A light source projects a light beam. An interferometer includes a splitting unit that splits the light beam. The interferometer generates interference beams with the respective split light beams. Each of the interference beam is generated by interference between a measurement beam radiated toward the measurement target and reflected at the measurement beam and a reference beam passing through an optical path. A light-receiving unit receives the interference beams. A processor calculates a distance to the measurement target by associating at least one detected peak with at least one of the spots in accordance with a mirror surface mode or a rough surface mode. The optical path length difference is made different among the split light beams. In the mirror surface mode, the processor uses a distance calculated based on a peak corresponding to a spot for which the optical path length difference is shortest.

There is provided a system and method of a method of detecting a local shape deviation of a structural element in a semiconductor specimen, comprising: obtaining an image comprising an image representation of the structural element; extracting, from the image, an actual contour of the image representation; estimating a reference contour of the image representation indicative of a standard shape of the structural element, wherein the reference contour is estimated based on a Fourier descriptor representative of the reference contour, the Fourier descriptor being estimated using an optimization method based on a loss function specifically selected to be insensitive to local shape deviation of the actual contour; and performing one or more measurements representative of one or more differences between the actual contour and the reference contour, the measurements indicative of whether a local shape deviation is present in the structural element.

Systems and methods for measuring a surface topography of a semiconductor chip are disclosed. A disclosed system comprises a light source configured to provide low coherent light to a first beam splitter, a scanner configured to use the low coherent light reflected from the first beam splitter to scan positions on a surface of a semiconductor chip, a second beam splitter configured to receive reflected signals from the positions on the surface of the semiconductor chip, a detector configured to detect interference signals from a first output of the second beam splitter, wherein each of the interference signals corresponds to a respective one of the positions, and a spectrometer configured to detect spectrum signals from a second output of the second beam splitter, wherein each of the spectrum signals corresponds to the respective one of the positions.

A method for optical inspection includes illuminating a patterned polymer layer on a semiconductor wafer with optical radiation over a range of infrared wavelengths, measuring spectral properties of the optical radiation reflected from multiple points on the patterned polymer layer over the range of infrared wavelengths, and based on the measured spectral properties, computing a complex refractive index of the patterned polymer layer.

There is provided a system and method of a method of detecting a local shape deviation of a structural element in a semiconductor specimen, comprising: obtaining an image comprising an image representation of the structural element; extracting, from the image, an actual contour of the image representation; estimating a reference contour of the image representation indicative of a standard shape of the structural element, wherein the reference contour is estimated based on a Fourier descriptor representative of the reference contour, the Fourier descriptor being estimated using an optimization method based on a loss function specifically selected to be insensitive to local shape deviation of the actual contour; and performing one or more measurements representative of one or more differences between the actual contour and the reference contour, the measurements indicative of whether a local shape deviation is present in the structural element.

Reflectometer, spectrophotometer, ellipsometer, and polarimeter systems having a supercontinuum laser source of coherent electromagnetic radiation over a range of between 400 nm to between 4400 nm and 18000 nm, and another source of wavelengths to provide between 400 nm and as high as at least 50000 nm; a stage for supporting a sample and a detector of electromagnetic radiation, wherein the source provides a beam of electromagnetic radiation which interacts with a sample and enters a detector system optionally incorporating a wavelength modifier, where the detector system can be functionally incorporated with combinations of gratings and/or combination dichroic beam splitter-prisms, which can be optimized as regards wavelength dispersion characteristics to direct wavelengths in various ranges to various detectors that are well suited to detect them.

A system (1) for generating a signal from a surface (22) having a speed V in a direction U, comprising: a light source (2) emitting a Gaussian light beam along a first optical path (11); a sensor (3) able to evaluate the effects of the electromagnetic interference of the first beam; a means (2′, 4) for generating a second Gaussian light beam along a second optical path (12); a second sensor (3′) able to evaluate the effects of electromagnetic interference of the second beam; a focusing lens (5, 6) located on the first and/or the second optical path (11, 12), focusing the light beam at a distance f and defining an upstream optical path (11′, 12′); and a means (4′, 7) for routing the second beam able to redirect the second path (12′) in the direction of the first path (11′).

A method for obtaining the profile of the outer surface (22) of a medium (21) having a median plane (23) comprising the following steps: obtaining two time signals A and B (1002), for, at each instant, a same geometrical target on a readout line of the outer surface (22); determining at least one Doppler frequency (2001) associated with each time signal A and B; sampling each time signal A and B (2002) at a frequency greater than 2 times the Doppler frequency to obtain a payload signal; determining an envelope (2004) of the payload signal of each signal A and B; performing a relative combination between the envelopes of each signal A and B (3001) to obtain a monotonic and bijective function F; and determining the profile of the outer surface (3002) using a calibration of the function F.

An ellipsometer includes a first separation unit configured to separate a first reflected light into two reflected lights, a first polarizing optical element configured to separate each of the two reflected lights into two linearly polarized lights, a first interference device configured to form an interference fringe by allowing components of the two linearly polarized lights to interfere with each other, a second separation unit configured to separate a second reflected light into two reflected lights, a second polarizing optical element configured to separate each of the two reflected lights into two linearly polarized lights, and a second interference device configured to form an interference fringe by allowing components of the two linearly polarized lights to interfere with each other.

Methods are proposed to improve axial resolution in optical coherence tomography (OCT). In one aspect, the method comprises: obtaining a k-space interferogram of an OCT spectral image; uniformly reshaping the k-space interferogram to a quasi-stationary interferogram by extracting a source envelope; fitting a spectral estimation model to the quasi-stationary interferogram; and calculating an axial depth profile using the fitted spectral estimation model.