JPS63286809A - Substrate exposure equipment - Google Patents

Abstract

PURPOSE:To easily perform positioning of a light transmissive base plate to be exposed and a mask, by placing focuses on reflection marks on the base plate and the mask through the contrast between the dark and pale patterns projected upon the plate and mask. CONSTITUTION:A light transmissive plate 17 which is positioned on the optical axis of a projecting optical system and provided with dark and pale patterns on both surfaces is provided and the dark and pale patterns respectively projected on a base plate 12 to be exposed and mask 13 are received by means of an image sensor 20. Focalizing operations of the base plate and mask are carried out by moving the base plate, mask and an observing optical system relatively to each other so that average contrast values of the dark and pale patterns projected on the surface or back of the base plate 12 and a reflection mark 11 can become equal to each other. Therefore, even if the transmissive base plate having a lower reflectivity is on one side, focalizing operations can be carried out easily and accurate positioning can be made.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a substrate exposure apparatus, and more particularly to a substrate exposure apparatus that allows easy positioning of a mask and a light-transmitting substrate to be exposed.

[Prior Art] Conventionally, an exposure apparatus for a substrate that performs close contact or close exposure has a mechanism for aligning the mask and the substrate in parallel in the exposure section, and prior to exposure, the mask and the substrate are aligned in 11 rows. exposure is performed after being positioned in a minute gap in order to keep the distance between them in a predetermined close or close state.

In this case, the distance adjustment performed as positioning between the mask and the substrate is performed by moving the observation optical system and focusing it on the respective surfaces of the mask and the substrate, and moving the observation optical system 1 unit downward. The distance between the substrate and the mask is set depending on the machine.

For focusing, the electrostatic field fixed to the viewing δ-1 optical system is connected to the observation optical system by electrically detecting the capacitance value of a displacement meter, or by observing the contrast of the reflection pattern with an image sensor. This is done by detecting the amounts of defocus between the surfaces of the mask and the substrate, and moving the substrate minutely in the optical axis direction of the tiJJ optical measurement system in accordance with the detected signals.

The substrate is placed on a substrate chuck, and the above-mentioned parallel alignment mechanism is operated by adjusting the inclination of the substrate chuck, which holds the substrate by a method such as pressure suction.

[Problem to be solved] In the conventional projection reflection method, which detects the contrast of the reflection pattern and recognizes the position of the reflection surface, a reflection mark is required on the substrate. If it is translucent, it may not be possible to provide a reflective mark. In particular, substrates for active liquid crystal display panels in which a large number of thin film transistors are formed at high density, various light-transmissive substrates, and other glass substrates.

When exposing a transparent plastic substrate, etc., various electric circuits, electrodes, etc. are often formed on the surface, and it is necessary to make it transparent. There is no area to provide a reflective mark, and in fact, there is a drawback in that 1--it is not possible to provide a mark, or the area and size of the reflective mark is limited, making it impossible to position with sufficient accuracy.

In addition, if no reflective mark is provided at all, conventionally,
Positioning is performed using the reflective surface on the surface or bottom of the board, but since the reflectance is not high, sufficient imaging signals cannot be obtained, and even in such cases, it is difficult to positioning is not possible.

SUMMARY OF THE INVENTION Therefore, it is an object of the present invention to provide a substrate exposure apparatus that solves the above-mentioned problems and allows easy positioning of a light-transmitting substrate to be exposed and a mask.

[Means for Solving the Problems] The above-mentioned means in the substrate exposure apparatus of the present invention for achieving the object are such that a transparent substrate to be exposed having a predetermined thickness is placed and held. A planar chuck, an observation optical system that observes the substrate to be exposed and a mask, respectively, a projection optical system fixed to the observation optical system, and a projection optical system on both sides of the optical axis -1- of the projection optical system. a translucent plate each having a light and shade pattern, an image sensor that receives the light and shade patterns respectively projected onto the substrate to be exposed and the mask by a projection optical system, and the output signal of this image sensor as human power; The mask is equipped with a drive stage for relatively moving the distance between the substrate to be exposed, the mask, and the observation optical system, respectively, and the mask is provided with a reflective mark, and the mask is provided with a reflective mark that allows the mask to move between the substrate to be exposed and the observation optical system. The substrate to be exposed, the mask, and the observation optical system are moved relative to each other so that the uniform contrast values of the light and shade patterns on both sides of the transparent plate projected on the reflective marks are approximately equal. This is to focus the substrate to be exposed and the mask.

[Function] In this way, a translucent plate is provided on the optical axis -1- of the projection optical system and has a light and shade pattern on both sides of its surface, and the light is projected onto the substrate to be exposed and the mask by the projection optical system. Observe each of the exposed substrate and the mask so that the average contrast values of the shaded patterns projected on the front or back surface of the exposed substrate and the reflective mark are approximately equal. Since the optical system is moved relative to each other to focus the exposed substrate and the mask, the two shading patterns and their average values can be adjusted without being affected by the strength of the shading pattern. Get the contrast
Focusing can be performed at a position where these are equal.

As a result, even if one of the substrates is a translucent substrate that does not have a high reflectance, focusing can be performed easily and positioning can be performed with high precision.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram of a light-transmitting substrate exposure device to which the substrate exposure device of the present invention is applied, and FIG. 2(b) is an explanatory diagram of the relationship between the pattern plate and the pattern, FIG. 3 is an explanatory diagram of the image sensor, and FIG. 4 is an explanatory diagram of the focus control circuit. A block diagram, FIG. 5 is an explanatory diagram of the positioning state of the transparent substrate to be exposed and the mask, FIG. 6 is an explanatory diagram of the focusing state, and FIG. 7 is a flowchart of the positioning process. It is. In each figure, equivalent parts are indicated by the same reference numerals.

In FIG. 1, reference numeral 10 denotes a substrate chuck that is integrated with an XYZ stage that moves in each direction of X1Y1Z, and has a +1-sided surface. It is fixed in a flat state by negative pressure adsorption. The substrate chuck 10 has three
Reflective marks 11 are provided, and the reflective marks 11.11 located on both the left and right sides of the drawing are arranged so as to be located at the center in the backward direction of 1 lil, and the reflective marks 11 located at the front rear of the drawing are: It is arranged so as to be located in the center in the left and right direction.

The substrate chuck 10 is supported by a motor 31 for minutely upward movement as a driving mechanism for focusing, and placed on the chuck mounting table 2LL via the motor 31.
Due to the lack of vertical movement of the chuck mounting table 21, the mask 1 is
3 and the substrate to be exposed 12 are positioned at a predetermined interval.

Note that the moving mechanism for the chuck mounting table 21 is arranged below it, but is not shown in the figure.

The exposed substrate 12 is irradiated with white light, and the reflected light from the reflective mark 11 is received by the observation optical system 15, and the intensity of the image signal S formed on the image sensor is used to detect the exposed substrate 12. Positioning of the surface and the observation optical system 15 is performed. For convenience of explanation - 1-1 In Fig. 1, the mask 13
Although omitted, as shown in FIG.
A mask 13 is provided on top of 2. As shown in FIG. 5, the mask 13 is provided with a reflective mark 14 on its bottom surface.

Reference numeral 15a denotes an objective lens of the observation optical system 15, and the reflected light from the light beam irradiated onto the reflective mark 11 provided on the surface of the substrate chuck 10 through the substrate 12 to be exposed is transmitted through the observation optical system 15. Objective lens 15 a s of system 15
Mirror 15b, half mirror 15c, imaging lens 15
d, and enters the light receiving section 19 provided above the imaging lens 15d of the observation optical system 15. Furthermore, these k
Each part of the IJ optical measurement system 15 and the light receiving section 19 are configured in a fixed relationship as being integrally oriented.

The light receiving section 19 is provided with an image sensor 20, and an output signal from the image sensor 20 is input to a focus control circuit 30. Note that as the image sensor 20, for example, a two-dimensional COD image sensor with 41×14 pixels, a one-dimensional image sensor with 41×1 pixels, or the like is used. Furthermore, in the figure, the objective lens 15a is provided at three locations corresponding to the three reflective marks 11.1.1. is provided. However, in this figure, only the objective lens 15a is shown for the other two;
The other observation optical systems and light receiving units are omitted. Note that the omitted observation optical system and light receiving section have the same configuration as described above.

In this way, without providing three observation optical systems 15, one
Each of the observation optical systems 15 may be moved to three points. The purpose of focusing at three points in this way is to perform flat-shutling between the substrate 12 to be exposed and the mask 13; When only positioning is required, focusing at one point is sufficient.

Further, by moving the substrate 12 to be exposed in the X direction and the Y direction by the substrate chuck 10, the objective lens 15a
The reflective mark 11 can be moved to an optimal position with respect to the light irradiated from the objective lens 15a.
The observation system 15 having the following structure may be moved in the X-Y direction.

The configuration related to such a positioning operation is not directly related to the gist of the present invention, so a description thereof will be omitted.

Next, the light projection system 16 will be explained. This portion of the light projection system 16 is provided in a fixed relationship with respect to the observation optical system 15, and 17 is a pattern plate with a pattern of light and shade stripes drawn on both sides of a glass plate, and lenses 16a, 16
b, and receives parallel light rays from lens 16b. Note that 16c is a lens that diffuses the light from the illumination light source 18.

Note that such a light projecting system 16 is also provided corresponding to the other two observation optical systems described above.

Here, the light (white light) from the light source 18 is transmitted through the lens lee.
, IE3b converts it into a -P row beam, and pattern plate 1
Light up 7. The light and dark striped pattern on both sides -1- of the pattern plate 17 is transmitted to the exposed substrate 1 through the lens 16a1, the half mirror 15c, the mirror 15b, and the objective lens 15a.
Projected onto 2.

Then, when the reflective mark 11 of the substrate chuck 10 coincides with the focal point of the observation optical system 15, the half mirror 17 is set so that the midpoint of the light and shade striped pattern on both sides of the pattern plate 17 is imaged on the surface of the image sensor 20. and objective lens 1
The focal length of the lens lea, which together with the lens 5a constitutes the projection optical system for the dark and light striped pattern, and the distance between the lens lea and the pattern plate 17 are adjusted.

Next, a focus control system for the autofocus gray striped pattern projected on the surface of the reflective mark 11 of the substrate chuck 10-t: will be described.

30 shown in FIG. 1 is a focus control circuit.

This circuit generates a focus error signal from the output signal of the two-dimensional image sensor 20, and controls the substrate chuck 10 in accordance with this focus error signal to cancel out the defocus.
The focus adjustment motor 31 is driven. This motor 31 is, for example, a piezo motor, and is used to finely move the exposed substrate 12 in two directions (upward and downward directions) at high speed for focus adjustment.

Note that the motor for moving the exposed substrate 12 largely in the z' force direction is separately operated by vertically moving a chuck mounting table 21 provided below the motor 31. and,
The signal from the focus control circuit 30 is transmitted to the substrate chuck 1
0 movement and other control of the entire device
2, and the next process to be executed is performed according to the result.

Here, the autofocus shading patterns provided on both sides of the pattern plate 17 are striped patterns as shown in FIG. This is the edge of the dark and light striped pattern, and 17
b is the edge of the dark and light striped pattern provided on the front side of the pattern plate 17 in the light traveling direction. Note that what is shown in correspondence with the left side of the drawing is a state in which a part of the pattern plate 17 is viewed from the front side of the optical axis.

As is clear from this figure, when viewed from the optical axis direction, the dark and light striped patterns on both sides of the pattern plate 17 have a relationship such that edge portions 17a and 17b are arranged alternately at a constant interval W. In this example, a glass plate with a thickness of about 3 vs.
It is about 70 μm. Furthermore, in the pattern board 17, the pattern 17b on the back side (the dotted line area in the drawing) is actually seen as a dark pattern.

FIG. 2(a) shows this in association with the exposed substrate I2, and in order to avoid confusion between the autofocus gray stripe pattern and the circuit already formed on the exposed substrate Lot. When this shading stripe pattern is projected onto the reflective mark 11, this shading stripe pattern is projected onto the exposed substrate 1.
It intersects the X%Y direction, which is the basic lattice direction of No. 2, at an angle of about 45 degrees. In order to clarify this relationship, the reduced outline of the substrate 12 to be exposed is drawn by the chain line 12.
It is indicated by a. Here, most of the circuit pattern on the exposed substrate 12 runs in the X direction or the Y direction.

Furthermore, in order to avoid confusion between the circuit pattern and minute foreign matter already formed on the exposed substrate 10L and the dark and light striped pattern, the width and length of the part and isthmus of the light and dark striped pattern are set to be longer than the circuit pattern and the foreign matter. It is largely determined.

FIG. 3 is an explanatory diagram of the field of view division of the two-dimensional image sensor 20. As shown in this figure, the field of view 20a of the two-dimensional image sensor 20 is formed by a portion 17a of a dark and light striped pattern on the front side.
imaging area A and the cJ section 17 of the gray striped pattern on the front side
The light is received while being divided alternately into the imaging area B of b. Then, the positions of the pattern plate 17 and the two-dimensional image sensor 20 are adjusted so that the corresponding a-light stripe pattern is included in each imaging region.

FIG. 4 is a schematic block diagram of the focus control circuit 30. In this figure, 40 is the two-dimensional image sensor 2
42 corresponds to the imaging area B of the two-dimensional image sensor 20; 42 corresponds to the imaging area B of the two-dimensional image sensor 20; This is an average value circuit for determining the average value (or total value) of pixel output signals.

44 indicates the output signal value of the average value circuit 40 and the average value circuit 42
Find the difference between the output signal value and the focus error signal ER.
This is a subtraction circuit that outputs R. This focus error signal ERR is the front and back light and shade striped pattern 17a projected on the surface of the reflective mark 11.

17b, its absolute value corresponds to the defocus 14, and its polarity corresponds to the direction of the defocus.

46 is a motor driver that drives the focus adjustment motor 31 in accordance with the focus error signal ERR.

48 is a peak passage detection circuit provided to detect that the surface of the reflective mark 11 has entered the autofocus pull-in range, and a focus error signal ERR is provided.
A peak passage detection signal PT is output when the signal passes through a peak that is less than or equal to a predetermined threshold level. This peak passing thrill No. 5 PT is sent to the device control unit 32! >Can be obtained. When the peak passage detection signal PT is generated, the apparatus control unit 32 stops the Z-direction movement (IJi' or lowering) of the substrate chuck 10, and sends an inhibition signal D to the motor driver 46.
E is turned off and the motor driver 46 is activated to start autofocus operation.

That is, from the just focus point to the substrate chuck lO
When the pattern plate 17 is moved down by a certain amount, the pattern plate 17
The imaging plane of one of the light and shade striped patterns on both sides of the image sensor 20 coincides with the surface of the image sensor 20, and the average output signal value (or total value, that is, the average contrast value) is maximum,
Average value (or total value, i.e., average contrast value) of the imaging signals of the front or rear gray stripe pattern
becomes almost zero.

This autofocus operation is performed in the following steps.

First, under the control of the device control unit 32, the substrate chuck 10
is driven upward, and the substrate 12 to be exposed gradually rises.

When the just focus point is approached, the focus error signal ERR increases to a positive peak, and immediately after that, the peak passage detection signal P is sent from the peak passage detection circuit 48.
T comes out.

In other words, the surface of the reflective mark 11 has come within the autofocus pull-in range.

In response to this peak passage detection signal PT, the device control unit 3
2 stops the upward drive of the substrate chuck IO and activates the motor driver 46 by turning off the inhibition signal DE (which has been in the ON state so far).

Here, when the suppression signal DE is turned off, the focus control circuit 30 starts operating. Focus error signal E
When RR has positive polarity, the exposed substrate 12 is
The focus adjustment motor 31 is driven by the motor driver 46 in the raising direction. Conversely, when the focus error signal ERR has negative polarity, the motor 31 is driven by the motor driver 46 in a direction that lowers the substrate 12 to be exposed. In this way, the height of the exposed substrate 12 is finely adjusted so as to keep the focus error signal ERR at approximately zero.

FIG. 6 shows the relationship between the focusing state and the signal level of the image formed on the image sensor 20, and shows the relationship between the focusing state and the signal level of the image formed on the image sensor 20. The objective lens 15a is just at the focus point (focus point) J
When the position is above F, the light and shade striped pattern 17b on the near side is imaged on the surface of the image sensor 20, and as shown on the left side of FIG. and the subsequent bright pattern a
2 (corresponding to the interval between the edge pattern of the front shading stripe pattern 17b and the edge pattern of the front shading stripe pattern 17a) is irradiated with light, and the next part of the previous shading stripe pattern 17a is blurred. Medium brightness pattern a3
appears as The next signal is a bright pattern a4. As a result, the overall average value of the contrast becomes -1- from the level 0 at the center, and the average value only for the imaging area A similarly becomes 4- from the level O.

-, the objective lens 15a is just at the focus point JF
When it's lower. The front side shading striped pattern 17a is imaged on the surface of the image sensor 20, and as shown on the left side of FIG. Light is irradiated in the bright pattern a2, and the next collapsed portion pattern 17a
A clear image is obtained for one part of the pattern, which becomes a dark pattern, turn a3. As a result, the overall average value of the contrast is -1- from the central level O, and the average value only for the imaging area B is also -1- from the level O.

Then, the objective lens 15a is at the just focus point JF.
When they match, the front stripe pattern 17a and the previous stripe pattern 17b are evenly imaged on the surface of the image sensor 20, resulting in a signal as shown in (b), and the average value of the contrast is corresponds to level 0 of

That is, at the just-focus point, the midpoint between the front and rear shading stripes is imaged on the surface of the image sensor 20, so both the front and rear shading stripes are projected onto the surface of the image sensor 20 as pale images, and the pattern plate 17
Each shading pattern 17a provided on the front and back sides of
The average contrast ratio of 17b is approximately 1.

When the ratio of the respective average contrasts becomes 1, that is, when the average contrast values of the light and shade patterns are almost equal, the ERR signal of the subtraction circuit 44 is zero, and at that time, the sum of the front and back amounts of light and shade patterns The average contrast value corresponds to the center level 0.

Incidentally, in this embodiment, the reflective mark 11 of the substrate chuck 10 is used, but such a detection relationship does not change even if the front or back surface of the exposed substrate 12 is used as a reflective surface to form an image on the image sensor 20. Therefore, focus control may be performed using the front surface or the back surface of the substrate 12 to be exposed, but as a better example, an example in which reflective marks 11 are used on the substrate chuck 10 is given here.

That is, the present invention is not limited to providing the reflective mark it on the substrate chuck 10.

° The following is about the autofocus control for the reflective mark 11 on the substrate chuck 10, but the autofocus control for the mask 13 is normally fixed, so the autofocus control shown in FIG. Mask 1
The observation optical system 15 is attached to the reflective mark 14 provided on the bottom surface of 3.
This is performed by moving the IIJ optical measuring system 15 side up and down and using the same control as the focusing of the substrate chuck 10. The only difference is which one to move relative to each other, and there is no substantial difference in focusing.

The mask 13 is fixed to a mask holder 14a, and the mask 13 side is supported by the water \11 in a fixed state, but the mask 13 side is slightly moved, not the observation optical system 15 side, to attach the substrate chuck. When performing focusing similar to IO, the focus control circuit 30 can adjust the position of the mask holder 14a, and for this purpose, a mask focus adjustment motor 33 is provided to adjust the position of the substrate chuck 10.
to drive. This motor 33 is also a piezo motor, and moves the mask 13 in the Z direction (,) -'F for focus adjustment.
It makes high-speed slight movements in the direction of force.

Next, to explain the distance control between the mask 13 and the substrate 12 to be exposed, assuming that the mask 13 side is fixed, simply focus the mask 13 using the reflective mark 14, and then use the observation optical system from that position. The system 15 may be moved down a predetermined distance and focused using the reflective mark 11 of the substrate chuck 10. In this case, since the thickness of the substrate 12 to be exposed is known, it is increased by that amount in addition to the moving distance.

On the other hand, the substrate chuck IO side may be fixed and the mask 13 side may be moved 1-up, and both of these may be moved 1-up.
It may be one that moves upward.

If the mask 13 is movable, as shown in FIG. 5, when aligning the mask 13, the objective lens 15a
Mask 1 the position of IIJ fltll optical system 15 including
3, and move the objective lens 15a to a certain position H2 from the set reference position.
and focus the mask 13 on the mask 13. Then, the observation optical system 1 including the objective lens 15a
5 and move the reflective mark 1 on the substrate chuck 10.
At -1 part of 1, the objective lens 15a is positioned at a certain position H/ from the reference position, and the substrate chuck 10 is focused.

When such positioning is carried out, the distance between the mask 13 and the exposed substrate 12! S is given by 5=H2-Hl-λ, where λ is the thickness of the exposed substrate 12. Note that since the thickness λ is known, the thickness λ can be subtracted from the height H2 in advance during the positioning process, and positioning can be performed in the same way as in the conventional method.

By the way, in this embodiment, focusing is preferred at three points with respect to the substrate chuck 10, so if the mask 13 side is fixed in a water wheel or in a predetermined flat state, then
By focusing at each position, it is possible to simultaneously align the mask 13 with the substrate 12 to be exposed.

If the mask side is also movable, reflective marks may be provided at three points on the mask 13 side including both sides when using the shuttle. In the above embodiment, the motor 31 is provided almost at the center of the substrate chuck 10 for focusing, which was explained as part 1-1, but the focusing and parallelization at the three points are If this is done, motors 31 will be provided at multiple locations so that the respective positions can be adjusted. For example, three motors 31 may be provided at respective positions corresponding to three reflective marks 11;
It may be provided at the four corners of 0. In short, it is sufficient that the motors 931 are provided at a plurality of locations so that the inclination of the substrate 12 to be exposed can be adjusted. Can be served.

Next, the process of the apparatus control section 32, which is provided with motors 31 at a plurality of locations and simultaneously parallelizes and positions the substrate 12 to be exposed, will be described with reference to FIG. In this case,
Reflective marks 14 are also provided on the mask 13 side at three points corresponding to the substrate chuck 10. Its position is to be provided at the center in front of L on both the left and right sides, and the reflective mark 11. ! =ffl, and is arranged so as to correspond to the three observation optical systems 15.

Here, the three observation optical systems 15 are moved up E to control their focus, and these are processed in parallel. First, the focus is adjusted using each of the three reflective marks 14 on the mask 13. ~■, and when the focusing is completed at each of the three points, the optical observation systems 15 (their objective lenses 15a) are simultaneously lowered to a predetermined position 11 from the position corresponding to the positioning in step (2). Note that the predetermined rl at this time is a value in which the thickness n of the exposed substrate 12 is added.

Next, in steps ■ to ■, focusing is performed using the three reflective marks 11 on the substrate chuck 10, and in step ■, the substrate chuck 10 is raised or lowered, the inclination is adjusted, and parallelization is achieved at a predetermined interval. Position.

Through such processing, the substrate 1 to be exposed is exposed to the mask 13.
Parallel alignment can be performed at the same time as positioning in step 2.

As described above in 1-1, the mark on the substrate chuck L can be provided at a convenient position for focusing, and its position is free. In particular, when focusing at one point, the center position of the substrate chuck can be selected, and accurate positioning is possible even at one point.

In FIG. 4 of the embodiment, in order to control the contrast of each shade pattern on the front and back sides of the pattern plate to be equal,
Although a subtraction circuit is used, this may be controlled using a comparator so that the average value of the entire signal becomes a predetermined level (corresponding to level O in the embodiment), or various other methods may be used. control circuit can be used.

In the example, the case where the mask is fixed and the case where the mask is moved so that the mask can be focused are shown, but it is sufficient if either the mask or the substrate is movable. In short, for focusing, it is sufficient that the observation optical system, the mask, and the substrate chuck can be moved minutely relative to each other.Also, regarding the distance between the mask and the substrate chuck, whichever one is movable is fine. In particular, in close exposure or close contact exposure, the masks can be overlapped and aligned at a predetermined distance from a light-transmitting substrate to be exposed.

The function of the focus control circuit in the embodiment is as follows:
It may also be realized by software.

Further, the pattern form of the autofocus gray pattern may be modified as appropriate, and the two-dimensional image sensor for autofocus may be other than the CCD image sensor. Furthermore, the light receiving section is not limited to such an image sensor.

In the example, a light and shade pattern is provided on both sides of a translucent glass plate as an example, but it is also possible to have a shaded pattern on each of the two plates. There is no limitation to the light and shade pattern, and focusing is possible using various patterns. Therefore, the shape of the pattern does not depend on the type. Note that shading also includes the case where a black pattern is drawn on a transparent board at the funeral.

As is clear from the explanation of "Effects of the Invention", the present invention includes a transparent plate which is located on the optical axis of the projection optical system and has a light and shade pattern on both sides of its surface. , the image sensor receives the shading patterns projected onto the exposed substrate and the mask by the projection optical system, and calculates the average contrast value of the shading patterns projected onto the front or back surface of the exposed substrate and the reflective mark, respectively. Since the substrate to be exposed and the mask are focused by moving the substrate to be exposed and the mask relative to each other so that the mask and the observation optical system are approximately equal, the intensity of the signal of the light and shade pattern is Two shading patterns and their respective average contrasts can be obtained without being affected, and focusing can be performed on a position where these patterns are equal.

As a result, even if one of the substrates is a translucent substrate whose reflection ζ is not large, focusing is easy and accurate positioning is possible.

[Brief explanation of drawings]

FIG. 1 shows a light-transmitting substrate exposure apparatus to which the substrate exposure apparatus of the present invention is applied! 11, FIG. 2(a) is an explanatory diagram showing the focus pattern on the pattern board in correspondence with the exposed substrate, and FIG. 2(b) is an explanatory diagram showing the relationship between the pattern board and the pattern. 3 is an explanatory diagram of the image sensor, FIG. 4 is a block diagram of the focus control circuit, and FIG. 5 is an explanatory diagram of the positioning state of the light-transmitting substrate to be exposed and the mask. FIG. 6 is an explanatory diagram of the focusing state, and FIG. 7 is a flowchart of the positioning process. 10...Substrate chuck, 11.14...Reflection mark, 12...Substrate to be exposed, 13...Mask, 15a.
...Objective lens, 1B...Mirror, 17...Half mirror-118...Imaging lens, 19...Light receiving r'l
<, 20... Image sensor, 17... Pattern plate, 30... Focus control circuit, 31. 33... Focus adjustment motor, 32... Device control unit.

Claims (2)

[Claims] (1) In a substrate exposure apparatus that exposes a transparent substrate to be exposed having a predetermined thickness by overlapping masks at a predetermined distance apart, a planar chuck on which the substrate to be exposed is placed and holding it; , an observation optical system for observing the substrate to be exposed and the mask, a projection optical system fixed to the observation optical system, and a shading pattern on both sides of the projection optical system on the optical axis thereof. an image sensor that receives the light and shade pattern projected onto the substrate to be exposed and the mask by the projection optical system, and an output signal of the image sensor as an input; a drive means for relatively moving the distance between the substrate to be exposed, the mask, and the observation optical system, respectively, and the mask is provided with a reflective mark, and the surface of the substrate to be exposed or the observation optical system and each of the substrate to be exposed and the mask so that the average contrast values of the shading patterns on both sides of the transparent plate projected on the back surface and the reflective mark, respectively, are approximately equal; A substrate exposure apparatus characterized in that the substrate to be exposed and the mask are brought into focus by moving them relative to each other. (2) The light and shade pattern is a striped pattern, a reflective mark is provided on the surface of the chuck, a reflective mark of the mask is provided on the bottom surface, and the observation optical system observes the surface of the chuck and the mask, respectively. and each of the chuck and the mask such that the average contrast ratio of the striped patterns on both sides of the transparent plate projected on the reflective marks of the chuck and the reflective mark of the mask is approximately 1. 2. The substrate exposure apparatus according to claim 1, wherein the chuck and the mask are brought into focus by moving the observation optical system relative to each other.