JPH0413142A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent the printing of a defective image and to improve yield by inspecting the negative image of an original plate pattern formed on a substrate in a nondevelopment state, and detecting foreign matter on an original plate. CONSTITUTION:An image inspecting unit A is provided with a light source for inspecting 20 emitting a luminous flux having a wavelength so as to observe a photochromic image on a wafer 5 and a wavelength zone where an image is not erased. This luminous flux illuminates the transfer region of a reticle pattern on the wafer 5 via a condenser lens 21, a beam splitter 22, and an objective lens for inspecting 23. Its reflected light is made incident on a relay lens 24 via the objective lens for inspection 23, and the beam splitter 22, and is condensed on a light receiving device 25. Then, aftera reticle circuit pattern is once transferred on the wafer, it is projected on the light receiving surface of the inspecting unit, and the output of the light receiving unit 25 is processed by an electric processing system 26 to detect the foreign matter. Thus, the printing of the defective image is prevented, and the yield is improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an exposure apparatus, and particularly to foreign matter other than a circuit pattern attached to an original plate such as a reticle or a photomask during a semiconductor manufacturing process using a light exposure method, such as The present invention relates to an exposure apparatus equipped with a surface condition inspection device suitable for detecting impermeable dust and the like.

[Prior Art] Generally, in the IC manufacturing process, a circuit pattern for exposure formed on a substrate such as a reticle or a photomask is printed on a resist-coated surface using a device (stepper or mask aligner). It is manufactured by transferring it onto eight sides.

At this time, if foreign matter such as dust is present on the substrate surface, the foreign matter will also be transferred at the time of transfer, causing a decrease in the yield of IC manufacturing.

In particular, when a reticle is used to repeatedly print a circuit pattern on eight surfaces using a step-and-repeat method, a single foreign object on the reticle surface is printed onto the entire wafer, which greatly reduces the yield of IC manufacturing. It becomes.

Therefore, in the IC manufacturing process, it is essential to detect the presence of foreign matter on the substrate, and various inspection methods have been proposed. For example, FIG. 2 shows an example of a method that utilizes the property of foreign matter to scatter light isotropically. In the figure, the light beam from the laser 10 is directed upward or downward through the scanning mirror 11 and the lens 12 by entering and exiting the mirror 13, and is incident on the front and back surfaces of the substrate 15 by two mirrors 14 and 45, respectively. and scan mirror 11
The substrate 15 is scanned by rotating or vibrating.

A plurality of light receiving sections 16, 17.18 are provided at positions away from the optical path of direct reflected light and transmitted light from the substrate 15, and output signals from these plurality of light receiving sections 16, 17. Detecting the presence of foreign matter on the top.

In other words, since the diffracted light from the circuit pattern has strong directionality, the output value from each light receiving section is different, but when the light beam is incident on a foreign object, the incident light beam is isotropically scattered, so the output values from multiple light receiving sections are different. become equal. Therefore, the presence of foreign matter is detected by comparing the output values at this time.

Furthermore, FIG. 3 shows an example of a method that utilizes the property that foreign matter disturbs the polarization characteristics of an incident light beam. In the same figure, the light beam from the laser 10 is made into a light beam with a predetermined polarization state through a polarizer 19, a scanning mirror 11, and a lens 12, and is directed upward or downward by moving a mirror 13 in and out.
45 to the front and back surfaces of the substrate 15, respectively, and the scanning mirror 11 scans the substrate 15. Two light receiving sections 21.23 each having an analyzer 20.22 disposed in front thereof are provided at positions away from the optical paths of direct reflected light and transmitted light from the substrate 15.

Then, the difference in the amount of light received due to the difference in polarization ratio between the diffracted light from the circuit pattern and the scattered light from the foreign object is detected by the two light receiving sections 21 and 23, thereby distinguishing between the circuit pattern on the board 15 and the foreign object. Separate.

[Problems to be Solved by the Invention] However, these conventional examples have the following drawbacks in common.

■ Since the method uses a method in which the laser is incident diagonally on the reticle and the scattered light of foreign objects is received, it is possible to remove dust with low scattering efficiency, such as water scale left when cleaning the reticle, flat dust, and light-transmitting dust. The point is that it is difficult to detect.

(2) A He-Ne laser with a wavelength of 633 nm is mainly used as the inspection light. For this reason, some dust may be transparent to this wavelength, but since the burning wavelength is ultraviolet light, light absorption may occur.As a result, when inspecting foreign objects, a reticle with no dust attached may be used. Although it was determined, common defects would occur on the wafer after baking.

In view of the problems of the prior art, an object of the present invention is to
In an exposure apparatus, dust adhering to an original such as a reticle that affects exposure is detected separately from dust adhering directly to a wafer. Another object of the present invention is to prevent the printing of defective images and to improve the yield.

[Means for Solving the Problems] In order to achieve the above object, the exposure apparatus of the embodiment described below uses an exposure transfer method that illuminates the original and transfers the pattern of the original to multiple shot positions on the substrate via a projection optical system. and an inspection means for inspecting a negative image, which is a photochromic image, of the original pattern formed on the substrate by the exposure transfer means to detect the presence or absence of foreign matter on the original.

The exposure transfer means includes, for example, an excimer laser as a light source for illumination.

The inspection means includes, for example, a memory storing data of the pattern of the original, and compares this data with a photochromic image of the pattern of the original formed on the substrate.

Preferably, said inspection means comprises a spatial filter.

When using a plurality of originals having the same pattern, the inspection means simultaneously checks image data of the same pattern portion within one shot and between different shots of at least two shots of photochromic images formed on the same substrate. It is preferable to have two systems of image detection means for detecting images, and a comparison means for comparing image data of the same pattern portion detected by the image detection means.

Alternatively, even when such an original plate is not used, the inspection means may check image data of at least two or more identical pattern portions of each photochromic image formed on the same substrate using at least three original plates having the same pattern. at least two systems of image detection means for simultaneous detection, and
It is preferable to include a comparison means for comparing the image data of the same pattern portions thus detected.

Furthermore, the inspection means includes means for scanning the photochromic image with a laser beam obliquely incident on the photochromic image, and detecting image data of the photochromic image by receiving scattered light emitted by the photochromic image at this time, and further includes a phase difference Preferably, it has a detection means.

[Function] In this configuration, in order to inspect the presence or absence of dust on the original before printing the actual product wafer, a substrate coated with a resist on which a negative image called a photochromic image is formed is used, and an exposure transfer means is applied to the substrate. The original pattern is attached to the grilled carp. The photochromic image of the printed original pattern is then inspected by an inspection means, and it is detected whether or not there is a level of foreign matter on the original that would affect printing. Depending on the characteristics of the negative image, only the dust attached to the light-transmitting areas on the original is detected.

[Example] Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 shows an exposure apparatus according to a first embodiment of the present invention.

In the figure, 1 is a light source for printing such as an ultra-high pressure mercury lamp or an excimer laser, 2 is an illumination system that uniformly irradiates the luminous flux emitted by light source 1 at a predetermined aperture angle, and 3 is an illumination system 2 that illuminates the entire surface. This is the reticle that is used. 4 is a lens for printing, and 7 is a reticle changer. The reticle 3 is sent from the reticle changer 7 to the object plane (exposure stage 6) of the printing lens 4. Reference numeral 5 denotes a wafer, onto which the circuit pattern of the reticle 3 is printed and transferred in a reduced size through a lens 4.

The wafer 5 has a layer (
photochromic material) is applied. A photochromic material is a material whose absorption spectrum changes reversibly upon irradiation with light (photochromism), and A, which is a material typified by spiropyran-based materials, is a photochromic image inspection unit. In this embodiment, after the reticle pattern is transferred onto the wafer 5 in at least a few steps, the wafer 5 is moved by the stage 6 and sent to the image inspection unit A for inspection.

The image inspection unit A includes an inspection light source 20 that emits a light beam (a laser or a halogen lamp (with a color filter) may be used) in a wavelength band that allows observation of the photochromic image on the wafer 5 and does not erase the image. This light flux passes through a condenser lens 21, a beam splitter 22, and an inspection objective lens 23 to an image forming area (
(transfer area of reticle pattern). The reflected light enters the relay lens 24 via the inspection objective lens 23 and the beam splitter 22, and is focused on the receiving light #s25 by the action of the relay lens 24. The surface of the wafer 5 and the light receiving surface of the light receiver 25 are optically conjugate. The light receiver m25 is a position sensor such as a two-dimensional CCD array or a video tube. After the circuit pattern of the reticle, including foreign matter, is transferred onto the -H evaporator, it is projected onto the light-receiving surface of this inspection unit. The pressure of the light receiver 25 is processed by an electrical processing system 26 to detect foreign matter.

FIG. 4 is a block diagram showing the configuration of the electrical processing system 26. The output of the position sensor 25 is sent to the control circuit/driver 40 under the control of an inspection condition setting means, for example, a controller 46 that commands the start and end of the positioning inspection of the wafer 5.
is taken in under the timing management of Amplifier 4.
After being amplified by 1, the signal is digitized by an A/D converter 42, subjected to binarization processing by a binarization circuit 43, and output to a comparison circuit 44. On the other hand, the controller 46
also causes the reticle pattern design data stored in the memory 47 in advance to be read out and output to the comparison circuit 44.

The comparison circuit 44 compares the outputs of the memory 47 and the binarization circuit 43, and if they do not match, it is determined that there is a foreign object and its position and the dog 1 etc. are stored in the memory 45.

Note that a negative image such as a photochromic image has a light absorber formed in the light irradiation area, and has the characteristic that the brightness and darkness of the reticle pattern is reversed. Therefore, even when inspecting only one chip on a wafer, foreign matter that has adhered to the reticle and foreign matter that has adhered to the wafer after exposure can be detected.
This can be determined as follows.

FIG. 5(A) is a horizontal cross-sectional view of a patterned reticle. P and l are foreign substances attached to this. Same figure (
D) shows the design data output SA from the memory 47 for this reticle. On the other hand, the diagram CB) shows the state of a wafer coated with a resist for forming a photochromic image before exposure. If the wafer is inspected in this state, the outputs of the binarization circuit 48 will all be high because the coating with this type of resist is transparent and the reflectance of the substrate is high.

However, when the reticle pattern is transferred onto this,
As shown in FIG. 5C, the exposed portion 5 absorbs the inspection light due to a chemical reaction. A portion PR' corresponding to the foreign matter PR attached to the reticle remains transparent. On the other hand, the foreign matter pw attached to the wafer after exposure prevents the inspection light beam from hitting the Uchihachi substrate, so the output of the binarization circuit 48 in this part becomes low. Therefore, the output SC of the binarization circuit 48 when inspecting the query in the state shown in FIG. 4(C) is shown in FIG. 4(E). Therefore, take this inverted output and combine it with the output SA of the memory 47.
It is possible to determine through inspection that it is a foreign object that has adhered to the final surface.

In addition, in Figure C, the dust P attached to the wafer is
Although it is placed on a non-exposed portion of the wafer, when it is placed directly on an exposed portion, the output SC becomes low due to the characteristics of a negative image. Therefore, it is not affected by Pw.

Returning to FIG. 1, B is an alignment unit for positioning the wafer 5. After the wafer is aligned, it is moved by a predetermined amount by the stage 6 and positioned at the exposure position.

However, there are roughly two methods for finally positioning the wafer with respect to the reticle. One is that after positioning the lens to the exposure position as described above, the printing is performed on the lens 4.
This is a TTL method that performs alignment through That is, this is a method in which unit B is used for pre-alignment of the wafer.

The other method is an off-axis method in which the alignment unit B completes positioning of the wafer outside the exposure position, and the stage 6 transports the wafer to the exposure position with high precision for exposure. For this system, unit B serves for final alignment of the wafer. In any case, its basic configuration is a light source 10, an objective lens 14, and a light receiver 1.
5 and an electrical processing system 16. Then, the light source 10 illuminates a predetermined mark on the wafer through the condenser lens 11, half mirror 13, and objective lens 14, and the mark image included in the reflected light is projected onto the light receiver 15 of the electrical processing system 16 by the objective lens 14. imaged and photoelectrically converted,
By processing this in the electrical processing system 16, the wafer position is detected, and based on the result, the wafer is moved and alignment is performed. Therefore, considering the overall device configuration of the stepper, this alignment unit B may have the function of the photochromic image inspection unit A. By adopting the above configuration, the following effects can be obtained.

■ Since the inspection is performed by actually setting a substrate such as a reticle at the exposure position and printing it onto the wafer, ■ there is no oversight due to the shape of foreign objects, which is a concern with conventional laser scanning methods; There is no oversight due to the wavelength difference between the exposure light and the inspection light, which is a concern with scanning methods. In addition, ■ Since it is equivalent to inspecting at the exposure position, it is not affected by internal emissions during the time when the reticle is transported to the exposure position after inspecting at the reticle changer section as in the conventional case. Because it passes through the lens, it is possible to detect only foreign substances that may affect the product wafer, while also including the performance of the actual printing lens.

■ Since there is no need to take the baked wafer outside the equipment for development, the total inspection time can be significantly reduced. Further, there is no risk of false detection due to failure of pattern edges due to etching processing or the like.

(2) Compared to directly inspecting a reticle, the inspection area on the wafer is only about 115 (determined by the reduction ratio of the printing lens), so the inspection unit can be made more compact.

1! Figure S6 shows a second embodiment of the invention. The difference from the first embodiment is that a spatial filter 31 is used between the beam splitter 22 and the relay lens 24 of the inspection unit A. The advantages of inserting the spatial filter 31 will be described below.

Generally, a circuit pattern on a wafer has many vertical and horizontal images, but when a laser beam is applied to this pattern, diffracted light is distributed in a direction orthogonal to the pattern, as shown in FIGS. 7(A) and 7(B). Therefore, if a spatial filter with a region 81 for blocking these diffracted lights is provided at the exit pupil position of the inspection objective lens 23, as shown in Fig. Vertical and horizontal lines are not imaged above.

On the other hand, since the shape of the foreign object is close to circular, the scattered light from the foreign object passes through the spatial filter and is re-imaged.

Due to the above-described operation, only the foreign matter can be electrically detected while the main circuit pattern on the wafer is erased. In this case, there is no need to compare the design data of the memory 47 in FIG. 4, so the configuration of the electrical system 26 is greatly simplified.

FIG. 8(B) shows a spatial filter provided with a region 82 that is opaque to inspection light in order to optically erase not only vertical and horizontal lines on the circuit pattern but also lines at an angle of 45 degrees.

However, in this case, a drawback arises in that foreign matter adhering to the wafer after exposure is also detected in the same manner as the photochromic image of the foreign matter transferred from the reticle. However, this method involves repeating the reticle pattern onto the wafer twice (2 chips), transferring it to exposure, performing the above inspection on each chip, and checking whether or not foreign matter is detected at the same position on the two chips. Distinguished by examination. If the foreign object is attached to the reticle, it will be detected at the same position on all exposed chips, but the probability that the same size foreign object will be attached at the same position on adjacent chips on the wafer is almost 0.
This is because.

FIG. 8(C) similarly shows an example of 'M3' of the spatial filter 31 placed at the exit pupil position of the light-receiving objective lens 23. This spatial filter is a phase plate used in a phase contrast microscope system.

While the peripheral portion P+ is simply a parallel plane plate, an optical thin film is deposited on the central portion PO so that the phase difference with the peripheral portion is π/2. By using such a phase plate, the phase difference between the exposed portion and the unexposed portion of the photochromic image can be detected as an intensity difference with high contrast on the light receiving surface.

In order to obtain better effects of such a phase difference detection method, a laser is used as the light source 20 in the light projecting section. Then, as in the case of the spatial filter 31, the exit pupil position of the objective lens 23 (but closer to the light source than the beam splitter 22) 32
A diaphragm as shown in FIG. 8(D) is provided. This diaphragm has an opening at the center P2, and the size of this diaphragm is equal to the size of the center P0 of the spatial filter 31 in the arrangement shown in FIG. This is due to the following reason.

Generally, the aperture 32 and the spatial filter 31 are in an optical imaging relationship, so the light beam emitted from one point on the aperture 32 is reflected by the surface onto the sea urchin via the beam splitter 22 and the objective lens 23. , the reflected light returns through the objective lens 23 and the beam splitter 22 and forms an image at a corresponding point in the center of the spatial filter 31. In the phase difference method, this is called 0th order light, and this is because it is necessary to give a strict phase difference to this 0th order light in order to maintain high contrast.

FIG. 9 shows a photochromic image inspection unit according to a third embodiment of the present invention. The difference from the first embodiment is that two sets of inspection optical systems consisting of a light source 20 to a light receiver 25 of a photochromic image inspection unit A are provided in parallel. The distance between the optical axes of the two objective lenses 23 is equal to the pitch P between chips when transferring a reticle pattern onto a wafer multiple times. Unlike the configuration of the electrical processing system 30 shown in FIG. 4, as shown in FIG.
- Comparison is only performed in the comparison circuit 70 via the binarization circuit 43.

Such a method is very effective when a plurality of chips (three chips will be used in the following explanation) are arranged on a ticle (three chips/ticle). The advantages are shown below.

FIG. 11 shows an area where the reticle pattern is repeatedly transferred onto the wafer 5 12 times (for 12 chips 01 to C12). However, in each chip, there are 3 wM identical pattern areas @a to C.

In this case, first, one of the two inspection objective lenses 23 is set in area a of the C1 chip, and the remaining one is set in area A of the C2 chip. Then, corresponding positions in these two areas are sequentially compared. If the two outputs are different, the position PR is stored in the memory 45.

Next, move the wafer and use one of the objective lenses 23 to
Inspect the PR points in area C of the chip. Alternatively, it may be a PR point within the C area of the C1 chip. PR within these three areas
Comparing the outputs of three points, there is an area a where the output differs only at one point.
You can see the PR points within. Finally, P in area a of 02 chip
If the FI point is inspected and the output is the same as that of the C1 chip (abnormal point), it means that foreign matter on the reticle has been repeatedly transferred to the PR point in area a in all chips.

Conversely, if the output of the PR point in area a of the C2 chip is different from that of the C1 chip (abnormal point), the output of the PR point in area a of the C1 chip
Only the inner PR points are considered abnormal. In this case, it is determined that the foreign matter has adhered only to this position on the wafer.

By performing the chip comparison as described above, processing in the electrical processing system is greatly simplified, and since there is no loss of time for reading out design data, processing speed can be increased.

FIG. 12 is a diagram illustrating a case where the above inspection method is applied to one chip/reticle. In this case, three reticles with the same pattern are required. Then, the image RANRc of each reticle is shifted and printed onto one photochromic image forming wafer.

The three areas a'-c in Fig. 11 are images RA to RC in this case.
Corresponding to area 9B, two areas of the stiffness are each comparatively inspected using two objective lenses in the same manner as before.

FIG. 13 shows a photochromic image inspection unit according to a $4 embodiment of the present invention. The inspection method is different from that of the first embodiment. That is, a laser beam is obliquely incident on the wafer 5, the beam is scanned in one direction (perpendicular to the drawing), and the foreign matter scattered light is detected. Then, in synchronization with the beam scan, the wafer 5 is moved in directions S, .

That is, the beam emitted from the laser 80 is expanded by the beam expander 81, and the beam is expanded by the polygon mirror 8.
2. The polygon mirror 82 rotates in a plane perpendicular to the drawing, and as a result, a focused beam is irradiated onto the wafer 5 via the scanning lens 83 and scanned in a direction perpendicular to the drawing. The light-receiving optical system looks at the beam scanning line formed on the wafer 5, and its tip axis is set in a direction that does not pick up the light directly reflected on the surface of the sea urchin.6For example, in Fig. 13, the backscattered light is I try to pick up. wafer 5
The scattered light emitted by the foreign object above spreads in almost all directions, but the light beam captured by the light-receiving objective lens 84 becomes a parallel light beam after passing through the same lens. Of these, the light receiving objective lens 8
The diameter of the luminous flux to be captured is determined by the aperture stop 85 provided at the exit pupil position of No. 4. The scattered light that has passed through the aperture stop 85 is refocused by the action of a reimaging lens 860, and a position that is optically conjugate with the beam scanning line on the wafer is created here.

A slit-shaped field stop 87 is provided at this position, thereby blocking unnecessary flare light beams emitted from areas other than the scanning line on the wafer. The scattered light flux is field aperture 8
7, the light diverges, is made parallel by a condenser lens 88, and is received by a photomultiplier 89.

In this way, by detecting the backscattered light of the obliquely incident laser beam, the S/N between the circuit pattern and the foreign object can be improved.
ratio can be improved. This is because the diffracted light from the circuit pattern is generated along with the directly reflected light R on the upper surface of the wafer 5, and the further it is angularly away from this directly reflected light, that is, the larger θ in the figure, the more it is reduced. This is because if the optical system is arranged as shown, this θ can be made large, so that the accuracy of foreign matter discrimination with respect to circuit patterns can be improved.

FIG. 14 is an explanatory diagram showing a method for further improving the S/N ratio between the pattern and foreign matter.

The beam incidence system and light receiving system may be those shown in FIG. In short, the vertical and horizontal pattern directions of the wafer (V 1V in the figure)
2, Hr H2) L The projection line of the optical axis of the optical system for si on the wafer may form an angle of approximately β=15° in the figure.

The diffracted light of the circuit pattern on the wafer is distributed in the direction orthogonal to the pattern as explained using FIG. The most common directions for circuit patterns are the vertical and horizontal directions, followed by the ±45° direction, followed by the ±30° and ±60° directions.
”. Therefore, the wafer is 15
"If the beam is twisted and received within this plane of incidence, it is possible to avoid the diffracted light from the circuit pattern. Foreign object scattered light is scattered in all directions, so by receiving the scattered light coming in this direction, The detection rate of foreign matter can be significantly improved.

The present invention is applicable not only to a reduction type projection exposure apparatus (stepper) saw, but also to a same-magnification type exposure apparatus and a proximity type exposure apparatus that does not involve a projection system. Moreover, it is not limited to a photochromic image, but also includes a case where a negative image is formed using an image of a developing resist before development, that is, a latent image. At this time, a negative type resist is used.

[Effects of the invention] Since foreign matter on the original is detected by inspecting the negative image of the original pattern formed on the substrate in an undeveloped state, no foreign matter is added to the substrate during post-processes such as development. Furthermore, even if foreign matter is added to the substrate before foreign matter inspection, it can be distinguished from the foreign matter on the original plate by the difference in brightness.

[Brief explanation of the drawing]

5iS1 is a schematic diagram showing an exposure apparatus according to the first embodiment of the present invention, FIGS. 2 and 3 are schematic diagrams showing a foreign object detection method according to a conventional example, and FIG. A block diagram showing the electrical processing system of the device; FIGS. 5A to 5F are explanatory diagrams showing signalization of the reticle and its photochromic image pattern; FIG. 6 is a second embodiment of the present invention. FIG. 7 is a schematic diagram showing a circuit pattern and its diffracted light; FIG. 8 is a schematic diagram showing an example of the spatial filter and aperture of the device in FIG. 6; FIG. 10 is a schematic diagram showing the photochromic image inspection unit according to the third embodiment of the present invention, FIG. 10 is a block diagram showing the electrical processing system of the apparatus shown in FIG. 9, and FIG. 3 chips showing the test procedure used/
Fig. 12 is an explanatory diagram for the case of 1 chip/reticle showing the inspection procedure using the 'NJ9 diagram. Fig. 13 is a photochromic image inspection according to the fourth embodiment of the present invention. FIG. 14 is an explanatory diagram showing an improved version of the fourth embodiment of the present invention. : Light source, : Illumination staff, Reticle, : Printing lens, : Wafer, : Stage, Reticle changer, : Photochromic image inspection unit, : Briar alignment unit, 1: Spatial filter.

Claims (10)

[Claims] (1) An exposure transfer means for exposing and transferring the pattern of the original plate onto a substrate on which a negative image of the pattern is formed, and a negative image of the original pattern formed on the substrate by the exposure transfer means without going through a developing process. 1. An exposure apparatus comprising an inspection means for inspecting and detecting foreign matter on an original. (2) The exposure apparatus according to claim 1, wherein the substrate includes a photochromic film to form a photochromic image as a negative image of the pattern. (3) The exposure apparatus according to claim 1, wherein the substrate includes a negative resist film to form a latent image as a negative image of the pattern. (4) The exposure apparatus according to claim 1, wherein the exposure transfer means includes an excimer laser as a light source for illumination. (5) The inspection means includes a memory storing data of the pattern of the original, and compares this data with a photochromic image of the pattern of the original formed on the substrate. The exposure apparatus described. (6) The exposure apparatus according to claim 1, wherein the inspection means has a spatial filter. (7) The inspection means simultaneously detects image data of the same pattern portion within one shot and between different shots of at least two shots of photochromic images formed on the same substrate using a plurality of originals having the same pattern. 2. The exposure apparatus according to claim 1, further comprising two systems of image detecting means for detecting the same pattern, and a comparing means for comparing image data of the same pattern portion detected by the image detecting means. (8) The inspection means simultaneously detects image data of at least two or more same pattern portions of each photochromic image formed on the same substrate using at least three original plates having the same pattern. Claim 1 comprising a detection means and a comparison means for comparing image data of the same pattern portion detected by the detection means.
The exposure apparatus described. (9) The inspection means includes means for scanning the photochromic image by making it obliquely incident with a laser beam, and detecting image data of the photochromic image by receiving scattered light emitted by the photochromic image at this time. 2. The exposure apparatus according to claim 1. (10) The exposure apparatus according to claim 1, wherein the inspection means includes phase difference detection means.