Abstract: A position detecting apparatus for optically observing an opaque mark formed on a transparent substrate to detect a position of the mark with a high degree of accuracy. The apparatus includes a detection optical system for forming a detected image of the mark, an illumination system for supplying an illuminating light to the mark through an objective lens of the detection optical system, projection means arranged to face the detection optical system through the substrate and forming a conjugate position to the mark, and reflecting means which is settable substantially at the conjugate position. The image of the mark can be detected as either a bright image or a dark image under the conditions where there are a sufficient contrast between the mark and the background and a uniform background density. The shape of the mark and the arrangement of patterns around the mark can be determined as desired.

Abstract: The structure of an alignment apparatus is as follows: The illuminating areas of the two laser beams for the use of alignment, which are irradiated onto a diffraction grating on a substrate and a diffraction grating mark on a fiducial member, are relatively driven by a field diaphragm and a diaphragm member. A photoelectric detector receives the interference light generated from a first portion in the area on the above-mentioned diffraction mark where the two laser beams intersect following the above-mentioned relative driving, and receives the interference light generated from a second portion in the aforesaid area. A main control system calculates the intersecting angles or rotational error of the two laser beams on the basis of the phase difference of the detection signals from the aforesaid photoelectric detector. The intersecting angles or rotational error is corrected by allowing the parallel flat glasses, which are arranged on the light path, to be slanted.

Abstract: In a position detecting apparatus having an object optical system, two beams are generated for irradiating a diffraction grating formed on an object from two directions at a predetermined intersect angle for forming an interference fringe, the beams passing through a pupil plane of the object optical system spaced apart a predetermined distance from each other. An opto-electric detector receives diffracted light from the grating via the object optical system and outputs a detection signal, and the position of the object is determined on the basis of the detection signal. An adjustable optical member provided in a light path between an optical source and the object changes incident angles at which the two beams are incident on the grating while keeping the intersect angle between the two beams substantially constant.

Abstract: A position detecting apparatus for optically observing an opaque mark formed on a transparent substrate to detect a position of the mark with a high degree of accuracy. The apparatus includes a detection optical system for forming a detected image of the mark, an illumination system for supplying an illuminating light to the mark through an objective lens of the detection optical system, projection means arranged to face the detection optical system through the substrate and forming a conjugate position to the mark, and reflecting means which is settable substantially at the conjugate position. The image of the mark can be detected as either a bright image or a dark image under the conditions where there are a sufficient contrast between the mark and the background and a uniform background density. The shape of the mark and the arrangement of patterns around the mark can be determined as desired.

Abstract: An aligning device for aligning a substrate with a predetermined point on the basis of a detection signal from a photoelectric detector uses interference light generated by light diffracted from a diffraction grating. A calculating device calculates at least one of a crossing angle of two coherent beams irradiating the grating and the rotational error of a crossing line between a plane containing principal rays of the beams and the surface of the substrate, with respect to the direction of arrangement of the grating, based on the phase difference between detection signals of the photoelectric detector corresponding to interference light generated from different portions of the crossing area. The output of the calculating device may be used to adjust the crossing angle and/or to correct the rotational error.

Abstract: There is disclosed an apparatus for transferring a reticle pattern onto a wafer, in which the reticle and the wafer are mutually aligned by irradiating an alignment mark of the wafer with light beams and detecting the optical information from the mark. Depending on the shape of the wafer mark, suitably selected is a first light beam passing through the center of entrance pupil of an objective optical system, or a pair of second light beams passing through the entrance pupil point-symmetrically with respect to its center. The wafer mark consists of a main mark and an auxiliary mark, and the main mark contains a diffraction grating pattern. The second paired light beams and the main mark are used for determining the positional error within an integral fraction of the pitch of the diffraction grating pattern, and the first light beam and the auxiliary mark are used for determining the positional error of an integral multiple of the pitch of the diffraction grating pattern.

Abstract: An alignment apparatus is provided with a first beam receiving device arranged to receive an interference beam which is produced at a diffraction grating of a substrate as a result of illumination with a pair of beams which intersect each other on the substrate, and a second beam receiving device arranged to receive a reference beam which is produced by the interference between regularly reflected beams of the pair of beams occurring on the substrate, wherein the positional offset of the substrate is obtained on the basis of a comparison between the output signal of the first beam receiving device and the output signal of the second beam receiving device. Since a beam transmitting path for transmitting a measurement beam is substantially common to a beam transmitting path for a reference beam, even if the fluctuations of air occur, both the measurement beam and the reference beam substantially equally reflect the influence of the fluctuations, whereby it is possible to cancel the same.