JPH10106938A - Aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain or prevent deterioration of overlapping precision of a mask pattern and a photosensitive substrate which is to be caused by positional change and rotation of a fixed mirror. SOLUTION: The local temperature of a fixed mirror 36 or its fixing part 38 are kept constant by a local temperature control mechanism (40, 42). Generation of thermal deformation, e.g. in the fixed mirror 36 or the fixing part 38 can be prevented. Thereby generation of measurement error of the position of a substrate stage 16 by a laser interference system 50 which is to be caused by a positional change and rotation of the fixed mirror 36 can be restrained or evaded. As a result, positioning precision of a substrate stage 16 is improved, so that deterioration of overlapping precision of the pattern of a mask R and a photosensitive substrate W can be restrained or prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus,
More specifically, the present invention relates to an exposure apparatus used in a photolithography process for a fine circuit pattern of a semiconductor integrated circuit, a liquid crystal display, or the like.

[0002]

2. Description of the Related Art When a semiconductor element or a liquid crystal display element is manufactured by a photolithography process, an image of a pattern of a photomask or a reticle (hereinafter, collectively referred to as a "reticle") is exposed to a photosensitive material through a projection optical system. There is used a projection exposure apparatus that projects onto each shot area on a substrate such as a wafer or a glass plate (hereinafter, collectively referred to as a “wafer”) on which is coated. In recent years, as a projection exposure apparatus of this type, a wafer is mounted on a two-dimensionally movable stage, and the wafer is moved (stepped) by this stage, and an image of a reticle pattern is shot on each wafer. 2. Description of the Related Art A so-called step-and-repeat type exposure apparatus that repeats an operation of sequentially exposing an area, particularly, a reduction projection type exposure apparatus (stepper) is relatively frequently used.

[0003] For example, semiconductor elements are formed by superposing and exposing a multi-layer circuit pattern on a wafer.
Then, when projecting and exposing the circuit pattern of the second and subsequent layers on the wafer, the alignment between the already formed circuit pattern on the wafer and the image of the reticle pattern, that is, the alignment between the wafer and the reticle (alignment) ) Must be performed accurately. For this alignment, a mark for position detection (alignment mark) is formed on the wafer together with the existing circuit pattern, and the position of the circuit pattern can be accurately recognized by detecting the position of the mark with an alignment sensor. Can be.

[0004] The position of a stage on which a wafer is mounted (hereinafter, referred to as a "wafer stage") is precisely measured using a laser interferometer, and the position of the stage during alignment is accurately measured. The overlay exposure is performed by adjusting the stage position so that each shot area is correctly aligned with the exposure position. In general, a laser interferometer is configured by a two-axis orthogonal measurement system having an intersection at the center of an exposure position on a wafer. As described above, when the exposure position and the interferometer measurement axis are on the same straight line, even if the wafer stage is slightly rotated, the rotation error does not affect the stage coordinate measurement value by the laser interferometer, and accurate position measurement is performed. And positioning is possible.

As an alignment sensor system currently used, a system for detecting the position of a mark on a wafer with a light beam other than the exposure wavelength is generally used. (Hereinafter referred to as “TTL (Throug
h The Lens) method, or a method that uses a dedicated position detection optical system (hereinafter “off-Axis”).
System "). In these systems, the reticle and the wafer are not directly aligned, but are indirectly adjusted via a reference mark provided in a projection exposure apparatus (generally, on a wafer stage).

As an example, the off-axis method will be specifically described. First, before the overlay exposure, the reference mark is aligned with the position of the alignment mark on the reticle projected on the wafer stage, and the position of the wafer stage at that time is measured. Subsequently, the reference mark is moved below the wafer mark detection optical system, and is aligned with the detection reference of the wafer mark detection optical system (alignment sensor). At this time, the position of the wafer stage is measured. The difference between these two stage positions is called a baseline amount, and the above sequence is called a baseline measurement.

At the time of overlay exposure on a wafer, the alignment mark on the wafer is aligned with the wafer mark detection optical system, and the wafer stage is moved to a position shifted by a baseline amount from the position of the wafer stage at that time. By performing the exposure, the existing circuit pattern on the wafer and the image of the reticle pattern can be superimposed.

However, depending on the configuration of the exposure apparatus, the position where the mark is detected by the alignment sensor and the exposure position may be far apart (for example, several tens of mm). There is no particular problem if the direction of the deviation is coincident with the measurement direction of the alignment sensor, but if the deviation is in the direction perpendicular to the measurement direction, the measurement error due to the minute rotation of the stage during mark position measurement May occur.

For this reason, the laser interferometer system of the apparatus having such a configuration has a measurement system with three or more axes so that it can measure not only the orthogonal two-dimensional stage coordinates but also the rotation amount of the stage. It has a configuration. Two of these axes are parallel measurement axes, and the rotation of the stage can be measured from the difference between the measured values of the two axes.

If the stage rotation at the time of alignment can be measured, even if there is stage rotation, accurate position measurement without errors can be performed by correcting the alignment measurement value by the amount of stage rotation.

Although the stage on which the wafer is mounted is generally of extremely high precision, the amount of rotation changes slightly (generally called "yawing") with the two-dimensional movement. . On the other hand, if the reticle is kept fixed, the projected image of the reticle will be rotated with respect to the wafer on the rotated wafer stage, and a position shift will occur. In order to prevent this, an apparatus that corrects the rotation of the reticle (the reticle stage on which the reticle is mounted) based on the rotation amount of the wafer stage measured by the above-mentioned laser interferometer, and always performs accurate alignment. There is also.

[0012]

In the conventional apparatus as described above, the measurement of the position or the amount of rotation of the stage is performed by using a reflecting mirror (generally called a "moving mirror") provided on a movable stage and an apparatus. It is measured as a change in relative position with respect to a reflecting mirror (generally referred to as a “fixed mirror”) or a relative rotation amount provided on a portion other than the stage inside. Therefore, if the positions of the reflecting mirrors are shifted due to, for example, thermal expansion or the like, the superposition result is also greatly shifted, and the semiconductor integrated circuit to be manufactured may be defective.

Generally, in an exposure apparatus, the wafer stage repeatedly moves (steps) at a high speed with the start of the exposure operation, and the wafer is irradiated with high energy (exposure light). Temperature tends to rise, the temperature of moving mirrors and fixed mirrors,
Alternatively, the temperature of the mounting portion also increases.

Therefore, due to the thermal deformation of those parts,
There was a possibility that the above-mentioned misalignment would occur. In particular, the fluctuation of the rotation of the fixed mirror has a large effect on the rotation measurement of the wafer stage described above, and as a result, there is a disadvantage that the overlay accuracy of the pattern on the reticle and the pattern on the wafer is deteriorated.

The present invention has been made under such circumstances, and an object of the present invention is to superimpose a mask pattern and a photosensitive substrate caused by positional fluctuation and rotation of a fixed mirror. An object of the present invention is to provide an exposure apparatus capable of suppressing or preventing deterioration in accuracy.

[0016]

According to a first aspect of the present invention, there is provided a substrate stage (16) capable of holding a photosensitive substrate (W) and moving in at least a two-dimensional plane, and comprising: A laser interferometer system (50) for measuring a position of the substrate stage (16) from a relative positional relationship between a provided movable mirror (34) and a fixed mirror (36) provided on an apparatus fixing part outside the substrate stage. And an image of the pattern formed on the mask (R) is transferred to the photosensitive substrate (W).
In the exposure apparatus for transferring images upward, local temperature control mechanisms (40, 42) for locally maintaining the temperature of the fixed mirror (36) or its mounting portion (38) are provided.

According to this, the local temperature control mechanism makes it possible to locally maintain the temperature of the fixed mirror or its mounting portion. For this reason, for example, it is possible to prevent thermal deformation of the fixed mirror or the mounting portion thereof, and thereby, a measurement error of the position of the substrate stage by the laser interferometer system due to the position fluctuation and rotation of the fixed mirror. The occurrence can be suppressed or avoided, and as a result, the positioning accuracy of the substrate stage can be improved, and as a result, it is possible to suppress or prevent the deterioration of the overlay accuracy between the mask pattern and the photosensitive substrate.

In this case, the laser interferometer system may be a system capable of measuring only the two-dimensional coordinate position of the substrate stage. The system may have at least three measurement axes and measure the two-dimensional coordinate values and the rotation amount of the substrate stage (16). In such a case, the local temperature control mechanism locally fixes the fixed mirror or its mounting portion to prevent the position fluctuation and rotation of the fixed mirror, so that the position of the substrate stage 2 measured by the laser interferometer system is reduced. The occurrence of measurement errors in the dimensional coordinate position and the amount of rotation can be suppressed or avoided, and as a result, the accuracy of positioning the substrate stage and the accuracy of overlaying the pattern of the mask with the photosensitive substrate can be improved.

The exposure apparatus according to claim 2 as well as the exposure apparatus according to claim 1 need not necessarily include a projection optical system, and may be, for example, a proximity type exposure apparatus. As in the exposure apparatus according to item 3, a projection optical system (PL) that projects the pattern of the mask (R) onto the photosensitive substrate (W), and alignment on the photosensitive substrate without passing through the projection optical system. When the apparatus further includes a mark detection system (18) for detecting the position of the mark, the local temperature control mechanism (40, 42) for locally maintaining the temperature of the fixed mirror (36) or its mounting part (38) is: Greater effect. That is, when a mark detection system that detects the position of an alignment mark on a photosensitive substrate without using a projection optical system is used, the measurement axis of the alignment mark and the measurement axis of the substrate stage (usually the center of the projection optical system) Is the origin)
Although the Abbe error occurs due to the difference between the two, there is no rotation of the fixed mirror, so the rotation of the wafer stage is accurately measured by the laser interferometer system based on the fixed mirror, and the measurement result This is because, by correcting the measurement value of the alignment mark based on the above, it is possible to prevent the deterioration of the overlay accuracy between the mask pattern and the photosensitive substrate due to Abbe error.

The local temperature control mechanism according to any one of the first to third aspects of the present invention is not limited as long as the fixed mirror or the mounting portion thereof is locally thermostated. Well, for example, as in the invention of claim 4,
The local temperature control mechanism may supply the constant temperature fluid (42a) to the vicinity of the fixed mirror or the mounting portion thereof. In this case, heat is exchanged between the supplied constant-temperature fluid and the fixed mirror or the mounting portion thereof, and thermal deformation of the fixed mirror and the mounting portion is prevented.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG.
A description will be given based on FIG.

FIG. 1 shows an exposure apparatus 10 according to one embodiment.
Is schematically shown. The exposure apparatus 10 is a step-and-repeat type reduction projection exposure apparatus (so-called stepper).

The exposure apparatus 10 includes an illumination system 12 for illuminating a reticle R as a mask with illumination light for exposure, a reticle stage 14 for holding the reticle R, and an image of a pattern (original) PA formed on the reticle R. A projection optical system PL that projects onto a wafer W as a substrate, a wafer stage 1 as a substrate stage that holds the wafer W, moves two-dimensionally in a reference plane, and is rotatable within a predetermined angle range.
6. Off-axis type alignment microscope 18 as a mark detection system for detecting an alignment mark (wafer mark) as a position detection mark formed on wafer W, laser interferometer for measuring the position and rotation of wafer stage 16 The system includes a system 50, a drive system 22 for driving the wafer stage 16, a main controller 24 including a minicomputer (or microcomputer) for controlling the entire apparatus.

The illumination system 12 includes a light source (a mercury lamp or an excimer laser or the like), a shutter, a blind, an input lens, a fly-eye lens, a relay lens, a main condenser lens (all not shown), and the like. .

The illumination system 12 illuminates the pattern PA on the lower surface (pattern forming surface) of the reticle R with uniform illumination distribution by illumination light for exposure from a light source. Here, the illumination light for exposure is monochromatic light (or quasi-monochromatic light), and its wavelength (exposure wavelength) is, for example, 365 nm of mercury emission line (i-line), and 248 nm of KrF excimer laser.

A reticle R is fixed on the reticle stage 14 by vacuum suction or the like. The reticle stage 14 is driven by a driving system (not shown) in the X direction (the horizontal direction in FIG. 1) and the Y direction (in FIG. 1). It can be finely driven in the direction perpendicular to the paper surface) and in the θ direction (the rotation direction in the XY plane).

The optical axis AX of the projection optical system PL is set in the Z-axis direction orthogonal to the plane of movement of the reticle stage 14. Here, both sides are telecentric, and a predetermined reduction magnification β (β is, for example, 1/5) is obtained. Are used. Therefore, as described later, the pattern P of the reticle R
When the reticle R is illuminated with uniform illuminance by the illumination light in a state where the alignment between the A and the shot area on the wafer W has been performed (alignment), the pattern PA on the pattern formation surface is reduced by the projection optical system PL. Scaled down by a factor β,
A projected image is projected onto the wafer W coated with the photoresist, and a reduced image of the pattern PA is formed in each shot area (for example, an area of each LSI chip) on the wafer W.

The wafer W is fixed on the wafer stage 16 via a wafer holder (not shown). The wafer stage 16 is actually a Y stage that moves on the base 30 in the Y direction (a direction orthogonal to the paper surface of FIG. 1), and an X stage that moves on the Y stage in the X direction (the horizontal direction of the paper surface of FIG. 1). And a θ stage mounted on the X stage and rotatable within a small angle range around the Z axis integrally with the wafer holder. In FIG. 1, these are representative wafers. Shown as stage 16.

A reference plate FP is fixed on the wafer stage 16 so that its surface is at the same height as the surface of the wafer W. On the surface of the reference plate FP, various reference marks including a reference mark used for baseline measurement or the like are formed.

The alignment microscope 18 is fixed to one side surface (the surface on the near side in FIG. 1) of the projection optical system PL via a mounting member 18A (see FIG. 2). In the embodiment, an image processing system is used. The alignment microscope 18 includes a light source that emits blow-band illumination light such as a halogen lamp, an objective lens, an index plate, an image sensor such as a CCD, a signal processing circuit, an arithmetic circuit, and the like (all not shown). I have. Illumination light emitted from a light source constituting the alignment microscope 18 passes through an objective lens inside the alignment microscope 18 and is irradiated onto a wafer W (or a reference plate FP), and a wafer mark area (not shown) on the surface of the wafer W The reflected light from the mirror returns to the inside of the alignment microscope 18, sequentially passes through the objective lens and the index plate, and forms an image of the wafer mark and an image of the index on the index plate on an imaging surface such as a CCD. The photoelectric conversion signals of these images are processed by the signal processing circuit, and the arithmetic circuit calculates the relative position between the wafer mark and the index.

Next, the laser interferometer system 50 will be described. The laser interferometer system 50 includes a movable mirror 34 fixed on the upper surface of the wafer stage 16 and a fixed mirror support member 3 as a fixed mirror mounting portion on a side surface of the projection optical system PL.
8 and the movable mirrors 3
4. A laser that projects a laser beam onto the fixed mirror 36 and receives each reflected light, thereby measuring the position and rotation of the wafer stage 16 as a relative positional relationship between the movable mirror 34 and the fixed mirror 36. And an interferometer 20. In the present embodiment, actually, an X moving mirror 34X having a reflecting surface substantially orthogonal to the X axis and a Y moving mirror 34Y having a reflecting surface substantially orthogonal to the Y axis are provided.
Similarly, the fixed mirror is also provided with an X fixed mirror 36X having a reflecting surface substantially perpendicular to the X axis and a Y fixed mirror 36Y having a reflecting surface substantially perpendicular to the Y axis. Two meters for measuring the position in the X-axis direction and one for measuring the position in the Y-axis direction are provided. In FIG. 1, these are the moving mirror 34, the fixed mirror 36, and the laser interferometer 2.
It is typically shown as 0 (see FIG. 2).

Here, the configuration and arrangement of the movable mirror, the fixed mirror, and the laser interferometer constituting the laser interferometer system 50 will be described with reference to FIG.

FIG. 2 is an enlarged schematic plan view of the fixed mirror and its peripheral portion. 2, an X-moving mirror 34X extends in the Y-axis direction at one end of the wafer stage 16 in the X-axis direction (the right end in FIG. 2), and the Y-movement mirror 34X moves at one end in the Y-axis direction (the upper end in FIG. 2). The mirror 34Y extends in the X-axis direction.

On one side of the projection optical system PL in the X-axis direction, an X fixed mirror 36 having a reflecting surface substantially orthogonal to the X-axis is provided.
X is mounted via a fixed mirror support member (fixed mirror mounting portion) 38X, and a Y fixed mirror 36Y having a reflection surface substantially orthogonal to the Y axis on one side surface of the projection optical system PL in the Y axis direction.
Are mounted via a fixed mirror support member (fixed mirror mounting portion) 38Y.

Two laser interferometers 20X ₁ for measuring the position in the X-axis direction facing the X fixed mirror 36X and the X movable mirror 34X,
20X ₂ are provided, Y fixed mirror 36Y, Y movable mirror 34Y
A laser interferometer 20Y for measuring the position in the Y-axis direction is provided to face the camera. In the following description, the measurement axes of the two laser interferometers 20X ₁ and 20X ₂ for measuring the position in the X-axis direction are referred to as X ₁ axis and X ₂ axis, respectively, and the measurement of the laser interferometer 20Y for measuring the position in the Y axis direction is performed. The axis is referred to as the Y axis (coincides with the Y axis that is the movement axis of wafer stage 16).

[0036] While laser interferometer 20X ₁ of the X-axis direction position for measurement, the fixed mirror 36X, measurement beams BRX ₁ in a direction parallel to the X axis, BMX ₁ and by projecting respectively moving mirror 34X, Receives each reflected light and fixed mirror 36X
Measuring the X ₁ axial relative position between the moving mirror 34X.
The other laser interferometer 20X for measuring the position in the X-axis direction
₂ projects the length measurement beams BrX ₂ , BmX ₂ in the direction parallel to the X axis to the fixed mirror 36X and the movable mirror 34X, receives the respective reflected lights, and measuring the relative position of the X ₂ axis direction.

Here, each of the two beams of the X ₁ axis and the X ₂ axis is positioned at the exposure position (the center C _{1 of} the projection optical system PL,
That is not coaxial with the wafer stage coordinate system origin) are separated by D _2/2 in one and the other side of the respective Y-axis direction. Therefore, the laser interferometer 20X ₁ and 20X ₂
By using the average value of the measured values, it is possible to perform a measurement completely equivalent to a one-axis (X-axis) interferometer coaxial with the exposure position. Moreover, these X ₁ axis and the X ₂ axis is the measurement axis of the laser interferometer 20X _1, 20X ₂ by a distance D ₂ apart,
And two laser interferometers 2
The rotation angle (rotation amount) of the wafer stage 16 can be measured by dividing the difference between the measurement values of 0X ₁ and 20Y ₂ by D ₂ .

Laser interferometer 20Y for position measurement in Y-axis direction
Respectively project the length measurement beams BrY and BmY in the Y-axis direction onto the fixed mirror 36Y and the movable mirror 34Y, receive the respective reflected lights, and receive the reflected light Y from the fixed mirror 36Y and the movable mirror 34Y.
Measure the relative position in the axial direction.

That is, the relative positional relationship between the fixed mirrors 36X and 36Y and the movable mirrors 34X and 34Y on the wafer stage 16 is determined by the interferometer beams (BmY and BrY) on the Y axis and X _1.
Is measured by the interferometer beams of the shaft (BMX ₁ and BRX ₁₎ and the interferometer beam of X ₂ axis (BMX ₂ and BRX _2).

The laser interferometer 20 (20X ₁ , 20X
₂ , 20Y) are supplied to the main controller 24. The main controller 24 determines the position and the rotation amount of the wafer stage 16 with the fixed mirror based on the measurement values of the laser interferometer 20 as described above. It is measured as the relative positional relationship of the moving mirror. Further, the main controller 24 positions the wafer stage 16, that is, the wafer W via the drive system 22 while monitoring the measurement value of the laser interferometer 20, for example, when positioning the wafer stage 16. I have.

Incidentally, the aforementioned alignment microscope 1
8, the center (detection position) C ₂ is, to an exposure position (center) C ₁ of the projection optical system PL, and are disposed apart D ₁ in the Y direction. This alignment microscope 18
This is for measuring the position of the mark on the wafer W in both the direction and the Y direction. Thus, for measurement of the X-direction, the measurement position X ₁ axis, without on the axis of any laser interferometer X ₂ axis, possible for the rotation of the measurement during the wafer stage 16 in this state the position measurement error There is.

However, in the apparatus 10 of this embodiment, the rotation angle (rotation amount) of the wafer stage 16 is measured by a value obtained by dividing the difference between the measurement values of the laser interferometers 20X ₁ and 20X ₂ by D ₂ as described above. it can, by a value obtained by multiplying the distance D ₁ to the rotation amount, by correcting the measurement value in the X direction as described above, it is possible to correct the position measurement error caused by the rotation of the wafer stage 16 at the time of the alignment mark measurement .

As described above, the position and rotation of the fixed mirrors 36X and 36Y are used as a reference for detecting the position or rotation of the stage. Therefore, fixed mirror 36X,
If the temperature of 36Y changes due to environmental change or the like and the heat is deformed, a. Error in determining stage position during exposure b. Error in determining stage position when measuring alignment mark c. Error related to stage rotation amount correction during alignment mark measurement d. Various error factors such as an error relating to the reticle rotation correction are generated, and the overlay accuracy of the projected images is deteriorated. In the device 10 of the present embodiment,
The measurement beam of the laser interferometer does not coincide with the coordinate axis of the wafer stage coordinate system. ~ D. Such an error occurs.

In order to prevent this, in this embodiment,
As shown in FIGS. 1 and 3, a temperature controller 40 and a temperature control pipe 42 are provided, and
The temperatures of X, 36Y and fixed mirror support members 38X, 38Y are made constant. That is, in the present embodiment, the local temperature control mechanism is configured by the temperature controller 40 and the temperature control pipe 42.

This will be described in more detail.
Is disposed inside the fixed mirror support member 38X as shown in FIG. 3, and is in contact with the back surface of the fixed mirror and the inner walls of the mounting legs at both ends. The temperature control pipe 42 has both ends connected to the temperature controller 40. The temperature controller 40 includes a heater and a cooler and a control system (not shown) for the heater and the cooler, and sets a predetermined target temperature (for example, a set temperature in a chamber (not shown) in which the exposure apparatus 10 is stored). (For example, 21 ° C. to 23
The temperature of the fluid (liquid or gas) 42a flowing through the temperature control pipe 42 is adjusted within a range of a predetermined temperature adjustment accuracy so that the temperature is slightly lower than (° C). In the present embodiment, an inert liquid, more specifically, a fluorine-based liquid or the like is used as a fluid to be subjected to temperature adjustment.

Therefore, in the present embodiment, the fixed mirror support member 38X and the fixed mirror 36X are thermostated by the action of the fluid (hereinafter, referred to as "constant thermofluid") 42a whose temperature is constant. Even if the temperature fluctuates in the environment, this part is locally thermostated. Here, the temperature controller 4
In order to prevent heat exchange between the constant temperature fluid 42a in the temperature control pipe 42 and the outside of the pipe 42 in the space between the zero and the fixed mirror support member 38X, the temperature controller 40 of the temperature control pipe 42 and the fixed mirror It is desirable to perform a treatment such as winding a heat insulating material around the portion between the support member 38X.

Although not shown, a local temperature control mechanism including a similar temperature controller and a temperature control pipe is also provided on the fixed mirror 61Y side.

Next, the operation of the exposure apparatus 10 configured as described above during exposure will be described. It is assumed that alignment of the reticle R with the projection optical system PL (reticle alignment) using a reticle microscope (not shown) has been completed.

First, prior to the overlay exposure, the alignment microscope 1 detects a position detection mark on the wafer W.
8 position (detection center) C2 and the center C1 of the projection optical system PL
Baseline measurement is performed to measure the positional relationship with the reticle pattern (usually coincident with the center of the reticle pattern). In the present embodiment, the baseline measurement sequence is the same as that of a projection exposure apparatus having a well-known off-axis alignment system, and a detailed description thereof will be omitted.

In the exposure apparatus 10 of this embodiment, after the above-described baseline measurement, the overlay exposure on the wafer W is started. That is, the position of an unillustrated wafer alignment mark on the wafer W is detected by the alignment microscope 18. Then, main controller 24 controls the wafer alignment mark at this time and alignment microscope 1 described above.
The sum of the relative positional relationship with the center of the index mark in 8 and the position of the wafer stage 16 (the output value of the laser interferometer 20) is recognized as the mark position. At this time, in the main controller, as described above, the wafer stage 16
By measuring the amount of rotation, this rotation amount by the value obtained by multiplying the D _1, corrects the measurement value in the X direction.

Subsequently, main controller 24 calculates the amount of wafer W (ie, wafer stage 16) from this mark position by the sum of the base line amount and the design coordinates of the wafer alignment mark.
Is moved based on the measurement value of the laser interferometer 20.

Thus, the pattern PA on the reticle R
Is precisely aligned with the existing pattern on the wafer W. In this state, a shutter (not shown) in the illumination system 12 is opened to perform exposure, and the pattern on the reticle R is projected on the wafer W. Transcribe. At this time, main controller 24 is controlled based on the amount of rotation of wafer stage 16 measured above.
May drive the reticle stage 14 holding the reticle R via a drive system (not shown), and rotate the reticle R by the rotation of the wafer stage 16 so that the pattern projection image can be superimposed on the wafer 10 more accurately. .

By repeating the exposure (projection transfer) while sequentially moving each shot area on the wafer W to the projection position of the image of the reticle pattern, the exposure of the step-and-repeat method is performed. Will be

With the start of the above-described exposure operation, the wafer stage 16 repeatedly moves (steps) at a high speed.
Since the wafer W is irradiated with high energy (exposure light), the temperature of the apparatus main body increases due to the energy. In the case of the present embodiment, the temperature inside the temperature controller 40 and the temperature control pipe 42 is constant. Depending on the fluid, the fixed mirrors 36X, 3
Since the temperature rise of the support members 38X and 38Y can be prevented, the position fluctuation and rotation of the fixed mirror reflecting surface caused by the thermal deformation of the support members 38X and 38Y can be prevented, and the yawing of the interferometer 20 can be prevented. The occurrence of measurement errors,
Error in tip rotation (reticle rotation) and measurement error (drift) in the X-axis direction of the alignment microscope 18
Can be reduced, and thereby, stable alignment accuracy, and thus, accuracy of superimposing the wafer W and the reticle pattern can be ensured with high accuracy and extremely stably.

Here, in the exposure operation of the step-and-repeat method, prior to exposure, each alignment mark in a plurality of shots is detected, and the detected values are statistically processed to determine the arrangement of exposure shots. A so-called EGA (Enhanced Global Alignment) method of exposing all shots based on the array may be used.
A so-called die-by-die method may be used in which alignment marks in each shot area on the wafer W are sequentially detected and the shots are overlaid and exposed. In particular, in the latter die-by-die method, the alignment mark is detected and aligned each time stepping is performed after the start of exposure, so that the effect of preventing the rotation fluctuation of the fixed mirror 36 by the constant temperature fluid becomes greater. .

In the above-described embodiment, the fixed mirror is fixed to the projection optical system PL. However, the place where the fixed mirror is installed is not limited to this, and the stage (movable part) on which the movable mirror is provided is provided.
Any place other than the above may be installed. In such a case, the same effect as in the above embodiment can be obtained. Further, the local temperature control mechanism (4)
0, 42), the temperature of the mounting member 18A of the alignment microscope 18 may be kept constant at the same time. In this case, there is an advantage that the drift of the baseline amount described above can be reduced.

In the above embodiment, the case where the present invention is applied to a projection exposure apparatus has been described. However, the scope of the present invention is not limited to this, and an X-ray proximity exposure apparatus or an electron beam exposure apparatus may be used. The present invention can be suitably applied to an apparatus.

[0058]

As described above, claims 1 to 4
According to the invention described in (1), the position fluctuation and rotation of the fixed mirror caused by the heat fluctuation of the fixed mirror and its mounting portion are prevented, and the deterioration of the overlay accuracy of the pattern of the mask and the photosensitive substrate is suppressed or prevented. There is an unprecedented excellent effect that it can be performed.

[Brief description of the drawings]

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

FIG. 2 is a schematic plan view of the fixed mirror of FIG. 1 and a peripheral portion thereof.

FIG. 3 is an enlarged sectional view showing an arrangement of a temperature control pipe in a fixed mirror mounting portion of FIG. 2 and a state of constant temperature by a temperature controller.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Exposure apparatus 16 Wafer stage (substrate stage) 18 Alignment microscope (mark detection system) 34 Moving mirror 36 Fixed mirror 38 Fixed mirror support member 40 Temperature controller 42 Temperature control pipe 42a Fluid 50 Laser interferometer system PL Projection optical system W Wafer (Photosensitive substrate) R reticle (mask)

Claims (4)

[Claims] A substrate stage capable of holding a photosensitive substrate and moving in at least a two-dimensional plane; a movable mirror provided on the substrate stage; and a fixed mirror provided on a device fixing part outside the substrate stage. A laser interferometer system that measures the position of the substrate stage from a relative positional relationship, and an exposure apparatus that transfers an image of a pattern formed on a mask onto the photosensitive substrate. An exposure apparatus, comprising: 2. The system according to claim 1, wherein the laser interferometer system has at least three measurement axes and measures a two-dimensional coordinate value and a rotation amount of the stage. Exposure equipment. A projection optical system for projecting the mask pattern onto the photosensitive substrate; and a mark detection system for detecting a position of an alignment mark on the photosensitive substrate without passing through the projection optical system. The exposure apparatus according to claim 2, wherein: 4. The exposure apparatus according to claim 1, wherein the local temperature control mechanism supplies the temperature-regulated fluid to the vicinity of the fixed mirror or a mounting portion thereof. .