JPH0314217A - Projection aligner - Google Patents

Abstract

PURPOSE:To manufacture the title device capable of rapid measurement with high precision using pulse emitting source while cutting down the exposure preparation time, etc., and increasing the operating efficiency of the device by a method wherein the opening part of a reference member fixed on a stage is formed so that the projected image may be formed to be relatively larger than an alignment mark. CONSTITUTION:The title device is provided with the second illumination optical systems 11-14 focussing a projected image on a mask 1 through the intermediary of a projection optical system 3 of an opening part 10 by projecting exposure light branched off from the first illumination optical systems 30-35 to be led into the opening part 10 of a reference member 8 as well as the second measuring means 25, 45 detecting the relative position of an image in transfer region projected on a focal image surface 4 to the position on a stage 5 by measuring the relative position between the image of the opening part 10 and an alignment mark 8 by image-picking up the overlapping state of the opening part 10 with the alignment mark 9 on the mask surface 1 when they are overlapped with each other by shifting the stage 5. Furthermore, the opening part 10 is formed so that the projected image on the mask surface 1 may be made in relatively wider than that of the alignment mark 9 in the position measuring direction.

Description

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

[Prior Art] Currently, a projection exposure apparatus is generally used for transferring circuit patterns of LSI memories and the like. In transferring a circuit pattern using this projection exposure apparatus, it is essential to perform high-precision relative positioning of the semiconductor wafer and mask via a projection optical system before performing projection exposure, and various relative positioning methods have been devised. It has been put into practical use.

FIG. 7 shows a schematic configuration of a projection exposure apparatus according to Japanese Patent Application Laid-Open No. 64-10105. Here, the light source of the exposure light has a maximum of 3
An excimer laser 30J that emits pulsed light of 0011z is used, and exposure is performed with approximately 200 pulses per shot (the excimer laser 30J emits light 200 times during one exposure period corresponding to a unit exposure area on the wafer). be exposed. In addition, relative positioning between the reticle (synonymous with a mask) 1j and the wafer 4J is performed via the projection optical system 3J using exposure light, and chromatic aberration of the projection lens 3j occurs when a separate light source for alignment is used. There is no effect of various errors caused by Further, this exposure light (hereinafter referred to as measurement light to distinguish it from exposure illumination) is irradiated from the stage 5j in the direction of the reticle 1j, so that the resist layer formed on the wafer is not exposed unnecessarily.

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

Furthermore, the light projector 8J on the stage 5J has a reference mark 10j for projecting open side light. Here, the reference mark 10J is a transparent light-transmitting portion having a cross shape (two orthogonal slits) formed in a light-shielding portion of the surface of the light projector 8j.

With respect to this reticle mark 9j, the reference mark 10j is
By moving the stage 5j, the reticle 1j and the stage 5j are moved relative to each other so as to cross through the projection lens 3j, and the amount of rotation of the stage 5j at this time is measured 84 times by the interferometer 45j. Thereby, the conjugate position of the reticle mark 9J with respect to the projection lens 3J is stored as the position coordinates of the stage 5J, and the position coordinates of an arbitrary point on the stage 5j including the center point of the transfer area of the reticle 1j are calculated.

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

The measurement light emitted from the excimer laser 30j when detecting the relative position between the reticle 1j and the stage 5j described above is pulsed light whose emission is triggered in response to a position measurement pulse from the interferometer 45j. This pulsed light is guided to a projector ajk via mirrors 11j to 14j, and is emitted from the reference mark 10j in the direction of the reticle IJ. A part of this measurement light is transmitted to the reticle 1 via the projection lens 3j.
Slit-shaped illumination spot (reference mark image) 10 on j
form j′. This illumination spot 10J' moves on the reticle 1j as the stage 5j moves. Then, the center of the illumination spot 10J° and the reticle mark 9J
When the centers of the two lines coincide with each other, the measurement light that passes through the reticle 1j and enters the photoelectric detector 25j reaches its maximum level.

Therefore, the output of the photoelectric detector 25j at this time becomes the maximum output. In other words, Stella 5 which can obtain this maximum output
By determining the position of j, the relative position of reticle IJ in the stellar movement coordinate system is defined.

FIG. 8(a) shows the illumination spot 1 on the reticle 1j.
Stage 5 j 8 between 0j' and reticle mark 9j
Indicates the overlapping state associated with the calligraphy. Lighting spot 10j'
is moving at a constant speed in the direction of the arrow as the stage 5J moves. Further, FIG. 8(b) shows the illumination spot 10
3 shows a change in the output signal of the photoelectric detector 25 as j゛ moves. Center of illumination spot 10J and reticle mark 9
The output signal reaches a maximum when the center of the laser beam j coincides with the center, or becomes a discrete output signal distribution corresponding to each light emission pulse of the excimer laser 30j (for example, a trigger every 016 μm movement of the stage 5j).

The excimer laser used as the light source for exposure light can emit light at a maximum of 200 pp per second at the current state of the art.
s, and 10 ns as the duration of one pulse of light emission
Generally, the light emission duration of one pulse is extremely short compared to the interval between each pulse emission.

[Problem to be solved by the invention] In an exposure device that uses an excimer laser as a light source for exposure light, such as a conventional projection exposure device, as mentioned above, the light emission repetition frequency of the excimer laser is low, so it is difficult to move the stage at high speed. Therefore, it was difficult to perform highly accurate position measurement. In other words, during the pause time of light emission (between pulses), information (photoelectric signal) indicating the relative position between the wafer and the mask cannot be obtained, so the response of the measurement pulse from the stage interferometer 45J is It was necessary to reduce the stage movement speed depending on the characteristics. Therefore, problems such as a long period of time required for relative positioning of the wafer and the reticule occur, which impairs the throughput of the apparatus. Furthermore, each time a slit-shaped mark is scanned, several hundred pulses of light emission are required, which impairs the gas life of the excimer laser.

Also, in order to increase the measurement speed, for example, it is possible to sharpen the transparent part of the resicle mark, or to trigger the excimer laser by scattering the measurement pulse of the interferometer 45 J. In that case, of course the position detection The accuracy of is reduced.

In addition, since the output of the excimer laser for each pulse emission varies, the measurement signal is calibrated (standardized) according to the output for each pulse emission, as shown in JP-A-64-10105.
It was also necessary to do so.

[Means for Solving the Problems] A projection exposure apparatus according to the present invention includes a first illumination optical system that uniformly illuminates a transfer area of a mask with exposure light, and an image of the transfer area that is formed on a predetermined imaging plane. a projection optical system for
a stage movable along the imaging plane; a reference member fixed to the stage and having an opening having approximately the same height as the imaging plane; and a first measuring means for measuring the position of the stage. Equipped with.

Further, a second illumination optical system is provided which forms a projection image on the mask surface via the projection optical system of the aperture by branching the exposure light from the first illumination optical system and guiding it to the aperture and projecting the light. Be prepared. Furthermore, when the stage is moved and the projected image of the opening on the mask surface and the positioning mark overlap, this overlapping state is imaged and the relative positional relationship between the image of the opening and the positioning mark is determined. , a second measuring means for detecting the position of the image of the transfer area projected onto the image plane with respect to the stage.

However, the opening is formed to have a relatively sufficiently larger width in the position measurement direction than the projected image or positioning mark on the mask surface.

[Function] In the projection exposure apparatus according to the present invention, the first illumination optical system is
A certain area including the transfer area of the mask is uniformly illuminated with exposure light. Further, the projection optical system projects an image of the transfer area of the mask illuminated by the exposure light onto a predetermined imaging plane.

The light projection opening is part of a second illumination optical system to be described later, and the exposure light is branched from the first illumination optical system or from the phantom exposure light source itself, and measurement light for position detection is used. is projected toward the mask.

Since the aperture is formed at the same height as the image formation surface of the transfer area of the mask, the measurement light projected from the aperture and incident on the projection optical system forms an image on the mask surface and is reflected in the aperture. Form a projected image. Furthermore, since the aperture is fixed to the stage and the stage moves along the imaging plane of the transfer area of the mask, the projected image of the aperture can move on the mask surface as the stage moves. At this time, a predetermined point on the stage, for example, the position of the reference mark, is always kept open by the first measuring means as the position coordinates of the stage.

In the projection exposure apparatus according to the present invention, the second illumination optical system includes:
Exposure light is branched from the first illumination optical system, guided to the aperture, and projected, and a projected image of the aperture is formed on the mask surface as described above. Further, when the stage is positioned and the projected image of the aperture on the mask surface overlaps with the positioning mark, the second measuring means captures an image of this overlapping state and determines the relative positional relationship between the image of the aperture and the positioning mark. For example, the amount of positional deviation between the two in this overlapping state is determined by the difference. Furthermore, by using this amount of positional deviation and the stop position coordinates of the stage measured by the first measuring means, for example, the amount of movement of the stage required to correct this amount of positional deviation is calculated. At this time, by placing an imaging detector on the image formation plane of the mark image, the amount of deviation can be measured without actually moving the stage. It is possible to determine the positional coordinates of each point on the stencil by autopsy.

Here, the opening is formed such that the projected image of the opening on the mask surface has a relatively sufficiently larger width in the position measurement direction than the slit-shaped positioning mark on the reticle side. The overlapping state of the positioning mark and the projected image of the opening captured by the means results in a relatively dark and thin positioning mark located inside the bright projected image of the opening. By processing this contrast image as an image,
The amount of positional deviation between the center of the positioning mark and the center of the projected image 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 and the center of the projected image of the opening match are calculated.

That is, the relative positional relationship between the opening and the positioning mark with respect to the projection optical system can be detected without particularly positioning the stage so that the center of the positioning mark coincides with the center of the projected image of the opening.

[Embodiment of the Invention] FIG. 1 shows the configuration of an exposure apparatus that is a first embodiment of the invention. Here, the relative position between the reticle (synonymous with mask) 1 and the stage 5 is measured through the projection lens 3 by comparing the reference mark 10 projected on the reticle with the reticle mark 9.

In this exposure apparatus, a reticle 121 having a predetermined circuit pattern and a positioning vehicle 9 is attached to a reticle stage 2, and is projected through a projection lens 3 that is telecentric on both sides (or may be centric on one side). and face stage 5.

The reticle 1 can be moved in the X and Y directions on the reticle stage 2 by a drive motor 42, and the amount of this movement is measured by an interferometer 43. Movement of the reticle stage 2 is used for positioning the reticle 1, which will be described later. The width of the reticle stage 2 is several millimeters or less, and the detection resolution on the interference side 43 is about 0.01 μm.

In reality, three sets of interferometers (laser light wave interferometric length measuring devices) 43 and mirrors 6 are installed to independently detect positions in the X direction, Y direction, and rotation θ direction. Some illustrations are omitted to simplify the explanation. Further, a total of three drive motors 42 are installed corresponding to each direction, and some of them are not shown in the drawings.

The stage 5 is configured to be freely movable by a drive motor 46 along the imaging plane for the reticle 10 and the projection lens 3. The positional coordinates of the stage 5 with respect to the main body of the exposure apparatus are calculated as the distance from a predetermined reference point by measuring the amount of movement of the mirror 7 fixed to the stage 5 using an interference cutter 45. In reality, two sets of interference i((laser light wave interferometric length measuring device) 45 and mirror 7 are installed to independently detect the positions in the X direction and Y direction.A brief explanation will be given here. For convenience, some illustrations are omitted.Also, a total of two drive motors 46 are installed corresponding to each direction.
Similarly, some illustrations are omitted.

The illumination optical system for exposure includes an excimer laser 30, a zoom expander 31, an optical integrator (fly's eye lens) 32, a mirror 33, 35, a relay lens 34,
It is composed of a main condenser lens 36 and the like. Exposure light emitted from the excimer laser 30 is adjusted by a zoom expander 31, an optical integrator 32, and a main condenser lens 36 to have a uniform intensity distribution on the irradiation surface of the reticle 1, and then ) 21 to illuminate a predetermined area of the reticle 1. The beam splitter 21 has a transmittance of 90% and a reflectance of 10% with respect to the wavelength of the exposure light.

The optical system for detecting the position of the reticle 1 is an excimer laser 3
0, mirrors 11 to 14, a light projection 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.

This conditioning light passes through mirrors 12, 13, and 14 to the projection system 8.
The reference mark 10 is emitted upward from the reference mark 10, which is an aperture formed in the conjugate plane of the reticle 1, and is incident on the projection lens 3 to form a projected image (aperture image) of the reference mark 100 on the reticle 1. .

The projected image of this reference mark can be positioned at any point on the reticle 1 by moving the stage 5. The mirror 11 also serves as a shutter for the exposure optical system, and is evacuated from the position shown in FIG. 1 by an unillustrated device or the like during exposure.

An optical system that images and compares the reference mark 10 and the reticle mark 9 projected on the reticle 1 is composed of a beam splitter 21, 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 capture the reticle mark 9 on the reticle 1, and when the stage 5h) moves and the projected image of the reference mark 10 overlaps with the reticle mark 9, this overlapping state is detected by the image sensor 25. The relative position between the reference mark 10 and the reticle mark 9 is measured.

At this time, the measurement light that has passed through the projection lens 3 passes through the transparent portion of the reticle 1 around the reticle mark 9, is partially reflected by the beam splitter 21, and passes through the objective lens 22, half mirror 23, and imaging optical system 24. The image is enlarged and imaged on the image sensor 25.

The detection resolution of this optical system depends on the magnification of the optical system including the objective lens 22, the imaging optical system 24, etc., and the resolution of the image sensor 25. 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 set to be wide enough to capture the image 5 6 of the reference mark IO on the reticle 1.

The objective lens 22 and mirror 23 are fixed on a movable pedestal and are moved in the direction of the arrow by a drive system. Thereby, if the reticle mark 9 is within an appropriate range on the reticle 1, it can be imaged on the image sensor 25.

The half mirror 23 may originally be a simple mirror, but on the grain flow side, the mirror 12 is movable and removed from the optical path, and the exposure light from the mirror 11 is transferred to the half mirror 23, the beam splitter 21, the reticle 1, and the projection lens 3. to position the shot area on the wafer by irradiating the wafer 4 through the
The configuration is also used for die-pie-gui alignment).

Next, position measurement of the reticle 1, reticle alignment, and wafer alignment using the projection exposure apparatus on the wood flow side will be explained.

FIG. 2(a) shows the reference mark 10 on the light projection system 8 fixed to the stage 5 on the wood flow side.

Here, the reference mark 10 is rectangular, 10(a), 0(
b) and two different sizes are set.

FIG. 2(b) shows a reticle mark 9 set in a transparent portion around the transfer area PE of the reticle 1. In FIG. The reticle mark 9 is a light-shielding cross mark, and 9 (a)
, 9 (bl) and 9 (c).

FIG. 2(C) shows a 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 when detecting the position of the reticle 1. Show the trajectory.

The reference mark 10 is set so that the width of the projected image of the reference mark 10 on the reticle 1 is sufficiently wider than that of the reticle mark 9. Further, the crosshairs of the reticle mark 9 are each set to be sufficiently long so that they overlap with the projected image of the reference mark 100 over a wide area.

Now, after the reticle 1 is placed on the reticle stage 2 with FLIR alignment, the position of the reticle 1 is detected and positioned. In this case, the stage 5 is moved by a predetermined program without causing the excimer laser 30 to emit light. As a result, the locus of the projected image of the reference mark 10 becomes the arrow shown in FIG.
(c) Intersects with.

This program also causes the control system 47 to cause the excimer laser 30 to emit light when the projected image of the reference mark 10 reaches the approximate overlap position with each reticle marker 9(a), 9(b), and 9(c). Press the trigger once or multiple times (
2 to 5 shots). At the same time, the position coordinates of the station 5 determined by the interference system 45 at the time of sending out the light emission trigger are stored.

(In the case of sending out multiple triggers, the stage 5 must be stopped during this time.) As a result, the excimer laser 30
emits light, generates measurement light, and gives an image to the image sensor 25''.

Further, the position coordinates of the stage 5 determined by the interference system 45 at the time of sending out the light emission trigger are extracted and stored in the control system 47.

For example, assume that an image as shown in FIG. 3(a) is formed on the image sensor 25 at a position where the projected image of the reticle mark 9(a) and the reference mark 10 roughly overlap. In this case, the horizontal scanning line direction of the image sensor 25 becomes the open side 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. 3(b). By detecting the position of the central recess with respect to the rising edges on both sides of this output signal, the amount of misalignment between the center of the projected image of the reference mark 10 and the reticle mark 9(a) can be determined. Also,
The position of the imaging point of the reticle mark 9(a) through the projection lens 3 is given as the coordinates of the interferometer 45 based on this shift amount and the previously stored stem coordinate values. This operation is performed along with the movement of the stage 5 mentioned above, and the reticle mark 9 (
b) and 9(C) one after another. Thereafter, the coordinates of each reticle mark 9(a), 9(b), and 9(C) are compared with the target value of each coordinate in the control system 47, and the deviation is determined by moving the reticle stage 2 by the drive motor 42. Corrected. At this time, the amount of correction in the X9 0 direction, y direction, and rotational direction of the reticle stage 2 is
3, and the control law 47 is hit.

In the projection exposure apparatus on the wood flow side, in order to align the reticle 1 with the apparatus efficiently and with high precision, the above operation is repeated twice, once for coarse adjustment and once for fine adjustment. Here, the coarse adjustment is performed using the large reference mark 1 on the projection system 8 in FIG. 2(a).
The stage 5 is continuously moved according to the above-mentioned program using the output signal of the image sensor 25 according to 0 (a), and the magnification of the imaging optical system 24 is switched to a low magnification to widen the optic kidney. In addition, fine adjustment is performed using the coordinates of the projection position of each reticle mark 9(a), 9(b), and 9(c) obtained by rough adjustment of the small reference mark 10(b). , 10 (b), or are positioned and stopped at a position apart from each other, and the magnification of the imaging optical system 24 is switched to a high magnification to increase the detection resolution.

By the above procedure, the reticle 1 is aligned with the device. Also, the stage 5 corresponding to each reticle mark 9(a), 9(b), 9(C) after this alignment is completed.
The circuit pattern area PE on the reticle 1 is determined from the position coordinate values of
The positional coordinates of the center position of the projected image are determined and stored.

Furthermore, the residual rotation (rotation amount) of reticle 1 is determined from the coordinates of reticle marks 9 (a) and 9 (c).
An error is detected.

In addition, die-pie-die alignment system (11, 22
, 23, 24, 25, 30) or the distance between the reference mark 10 on the stage 5 and the alignment mark 1 on the wafer 4 measured by an off-axis alignment system (not shown), etc., to project the circuit pattern area PE. The amount of movement of the stage 5 necessary for overlapping the image and the transfer target area on the wafer is calculated. The control system 47 adjusts the position of the stage 5 using the drive motor 46 according to this movement amount. As a result, a relative positioning operation (alignment) between the wafer 4 and the reticle 1 is performed.

In the above operation, the width of one light emission pulse of the excimer laser 30 is about 20 n5ec, and the light emission can be made within 1 μsec after the light emission trigger is sent from the control system 47. Therefore, the reticle mark can be marked without stopping the wafer stage 5. Even if one pulse or light is emitted while the reference mark 10 is scanning the projected position of the reference mark 9 at high speed, sufficiently high precision measurement is possible. At this time, if the light emission 1-rega 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.

Furthermore, by emitting light from the excimer laser 3o several times in a sufficiently stable state after positioning the wafer stage 5, it is also possible to accumulate the same image in the image sensor 25 and average the output signal to improve measurement reproducibility. It is possible.

Furthermore, 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 certain amount in the measurement direction, and the amount of positional deviation is measured, and two or more overlapping images are obtained. It is also possible to calculate the stage position coordinates in which the center of the registration car carriage 9 coincides with the center of the reference mark image, etc. from the displacement amount (movement position) obtained from the displacement amount.

Next, the measurement of the EB rate and distortion in the exposure apparatus of this embodiment will be explained.

The reticle 1 used here includes the above-mentioned reticule
Along with 9, a light-shielding cross mark is formed corresponding to the distortion and magnification measurement position in the area including the transfer area. By detecting the positions of the projected images of these cross marks, the magnification open side and distortion are measured.

After positioning the reticle 1 on the device, the interferometer 45 feeds back the amount of movement according to a predetermined program such that the reference mark 10 passes through each designed imaging point on the imaging lens 3 of the latter cross mark. while moving stage 5. When the center of the reference mark 10 or each imaging point according to this rule is reached as shown in FIG. 4(a), the excimer laser 3° is emitted. The image sensor 25 obtains an output signal as shown in FIG. Calculate the amount of positional deviation. Here, the image sensor 25 detects X! Since it simultaneously outputs output signals in two directions, the ll111 direction and the y-axis direction (two-dimensional sensor), one emission of the excimer laser 30 produces
The amount of positional deviation in two directions, the axial direction and the y-axis direction, is detected.

However, in the vertical scanning direction of the image sensor 25, after scanning one frame, the levels of the pixel rows arranged in the vertical direction are extracted using a cutting circuit or the like to obtain a signal as shown in FIG. 4(b). .

If there is no distortion or magnification error in the projection lens, the center of the cross mark and the center of the luminescent mark either coincide or are usually slightly deviated, and this deviation is the distortion or magnification error.

When measuring this distortion and magnification error, the objective lens 22 is moved by the drive system in a plane perpendicular to the plane of the paper, and images of all the cross marks on the reticle 1 are formed on the image sensor 25. can. As a result, all cross marks on the reticle 1 are measured.

As yet another function of the projection exposure apparatus of this 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, a gap sensor, etc. that opens the amount of movement in the unidirectional direction. The image sensor 2 is moved by moving the stage 5 either up or down.
By zumbling the signal waveform in step 5, the in-focus point is determined from the contrast of the signal waveform and the slope of the unevenness of the waveform, and the height position is measured from the amount of oscillation indicated by the focus detection system, gap sensor, etc. .

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

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 that has passed 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 in FIG. 1. Further, the outside of the transfer area of the reticle 1 is processed into a mirror surface, and the reticle mark 9 is a translucent or absorptive cross formed on this mirror surface.

Exposure light from the reference mark 10 passes through the projection lens 3b, is reflected by the reticle 1b, and then passes through the mirror 26 and the objective lens 22.
b. A person is emitted onto the image sensor 25b via the imaging lens 24b. The second embodiment also provides the same functions and effects as the first embodiment.

FIG. 6 shows a third embodiment of the projection exposure apparatus of the present invention.

In the third embodiment, a 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 going through the reticle 1c. here,
Other configurations not shown are the same as in FIG. 1. Further, the reticle 1c is positioned in advance with high accuracy on the main body of the apparatus by another method.

In the projection exposure apparatus of the third embodiment, after the wafer 4 is pre-aligned and placed on the stage 5, the positions of the plurality of positioning marks set on the wafer 4 are measured using the alignment system 26c. do. As a result, the position of the positioning mark on the wafer 4, that is, the relative positional relationship between the center point of the exposed region (1 to 1) and the reference mark 10 is determined.

Since the positional relationship between the reference mark 10 and the reticle 1c is measured in advance using the light projection system 8 on the stage, the reticle 1c and the wafer 4 are relatively positioned as a result. In addition, 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 a positioning index set inside the alignment system 25c. In the projection exposure apparatus of the third embodiment, the stage 5 is moved after the stellar 5 is moved and the reference mark 1o is captured by the alignment system 25c to store the coordinate position of the reference mark 10. By capturing each positioning mark on the wafer 4 with the alignment system 25C, the distance between each positioning mark and the reference mark 10 is determined by the interferometer 45. In this case, the reference mark 10 needs to have a pattern that can be easily detected by the alignment system, and preferably has the same shape as each positioning mark on the wafer 4.

Further, as a fourth embodiment (not shown), JP-A-64-10
Similarly, in a projection exposure apparatus having an 0FF-AXIs alignment system as shown in No. 105, it is possible to replace the photoelectric detector with a relative position detection system equipped with an imaging function. Thereby, the heel line amount, etc. can be measured in exactly the same way as in the third embodiment.

[Effects of the Invention] In the projection exposure apparatus according to the invention, the coordinates on the stage corresponding to the transfer area on the reticle are measured accurately and efficiently, so the exposure preparation time etc. are shortened and the operating efficiency of the apparatus is improved. will improve.

In addition, the overlapping state is imaged to determine the relative positional relationship between the aperture image and the positioning mark, and the coordinates on the stage of the image of the mask transfer area projected onto the imaging plane are detected from any overlapping state. Therefore, high-speed and highly accurate measurement is possible even when using a light source that emits pulsed light such as an excimer laser. Further, the number of times the light source emits light at this time is much smaller than that of, for example, the projection exposure apparatus disclosed in Japanese Patent Application Laid-open No. 10105/1983. This extends the gas lifetime of the pulsed light source.

Further, in the projection exposure apparatus according to the present invention, since the wafer is not irradiated with exposure light in cases other than exposure transfer, there is no unnecessary exposure of the resist layer of the wafer.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the configuration of a projection exposure apparatus according to a first embodiment of the invention. FIG. 2(a) shows the projector 8 of the projection exposure apparatus of the first embodiment.
FIG. 2(b) is a plan view of the reticule 1, and FIG. 2(c) is a conceptual diagram illustrating a method of positioning the reticule 1 with respect to the main body of the apparatus in the first embodiment. FIG. 3(a) is a conceptual diagram showing an example of an image captured by the image sensor 25 of the projection exposure apparatus of the first embodiment, and FIG. 3(b)
is a conceptual diagram showing the output signal of the image sensor 25 at this time. FIG. 4(a) is a conceptual diagram showing an example of an image captured by the image sensor 25 when the distion is open in the first embodiment, and FIG. 4(b) is an output of the image sensor 25 at this time. It is a conceptual diagram showing a signal. 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 the configuration of a conventional projection exposure apparatus. FIG. 8(a) shows a reticle 1j of a conventional projection exposure apparatus.
FIG. 8B, which is a conceptual diagram showing an example of the overlapping of the projected images of the reticle mark 9J and the reference mark 10j shown above, is a conceptual diagram showing the output signal of the photoelectric detector 25j at this time. [Explanation of symbols of main parts...Regicule 3...Projection lens 4...
Wafer 5...Stage 8...Lighting system
9...Resigil vehicle 10...Reference mark 11-14...Mira 25...Image sensor 30...Excimer laser 34...Relay lens system 36...Condenser lens 45...Interference Total

Claims (1)

[Scope of Claims] A first illumination optical system that uniformly illuminates the transfer area of a mask having a predetermined transfer area and a predetermined positioning mark on the mask surface with exposure light; A projection optical system that forms an image of the transfer area on a predetermined image forming surface, a stage that is movable along this image forming surface, and an aperture for projecting light whose height is approximately matched with the image forming surface. a reference member fixed to the stage, and a first measuring means for measuring the position of the stage, the exposure light being branched from the first illumination optical system and directed to the opening. A second method for forming a projected image of the opening through the projection optical system on the mask surface by guiding and projecting light.
an illumination optical system; when the stage is moved and the projected image of the opening on the mask surface and the positioning mark overlap, the overlapping state is imaged and the image of the opening and the positioning mark are captured; and second measuring means for detecting the position of the image of the transfer area projected onto the image forming surface with respect to the stage by determining the relative positional relationship between the frontage and the mask surface. A projection exposure apparatus characterized in that a projected image thereon is formed to have a relatively sufficiently larger width than the positioning mark in the direction of position measurement.