HK1214369B - Exposure method and exposure apparatus, and device manufacturing method - Google Patents

Description

Exposure method, exposure device, and device manufacturing method

This application is a divisional application of the invention patent application with application number 201080037584.X, PCT international application date August 24, 2010, and invention name “Exposure method and exposure device, and component manufacturing method”.

Technical Field

The present invention relates to an exposure method and an exposure device, as well as a component manufacturing method, and particularly relates to an exposure method and an exposure device used in photolithography processing for manufacturing micro components (electronic components) such as semiconductor components, and a component manufacturing method using the above-mentioned exposure method or exposure device.

Existing technology

Traditionally, for the photolithography process of manufacturing electronic components (microcomponents) such as semiconductor components (integrated circuits, etc.) and liquid crystal display components, projection exposure devices using a step-and-repeat method (so-called steppers) or projection exposure devices using a step-and-scan method (so-called scanning steppers (also called scanners)) have been mainly used.

As semiconductor devices become increasingly integrated and their patterns become finer, such exposure equipment is required to have higher overlay accuracy (positioning accuracy). Therefore, the position measurement of substrates such as wafers or glass plates on which patterns are formed is also required to be more accurate.

As a device that responds to this demand, for example, Patent Document 1 discloses an exposure device equipped with a position measurement system. This position measurement system uses a plurality of encoder-type sensors (encoder heads) mounted on a substrate stage. In this exposure device, the encoder head measures the position of the substrate stage by irradiating a measurement beam to a scale arranged opposite the substrate stage and receiving a return beam from the scale. In the position measurement system disclosed in Patent Document 1, it is best that the scale covers the moving area of the substrate stage as much as possible except for the area directly below the projection optical system. Therefore, although there is a need for a large-area scale, it is not only very difficult but also very costly to produce a large-area scale with high precision. Therefore, generally, a plurality of small-area scales are produced by dividing the scale into a plurality of parts and combining them. Therefore, although it is hoped that the position alignment between the plurality of scales can be performed correctly, in reality, it is very difficult to produce a scale without individual errors and to add the scales together without errors.

Prior art literature

[Patent Document 1] U.S. Patent Application Publication No. 2006/0227309

Summary of the Invention

The present invention is completed under the above circumstances. According to the first aspect, a first exposure method for exposing an object is provided, which includes: an action of obtaining correction information of deviations between a plurality of different reference coordinate systems corresponding to the plurality of head groups in a first moving area of the moving body that moves along a predetermined plane, wherein a plurality of head groups including at least one different head among a plurality of heads provided on the moving body face corresponding areas of a measuring surface arranged outside the moving body to be approximately parallel to the predetermined plane; and an action of obtaining position information of the moving body using each of the plurality of heads belonging to the plurality of head groups in the first moving area, and driving the moving body using the position information and the correction information of the deviations between the plurality of different reference coordinate systems corresponding to the plurality of head groups, so as to expose the object held on the moving body.

According to this method, the position information of the movable body obtained using the multiple readers corresponding to the multiple reader groups can be used to drive the movable body with good accuracy within the first moving area without being affected by the deviation between the multiple different reference coordinate systems corresponding to the multiple reader groups, thereby performing high-precision exposure on the object held by the movable body.

According to the second aspect of the present invention, a second exposure method for exposing an object includes: to expose the object, driving the movement of the movable body using at least one of first position information and second position information obtained by the first and second head groups, among a first number of heads carried on a movable body holding the object, within predetermined areas facing each other corresponding to areas on a measuring surface.

According to this method, even if the coordinate systems corresponding to the first head and the second head are different, the movable body can be driven with high precision without being affected by the different coordinate systems.

According to the third aspect of the present invention, a first exposure device for exposing an object includes: a movable body that keeps the object moving along a predetermined plane; a position measurement system that obtains position information of the movable body based on the output of a plurality of readers provided on the movable body, which irradiates a measuring beam to a measuring surface arranged outside the movable body to be approximately parallel to the predetermined plane near the exposure position of the object and receives a return beam from the measuring surface; and a control system that drives the movable body based on the position information obtained by the position measurement system and switches the reader used by the position measurement system to obtain the position information from the plurality of readers based on the position of the movable body; the control system corrects the mutual deviations between the plurality of reference coordinate systems corresponding to the plurality of readers in a first moving area of the movable body where the plurality of readers face the measuring surface.

According to this device, since the deviations between the plurality of reference coordinate systems are corrected, the position information of the movable body can be measured with high precision using the plurality of heads for driving (position control).

According to the fourth aspect of the present invention, a second exposure device for exposing an object is provided, which includes: a movable body for keeping the object moving along a predetermined plane; a position measurement system for obtaining position information of the movable body based on the output of a first number of readers mounted on the movable body, which irradiates a measuring beam to a measuring surface arranged outside the movable body to be approximately parallel to the predetermined plane near the exposure position of the object and receives a return beam from the measuring surface; a drive system for driving the movable body; and a control system for controlling the drive system using at least one of the first position information and the second position information obtained by the first and second head groups in a predetermined area where a first head group including a different head and a second head group each belonging to the first number of heads in the position measurement system face corresponding areas on the measuring surface.

According to this device, even if the coordinate systems corresponding to the first head and the second head are different, the movable body can be driven with high precision without being affected by the different coordinate systems.

According to the fifth aspect of the present invention, there is provided a third exposure device for exposing an object, which includes: a movable body that keeps the object moving along a predetermined plane; a position measurement system that obtains position information of the movable body based on the output of a plurality of readers provided on the movable body, which irradiates a measuring beam to a measuring surface arranged outside the movable body to be approximately parallel to the predetermined plane near the exposure position of the object and receives a return beam from the measuring surface; and a control system that drives the movable body based on the position information obtained by the position measurement system and moves the movable body within an area where the position can be measured by a second number of readers, which is greater than the first number of readers used for position control of the movable body, so as to obtain correction information of the position information of the movable body obtained by the position measurement system.

According to this device, since the control system obtains correction information for the position information of the movable body obtained by the position measurement system, the movable body can be driven with high precision using the correction information.

According to the sixth aspect of the present invention, there is provided a third exposure method for exposing an object, comprising: an action of moving the movable body within a first moving area of the movable body facing a measuring surface arranged outside the movable body to be roughly parallel to the predetermined plane, the action of obtaining correction information of the position information of the movable body moving along the predetermined plane obtained by the position measurement system, by using the correction information to drive the movable body 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 seventh aspect of the present invention, there is provided a fourth exposure device for exposing an object, which includes: a movable body for keeping the object moving along a predetermined plane; a position measurement system for obtaining position information of the movable body based on the output of a plurality of readers provided on the movable body, which irradiates a measuring beam to a measuring surface composed of a plurality of scale plates arranged outside the movable body to be roughly parallel to the predetermined plane near the exposure position of the object and receives a return beam from the measuring surface; and a control system for driving the movable body based on the position information obtained by the position measurement system, and switching the reader used by the position measurement system for obtaining the position information from the plurality of readers based on the position of the movable body; the control system for obtaining the mutual positional relationship of the plurality of scale plates corresponding to the plurality of readers in a first moving area of the movable body where the plurality of readers face the measuring surface.

According to this device, since the positional relationship between multiple scales is obtained by the control system, multiple reading heads can be used to measure the position information of the movable body with high precision and perform driving (position control).

According to the eighth aspect of the present invention, there is provided a fourth exposure method for exposing an object, comprising: an action of obtaining, within a first moving area of the movable body which moves along a predetermined plane and faces a measuring surface constituted by a plurality of scale plates arranged outside the movable body to be roughly parallel to the predetermined plane, a plurality of head groups to which a plurality of heads including at least one different head among a plurality of heads provided on the movable body respectively belong; and an action of obtaining, within the first moving area, position information of the movable body using the plurality of heads belonging to each of the plurality of head groups, and driving the movable body using the position information and the mutual position relationship of the plurality of scale plates corresponding to the plurality of head groups, so as to expose the object held by the movable body.

According to this method, the position information of the movable body obtained by the multiple readers belonging to the multiple reader groups can be used without being affected by the position offset between the multiple scale plates corresponding to the multiple reader groups, and the movable body can be driven with good precision within the first moving area, thereby enabling high-precision exposure of the object held by the movable body.

According to the ninth aspect of the present invention, the device manufacturing method comprises: exposing an object using any one of the first to fourth exposure devices of the present invention to form a pattern on the object; and developing the object with the pattern formed thereon.

According to a tenth aspect of the present invention, a device manufacturing method includes: forming a pattern on an object using any one of the first to fifth exposure methods of the present invention; and developing the object on which the pattern is formed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram schematically showing the configuration of an exposure apparatus according to one embodiment.

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

FIG3 is a diagram showing the configuration of an encoder system arranged around an alignment system.

FIG. 4 is an enlarged view showing a portion of the wafer stage in cross section.

FIG5 is a diagram showing the arrangement of the encoder head on the wafer stage.

FIG6 is a block diagram showing a main configuration of a control system associated with stage control in the exposure apparatus of FIG1.

Figure 7(A) is a diagram showing the relationship between the configuration of the encoder head and the scale plate and the measurement area of the encoder system, Figure 7(B) is a diagram showing the four stages coordinate systems corresponding to the four groups of encoder heads facing the scale plate, and Figure 7(C) is a diagram showing the situation where the four parts of the scale plate deviate from each other.

Figures 8(A), 8(C) and 8(E) are diagrams showing the movement of the wafer stage in the stage position measurement for correcting the stage coordinates (1, 2 and 3 thereof), and Figures 8(B), 8(D) and 8(F) are diagrams used to illustrate the correction of the four stage coordinate systems (1, 2 and 3 thereof).

Figures 9(A) and 9(B) are diagrams used to illustrate the measurement of the origin, rotation, and calibration of the combined stage coordinate system _CE .

FIG10(A) and FIG10(B) are diagrams for explaining the measurement of the origin, rotation, and scaling of the combined stage coordinate system _CA.

DETAILED DESCRIPTION

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

FIG1 schematically illustrates the configuration of an exposure apparatus 100 according to one embodiment. Exposure apparatus 100 is a step-and-scan projection exposure apparatus, also known as a scanner. As described later, this embodiment includes a projection optical system PL. The following description assumes that the direction parallel to the optical axis AX of projection optical system PL is the Z-axis direction, the direction for relative scanning of the reticle and wafer within a plane perpendicular to the Z-axis is the Y-axis direction, and the direction perpendicular to the Z and Y-axes is the X-axis direction. The directions of rotation (tilt) about the X, Y, and Z axes are the θx, θy, and θz directions, respectively.

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

Illumination system 10, as disclosed in, for example, U.S. Patent Application Publication No. 2003/0025890, comprises a light source, an illumination uniformization optical system including an optical integrator, and an illumination optical system including a reticle curtain (not shown). Illumination system 10 illuminates a slit-shaped illumination area IAR on reticle R, defined by a reticle curtain (masking system), with illumination light (exposure light) IL at a substantially uniform illumination intensity. Here, illumination light IL utilizes, for example, ArF excimer laser light (wavelength 193 nm).

Reticle R, having a circuit pattern or the like formed on its pattern surface (the lower surface in FIG1 ), is fixed to reticle stage RST by, for example, vacuum suction. Reticle stage RST can be micro-driven within the XY plane by, for example, a reticle stage drive system 11 (not shown in FIG1 , see FIG6 ) including a linear motor, and driven in a scanning direction (the Y-axis direction orthogonal to the paper in FIG1 ) at a predetermined scanning speed.

The position information of reticle stage RST within the XY plane (moving surface) (including the position information in the θz direction (θz rotation amount)) is continuously detected with a resolution of, for example, approximately 0.25 nm by a reticle laser interferometer (hereinafter referred to as "reticle interferometer") 16 shown in FIG1 , which irradiates a ranging beam onto movable mirror 15 (actually, a Y movable mirror (or retroreflector) having a reflective surface orthogonal to the Y-axis direction and an X movable mirror having a reflective surface orthogonal to the X-axis direction). Furthermore, to measure the position information of reticle R in at least three degrees of freedom (DOF) directions, an encoder system such as that disclosed in U.S. Patent Application Publication No. 2007/0288121 can be used in place of or in combination with reticle interferometer 16.

Projection unit PU is held in a main frame (also called a metrology frame) that is located below (-Z side) of reticle stage RST in FIG1 and constitutes a portion of a body (not shown). Projection unit PU includes a lens barrel 40 and a projection optical system PL composed of a plurality of optical elements held in lens barrel 40. Projection optical system PL is a refractive optical system that uses, for example, a plurality of optical elements (lens elements) arranged along an optical axis AX parallel to the Z-axis direction. Projection optical system PL is, for example, bilaterally telecentric and has a predetermined projection magnification (e.g., 1/4, 1/5, or 1/8). Therefore, when illumination area IAR is illuminated by illumination light IL from illumination system 10, illumination light IL, which passes through reticle R, whose pattern surface is substantially aligned with the first surface (object plane) of projection optical system PL, forms a reduced image of the circuit pattern of reticle R within illumination area IAR (a reduced image of a portion of the circuit pattern) through projection optical system PL on a region (exposure area) IA conjugate with illumination area IAR on wafer W, which is disposed on the second surface (image plane) side of projection optical system PL and coated with a resist (sensor). Next, by synchronously driving reticle stage RST and wafer stages WST1 and WST2, reticle R is moved in the scanning direction (Y-axis direction) relative to illumination area IAR (illumination light IL), and wafer W is moved in the scanning direction (Y-axis direction) relative to exposure area IA (illumination light IL), thereby performing scanning exposure of a single exposure area (division area) on wafer W, transferring the pattern of reticle R to the exposure area. That is, in this embodiment, the pattern of the reticle R is generated on the wafer W by the illumination system 10 and the projection optical system PL, and the pattern is formed on the wafer W by exposing the sensing layer (resist layer) on the wafer W with the illumination light IL.

The main frame may be of a commonly used portal type or a suspended support type as disclosed in, for example, US Patent Application Publication No. 2008/0068568.

A scale plate 21 is arranged around the -Z end of the lens barrel 40, for example, at approximately the same level as the lower end of the lens barrel 40 and parallel to the XY plane. In this embodiment, as shown in FIG2 , the scale plate 21 is composed of four L-shaped parts (components), 21 ₁ , 21 ₂ , 21 ₃ , and 21 ₄ . The scale plate 21 is inserted into a rectangular opening 21 a formed in its center, for example, at the -Z end of the lens barrel 40. The widths of the scale plate 21 in the X-axis and Y-axis directions are a and b, respectively, and the widths of the opening 21 a in the X-axis and Y-axis directions are _ai and _bi , respectively.

As shown in FIG1 , a scale plate 22 is disposed approximately flush with the scale plate 21 at a position separated from the scale plate 21 in the +X direction. As shown in FIG3 , the scale plate 22 is also composed of four L-shaped parts (components) 22 ₁ , 22 ₂ , 22 ₃ , and 22 ₄ . A rectangular opening 22 a, for example, is formed in the center thereof, into which the -Z side end of the alignment system ALG, described later, is inserted. The widths of the scale plate 22 in the X-axis and Y-axis directions are a and b, respectively, and the widths of the opening 22 a in the X-axis and Y-axis directions are ai and bi, respectively. Furthermore, in this embodiment, while the widths of the scale plates 21 and 22 in the X-axis and Y-axis directions and the widths of the openings 21 a and 22 a are set to be the same, they do not necessarily need to be the same width and may differ in at least one of the X-axis and Y-axis directions.

In this embodiment, scale plates 21 and 22 are suspended from a main frame (not shown) that supports projection unit PU and alignment system ALG. A reflective two-dimensional diffraction grating RG is formed on the lower surfaces (the -Z side) of scale plates 21 and 22. The grating is composed of a grating with a predetermined pitch, for example, 1 μm, periodically arranged in a 45-degree direction relative to the X-axis (-45-degree direction relative to the Y-axis), and a grating with a predetermined pitch, for example, 1 μm, periodically arranged in a -45-degree direction relative to the X-axis (-135-degree direction relative to the Y-axis) (see Figures 2, 3, and 4). However, the two-dimensional diffraction grating RG and the encoder head (described later) contain an inactive region of width t near the outer edges of the portions 21 ₁ to 21 ₄ and 22 ₁ to 22 ₄ that constitute scale plates 21 and 22. Two-dimensional diffraction gratings RG of scale plates 21 and 22 respectively cover the movement ranges of wafer stages WST1 and WST2 at least during exposure and alignment (measurement).

As shown in FIG1 , the wafer stage device 50 comprises: a stage base 12 supported approximately horizontally on the ground by a plurality of (e.g., three or four) anti-vibration mechanisms (not shown), wafer stages WST1 and WST2 arranged on the stage base 12, a wafer stage driving system 27 (only a portion is shown in FIG1 , refer to FIG6 ) for driving the wafer stages WST1 and WST2, and a measurement system for measuring the positions of the wafer stages WST1 and WST2. The measurement system comprises the encoder systems 70 and 71 shown in FIG6 and a wafer laser interferometer system (hereinafter referred to as the wafer interferometer system) 18. The encoder systems 70 and 71 and the wafer interferometer system 18 will be described later. However, in this embodiment, the wafer interferometer system 18 is not necessarily required.

As shown in Figure 1, stage base 12 is constructed from a flat plate-shaped member. Its top surface is highly flat, serving as a guide surface for wafer stages WST1 and WST2 during their movement. Within stage base 12, a coil unit is housed, comprising a plurality of coils 14a arranged in a matrix with rows and columns in the XY two-dimensional directions.

In addition, another base member different from the carrier base 12 can be provided for suspending and supporting it, so that it has the function of a balancing mass (reaction force canceller) that allows the carrier base 12 to move according to the law of conservation of momentum due to the reaction force of the driving force of the wafer carriers WST1 and WST2.

As shown in FIG1 , wafer stage WST1 comprises a stage body 91 and a wafer table WTB1 disposed above stage body 91 and supported in a non-contact manner on stage body 91 by a Z-tilt drive mechanism (not shown). In this case, wafer table WTB1 is supported in a non-contact manner by the Z-tilt drive mechanism, which adjusts the balance between an upward force (repulsive force) such as an electromagnetic force and a downward force (attractive force) including its own weight at three points. The wafer table is then micro-driven in at least three degrees of freedom: the Z-axis, the θx direction, and the θy direction. A slider portion 91a is provided at the bottom of stage body 91. Slider portion 91a comprises a magnet unit composed of a plurality of magnets arranged in an XY two-dimensional arrangement within an XY plane, a housing that houses the magnet unit, and a plurality of air bearings disposed around the bottom surface of the housing. The magnet unit and the coil unit together form 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 drive method; a planar motor driven by a variable reluctance method may also be used.

Wafer stage WST1 is suspended on stage base 12 via the aforementioned plurality of air bearings, separated by a predetermined gap (spacing/gap/spatial distance), for example, a gap of several μm. It is driven in the X-axis, Y-axis, and θz directions by planar motor 30. Consequently, wafer table WTB1 (wafer W) can be driven relative to stage base 12 in six degrees of freedom (X-axis, Y-axis, Z-axis, θx-direction, θy-direction, and θz-direction (hereinafter referred to as X, Y, Z, θx, θy, θz)).

In this 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. The wafer stage drive system 27 is composed of a planar motor 30 and the aforementioned Z tilt drive mechanism. In addition, the planar motor 30 is not limited to a moving magnet method, but can also be a moving coil method. A magnetic levitation planar motor can also be used as the planar motor 30. In this case, the aforementioned air bearing can be omitted. In addition, the planar motor 30 can also be used to drive the wafer stage WST1 in the six degrees of freedom direction. Of course, the wafer stage WTB1 can also be fine-moved in at least one direction of the X-axis direction, the Y-axis direction, and the θz direction. That is, the wafer stage WST1 can be composed of a coarse/fine motion stage.

Wafer W is loaded on wafer table WTB1 by a wafer holder (not shown) and fixed by a chuck mechanism (for example, vacuum adsorption (or electrostatic adsorption)) (not shown). In addition, a first reference mark plate and a second reference mark plate are provided on a diagonal line on wafer table WTB1 across the wafer holder (for example, refer to FIG. 2 ). A plurality of reference marks are formed on these first and second reference mark plates, respectively, to be detected by a pair of reticle alignment systems 13A, 13B and alignment system ALG described later. Here, it is assumed that the positional relationship between the plurality of reference marks on the first and second reference mark plates FM1, FM2 is known.

The configuration of wafer stage WST2 is the same as that of wafer stage WST1.

Encoder systems 70 and 71 are used to determine (measure) the position information of wafer stages WST1 and WST2 in the six degrees of freedom directions (X, Y, Z, θx, θy, θz), respectively, within the exposure movement area, which includes the area immediately below projection optical system PL, and the measurement movement area, which includes the area immediately below alignment system ALG. The configuration of encoder systems 70 and 71 will be described in detail herein. The exposure movement area (first movement area) is the area within the exposure station (first area) where wafer exposure is performed through projection optical system PL, where the wafer stage moves during the exposure operation. This exposure operation not only involves, for example, exposure of all irradiated areas of the wafer to be transferred, but also includes preparatory operations for such exposure (for example, detection of the aforementioned fiducial marks). The moving area during measurement (the second moving area) is the area where the wafer stage moves during the measurement action within the measurement station (the second area) where the alignment system ALG is used to detect the wafer alignment marks and measure their position information. This measurement action not only includes, for example, the detection of multiple alignment marks of the wafer, but also includes the detection of the reference marks performed by the alignment system ALG (and the measurement of the wafer position information (step difference data) in the Z-axis direction).

As shown in the top views of Figures 2 and 3 , respectively, encoder heads (hereinafter referred to as heads, as appropriate) 60 ₁ to 60 ₄ are positioned at the four corners of wafer tables WTB1 and WTB2. The separation distance between heads 60 ₁ and 60 ₂ in the X-axis direction is equal to the separation distance between heads 60 ₃ and 60 ₄ in the X-axis direction, which is A. Furthermore, the separation distance between heads 60 ₁ and 60 ₄ in the Y-axis direction is equal to the separation distance between heads 60 ₂ and 60 ₃ in the Y-axis direction, which is B. These separation distances A and B are greater than the widths ai _{and bi} of opening 21a of scale plate 21. Strictly speaking, considering the width t of the aforementioned inactive region, A ≧ _ai + 2t and b ≧ _bi + 2t. As shown in FIG. 4 , which typically uses the read head 60 ₁ as an example, the read heads 60 ₁ to 60 ₄ are respectively housed in holes of a predetermined depth in the Z-axis direction formed in wafer tables WTB1 and WTB2 .

Read head 60 ₁ , as shown in FIG5 , is a two-dimensional read head with measurement directions in the 135-degree direction relative to the X-axis (i.e., -45-degree direction relative to the X-axis) and the Z-axis. Similarly, read heads 60 ₂ - 60 ₄ are two-dimensional read heads with measurement directions in the 225-degree direction relative to the X-axis (i.e., 45-degree direction relative to the X-axis) and the Z-axis, the 315-degree direction relative to the X-axis (i.e., -45-degree direction relative to the X-axis) and the Z-axis, and the 45-degree direction relative to the X-axis and the Z-axis, respectively. As shown in Figures 2 and 4 , read heads 60 ₁ - 60 ₄ irradiate a measurement beam onto two-dimensional diffraction gratings RG formed on the surfaces of portions 21 ₁ - 21 ₄ of scale plate 21 or portions 22 ₁ - 22 ₄ of scale plate 22, respectively. They receive the reflected and diffracted beams from two-dimensional diffraction gratings RG and measure the positions of wafer tables WTB1 and WTB2 (wafer stages WST1 and WST2) in respective measurement directions. For example, read heads 60 ₁ - 60 ₄ can each be a sensor head having the same configuration as the displacement measurement sensor head disclosed in U.S. Patent No. 7,561,280.

Read heads 60 ₁ - 60 ₄ constructed in the manner described above can almost ignore the effects of air fluctuations because the optical path length of the measurement beam in air is extremely short. However, in this embodiment, the light source and light detector are located outside each read head, specifically, inside (or outside) stage body 91, and only the optical system is located inside each read head. The light source and light detector are optically connected to the optical system via an optical fiber (not shown). To improve the positioning accuracy of wafer table WTB (fine movement stage), it is also possible to transmit a laser or other signal through air between stage body 91 (coarse movement stage) and wafer table WTB (fine movement stage) (hereinafter referred to as between the coarse/fine movement stages). Alternatively, a read head may be located on stage body 91 (coarse movement stage) to measure the position of stage body 91 (coarse movement stage), and another sensor may be used to measure the relative displacement between the coarse/fine movement stages.

When the wafer stages WST1 and WST2 are located in the aforementioned moving area during exposure, the reader 60 ₁ is configured to irradiate the scale plate 21 (part 21 ₁ ) with a measuring beam (measuring light) and receive a diffracted beam from a grating formed on the surface (bottom) of the scale plate 21 with a periodic direction of 135 degrees based on the X-axis, that is, in a direction of -45 degrees based on the X-axis (hereinafter referred to as simply the -45 degree direction), to measure the two-dimensional encoders 70 ₁ and 71 ₁ (refer to FIG6 ) of the positions of the wafer stages WTB1 and WTB2 in the -45 degree direction and the Z-axis direction. Similarly, the reading heads 60 ₂ to 60 ₄ respectively irradiate the scale plate 21 (parts 21 ₂ to 21 ₄ ) with a measuring beam (measuring light) and receive diffracted beams from the grating formed on the surface (bottom) of the scale plate 21 in the 225-degree direction based on the X-axis, that is, the +45-degree direction based on the X-axis (hereinafter referred to as simply the 45-degree direction), the 315-degree direction, that is, the -45-degree direction based on the X-axis, and the 45-degree direction as the periodic direction, to measure the two-dimensional encoders 70 2 to 70 4 and 71 2 to 71 4 (refer to FIG6 ) of the wafer tables _WTB1 and WTB2 in the 225-degree (45-degree) direction and the Z-axis direction positions, the 315- _degree (-45-degree) direction and the Z-axis direction positions, and the 45 _- degree direction and the Z- _axis direction positions.

Furthermore, when the wafer stages WST1 and WST2 are located in the aforementioned moving area during measurement, the read head 60 ₁ is configured to irradiate the scale plate 22 (part 22 ₁ ) with a measurement beam (measurement light) and receive a diffracted beam from a grating formed on the surface (bottom) of the scale plate 22 with a periodic direction of 135 degrees (-45 degrees), so as to measure the two-dimensional encoders 70 ₁ and 71 ₁ (refer to FIG6 ) of the positions of the wafer stages WTB1 and WTB2 in the 135 degree direction and the Z-axis direction. Similarly, the reading heads 60 ₂ to 60 ₄ are respectively configured to irradiate the scale plate 22 (parts 222 to 224) with a measuring beam (measuring light) and receive a diffracted beam from a grating formed on the surface (bottom) of the scale plate 22 with periodic directions of 225 degrees (45 degrees), 315 degrees (-45 degrees) and 45 degrees, so as to respectively measure the two-dimensional encoders 70 2 to 70 4 and 71 2 to 71 4 (refer to FIG6 ) of the wafer tables _WTB1 and WTB2 in the 225 degree direction (45 degree direction) and Z-axis direction positions, the 315 degree direction (-45 degree _direction ) and Z-axis direction positions, and the ₄₅ degree _direction and Z-axis direction positions.

As can be seen from the above description, in this embodiment, regardless of whether the measuring beam (measuring light) is irradiated on either of the scale plates 21 and 22, that is, regardless of whether the wafer stages WST1 and WST2 are in any of the aforementioned moving areas during exposure and moving areas during measurement, the readers 60 ₁ to 60 ₄ on the wafer stage WST1, together with the scale plate irradiated with the measuring beam (measuring light), respectively constitute two-dimensional encoders 70 ₁ to 70 ₄ , and the readers 60 ₁ to 60 ₄ on the wafer stage WST2, together with the scale plate irradiated with the measuring beam (measuring light), respectively constitute two-dimensional encoders 71 ₁ to 71 ₄ .

The measurement values of each of two-dimensional encoders (hereinafter referred to as encoders, as appropriate) 70 ₁ to 70 ₄ and 71 _{1 to 71 4} are supplied to main controller 20 (see FIG6 ). Main controller 20 determines position information of wafer tables WTB1 and WTB2 within an area of movement during exposure that includes an area immediately below projection optical system PL, based on the measurement values of at least three encoders (i.e., at least three encoders that output valid measurement values) facing the underside of scale plate 21 (constituting portions 21 ₁ to 21 _{4 )} on which two-dimensional diffraction grating RG is formed. Similarly, main controller 20 determines position information of wafer tables WTB1 and WTB2 within an area of movement during measurement that includes an area immediately below alignment system ALG, based on the measurement values of at least three encoders (i.e., at least three encoders that output valid measurement values) facing the underside of scale plate 22 (constituting portions 22 1 to 22 4 ) on which two-dimensional diffraction grating RG is formed.

Furthermore, in exposure apparatus 100 of this embodiment, the positions of wafer stages WST1 and WST2 (wafer tables WTB1 and WTB2) can be measured independently from encoder systems 70 and 71 by wafer interferometer system 18 (see FIG. 6 ). The measurement results of wafer interferometer system 18 are used as an auxiliary tool to correct (correct) long-term fluctuations in the measured values of encoder systems 70 and 71 (e.g., caused by time-dependent deformation of the scales), or as a backup in the event of abnormal outputs from encoder systems 70 and 71. A detailed description of wafer interferometer system 18 is omitted here.

As shown in Figure 1, the alignment system ALG is an off-axis alignment system positioned at a predetermined distance on the +X side of the projection optical system PL. In this embodiment, the alignment system ALG utilizes, for example, a Field Image Alignment (FIA) system, a type of image processing alignment sensor that illuminates a mark with broadband light, such as a halogen lamp, and measures the mark's position by performing image processing on the mark's image. The imaging signal from the alignment system ALG is supplied to the main control unit 20 (see Figure 6) via an alignment signal processing system (not shown).

Furthermore, the alignment system ALG is not limited to the FIA system. Alignment sensors that irradiate a mark with coherent detection light and detect scattered or diffracted light from the mark, or that interfere with two diffracted light beams (e.g., diffracted light beams of the same order or diffracted in the same direction) generated from the mark, may also be used alone or in combination. Alignment systems with multiple detection areas, such as those disclosed in U.S. Patent Application Publication No. 2008/0088843, may also be used as the alignment system ALG.

Furthermore, the exposure apparatus 100 of this embodiment is equipped with an oblique-incidence multi-point focus position detection system (hereinafter referred to as a multi-point AF system) (not shown in FIG1 , see FIG6 ) configured similarly to that disclosed in, for example, U.S. Patent No. 5,448,332, along with the alignment system ALG at the measurement station. The multi-point AF system performs at least a portion of its measurement operation in parallel with the mark detection operation performed by the alignment system ALG, and uses the encoder system to measure wafer stage position information during this measurement operation. Detection signals from the multi-point AF system are supplied to the main controller 20 (see FIG6 ) via an AF signal processing system (not shown). The main controller 20 detects Z-axis position information (step difference data/concave-convex information) on the surface of the wafer W based on the detection signals from the multi-point AF system and the measurement information from the encoder system. During the exposure operation, focus and leveling control of the wafer W during scanning exposure is performed based on this pre-detection information and the measurement information from the encoder system (position information in the Z-axis, θx, and θy directions). Furthermore, a multi-point AF system may be installed near the projection unit PU in the exposure station to measure the position information (concave-convex information) of the wafer surface while driving the wafer stage during the exposure operation to implement focusing and leveling control of the wafer W.

Exposure apparatus 100 further includes a pair of reticle alignment systems 13A and 13B (not shown in FIG1 , see FIG6 ) using a TTR (Through The Reticle) method using light of an exposure wavelength, such as disclosed in U.S. Patent No. 5,646,413, above reticle R. Detection signals from reticle alignment systems 13A and 13B are supplied to main controller 20 via an alignment signal processing system (not shown). Alternatively, an aerial image measuring device (not shown) provided on wafer stage WST may be used in place of the reticle alignment system for reticle alignment.

FIG6 is a partially omitted block diagram of the control system associated with stage control of exposure apparatus 100. This control system is centered around main control unit 20. Main control unit 20 includes a so-called microcomputer (or workstation) composed of a CPU (central processing unit), ROM (read-only memory), RAM (random access memory), and other components, and oversees the overall control of the apparatus.

During device manufacturing, exposure apparatus 100 configured as described above moves one of wafer stages WST1 and WST2, carrying a wafer, within a measurement station (a measurement movement area) via main controller 20 to perform wafer measurement using alignment system ALG and a multi-point AF system. Specifically, alignment system ALG is used to detect marks on wafer W held by one of wafer stages WST1 and WST2 within the measurement movement area, along with so-called wafer alignment (e.g., enhanced full wafer alignment (EGA) as disclosed in U.S. Patent No. 4,780,617), and measurement of wafer surface information (step difference/concave/convex information) using the multi-point AF system. At this time, encoder system 70 (encoders 70 ₁ to 70 ₄ ) or encoder system 71 (encoders 71 ₁ to 71 ₄ ) obtains (measures) position information of wafer stages WST1 and WST2 in the six degrees of freedom directions (X, Y, Z, θx, θy, θz).

After measurement actions such as wafer alignment, one wafer stage (WST1 or WST2) moves to the moving area during exposure, and the main control unit 20 uses the reticle alignment system 13A, 13B, the reference mark plate (not shown) on the wafer stage (WTB1 or WTB2), etc., to perform reticle alignment, etc. using the same procedure as a general scanning stepper (for example, the procedure disclosed in the specification of U.S. Patent No. 5,646,413, etc.).

Next, main controller 20 performs a step-and-scan exposure operation based on the measurement results of wafer alignment and other processes, transferring the pattern of reticle R to multiple shot areas on wafer W. The step-and-scan exposure operation is performed by alternately and repeatedly performing a scanning exposure operation, which synchronizes the movement of reticle stage RST and wafer stage WST1 or WST2, and an inter-shot movement (stepping) operation, which moves wafer stage WST1 or WST2 to the acceleration start position for exposure of the shot area. During the exposure operation, encoder system 70 (encoders 70 ₁ - 70 ₄ ) or encoder system 71 (encoders 71 ₁ - 71 ₄ ) determines (measures) the position information of one wafer stage (WST1 or WST2) in the six degrees of freedom directions (X, Y, Z, θx, θy, θz).

Furthermore, the exposure apparatus 100 of this embodiment includes two wafer stages WST1 and WST2. Therefore, the following parallel processing operations are performed: while step-and-scan exposure is performed on one wafer stage, for example, the wafer loaded on wafer stage WST1, wafer alignment is performed on the other wafer stage WST2 in parallel with this exposure.

In exposure apparatus 100 of this embodiment, as previously described, main controller 20 uses encoder system 70 (see FIG. 6 ) to determine (measure) position information in the six degrees of freedom (X, Y, Z, θx, θy, θz) of wafer stage WST1, both in the exposure movement area and the measurement movement area. Furthermore, main controller 20 uses encoder system 71 (see FIG. 6 ) to determine (measure) position information in the six degrees of freedom (X, Y, Z, θx, θy, θz) of wafer stage WST2, both in the exposure movement area and the measurement movement area.

Next, the principle of position measurement in the three degrees of freedom (X-axis, Y-axis, and θz direction (also referred to as X, Y, θz)) within the XY plane using encoder systems 70 and 71 will be further described. Here, the measurement results or values of encoder heads 60 ₁ to 60 ₄ or encoders 70 ₁ to 70 ₄ refer to the measurement results of encoder heads 60 ₁ to 60 ₄ or encoders 70 ₁ to 70 ₄ in measurement directions other than the Z-axis direction.

In this embodiment, by adopting the aforementioned configuration and arrangement of the encoder heads 60 ₁ - 60 ₄ and the scale plate 21 , at least three of the encoder heads 60 ₁ - 60 ₄ can constantly face the scale plate 21 (the corresponding parts 21 ₁ - 21 ₄ ) within the moving area during exposure.

FIG7(A) shows the relationship between the arrangement of encoder heads 60 ₁ to 60 ₄ and portions 21 ₁ to 21 ₄ of scale plate 21 on wafer stage WST1, and measurement areas A ₀ to A ₄ of encoder system 70. Since wafer stage WST2 has the same configuration as wafer stage WST1, only wafer stage WST1 will be described here.

When the center of wafer stage WST1 (coinciding with the center of the wafer) is within the area moved during exposure and within first area _A1 , an area on the +X and +Y sides of exposure center P (the center of exposure area IA) (the area within the first quadrant with exposure center P as the origin (but excluding area _A0 )), read heads ₆₀₄ , ₆₀₁ , and ₆₀₂ on wafer stage WST1 face portions ₂₁₄ , ₂₁₁ , and ₂₁₂ of scale plate 21, respectively. Within first area _A1 , valid measurement values are transmitted from read heads ₆₀₄ , ₆₀₁ , and ₆₀₂ (encoders ₇₀₄ , ₇₀₁ , and ₇₀₂ ) to main controller 20. The positions of wafer stages WST1 and WST2 in the following description refer to the positions of the centers of the wafer stages (coinciding with the centers of the wafers). That is, the positions of the centers of wafer stages WST1 and WST2 are described as the positions of wafer stages WST1 and WST2.

Similarly, when wafer stage WST1 is within the exposure movement area and in second area A2 on the -X and +Y sides relative to exposure center P (the area in the second quadrant with exposure center P as the origin (but excluding area _A0 ) ₎ , heads ₆₀₁ , ₆₀₂ , and ₆₀₃ respectively face portions ₂₁₁ , ₂₁₂ , and ₂₁₃ of scale plate 21. When wafer stage WST1 is within the exposure movement area and in third area A3 on the -X and -Y sides relative to exposure center P (the area in the third quadrant with exposure center P as the origin (but excluding area _A0 )), heads ₆₀₂ , ₆₀₃ , and ₆₀₄ respectively face portions ₂₁₂ , ₂₁₃ , and _{214 of} scale plate 21. When wafer stage WST1 is within the movement area during exposure and within the fourth area A4 on the +X and -Y sides relative to exposure center P (the area within the fourth quadrant with exposure center P as the origin (however, excluding area _A0 ) ₎ , read heads ₆₀₃ , ₆₀₄ , and ₆₀₁ face parts ₂₁₃ , ₂₁₄ , and ₂₁₁ of scale plate 21, respectively.

In this embodiment, under the aforementioned configuration and arrangement conditions (A ≧ a _i +2t, B ≧ b _i +2t) of encoder heads 60 ₁ - 60 ₄ and scale plate 21, as shown in FIG7A , when wafer stage WST1 is located within a cross-shaped area A ₀ centered on exposure center P (an area comprising an area with a width of A - a _i -2t, with the Y-axis direction passing through exposure center P as its longitudinal direction, and an area with a width of B - b _i -2t, with the X-axis direction as its longitudinal direction (hereinafter referred to as area 0)), all heads 60 ₁ - 60 ₄ on wafer stage WST1 face scale plate 21 (corresponding portions 21 ₁ - 21 ₄ ). Therefore, within area 0 A ₀ , valid measurement values are transmitted from all heads 60 ₁ - 60 ₄ (encoders 70 ₁ - 70 ₄ ) to main controller 20. In addition to the aforementioned conditions (A ≧ a _i + 2t, B ≧ b _i + 2t), this embodiment also considers the dimensions (W, L) of the exposure area on the wafer where the pattern is formed, and adds the conditions A ≧ a _i + W + 2t, B ≧ b _i + L + 2t. Here, W and L are the widths of the exposure area in the X-axis and Y-axis directions, respectively. W and L are equal to the distance between the scanning exposure intervals and the stepping distance in the X-axis direction, respectively.

Main controller 20 calculates the position (X, Y, θz) of wafer stage WST1 in the XY plane based on the measurement results of heads 60 ₁ to 60 ₄ (encoders 70 ₁ to 70 ₄ ). The measurement values of encoders 70 ₁ to 70 ₄ (represented as C ₁ to C ₄ , respectively) are expressed as shown in equations (1) to (4) below and depend on the position (X, Y, θz) of wafer stage WST1.

C ₁ =-(cosθz+sinθz)X/√2

+(cosθz－sinθz)Y/√2+√2psinθz…(1)

C ₂ =-(cosθz-sinθz)X/√2

-(cosθz+sinθz)Y/√2+√2psinθz…(2)

C ₃ = (cosθz + sinθz)X/√2

-(cosθz－sinθz)Y/√2+√2psinθz…(3)

C ₄ =(cosθz－sinθz)X/√2

+(cosθz+sinθz)Y/√2+√2Psinθz…(4)

As shown in FIG5 , p is the distance from the center of wafer table WTB1 (WTB2) to the read head in the X-axis and Y-axis directions.

Main control unit 20 identifies three readers (encoders) facing scale plate 21 based on areas A ₀ to A ₄ where wafer stage WST1 is located, and selects equations based on these measurement values from equations (1) to (4) above to combine simultaneous equations. The simultaneous equations are solved using the measurement values of the three readers (encoders) to calculate the position (X, Y, θz) of wafer stage WST1 in the XY plane. For example, when wafer stage WST1 is located in first area A ₁ , main control unit 20 combines simultaneous equations based on equations ( ₁ ), (2 ₎ , and (4) based on the measurement values of readers 60 ₁ , 60 2 , and 60 ₄ (encoders 70 1 , 70 ₂ , and 70 ₄ ), and substitutes the measurement values of each reader into the left side of each of equations (1), (2), and (4) to solve the simultaneous equations. The calculated position (X, Y, θz) is expressed as X ₁ , Y ₁ , θz ₁ . Similarly, when wafer stage WST1 is within the kth area _Ak , main controller 20 composes simultaneous equations based on the measurement values ( _{k-1), (k), and (k+1) of heads 60 k-1 , 60} k , and 60 _k+1 (encoders 70 k-1 , 70 _k , and 70 k ₊₁ ). Substituting the measurement values of each head into the left side of the equations, the simultaneous equations are solved. The position (X _k , Y _k , θz _k ) is calculated accordingly. Here, k-1, k, and k+1 are periodically permuted numbers from 1 to 4.

Furthermore, when wafer stage WST1 is positioned within area 0 _A0 , main controller 20 may select any three of heads 60 ₁ to 60 ₄ (encoders 70 ₁ to 70 ₄ ). For example, after wafer stage WST1 moves from area 1 to area 0, heads 60 ₁ , 60 ₂ , and 60 ₄ (encoders 70 ₁ , 70 ₂ , and 70 ₄ ) corresponding to area 1 may be selected.

Main controller 20 drives wafer stage WST1 (performs position control) within the movement area during exposure based on the calculation results (X, Y, θz).

When wafer stage WST1 is within the movement area during measurement, main controller 20 measures position information in the three degrees of freedom directions (X, Y, and θz) using encoder system 70. The measurement principle and other aspects are the same as for the case where wafer stage WST1 is within the movement area during exposure, except that exposure center P is replaced by the detection center of alignment system ALG and scale plate 21 (portions 21 ₁ to 21 ₄ ) is replaced by scale plate 22 (portions 22 ₁ to 22 ₄ ).

Furthermore, main control unit 20 switches at least one of three encoder heads 60 ₁ - 60 ₄ facing scale plates 21 and 22 for use, based on the positions of wafer stages WST1 and WST2. When switching encoder heads, a connection process is performed to ensure the continuity of wafer stage position measurement results, such as that disclosed in U.S. Patent Application Publication No. 2008/0094592.

As previously described, scale plates 21 and 22 in exposure apparatus 100 of this embodiment are respectively composed of four sections 21 ₁ to 21 ₄ and 22 ₁ to 22 _4. Here, if the four sections, or more precisely, the two-dimensional diffraction gratings RG formed under the four sections, deviate from each other, measurement errors of encoder systems 70 and 71 may occur.

FIG7(B) and FIG7(C) schematically illustrate the kth reference coordinate system C _k (k = 1 to 4) corresponding to the position ( _{X k} , Y _k , θz k ) of wafer stage WST1 or _WST2 calculated from the effective measurement values of heads 60 _k- 1 , 60 _k , and 60 _k+ 1 (encoders 70 _k-1 , 70 k , 70 _k +1 or encoders 71 _k -1 , 71 _k , 71 _{k +} 1) within the kth region _Ak (k = 1 to 4). The four reference coordinate systems C ₁ to C ₄ correspond to the arrangement of regions A ₁ to A ₄ (see FIG7(A) ), overlap with each other near origin O, and overlap with adjacent reference coordinate systems in a cross-shaped region C ₀ centered on origin O.

When the configuration of scale plate 21 is as designed, that is, when the two-dimensional diffraction gratings RG formed in the four portions 21 ₁ - 21 ₄ are aligned, as shown in FIG7B , the origins O ₁ -O ₄ of the four reference coordinate systems C ₁ -C ₄ coincide with each other (indicated by the symbol O in the figure), and the rotations θz ₁ -θz ₄ and the scalings Γx ₁ -Γx ₄ and Γy ₁ -Γy ₄ also coincide with each other. Therefore, the four reference coordinate systems can be combined into a single coordinate system _CE . Specifically, the positions of wafer stages WST1 and WST2 within movement areas A ₁ -A ₄ during exposure can be expressed as position coordinates X, Y, and θz in the combined coordinate system _CE .

However, if the two-dimensional diffraction gratings RG formed in the four portions 21 ₁ to 21 ₄ are misaligned, as shown in FIG7(C), the origins O ₁ to O ₄ , rotations θz ₁ to θz ₄ , and scales Γx ₁ to Γx ₄ and Γy ₁ to Γy ₄ of the four reference coordinate systems C ₁ to C ₄ may deviate from each other, leading to measurement errors. Therefore, in the example shown in FIG7(B), the four reference coordinate systems cannot be combined into a single coordinate system _CE .

Likewise, when the four parts 22 ₁ - 22 ₄ constituting the scale plate 22 , or more precisely, when the two-dimensional diffraction gratings RG formed under the four parts 22 ₁ - 22 ₄ , deviate from each other, a measurement error of the encoder system 70 or 71 may occur.

Therefore, this embodiment adopts a correction method for correcting the deviations among the four reference coordinate systems _C1 to _C4 caused by the deviations among the parts ₂₁₁ to ₂₁₄ and ₂₂₁ to ₂₂₄ constituting the scale plates 21 and 22. Next, the correction method will be described in detail using the scale plate 21 as an example.

First, as shown in FIG8(A), main controller 20 positions wafer stage WST1 (WST2) within area _A0 . In FIG8(A), wafer stage WST1 is positioned at the center of area _A0 (immediately below projection optical system PL). Within area _A0 , heads 60 ₁ to 60 ₄ mounted on wafer stage WST1 all face scale plate 21 (corresponding portions 21 ₁ to 21 ₄ thereof) and transmit valid measurement values to main controller 20. Main controller 20 calculates the position (X k , Y k , θz k ) of wafer stage _WST1 using the measurement values of heads 60 _k-1 , 60 _k , and 60 _k+2 (referred to as the _k th head group) used within area Ak (= ₁ to ₄ ). Main control device 20 calculates the deviation of the position ( _Xk , _Yk ) calculated from the measurement values of the kth (=2-4) head group relative to the position ( _X1 , _Y1 ) calculated from the measurement values of the first head group, that is, the offset ( _OXk = _Xk - _X1 , _OXk = _Yk - _Y1 ).

Furthermore, the offset (O _Xk , O _Yk ) for the rotation θz may be obtained together with the offset (O _θzk = θz _k - θz ₁ ). In this case, the calculation of the offset O _θzk described later is omitted.

The calculated offsets ( _OXk , _OXk ) are used to correct the positions ( _Xk , Yk) calculated from the measurements of the kth (2nd to _4th ) head group to ( _Xk - _OXk , _Yk - _OXk ). This correction results in the origin Ok of the kth reference coordinate system _Ck (2nd to 4th) coinciding with the origin _O1 of the first reference coordinate system _C1 , as shown in FIG8B. In the figure, these coincident origins are denoted by the symbol _O.

Next, as shown in FIG8(C), main control unit 20 drives wafer stage WST1 in the direction of the arrows (X-axis direction and Y-axis direction) within area _A0 based on the stage position ( _X1 , _Y1 , _θz1 ) calculated from the measurement values of the first head group as a correction reference, and calculates the positions of the four wafer stages WST1 ( _Xk , _Yk (k=1 to 4)) using the measurement values of the four head groups while positioning them at predetermined intervals.

Main controller 20 uses the four stage positions (X _k , Y _k (k = 1 to 4)) obtained above to determine offset O _θzk using, for example, a least squares calculation to minimize the squared error ε _k = Σ((ξ _k - X ₁ ) ² +(ζ _k - _{Y 1} ) ² ). Here, k = 2 to 4. (ξ _k , ζ _k ) are the stage positions (X _k , Y _k (k = 2 to 4)) that have been rotationally transformed using the following equation (5). While the least squares method is used as an example to determine offset O _θzk , this is not limiting, and calculation methods other than the least squares method may also be used.

The offset _Oθzk obtained above is used to correct the rotation _θzk calculated from the measurement values of the kth (= 2-4) head group to _θzk - _Oθzk . With this correction, the direction (rotation) of the kth reference coordinate system _Ck (= 2-4) coincides with the direction (rotation) of the first reference coordinate system _C1 , as shown in FIG8(D).

Next, as in the previous example, main controller 20 drives wafer stage WST1 in the directions of arrows (X-axis and Y-axis directions) within area _A0 based on the stage position ( _X1 , _Y1 , _θz1 ), and determines the positions ( _Xk , _Yk (k=1 to 4)) of the four wafer stages WST1 while positioning them at predetermined intervals, as shown in FIG8(E).

Main controller 20 uses the four stage positions (X _k , Y _k (k = 1 to 4)) obtained above to determine the scaling (Γ _{X k} , Γ _{Y k} ) by least squares calculation to minimize the squared error ε _k = Σ((ξ _k '-X ₁ ) ² +(ζ _k '-Y ₁ ) ² ). Here, k = 2 to 4. Here, (ξ _k ', ζ _k ') are the stage positions (X _k , Y _k (k = 2 to 4)) scaled using the following equation (6).

The calibration (Γ _Xk , Γ _Yk ) calculated above is used to correct the positions ( _Xk , Yk) calculated from the measurements of the kth (= _2-4 ) head group to ( _Xk /(1+Γ _Xk ), _Yk /(1+Γ _Yk )). With this correction, as shown in FIG8(F), the calibration of the kth reference coordinate system _Ck (=2-4) becomes consistent with the calibration of the first reference coordinate system _C1 .

Through the above processing, the four reference coordinate systems C ₁ -C ₄ that have been rotated and scaled are combined into a coordinate system (combined coordinate system) _CE covering the movement areas A ₀ -A ₄ during exposure.

Alternatively, instead of the above processing, the offset and calibration (O _Xk , O _Yk , O _θzk , Γ _Xk , Γ _Yk (k=2-4)) may be obtained by the following processing. Specifically, as shown in FIG8(C) or FIG8(E), main controller 20 drives wafer stage WST1 in the directions of arrows (X-axis direction and Y-axis direction) within area _A0 based on the stage position ( _X1 , _Y1 , _θz1 ), and obtains the positions ( _Xk , _Yk (k=1-4)) of the four wafer stages WST1 while positioning them at predetermined intervals. Main controller 20 uses the four determined stage positions ( _Xk , _Yk (k = 1 to 4)) to determine the offset and calibration ( _OXk , _OYk , _Oθzk , _ΓXk , _ΓYk ) using a least squares operation to minimize the squared error _εk = Σ((ξ” _k - _X1 ) ² + (ζ” _k - _Y1 ) ² ). Here, k = 2 to 4. Here, (ξ” _k , ζ” _k ) are the stage positions ( _Xk , _Yk (k = 2 to 4)) converted using the following equation (7).

Furthermore, while the above process directly calculates the offsets and scaling for the second to fourth reference coordinate systems _{C2 to C4} based on the first reference coordinate system _C1 , these can also be calculated indirectly. For example, the above procedure calculates the offsets and scaling (O _X2 , O _Y2 , O _θz2 , Γ _X2 , Γ _Y2 ) for the second reference coordinate system _C2 based on the first reference coordinate system C1. Similarly, the offsets and scaling (O _X32 , O _Y32 , O _θz32 , Γ _X32 , Γ _Y32 ) for the third reference coordinate system _C3 based on the _second reference coordinate system C2 are calculated. From these results, the offset and scaling for the third reference coordinate system _{C3 , which} is based on the first reference coordinate system C1, are calculated as ( _OX3 = _OX32 + _OX2 , _OX3 = OX32 + OX2, OX3 = _OX32 + _OX2 , _OX3 = _OX32 + _OX2 , _OX3 = _OX32 + _OX2 , _OX3 = _OX32 + _OX2 .) Similarly, the offset and scaling for the fourth reference coordinate system C4 _{, which} is based on the third reference coordinate system _C3 , can be calculated, and the results are used to calculate the offset and scaling for the fourth reference coordinate system _C4, which is based on the first reference coordinate system _C1 .

The main control unit 20 also calibrates the four reference coordinates for the scale plate 22 according to the same procedure, and combines the four reference coordinate systems covering the moving area during measurement into one coordinate system (combined coordinate system) _CA (see FIG. 7(B)).

Finally, main controller 20 calculates the position, rotation, and calibration deviations between combined coordinate system _CE, which covers the exposure movement area _A0 to _A4 , and combined coordinate system _CA , which covers the measurement movement area. As shown in FIG9(A), main controller 20 uses encoder system 70 to calculate (measure) the position information of wafer stage WST1. Based on the measurement result, main controller 20 drives wafer stage WST1 to position first fiducial mark plate FM1 on wafer table WTB1 directly below projection optical system PL (exposure center P). Main controller 20 uses a pair of reticle alignment systems 13A and 13B to detect two (a pair of) fiducial marks formed on first fiducial mark plate FM1. Next, based on the measurement result of encoder system 70, main controller 20 drives wafer stage WST1 to position second fiducial mark plate FM2 on wafer table WTB1 directly below projection optical system PL (exposure center P). Using either of the pair of reticle alignment systems 13A and 13B, main controller 20 detects a single fiducial mark formed on second fiducial mark plate FM2. The main controller 20 calculates the position, rotation, and scaling of the origin of the combined coordinate system _CE from the detection results of the three reference marks (i.e., the two-dimensional position coordinates of the three reference marks).

Main controller 20 moves wafer stage WST1 to the measurement movement area. At this point, main controller 20 uses wafer interferometer system 18 in the area between exposure movement areas _A0 - _A4 and the measurement movement area, and encoder system 70 within the measurement movement area to measure position information of wafer stage WST1. Based on these measurements, main controller 20 drives (position controls) wafer stage WST1. After the movement, main controller 20, as shown in Figures 10(A) and 10(B), uses alignment system ALG to detect the three fiducial marks in the same manner as before. Based on these detection results, the position, rotation, and calibration of the origin of combined coordinate system _CA are determined. In addition, although it is better to use the same mark as the three reference marks that are the detection objects of the reticle alignment systems 13A and 13B and the three reference marks that are the detection objects of the alignment system ALG, when it is impossible to detect the same reference mark by the reticle alignment systems 13A and 13B and the alignment system ALG, since the positional relationship between the reference marks is known, the reticle alignment systems 13A and 13B and the alignment system ALG can use different reference marks as the detection objects.

Furthermore, when the wafer stage moves between the moving area during exposure and the moving area during measurement, the encoder system can also be used to control the position of the wafer stage. Connection processing (phase connection and/or coordinate connection) is performed separately in the moving area during exposure and the moving area during measurement. Here, coordinate connection refers to the connection processing of setting the measurement value of the encoder used after switching and resetting the phase offset at this time in order to make the calculated position coordinates of the wafer stage WST completely consistent before and after switching the encoder (reader). The phase connection method is basically the same as the coordinate connection method, but the processing of the phase offset is different. The phase offset is not reset, and the set phase offset is continued to be used, and only the count value is reset.

Main controller 20 calculates the deviation in origin, rotation, and scaling between combined coordinate systems CE and _CA from the position, rotation, and scaling of the origin of combined coordinate system _CE and _the position, rotation, and scaling of the origin of combined coordinate system _CA. Main controller 20 can use this deviation to convert wafer alignment results measured on combined coordinate system _CA , such as the arrangement coordinates of a plurality of shot regions on the wafer (or the position coordinates of alignment marks on the wafer), into the arrangement coordinates of the plurality of shot regions on the wafer on combined coordinate system _CE . Based on these converted arrangement coordinates, main controller 20 drives (position controls) wafer stage WST1 on combined coordinate system _CE during wafer exposure.

The main control unit 20 performs the above-mentioned calibration method during the exposure process of each wafer (or during the exposure process of every predetermined number of wafers). That is, before performing wafer alignment using the alignment system ALG, as described above, the encoder systems 70 and 71 when using the scale plate 22 are calibrated (the four reference coordinate systems _C1 to _C4 are combined into the combined coordinate system _CA ). The calibrated encoder systems 70 and 71 are used (on the combined coordinate system _CA ) to perform measurement operations such as wafer alignment on the wafer to be exposed. Next, before the exposure process of the wafer, as described above, the encoder systems 70 and 71 when using the scale plate 21 are calibrated (the four reference coordinate systems _C1 to _C4 are combined into the combined coordinate system _CE ). In addition, the deviations in position, rotation, and calibration (relative position, relative rotation, relative calibration) between the combined coordinate systems _CA and _CE are calculated. Use these results to convert the wafer alignment results measured on the combined coordinate system _CA (for example, the arrangement coordinates of multiple irradiation areas on the wafer) into the arrangement coordinates of multiple irradiation areas on the wafer on the combined coordinate system _CE . Based on the converted arrangement coordinates, the wafer stages WST1 and WST2 holding the wafer are driven (position controlled) on the combined coordinate system _CE to perform exposure processing on the wafer.

Furthermore, while the encoder system's measured values can be corrected as a calibration process (calibration method), other processes can also be used. For example, the measurement error can be added as an offset to the wafer stage's current or target position to drive the wafer stage (position control), or other methods can be used to correct the reticle position based solely on the measurement error.

Next, the principle of position measurement in the three degrees of freedom directions (Z, θx, θy) using encoder systems 70 and 71 will be further described. Here, the measurement results or measurement values of encoder heads 60 ₁ to 60 ₄ or encoders ₇₀ 1 to 70 ₄ refer to the measurement results in the Z-axis direction of encoder heads 60 ₁ to 60 ₄ or encoders 70 ₁ to 70 ₄ .

In this embodiment, due to the aforementioned configuration and arrangement of encoder heads 60 ₁ - 60 ₄ and scale plate 21, within the movement area during exposure, at least three of encoder heads 60 ₁ - 60 ₄ face scale plate 21 (or corresponding portions 21 ₁ - 21 ₄ thereof), corresponding to areas A ₀ - A 4 where wafer stage WST1 (WST2) is located. Effective measurement values are transmitted to main controller ₂₀ from the heads (encoders) facing scale plate 21.

Main controller 20 calculates the position (Z, θx, θy) of wafer stage WST1 (WST2) based on the measurement results of encoders 70 ₁ to 70 ₄ (or 71 ₁ to 71 ₄ ). Here, the measurement values of encoders 70 1 to _{70 4} (or 71 ₁ to 71 ₄ ) in the Z-axis direction (not the aforementioned Z-axis direction, that is, to distinguish them from the measurement values C ₁ to C ₄ for a single axis within the XY plane, and recorded as D ₁ to D ₄ , respectively) are dependent on the position (Z, θx, θy) of wafer stage WST1 (WST2) as shown in the following equations (8) to (11).

D ₁ =-ptanθy+ptanθx+Z…(8)

D ₂ =ptanθy+ptanθx+Z…(9)

D ₃ =ptanθy-ptanθx+Z…(10)

D ₄ =-ptanθy-ptanθx+Z...(11)

Here, p is the distance from the center of wafer table WTB1 (WTB2) to the read head in the X-axis and Y-axis directions (see FIG5 ).

Main controller 20 selects three equations based on the measurement values of the heads (encoders) from equations (8) to (11) above, based on the area A ₀ to A ₄ where wafer stage WST1 (WST2) is located, and solves the simultaneous equations consisting of the three selected equations by substituting the measurement values of the three heads (encoders) into the equations to calculate the position (Z, θx, θy) of wafer stage WST1 (WST2). For example, when wafer stage WST1 (or WST2) is located within area A ₁ , main controller 20 combines simultaneous equations based on equations (8), (9), and (11) based on the measurement values of heads 60 ₁ , 60 ₂ , 60 ₄ (encoders 70 ₁ , 70 ₂ , 70 ₄ or 71 ₁ , 71 ₂ , 71 ₄ ), and substitutes the measurement values into the left side of each of equations (8), (9), and (11) to solve them. The calculated positions (Z, θx, θy) are expressed as Z ₁ , θx ₁ , θy ₁ . Similarly, when wafer stage WST1 is within the k-th area _Ak , main controller 20 assembles simultaneous equations based on equations ( _(k-1 )+7), (k+7), and ((k+1)+7) based on the measurement values of heads 60 _{k -1} , 60 k , and 60 _{k+ 1} (encoders 70 k-1 , 70 _k , and 70 k+1 ). The measured values of each head are substituted into the left sides of equations ((k-1)+7), (k+7), and ((k+1)+7) to solve the simultaneous equations. Thus, the positions (Z _k , θx _k , θy _k ) are calculated. Here, the periodically permuted numbers 1 to 4 are substituted into k-1, k, and k+1.

When wafer stage WST1 (or WST2) is located in area 0 _A0 , any three heads ₆₀₁ to ₆₀₄ (encoders ₇₀₁ to ₇₀₄ or ₇₁₁ to ₇₁₄ ) are selected, and simultaneous equations based on the combination of equations of the measurement values of the selected three heads are used.

Main controller 20 performs focus leveling control of wafer stage WST1 (or WST2 ) within the movement area during exposure based on the calculation results (Z, θx, θy) and the focus mapping data.

When wafer stage WST1 (or WST2) is within the measurement movement area, main controller 20 uses encoder system 70 (or 71) to measure the position information of wafer stage WST1 (or WST2) in the three degrees of freedom directions (Z, θx, θy). The measurement principle, etc., is the same as when wafer stage WST1 was previously within the measurement movement area, except that the exposure center is replaced by the detection center of alignment system ALG and scale plate 21 (portions 21 ₁ to 21 ₄ ) is replaced by scale plate 22 (portions 22 ₁ to 22 ₄ ). Main controller 20 performs focus and leveling control on wafer stage WST1 or WST2 based on the measurement results of encoder system 70 or 71. Furthermore, focusing and leveling may not be performed within the measurement movement area (measurement station). Specifically, the mark position and focus mapping data are first acquired. The Z tilt of the wafer stage at the time of acquisition (measurement) is then subtracted from this focus mapping data to obtain the focus mapping data relative to the wafer stage's reference plane, such as the top surface. During exposure, focusing and leveling are performed based on this focus mapping data and the position information of the wafer stage (the reference plane) in the three degrees of freedom (Z, θx, θy).

Furthermore, main controller 20 replaces three of encoder heads 60 ₁ - 60 ₄ facing scale plates 21 and 22 with at least one different set of encoder heads, depending on the positions of wafer stages WST1 and WST2. When the encoder heads are switched, the same connection process as described above is performed to ensure continuity of the position measurement results of wafer stage WST1 (or WST2).

As previously described, scale plates 21 and 22 in exposure apparatus 100 of this embodiment are composed of four sections, 21 ₁ to 21 ₄ and 22 ₁ to 22 ₄ , respectively. Here, any deviation in the height or tilt of these four sections can lead to measurement errors in encoder systems 70 and 71. Therefore, the same correction method as previously described is applied to correct for any deviations in the height or tilt of sections 21 ₁ to 21 ₄ or 22 ₁ to 22 ₄ between the four reference coordinate systems C ₁ to C ₄ .

Here, an example of a calibration method will be described using the case of using the encoder system 70 as an example.

As shown in FIG8(C) or 8(E), main control unit 20 drives wafer stage WST1 in the directions of arrows (X-axis and Y-axis directions) within area A0 based on the measurement results ( _X1 , _Y1 , _θz1 ) of the position of wafer stage WST1 measured by encoder system ₇₀ , and calculates the positions ( _Zk , θxk, _θyk (k=1 to 4)) of the four wafer tables WTB1 using the measurement values of the four head _groups while positioning the wafer stage WTB1 at predetermined intervals. Using these results, main controller 20 calculates the deviation of the position (Z _k , θx _k , θy _k ) calculated from the measurement values of the kth (= 2nd to 4th) head group relative to the position (Z ₁ , θx ₁ , θy ₁ ) calculated from the measurement values of the first head group, or in other words, the offset (O _Zk = Z _k - Z ₁ , O _θxk = θx _k - θx ₁ , O _θyk = θy _k - θy ₁ ). Main controller 20 then averages the offsets (O _Zk , O _θxk , O _θyk ) calculated for each positioning operation.

The calculated offsets ( _Ozk , _Oθxk , _Oθyk ) are used to correct the positions ( _Zk , θxk, _θyk ) calculated from the measurement values of the kth (=2-4) head group to Zk - _Ozk , _{θxk - Oθxk} , and _θyk - _Oθyk , respectively. This correction aligns the height Z and tilt θx and θy of the kth reference coordinate system _Ck (k = 2-4) with those of the first reference coordinate system C1. In other words, _{the four} reference coordinate systems _C1 - _C4 are combined into a single coordinate system (combined coordinate system) _CE that encompasses the exposure movement area _A0 - _A4 .

The main control device 20 also calibrates the four reference coordinates for the encoder system 71 according to the same procedure, and combines them into a coordinate system (combined coordinate system) _CA covering the movement area during alignment measurement.

The main controller 20, as before, performs the above-described calibration method for each wafer exposure process (or for each predetermined number of wafers). Specifically, prior to wafer alignment using the alignment system ALG, as previously described, the encoder system 70 (or 71) is calibrated when using the scale plate 22 (the four reference coordinate systems C ₁ to C ₄ are combined into the combined coordinate system _CA ). The main controller 20 then uses the calibrated encoder system 70 (or 71) (on the combined coordinate system _CA ) to perform wafer alignment on the wafer to be exposed. Next, prior to wafer exposure, the main controller 20 calibrates the encoder system 70 (or 71) when using the scale plate 21 (the four reference coordinate systems C ₁ to C ₄ are combined into the combined coordinate system _CE ) as previously described. The main control unit 20 uses the calibrated encoder system 70 (or 71) (on the combined coordinate system _CE ) to calculate (measure) the position information of the wafer table WTB1 (or WTB2) holding the wafer, and based on the measurement result and the result of the wafer alignment, the wafer table WTB1 (or WTB2) is driven (position controlled) when the wafer is exposed.

As described in detail above, according to the exposure device 100 of this embodiment, the main control device 20 drives (position controls) the wafer stages WST1 and WST2 based on the position information obtained using the first head group within the area _A0 facing the corresponding areas on the scale plates 21 and 22 (parts 21 ₁ to 21 ₄ , 22 ₁ to 22 ₄ ) of the first head group and the second head group to which three heads including one different head belong among the four heads 60 ₁ to 60 ₄ carried on the wafer stages WST1 and WST2, and uses the position information obtained using the first and second head groups to calculate the deviations (deviations in position, rotation, and calibration) between the first and second reference coordinate systems C ₁ and C ₂ corresponding to the first and second head groups, respectively. Main control unit 20 uses this result to correct the measurement result obtained using the second head group, thereby correcting the deviation between the first and second reference coordinate systems _C1 and _C2 , and correcting the measurement error associated with the deviation between the areas on scale plates 21 and 22 facing each of the _four heads ₆₀₁ to 604.

Furthermore, according to exposure apparatus 100 of this embodiment, encoder systems 70 and 71 are calibrated using the calibration method described above to correct for deviations between four reference coordinate systems _C1 to _C4 . Therefore, encoder systems 70 and 71 can be used to measure the position information of wafer stages WST1 and WST2 with high precision and drive them (position control).

Furthermore, according to exposure apparatus 100 of this embodiment, main controller 20 uses reticle alignment systems 13A and 13B and alignment system ALG to detect three fiducial marks provided on wafer stages WST1 and WST2. Based on these fiducial marks, the relative positions, relative rotations, and relative calibrations of combined coordinate systems _CE and _CA , which correspond to the movement regions during exposure and measurement, respectively, are calculated. Main controller 20 uses these results to convert wafer alignment results measured on combined coordinate system _CA , for example, the arrangement coordinates of a plurality of shot regions on the wafer, into the arrangement coordinates of the plurality of shot regions on the wafer on combined coordinate system _CE . Using these results, wafer stages WST1 and WST2 are driven (position controlled) on combined coordinate system _CE to expose the wafers.

Furthermore, in the above embodiment, when wafer stage WST1 is located within area 0 _A0 , all heads 60 ₁ - 60 ₄ on wafer stage WST1 face scale plate 21 (corresponding portions 21 ₁ - 21 ₄ ). Therefore, within area 0 _A0 , valid measurement values are transmitted to main controller 20 from all heads 60 ₁ - 60 ₄ (encoders 70 ₁ - 70 ₄ ). Therefore, main controller 20 can also drive (position control) wafer stages _WST1 and _WST2 based on position information obtained by at least one of the k-th head group (k=1-4), for example, at least one of the first position information obtained by the first head group and the second position information obtained by the second head group, within area _A0 facing the corresponding area (portions 21 ₁ to 21 ₄ ) on scale plate 21, within the k-th head group (k=1-4) to which three heads, including one different head, belong among four heads 60 1 to 60 4 . In this case, even if the coordinate systems (portions of scale plate 21 ) corresponding to the first and second head groups differ, wafer stages WST1 and WST2 can be driven with high precision without being affected. The same applies when scale plate 22 is used.

Furthermore, in the above-mentioned embodiment, the correction process for the deviations between the four reference coordinate systems C ₁ to C ₄ caused by the deviations between the parts 21 ₁ to 21 ₄ and 22 ₁ to 22 ₄ constituting the scale plates 21 and 22 does not need to focus on all of position, rotation, and calibration. It may be one or any two of them, and other factors (such as orthogonality) may be added or substituted.

Furthermore, in the above embodiment, at least one auxiliary read head can be positioned near each of the four read heads on the wafer stage. If a measurement anomaly occurs with the primary read head, the measurement can be continued by switching to the adjacent auxiliary read head. In this case, the aforementioned placement conditions also apply to the auxiliary read heads.

Furthermore, although the above embodiment illustrates a case where a two-dimensional diffraction grating RG is formed on the bottom surface of each of the parts 21 ₁ to 21 ₄ and 22 ₁ to 22 ₄ of the scale plates 21 and 22, the present invention is not limited to this. The above embodiment is also applicable to a case where a one-dimensional diffraction grating is formed with only the measurement direction (one-axis direction in the XY plane) of the corresponding encoder read heads 60 ₁ to 60 ₄ as a periodic direction.

Furthermore, in the above-described embodiment, although the position information obtained by the first head group is used to drive (position control) wafer stages WST1 and WST2 within the area A0 facing the corresponding areas (parts _{21 1 to} 21 4 and 22 ₁ to 22 ₄ ) on scale plates 21 and 22, to which the first head group and the second head group of three heads including one different head among the four heads _{60 1} to 60 ₄ mounted on wafer stages _WST1 and WST2 belong, the position information obtained by the first head group is used to calculate the deviation (deviation in position, rotation, and calibration) between the first and second reference coordinate systems C ₁ and C ₂ corresponding to the first and second head groups, respectively, and the measurement result obtained by the second head group is corrected using the result, thereby correcting the measurement result of the four heads 60 ₁ to 60 4. While the above description has been given of a case where measurement errors are caused by deviations between the areas on the scale plates ₂₁ and 22 facing each other, the present invention is not limited thereto. For example, a plurality (a second number) of reading heads, which is greater than the plurality (a first number) of reading heads used for position control of the wafer stage, may be used to move the wafer stage within an area where position measurement can be performed separately, thereby obtaining correction information for the stage position information obtained by the encoder system. In other words, the stage may be moved within the cross area A0 _in the above-described embodiment, for example, and correction information may be obtained using redundant reading heads.

In this case, the correction information is used by the main control device 20 to correct the encoder measurement value, but the present invention is not limited thereto and can also be used in other processing.

For example, other methods may be used to add the measurement error as an offset to the current position or target position of the wafer stage to drive the wafer stage (position control), or to correct the reticle position by only the measurement error.

Furthermore, in the above-mentioned embodiment, although the position information obtained by the first and second head groups is used to calculate the deviations (deviations in position, rotation, and calibration) between the first and second reference coordinate systems _C1 and _C2 corresponding to the first and second head groups, respectively, the exposure device is not limited to this. The exposure device may also include, for example, a position measurement system (such as an encoder system) that irradiates a measurement beam on a measurement surface composed of a plurality of scale plates arranged on the outside of the wafer stage near the exposure position of the wafer and substantially parallel to the XY plane according to a plurality of heads provided on the wafer stage, and receives the output of a return beam from the measurement surface to calculate the position information of the wafer stage; and a control system that drives the wafer stage according to the position information obtained by the position measurement system and switches the head used by the position measurement system to obtain the position information from the plurality of heads according to the position of the wafer stage, the control system obtaining the positional relationship between the plurality of scale plates corresponding to the plurality of heads within the first moving area of the movable body facing the plurality of heads and the measurement surface. In this case, the plurality of head groups to which the plurality of heads including at least one mutually different head belong can be made to face the plurality of scale plates.

In this case, the positional relationship between the multiple scale plates can be used not only to correct the encoder measurement value, but also for other processing. For example, the measurement error can be used as an offset to the current or target position of the wafer stage to drive the wafer stage (position control), or other methods can be used to correct the reticle position based solely on the measurement error.

Furthermore, while the above embodiment illustrates the case where each of the read heads 60 ₁ - 60 ₄ (encoders 70 ₁ - 70 ₄ ) employs a two-dimensional encoder with a single axis in the XY plane and a Z axis as the measurement direction, the present invention is not limited thereto. Alternatively, a one-dimensional encoder with a single axis in the XY plane and a one-dimensional encoder with a Z axis as the measurement direction (or a non-encoder type surface position sensor, etc.) may be employed. Alternatively, a two-dimensional encoder with two orthogonal axial directions in the XY plane as the measurement direction may be employed. Furthermore, a three-dimensional encoder (3DOF sensor) with three measurement directions: the X, Y, and Z axes may be employed.

Furthermore, although the above embodiment is described with respect to the case where the exposure device is a scanning stepper, it is not limited thereto and can also be applied to a stationary exposure device such as a stepper. Even for a stepper, by measuring the position of the carrier carrying the exposure object with an encoder, unlike the case where the carrier position is measured using an interferometer, the position measurement error caused by air fluctuations can be reduced to almost zero, and the carrier can be positioned with high precision based on the measurement value of the encoder. As a result, the reticle pattern can be transferred to the wafer with high precision. In addition, the above embodiment can also be applied to a projection exposure device of a step & stitch method in which the exposure area and the exposure area are synthesized. Furthermore, the above embodiment can also be applied to a multi-stage exposure device having a plurality of wafer stages, such as disclosed in U.S. Patent No. 6,590,634, U.S. Patent No. 5,969,441, and U.S. Patent No. 6,208,407. In addition, the above embodiments can also be applied to exposure devices disclosed in, for example, U.S. Patent Application Publication No. 2007/0211235 and U.S. Patent Application Publication No. 2007/0127006, which have a measurement stage different from the wafer stage and include measurement components (such as reference marks and/or sensors, etc.).

Furthermore, the exposure apparatus of the above-mentioned embodiment may also be a liquid immersion exposure apparatus disclosed in, for example, International Publication No. 99/49504 and US Patent Application Publication No. 2005/0259234.

Furthermore, the projection optical system in the exposure device of the above embodiment is not limited to the reduction system but can be either an equal-magnification system or an enlargement system. The projection optical system PL is not limited to the refraction system but can be either a reflection system or a catadioptric system. The projected image can be either an inverted image or an upright image.

Furthermore, the illumination light IL is not limited to ArF excimer laser light (wavelength 193 nm) but may also be ultraviolet light such as KrF excimer laser light (wavelength 248 nm) or vacuum ultraviolet light such as _F laser light (wavelength 157 nm). Alternatively, a fiber amplifier doped with erbium (or both erbium and ytterbium) as disclosed in U.S. Patent No. 7,023,610 may be used to amplify single-wavelength laser light in the infrared or visible region emitted from a DFB semiconductor laser or fiber laser to produce vacuum ultraviolet light, and then convert the wavelength of the light into harmonics of the ultraviolet light using a nonlinear optical crystal.

Furthermore, while the above-described embodiments utilize a light-transmitting mask (reticle) having a predetermined light-shielding pattern (or phase pattern, or dimming pattern) formed on a light-transmitting substrate, this reticle may be replaced with an electronic mask (including a DMD (Digital Micro-mirror Device), also known as a deformable mask, active mask, or image generator, such as a non-luminous image display element (spatial light modulator)) that forms a transmissive pattern, a reflective pattern, or a luminous pattern based on electronic data of the pattern to be exposed, as disclosed in U.S. Patent No. 6,778,257. When using this deformable mask, the stage carrying the wafer or glass plate is scanned relative to the deformable mask, and the position of the stage is measured using an encoder system and a laser interferometer system, thereby achieving the same effects as those of the above-described embodiments.

Furthermore, the above-described embodiment can also be applied to an exposure apparatus (photolithography system) for forming a line and space pattern on a wafer W by forming interference fringes on the wafer W, as disclosed in, for example, International Publication No. 2001/035168.

Furthermore, the above embodiment can also be applied to an exposure device disclosed in, for example, US Pat. No. 6,611,316, which combines two reticle patterns on a wafer through a projection optical system and substantially simultaneously double-exposes an exposure area on the wafer through a single scanning exposure.

Furthermore, in the above embodiments, the object on which a pattern is to be formed (the object to be exposed to the energy beam) is not limited to a wafer, but may be other objects such as a glass plate, a ceramic substrate, a thin film member, or a mask motherboard.

The use of the exposure device is not limited to exposure devices used in semiconductor manufacturing. It can also be widely applied to, for example, liquid crystal exposure devices that transfer liquid crystal display device patterns onto square glass plates, and exposure devices used to manufacture organic ELs, thin-film magnetic heads, imaging devices (such as CCDs), micromachines, and DNA chips. Furthermore, the present invention is applicable not only to micro components such as semiconductor devices, but also to exposure devices that transfer circuit patterns onto glass substrates or silicon wafers, such as reticles or masks used in the manufacture of optical exposure devices, EUV exposure devices, X-ray exposure devices, and electron beam exposure devices.

In addition, the disclosures of all publications, international publications, U.S. patent application publications, and U.S. patent specifications regarding exposure apparatuses, etc. cited in the above description are incorporated herein by reference as part of the description of this specification.

Electronic components such as semiconductor devices are manufactured through steps such as designing the device's functions and performance, fabricating a reticle based on this design, fabricating a wafer from silicon material, transferring the mask (reticle) pattern to the wafer using the exposure apparatus (patterning apparatus) and exposure method of the aforementioned embodiments, developing the exposed wafer (object), etching to remove exposed components other than those containing residual photoresist, removing photoresist after etching, assembling the device (including dicing, bonding, and packaging), and inspecting. In this case, using the exposure apparatus and exposure method of the aforementioned embodiments in the lithography process enables the manufacture of highly integrated devices with good productivity.

As described above, the exposure device (pattern forming device) of the above embodiment is assembled and manufactured by assembling various subsystems including the various components listed in the scope of the patent application of this case in a manner that can maintain the predetermined mechanical precision, electrical precision, and optical precision. In order to ensure the above-mentioned various precisions, before and after this assembly, the various optical systems are adjusted to achieve optical precision, the various mechanical systems are adjusted to achieve mechanical precision, and the various electrical systems are adjusted to achieve various electrical precisions. The steps of assembling the various subsystems to the exposure device include mechanical connections between the various subsystems, connections of electrical circuits, connections of pneumatic circuits, etc. Before the steps of assembling the various subsystems to the exposure device, there are of course steps of assembling the various subsystems. After the steps of assembling the various subsystems to the exposure device are completed, comprehensive adjustments are performed to ensure the various precisions of the entire exposure device. In addition, the manufacture of the exposure device is preferably carried out in a clean room where temperature and cleanliness are managed.

Industrial applicability

As described above, the exposure method and exposure apparatus of the present invention are suitable for exposing an object. Furthermore, 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 (26)

1. An exposure apparatus for exposing a substrate to illumination light using a projection optical system, comprising: An illumination optical system that illuminates a mask with the illumination light; The first stage is positioned above the projection optical system to hold the mask. The first drive system drives the first platform; The first encoder system measures the position information of the first stage; The base is positioned below the projection optical system; The second stage has a holding device for holding the substrate and is disposed on the base; The second drive system has a planar motor of magnetic levitation mode, which suspends and supports the second stage on the base, and drives the second stage to move the substrate in 6 degrees of freedom directions, including a first direction and a second direction orthogonal to each other in a predetermined plane that is perpendicular to the optical axis of the projection optical system. The second encoder system has four read heads disposed on the second stage. These four read heads illuminate a scale member having four portions forming a reflective two-dimensional grating from below, respectively, to measure the position information of the second stage in the six degrees of freedom directions at an exposure station that exposes the substrate via the projection optical system; and The control system controls the first drive system based on the measurement information of the first encoder system and the second drive system based on the measurement information of the second encoder system in order to move the mask and the substrate relative to the illumination light during the scanning exposure of the substrate. The scale component is configured in the exposure station such that the four parts are substantially parallel to the predetermined surface at the lower end of the projection optical system. The control system moves the second stage in the exposure station within a moving area comprising four coordinate systems, each containing a set of three read heads that measure position information by removing the different read heads one by one from the four read heads. Based on the position information measured by one set of three read heads in one of the four coordinate systems within the moving area, the control system controls the second drive system. Furthermore, based on the measurement information of the second encoder system located in a portion of the moving area where the four read heads are respectively opposite to the four portions, the control system obtains correction information to compensate for measurement errors in the second encoder system caused by deviations in the four portions. This correction information is used for the drive control of the second platform in the moving area. 2. The exposure apparatus as claimed in claim 1, wherein the second encoder system uses four sets of three read heads to measure the position information of the second stage in the four coordinate systems respectively. 3. The exposure apparatus of claim 2, wherein the second encoder system, instead of one of the three read heads used in one of the four coordinate systems, measures the position information of the second stage in a coordinate system different from the first coordinate system by means of three read heads including another read head among the four read heads that is different from the three read heads used in the first coordinate system. 4. The exposure apparatus of claim 3, wherein, in order to perform drive control for moving the second stage from the one coordinate system to the different coordinate system, the one read head is switched to the other read head, and based on the position information measured by the three read heads used in the one coordinate system, the other read head is used instead of the one read head to obtain switching information for controlling the drive of the second stage. 5. The exposure apparatus of claim 4, wherein the switching information is obtained during the period when the second stage is located in a portion of the moving area. 6. The exposure apparatus according to any one of claims 1-5, wherein the second encoder system has an auxiliary reader configured close to the reader head, and is capable of switching the reader head to the auxiliary reader head to continue performing the measurement. 7. The exposure apparatus according to any one of claims 1-5, wherein each of the four read heads is capable of measuring the position information of the second stage in one of the first direction and the second direction, and the third direction orthogonal to the predetermined plane. 8. The exposure apparatus according to any one of claims 1-5, further comprising: a body structure having a measuring frame supporting the projection optical system; The scale component is suspended and supported on the measuring frame. 9. The exposure apparatus of claim 8, further comprising: The inspection system, supported on the measuring frame in a measuring station different from the exposure station, detects the position information of the substrate; and Another scale component, different from the scale component, has four different parts that form reflective two-dimensional gratings. In the measuring station where the substrate is inspected by the detection system, the four different parts are supported on the measuring frame in a manner that is parallel to the predetermined surface on the lower side of the detection system. The second encoder system measures the position information of the second stage positioned below the scale member during the exposure step of the substrate, and measures the position information of the second stage positioned below the other scale member during the inspection step of the substrate by means of the inspection system. 10. The exposure apparatus of claim 9, wherein the control system obtains correction information, which is different from the correction information, to compensate for measurement errors of the second encoder system caused by deviations of the different four parts, based on position information of the second stage below the detection system, which is arranged such that the four read heads are respectively opposite to the four different parts, as measured by the second encoder system. 11. The exposure apparatus of claim 10, wherein the control system uses, in the exposure step, the position information of the substrate detected by the detection system, the position information of the second stage measured by the second encoder system in the detection step, and the different correction information. 12. The exposure apparatus of claim 11, further comprising: a second stage disposed on the base and different from the second stage; The different second stage is equipped with four different reading heads than the four reading heads. The position information of the different second stage in the six degrees of freedom direction is measured by at least three of the four different reading heads. 13. A method for manufacturing a component, comprising: The step of exposing a substrate using the exposure apparatus according to any one of claims 1-12; and The step of developing the exposed substrate. 14. An exposure method for exposing a substrate to illumination light using a projection optical system, comprising: The step of measuring the position information of a first stage that is positioned above the projection optical system and maintains illumination by illumination light through the illumination optical system using a first encoder system; The step of moving the second stage by means of a planar motor of the moving magnet or moving coil type, which suspends a second stage having a holding device for holding the substrate on a base disposed below the projection optical system, in a manner that moves the substrate in a 6-degree-of-freedom direction including a first direction and a second direction orthogonal to each other in a predetermined plane perpendicular to the optical axis of the projection optical system. The step of measuring the position information of the second stage in the six degrees of freedom directions at an exposure station that exposes the substrate through the projection optical system, using a second encoder system having a second stage and four read heads that respectively illuminate the measurement beam from below with scale members that form four parts of a reflective two-dimensional grating; and In the scanning exposure of the substrate, the steps of driving the first stage according to the measurement information of the first encoder system and driving the second stage according to the measurement information of the second encoder system are as follows: in order to move the mask and the substrate respectively relative to the illumination light. The scale component is configured in the exposure station such that the four parts are substantially parallel to the predetermined surface at the lower end of the projection optical system. In the exposure station, within a moving area comprising four coordinate systems, which are defined by four groups of three-readers that measure position information by removing the different readers from the four readers one by one, the second stage is moved according to the position information measured by one of the three-readers in one of the four coordinate systems in which the second stage is located. Based on the measurement information of the second encoder system located in a part of the moving area where the four readers are respectively opposite to the four parts, correction information is obtained to compensate for the measurement error of the second encoder system caused by the deviation of the four parts. This correction information is used for the drive control of the second platform in the moving area. 15. The exposure method as described in claim 14, wherein the position information of the second stage is measured using four sets of three read heads in the four coordinate systems respectively. 16. The exposure method of claim 15, wherein, instead of one of the three read heads used in one of the four coordinate systems, the position information of the second stage in a coordinate system different from the first coordinate system is measured by three read heads including another read head that is different from the three read heads used in the first coordinate system. 17. The exposure method of claim 16, wherein, in order to perform drive control for moving the second stage from the one coordinate system to the different coordinate system, the one read head is switched to the other read head, and based on the position information measured by the three read heads used in the one coordinate system, the other read head is used instead of the one read head to obtain switching information for controlling the drive of the second stage. 18. The exposure method of claim 17, wherein the switching information is obtained during the period when the second stage is located in a portion of the moving area. 19. The exposure method according to any one of claims 14-18, wherein the read head is switched to an auxiliary read head configured close to the read head while the measurement continues. 20. The exposure method according to any one of claims 14-18, wherein each of the four read heads measures the position information of the second stage in one of the first direction and the second direction, and the third direction orthogonal to the predetermined surface. 21. The exposure method according to any one of claims 14-18, wherein the scale member is suspended and supported on a measuring frame of a body structure supporting the projection optical system. 22. The exposure method of claim 21, wherein the position information of the substrate is detected in a measurement station different from the exposure station by a detection system supported on the measurement frame; For another scale component that is different from the scale component, the measuring beam is irradiated from below by the four reading heads. The other scale component has four parts that are different from the four parts and form reflective two-dimensional gratings respectively. In the measuring station where the substrate is inspected by the detection system, the four different parts are supported on the measuring frame in a manner that is parallel to the predetermined surface on the lower side of the detection system. The second encoder system measures the position information of the second stage positioned below the scale member during the exposure step of the substrate, and measures the position information of the second stage positioned below the other scale member during the inspection step of the substrate by means of the inspection system. 23. The exposure method of claim 22, wherein, based on the position information of the second stage, which is configured below the detection system in a manner that is relative to the four read heads respectively with respect to the four different parts, as measured by the second encoder system, correction information different from the correction information is obtained to compensate for the measurement error of the second encoder system caused by the deviation of the four different parts. 24. The exposure method of claim 23, wherein, in the exposure step, the position information of the substrate detected by the detection system, the position information of the second stage measured by the second encoder system in the detection step, and the different correction information are used. 25. The exposure method of claim 24, wherein the substrate is held by a second stage disposed on the base and different from the second stage; The position information of the different second stages in the 6-degree-of-freedom direction is measured by at least three of the four read heads located on the different second stages and different from the four read heads. 26. A method for manufacturing a component, comprising: The step of exposing a substrate using the exposure method according to any one of claims 14-25; and The step of developing the exposed substrate.