Abstract: There is provided a system and method of determining an overlay measurement between a first layer and a second layer of a specimen. The method includes acquiring a first image of a first structure on the first layer and a second image of a second structure on the second layer, obtaining one or more first regions of interest (ROIs) enclosing part of the first structure and one or more second ROIs enclosing part of the second structure, determining one or more first sets of symmetric sub-structures based on the first ROIs and one or more second sets of symmetric sub-structures based on the second ROIs, localizing a first center of symmetry (COS) based on a COS identified for each first set, and localizing a second COS based on a COS identified for each second set, and determining the overlay measurement based on the first COS and the second COS.

Abstract: There is provided a method, a non-transitory computer readable medium, and a system for measuring a pattern. The method can include (a) obtaining an electron image of an area of a sample, the area comprises the pattern, the electron image comprises multiple lines; each line comprises information obtained by moving an electron beam over a scan line; (b) generating a converted image by applying a noise reduction kernel on the electron image, the noise reduction kernel has a width that represents a number of consecutive lines of the electron image; the width is determined based on relationships between analysis results obtained when using noise reduction kernels of different widths; and (c) analyzing the converted image to provide a pattern measurement.

Abstract: There is provided a method, a non-transitory computer readable medium, and a system for measuring a pattern. The method can include (a) obtaining an electron image of an area of a sample, the area comprises the pattern, the electron image comprises multiple lines; each line comprises information obtained by moving an electron beam over a scan line; (b) generating a converted image by applying a noise reduction kernel on the electron image, the noise reduction kernel has a width that represents a number of consecutive lines of the electron image; the width is determined based on relationships between analysis results obtained when using noise reduction kernels of different widths; and (c) analyzing the converted image to provide a pattern measurement.

Abstract: A method for overlay monitoring including: obtaining a secondary electron image and a backscattered electron image of as area of the substrate in which an array of first structural elements are positioned at a surface of the substrate and a second array of second structural elements are positioned below the first array; determining locations of the first structural elements within the secondary electron image; defining regions of interest in the backscattered electron image, based on the locations of the first structural elements; processing pixels of the backscattered electron image that are located within the regions of interest to provide a backscattered electron representation of a second structural element; and calculating an overlay error based on location information regarding the second structural element within the backscattered electron representation of the second structural element and on location information regarding of at least one first structural element in the secondary electron image.

Abstract: A method, computer program product and a system for imaging an area that includes an upper surface and hole. The method may include acquiring, by a charged particle imager, a first image of a first type of electrons of the area while the charged particle imager is at a first configuration; acquiring, by the charged particle imager, a second image of the first type of electrons of the area and a first image of a second type of electrons of the area while the charged particle imager is at a second configuration that differs from the first configuration; and generating a hybrid image of the area based on (i) a first image of the first type of electrons of the upper surface, (ii) an inter-image offset, and (iii) a first image of the second type of electrons of the bottom of the hole.