Systems and methods are provided for charged particle detection. The detection system can comprise a signal processing circuit configured to generate a set of intensity gradients based on electron intensity data received from a plurality of electron sensing elements. The detection system can further comprise a beam spot processing module configured to determine, based on the set of intensity gradients, at least one boundary of a beam spot; and determine, based on the at least one boundary, that a first set of electron sensing elements of the plurality of electron sensing elements is within the beam spot. The beam spot processing module can further be configured to determine an intensity value of the beam spot based on the electron intensity data received from the first set of electron sensing elements and also generate an image of a wafer based on the intensity value.

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.

The invention provides an observation system capable of observing a formation position of a target shape that cannot be directly irradiated with an electron beam. The observation system includes an electron microscope and a computer. The electron microscope is configured to irradiate, with an electron beam, a first surface position on a specimen, which is different from a formation position of a target shape on the specimen, detect predetermined electrons that are scattered in the specimen from the first surface position and that escape from the formation position of the target shape to an outside of the specimen, and output the predetermined electrons as a detection signal. The computer is configured to output one or more values related to the target shape based on the detection signal.

The invention provides an observation system capable of observing a formation position of a target shape that cannot be directly irradiated with an electron beam. The observation system includes an electron microscope and a computer. The electron microscope is configured to irradiate, with an electron beam, a first surface position on a specimen, which is different from a formation position of a target shape on the specimen, detect predetermined electrons that are scattered in the specimen from the first surface position and that escape from the formation position of the target shape to an outside of the specimen, and output the predetermined electrons as a detection signal. The computer is configured to output one or more values related to the target shape based on the detection signal.

A defect observation method includes, as steps executed by a computer system, a first step of acquiring, as a bevel image, an image captured using defect candidate coordinates in a bevel portion as an imaging position by using a microscope or an imaging apparatus; and a second step of detecting a defect in the bevel image. The second step includes a step of determining whether there is at least one portion among a wafer edge, a wafer notch, and an orientation flat in the bevel image, a step of switching and selectively applying a defect detection scheme of detecting the defect from the bevel image from a plurality of schemes which are candidates based on a determination result, and a step of executing a process of detecting the defect from the bevel image in conformity with the switched scheme.

A defect observation method includes, as steps executed by a computer system, a first step of acquiring, as a bevel image, an image captured using defect candidate coordinates in a bevel portion as an imaging position by using a microscope or an imaging apparatus; and a second step of detecting a defect in the bevel image. The second step includes a step of determining whether there is at least one portion among a wafer edge, a wafer notch, and an orientation flat in the bevel image, a step of switching and selectively applying a defect detection scheme of detecting the defect from the bevel image from a plurality of schemes which are candidates based on a determination result, and a step of executing a process of detecting the defect from the bevel image in conformity with the switched scheme.

A data processing device for detecting defects in sample image data generated by a charged particle assessment system, the device comprising: a first processing module configured to receive a sample image datastream from the charged particle assessment system, the sample image datastream comprising an ordered series of data points representing an image of the sample, and to apply a first defect detection test to select a subset of the sample image datastream as first selected data, wherein the first defect detection test is a localised test which is performed in parallel with receipt of the sample image datastream; and a second processing module configured to receive the first selected data and to apply a second defect detection test to select a subset of the first selected data as second selected data.

Disclosed in the embodiments of the present invention is an electron microscope, comprising: an electron source, which is configured to generate an electron beam; a first beam conduit, which is configured to accelerate the electron beam; a second beam conduit, which is configured to accelerate the electron beam; a first detector, which is disposed between the first beam conduit and the second beam conduit and configured to receive secondary electrons generated by the electron beam acting on a sample to be tested; and a control electrode, which is disposed between the first detector and an optical axis of the electron beam and configured to change the direction of movement of backscattered electrons and the secondary electrons generated by the electron beam acting on said sample. By means of the electron microscope provided by the embodiments of the present invention, secondary electrons generated by a pure electron beam acting on a sample to be tested can be detected.

Disclosed in the embodiments of the present invention is an electron microscope, comprising: an electron source, which is configured to generate an electron beam; a first beam conduit, which is configured to accelerate the electron beam; a second beam conduit, which is configured to accelerate the electron beam; a first detector, which is disposed between the first beam conduit and the second beam conduit and configured to receive secondary electrons generated by the electron beam acting on a sample to be tested; and a control electrode, which is disposed between the first detector and an optical axis of the electron beam and configured to change the direction of movement of backscattered electrons and the secondary electrons generated by the electron beam acting on said sample. By means of the electron microscope provided by the embodiments of the present invention, secondary electrons generated by a pure electron beam acting on a sample to be tested can be detected.

Prior to execution of primary correction, a first centering process, an in-advance correction of a particular aberration, and a second centering process are executed stepwise. In the first centering process and the second centering process, a ronchigram center is identified based on a ronchigram variation image, and is matched with an imaging center. In the in-advance correction and the post correction of the particular aberration, a particular aberration value is estimated based on a ronchigram, and the particular aberration is corrected based on the particular aberration value.