A method of processing a wafer is provided. The method includes providing a reference plate below the wafer. The reference plate includes a reference pattern. The reference plate is imaged to capture an image of the reference pattern by directing light through the wafer. A first pattern is aligned using the image of the reference pattern. The first pattern is applied to a working surface of the wafer based on the aligning.

Systems, methods, and apparatus are provided for determining overlay of a pattern on a substrate with a mask pattern defined in a resist layer on top of the pattern on the substrate. A first grating is provided under a second grating, each having substantially identical pitch to the other, together forming a composite grating. A first illumination beam is provided under an angle of incidence along a first horizontal direction. The intensity of a diffracted beam from the composite grating is measured. A second illumination beam is provided under the angle of incidence along a second horizontal direction. The second horizontal direction is opposite to the first horizontal direction. The intensity of the diffracted beam from the composite grating is measured. The difference between the diffracted beam from the first illumination beam and the diffracted beam from the second illumination beam, linearly scaled, results in the overlay error.

Disclosed herein is s computer-based method for obtaining and analyzing multi-die scan data of a patterned wafer. The method includes sequentially implementing an operation of scanning a respective plurality of sets of slices on a wafer, and, per each slice segment in a multiplicity of slice segments in the plurality of sets of slices, an operation of performing die-to-multi-die (D2MD) analysis of scan data of the slice segment in order to detect defects in the slice segment. Each set of slices may constitute a subset of the totality of slices on the respective die-column. Sets scanned in a same implementation are analogous to one another, thereby facilitating—in the die-to-multi-die analysis of scan data of a slice segment—taking into account, as reference, scan data of areas on other die-columns, which were scanned in the same implementation.

A semiconductor wafer inspection method is provided. The semiconductor wafer inspection method includes: providing a wafer with target and reference dies; obtaining a candidate image of a first region of the target die and a reference image of a second region of the reference die; performing an imaging process on the candidate image to obtain a high resolution candidate image including sub-pixels for each pixel of the candidate image; performing the imaging process on the reference image to obtain a high resolution reference image including sub-pixels for each pixel of the candidate image; shifting the high resolution reference image in units of the sub-pixels; obtaining a difference image based on a difference between the high resolution candidate image and the high resolution reference image; and detecting whether a defect signal generated based on the difference image exceeds a threshold value.

Systems, methods, and apparatus are provided for determining overlay of a pattern on a substrate with a mask pattern defined in a resist layer on top of the pattern on the substrate. A first grating is provided under a second grating, each having substantially identical pitch to the other, together forming a composite grating. A first illumination beam is provided under an angle of incidence along a first horizontal direction. The intensity of a diffracted beam from the composite grating is measured. A second illumination beam is provided under the angle of incidence along a second horizontal direction. The second horizontal direction is opposite to the first horizontal direction. The intensity of the diffracted beam from the composite grating is measured. The difference between the diffracted beam from the first illumination beam and the diffracted beam from the second illumination beam, linearly scaled, results in the overlay error.

An electron optical system includes an electromagnetic lens configured to include a yoke, and refract an electron beam passing through the yoke by generating a magnetic field, and a shield coil disposed along the inner wall of the yoke, and configured to reduce a leakage magnetic field generated by the electromagnetic lens.

A method of pattern alignment is provided. The method includes identifying a reference pattern positioned below a working surface of a wafer. The wafer is exposed to a first pattern of actinic radiation. The first pattern is a first component of a composite pattern. The first pattern of actinic radiation is aligned using the reference pattern. The wafer is exposed to a second pattern of actinic radiation. The second pattern is a second component of the composite pattern and exposed adjacent to the first pattern. The second pattern of actinic radiation is aligned with the first pattern of actinic radiation using the reference pattern.

The invention relates to a method for assessing contrasts on surfaces (2), in particular for optically identifying structured and/or pictorial surfaces (2), e.g. of paintings (1) or sculptures, said method being simple to use independently of the location and safe. For this purpose, the method involves the steps of—focusing a camera (5) onto a prominent image dot (3) on the surface, —creating at least two images of a recognizable, high-contrast area of the image dot (3), —storing the image having the greatest depth of detail as a reference image.

Systems and processes are provided for measuring carbon deposits on an engine. In some examples, a light source can be transmitted through a viewing window of an engine onto an area of an internal surface of the engine and reflected back through the viewing window and detected using an optical sensor. A topography of the area can be determined based, at least in part, on the reflected light source detected by the optical sensor and used to determine whether carbon deposits have increased, decreased, or remained constant on the area.

A system and method for defect detection in a hole array on a substrate is disclosed herein. In one embodiment, a method for defect detection in a hole array on a substrate, includes: scanning a substrate surface using at least one optical detector, generating at least one image of the substrate surface; and analyzing the at least one image to detect defects in the hole array on the substrate surface based on a set of predetermined criteria.