JPH10261570A - Stage device and aligner with the device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure the rotary angle of a movable part without using especially optical beams for measuring a rotary angle in addition to optical beams for measuring the displacement of a movable part in a specific direction that moves along with a positioning target. SOLUTION: Laser beams from an interferometer body 12X are divided into beams LX1 for measurement and beams LX2 for reference by a polarization beam splitter 17X, the beams LX1 for measurement make a round trip for two times between a double path unit 18X and a mirror surface 8x of a sample stand 8 and return to an interferometer body 12X, the beams LX2 for reference make a round trip for two times between a double path unit 22X and a reference mirror 14X and return to the interferometer body 12X, and the displacement of the mirror surface 8x is detected by the interferometer body 12X. By detecting the amount of side shift of the beams LX1 for measurement by a stage rotary angle detection system 15X, the rotary angle of the mirror surface 8x is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for transferring a mask pattern onto a substrate such as a wafer in a lithography process for manufacturing, for example, a semiconductor device, a liquid crystal display device, an image pickup device (CCD or the like), a thin film magnetic head or the like. Apparatus suitable for use as a stage of an exposure apparatus for use in an exposure apparatus, and an exposure apparatus having the stage apparatus.

[0002]

2. Description of the Related Art Conventionally, when manufacturing a semiconductor device or the like, an exposure apparatus has been used which transfers a reticle pattern as a mask onto a wafer (or a glass plate or the like) coated with a resist. As an exposure apparatus, in addition to a batch exposure type such as a stepper, a scanning exposure type such as a step-and-scan method is being used. Further, an electron beam exposure apparatus and the like have been used.
These exposure apparatuses are provided with a stage for positioning the reticle and the wafer or for performing continuous scanning with high accuracy.

FIG. 9A is a plan view showing a stage on the wafer side of a conventional batch exposure type projection exposure apparatus, and FIG.
FIG. 9B is a front view of the reticle. As shown in FIG. 9B, the exposure light transmitted through the reticle (not shown) forms a pattern image of the reticle on the photoresist on the wafer 51 via the projection optical system 50. . The wafer 51 is vacuum-sucked to a wafer holder (not shown), the wafer holder is fixed on a sample stage 52, the sample stage 52 is fixed on a wafer stage 55, and the wafer stage 55 is placed on a surface plate 56 via an air bearing. It is mounted so that it can move two-dimensionally in a plane perpendicular to the optical axis AX of the projection optical system 50. Optical axis AX
Assuming that the direction along the axis is the Z axis and the orthogonal coordinate system of a plane perpendicular to the Z axis is the X axis and the Y axis, the wafer stage 55
2 (wafer 51) is finely moved in the Z direction and positioned in the X and Y directions.

[0004] Further, as shown in FIG.
In order to measure the two-dimensional position of the wafer 2 (wafer 51), two elongated plate-shaped movable mirrors 53X and 5X are provided at the end of the sample table 52 such that the reflection surface is perpendicular to the X axis and the Y axis, respectively.
3Y is fixed, and the X-axis interferometer body 5 is attached to the movable mirror 53X.
From 4X, two-axis measurement laser beams 57X and 58X are emitted in the Y direction at an interval D1. Then, the interference light between the reflected laser beam and the corresponding reference beam (not shown) is photoelectrically detected in the interferometer main body 54X, so that the sample stage 5 at the irradiation point of the laser beams 57X and 58X is detected.
2 are measured. In this case, the X coordinate of the sample table 52 is calculated from the average value of the two displacements, and the difference between the two displacements is divided by the interval D1 to obtain the X axis of the sample table 52 around the axis parallel to the Z axis. The rotation angle (the amount of yawing) is calculated. Similarly, the movable mirror 53Y is irradiated with two measurement laser beams 57Y and 58Y at an interval D1 in the X direction from the Y-axis interferometer body 54Y, and the displacement at the irradiation point of the laser beams 57Y and 58Y. The Y coordinate of the sample table 52 is calculated from the average value of the above, and the yawing amount is calculated by dividing the difference between those displacements by the interval D1. The center lines of the laser beams 57X and 58X and the center lines of the laser beams 57Y and 58Y respectively pass through the optical axis AX.

Further, as shown in FIG. 9B, a laser beam 57 is transmitted from the interferometer main body 54X to the movable mirror 53X.
The laser beam 59 for measurement has an interval of D2 with X in the Z direction.
X is irradiated, and the displacement at the irradiation point of the laser beam 59X is also detected. Then, the laser beams 57X and 59
By dividing the difference between the displacements measured via X by the interval D2, the rotation angle (the amount of rolling in the Y direction) about the axis parallel to the Y axis of the sample stage 52 is calculated. Similarly, the distance D2 from the Y-axis interferometer main body 54Y in the Z-direction.
Are irradiated with two measurement laser beams, and the difference between the displacements measured by the two is divided by the interval D2, whereby the rotation angle (in the Y direction) about the axis parallel to the X axis of the sample stage 52 is obtained. Is calculated. That is, FIG.
The conventional interferometer system shown in (1) is composed of a single-pass interferometer having at least three axes with respect to the X-axis and a single-pass interferometer having at least three axes with respect to the Y-axis.

Further, conventionally, the amount of bending of the movable mirrors 53X and 53Y has been measured using an interferometer system as shown in FIG. For example, the Y-axis movable mirror 53
When performing the bending measurement of Y, by driving the wafer stage 55, the sample table 52 is continuously moved to X, for example.
In the direction, and the difference ΔYL of the displacement measured by the interferometer main body 54Y via the laser beams 57Y and 58Y almost continuously as a function of the position X, and the interferometer main body 54X via the laser beams 57X and 58X. The yaw amount θZ (θZ is the amount of rotation about the Z axis) of the sample table 52 is obtained as a function of the position X from the displacement measured by the measurement. In this case, if the bending of the movable mirror 53Y is exaggerated as shown in FIG. 10A, the tilt angle obtained by dividing the displacement difference ΔYL detected via the laser beams 57Y and 58Y by the interval D1. The result obtained by subtracting the yawing amount θZ from the above becomes the bending angle Δθ of the movable mirror 53Y at that position. Therefore, the turning angle Δθ at each point is
By integrating the value obtained by multiplying the displacement amount ΔXL in the X direction for each calculation of θ, as shown in FIG. 10B, the position ΔYM of the reflecting surface of the movable mirror 53Y depends on the position in the X direction. The change in the position ΔYM is
Y represents the amount of bending.

In FIG. 9, while moving the sample stage 52 at a predetermined relatively large interval in the X direction, the bending angles .DELTA..theta. Of the movable mirror 53Y are calculated at each stationary point, and these bending angles .DELTA..theta. A method of obtaining the amount of bending in the entire range of the movable mirror 53Y by interpolating using the method has also been proposed.

[0008]

As described above, in the conventional projection exposure apparatus, the sample stage 52 of the stage on the wafer side is used.
In order to measure not only the position of the (wafer 51) in the X and Y directions but also the amount of yawing of the sample table 52, the X-axis interferometer main body 54X moves the corresponding moving mirror 53X with respect to the corresponding moving mirror 53X
Biaxial single-pass laser beam 5 with an interval D1 in the direction
7X and 58X are irradiated. Similarly, when measuring the amount of bending of the X-axis movable mirror 53X, the Y-axis interferometer main body 54Y can also measure the corresponding moving mirror 53Y from the interferometer main body 54Y so that the yaw amount can be measured.
Biaxial single-pass laser beam 5 with an interval D1 in the direction
7Y and 58Y are irradiated. Therefore, in order to prevent those laser beams from deviating from the movable mirrors 53X and 53Y, the movable mirrors 53X and 53Y and the sample table 52 are required.
Needs to be longer than the originally required movement stroke by a length exceeding the interval D1.

FIG. 11 shows a sample table 52 shown in FIG.
In FIG. 11, the length of the X-axis movable mirror 53X in the Y direction is set to Y1, and the movable mirror 5X is moved.
From the state where the laser beam 57X is irradiated to the end in the −Y direction of 3X, the laser beam 58 is applied to the end of the movable mirror 53X in the + Y direction as shown by a position 52A.
The amount of movement when moving in the −Y direction until X irradiation is performed is defined as Y2. The movement amount Y2 is a movement stroke in the Y direction, and the length Y1 and the movement stroke Y2 have substantially the following relationship.

Y1 = Y2 + D1 (1) Similarly, the length of the movable mirror 53Y needs to be increased by the distance D1 between the biaxial laser beams. Thus, the moving mirror 5
As 3X and 53Y become longer, it is necessary to enlarge the sample stage 52. As a result, the wafer stage 55 shown in FIG.
There is a disadvantage that the weight of the upper movable portion becomes large and control characteristics such as the stepping speed cannot be enhanced. Further, if the sample stage 52 is large, there is a disadvantage that the installation area (footprint) of the wafer stage 55 for driving the sample stage 52 and, consequently, the projection exposure apparatus becomes large. In this regard, if the distance D1 between the laser beams 57X and 58X in the Y direction is reduced, the length Y of the movable mirror 53X can be calculated from the equation (1).
1 can be shortened, but if the interval D1 is shortened, the measurement accuracy of the yawing amount decreases.

In a conventional projection exposure apparatus, FIG.
As shown in (b), in order to measure the pitching amount or the rolling amount of the sample table 52, the moving mirror 53X was irradiated with a two-axis single-pass laser beam at an interval D2 in the Z direction. However, this distance D2 cannot be wider than the thickness of the moving mirror 53X, and
Cannot be made so thick, so that the measurement accuracy of the pitching amount or the rolling amount cannot be increased much. Therefore, conventionally, there is an example in which a measurement device for measuring the inclination of the sample table 52 is provided inside the wafer stage 55.

FIG. 10 shows a conventional projection exposure apparatus.
As shown in (a), a biaxial laser beam 5 with an interval D1
When the bending amount of the movable mirror 53Y is measured from the difference between the measurement values obtained through 7Y and 58Y, if the pitch (period) of the bending of the movable mirror 53Y matches the interval D1, for example, the bending amount is accurately determined. There was an inconvenience that evaluation could not be performed. That is, as shown in FIG. 10C, when the bending pitch of the movable mirror 53Y matches the interval D1, the displacements measured by the laser beams 57Y and 58Y become equal. Further, as shown in FIG. 10D, even if the movable mirror 53Y moves by a half pitch from the state of FIG. 10C, the displacements measured by the laser beams 57Y and 58Y become equal, so that the final position is obtained. The position ΔYM of the reflecting surface of the movable mirror 53Y measured according to X is shown in FIG.
As shown in (e), the bending amount of the movable mirror 53Y is not accurately measured. Further, if the bending pitch of the moving mirror 53Y is smaller than the laser beam interval D1, a phase shift occurs in the bending of the moving mirror 53Y.
A bending amount different from the actual bending amount is measured.

In view of the above, the present invention uses a light beam for measuring a rotation angle in addition to a light beam for measuring a displacement in a predetermined direction of a movable portion that moves together with an object to be positioned. It is a first object to provide a stage device capable of measuring the rotation angle of the movable part. Further, the present invention can measure the displacement of the movable portion by irradiating the movable portion with the positioning target with a light beam, and can reduce the bending amount of the reflection portion of the light beam in the movable portion to a period of a certain small pitch. A second object is to provide a stage device that can accurately detect the amount of bending even when there is a possibility.

Further, the present invention provides a method for measuring a displacement of a movable portion which moves together with a mask or a substrate in a predetermined direction without using a light beam for measuring a rotation angle. A third object is to provide an exposure apparatus capable of measuring a rotation angle such as a yawing amount of a section.

[0015]

A stage apparatus according to the present invention comprises a movable stage (8) on which a positioning object (W) is mounted and moves with the positioning object, and a light beam for measurement on the movable stage. (LX1) and receives the light beam returned from the movable stage and detects the displacement of the movable stage in a predetermined direction.
2X, 17X, 18X, 21X, 22X, 14X),
A light beam detection system (15X) for detecting at least one of a lateral shift amount or a change amount of a deflection angle of the light beam (LX1) returned from the movable stage (8), and An operation system (4) that calculates the rotation angle of the movable stage (8) based on the detection result of the beam detection system
3).

According to the present invention, when the movable stage (8) is irradiated with the light beam (LX1) for detecting displacement of the uniaxial interferometer, the movable stage (8) rotates (inclines). Then, the rotation angle of the movable stage is detected by utilizing the fact that the angle of the reflected light beam changes according to the rotation angle. At this time, when the one-axis interferometer is a single-pass interferometer, the deflection angle (tilt angle) of the reflected light beam corresponds to the rotation angle of the movable stage (8). The rotation angle can be obtained from the deflection angle.

On the other hand, when the one-axis interferometer is a double-pass interferometer in order to increase the measurement resolution, the light beam (LX1) passes between a predetermined optical system and the movable stage (8). Due to the reciprocation, the light beam returned when the movable stage (8) is rotating is shifted laterally according to the rotation angle. Therefore, the rotation angle of the movable stage (8) can be obtained from the lateral shift amount.
In any case, the movable stage (8) can use the light beam for displacement measurement as the light beam for rotation angle measurement.
Can be reduced in size and weight.

The movable stage (8) is detected by detecting the rotation angle of the movable stage (8) via the light beam detection system while moving the movable stage (8) in a direction orthogonal to the predetermined direction. The amount of bending of the reflection portion in the inside can be detected. At this time, the light beam applied to the movable stage (8) is a single light beam in the case of the single-pass system, and is a light beam that reciprocates at a predetermined narrow interval in the case of the double-pass system. Even if there is a pitch periodicity in the amount of bending of the reflecting portion to some extent (that is, in the case of the double-pass method, it is larger than the interval between reciprocating light beams), the amount of bending can be accurately detected.

In this case, the light beam detection system (15X)
As an example, a first light beam detection system (3) for detecting at least one of a lateral shift amount of a light beam returned from the movable stage (8) in a predetermined first direction and a swing angle change amount.
0A) and the amount of lateral shift of the light beam returned from the movable stage (8) in a second direction orthogonal to the first direction;
Or a second light beam detection system (30B) for detecting at least one of the amounts of change in the deflection angle, and the arithmetic system (43) is based on the detection results of the first and second light beam detection systems. The rotation angle of the movable stage (8) around two axes is calculated. This means that the rotation angle of the movable stage (8) around the two axes can be detected based on the lateral shift amount or the deflection angle of the uniaxial light beam in two directions.

The light beam detection system (15X)
As an example, the horizontal shift amount of the light beam returned from the movable stage (8) is detected. In this case, the arithmetic system (43) uses the horizontal shift amount detected by the light beam detection system and the interference thereof. The rotation angle of the movable stage may be calculated from the displacement of the movable stage measured by a meter. For example, if the interferometer is of a double-pass type, the rotation angle of the movable stage (8) is θ (rad), and an optical member (18) that forms a double-pass optical path in the interferometer.
Assuming that the interval from X) to the movable stage (8) is L1, the interval of the predetermined offset is L2, and the lateral shift amount detected by the light beam detection system is ΔY, the lateral shift amount ΔY is substantially expressed by the following equation. expressed.

ΔY = 4 (L1 + L2) θ (2) In this case, the distance L ₀ between the optical member (18X) and the movable stage (8) when the movable stage (8) is at a certain reference position is obtained in advance. Assuming that the displacement of the movable stage (8) measured by the interferometer is ΔL, L1 = L ₀ +
Since there is a relationship of ΔL, the rotation angle θ can be accurately obtained from the equation (2).

Further, based on the lateral shift amount of the light beam detected by the light beam detection system or the change amount of the deflection angle,
An optical path correction system (20X, 23) that corrects the optical path of the reference light beam (LX2) and the measurement light beam (LX1) in the interferometer so that the overlap amount of the light beam increases.
It is desirable to provide X). This means that the optical path of the light beam is corrected so as to cancel out the detected lateral shift amount or deflection angle of the light beam.

The exposure apparatus according to the present invention further comprises a movable stage (8) on which a positioning object formed of a mask (R) or a substrate (W) is placed and two-dimensionally moves together with the positioning object. The stage (8) is irradiated with a measurement light beam (LX1) along a predetermined first direction (X direction), and receives the light beam returned from the movable stage to receive the first light of the movable stage. Interferometer (12X, 17X, 18X, 21) for detecting displacement in the
X, 22X, 14X) and the movable stage (8) are irradiated with a measurement light beam (LY1) along a second direction (Y direction) orthogonal to the first direction and returned from the movable stage. A second interferometer (1) that receives a light beam to be received and detects displacement of the movable stage in the second direction.
2Y, 17Y, 18Y, 21Y, 22Y, 14Y),
And an exposure apparatus that two-dimensionally positions the mask or the substrate by the movable stage (8) and transfers the pattern of the mask onto the substrate.

The exposure apparatus determines at least one of the two-dimensional lateral shift amount and the two-dimensional change amount of the deflection angle of the light beam returned from the movable stage (8) to the first interferometer. The first light beam detection system (15
X) and a second light beam detection system (15) for detecting at least one of a lateral shift amount of the light beam returned from the movable stage (8) to the second interferometer or a change amount of the deflection angle.
Y), and an arithmetic system (43) for calculating a rotation angle of the movable stage (8) around three axes based on the detection results of the first and second light beam detection systems.

According to the exposure apparatus of the present invention, displacement (coordinate)
The light beam emitted from the measurement interferometer to the movable stage (8) is also used for measuring the rotation angle of the movable stage (8). Further, when a single-axis light beam is used, the rotation angle of the movable stage (8) around two axes can be measured.
When a two-axis light beam for measuring the displacement in the direction is used, the rotation angle around each of the two axes can be measured with each light beam, and the rotation angle of one axis among them is common. Therefore, as a result, the rotation angle of the movable stage (8) around three axes including yawing, pitching, and rolling can be measured. In addition, since no light beam other than the displacement measurement light beam is used, the size and weight of the movable stage (8) can be reduced, the controllability of the movable stage (8) such as the moving speed and response speed can be improved, and the exposure can be improved. The installation area (footprint) of the device can be reduced.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. The stage apparatus according to the present invention can be used for any one of an electron beam exposure apparatus, a batch exposure type projection exposure apparatus such as a stepper, and a scanning exposure type projection exposure apparatus such as a step-and-scan method. Hereinafter, an example in which the present invention is applied to a step-and-scan type projection exposure apparatus will be described.

FIG. 1 shows a step-and-scan type projection exposure apparatus according to this embodiment. In FIG. 1, mercury from an illumination optical system 1 including a light source, a fly-eye lens, a field stop, a condenser lens and the like is exposed. Exposure light IL such as i-line of a lamp or excimer laser light illuminates a slit-shaped illumination area on the pattern surface (lower surface) of reticle R.
Under the exposure light IL, an image of the pattern in the illumination area of the reticle R is projected at a predetermined projection magnification β (β
Are 1/4, 1/5, etc.), and are projected and exposed in a slit-shaped exposure area on a wafer W coated with a photoresist. Hereinafter, the Z axis is taken parallel to the optical axis AX of the projection optical system PL, the X axis is taken parallel to the plane of FIG. 1 in a plane perpendicular to the optical axis AX, and the Y axis is taken perpendicular to the plane of FIG. Will be explained.

First, the reticle R is held on the reticle stage 2 by vacuum suction. The reticle stage 2 is continuously moved in the Y direction (scanning direction) by a linear motor while floating on the reticle base 3 via an air bearing. At the same time, the position of the reticle R is finely adjusted in the X direction, the Y direction, and the rotation direction. A laser beam for measurement is emitted from an external laser interferometer 5 to a movable mirror (actually composed of two orthogonally movable mirrors) 4 arranged on the side surface of the reticle stage 2, and is emitted from the laser interferometer 5. The interference light between the reference laser beam and the laser beam reflected from the movable mirror 4 is received by a photoelectric detector in the laser interferometer 5 so that the two-dimensional position of the reticle stage 2 (reticle R) is detected. Is measured. The measurement result is supplied to the reticle stage control system 6, and the reticle stage control system 6 controls the position and the moving speed of the reticle stage 2 under the control of the main control system 7, which controls the overall operation of the apparatus. .

On the other hand, the wafer W is held by vacuum suction on a sample table 8 which also serves as a wafer holder, and the sample table 8 is fixed on a Z tilt stage 9 and a Z tilt stage 9
Is placed on the XYθ stage 10 and the XYθ stage 1
Reference numeral 0 denotes a state in which the sample table 8 (wafer W) is moved and positioned in the X direction, the Y direction (scanning direction), and the rotation direction by a linear motor while floating above the surface plate 11 via an air bearing. The Z tilt stage 9, the XYθ stage 10, and the surface plate 11 constitute a wafer stage. The Z tilt stage 9 controls the position (focus position) of the wafer W in the Z direction and controls the tilt angle (leveling).
I do. Therefore, an optical oblique incidence type multipoint autofocus sensor 44 is arranged on the side surface of the projection optical system PL, and the autofocus sensor 44 precedes the exposure area on the surface of the wafer W and the scanning direction with respect to the exposure area. The focus positions at a plurality of detection points in the pre-reading area to be detected are detected, and the detection results are supplied to the focus control system 45. Under the control of the main control system 7, the focus control system 45 uses the supplied focus position information to focus the surface in the exposure area of the wafer W on the image plane of the projection optical system PL. The control amounts of the focus position and the tilt angle of the tilt stage 9 are calculated in accordance with the position of the wafer W, and based on the control amounts, Z is determined by the auto-focus method and the auto-leveling method.
The operation of the tilt stage 9 is controlled. An example of the mechanism and the operation for focusing is disclosed in detail in Japanese Patent Application Laid-Open No. 6-283403.

The sample stage 8 also serving as a wafer holder of this embodiment is made of quartz or glass ceramic having a low expansion coefficient, and the side surfaces of the sample stage 8 in the -X direction and + Y direction are mirror-finished. Mirror surface 8x and Y for X axis
The mirror surface 8y is for the shaft (see FIG. 2). The mirror surfaces 8x and 8y are reflecting surfaces substantially perpendicular to the X axis and the Y axis, respectively, and are orthogonal to each other. Mirror surfaces 8x and 8
Each of y acts as a moving mirror for an interferometer, and the sample stage 8 of this example can be regarded as also serving as a biaxial moving mirror. Further, an X-axis reference mirror 14X having a reflecting surface substantially parallel to the mirror surface 8x is fixed to the lower side of the projection optical system PL in the −X direction, and the mirror surface 8y is substantially lower to the lower side in the + Y direction. Is fixed to the Y-axis reference mirror 14Y (see FIG. 2) having a reflecting surface parallel to.

In FIG. 1, the laser beam emitted from the X-axis interferometer body 12X is split into
The measurement laser beam (hereinafter, referred to as “measurement beam”) LX1 and the reference laser beam (hereinafter, referred to as “reference beam”) LX which are respectively parallel to the X axis by 3X
The measurement beam LX1 is incident on the X-axis mirror surface 8x of the sample stage 8, and the reference beam LX2 is incident on the X-axis reference mirror 14X. The measurement beam LX1 reciprocates two times between the branching and combining optical system 13X and the mirror surface 8x and returns to the interferometer body 12X. The reference beam LX2 also travels between the branching and combining optical system 13X and the reference mirror 14X. It reciprocates and returns to the interferometer main body 12X (details will be described later). That is, the interferometer body 1
X from the 2X, the branching / combining optical system 13X, and the reference mirror 14X
An axial double-pass laser interferometer is configured, and the interferometer body 12X interpolates and integrates a detection signal obtained by photoelectrically converting interference light of the returning measurement beam LX1 and reference beam LX2. Then, the displacement of the mirror surface 8x in the X direction is obtained with reference to the reference mirror 14X, and the obtained displacement is supplied to the wafer stage control system 43. The wafer stage control system 43 obtains the X coordinate of the sample table 8 by adding a predetermined offset to the displacement.

In this case, the measurement beam LX1 and the reference beam LX2 are, for example, H of 633 nm.
Light beams obtained by frequency-modulating the e-Ne laser beam at predetermined frequencies Δf and −Δf, respectively, are used, and both beams are linearly polarized, for example, and their polarization directions are orthogonal to each other. By splitting and synthesizing both light beams by this method, displacement measurement is performed by the heterodyne interference method. In addition, since the present example is a double-pass method, if the wavelength of the measurement beam LX1 is λ, the displacement of the sample table 8 can be detected with a resolution λ / 4 when electrical interpolation is not performed. This is 分解 能 of the resolution (λ / 2) in the single-pass system. Further, in this example, an electric interpolation process is added to make the final resolution, for example, from λ / 40 (≒ 10 nm) to λ / 400.
(≒ 1 nm).

In this example, a Y-axis double-pass laser interferometer is provided in addition to the X-axis double-pass laser interferometer. FIG. 2 shows a laser interferometer system of a stage on the wafer side of the projection exposure apparatus of FIG. However, in FIG. 2, for the sake of simplicity, some optical members are omitted, and, for example, a prism type beam splitter is represented by a flat beam splitter. In FIG. 2, a laser beam emitted from the Y-axis interferometer main body 12Y is branched into a measurement beam LY1 and a reference beam LY2 parallel to the Y-axis by a branching and combining optical system 13Y, and the measurement beam LY1 is The reference beam LY2 is incident on the Y-axis mirror surface 8y of the sample stage 8, and the Y-axis reference mirror 14
It is incident on Y. Further, the measurement beam LY1 reciprocates two times between the branching and combining optical system 13Y and the mirror surface 8y and returns to the interferometer main body 12Y, and the reference beam LY2 also travels between the branching and combining optical system 13Y and the reference mirror 14Y. Reciprocating interferometer body 1
Return to 2Y. The interferometer body 12Y interpolates and integrates a detection signal obtained by photoelectrically converting the interference light of the returning measurement beam LY1 and reference beam LY2, thereby obtaining the Y of the mirror surface 8y with respect to the reference mirror 14Y. The displacement in the direction is obtained, and the obtained displacement is supplied to the wafer stage control system 43 in FIG. In the wafer stage control system 43,
A Y-coordinate of the sample table 8 is obtained by adding a predetermined offset to the displacement.

As shown in FIG. 2, the optical axis of the measurement beam LX1 on the X-axis (the center line for two reciprocations) is on a straight line parallel to the X-axis and passing through the optical axis AX of the projection optical system PL. Yes, Y
The optical axis of the axis measurement beam LY1 is also parallel to the Y axis and the optical axis AX
On a straight line passing through. Therefore, in this example, the projection optical system PL
Of the optical axis AX, that is, the position of the center (exposure center) of the substantially slit-shaped exposure region can be measured with high accuracy without Abbe error.

Returning to FIG. 1, the wafer stage control system 43
Under the control of the main control system 7, the interferometer main body 12X, 1
Based on the X and Y coordinates of the sample stage 8 measured via 2Y
The movement speed and positioning operation of the XYθ stage 10.
Control. During exposure, the XYθ stage 10 is
The next exposure on the wafer W is performed by the
Is set as the scanning start position. That
Then, reticle R is moved through reticle stage 2 in the + Y direction.
(Or -Y direction)_RIn sync with scanning with
The wafer W is moved through the XYθ stage 10 in the −Y direction (or
+ Y direction) _W(= Β · V_R) (Where β is the projection
By scanning at the projection magnification of the optical system PL),
The pattern image of the reticle R is scanned and exposed in the shot area.
You.

Although not shown, the projection exposure apparatus of this embodiment is provided with an alignment sensor for measuring the position of the reticle R and the position of the wafer W. Based on the measurement result of the alignment sensor, The alignment between the reticle R and each shot area on the wafer W is performed. As described above, in this example, the X coordinate and the Y coordinate of the sample table 8 (wafer W) are measured using a single-axis double-pass laser interferometer in each of the X direction and the Y direction. The positioning of the sample table 8 and the scanning exposure are performed based on the above. However, for example, when the sample stage 8 rotates (yaws) about an axis parallel to the Z axis during the scanning exposure, an overlay error occurs between the reticle R and the wafer W. In this example, since there is a space in the Z direction between the height of the measurement beams LX1 and LY1 and the surface of the wafer W, the sample table 8 is rotated around an axis parallel to the X axis (in the scanning direction). Pitching) or rotation around an axis parallel to the Y axis (rolling in the scanning direction) causes the actual position of the wafer W due to Abbe error and the coordinates measured via the interferometer bodies 12X and 12Y. Is generated. Therefore, in this example,
The yawing amount, the pitching amount, and the rolling amount of the sample table 8 are measured.

In the following, the X axis, the Y axis, and the Z
A mechanism for measuring a rotation angle about an axis parallel to the axis will be described in detail. In this example, since the rotation angle is also measured using the measurement beams LX1 and LY1 of the double-pass type laser interferometer for displacement measurement, the configuration of the laser interferometer is also referred to with reference to FIGS. This will be described in detail. In FIG. 2, a laser beam emitted from the X-axis interferometer main body 12X is incident on a polarization beam splitter 17X in a splitting / combining optical system 13X, and the polarization beam splitter 17X.
The reference beam LX2 of the S-polarized light reflected by the P beam and the P beam transmitted through the polarization beam splitter 17X and traveling parallel to the X axis
It is split into a polarization measurement beam LX1. The latter measurement beam LX1 enters the double pass unit 18X.

FIG. 3A shows the branching / combining optical system 13X shown in FIG.
FIG. 3B is a plan view of the double-pass unit 18X of FIG. 3A. As shown in FIG. 3B, the double-pass unit 18X includes a polarization beam splitter 26, It comprises a quarter-wave plate 27 attached to the exit surface, and a corner cube 28 attached to the side of the polarizing beam splitter 26. The measurement beam LX1 that has entered the double-pass unit 18X once passes through the polarizing beam splitter 26 and the quarter-wave plate 27, and is reflected on the mirror surface 8x of the sample stage 8 in a circularly polarized state. The reflected measurement beam LX1 is a 波長 wavelength plate 2
7, the light is converted into S-polarized light, reflected by the polarizing beam splitter 26, reflected by the corner cube 28, reflected again by the polarizing beam splitter 26, and reflected again by the mirror surface 8x in a circularly polarized state through the quarter-wave plate 27. Is done. The reflected measurement beam LX1 becomes P-polarized light via the quarter-wave plate 27, passes through the polarization beam splitter 26, and enters the beam splitter 19X having a small reflectance.

As shown in FIG. 3A, the measurement beam LX1 reflected by the beam splitter 19X is incident on the stage rotation angle detection system 15X, and the measurement beam LX1 transmitted through the beam splitter 19X is changed in tilt angle. After passing through the parallel plate glass 20X, the light passes through the polarizing beam splitter 17X and returns to the interferometer body 12X. Parallel flat glass 20
X is configured so that it can be tilted by a desired angle around two orthogonal axes by a driving device 23X.
The operation of X is controlled by the wafer stage control system 43 of FIG. The inclination angle of the parallel plate glass 20X is controlled so that the amount of overlap between the measurement beam LX1 and the reference beam LX2 is maximized.

Returning to FIG. 2, the polarization beam splitter 17X
Is reflected by a mirror (actually a reflecting prism) 21X in a direction parallel to the X-axis, and then passes through a half-wave plate for rotating a polarization direction (not shown) by 90 °. Becomes P-polarized light through the double-pass unit 22X
Incident on. This double-pass unit 22X is configured as shown in FIG.
It has the same configuration as the double-pass unit 18X of (b),
After the reference beam LX2 makes two reciprocations between the double-pass unit 22X and the reference mirror 14X, the double-pass unit 2X
Pass through 2X. Although not shown in FIG. 2 for simplicity, in practice, as shown in FIG. 3A, a beam splitter 24X having a small reflectance is arranged on the exit surface on the −X direction side of the double pass unit 22X. The reference beam LX2 reflected by the beam splitter 24X is incident on the reference rotation angle detection system 16X, and the reference beam LX2 transmitted through the beam splitter 24X is converted into S-polarized light via a half-wave plate (not shown). After being reflected by the mirror 21X, it is reflected by the polarization beam splitter 17X,
Return to X.

In this case, in FIG. 2, when the sample stage 8 is rotated by an angle (yaw amount) θZ around, for example, an axis parallel to the Z axis (for example, the optical axis AX), the measurement first reflected on the mirror surface 8x The use beam LX1 is reflected while being inclined in the Y direction. However, the tilt angle (shake angle) is converted into a lateral shift amount by making two reciprocations with the double pass unit 18X.

FIG. 4 is an explanatory diagram showing that the rotation angle of the mirror surface 8x causes a lateral shift of the measurement beam LX1 in the double pass unit 18X.
Optical axis of measurement beam LX1 and double pass unit 18X
From the intersection with the reflection surface of the polarizing beam splitter 26 in
The distance to the mirror surface 8x is L1, and the distance to the vertex of the corner cube 28 is L2. The distance L1 is the X of the sample table 8.
In the following, the distance L1 is represented by L1 (X)
And When the mirror surface 8x is not rotating, the measurement beam LX1 is assumed to make two reciprocations between the double pass unit 18X and the mirror surface 8x along the optical path of the solid line, and the mirror surface 8x is parallel to the Z axis. When rotated around the axis by an angle θ (rad), the direction of the measurement beam LX1 reflected for the first time is inclined by the angle θ as shown by the dotted optical path Q3. However, in the corner cube 28, since the incident light beam and the outgoing light beam are parallel, the measuring beam LX1 thus inclined is inclined by the same angle when reflected from the double pass unit 18X to the mirror surface 8x. . Therefore, the direction of the measurement beam LX1 reflected from the mirror surface 8x for the second time is parallel to that at the time of incidence as shown by the dotted optical path P3, and is in the Y direction as compared with the case where the mirror surface 8x is not rotating. Are shifted laterally by ΔY. The measurement beam LX1 is a double-pass unit 1
Since there are two reciprocations between 8X and the mirror surface 8x, the lateral shift amount ΔY is approximately as follows.

ΔY = 4 (L1 (X) + L2) θ (3) Similarly, when the mirror surface 8x is rotated by an angle θ (the amount of rolling in the Y direction) about an axis parallel to the Y axis. Also, the measurement beam LX1 returned two times back and forth between the double-pass unit 18X and the mirror surface 8x is laterally shifted in the Z direction by the same amount as in the expression (3).

Returning to FIG. 2, when a yawing amount θZ is generated on the mirror surface 8x and the measuring beam LX1 reflected on the mirror surface 8x is inclined in the Y direction as shown by the optical path Q3,
As described above, after passing through the double pass unit 18X, the position of the measurement beam LX1 reflected by the beam splitter 19X and incident on the stage rotation angle detection system 15X shifts in the Y direction as indicated by the optical path P3. Similarly, when a rolling amount θY is generated on the mirror surface 8x and the measurement beam LX1 reflected on the mirror surface 8x is inclined in the Z direction as shown by the optical path Q2, the double-pass unit 1
Measurement beam LX that passes through 8X, is reflected by beam splitter 19X, and enters stage rotation angle detection system 15X
The position of 1 is shifted laterally in the X direction as indicated by the optical path P2.

However, due to the fluctuation of the laser light source,
Even if a horizontal shift and a tilt of the laser beam itself emitted from the interferometer body 12X occur, the stage rotation angle detection system 1
The position of the measurement beam LX1 incident on 5X is shifted laterally. Therefore, in order to correct the lateral shift caused by the lateral shift and the inclination of the laser beam itself, the stage rotation angle detection system 15X uses the lateral shift amount ΔX1 in the X direction with respect to the initial position of the incident measurement beam LX1; In addition to the lateral shift amount ΔY1 in the Y direction, the inclination angle Δφ in the X direction with respect to the initial inclination angle (deflection angle) of the measurement beam LX1.
X1 (rad, the same applies hereinafter), and the inclination angle Δφ in the Y direction
Y1 is measured, and the measurement result is supplied to the wafer stage control system 43 in FIG. The configuration of the stage rotation angle detection system 15X will be described later.

Further, in FIG. 2, from the apparent lateral shift amounts .DELTA.X1 and .DELTA.Y1 of the measuring beam LX1 measured by the stage rotation angle detecting system 15X, the lateral shift amount caused by the angle change or lateral displacement of the laser beam itself is obtained. In order to separate the reference rotation angle detection system 1 as shown in FIG.
6X, the two-dimensional lateral shift amounts ΔX2, ΔY2 of the reference beam LX2 and the two-dimensional inclination angles ΔφX2, Δ
φY2 is measured, and the measurement result is supplied to the wafer stage control system 43 in FIG. In the wafer stage control system 43, as an example, as described below, the accurate lateral shift amount Δ of the reference beam LX2 after removing the influence of the inclination of the laser beam.
X _R and ΔY _R are obtained. That is, when the distance to the detection surface of the lateral shift amount in interferometer laser beam reference rotation angle within the detection system 16X from the injection point in the 12X and L _0, becomes similar to the following.

ΔX_R= ΔX2-L₀・ ΔφX2 (4A) ΔY_R= ΔY2-L₀.DELTA..phi.Y2 (4B) Next, the wafer stage control system 43 outputs the measurement beam LX.
From the apparent lateral shift amounts ΔX1 and ΔY1 of No. 1 for reference
Accurate lateral shift amount ΔX of beam LX2_R, ΔY _R,as well as
The amount of lateral shift caused by the inclination of measurement beam LX1 is
Pull, lateral shift caused only by the rotation angle of mirror surface 8x
Quantity ΔX_M, ΔY_MAsk for. At this time, the interferometer body 12
Stage rotation angle detection system from laser beam emission point in X
The distance to the detection plane of the lateral shift amount within 15X is
When expressed as a function L (X) of the X coordinate of 8, the measurement beam LX
X direction, Y direction caused by the inclination angles ΔφX1, ΔφY1 of 1
The lateral shift amount in the direction is approximately L (X) · ΔφX1,
And L (X) · ΔφY1. Therefore, the wafer stay
The control system 43 controls the mirror surface 8x of the measurement beam LX1.
Lateral shift amount ΔX caused only by rotation angle_M, ΔY_MIt
Each is calculated by the following equation.

The measurement detected by _{ΔX M = ΔX1-ΔX R -L} (X) · ΔφX1 (5A) ΔY M = ΔY1-ΔY R -L (X) · ΔφY1 (5B) In addition, the stage rotation angle detecting system 15X Since the inclination angles ΔφX1 and ΔφY1 of the reference beam LX1 are in principle equal to the inclination angles ΔφX2 and ΔφY2 of the reference beam LX2 detected by the reference rotation angle detection system 16X, respectively.
The inclination angles ΔφX1 and Δφ in the equations (5A) and (5B)
Y1 may be replaced with the inclination angles ΔφX2, ΔφY2.
In this case, the stage rotation angle detection system 15X does not need to have a function of detecting the deflection angle of the measurement beam LX1. In addition, a reference rotation angle detection system is provided for both, and the difference between the detection results is obtained, so that the change in orthogonality between the mirror surfaces 8x and 8y can be examined.

Also, as shown in FIG.
Distance L from the optical axis of X1 to the vertex of corner cube 28
2 is obtained and stored in advance, and the distance L1 from the intersection of the optical axis and the reflection surface of the polarization beam splitter 26 to the mirror surface 8x is determined by the X coordinate of the sample table 8 measured by the interferometer body 12X and the predetermined value. It can be obtained as the sum of the offsets. From these, the wafer stage control system 43 satisfies (3)
The rolling amount θY is calculated by substituting the lateral shift amount ΔX _M of the expression (5A) into the lateral shift amount ΔY of the expression, and the lateral shift amount ΔY of the expression (5B) is substituted for the lateral shift amount ΔY of the expression (3). By substituting _M , the yawing amount θZ
Is calculated.

As shown in FIG. 2, the Y-axis branching and combining optical system 13Y also has an X-axis branching and combining optical system 13X.
Symmetrically, the laser beam emitted from the interferometer body 12Y is branched by the polarization beam splitter 17Y into a measurement beam LY1 and a reference beam LY2 which travel in parallel with the Y axis, and the measurement beam LY1 is divided into a double-pass unit 18Y.
After two reciprocations between the sample table 8 and the Y-axis mirror surface 8y, the beam returns to the interferometer body 12Y via the beam splitter 19Y, the parallel flat glass 20Y having a variable inclination angle, and the polarization beam splitter 17Y. The measurement beam LY1 reflected by the beam splitter 19Y is incident on the Y-axis stage rotation angle detection system 15Y, where the lateral shift amount and the tilt angle (shake angle) are detected. On the other hand, the reference beam LY2
Is reflected by the mirror 21Y to form the double-pass unit 2
After two reciprocations between 2Y and the Y-axis reference mirror 14Y, the light returns to the interferometer main body 12Y via the mirror 21Y and the polarization beam splitter 17Y. In this case as well, although not shown, a beam splitter is disposed between the double-pass unit 22Y and the mirror 21Y, and the reference beam LY2 reflected by the beam splitter is used as a reference rotation angle detection system in FIG. The incident light enters the Y-axis reference rotation angle detection system having the same configuration as that of 16X, and the lateral shift amount and the inclination angle are also detected here.

At this time, in FIG. 2, when the sample table 8 is pitched in the Y direction and rotated by an angle (pitching amount) θX about an axis parallel to the X axis, the mirror surface 8 is rotated.
The measurement beam LY1 reflected for the first time at y is inclined in the Z direction as shown by the dotted optical path Q5. Then, the stage rotation angle detection system 15 passes through the double pass unit 18Y.
The position of the measurement beam LY1 incident on Y shifts laterally in the Y direction as indicated by the optical path P5. Also in this case, the lateral shift amount of the measurement beam LY1 excluding the influence of the lateral shift and the tilt of the laser beam itself is calculated using the Y coordinate of the mirror surface 8y and the pitching amount θX, as in the equation (3). Therefore, the wafer stage control system 43 calculates the pitching amount θX from the lateral shift amount.

When the sample stage 8 is rotated by an angle (yaw amount) θZ about an axis parallel to the Z-axis, the measurement beam LY1 is also used by the Y-axis stage rotation angle detection system 15Y.
Causes a lateral shift in the X direction, the wafer stage control system 4 based on the lateral shift amount of the measurement beam LY1 in the X direction detected by the Y-axis stage rotation angle detection system 15Y.
3 calculates the yawing amount θZ. Normally, the yawing amount θZ calculated based on the lateral shift amount of the measurement beam LX1 in the X-axis stage rotation angle detection system 15X is used. For example, by moving the sample table 8 in the Y direction, In the case of measuring the amount of bending of the X-axis mirror surface 8x, the yawing amount θZ calculated based on the amount of lateral shift of the measurement beam LY1 in the Y-axis stage rotation angle detection system 15Y is used. .

The X-axis interferometer body 12X and the Y-axis interferometer body 12Y may use a laser beam from a common laser light source. In this case, 2
Since the lateral shift amounts and the inclination angles of the laser beams themselves emitted from the two interferometer bodies 12X and 12Y are common,
For example, the reference beam LY is applied to the Y-axis branching and combining optical system 13Y.
It is not necessary to provide a reference rotation angle detection system for detecting the lateral shift amount and the inclination angle of 2, and the configuration of the optical system is simplified.

As described above, in this embodiment, the two-dimensional lateral shift amount and the inclination angle of the incident light beam are detected by the stage rotation angle detection systems 15X and 15Y and the reference rotation angle detection system 16X. As a simple method for detecting the lateral shift amount of the light beam, for example, a four-division light receiving element in which the light receiving surface is divided into four, or a photoelectric element capable of detecting the two-dimensional center of gravity of the light quantity distribution of the incident light beam is used. Detector or CC
There is a method using an image pickup device made of D or the like. Similarly, in order to detect the tilt angle of the light beam, such a four-division light receiving element, a photoelectric detector, or an imaging element such as a CCD is used on the optical Fourier transform plane (pupil plane) of the lens system. Then, the lateral shift amount of the light beam may be measured. However,
In this example, in order to detect the lateral shift amount and the tilt angle of the light beam with higher accuracy, the two-beam laser interference method is used as follows. Typically, the X-axis stage rotation angle detection system 15
The configuration of X will be described with reference to FIG.

FIG. 5 shows the configuration of the stage rotation angle detection system 15X. In FIG. 5, the incident linearly polarized measurement beam LX1 is split into two by the half mirror 29A, and one of the light beams is the first beam. Lateral shift tilt angle detection system 30
A, and the other light beam enters the second lateral shift tilt angle detection system 30B. The latter lateral shift inclination angle detection system 30
B is obtained by rotating the former lateral shift inclination angle detection system 30A by 90 °. In the horizontal shift tilt angle detection system 30A, the incident light beam becomes circularly polarized light by the 波長 wavelength plate 31A, and is split into two light beams by the half mirror 29B.

The light beam transmitted through the half mirror 29B (also referred to as the “measurement beam LX1”) is spread by the birefringent prism 40 almost symmetrically so that the first light beam b1 of P polarization and the second light beam of S polarization are spread. b2. The first light beam b1 and the second light beam b2 are returned to circularly polarized light by the １ ／ wavelength plate 31B, and then become light beams parallel to each other via the first relay lens 41A. Then, the first light beam b1 is incident on the acousto-optic element 33B and is frequency-modulated at a predetermined frequency F, the second light beam b2, and the frequency-modulated first light beam b
1 is condensed via a second relay lens 41B onto a diffraction grating 35B having a predetermined pitch at a predetermined intersection angle. Due to the frequency modulation, interference fringes flowing in the pitch direction are formed on the diffraction grating 35B. In this example, the pitch of the diffraction grating 35B is set to be twice the pitch of the interference fringes. Note that, in order to lower the beat frequency, the first light flux b
The first and second luminous fluxes b2 may be frequency-modulated by acousto-optic devices whose driving frequencies are different from each other by a predetermined amount.

As a result, the + 1st-order diffracted light of the first light beam b1 and the -1st-order diffracted light of the second light beam b2 by the diffraction grating 35B are emitted from the diffraction grating 35B in parallel as interference light b3. The interference light b3 is beat light whose intensity changes at the frequency F, and other zero-order light and the like are also emitted from the diffraction grating 35B. These diffracted lights enter the pupil filter 37B via the condenser lens 36B, and only the interference light b3 composed of the ± 1st-order diffracted light passes through the aperture of the pupil filter 37B and is received by the photoelectric detector 38B. Interference light b at 38B
A beat signal of frequency F obtained by photoelectrically converting 3 is supplied to a signal processing system 39. The signal processing system 39 also incorporates a drive circuit for the acousto-optic device 33B. The signal processing system 39 includes, for example, a drive signal having a frequency F of the drive circuit and a beat signal having a frequency F supplied from the photoelectric detector 38B. A phase difference REF1 (rad) from the signal is obtained.

In this case, the incident position of the measurement beam LX1 in the birefringent prism 40 and the condensing positions of the two light beams b1 and b2 on the diffraction grating 35B are determined by the relay lenses 41A and 41.
Conjugate with respect to B. Accordingly, as shown in FIG. 6A, when the incident position of the measurement beam LX1 in the birefringent prism 40 is shifted from the position indicated by the solid line to the position indicated by the dotted line, the two light beams b1 and b2 on the diffraction grating 35B are shifted. The focusing position is shifted laterally from the position B1 to the position B2, and the above-described phase difference REF is obtained.
1 changes. In this case, the pitch of the diffraction grating 35B is P
If it is set to 1, the measurement beam LX is calculated using a predetermined coefficient k1.
The lateral shift amount of 1 (this is referred to as ΔX1) can be expressed as follows. Therefore, the signal processing system 39 converts the lateral shift amount ΔX1 obtained from the following equation into the wafer stage control system 43.
To supply.

ΔX1 = k1 · P1 · REF1 / (2π) (6) In FIG. 5, the light beam reflected by the half mirror 29B (also referred to as the “measurement beam LX1”) is transmitted to the half mirror 29C and The light is split into a first light flux a1 and a second light flux a2 that travel in parallel at a predetermined interval by the mirror 32. Then, the first light beam a1 is incident on the fθ lens 34, and the second light beam a2 is incident on the fθ lens 34 after being subjected to frequency modulation of the frequency F by the acousto-optic element 33A,
The two light beams a1 and a2 that have passed through the fθ lens 34 are condensed on a diffraction grating 35A having a predetermined pitch at a predetermined intersection angle. Due to the frequency modulation, interference fringes flowing in the pitch direction are formed on the diffraction grating 35A, and the pitch of the diffraction grating 35A is set to be twice the pitch of the interference fringes.

As a result, the + 1st-order diffracted light of the first light beam a1 and the -1st-order diffracted light of the second light beam a2 by the diffraction grating 35A are emitted from the diffraction grating 35A in parallel as interference light a3. The interference light a3 is beat light whose intensity changes at the frequency F. Various diffracted lights emitted from the diffraction grating 35A are incident on the pupil filter 37A via the condenser lens 36A, and are formed as ± 1st-order diffracted light. Only a3 passes through the aperture of the pupil filter 37A and is received by the photoelectric detector 38A.
A beat signal of a frequency F obtained by photoelectrically converting the interference light a3 by the photoelectric detector 38A is supplied to the signal processing system 39.
The signal processing system 39 also incorporates a drive circuit for the acousto-optical element 33A. The signal processing system 39 includes, as an example, a drive signal having a frequency F of the drive circuit and a drive signal having a frequency F supplied from the photoelectric detector 38A. Phase difference REF2 with beat signal
(Rad).

In this case, the arrangement plane of the diffraction grating 35A is substantially an optical Fourier transform plane (pupil plane) by the fθ lens 34 with respect to the division plane of the half mirror 29C which is the incident position of the measurement beam LX1. , Half mirror 29
The inclination angle of the measurement beam LX1 incident on C is converted into a lateral shift amount in the diffraction grating 35A. Therefore, FIG.
As shown in (b), when the inclination angle of the measurement beam LX1 with respect to the half mirror 29C changes from the optical path indicated by the solid line to the optical path indicated by the dotted line, the two light beams a1, a on the diffraction grating 35A
The focus position of No. 2 is shifted laterally from the position A1 to A2, and the above-mentioned phase difference REF2 changes. Assuming that the pitch of the diffraction grating 35A is P2, the measurement beam L is determined using a predetermined coefficient k2.
The tilt angle of X1 (this is ΔφX1) can be expressed as follows. Therefore, the signal processing system 39 supplies the tilt angle ΔφX1 obtained by the following equation to the wafer stage control system 43.

ΔφX1 = k2 · P2 · REF2 / (2π) (7) In the stage rotation angle detection system 15X, the other light beam split by the half mirror 29A is sent to the second horizontal shift inclination angle detection system 30B. Here, the lateral shift amount detected by the lateral shift inclination angle detection system 30A, the lateral shift amount ΔY1 of the measurement beam LX1 in the direction orthogonal to the inclination angle, and the inclination angle ΔφY1 are detected. It is supplied to the stage control system 43. Similarly, in the Y-axis stage rotation angle detection system 15Y in FIG. 2 and the reference rotation angle detection system 16X in FIG. Lateral shift amount,
And a tilt angle (shake angle) are detected.

As described above, in the present embodiment, the yawing amount θZ of the sample table 8 is utilized by using the measurement beams LX1 and LX2 for measuring the displacement applied to the sample table 8 from the interferometer bodies 12X and 12Y of FIG. , Pitching amount θX, and rolling amount θY are constantly measured. In this case, the wafer stage control system 43 rotates the sample stage 8 via the XYθ stage 10 of the wafer stage in FIG. 1 so as to cancel the yawing amount θZ during the scanning exposure. Thereby, high overlay accuracy between the reticle R and the wafer W can be obtained.

When the pitching amount θX and the rolling amount θY of the sample table 8 are generated, the wafer W
The distance in the Z direction between the surface of the laser beam and the measurement beams LX1 and LY1 in the Z direction is δZ, and δZ · θY in the X direction and δZ · θ in the Y direction.
Abbe error of X occurs. Therefore, the wafer stage control system 43 controls the XY to cancel those Abbe errors.
The position of the wafer W in the X and Y directions is corrected via the θ stage 10. Thus, highly accurate positioning of the wafer W is performed. In this case, for example, as shown in FIG.
In this example, since the tilt angle of the sample table 8 is measured using the uniaxial measurement beams LX1 and LY1, the width of the mirror surface 8x of the sample table 8 in the X direction and the width of the mirror surface 8y in the Y direction are measured. The entire width is almost a movement stroke.

In this example, since the double-pass system is used, the measurement beams LX1 and LY1 make two round trips to the corresponding mirror surfaces, respectively. It is considerably narrower than the distance between two-axis single-pass laser beams as in the conventional example.
The spread of the measurement beams LX1 and LY1 is negligible. Therefore, if it is sufficient to obtain a moving stroke equivalent to that of the conventional example, the moving mirror, that is, the mirror surfaces 8x and 8y of the sample stage 8 in this example can be reduced, and the sample stage 8 can be reduced in size and weight. Therefore, the controllability such as the moving speed of the sample table 8 can be improved, and the footprint of the projection exposure apparatus can be reduced.

Conventionally, for example, when the width of the movable mirror in the Z direction is narrow and there is no room for measuring the pitching amount and the rolling amount of the sample table by irradiating a biaxial measurement beam in the Z direction, FIG. A tilt angle measuring mechanism (such as a digital micrometer) is provided in a stage corresponding to the Z tilt stage 9 to indirectly measure the tilt angle of the sample table and correct the position of the wafer W based on the tilt angle. Something like that was being done. In this method, the mechanism of the stage becomes complicated, and the processing of the measurement result of the inclination angle is complicated. On the other hand, in this example, since the tilt angle of the sample table 8 is directly measured, the position of the wafer W can be controlled with high accuracy while simplifying the stage mechanism. Further, even when the thickness of the mirror surfaces 8x and 8y as the movable mirror is small, the pitching amount and the rolling amount can be measured with high accuracy.

Further, in parallel with such an operation, the wafer W detected through the auto focus sensor 44 of FIG.
By driving the Z-tilt stage 9 based on the information on the focus position, the surface of the wafer W is focused on the image plane of the projection optical system PL by the auto-focus method and the auto-leveling method. At this time, since the operation of the Z tilt stage 9 can be performed based only on the measurement result of the auto focus sensor 44, higher accuracy,
In addition, focusing can be performed at a higher tracking speed.

Next, an example of the operation of the projection exposure apparatus of this embodiment when measuring the amount of bending of the movable mirror, ie, the mirror surfaces 8x and 8y of the sample table 8, will be described with reference to FIG. For example, when measuring the amount of bending of the mirror surface 8x as an X-axis movable mirror, by driving the XYθ stage 10 of FIG. 1, the X-axis of the sample table 8 measured by the X-axis interferometer body 12X is measured. The sample table 8 is moved at predetermined intervals in the Y direction while the coordinates are maintained at a constant value and the yawing amount θZ of the sample table 8 measured by the Y-axis stage rotation angle detection system 15Y is set to, for example, 0. Let me do it. At each measurement point in the Y direction, the yawing amount of the sample table 8 via the X-axis stage rotation angle detection system 15X, that is, in this case, the inclination angle θ _i (i = 1, 2,...) Of the mirror surface 8x It was measured, by multiplying the interval [delta] Y of the movement in the Y direction to the inclination angle theta _i, to calculate the amount of displacement [delta] Y · theta _i of the mirror surface 8x for the next measurement point from the measurement points, the amount of displacement [delta] Y The amount of bending of the reflection surface of the mirror surface 8x is obtained by integrating θ _i .

Similarly, when measuring the amount of bending of the Y-axis mirror surface 8y, the X-axis stage rotation angle detection system 15X
In the state where the yawing amount θZ of the mirror surface 8x measured in the step is set to 0, the sample stage 8 is moved in the X direction, and Y is measured at each measurement point.
Mirror surface 8y via shaft stage rotation angle detection system 15Y
May be measured. In this case, the measurement beams LX1 and LY1 of this example are of the double-pass type,
Since the interval between the optical paths of the reciprocating movements is considerably narrower than the bending pitch of the ordinary movable mirror, the amount of the bending can be measured with high accuracy regardless of the periodicity of the bending of the mirror surface 8x.

Next, another embodiment of the present invention will be described with reference to FIGS. While the embodiment of FIG. 2 uses a double-pass laser interferometer, the present embodiment uses a single-pass laser interferometer. In FIG. 7, a portion corresponding to FIG. Are denoted by the same reference numerals, and detailed description thereof is omitted. FIG. 7 shows a laser interferometer system of a stage on the wafer side of the projection exposure apparatus of this embodiment. In FIG.
The laser beam emitted from 2X is split into an X-axis measurement beam LX1 and a reference beam LX2 by a polarization beam splitter 17X, and the measurement beam LX1 is passed through a beam splitter 19X to a mirror surface 8x of the sample table 8.
Is irradiated. Then, the measurement beam LX1 reflected by the mirror surface 8x returns to the interferometer main body 42X via the beam splitter 19X and the polarization beam splitter 17X, and the measurement beam LX1 reflected by the beam splitter 19X is converted to a stage rotation angle detection system. It is incident on 15X.

The reference beam LX2 is transmitted to the mirror 21
After being reflected by X and being reflected by the reference mirror 14X on the side of the projection optical system PL, the beam returns to the interferometer main body 42X again via the mirror 21X and the polarization beam splitter 17X, and is returned by the interferometer main body 42X. The interference light of the LX1 and the reference beam LX2 is photoelectrically converted, and the displacement of the mirror surface 8x in the X direction with respect to the reference mirror 14X is measured. Although not shown, a beam splitter 24X as shown in FIG. 3A is also arranged between the reference mirror 14X and the mirror 21X, and the reference beam LX2 reflected by the beam splitter 24X is rotated by the reference rotation angle. It is incident on the detection system 16X.

In FIG. 7, the Y-axis laser interferometer is also symmetrical to the X-axis laser interferometer, and includes an interferometer main body 42Y, a polarization beam splitter 17Y, a beam splitter 19Y, a mirror 21Y, and a reference mirror 14Y. Total body 4
Measurement beam LY1 and reference beam L returned to 2Y
Based on Y2, the displacement of the mirror surface 8y of the sample table 8 in the Y direction with respect to the reference mirror 14Y is measured. The measurement beam LY1 reflected by the beam splitter 19Y is received by the stage rotation angle detection system 15Y.

In this example, when the sample stage 8 rotates by an angle (yaw amount) θZ about an axis parallel to the Z-axis, the measurement beam LX1 incident on the mirror surface 8x is represented by a dotted optical path Q3. Measurement beam LX that is reflected while being inclined in the Y direction and enters the stage rotation angle detection system 15X
1 also inclines in the Y direction at the same angle. In addition, Y
When rotation of an angle (rolling amount) θY occurs around an axis parallel to the axis, the measurement beam L incident on the mirror surface 8x
X1 is reflected while being inclined in the Z direction as indicated by a dotted optical path Q2, and the measurement beam LX1 incident on the stage rotation angle detection system 15X is also inclined in the X direction at the same angle. Similarly,
When rotation of the sample table 8 by an angle (pitching amount) θX occurs around an axis parallel to the X axis, the measurement beam LY1 incident on the mirror surface 8y is inclined in the Z direction as shown by the dotted optical path Q5. The measurement beam LY1 reflected and incident on the stage rotation angle detection system 15Y is also inclined in the Y direction at the same angle. Therefore, the stage rotation angle detection system 15X, 1
In 5Y, the measuring beams LX1 and LY1 that are incident respectively.
Are detected in the X and Y directions.

Further, in this example, the interferometer bodies 42X, 42
Assuming that a common laser light source is used for Y, FIG. 3 (a) disposed between the mirror 21X and the reference mirror 14X in order to measure the change in the tilt angle of the laser beam by the laser light source. The reference rotation angle detection system 16X detects the inclination angles of the reference beam LX2 in the X and Y directions. Then, the stage rotation angle detection system 15X, 1
By subtracting the inclination angle of the reference beam LX2 measured by the reference rotation angle detection system 16X in the X direction and Y direction from the inclination angle of the measurement beam measured in 5Y in the X direction and Y direction, a single angle is obtained. The yawing amount θZ, the rolling amount θY, and the pitching amount θX of the sample table 8 can be accurately detected by using the measurement beams LX1 and LY1 of the laser interferometer of the path.

In such a single-pass system, the width of the mirror surfaces 8x and 8y becomes the moving stroke of the sample stage 8 almost as it is. That is, as shown in FIG. 8, the width of the mirror surface 8x of the sample stage 8 in the Y direction is Y3, and
From the state in which the measurement beam LX1 is irradiated to the end in the Y direction, the sample table 8 is moved from the state where the measurement beam LX1 is irradiated to the end in the + Y direction of the mirror surface 8x as shown by the two-dot chain line. Assuming that the moving amount at the time of moving is Y2, the moving amount Y2 is a moving stroke in the Y direction. Since the width of the measurement beam LX1 in the Y direction is negligible in the single-pass method, the movement stroke Y
2 is substantially equal to the width Y3 of the mirror surface 8x. Therefore,
If the same movement stroke as that of the conventional example is sufficient, the sample table 8
With the function of detecting the rotation angle around the axis, the sample table 8
Can be significantly reduced in size and weight as compared with the conventional example.

In the above-described embodiment, the present invention is applied to the stage on the wafer side. However, in order to detect the inclination of the reticle stage 2 on which the reticle R shown in FIG. May be applied. For example, by applying the present invention and detecting the yaw amount of the reticle stage 2 using a laser beam for displacement measurement,
The reticle stage 2 can be reduced in size and weight.

The present invention can also be applied to a stage for positioning a wafer or the like in an electron beam exposure apparatus or the like. As described above, the present invention is not limited to the above-described embodiment, and can take various configurations without departing from the gist of the present invention.

[0078]

According to the stage apparatus of the present invention, the rotation angle of the movable stage is calculated from the lateral shift amount or the deflection angle of the displacement detection light beam returned from the movable stage. There is an advantage that the rotation angle of the movable stage (movable part) can be measured without using a dedicated light beam for measuring the rotation angle. Therefore, since the movable stage can be reduced in size and weight, the controllability of the movable stage can be improved, and the installation area (footprint) of the device including the movable stage can be reduced.

Further, by detecting the inclination angle of the reflecting portion of the movable stage by using the light beam for detecting the displacement, even if the bending amount of the reflecting portion has a periodicity of a somewhat small pitch. This has the advantage that the amount of bending can be accurately detected. The light beam detection system includes a first light beam detection system that detects at least one of a lateral shift amount of the light beam returned from the movable stage in a predetermined first direction and a change amount of a swing angle, and A second light beam detection system for detecting at least one of a lateral shift amount of a light beam returned from the movable stage in a second direction orthogonal to the first direction, or a change amount of a deflection angle, When calculating the rotation angle of the movable stage around the two axes from the detection results of the first and second light beam detection systems, the arithmetic system uses the one-axis light beam for displacement detection to calculate the rotation angle. There is the advantage that the angle of rotation about the axis can be detected.

The light beam detection system detects the lateral shift amount of the light beam returned from the movable stage, and the operation system
When calculating the rotation angle of the movable stage from the amount of lateral shift detected by the light beam detection system and the displacement of the movable stage measured by the interferometer, for example, when a double-pass interferometer is used The rotation angle of the movable stage can be easily calculated.

Further, the amount of overlap between the reference light beam and the measurement light beam in the interferometer is increased based on the lateral shift amount or the change amount of the deflection angle of the light beam detected by the light beam detection system. When an optical path correction system for correcting the optical path of the light beam is provided, displacement measurement can always be performed at a high SN ratio, and measurement accuracy is improved. Further, according to the exposure apparatus of the present invention, by using a biaxial light beam for displacement measurement, a movable stage on which a mask or a substrate is placed without particularly using a light beam for measuring a rotation angle. The rotation angles of the (movable part) around three axes, that is, the angles of yawing, rolling, and pitching can be measured.
Therefore, when the moving stroke can be the same as that of the conventional example, the movable stage can be reduced in size and weight as compared with the conventional example in addition to the function of measuring the rotation angle, and as a result, the footprint of the exposure apparatus can be reduced. .

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a projection exposure apparatus used in an example of an embodiment of the present invention.

FIG. 2 is a partially simplified perspective view showing a laser interferometer system of a stage on a wafer side of the projection exposure apparatus of FIG. 1;

FIG. 3A is a front view showing the configuration of a branching / combining optical system 13X of FIG. 2 and members around it, and FIG. 3B is a front view of FIG.
FIG. 5 is a plan view showing a double pass unit 18X and the like.

FIG. 4 is an explanatory diagram showing that the inclination of the mirror surface 8x causes a lateral shift of the measurement beam LX1 by the double-pass interference method.

FIG. 5 is a configuration diagram showing a stage rotation angle detection system 15X in FIG. 2;

6A is a diagram illustrating a state in which a focal point of two light beams moves on a diffraction grating 35B due to a lateral shift of the measurement beam LX1 in FIG. 5, and FIG. 6B is a diagram illustrating the measurement beam LX1 in FIG. FIG. 8 is a diagram showing a state in which the focal points of two light beams move on the diffraction grating 35A due to the inclination of.

FIG. 7 is a partially simplified perspective view showing a laser interferometer system of a stage on a wafer side according to another example of the embodiment of the present invention.

8 is an explanatory diagram of a movement stroke in the Y direction in FIG. 7;

FIG. 9A is a plan view showing a stage on a wafer side of a conventional projection exposure apparatus, and FIG. 9B is a front view thereof.

FIG. 10 is a diagram for explaining a conventional method for measuring the amount of bending of a movable mirror for a laser interferometer, and its problems.

11 is an explanatory diagram of a movement stroke in the Y direction in the conventional example of FIG. 9;

[Explanation of symbols]

 R Reticle PL Projection optical system W Wafer 2 Reticle stage 7 Main control system 8 Sample stage 8x, 8y Mirror surface 9 Z tilt stage 10 XYθ stage 11 Surface plate 12X, 12Y Interferometer main body 13X, 13Y Branch combining optical system 14X, 14Y See Mirror 15X, 15Y Stage rotation angle detection system 16X Reference rotation angle detection system 18X, 18Y, 22X, 22Y Double pass unit 20X, 20Y Parallel flat glass LX1, LY1 Measurement beam LX2, LY2 Reference beam 30A, 30B Lateral shift tilt angle detection System 43 Wafer stage control system

Claims (5)

[Claims] A movable stage on which a positioning target is placed and moved together with the positioning target; and a light beam for measurement is irradiated on the movable stage, and a light beam returned from the movable stage is received to receive the light beam. An interferometer for detecting displacement of the movable stage in a predetermined direction, comprising: a lateral shift amount of a light beam returned from the movable stage;
A stage comprising: a light beam detection system that detects at least one of a change amount of a shake angle; and a calculation system that calculates a rotation angle of the movable stage based on a detection result of the light beam detection system. apparatus. 2. The stage apparatus according to claim 1, wherein the light beam detection system includes a lateral shift amount in a predetermined first direction of a light beam returned from the movable stage, or a change amount of a deflection angle. A first light beam detection system that detects at least one of: a shift amount of a light beam returned from the movable stage in a second direction orthogonal to the first direction; And a second light beam detection system for detecting one of the movable stages. The calculation system calculates a rotation angle of the movable stage around two axes from the detection results of the first and second light beam detection systems. A stage device characterized by the above-mentioned. 3. The stage device according to claim 1, wherein the light beam detection system detects a lateral shift amount of the light beam returned from the movable stage, and the arithmetic system includes the light beam. A stage apparatus for calculating a rotation angle of the movable stage from a lateral shift amount detected by a detection system and a displacement of the movable stage measured by the interferometer. 4. The interferometer according to claim 1, 2 or 3, wherein the interferometer is based on a lateral shift amount or a change amount of a deflection angle of the light beam detected by the light beam detection system. A stage device provided with an optical path correction system that corrects the optical path of the light beam so as to increase the amount of overlap between the reference light beam and the measurement light beam. 5. A movable stage on which a positioning object formed of a mask or a substrate is placed and which moves two-dimensionally with the positioning object, and a light for measurement is provided on the movable stage along a predetermined first direction. A first interferometer that irradiates a beam and receives a light beam returned from the movable stage to detect a displacement of the movable stage in the first direction; and a first interferometer orthogonal to the movable stage in the first direction. A second interferometer that irradiates a light beam for measurement along a second direction and receives a light beam returned from the movable stage to detect displacement of the movable stage in the second direction; And the mask or the substrate is moved by the movable stage to 2
An exposure apparatus for transferring a pattern of the mask onto the substrate by two-dimensionally positioning the two-dimensional lateral shift amount of a light beam returned from the movable stage to the first interferometer. A first light beam detection system that detects at least one of a change amount of a dimensional shake angle, and a lateral shift amount of a light beam returned from the movable stage to the second interferometer, or a change amount of a shake angle. A second light beam detection system that detects at least one of the first and second light beam detection systems; and a calculation system that calculates a rotation angle of the movable stage around three axes based on detection results of the first and second light beam detection systems. An exposure apparatus comprising: