Abstract: Interferometric apparatus and methods by which the local surface characteristics of photolithographic mirrors or the like may be interferometrically measured in-situ to provide correction signals for enhanced distance and angular measurement accuracy. Surface characterizations along one or multiple datum lines in one or more directions may be made by measuring the angular changes in beams reflected off the surfaces during scanning operations to determine local slope and then integrating the slope to arrive at surface topology. The mirrors may be mounted either on the photolithographic stages or off the photolithographic stages on a reference frame.

Abstract: An optical interferometric measuring instrument comprises a laser light source 12, an interferometer portion 14, a reflecting mirror 20, a bellows driving carriage 30, and a fixed portion 34. The bellows driving carriage 30 moves together with a slider 16. A main bellows 36 is disposed between the bellows driving carriage 30 and the fixed portion 34. An auxiliary bellows 38 is disposed between the reflecting mirror 20 and the bellows driving carriage 30. An auxiliary bellows 40 is disposed between the interferometer portion 14 and the fixed portion 34. It is possible to avoid the variation of the laser wavelength ascribable to the change of the refractive index of air when the laser light passes through the air.

Abstract: An endpoint detection system in a CMP apparatus has a polishing platen, a polishing pad covering the polishing platen, a chamber located in the polishing platen, and a gas flow system arranged in a periphery of the chamber. The gas flow system has a gas inlet used to flow dry gas into the chamber and a gas outlet used to evacuate water vapor in the chamber. Since the gas flow system can evacuate the water vapor in the chamber, the problem of contaminants such as water droplets has been solved. The endpoint detection can thus be precisely controlled.

Abstract: This invention includes X-axis interferometers (3, 4) which measure the position information of a wafer stage (7), a switching device which switches a position measuring device from the X-axis interferometer (3) to the X-axis interferometer (4), depending on the moving area of the wafer stage (7), a correction computing device which performs correction calculation for the measurement result from the X-axis interferometer (3) using the first correction parameter set to obtain the current position of the wafer stage (7), a position controller which generates a signal for driving the wafer stage (7) to a target position on the basis of the correction calculation result from the correction computing device, and a reverse correction computing device which performs calculation for the signal generated by the position controller using the second correction parameter set to obtain a command value for the X-axis interferometer (4).

Abstract: A corner cube retroreflector having a coating including one or more layers at each reflecting surface. The coating causes the retroreflector to have polarization eigenstates that are substantially linear and to have the properties of a half-wave plate. The coated retroreflector can be used in interferometry and microlithography system.

Abstract: Techniques for monitoring the position of a stage in a twin stage lithography tool are disclosed.

Abstract: An apparatus includes a multi-axis interferometer for measuring changes in a position of a measurement object. The interferometer is configured to receive a progenitor input beam, direct a first angle-measuring beam derived from the progenitor input beam to make a pass to a first point on the measurement object, direct a second angle-measuring beam derived from the progenitor input beam to make a pass to a second point on the measurement object, and then combine the angle-measuring beams to produce an angle-measuring output beam, wherein each angle-measuring beam makes only a single pass to the measurement object before being combined to form the angle-measuring output beam. The interferometer is further configured to direct another set of beams derived from the progenitor input beam along different paths and then combine them to produce another output beam comprising information about changes in the position of the measurement object.

Abstract: Interferometric apparatus for measuring changes in altitude between a surface and a datum line where the apparatus comprises a dimensionally stable metrology frame and the datum line is defined in an object mounted for nominally plane translation with respect to the metrology frame in at least two orthogonal directions while experiencing relatively smaller changes in altitude in a direction nominally normal to at least two orthogonal directions. An elongated reflector is mounted with respect to either the metrology frame or the object to provide the surface, and at least one interferometer system is mounted at least in part on object for movement therewith.

Abstract: Interferometer systems are described that comprise optical assemblies to measure multiple degrees of freedom of a stage mirror and the topography of a reflecting surface of a stage mirror represented by datum lines and datum lines with corresponding local rotations of the reflecting surface of the stage mirror about the datum lines with high lateral spatial resolution. The interferometer systems measure slopes of datum lines and local rotations of the reflecting surface about the datum lines using single pass interferometric measurements of angular changes of directions of beams reflected by the reflecting surfaces. Two or more datum lines on a reflecting surface with concomitant measures of local rotations may be used to characterize topographic features, and these may be measured in situ in a lithography tool or measured off line either before installation or after removal from a lithography tool.

Abstract: The invention features an interferometry system which includes at least one dynamic beam steering assembly for redirecting one or more beams within the interferometry system in response to changes in the angular orientation or position of the measurement object. A control circuit controls the beam steering assembly based on a signal derived from one or more beams within the interferometry system. The dynamic beam steering assembly can be incorporated into interferometry systems that measure displacement, angle, and/or dispersion. The interferometry systems can be advantageously incorporated into lithography systems used to fabricate integrated circuits and other semiconducting devices and beam writing systems used to fabricate lithography masks.

Abstract: Methods and systems for compensating a measured optical path length for time-varying optical properties of gas in an interferometer's measurement beam path based on a measurement of the beam propagation direction are disclosed.

Abstract: An interferometric apparatus includes: a polarizing beam-splitting interface positioned to separate an input beam into two orthogonally polarized beams; and interferometer optics positioned to receive a first set of beams derived from one of the orthogonally polarized beams and a second set of beams derived from the other of the orthogonally polarized beams. The interferometer optics are configured to direct each beam in the first set to contact different locations of a measurement object at least once, and subsequently combine each beam in the first set with a corresponding beam from the second set of beams to produce a corresponding output beam comprising information about changes in the position of the measurement object with respect to a different degree of freedom.

Abstract: A scan type exposure apparatus in which a pattern formed on an original is transferred a substrate while relatively moving the original and the substrate relative to a projection optical system, wherein a stage is servo controlled on the basis of measurement of X and Y coordinates (x,y) and yawing component &thgr;, and wherein yawing measuring systems provided in relation to X and Y directions are selectively used in accordance with the state of operation of the apparatus so that the yawing component measurement direction is laid on preferable one of the X and Y directions.

Abstract: A two-dimensional positioning apparatus for positioning an object in a two dimensional direction, wherein are provided a platen, a slider having two X-axis motors and sensors and a Y-axis motor and sensor disposed above the platen, a converter for providing signals to detect the X-axis position of the center point of the slider, a controller for feedback control of the slider in a X-axis direction and a yaw direction, and for feedback control in the Y-direction, and a converter circuit for converting output of the controller to propulsion commands to be supplied to the motors, wherein a limiter is provided to restrict one axis limits of the propulsion commands. In this manner, accuracy is improved and flexibility is increased.

Abstract: A high speed, wide-range, high-accuracy positioning stage device for eliminating errors due to deterministic elements such as variation of surface machining accuracy of a bar mirror and for preventing error accumulation due to indeterminate elements such as air fluctuations when switching between laser interferometers. When an X1 laser interferometer as a first position measurement device and an X2 laser interferometer as a second position measurement device are switched, at a place at which at least two position measurement devices are activated, when a value is handed over from the X1 laser interferometer, which was activated, to the X2 laser interferometer, which is to be activated, errors due to the effect of X-bar mirror flatness and air fluctuations are found by a correction function for the X-bar mirror and/or a table and the average of the measured values, and the value of the X2 laser interferometer is corrected by a correction device such as a calculation device.

Abstract: A method for compensating data age in measurement signals from an interferometer includes measuring a value of the measurement signal and adjusting the measured value based on the measurement signal with a data age adjustment value to correct for data age.

Abstract: An alignment stage includes a first plane mirror (2A, 2B) which extends in two directions substantially perpendicular to each other in order to measure the position of a stage in the translation direction and the tilt of the stage in the direction of height, a first measurement unit (3A-1) which irradiates the plane mirror with a laser beam and measures the position of the stage in the translation direction by using reflection of the laser beam, a second measurement unit (3A-2) which irradiates the first plane mirror with a laser beam and measures the position by using reflection of the laser beam at a position vertically spaced apart from the first measurement unit in order to measure the tilt of the stage, a third measurement unit (14-1, 14-2, 14-3) which measures the tilt of the stage with respect to the surface of the surface plate in the direction of height, an arithmetic unit which calculates the error of the first plane mirror corresponding to each position of the stage on the basis of the difference b

Abstract: Methods are disclosed for determining and accounting for errors in a moving mirror of an interferometer used for determining the position of a stage or the like in a microlithography system or other system requiring highly accurate positioning. In an embodiment, straight lines that approximate respective curves of mirror surfaces (29a), (29b) are determined with respect to a coordinate system defined on a wafer table. The straight lines are determined by a least-squares method. Also determined are angles (&PSgr;u) and (&PSgr;v) formed by straight lines (Lu) and (Lv) relative to coordinate axes (u) and (v), respectively. Intersections with the coordinate axes u, v are (Bu, 0) and (0, Bv), respectively. The distances to points U1 and V1 on mirror surfaces 29a and 29b with respect to straight lines Lu and Lv are &ohgr;u(v) and &ohgr;v(u), respectively, and the angles with the tangent lines of the points U1 and V1 are &bgr;u(v) and &bgr;v(u), respectively.

Abstract: A laser tracking interferometric length measuring instrument has a laser source and a tracking articulating optical lever provided on an optical path of an interferometric optical system. To track a retroreflector, the optical lever reflects a laser beam at the retroreflector, which reflects the beam back to the optical lever. This beam is reflected onto a quadrant photodiode. An attitude control means is used to control the attitude of the optical lever so that the laser beam reflected by the optical lever falls on the neutral point of the photodiode.

Abstract: This invention relates to an apparatus and method for positioning dual stages during semiconductor wafer processing. More particularly, the invention facilitates the use of interferometers to determine the positions of both wafer stages at all times during processing. While the movement of a typical twin stage apparatus causes one of the stages to eclipse the other and requires the addition of a significant number of additional interferometers, this invention minimizes the number of interferometers necessary through dimensioning the stages so that one stage never totally eclipses the other.

Abstract: Apparatus for correcting positional deviations of at least one area of a subject along one or more subject position axes.

Abstract: an apparatus including: a support structure; a stage configured to move relative to the support structure; a first reflection surface carried by one of the support structure and the stage; and a first interferometry system. The first interferometry system is configured to direct a first measurement beam to contact the first reflection surface and monitor changes in the position and orientation of the stage relative to the support structure along multiple degrees of freedom using the first measurement beam and no other measurement beam that contacts the first reflection surface. For example, the first measurement beam can define a first measurement axis and the multiple degrees of freedom can include at least two of: distance along the first measurement axis, pitch about the first measurement axis, and yaw about the first measurement axis.

Abstract: Interferometry system including a multiple-pass interferometer having reflectors to reflect at least two beams along multiple passes through the interferometer, the multiple passes including a first set of passes and a second set of passes, the reflectors having first alignments that are normal to the directions of the paths of the beams that are reflected by the reflectors, the paths of the beams being sheared during the first set of passes and during the second set of passes if at least one of the reflectors has an alignment other than the first alignment, and optics to redirect the beams after the first set of passes and before the second set of passes so that shear imparted during the second set of passes cancels shear imparted during the first set of passes.

Abstract: A goniometer includes a base, a compound member supported by the base, a light-directing element operably mounted on the compound member, optically connected to a coherent light source, and disposed toward an optical filter, a first actuator disposed along a first axis and operably coupled to the base for translating the light-directing element along a first arcuate path disposed in a first plane; and a second actuator disposed along a second axis and operably coupled to the compound member for translating the light-directing element along a second arcuate path disposed in a second plane, wherein the first plane is orthogonal to the second plane, and wherein the first and second axes are co-planar, for directing coherent light at an angle that is normal to the optical filter.

Abstract: Interferometric apparatus and methods by which the local surface characteristics of photolithographic mirrors or the like may be interferometrically measured in-situ to provide correction signals for enhanced distance and angular measurement accuracy. Surface characterizations along one or multiple datum lines in one or more directions may be made by measuring the angular changes in beams reflected off the surfaces during scanning operations to determine local slope and then integrating the slope to arrive at surface topology. The mirrors may be mounted either on the photolithographic stages or off the photolithographic stages on a reference frame.

Abstract: A method and apparatus used to reduce glitches in measurements made by an accumulation of phase changes over a range greater than 2&pgr;. Embodiments of the invention feature the use of a glitch filter that receives a phase input indicating a position value. The glitch filter reduces glitches by using a feedback term that has been reduced modulo 2&pgr;.

Abstract: Interferometric apparatus and method for measuring changes in distance to an object are compensated for the presence of undesirable phase shifts in measurement beams that result from their interacting with non-polarization preserving optical elements in at least one interferometer measurement leg. Compensation is provided by phase plates, multi-order phase plates set at a predetermined angle with respect to beam components, coatings on reflecting surfaces, or a segmented phase plate at least part of which is rotated with respect to polarized beam components, and combinations thereof. Compensation is provided in interferometers having measurement legs folded with reflecting surfaces that cause relative phase shifts in propagating polarized beams because of non-normal incidence. Compensation is also provided in upward and downward looking interferometers for measuring altitude and changes in altitude to a surface such as a translating wafer stage of a photolithographic exposure apparatus.

Abstract: Interferometric apparatus and methodology for monitoring the relative motion among objects, preferably that of mask and wafer stages in photolithographic processes. The apparatus comprises a plurality of interferometers where each interferometer operates to provide a mixed optical interference signal containing phase information indicative of the motion of a corresponding object. Detector means are provided for receiving the mixed optical interference signals and generating electrical interference signals containing information corresponding to the motion of an associated object. Electronic processing means operate to receive at least one select one of the electrical interference signals and generate a corresponding modified electrical interference signal that is compensated for any Doppler shift differences among the electrical interference signals caused by differences in preferred relative rates of motion in the objects.

Abstract: The shape of a reflecting surface (7XS) formed on a moving object (4) moving along a reference plane is measured by measuring one-dimensional shapes of the reflecting surface (7XS) along the extending direction of the reflecting surface (7XS) at a plurality of different positions in a direction perpendicular to the reference plane. At least one of the position and posture of the moving object (4) is accurately controlled on the basis of the shape information obtained in this manner, the two-dimensional position information of the moving object (4), and the tilt information of the reflecting surface (7XS).

Abstract: The invention features a system and method for reducing the contribution of cyclic errors to an interferometric position measurement of a movable stage. An initial interferometric position measurement of the stage is averaged with at least one additional measurement corresponding to a displacement(s) of the stage from its initial position. The displacements are selected to reduce the overall cyclic error contribution to an average position measurement. As a result, the average position of the stage can be measured more accurately than any of its individual positions. The average position can be used to more accurately determine the average position of an alignment mark on a wafer carried by the stage. Furthermore, the averaging described above can be applied to additional interferometric measurement axes.

Abstract: A positioning stage has a base which carries a stage plate slidably on its upper surface. Three rotatable drives engage both the stage plate and the base to move the stage plate on the base to provide motion along the x and y axes plus rotation. The linear drives each include a motor and a capstan driven by the motor and a drivebar frictionally coupled to the capstan. The stage is spring loaded to provide constant down-load force, regardless of the varying extension length of the drivebar. A ball joint permits varying between the cones and the ball of the ball joint dynamically to desired levels. Pitch, roll, and movement in the Z-axis are precisely maintained by the stage plate. X and Y position are determined by an X interferometer and a Y interferometer, respectively. Yaw is measured by a yaw sensor device for determining yaw angle comprising a light emitting source and a position sensing detector, which generates an analog signal that is the input to a yaw servo to correct yaw error.

Abstract: A scanning exposure apparatus and method thereof for maintaining a desired shape of a shot area exposed on a photosensitive substrate where an angle formed by the mirrors of interferometric systems for measuring the position of a stage and/or the angle formed by the running direction of a wafer stage and a reference mark plate is changed. A reticle on a reticle minute drive stage is scanned relative to an illuminated region and a wafer on a Z&thgr;-axis drive stage is scanned relative to an exposure region in synchronization with the scanning of the reticle. Thus, a shot area SA on the wafer is exposed to light carrying a pattern image of the reticle. The angle of rotation of a mirror facing in the non-scanning direction of the Z&thgr;-axis drive stage is calculated based on measurement values of two interferometers. The angle of rotation of a mirror facing in the non-scanning direction of the reticle minute drive stage is calculated based on measurement values of two interferometers.

Abstract: A method of assembling arrays of small particles or molecules using an atomic force microscope to define ferroelectric domains includes depositing a ferroelectric thin film upon a substrate forming workpiece, then using an atomic force microscope having a conductive, tip for generating a pattern on this thin film to define desired nano-circuit patterns. Next, exposure of this thin film to a solution containing chemical species which selectively adsorb or accumulate under the influence of electrophoretic forces in selected regions of this thin film.

Abstract: To accurately measure the position and posture of a stage apparatus used in an exposure apparatus or the like, the Z position and displacement of a top stage (27) are measured using as a reference a lens barrel support (35) independently of the top stage in terms of vibrations by an interferometer system which includes a projection optical system (34) for projecting a pattern formed on a master onto a substrate, stages (27, 31, 40) capable of moving with respect to the projection optical system (34) while holding the substrate or master, and a lens barrel support (35) that supports the projection optical system (34), and which uses a Z measuring mirror (30) that is arranged on a Y stage (31) and has a reflecting surface almost parallel to the XY plane, and a Z interferometer (25) arranged on the Y stage (31).

Abstract: A jacket is provided to surround coils in a stationary member of a linear motor. An inlet of the jacket is directed toward the optical path of a laser beam from a laser interferometer, and a temperature-controlled fluid is circulated through the jacket. Temperature sensors are provided at the outlet and inlet, respectively, of a temperature controller. The temperature of the fluid supplied to the stationary member is controlled so as to become equal to the temperature around the optical path of the laser beam on the basis of the values of temperature measured by the temperature sensors, thereby suppressing fluctuations of air in the optical path of the laser beam. An exhaust groove is provided in a guide bar transport member so as to surround a bearing surface around a gas outlet, and partition walls flush with the bearing surface are provided outside the exhaust groove.

Abstract: A positioning stage system includes a first stage movable at least in one of a rotational direction and a tilt direction, a second stage movable at least in X and Y directions, a measurement mirror system fixed to the second stage, a reference mirror system disposed on the first stage, and a measuring system for measuring displacement of the measurement mirror system in the X or Y direction, while using the reference mirror system as a positional reference, wherein the reference mirror system is arranged so that laser light incident on the reference mirror system is reflected in the same direction as the incidence direction, substantially constantly.

Abstract: A displaceable X/Y coordinate measurement table having two orthogonally arranged measurement mirrors for interferometric position determination is described. The displaceable measurement table, a mirror body carrying the measurement mirrors, and the receptacle for the substrate are embodied as separate components. The mirror body has a number of support points on its upper side and lower side for supporting a substrate or a receptacle above the upper side and for supporting the mirror body on the lower points above the measurement table. The mirror geometry is therefore unaffected by the weight of various substrates. The two measurement mirrors are integrated into a one-piece mirror body made of a material having an extremely low coefficient of thermal expansion. The described embodiments have frame-shaped openings in the X/Y coordinate measurement table and mirror body, which makes the measurement table suitable for both reflected and transmitted applications.

Abstract: An exposure apparatus has a triangular shaped stage which is movable in a two-dimensional plane while holding a substrate. The stage has a reflecting surface provided on a side face of the stage so that the surface extends in a specific direction intersecting Y axis and X axis. An interferometer radiates a beam onto the reflecting surface to measure a position of the stage in a direction perpendicular to the specific direction. Using the measured position and an angle of the specific direction, a calculator can calculate the position of the stage on rectangular coordinate system defined by X and Y axes. The size and weight of the stage can be reduced, and the throughput of the exposure apparatus is improved.

Abstract: Interferometric apparatus for measuring changes in altitude between a surface and a datum line where the apparatus comprises a dimensionally stable metrology frame and the datum line is defined in an object mounted for nominally plane translation with respect to the metrology frame in at least two orthogonal directions while experiencing relatively smaller changes in altitude in a direction nominally normal to said at least two orthogonal directions. Elongated reflector means are mounted with respect to either the metrology frame or the object to provide the surface, and at least one interferometer system is mounted at least in part on said object for movement therewith.

Abstract: Interferometric apparatus and methods by which the local surface characteristics of photolithographic mirrors or the like may be interferometrically measured in-situ to provide correction signals for enhanced distance and angular measurement accuracy. Surface characterizations along one or multiple datum lines in one or more directions may be made by measuring the angular changes in beams reflected off the surfaces during scanning operations to determine local slope and then integrating the slope to arrive at surface topology. The mirrors may be mounted either on the photolithographic stages or off the photolithographic stages on a reference frame.

Abstract: An exposure apparatus for exposing a substrate with an exposure light beam passing through a mask comprises a movable stage for moving the substrate, a stage chamber for accommodating the movable stage, a transport system for transporting the substrate into the stage chamber, and a first alignment system for performing positional adjustment for the substrate with respect to the movable stage in the stage chamber. The position of an exposure objective delivered from the transport system into the stage chamber can be subjected to positional adjustment by using the first alignment system. The stage chamber and the movable stage can be assembled to a frame of the exposure apparatus in accordance with the module system. The exposure apparatus includes a second alignment system for performing positional adjustment for the substrate installed on the movable stage at an exposure position.

Abstract: An exposure apparatus includes a projection optical system, a barrel supporting member for supporting the projection optical system, a stage being movable relative to the projection optical system, a base for supporting the stage, a base measuring system for measuring at least one of a position and a displacement of the base with respect to the barrel supporting member, and a stage measuring system for measuring at least one of a position and a displacement of the stage with respect to the barrel supporting member.

Abstract: The invention features an interferometry system that measures changes in the angular orientation of a measurement object and that also includes at least one dynamic beam steering assembly. The dynamic beam steering assembly redirects one or more beams within the interferometry system in response to a change in the angular orientation of the measurement object. In many embodiments, the presence of the dynamic beam steering assembly permits the interferometry system to measure the angular orientation of the measurement object using only a single measurement beam to contact the measurement object. Furthermore, in many embodiments, a control signal derived from the measurement beam contacting the measurement object causes the beam steering assembly to redirect a measurement beam to contact the measurement object at normal incidence.

Abstract: A stage system includes a movable stage, a gas blowing port for blowing a gas in a predetermined direction, a mirror disposed on the stage, a laser interferometer for projecting measurement light to the mirror, to measure a position of the stage, and a member disposed between the gas blowing port and a measurement light path of the laser interferometer, to block a portion of a gas flow from the gas blowing port. This arrangement enables reduction of an interferometer error caused by any fluctuation of an air, without disturbing the stage motion.

Abstract: The invention features an interferometry system which includes at least one dynamic beam steering assembly for redirecting one or more beams within the interferometry system in response to changes in the angular orientation or position of the measurement object. A control circuit controls the beam steering assembly based on a signal derived from one or more beams within the interferometry system. For example, the control circuit can cause the beam steering assembly to redirect a measurement beam within the system such that exit measurement and reference beams used to generate an interferometric signal remain substantially parallel to one another over a range of angular orientations or translations of the measurement object. The interferometry systems can be advantageously incorporated into lithography systems used to fabricate integrated circuits and other semiconducting devices and beam writing systems used to fabricate lithography masks.

Abstract: An exposure apparatus includes a projection optical system, a barrel supporting member for supporting the projection optical system, a stage being movable relative to the projection optical system, a base for supporting the stage, a base measuring system for measuring at least one of a position and a displacement of the base with respect to the barrel supporting member, and a stage measuring system for measuring at least one of a position and a displacement of the stage with respect to the barrel supporting member.

Abstract: A laser interferometer for detecting the position of a moving object in a Y-direction when the object moves in an X-direction has a separating optical system that moves in the X-direction at a speed different from that of the moving object. A laser beam is separated by the separating optical system into a reference beam and a measurement beam, which are individually directed toward a reference mirror and a moving mirror on the moving object. The light of the measurement beam reflected from the moving mirror, and the light of the reference beam reflected from the reference mirror are received by a photodetector via the separating optical system, and the photoelectric conversion signal of the interference light is output as information concerning the position of the moving object in the Y-direction. A fixed mirror that is shorter than the moving object can be used because the separating optical system also moves in the X-direction.

Abstract: Interferometric apparatus and method by which polarization effects and stage yaw and pitch are substantially reduced. A beam redirecting means selected from the group consisting of corner mirrors, prisms, diffractive elements, holographic elements, and combinations thereof are fixedly mounted on a body capable of rectilinear motion for movement therewith. The measurement beam path to and from the redirecting means is folded at least once so that incoming and outgoing beam segments are spatially separated and substantially parallel to one another and the reference beam.

Abstract: Even though a laser interferometer is affected by the changes in the environment, a reticle can be inspected with a high accuracy by synthesizing a reference image corrected appropriately to compare with an optical image. The reticle which a pattern is plotted in advance is irradiated with a light beam to obtain the optical image from the transmitted light to compare the optical image with the reference image synthesized by converting draft data used at plotting said pattern and to detect defects of the pattern. The reference image is corrected based on the deviation data obtained at the preceding pattern defect detection.

Abstract: A projection exposure apparatus and method aligns a substrate with an optical axis of a lens column using one or more interferometers, mirrors, and a control device. The lens column projects a pattern from a mask onto the substrate. The optical axis of the lens column is perpendicular to the substrate. To ensure precise alignment of the lens column and the substrate, the one or more interferometers use a plurality of beams having respective paths, the lengths of which change in response to movement of the optical axis. In response to the detected changes of the interferometer beams, a control device adjusts the position of the stage so that the substrate is aligned with the optical axis of the lens column.