JP3209186B2 - Exposure apparatus and method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection exposure apparatus for exposing a photosensitive layer applied to a substrate such as a semiconductor wafer or a glass plate for a liquid crystal, and more particularly, to precisely control a baseline of an off-axis type alignment system. The present invention relates to a projection exposure apparatus having a function of performing

[0002]

2. Description of the Related Art Conventionally, a projection exposure apparatus having an off-axis alignment system (hereinafter referred to as a stepper for convenience) has been disclosed in Japanese Patent Application Laid-Open Nos. 53-56975 and 56-56975.
As disclosed in JP-A-134737, etc., a reference mark plate is fixed on a wafer stage that holds a photosensitive substrate (hereinafter, referred to as a wafer) and moves two-dimensionally by a step-and-repeat method, The reference mark plate is used to manage the distance between the off-axis alignment system and the projection optical system, that is, the so-called baseline amount. FIG. 1 is a diagram schematically illustrating the principle of baseline measurement disclosed in the above publications. In FIG. 1, a main condenser lens ICL illuminates a reticle (mask) R uniformly during exposure. Reticle R is reticle stage RS
The reticle stage RST is held at T and moved such that the center CC of the reticle R coincides with the optical axis AX of the projection lens PL. On the other hand, on wafer stage WST, a reference mark FM equivalent to an alignment mark formed on the wafer surface is provided, and stage W is moved so that reference mark FM comes to a predetermined position in the projection field of view of projection lens PL.
When the ST is positioned, a TTL (through-the-lens) type alignment system DDA provided above the reticle R
Thereby, the mark RM of the reticle R and the reference mark FM are simultaneously detected. Mark RM and center C of reticle R
The distance La to C is a value predetermined in design, and the distance between the projection point of the mark RM and the projection point of the center CC on the image plane side (wafer side) of the projection lens PL is La / M.
Here, M is the magnification of the projection lens PL when the reticle side is viewed from the wafer side, and M = 5 in the case of a 1/5 reduction projection lens.

[0003] Outside the projection lens PL (outside the projection field of view)
Has an off-axis wafer alignment system O
The WA is fixed. Wafer alignment system OWA
Is parallel to the optical axis AX of the projection lens PL on the projection image plane side. In the wafer alignment system OWA, a mark on the wafer or an index mark TM serving as a reference when aligning the reference mark FM is provided on the glass plate, and a projected image plane (wafer surface or reference mark FM) is provided. Plane) is arranged substantially conjugate with the plane.

As shown in FIG. 1, the base line amount BL is such that the position X1 of the stage WST when the reticle mark RM and the reference mark FM are aligned, and the index mark TM and the reference mark FM are aligned. The position X2 of the stage WST at that time is measured by a laser interferometer or the like, and the difference (X1−X2) is calculated. This baseline amount BL is used as a reference amount when the mark on the wafer is later aligned by the wafer alignment system OWA and is sent immediately below the projection lens PL. That is, one shot on the wafer (exposed area)
XP between the center of the mark and the mark on the wafer, and the wafer stage W when the wafer mark matches the index mark TM.
Assuming that the position of ST is X3, the wafer center WST may be moved to the position of the following equation in order to match the shot center with the reticle center CC.

X3-BL-XP or X3-BL + XP Note that this formula only represents the one-dimensional direction in principle, and it is actually necessary to consider it in two dimensions.
The calculation method differs depending on the arrangement of the TL alignment system DDA (that is, the mark RM), the arrangement of the wafer alignment system OWA, and the like.

In any case, after the mark position on the wafer is detected using the off-axis type wafer alignment system OWA, the wafer stage WST is fed by a fixed amount, and the pattern of the reticle R is immediately transferred onto the wafer. Exposure can be performed so as to be accurately superimposed on the shot area.

[0007]

In the prior art as described above, the detection center of the off-axis type alignment system OWA (the center of the index mark TM) and the projection point of the mark RM of the reticle R by the projection lens PL are used. When measuring the positional relationship (baseline amount BL) with the laser interferometer, the relative distance is obtained by moving the wafer stage WST. For this reason, there is a natural limitation in improving the accuracy of the baseline measurement due to inevitable factors such as the running accuracy of the wafer stage WST and air fluctuation in the laser beam optical path of the laser interferometer. In addition, movement of wafer stage WST for positioning reference mark FM in the detection area of TTL alignment system DDA, and off-axis alignment system OWA of reference mark FM.
Stage WS for positioning at the detection center point
It is necessary to move T, and there is naturally a limit in increasing the speed of the baseline measurement processing.

SUMMARY OF THE INVENTION The present invention has been made in view of such conventional problems, and has as its object to provide a projection exposure apparatus capable of improving baseline measurement accuracy and processing speed.

[0009]

According to the present invention, a first reference mark (FM) detectable by an off-axis alignment system (OWA) is provided on a stage for holding a photosensitive substrate.
1) and a second reference mark (FM2) detectable by an alignment system via a projection optical system were juxtaposed in a predetermined positional relationship in design. The alignment system via the projection optical system detects the positional deviation between the marks (RM1, RM2) on the reticle (mask) and the second reference mark (FM2) on the stage, and simultaneously detects off-position.
An axis alignment system (OWA) detects a displacement of the first reference mark (FM1) on the stage from the detection center. Further, a projection optical system for the mark on the reticle is determined based on a design interval (including a manufacturing error) between the first fiducial mark (FM1) and the second fiducial mark (FM2) and the detected amount of misalignment. , And the relative distance between the detection center point of the off-axis alignment system OWA, that is, the base line is calculated.

In the present invention, since each reference mark on the reference plate is detected by simultaneously using the alignment system via the projection optics and the off-axis alignment system, it is not affected by the running accuracy and positioning accuracy of the stage. In addition, extremely accurate baseline measurements can be made. Since the base line amount is not measured by moving the wafer stage and moving the wafer stage as in the related art, there is an advantage that the wafer stage does not depend on the measurement value of the laser interferometer for measuring the stage position.

Further, according to the present invention, the position of a reticle (mask), the amount of misregistration detection, or the reticle alignment is detected with reference to each mark of a reference plate provided on a stage, and the base is set with reference to the reference plate. Since line measurement is performed, all standards are unified,
An advantage that a series of processing is completed in a short time, that is, both effects of high accuracy and high throughput can be obtained.

[0012]

FIG. 2 is a perspective view showing the structure of a projection exposure apparatus according to an embodiment of the present invention. The same members as those in the conventional apparatus shown in FIG. 1 are denoted by the same reference numerals. In FIG.
On the reticle R, there are provided a pattern area PA in which a circuit pattern to be exposed on the wafer W and the like, and reticle marks RM1 and RM2 for alignment. The reticle marks RM1 and RM2 are photoelectrically detected via objective lenses 1A and 1B of an alignment system via a projection optical system, respectively. Reticle stage RST
Can be moved two-dimensionally (X, Y, θ directions) by a driving system such as a motor not shown in FIG.
Or the movement position is determined by three laser interferometers IRX, IRY, I
It is successively measured by Rθ. Reticle stage RST
The amount of rotation about the Z-axis (coordinate axis parallel to the optical axis AX) is determined by the difference between the measured values of the interferometers IRY and IRθ, and the amount of translation in the Y-axis direction is the average of the measured values of the interferometers IRY and IRθ. The amount of parallel movement in the X-axis direction is obtained by the interferometer IRX.

In this embodiment, a second alignment system via a projection optical system for detecting a mark on the wafer W via only the projection lens PL is separated for the X direction and the Y direction. Is provided. The alignment system via the second projection optical system for the X direction includes a mirror 2X fixed between the reticle stage RST and the projection lens PL, the objective lens 3X, and the like. The second alignment system for the Y direction is , A mirror 2Y and an objective lens 3Y arranged in the same manner.
Etc. In this embodiment, the objective lenses 1A, 1B
Is hereinafter referred to as a TTR (through the reticle) alignment system, and the objective lens 3X, 3
The second alignment system including Y is simply called a TTL alignment system.

On two sides of the wafer stage WST on which the wafer W is mounted, a moving mirror IMx for reflecting a beam from the laser interferometer IFX, a laser interferometer IFY1,
The movable mirror IMy that reflects the beam from each of the IFYs 2 is fixed. The beam from the interferometer IFX is perpendicular to the reflecting surface of the moving mirror IMx extending in the Y direction, and the extension of the beam is orthogonal to the extension of the optical axis AX of the projection lens PL. The beam from the interferometer IFY2 is perpendicular to the reflecting surface of the moving mirror IMy extending in the X direction, and the extension of the beam is also orthogonal to the extension of the optical axis AX. Another interferometer I
The beam from FY1 is perpendicular to the reflecting surface of the moving mirror IMy, and is parallel to the beam of the interferometer IFY2.

The off-axis type wafer alignment system includes a reflecting prism (or mirror) 4A and an objective lens 4B, which are fixed immediately near the lower end of the projection lens PL. The light receiving system 4C of the wafer alignment system includes a conjugate index mark TM inside, and picks up an image of a mark or the like on the wafer formed on the index mark plate via the prism 4A and the objective lens 4B with a CCD camera.

In this embodiment, the optical axis of the objective lens 4B which falls on the wafer stage WST via the prism 4A,
The optical axis AX of the projection lens PL is set so as to be apart from the optical axis AX only by a certain distance only in the X direction, and there is almost no positional coordinate difference in the Y direction. Further, the extension of the optical axis of the objective lens 4B that falls on the wafer stage WST is orthogonal to each of the extension of the beam of the interferometer IFX and the extension of the beam of the interferometer IFY1. The arrangement of such an interferometer is disclosed in detail in JP-A-1-309324.

On the wafer stage WST, a reference plate FP provided with two reference marks FM1 and FM2 for baseline measurement is fixed. The reference plate FP is disposed at a corner surrounded by the two movable mirrors IMx and IMy on the wafer stage WST, and forms a light-shielding layer such as chromium on the surface of a low expansion coefficient transparent material such as a quartz plate. A part is etched in the shape of the reference marks FM1 and FM2. The reference mark FM1 is an off-axis type wafer.
It can be detected by the alignment system (4A, 4B, 4C), and the reference mark FM2 can be detected by the TTR alignment system (1A,
1B) or TTL alignment system (2X, 3X; 2
Y, 3Y). The distance between the reference marks FM1 and FM2 in the X direction is accurately formed with submicron accuracy.

FIG. 3 is a plan view showing the arrangement of each member on wafer stage WST.
The wafer is placed on a wafer holder WH that can be slightly rotated on T, and is vacuum-sucked. In this embodiment, the wafer W is placed on the wafer holder WH after being mechanically pre-aligned so that the linear cutout OF of the wafer W is parallel to the X axis. As shown in FIG. 3, the center (optical axis AX) of the diameter of the lower end of the lens barrel of the projection lens PL and the field of view of the objective lens 4B are arranged as close as possible. Thus, when the projection lens PL and the reference plate FP are arranged, the wafer W
Since the wafer W has been moved most diagonally downward and to the right in the drawing from the position immediately below L, loading and unloading of the wafer W can be performed in this state. This arrangement is described in, for example,
No. 224326.

FIG. 4 shows a reference mark FM on a reference plate FP.
1 is a plan view showing a detailed mark arrangement of FM2. In FIG. 4, the intersection of a straight line LX parallel to the X axis and a straight line LY2 parallel to the Y axis is the center of the reference mark FM2, and the intersection substantially coincides with the optical axis AX of the projection lens PL at the time of baseline measurement. . In this embodiment, a light-emitting cross-shaped slit mark IFS is arranged on the intersection, and illumination light having the same wavelength as the exposure light illuminates only the local area ISa including the light-emitting slit mark IFS from the back side of the reference plate FP. Further, reference marks FM2A and FM2B corresponding to the respective arrangements of the reticle marks RM1 and RM2 are provided at two contrasting places on both sides of the light emitting slit mark IFS on the straight line LX. The marks FM2A and FM2B are
The mark FM2A is aligned with the reticle mark RM1, and the mark FM2B is aligned with the reticle mark RM2.

Center (intersection) of the emission slit mark IFS
Is the projection field of view of the projection lens PL. In the case of this embodiment, the mark LIMx detectable by the TTL alignment system (2X, 3X) for the X direction shown in FIG. A TTL alignment system (2Y,
3Y), two marks LIMy and LS detectable by
My is arranged on the straight line LX of the visual field region PIF. The detailed arrangement relationship of each mark will be described later, but in the present embodiment, two TTR alignment systems 1A, 1A,
B is simultaneously detecting the reticle marks RM1, RM2 and the reference marks FM2A, FM2B, respectively.
Each mark FM2A, FM2B, LIMx such that the TTL alignment system (2X, 3X) for the X direction can detect the mark LIMx and the TTL alignment system (2Y, 3Y) for the Y direction can detect the mark LIMy. , L
IMy was placed.

On the other hand, a straight line LY1 set at a predetermined distance in the X direction from the straight line LY2 is parallel to the Y axis, and an intersection of the straight line LY1 and the straight line LY is provided with an objective lens of an off-axis alignment system. A reference mark FM1 having a size that can be included in the 4B field of view MIF is formed. The mark FM1 has an X so that two-dimensional alignment is possible.
It is an aggregate of a plurality of line patterns provided in parallel to the direction and the Y direction. As is apparent from the above description, the reference plate FP is such that the straight line LY1 coincides with the center line of the beam of the interferometer IFY1 within the XY plane as much as possible, and the straight line LY
2 is fixed on wafer stage WST so as to coincide as much as possible with the center line of the beam of interferometer IFY2.

Further, two reference marks FM are located at symmetric positions on the straight line LX with respect to the intersection of the straight lines LX and LY1.
2C and FM2D are provided. Fiducial mark FM2
C and FM2D are cross-shaped slit patterns of exactly the same shape and size as the reference marks FM2A and FM2B, and the interval in the X direction is exactly the same as the interval between the marks FM2A and FM2B. The mark LSMx in FIG. 4 is detected by the TTL alignment system (2X, 3X) for the X direction, and is provided at the same position as the X coordinate value of the reference mark FM2B.

FIG. 5 shows a reference mark FM2 on the reference plate FP.
Only the arrangement of each mark on the side is enlarged, and the projection lens P
The center of the projection field area PIF of L is the emission slit mark I
The state where it matched with the intersection of FS is shown. FIG. 5 further shows the positional relationship between the outer shape of the reticle R and the outer shape of the pattern area PA, which are ideally positioned in this state, by a two-dot chain line.

Mark LIM for TTL alignment system
x and LIMy are located at the outermost periphery of the projection visual field PIF,
This is the mirror 2X, 2Y at the tip of the TTL alignment system.
Is arranged so that the projection area of the pattern area PA is not shielded from light. In this state, the reference mark FM2A can be aligned with the reticle mark RM1, but the reticle mark RM1 (also RM2) extends in the Y direction with the double slit mark RM1y extending in the X direction, as shown in FIG. A double slit mark RM1x is formed, and these marks RM1y and RM1x are formed as dark portions in a transparent window portion surrounded by a rectangular light shielding band SB.

Of the cross-shaped slits of the reference mark FM2A, the slit extending in the X direction is a double slit mark R
The ideal alignment has been achieved by the slit that is sandwiched between M1y and extends in the Y direction is sandwiched between the double slit marks RM1x. Here, the distance K1 between the center of the reference mark FM2A and the center of the mark LIMy in the X direction and the distance K2 between the center of the light emitting slit mark IFS and the center of the mark LSMy in the X direction are the light emitting slits shown in FIG. Mark IFS is reticle mark RM
X-direction offset amount ΔXk when scanning 1 in the Y-direction
(Wafer side conversion value). That is, K1 = K2 + ΔXk or K1 = K
2-ΔXk.

Further, the center position in the X direction of the mark LSMx detectable by the TTL alignment system for the X direction coincides with the center position in the X direction of the reference mark FM2B. This is the distance K in the X direction between the center point of each of the two reference marks FM2A and FM2B and the center of the light emitting slit mark IFS.
3 is a condition that holds when both are equal. The position of the mark LSMx in the Y direction is substantially equal to the position of the mark LIMx in the Y direction.
Is the distance in the Y direction between the center of the mark LIMx and the center of the mark LIMx.
4. When the interval in the Y direction between the center of the light emitting mark IFS and the center of the mark LSMx is K5, K4 = K5 + ΔY
k or K4 = K5−ΔYk. Here, ΔYk is the light emission slit mark IF as shown in FIG.
S is the double slit mark RM of reticle mark RM1
This is the offset amount in the Y direction when 1x is scanned in the X direction.

Next, the detailed configuration of the TTR alignment system (1A) will be described with reference to FIG. Reticle mark R
Above M1, a total reflection mirror 100 is inclined at 45 ° to make the optical axis of the horizontally arranged objective lens 101 perpendicular to the reticle R. This TTR alignment system uses a beam splitter 102, a light source 103 that generates light of an exposure wavelength, a shutter 104 that switches between blocking and passing of illumination light, an optical fiber 105 that guides illumination light, and an emission end of the optical fiber 105 for coaxial epi-illumination. And a lens system 109 for transmitting illumination light from the field stop 107 to the objective lens 101 under Koehler illumination conditions. It has a self-illuminating system. Thus, the objective lens 101 illuminates only the inside of the light-shielding band SB on which the mark RM1 of the reticle R is formed. As a result, the reflected light from the mark RM1 is reflected by the mirror 100 and the objective lens 10
The light is reflected by the beam splitter 102 through the light source 1 and enters the imaging lens 110. The image light flux of the mark RM1 is split into two by the half mirror 111, and is enlarged and formed on the respective imaging surfaces of the CCD camera 112X for detecting the X direction and the CCD camera 112Y for detecting the Y direction by the imaging lens 110. You. The CCD cameras 112X and 112Y are arranged so that the directions of horizontal scanning lines with respect to the enlarged image of the mark RM1 are orthogonal to each other.

At this time, the reference mark FM2A on the reference plate FP is located immediately below the inner area of the light-shielding band SB including the mark RM1.
Is located, the CCDs 112X and 112Y take an image of the cross-shaped slit of the reference mark FM2A as a black line. The image processing circuit 113X subjects the image signal from the CCD camera 112X to digital waveform processing, and outputs the Y signal of the reference mark FM2A.
A positional shift amount in the X direction (horizontal scanning line direction) between the slit extending in the direction and the double slit mark RM1x of the reticle mark RM1 is obtained. The image processing circuit 113Y is C
An image signal from the CD camera 112Y is subjected to digital waveform processing, and a slit extending in the X direction of the reference mark FM2A and a double slit mark RM of the reticle mark RM1.
The position deviation amount in the Y direction (horizontal scanning line direction) from 1y is obtained. The main control system 114 includes a reference mark FM2A and a reticle mark RM1 determined by the processing circuits 113X and 113Y.
When the amount of displacement in the X and Y directions is outside the preset allowable range, the drive system 115 of the reticle stage RST is controlled to correct the position of the reticle R. Drive system 115
Are the three interferometers IRX, IRY and IRθ shown in FIG.
Position of reticle stage RST before correction (X,
Y, θ) are detected, and after the correction, three interferometers IR
Measurement values to be detected by X, IRY, and IRθ are obtained by calculation.

Therefore, the driving system 115 includes three interferometers IR.
Reticle stage RST such that the measured values of X, IRY, and IRθ become the measured values to be detected after the correction.
Is positioned by position servo control. Main control system 114 also controls movement of wafer stage WST by interferometer IF.
The drive system 116 that performs position servo control based on the measured value of X, IFY1, or IFY2 is also controlled.

Now, the TTR alignment system 1A shown in FIG. 7 applies illumination light from the light emitting mark IFS on the reference plate FP to the projection lens PL, the transparent portion inside the light shielding band SB of the reticle R, the mirror 100, A light emitting mark light receiving system for detection via the objective lens 101, the beam splitter 102, the lens system 109, and the beam splitter 108 is provided. This light emitting mark light receiving system is composed of a lens system 120 and a photoelectric sensor (photomultiplier) 121 and the like.
The light receiving surface of the photoelectric sensor 121 is the pupil E of the projection lens PL.
P and a conjugate between the objective lens 101 and the lens system 109. The photoelectric sensor 121 has a light emitting mark I
The FS detects the amount of transmitted light that changes when the FS scans the reticle mark RM1 (or RM2), and outputs a photoelectric signal SSD corresponding to the change. The processing of the photoelectric signal SSD is performed by the interferometer IF in accordance with the scanning of the wafer stage WST.
This is performed by digitally sampling a signal waveform in response to an up / down pulse output from X, IFY1 (for example, one pulse for every movement of 0.02 μm) and storing it in a memory.

Next, an example of the configuration of the TTL alignment system (2Y, 3Y) in FIG. 2 will be described with reference to FIG. The TTL alignment system used in this embodiment is He-Ne
The red light from the laser light source 130 is used as mark illumination light, thereby preventing the influence of the resist layer of the wafer W when detecting the mark reflected light and preventing the resist layer from being exposed to light. Furthermore, the TTL alignment system incorporates two alignment sensors having different mark detection principles, and shares the objective lens 3Y so that the two alignment sensors can be used alternatively. Such a configuration is disclosed in JP-A-2-272305 or JP-A-2-2830.
Since it is disclosed in detail in Japanese Patent Publication No. 11 (Kokai), it will be briefly described here.

The He-Ne laser light from the laser light source 130 is split by the beam splitter 131 and reaches shutters 132A and 132B which are opened and closed complementarily. In FIG. 8, the shutter 132A is open and the shutter 132B is closed, and the laser light is incident on a light transmission system 133A of a two-beam interference alignment (hereinafter, referred to as LIA) method.
The light transmission system 133A divides an incident beam into two laser beams, and outputs the two laser beams by giving a certain frequency difference using an acousto-optic modulator. In the case of FIG. 8, two laser beams output from the light transmission system 133A are arranged in parallel in a direction perpendicular to the plane of FIG. These two laser beams are reflected by the half mirror 134 and further split into two by the beam splitter 135. The two laser beams reflected by the beam splitter 135 intersect on the aperture APA on the wafer conjugate plane by the objective lens 3Y. The two parallel laser beams that have passed through the stop APA are reflected by the mirror 2Y, enter the projection lens PL, and intersect again on the wafer W or the reference plate FP. In the area where the two laser beams intersect, 1
A two-dimensional interference fringe is created, and the interference fringes flow in the pitch direction of the interference fringes at a speed corresponding to the frequency difference between the two beams. Therefore, assuming that the marks LIMy and LIMx shown in FIGS. 4 and 5 are diffraction gratings parallel to the interference fringes, interference beat light whose intensity changes at a beat frequency corresponding to the frequency difference from the diffraction grating marks LIMx and LIMy. Occurs. Assuming that the pitch of the diffraction grating of the marks LIMx and LIMy and the pitch of the interference fringes have a certain relationship, the interference beat light is generated perpendicularly from the wafer W or the reference plate FP, and is transmitted through the projection lens PL. Along the optical path of the transmitted light beam, the mirror 2Y, the aperture APA, and the objective lens 3Y return in this order. The interference beat light partially passes through the beam splitter 135 and reaches the photoelectric detector 139. Photoelectric detector 139
Are arranged almost conjugate with the pupil plane EP of the projection lens PL. A plurality of photoelectric elements (photodiodes, phototransistors, etc.) are arranged on the light receiving surface of the photoelectric detector 139 separately from each other.
9 is received by the photoelectric element located at the center of the pupil plane 9 (the center of the pupil plane). The photoelectric signal becomes a sine wave AC signal having a frequency equal to the beat frequency, and is input to the phase difference measurement circuit 140.

The two transmitted light beams transmitted through the beam splitter 135 intersect as parallel light beams on a transmission type reference grating plate 137 by an inverse Fourier transform lens 136. Therefore, one-dimensional interference fringes are formed on the reference grating plate 137, and the interference fringes flow in one direction at a speed corresponding to the beat frequency. The photoelectric element 138 includes a reference grid plate 137.
One of coherent light of ± 1 dimensional diffracted light or coherent light of the 0th-order light and the 2nd-order diffracted light generated coaxially from the light source.
These interference lights also change in intensity in the form of a sine wave at a frequency equal to the beat frequency, and the photoelectric element 138 outputs an AC signal having a frequency equal to the beat frequency to the phase difference measurement circuit 140 as a reference signal.

The phase difference measuring circuit 140 includes a photoelectric element 138
, The phase difference Δφ (± 180 °) of the AC signal from the photoelectric detector 139 is determined with reference to the reference signal from the photodetector 139, and the mark LIMy on the reference plate FP corresponding to the phase difference Δφ (or the equivalent mark on the wafer) 7) is output to the main control system 114 in FIG. The resolution of the displacement detection is the mark L
It is determined by the relationship between the pitch of IMy and the pitch of the interference fringes irradiated on this mark, and the resolution of the phase difference detection circuit. If the phase difference detection resolution is ± 1 °,
When the grating pitch Pg of the mark LIMy is 8 μm and the pitch Pf of the interference fringes is Pg / 2, the displacement detection resolution is represented by ± (1 ° / 180 °) × (Pg / 4),
It is about ± 0.01 μm.

The main control system 114 shown in FIG. 7 servo-controls the drive system 116 of the wafer stage WST on the basis of the positional deviation information SSB from the TTL alignment system of the high resolution LIA system, Mark LIM
Wafer stage WST can be servo-locked so that y is always driven into a fixed positional relationship with reference lattice plate 137.

However, when the servo lock is performed, the phase difference between the signals from the photoelectric element 138 and the photoelectric detector 139 only needs to be stabilized at a predetermined value.
It is not necessary to convert the phase difference into a positional deviation amount, and servo lock can be performed only by detecting the amount of change from the target value of the phase difference. Another detection method of the TTL alignment system is, as disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 2-233011, for a slit-like laser spot light extending in a direction orthogonal to the mark detection direction. A mark is scanned, and a signal level obtained by photoelectrically detecting diffraction and scattered light generated from the mark is converted into an interferometer IFX generated by movement of the wafer stage WST for scanning the mark.
In this method, digital sampling is performed in response to an up / down pulse from IFY1.

The laser step alignment (L
The SA) type light transmission system 133B includes a shutter 132A.
Is closed and the laser beam enters when the shutter 132B is open. The incident beam is shaped by a beam expander and a cylindrical lens into a slit shape in which the beam cross section at the focal point extends in one direction, and is projected through the beam splitters 134 and 135, the lens system 3Y, and the mirror 2Y. The light enters the lens PL. At this time, the aperture APA is conjugate with the wafer surface (the surface of the reference plate FP) under the wavelength of the He-Ne laser beam, and the beam is focused in a slit shape here. In the case of the TTL alignment system shown in FIG. 8, a beam spot formed by the LSA method is formed into a slit shape extending in the X direction at a stationary position in the projection visual field PIF. When the mark LSMy on the reference plate FP crosses the beam spot by scanning the wafer stage WST in the Y direction, diffracted light or scattered light generated from the mark LSMy is reflected by the projection lens PL and the mirror 2.
The light reaches the photoelectric detector 139 via Y, the objective lens 3Y, and the beam splitter 135, and is received by peripheral photoelectric elements other than the central photoelectric element. The photoelectric signal from the photoelectric element is input to the LSA processing circuit 142 and is digitally sampled in response to an up / down pulse signal UDP from the interferometer IFY1 (or IFY2) for the wafer stage WST. The processing circuit 142 stores the digitally sampled signal waveform in a memory, and performs high-speed waveform processing using digital calculation to determine the center point in the Y direction of the LSA-type slit spot light and the mark L from the waveform on the memory.
The Y coordinate value of wafer stage WST when the center point of SMy in the Y direction precisely matches is calculated and output as mark position information SSA. This information SSA is sent to main control system 114 in FIG.
16 is used for drive control.

In the LSA processing circuit 142, a memory for digitally sampling the photoelectric signal SSD from the photoelectric sensor 121 shown in FIG. And a projection lens PL for the reticle mark RM1
The coordinates of the wafer stage WST when the projected image by the light emitting mark IFS coincides with the reticle mark RM1.
Is output to the main control system 114 as the projection position information SSC.

Next, the detailed configuration of the off-axis alignment system OWA will be described with reference to FIGS.
FIG. 10 shows the configuration of the off-axis alignment system OWA, and IMP represents the surface of the wafer or the surface of the reference plate FP. The image of the surface area of the objective lens 4B located in the field of view MIF is obtained by the prism mirror 4A and the objective lens 4B.
B, mirror 4C, lens system 4D, and half mirror 4E
The image is formed on the index plate 4F via. The light illuminating the surface IMP proceeds to the surface IMP via the lens system 4D, the mirror 4C, the objective lens 4B, and the prism 4A via the half mirror 4E. The illumination light has a bandwidth of about 300 nm in a wavelength region where the sensitivity to the resist layer of the wafer is extremely low.

As shown in FIG. 9, the index plate 4F has index marks TMX1, TMX2, TM formed of a plurality of (for example, four) line patterns formed by a light shielding portion on a transparent glass.
Y1 and TMY2 are formed. FIG. 10 shows a state where the intersection of the straight line LX and LY1 set on the reference plate FP coincides with the center of the index plate 4F. Index mark TM
X1 and TMX2 correspond to the reference mark FM1 on the reference plate FP.
The index marks TMY1,
TMY2 is provided so as to sandwich the reference mark FM1 in the Y direction.

The image of each index mark on the index plate 4F and the image of the reference mark FM1 (or the mark on the wafer) are transferred to the two CCD cameras 4X and 4Y via the imaging lens 4G and the half mirror 4H. Magnified image above. The imaging area of the CCD camera 4X is set to the area 40X in FIG. 9 on the index plate 4F, and the imaging area of the CCD camera 4Y is set to the area 40Y.

The horizontal scanning line of the CCD camera 4X is defined in the X direction orthogonal to the line patterns of the index marks TMX1, TMX2, and the horizontal scanning line of the CCD camera 4Y is orthogonal to the line patterns of the index marks TMY1, TMY2. It is determined in the Y direction. CCD camera 4X, 4
The image signal from each of Y is digitally sampled for each pixel, a circuit for converting and averaging image signals (digital values) obtained for each of a plurality of horizontal scanning lines, and a circuit for index mark TM and reference mark FM1. The information is processed by a waveform processing circuit including a circuit or the like that calculates the amount of displacement in the X direction and the Y direction at high speed.
14 as information SSE.

In this embodiment, the detection center point of the off-axis alignment system OWA is, for example, the center point of two index marks TMX1 and TMX2 in the X direction and two detection points in the Y direction. Index mark TMY
1. Central point of TMY2. However, in some cases,
Of the two index marks TMX1 and TMX2, for example, the center point in the X direction of only the mark TMX2 may be the detection center.

FIG. 11 is an enlarged view of the reference mark FM1 formed on the reference plate FP. A plurality of line patterns extending in the Y direction are arranged at a constant pitch in the X direction.
It is formed as a two-dimensional pattern in which a plurality of line patterns extending in the X direction are arranged at a constant pitch in the Y direction. When detecting the position of the reference mark FM1 in the X direction, C
The image signal from the CD camera 4X is analyzed by a waveform processing circuit, and the average position of each detection position (pixel position) of a plurality of line patterns arranged in the X direction is set as the X direction position of the reference mark FM1, and the index marks TMX1, The amount of deviation from the center position of TMX2 may be obtained.

Detection of the reference mark FM1 in the Y direction,
The detection of the amount of displacement is performed in the same manner by the CCD camera 4Y. By the way, as described above with reference to FIG. 5, the arrangement of various marks on the reference plate FP detected by the TTR alignment system and the TTL alignment system is determined to have a fixed positional relationship. This will be further described with reference to FIG. FIG. 12 is an enlarged view of each mark located on the straight line LX. The mark LIMy is a diffraction grating in which grating elements are arranged at a constant pitch (for example, 8 μm) in the Y direction, and the mark LSMy is shown enlarged in a circle. A small square dot pattern is arranged at a pitch PSx in the X direction and at a pitch PSy in the Y direction.
It is a dimensional lattice pattern. The mark LSMy is detected by a beam spot of the TTL alignment system of the LSA system for the Y direction, the beam spot extends in a slit shape in the X direction, and the beam width in the Y direction is substantially equal to the dimension of the dot pattern in the Y direction. equal. In addition, the pitch PSx in the X direction
Contributes to the generation of diffracted light at the time of mark detection.
The pitch PSy in the direction is for arranging a plurality of lattice marks in the Y direction to form a multi-mark. Therefore, when it is not necessary to form multi-marks, it is only necessary to have only one line of dot pattern groups arranged on the straight line LX.

Although the pitch PSx in the X direction is uniquely determined by the wavelength of the beam spot and the required diffraction angle of the first-order diffracted light, the pitch PSy in the Y direction is PSx
It is better if it is equal to or larger than. As described with reference to FIG. 5, the distance K1 between the center point of the mark LIMy in the X direction and the center point of the reference mark FM2A in the X direction, the center point of the light emitting mark IFS in the X direction, and the mark L
The distance K1 between SMy and the center point in the X direction is K1 = K2
There is a relationship of ± ΔXk. This condition is such that the center of the mark detection area (irradiation area of interference fringes) of the LIA TTL alignment system in this embodiment substantially coincides with the mark detection center point (beam spot) of the LSA TTL alignment system. This is necessary for the above, and is not necessarily limited to the above conditions.

The TTL alignment system described above with reference to FIG. 8 is configured in exactly the same manner for the X direction, and the position information of each mark in the X direction is sent to the main control system 114. Next, the operation of the baseline measurement by the apparatus of the present embodiment will be described. However, the operation described here is typical, and some modified operations will be described later.

FIGS. 13 and 14 are flow charts for explaining a typical sequence. The sequence is mainly controlled by the main control system 114. First, the reticle R stored in a predetermined storage location is automatically or manually conveyed and loaded on the reticle stage RST in a form depending only on mechanical positioning and delivery accuracy. (Step 500).

In this case, the loading accuracy of the reticle R is determined by the reticle mark window area shown in FIG.
If the size of the double slit marks RM1x and RM2y is set to about 4 mm and the size of the double slit marks RM1x and RM2y is set to about 4 mm, the size is preferably ± 2 mm or less. Next, the main control system 114
A reticle search for preliminary rough alignment of the position of the reticle R is performed so that the marks RM1 and RM2 of the reticle R are normally detected by the TTR alignment systems 1A and 1B. As shown in steps 504 and 506 of FIG. 13, this reticle search has two modes, the SRA mode and the IFS mode. In step 502, which mode is selected. The pre-alignment by the IFS method in step 504 means that the light emitting mark IFS searches for a position where the reticle mark RM1 or RM2 is likely to exist while the position of the reticle stage RST is fixed as shown in FIG. The WST is moved in the X and Y directions by a large stroke (for example, several mm) in a large stroke (for example, several mm) to roughly detect the positions of the reticle marks RM1 and RM2, and to calculate the amount of deviation of the detected positions from the designed position. Interferometer IRX for reticle stage RST,
This is a method in which the reticle stage RST is finely moved based on IRY and IRθ.

On the other hand, the pre-alignment by the SRA method in step 506 is executed as follows.
The plain surface of the reference plate FP is placed immediately below the position where the reticle marks RM1 and RM2 are likely to exist, and the TTR is
Using the alignment systems 1A and 1B, the CCD camera 11
The pattern on the reticle R is imaged by 2X and 112Y (FIG. 7), and the image signal waveform corresponding to the horizontal scanning line in one screen is taken into the memory. Next, the reticle stage RST is moved by a fixed amount in the X or Y direction by the drive system 115 based on the measured values of the interferometers IRX, IRY, and IRθ, and then the image signal waveform of the second screen is captured from the CCD camera. 1. Connect with the signal waveform of the first screen. Thereafter, the connected image signal waveforms are analyzed to determine the respective positions of the reticle marks RM1 and RM2, the amount of deviation from the designed position is determined, and then the position of the reticle stage RST is moved.

In any of the search modes, the centers of the marks RM1 and RM2 of the reticle R are set to two TTRs.
Pre-alignment can be performed at the center of the imaging area of the CCD cameras 112X and 112Y provided in each of the alignment systems 1A and 1B with an accuracy of about several μm. Next, the main control system 11
4 enters the reticle alignment operation from step 508, but before that, the two reference marks FM2A, FM2
The drive system 116 is moved to the interferometers IFX, IFY2 so that
The wafer stage WST is positioned under control according to the measured value of (or IFY1). When wafer stage WST is positioned, reference marks FM2A (FM2B) are imaged by CCD cameras 112X and 112Y in a state where they are almost aligned with reticle marks RM1 (RM2).

At this stage, the processing circuits 113X, 1
13Y, the amount of displacement (ΔXR) of the reticle mark RM1 in the X and Y directions with respect to the reference mark FM2A.
1, ΔYR1) and the amount of displacement (ΔXR2) of the reticle mark RM2 in the X and Y directions with respect to the reference mark FM2B.
, ΔYR2). Next, in step 510, it is determined whether or not each positional deviation amount is within an allowable value. If the positional deviation amount is out of the allowable value, the process proceeds to step 512.

At this time, two reticle marks RM1,
As is clear from the shape and arrangement of the RM2, the alignment of the reticle R in the X direction is based on the reference marks FM2A and FM2.
Each reticle mark RM1, RM2 for each center point of B
When each of the center points is shifted toward the center of the reticle CC, and when the center point is shifted in the reverse direction, it is assumed that the center point is negative. Achieved.

Similarly, the alignment of the reticle R in the Y direction and the θ direction is defined as a positive shift when the center point of each of the reticle marks RM1 and RM2 is shifted in the positive direction of the Y axis of the stationary coordinate system. This is achieved by making the polarities and absolute values of the quantities ΔYR1 and ΔYR2 equal. The deviation amount ΔθR of the reticle R in the θ direction (rotation direction) is equal to the reticle mark RM1.
If the distance in the X direction between the RM2 and the RM2 is Lrm, the distance can be obtained from the displacement amounts ΔYR1 and ΔYR2 (actual size on the reticle) in the Y direction by the following equation.

ΔθR = sin-1 ((ΔYR1−ΔYR2) / Lrm) ≒ (ΔYR1−ΔYR2) / Lrm However, since the interval Lrm is constant for any reticle, the evaluation of the deviation amount of the reticle R in the θ direction is as follows. Simply, it is only necessary to determine the magnitude of the absolute value of ΔYR1−ΔYR2. From the above, when the deviation amount of the reticle R in the X, Y, and θ directions is larger than the allowable value, the reticle stage RST is finely moved in step 512. At this time, how much the reticle stage RST should be finely moved in the X direction, the Y direction, and the θ direction is determined by each shift amount (ΔXR1,
Since it is calculated based on (ΔYR1) and (ΔXR2, ΔYR2), the position of the reticle stage RST is finely moved to the position to be corrected while being monitored by the three interferometers IRX, IRY, and IRθ.

This drive system is called a so-called open control system, and includes the control accuracy of the drive system 115 and the reticle stage R
If the positioning accuracy of the ST is sufficiently high and stable, the reticle R can be accurately aligned with the target position by only one position measurement (step 508) and one position correction (step 512). Can be. However, since it is necessary to confirm whether or not the target position is correctly aligned by the position correction, the main control system 114
Repeats the operation from step 508 again.

By the above steps 508 to 510,
Reticle R has two reference marks FM2 on reference plate FP.
A, alignment with respect to the designed coordinate position of FM2B. Next, main control system 114 executes the operation from step 516 shown in FIG. Step 51
Reference numeral 6 is used to select whether the position of the reference plate FP is servo-locked based on the measurement value of the interferometers IFX, IFY2 (or IFY1) for the wafer stage WST, or servo-locked by the TTL alignment system LIA method. is there.

If the servo lock using the interferometer has been selected, the process proceeds to step 518, where the coordinate values of the wafer stage WST at the time when the reticle alignment is achieved are stored, and the interferometers IFX, IFY2 (or IFY1) are stored. )
Is servo-controlled so that the measured value of.. LI
If the A-type servo lock is selected, the process proceeds to step 520, where the shutters 132A and 132A shown in FIG.
32B is set to the state shown in FIG.
Each of IMx and LIMy is irradiated with interference fringes. Then, the wafer stage WST is servo-controlled by the phase difference measurement circuit 140 such that the phase difference between the reference signal and the reference signal always becomes a predetermined value in each of the X direction and the Y direction.

In the case of the LIA method, the two marks LIMx and LIMy on the reference plate FP are aligned with respect to the reference grating plate 138 fixed inside the TTL alignment system. The servo lock of the wafer stage WST can be controlled with almost the same accuracy in the interferometer mode based on the measured values of the interferometers IFX and IFY2 (or IFY1) and in the LIA mode based on the TTL alignment system. According to LI
It has been confirmed that the A mode is more stable than the interferometer mode. Generally, the movement stroke of the wafer stage WST in the X and Y directions is larger than the diameter of the wafer, and for example, needs to be 30 cm or more. For this reason, the optical path length of the laser beams from the interferometers IFX and IFY2 exposed to the atmosphere is longer than several tens of cm, and if local refractive index fluctuations occur in the air between them, the wafer stage WS
Although T is strictly stationary, the counter value inside the interferometer fluctuates on the order of 1/100 μm to 1/10 μm. Therefore, when the servo lock is performed so that the count value of the interferometer becomes constant, the position of wafer stage WST may slightly move within a range of, for example, about ± 0.08 μm due to fluctuation of the refractive index. The fluctuation of the refractive index is
This occurs when a block of air having a temperature difference slowly passes through the optical path of the laser beam from the interferometer. The interferometer for the wafer stage has such environmental disadvantages and may be less stable than the LIA method.
The beam used in the LIA system can be provided with a cover so that it is hardly exposed to the atmosphere, and furthermore, the space between the reticle and the projection lens, and the space between the projection lens and the wafer, where the exposure of the beam cannot be avoided. Has only a few cm at most, so fluctuations in the refractive index hardly occur.

From the above, when the position servo of the reference plate FB (wafer stage WST) can be performed using the TTL alignment system while the reference marks FM2A and FM2B are being detected by the TTR alignment system, it is as small as possible. It is preferable to use Next, the main control system 114
In step 522, reference mark detection is performed by simultaneously using the TTR alignment system and the off-axis alignment system.

In general, when the reticle stage RST is finely moved to the target position in the previous step 510 and the alignment is achieved, the reticle stage RST is fixed to the base column by vacuum suction or the like. During this suction, the reticle stage RST may be laterally shifted by a small amount. Although this lateral displacement is minute, it is one of the error factors in the baseline management and needs to be sufficiently recognized. The recognition is TTR alignment system CCD
Step 50 is performed again using the cameras 112X and 112Y.
8 or the interferometers IRX and IR
It is possible to monitor the amount of change in the measured values of Y and IRθ from the time when the reticle alignment is achieved. However, in this embodiment, since the lateral shift is managed as the baseline amount, it is not necessary to individually determine only the lateral shift amount.

At the stage of step 522, the reference mark FM1 on the reference plate FP has already been located in the detection area of the off-axis alignment system OWA. Therefore, the main control system 114 performs the off-axis control shown in FIG.
Using the CCD cameras 4X and 4Y of the alignment system, X of the index mark TM and the reference mark FM1 in the index plate 4F,
The amount of displacement in the Y direction (ΔXF, ΔYF) is determined as the actual size on the wafer. At the same time, TTR alignment CCD
Reticle mark RM using cameras 112X and 112Y
1 and the reference mark FM2A (ΔXR1, ΔXR1,
YR1), reticle mark RM2 and reference mark FM2
The position deviation amount (ΔXR2, ΔYR2) from B is measured as the actual size on the wafer side. At this time, the TTR method is also turned off.
Also in the Axis system, since both CCD cameras are photoelectric sensors, the processing circuits 113X, 113Y, etc. are controlled so that the timing of taking in the image signal waveform corresponding to the picked-up mark image into the memory is matched as much as possible.

When the position of the reference plate FP is servo-locked by the interferometer, the difference between the time when the image signal waveform is captured by the TTR method and the time when the image signal waveform is captured by the off-axis method is determined by the refraction of air. It is necessary to set the interval sufficiently shorter than the time required for the fluctuation of the wafer stage position due to the fluctuation of the rate. Next, main control system 114 releases the servo lock of wafer stage WST in step 524, and
The operation proceeds to the operation 26, in which the movement (scanning) of the wafer stage WST is started in order to detect each mark on the reference plate FP by simultaneously using the LSA method and the IFS method.

This step 526 moves the wafer stage WST so that the light emitting slit mark IFS scans the reticle mark RM1 two-dimensionally, as described above with reference to FIGS. ,
First, the light emitting slit mark IFS is positioned so as to have the positional relationship shown in FIG. At this time, the slit-shaped beam spot extending in the X direction by the LSA method of the TTL alignment system is shifted in the Y direction with respect to the mark LSMy on the reference plate FP. When the wafer stage WST is scanned in the Y direction from this state, the photoelectric signal from the LSA type photoelectric detector 139 and the IFS type photoelectric element 121 are scanned.
Both waveforms with the photoelectric signal SSD from FIG. FIG. 15A shows a detection waveform of the mark LSMy captured on the memory by the LSA method. Here, since the mark LSMy has five diffraction grating patterns, five peaks occur on the signal waveform. I have. The processing circuit 142 shown in FIG. 8 obtains the position of the center of gravity of each of the five peak waveforms, and calculates the average value as the Y coordinate and the position YLs of the mark LSMy.

On the other hand, the signal SSD obtained by the IFS method
Is a reticle mark RM1 as shown in FIG.
Include two bottom waveform portions for the double slit mark RM1y. The processing circuit 142 finds the center point of each of the two bottom waveforms in the signal waveform of FIG. 15B, and calculates the center point as the center coordinate position YIf in the Y direction of the projected image of the double slit mark RM1y.

Similarly, the light emitting slit mark IFS is moved as indicated by the arrow in the X direction in FIG. 6 to scan the double slit mark RM1x of the reticle mark RM1. At this time, the slit-shaped spot by the LSA method of the TTL alignment system for the X direction is formed by the mark L on the reference plate FP.
Scanning is performed simultaneously by SMx, and a waveform similar to that in FIG. 15 is obtained. At this time, the X coordinate value of the mark LSMx detected by the X direction LSA method is XLs, and IF
Double slit mark RM1 detected by S method
The X coordinate value of x is XIf.

As shown in FIG. 15, the coordinate positions YLS and YLS
The difference from If is the base line amount in the Y direction between the detection center point of the TTL alignment system by the LSA method for the Y direction and the projection point of the center CC of the reticle R. Next, the main control system 1
14 performs an operation for obtaining a baseline amount in step 528. The parameters required for this calculation are shown in FIG.
As shown in Table 6, the measured values are divided into measured values and constant values predetermined in design. In the measured values in the table of FIG. 16, “TTR-A” refers to the TTR alignment system 1A in FIG. 2, and “TTR-B” refers to the TTR alignment system 1B. In addition, the measured values obtained by the respective alignment systems are displayed with the amount of displacement or the mark position in the X direction and the Y direction separately. On the other hand, the constant value in the design includes the center point of the reference mark FM1 and the reference mark FM1.
XA, .DELTA.Xfa, .DELTA.Yfa with respect to the reference mark FM2B, and X, Y between the center point of the reference mark FM1 and the reference mark FM2B.
Direction distances (ΔXfb, ΔYfb) and the wafer stage W
It is stored as a value on a stationary coordinate system determined by the ST interferometers IFX and IFY2 (or IFY1). Therefore, the distances (ΔXfa, ΔYfa) and (ΔXfb, ΔYfb)
The relative tilt amount in the XY coordinate system between the straight line LX on the reference plate FP and the reflection surface of the movable mirror IMy caused by an error in mounting the reference plate FP to the wafer stage WST, and the reference plate of each reference mark. It is assumed that an arrangement error on the FP is included in advance.

The main control system 114 has constant values ΔXfa, ΔXfb
, The X-direction distance LF between the bisecting point of the line connecting the center points of the reference marks FM2A and FM2B and the center point of the reference mark FM1 is calculated. LF = (ΔXfa + ΔXfb) / 2 (1) Next, the main control system 114 calculates the deviation ΔXR1 in the X direction obtained by TTR-A and the deviation ΔX in the X direction obtained by TTR-B.
One half of the difference ΔXcc from R2 is obtained as the dimension on the wafer side.

ΔXcc = (ΔXR1−ΔXR2) / 2 (2) where ΔXR1 and ΔXR2 are reticle marks RM1 and R
When M2 is displaced in the direction of the center of the reticle with respect to each of the reference marks FM2A and FM2B, it takes a positive value, and when M2 is displaced in the opposite direction, it takes a negative value. When the value ΔXcc obtained by the equation (2) is zero, the projected point of the center CC of the reticle R exactly matches the bisecting point in the X direction of each of the center points of the two reference marks FM2A and FM2B. Will be.

Next, the main control system 114 determines the center CC of the reticle R based on the measured value ΔXF and the calculated values LF and ΔXcc.
Projected point on the XY coordinate plane, and the projected point on the XY coordinate plane of the center point in the X direction of the index plate 4F of the off-axis alignment system OWA (a bisecting point between the index marks TMX1 and TMX2). The distance BLOx in the X direction with respect to the off-axis alignment system OWA is calculated as the X direction base line amount.

BLOx = LF−ΔXcc−ΔXF (3) where ΔXF is a distance between the reference mark FM1 and the projection lens P with respect to the bisecting point of the index marks TMX1 and TMX2 in the X direction.
It is assumed that a positive value is detected when the light is detected in the direction of L (reference marks FM2A, FM2B), and a negative value is detected when the light is detected in the reverse direction.

Next, the main control system 114, based on the actually measured values ΔYR1 and ΔYR2, calculates a line segment connecting the projected point of the center point CC of the reticle R and the center point of the reference mark FM2A and the center point of FM2B. The amount of deviation ΔYcc in the Y direction from the dividing point (almost on the straight line LY2) is obtained. ΔYcc = (ΔYR1−ΔYR2) / 2 (4) where ΔYR1 and ΔYR2 are reticle marks RM1
, RM2 respectively correspond to the reference marks FM2A, FM2
With respect to 2B, the value takes a positive value when it is shifted in the positive direction of Y in FIG. 4 (upward in the paper plane of FIG. 4), and a negative value when it is shifted in the reverse direction. The shift amount Ycc is determined by comparing the projected point of the center CC of the reticle R with the reference marks FM2A and FM2.
It becomes zero when the bisecting point of the line connecting the center points of B exactly matches. Further, the main control system 114 has a constant value ΔYf
Based on a and ΔYfb, a deviation ΔYf2 in the Y direction between a bisecting point of a line connecting the center points of the reference marks FM2A and FM2B and the center point of the reference mark FM1 is obtained.

ΔYf2 = (ΔYfa−ΔYfb) / 2 (5) On the basis of the calculated values ΔYcc and ΔYf2 and the actually measured value ΔYF, the main control system 114 sets the projected point of the center CC of the reticle R to OFF.・ Index plate 4 for Axis alignment system OWA
Distance BLOy in the Y direction from the projection point of the center point of F in the Y direction (a bisecting point between index marks TMY1 and TMY2).
Is calculated as the Y-direction baseline amount of the off-axis alignment system OWA.

BLOy = ΔYcc−ΔYf2−ΔYF (6) By the above calculation, the off-axis alignment system O
The baseline amount (BLOx, BLOy) of the WA is determined, and then the main control system 114 determines the baseline amount (BLTx, BLTy) of the TTL alignment system of the LSA system. The base line amount BLTy of the LSA type TTL alignment system for the Y direction is determined by calculating the Y value between the center point of the slit beam spot in the Y direction and the projection point of the center CC of the reticle R.
It is the amount of deviation in the direction, and is obtained by the following equation.

BLTy = YIf−YLs (7) Similarly, the base line amount BLTx of the LSA type TTL alignment system for the X direction is the center of the slit-shaped beam spot in the X direction and the center of the reticle R. This is the amount of deviation of the CC from the projection point in the X direction, and is obtained by the following equation. BLTx = XIf−XLs (8) However, the values obtained by the equations (7) and (8) include the arrangement error ΔYsm in the Y direction between the center of the light emitting mark IFS and the mark LSMy on the reference plate FP. , Emission mark IFS and mark LS
Since an arrangement error ΔXsm in the X direction with respect to Mx is included, if these errors cannot be ignored, they are stored in advance as constant values, and Equations (7) and (8) are respectively substituted into Equation (7 ′). , (8 ′).

BLTy = YIf−YLs−ΔYsm (7 ′) BLTx = XIf−XLs−ΔXsm (8 ′) By the above sequence, the baseline measurement is completed and the pre-processing is performed on the wafer stage WST. The aligned wafer W is placed thereon. On the wafer W, a plurality of exposure areas, that is, shot areas where the pattern area PA of the reticle R is projected are two-dimensionally arranged. In each shot area, an off-axis alignment system O
WA or TTL alignment system (2X, 3X; 2Y,
3Y), the alignment mark is formed in a fixed positional relationship with the center point of the shot area. In many cases, the alignment marks on those wafers are provided in the street lines.

There are many known methods and sequences for actual wafer alignment, so that the description of these methods and sequences will be omitted here, and only the basic wafer alignment will be described. FIG. 17 shows the arrangement of shot areas and marks on the wafer W. The X-direction interval between the center SCn of the shot area SAn and the X-direction mark WMx is ΔXwm, and the center SCn and the Y-direction W mark WMy are Y-direction. The interval in the Y direction is determined by design as ΔYwm. First, when the off-axis alignment system OWA is used, the mark WMx of an arbitrary shot area SAn is set to the index marks TMX1 and TMX2 within the detection area of the off-axis alignment system OWA.
The wafer stage WST is positioned so as to be sandwiched between them. Here, the marks WMx and WMy are the reference marks FM.
It is assumed that the pattern is a multi-line pattern as in the case of FIG.

Then, main control system 114 reads coordinate position Xm of wafer stage WST in the X direction, which is positioned, from interferometer IFX. Further, an image signal from the CCD camera 4X in the off-axis alignment system OWA is processed to detect a deviation amount ΔXp in the X direction between the center point of the index plate 4F and the center point of the mark WMx. Next, wafer stage WST is moved so that wafer mark WMy is sandwiched between index marks TMY1 and TMY2 of the off-axis alignment system.
Position. At this time, the coordinate position Ym in the Y direction is read from the interferometer IF1. Then, the amount of displacement ΔYp in the Y direction between the center point of the index plate 4F and the center point of the mark WMy is obtained by imaging with the CCD camera 4Y.

After the above-described mark position detection is completed, the coordinate position of the wafer stage WST for aligning the center SCn of the shot area SAn with the projection point of the center CC of the reticle R during exposure is calculated only by the following equation. Xe, Y
e) is required. Xe = Xm- [Delta] Xp + (BLOx- [Delta] Xwm) (9) Ye = Ym- [Delta] Yp + (BLOy- [Delta] Ywm) (10) The mark WM in the LSA TTL alignment system
When detecting x and WMy, the mark W by the LSA method is used.
With the respective detection positions of Mx and WMy being Xm and Ym, the stage coordinate position at the time of exposure is obtained by the following equation.

Xe = Xm + BLTx−ΔXwm (11) Ye = Ym + BLTy−ΔYwm (12) The embodiment of the present invention has been described above. In this embodiment, the off-axis alignment system OWA is stationary. Even at the detection center point in the coordinate system, the two measurement axes of the interferometers IFX and IFY1 are defined so as to be orthogonal, so that the two-dimensional mark position detection using the off-axis alignment system OWA is performed.
Using the measured values of the two interferometers IFX and IFY1, the coordinates, position Xm, and Y of the wafer stage WST at the time of mark detection are used.
m and the deviation amounts ΔXp and ΔYp of the mark positions do not include Abbe errors.

Therefore, when detecting a wafer mark or a reference mark using the off-axis alignment system OWA, not the interferometer IFY2 satisfying the Abbe condition for the projection lens PL but the Abbe condition for the alignment system OWA. It is important to use an interferometer IFY1 satisfying As a means for servo-locking the position of the reference plate FP for the baseline measurement of the off-axis alignment system OWA, a TTR alignment system for simultaneously detecting the reticle marks RM1, RM2 and the reference marks FM2A, FM2B is used. The wafer stage WST may be servo-controlled so that the amount of positional deviation always becomes a predetermined value.

Next, a modification of this embodiment will be described.
Step 50 in the sequence described in FIGS.
In Steps 8 to 512, the reticle alignment is completely achieved by using the TTR alignment systems 1A and 1B, but the operation can be omitted to some extent. As shown in FIG. 2, in the apparatus of this embodiment, the reticle R
Of the X, Y, and θ directions of the interferometers IRX, IRY,
Since the reticle mark RM is continuously monitored by IRθ, the reticle mark RM
1, when the projection point coordinates of RM2 are detected by the interferometer on the wafer stage side, the amount of deviation from the designed arrangement of the reticle R in the X, Y, and θ directions is calculated by calculation based on the coordinate values. Reticle stage RST may be finely moved by relying on the reticle-side interferometer so that the shift amount is corrected. In this case, the reticle-side interferometers IRX, IRY,
The measurement resolution of IRθ is sufficiently high (for example, 0.005 μm).
If m), the positioning of the reticle R will be performed very accurately.

The off axis used in this embodiment is
Alignment system OWA is a static alignment system that performs mark detection in a state where wafer stage WST is stationary. However, as in LSA TTL alignment system or IFS system, mark detection is performed by moving wafer stage WST. The same effect can be obtained by a scanning alignment method that performs the above. For example, in a case where the off-axis alignment system OWA is configured to project the laser beam spot into a slit shape on the wafer W and detect the mark on the wafer by scanning the stage WST,
When the wafer stage WST is moved so that the reference mark FM1 on the reference plate FP crosses the beam spot, at the same time, the emission mark IFS is changed to the reticle mark RM1,
Alternatively, the arrangement of each mark on the reference plate FP may be determined so as to scan the RM2.

Further, an off-axis alignment system O
When the LIA system is incorporated in the WA and the reference mark FM1 on the reference plate FP is set to the same diffraction grating as the marks LIMx and LIMy, the reference mark FM1 detected by the off-axis alignment system OWA becomes off-axis alignment The wafer stage WST can be servo-locked based on the detection result of the phase difference measurement circuit so that the wafer stage WST is always aligned with the LIA reference grating in the system. In this case, with the detection center of the off-axis alignment system OWA precisely aligned with the center of the fiducial mark FM1, the TTR alignment systems 1A and 1B
By calculating the respective positional deviation amounts between the reference marks FM2A and FM2B and the reticle marks RM1 and RM2, the baseline amount can be calculated. In this case, TT
The displacement amount detected by the R alignment system is a baseline error amount, and this value is stored in the memory.

Further, as a TTL alignment system, CC
Using a D camera, both the mark image on the wafer or the reference plate FP and the image of the index mark provided in the optical path of the TTL alignment system are imaged, and the amount of displacement of the mark is detected. A method of performing position detection may be used. In the case of this method, the projection point of the center point (detection center point) of the index mark in the optical path of the TTL alignment system on the wafer side and the projection point of the center of the reticle marks RM1 and RM2 (or the center CC of the reticle). The baseline amount may be managed during the period.

Incidentally, the IFS system shown in this embodiment has been described exclusively as a stage scan, that is, a scanning type alignment system. However, a stationary type alignment system may be used. For that purpose, the light emitting mark IFS on the reference plate FP is changed from a slit shape to a rectangular light emitting surface,
Double slit RM1y of reticle mark shown in FIG.
(Or RM1x), a rectangular light emitting surface sufficiently larger than the width of the double slit is positioned, and the mark RM1y is positioned from above the reticle R using a TTR alignment system or the like.
If an image of (or RM1x) is taken by a CCD camera or the like, an image signal having a waveform equivalent to the waveform shown in FIG. 15B can be obtained. At this time, if the mark serving as the index is not in the TTR alignment system, the shift amount of the double slit mark RM1y (or RM1x) can be obtained with reference to a specific pixel position of the CCD camera. Further, in this method, the projection point at the center of reticle mark RM1 (or RM2) is calculated based on the shift amount and the coordinate value of wafer stage WST when positioning the rectangular light emitting surface. Incidentally, as shown in FIG.
A light-shielding slit pattern SSP for measuring an amount of deviation from the double slit mark RM1y (RM1x) is provided in a part of the rectangular light emitting surface PIF, and the light emitting surface PIF is imaged by a CCD camera of a TTR alignment system. Then, the positional deviation between the dark line by the double slit mark RM1y and the dark line by the slit pattern SSP may be obtained.

FIG. 18 shows a modified example of the arrangement of the reference plate FP on the wafer stage WST and the arrangement of the off-axis alignment system. The position of the objective lens 4B of the off-axis alignment system is shown in FIG. Projection lens P in the paper
FIG. 4 is a configuration diagram when the position is below L. This position is on the front side of the apparatus main body and corresponds to the wafer loading direction.
18 are the same as those in FIG. 3 except for the interferometers IFY, IFX1, and IFX2 for measuring the position of the wafer stage WST among the reference numerals in FIG. In the case of FIG. 18, the optical axis position of the projection lens PL and the off-axis alignment system O
Since the line segment connecting the detection center of the WA (substantially the optical axis position of the objective lens 4B) is parallel to the Y axis, the interferometer I in the Y direction is used.
The number of FY is one, and the number of interferometers IFX1 and IFX2 in the X direction is two. In accordance with this, the arrangement of the marks on the reference plate FP is changed, and the line connecting the center points of the reference marks FM1 and FM2 is made parallel to the Y axis.

Also in the case shown in FIG. 18, a mark on a wafer,
Alternatively, when detecting the reference mark FM1 or the like, the interferometers IFX1 and IFY satisfying the Abbe condition are used, and the interferometers IFX2 and IFX are used for positioning the wafer stage during exposure.
Y is used. That is, when a mark is detected by the off-axis alignment system OWA, the interferometer I
Since it is measured by FX1, the position coordinate value in the X direction is associated with the position coordinate value measured by interferometer IFX2. This association is made with the interferometers IFY1 and IFY2 shown in FIG.
The same is done during the period.

By the way, as shown in FIGS. 13 and 14, the baseline measurement operation exemplified above is performed after the precise reticle alignment is completed.
Baseline measurement may be performed when the reticle is roughly aligned. For example, at step 504 or 506 in FIG.
Until M1 and RM2 reach positions that can be detected by the TTR alignment systems 1A and 1B, the SRA method or the IFS
The reticle is roughly aligned by the method. Thereafter, step 508 in FIG. 13 and step 522 in FIG. 14 are simultaneously executed to shift the positions of the reference mark FM2A and the reticle mark RM1 (ΔXR1, ΔYR1) and the positions of the reference mark FM2B and the reticle mark RM2. The deviation amounts (ΔXR2, ΔYR2) and the positional deviation amounts (ΔXF, ΔYF) between the reference mark FM1 and the index marks of the off-axis alignment system are obtained.

At this time, the reference plate FP is servo-locked in the interferometer mode or the LIA mode. However, taking into account the slight movement of the wafer stage WST, the amount of displacement by the TTR alignment system and the off-axis alignment system is considered. The detection is repeatedly performed several times, and the average value is obtained. This averaging reduces the amount of error that occurs randomly. When the amount of each position shift is obtained in this manner, the center CC (or the mark RM) of the reticle R is calculated thereafter.
The relative positional relationship between the projection point of (1, RM2) and the detection center point of the off-axis alignment system OWA can be understood. Further, the position (rough alignment position) of reticle stage RST in this state is determined by using interferometers IRX and IR.
It is read from the measured values of Y and IRθ and stored. It is desirable to perform averaging also for this reading. Then, the previously measured displacement amounts (ΔXR1, ΔYR
1) Based on (ΔXR2, ΔYR2), (ΔXF, ΔYF) and a preset constant value, the detection center point of the off-axis alignment system OWA is set to the reference mark F.
A projection point of the center CC of the reticle and a center point of the reference mark FM2 (a bisecting point between the marks FM2A and FM2B) to be generated when the center coincides with the center of M1 (ΔXF = 0, ΔYF = 0). Is calculated (X, Y, θ directions). Thereafter, reticle stage R
ST is slightly moved from the stored rough alignment position by using the interferometers IRX, IRY, and IRθ. Thus, reticle R is off-axis alignment system OW
A is precisely aligned with the detection center of A.
The main control system 114 continues the sequence from step 524 in FIG.

As described above, when there is a sensor (interferometer or alignment system) that can measure the position change amount of reticle stage RST (that is, reticle R) over a relatively long range (for example, ± several mm) with high accuracy. Can store the rough alignment position, perform the operation of detecting each fiducial mark for baseline measurement, and then perform fine alignment of the reticle R.
Throughput can be improved as compared with the sequence of 3 and 14.

In the embodiment of the present invention, the TTL of the LIA system is used.
Although the alignment system is used for servo locking of the reference plate FP, it is necessary to manage the baseline of the LIA TTL alignment system itself with the center CC of the reticle R. Assuming that a TTL alignment system of the LIA system is used to detect a mark on the wafer W, the reticle marks RM1, RM2 detected by the TTR alignment systems 1A, 1B and the reference mark FM2A,
When the FM2B precisely matches, the phase errors Δφx, Δφy of the marks LIMx, LIMy detected by the LIA TTL alignment systems 1A, 1B, respectively.
May be stored as a considerable amount of the baseline error amount with respect to the center CC of the reticle R.

The exposure apparatus described in the above embodiments is a stepper for exposing the projection image of the pattern area PA on the reticle R onto the wafer W by a step-and-repeat method. The present invention can be similarly applied to a step-scan type exposure apparatus that simultaneously scans a wafer in a direction perpendicular to the optical axis of a projection optical system. Also,
A similar alignment system can be applied to an X-ray aligner using an X-ray source such as an SOR, an X-ray stepper, and the like.

[0094]

As described above, according to the present invention, since the baseline measurement is performed without being affected by the various precisions of the substrate stage, an improvement in the accuracy of the baseline measurement can be expected. In addition, the alignment of the reticle (mask) and the baseline measurement can be performed almost simultaneously, the stage is moved to check the rotation error of the mask (error in the θ direction), or the stage is moved for the baseline measurement. Since there is no need to perform such operations, the effect of improving the total processing speed can be obtained. Furthermore, according to the present invention, since the reticle alignment and the baseline measurement can be performed almost simultaneously, even if a sequence for performing the baseline measurement every time the wafer is replaced is set, the throughput is not deteriorated, and the baseline is not deteriorated. , And the position drift of the reticle holder due to the exposure of the reticle to the exposure light can be confirmed and corrected at high speed.

According to the embodiment, a TTL alignment system or a TTR alignment system (second mark detecting means)
With the position of the reference plate servo-locked using, the mark on the reference plate is set to off-axis alignment system (1st
The mark is detected by the mark detection means) and baseline measurement is performed, so that the measurement caused by the influence of air fluctuation (refractive index fluctuation) on the optical path of the interferometer without using an interferometer for measuring the position of the substrate stage as in the related art. Errors can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a state of baseline measurement in a conventional projection exposure apparatus.

FIG. 2 is a perspective view showing a configuration of a projection exposure apparatus according to an embodiment of the present invention.

FIG. 3 is a plan view showing an arrangement of a reference mark plate on a wafer stage.

FIG. 4 is a plan view showing an arrangement of various marks on a reference mark plate.

FIG. 5 is a plan view showing an arrangement relationship between an image field, a reticle pattern, and a reference mark of a projection lens.

FIG. 6 is a diagram showing an example of the shape of a reticle alignment mark.

FIG. 7 is a diagram showing a configuration of a TTR alignment system.

FIG. 8 is a diagram showing a configuration of a TTL alignment system.

FIG. 9 is a view showing a pattern arrangement of an index plate of an off-axis alignment system.

FIG. 10 is a diagram showing a configuration of an off-axis alignment system.

FIG. 11 is a diagram showing an example of a reference mark pattern on a reference mark plate detected by an off-axis alignment system.

FIG. 12 is a diagram showing an example of a reference mark pattern detected by each of a TTR alignment system and a TTL alignment system.

FIG. 13 is a flowchart showing the first half of the baseline measurement operation of the present apparatus.

FIG. 14 is a flowchart showing the latter half of the baseline measurement operation of the apparatus.

FIG. 15 is a waveform chart showing an example of a signal waveform obtained by an alignment system.

FIG. 16 is a table summarizing parameters required for a baseline calculation.

FIG. 17 is a plan view showing a shot arrangement and a mark arrangement on a wafer.

FIG. 18 is a plan view showing another arrangement of the off-axis alignment system.

FIG. 19 is a diagram showing another pattern example of the light emitting mark on the reference mark plate.

[Explanation of symbols]

R Reticle W Wafer PL Projection lens RST Reticle stage WST Wafer stage 1A, 1B TTR alignment system 2X, 3X TTL alignment system for X direction 2Y, 3Y TTL alignment system for Y direction OWA Off-axis alignment system FP Reference plate FM1 Off- Reference mark for Axis alignment system FM2 Reference mark for TTR alignment system IFX, IFY Laser interferometer RM1, RM2 for wafer stage Reticle mark

Claims (29)

(57) [Claims] 1. A pattern image of a mask is projected on a substrate.
A projection optical system and detection outside the projection field of view of the projection optical system
An exposure apparatus comprising: a first mark detection system having a center and detecting a mark on the substrate; and a second mark detection system detecting a mark on the mask, wherein the first and second mark detection systems include: An exposure apparatus comprising a mark plate capable of simultaneous detection by a mark detection system. 2. The mark plate according to claim 1, wherein a first mark detected by the first mark detection system and a second mark detected by the second mark detection system are formed separately from each other. The exposure apparatus according to claim 1, wherein: 3. The exposure apparatus according to claim 1, further comprising a movable body provided with the mark plate and arranged on a coordinate system that defines movement of the substrate. 4. The exposure apparatus according to claim 3, wherein the movable body is a substrate stage that holds the substrate. 5. A pattern image of a mask is projected onto a substrate.
A projection optical system and detection outside the projection field of view of the projection optical system
An exposure apparatus comprising: a first mark detection system having a center and detecting a mark on the substrate; and a second mark detection system detecting a mark on the mask, wherein the first and second mark detection systems include: An exposure apparatus comprising a movable body on which a reference mark that can be simultaneously detected by a mark detection system is formed. 6. A pattern image of a mask is projected onto a substrate.
A projection optical system and detection outside the projection field of view of the projection optical system
An exposure apparatus , comprising: a first mark detection system having a center and detecting a mark on the substrate; and a second mark detection system detecting a mark on the mask, wherein the first and second marks are provided. An exposure apparatus comprising: a movable body on which a reference mark that can be detected by a mark detection system at the same position is formed. 7. The apparatus according to claim 1, further comprising an interferometer for detecting position information on a rectangular coordinate system on which the movable body moves, wherein the first and second mark detection systems detect the baseline when measuring the first mark detection system. 7. The exposure apparatus according to claim 5, wherein a detection result and information on a rotation amount of the movable body obtained from the interferometer are used. 8. The apparatus according to claim 7, wherein the first mark detection system detects the reference mark a plurality of times, and uses a plurality of detection results of the first mark detection system at the time of the baseline measurement. Exposure equipment. 9. The method according to claim 7, wherein the second mark detection system detects the reference mark a plurality of times, and uses a plurality of detection results of the second mark detection system at the time of the baseline measurement. Exposure apparatus according to the above. 10. An interferometer for detecting position information on a rectangular coordinate system on which the movable body moves, wherein the first and second mark detection systems detect the baseline when measuring the first mark detection system. 7. The exposure apparatus according to claim 5, wherein a detection result on one side and information on a position and a rotation amount of the movable body detected by the interferometer are used. 11. The first mark detection system or the second mark detection system.
The device according to any one of claims 7 to 10, further comprising a drive control unit that servo-locks the movable body using an output of the interferometer when the reference mark is detected by a mark detection system. Exposure equipment. 12. The first mark detection system or the second mark detection system.
When the mark detection system detects the fiducial mark, a drive control unit for servo-locking the movable body using an output of a third mark detection system for detecting a specific mark provided on the movable body is further provided. The exposure apparatus according to claim 5. 13. The exposure apparatus according to claim 12, wherein the third mark detection system is one of the first and second mark detection systems. 14. A mask stage for holding the mask, and a second interferometer for detecting positional information of the mask stage, wherein the output of the second interferometer at the time of baseline measurement of the first mark detection system. 7. The exposure apparatus according to claim 5, wherein 15. The exposure apparatus according to claim 14, wherein the position information of the mask stage is detected a plurality of times by the second interferometer, and the plurality of position information is used when measuring the baseline. 16. The exposure apparatus according to claim 5, wherein the movable body is a substrate stage that holds the substrate. 17. A projection optical system for projecting a pattern image of the mask onto the substrate, wherein the first mark detection system has a detection area outside a field of view of the projection optical system. Item 18. The exposure apparatus according to any one of Items 1 to 17. 18. The method of claim 17, wherein the first mark detection system, an exposure apparatus according to claim 17, wherein the benzalkonium which have a objective optical system separately provided from said projection optical system. 19. The reference mark has at least a first mark detected by the first mark detection system and a second mark detected by the second mark detection system, and the first and second marks are provided. 19. The exposure apparatus according to claim 5, wherein the marks are formed at different positions on the movable body. 20. The exposure apparatus according to claim 19, wherein the first and second marks are formed on the same plate provided on the movable body. 21. A pattern formed on a mask is projected light.
In a method of exposing a substrate through a scientific system , a detection center is provided outside a projection field of view of the projection optical system, and
One the said first mark detection system baseline measurement for detecting the mark on the substrate, and the detection of the first mark by the first mark detection system, according to the second mark detecting system that detects marks on the mask An exposure method, wherein the movement of a mark plate on which the first and second marks are formed is controlled so that the detection of the second mark can be performed simultaneously. 22. A pattern formed on a mask is projected light.
In a method of exposing a substrate through a scientific system , a detection center is provided outside a projection field of view of the projection optical system, and
One the said first mark detection system baseline measurement for detecting the mark on the substrate, and the detection of the first mark by the first mark detection system, according to the second mark detecting system that detects marks on the mask An exposure method comprising: positioning a mark plate on which the first and second marks are formed so that detection of a second mark can be performed at the same position. 23. The exposure method according to claim 21, wherein information on a rotation amount of the mark plate is used at the time of the baseline measurement. 24. The first mark detection system according to claim 1, wherein
The exposure method according to any one of claims 21 to 23, wherein mark detection is performed a plurality of times, and a plurality of detection results of the first mark detection system are used during the baseline measurement. 25. The second mark detection system according to claim 25, wherein
The exposure method according to any one of claims 21 to 24, wherein mark detection is performed a plurality of times, and a plurality of detection results of the second mark detection system are used at the time of the baseline measurement. 26. The exposure method according to claim 21, wherein the mark plate is servo-locked using the position information of the mark plate at the time of the baseline measurement. 27. The apparatus according to claim 21, wherein said mask position information is used at said baseline measurement.
The exposure method according to any one of the above. 28. The exposure method according to claim 27, wherein the position information of the mask is detected a plurality of times, and the plurality of position information is used at the time of the baseline measurement. 29. The exposure method according to claim 21, wherein the pattern is exposed on the substrate by scanning the mask and the substrate.