A semiconductor structure and a method for managing semiconductor wafer stress are disclosed. The semiconductor structure includes a semiconductor wafer, a first stress layer disposed on and in contact with a backside of the semiconductor wafer, and a second stress layer on and in contact with the first stress layer. The first stress layer exerts a first stress on the semiconductor wafer and the second layer exerts a second stress on the semiconductor wafer that is opposite the first backside stress. The method includes forming a first stress layer on and in contact with a backside of a semiconductor wafer, and further forming a second stress layer on and in contact with the first stress layer. The first stress layer exerts a first stress on the semiconductor wafer and the second stress layer exerts a second stress on the semiconductor wafer that is opposite to the first stress.

An end mill inspection device, which inspects an end mill having a blade part formed in a curved convex shape or an arc shape, includes: an imaging data acquisition unit that acquires imaging data obtained by capturing an image of a blade part of the end mill by an imaging unit; a contour extraction unit that extracts the contour of the blade part on the basis of the imaging data acquired by the imaging data acquisition unit; and a curvature radius calculation unit that calculates a curvature radius of the contour on the basis of the contour of the blade part extracted by the contour extraction unit.

An end mill inspection device, which inspects an end mill having a blade part formed in a curved convex shape or an arc shape, includes: an imaging data acquisition unit that acquires imaging data obtained by capturing an image of a blade part of the end mill by an imaging unit; a contour extraction unit that extracts the contour of the blade part on the basis of the imaging data acquired by the imaging data acquisition unit; and a curvature radius calculation unit that calculates a curvature radius of the contour on the basis of the contour of the blade part extracted by the contour extraction unit.

A method for inspection of a target object, the method including irradiating a reference surface having a non-flat reference profile with radiation; determining reference response data based on detected radiation having interacted with the reference surface; irradiating a target object with radiation, the target object including a target surface having a non-flat target profile corresponding to the reference profile; determining inspection response data based on detected radiation having interacted with the target object; and determining at least one parameter of the target object based on the reference response data and the inspection response data. An alternative method; a control system for controlling an emitter system and a detector system; and an inspection system including a control system, an emitter system and a detector system, are also provided.

System and methods are provided for characterizing an internal surface of a lens using interferometry measurements. Sphere-fitting a distorted radius determines distorted pathlengths. Ray-tracing simulates refraction at all upstream surfaces to determine a cumulative path length. A residual pathlength is scaled by the group-index and rays are propagated based on the phase-index. After aspheric surface fitting, a corrected radius is determined. To estimate a glass type for the lens, a thickness between focal planes of the lens surfaces is determined using RCM measurements. Then, for both surfaces, the surface is positioned into focus, interferometer path length matching is performed, a reference arm is translated to stationary phase point positions for three wavelengths to determine three per-color optical thicknesses, and ray-tracing is performed. A glass type is identified by minimizing an error function based on optical parameters of the lens and parameters determined from known glass types from a database.

System and methods are provided for characterizing an internal surface of a lens using interferometry measurements. Sphere-fitting a distorted radius determines distorted pathlengths. Ray-tracing simulates refraction at all upstream surfaces to determine a cumulative path length. A residual pathlength is scaled by the group-index and rays are propagated based on the phase-index. After aspheric surface fitting, a corrected radius is determined. To estimate a glass type for the lens, a thickness between focal planes of the lens surfaces is determined using RCM measurements. Then, for both surfaces, the surface is positioned into focus, interferometer path length matching is performed, a reference arm is translated to stationary phase point positions for three wavelengths to determine three per-color optical thicknesses, and ray-tracing is performed. A glass type is identified by minimizing an error function based on optical parameters of the lens and parameters determined from known glass types from a database.

A device for measuring a curvature radius includes a sample stage configured to support a sample to be measured, a diffracted light array generation module configured to generate and emit a diffracted light array to the sample, and a detection and analysis module configured to receive a reflected light array emitted from the sample and to obtain the curvature radius of the sample according to a dimension of the received reflected light array. Also disclosed is a method for measuring the curvature radius.

A device for measuring a curvature radius includes a sample stage configured to support a sample to be measured, a diffracted light array generation module configured to generate and emit a diffracted light array to the sample, and a detection and analysis module configured to receive a reflected light array emitted from the sample and to obtain the curvature radius of the sample according to a dimension of the received reflected light array. Also disclosed is a method for measuring the curvature radius.

Methods, apparatus and systems for achieving efficient optical design are described. In one representative aspect, a method for optical design includes introducing a light source into the optical system. The light source emits illumination that is characterized as a point source, a collimated illumination, or a superposition of one or more point sources or one or more collimated illuminations. The light source is represented by a vector field comprising a plurality of vectors. The method also includes defining each optical surface of the optical system based on the vector field of the light source, tracing a plurality of rays that propagate from the light source, traverse through the optical system and reach a predetermined target or targets, and determining whether an illumination or an image characteristic at the predetermined target or targets meets preset design requirements.

Methods, apparatus and systems for achieving efficient optical design are described. In one representative aspect, a method for optical design includes introducing a light source into the optical system. The light source emits illumination that is characterized as a point source, a collimated illumination, or a superposition of one or more point sources or one or more collimated illuminations. The light source is represented by a vector field comprising a plurality of vectors. The method also includes defining each optical surface of the optical system based on the vector field of the light source, tracing a plurality of rays that propagate from the light source, traverse through the optical system and reach a predetermined target or targets, and determining whether an illumination or an image characteristic at the predetermined target or targets meets preset design requirements.