Abstract: An alignment device comprising a movable table, a plurality of movable support means for movably supporting the movable table, means for reading a recognition mark, and a control means for controlling the drive of the movable support means based on information from the recognition means, wherein each movable support means comprises means having a pair of support blocks each provided to be able to contact/separate with/from the movable table and a pair of piezoelectric actuators each provided with expansible first, second and third piezoelectric elements connected to a support block and extending in each direction, and being capable of walking operation relative to the movable table by the operations of the respective piezoelectric actuators. An alignment accuracy up to a nanometer level can be attained, and the alignment device itself and therefore the entire apparatus incorporating the alignment device can be significantly reduced in thickness and size.

Abstract: A method and apparatus that provide multichannel imaging and that allow using diffraction-limited optics. The imaging apparatus includes a laser beam source to generate single-mode laser beam of energy, a multichannel spatial light modulator (SLM) accepting a plurality of modulating signals, and a beam multiplier between the radiation source and the SLM. The beam multiplier accepts the beam generated by the source and generates from that beam a plurality of beams directed onto the SLM. The beams from the beam multiplier illuminate the active region of the SLM such that the SLM generates a plurality of modulated beams modulated according to the modulating signals. The apparatus further includes an optical subsystem located between the SLM and an imaging plane that includes at least one optical element to focus the modulated beams onto an imaging plane. A recording medium sensitive to imaging radiation from the source is placed at the imaging plane.

Abstract: A surface shape measurement method using a stage to carry a substrate on which plural chip patterns are arranged in a predetermined direction and to move in a predetermined direction, and a sensor to measure a surface position of the substrate placed on the stage in a focus direction. The same position in at least two of the plural chip patterns is set to a measurement position. Measurement by the sensor is performed in the set measurement position while the stage is moved in the predetermined direction. A deflection shape of the substrate in the predetermined direction is estimated based on the surface position obtained by the measurement.

Abstract: Alignment accuracy between two or more patterned layers is measured using a metrology target comprising substantially overlapping diffraction gratings formed in a test area of the layers being tested. An optical instrument illuminates all or part of the target area and measures the optical response. The instrument can measure transmission, reflectance, and/or ellipsometric parameters as a function of wavelength, polar angle of incidence, azimuthal angle of incidence, and/or polarization of the illumination and detected light. Overlay error or offset between those layers containing the test gratings is determined by a processor programmed to calculate an optical response for a set of parameters that include overlay error, using a model that accounts for diffraction by the gratings and interaction of the gratings with each others' diffracted field. The model parameters might also take account of manufactured asymmetries.

Abstract: The X, Y and Rx positions of a mask stage are measured using two optical encoder-reading heads measuring displacements of respective grid gratings mounted on the mask stage. The grid gratings are preferably provided on cut-away portions of the mask table so as to be co-planar with the pattern on the mask itself. Measurements of the table position in the other degrees of freedom can be measured with capacitative or optical height sensors.

Abstract: A method and apparatus are disclosed for aligning an array of light transmitting elements to an array of photosensitive detectors. The array is adjusted along three axes. Any element (a coupled transmitting and detecting unit of the array) can be selected as the center of rotation. Small angular correction is made about the selected element by differentially moving the array in two axes, using adjustment tools. Alignment is accomplished by performing translational movement in the horizontal X and Y axes until a signal is detected. A rotational correction about the selected element is performed by moving one of a pair of adjustment devices until maximum light intensity is achieved for the end elements. Next, the array is scanned for the weakest performing element in the array. The alignment procedure is repeated until the performance of all of the elements in the array fall within a pre-established specification range.

Abstract: A photomask for focus monitoring of the present invention is provided with a substrate that allows the exposure light to pass through and a unit mask structure for focus monitoring. Unit mask structure for focus monitoring has two patterns, and that are formed on the surface of substrate and a light blocking film that has a rear surface pattern that is formed on the rear surface of substrate for substantially differentiating the incident directions of the exposure light that enters two patterns, and for position measurement. When the dimension of rear surface pattern is L and the wavelength of the exposure light is &lgr;, L/&lgr; is 10, or greater.

Abstract: A main controller sets an exposure control target value according to the transmittance of an optical system measured by means of a sensor prior to exposure or estimated by predetermined calculation, and exposure is controlled according to the set exposure control target value while a reticle pattern is being transferred onto a wafer through the optical system. Since the exposure energy provided to the image surface changes in a unit time per unit area in accordance with the transmittance of the optical system, the exposure control target value is set according to the transmittance of the optical system, and exposure is controlled according to the set control target value. Thus, exposure with a high precision is achieved without being influenced by the variation of the transmittance.

Abstract: A technique for dynamic optical alignment precisely adjusts the relative position of a first linear arrangement with respect to a second linear arrangement by correcting rotational misalignment about the vertical axis, establishing an optimal displacement therebetween along an optical axis, correcting rotational misalignment about the optical axis, and setting an optimum displacement therebetween on the vertical axis. The technique is carried out semiautomatically using a computer to operate actuators to control movement of the first linear arrangement, while the second linear arrangement is fixedly disposed on a substrate. When optimal alignment has been established, the first linear arrangement is fixedly attached to the substrate.

Abstract: A focus monitoring method of the invention is characterized by transferring the pattern of a photo mask for phase shift focus monitor onto a photoresist on a semiconductor substrate by using modified illumination. Photo mask for phase shift focus monitor has first and second light transmitting portions which are adjacent to each other while sandwiching a shielding pattern, and is constructed so that a phase difference other than 180 degrees occurs between exposure light passed through the first light transmitting portion and exposure light passed through the second light transmitting portion. Consequently, a focus monitoring method, a focus monitor system, and a semiconductor fabricating method with high detection sensitivity in the z direction and which do not require changing of an illumination aperture can be achieved.

Abstract: A system and method for aligning a wafer in an exposure apparatus includes a holder adapted to hold a wafer (the wafer includes alignment marks), a coarse alignment system, and a fine alignment system having a higher precision than the coarse alignment system. The fine alignment system includes multiple optical detectors. Each of the optical detectors is positioned to detect a corresponding alignment mark on the wafer. An alignment processor is connected to and controls the optical detectors and the holder. The optical detectors are controlled by the alignment processor to simultaneously detect the alignment marks in parallel operations. Further, the alignment processor simultaneously processes signals from the optical detectors in parallel operations.

Abstract: A process for measuring alignment of latent images in a photoresist layer of an integrated circuit structure on a semiconductor substrate with a test pattern formed in a lower layer on the substrate comprises the steps of forming a test pattern in selected fields of a first layer on a semiconductor substrate, forming a layer of photoresist over the first layer, forming latent images in portions of the photoresist layer lying in the selected fields overlying the test pattern of the first layer; and measuring the alignment of the test pattern in the selected fields of the first layer with the overlying latent images in the photoresist layer using scatterometry.

Abstract: An optical system for detecting and coupling light to optical devices, and a method for aligning and calibrating the system. The system includes positioning stages and fiber sensors. The fiber sensors are used to detect the positions of calibration pieces and other sensors in a variety of configurations. From these detected positions, any misalignment of the sensors or positioning stages may be calculated and corrected for. The fiber sensors calibrate the system.

Abstract: The present invention includes a method of determining a relative position of a substrate and a template spaced-apart therefrom, the substrate having substrate alignment marks disposed thereon and the template having template alignment marks disposed thereon, the method including, impinging first and second fluxes of light upon the substrate and template alignment marks, with the substrate and template alignment marks being responsive to the first flux of light defining a first response, and being responsive to the second flux of light defining a second response differing from the first response; and processing the first and second responses to form a focused image of the substrate and template alignment marks on a common plane, with the focused image indicating the relative position of the substrate and the template.

Abstract: An off-axis alignment system in a lithographic projection apparatus uses broadband radiation to illuminate a phase grating on the wafer. The broadband radiation source may include fluorescent materials, e.g. Yag:Ce or ND:Yag crystals illuminated by excitation light.

Abstract: Overlay measurements for a semiconductor wafer are obtained by forming a periodic grating on the wafer having a first set of ridges and a second set of ridges. The first and second sets of ridges are formed on the wafer using a first mask and a second mask, respectively. After forming the first and second sets of gratings, zero-order cross polarization measurements of a portion of the periodic grating are obtained. Any overlay error between the first and second masks used to form the first and second sets of gratings is determined based on the obtained zero-order cross polarization measurements.

Abstract: The invention relates to a projection lens comprising a lens assembly that has at least one first narrowing of the group of light beams. A lens with a non-spherical surface is located in front of and/or behind the first narrowing.

Abstract: An optical measurement method and system are presented for imaging two target structures in two parallel layers, respectively, of a sample, to enable determination of a registration between the two target structures along two mutually perpendicular axes of the layer. The sample is illuminated with incident radiation to produce a radiation response of the sample. The radiation response is collected by an objective lens arrangement, and the collected radiation response is split into two spatially separated radiation components. The split radiation components are directed towards at least one imaging plane along different optical channels characterized by optical paths of different lengths, respectively. The two split radiation components are detected in said at least one imaging plane, and two image parts are thereby acquired, each image part containing images of the two target structures. This enables determination of the relative distance between the two target structures.

Abstract: A system for manufacturing a semiconductor device which predicts a difference in registration error between a circuit pattern and an overlay mark from a pattern dimension, illumination conditions and the wave aberration of an exposure lens, feeds a correction value based on the predicted difference back to an exposure device and modifies an overlay inspection data control limit.

Abstract: An exposure apparatus for projecting a pattern of a reticle onto an object to be exposed with first light having a wavelength of 20 nm or smaller, said exposure apparatus comprising a projection optical system for projecting the pattern onto the object, and a position detecting system for detecting a positional information of a mark by receiving a second light having a wavelength different from that of the first light via the projection optical system.

Abstract: The present invention includes a method of aligning a substrate and a template spaced-apart from the substrate with an activating light curable liquid disposed therebetween, the substrate having substrate alignment marks and the template having template alignment marks, the method including, reducing a distance between the substrate and the template to cause a spreading of the activating light curable liquid; and varying an overlay placement of the template with respect to the substrate such that the template alignment marks are substantially aligned with the substrate alignment marks before the spreading causes the activating light curable liquid to cover an area between the substrate alignment marks and the template alignment marks.

Abstract: A light beam emitted from a light source passes through a spatial light modulation device, at which a plurality of unit elements for respectively modulating incident light beam are two-dimensionally arrayed, and a microlens array, at which a plurality of microlenses corresponding to the unit elements are arrayed, and is focused on an exposure surface. A four-part detector, which is structured by four diodes, is disposed on the exposure surface so as to correspond to four pixels which are present at one corner of the exposure area. Relative mispositioning between the spatial light modulation device and the microlens array generates a difference in respective detection signals of the four diodes. Thus, an offset between the spatial light modulation device and the microlenses can be detected. Positional adjustment of the microlens array is performed on the basis of a detected offset amount.

Abstract: The projection exposure apparatus is provided with a moving mirror (24X, 24Y) having a length Lm set so as to satisfy a relationship as represented by Lm<Dw+2BL, in which Dw is a diameter of a substrate stage (18) and BL is the distance between a projection center of an optical projection system (PL) and a detection center of a mark detection system (AS). The projection exposure apparatus having the moving mirror so set for its length Lm as to satisfy the above relationship can make the substrate stage (18) more compact in size and lighter in weight, thereby achieving improvements in performance of controlling the position of the substrate stage (18), as compared with a conventional exposure apparatus having a moving mirror set so as for its length to meet a relationship as represented by Lm>Dw+2BL.

Abstract: To provide an aligner capable of controlling a proper light exposure in accordance with an oxygen density and moisture density on an laser beam optical path, an aligner of the present invention is an aligner for illuminating a mask (or reticle) with the light emitted from a light source to expose an object to be exposed with the light reflected from the mask, which is provided with the following:

Abstract: Provided is an exposure apparatus for exposing a pattern of a reticle mounted on a first stage onto a substrate which is mounted on a second stage through a projection optical system, in which focus calibration can be conducted with high precision and a throughput can be increased. The exposure apparatus includes at least three detection systems capable of simultaneously detecting three or more marks formed at different positions on at least one of the substrate and the second stage through the projection optical system.

Abstract: Disclosed is an exposure method in which high precision focus calibration is realized by measuring a tilt of an image plane in a scanning direction, so that exposure with a high resolution can be performed. The exposure method includes: a measuring step of measuring a position of an image plane of a projection optical system at a plurality of measurement positions different from each other with respect to a scanning direction; and a correcting step of correcting a tilt of the image plane of the projection optical system based on measurements.

Abstract: An exposure apparatus includes an optical system for guiding light from a light source to an object, a holding member for holding the object, and a measuring device for measuring position of the holding member by using a reference surface provided in the holding member, wherein the reference surface is located in an area corresponding to the object which is held by the holding member.

Abstract: A method and apparatus are disclosed for aligning and maintaining the alignment of the transmitting unit and the receiving unit in an optical wireless communication system. The receiving unit includes an optical bundle positioned at the focal point of an objective optic element. The optical bundle is comprised of an array of optical fibers, arranged surrounding the receiving fiber. The receiving unit also includes a number of detectors that measure the optical signal strength on a corresponding fiber in the optical bundle. The array of fibers is used to detect the location of the received signal relative to the receiving optical fiber and to provide feedback to adjust the orientation of the optical bundle to optimize the received signal strength. When misalignment occurs between the received signal and the receiving fiber, some of the incident received signal will be captured by one or more of the outer optical fibers.

Abstract: A method for overlay measurement in an exposure process uses a multiplex filter having a plurality of filters. A first filter is selected from theplurality of filters and positioned underneath a lens of an overlay measurement apparatus. Next, a determination is made whether overlay marks formed on a wafer are perceptible through the lens and the first filter. If perceptible, the overlay marks are measured. If the overlay marks are not perceptible, the first filter is replaced with a second filter from the plurality of filters, and a determination is made whether the overlay marks are perceptible through the second filter and, if perceptible, the overlay marks are measured. Accordingly, there is no need to stop the exposure process if there is a failure to perceive the overlay marks. Further, the method, according to an embodiment of the present invention, increases the efficiency of the exposure process, especially, the wafer alignment process.

Abstract: A lithographic projection apparatus is provided with an optical system built into the wafer table for producing an image of a wafer mark that is provided on the back side of the wafer. The image is located at the plane of the front side of the wafer and can be viewed by an alignment system from the front side of the wafer.

Abstract: During device manufacturing, a beam of radiation is projected onto a substrate via a mask. The substrate is aligned with the mask using an alignment structure on the substrate, with properties of the light reflected from (or transmitted by) the alignment structure being used to determine the relative position of the substrate. Earlier processing of the substrate may cause errors in the position determined from the reflected light. In one embodiment of the invention, measurement of properties of the reflected light are used to determine a correction for errors caused by processing of the substrate. Parameters of a physical model of the alignment structure may be estimated from the reflected light and used to determine the correction. Amplitudes of a plurality of different diffraction peaks may be measured to determine the correction.

Abstract: An alignment target structure includes a reflective member and a non-reflective field proximate to the member. The field is configured to enhance identification of the target and/or to enhance contrast between the member and the field. The field may include an absorptive structure and/or a diffractive structure.

Abstract: Disclosed are techniques, apparatus, and targets for determining overlay error between two layers of a sample. In one embodiment, a method for determining overlay between a plurality of first structures in a first layer of a sample and a plurality of second structures in a second layer of the sample is disclosed. Targets A, B, C and D that each include a portion of the first and second structures are provided. Target A is designed to have an offset Xa between its first and second structures portions; target B is designed to have an offset Xb between its first and second structures portions; target C is designed to have an offset Xc between its first and second structures portions; and target D is designed to have an offset Xd between its first and second structures portions. Each of the offsets Xa, Xb, Xc and Xd is preferably different from zero; Xa is an opposite sign and differ from Xb; and Xc is an opposite sign and differs from Xd.

Abstract: Alignment marks (PMOL, PMOR, and FXY01 to FXY04) for measuring a wafer position are formed on a wafer (W) by projecting alignment mark patterns (PM and FM) arranged on a reticle reference plate (PL) fixed on a reticle stage (RSTG) which supports a reticle.

Abstract: When the ordinary exposure is performed, a wafer, to which a photoresist is applied by a resist coater, is transported onto a wafer stage of a projection exposure apparatus to perform the exposure, followed by development by a developing apparatus. When the characteristic is evaluated, respective shot areas on the wafer applied with the photoresist are exposed with an image of a predetermined evaluating mark in a narrow area in an effective field of a projection optical system of the projection exposure apparatus. The characteristic of the resist coater or the developing apparatus is evaluated by detecting a state of a resist pattern after the development. When the image formation characteristic of the projection exposure apparatus is evaluated, the wafer is exposed with images of a plurality of predetermined evaluating marks in a wide area in the effective field.

Abstract: A level sensor for a lithographic projection apparatus according to one embodiment of the invention includes a light source, a first reflector, a second reflector and a detector. The first reflector is positioned to direct light from the light source towards a wafer surface, and the second reflector is positioned to direct light reflected from the wafer surface to the detector. The first and second reflectors are selected to incur a minimal process dependent apparent surface depression.

Abstract: The invention relates to a diaphragm (1) for an integrator unit of a microlithographic projection exposure system. The diaphragm (1) includes a diaphragm opening (3), which is symmetrical with respect to a first axis of symmetry (5). The widths of the diaphragm aperture (3) in the direction of the axis of symmetry (5) are dependent on the distance (y) from the first axis of symmetry (5). The widths are greater than or equal to the width at y=0. The diaphragm (1), together with a cylindrical integrator, forms an integrator unit, which is located in an illumination system.

Abstract: An aberration mark for use in an optical photolithography system, and a method for estimating overlay errors and optical aberrations. The aberration mark includes an inner polygon pattern and an outer polygon pattern, wherein each of the inner and outer polygon patterns include a center, and two sets of lines and spaces having a different feature size and pitch that surround the outer polygon pattern. The aberration mark can be used to estimate overlay errors and optical aberrations. In some embodiments, the mark can also be used with scatterometry or scanning electron microscope devices. In other embodiments, the mark can be used to monitor aberrations of a lens in an optical photolithography system.

Abstract: A system and method having applications in semiconductor areas for accurate die placement on a substrate that takes into account any positional offset from the reference position due to variations caused by thermal change and other nonrandom systemic effects. The system includes an offset alignment tool having a plurality of internal reflection surfaces and located below a vision plane of the substrate, and an optical detector to receive an indirect image of a bottom surface of the die through the alignment tool, such that the die is accurately positioned on the substrate based on the indirect image received by the optical detector. The method comprises the steps of providing a cornercube offset alignment tool having a plurality of total internal reflection surfaces below a vision plane of the die, and receiving an indirect image of the die tool through the cornercube offset tool.

Abstract: A reference frame provided in a vacuum chamber is supported by support pillars extending through and isolated from the vacuum chamber walls to isolate the reference frame from vibrations in the vacuum chamber. The gap between the support pillar and the vacuum chamber wall may be sealed by a low-stiffness seal. The low stiffness seal may be a three part seal allowing relative motion in six-degrees of freedom.

Abstract: A method includes providing a wafer having a first grating structure and a second grating structure formed in a photoresist layer. At least a portion of the first and second grating structures is illuminated with a light source. Light reflected from the illuminated portion of the first and second grating structures is measured to generate a reflection profile. Misregistration between the first and second grating structures is determined based on the reflection profile. A processing line includes a photolithography stepper, a metrology tool, and a controller. The photolithography stepper is adapted to process wafers in accordance with an operating recipe. The metrology tool is adapted to receive a wafer processed in the stepper. The wafer has a first grating structure and a second grating structure formed in a photoresist layer. The metrology tool includes a light source, a detector, and a data processing unit.

Abstract: Overlay measurements for a semiconductor wafer are obtained by forming a periodic grating on the wafer having a first set of gratings and a second set of gratings. The first and second sets of gratings are formed on the wafer using a first mask and a second mask, respectively. The first and second sets of gratings are intended to be formed on the wafer with an intended asymmetrical alignment. A diffraction signal of the first and second sets of gratings is measured after the first and second sets of gratings are formed on the wafer. The misalignment between the first and second sets of gratings formed on the wafer is determined based on the measured diffraction signal.

Abstract: A wavefront measurement system includes a source of electromagnetic radiation. An imaging system directs the electromagnetic radiation at an object plane that it uniformly illuminates. A first grating is positioned in the object plane to condition the radiation entering the input of a projection optic. A projection optical system projects an image of the first grating onto the focal plane. A second grating is positioned at the focal plane that receives a diffracted image of the source to form a shearing interferometer. A CCD detector receives the image of the first grating through the projection optical system and the second grating that forms a fringe pattern if there are aberrations in the projection optical system. Phaseshift readout of fringe pattern can be accomplished by stepping the first grating in a lateral direction and reading each frame with the CCD detector. The first grating includes a plurality of reflecting lines each formed by a plurality of reflecting dots.

Abstract: A semiconductor structure and a method of determining an overlay error produced during formation of a semiconductor structure is disclosed. The semiconductor structure comprises a first periodic pattern and a second periodic pattern, which overlap with each other, wherein a relative position between the overlapping first and second periodic patterns contains information on the magnitude and the sign of an overlay error in a predefined direction that has been caused during the formation of the first and second periodic patterns. The overlay error is determined by directing a light beam of known optical properties onto the first and second periodic patterns and by analyzing the diffracted beam by comparison with reference data. By providing two differently oriented diffracting areas, each comprising first and second periodic patterns, the overlay error in two dimensions can be determined.

Abstract: An alignment system for a lithographic apparatus has a source of alignment radiation that has a first wavelength and a second wavelength; a detection system that has a first wavelength channel arranged to receive alignment radiation from an alignment mark at the first wavelength and a second wavelength channel arranged to receive alignment radiation from the alignment mark at the second wavelength; and a position determining unit in communication with the detection system. The position determining unit processes information from the first and second wavelength channels in combination to determine a position of the alignment mark based on information from the first wavelength channel, information from the second wavelength channel or combined information from the first and second wavelength channels according to a relative strength of the alignment radiation detected at the first wavelength to alignment radiation detected at the second wavelength. A lithographic apparatus includes the above alignment system.

Abstract: Method and apparatus for optically aligning, for subsequent assembly into discrete packages, opto-mechanical components, e.g., optical filters, and lenses for directing direct light to and from those opto-mechanical components. The apparatus comprises a light source for producing a beam of light emulating the light which exists in the assembled package of components during use, manipulator means for supporting a lens and a selected opto-mechanical component in tandem along the optical axis of the light beam and for moving the lens and selected opto-mechanical component along X and Y axes perpendicular to that optical axis, and a machine vision system having imaging means for recording images of the light beam and the opto-mechanical component and being adapted to control operation of the manipulator means so as to cause the latter to shift the lens and opto-mechanical component along the X and/or Y axes to achieve optical alignment.

Abstract: A scanning exposure apparatus for exposing a substrate (8) to a pattern with an original (1) through a projection optical system (5), while scanning the original and the substrate, includes a first detection system (14c) which detects a first substrate reference mark (18c1, 18c3) corresponding to the substrate through the projection optical system on/at at least one of an optical axis of the projection optical and an off-axis position shifted from the optical axis in a scanning direction, and an alignment system (2, 9) which aligns the original and the substrate on the basis of a detection result of the first detection system.

Abstract: A lithographic projection apparatus including an interferometer system having a reach extending over a first, measurement station and a second, exposure station. The apparatus stores the position of the mask relative to the mask table initially. A wafer table may be transferred from the first, measurement station to the second, exposure station while fully under the control of the interferometer system. The critical path through the exposure station may then be reduced. The apparatus stores the position of the wafer relative to the wafer table at the measurement station. Subsequent alignment in the exposure station may then be performed in a shorter time as the position of the mask relative to a mask table is known.

Abstract: A lithography system and method for cost-effective device manufacture that can employ a continuous lithography mode of operation is disclosed, wherein exposure fields are formed with single pulses of radiation. The system includes a pulsed radiation source (14), an illumination system (24), a mask (M), a projection lens (40) and a workpiece stage (50) that supports a workpiece (W) having an image-bearing surface (WS). A radiation source controller (16) and a workpiece stage position system (60), which includes a metrology device (62), are used to coordinate and control the exposure of the mask with radiation pulses so that adjacent radiation pulses form adjacent exposure fields (EF). Where pulse-to-pulse uniformity from the radiation source is lacking, a pulse stabilization system (18) may be optionally used to attain the desired pulse-to-pulse uniformity in exposure dose.

Abstract: A film-thickness measurement apparatus of the present invention includes a lifter, a support mount, a light-emitting device, and a light-receiving device. With the center of a wafer staying in alignment with that of the support mount, the lifter places the wafer onto the surface of the support mount to determine the center of the wafer. While the wafer is being rotated about the center of the wafer, the light-emitting device irradiates the circumferential portion of the wafer with a laser beam, thereby allowing the position of a notch to be detected depending on whether or not the laser beam passes through the notch. This makes it possible to detect the positions of the notch and the center of the wafer to determine the center axis line of the surface of the wafer, thereby allowing the coordinates of a given position on the surface of the wafer to be defined in accordance with the center axis line and the center of the wafer.