JP2818074B2 - Pre-alignment equipment for proximity exposure equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of exposing a rectangular glass substrate (hereinafter simply referred to as "substrate") coated with a photosensitive agent , for example, for a liquid crystal display, to a mask and exposing the mask pattern. Regarding proximity exposure equipment that prints on photosensitive agent ,
In particular, before accurate alignment is performed with the substrate and the mask brought close to each other, a pre-alignment that detects a position shift between the substrate and the mask in a state where the substrate and the mask are separated and corrects the position shift Related to the device.

[0002]

2. Description of the Related Art In conventional pre-alignment of a proximity exposure apparatus, two orthogonal side edges of a substrate carried on an exposure stage are brought into contact with a plurality of positioning pins erected on the exposure stage. It is done by letting you do.

[0003]

However, the prior art having such a structure has the following problems. That is, since the edge of the substrate is brought into contact with the positioning pins in order to perform the pre-alignment of the substrate, there is a problem that chips are easily generated at the edge of the substrate. Also,
Since the substrate placed on the exposure stage is moved to hit the positioning pins, the bottom surface of the substrate and the surface of the exposure stage rub against each other, and as a result, dust (hereinafter, referred to as particles) is likely to be generated. There's a problem.

The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a pre-alignment apparatus for a proximity exposure apparatus which does not damage the substrate and does not generate particles in the pre-alignment of the substrate. Aim.

[0005]

The present invention has the following configuration in order to achieve the above object. That is, the invention according to claim 1 is an exposure stage on which the substrate is placed in a proximity exposure apparatus for printing a predetermined pattern drawn on a mask onto a photosensitive agent applied to the surface of the substrate by irradiation of light. Lifting drive means for driving the exposure stage up and down, horizontal drive means for driving the exposure stage in a horizontal plane, and a non-contact state with respect to the substrate carried in above the exposure stage; Position shift detection means for detecting a position shift amount of the edge of the substrate, and before mounting the loaded substrate on the exposure stage, before the exposure stage is driven up by the elevation drive means, or , During ascending drive, or from before ascending drive to during ascending drive,
The horizontal drive unit is controlled so that the exposure stage is displaced in a horizontal plane with respect to the origin position by an amount corresponding to the position shift amount detected by the position shift detection unit, and the substrate is placed on the exposure stage. After the is mounted, the exposure stage is driven up by the elevation drive means, and before the substrate and the mask are set at a predetermined gap, the horizontal drive means is returned so that the exposure stage returns to the origin. And drive control means for controlling.

According to a second aspect of the present invention, the above-mentioned position shift detecting means emits light having a predetermined width to at least three orthogonal edges of the substrate, and a part of the light has a predetermined width. Light emitting means for irradiating obliquely so as to be incident on the
Light receiving means for receiving the light emitted by each of the light emitting means, and position shift amount calculating means for calculating a position shift amount of the edge of the substrate based on light receiving data obtained from each of the light receiving means. It was done.

[0007]

The operation of the present invention is as follows. According to the first aspect of the invention, with respect to the substrate carried above the exposure stage, the positional deviation detecting means detects the amount of positional deviation of the edge of the substrate with respect to the mask in a non-contact state with the substrate. I do. Next, in order to mount the substrate on the exposure stage, the drive is performed while the exposure stage is being lifted by the lift drive means, or before the lift drive, or from before the lift drive to during the lift drive. The control means controls the horizontal drive means, so that the exposure stage is displaced in the horizontal plane from the origin position by an amount corresponding to the displacement amount detected by the displacement detection means. After the substrate is mounted on the exposure stage, while the exposure stage is being driven up until the predetermined gap between the substrate and the mask, or before or before the ascending drive, the ascending drive is performed. In the middle, the drive control means controls the horizontal drive means to return the exposure stage to the origin position, thereby completing the pre-alignment of the substrate.

According to the second aspect of the present invention, the light emitting means installed for detecting at least three orthogonal edges of the substrate emits light having a width to each detection position. Irradiation is performed obliquely so that a part of the light is incident on the substrate. Of the light emitted by the light emitting means, the light deviating from the substrate goes straight. On the other hand, if the light incident on the substrate is a translucent substrate, the light path of the transmitted light is shifted due to refraction when passing through the substrate. If the substrate is not a light-transmitting substrate, light incident on that portion is blocked. Utilizing this property, the light receiving means receives light irradiated off the substrate at each detection position. Since the amount of light received by each light receiving unit changes according to the position of the substrate, the positional deviation amount calculating unit calculates the positional deviation amount of the edge of the substrate based on the light receiving data from each light receiving unit.

[0009]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a front view showing a schematic configuration of a proximity exposure apparatus, and FIG. 2 is a plan view thereof. However, in FIG. 2, the exposure optical section is omitted.

The proximity exposure apparatus holds a substrate loader unit 3 for sequentially loading the substrates 1 coated with a photosensitive agent one by one, and aligns the substrate 1 with a mask 2 for exposing the substrate 1. An exposure unit 4 and a substrate unloader unit 5 for unloading the exposed substrate 1 and temporarily storing the unloaded substrate 1
And an exposure optical unit 6 for exposing the substrate 1 to light.

The substrate loader unit 3 includes a loader robot 32 for sequentially taking out the substrates 1 from the substrate cassette 31. The loader robot 32 moves the loader arm 33 from the loader position LP to the left in the drawing and inserts it into the substrate cassette 31, whereupon the loader arm 33 is lifted,
One of the lowermost substrates 1 of the plurality of substrates 1 stored in the substrate cassette 31 is taken out, carried to the loader position LP, and lowered to the loader arm 33 to be transferred to the substrate transfer machine 7.

As shown in FIG. 2, the substrate transfer machine 7 is arranged opposite to the loader arm 33 and the like, and is constituted by a pair of arms 7 ₁ and 7 _{2 which} can move in synchronization with the substrate transfer direction. I have. The substrate transporter 7 simultaneously carries the substrate 1 into the exposure unit 4 and, at the same time,
So that it can be carried out to the substrate unloader section 5,
At both ends, suction support portions 7a and 7b are provided.

The substrate 1 supported by the suction support portion 7a of the substrate transfer device 7 is carried into the exposure unit 4 by being driven rightward in the drawing. Exposure unit 4 into which substrate 1 is loaded
Detects a positional shift of the substrate 1 with respect to the mask 2 using a sensor described later while the substrate 1 is held by the substrate transporter 7. Note that the mask 2 is installed at a position above the exposure stage 41 by the mask holder 21. Next, the exposure stage 41 is moved up in the Z-direction by a Z-direction driving device 42 as a lifting / lowering driving means, from the origin position by an amount corresponding to the detected positional deviation amount of the substrate 1 as described later. After being displaced in the X, Y, and θ directions, the substrate 1 is further lifted and sucked and held from the bottom surface by the substrate transfer device 7. At the same time, the substrate transporter 7 releases the suction of the substrate 1 and returns to the loader position LP. Further, the exposure stage 41 returns to the origin position in the X, Y, and θ directions while being raised in the Z direction by the Z direction driving device 42 while holding the substrate 1, and the mask 2 and the predetermined gap, for example, Stop 50 to 100 μm apart. After performing the pre-alignment as described above, fine adjustment is performed so that the gap becomes uniform, and further precise alignment is performed using the microscopic optical system. Is printed on the photosensitive agent applied to the substrate 1.

In the exposure optical section 6, for example, light emitted from a xenon (Xr) lamp 61 for ultraviolet irradiation is condensed by a concave mirror 62, the optical path is inverted by an optical path inverting mirror 63, and the light is passed through a fly-eye lens 64. Then, after the optical path is reversed again by the optical path reversing mirror 65, the light becomes parallel light perpendicular to the mask 2 by the Fresnel lens 66, and is irradiated on the surface of the substrate 1 through the mask 2.

When the exposure is completed, the exposure stage 41 is lowered in the Z-direction by the Z-direction drive unit 42 while holding the exposed substrate 1 to release the suction of the substrate 1 and to set the substrate 1 already in standby. The substrate 1 is placed on the suction support portion 7b of the transfer device 7. The exposure stage 41 further includes a Z-direction drive 42
As a result, it descends in the Z direction and waits until the next substrate 1 is carried in. The substrate transfer device 7 on which the substrate 1 is placed sucks and holds the substrate 1 and transports the substrate 1 to the unloader position ULP of the substrate unloader unit 5. While the substrate 1 is being exposed, the next substrate 1 is mounted on the suction support 7a of the substrate transporter 7, and the exposed substrate 1 supported by the suction support 7b is unloaded to the unloader position ULP. At the same time, a new substrate 1 supported by the suction support section 7a is carried into the exposure section 4.

Substrate 1 unloaded to unloader position ULP
Is transferred to the unloader arm 53 when the unloader arm 53 of the unloader robot 52 moves up at the unloader position ULP. When the unloader arm 53 enters the exposed substrate cassette 51, the substrate 1 is stored in the exposed substrate cassette 51.

A sensor for detecting a positional shift of the edge of the substrate 1 in the exposure unit 4 of the proximity exposure apparatus having the above-described configuration will be described with reference to FIGS. 3 is a plan view of the exposure unit 4, FIG. 4 is a rear view thereof, and FIG. 5 is a right side view thereof. In the drawing, reference numerals 43a to 43c denote LDs (laser diodes) as light emitting means for emitting light for measurement. In addition, you may comprise with LED (light emitting diode) etc. other than LD. As shown in the drawing, two LDs 43a to 43c are provided on one side of the orthogonal edge and one on the other side to detect the edge of the substrate 1 loaded. Light having a predetermined width is emitted from each of the LDs 43 a to 43 c from above the edge of the substrate 1 so that a part of the light enters the substrate 1. Of the light emitted from each of the LDs 43a to 43c, light deviating from the substrate 1 is
D43a-43c light-receiving means installed at a position facing each other, for example, C having a function as a one-dimensional line sensor
Light is received by the CDs 44a to 44c.

Next, a driving mechanism as horizontal driving means for driving the exposure stage 41 in a horizontal plane will be described with reference to FIGS. 6 is a plan view showing one of the driving mechanisms, FIG. 7 is a front view thereof, and FIG. 8 is a plan view showing the arrangement of each driving mechanism. The exposure stage 41 is horizontally movably supported by a bottom plate 47 by three support mechanisms 46 using steel balls. On the bottom plate 47, three drive mechanisms 45 for displacing the exposure stage 41 in the X, Y, and θ directions are installed. The drive mechanism 45 will be described with reference to FIGS.

The motor 451 attached to the bottom plate 47
A screw shaft 453 is connected to the output shaft 452, and a nut 454 whose rotation is suppressed is screwed to the screw shaft 453. A member 456 in which a roller 455 is provided so as to protrude partially is connected to the nut 454. The roller 455 partially projecting from the member 456 contacts the transmission member 457 fixed on the lower surface of the exposure stage 41,
The transmission member 457 is urged in the direction of the motor 451 by a tension coil spring 458 and is connected to the bottom plate 47.

When the motor 451 rotates forward, the nut 4
The roller 54 moves straight, and the roller 455 pushes the transmission member 457 to move the exposure stage 41. In addition, the motor 451
Is rotated in the opposite direction, the nut 454 is retracted,
When the transmission member 457 is pulled back by the spring 458, the exposure stage 41 is moved in the opposite direction.

As shown in FIG. 8, two drive mechanisms 45 as described above are provided at both ends of the bottom plate 47 in the X direction, and one drive mechanism 45 is provided at the center in the Y direction, so that the exposure stage 41 is moved to X, Y,
It can be driven in the θ direction. That is, when it is desired to move in the Y direction, only the drive mechanism 45a is driven, and when it is desired to move in the X direction, the drive mechanisms 45b and 45c are driven by the same amount of movement. The movement in the θ direction is realized by driving the driving mechanisms 45b and 45c with a difference in the amount of movement according to the required amount of rotation of the exposure stage 41.

Next, the configuration of a position shift detecting unit using a sensor composed of an LD and a CCD, the configuration of a drive control unit of the exposure stage 41, and their relationship will be described with reference to the block diagram shown in FIG. explain. In the displacement detection unit 70, the CPU 71 for edge detection gives timing control information to the controller 72, calculates the displacement of the board edge based on the measured light reception data, and transmits the data via the communication line 83. Transfer to the communication memory 82. The controller 72 performs switching control of the data memories 73a and 73b, data conversion instruction of the A / D converter 74, channel switching control of the multiplexer 75, light receiving control of the CCDs 44a to 44c, light emission control of the LDs 43a to 43c, and the like. . The multiplexer 75 sequentially takes out the light receiving data from each of the CCDs 44a to 44c. The taken-out light reception data is converted into digital data by an A / D converter 74, and the data is stored in a data memory 73.
a or 73b.

On the other hand, in the drive control unit 80, the CPU 81
However, every time the board 1 is carried in, the board edge position shift data sequentially transferred to the communication memory 82 at regular intervals is extracted from the communication memory 82, and based on the position shift data, as described later. The exposure stage 41 is controlled.

Here, the procedure of measurement by the displacement detecting section 70 will be described with reference to the flowchart shown in FIG. While measuring the measurement timing, check the end instruction of the measurement by stopping the exposure apparatus, etc., and when the measurement timing comes,
The measurement by the CCDs 44a to 44c is started (steps S1, S2).

Each of the CCDs 44a to 44c measures the received light data at regular intervals according to the instruction from the controller 72 (step S3). When the substrate 1 is loaded as described above, each of the LDs 43a to 43c emits light having a width as shown in FIG. Irradiation. As shown in FIG. 3B, light in a portion deviating from the substrate 1 goes straight as indicated by a solid line, and light incident on the substrate 1 is refracted as indicated by a dotted line if the substrate 1 is translucent. If the substrate 1 is not translucent, it is blocked by the substrate 1 and reflected as indicated by a dashed line, and does not enter the CCDs 44a to 44c in any case. Each of the CCDs 44a to 44c has a corresponding L
Among the irradiation light from D43a to D43c, the light that has deviated from the substrate 1 and passed through is received.

When the light reception by the CCDs 44a to 44c is completed, the controller 72 controls the multiplexer 75 to sequentially take out the light reception data measured by the CCDs 44a to 44c, and sends the light reception data to the A / D converter 74.
The received light data converted into digital data is stored in the data memory 73a or 73b (step S4). When the received light data is stored in the data memory,
Based on the stored light reception data, the CPU 71 determines, based on the light reception data stored in the data memory,
The amount of displacement of the substrate edge is calculated (step S5).
The acquisition of the measurement data and the calculation of the positional deviation amount of the substrate edge are executed in parallel for all the CCDs 44a to 44c (step S6), and the calculated positional deviation data is transferred to the communication memory 82 via the communication line 83. (Step S7).

The data memories 73a and 73b store
U71 to calculate the edge misalignment amount and the CCD
It is switched and used to alternately store the light reception data measured in step (1). That is, when the CPU 71 is calculating the positional shift amount of the edge based on the received light data stored in the data memory 73a, the next CCD
Is converted into digital data by the A / D converter 74 and stored in the data memory 73b. When the process of calculating the amount of displacement based on the received light data stored in the data memory 73a is completed,
The position shift amount is calculated based on the received light data b, and new received light data is stored in the data memory 73a during that time.
Hereinafter, the above operation is similarly repeated.

Here, a method of calculating the positional deviation amount of the edge based on the received light data will be described with reference to FIG. FIG. 13A shows a state in which the substrate 1 does not exist and CC
9 shows light reception data measured at D. In the figure, the horizontal axis represents the light receiving position corresponding to the pixels arranged one-dimensionally in the CCD, and the vertical axis represents the amount of accumulated charge corresponding to the amount of received light. That is, the charge amount is high at the position where the light is received by the CCD, and there is no charge amount at the position where the light is not received. Next, the received light data measured by the CCD with the substrate 1 loaded is shown in FIG. As compared with FIG. 13A, the light receiving area is smaller only in the portion indicated by the one-dot chain line. This is because, as shown in FIG. 12B, the light incident on the substrate portion is refracted or reflected by the substrate and is not received by the CCD. This FIG.
Based on the received light data shown in (b), the displacement amount is calculated as follows. That is, by determining the deviation between the predetermined reference origin o and the left rising portion of the received light data, the positional deviation amount of the edge of the substrate 1 is determined.
The reference origin o is measured when light is incident while the edge of the substrate 1 is carried into a position where it should be (a position correctly aligned with respect to a held mask). A light receiving position corresponding to the position is determined. In FIG. 13B, a left rising portion of the received light data is a light receiving position corresponding to an edge position of the substrate 1, and a light receiving position ep corresponding to the reference level SHL of the rising portion and a reference origin o. The displacement amount pz is shown in FIG.
As shown in FIG. 3 (c), the calculation is performed based on the number of pixels in between. For example, if one pixel is 8 μm and the number of pixels between each point is 10, the shift amount pz is 88 μm.

Next, the procedure for controlling the exposure stage 41 will be described below with reference to the flowchart shown in FIG.
First, until the substrate 1 is carried in, it is checked whether the exposure apparatus has been stopped or the like, and when the substrate 1 is carried in, the displacement of the substrate 1 is corrected as follows (Step S).
11, 12).

When the board 1 is carried in, the board edge position shift data transferred from the edge detecting CPU 71 at regular intervals and stored in the communication memory 82 is extracted as described above (step S13).

The driving amounts of the three driving mechanisms 45 provided on the bottom plate 47 of the exposure stage 41 are calculated based on the positional deviation data of each edge taken out, and the driving mechanisms 45 are driven to drive the exposure stage 41. X, Y,
While displacing in the θ direction, the Z direction driving machine 42
The exposure stage 41 is raised (Step S14). The position correction of the exposure stage 41 by each drive mechanism 45 is performed, for example, if the position shift is detected by the CCD 44a.
Therefore, the driving mechanism 45a is driven to move the exposure stage 41 in the Y direction by a distance equal to the positional deviation amount. Also, the CCD 44
(b) If the same amount of positional deviation is detected by the CCD 44c, it means that the carriage has been carried in with a deviation in the X direction, so that the driving mechanism 45b and the driving mechanism 45c are driven to move the exposure stage 41 to the positional deviation. Move in the X direction by a distance equal to the amount. Further, if a positional shift amount of a different length is detected between the CCD 44b and the CCD 44c, it means that the wafer is loaded with a shift in the θ direction, and the exposure stage 41 is rotationally displaced by the angle at which the substrate 1 is loaded. Thus, the drive mechanism 45b and the drive mechanism 45c are separately driven.

As described above, when the exposure stage 41 is displaced upward by the same amount as the positional deviation amount of the loaded substrate 1 and comes into contact with the bottom surface of the substrate 1, the exposure stage 41 sucks and holds the substrate 1 from the bottom surface ( Step S15). At this time, the suction of the substrate transfer device 7 has been released.

After holding the substrate 1 by suction, the exposure stage 4
1 is returned to the original point by being driven by the respective driving mechanisms 45 in the opposite directions by the same amount of displacement in the X, Y, and θ directions in accordance with the above-described displacement amount of the substrate 1. Pre-alignment of the substrate 1 and the mask 2 is completed by returning the exposure stage 41 to the origin. While the exposure stage 41 is returning to the origin, the exposure stage 41
The substrate 1 and the mask 2 are lifted by the direction driver 42 and stopped at a position where a predetermined gap is formed between the substrate 1 and the mask 2 (step S).
16). As described above, in the state where the substrate 1 and the mask 2 are pre-aligned and held close to each other, after being accurately aligned by the microscope optical system, the exposure processing is performed as described above.

In the embodiment described above, the exposure stage 41 is used to reduce the time required for pre-alignment.
While the exposure stage 41 was raised, the exposure stage 41 was displaced in the horizontal plane. However, the present invention is not limited to this, and the exposure stage 41 may be displaced in the horizontal plane, and then raised. The displacement of the exposure stage 41 in the horizontal plane may be performed from before the ascent to during the ascent.

The method of non-contactly detecting the amount of positional deviation of the substrate 1 carried above the exposure stage 41 is not limited to the above-described embodiment, and the position of the substrate may be imaged with a television camera or the like. May be detected.

Further, in the above-described embodiment, the position of the edge is detected by irradiating light from obliquely above the substrate edge. However, the LD and the CCD for detecting the substrate edge are used.
May be vertically arranged opposite to each other across the substrate edge.
In this case, the light incident on the substrate edge is scattered, and a change in the output of the CCD is observed at a portion corresponding to the substrate edge position. By detecting this, it is possible to detect the displacement of the substrate edge. . However, as described in the above-described embodiment, when light is irradiated from obliquely above the substrate edge, the output of the CCD becomes more remarkable as compared with the case where the LD and the CCD are arranged opposite to each other. There is an advantage that the amount of displacement of the substrate edge can be easily detected.

[0037]

As is apparent from the above description, according to the pre-alignment apparatus according to the first aspect, since the displacement of the substrate is detected without contacting the substrate, the substrate is damaged such as chipping. Nothing. Also, when correcting the position of the substrate based on the detected displacement amount, before the substrate is mounted on the exposure stage, the exposure stage is displaced with respect to the origin by an amount corresponding to the displacement amount of the substrate, and thereafter, Since the substrate is mounted on the exposure stage and the substrate is pre-aligned by returning the exposure stage to the origin, the substrate and the exposure stage are not rubbed, and no particles are generated.

According to the pre-alignment apparatus of the present invention, light having a predetermined width is obliquely applied to the substrate edge so that a part of the light enters the substrate.
Since the position shift amount of the substrate edge is calculated by receiving the light that has passed away from the substrate edge, even if the substrate is translucent, the position shift amount can be accurately detected.

[Brief description of the drawings]

FIG. 1 is a front view showing the appearance of a proximity exposure apparatus according to one embodiment of the present invention.

FIG. 2 is a plan view showing the appearance of the apparatus of the embodiment.

FIG. 3 is a plan view showing an arrangement position of a sensor.

FIG. 4 is a rear view showing an arrangement position of a sensor.

FIG. 5 is a right side view showing an arrangement position of a sensor.

FIG. 6 is a plan view showing one configuration of a horizontal drive mechanism of the exposure stage.

FIG. 7 is a front view showing one configuration of a horizontal drive mechanism of the exposure stage.

FIG. 8 is a diagram showing an arrangement of a horizontal drive mechanism of the exposure stage.

FIG. 9 is a block diagram illustrating a configuration of a displacement detection unit, a configuration of a drive control unit, and a relationship between them.

FIG. 10 is a flowchart illustrating a procedure of measurement by a displacement detection unit.

FIG. 11 is a flowchart illustrating a procedure of controlling an exposure stage.

FIG. 12 is a diagram illustrating an optical path of light emitted from an LD.

FIG. 13 is a diagram showing light reception data received by a CCD.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Mask 3 ... Substrate loader part 4 ... Exposure part 5 ... Substrate unloader part 6 ... Exposure optical part 7 ... Substrate transfer machine 41 ... Exposure stage 42 ... Z direction drive machine (elevation drive means) 43a-43c ... LD (Light emitting means) 44a to 44c CCD (light receiving means) 45a to 45c Drive mechanism (horizontal drive means) 70 Position shift detection unit (position shift detection means) 80 Drive control unit (drive control means)

Continuation of the front page (72) Inventor Yasuyuki Koyagi 4-chome Tenjinchi, Horikawa-dori-Terauchi, Kamigyo-ku, Kyoto 1 Dainippon Screen Mfg. Co., Ltd. (72) Inventor Toshimitsu Namba Hashizushi, Fushimi-ku, Kyoto-shi 322 Furukawa-cho Dai Nippon Screen Manufacturing Co., Ltd. Rakusai Plant (58) Field surveyed (Int.Cl. ⁶ , DB name) H01L 21/027

Claims (2)

(57) [Claims] 1. A proximity exposure apparatus for printing a predetermined pattern drawn on a mask onto a photosensitive agent applied to the surface of a substrate by irradiation of light, comprising: an exposure stage on which the substrate is mounted; Lifting drive means for driving up and down; horizontal drive means for driving the exposure stage in a horizontal plane; and a position of an edge of the substrate with respect to the mask in a non-contact state with respect to the substrate carried above the exposure stage. Position shift detecting means for detecting the shift amount, and for mounting the loaded substrate on the exposure stage, before the exposure stage is driven up by the elevation drive means, or during the ascent drive, Or,
From the time before the ascending drive to during the ascending drive, by an amount corresponding to the displacement amount detected by the displacement detection means,
While controlling the horizontal driving means so that the exposure stage is displaced in a horizontal plane with respect to the origin position, after the substrate is mounted on the exposure stage, the exposure stage is driven up by the elevation drive means Before the substrate and the mask are set to a predetermined gap,
And a drive control means for controlling the horizontal drive means so that the exposure stage returns to the origin. 2. A position shift detecting unit according to claim 1, wherein light having a predetermined width is incident on at least three positions of orthogonal edges of the substrate so that a part of the light enters the substrate. A light-emitting unit that irradiates the light obliquely; a light-receiving unit that receives the light emitted by each of the light-emitting units; and a position that calculates a positional shift amount of the edge of the substrate based on light-receiving data obtained from each of the light-receiving units. A pre-alignment apparatus for a proximity exposure apparatus, comprising: a shift amount calculating unit.