JP2787711B2 - Projection exposure equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to, for example, a projection exposure apparatus used in the manufacture of LSIs, in particular, provided with a mechanism for measuring the relative position between a mask and a stage and measuring distortion. The present invention relates to a projection exposure apparatus.

[Prior Art] At present, a projection exposure apparatus is generally used for transferring a circuit pattern of an LSI memory or the like. In the transfer of a circuit pattern by this projection exposure apparatus, high-precision relative positioning of a semiconductor wafer and a mask through a projection optical system, which is performed before performing projection exposure, is indispensable, and various relative positioning methods have been devised. Has been put to practical use.

FIG. 7 shows a schematic configuration of a projection exposure apparatus according to JP-A-64-10105. Here, the exposure light source is set to a maximum of 300 Hz.
The excimer laser 30j that emits a pulse is used, and exposure is performed with about 200 pulses per shot (the excimer laser 30j emits 200 times during one exposure period corresponding to a unit exposure area on a wafer). . In addition, the reticle (synonymous with a mask) 1j and the wafer 4j are positioned relative to each other via the projection optical system 3j by the exposure light, and the chromatic aberration of the projection lens 3j as in the case where another light source for alignment is used. Is not affected by various errors caused by This exposure light (hereinafter referred to as measurement light to distinguish it from the case of exposure illumination)
Since the irradiation is performed from the stage 5j in the direction of the reticle 1j, the resist layer formed on the wafer is not unnecessarily exposed.

In this conventional example, the reticle 1j attached to the reticle stage 2j has a light-shielding portion formed around the transfer area and a plurality of positioning reticle marks 9j formed in the light-shielding portion. Where reticle mark 9j
Is a transparent light transmitting portion having a slit shape formed in the light shielding portion.

The light projector 8j on the stage 5j has a reference mark 10j for projecting measurement light. Here, the reference mark 10j
Is a cross shape (2) formed on the light shielding portion on the surface of the projector 8j.
This is a transparent light-transmitting portion having a slit perpendicular to the book.

The reticle 1j and the stage 5j are moved relative to the reticle mark 9j so that the reference mark 10j moves across the projection lens 3j by moving the stage 5j, and the amount of movement of the stage 5j at this time is measured by an interferometer. Measure with 45j. Thereby, the projection lens of the reticle mark 9j
The conjugate position regarding 3j is stored as the position coordinates of the stage 5j, and the position coordinates of an arbitrary point including the center point of the transfer area of the reticle 1j on the stage 5j are calculated.

During the exposure period, the exposure light emitted from the excimer laser 30j is adjusted by the zoom expander 31j, the optical integrator 32j, and the main condenser lens 36j so as to have a uniform intensity distribution on the transfer area of the reticle 1j, and is dichroic. A predetermined area of the reticle 1j is illuminated through the mirror 21j.

The measurement light emitted from the excimer laser 30j when detecting the relative position between the reticle 1j and the stage 5j,
This is a pulse light that emits light in response to a position measurement pulse from the interferometer 45j. This pulse light is transmitted to the mirror 11
The light is guided to the projector 8j through j to 14j, and emitted from the reference mark 10j in the direction of the reticle 1j. Part of this measurement light forms a slit-like illumination spot (reference mark image) 10j 'on the reticle 1j via the projection lens 3j. Stage 5j
The illumination spot 10j ′ becomes reticle 1j
Move up. Then, when the center of the illumination spot 10j 'matches the center of the reticle mark 9j, the reticle 1j
Is transmitted to the photoelectric detector 25j and reaches the maximum level. Therefore, the output of the photoelectric detector 25j at this time becomes the maximum output. That is, the relative position of the reticle 1j in the stage movement coordinate system is determined by obtaining the position of the stage 5j at which the maximum output is obtained.

FIG. 8A shows an illumination spot 10 on the reticle 1j.
This shows an overlapping state of j ′ and reticle mark 9j accompanying the movement of stage 5j. The illumination spot 10j 'moves at a constant speed in the direction of the arrow as the stage 5j moves. FIG. 8B shows a change in the output signal of the photoelectric detector 25 accompanying the movement of the illumination spot 10j '. Lighting spot 10j ′
When the center of the reticle mark 9j coincides with the center of the reticle mark 9j, the output signal becomes maximum. However, each emission pulse of the excimer laser 30j (for example, a trigger every 0.16 μm movement of the stage 5j)
And a discrete output signal distribution corresponding to

Excimer lasers used as a light source for exposure light generally have a maximum emission rate of about 200 pps per second and a light emission duration of about 10 nsec per pulse in the current state of the art. In comparison, the light emission duration of one pulse is extremely short.

[Problems to be Solved by the Invention] In an exposure apparatus using an excimer laser as a light source of exposure light, as in a conventional projection exposure apparatus, the stage is moved at high speed because the emission repetition frequency of the excimer laser is low as described above. It was difficult to perform high-accuracy position measurement while doing so. That is, information (photoelectric signal) indicating the state of the relative position between the wafer and the mask cannot be obtained during the light-emission pause time (between pulses), so that the stage interferometer is used.
It was necessary to reduce the stage moving speed according to the response of the measurement pulse from 45j. Therefore, a problem such as a long time is required for the relative positioning between the wafer and the reticle, and the throughput of the apparatus is impaired. In addition, the pulse life of excimer laser is impaired because pulse emission of several hundred times or more is required every time the slit mark is scanned once.

In order to increase the measurement speed, for example, it is conceivable to enlarge the light-transmitting portion of the reticle mark, or to trigger the excimer laser by covering the measurement pulse of the interferometer 45j. Accuracy decreases.

Further, since the output of each pulse emission of the excimer laser fluctuates, it is necessary to calibrate (normalize) the measurement signal according to the output of each pulse emission as shown in JP-A-64-10105. Was.

[Means for Solving the Problems] A projection exposure apparatus according to the present invention includes a first illumination optical system for illuminating a mask having a predetermined pattern and a predetermined positioning mark formed on a mask surface with exposure light, A projection optical system that projects the image of the image onto a predetermined image plane, and a stage that is movable along the image plane, wherein an opening is formed in substantially the same plane as the image plane. A reference member fixed to the stage, and a second illumination optical system that illuminates an opening of the reference member and forms a projected image of the opening on the mask surface via the projection optical system. System and
The positioning is performed by moving the stage to capture a projection image of the opening and the positioning mark on the mask surface and obtaining a relative positional relationship between the projection image of the opening and the positioning mark by image processing. Measuring means for measuring an image forming position of the mark by the projection optical system.

[Operation] In the projection exposure apparatus according to the present invention, the first illumination optical system illuminates the mask surface with exposure light. Further, the projection optical system projects an image of a predetermined pattern on the mask surface illuminated by the exposure light onto a predetermined imaging surface. Since the opening is formed in the same plane as the image forming plane, a projected image of the opening is formed on the mask surface via the projection optical system. Further, the opening is provided on a reference member fixed to the stage, and the stage moves along the imaging plane, so that the projected image of the opening moves on the mask surface with the movement of the stage. obtain. The second illumination optical system forms a projection image of the opening on the mask surface as described above. Further, the measuring means moves the stage and obtains a relative positional relationship between the projected image of the opening on the mask surface and the positioning mark by image processing, thereby determining an image forming position of the positioning mark by the projection optical system. measure.

FIG. 1 shows a configuration of an exposure apparatus according to a first embodiment of the present invention. Here, measurement of the relative position between the reticle (synonymous with the mask) 1 and the stage 5 via the projection lens 3 is performed by comparing the reference mark 10 projected on the reticle with the reticle mark 9.

In the present exposure apparatus, a reticle 1 having a predetermined circuit pattern and a reticle mark 9 for positioning is attached to a reticle stage 2 and faces a stage 5 via a projection lens 3 which is telecentric on both sides (or one side centric). I do. The reticle 1 can be moved on the reticle stage 2 in the X and Y directions by a drive motor 42, and the amount of movement is measured by an interferometer 43. The movement of the reticle stage 2 is used for positioning the reticle 1 described later. The moving width of the reticle stage 2 is several millimeters or less, and the detection resolution of the interferometer 43 is about 0.01 μm.

Actually, three sets of interferometers (laser-wave interferometers) 43 and mirrors 6 are provided to independently detect the positions in the X direction, the Y direction, and the rotation θ direction. The illustration is partially omitted for simplicity of explanation. Further, a total of three drive motors 42 are provided corresponding to the respective directions, but a similar illustration is partially omitted.

The stage 5 is configured to be freely movable by a drive motor 46 along an image plane of the reticle 1 with respect to the projection lens 3. The position coordinates of the stage 5 with respect to the exposure apparatus main body are determined by the amount of movement of the mirror 7 fixed to the stage 5 by an interferometer.
It is measured by 45 and calculated as the distance from a predetermined reference point. Actually, an interferometer (laser light wave interferometer) 45
Although two sets of the mirror 7 and the mirror 7 are provided for independently detecting the positions in the X direction and the Y direction, some of them are not shown here for the sake of simplicity. Further, a total of two drive motors 46 are provided corresponding to the respective directions, but also partially omitted in the drawing.

The illumination optical system for exposure includes an excimer laser 30, a zoom expander 31, an optical integrator (fly-eye lens) 32, mirrors 33 and 35, a relay lens 34, a main condenser lens 36, and the like. Excimer laser
Exposure light emitted from 30 is supplied to a zoom expander 31, an optical integrator 32, and a main condenser lens 36.
Is adjusted so as to have a uniform intensity distribution on the irradiation surface of the reticle 1, and the beam splitter (half mirror)
A predetermined area of the reticle 1 is illuminated through the reticle 1. The zoom splitter 21 has a transmittance of 90% with respect to the wavelength of the exposure light.
With a reflectance of 10%.

The optical system for detecting the position of the reticle 1 is an excimer laser
The optical system includes a mirror 30, mirrors 11 to 14, a light projecting system 8, and a projection lens 3. When performing this position detection, the exposure light emitted from the excimer laser 30 is reflected by the mirror 11 and used as measurement light. The measurement light is guided to the light projecting system 8 via the mirrors 12, 13, and 14, and is emitted upward from the reference mark 10 which is an opening formed in the conjugate plane of the reticle 1, and the projection lens 3
To form a projection image (aperture image) of the reference mark 10 on the reticle 1.

The projected image of the reference mark can be positioned at an arbitrary point on the reticle 1 by moving the stage 5. The mirror 11 also serves as a shutter of an optical system for exposure, and is retracted from a position in FIG. 1 by a motor (not shown) during exposure.

The optical system for imaging and comparing the reference mark 10 projected on the reticle 1 and the reticle mark 9 is a beam splitter 2.
1. It comprises an objective lens 22, a half mirror 23, an imaging lens 24, and an image sensor 25.

This optical system is arranged so as to catch the reticle mark 9 on the reticle 1. When the stage 5 moves and the projected image of the reference mark 10 overlaps with the reticle mark 9, this overlapping state is determined by the image sensor 25. And the relative position between the reference mark 10 and the reticle mark 9 is measured. At this time, the measurement light passing through the projection lens 3 is
The transparent portion of the reticle 1 around the reticle mark 9 is transmitted and partially reflected by the beam splitter 21 so that the objective lens 2
2. The image is enlarged and formed on the image sensor 25 via the half mirror 23 and the image forming optical system 24.

The detection resolution of this optical system depends on the magnification of the optical system composed of the objective lens 22, the imaging optical system 24, etc., and the image sensor.
Depends on 25 resolution. Here, if the magnification is increased to increase the detection resolution, the field of view of this optical system becomes smaller. However, this field of view is the reference mark on reticle 1.
It is set large enough to capture 10 images.

The objective lens 22 and the mirror 23 are fixed on a movable pedestal, and are moved in the direction of the arrow by a drive system. Thus, if the reticle mark 9 is within an appropriate range on the reticle 1, it can be imaged on the image sensor 25. Also, the half mirror 23 may be a simple mirror originally, but in the present embodiment, the mirror 12 is made movable and retracted from the optical path,
A configuration in which exposure light from the mirror 11 is irradiated to the wafer 4 via the half mirror 23, the beam splitter 21, the reticle 1, and the projection lens 3 to be used for positioning of a shot area on the wafer (die-by-die alignment). And

Next, position measurement of the reticle 1, alignment of the reticle, and wafer alignment using the projection exposure apparatus of the present embodiment will be described.

FIG. 2A shows a reference mark 10 on the light projecting system 8 fixed to the stage 5 in the present embodiment. Here, the reference mark 10 is rectangular, and two pieces are set in a different size, 10 (a) and 10 (b).

FIG. 2B shows a reticle mark 9 set on a transparent portion around the transfer area PE of the reticle 1. The reticle mark 9 is a light-shielding cross mark, and
(B) and 9 (c) are set in three places.

FIG. 2C shows a case where the position of the reticle 1 is detected.
The trajectory of the projected image of the reference mark 10 when the stage 5 is moved to sequentially position each of the three reference marks on the reticle 1 is shown.

The reference mark 10 is set such that the width of the projected image of the reference mark 10 on the reticle 1 is sufficiently wider than the reticle mark 9. Also, the crosshair of the reticle mark 9 is
Each of them is set to be sufficiently long so that an overlap with the projected image of the reference mark 10 occurs in a wide area.

After the reticle 1 is pre-aligned and mounted on the reticle stage 2, position detection and positioning of the reticle 1 are performed. In this case, the stage 5 is moved by a predetermined program without causing the excimer laser 30 to emit light. Accordingly, the locus of the projected image of the reference mark 10 is
It becomes an arrow in FIG. 2 (c) and intersects with each of the reticle marks 9 (a), 9 (b), 9 (c) at an approximate position.

Further, this program emits light from the control system 47 to the excimer laser 30 when the projected image of the reference mark 10 reaches an approximate overlapping position with each of the reticle marks 9 (a), 9 (b), 9 (c). One or more triggers (2-5)
Send out. At the same time, the interfering system 45
Is stored. (In the case of sending a plurality of triggers, the stage 5 needs to be stopped during this period.) Thereby, the excimer laser 30 emits light, generates measurement light, and gives an image on the image sensor 25.

The position coordinates of the stage 5 by the interference system 45 at the time of emission trigger transmission are extracted and stored in the control system 47.

For example, it is assumed that an image as shown in FIG. 3A is formed on the image sensor 25 at an approximate overlapping position of the reticle mark 9 (a) and the projected image of the reference mark 10. In this case, the horizontal scanning line direction of the image sensor 25 is the measurement direction, and the positional relationship between the edge of the reticle mark 9 and the edge of the reference mark 10 extending in a direction intersecting this direction is photoelectrically detected. The output signal of the image sensor 25 at this time is as shown in FIG. By detecting the position of the central concave portion with respect to the rising edges on both sides of the output signal, the shift amount between the center of the projected image of the reference mark 10 and the reticle mark 9 (a) is obtained. Also, the position of the image forming point of the reticle mark 9 (a) via the projection lens 3 is given as the coordinates of the interferometer 45 based on the shift amount and the previously stored stage coordinate value. This operation is performed in accordance with the movement of the stage 5, and the reticle marks 9 (b), 9 (b)
(C) is performed one after another. Then each reticle mark 9
The coordinates of (a), 9 (b), and 9 (c) are compared with target values of the respective coordinates by the control system 47, and the deviation is corrected by moving the reticle stage 2 by the drive motor 42. At this time, the correction amounts of the reticle stage 2 in the x direction, the y direction, and the rotation direction are measured by the interferometer 43 and the controller 47
Is fed back to

In the projection exposure apparatus of the present embodiment, the above operation is repeated twice, that is, coarse adjustment and fine adjustment, in order to perform the alignment of the reticle 1 with the apparatus efficiently and with high accuracy. Here, the coarse adjustment is performed by using a large reference mark on the light projecting system 8 in FIG.
The stage 5 is continuously moved in accordance with the above-mentioned program using the output signal of the image sensor 25 according to 10 (a), and the field of view is widened by switching the magnification of the imaging optical system 24 to a low magnification. The fine adjustment is performed on each reticle mark 9 obtained by coarse adjustment of the small reference mark 10 (b).
(A), 9 (b) and 9 (c) are moved from the coordinates of the projected position by the center distance of both reference marks 10 (a) and 10 (b), or are positioned and stopped at the shifted positions. Let
The magnification of the imaging optical system 24 is switched to a high magnification to increase the detection resolution.

The alignment of the reticle 1 with respect to the apparatus is performed by the above procedure. Further, the circuit pattern area PE on the reticle 1 is obtained from the position coordinate values of the stage 5 corresponding to the respective reticle marks 9 (a), 9 (b), 9 (c) after the completion of the alignment.
Is obtained and stored.
Further, a residual rotation (rotation amount) error of the reticle 1 is detected from the coordinates of the reticle marks 9 (a) and 9 (c).

Die-by-die alignment systems (11, 22,
23, 24, 25, 30) or the distance between the reference mark 10 on the stage 5 and the alignment mark on the wafer 4 measured by an off-axis alignment system or the like (not shown), the projected image of the circuit pattern area PE and the wafer The amount of movement of the stage 5 necessary to overlap the upper transfer target area is calculated. The control system 47 adjusts the position of the stage 5 by the drive motor 46 according to the amount of movement. Thus, a relative positioning operation (alignment) between the wafer 4 and the reticle 1 is performed.

In the above operation, one emission pulse width of the excimer laser 30 is about 20 nsec, and an emission trigger can be emitted within 1 μsec from the control system 47, so that the reticle mark 9 can be emitted without stopping the wafer stage 5. Sufficiently accurate measurement is possible by emitting only one pulse while the reference mark 10 scans the projected position at a high speed. At this time, if the light emission trigger and the output of the interferometer 45 are processed at a sufficiently high speed by the hardware of the control system 47, the error caused by scanning can be made sufficiently smaller than the interferometer resolution.

In addition, by positioning the wafer stage 5 and emitting the excimer laser 30 several times in a sufficiently stable state, the same image can be accumulated in the image sensor 25 and the output signals can be averaged to improve the measurement reproducibility. It is possible.

Further, at the approximate overlapping position of the projected image of the reference mark 10 and the reticle mark 9, the relative positions of the two are shifted by a fixed amount in the measurement direction, and the amount of displacement is measured. The reticle mark 9 is calculated based on the positional shift amount obtained from the image and the shifted amount (moved position).
It is also possible to calculate the stage position coordinates where the center of the reference mark image coincides with the center of the reference mark image.

Next, magnification measurement and distortion measurement in the exposure apparatus of the present embodiment will be described.

On the reticle 1 used here, together with the reticle mark 9 described above, a light-shielding cross mark is formed corresponding to the distortion and magnification measurement positions of the area including the transfer area. By detecting the positions of the projected images of these cross marks, magnification measurement and distortion measurement are performed.

After positioning the reticle 1 with respect to the apparatus, the interferometer 45 feeds back the movement amount by the interferometer 45 in accordance with a predetermined program such that the reference mark 10 passes through each of the design imaging points of each cross mark with respect to the imaging lens 3. Move 5 When the center of the reference mark 10 reaches each of the design imaging points as shown in FIG.
Flash 30. An output signal as shown in FIG. 4 (b) is obtained from the image sensor 25, and the rising of both sides and the central concave portion are detected, and the positional shift between each of the design imaging points of the cross mark and the reference mark 10 is detected. Calculate the amount. Here, the image sensor 25 simultaneously outputs output signals in two directions of the x-axis direction and the y-axis direction (two-dimensional sensor), so that one emission of the excimer laser 30 emits two signals in the x-axis direction and the y-axis direction. The amount of displacement in the direction is detected. However, in the vertical scanning direction of the image sensor 25, a signal as shown in FIG. 4 (b) is obtained by extracting a level of a pixel row arranged in the vertical direction by a clipping circuit or the like after scanning one frame.

If there is no distortion or magnification error in the projection lens, the center of the cross mark and the center of the light-emitting mark coincide with each other, but usually slightly deviate, and this deviation is distortion or magnification error.

Also at the time of measuring the distortion and the magnification error, the objective lens 22 can be moved in a plane perpendicular to the paper surface by the drive system to form all the cross marks on the reticle 1 on the image sensor 25. Thereby, reticle 1
Measurements are made for all the above cross marks.

As still another function of the projection exposure apparatus of the present embodiment, it is also possible to measure the in-focus position of an arbitrary point on the reticle 1 with respect to the projection lens 3.

Here, the stage 5 is provided with a focus detection system that measures the amount of vertical movement, a gap sensor, and the like. The stage 5 is moved up or down to move the image sensor 25
By sampling the signal waveform, the in-focus point is determined from the contrast of the signal waveform, the inclination of the unevenness of the waveform, and the like, and the height position is measured from the movement amount indicated by the focus detection system, the gap sensor, and the like.

In this embodiment, the transmitted light of the reticle is used. However, in a configuration in which the projection lens 3 is telecentric only on the wafer side, it is possible to use the reflected light of the reticle.

FIG. 5 shows a second embodiment of the projection exposure apparatus of the present invention. In the second embodiment, the exposure light from the reference mark 10 passing through the telecentric projection lens 3b only on the wafer side is reflected by the reticle 1b and guided to the image sensor 25b.

Here, other configurations not shown are the same as those in FIG. The outside of the transfer area of the reticle 1 is processed on a mirror surface, and the reticle mark 9 is a light-transmitting or absorbing cross shape formed on the mirror surface.

The exposure light from the reference mark 10 passing through the projection lens 3b is
The light is reflected by the reticle 1b and is incident on the image sensor 25b via the mirror 26, the objective lens 22b, and the imaging lens 24b. In the second embodiment, functions and effects similar to those of the first embodiment can be obtained.

FIG. 6 shows a third embodiment of the projection exposure apparatus of the present invention. In the third embodiment, the positioning mark set on the wafer 4 is detected as an image by the alignment system 26c through the projection lens 3c and mirrors 27c and 26c without passing through the reticle 1c. Here, other configurations not shown are the same as those in FIG. The reticle 1c is accurately positioned in advance in the apparatus main body by another method.

In the projection exposure apparatus according to the third embodiment, after pre-aligning the wafer 4 and placing it on the stage 5, the positions of a plurality of positioning marks set on the wafer 4 are measured using the alignment system 26c. I do. Thus, the position of the positioning mark on the wafer 4, that is, the relative positional relationship between the reference mark 10 and the center point of the exposure area (shot) is obtained.

Since the positional relationship between the reference mark 10 and the reticle 1c is measured in advance using the light projecting system 8 on the stage, the reticle 1c and the wafer 4 are relatively positioned as a result. The alignment system 25c has an imaging function like the image sensor 25 of the first embodiment, and also has a function of calculating the amount of deviation of the center position of the detected image with respect to the positioning index set inside the alignment system 25c. have.

In the projection exposure apparatus according to the third embodiment, the stage 5 is moved so that the reference mark 10 is first captured by the alignment system 25c and the coordinate position of the reference mark 10 is stored.
Is moved to catch each positioning mark on the wafer 4 by the alignment system 25c, so that the distance between each positioning mark and the reference mark 10 is reduced by the interferometer 45.
Is measured by In this case, the reference mark 10 needs to be a pattern having a shape that can be easily detected by the alignment system, and desirably has the same shape as the positioning marks on the wafer 4.

Further, as a fourth embodiment not shown, Japanese Patent Application Laid-Open No. 64-1010
Similarly, in a projection exposure apparatus having an OFF-AXIS alignment system as shown in No. 5, a relative position detection system having an imaging function can be employed instead of the photoelectric detector. Thus, the baseline amount and the like can be measured in exactly the same manner as in the third embodiment. According to the present embodiment, the imaging position of the positioning mark by the projection optical system can be detected without positioning the stage so that the center of the positioning mark matches the center of the projected image of the opening.
Further, since the opening is formed so that the projected image of the opening on the mask surface has a width sufficiently larger in the position measurement direction than the slit-shaped positioning mark on the mask side, the image sensor captures the image. The overlapping state between the projected image of the opening and the positioning mark becomes a relatively dark and thin positioning mark inside the bright projected image of the opening. By performing image processing on this bright / dark image, the amount of displacement between the center of the positioning mark and the center of the opening is calculated in units of coordinate values of the stage. Thereby, the coordinates of the stage position where the center of the positioning mark coincides with the center of the projected image of the opening are calculated. That is, the relative positional relationship between the opening and the positioning mark with respect to the projection optical system can be measured without positioning the stage so that the center of the positioning mark coincides with the center of the projection image of the opening. Furthermore, since the relative positional relationship between the projection image of the opening and the positioning mark is obtained by image processing, the image forming position of the positioning mark by the projection optical system can be measured.
High-speed and high-accuracy measurement is possible even using a pulsed light source such as an excimer laser. Further, the number of times of light emission of the light source at this time is much smaller than that of the projection exposure apparatus disclosed in, for example, JP-A-64-10105. This extends the gas life of the light source that emits pulsed light. Further, in the projection exposure apparatus according to the present invention, unnecessary exposure of the resist layer of the wafer is eliminated because the exposure light is not irradiated to the wafer except for the exposure transfer. [Effect of the Invention] In the projection exposure apparatus according to the present invention, the positioning mark is obtained by determining the relative positional relationship between the projection image of the opening of the reference member fixed to the stage and the positioning mark on the mask surface by image processing. Since the image formation position by the projection optical system can be measured, the exposure preparation time and the like are shortened, and the operation efficiency of the apparatus is improved. In addition, by determining the relative positional relationship between the projection image of the opening and the positioning mark by image processing, the image forming position of the positioning mark by the projection optical system can be obtained regardless of the state of overlap between the projection image of the opening and the positioning mark. Can be measured.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of a projection exposure apparatus according to a first embodiment of the present invention. FIG. 2A shows a projector 8 of the projection exposure apparatus according to the first embodiment.
2 (b) is a plan view of the reticle 1, and FIG. 2 (c) is a conceptual diagram illustrating a method of positioning the reticle 1 with respect to the apparatus main body in the first embodiment. FIG. 3A is a conceptual diagram showing an example of a captured image of the image sensor 25 of the projection exposure apparatus of the first embodiment, and FIG.
Is a conceptual diagram showing an output signal of the image sensor 25 at this time. FIG. 4A is a conceptual diagram showing an example of a captured image of the image sensor 25 at the time of measuring distortion in the first embodiment, and FIG. 4B shows an output signal of the image sensor 25 at this time. It is a conceptual diagram. FIG. 5 is a schematic diagram showing a partial configuration of a projection exposure apparatus according to a second embodiment of the present invention. FIG. 6 is a schematic diagram showing a partial configuration of a projection exposure apparatus according to a third embodiment of the present invention. FIG. 7 is a schematic diagram showing a configuration of a conventional projection exposure apparatus. FIG. 8A is a conceptual diagram showing an example of an overlap of projected images of a reticle mark 9j and a reference mark 10j on a reticle 1j of a conventional projection exposure apparatus, and FIG. FIG. 14 is a conceptual diagram showing an output signal of a detector 25j. [Description of Signs of Main Parts] 1 reticle, 3 projection lens 4 wafer 5 stage 6 projection system 9 reticle mark 10 reference mark 11 to 14 Mirror 25 ... Image sensor, 30 ... Excimer laser 34 ... Relay lens system, 36 ... Condenser lens 45 ... Interferometer

Claims (8)

(57) [Claims] 1. A first illumination optical system for irradiating a mask having a predetermined pattern and a predetermined positioning mark formed on a mask surface with exposure light, and a projection optical system for projecting an image of the pattern on a predetermined image forming surface. A projection exposure apparatus comprising: a system; and a stage movable along the imaging plane, comprising: a reference member having an opening in substantially the same plane as the imaging plane and fixed to the stage; A second illumination optical system that illuminates the opening of the reference member and forms a projected image of the opening on the mask surface via the projection optical system; and moving the stage to move the stage onto the mask surface. By imaging the projected image of the opening and the positioning mark in the above and determining the relative positional relationship between the projected image of the opening and the positioning mark by image processing, the image forming position of the positioning mark by the projection optical system Measure That the measuring means and; projection exposure apparatus comprising: a. 2. The apparatus according to claim 1, wherein the opening is formed such that a projection image on the mask surface has a width larger than the positioning mark in a direction of position measurement. The projection exposure apparatus according to claim 1. 3. The projection exposure apparatus according to claim 1, wherein the second illumination optical system has an illumination light source for illuminating the opening with pulsed light. . 4. The apparatus according to claim 1, wherein the first illumination optical system has an exposure light source for illuminating the mask with pulsed light, and the second illumination optical system uses the exposure light source as the illumination light source. 4. The projection exposure apparatus according to claim 3, wherein the projection exposure apparatus is characterized in that: 5. The projection exposure apparatus according to claim 4, wherein said exposure light source emits an excimer laser. 6. The measuring means determines a relative positional relationship between a projection image of the opening and the positioning mark based on image information generated by generating a plurality of pulse lights from the illumination light source. Claim 3 characterized by the following.
Item 3. The projection exposure apparatus according to Item 1. 7. The measuring means measures the image forming positions of a plurality of positioning marks formed on the mask by the projection optical system, and based on a result of the measurement, a magnification and a distortion related to the projection optical system. 3. The projection exposure apparatus according to claim 1, wherein at least one of the two is measured. 8. The apparatus according to claim 1, wherein said measuring means measures the in-focus position of said projection optical system by moving said stage in an optical axis direction of said projection optical system. Item 3. The projection exposure apparatus according to Item 2.