A semiconductor measurement apparatus may include an illumination unit configured to irradiate light to the sample, an image sensor configured to receive light reflected from the sample and output multiple interference images representing interference patterns of polarization components of light, an optical unit in a path through which the image sensor receives light and including an objective lens above the sample, and a control unit configured to obtain, by processing the multi-interference image, measurement parameters determined from the polarization components at each of a plurality of azimuth angles defined on a plane perpendicular to a path of light incident to the image sensor. The control unit may be configured to determine a selected critical dimension to be measured from a structure in the sample based on measurement parameters. The illumination unit and/or the optical unit may include a polarizer and a compensator having a ? wave plate.

A method for determining a focal length of a particle in a medium, wherein the method comprises: providing a sample; emitting a coherent light beam to irradiate the sample, wherein a first part of the light beam is scattered by the particle; recording an interference image; computing for a set of positions an electric field from the interference image; generating a representation comprising, for each of said positions, an intensity value of the coherent light beam calculated from the computed electric field; finding two positions, a first of which lies in the sample, a second of which lies in the beam direction behind or in front of said first position; and determining the focal length from the two found positions.

In an alignment sensor of a lithographic apparatus, position sensing radiation is delivered to a target (P1). After reflection or diffraction from the target, position sensing radiation is processed to determine a position of the target. Reference radiation interferes with the position sensing radiation) while a relative phase modulation is applied between the reference radiation and the position sensing radiation. The interfering radiation includes a time-varying component defined by the applied phase modulation. The interfering radiation is delivered to two photodetectors in such a way that each photodetector receives said time-varying component in anti-phase to that received at the other photodetector. A difference signal (i(t)) from said photodetectors contains an amplified, low noise version of said time-varying component. This is used in determining the position of the target. Mode matching enhances interference. Surface scattered radiation is rejected.

Systems and methods are described herein for a self-referencing interferometer. The interferometer can comprise an improved spatial phase shifter that reduces the number of components, size and complexity of the spatial phase shifter and maintains a common path for a combined reference beam and signal beam. The self-referencing interferometer further comprises a single mode fiber shunt for filtering the reference beam and further reducing the size of the interferometer. The angle of the reference beam can be tilted before being recombined with the single beam which further simplifies the spatial phase shifting component of the interferometer.

A holographic interferometer, comprising: at least one imaging device capturing an interference pattern created by at least two light beams; and at least one aperture located in an optical path of at least one light beam of the at least two light beams; wherein the at least one aperture is located away from an axis of the at least one light beam, thus transmitting a subset of the at least one light beam collected at an angle range.

An optical distance measuring apparatus includes: a scanning element scanning a coherent irradiation light from a light source and sending it to an object under measurement; a photo detector receiving the irradiation light modulated by being passed through the object under measurement in accordance with the scanning, and performing photoelectric conversion on the irradiation light; and a measuring unit obtaining phase information of the object under measurement based on a signal photoelectrically converted by the photo detector and a signal to be a reference for the scanning by the scanning element, and obtaining a measurement value regarding the object under measurement based on the phase information.

Stackable and/or nestable box having a bottom wall and a side wall which rises from the bottom wall and which is defined by side panels, a front panel and a rear panel. The side panels include at least one recessed portion which is recessing from the containment volume and at least one portion protruding towards the containment volume. The box is configured to be nested within another box and to be stacked with other boxes or other containers with dimensions compatible with, or close to, the dimensions of box.

An interferometer apparatus comprises an adjustable birefringent device configured to receive an input radiation and produce corresponding replicas having reciprocally orthogonal polarizations and delayed from each other by an adjustable time delay. The birefringent device also introduces an additional time delay between the replicas. The interferometer apparatus also comprises a compensation optical device optically coupled to the adjustable birefringent device and configured to have a respective structural thickness and respective ordinary and extraordinary refractive indexes to introduce a compensation time delay between the replicas having a sign opposite to a sign of the additional time delay.

An optical position-measuring device includes a scanning unit and a material measure that is movable relative thereto in a measuring direction. The scanning unit includes a splitting device and an optoelectronic detector arrangement. The splitting device is configured to separate sub-beams incident thereon as a function of wavelength. The splitting device is configured as an asymmetrical interferometer that includes two interferometer arms having different optical path lengths, within which the sub-beams propagate between splitting and recombination until the recombined sub-beams arrive at the detector arrangement. The optical position-measuring device is configured to generate a plurality of phase-shifted scanning signals indicative of a relative position of the scanning unit and of the material measure, wherein phase relations of the generated phase-shifted scanning signals are wavelength-dependent.

The present disclosure relates to a method for detecting focal plane based on a grating Talbot effect, the function of which is to detect position of a silicon wafer in a photolithography machine in real time so as to implement an adjustment of leveling and foal plane of the silicon wafer in a high resolution. The detection system utilizes a phase change of self-image generated by a grating Talbot effect caused by defocusing of the silicon wafer, so as to accomplish the detecting for focal plane of the silicon wafer in the photolithography machine in a high resolution: if the silicon wafer is at a focal plane, the imaged wavefront by the grating is a planar wavefront; and when the silicon wafer is defocused, the imaged wavefront is a spherical wavefront. Such a detection system has a simple structure, a higher anti-interference capability and a perfect adaption of the process.