The methods and systems disclosed here leverage currently available reliable top down imaging techniques used by SEMs and use computational methods to synthesize accurate 3D profiles of features of high aspect ratio structures in a device. Radial cross-sectional profiles obtained from different locations along the lateral direction at different heights/depths are stitched together to create one composite 3D profile of the HAR feature.

According to one aspect of the present invention, a multiple electron beam inspection apparatus includes a reference image generation circuit generating reference images corresponding to the secondary electron images, in accordance with an image generation characteristic of a secondary electron image by irradiation of one beam; and a correction circuit generating corrected reference images in which, on the basis of deviation information between a figure pattern of the secondary electron image by irradiation of the one beam of the multiple primary electron beams and a figure pattern of a secondary electron image by irradiation of another beam different from the one beam of the multiple primary electron beams, a shape of a figure pattern of a reference image corresponding to the figure pattern of the secondary electron image by the irradiation of the another beam in the reference images is corrected.

The invention relates to a method of determining an aberration of a charged particle microscope. The method comprises a step of providing a charged particle microscope that is at least partly operable by a user. Then, a set of image data is obtained with said charged particle microscope. The image data is processed to determine an aberration of said charged particle microscope. According to the invention, said set of image data is actively obtained by a user. In particular, the image data may be obtained during normal operation of the microscope by a user, which may include navigating and/or focusing of the microscope. Thus, the set of image data is acquired by said user, and not by the controller thereof. This allows background processing of an aberration, and aberration correction during use of the charged particle microscope. The invention further relates to a charged particle microscope incorporating the method.

The invention relates to a method for inspecting a sample with an assembly comprising a scanning electron microscope (SEM) and a light microscope (LM). The assembly comprises a sample holder for holding the sample. The sample holder is arranged for inspecting the sample with both the SEM and the LM, preferably at the same time. The method comprising the steps of: capturing a LM image of the sample in its position for imaging with the SEM; determining a position and dimensions of a region of interest in or on the sample using the LM image; determining values to which the SEM parameters need to be set to image the sample at a desired resolution; and capturing a SEM image of the region of interest, preferably using the first electron beam exposure of said region of interest.

An improved charged particle beam inspection apparatus, and more particularly, a particle beam inspection apparatus including an improved alignment mechanism is disclosed. An improved charged particle beam inspection apparatus may include a second electron detection device to generate one or more images of one or more beam spots of the plurality of secondary electron beams during the alignment mode. The beam spot image may be used to determine the alignment characteristics of one or more of the plurality of secondary electron beams and adjust a configuration of a secondary electron projection system.

A calibration method for calibrating the position error in the point of interest induced from the stage of the defect inspection tool is achieved by controlling the deflectors directly. The position error in the point of interest is obtained from the design layout database.

A distortion measurement method for an electron microscope image includes: loading a distortion measurement specimen having structures arranged in a lattice to a specimen plane of an electron microscope or a plane conjugate to the specimen plane in order to obtain an electron microscope image of the distortion measurement specimen; and measuring a distortion from the obtained electron microscope image of the distortion measurement specimen.

Disclosed are methods for sensing conditions of an electron microscope system and/or a specimen analyzed thereby. Also disclosed are sensor systems and electron microscope systems able to sense system conditions, and/or conditions of the specimen being analyzed by such systems. In one embodiment, a sparse dataset can be acquired from a random sub-sampling of the specimen by an electron beam probe of the electron microscope system. Instrument parameters, specimen characteristics, or both can be estimated from the sparse dataset.

Methods and systems for quantifying and correcting for non-uniformities in images used for metrology operations are disclosed. A metrology area image of a wafer and a design clip may be used. The metrology area image may be a scanning electron microscope image. The design clip may be the design clip of the wafer or a synthesized design clip. Tool distortions, including electron beam distortions, can be quantified and corrected. The design clip can be applied to the metrology area image to obtain a synthesized image such that one or more process change variations are suppressed and one or more tool distortions are enhanced.

The disclosure relates to a method of aligning a charged particle beam apparatus, comprising the steps of providing a charged particle beam apparatus in a first alignment state; using an alignment algorithm, by a processing unit, for effecting an alignment transition from said first alignment state towards a second alignment state of said charged particle beam apparatus; and providing data related to said alignment transition to a modification algorithm for modifying said alignment algorithm in order to effect a modified alignment transition.