JP2004233473A - Apparatus and method for assembling large substrates - Google Patents

Abstract

When manufacturing a liquid crystal display device, a substrate assembling apparatus capable of manufacturing a plurality of display devices at once by enlarging a substrate to be used is desired.
A lower frame and an upper frame are provided on a gantry, and a first Z-axis driving mechanism is provided on the lower frame side for largely moving the upper frame up and down. A lower chamber is provided inside the lower frame, and an upper frame is provided. A second Z-axis driving mechanism for vertically moving the lower table provided in the lower chamber below the lower chamber by providing an upper chamber inside the upper chamber; A drive mechanism for moving the lower table in the horizontal direction is provided on the side surface, and the upper frame and the lower frame are combined to form a vacuum chamber by combining the upper and lower chambers via a seal ring.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a device for bonding two substrates such as a liquid crystal display device, and more particularly to a substrate assembly device for bonding substrates having a large area of 1 m or more on one side and a method for assembling the same.
[0002]
[Prior art]
As a conventional large substrate assembling apparatus, there is one described in Japanese Patent Application Laid-Open No. 2002-318378. In this apparatus, the upper container that forms the vacuum chamber by supporting the upper substrate is configured to be rotatable, and the upper substrate is received and held on a table provided in the upper container facing upward, and then rotated, and then the lower substrate is rotated. The lower substrate is placed on a table that supports the substrate, the lower container is moved to the upper container position, and the lower container is combined with the upper container to evacuate the upper and lower containers. For this reason, the lower container is configured to be connectable and detachable to an exhaust pipe or the like for evacuating the combined container after the movement.
[0003]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2002-318378
[Problems to be solved by the invention]
By the way, in the configuration of Patent Document 1, in order to rotate the upper container holding the upper substrate, a space for the rotation is necessarily required, and therefore, an increase in the size of the apparatus is inevitable.
[0005]
In addition, since the lower container is movable, it is necessary to connect an exhaust pipe for evacuation when the upper and lower containers are combined, and to connect the moved container after the movement. Could occur.
[0006]
SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and provides a board assembling apparatus and an assembling method capable of assembling a board with small size and high accuracy.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, a lower frame and an upper frame are provided on a gantry, and a first Z-axis drive mechanism for largely moving the upper frame up and down with respect to the lower frame is provided. A lower chamber constituting a vacuum chamber inside the frame is provided with an upper chamber inside the upper frame, an upper table is provided inside the upper chamber, and a lower table provided in the lower chamber below the lower chamber is moved up and down. A second Z-axis drive mechanism for minute movement is provided, and a drive mechanism for horizontally moving the lower table is provided on the side of the lower chamber, and the upper and lower chambers are combined by combining the upper and lower frames. It was configured to form a vacuum chamber by uniting via a seal ring.
[0008]
Also, when holding the substrate on the upper and lower tables, the substrate center width direction is held on the substrate, and then the substrate is sequentially sucked from the center in the length direction to one end side toward the end, When the suction to one end is completed, the suction is sequentially performed toward the other end, so that the substrate can be maintained without distortion and with little residual air between the substrate and the table.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[0010]
FIG. 1 is a vertical sectional view of an embodiment of the substrate assembling apparatus of the present invention. The substrate assembling apparatus is configured such that the lower frame 2 and the upper frame 25 provided on the gantry 1 are used as rigid support members, and the upper chamber 21 and the lower chamber 4 are provided inside the lower frame 2 and the upper frame 25. The upper frame 25 is rotated by driving the ball screw 12 of the first Z-axis drive motor 11 constituting the first Z-axis drive mechanism (upper unit drive mechanism) provided on the lower frame 2 side. The upper frame 25 moves up and down with respect to the lower frame 2 via the ball screw receiving portion 13 provided on the lower frame 2. A substantially conical groove 30 is provided on the lower frame 2 side so as to fit into the projection 31 provided on the upper frame 25 side, but the upper frame 25 moves downward and rides on the lower frame 2. A mechanism for fixing the lower frame 2 and the upper frame 25 may be installed later.
[0011]
On the gantry 1, a lower chamber support member 4P for supporting the lower chamber 4 inside the lower frame 2 is provided. Below the lower chamber 4, a lower connection base 3 is provided on a second Z-axis guide 6 attached to the gantry 1. A rotating wheel is provided below the lower connection base 3, and the rotating wheel is driven by a second Z-axis drive motor 5 provided on the gantry 1 and moves on a moving member 5 b having a taper in the left-right direction in the figure. A second Z-axis drive mechanism (table fine movement mechanism) is provided for moving the lower connection base 3 up and down by rolling to apply a pressing force between the substrates.
[0012]
In the present embodiment, the vertical drive mechanism (second Z-axis drive mechanism) of the lower table 7 is configured as described above. However, the present invention is not limited to this configuration. A mechanism that can move up and down directly by a motor or a mechanism that uses hydraulic pressure or air pressure may be used as long as the mechanism can move with high accuracy of about mm. As an example of this, FIG. 4 shows a structure provided with an upper table fine movement mechanism (second Z-axis driving mechanism) capable of moving the upper table 20 up and down with high accuracy. In this structure, the linear actuator 60 is installed on the upper frame 25, and the plate 61 can be moved up and down. The plate 61 is fixed to the connection plate 23 via the load cell 24 so that the applied pressure can be detected by the load cell 24. Note that, instead of the linear actuator 60, a vertical movement mechanism using a ball screw, an air cylinder, or the like may be used. By providing the first Z-axis drive mechanism (coarse movement mechanism) and the second Z-axis drive mechanism (fine movement mechanism) for largely moving the upper table up and down, a horizontal drive mechanism is provided on the lower table side. Only the (positioning mechanism in the XYθ directions) needs to be provided, and it is not necessary to consider the vertical movement of the lower table 7 in the horizontal driving mechanism, and the positioning accuracy is improved.
[0013]
Returning to FIG. 1, a plurality of lower shafts 8 are mounted above the lower connection base 3 to support the lower table 7. Each lower shaft 8 projects into the lower chamber 4 via a vacuum seal in order to maintain airtightness with the lower chamber 4. Further, an XYθ moving unit 10 configured to be independently movable in the XYθ directions is attached between each lower shaft 8 and the lower table 7. Note that the XYθ moving unit 10 may be constituted by a mechanism using a ball bearer or the like that is fixed vertically and freely movable in the horizontal direction. A plurality of lower table horizontal driving mechanisms 9 are provided outside the lower chamber 4 in the horizontal direction (X, Y directions) of the lower table 7, and the lower table side surface (the thickness direction of the lower table) is set by an axis provided in the driving mechanism. It is configured so that positioning in the XYθ direction can be performed by pressing. The movement of the lower table 7 in the Z-axis direction is performed by raising and lowering the lower connection base 3 by the above-described second vertical drive mechanism. The tip of the shaft that comes into contact with the lower table in the lower table horizontal drive mechanism 9 is formed of a wheel-shaped or low-friction material that rotates up and down so that there is no resistance even if the lower table moves up and down. In the structure for moving the upper table 20 up and down as shown in FIG. 4, the shaft end of the horizontal drive mechanism 9 may have a structure in which only the lower table is pushed by seven.
[0014]
Further, a seal ring 14 is provided at a connection portion between the lower chamber 4 and the upper chamber 21 so that the upper and lower chambers are united to prevent leakage of air when the inside is exhausted.
[0015]
The upper chamber 21 is mounted inside the upper frame 25. An upper connection plate 23 is provided above the upper frame 25, and a plurality of load cells 24 are provided between the upper connection plate 23 and the upper frame. Further, the upper connection plate 23 is provided with a plurality of upper shafts 26 toward the inside of the upper chamber in order to support the upper table 20. The upper shaft 26 and the upper chamber 21 are connected by a vacuum seal to maintain the pressure in the chamber. Further, between the upper shaft 26 and the upper frame 25, there is provided a shaft guide 27 which can move in the vertical direction and has no backlash in the horizontal direction. With this structure, the upper table 20 and the upper frame 25 can be regarded as a fixed state, and the load cell 24 can detect the force when the substrate is pressed.
[0016]
A camera 22 for detecting a position mark provided on the substrate is fixed to the upper connecting plate. By fixing the camera 22 to the upper connection plate 23 in this manner, the distance between the camera 22 and the upper table 20 does not change. It is not necessary to adjust the focus of the position mark of the upper substrate held on the upper table 20 of the upper substrate 22.
[0017]
The distance between the upper and lower tables when the vacuum chamber is formed by combining the upper and lower chambers may be a distance (several mm) at which a pressing force can be applied to the substrate, and the distance for lifting the lower table by the second Z-axis driving mechanism is sufficient. Pressing can be applied by moving. Therefore, it is not necessary to take a large volume in the vacuum chamber, and the time required for decompression can be shortened. As described above, the pressing force can be measured by the load cell 24 provided on the upper table side.
[0018]
In addition, as described above, in the present embodiment, the upper table 20 and the lower table 7 are arranged separately from the upper chamber 21 and the lower chamber 4, so that when the pressure in the chamber is reduced, the chamber is deformed. The substrate can be held horizontally without transmitting to the table.
[0019]
Further, the portions on which a large force acts, such as the gantry 1, the lower frame 2, and the upper frame 25, are made of a rigid body, but the lower chamber 4 and the upper chamber 21 are square pipes so as not to be greatly deformed when the pressure in the chamber is reduced. The structure is used to reduce the weight of the entire apparatus.
[0020]
Although not shown in the drawing, a method of holding a substrate with suction holes for suction suction by negative pressure or a method of providing an electrostatic chuck on the table to hold the substrate by electrostatic suction force is used for holding the substrate. Alternatively, a method in which an adhesive is provided on the table side to hold the adhesive is considered. In particular, in the case of using suction suction by negative pressure, the suction force is reduced when the pressure in the chamber is reduced. Therefore, it is preferable to use the suction force together with the electrostatic suction force or the adhesive force.
[0021]
Next, a procedure for assembling the substrate according to the present invention will be described.
[0022]
First, the upper unit drive mechanism is operated to insert a substrate, and the upper frame 25 is separated from the lower frame 2 in order to provide a space enough to hold the upper table 20 and the lower table 7. This operation distance is about 100 to 200 mm. In addition, when performing maintenance or cleaning of the inside of the chamber, the operability is improved by separating the chamber by about 200 to 300 mm.
[0023]
Next, the upper substrate 33 is suction-held on the upper table 20 according to the procedure shown in FIG. In the embodiment of FIG. 2, the left-right direction is the longitudinal direction of the substrate, and the front-rear direction is the width direction of the substrate. That is, the upper substrate 33 with the bonding surface facing the lower table 7 is carried into the lower surface of the upper table 20 using the robot hand 50. At this time, the upper substrate 33 is carried under the upper table 20 in a state where the center is bent (a downwardly convex state) as shown in FIG. In this state, the plurality of suction support nozzles 40 provided in the width direction at the center of the upper table 20 are lowered to the bending surface of the substrate as shown in FIG. I do. Thereafter, as shown in FIG. 2B, the support nozzle 40 is retracted until the suction surface of the support nozzle 40 becomes the same as the surface of the upper table 20, and negative pressure is applied to the suction suction hole near the center of the upper table 20. To partially adsorb the central part of the upper substrate.
[0024]
Next, as shown in FIG. 2 (3), the support nozzle 40 is protruded toward one end side in the longitudinal direction of the upper substrate to the surface of the upper substrate 33 to perform suction suction. Then, the protruding support nozzle 40 is retracted until the suction surface becomes the upper table 20 surface, and a negative pressure is also supplied to the surrounding suction suction holes. At this time, the other end of the upper substrate in the longitudinal direction is still supported by the robot hand 50. Therefore, the support nozzle 40 is made to protrude from the other end of the upper substrate, and the other end of the upper substrate is suction-adsorbed to the tip of the support nozzle. Thereafter, the support nozzle 40 is retracted until the tip of the support nozzle 40 reaches the upper table surface position, and a negative pressure is supplied to the suction suction holes around the support nozzle 40 to hold the substrate on the upper table surface. In this state, if the upper table 20 is provided with an electrostatic attraction mechanism, the electrostatic attraction is performed with a small voltage. If an adhesive holding mechanism is provided, the adhesive member is lowered to the upper table surface and held. Note that the substrate may be held in the procedure of (1) to (5) by using an adhesive mechanism without using the suction / suction mechanism.
[0025]
By holding the upper substrate in the above-described procedure, the substrate can be held without bending remaining on the upper substrate and without leaving an air layer between the substrate and the upper table surface. If the flexure remains, the position of the alignment mark provided on the substrate is shifted and accurate bonding cannot be performed. Also, if an air layer remains between the substrate and the upper table surface, when the pressure in the vacuum chamber is reduced, the residual air expands, and when the substrate cannot be held or an electrostatic attraction force is applied, A discharge phenomenon may occur, damaging the substrate. Note that, in the description of FIG. 2, the suction support nozzle 40 sucks in the width direction at the center of the substrate, and then sucks toward the end in the longitudinal direction. May be provided in the longitudinal direction at the center of the substrate, suctioning the longitudinal direction at the center of the substrate, and then adsorbing toward the end in the width direction.
[0026]
FIG. 3 shows a procedure for holding the lower substrate on the lower table. After adsorbing and holding the upper substrate 33 on the upper table 20, if there is a liquid crystal substrate that has been bonded to the lower table 7, the support pins 45 provided on the lower table 7 are made to protrude from the table surface, and Is lifted from the lower table surface so that the robot hand 50 can be inserted below the liquid crystal substrate. Then, the liquid crystal substrate is discharged out of the vacuum chamber by the robot hand 50. Thereafter, as shown in FIG. 3A, an adhesive (sealant) is applied to the surface of the lower substrate 34 in a ring shape, and the liquid crystal is dropped on a region surrounded by the adhesive. Is carried in by the robot hand 50 and placed on the support pins 45. In the above description, the adhesive is provided on the lower substrate. However, the adhesive may be provided on the upper substrate or on both the upper and lower substrates.
[0027]
Next, as shown in FIG. 3 (2), among the support pins 45, the support pins 45 installed on the center line of the lower table 7 are retracted toward the lower table until the tips of the support pins 45 are on the table surface, and the suction holes in the center are formed. And maintain the vicinity of the center. Thereafter, as shown in FIG. 3 (3), the other support pins 45 are gradually retracted toward one end. A negative pressure is also sequentially supplied to the suction holes near the support pins that have retreated as the support pins 45 retreat. When the suction holding at one end is completed, the other support pins 45 are similarly retracted toward the other end, and a negative pressure is supplied to the suction holes, so that the entire lower substrate is suction-adsorbed to the lower table 7. Hold. In the above description, after the respective support pins 45 are retracted, the substrate portion that is in contact each time is attracted to the lower table 7 by negative pressure. However, all the operations of the support pins 45 are completed, and the entire lower substrate is moved to the lower table. The negative pressure may be applied after contact with the negative electrode 7. By placing the substrate on the lower table surface from the center toward the one end in this way, no air layer remains between the substrate and the table surface, and the substrate can be securely adsorbed on the table surface, and the inside of the chamber can be maintained. In the process of reducing the pressure, the substrate does not come off and no displacement occurs.
When the upper and lower substrates are respectively held on the upper and lower tables, the upper unit driving mechanism is operated to combine the upper frame 25 with the lower frame 2. At this time, the upper chamber 21 and the lower chamber 4 are united together via the seal ring 14 to form a vacuum chamber. At this time, the interval between the upper and lower substrates is set to about several mm. With the vacuum chamber formed, the amount of displacement of the positioning marks provided on the upper substrate 33 and the lower substrate 34 is obtained by using the camera 22 having a large depth of focus provided on the upper unit side. However, when the depth of focus of the camera 22 is shallow, a mechanism for vertically moving the camera 22 is provided. First, the positioning mark of the upper substrate 33 is recognized, and then the camera 22 is moved downward to move the positioning mark of the lower substrate 34. And a method of determining the amount of displacement of the positioning marks on the upper and lower substrates by recognizing the difference. Thereafter, by driving the motor of the lower table horizontal drive mechanism 9, the lower table 7 is moved to correct the displacement of the upper and lower substrates in the XYθ directions.
[0028]
When the positioning of the upper and lower substrates is completed, although not shown in FIG. 1, the air in the vacuum chamber is exhausted from the exhaust port provided on the lower chamber 4 side to reduce the pressure in the vacuum chamber. When the inside of the vacuum chamber is decompressed to pressurize, the second Z-axis driving mechanism provided at the lower outside of the lower chamber 4 is operated to move the lower table 7 to the upper table 20 side via the lower connection base 3. The substrates are bonded by applying a pressing force to the substrates by moving them. In some cases, the substrates held on both tables may be displaced during the pressurization, and it is better to correct the displacement by observing the positioning marks from time to time. Further, when the substrate is held by the electrostatic suction mechanism together with the suction suction, the substrate was held at a low voltage (about 500 V) in the atmosphere during the process of depressurizing the inside of the vacuum chamber. Then, if the voltage applied to the electrostatic chuck is increased to several kilo volts and the chuck is attracted, discharge and the like can be reliably prevented.
[0029]
When the upper and lower substrates are pressed and the bonding is completed, a UV irradiation mechanism (not shown) is operated in this state to cure the adhesive at a plurality of locations and temporarily fix the adhesive. Thereafter, the atmosphere is introduced into the vacuum chamber to return to the atmospheric pressure. When the substrate is temporarily fixed and returned to the atmospheric pressure, the substrate is returned to the atmospheric pressure, so that a pressing force is further applied, and the substrate is pressed to a specified thickness. In this state, the entire adhesive is cured by the UV irradiation mechanism, and the bonding of the liquid crystal substrates is completed.
[0030]
When bonding of one set of substrates is completed, as described above, preparation for bonding of the next substrate and discharge of the completed liquid crystal substrate are performed.
[0031]
As described above, when the substrate assembling method of the present invention is used, the bending of the substrate that occurs when the large substrate is held on the table can be prevented, and highly accurate positioning can be performed. In addition, residual air that is easily generated between the substrates can be almost eliminated, and is generated when a part of the substrate comes off the table or is electrostatically attracted due to the effect of the residual air when the pressure in the vacuum chamber is reduced. The occurrence of a discharge phenomenon can be suppressed.
[0032]
【The invention's effect】
As described above, with the configuration of the substrate assembling apparatus of the present invention, the volume of the vacuum chamber can be reduced, and the entire apparatus can be reduced in size and weight.
[0033]
In addition, since the camera for observing the alignment mark is moved together with the upper table, there is no need to adjust the drive mechanism for aligning the camera and the focal position of the camera each time the upper table is moved. The work time required for the alignment can be reduced.
[0034]
Further, by using the assembling method of the present invention, the bending of the substrate that occurs when the large substrate is held on the table can be eliminated, and the bonding of the upper substrate and the lower substrate with high positioning accuracy can be realized. Furthermore, since the generation of residual air between the substrate and the table can be suppressed, it is possible to prevent the substrate from falling or falling when depressurizing, and to prevent discharge when using electrostatic suction, and achieve highly reliable bonding. it can.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of an overall configuration of a substrate assembling apparatus of the present invention.
FIG. 2 is a diagram illustrating a procedure for holding an upper substrate on an upper table.
FIG. 3 is a diagram illustrating a procedure for holding a lower substrate on a lower table.
FIG. 4 is a schematic view of an overall configuration of a substrate assembling apparatus according to another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Stand, 2 ... Lower frame, 3 ... Lower connection base, 4 ... Lower chamber, 5 ... Second Z-axis drive motor, 6 ... Second Z-axis guide, 7 ... Lower table, 8 ... Lower shaft, 9 Lower table horizontal drive mechanism, 10 XYθ moving unit, 11 first Z-axis drive motor, 12 ball screw, 13 ball screw receiver, 14 seal ring, 20 upper table, 21 upper chamber, 22 camera , 23 ... Upper connection plate, 24 ... Load cell, 25 ... Upper frame, 26 ... Upper shaft, 27 ... Shaft guide, 60 ... Linear actuator, 61 ... Plate.

Claims (8)

Providing a lower frame and an upper frame on a gantry, providing a first Z-axis driving mechanism for largely moving the upper frame up and down relative to the lower frame, and a lower chamber constituting a vacuum chamber inside the lower frame. A second Z-axis drive mechanism for providing an upper chamber inside the upper frame, providing an upper table inside the upper chamber, and vertically moving a lower table provided in the lower chamber below the lower chamber. A drive mechanism for moving the lower table in the horizontal direction is provided on the side of the lower chamber, and the upper and lower chambers are united via a seal ring by forming the upper and lower frames together to form a vacuum chamber. A large-sized board assembling apparatus characterized in that: Providing a lower frame and an upper frame on a gantry, providing a first Z-axis driving mechanism for largely moving the upper frame up and down relative to the lower frame, and a lower chamber constituting a vacuum chamber inside the lower frame. A second Z-axis driving mechanism for providing an upper chamber inside the upper frame, providing an upper table inside the upper chamber, and vertically moving the upper table provided in the upper chamber slightly above the upper chamber. A driving mechanism for moving the lower table in a horizontal direction is provided on a side surface of the lower chamber, and the upper and lower chambers are united via a seal ring by forming the upper and lower frames together to form a vacuum chamber. A large-sized board assembling apparatus having a configuration. The apparatus for assembling a large-sized board according to claim 1 or 2,
The apparatus for assembling a large substrate, wherein the lower frame and the upper frame are formed of a rigid body, and the upper chamber and the lower chamber are formed of a square pipe structure. The apparatus for assembling a large-sized board according to claim 1 or 2,
An apparatus for assembling a large substrate, wherein the upper table and the lower table are supported by members separate from the upper chamber and the lower chamber. The apparatus for manufacturing a large-sized substrate according to claim 1 or 2,
A large substrate assembling apparatus, wherein a camera for observing the alignment marks of the substrates held on the upper table and the lower table moves integrally with the upper table. The substrate is held on the upper table and the lower table provided in the vacuum chamber, and a sealing material is applied to at least one of the substrates, and the liquid crystal is dropped on the surface of the substrate held on the lower table. In the method of assembling a large-sized substrate in which the pressure in the chamber is reduced and the distance between the two tables is reduced, the substrates are attached to each other to assemble the liquid crystal substrate.
When holding the substrate on the upper table, first, a plurality of support nozzles in the width direction of the center of the upper table are lowered near the substrate surface to suck the substrate, and the tip of the support nozzle is retracted to the upper table surface. A negative pressure is supplied to the suction hole near the central portion to suck the central portion of the substrate, and then a support nozzle is sequentially protruded from one side of the substrate to the substrate surface, sucked to the front end, and the support nozzle tip is sequentially started from the central side. Is retracted to the upper table surface, and a negative pressure is sequentially supplied to suction holes near the support nozzles on the upper table side to be sucked on the upper table surface, and the other end of the substrate is similarly moved from the center to the end. A method for assembling a large substrate, wherein the large substrate is suctioned and held on an upper table. A substrate is held on an upper table and a lower table provided in a vacuum chamber, and a sealing material is applied to at least one of the substrates held on the upper or lower table, and further, the substrate held on the lower table With the liquid crystal dropped on the surface, the inside of the vacuum chamber is decompressed, the distance between the two tables is reduced, and the substrates are attached to each other to assemble the liquid crystal substrate.
When holding the substrate on the lower table, of the plurality of support pins protruding from the lower table, lower one of the support pins in the width direction of the lower table central portion into the lower table, and thereafter, from the central portion in the longitudinal direction of the substrate to one end. The support pins are sequentially lowered into the lower table toward the lower table, and a negative pressure is supplied to the suction suction holes near the lowered support pins to suck the substrate to the lower table surface to one end, and then, from the central portion to another side. The support pins are sequentially lowered into the lower table toward the end, and the substrate is held on the lower table by supplying negative pressure to suction suction holes near the support pins that have been lowered into the lower table. To assemble a large substrate. A substrate is held on an upper table and a lower table provided in a vacuum chamber, and a sealing material is applied to at least one of the substrates held on the upper or lower table, and further, the substrate held on the lower table With the liquid crystal dropped on the surface, the inside of the vacuum chamber is decompressed, the distance between the two tables is reduced, and the substrates are attached to each other to assemble the liquid crystal substrate.
When holding the board on the lower table, of the plurality of support pins protruding from the lower table, lower one of the support pins in the width direction of the table into the lower table, and then from the center in the length direction of the substrate to one end. The support pins are sequentially lowered into the lower table toward the lower table, and the support pins are sequentially lowered into the lower table from the center toward the other end, and after the entire surface of the substrate is in contact with the lower table, the suction suction holes of the lower table. A substrate is held on a lower table by supplying a negative pressure to the substrate.

Images