HK1214371B - Exposure method and exposure apparatus, and device manufacturing method - Google Patents

Description

Exposure method, exposure apparatus, and device manufacturing method

The present application is a divisional application of an invention patent application having an international application number of 201080037584, X, PCT, application number of 2010, 8/24, and an invention name of "exposure method, exposure apparatus, and device manufacturing method".

Technical Field

The present invention relates to an exposure method, an exposure apparatus, and a device manufacturing method, and more particularly, to an exposure method and an exposure apparatus used in a photolithography process for manufacturing microdevices (electronic devices) such as semiconductor devices, and a device manufacturing method using the exposure method or the exposure apparatus.

Prior Art

Conventionally, a projection exposure apparatus of a step & repeat (step & repeat) system (so-called stepper), a projection exposure apparatus of a step & scan (step & scan) system (so-called scanning stepper (also called scanner)), or the like has been mainly used for a photolithography process for manufacturing electronic devices (microdevices) such as semiconductor devices (integrated circuits and the like) and liquid crystal display devices.

Such an exposure apparatus is increasingly required to have high overlay accuracy (alignment accuracy) in accordance with the miniaturization of device patterns for high integration of semiconductor devices. Therefore, higher accuracy is also required for measuring the position of a substrate such as a wafer or a glass plate on which a pattern is formed.

As a device for responding to such a request, for example, patent document 1 discloses an exposure device including a position measurement system using a plurality of encoder type sensors (encoder heads) mounted on a substrate stage. In the exposure apparatus, the encoder head irradiates a measuring beam to a scale arranged to face a substrate stage and receives a return beam from the scale to measure a position of the substrate stage. In the position measurement system disclosed in patent document 1 and the like, it is preferable that the scale covers as much as possible the moving area of the substrate table except the area directly below the projection optical system. Therefore, although a large-area scale is required, it is very difficult and costly to manufacture a large-area scale with high accuracy. Therefore, a plurality of small-area rulers are generally produced by dividing the ruler into a plurality of parts, and these are combined. Therefore, although it is desirable that the alignment between the plurality of scales be performed correctly, it is actually very difficult to manufacture scales without individual errors and to add the scales without errors.

Documents of the prior art

[ patent document 1] specification of U.S. patent application publication No. 2006/0227309

Disclosure of Invention

The present invention has been made under the above circumstances, and according to the 1 st aspect, there is provided a 1 st exposure method of exposing an object, comprising: an operation of obtaining correction information of a deviation between a plurality of different reference coordinate systems corresponding to a plurality of head groups, among a plurality of heads provided on a movable body, in a 1 st movement region of the movable body that moves along a predetermined plane, the plurality of head groups to which the plurality of heads including at least one different head belong, and corresponding regions of a measurement surface that is disposed outside the movable body so as to be substantially parallel to the predetermined plane, respectively, face each other; and an operation of obtaining position information of the movable body using the plurality of heads belonging to the plurality of head groups in the 1 st movement region, and driving the movable body using the position information and correction information of a deviation between a plurality of different reference coordinate systems corresponding to the head groups of the plurality of head groups, respectively, to expose an object held on the movable body.

According to this method, the movable body can be driven with high accuracy within the 1 st movement region using the position information of the movable body obtained using the plurality of heads corresponding to each of the plurality of head groups without being affected by the deviation between the plurality of different reference coordinate systems corresponding to each of the plurality of head groups, and the object held by the movable body can be exposed with high accuracy.

According to the 2 nd aspect of the present invention, a 2 nd exposure method of exposing an object, comprising: in order to expose the object, the moving body is driven by using at least one of the 1 st position information and the 2 nd position information obtained by the 1 st head group and the 2 nd head group in accordance with the 2 nd head group, which belongs to the 1 st head group and the 2 nd head group including at least one different head, among the 1 st head group and the 2 nd head group mounted on the moving body holding the object, within a predetermined region facing the corresponding region on the measurement surface.

According to this method, even if the coordinate systems corresponding to the 1 st head and the 2 nd head are different, the movable body can be driven with high accuracy without being affected by the coordinate systems.

According to the 3 rd aspect of the present invention, the 1 st exposure apparatus that exposes an object, includes: a moving body that holds the object to move along a predetermined plane; a position measurement system that obtains position information of the movable body based on an output of a head that irradiates a measurement beam onto a measurement surface arranged substantially parallel to the predetermined plane outside the movable body in the vicinity of an exposure position to the object and receives a return beam from the measurement surface, among a plurality of heads provided on the movable body; and a control system for driving the movable body based on the position information obtained by the position measuring system, and switching the head used for obtaining the position information by the position measuring system from the plurality of heads based on the position of the movable body; the control system corrects a mutual deviation between a plurality of reference coordinate systems corresponding to the plurality of heads in a 1 st movement region of the movable body in which the plurality of heads face the measurement surface.

According to this apparatus, since the deviation between the plurality of reference coordinate systems is corrected, the positional information of the movable body can be measured with high accuracy using the plurality of heads, and driving (position control) can be performed.

According to the 4 th aspect of the present invention, there is provided a 2 nd exposure apparatus that exposes an object, comprising: a moving body that holds the object to move along a predetermined plane; a position measurement system that obtains position information of the movable body based on an output of a head that irradiates a measurement beam on a measurement surface arranged substantially parallel to the predetermined plane outside the movable body in the vicinity of an exposure position to the object and receives a return beam from the measurement surface, among the 1 st head mounted on the movable body; a drive system that drives the movable body; and a control system for controlling the drive system by using at least one of the 1 st position information and the 2 nd position information obtained by the 1 st and 2 nd head groups, based on a predetermined region in which the 2 nd head group including the 1 st head group and the 2 nd head group of the different heads and the corresponding region on the measurement surface face each other, among the 1 st head group of the position measurement system.

According to this apparatus, even if the coordinate systems corresponding to the 1 st head and the 2 nd head are different, the movable body can be driven with high accuracy without being affected by the coordinate systems.

According to the 5 rd aspect of the present invention, there is provided a 3 rd exposure apparatus for exposing an object, comprising: a moving body that holds the object to move along a predetermined plane; a position measurement system that obtains position information of the movable body based on an output of a head that irradiates a measurement beam onto a measurement surface arranged substantially parallel to the predetermined plane outside the movable body in the vicinity of an exposure position to the object and receives a return beam from the measurement surface, among a plurality of heads provided on the movable body; and a control system that drives the movable body based on the position information acquired by the position measurement system, and moves the movable body in a region where the number of head measurement positions is 2, which is larger than the number of 1 head used for position control of the movable body, so as to acquire correction information of the position information of the movable body acquired by the position measurement system.

According to this apparatus, since correction information of the positional information of the movable body obtained by the position measurement system is obtained by the control system, the movable body can be driven with high accuracy using the correction information.

According to the 6 th aspect of the present invention, there is provided a 3 rd exposure method of exposing an object, comprising: an operation of moving the movable body within a 1 st movement region of the movable body, which is a region where a plurality of heads, including at least one different head, among a plurality of heads provided on the movable body belong to the 1 st head group, and a measurement surface arranged outside the movable body so as to be substantially parallel to the predetermined plane, face each other, to acquire correction information of position information of the movable body moving along the predetermined plane, the correction information being obtained by the position measurement system; and an operation of driving the movable body using the correction information to expose the object held by the movable body.

According to this method, high-precision exposure of an object can be performed.

According to the 7 th aspect of the present invention, there is provided a 4 th exposure apparatus that exposes an object, comprising: a moving body that holds the object to move along a predetermined plane; a position measurement system that obtains position information of the movable body based on an output of a head that irradiates a measurement beam onto a measurement surface constituted by a plurality of scale plates arranged substantially parallel to the predetermined plane outside the movable body in the vicinity of an exposure position to the object, and receives a return beam from the measurement surface, among the plurality of heads provided on the movable body; and a control system that drives the movable body based on the position information acquired by the position measurement system, and switches a head used by the position measurement system for acquisition of the position information from among the plurality of heads based on a position of the movable body; the control system obtains a mutual positional relationship of a plurality of scale plates corresponding to the plurality of heads in a 1 st movement region of the movable body in which the plurality of heads face the measurement surface.

According to this apparatus, since the positional relationship between the plurality of scales is acquired by the control system, the position information of the movable body can be measured with high accuracy using the plurality of heads, and the movable body can be driven (position control).

According to the 8 th aspect of the present invention, there is provided a 4 th exposure method of exposing an object, comprising: an operation of obtaining a mutual positional relationship of a plurality of scale plates corresponding to a plurality of head groups, respectively, in a plurality of head groups to which the plurality of heads including at least one different head, among the plurality of heads provided on the movable body, respectively, belong, in a 1 st movement region of the movable body that moves along a predetermined plane, respectively, facing a measurement plane constituted by the plurality of scale plates arranged outside the movable body so as to be substantially parallel to the predetermined plane; and (2) an operation of obtaining position information of the movable body in the 1 st movement region by using the plurality of heads belonging to each of the plurality of head groups, and driving the movable body by using a mutual positional relationship between the position information and a plurality of scale plates respectively corresponding to the plurality of head groups, so as to expose an object held by the movable body.

According to this method, the movable body can be driven with high accuracy within the 1 st movement region using the position information of the movable body obtained using the plurality of heads belonging to each of the plurality of head groups without being affected by the positional deviation between the plurality of scale plates corresponding to each of the plurality of head groups, and high-accuracy exposure of the object held by the movable body can be performed.

The element manufacturing method according to the 9 th aspect of the present invention comprises: an operation of exposing an object to light using any one of the 1 st to 4 th exposure apparatuses of the present invention to form a pattern on the object; and an operation of developing the object on which the pattern is formed.

The element manufacturing method according to the 10 th aspect of the present invention comprises: an operation of forming a pattern on the object by using any one of the 1 st to 5 th exposure methods of the present invention; and developing the object on which the pattern is formed.

Drawings

Fig. 1 is a view schematically showing the configuration of an exposure apparatus according to an embodiment.

Fig. 2 is a diagram showing a configuration of an encoder system disposed around a projection optical system.

Fig. 3 is a diagram showing a configuration of an encoder system disposed around an alignment system.

Fig. 4 is an enlarged view of a portion of the wafer stage, cut away.

Fig. 5 is a diagram showing the arrangement of encoder heads on the wafer stage.

Fig. 6 is a block diagram showing a main configuration of a control system related to stage control in the exposure apparatus of fig. 1.

Fig. 7(a) is a diagram showing a relationship between the arrangement of the encoder head and the scale plate and the measurement region of the encoder system, fig. 7(B) is a diagram showing four stage coordinate systems defined in correspondence with the four groups of the encoder head facing the scale plate, and fig. 7(C) is a diagram showing a case where the four parts of the scale plate are deviated from each other.

Fig. 8 a, 8C, and 8E are diagrams (1, 2, and 3 thereof) showing the operation of the wafer stage in stage position measurement for correcting stage coordinates, and fig. 8B, 8D, and 8F are diagrams (1, 2, and 3 thereof) for explaining the correction of four stage coordinate systems.

FIG. 9(A) and FIG. 9(B) are diagrams for explaining a combined stage coordinate system C_EOrigin, rotation, scaled measured map.

FIG. 10(A) and FIG. 10(B) are views for explaining a combined stage coordinate system C_AOrigin, rotation, scaled measured map.

Detailed Description

Hereinafter, an embodiment of the present invention will be described with reference to fig. 1 to 10 (B).

Fig. 1 shows a schematic configuration of an exposure apparatus 100 according to an embodiment. The exposure apparatus 100 is a projection exposure apparatus of a step-and-scan method, a so-called scanner. As will be described later, in the present embodiment, the projection optical system PL is provided, and hereinafter, the direction parallel to the optical axis AX of the projection optical system PL is defined as the Z-axis direction, the direction in which the reticle and the wafer are relatively scanned in a plane orthogonal thereto is defined as the Y-axis direction, the direction orthogonal to the Z-axis and the Y-axis is defined as the X-axis direction, and the rotational (tilt) directions about the X-axis, the Y-axis, and the Z-axis are defined as the θ X, the θ Y, and the θ Z directions, respectively.

Exposure apparatus 100 includes illumination system 10, reticle stage RST for holding reticle R, projection unit PU, wafer stage WST1 on which wafer W is mounted, wafer stage device 50 including WST2, and a control system for these components.

An illumination system 10, such as disclosed in U.S. patent application publication No. 2003/0025890, includes: a light source, an illumination uniformizing optical system including an optical integrator and the like, and an illumination optical system having a reticle blind and the like (all not shown). The illumination system 10 illuminates a slit-shaped illumination region IAR on a reticle R defined by a reticle blind (masking system) with illumination light (exposure light) IL at a substantially uniform illuminance. The illumination light IL is, for example, an ArF excimer laser (wavelength 193 nm).

On reticle stage RST, reticle R having a pattern surface (lower surface in fig. 1) on which a circuit pattern or the like is formed is fixed by, for example, vacuum suction. Reticle stage RST is micro-driven in the XY plane by reticle stage driving system 11 (not shown in fig. 1, see fig. 6) including, for example, a linear motor or the like, and is driven in the scanning direction (Y-axis direction in the direction orthogonal to the paper surface in fig. 1) at a predetermined scanning speed.

Position information (including position information in the θ z direction (θ z rotation amount)) in the XY plane (moving surface) of reticle stage RST is detected at any time with an analysis capability of, for example, about 0.25nm by a reticle laser interferometer (hereinafter, referred to as "reticle interferometer") 16 that irradiates a distance measuring beam onto moving mirror 15 (actually, a Y moving mirror (or a retro-reflector) having a reflecting surface orthogonal to the Y axis direction and an X moving mirror having a reflecting surface orthogonal to the X axis direction) as shown in fig. 1. Further, to measure position information in at least a 3 degree of freedom direction of the reticle R, an encoder system such as disclosed in U.S. patent application publication No. 2007/0288121, and the like, can be used in place of, or in combination with, the reticle interferometer 16.

Projection unit PU is held by a main frame (also referred to as a metrology frame) which is disposed below (on the Z side of) reticle stage RST in fig. 1 and constitutes a part of a body (not shown). The projection unit PU includes a lens barrel 40 and a projection optical system PL including a plurality of optical elements held by the lens barrel 40. The projection optical system PL is a refractive optical system including, for example, a plurality of optical elements (lens elements) arranged along an optical axis AX parallel to the Z-axis direction. The projection optical system PL is, for example, both-side telecentric and has a predetermined projection magnification (e.g., 1/4 times, 1/5 times, 1/8 times, or the like). Therefore, when the illumination area IAR is illuminated with the illumination light IL from the illumination system 10, that is, by the illumination light IL of the reticle R arranged so that the pattern surface thereof substantially coincides with the 1 st surface (object surface) of the projection optical system PL, a reduced circuit pattern image (reduced image of a part of the circuit pattern) of the reticle R in the illumination area IAR is formed on the area (exposure area) IA conjugate to the illumination area IAR on the wafer W arranged on the 2 nd surface (image surface) side of the projection optical system PL and coated with a resist (sensitive agent) on the surface thereof through the projection optical system PL. Next, by synchronously driving reticle stage RST and wafer stages WST1 and WST2, reticle R is moved in the scanning direction (Y-axis direction) with respect to illumination area IAR (illumination light IL), and wafer W is moved in the scanning direction (Y-axis direction) with respect to exposure area IA (illumination light IL), so that scanning exposure of one illumination area (divided area) on wafer W is performed, and the pattern of reticle R is transferred to the illumination area. That is, in the present embodiment, a pattern of the reticle R is generated on the wafer W by the illumination system 10 and the projection optical system PL, and the sensitive layer (resist layer) on the wafer W is exposed with the illumination light IL to form the pattern on the wafer W.

The main frame may be of a door type commonly used and a suspension support type disclosed in, for example, U.S. patent application publication No. 2008/0068568.

In lens coneAround the-Z-side end of the lens barrel 40, for example, a scale plate 21 is disposed at approximately the same height as the lower end surface of the lens barrel 40 and parallel to the XY plane. The scale plate 21, in the present embodiment, as shown in FIG. 2, is composed of four L-shaped parts 21₁、21₂、21₃、21₄the-Z-side end of the lens barrel 40 is inserted into, for example, a rectangular opening 21a formed in the center thereof. Here, the widths in the X-axis direction and the Y-axis direction of the scale plate 21 are a and b, respectively, and the widths in the X-axis direction and the Y-axis direction of the opening 21a are a_iAnd b_i。

As shown in fig. 1, a scale plate 22 is disposed on substantially the same plane as the scale plate 21 at a position apart from the scale plate 21 in the + X direction. The scale plate 22, as shown in FIG. 3, is also formed of, for example, four L-shaped parts 22₁、22₂、22₃、22₄the-Z-side end of the alignment system ALG described later is inserted into, for example, a rectangular opening 22a formed in the center thereof. The widths of the scale plate 22 in the X-axis direction and the Y-axis direction are a and b, respectively, and the widths of the opening 22a in the X-axis direction and the Y-axis direction are ai and bi, respectively. In the present embodiment, the widths of the scale plates 21 and 22 and the widths of the openings 21a and 22a in the X-axis and Y-axis directions are the same, respectively, but the widths are not necessarily the same, and may be different in at least one of the X-axis and Y-axis directions.

In the present embodiment, the scale plates 21, 22 are suspended from a not-shown main frame (measurement frame) for supporting the projection unit PU and the alignment system ALG. A reflection type two-dimensional diffraction grating RG (see fig. 2, 3, and 4) is formed on the lower surface (-Z side surface) of the scale plates 21 and 22, and is composed of a grating having a predetermined pitch, for example, 1 μm, in which the periodic direction is the 45-degree direction with respect to the X axis (the-45-degree direction with respect to the Y axis), and a grating having a predetermined pitch, for example, 1 μm, in which the periodic direction is the-45-degree direction with respect to the X axis (the-135-degree direction with respect to the Y axis). However, in the configuration of the two-dimensional diffraction grating RG and the encoder head described later, the portions 21 constituting the scale plates 21 and 22 are formed₁～21₄、22₁～22₄Each having an outer edge nearSide contains an inactive area of width t. The two-dimensional diffraction gratings RG of the scale plates 21 and 22 respectively cover the movement ranges of the wafer stages WST1 and WST2 at least during the exposure operation and during the alignment (measurement).

As shown in fig. 1, wafer stage device 50 includes: stage base 12 supported substantially horizontally on the floor surface by a plurality of (for example, three or four) vibration-proof mechanisms (not shown), wafer stages WST1 and WST2 arranged on stage base 12, wafer stage drive system 27 (only a part of which is shown in fig. 1, see fig. 6) for driving wafer stages WST1 and WST2, and a measurement system for measuring the positions of wafer stages WST1 and WST 2. The measurement system includes encoder systems 70 and 71 and a wafer laser interferometer system (hereinafter simply referred to as a wafer interferometer system) 18 shown in fig. 6. The encoder systems 70 and 71 and the wafer interferometer system 18 are described below. However, in the present embodiment, the wafer interferometer system 18 is not necessarily provided.

As shown in fig. 1, stage base 12 is formed of a member having a flat plate-like outer shape, and the flatness of the upper surface thereof is extremely high so as to serve as a guide surface when wafer stages WST1 and WST2 move. Inside the stage base 12, a coil unit including a plurality of coils 14a arranged in a matrix shape with the XY two-dimensional direction as the row direction and the column direction is housed.

Further, another base member for supporting this in a floating manner may be provided separately from the stage base 12, and may have a function of a counter mass (reaction force canceller) for moving the stage base 12 in accordance with the law of conservation of momentum due to the reaction force of the driving force of the wafer stages WST1 and WST 2.

As shown in fig. 1, wafer stage WST1 includes: stage main body 91, and wafer table WTB1 arranged above stage main body 91 and supported by stage main body 91 in a noncontact manner by a Z tilt drive mechanism not shown. In this case, the wafer table WTB1 is supported in a non-contact manner by adjusting the balance between an upward force (repulsive force) such as an electromagnetic force and a downward force (attractive force) including its own weight at 3 points by the Z tilt driving mechanism, and is micro-driven in a 3-degree-of-freedom direction of at least the Z-axis direction, the θ x direction, and the θ y direction. A slider 91a is provided at the bottom of the stage body 91. The slider 91a has a magnet unit including a plurality of magnets arranged in an XY plane in an XY two-dimensional manner, a housing accommodating the magnet unit, and a plurality of air bearings provided around the bottom surface of the housing. The magnet unit and the coil unit together constitute a planar motor 30 driven by electromagnetic force (lorentz force) as disclosed in, for example, U.S. patent No. 5,196,745. Of course, the planar motor 30 is not limited to the lorentz force driving method, and a variable reluctance driving planar motor may be used.

Wafer stage WST1 is supported on stage base 12 by the plurality of air bearings in a floating manner with a predetermined gap (gap/spatial distance), for example, a gap of several μm, and is driven in the X-axis direction, the Y-axis direction, and the θ z direction by flat motor 30. Therefore, wafer table WTB1 (wafer W) can be driven in the 6-degree-of-freedom direction (X-axis direction, Y-axis direction, Z-axis direction, θ X direction, θ Y direction, and θ Z direction (hereinafter, abbreviated as X, Y, Z, θ X, θ Y, and θ Z)) with respect to stage base 12.

In the present embodiment, the magnitude and direction of the current supplied to each coil 14a constituting the coil unit are controlled by the main control device 20. Wafer stage drive system 27 is constituted by including plane motor 30 and the Z tilt drive mechanism. The planar motor 30 may be a moving coil (moving magnet) system, not limited to the moving magnet (moving magnet) system. The planar motor 30 may be a magnetic levitation type planar motor. In this case, the air bearing may not be provided. Further, wafer stage WST1 may be driven in the 6-degree-of-freedom direction by using plane motor 30. Of course, the wafer table WTB1 may be moved slightly in at least one of the X-axis direction, the Y-axis direction, and the θ z direction. That is, wafer stage WST1 may be configured as a coarse/fine movement stage.

The wafer W is loaded on the wafer table WTB1 by a wafer holder (not shown) and fixed by a chuck mechanism (not shown) (for example, vacuum suction (or electrostatic suction)). Further, a 1 st fiducial mark plate and a 2 nd fiducial mark plate are provided on a diagonal line on the wafer table WTB1 with a wafer holder interposed therebetween (see, for example, fig. 2). On the 1 st and 2 nd reference mark plates, a plurality of reference marks to be detected by the pair of reticle alignment systems 13A and 13B and the alignment system ALG described later are formed, respectively. Here, it is assumed that the positional relationship between the plurality of fiducial markers on the 1 st and 2 nd fiducial marker plates FM1 and FM2 is known.

Wafer stage WST2 has the same configuration as wafer stage WST 1.

Encoder systems 70 and 71 are used to obtain (measure) positional information in the 6-degree-of-freedom directions (X, Y, Z, θ x, θ y, and θ z) of the movement region of wafer stages WST1 and WST2 during exposure including the region immediately below projection optical system PL and the movement region during measurement including the region immediately below alignment system ALG, respectively. Here, the configurations of the encoder systems 70 and 71 and the like are described in detail. The exposure movement region (1 st movement region) is a region in which the wafer stage moves during an exposure operation in the exposure station (1 st region) where the wafer is exposed through the projection optical system PL, and the exposure operation includes, for example, not only exposure of all the irradiation regions of the pattern to be transferred on the wafer but also a preparatory operation for performing the exposure (for example, detection of the reference mark). The movement area during measurement (2 nd movement area) is an area in which the wafer stage moves during a measurement operation in a measurement station (2 nd area) in which the alignment system ALG detects the wafer alignment marks and measures the positional information thereof, and the measurement operation includes not only the detection of a plurality of alignment marks of the wafer, but also the detection of reference marks by the alignment system ALG (and the measurement of the wafer positional information (step data) in the Z-axis direction).

As shown in the plan views of fig. 2 and 3, encoder heads (hereinafter, referred to as heads) 60 are disposed at four corners of the top surface of each of the wafer tables WTB1 and WTB2₁～60₄. Here, the read head 60₁、60₂Separation distance between the X-axis direction and the read head 60₃、60₄The separation distances in the X-axis direction are equal to each other by a. Furthermore, the read head 60₁、60₄In the Y-axis directionSeparation distance of direction from the read head 60₂、60₃The separation distances in the Y-axis direction are equal to each other by B. These separation distances A, B are greater than the width a of the opening 21a of the scale plate 21_i、b_iThe size is large. Strictly speaking, considering the width t of the non-effective region, A ≧ a_i+2t、b≧b_i+2 t. Read head 60₁～60₄A head 60 as represented in FIG. 4₁For example, the wafer tables WTB1 and WTB2 are housed in holes formed therein at predetermined depths in the Z-axis direction.

Read head 60₁As shown in fig. 5, the two-dimensional head is a two-dimensional head in which the 135-degree direction (i.e., -45-degree direction with the X-axis as a reference) and the Z-axis direction are measurement directions with the X-axis as a reference. Similarly, the read head 60₂～60₄Also, the two-dimensional head is provided with a 225-degree direction (i.e., a 45-degree direction with respect to the X-axis) and a Z-axis direction with respect to the X-axis, a 315-degree direction (i.e., -45-degree direction with respect to the X-axis) and a Z-axis direction with respect to the X-axis, and a 45-degree direction and a Z-axis direction with respect to the X-axis as measurement directions, respectively. Read head 60₁～60₄As can be seen from FIGS. 2 and 4, the portions 21 of the scale plate 21 face each other₁～21₄Or portion 22 of scale plate 22₁～22₄The two-dimensional diffraction grating RG formed on the surface irradiates the measuring beam, receives the reflected and diffracted beams from the two-dimensional diffraction grating RG, and measures the positions of wafer tables WTB1 and WTB2 (wafer stages WST1 and WST2) in the respective measuring directions. Here, the read head 60 is provided₁～60₄For example, a sensor head having the same configuration as that of the displacement measuring sensor head disclosed in U.S. Pat. No. 7,561,280 can be used.

The reading head 60 configured as described above₁～60₄Since the optical path length of the measuring beam in air is extremely short, the influence of air fluctuation can be almost ignored. In the present embodiment, however, the light source and the photodetector are provided outside each head, specifically, inside (or outside) stage main body 91, and only the optical system is provided inside each head. And the light source and the photodetector and the optical system are connected viaOptically connected by optical fibers not shown. In order to improve the positioning accuracy of wafer table WTB (fine movement stage), aerial transmission of laser light or the like may be performed between stage body 91 (coarse movement stage) and wafer table WTB (fine movement stage) (hereinafter, simply referred to as coarse/fine movement stage), or a reading head may be provided on stage body 91 (coarse movement stage), the position of stage body 91 (coarse movement stage) may be measured by the reading head, and the relative displacement between coarse/fine movement stages may be measured by another sensor.

When wafer stages WST1 and WST2 are located in the above-described exposure movement region, head 60₁Is configured as a pair of (parts 21 of) scale boards 21₁) A two-dimensional encoder 70 for irradiating a measuring beam (measuring light), receiving a diffracted beam from a grating formed on the surface (lower surface) of the scale plate 21 and having a 135-degree direction with respect to the X axis, that is, a-45-degree direction with respect to the X axis (hereinafter, simply referred to as the-45-degree direction), and measuring the positions of the wafer tables WTB1, WTB2 in the-45-degree direction and the Z-axis direction₁、71₁(refer to fig. 6). Similarly, the read head 60₂～60₄Respectively constituting (parts 21 of) the scale plate 21₂～21₄) A two-dimensional encoder 70 for irradiating a measuring beam (measuring light), receiving diffracted light beams from a grating formed on a surface (lower surface) of the scale plate 21 and having a 225-degree direction with respect to the X axis, that is, a + 45-degree direction with respect to the X axis (hereinafter, simply referred to as a 45-degree direction), a 315-degree direction, that is, a-45-degree direction with respect to the X axis, and a 45-degree direction as a periodic direction, and measuring positions of the wafer tables WTB1, WTB2 in the 225-degree (45-degree) direction and the Z-axis direction, a 315-degree (-45-degree) direction and the Z-axis direction, and a 45-degree direction and the Z-axis direction₂～70₄、71₂～71₄(refer to fig. 6).

When wafer stages WST1 and WST2 are located in the movement region during measurement, head 60₁Is configured as a pair of (parts 22 of) scale plates 22₁) Irradiating a measuring beam (measuring light), receiving a diffracted light beam from a grating formed on the surface (lower surface) of the scale plate 22 and having a periodic direction of 135 degrees (-45 degrees) to measure the 135 degrees direction and the Z-axis direction of the wafer tables WTB1, WTB2Two-dimensional encoder 70 for orientation₁、71₁(refer to fig. 6). Similarly, the read head 60₂～60₄Two-dimensional encoder 70 for irradiating measurement beams (measurement light) to (portions 222 to 224 of) scale plate 22 and receiving diffracted beams from gratings having a periodic direction of 225 degrees (45 degrees), 315 degrees (-45 degrees) and 45 degrees formed on the surface (lower surface) of scale plate 22 to measure the 225 degrees (45 degrees), Z-axis, 315 degrees (-45 degrees) and Z-axis positions, and 45 degrees and Z-axis positions of wafer tables WTB1 and WTB2, respectively₂～70₄、71₂～71₄(refer to fig. 6).

As is clear from the above description, in the present embodiment, regardless of whether the measuring beam (measuring beam) is irradiated to either one of the scale plates 21, 22, that is, regardless of whether the wafer stages WST1, WST2 are within either one of the movement region at the time of exposure and the movement region at the time of measurement, the head 60 on the wafer stage WST1₁～60₄Are respectively formed into a two-dimensional encoder 70 together with a scale plate to which a measuring beam (measuring light) is irradiated₁～70₄Read head 60 on wafer stage WST2₁～60₄The two-dimensional encoder 71 is constituted by a scale plate irradiated with a measuring beam (measuring light)₁～71₄。

Two-dimensional encoder (hereinafter, referred to simply as encoder as appropriate) 70₁～70₄、71₁～71₄The measured values of the respective encoders are supplied to the main control device 20 (see fig. 6). The main control device 20 is based on a scale plate 21 (a component 21) formed with a two-dimensional diffraction grating RG₁～21₄) The measurement values of the at least three encoders facing below (i.e., the at least three encoders outputting valid measurement values) determine positional information of wafer tables WTB1, WTB2 within the movement region at the time of exposure including the region immediately below projection optical system PL. Similarly, main control device 20 is based on a scale plate 22 (constituting part 22) on which a two-dimensional diffraction grating RG is formed₁～22₄) At least three encoders facing below (i.e., outputting valid measurements)At least three encoders) to determine positional information of wafer tables WTB1, WTB2 within the measured movement area including the area immediately below alignment system ALG.

In exposure apparatus 100 of the present embodiment, the positions of wafer stages WST1 and WST2 (wafer tables WTB1 and WTB2) can be measured separately and independently from encoder systems 70 and 71 by wafer interferometer system 18 (see fig. 6). The measurement result of the wafer interferometer system 18 is used for auxiliary correction (correction) of long-term variations (for example, due to temporal deformation of the scale) in the measurement values of the encoder systems 70 and 71, or for backup in the case where the outputs of the encoder systems 70 and 71 are abnormal. Here, a detailed description of the wafer interferometer system 18 is omitted.

As shown in fig. 1, the alignment system ALG is an off-axis alignment system disposed at a predetermined interval on the + X side of the projection optical system PL. In the present embodiment, the Alignment system ALG is, for example, a FIA (Field Image Alignment) system that uses a wide-band light such as a halogen lamp to illuminate the mark and aligns the sensor by performing Image processing on the mark Image to measure the mark position. The imaging signal from the alignment system ALG is supplied to the main control device 20 (see fig. 6) through an alignment signal processing system (not shown).

The alignment system ALG is not limited to the FIA system, and may be an alignment sensor that irradiates a mark with coherent (coherent) detection light, detects scattered light or diffracted light generated from the mark, or detects two diffracted lights generated from the mark by interference (for example, diffracted lights of the same order or diffracted lights diffracted in the same direction), alone or in an appropriate combination. As the alignment system ALG, an alignment system having a plurality of detection regions, such as disclosed in U.S. patent application publication No. 2008/0088843 and the like, may also be used.

The exposure apparatus 100 of the present embodiment is provided with a multi-point focus position detection system (hereinafter, simply referred to as a multi-point AF system) AF (not shown in fig. 1, see fig. 6) of an oblique incidence system (not shown in fig. 1) which is disposed in a measurement station together with the alignment system ALG and has the same configuration as that disclosed in, for example, U.S. Pat. No. 5,448,332. At least a part of the measurement operation by the multi-spot AF system AF is performed in parallel with the mark detection operation by the alignment system ALG, and the encoder system is used to measure the position information of the wafer table during the measurement operation. The detection signal of the multi-point AF system AF is supplied to the main control device 20 (see fig. 6) via an AF signal processing system (not shown). The main controller 20 detects position information (step data/irregularity information) in the Z-axis direction of the surface of the wafer W based on the detection signal of the multi-point AF system AF and the measurement information of the encoder system, and performs so-called focus/leveling control for scanning and exposing the wafer W based on the previous detection information and the measurement information of the encoder system (position information in the Z-axis, θ x, and θ y directions). Further, a multipoint AF system may be provided in the exposure station near the projection unit PU, and the wafer stage may be driven while measuring positional information (concave-convex information) on the wafer surface during the exposure operation, thereby performing focus and leveling control of the wafer W.

In The exposure apparatus 100, a pair of Reticle alignment systems 13A and 13B (not shown in fig. 1, see fig. 6) of The TTR (Through The Reticle) system using light of an exposure wavelength, for example, disclosed in specification No. 5,646,413, are further provided above The Reticle R. The detection signals of the reticle alignment systems 13A, 13B are supplied to the main control device 20 via an alignment signal processing system not shown. Instead of the reticle alignment system, the reticle alignment may be performed by using an aerial image measuring instrument, not shown, provided on wafer stage WST.

Fig. 6 is a partially omitted block diagram of a control system related to stage control of the exposure apparatus 100. This control system is configured with a main control device 20 as a center. The main controller 20 includes a so-called microcomputer (or a workstation) including a CPU (central processing unit), a ROM (read only memory), a RAM (random access memory), and the like, and collectively controls the entire apparatus.

The exposure apparatus 100 constructed as described above is controlled by the master controller during the manufacture of the deviceApparatus 20 moves one of wafer stages WST1 and WST2 on which a wafer is mounted in a measurement station (movement area during measurement) to perform a wafer measurement operation using alignment system ALG and multipoint AF system. That is, the mark detection using the alignment system ALG, the so-called wafer alignment (for example, the all-wafer-enhanced alignment (EGA) disclosed in U.S. patent No. 4,780,617, etc.), and the measurement of the wafer surface information (step/unevenness information) using the multi-point AF system are performed on the wafer W held on one of the wafer stages WST1 and WST2 in the movement region during the measurement. At this time, the encoder system 70 (encoder 70) is used₁～70₄) Or encoder system 71 (encoder 71)₁～71₄) Position information in the 6-degree-of-freedom directions (X, Y, Z, thetax, thetay, and thetaz) of the wafer stages WST1 and WST2 is obtained (measured).

After the measurement operation such as wafer alignment, one of the wafer stages (WST1 or WST2) is moved to the movement area during exposure, and the main controller 20 performs reticle alignment or the like using the reticle alignment systems 13A and 13B, a reference mark plate (not shown) on the wafer table (WTB1 or WTB2), and the like, in the same program as that of a general scanning stepper (for example, the program disclosed in the specification of U.S. patent No. 5,646,413 or the like).

Then, the main controller 20 performs an exposure operation of the step-and-scan method based on the measurement results of the wafer alignment or the like, and transfers the pattern of the reticle R to each of the plurality of irradiation regions on the wafer W. The step-and-scan type exposure operation is performed by alternately repeating a scanning exposure operation in which the reticle stage RST and the wafer stage WST1 or WST2 are moved in synchronization with each other, and an inter-irradiation movement (stepping) operation in which the wafer stage WST1 or WST2 is moved to an acceleration start position for performing exposure of an irradiation region. During the exposure operation, the encoder system 70 (encoder 70) is used₁～70₄) Or encoder system 71 (encoder 71)₁～71₄) Position information in the 6-degree-of-freedom direction (X, Y, Z, thetax, thetay, thetaz) of one wafer stage (WST1 or WST2) is obtained (measured).

Exposure apparatus 100 of the present embodiment includes two wafer stages WST1 and WST 2. Therefore, a parallel processing operation is performed, in which wafer alignment or the like is performed on a wafer mounted on the other wafer stage WST2 in parallel with step-and-scan exposure of one wafer stage, for example, a wafer mounted on wafer stage WST 1.

As described above, in exposure apparatus 100 of the present embodiment, main controller 20 obtains (measures) positional information of wafer stage WST1 in the 6-degree-of-freedom direction (X, Y, Z, θ x, θ y, θ z) by using encoder system 70 (see fig. 6) both in the exposure movement region and in the measurement movement region. In both the exposure-time movement region and the measurement-time movement region, main controller 20 obtains (measures) positional information of wafer stage WST2 in the 6-degree-of-freedom direction (X, Y, Z, θ x, θ y, θ z) using encoder system 71 (see fig. 6).

Next, the principle of position measurement in the 3-degree-of-freedom direction (X-axis direction, Y-axis direction, and θ z direction (also abbreviated as X, Y, θ z)) in the XY plane using the encoder systems 70 and 71 will be described further. Here, the encoder readhead 60₁～60₄Or encoder 70₁～70₄The measurement result or value of (2) is the encoder readhead 60₁～60₄Or encoder 70₁～70₄Is measured in a direction other than the Z-axis direction.

In this embodiment, the encoder head 60 is adopted₁～60₄And the scale plate 21, the encoder head 60 being disposed in a movement region during exposure₁～60₄Can be constantly associated with (the corresponding portion 21 of) the scale plate 21₁～21₄) Face to face.

FIG. 7(A) shows encoder readhead 60 on wafer stage WST1₁～60₄And each part 21 of the scale plate 21₁～21₄Is configured with the measurement area a of the encoder system 70₀～A₄The relationship (2) of (c). Further, wafer stage WST2 has the same structure as wafer stage WST1Therefore, only wafer stage WST1 will be described here.

When the center of wafer stage WST1 (which coincides with the center of the wafer) is located within the movement region during exposure and is located at the + X side and the + Y side with respect to the exposure center (center of exposure area IA) P (i.e., the region in quadrant 1 with the exposure center P as the origin (however, the region a is not included)₀)1 st region A of₁In-process, read head 60 on wafer stage WST1₄、60₁、60₂Portions 21 respectively facing the scale plate 21₄、21₁、21₂. In the 1 st region A₁Internal, slave read head 60₄、60₁、60₂(encoder 70)₄、70₁、70₂) The valid measurement values are sent to the main control device 20. The positions of wafer stages WST1 and WST2 in the following description mean the positions of the centers of the wafer stages (which coincide with the center of the wafer). That is, the positions of the centers of wafer stages WST1 and WST2 are described as the positions of wafer stages WST1 and WST 2.

Similarly, when wafer stage WST1 moves within the exposure area and is positioned on the-X side and the + Y side with respect to exposure center P (the area in quadrant 2 with exposure center P as the origin (however, area A is not included)₀)2 nd region A of₂Inner, read head 60₁、60₂、60₃Portions 21 respectively facing the scale plate 21₁、21₂、21₃. In the area where wafer stage WST1 moves during exposure, the position of which is on the-X side and the-Y side with respect to exposure center P (the area in quadrant 3 with exposure center P as the origin (however, area A is not included)₀) Region 3A of)₃Inner, read head 60₂、60₃、60₄Portions 21 respectively facing the scale plate 21₂、21₃、21₄. When wafer stage WST1 moves within the exposure area and is positioned at the + X side and the-Y side with respect to exposure center P (the area in quadrant 4 with exposure center P as the origin (however, area A is not included)₀) 4 th region A of (B)₄Inner, read head 60₃、60₄、60₁Portions 21 respectively facing the scale plate 21₃、21₄、21₁。

In the present embodiment, the encoder head 60 is described above₁～60₄And conditions (A ≧ a) for the configuration and arrangement of the scale plate 21_i+2t、B≧b_i+2t), when wafer stage WST1 is positioned in cross-shaped area a centered on exposure center P, as shown in fig. 7(a)₀(including a width A-a in which the Y-axis direction passing through the exposure center P is the longitudinal direction_iA region of-2 t and a width B-B with the X-axis direction as the long side direction_iIn the region of-2 t (hereinafter referred to as "0 th region")), all heads 60 on wafer stage WST1₁～60₄Facing the scale plate 21 (corresponding part 21)₁～21₄). Thus, in the 0 th region A₀From all of the read heads 60₁～60₄(encoder 70)₁～70₄) The valid measurement values are sent to the main control device 20. In addition, in the present embodiment, the above conditions (A ≧ a) are removed_i+2t、B≧b_i+2t), the condition A ≧ a may be added to the size (W, L) of the irradiation region on the wafer on which the pattern is formed_i+W+2t、B≧b_i+ L +2 t. Here, W, L are widths of the irradiation region in the X axis direction and the Y axis direction, respectively. W, L are equal to the distance between the scanning exposure zones and the step distance in the X-axis direction.

Master control device 20 according to read head 60₁～60₄(encoder 70)₁～70₄) The position (X, Y, θ z) of wafer stage WST1 in the XY plane is calculated as a result of the measurement of (a). Here, the encoder 70₁～70₄Measured values of (are respectively denoted as C)₁～C₄) As shown in the following expressions (1) to (4), the position depends on the position (X, Y, θ z) of wafer stage WST 1.

C₁＝－(cosθz+sinθz)X/√2

+(cosθz－sinθz)Y/√2+√2psinθz…(1)

C₂＝－(cosθz－sinθz)X/√2

－(cosθz+sinθz)Y/√2+√2psinθz…(2)

C₃＝(cosθz+sinθz)X/√2

－(cosθz－sinθz)Y/√2+√2psinθz…(3)

C₄＝(cosθz－sinθz)X/√2

+(cosθz+sinθz)Y/√2+√2Psinθz…(4)

As shown in fig. 5, p is the distance from the center of the wafer table WTB1(WTB2) in the X-axis and Y-axis directions of the head.

Main control apparatus 20 is based on area A where wafer stage WST1 is located₀～A₄Three heads (encoders) facing the scale plate 21 are specified, the connected cubic program is combined by selecting an expression based on the measurement values from the above expressions (1) to (4), and the positions (X, Y, θ z) of the wafer stage WST1 in the XY plane are calculated by disconnecting the cubic program using the measurement values of the three heads (encoders). For example, wafer stage WST1 is located in area A1₁In the internal case, the master control device 20 slave heads 60₁、60₂、60₄(encoder 70)₁、70₂、70₄) The measurement values of the read heads are combined with the cubic program according to the formulas (1), (2) and (4), and the measurement values of the read heads are substituted into the left side of the formulas (1), (2) and (4) to disconnect the cubic program. The calculated position (X, Y, θ z) is represented as X₁、Y₁、θz₁. Similarly, when wafer stage WST1 is located in k-th area A_kInternal time, master control device 20 slave head 60_k－1、60_k、60_k+1(encoder 70)_k－1、70_k、70_k+1) The measured values (k-1), (k) and (k +1) of (a) are combined into a connected cubic equation, and the measured values of each read head are substituted into the left side of the equation to disconnect the cubic equation. Based on the above, the position (X) is calculated_k、Y_k、θz_k). Here, the numbers of 1-4 periodic substitutions are substituted for k-1, k and k + 1.

In addition, when wafer stage WST1 is located in area 0A₀Internal conditionsIn this configuration, the master control device 20 slave heads 60₁～60₄(encoder 70)₁～70₄) Any three of them can be selected. For example, after wafer stage WST1 moves from region 1 to region 0, head 60 corresponding to region 1 is selected₁、60₂、60₄(encoder 70)₁、70₂、70₄) And (4) finishing.

Based on the calculation results (X, Y, θ z), main controller 20 drives wafer stage WST1 within the movement region during exposure (performs position control).

When wafer stage WST1 is located within the movement region during measurement, main controller 20 measures positional information in the 3-degree-of-freedom direction (X, Y, θ z) using encoder system 70. Here, regarding the measurement principle and the like, (the portion 21 of) the scale plate 21 except for the exposure center P is replaced with the detection center of the alignment system ALG₁～21₄) Replaced by (part 22 of) scale plate 22₁～22₄) This is also consistent with the case where wafer stage WST1 is located in the movement region during exposure.

Further, main controller 20 moves heads 60 facing scale plates 21 and 22 in accordance with the positions of wafer stages WST1 and WST2₁～60₄And switching to at least one different three for use. Here, when the encoder heads are switched, a subsequent process for ensuring continuity of the wafer stage position measurement results as disclosed in, for example, U.S. patent application publication No. 2008/0094592 is performed.

As described above, the scale boards 21 and 22 in the exposure apparatus 100 of the present embodiment are respectively composed of four parts 21₁～21₄、22₁～22₄And (4) forming. Here, when the four portions, strictly speaking, the two-dimensional diffraction gratings RG formed under the four portions deviate from each other, a measurement error of the encoder systems 70, 71 is generated.

In FIGS. 7(B) and 7(C), the first and second regions A and B are schematically shown_k(k 1-4) internal slave head 60_k－1、60_k、60_k+1(encoder 70)_k－1、70_k、70_k+1Or encoder 71_k－1、71_k、71_k+1) Position (X) of wafer stage WST1 or WST2 calculated from the effective measurement values of (A)_k、Y_k、θz_k) Corresponding kth reference coordinate system C_k(k is 1 to 4). Four reference coordinate systems C₁～C₄Corresponding region A₁～A₄(see FIG. 7A)) are arranged so as to overlap each other in the vicinity of the origin O and so as to form a cross-shaped area C centered on the origin O₀Repeating with the adjacent reference coordinate system.

When the scale plate 21 is constituted as designed, that is, formed in the four portions 21₁～21₄When the two-dimensional diffraction gratings RG are not deviated from each other, four reference coordinate systems C are shown in FIG. 7(B)₁～C₄Respective origin O₁～O₄Coincide with each other (denoted by symbol O in the figure), and rotate by θ z₁～θz₄And scaling (scaling) Γ x₁～Γx₄、Γy₁～Γy₄Are also consistent with each other. Therefore, four reference coordinate systems can be combined into one coordinate system C_E. That is, the area A can be moved during exposure₁～A₄The positions of the inner wafer stages WST1 and WST2 in a combined coordinate system C_EIs represented by position coordinates X, Y, θ z.

However, formed in four portions 21₁～21₄When the two-dimensional diffraction gratings RG have deviations from each other, four reference coordinate systems C are shown in FIG. 7(C)₁～C₄Respective origin O₁～O₄Rotation theta z₁～θz₄And scaling Γ x₁～Γx₄、Γy₁～Γy₄A deviation occurs, and a measurement error occurs in association with the deviation. Therefore, in the example shown in fig. 7(B), four reference coordinate systems cannot be combined into one coordinate system C_E。

Similarly, when the four parts 22 of the scale plate 22 are constructed₁～22₄Strictly speaking, it is formed in four parts22₁～22₄When the lower two-dimensional diffraction gratings RG deviate from each other, a measurement error of the encoder system 70 or 71 occurs.

Therefore, in the present embodiment, the portion 21 constituting the scale plates 21, 22 is corrected₁～21₄、22₁～22₄Four reference coordinate systems C resulting from deviations from each other₁～C₄And a method for correcting the deviation between each other. Next, the calibration method will be described in detail by taking the scale plate 21 as an example.

First, main controller 20 positions wafer stage WST1(WST2) in area a as shown in fig. 8 a₀And (4) the following steps. In fig. 8(a), wafer stage WST1 is positioned in area a₀Is located in the center (immediately below the projection optical system PL). In the region A₀Head 60 mounted on wafer stage WST1₁～60₄All facing (the corresponding part 21 of) the scale plate 21₁～21₄) The valid measurement values are sent to the main control device 20. The main controller 20 is used in the k-th (1-4) area a_kInternally used readhead 60_k－1、60_k、60_k+2The position (X) of wafer stage WST1 is obtained from the measurement values of (the k-th head group)_k、Y_k、θz_k). The main controller 20 obtains a position (X) calculated from the measurement values of the k-th (2-4) head group_k、Y_k) Relative to the position (X) calculated from the measurement value of the 1 st head group₁、Y₁) Also, the deviation (O) is obtained_Xk＝X_k－X₁、O_Yk＝Y_k－Y₁)。

Also, the offset (O) may be used_Xk、O_Yk) Determining the offset (O) of the rotation theta z_θzk＝θz_k－θz₁). In this case, the offset O described later is omitted_θzkAnd (4) calculating.

The obtained offset (O)_Xk、O_Yk) A position (X) calculated from the measured values of the k-th (2-4) head group_k、Y_k) Is corrected to (X)_k－O_Xk、Y_k－O_Yk). By this correction, as shown in FIG. 8(B), the kth reference coordinate system C_kOrigin O of (═ 2-4)_kI.e. with reference to the 1 st reference coordinate system C₁Origin O of₁And (5) the consistency is achieved. In the figure, the origins that coincide with each other are denoted by the symbol O.

Next, as shown in fig. 8C, main controller 20 calculates the stage position (X) from the measurement values of the 1 st head group as a calibration reference₁、Y₁、θz₁) Wafer stage WST1 is located in area A₀The positions (X) of four wafer stages WST1 are determined using the measurement values of the four head groups while performing positioning at predetermined intervals by internal driving in the arrow direction (X-axis direction and Y-axis direction) and while performing positioning at predetermined intervals_k、Y_k(k＝1～4))。

Main controller 20 uses the four stage positions (X) obtained as described above_k、Y_k(k 1-4)) determining an offset O by, for example, least squares_θzkSo that the square error epsilon_k＝Σ((ξ_k－X₁)²+(ζ_k－Y₁)²) is the minimum, wherein k is 2-4 (ξ)_k、ζ_k) Is a carrier position (X) which is rotationally converted by using the following formula (5)_k、Y_k(k 2-4)). Here, to find the offset O_θzkAlthough the least square method is used as an example, the method is not limited to this, and an operation method other than the least square method may be used.

The offset O obtained as described above_θzkAnd a rotation θ z for calculating the rotation θ z from the measurement value of the k-th (2-4) head group_kCorrected to θ z_k－O_θzk. By this correction, as shown in FIG. 8(D), the kth reference coordinate system C_k(2-4) direction (rotation) of the coordinate system C with the 1 st reference coordinate system₁Are aligned in the same direction (rotation).

Next, the main control device 20 is connected to the firstSimilarly, as shown in fig. 8(E), the stage position (X) is determined according to₁、Y₁、θz₁) Placing wafer stage WST1 in area A₀The positions (X axis direction and Y axis direction) of four wafer stages WST1 are obtained while performing positioning at predetermined intervals by internal driving in the arrow direction (X axis direction and Y axis direction)_k、Y_k(k＝1～4))。

Main controller 20 uses the four stage positions (X) obtained as described above_k、Y_k(k 1-4)), and determining a scaling (gamma) by least squares operation_Xk、Γ_Yk) So that the square error epsilon_k＝Σ((ξ_k’－X₁)²+(ζ_k’－Y₁)²) is the minimum, wherein k is 2-4, and (xi)_k’、ζ_k') is the stage position (X) scaled using the following equation (6)_k、Y_k(k＝2～4))。

The obtained calibration (gamma)_Xk、Γ_Yk) Position (X) for calculating from measurement values of k-th (2-4) -th head group_k、Y_k) Is corrected to (X)_k/(1+Γ_Xk)、Y_k/(1+Γ_Yk)). By this correction, as shown in FIG. 8(F), the k-th reference coordinate system C_k(2-4) scaling with the 1 st reference coordinate system C₁The scaling is consistent.

By the above processing, the four corrected reference coordinate systems C are rotated and scaled₁～C₄I.e. combined to cover the moving area A during exposure₀～A₄A coordinate system (combined coordinate system) C_E。

Alternatively, instead of the above-described processing, the offset and the calibration (O) may be obtained by the following processing_Xk、O_Yk、O_θzk、Γ_Xk、Γ_Yk(k 2-4)). That is, the main control device 20, as shown in FIG. 8(C) or FIG. 8(E), is a rootAccording to the position of the table (X)₁、Y₁、θz₁) Placing wafer stage WST1 in area A₀The positions (X axis direction and Y axis direction) of four wafer stages WST1 are obtained while performing positioning at predetermined intervals by internal driving in the arrow direction (X axis direction and Y axis direction)_k、Y_k(k is 1 to 4)). Main controller 20 uses the four stage positions (X) obtained_k、Y_k(k 1-4)), and determining an offset and a scaling (O) by least squares_Xk、O_Yk、O_θzk、Γ_Xk、Γ_Yk) So that the square error epsilon_k＝Σ((ξ”_k－X₁)²+(ζ”_k－Y₁)²) is the minimum, wherein k is 2-4, here, (ξ) "_k、ζ”_k) Is a stage position (X) converted by the following formula (7)_k、Y_k(k＝2～4))。

The above processing is performed in the 1 st reference coordinate system C₁Directly obtaining a reference coordinate system C for the 2 nd to the 4 th₂～C₄But can also be determined indirectly. For example, the 1 st reference coordinate system C is obtained according to the above procedure₁Reference 2 nd reference coordinate system C₂Offset and scaling (O)_X2、O_Y2、O_θz2、Γ_X2、Γ_Y2). Similarly, the 2 nd reference coordinate system C is obtained₂Reference 3 rd reference coordinate system C₃Offset and scaling (O)_X32、O_Y32、O_θz32、Γ_X32、Γ_Y32). From these results, the reference coordinate system C of the No. 1₁A third reference coordinate system C as a reference₃Is obtained as (O)_X3＝O_X32+O_X2、O_Y3＝O_Y32+O_Y2、O_θz3＝O_θz32+O_θz2、Γ_X3＝Γ_X32·Γ_X2、Γ_Y3＝Γ_Y32·Γ_Y2). Similarly, the 3 rd reference coordinate system C can be obtained₃Reference 4 th reference coordinate C₄Using the result of the deviation and calibration of (1) th reference coordinate C₁Reference 4 th reference coordinate C₄Offset and scaling.

The main controller 20 also corrects four reference coordinates for the scale plate 22 in accordance with the same procedure, and combines four reference coordinate systems covering the movement area during measurement into one coordinate system (combined coordinate system) C_A(see FIG. 7B).

Finally, the main controller 20 calculates the moving area A covering the exposure₀～A₄Combined coordinate system C_ECombined coordinate system C covering the moving area during measurement_APositional, rotational, and scaled deviations. As shown in fig. 9 a, main controller 20 obtains (measures) positional information of wafer stage WST1 using encoder system 70, and drives wafer stage WST1 based on the result of the measurement to position 1 st fiducial mark plate FM1 on wafer table WTB1 directly below projection optical system PL (exposure center P). Main controller 20 detects two (a pair of) fiducial marks formed on fiducial mark plate FM1 of item 1 using a pair of reticle alignment systems 13A and 13B. Next, main controller 20 drives wafer stage WST1 based on the measurement result of encoder system 70, positions 2 nd fiducial mark plate FM2 on wafer table WTB1 directly below projection optical system PL (exposure center P), and detects one fiducial mark formed on 2 nd fiducial mark plate FM2 using either of the pair of reticle alignment systems 13A and 13B. Main controller 20 obtains combined coordinate system C from the detection results of the three reference marks (i.e., the two-dimensional position coordinates of the three reference marks)_EPosition, rotation, and calibration of the origin.

Main controller 20 moves wafer stage WST1 to the movement area for measurement. At this time, the main controller 20 moves the area a during exposure₀～A₄In the area between the measurement-time movement area, the wafer interferometer system 18 is used, and in the measurement-time movement area, the encoder system 70 is used to measure the waferThe position information of stage WST1 is based on the result, and wafer stage WST1 is driven (position control). After the movement, main controller 20 detects three reference marks using alignment system ALG in the same manner as before, and obtains combined coordinate system C from the detection result, as shown in fig. 10(a) and 10(B)_APosition, rotation, and calibration of the origin. Further, although it is preferable that the three reference marks to be detected by the reticle alignment systems 13A and 13B and the three reference marks to be detected by the alignment system ALG are the same mark, when the same reference mark cannot be detected by the reticle alignment systems 13A and 13B and the alignment system ALG, the positional relationship between the reference marks is known, and therefore the reticle alignment systems 13A and 13B and the alignment system ALG can be marked as the detection targets with different reference marks.

Further, when the wafer stage moves between the movement region during exposure and the movement region during measurement, the position of the wafer stage may be controlled using the encoder system. The connection processing (phase connection and/or coordinate connection) is performed in the exposure-time moving region and the measurement-time moving region, respectively. Here, coordinate connection refers to a connection process in which measurement values for the encoder used after switching are set before and after switching of the encoder (head) so that the calculated position coordinates of wafer stage WST completely match, and at the same time, a phase shift is reset. The phase connection rule is basically the same as the coordinate connection method, but the phase shift processing is different, and the phase shift is not reset, and only the count value is reset by continuing to use the set phase shift.

The main controller 20, based on the obtained combined coordinate system C_EPosition, rotation, calibration and combined coordinate system C of origin_APosition, rotation, and calibration of the origin to obtain a combined coordinate system C_E、C_AOrigin, rotation, and calibration deviation between. The master control device 20 may use this deviation, e.g. in the combined coordinate system C_AThe wafer alignment result measured above, for example, the arrangement coordinates of a plurality of irradiation areas on the wafer (or the position coordinates of alignment marks on the wafer) is converted into a combined coordinate system C_EThe arrangement coordinates of the plurality of irradiation regions on the wafer are combined at the combination coordinate C during the exposure operation of the wafer according to the converted arrangement coordinates_EThe wafer stage WST1 is driven (position controlled).

The main control device 20 performs the above-described correction method for each wafer exposure process (or for each predetermined number of wafers). That is, before the wafer alignment using the alignment system ALG is performed, the encoder systems 70 and 71 when the scale plate 22 is used are corrected as described above (the four reference coordinate systems C are set to the four reference coordinate systems C)₁～C₄Combined into a combined coordinate system C_A). Using corrected encoder systems 70, 71 (in a combined coordinate system C)_AAbove) a wafer to be exposed is subjected to a measurement operation such as wafer alignment. Next, before the exposure process of the wafer, the encoder systems 70 and 71 (using the four reference coordinate systems C) when the scale plate 21 is used are corrected as described above₁～C₄Combined into a combined coordinate system C_E). Further, a combined coordinate system C is obtained_A、C_EPositional, rotational, and scaled deviations (relative position, relative rotation, relative scaling). Using these results will be in the combined coordinate system C_AThe wafer alignment result (e.g. the arrangement coordinates of a plurality of irradiation areas on the wafer) measured on the wafer is converted into a combined coordinate system C_EThe arrangement coordinates of the plurality of irradiation areas on the wafer are converted into the combination coordinate system C_EThe wafer stages WST1 and WST2 holding the wafer are driven (position control) to perform exposure processing of the wafer.

Further, as the correction processing (correction method), although the measurement value of the encoder system can be corrected, other processing may be adopted. For example, other methods such as driving (position control) the wafer stage by adding an offset to the current position or the target position of the wafer stage, or correcting the position of the reticle only by the measurement error may be applied.

Next, the principle of position measurement in the 3-degree-of-freedom directions (Z, θ x, θ y) by the encoder systems 70 and 71, and the like will be further described. Here, the encoder readhead 60₁～60₄Or encoder 70₁～70₄The measurement result or value of (2) is the encoder readhead 60₁～60₄Or encoder 70₁～70₄The Z-axis direction of (a).

This embodiment, due to the use of an encoder readhead 60 as described above₁～60₄And a scale plate 21 configured and arranged so that, in a moving region during exposure, a region A where a wafer stage WST1(WST2) is located₀～A₄Encoder readhead 60₁～60₄At least three of which are associated with (corresponding parts 21 of) the scale plate 21₁～21₄) Face to face. The valid measurement values are sent from the head (encoder) facing the scale plate 21 to the main control device 20.

Main control device 20 according to encoder 70₁～70₄(or 71)₁～71₄) The position (Z, θ x, θ y) of wafer stage WST1(WST2) is calculated from the measurement results of (a). Here, the encoder 70₁～70₄(or 71)₁～71₄) Measurement in the Z-axis direction (a measurement direction other than the aforementioned Z-axis direction, i.e., a measurement C with respect to an axial direction in the XY plane)₁～C₄Distinguished by being respectively recorded as D₁～D₄) The values are the positions (Z, θ x, θ y) depending on the wafer stage WST1(WST2) as in the following expressions (8) to (11).

D₁＝－ptanθy+ptanθx+Z…(8)

D₂＝ptanθy+ptanθx+Z…(9)

D₃＝ptanθy－ptanθx+Z…(10)

D₄＝－ptanθy－ptanθx+Z…(11)

Where p is the distance from the center of the wafer table WTB1(WTB2) to the X-axis and Y-axis directions of the head (see fig. 5).

Main control apparatus 20 is controlled based on area A where wafer stage WST1(WST2) is located₀～A₄The position (Z, θ x, θ y) of wafer stage WST1(WST2) is calculated by selecting an equation based on the measurement values of the three heads (encoders) from equations (8) to (11) and substituting the measurement values of the three heads (encoders) into a connected cubic equation solving the three equations selected. For example, wafer stage WST1 (or WST2) is located in zone A1₁In the case of the inside, the head 60 of the main controller 20₁、60₂、60₄(encoder 70)₁、70₂、70₄Or 71₁、71₂、71₄) The measurement values are solved by combining the equations (8), (9) and (11) according to a connected equation, and substituting the measurement values into the left side of the equations (8), (9) and (11). The calculated positions (Z, θ x, θ y) are represented as Z₁、θx₁、θy₁. Similarly, main controller 20 is located in k-th area a on wafer stage WST1_kIn the inner case, the slave reading head 60_k－1、60_k、60_k+1(encoder 70)_k－1、70_k、70_k+1) The measurement values of (a) are based on the combined connected cubic equations of the formulae ((k-1) +7), (k +7) and ((k +1) +7), and the measurement values of each head are substituted for the left side of each of the formulae ((k-1) +7), (k +7) and ((k +1) +7) to disconnect the cubic equations. Based on the above, the position (Z) is calculated_k、θx_k、θy_k). Here, the number of periodic substitutions 1 to 4 are substituted into k-1, k and k + 1.

When wafer stage WST1 (or WST2) is located in area 0A₀In the inner case, the slave reading head 60₁～60₄(encoder 70)₁～70₄Or 71₁～71₄) Any three are selected) and a connected equation of a combination of equations based on the measured values of the selected three heads is used.

Based on the above calculation results (Z, θ x, θ y) and the step difference data (focus mapping data), main controller 20 performs focus leveling control of wafer stage WST1 (or WST2) in the movement region during exposure.

When wafer stage WST1 (or WST2) is located in the movement area during measurement, main controller 20 makes the movement area of wafer stage WST1 (or WST2) be smaller than the movement area of wafer stage WSTThe position information of the wafer stage WST1 (or WST2) in the 3-degree-of-freedom direction (Z, θ x, θ y) is measured by the encoder system 70 (or 71). Here, the measurement principle and the like are changed to (the portion 21 of) the scale plate 21 except that the exposure center is changed to the detection center of the alignment system ALG₁～21₄) Portion 22 replaced by scale plate 22₁～22₄) Otherwise, the same is true for the case where wafer stage WST1 is located in the movement region in the previous exposure. Main controller 20 performs focus leveling control of wafer stage WST1 or WST2 based on the measurement result of encoder system 70 or 71. In addition, the moving area (measuring station) may not be focused or leveled during measurement. That is, the mark position and the step data (focus mapping data) are acquired first, and the Z tilt component of the wafer stage at the time of acquiring the step data (at the time of measurement) is subtracted from the step data, thereby acquiring the step data with the reference surface, for example, the upper surface of the wafer stage as the reference. During exposure, focusing and leveling can be performed based on the difference data and the position information of the wafer surface stage in the 3-degree-of-freedom direction (Z, θ x, θ y).

Further, main controller 20 moves heads 60 facing scale plates 21 and 22 in accordance with the positions of wafer stages WST1 and WST2₁～60₄For at least one different three. Here, when the encoder heads are switched, the same following process as described above is performed to ensure continuity of the position measurement result of wafer stage WST1 (or WST 2).

As described above, the scale boards 21, 22 in the exposure apparatus 100 of the present embodiment are respectively composed of the four portions 21₁～21₄、22₁～22₄And (4) forming. Here, when the heights and inclinations of the four portions deviate from each other, measurement errors of the encoder systems 70, 71 occur. Therefore, the same correction method as before is applied, the correction factor part 21₁～21₄Or 22₁～22₄Four reference coordinate systems C caused by the height and inclination deviation of each other₁～C₄Deviation from each other.

Here, an example of the correction method will be described by taking a case where the encoder system 70 is used as an example.

As shown in fig. 8C or 8E, main controller 20 measures the position of wafer stage WST1 based on the measurement result (X) of the position of wafer stage WST1 measured by encoder system 70₁、Y₁、θz₁) Wafer stage WST1 is located in area A₀The position of four wafer tables WTB1 (Z) is determined by using the measurement values of four head groups while performing positioning at predetermined intervals by internally driving in the arrow direction (X-axis direction and Y-axis direction) and determining the position of four wafer tables WTB1_k、θx_k、θy_k(k is 1 to 4)). The main controller 20 uses these results to determine the position (Z) calculated from the measurement values of the k-th (2 to 4) head group_k、θx_k、θy_k) Relative to the position (Z) calculated from the measured value of the 1 st head group₁、θx₁、θy₁) Deviation of (2), i.e. finding the offset (O)_Zk＝Z_k－Z₁、O_θxk＝θx_k－θx₁、O_θyk＝θy_k－θy₁). Further, the main controller 20 calculates an offset (O) for each positioning_Zk、O_θxk、O_θyk) The average is taken.

The obtained offset (O)_Zk、O_θxk、O_θyk) Is used for calculating the position (Z) from the measured value of the k (2-4) th head group_k、θx_k、θy_k) Respectively corrected to Z_k－O_Zk、θx_k－O_θxk、θy_k－O_θyk. By this correction, the k-th reference coordinate system C_k(k is 2 to 4) and the inclinations θ x and θ y are the same as the 1 st reference coordinate system C₁Is coincident with the inclinations thetax, thetay. I.e. four reference coordinate systems C₁～C₄Is combined to cover the moving area A during exposure₀～A₄A coordinate system (combined coordinate system) C_E。

The main control device 20 corrects the four reference coordinates for the encoder system 71 in accordance with the same procedure, and combines the four reference coordinates into one coordinate system (combined coordinate system) covering the moving region during the alignment measurement)C_A。

The main controller 20 performs the above-described calibration method in the same manner as in the conventional case for each exposure process for each wafer (or each exposure process for a predetermined number of wafers). That is, prior to wafer alignment using alignment system ALG, encoder system 70 (or 71) when scale plate 22 is used is corrected (using four reference coordinate systems C) as previously described₁～C₄Combined into a combined coordinate system C_A). The master control device 20 uses the corrected encoder system 70 (or 71) (in the combined coordinate system C)_AUpper) wafer alignment is performed on the wafer to be exposed. Next, before the exposure process of the wafer, the main controller 20 corrects the encoder system 70 (or 71) when the scale plate 21 is used as described above (the four reference coordinate systems C are set to be four reference coordinate systems C)₁～C₄Combined into a combined coordinate system C_E). The master control device 20 uses the corrected encoder system 70 (or 71) (in the combined coordinate system C)_EAbove) obtains (measures) the positional information of the wafer table WTB1 (or WTB2) holding the wafer, and performs driving (position control) of the wafer table WTB1 (or WTB2) at the time of exposure of the wafer based on the measurement result and the result of alignment of the wafer.

As described above in detail, according to exposure apparatus 100 of the present embodiment, main controller 20 includes four heads 60 mounted on wafer stages WST1 and WST2₁～60₄The areas (portions 21, 22) corresponding to the heads included in the 1 st head group and the 2 nd head group to which the three heads including the different one head belong₁～21₄、22₁～22₄) Facing area A₀In the method, the wafer stages WST1 and WST2 are driven (position control) based on the position information obtained by using the 1 st head group, and the 1 st and 2 nd reference coordinate systems C corresponding to the 1 st and 2 nd head groups are obtained by using the position information obtained by using the 1 st and 2 nd head groups₁、C₂Deviation between (positional, rotational, scaled deviation). The main controller 20 uses the result to correct the measurement result obtained by using the 2 nd head group, thereby making the 1 st and 2 nd reference coordinate systems C₁、C₂The deviation between the two is corrected for,to correct four heads 60₁～60₄The measurement error associated with the deviation of the areas on the respective facing scale plates 21, 22 from each other.

Further, according to the exposure apparatus 100 of the present embodiment, the encoder systems 70 and 71 are corrected by the correction method described above to correct the four reference coordinate systems C₁～C₄The positional deviation between the wafer stages WST1 and WST2 can be measured and driven (position control) with high accuracy using the encoder systems 70 and 71.

In the exposure apparatus 100 of the present embodiment, the main controller 20 detects three reference marks provided on the wafer stages WST1 and WST2 using the reticle alignment systems 13A and 13B and the alignment system ALG, and obtains the combined coordinate system C corresponding to the movement region during exposure and the movement region during measurement, respectively_E、C_ARelative position, relative rotation, relative scaling. And the result can be used by the master control device 20 to determine the coordinate system C_AThe result of the wafer alignment measured above, e.g. the conversion of the arrangement coordinates of a plurality of irradiated areas on the wafer into a combined coordinate system C_EThe arrangement coordinates of a plurality of irradiation areas on the wafer, using the result at the combined coordinate C_EThe wafer stages WST1 and WST2 are driven (position controlled) to expose the wafer.

In the above embodiment, wafer stage WST1 is located in 0 th area a₀All of the read heads 60 on inner time wafer stage WST1₁～60₄Corresponding to the scale plate 21 (corresponding part 21)₁～21₄) Face to face. Thus, in the 0 th region A₀Therein, is from all of the read heads 60₁～60₄(encoder 70)₁～70₄) The valid measurement values are sent to the main control device 20. Therefore, the main controller 20 can be provided with four heads 60₁～60₄Heads included in the k-th head group (k 1-4) including three heads including different heads and corresponding regions (portions 21) on the scale plate 21₁～21₄) Facing area A₀In, using the kth readAt least one of the head groups (k is 1 to 4), for example, at least one of the 1 st position information obtained by using the 1 st head group and the 2 nd position information obtained by using the 2 nd head group, performs driving (position control) of wafer stages WST1 and WST 2. In this case, even if the coordinate systems (portions of the scale plate 21) corresponding to the 1 st head group and the 2 nd head group are different, the wafer stages WST1 and WST2 can be driven with high accuracy without being affected. The same applies to the use of the scale plate 22.

In the above embodiment, the portions 21 constituting the scale plates 21 and 22₁～21₄、22₁～22₄Four reference coordinate systems C caused by deviations from each other₁～C₄The correction process of the mutual deviation does not need to pay attention to all of the position, rotation, and calibration, and may be one or both of them, or may be added or substituted with other factors (orthogonality, etc.).

In the above embodiment, at least one auxiliary head may be provided near each of the heads on the upper four corners of the wafer table, and when a measurement abnormality occurs in the main head, the measurement is continued by switching to the adjacent auxiliary head. In this case, the above arrangement condition can be applied to the auxiliary head.

In the above embodiments, the portions 21 of the scale plates 21 and 22 are referred to₁～21₄、22₁～22₄The case where the two-dimensional diffraction grating RG is formed on the lower surface of each of the encoder heads 60 is exemplified, but not limited thereto₁～60₄The above-described embodiments can also be applied to a 1-dimensional diffraction grating in which the measurement direction (the axial direction in the XY plane) is the periodic direction.

In the above embodiment, the four heads 60 mounted on wafer stages WST1 and WST2 are used₁～60₄The areas (portions 21, 22) corresponding to the heads included in the 1 st head group and the 2 nd head group to which the three heads including the different one head belong₁～21₄、22₁～22₄) Facing each otherRegion A₀In the system, the wafer stages WST1 and WST2 are driven (position controlled) using the position information obtained by the 1 st head group, and the 1 st and 2 nd reference coordinate systems C corresponding to the 1 st and 2 nd head groups are obtained using the position information obtained by the 1 st and 2 nd head groups₁、C₂The measurement result obtained by using the 2 nd head group is corrected using the deviation (position, rotation, calibration deviation) between the four heads 60, thereby correcting the four heads₁～60₄The case of the measurement error due to the deviation between the areas on the scale plates 21 and 22 has been described, but the present invention is not limited to this, and for example, a case may be adopted in which a plurality of heads (2 nd number) having a larger number than a plurality of heads (1 st number) for position control of the wafer stage moves the wafer stage in the areas where the position measurement can be performed, and correction information of the stage position information obtained by the encoder system is obtained, or for example, in the cross area a of the above-described embodiment₀The correction information is obtained by moving the stage and using the redundant head.

In this case, the correction information is a value for correcting the encoder measurement value by the main control device 20, but is not limited thereto, and may be used in other processes.

For example, other methods such as driving (position control) the wafer stage by adding an offset to the current position or the target position of the wafer stage, or correcting the reticle position by the measurement error component may be applied.

In the above embodiment, the 1 st and 2 nd reference coordinate systems C corresponding to the 1 st and 2 nd head groups are obtained using the position information obtained by the 1 st and 2 nd head groups₁、C₂The exposure apparatus may include, for example, a head that obtains position information of the wafer stage by irradiating a measurement beam on a measurement surface formed by a plurality of scale plates arranged substantially parallel to the XY plane outside the wafer stage in the vicinity of an exposure position to the wafer among a plurality of heads provided on the wafer stage and receiving a return beam from the measurement surface, and the exposure apparatus may include a head that obtains position information of the wafer stageAnd a control system that drives the wafer stage based on the position information obtained by the position measurement system and switches the head used for obtaining the position information from the position measurement system among the plurality of heads based on the position of the wafer stage, wherein the control system obtains a positional relationship between a plurality of scale plates corresponding to the plurality of heads in a 1 st movement region of the moving body in which the plurality of heads and the measurement surface face each other. In this case, the plurality of scale plates are faced with the plurality of head groups to which the plurality of heads including at least one head different from each other among the plurality of heads belong, respectively.

In this case, the positional relationship between the plurality of scale plates can be used not only for correcting the value of the encoder measurement value but also for other processes. For example, other methods such as driving (position control) the wafer stage by adding an offset to the current position or the target position of the wafer stage as the measurement error, or correcting the position of the reticle only by the measurement error may be applied.

In the above embodiment, the heads 60 are respectively provided for the heads₁～60₄(encoder 70)₁～70₄) The case of using a two-dimensional encoder in which the one-axis direction and the Z-axis direction in the XY plane are the measurement directions has been exemplified, but the present invention is not limited thereto, and a 1-dimensional encoder in which the 1-axis direction in the XY plane is the measurement direction and a 1-dimensional encoder in which the Z-axis direction is the measurement direction (a surface position sensor of a non-encoder type or the like) may be used. Alternatively, a two-dimensional encoder may be used in which 2 axial directions orthogonal to each other in the XY plane are used as measurement directions. Further, a 3-dimensional encoder (3DOF sensor) having 3 directions of the X-axis, Y-axis, and Z-axis directions as measurement directions may be used.

Further, although the above embodiments have been described with respect to the case where the exposure apparatus is a scanning stepper, the present invention is not limited thereto, and the above embodiments may be applied to a stationary exposure apparatus such as a stepper. Even in a stepper or the like, since the position of the stage on which the exposure target object is mounted is measured by an encoder, unlike the case where the position of the stage is measured by an interferometer, the occurrence of a position measurement error due to air fluctuation can be made almost zero, and the stage can be positioned with high accuracy based on the measurement value of the encoder, and as a result, the reticle pattern can be transferred onto the wafer with high accuracy. In addition, the above embodiment can be applied to a step & stick type projection exposure apparatus in which an irradiation region and an irradiation region are combined. The above-described embodiments can also be applied to a multi-stage exposure apparatus including a plurality of wafer stages, as disclosed in, for example, U.S. Pat. No. 6,590,634, U.S. Pat. No. 5,969,441, and U.S. Pat. No. 6,208,407. The above-described embodiments can also be applied to an exposure apparatus including a measurement stage including a measurement member (e.g., a reference mark and/or a sensor) different from a wafer stage, as disclosed in, for example, U.S. patent application publication No. 2007/0211235 and U.S. patent application publication No. 2007/0127006.

The exposure apparatus of the above embodiment may be a liquid immersion type exposure apparatus as disclosed in, for example, International publication No. 99/49504 and U.S. patent application publication No. 2005/0259234.

The projection optical system in the exposure apparatus according to the above-described embodiment is not limited to the reduction system, and may be any of the equal magnification system and the enlargement system, and the projection optical system PL is not limited to the refraction system, and may be any of the reflection system and the catadioptric system, and the projection image may be any of an inverted image and an erect image.

The illumination light IL is not limited to ArF excimer laser (wavelength 193nm), but may be ultraviolet light such as KrF excimer laser (wavelength 248nm), or F₂Vacuum ultraviolet light such as laser light (wavelength 157 nm). Single wavelength laser light in the infrared or visible region emitted from DFB semiconductor laser or fiber laser can also be amplified as vacuum ultraviolet light and converted to a wavelength of ultraviolet light harmonic by nonlinear optical crystals using, for example, an erbium (or both erbium and ytterbium) doped fiber amplifier as disclosed in U.S. patent No. 7,023,610.

In the above-described embodiments, although a light transmissive mask (reticle) in which a predetermined light shielding pattern (or phase pattern or light reduction pattern) is formed on a light transmissive substrate is used, an electronic mask (including a DMD (Digital Micro-mirror Device) which forms a transmission pattern, a reflection pattern or a light emission pattern from electronic data of a pattern to be exposed, which is also referred to as a variable shape mask, an active mask or an image generator, for example, a non-light emitting image display Device (spatial light modulator)) as disclosed in, for example, U.S. Pat. No. 6,778,257 may be used instead of the reticle. In the case of using the variable shaping mask, since the stage on which the wafer, the glass plate, or the like is mounted is scanned with respect to the variable shaping mask, the same effect as that of the above-described embodiment can be obtained by measuring the position of the stage using the encoder system and the laser interferometer system.

The above embodiments can also be applied to an exposure apparatus (lithography system) for forming a line and space (line & space) pattern on a wafer W by forming interference fringes on the wafer W as disclosed in, for example, international publication No. 2001/035168.

Further, the above-described embodiments can be applied to an exposure apparatus in which two reticle patterns are combined on a wafer through a projection optical system and one irradiation region on the wafer is double-exposed substantially simultaneously by one scanning exposure, as disclosed in, for example, U.S. Pat. No. 6,611,316.

In the above-described embodiment, the object to be patterned (the exposure object to which the energy beam is applied) is not limited to a wafer, but may be another object such as a glass plate, a ceramic substrate, a thin film member, or a mask master.

The application of the exposure apparatus is not limited to the exposure apparatus for semiconductor manufacturing, and it can be widely applied to, for example, an exposure apparatus for liquid crystal for transferring a liquid crystal display element pattern to a square glass plate, and an exposure apparatus for manufacturing organic EL, a thin film magnetic head, an imaging element (CCD or the like), a micromachine, a DNA chip, or the like. The present invention is applicable not only to microdevices such as semiconductor devices, but also to exposure apparatuses that transfer a circuit pattern onto a glass substrate, a silicon wafer, or the like to produce a reticle or a mask used in a light exposure apparatus, an EUV exposure apparatus, an X-ray exposure apparatus, an electron beam exposure apparatus, or the like.

Further, the disclosures of all publications on exposure apparatuses and the like, international publications, U.S. patent application publications, and U.S. patent specifications cited in the above description are incorporated as a part of the present specification.

An electronic device such as a semiconductor device is manufactured by a step of designing the function and performance of the device, a step of fabricating a reticle based on the designing step, a step of fabricating a wafer from a silicon material, a photolithography step of transferring a mask (reticle) pattern to the wafer by an exposure apparatus (pattern forming apparatus) and an exposure method thereof according to the above embodiments, a development step of developing the wafer (object) after exposure, an etching step of etching and removing an exposed member except for a portion where the photoresist remains, a photoresist removal step of removing the photoresist which is unnecessary after etching, a device assembly step (including a dicing step, a bonding step, a packaging step), an inspection step, and the like. In this case, since the exposure apparatus and the exposure method according to the above embodiments are used for the photolithography process, a device with high integration can be manufactured with good productivity.

As described above, the exposure apparatus (patterning apparatus) according to the above embodiment is manufactured by assembling various subsystems including the respective constituent elements recited in the claims of the present application so as to maintain predetermined mechanical, electrical, and optical precision. To ensure the various accuracies described above, adjustments are made to various optical systems to achieve optical accuracy, to various mechanical systems to achieve mechanical accuracy, and to various electrical systems to achieve various electrical accuracy before and after this assembly. The steps of assembling the various subsystems to the exposure apparatus include mechanical connection, electrical circuit connection, and pneumatic circuit connection among the various subsystems. Before the step of assembling the various subsystems into the exposure apparatus, there is, of course, an assembling step of the various subsystems. After the step of assembling the various subsystems into the exposure apparatus is completed, the overall adjustment is performed to ensure various accuracies of the entire exposure apparatus. Further, the exposure apparatus is preferably manufactured in a clean room in which temperature, cleanliness, and the like are controlled.

Industrial applicability

As described above, the exposure method and the exposure apparatus of the present invention are suitable for exposing an object. The device manufacturing method of the present invention is very suitable for manufacturing electronic devices such as semiconductor devices and liquid crystal display devices.

Claims (40)

1. An exposure apparatus for exposing a substrate with illumination light through a projection optical system, comprising:

a main frame having a main frame for supporting the projection optical system;

a detection system which is separated from the projection optical system, supported by the main frame, and detects position information of the substrate;

a base configured below the projection optical system and the detection system;

a stage having a holding device for holding the substrate and disposed on the base;

a drive system having a motor, a part of which is arranged on the stage, for moving the stage on the base to make the substrate be arranged opposite to the projection optical system and the detection system, respectively;

a 1 st measurement plate having four 1 st regions each forming a reflection type grating, the 1 st measurement plate being supported by the main frame such that the four 1 st regions are parallel to a predetermined plane and are arranged on a lower end side of the projection optical system;

a 2 nd measurement plate having four 2 nd regions each forming a reflection type grating, the 2 nd measurement plate being supported by the main frame so that the four 2 nd regions are parallel to the predetermined plane and are disposed on a lower end side of the detection system;

an encoder system having four heads provided on the stage, the four heads irradiating beams from below onto the 1 st or 2 nd measurement plate respectively to measure positional information of the stage; and

a control system for controlling the drive system based on the position information measured by the encoder system;

the encoder system measures positional information of the stage disposed below the 1 st measurement plate in the exposure step of the substrate, and measures positional information of the stage disposed below the 2 nd measurement plate in the detection step of the substrate by the detection system;

a moving area of the stage in the exposing step includes four coordinate systems for measuring the position information respectively by four sets of three heads removing mutually different heads one by one from the four heads;

measuring position information of the stage in a coordinate system different from one of the four coordinate systems, instead of one of the four coordinate systems, by movement of the stage within the movement area;

the control system obtains correction information for compensating for a position error of the one coordinate system and the different coordinate system caused by the offsets of the four 1 st areas, using position information measured by the encoder system at a part of a moving area of the stage where the four heads respectively oppose the four 1 st areas;

the correction information is used to drive and control the stage by using the three heads used in the different coordinate systems instead of controlling the drive of the stage by using the three heads used in the one coordinate system.

2. The exposure apparatus according to claim 1, wherein the four heads drive-control the stage with three heads used in the different coordinate system, instead of driving-controlling the stage with three heads used in the one coordinate system, at a part of the moving area that respectively opposes the four areas.

3. The exposure apparatus according to claim 1, wherein the correction information includes offsets for compensating for relative shifts of the four coordinate systems due to differences in combinations of three heads respectively used for the measurement of the position information in the four coordinate systems.

4. The exposure apparatus according to claim 1, wherein the correction information includes an offset for compensating for a difference between position information of the stage at a part of the movement area obtained from three heads used in the one coordinate system and position information obtained from three heads used in the different coordinate system.

5. The exposure apparatus according to claim 1, wherein the encoder system measures position information of the stage by any one of the four sets of three heads in a region different from the one portion among the moving regions.

6. The exposure apparatus according to any one of claims 1 to 5, wherein the encoder system, instead of one head of the three heads used in the one coordinate system, uses another head different from the three heads used in the one coordinate system among the four heads, and measures the position information of the stage in the different coordinate system by the another head, and three heads of two heads other than the one head among the three heads used in the one coordinate system.

7. The exposure apparatus according to claim 6, wherein subsequent information of the encoder system for controlling the driving of the stage is acquired using the other head based on the position information measured by the three heads used in the one coordinate system.

8. The exposure apparatus according to claim 7, wherein the continuation information is acquired while the stage is located in a part of the movement area.

9. The exposure apparatus according to claim 6, wherein the substrate is subjected to scanning exposure;

the switching from the one head to the other head is performed outside a scanning exposure period in which the illumination light is irradiated onto the substrate.

10. The exposure apparatus according to claim 6, wherein switching from the one head to the other head is performed outside a period during which the stage moves at a constant speed.

11. The exposure apparatus according to any one of claims 1 to 5, wherein the encoder system measures positional information of the stage in a 6-degree-of-freedom direction including a 1 st direction, a 2 nd direction, and a 3 rd direction that are orthogonal to the predetermined plane, the directions being orthogonal to each other within the predetermined plane.

12. The exposure apparatus according to claim 11, wherein the four heads are capable of measuring the position information of the stage in the 1 st direction or the 2 nd direction, and the 2 nd direction which is the 3 rd direction, respectively.

13. The exposure apparatus according to claim 11, wherein the 1 st and 2 nd measuring boards have four scale boards, respectively;

the scale plate is formed with a reflection type two-dimensional grating.

14. The exposure apparatus according to any one of claims 1 to 5, wherein the control system controls driving of the stage while compensating for a measurement error of the encoder system caused by at least one of a manufacturing error of the 1 st measurement plate, an acceleration of the stage, and a position or a tilt of the head.

15. The exposure apparatus according to any one of claims 1 to 5, wherein the encoder system has an auxiliary head disposed close to the head, and the head can be switched to the auxiliary head to continue performing the measurement.

16. The exposure apparatus according to any one of claims 13, further comprising:

a mask stage for holding a mask illuminated by the illumination light; and

an encoder system that measures positional information of the mask stage;

in the scanning exposure of the substrate, the drive of the mask stage and the stage is controlled so that the mask and the substrate move synchronously.

17. The exposure apparatus of claim 16, further comprising:

a stage different from the stage;

the encoder system has four different heads disposed on the different stages and different from the four heads, and measures position information of the different stages in the 6-degree-of-freedom direction by at least three heads among the four different heads.

18. The exposure apparatus according to claim 17, wherein the motor includes a flat motor having a magnet unit provided on one side of the base and the stage and a coil unit provided on the other side of the base and the stage, and the stage supported on the base in a floating manner is driven by the flat motor.

19. The exposure apparatus according to claim 18, wherein the stage is magnetically levitated on the base by the planar motor.

20. A device manufacturing method, comprising:

a step of exposing an object using the exposure apparatus according to any one of claims 1 to 19; and

and developing the exposed object.

21. An exposure method for exposing a substrate with illumination light through a projection optical system, comprising:

a step of driving a stage having a holding device for holding the substrate by a motor having a part of the stage provided on the stage, in such a manner that the substrate is arranged on a base which is separated from each other and supported below the projection optical system and the detection system of the main frame of the body, and the surface of which is parallel to a predetermined surface perpendicular to the optical axis of the projection optical system, so as to be opposed to the detection system to detect positional information of the substrate by the detection system;

driving the substrate on the base by the motor so that the substrate is disposed opposite to the projection optical system in order to expose the substrate with the illumination light through the projection optical system;

a step of measuring position information of the stage by an encoder system that irradiates four heads provided on the stage with light beams from below a 1 st measurement plate supported by the main frame so that the four 1 st areas are parallel to a predetermined surface and arranged on a lower end side of the projection optical system, in the exposure step of the substrate, the four 1 st areas each having a reflection type grating; and

controlling the drive of the motor to the stage according to the measured position information;

in the step of detecting the substrate by the detection system, the position information of the stage disposed below a 2 nd measurement plate is measured by the encoder system, the 2 nd measurement plate having four 2 nd areas each forming a reflection type grating, the four 2 nd areas being supported by the main frame so as to be parallel to the predetermined plane and disposed on a lower end side of the detection system;

a movement region of the stage in the exposure step includes four coordinate systems that respectively measure the position information by removing four sets of three heads of heads different from each other one by one from the four heads, and measures the position information of the stage in a coordinate system different from one coordinate system among the four coordinate systems, instead of one coordinate system of the four coordinate systems, by movement of the stage in the movement region;

acquiring correction information for compensating for a position error of the one coordinate system and the different coordinate system generated by the offsets of the four 1 st sections, using position information measured by the encoder system at a portion of the moving sections of the four heads respectively opposite to the four 1 st sections;

the correction information is used to drive and control the stage by using the three heads used in the different coordinate systems instead of controlling the drive of the stage by using the three heads used in the one coordinate system.

22. The exposure method according to claim 21, wherein the four heads drive-control the stage with three heads used in the different coordinate system, instead of driving-controlling the stage with three heads used in the one coordinate system, at a part of the moving area that respectively opposes the four areas.

23. The exposure method according to claim 21, wherein the correction information includes offsets for compensating for relative shifts of the four coordinate systems due to differences in combinations of three heads respectively used for the measurement of the position information in the four coordinate systems.

24. The exposure method according to claim 21, wherein the correction information includes an offset for compensating for a difference between position information of the stage at a part of the moving area obtained from three heads used in the one coordinate system and position information obtained from three heads used in the different coordinate system.

25. The exposure method according to claim 21, wherein position information of the stage is measured by any one of the four sets of three heads in a region different from the one portion among the moving regions.

26. The exposure method according to any one of claims 21 to 25, wherein, instead of one head of the three heads used in the one coordinate system, the position information of the stage in the different coordinate system is measured by another head, which is different from the three heads used in the one coordinate system, among the four heads, and three heads of two heads, other than the one head, among the three heads used in the one coordinate system.

27. The exposure method according to claim 26, wherein subsequent information of the encoder system for controlling the driving of the stage is acquired using the other head based on the position information measured by the three heads used in the one coordinate system.

28. The exposure method of claim 27, wherein the continuation information is acquired during a period when the stage is located at a portion of the moving area.

29. The exposure method according to claim 26, wherein the substrate is subjected to scanning exposure;

the switching from the one head to the other head is performed outside a scanning exposure period in which the illumination light is irradiated onto the substrate.

30. The exposure method according to claim 26, wherein switching from the one head to the other head is performed outside a period during which the stage moves at a constant speed.

31. The exposure method according to any one of claims 21 to 25, wherein the encoder system measures positional information of the stage in a 6-degree-of-freedom direction including a 1 st direction, a 2 nd direction, and a 3 rd direction that are orthogonal to the predetermined plane, which are orthogonal to each other within the predetermined plane.

32. The exposure method according to claim 31, wherein the four heads are capable of measuring the position information of the stage in the 1 st direction or the 2 nd direction, and the 2 nd direction from the 3 rd direction, respectively.

33. The exposure method according to claim 31, wherein the 1 st and 2 nd measurement boards each have four scale boards;

the scale plate is formed with a reflection type two-dimensional grating.

34. The exposure method according to any one of claims 21 to 25, wherein driving of the stage is controlled while compensating for a measurement error of the encoder system caused by at least one of a manufacturing error of the 1 st measurement plate, an acceleration of the stage, and a position or a tilt of the head.

35. The exposure method according to any one of claims 21 to 25, wherein the measurement can be continued by switching the head to an auxiliary head close to the head.

36. The exposure method according to claim 33, wherein the position information of a mask stage that holds a mask illuminated by the illumination light is measured by the encoder system;

in the scanning exposure of the substrate, the drive of the mask stage and the stage is controlled so that the mask and the substrate move synchronously.

37. The exposure method according to claim 36, wherein the substrate is held by a stage different from the stage;

the position information of the different stages in the 6-degree-of-freedom direction is measured by at least three heads among four heads that are provided on the different stages and are different from the four heads.

38. The exposure method according to claim 37, wherein the motor includes a planar motor having a magnet unit provided on one side of the base and the stage and a coil unit provided on the other side of the base and the stage, and the stage supported on the base in a floating manner is driven by the planar motor.

39. The exposure method of claim 38, wherein the stage is magnetically levitated on the base by the planar motor.

40. A device manufacturing method, comprising:

a step of exposing the object using the exposure method according to any one of claims 21 to 39; and

and developing the exposed object.