Abstract: A method of measuring information related to an object, includes the steps of measuring a change of a measurement error with respect to time, and determining the frequency of measurements for measuring the measurement error, to be done during a measurement period, on the basis of the change in measurement error. Then, in the measurement period, a measured value is corrected by using a latest measurement error.

Abstract: A displacement measuring method for measuring displacement of an object to be examined is disclosed, wherein light which contains two components having a small difference in frequency is separated into a first light of a firs wavelength and a second light of a second wavelength, having different frequencies. First light beam of the first light and a second light beam of the second light interfere with each other, wherein at least one of the first and second light beams is directed via the object, whereby a first light beat signal is produced. Third light beam of the first light and a fourth light beam of the second light interfere with each other, wherein at least one of the third and fourth light beams is directed via the object, whereby a second light beat signal having a predetermined phase difference as compared with the first light beat signal is produced.

Abstract: A device and method for measuring the positional deviation between a plurality of diffraction gratings formed on the same object include an illumination optical system for illuminating the plurality of diffraction gratings with a light beam, the illumination by the optical system generating a plurality of diffracted light beams from the plurality of diffraction gratings, an interference optical system for forming at least one interference light beam from the plurality of diffracted light beams, a detector for detecting the at least one interference light beam, the result of the detection serving as the basis for measuring the positional deviation between the plurality of diffraction gratings, and a measuring portion for measuring the relative positional relation between the illumination optical system and the plurality of diffraction gratings.

Abstract: A position detection apparatus and method detects the relative positional relationship between first and second objects facing each other in a facing direction. First, second and third marks each serving as a physical optical element are provided on the first object, while a fourth mark serving as a physical optical element is provided on the second object. A light projector projects light onto the first and second objects A light detector detects a first light beam diffracted by the first mark and reflected by the second object, a second light beam diffracted by the second mark and reflected by the second object, and a third light beam diffracted by the third and fourth marks. A first position detector detects the relative positional relationship between the first and second objects in the facing direction based on signals representing the first and second light beams from the light detector.

Abstract: Apparatus for detecting a positional deviation of two diffraction gratings of each of first and second pairs of diffraction gratings formed on a substrate, by utilizing an optical heterodyne interference method.

Abstract: A deviation detecting system for detecting a relative positional deviation between first and second diffraction gratings, includes a light source, an illuminating device for projecting first and second light beams from the light source, having different directions of polarization, onto the first and second diffraction gratings along different directions, a first signal detecting device for detecting a first interference light signal from the first diffraction grating, being based on a combination of diffraction light of the first light beam and diffraction light of the second light beam, a second signal detecting device for detecting a second interference light signal from the second diffraction grating, being based on a combination of diffraction light of the first light beam and diffraction light of the second light, a first phase difference detecting device for detecting a phase difference between the first and second interference light signals and, a second phase difference detecting device for producing

Abstract: A method and device for measuring the relative displacement between first and second diffraction gratings includes an interference optical system forming first and second interference rays of light from light diffracted from the first and second diffraction gratings and separating the first and second interference rays of light on the basis of the difference in their direction of polarization, a first detector for detecting the first interference ray of light to generate a first detection signal, a second detector for detecting the second interference ray of light to generate a second detection signal, and signal processing section for detecting the phase difference between the first and second detection signals and for determining the relative displacement between the first and second diffraction gratings on the basis of the phase difference.

Abstract: A method and apparatus for measuring the relative positional deviation between first and second diffraction gratings formed on an object includes determining the relative positional deviation of the first and second diffraction gratings while detecting and correcting an error produced in relation to detection of the positional deviation of the first and second diffraction gratings.

Abstract: An X-ray mask structure for X-ray lithography comprises a pattern, an X-ray transmissive film for holding the pattern, and a frame for supporting the X-ray transmissive film, wherein a light-scattering prevention film is formed on at least a part of the surface of the X-ray transmissive film and/or of the pattern, and the light scattering prevention film may be a flat coating film formed on at least one of the top face and the back face of the X-ray transmissive film and having a refractive index substantially equal to the refractive index of the X-ray transmissive film. A process for producing the X-ray mask structure comprises steps of forming a flat coating film having a refractive index substantially the same as that of the X-ray transmissive film on at least one of the top face and the back face of the X-ray transmissive film, and forming a pattern at least on the top face of the X-ray transmissive film.

Abstract: A deviation detecting system for detecting a rotational deviation of an object, includes a pattern formed on the object and having a periodicity, a light source for providing light, a detecting device for projecting the light from the light source onto the pattern and for detecting at least two diffraction lights from the pattern with a predetermined detection plane, and a determining device for determining a rotational deviation of the object with respect to a predetermined axis, on the basis of the positions of incidence of the diffraction lights upon the detection plane as detected through the detection by the detecting device.

Abstract: A first Savart plate and an object to be measured are arranged on the light path of a Zeeman light source. The object to be measured is constructed of a diffraction grating on a mask and a diffraction grating on a wafer. A second Savart plate, a deflection plate and a photoelectric detector are sequentially arranged in the light path for the diffracted beams from the measured object. The output of the photoelectric detector is connected to a phase-difference unit to detect the phase difference between two beat signals. Herein, the light is split into two beams by the Savart plate. After a diffraction is caused by the diffraction gratings, thereafter, the beams are re-synthesized by the Savart plates. The two beams travel on the same light path, thereby improving a measurement accuracy.

Abstract: An optical element comprised of a plurality of polarizing beam splitters is provided on the optical path of a two-frequency linearly polarized laser beam source, and the optical element divides a light beam from the two-frequency linearly polarized laser beam source into two light beams, whereafter these two light beams are incident on diffraction gratings provided on a mask and a wafer, respectively. A pair of mirrors are provided vertically above the mask, and a pair of lenses, a pair of polarizing plates and a pair of photoelectric detectors are arranged in succession in the directions of reflection of the pair of mirrors. The outputs of the two photoelectric detectors become beat signals, and the phase difference between these beat signals is measured, whereby the alignment of the mask and wafer is effected. Since the optical element is comprised of a plurality of polarizing beam splitters, leak-in light included in each light beam is reduced.

Abstract: A position detector includes a diffraction grating provided on the surface of an object, an illumination system for illuminating the diffraction grating, a detection system for detecting diffracted light diffracted from the diffraction grating, and a processing system for detecting positional information relating to the object. The illumination system emits a first pair of beams which are diffracted by the diffraction grating and interfere with each other, and emits a second pair of beams which are diffracted by the diffraction grating and also interfere with each other. The first pair of beams are incident upon the diffraction grating along a plane extending in a first direction in which the diffraction grating extends. The second pair of beams are incident upon the diffraction grating along a plane extending in a second direction in which the diffraction grating extends. The first and second directions are different from a grating line direction.

Abstract: Disclosed is a method and apparatus for measuring a relative positional deviation between a first pattern and a second pattern, printed on an article such as a semiconductor wafer at different moments, the measurement being based on detection of interference of diffraction lights from at least one of the first and second printed patterns.

Abstract: A measuring arrangement includes forming first and second pairs of light beams each having a low frequency light beam and a high frequency light beam. Both pairs of light beams generate beat signals of the same frequency. The low frequency light beam of either pair and the high frequency of the other pair pass through a predetermined optical path to cause phase changes in the same direction. Beat signals are generated by superposing the first and second beam pair to provide measurement information on the phase changes.