Movable body drive method, movable body apparatus, exposure method, exposure apparatus, and device manufacturing method

A stage is driven (position control) using a hybrid signal which is obtained by synthesizing an output signal of an interferometer (an interferometer system) and an output signal of an encoder (an encoder system) that are made to pass through a high pass filter and a low pass filter, respectively. A cutoff frequency is set to a frequency corresponding to a speed slightly smaller than the speed of the stage at the time of scanning exposure. This allows the stage to be driven using an interferometer whose linear measurement is high at the time of scanning exposure, and using an encoder whose measurement reproducibility is high at the time of stepping.

CROSS-REFERENCE TO RELATED APPLICATIONS

This non-provisional application claims the benefit of Provisional Application No. 61/290,359 filed Dec. 28, 2009, and Provisional Application No. 61/302,633 filed Feb. 9, 2010, the disclosures of which are hereby incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to movable body drive methods, movable body apparatus, exposure methods, exposure apparatus, and device manufacturing methods, and more particularly to a movable body drive method in which a movable body is driven along a predetermined plane, a movable body apparatus including the movable body, an exposure method which uses the movable body drive method, an exposure apparatus which is equipped with the movable body apparatus, and a device manufacturing method which uses the exposure method or the exposure apparatus.

2. Description of the Background Art

Conventionally, in a lithography process for manufacturing microdevices (such as electron devices) such as semiconductor devices, liquid crystal display devices and the like, exposure apparatuses such as a projection exposure apparatus by a step-and-repeat method (a so-called stepper) and a projection exposure apparatus by a step-and-scan method (a so-called scanning stepper (which is also called a scanner) are mainly used.

In this kind of exposure apparatus, in order to transfer a pattern of a reticle (or a mask) on a plurality of shot areas on a wafer, a wafer stage holding the wafer is driven, for example, by linear motors and the like. In this case, position measurement of the wafer stage has been generally performed, using a laser interferometer which is stable and has high resolution.

However, requirements for a stage position control with higher precision are increasing due to finer patterns that accompany higher integration of semiconductor devices, and now, measurement errors resulting from air fluctuation generated by temperature variation of the atmosphere on the beam path of the laser interferometer or by temperature gradient has come to occupy a large percentage in the overlay budget.

As a position measuring device of the stage instead of the laser interferometer, an encoder (for example, U.S. Pat. No. 7,238,931) is promising. However, while the encoder is superior to the laser interferometer in the viewpoint of measurement reproducibility because of using a scale, it is inferior to the laser interferometer for the mechanical instability (drift of the grating pitch, fixed location drift, thermal expansion and the like) of the scale in the viewpoint of linearity.

In view of the drawbacks of the laser interferometer and the encoder described above, various proposals are being made (refer to, for example, U.S. Patent Application Publication No. 2007/0288121, or U.S. Patent Application Publication No. 2009/0027640 and the like) of methods used to measure the position of a stage using both a laser interferometer and an encoder (a position detection sensor which uses a diffraction grating). However, the methods and the like disclosed in these U.S. Patent Application Publication and the like are still not sufficient enough when ensuring a highly accurate and stable position control performance of the stage which is required in the current exposure apparatus.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, there is provided a movable body drive method in which a movable body is driven along a predetermined plane, the method comprising: driving the movable body based on one of a synthesized signal of a first signal which is a first detection signal that has been made to pass through a high pass filter and a second signal which is a second detection signal that has been made to pass through a low pass filter having a cut off frequency which is the same as the high pass filter, the first detection signal corresponding to a position of the movable body obtained by receiving a return beam of a measurement beam via an optical member provided on the movable body, and the second detection signal being obtained by irradiating a measurement beam on a diffraction grating provided on a measurement plane parallel to the predetermined plane on one of the movable body and an outside of the movable body and receiving a diffraction beam from the diffraction grating by a measurement system which has at least a part of the system placed on the other of the movable body and an outside of the movable body, and a signal which is substantially equivalent to the synthesized signal.

When the optical member provided on the movable body is a reflection surface member, the return beam of the measurement beam via the optical member can be a reflection beam of a measurement beam that has been irradiated on the reflection surface, or in the case the optical member is a deflection member or a separation member, the return beam can be a return beam of a reflection beam of a measurement beam that has been irradiated on another reflection surface member different from the optical member via the optical member. In this specification, the expression, a return beam of a measurement beam via an optical member, is used in such a meaning.

According to this method, the movable body is driven based on a synthetic signal (or a signal substantially equivalent to the synthetic signal) of a first signal which is the first detection signal that has been made to pass through the high pass filter and a second signal which is the second detection signal that has been made to pass through the low pass filter (which has the same cutoff frequency as the high pass filter). Therefore, in the case the frequency of the first and second detection signals is higher than a predetermined cutoff frequency, the movable body is driven based on the first detection signal of the first measurement system having high linear measurement, whereas in the case when the first and second detection signals is lower, the movable body is driven based on the second detection signal of the second measurement system having high measurement reproducibility.

According to a second aspect of the present invention, there is provided a first exposure method, comprising: making a movable body hold an object subject to exposure; and driving the movable body by using the movable body drive method of the present invention when irradiating an energy beam on the object held by the movable body and forming a pattern on the object.

According to this method, it becomes possible to linearly drive the movable body at a constant speed quickly and with high precision with respect to the energy beam, as well as drive wafer stage WST precisely to the starting position of the constant speed drive. The former makes it possible to form a pattern on the object with good precision, and the latter makes it possible to improve the overlay accuracy.

According to a third aspect of the present invention, there is provided a movable body apparatus, comprising: a movable body which moves along a predetermined plane; a first measurement system which outputs a first detection signal corresponding to a position of the movable body obtained by receiving a return beam of a measurement beam via an optical member provided on the movable body; a second measurement system which outputs a second detection signal by irradiating a measurement beam on a diffraction grating on a measurement plane parallel to the predetermined plane provided on one of the movable body and an outside of the movable body and receiving a diffraction beam from the diffraction grating, and has at least a part of the system placed on the other of the movable body and an outside of the movable body; and a drive system which drives the movable body based on a synthesized signal of a first signal which is the first detection signal that has passed through a high pass filter and a second signal which is the second detection signal that has passed through a low pass filter having the same cutoff frequency as the high pass filter, or a signal which is substantially equivalent to the synthesized signal.

According to this apparatus, the movable body is driven based on a synthetic signal (or a signal substantially equivalent to the synthetic signal) of a first signal which is the first detection signal that has been made to pass through the high pass filter and a second signal which is the second detection signal that has been made to pass through the low pass filter (which has the same cutoff frequency as the high pass filter). Therefore, in the case the frequency of the first and second detection signals is higher than a predetermined cutoff frequency, the movable body is driven based on the first detection signal of the first measurement system having high linear measurement, whereas in the case when the first and second detection signals is lower, the movable body is driven based on the second detection signal of the second measurement system having high measurement reproducibility.

According to a fourth aspect of the present invention, there is provided a first exposure apparatus, the apparatus comprising the movable body apparatus of the present invention in which an object is held by the movable body; and a pattern generation device which generates a pattern by irradiating an energy beam on the object held by the movable body and exposing the object.

According to this apparatus, it becomes possible to form a pattern on an object with good precision, and also to improve the overlay accuracy.

According to a fifth aspect of the present invention, there is provided a second exposure method in which an energy beam is irradiated on a mask on which a pattern is formed, and the pattern is transferred on an object, the method comprising: driving at least one of a first movable body which moves along a predetermined plane holding the object and a second movable body which holds the mask, based on one of a synthesized signal of a first signal which is a first detection signal that has been made to pass through a high pass filter and a second signal which is a second detection signal that has been made to pass through a low pass filter having a cut off frequency which is the same as the high pass filter, the first detection signal corresponding to a position of the movable body obtained by receiving a return beam of a measurement beam via an optical member provided on the first movable body, and the second detection signal being obtained by irradiating a measurement beam on a diffraction grating provided on a measurement plane parallel to the predetermined plane on one of the movable body and an outside of the movable body and receiving a diffraction beam from the diffraction grating by a measurement system which has at least a part of the system placed on the other of the movable body and an outside of the movable body, and a signal which is substantially equivalent to the synthesized signal.

According to this method, at least one of the first movable body and the second movable body is driven based on a synthetic signal (or a signal substantially equivalent to the synthetic signal) of a first signal which is the first detection signal that has been made to pass through the high pass filter and a second signal which is the second detection signal that has been made to pass through the low pass filter (which has the same cutoff frequency as the high pass filter). Therefore, in the case the frequency of the first and second detection signals is higher than a predetermined cutoff frequency, at least one of the first movable body and the second movable body is driven based on the first detection signal of the first measurement system having high linear measurement, whereas in the case when the first and second detection signals is lower, the movable body is driven based on the second detection signal of the second measurement system having high measurement reproducibility. This makes it possible to transfer and form a pattern with an accurate overlay in a predetermined area (pattern formation area) on an object.

According to a sixth aspect of the present invention, there is provided a third exposure method in which a mask and an object is synchronously moved in a predetermined direction while an energy beam is irradiated on the mask on which a pattern is formed, and the pattern is transferred onto the object, the method comprising: driving at least one of a first movable body moving along a predetermined plane holding the object and a second movable body holding the mask, according to a predetermined temporal change curve of speed and also along a predetermined path, while switching between a first detection signal corresponding to a position of the first movable body output by an interferometer system which detects positional information of the first movable body and a second detection signal corresponding to a position of the first movable body output by an encoder system which detects positional information of the first movable body that serves as a drive signal, by making the first detection signal and the second detection signal pass through a high pass filter and a low pass filter that have the same cutoff frequency, respectively; and performing a weighting of a first drive period in which the at least one movable body is driven based on the first detection signal and a second drive period in which the at least one movable body is driven based on the second detection signal by setting the cutoff frequency.

According to this method, at least one of the first movable body and the second movable body holding the mask can be driven according to a predetermined temporal change curve of speed and also along a predetermined path based on the drive signal, while switching between the first detection signal corresponding to a position of the first movable body output by an interferometer system which detects positional information of the first movable body and the second detection signal corresponding to a position of the first movable body output by an encoder system which detects positional information of the first movable body that serves as the drive signal, and it becomes possible to set the first drive period and the second drive period according to their weight.

According to a seventh aspect of the present invention, there is provided a device manufacturing method, including forming a pattern on an object by the exposure method according to the present invention; and developing the object on which the pattern is formed.

According to an eighth aspect of the present invention, there is provided a second exposure apparatus which irradiates an energy beam on a mask on which a pattern is formed, and transfers the pattern on an object, the apparatus comprising: a first movable body which holds the object and moves along a predetermined plane; a second movable body which moves holding the mask; a first measurement system which outputs a first detection signal corresponding to a position of the first movable body obtained by receiving a return beam of a measurement beam via an optical member provided on the first movable body; a second measurement system which outputs a second detection signal by irradiating a measurement beam on a diffraction grating on a measurement plane parallel to the predetermined plane provided on one of the first movable body and an outside of the first movable body and receiving a diffraction beam from the diffraction grating, and has at least a part of the system placed on the other of the first movable body and an outside of the first movable body; and a movable body drive system which drives at least one of the first movable body and the second movable body, based on a synthesized signal of a first signal which is the first detection signal that has passed through a high pass filter and a second signal which is the second detection signal that has passed through a low pass filter having the same cutoff frequency as the high pass filter, and a signal which is substantially equivalent to the synthesized signal.

According to this apparatus, by the movable body drive system, at least one of the first movable body and the second movable body is driven based on a synthetic signal (or a signal substantially equivalent to the synthetic signal) of a first signal which is the first detection signal that has been made to pass through the high pass filter and a second signal which is the second detection signal that has been made to pass through the low pass filter (which has the same cutoff frequency as the high pass filter). Therefore, in the case the frequency of the first and second detection signals is higher than a predetermined cutoff frequency, at least one of the first movable body and the second movable body is driven based on the first detection signal of the first measurement system having high linear measurement, whereas in the case when the first and second detection signals is lower, the movable body is driven based on the second detection signal of the second measurement system having high measurement reproducibility. This makes it possible to transfer and form a pattern with an accurate overlay in a predetermined area (pattern formation area) on an object.

According to the ninth aspect of the present invention, there is provided a third exposure apparatus that synchronously moves a mask and an object in a predetermined direction while irradiating an energy beam on the mask on which a pattern is formed, and transfers the pattern onto the object, the apparatus comprising: a first movable body which holds the object and moves along a predetermined plane; a second movable body which moves holding the mask; an interferometer system which detects positional information of the first movable body, and outputs a first detection signal corresponding to the position of the first movable body; an encoder system which detects positional information of the first movable body, and outputs a second detection signal corresponding to the position of the first movable body; a drive system which drives at least one of the first movable body and the second movable body, according to a predetermined temporal change curve of speed and also along a predetermined path, while switching between the first detection signal and the second detection signal that serves as a drive signal, by making the first detection signal and the second detection signal pass through a high pass filter and a low pass filter that have the same cutoff frequency, respectively; and a setting device which performs a weighting of a first drive period in which the at least one movable body is driven based on the first detection signal and a second drive period in which the at least one movable body is driven based on the second detection signal by setting the cutoff frequency.

According to this apparatus, at least one of the first movable body and the second movable body holding the mask can be driven according to a predetermined temporal change curve of speed and also along a predetermined path based on the drive signal, while switching between the first detection signal corresponding to a position of the first movable body output by an interferometer system which detects positional information of the first movable body and the second detection signal corresponding to a position of the first movable body output by an encoder system which detects positional information of the first movable body that serves as the drive signal, and it becomes possible to set the first drive period and the second drive period according to their weight.

According to the tenth aspect of the present invention, there is provided a device manufacturing method, including forming a pattern on an object using the exposure apparatus of the present invention, and developing the object on which the pattern is formed.

DESCRIPTION OF THE EMBODIMENTS

First Embodiment

A first embodiment will be described below, with reference toFIGS. 1 to 13C.

FIG. 1schematically shows a configuration of an exposure apparatus100related to the first embodiment. Exposure apparatus100is a projection exposure apparatus by a step-and-scan method, which is a so-called scanner. As it will be described later on, a projection optical system PL is provided in exposure apparatus100. In the description below, a direction parallel to an optical axis AX of projection optical system PL will be described as the Z-axis direction, a scanning direction within a plane orthogonal to the Z-axis direction in which a reticle and a wafer are relatively scanned will be described as the Y-axis direction, a direction orthogonal to the Z-axis and the Y-axis will be described as the X-axis direction, and rotational (inclination) directions around the X-axis, the Y-axis, and the Z-axis will be described as θx, θy, and θz directions, respectively.

Exposure apparatus100is equipped with an illumination system10, a reticle stage RST, a projection unit PU, a stage device50having a wafer stage WST, and a control system of these parts. InFIG. 1, wafer W is mounted on wafer stage WST.

Illumination system10lights up illumination domain IAR of the form of slit in reticle R done setting (a limit) of in a reticle blind (a masking system) in approximately uniform illumination by illuminating ray (exposing light) IL. A configuration of illumination system10is disclosed in, for example, U.S. Patent Application Publication No. 2003/0025890 and the like. In this case, as illumination light IL, for example, an ArF excimer laser beam (wavelength 193 nm) is used.

On reticle stage RST, reticle R having a pattern surface (the lower surface inFIG. 1) on which a circuit pattern and the like are formed is fixed by, for example, vacuum adsorption. Reticle stage RST is finely drivable within an XY plane, for example, by a reticle stage drive section11(not shown inFIG. 1, refer toFIG. 6) that includes a linear motor or the like, and reticle stage RST is also drivable in a scanning direction (in this case, the Y-axis direction, which is the lateral direction of the page surface inFIG. 1) at a predetermined scanning speed.

Positional information (including rotation information in the θz direction) of reticle stage RST in the XY plane is constantly detected, for example, at a resolution of around 0.25 nm by a reticle laser interferometer (hereinafter referred to as a “reticle interferometer”)116, via a movable mirror15(or a reflection surface formed on an edge surface of reticle stage RST). The measurement values of reticle interferometer116are sent to a main controller20(not shown inFIG. 1, refer toFIG. 6). Incidentally, positional information of reticle stage RST can be measured using the encoder disclosed in, for example, U.S. Patent Application Publication No. 2007/0288121, instead of using a reticle interferometer.

Projection unit PU is placed below reticle stage RST inFIG. 1. Projection unit PU includes a barrel40and projection optical system PL held within barrel40. As projection optical system PL, for example, a dioptric system that is composed of a plurality of optical elements (lens elements) that are disposed along optical axis AX parallel to the Z-axis direction is used. Projection optical system PL is, far example, both-side telocentric and has a predetermined projection magnification (e.g. one-quarter, one-fifth, one-eighth times, or the like) n Therefore, when illumination system10illuminates illumination area IAR on reticle R, by illumination light IL which has passed through reticle R placed so that its pattern surface substantially coincides with a first surface (object surface) of projection optical system PL, a reduced image of the circuit pattern of reticle R within illumination area IAR via projection optical system PL (projection unit PU) is formed on an area (hereinafter also referred to as an exposure area) IA conjugate with illumination area IAR on a wafer W whose surface is coated with a resist (sensitive agent) and is placed on a second surface (image plane surface) side of projection optical system PL. And by reticle stage RST and wafer stage WST being synchronously driven, reticle R is relatively moved in the scanning direction (the Y-axis direction) with respect to illumination area IAR (illumination light IL) while wafer W is relatively moved in the scanning direction (the Y-axis direction) with respect to exposure area IA (illumination light IL), thus scanning exposure of a shot area (divided area) on wafer W is performed, and the pattern of reticle R is transferred onto the shot area That is, the pattern of reticle R is generated on wafer W according to illumination system10and projection optical system PL, and then by the exposure of the sensitive layer (resist layer) on wafer W with illumination light IL, the pattern is formed on wafer W.

As shown inFIG. 1, stage device50is equipped with a wafer stage WST placed on a base board12, a measurement system200(refer toFIG. 6) which measures positional information of wafer stage WST, a stage drive system124(refer toFIG. 6) which drives wafer stage WST, and the like. Measurement system200includes an interferometer system118and an encoder system150, as shown inFIG. 6.

Wafer stage WST is supported on base board12, via a clearance gap (gap, clearance) of around several μm by noncontact bearings (not shown), such as, for example, air bearings and the like. Further, wafer stage WST is drivable in predetermined strokes in the X-axis direction and the Y-axis direction, by stage drive system124(refer toFIG. 6) which includes a linear motor and the like.

Wafer stage WST includes a stage main section91, and a wafer table WTB that is mounted on stage main section91. Wafer table WTB and stage main section91are configured drivable in the X-axis direction, the Y-axis direction, the Z-axis direction, the θx direction, the θy direction, and the θz direction (hereinafter described as directions of six degrees of freedom, or directions of six degrees of freedom (X, Y, Z, θx, θy, and θz)) with respect to base board12, for example, by a drive system including a linear motor and a Z leveling mechanism (including a voice coil motor and the like).

In the center of the upper surface of wafer table WTB, a wafer holder (not shown) is arranged which holds wafer W by vacuum suction or the like. As shown inFIG. 2, on the +Y side of the wafer holder (wafer W) on the upper surface of wafer table WTB, a measurement plate30is provided. In measurement plate30, a fiducial mark FM used for wafer alignment is provided in the center, and on both sides of fiducial mark FM in the X-axis direction, a pair of reference marks RM is provided.

Further, on the upper surface of wafer table WTB, a scale used by an encoder system described below is formed. More specifically, in areas on one side and the other side in the X-axis direction (both sides in the horizontal direction of the page surface inFIG. 2) on the upper surface of wafer table WTB, Y scales39Y1and39Y2are formed, respectively. Y scales39Y1and39Y2are each composed of a reflective grating (for example, a diffraction grating) having a periodic direction in the Y-axis direction in which grid lines38whose longitudinal direction is in the X-axis direction are arranged in a predetermined pitch along the Y-axis direction.

Similarly, in areas on one side and the other side in the Y-axis direction (both sides in the vertical direction of the page surface inFIG. 2) on the upper surface of wafer table WTB, X scales39X1and39X2are formed, respectively, in a state where the scales are placed between Y scales39Y1and39Y2. X scales39X1and39X2are composed of a reflective grating (for example, a diffraction grating) having a periodic direction in the X-axis direction in which grid lines37having the longitudinal direction in the Y-axis direction are arranged in a predetermined pitch along the X-axis direction.

Incidentally, the pitch of grid lines37and38, for example, is set to 1 μm. InFIG. 2and other drawings, the pitch of the gratings is illustrated larger than the actual pitch for the sake of convenience.

Further, in order to protect the diffraction grating, it is also effective to cover the grating with a glass plate with low thermal expansion. In this case, as the glass plate, a plate whose thickness is the same level as the wafer, such as for example, a plate 1 mm thick, can be used, and the plate is set on the upper surface of wafer table WTB so that the surface of the glass plate becomes the same height (flush) as the wafer surface.

Further, on the −Y end surface and the −X end surface of wafer table WTB, as shown inFIG. 2, a reflection surface17aand a reflection surface17bused in the interferometer system to be described later) are formed.

Further, on a surface on the +Y side of wafer table WTB, a fiducial bar (hereinafter, shortly referred to as an “FD bar”)46extending in the X-axis direction is attached as shown inFIG. 2, similar to the CD bar disclosed in, for example, U.S. Patent Application Publication No. 2008/0088843. In the vicinity of the end portions on one side and the other side in the longitudinal direction of FD bar46, a reference grating (for example, a diffraction grating)52whose periodic direction is the Y-axis direction is respectively formed, placed symmetric to a center line LL. Further, on the upper surface of FD bar46, a plurality of reference marks M is formed. As each of the reference marks M, a two-dimensional mark is used having a size that can be detected by an alignment system (to be described later).

In exposure apparatus100, a primary alignment system AL1is provided which has a detection center at a position spaced apart by a predetermined distance to the −Y side from optical axis AX, on a straight line (hereinafter referred to as a reference axis) LV parallel to the Y-axis passing through optical axis AX of projection optical system PL, as shown inFIGS. 3 and 4. Primary alignment system AL1is fixed to the lower surface of the mainframe not shown). As shown inFIG. 5, on one side and the other side in the X-axis direction with primary alignment system AL1in between, secondary alignment systems AL21and AL22, and AL23and AL24whose detection centers are substantially symmetrically placed with respect to reference axis LV are severally arranged. Secondary alignment systems AL21to AL24are fixed via a movable support member to the lower surface of the mainframe (not shown), and by using drive mechanisms601to604(refer toFIG. 6), the relative position of the detection areas can be adjusted in the X-axis direction.

In exposure apparatus100, as each of alignment systems AL1and AL21to AL24, for example, an FIA (Field Image Alignment) system by an image processing method is used The imaging signals from each of alignment systems AL1and AL21to AL24are supplied to main controller20, via a signal processing system (not shown).

Moreover, in exposure apparatus100, a multiple point focal point position detection system (hereinafter shortly referred to as a multipoint AF system) AF (not shown inFIG. 1, refer toFIG. 6) by the oblique incidence method having a similar configuration as the one disclosed in, for example, U.S. Pat. No. 5,448,332 and the like, is arranged in the vicinity of projection unit PU. Detection signals of multipoint AF system AF are supplied to main controller20(refer toFIG. 6) via an AF signal processing system (not shown). Main controller20detects positional information (surface position information) of the wafer W surface in the Z-axis direction at a plurality of detection points of the multipoint AF system AF based on detection signals of multipoint AF system AF, and performs a so-called focus leveling control of wafer W during the scanning exposure based on the detection results. Incidentally, positional information (unevenness information) of the wafer W surface can be acquired in advance at the time of wafer alignment (EGA) by arranging the multipoint AF system in the vicinity of alignment systems AL1, and AL21to AL24, and at the time of exposure, the so-called focus leveling control of wafer W can be performed, using the surface position information and measurement values of an interferometer system118(refer toFIG. 6) which will be described later one Incidentally, instead of interferometer system118, measurement values of the encoder system which can measure the Z position can also be used in the focus leveling control.

Further, above reticle stage RST, as disclosed in detail in, for example, U.S. Pat. No. 5,646,413 and the like, a pair of reticle alignment systems RA1and RA2by an image processing method, each of which has an imaging device such as a CCD and uses light with an exposure wavelength (illumination light IL in the present embodiment) as alignment illumination light, are placed (inFIG. 1, reticle alignment system RA2hides behind reticle alignment system RA1in the depth of the page surface). The pair of reticle alignment systems RA1and RA2is used in a reticle alignment to be described later (in the embodiment, reticle alignment also serves as a latter processing of a baseline check of primary alignment system AL1) by main controller20, in a state where measurement plate30is positioned directly below projection optical system PL, to detect a positional relation between a projection image of a pair of reticle alignment marks (omitted in drawings) formed on reticle R and a corresponding pair of reference marks RM on measurement plate30. The detection signals of reticle alignment systems RA1and RA2are supplied to main controller20(refer toFIG. 6) via a signal processing system that is not illustrated. Incidentally, reticle alignment systems RA1and RA2do not have to be arranged. In this case, it is desirable for wafer table WTB to have a detection system in which a light transmitting section (light-receiving section) is installed, to detect the projection image of the reticle alignment mark, as disclosed in, for example, U.S. Patent Application Publication No. 2002/0041377 and the like.

As shown inFIG. 3, interferometer system118is equipped with a Y interferometer16, three X interferometers126to128, and a pair of Z interferometers43A and43B that irradiate interferometer beams (measurement beams) on reflection surfaces17aor17b, respectively, and receive the reflected light.

To enter the details, Y interferometer16irradiates at least three measurement beams parallel to the Y-axis including a pair of measurement beams B41and B42which is symmetric with respect to reference axis LV on reflection surface17aand a movable mirror41to be described later on). Further, X interferometer126irradiates at least three measurement beams parallel to the X-axis including a pair of measurement beams B51and B52which is symmetric with respect to a straight line (hereinafter referred to as a reference axis) LH orthogonal to optical axis AX and reference axis LV and parallel to the X-axis on reflection surface17b, as shown inFIG. 3. Further, X interferometer127irradiates at least two measurement beams parallel to the Y-axis including a measurement beam B6whose measurement axis is a straight line (hereinafter referred to as a reference axis) LA which is orthogonal to reference axis LV at the detection center of alignment system AL1and is parallel to the X-axis, on reflection surface17b. Further, X interferometer128irradiates a measurement beam B7which is parallel to the Y-axis on reflection surface17b.

Each interferometer configuring interferometer system118receives the return beam from a corresponding reflection surface, and supplies an intensity signal (an output signal) of the return beam (or to be more precise, an interference beam of the measurement beam (measurement beam) and the reference beam) to main controller20(refer toFIG. 6), via a signal processing device160(refer toFIG. 6). Main controller20obtains displacement of wafer table WTB (wafer stage WST) related to each measurement direction using the output signal of each interferometer which has been supplied, and obtains positional information (including rotation in the X, Y, and θz directions (yawing), rotation in the θx direction (pitching), and rotation in the θy direction (rolling) as well) of wafer table WTB (wafer stage WST) using the displacement information.

Further, as shown inFIG. 1, movable mirror41having a concave-shaped reflection surface is attached to the side surface on the −Y side of stage main section91. As it can be seen fromFIG. 2, the length in the X-axis direction of movable mirror41is longer than reflection surface17aof wafer table WTB.

A pair of Z interferometers43A and43B (refer toFIGS. 1 and 3) that configures a part of interferometer system118(refer toFIG. 6) is arranged facing movable mirror41. Z interferometers43A and43B, for example, irradiate two measurement beams B1and B2that are parallel to the Y-axis on fixed mirrors47A and47B, respectively, which are fixed on the mainframe (not shown) supporting projection unit PU, via movable mirror41. And by receiving each reflected light, Z interferometers43A and43B measure the optical path length of measurement beams B1and B2. The results are sent to main controller20(refer toFIG. 6) via signal processing device160, and positional information of wafer stage WST in directions of four degrees of freedom (in each of the Y-axis, Z-axis, θy, and θz directions) is obtained. The computation method of the position of the wafer stage based on Z interferometers43A and43B and the measurement values is disclosed in detail, for example, in U.S. Patent Application Publication No. 2009/0040488.

In exposure apparatus100of the embodiment, a plurality of head units configuring encoder system150to measure the position of wafer stage WST within the XY plane, or in other words, the position (hereinafter shortly referred to as position (X, Y, θz) in the XY plane, as appropriate) in each of the X-axis, the Y-axis, and the θz directions, is provided, independently from interferometer system118.

As shown inFIG. 4, four head units62A,623,62C and62D are placed on the +X side, the +Y side, and the −X side of projection unit PU, and the −Y side of primary alignment system AL1, respectively. Further, head units62E and62F are provided, respectively, on the outer side on both sides in the X-axis direction of alignment system AL1and AL21to AL24. Head units62A to62F are fixed to the mainframe (not shown) holding projection unit PU in a suspended state, via a support member. Further, inFIG. 4, a reference code UP indicates an unloading position where a wafer on wafer table WTB is unloaded, and a reference code LP indicates a loading position where a new wafer is loaded on wafer stage WST.

Head units62A and62C are equipped with a plurality of (five, in this case) Y heads651to655and641to645, as shown inFIG. 5, respectively, which are placed on reference axis LH previously described at a predetermined distance. Hereinafter, heads651to655and heads641to645will also be described as head65and head64, respectively, as necessary.

Head units62A and62C respectively constitute multiple-lens Y linear encoders70A and70C (refer toFIG. 6) that measure the position (Y position) of wafer stage WST (wafer table WTB) in the Y-axis direction, using Y scales39Y1and39Y2. Incidentally, in the description below, the Y linear encoders will be shortly described as “Y encoder” or “encoder,” appropriately.

As shown inFIG. 5, head unit62B is placed on the +Y side of projection unit PU, and is equipped with a plurality of (in this case, four) X heads665to668that are placed on reference axis LV at a distance WD. Further, head unit62D is placed on the −Y side of primary alignment system AL1, and is equipped with a plurality of (in this case, four) X heads661to664that are placed on reference axis LV at distance WD. In the following description, X heads665to668and X heads661to664are also described as X head66, when necessary.

Head units62B and62D respectively constitute multiple-lens Y linear encoders70B and70D (refer toFIG. 6) that measure the position (X position) of wafer stage WST (wafer table WTB) in the X-axis direction, using X scales39X1and39X2. Incidentally, in the description below, the X linear encoders will be shortly described as “X encoder” or “encoder,” appropriately.

Distance WD in the X-axis direction of each of the five Y heads65and64(to be more accurate, the irradiation point on the scale of the measurement beam generated by Y heads65and64) that head units62A and62C are equipped with, here, is decided so that on exposure and the like, at least one head constantly faces (irradiates a measurement beam on) the corresponding Y scales39Y1and39Y2. Similarly, distance WD in the Y-axis direction of each of the adjacent X heads66(to be more accurate, the irradiation point on the scale of the measurement beam generated by X heads66) that head units628and62D are equipped with, is decided so that on exposure and the like, at least one head constantly faces (irradiates a measurement beam on) the corresponding X scale39Y1or39X2.FIG. 7Ashows a state during the exposure operation, and in this state, Y heads653and643face Y scales39Y1and39Y2, respectively, and X head665faces (irradiates a measurement beam on) X scale39X1.

Incidentally, the distance between X head665farthest to the −Y side of head unit62B and X head664farthest to the +Y side of head unit62D is set slightly narrower than the width of wafer table WTB in the Y-axis direction so that switching (linkage described below) becomes possible between the two X heads when wafer stage WST moves in the Y-axis direction.

Head unit62E is equipped with a plurality of (in this case, four) Y heads671to674, as shown inFIG. 5.

Head unit62F is equipped with a plurality of (in this case, four) Y heads681to684. Y heads681to684are placed at positions symmetric to Y heads674to671with respect to reference axis LV. Hereinafter, Y heads671to674and Y heads681to684will also be described as Y head67and Y head68, as necessary.

On alignment measurement and the like, at least one each of Y heads67and68face Y scales39Y2and39Y1, respectively.FIG. 7Bshows a state during the alignment measurement, and in this state, Y heads673and682face Y scales39Y2and39Y1, respectively. The Y position (and θz rotation) of wafer stage WST is measured by Y heads67and68(more specifically, Y encoders70E and70F configured by Y heads67and68).

Further, in the embodiment, at the time of baseline measurement and the like of the secondary alignment system, Y head673and682which are adjacent to the secondary alignment systems AL21and AL24in the X-axis direction face a pair of reference gratings52of FD bar46, respectively, and by Y heads673and682that face the pair of reference gratings52, the position of FD bar46is measured at the position of each reference grating52. In the description below, the encoders configured by Y heads673and682which face a pair of reference gratings52, respectively, are referred to as Y linear encoders705and70F (refer toFIG. 6). Further, for identification, the Y encoders configured by Y heads67and68that face Y scales39Y2and39Y1, will be referred to as encoders70E1and70F1.

As the heads of encoders70A to70F, as an example, a diffraction interference type encoder head is used, as in the encoder head disclosed in U.S. Pat. No. 7,238,931, or in U.S. Patent Application Publication No. 2007/0288121 and the like.

In the diffraction interference type encoder head, as is known, by a scale (wafer table WTB to which scale39X1,39X2,39Y1or39Y2is fixed) moving in the measurement direction (the periodic direction of the diffraction grating), a phase difference between two measurement beams changes, which changes the intensity of the interference light. Accordingly, the positional information of the scale (in other words, wafer table WTB (wafer stage WST)) can be obtained from the intensity change of the interference of light that has been detected.

Each of the encoders70A to70F configuring encoder system150sends an intensity signal (output signal) of the interference light that has been detected to signal processing device160(refer toFIG. 6). Signal processing device160processes the output signal, and then sends the signal to main controller20(refer toFIG. 8). Main controller20obtains the displacement of the scale regarding the measurement direction (the periodic direction of the diffraction grating) using an output signal from each encoder70A to70F, and using the displacement information, obtains positional information (including the X, Y positions and rotation in the82direction (that is, yawing)) of wafer table WTB (wafer stage WST) Incidentally, details on the signal processing by signal processing device160and computation of the positional information (X, Y, and θz positions) by main controller20will be described later in the description.

Main controller20controls the position of wafer table WTB within the XY plane using three output signals of encoders70A to70D, or of encoders70E1,70F1,70B, and70D, as well as controls the rotation in the θz direction of FD bar46(wafer table WTB) based on the output signals of encoders70E2and70F2.

FIG. 6shows a block diagram that shows input/output relations of main controller20that is configured of a control system of exposure apparatus100as the central component and performs overall control of the respective components. Main controller20includes a work station (or a microcomputer), and has overall control over the entire apparatus.

Next, a drive (position control) of wafer stage WST employed in exposure apparatus100of the first embodiment which uses a hybrid method by encoder system150and interferometer system118will be described.

In the drive (position control) of wafer stage WST by the hybrid method in the first embodiment, signal processing device160synthesizes (makes) a hybrid signal from an output signal of the interferometer (interferometer system118) and an output signal of the encoder (encoder system150) using a high-pass filter and a low-pass filter of a cut-off frequency fc, and wafer stage WST is driven based on the hybrid signal.

FIG. 8shows an example of signal processing device160in a block diagram. Now, the synthesis of the hybrid signal by signal processing device160will be described. As an example, here, a case will be considered where a hybrid signal fHY(t) is made by synthesizing an output signal fIY(t) of Y interferometer16configuring interferometer system118and an output signal fEY(t) of Y linear encoder70A configuring encoder system150. Here, Laplace transform (F(s)=∫o∞f(t)e−stdt) of the three signals fIY(t), fEY(t), and fHY(t) will be expressed as FIY(s), FEY(s), and FHY(s), respectively. Incidentally, t is time, s=iω=12 πf, and f is frequency.

Incidentally, by placing Y head65configuring Y linear encoder70A in the manner previously described, at least one Y head65constantly faces Y scale39Y1. Accordingly, from one of the Y heads65facing Y scale39Y1according to the position of wafer stage WST, an intensity signal of the interference light signal is sent to signal processing device160as output signal fEY(t) of Y linear encoder70A.

Further, the amplitude and phase of each of the output signals of Y heads65are to be adjusted so as to coincide with each other. Accordingly, even if Y head65is switched according to the position of wafer stage WST, the continuity of output signal fEY(t) of Y linear encoder70A will be sufficiently secured. Further, the output signal fEY(t) of Y linear encoder70A and the output signal fIY(t) of Y interferometer16, respectively, are to be adjusted so that the amplitude, phase, and period (an oscillatory period which results from a measurement unit) coincide with each other.

Signal processing device160puts output signal FIY(s) of Y interferometer16(interferometer system118) and output signal FEY(s) of Y linear encoder70A (encoder system150), respectively, through high pass filter Hfc(s) and low pass filter Lfc(s) of cutoff frequency fc, as shown inFIG. 8, and synthesizes the signals. This allows hybrid signal FHY(s) to be obtained in the manner described below.
FHY(s)=Hfc(s)FIY(s)+Lfc(s)FEY(s)  (1)

As high pass filter Hfc(s) and low pass filter Lfc(s), for example, RC circuit type filters Hfc(s)=(s/ωc)/(1+s/ωc) and Lfc(s)=1/(1+s/ωc) can be adopted. However, ωc=2 πfc.FIG. 10shows a frequency characteristic (frequency dependency of a gain of an input/output signal) of these filters Hfc(s) and Lfc(s). High pass filter Hfc(s) provides a gain (absolute value) of 1 in a frequency band (f>fc) which is higher than cut-off frequency fc, and provides a gain (absolute value) of 0 in a low frequency band (f<fc). On the other hand, low pass filter Lfc(s) provides a gain (absolute value) of 0 in a frequency band (f>fc) which is higher than cut-off frequency fc, and provides a gain (absolute value) of 1 in a low frequency band (f<fc). Incidentally, in this case, because cutoff frequency of high pass filter Hfc(s) and low pass filter Lfc(s) was equally determined as fc, the following relation is satisfied for an arbitrary frequency f.
Hfc(s)+Lfc(s)=1  (2)
Now, high pass filter Hfc(s) and low pass filter Lfc(s) both provide a gain (absolute value) of 0.5, at frequency f=fc.

Frequency f (oscillatory period l/f) of output signal fIY(t) of Y interferometer16and output signal fEY(t) of Y linear encoder70A changes in proportion to (inversely proportional to) speed Vy of wafer stage WST in the Y-axis direction. Accordingly, in the case speed Vy is higher than a threshold speed Vc which corresponds to cutoff frequency fc, hybrid signal FHY(s) expressed by formula (1) becomes output signal FIY(s) of Y interferometer16that passes through high pass filter Hfc(s), and in the case speed Vy is lower than threshold speed Vc, hybrid signal FHY(s) becomes output signal FIY(s) of Y linear encoder70A that passes through low pass filter Lfc(s).

Now, a behavior of hybrid signal fHY(t) to a temporal change of speed Vy of wafer stage WST shown inFIG. 11Awill be considered. Wafer stage WST begins acceleration in the Y axis direction at time t0(=0), and reaches maximum speed Vmax after time Ta+Tb has passed, at time t2. Then, wafer stage WST moves at a constant speed until time Tc has passed, to time t3, and then begins deceleration.

In correspondence with this, output signal FIY(t) of Y interferometer16and output signal fEY(t) of Y linear encoder70A temporally change, as is schematically shown inFIG. 11B. However, in convenience of illustration, the oscillatory period of output signals fIY(t) and fEY(t) is illustrated much longer than the actual oscillatory period. Further, the measurement results of Y interferometer16and Y linear encoder70A actually include minute measurement errors, however, details of such measurement errors are omitted inFIG. 11B(and inFIG. 11C). Therefore, inFIG. 11B, output signals fIY(t) and fEY(t) overlap each other.

Output signals fIY(t) and fEY(t) begin oscillation due to wafer stage WST, which begins acceleration (speed Vy increases) at time t0(=0). With the increase of speed Vy, oscillation of output signals fIY(t) and fEY(t) also becomes faster (the oscillatory period becomes shorter), and when speed Vy reaches maximum speed Vmax after time Ta+Tb passes and becomes constant, output signals fIY(t) and fEY(t) perform constant oscillation (the oscillatory period becomes constant 1/fmax) at a maximum frequency fmax which corresponds to maximum speed Vmax.

Here, cut-off frequency fc of high pass filter Hfc(s) and low pass filter Lfc(s) is to be determined slightly smaller than maximum frequency fmax, as shown inFIG. 11A. As shown inFIG. 11C, from time t0(=0) until time t1when frequency f of output signals fIY(t) and fEY(t) coincides with cut-off frequency fc, output signal fIY(t) is cut off by high pass filter Hfc(s), and output signal fEY(t) passes through low pass filter Lfc(s) and is output as hybrid signal fHY(t). When frequency f exceeds cut-off frequency fc at time t1, output signal FIY(t) is cut off by low pass filter Lfc(s), and output signal fIY(t) passes through high pass filter Hfc(s) and is output as hybrid signal fHY(t).

Here, the frequency characteristic (gain of input/output signal) of filters Lfc(s) and Hfc(s) varies continuously with respect to frequency f (refer toFIG. 10), as is previously described. However, in this case, the variation band is set sufficiently narrow. Therefore, it appears that output signal fEY(t) is cut off by low pass filter Lfc(s) and the cut off of output signal fIY(t) is cancelled by high pass filter Hfc(s) instantly.

By wafer stage WST beginning deceleration (speed Vy decreases) at time t3after time Ta+Tb+Tc has passed, oscillation of output signal fIY(t) and fEY(t) also becomes slow (the oscillatory period becomes longer). Now, when frequency f becomes smaller than cut-off frequency fc at time t4, as shown inFIG. 11C, output signal fIY(t) is cut off by high pass filter Hfc(s) again, and output signal fEY(t) passes through low pass filter Lfc(s) and is output as hybrid signal fHY(t).

Furthermore, when speed Vy reaches speed Vy<0 at time t5, oscillation of output signals fIY(t) and fEY(t) is reversed. Further, when frequency f exceeds cut-off frequency −fc (f<fc) at time t6, output signal fEY(t) is cut off by low pass filter Lfc(s), and output signal fIY(t) passes through high pass filter Hfc(s), and is output as hybrid signal fHY(t).

InFIGS. 12A and 12B, as an example, noise included in hybrid signal fHY(t) at the time of low frequency (f<fc) and at the time of high frequency (f>fc) is shown, respectively. It can be seen that the amplitude of the noise becomes small at the time of high frequency, whereas the amplitude is large at the time of low frequency. In other words, at the time of low frequency, noise which is caused by a measurement error (mainly a production error of the scale) of Y linear encoder70A appears, whereas noise which is caused by a measurement error (a fluctuation error) of Y interferometer16appears at the time of high frequency. Incidentally, the amplitude (the scale of the vertical axis of the graph) of the noise is in the order of 1 ppb.

Incidentally, by using Hfc(s)=1−Lfc(s), which is a transformation of formula (2), formula (1) can be rewritten as follows.
FHY(s)=FIY(s)−Lfc(s)(FIY(s)−FEY(s))  (3)
In other words, as shown inFIG. 9A, hybrid signal FHY(s) can also be synthesized by obtaining a difference FHY(s)−FEY(s) which is the difference between output signal FIY(s) and output signal FEY(s) putting the difference through low pass filter Lfc(s) of cutoff frequency fc, and then by further obtaining a difference between the difference and output signal FIY(s).

Further, by using Lfc(s)=1−Hfc(s), which is a transformation of formula (2), formula (1) can be rewritten as follows.
FHY(s)=FEY(s)−Hfc(s)(FIY(s)−FEY(s))  (4)
In other words, as shown inFIG. 9B, hybrid signal FHY(s) can also be synthesized by obtaining a difference FIY(s)−FEY(s) which is the difference between output signal FIY(s) and output signal FEY(s), putting the difference through high pass filter Hfc(s) of cutoff frequency fc, and then by further obtaining a sum of the difference and output signal FEY(s).

Signal processing device160transfers hybrid signal FHY(s) obtained in the manner described above to main controller20as a measurement result of Y linear encoder70A. Further, signal processing device160also synthesizes output signals from other encoders70B to70F with output signals of the corresponding interferometers in a similar manner, and transfers the hybrid signals which have been obtained as measurement results of encoders70B to70F to main controller20(refer toFIG. 6).

The output signals of encoders70A to70F reflect a position (displacement) of wafer stage WST (to be more precise, the corresponding scale) in their respective measurement directions. Therefore, main controller20converts the output signals of encoders70A to70F into position (X, Y, θz) of wafer stage WST in the XX plane in such measurement directions. Main controller20drives (controls the position of) wafer stage WST1, based on the position (X, Y, θz) obtained above. Further, main controller20dobtains the position of FD bar46from the output signals of encoders70E2and70F2, and controls the rotation of FD bar46(wafer stage WST) in the θz direction according to the results.

In exposure apparatus100of the first embodiment, a series of processing operations like the ones described below is performed according to a procedure almost the same as in a normal scanning stepper. In other words,a) when wafer stage WST is at an unloading position shown inFIG. 4, wafer W is unloaded, and when wafer stage WST has moved to a loading position LP shown inFIG. 4, a new wafer W is loaded on wafer table WTB. In the vicinity of unloading position Up and loading position LP, the position of wafer stage WST in directions of six degree of freedom is controlled, based on the measurement values of interferometer system118. At this point, X interferometer128is used.

In parallel with the wafer exchange described above being performed, a baseline measurement of the secondary alignment systems AL21to AL24is performed. This baseline measurement is performed using alignment systems AL1and AL21to AL24and simultaneously measuring reference marks M on FD bar46within each of the fields in a state where the θz rotation of FD bar46is adjusted, based on the measurement values of encoders70E2and70F2previously described, as in the method disclosed in, U.S. Patent Application Publication No. 2008/0088843 described above.b) After wafer exchange and the baseline measurement of secondary alignment systems AL21to AL24has been completed, wafer stage WST is moved and a former processing of a baseline check of primary alignment system AL1where fiducial marks FM on measurement plate30are detected by primary alignment system AL1is performed. Around the time of this processing, resetting (reset) of the origin of encoder system150and interferometer system118is performed.c) Then, alignment measurement is performed in which alignment marks on a plurality of sample shot areas on wafer W are detected using alignment systems AL1, and AL21to AL24, while measuring the position of wafer stage WST in directions of six degrees of freedom using encoder system150and interferometer system118. When wafer stage WST moves in the +Y direction for alignment measurement, and measurement plate30reaches a position right under projection optical system PL, a latter processing of the baseline check of primary alignment system AL1, or in other words, reticle alignment is performed in which a positional relation between a center of a projection area of a pattern of reticle R and a reference position on the Measurement plate, or more specifically, a center of the pair of reference marks RM used for reticle alignment, is detected by projection optical system PL, by main controller20detecting a projected image of a pair of reticle alignment marks (omitted in drawings) formed on reticle R and the corresponding pair of reference marks RM used for reticle alignment on measurement plate30via projection optical system PL. Incidentally, the former processing and the latter processing (reticle alignment) of the base line check of primary alignment system AL1can be reversed in order.d) Then, when the alignment measurement is completed, the plurality of shot areas on wafer W is exposed by the step-and-scan method based on the positional information of each shot area on the wafer obtained as a result of the alignment measurement and the latest baseline of the alignment system, and a pattern of reticle R is transferred.

On exposure of the plurality of shot areas on wafer W by the step and scan method described above, drive (position control) of wafer stage WST is performed using the hybrid method previously described. On this drive, wafer stage WST performs a movement operation (a stepping operation) between shot areas along a U shaped path, as is disclosed in, for example, U.S. Patent Application Publication No. 2003/0128348 and the like. As a consequence, as for the Y-axis direction which is the scanning direction, wafer stage WST is driven according to a temporal change of speed as shown inFIG. 11Apreviously described, by hybrid signal fHY(t). Accordingly, at time Tc when wafer stage WST moves at a constant speed at maximum speed Vmax, scanning exposure is performed with reticle stage RST being driven in sync with wafer stage WST. And, at the time of this scanning exposure, the output signal of the interferometer (interferometer system118) is used for the drive (position control) of wafer stage WST, whereas at the time of the stepping operation before and after the scanning exposure, the output signal of the encoder (encoder system150) is used.

Here, details will be further described on the advantage of the drive (position control) of wafer stage WST by the hybrid method in the first embodiment.

In the diffraction interference type encoder used in exposure apparatus100, since the optical path lengths of the two diffraction beams which are made to interfere are extremely short and are also almost equal to each other, the influence of air fluctuation can mostly be ignored when compared with an interferometer. Accordingly, by using encoder system150(encoders70A to70F), in principle, wafer stage WST can be driven (the position controlled) with high accuracy. Further, because the encoder uses a scale, the encoder is superior to the interferometer from the viewpoint of measurement reproducibility. However, because of production errors and mechanical, instabilities (drift of grating pitch, fixed position drift, thermal expansion and the like) of the scale, the encoder is inferior to the interferometer from the viewpoint of linearity.

In the drive (position control) of wafer stage WST using encoder system150, as for the true position (actual position) of wafer stage WST and (the measurement results of) the position of wafer stage WST measured by encoder system150, the track of the actual position of wafer stage WST fluctuates minutely when the movement track of wafer stage WST corresponding to the measurement results of encoder system150serves as a reference, due to measurement errors which are caused by production errors and the like of the scale. Therefore, when wafer W shown inFIG. 13Ais exposed by the step-and-scan method, it can be expected that the array of the shot areas arranged on the surface of wafer W will be altered (that is, a grid error occurs), and the shape of the shot areas will also be distorted (that is, a formation error of the pattern occurs), as shown inFIG. 13Bwhich shows an enlarged view of a range surrounded by a reference code SS inFIG. 13A.

Further, in encoder system150, the encoder heads facing the scales are switched and used, according to the position of wafer stage WST. When switching the encoder heads, a linkage process to secure the continuity of the measurement results of encoder system150is performed, as is disclosed in, for example, U.S. Patent Application Publication No. 2009/0027640 and the like. In this case, when an operation error (a linkage error) occurs in this linkage process, the measurement results are discontinuously altered, which in turn makes the actual position of wafer stage WST become discontinuously altered (the track is discontinuously uneven) Accordingly, when a linkage error occurs at the time of scanning exposure, it can be expected that a crack (more specifically, a crack of the pattern) will occur in the shot area as shown inFIG. 13B.

Further, by foreign materials such as dust, flaws and the like adhering on the scale surface and scanning such foreign materials, output signals from an encoder (a head) can be cut off momentarily, or an abnormal signal can be output. When such an inconvenience occurs at the time of scanning exposure, it can be expected that a crack of the pattern will Occur as in the case described above. Now, in the case of a liquid immersion exposure apparatus disclosed in, for example, PCT International Publication No. 99/49504 and the like, the liquid (liquid immersion liquid) supplied between a projection optical system and a wafer may remain on the scale, and because the remaining liquid immersion liquid serves as a foreign material, a crack of the pattern, discontinuously and the like can easily occur.

Accordingly, at the time of scanning exposure to each shot area, it is desirable to use a stable position measuring instrument (position measuring system) which is superior in linear measurement and whose temporal change of the output signals is moderate at the time of abnormality generation, or which does not cause an abnormal operation which is accompanied by a temporal change of the output signals. In this viewpoint, it is desirable to use an interferometer (interferometer system118) at the time of scanning exposure as in the drive (position control) of wafer stage WST using the hybrid method in the first embodiment. This is because the time scale of air fluctuation which becomes a factor of measurement errors of the interferometer is relatively long compared to the time scale when performing scanning exposure on one shot area, and the fluctuation error (or to be precise, variation of the fluctuation error within the scanning exposure time) is not always large when it is limited to the time of performing scanning exposure on one shot area.

Accordingly, in the first embodiment, because the linear measurement of the position of wafer stage WST at the time of scanning exposure is secured, distortion of the shape of the shot area, or in other words, the formation error of the pattern is canceled as shown inFIG. 13C.

Meanwhile, at the time of stepping between the shot areas, it is desirable to use a position measuring instrument (position measuring system) which is not affected by the air fluctuation and is also superior in measurement reproducibility, in order to precisely align each shot area on the wafer to the exposure position according to the alignment results and to improve the overlay accuracy. In this viewpoint, it is desirable to use an encoder (encoder system150) at the time of stepping, as in the drive (position control) of wafer stage WST using the hybrid method in the first embodiment. Distortion of the shot areas arranged caused by the measurement errors of encoder system150, or in other words, grid errors, can easily be canceled by correcting the acceleration starting position with respect to each of the shot areas due to the high measurement reproducibility of encoder system150.

However, especially in the exposure apparatus previously described using the liquid immersion exposure method, it is desirable to use a position measuring instrument (position measuring system) which is slow in temporal change of output signals at the time of abnormality generation, or a position measuring instrument whose temporal change of the output signals does not cause a notable abnormal operation so as to drive (control the position of) wafer stage WST in a stable manner. In this viewpoint, it is favorable to use the interferometer (interferometer system118).

Incidentally, an offset for each of the X-axis direction, the Y-axis direction, and the θz direction of the acceleration start position are to be obtained in advance with respect to all of the shot areas. At the time of stepping, a target position to drive wafer stage WST to the next acceleration starting position, or in other words, the shot arrangement (the position of the individual shot areas) obtained by an alignment measurement is corrected, using the offset. This allows the acceleration starting position to be corrected, which in turn allows the remaining grid errors to be canceled easily. In addition, grid errors can be canceled, for example, as is disclosed in, for example, U.S. Patent Application Publication No. 2007/0260419 and the like, by driving a lens element configuring projection optical system PL, or by finely correcting the synchronous drive of reticle stage RST and wafer stage WST.

Incidentally, it is also possible to used positional information (hybrid positional information) of wafer stage WST obtained from a hybrid signal in the alignment measurement (for example, EGA measurement). In other words, in wafer stage control system124, wafer stage WST is driven based on the first current position (fI) measured by interferometer system118, and alignment marks (sample marks) in a plurality of sample shot areas on wafer W are detected, using alignment systems AL1and AL21to AL24. On this detection, main controller20computes the position of each sample mark, based on measurement results (position (Δx, Δy) of each sample mark whose origin is the detection center of each alignment system) of each sample mark measured by alignment systems AL1and AL21to AL24, respectively, and hybrid positional information (fH) which is the output of signal processing device160. In this case, because the position detection of each sample mark is performed in a state (a positioning servo state based on the interferometer measurement values at the positioning target position) where wafer stage WST is positioned, the hybrid positional information (fH) described above is the second current position (fE), measured by encoder system150. In other words, measurement errors of interferometer system118due to air fluctuation are not included in the detection results of the position of each sample mark. Further, at the detection position of each sample mark, main controller20can easily obtain an error between the first current position measured by interferometer system118and hybrid positional information, namely, the second current position measured by encoder system150. And, on exposure of each of the plurality of shot areas by the step-and-scan method, main controller20moves wafer stage WST to a scanning starting position (an acceleration starting position) for exposure of each shot area based on the first current position (fI) measured by interferometer system118, and in doing so, the target position when moving wafer stage WST is corrected by the error amount described above. This allows each shot area on wafer W to be positioned accurately at a proper target position (a target position which does not include the effect of the measurement errors of interferometer system118due to air fluctuation) obtained from the measurement results of the sample marks, while carrying out a servo control of wafer stage WST by interferometer system118.

Further, not only on alignment measurement but also on measurement and the like of optical properties of projection optical system PL, a measurement mark with respect to hybrid positional information is detected using a measuring instrument provided on wafer stage WST and the like and detection results are processed, while driving wafer stage WST using an output signal of interferometer system118. This allows wafer stage WST to be driven in a stable manner on measurement, and also makes it possible to accurately align the pattern to each of the plurality of shot areas on exposure.

As described above, according to exposure apparatus100of the first embodiment, a hybrid signal is made by synthesizing the output signal of an interferometer (interferometer system118) and the output signal of an encoder (encoder system150) which are made to pass through a high pass filter and a low pass filter, respectively, and wafer stage WST is driven (position control performed) based on the hybrid signal that has been made. The cutoff frequency of a high pass filter and the low pass filter in this case, is set to a frequency corresponding to a speed slightly smaller than the speed of wafer stage WST at the time of the scanning exposure. This allows wafer stage WST to be driven based on the output signal of the interferometer (interferometer system118) whose linear measurement is high at the time of scanning exposure (when the speed of wafer stage WST is higher than a threshold speed corresponding to the cutoff frequency), and also allows wafer stage WST to be driven based on the output signal of the encoder (encoder system150) whose measurement reproducibility is high at the time of stepping (when the speed of wafer stage WST is lower than the threshold speed). Accordingly, it becomes possible to linearly drive wafer stage WST at a constant speed quickly and with high precision, as well as drive wafer stage WST precisely to the starting position of the constant speed drive, which in turn allows a pattern to be formed by accurately overlaying the pattern in each of a plurality of shot areas arranged on a wafer.

Further, because wafer stage WST is driven and controlled using the output signal of the interferometer (interferometer system118) at the time of scanning exposure, measurement errors caused by switching a head in encoder system150, scanning a foreign material adhered on the scale and the like, especially variation of a discontinuous measurement result will not occur. Accordingly, an accurate pattern transfer without any distortion, crack and the like becomes possible.

Further, because wafer stage WST is driven based on the output signal of the encoder (encoder system150) at the time of stepping between shots, the pattern can be aligned to the shot areas with good reproducibility, as is described above. In this case, while distortion of the shot areas arranged occurring due to the measurement errors of encoder system150, or in other words, grid errors may remain, the errors can easily be canceled by correcting the results of the alignment measurement due to the high measurement reproducibility of encoder system150.

Further, in exposure apparatus100of the first embodiment, main controller20performs alignment measurement using alignment systems AL1and AL21to AL24, while driving wafer stage WST based on the output (measurement results) of the interferometer (interferometer system118). In this case, alignment marks are detected with respect to positional information (hybrid positional information) of wafer stage WST obtained by the hybrid signal described above, and are processed. Based on such detection results, the accurate target position of the plurality of shot areas on wafer W are computed, and wafer stage WST is aligned with respect to a true target position while a servo control of wafer stage WST is performed based on the measurement results of interferometer system118, and the plurality of shot areas on wafer W are exposed by the step-and-scan method. Accordingly, wafer stage WST can be driven in a stable manner on alignment measurement. Further, it becomes possible to accurately align a pattern to each of the plurality of shot areas when a pattern is transferred.

Second Embodiment

Next, a second embodiment will be described. Here, the same reference numerals will be used for the same or similar sections as in the first embodiment previously described, and a detailed description thereabout will be simplified or omitted.

In the exposure apparatus of the second embodiment, the configuration and the like of the apparatus is the same as exposure apparatus100of the first embodiment previously described, except for a part of a stage control system which will be described later on The description below will be focusing on a synchronous drive control of wafer stage WST and reticle stage RST employed in the exposure apparatus of the second embodiment which uses a hybrid method by encoder system150and interferometer system118.

In the synchronous drive control by the hybrid method in the exposure apparatus of the second embodiment, signal processing device160synthesizes (makes) a hybrid signal from an output signal of the interferometer (interferometer system118) and an output signal of the encoder (encoder system150) using a high-pass filter and a low-pass filter of a cut-off frequency fc, and the synchronous drive of wafer stage WST and reticle stage RST is controlled based on the hybrid signal.

As in the first embodiment previously described, output signals from encoders70A to70F are synthesized with the output signals of the corresponding interferometers by signal processing device160, and hybrid signals FHY(s) which have been obtained are sent to main controller20as measurement results of encoders70A to70F (refer toFIG. 6).

The output signals of encoders70A to70F reflect a position (displacement) of wafer stage WST (to be more precise, the corresponding scale) in their respective measurement directions. Therefore, main controller20converts the output signals of encoders70A to70F into position (X, Y, θz) of wafer stage WST in the XY plane in such measurement directions. Main controller20controls the synchronous drive of wafer stage WST and reticle stage RST, using information (referred to as hybrid positional information) on the position of wafer stage WST (X, Y, and θz) obtained from the hybrid signals as is described above.

FIG. 14is a block diagram showing an arrangement of a stage control system, which performs a drive (position control) of wafer stage WST and reticle stage RST including control and the like of the synchronous drive of wafer stage WST and reticle stage RST using the hybrid positional information.

The stage control system is equipped with a target value output section120which outputs a target position Stargetof wafer stage WST, a first position error computing section119which computes an error (a deviation signal) between target position Stargetand a first current position of wafer stage WST measured by interferometer system118, a wafer stage control system121which controls the movement of wafer stage WST using the error (deviation signal) computed by the first position error computing section119as an operation signal, a signal processing device160to which the first current position of wafer stage WST measured by interferometer system118and a second current position of wafer stage WST measured by encoder system150are input, a second position error computing section123which computes an error (a deviation signal) between a target position of reticle stage RST that is 1/β times the hybrid position signal (hybrid positional information) output from signal processing device160and a current position of reticle stage RST measured by reticle interferometer116, and a reticle stage control system125which controls the movement of the reticle stage using the error (deviation signal) computed by the second position error computing section123as an operation signal.

Of each of the components described above, target value output section120, the first position error computing section119, wafer stage control system121, 1/β gain of the hybrid position signal, the second position error computing section123, and reticle stage control system125are each a part of a function of main controller20which are described as a function block. Incidentally, while signal processing device160is provided separately from main controller20, as well as this, the function of signal processing device160can also naturally be a part of a function of main controller20.

To first position error computing section119, target position Stargetof wafer stage WST is input from target value output section120, as well as the first current position of wafer stage WST measured by interferometer system118, and a position error (a deviation signal) with respect to the target position is computed and is sent to wafer stage control system121. Wafer stage control system121performs a control operation (a P or a PI operation) using the deviation signal as an operation signal, and provides a control quantity to wafer stage drive system124. Wafer stage drive system124drives wafer stage WST by generating a thrust corresponding to the control quantity which has been provided. This allows wafer stage WST to move, and the position of wafer stage WST is measured by interferometer system118, and the measurement values are fed back to the first position error computing section119previously described.

In the stage control system related to the second embodiment, relative alignment of both stages WST and RST is performed by making the reticle stage RST side follow wafer stage WST during scanning exposure of the step and scan method in the case wafer stage WST is shifted from the target position of wafer stage WST.

More specifically, in the case the reticle stage RST side is made to follow wafer stage WST, the first current position (fIYand the like previously described, referred to as fIin general) of wafer stage WST measured by interferometer system118and the second current position (fEYand the like previously described, referred to as fEin general) of wafer stage WST measured by encoder system150are input into signal processing device160. And, the hybrid position signal (hybrid positional information, namely fHYand the like, which is referred to in general as fH) previously described is synthesized by signal processing device160, multiplied by 1/β times, and then is provided to the second position error computing section123as a target position of reticle stage RST. The second position error computing section123computes a position error (a deviation signal) between the given target position of reticle stage RST and the current position of reticle stage RST measured using reticle interferometer116, and provides the position error to reticle stage control system125. Reticle stage control system125performs a control operation (a P or a PI operation) using the given deviation signal as an operation signal, and drives (controls the position of) reticle stage RST via reticle stage drive system11so that the deviation signal converges to zero.

In the control (including the control of a synchronous drive by the hybrid method) of wafer stage WST and reticle stage RST by the stage control system, because the drive (position control) of wafer stage WST is performed based on measurement values of interferometer system118, it is preferable in terms of stability. In addition, even if an error occurs in the drive (position control) of wafer stage WST by interferometer system118, because a highly precise hybrid positional information is input into reticle stage control system125as a position target value, and reticle stage RST is driven following wafer stage WST, it becomes possible to perform a relative position control (including synchronous drive) of both stages WST and RST with enough control accuracy.

In the exposure apparatus of the second embodiment as well, as in exposure apparatus100of the first embodiment previously described, a series of processing operations previously described is performed according to a procedure almost the same as in a normal scanning stepper. And, in the exposure apparatus of the second embodiment, the synchronous drive (follow-up drive) of wafer stage WST and reticle stage RST by the hybrid method previously described is performed, on exposure of the plurality of shot areas on wafer W by the step-and-scan method previously described. On this drive, wafer stage WST performs a movement operation (a stepping operation) between shot areas along a U shaped path, as is disclosed in, for example, U.S. Patent Application Publication No. 2003/0128348 and the like. As a consequence, as for the Y-axis direction which is the scanning direction, wafer stage WST is driven based on the current position measured by interferometer system118, and reticle stage RST is driven concurrently in accordance with the temporal change of speed of wafer stage WST (and reticle stage RST) shown inFIG. 11Apreviously described, by hybrid signal fHY(t). Accordingly, at time Tc when wafer stage WST moves at a constant speed at maximum speed Vmax, scanning exposure is performed with reticle stage RST being driven in sync with wafer stage WST. And, at the time of this scanning exposure, the output signal of the interferometer (interferometer system118) is used when reticle stage RST follows (controls the position of) wafer stage WST, whereas at the time of the stepping operation before and after the scanning exposure, the output signal of the encoder (encoder system150) is used.

The synchronous drive (follow-up drive) control of wafer stage WST by the hybrid method in the second embodiment has the following the advantage, in addition to the advantage of the drive (position control) of wafer stage WST by the hybrid method in the first embodiment. In other words, by employing the control of the synchronous drive of both stages WST and RST using the hybrid method described above, the follow-up drive of reticle stage RST with respect to wafer stage WST is controlled, based on measurement results of interferometer system118at the time of scanning exposure and (mainly of) encoder system150at the time of stepping (at the time of acceleration and deceleration before and after exposure), while driving (controlling the position of) wafer stage WST using interferometer system118. Accordingly, because the linear measurement of the position of wafer stage WST at the time of scanning exposure is secured, distortion of the shape of the shot area, or in other words, the formation error of the pattern is canceled as shown inFIG. 13C. Furthermore, distortion of the shot areas arranged caused by the measurement errors of encoder system150, or in other words, grid errors, can easily be canceled by correcting the acceleration starting position with respect to each of the shot areas due to the high measurement reproducibility of encoder system150.

According to the exposure apparatus of the second embodiment described so far, a hybrid signal is made by synthesizing the output signal of an interferometer (interferometer system118) and the output signal of an encoder (encoder system150) which are made to pass through a high pass filter and a low pass filter, respectively, and reticle stage RST is made to perform a follow-up drive (position control) with respect to wafer stage WST based on the hybrid signal that has been made. The cutoff frequency of a high pass filter and the low pass filter in this case, is set to a frequency corresponding to a speed slightly smaller than the speed of wafer stage WST at the time of the scanning exposure. This allows reticle stage RST to perform a follow-up drive (position control) to wafer stage WST based on the output signal of the interferometer (interferometer system118) whose linear measurement is high at the time of scanning exposure (when the speed of wafer stage WST is higher than a threshold speed corresponding to the cutoff frequency), and also allows reticle stage RST to perform a follow-up drive (position control) to wafer stage WST based on the output signal of the encoder (encoder system150) whose measurement reproducibility is high at the time of stepping (when the speed of wafer stage WST is lower than the threshold speed). Accordingly, it becomes possible to form a pattern by accurately overlaying the pattern in each of a plurality of shot areas arranged on a wafer.

Further, because reticle stage RST is made to perform a follow-up drive (position control) to wafer stage WST using the output signal of the interferometer (interferometer system118) at the time of scanning exposure, measurement errors caused by switching a head in encoder system150, scanning a foreign material adhered on the scale and the like, especially variation of a discontinuous measurement result will not occur. Accordingly, an accurate pattern transfer without any distortion, crack and the like becomes possible.

Further, because reticle stage RST is made to perform a follow-up drive (position control) to wafer stage WST based on the output signal of the encoder (encoder system150) at the time of stepping drive, the pattern can be overlaid on (aligned to) the shot areas with good reproducibility, as is described above. In this case, while distortion of the shot areas arranged occurring due to the measurement errors of encoder system150, or in other words, grid errors may remain, the errors can easily be canceled by correcting the results of the alignment measurement due to the high measurement reproducibility of encoder system150.

The exposure apparatus of each embodiment described above also has an effect described below, in addition to the effect described above. In other words, because the hybrid signal is made by synthesizing the output signal of the interferometer (interferometer system118) and the output signal of the encoder (encoder system150) that have passed through a high pass filter and a low pass filter, one of the output signal of the interferometer (interferometer system118) and the output signal of the encoder (encoder system150) is output as the hybrid signal by the function of the filter according to the speed of wafer stage WST, which is used to drive (perform position control of) wafer stage WST. Accordingly, the switching process between the interferometer (interferometer system118) and the encoder (encoder system150), and the linkage process which is performed to secure the continuity of the positional information of wafer stage WST before and after the switching will not be required, and errors (linkage errors) that accompany the linkage computing will not occur.

Incidentally, in each embodiment described above, the cutoff frequency of the high pass filter and the low pass filter was set constant. In this case, the way that measurement errors of the encoder (encoder system150) caused by a scale production error appear may change according to the speed of wafer stage WST. Therefore, the cutoff frequency can be set to fluctuate slightly, depending on the speed of wafer stage WST. While, such setting of the cutoff frequency to fluctuate is performed, for example, by an operator, the increase and decrease of the cutoff frequency corresponding to the speed of wafer stage WST in accordance with the setting can be performed by main controller20. Changing (setting) the cutoff frequency is no other than to perform a weighting of a drive period in which wafer stage WST and/or reticle stage RST is driven based on the output signals of the interferometer (interferometer system118) and a drive period in which wafer stage WST and/or reticle stage RST is driven based on the output signals of the encoder (encoder system150), and on setting the cutoff frequency, main controller20functions as a setting device which performs such weighting. Further, the high pass filter and the low pass filter can be selected appropriately, depending on the behavior of the measurement errors of the encoder (encoder system150).

Incidentally, it is a matter of course that the configuration of each measurement device such as the encoder system described in each embodiment above is a mere example. For example, in each embodiment above, an example has been described where an encoder system is employed that has a configuration where a grid section (a Y scale and an X scale) is arranged on a wafer table (a wafer stage), and an X head and a Y head facing the grid section is placed external to the wafer stage, however, the present invention is not limited to this, and as is disclosed in, for example, the U.S. Patent Application Publication No. 2006/0227309 description, an encoder system which is configured having an encoder head arranged on the wafer stage and has a grid section (for example, a two-dimensional grid, or a linear grid section having a two-dimensional placement) facing the encoder heads placed external to the wafer stage can also be adopted. In this case, a Z head (a head of a surface position sensor which measures a Z position of the wafer and the wafer table) can also be provided on the wafer stage, and the surface of the grid section can be a reflection surface on which the measurement beam of the Z head is irradiated.

Further, in each embodiment above, while the case has been described, for example, where only an encoder head was arranged inside head units62A and62C, an encoder head and a Z head can be provided separately inside each head unit, or a single head that has the function of both an encoder head and a Z head can be provided. As a single head which has the function of an encoder head and a Z head, a sensor head whose measurement direction is in one of the X-axis direction and the Y-axis direction, and the Z-axis direction can be used. As such a sensor head, a displacement measurement sensor head whose details are disclosed in, for example, U.S. Pat. No. 7,561,280, can be used.

Incidentally, in each embodiment described above, while the case has been described where the exposure apparatus was a dry type exposure apparatus that performs exposure of wafer W without liquid (water), as well as this, as is disclosed in, for example, EP Patent Application Publication No. 1,420,298, PCT International Publication No. 2004/055803, each of the embodiments described above can also be applied to an exposure apparatus which has a liquid immersion space including an optical path of the illumination light between a projection optical system and a wafer, and exposes the wafer with the illumination light via the projection optical system and the liquid in the liquid immersion space. Further, each embodiment described above can be applied to a liquid immersion exposure apparatus and the like whose details are disclosed in, for example, U.S. Patent Application Publication No. 2008/008843. In the liquid immersion exposure apparatus disclosed in U.S. Patent Application Publication No. 2008/0088843, an encoder system is employed in which a measurement beam is irradiated on a grating (scale) provided on a wafer stage, and by receiving its reflected light, a relative position between a head and a scale in a periodic direction of the grating is measured.

Further, in each embodiment described above, while a case has been described where the exposure apparatus was a scanning exposure apparatus by a step-and-scan method, as well as this, each of the embodiments above can also be applied to a reduction projection exposure apparatus by a step-and-stitch method that synthesizes a shot area and a shot area, an exposure apparatus by a proximity method, a mirror projection aligner and the like. Further, each embodiment described above can also be applied to a multi-stage type exposure apparatus equipped with a plurality of wafer stages, as is disclosed in, for example, U.S. Pat. No. 6,590,634, U.S. Pat. No. 5,969,441, U.S. Pat. No. 6,208,407 and the like.

Further, the magnification of the projection optical system in the exposure apparatus in each embodiment above is not only a reduction system, but also may be either an equal magnifying or a magnifying system, and projection optical system PL is not only a dioptric system, but also may be either a catoptric system or a catadioptric system, and in addition, the projected image may be either an inverted image or an upright image. Further, the illumination area and exposure area described above are to have a rectangular shape. However, the shape is not limited to rectangular, and can also be circular arc, trapezoidal, parallelogram or the like.

Incidentally, the light Source of the exposure apparatus in each embodiment above is not limited to the ArF excimer laser, but a pulse laser light source such as a KrF excimer laser (output wavelength: 248 nm), an F2laser (output wavelength: 157 nm), an Ar2laser (output wavelength: 126 nm) or a Kr2laser (output wavelength: 146 nm), or an extra-high pressure mercury lamp that generates an emission line such as a g-line (wavelength: 436 nm), an i-line (wavelength: 365 nm) and the like can also be used. Further, a harmonic wave generating unit of a YAG laser or the like can also be used. Besides the sources above, as is disclosed in, for example, U.S. Pat. No. 7,023,610, a harmonic wave, which is obtained by amplifying a single-wavelength laser beam in the infrared or visible range emitted by a DFB semiconductor laser or fiber laser as vacuum ultraviolet light, with a fiber amplifier doped with, for example, erbium (or both erbium and ytteribium), and by converting the wavelength into ultraviolet light using a nonlinear optical crystal, can also be used.

Further, in each embodiment above, illumination light IL of the exposure apparatus is not limited to the light having a wavelength more than or equal to 100 nm, and it is needless to say that the light having a wavelength less than 100 nm can be used. For example, each embodiment above can be suitably applied to an EUV exposure apparatus whose exposure light is an EUV (Extreme Ultraviolet) light in a soft X-ray range (e.g. a wavelength range from 5 to 15 nm) that uses a total reflection reduction optical system and a reflective mask. In addition, each embodiment above can also be applied to an exposure apparatus that uses charged particle beams such as an electron beam or an ion beam.

Further, in the embodiment above, a light transmissive type mask (reticle) is used, which is obtained by forming a predetermined light-shielding pattern (or a phase pattern or a light-attenuation pattern) on a light-transmitting substrate, but instead of this reticle, as disclosed in, for example, U.S. Pat. No. 6,778,257, an electron mask (which is also called a variable shaped mask, an active mask or an image generator, and includes, for example, a DMD (Digital Micromirror Device) that is a type of a non-emission type image display element (spatial light modulator) or the like) on which a light-transmitting pattern, a reflection pattern, or an emission pattern is formed according to electronic data of the pattern that is to be exposed can also be used.

Further, for example, each embodiment described above can also be applied to an exposure apparatus (lithography system) that forms line-and-space patterns on a wafer by forming interference fringes on the wafer.

Moreover, each embodiment described above can also be applied to an exposure apparatus that synthesizes two reticle patterns on a wafer via a projection optical system and substantially simultaneously performs double exposure of one shot area on the wafer by one scanning exposure, as disclosed in, for example, U.S. Pat. No. 6,611,316.

Further, an apparatus that forms a pattern on an object is not limited to the exposure apparatus (lithography system) described above, and for example, each embodiment described above can also be applied to an apparatus that forms a pattern on an object by an ink-jet method.

Incidentally, an object on which a pattern is to be formed an object subject to exposure to which an energy beam is irradiated) in each embodiment described above is not limited to a wafer, but may be other objects such as a glass plate, a ceramic substrate, a film member, or a mask blank.

The use of the exposure apparatus is not limited only to the exposure apparatus for manufacturing semiconductor devices, but the present invention can also be widely applied, for example, to an exposure apparatus for transferring a liquid crystal display device pattern onto a rectangular glass plate, and an exposure apparatus for producing organic ELs, thin-film magnetic heads, imaging devices (such as CCDs), micromachines, DNA chips, and the like. Further, each embodiment described above can also be applied to an exposure apparatus that transfers a circuit pattern onto a glass substrate, a silicon wafer or the like not only when producing microdevices such as semiconductor devices, but also when producing a reticle or a mask used in an exposure apparatus such as an optical exposure apparatus, an EUV exposure apparatus, an X-ray exposure apparatus, and an electron beam exposure apparatus.

Electronic devices such as semiconductor devices are manufactured through the steps of; a step where the function/performance design of the device is performed, a step where a reticle based on the design step is manufactured, a step where a wafer is manufactured from silicon materials, a lithography step where the pattern of a reticle is transferred onto the wafer by the exposure apparatus (pattern formation apparatus) in the embodiment previously described, a development step where the wafer that has been exposed is developed, an etching step where an exposed member of an area other than the area where the resist remains is removed by etching, a resist removing step where the resist that is no longer necessary when etching has been completed is removed, a device assembly step (including a dicing process, a bonding process, the package process), inspection steps and the like. In this case, in the lithography step, because the device pattern is formed on the wafer by executing the exposure method previously described using the exposure apparatus in each embodiment described above, a highly integrated device can be produced with good productivity.

Incidentally, the disclosures of all publications, the Published PCT International Publications, the U.S. Patent Applications and the U.S. patents that are cited in the description so far related to exposure apparatuses and the like are each incorporated herein by reference.

While the above-described embodiments of the present invention are the presently preferred embodiments thereof, those skilled in the art of lithography systems will readily recognize that numerous additions, modifications, and substitutions may be made to the above-described embodiments without departing from the spirit and scope thereof. It is intended that all such modifications, additions, and substitutions fall within the scope of the present invention, which is best defined by the claims appended below.