An optical measurement apparatus includes a light source unit generating and outputting light, a polarized light generating unit generating polarized light from the light, an optical system generating a pupil image of a measurement target, using the polarized light, a self-interference generating unit generating multiple beams that are split from the pupil image, and a detecting unit detecting a self-interference image generated by interference of the multiple beams with each other.

An illumination apparatus configured to provide illumination while changing a spectrum of light from a light source includes a wavelength variable unit configured to change a spectrum of irradiating light, and an optical system configured to irradiate the wavelength variable unit with the light from the light source. The wavelength variable unit is disposed so that an incident surface of the wavelength variable unit on which the light emitted from the optical system is incident is tilted with respect to a plane perpendicular to an optical axis of the optical system.

An optical measuring system is used to reproduce a target wavefront of an imaging optical production system when an object is illuminated with illumination light. The optical measuring system comprises an object holder displaceable by actuator means and at least one optical component displaceable by actuator means. Within the scope of the target wavefront reproduction, a starting actuator position set (X.sub.0), in which each actuator is assigned a starting actuator position, is initially specified. An expected design wavefront (W.sub.D) which approximates the target wavefront and which the optical measuring system produces as a set wavefront is determined. A coarse measurement of a starting wavefront (W.sub.0) which the optical measuring system produces as actual wavefront after actually setting the starting actuator position set (X.sub.0) is carried out. Then, the object holder is adjusted by actuator means until a coarse target wavefront (W.sub.1) is obtained for a coarse actuator position set (X.sub.1) in the case of a minimum wavefront deviation between the actual wavefront and the design wavefront (W.sub.D). Said coarse target wavefront is then subjected to a fine measurement and the at least one optical component is displaced until a fine target wavefront (W.sub.2) is obtained for a fine actuator position set (X.sub.2) in the case of a minimum deviation between the actual wavefront setting-in in that case and the design wavefront (W.sub.D). This reproduction method allows wavefront deviations of the optical measuring system generated by way of targeted misalignment to provide a good approximation of corresponding deviations of the optical production system.

A system of measuring an image of a pattern in a high NA scanning-type extreme ultra-violet (EUV) mask is disclosed. The system may include a light source generating an EUV light; an toroidal mirror; an flat mirror allowing light, which is reflected by the toroidal mirror, to be incident into the mask; an beam splitter; a light detection part; an anamorphic zone-plate lens focusing a transmitted portion of a light emitted from the beam splitter on the mask; a stage; and an anamorphic photo sensor, which is configured to measure an energy of a reflected portion of the coherent EUV light, is composed of a detector array, and has different sizes from each other in horizontal and vertical directions of an incidence surface of the detector array.

A metrology system comprises a radiation source, an optical element, first and second detectors, an integrated optical device comprising a multimode waveguide, and a processor. The radiation source generates radiation. The optical element directs radiation toward a target to generate scattered radiation from the target. The first detector receives a first portion of the scattered radiation and generates a first detection signal based on the received first portion. The multimode waveguide interferes a second portion of the scattered radiation using modes of the multimode waveguide. The second detector receives the interfered second portion and generates a second detection signal based on the received interfered second portion. The processor receives the first and second detection signals. The processor analyzes the received first portion, the received interfered second portion, and a propagation property of the multimode waveguide. The processor determines the property of the target based on the analysis.

An overlay metrology system may illuminate overlay targets sample with a dipole pair of illumination beams, generate a first set of metrology data associated with two or more cells having nonzero offset values from a first set of the overlay targets, determine overlay measurements for the first set of overlay targets, determine effective stack heights representative of an effective distance between layers at the locations of the first set of the overlay targets, generate a second set of metrology data from a second set of the overlay targets, determine the effective stack heights at locations of the second set of the overlay targets based on the first effective stack heights, and determine overlay measurements for the second set of overlay targets based on the effective stack heights at the locations of the second set of the overlay targets and the second set of metrology data.

An overlay measurement apparatus that can quickly measure an overlay error between layers with a large height difference is provided. The overlay measurement apparatus measures an error between a first overlay mark and a second overlay mark formed in a pair on different layers of a wafer. The overlay measurement apparatus includes an imaging system configured to acquire alignment images of a pair of first and second overlay marks at a plurality of focus positions, and a controller communicatively coupled to the imaging system. The overlay measurement apparatus can rapidly and accurately measure an overlay error between layers with a large height difference.

An optical metrology system may include an overlay metrology tool for characterizing an overlay target on a sample, where the overlay target includes first-direction periodic features in a first set of layers of the sample, and second-direction periodic features in a second set of layers of the sample. The overlay metrology tool may simultaneously illuminate the overlay target with first illumination beams and second illumination beams and may further generate images of the overlay target based on diffraction of the first illumination beams and the second illumination beams by the overlay target, where diffraction orders of the first illumination beams contribute to resolved image formation of only the first-direction periodic features, and where diffraction orders of the second illumination beams contribute to resolved image formation of only the second-direction periodic features. The system may further generate overlay measurements along the first and second measurement directions based on the images.

A lens system including: a first asphercal axicon lens element having a first refractive surface and a second refractive surface; a second aspherical axicon lens element having a third refractive surface similar to the second refractive surface and a fourth refractive surface similar to the first refractive surface, and an aperture stop located between the first asphercal axicon lens element and the second aspherical axicon lens element. The first aspherical axicon lens element and second aspherical axicon lens are mutually oriented such that the second refractive surface and third refractive surface are mutually facing. The first aspherical axicon lens element and the second aspherical axicon lens element are configured to minimize chromatic aberration for at least a spectral range of radiation relayed by the lens system.

A system of measuring an image of a pattern in a high NA scanning-type extreme ultra-violet (EUV) mask is disclosed. The system may include a light source generating an EUV light; an toroidal mirror; an flat mirror allowing light, which is reflected by the toroidal mirror, to be incident into the mask; an beam splitter; a light detection part; an anamorphic zone-plate lens focusing a transmitted portion of a light emitted from the beam splitter on the mask; a stage; and an anamorphic photo sensor, which is configured to measure an energy of a reflected portion of the coherent EUV light, is composed of a detector array, and has different sizes from each other in horizontal and vertical directions of an incidence surface of the detector array.