monolithic backscattered electron detector; or alternatively with a stationary electron beam and a pixelated electron backscatter diffraction detector. Applications include strain engineering, process monitoring, detecting spatial variations, and incoming wafer inspection. Methods are 40× faster than X-ray diffraction. 0.01-0.1° accuracy enables semiconductor applications.

A scanning electron microscope and a method for evaluating a sample, the method may include (a) illuminating the sample with a primary electron beam, (b) directing secondary electrons emitted from the sample and propagated above a first scintillator, towards an upper portion of the first scintillator, wherein the first scintillator and a second scintillator are positioned between the sample and a column electrode of the column; wherein the first scintillator is positioned above the second scintillator; (c) detecting the secondary electrons by the first scintillator; (d) directing backscattered electrons emitted from the sample towards a lower portion of the second scintillator; and (e) detecting the backscattered electrons by the second scintillator.

A system and corresponding method for electron cryomicroscopy, comprising: a field-emission gun for generating an electron beam, the field-emission gun being energized, in use, to generate a 80 keV to 120 keV electron beam which is emitted into a vacuum enclosure and towards a specimen holder; the vacuum enclosure containing, at least in part: an objective lens for focusing an image of the specimen, the objective lens being disposed in the path of the electron beam and having a chromatic aberration coefficient, Cc, selected to achieve a resolution value better than a desired amount; the specimen holder for holding a specimen, the specimen holder being disposed in the path of the electron beam; a cryostage for cooling a specimen; a cryo-shield for surrounding a specimen and reducing an ice contamination rate of the specimen; and a direct electron detector comprising an array of pixels, each pixel capable of detecting an incident electron that has passed through a sample and struck the pixel.

Some disclosed embodiments include an electron detector comprising: a first semiconductor layer having a first portion and a second portion; a second semiconductor layer; a third semiconductor layer; a PIN region formed by the first, second, and third semiconductor layers; a power supply configured to apply a reverse bias between the first and the third semiconductor layers; and a depletion region formed within the PIN region by the reverse bias and configured to generate a detector signal based on a first subset of the plurality of signal electrons captured within the depletion region, wherein the second portion of the first semiconductor layer is not depleted and is configured to provide an energy barrier to block a second subset of the plurality of signal electrons and to allow the first subset of the plurality of signal electrons to pass through to reach the depletion region.

In order to allow detecting backscattered electrons (BSEs) generated from the bottom of a hole for determining whether a hole with a super high aspect ratio is opened or for inspecting and measuring the ratio of the top diameter to the bottom diameter of a hole, which are typified in 3D-NAND processes of opening a hole, a primary electron beam accelerated at a high accelerating voltage is applied to a sample. Backscattered electrons (BSEs) at a low angle (e.g. a zenith angle of five degrees or more) are detected. Thus, the bottom of a hole is observed using “penetrating BSEs” having been emitted from the bottom of the hole and penetrated the side wall. Using the characteristics in which a penetrating distance is relatively prolonged through a deep hole and the amount of penetrating BSEs is decreased to cause a dark image, a calibration curve expressing the relationship between a hole depth and the brightness is given to measure the hole depth.