JP2004087635A - Method and apparatus for laminating substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely hold the substrates without damaging the substrate and an electrostatic chuck in vacuum. <P>SOLUTION: At least one of the two substrates 33 and 34 is provided with an adhesive, and the substrates 33 and 34 are disposed opposite to each other and are objects to be laminated. In the case of positioning the substrates 33 and 34 within a chamber 15 in a pressure-reduced state and thereafter laminating them, the substrates 33 and 34 are held by suction and adsorption force until inside of the chamber 15 comes into the prescribed pressure reduced state. When the prescribed pressure reduced state is formed, the substrates 33 and 34 are held by applying voltage to a desired pair of electrodes according to the dimension of the substrates within each electrode of a bipolar electrostatic chuck having a plurality of pairs of electrodes 23D<SB>1</SB>, 24D<SB>1</SB>, 23D<SB>2</SB>and 24D<SB>2</SB>provided within the chamber 15. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method and apparatus for bonding two substrates, and more particularly, to a method and apparatus for bonding a liquid crystal display panel and the like in a reduced-pressure atmosphere.
[0002]
[Prior art]
In manufacturing a liquid crystal display panel, two glass substrates provided with a transparent electrode, a thin film transistor array, and the like are provided with an adhesive (hereinafter, also referred to as a “sealant”) at an extremely close interval of about several μm (eg, 2 μm). There is a process of bonding (hereinafter, the substrate after the bonding is referred to as “cell”), and sealing a liquid crystal in a space formed by each substrate and an adhesive (sealant).
[0003]
Conventionally, as a method of bonding the substrates when sealing the liquid crystal, the liquid crystal is dropped on one of the substrates in which a sealing agent is drawn in a closed pattern (braille shape) so as not to provide an injection port. Then, a method disclosed in Japanese Patent Application Laid-Open No. 2000-284295, in which the other substrate is arranged above one substrate in a vacuum chamber, and the other substrate and one substrate are bonded together by pressing. is there.
[0004]
Specifically, in the substrate bonding method disclosed in Japanese Patent Application Laid-Open No. 2000-284295, the other substrate is electrostatically attracted and held on the lower surface of a pressure plate provided in a vacuum chamber, and the vacuum is also applied. The one substrate is electrostatically adsorbed and held on a table arranged opposite to the pressure plate in the chamber. Then, the pressure in the vacuum chamber is reduced to a vacuum state, and the distance between the pressure plate and the table is reduced, whereby the respective substrates are pressed and bonded.
[0005]
[Problems to be solved by the invention]
However, in the substrate bonding method disclosed in Japanese Patent Application Laid-Open No. 2000-284295, nothing is disclosed about the substrate size. For this reason, if the size of the substrate to be electrostatically attracted is smaller than the size of the electrostatic attraction mechanism (the size of the electrode), the dielectric covering the electrode is exposed in a reduced-pressure atmosphere. There is a disadvantage that the substrate and the electrostatic attraction mechanism may be damaged by discharging from the exposed portion of the substrate.
[0006]
In addition, when the area of the electrode and the dielectric is reduced in order to correspond to a small substrate, that is, when the electrode is reduced so that the dielectric does not protrude from the substrate surface in a reduced-pressure atmosphere and the exposed portion does not occur, a large size is required. There has been a disadvantage that it is not possible to generate an attraction force enough to hold the substrate. In order to remedy such inconvenience, it is only necessary to prepare a large number of electrostatic suction mechanisms having different sizes according to the size of the substrate. However, preparing such a large number of electrostatic attraction mechanisms causes a troublesome operation of replacing the electrostatic attraction mechanism in accordance with the substrate size, thereby causing an inconvenience of increasing costs.
[0007]
Here, a bipolar electrostatic chuck may be used as the electrostatic chucking mechanism. In the bipolar electrostatic chuck, positive and negative voltages are applied to a pair of electrodes provided therein, so that positive and negative voltages are applied to the dielectric surface (electrostatic chuck suction surface) and the transparent conductive film on the substrate film surface. A negative charge is generated, and the substrate is held by the Coulomb force acting during this period. However, when multiple panels are formed from one substrate, the transparent conductive film on the substrate film surface may be divided between the panels. In such a case, a Coulomb force is not generated unless positive and negative charges are generated in one panel, so that an electrostatic chuck composed of a pair of large bipolar electrodes must hold a multi-faced substrate. There was an inconvenience that it was not possible.
[0008]
The present invention improves the disadvantages of the conventional example, and can reliably hold the substrate in a reduced-pressure atmosphere without damaging the substrate or the electrostatic chuck. It is an object of the present invention to provide a method and an apparatus for bonding substrates that can be performed.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention, at least one of the two substrates, which is an object to be bonded, provided with an adhesive and opposed to each other, is positioned in a chamber under reduced pressure. When performing bonding by applying pressure later, the substrate is held by applying a suction force until the inside of the chamber reaches a predetermined reduced pressure state. When the predetermined reduced pressure state is reached, the substrate is provided in the chamber. In the bipolar electrostatic chuck having a plurality of pairs of electrodes, a voltage is applied to a desired one of the electrodes corresponding to the size of the substrate and held. Here, the voltage may be applied to a desired electrode pair corresponding to the shape of the conductive film formed on the substrate.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
One embodiment of a substrate bonding apparatus according to the present invention will be described with reference to FIGS.
[0011]
FIG. 1 shows the overall configuration of an embodiment of the substrate bonding apparatus of the present invention. As shown in the drawing, the substrate bonding apparatus is roughly classified into two substrates 33 and 34 (hereinafter, a substrate 33 placed and held on a table 9 to be described later is referred to as a “lower substrate 33”, An XYθ stage unit S1 for positioning the substrate 34 held on the pressing plate 16 to be pressed is referred to as an “upper substrate 34”; a substrate bonding unit S2 (chamber unit) for bonding the substrates 33 and 34; And a Z-axis moving stage section S3 provided with a drive mechanism for generating a pressing force on each of the substrates 33 and 34. The respective parts S1, S2, S3 are sequentially arranged on the gantry 1. Here, the XYθ stage unit S1 is placed and held on the gantry 1, and the substrate bonding unit S2 is supported by the first frame 2 provided with, for example, four columns erected on the gantry 1, and the Z-axis moving stage The portion S3 is supported by a second frame 3 provided on the gantry 1 and having, for example, four columns. Hereinafter, these units S1, S2, and S3 will be described in detail.
[0012]
The XYθ stage S1 has an X stage 4a disposed on the gantry 1, a Y stage 4b disposed on the X stage 4a, and a θ stage 4c disposed on the Y stage 4b. . The X stage 4a of the present embodiment is configured to be able to move the Y stage 4b and the θ stage 4c in the left-right direction (X-axis direction in FIG. 1) by the drive motor 5. The Y stage 4b is configured so that the drive motor 6 can move the θ stage 4c in the front-rear direction (the Y-axis direction in FIG. 1). Further, the θ stage 4c is configured to rotate in the θ direction shown in FIG. 1 with respect to the Y stage 4b by the drive motor 8 via the rotary bearing 7.
[0013]
Here, the table 9 for mounting and holding the lower substrate 33 is fixed via the support pillar 10 on the θ stage 4c. The Y stage 4b is provided with an arm 11 that covers the lower side of the support column 10 via a rotary bearing 13 and a vacuum seal 14, whereby the arm 11 is rotated with the rotation of the support column 10. It does not rotate. Further, between the arm 11 and a later-described bonding chamber 15 of the substrate bonding section S2, one end is fixed on the arm 11 and the other end is fixed below the bonding chamber 15, and the supporting column 10 is fixed. A vacuum bellows 12 made of a bellows-like elastic body is provided. Thereby, at the time of bonding, the inside of the bonding chamber 15 can be maintained in a predetermined reduced pressure state.
[0014]
In the present embodiment, one support column 10 is disposed substantially at the center of the table 9, but the present invention is not limited to this. For example, a predetermined amount of the table 9 by the θ stage 4 c (described later) A plurality of support columns 10 may be provided as long as the rotation can be performed to correct the positional deviation amount of the alignment mark).
[0015]
As shown in FIG. 1, the substrate bonding section S2 is provided with a bonding chamber (chamber) 15 for bonding two substrates 33 and 34 under a predetermined reduced pressure, and is provided in the bonding chamber 15. And a pressure plate 16 disposed above and facing the surface of the table 9 in the bonding chamber 15. In this case, the table 9 holds and holds a lower substrate 33 provided with an adhesive or liquid crystal, which will be described later, and the pressing plate 16 holds an upper substrate 34 to be attached to the lower substrate 33.
[0016]
An opening 15a through which the substrates 33 and 34 enter and exit is provided on a side of the bonding chamber 15, and a gate valve 17 that closes the opening 15a is provided on the side. Here, the gate valve 17 is configured to be movable vertically (in the Z-axis direction in FIG. 1) by a cylinder 17a.
[0017]
Further, below the bonding chamber 15, first and second exhaust pipes 20a and 20b are connected to a vacuum pump via a switching valve (not shown) to evacuate the bonding chamber 15 under reduced pressure. Here, the first exhaust pipe 20a used is thinner than the second exhaust pipe 20b. For example, in a case where each of the exhaust pipes has a substantially circular cross section, the diameter of the first exhaust pipe 20a is set to 1. The thicker second exhaust pipe 20b has a diameter of about 10 to 100 times. The diameter of the first exhaust pipe 20a is such that when the inside of the bonding chamber (inside the chamber) is depressurized, the flow of the gas (or air) causes the substrates 33, 34 to ramp up, the liquid crystal on the lower substrate 33 to be scattered, The pumping speed is set so as not to cause the freezing of water due to the pressure. This setting can be determined in advance by experiments or the like. After the pressure is slowly reduced to a predetermined reduced pressure state by the first exhaust pipe 20a, the pressure is reduced at a high speed by switching to the second exhaust pipe 20b, so that the time required for the pressure reduction can be reduced without causing a problem such as scattering of liquid crystal. Can be shortened.
[0018]
On the table 9 side in the bonding chamber 15, a plurality of elevating pins 35 used to receive the lower substrate 33 from a transfer machine (not shown) or to take out the bonded cells are provided upright. I have. The lifting pin 35 is provided with a cylinder 36 at one end (the lower end in FIG. 1), and is configured to be able to move vertically through a through hole formed in the table 9 by the cylinder 36. ing.
[0019]
Further, a pipe 21 for returning the decompressed state in the bonding chamber 15 to the atmospheric pressure and a pipe for introducing or shutting off gas (air) into the bonding chamber 15 are provided above the bonding chamber 15. A valve 22 provided in the middle of 21 is provided. Here, a pressure source (not shown) (for example, a pump) is connected to the pipe 21, so that the introduction speed of the gas into the bonding chamber 15 can be controlled. In addition, the pressure source does not necessarily need to be provided. Further, an air release valve 23 and a cylinder 24 for driving the valve are provided on the side surface of the bonding chamber, and are used when the bonding chamber is returned to the atmospheric pressure.
[0020]
Further, a plurality of windows 25 for observing alignment marks of the upper and lower substrates 33 and 34 through mark recognition holes (not shown) formed in the pressure plate 16 are provided above the bonding chamber 15. Here, a recognition camera 26 shown in FIG. 1 is used for observing the alignment mark, and the displacement of the alignment mark on each of the substrates 33 and 34 is measured by the recognition camera 26.
[0021]
The pressure plate 16 is provided with a plurality of suction holes for sucking and sucking the upper substrate 34 by negative pressure, and an electrostatic suction mechanism for sucking the upper substrate 34 by electrostatic force. The electrostatic suction mechanism ensures that the substrate is kept in a reduced pressure state by providing two or more pairs of electrodes consisting of a positive electrode and a negative electrode, even if the size of the substrate to be bonded changes or the number of chamfers changes. Bipolar electrostatic chuck. Here, the electrostatic attraction mechanism provided on the pressing plate will be described as an example, but the electrostatic attraction mechanism provided on the table is similarly configured.
[0022]
Here, a general arrangement of the bipolar electrostatic chuck provided on the pressing plate is shown in FIG. For convenience of explanation, the white electrodes in the figures are positive electrodes, and the hatched electrodes are negative electrodes. In addition, since each electrode is held inside the pressure plate 16 and adsorbs the substrate via a dielectric covering the electrode surface, the electrode arrangement positions shown in the following figures are arranged inside the pressure plate 16. 3 shows the arrangement positions of the electrodes. The substrate is a glass substrate having semiconductor properties.
[0023]
First, the bipolar electrostatic chuck shown in FIG. 2A has two substantially rectangular recesses formed on the lower surface of the pressure plate 16 and two substantially rectangular planar electrodes 23A and 24A embedded therein. A dielectric whose main surface is flush with the lower surface of the pressure plate 16 is covered on the surfaces of the bipolar electrodes 23A and 24A (the surface on the lower surface side of the pressure plate 16). In such a case, the bipolar electrostatic chuck applies the positive voltage to one electrode 23A and the negative voltage to the other electrode 24A, thereby applying the substrate 34 to the pressing plate 16 by Coulomb force or Johnson-Rahbek force. Hold by electrostatic attraction.
[0024]
The bipolar electrostatic chuck shown in FIG. 2B has a pair of comb-shaped bipolar electrodes 23B and 24B embedded in the pressing plate 16 and covered with a dielectric. This bipolar electrostatic chuck applies a positive voltage to one electrode 23B and a negative voltage to the other electrode 24B, thereby applying negative and positive charges to the main surface of each dielectric and the substrate 34. Then, the substrate 34 is electrostatically attracted to the pressure plate 16 and held by the Coulomb force acting during the generation.
[0025]
Here, the entire size of the pair of bipolar electrodes 23A and 24A shown in FIG. 2A and the pair of bipolar electrodes 23B and 24B shown in FIG. It is formed slightly smaller.
[0026]
On the other hand, FIGS. 3A and 3B show a case where the substrate itself is smaller than the entire size of the pair of electrodes provided on the pressing plate.
[0027]
That is, when the small substrate 34 shown in FIGS. 3A and 3B is electrostatically attracted to the pressing plate provided with the bipolar electrostatic chuck shown in FIGS. 2A and 2B, each of the electrodes 23A, A part of 23B, 24A, 24B protrudes from the substrate 34. This is because the pressure plate 16 is made to press a large substrate. When a voltage (approximately ± 100 V to ± 5000 V) is applied to the partially exposed electrodes (dielectrics) 23A, 23B, 24A, and 24B in a predetermined reduced-pressure atmosphere, discharge occurs from the exposed portions of the dielectrics. May occur to damage the substrate 34B and the electrostatic chuck.
[0028]
Therefore, there is a method of reducing the area of the electrode and the dielectric so as to correspond to a substrate having a small size so that the dielectric does not protrude from the substrate surface and is not exposed in a reduced-pressure atmosphere as described above. However, even if an attempt is made to hold a large-sized substrate using the small electrode, the substrate cannot be held because an electrostatic attraction force required to hold the large substrate cannot be generated. Therefore, in order to effectively hold the substrate by electrostatic force, it is necessary to make the size of the entire electrode and the size of the substrate substantially the same.
[0029]
In recent years, there is a manufacturing method in which a plurality of liquid crystal substrates are first formed on a large substrate, and the substrates are bonded and cut to obtain a plurality of liquid crystal substrates of a desired size. In this manufacturing method, a plurality of types of substrates cut from the mother substrate may flow on the same manufacturing line. In this case, it is necessary to divide the electrodes in accordance with the size of the substrate that has been cut small, so that the electrodes (dielectric) to which the voltage is applied are not exposed in a reduced-pressure atmosphere, so that no discharge occurs.
[0030]
As described above, the electrostatic chucking mechanism of this embodiment uses the bipolar electrostatic chuck provided with two or more pairs of positive and negative electrodes as described above. Specifically, the electrostatic attraction mechanism is provided with a plurality of electrode pairs formed of two positive and negative electrodes formed on a pressure plate so as to adsorb and hold a substrate having the smallest area. In other words, an electrode pair to be used is selected and determined according to the size of the substrate, and a voltage is applied to the determined electrode pair so that it can be used for both large and small substrates. That is, the bipolar electrostatic chuck is provided with voltage applying means for applying a voltage to a desired electrode pair. For example, in this embodiment, substrate information such as the size of the substrate, which is obtained in advance in the adhesive application step for bonding, is transmitted from the coating device and stored in the control device of the bonding device. The control device of the bonding device determines an electrode to which a voltage is to be applied based on the stored substrate information from the substrate No. or the like carried into the device, and sends a command to the voltage application unit. . The electrodes applied by the operator may be appropriately switched according to the substrate to be bonded.
[0031]
FIG. 4 shows a pressure plate 16 provided with two pairs of two electrodes, positive and negative. In addition, for convenience of explanation, a white electrode in the drawing is a positive electrode, and a hatched electrode is a negative electrode.
[0032]
As shown in FIGS. 4 (a) and 4 (b), the bipolar electrostatic chuck according to the present embodiment has four substantially rectangular concave portions formed on the lower surface of the pressure plate 16 and substantially rectangular planar electrodes 23D. ₁ , 24D ₁ , 23D ₂ , 24D ₂ Are respectively buried and their electrodes 23D ₁ , 24D ₁ , 23D ₂ , 24D ₂ (The lower surface of the pressing plate 16) is covered with a dielectric whose main surface is flush with the lower surface of the pressing plate 16. In such a case, the bipolar electrostatic chuck uses the electrode 23D ₁ , 23D ₂ To a positive electrode by applying a positive voltage to ₁ , 24D ₂ By applying a negative voltage to the negative electrode, negative and positive charges are generated in the transparent conductive film formed on the main surface of each dielectric and the surface of the substrate (substrate bonding surface). The substrate is electrostatically attracted to the pressure plate 16 and held by the applied Coulomb force.
[0033]
In the case of a large upper substrate 34D as shown in FIG. ₁ , 24D ₁ , 23D ₂ , 24D ₂ By applying a voltage to the substrate 34, a large attraction force is generated to attract and hold the substrate 34 thereon. In the case of a small upper substrate 34E as shown in FIG. 4B, a pair of adjacent positive and negative electrodes (a pair of electrodes 23D disposed near the center of the pressing plate 16 in this embodiment). ₂ , 24D ₁ ), The upper substrate 34E is suction-held with a necessary and sufficient large suction force. In such a case, the remaining electrode 23D ₁ , 24D ₂ Since no voltage is applied to, the occurrence of a discharge phenomenon as in the conventional example can be prevented. If a transparent conductive film is provided on the substrate, a larger electrostatic attraction force can be generated, so that the substrate can be reliably held.
[0034]
As described above, when the size of the substrate or the number of chamfers of the liquid crystal substrate changes, the number of electrode pairs is increased to 3, 4, 5,... It is possible to reliably hold and hold several sizes and multiple substrates under reduced pressure. That is, by providing a plurality of pairs of electrodes for an electrostatic chuck corresponding to the shape of a substrate having the smallest area on a pressing plate (table described later), the substrate can have a large suction force regardless of the size of the substrate. Can be held by suction. In the present embodiment, a single row of electrode groups provided in the horizontal direction has been exemplified. However, the present invention is not limited to this. For example, a plurality of single row electrode groups may be provided in the vertical direction.
[0035]
Subsequently, each suction suction hole for performing suction suction by negative pressure is connected to a suction valve (not shown) provided outside the substrate bonding chamber 15 via a pipe 19, and a vacuum (not shown) is provided via the suction valve. Connected to pump. In this case, a bypass pipe for opening to the atmosphere via a suction / adsorption releasing valve is provided, and the suction state is forcibly released by opening the suction / adsorption releasing valve to the atmosphere. The pressure plate 16 is provided with an electrode for electrostatic suction and a suction hole for suction and suction. In the present embodiment, a configuration is adopted in which the electrode for electrostatic adsorption is divided into a plurality of parts, and a suction suction hole by negative pressure is provided so as to surround the periphery thereof. For this reason, an introduction hole for introducing a negative pressure up to the suction suction hole can be provided avoiding the electrode portion, the distance from the electrode surface to the pressure plate surface can be shortened, and a large electrostatic attraction force can be generated.
[0036]
Here, as will be described later, when the pressure in the bonding chamber 15 is reduced while the upper substrate 34 is being sucked and sucked by the suction holes, the suction force is reduced and the upper substrate 34 falls. There is. Therefore, a substrate holding claw 40 for receiving the upper substrate 34 at a position slightly below the pressing plate 16 is provided in the bonding chamber 15. The substrate holding claws 40 are provided, for example, corresponding to two diagonally opposite corners of the upper substrate 34, and are hooked and held by a shaft extending downward from the upper part of the bonding chamber 15. You.
[0037]
Specifically, though not shown, a shaft is inserted into a through hole formed in the upper part of the bonding chamber 15, and the shaft is configured to rotate around its axis and move up and down. In this case, the shaft is covered with a vacuum seal so that the inside of the bonding chamber 15 does not cause air leakage. The rotation is performed by a rotary actuator (not shown) connected to the end of the shaft, and the vertical movement is performed by a lifting actuator (not shown) similarly connected to the end of the shaft. When the shaft is rotated or moved up and down as described above, the substrates 33 and 34 are attached to each other, and the liquid crystal agent dropped on the lower substrate 33 is expanded in the spreading direction of the main surfaces of the substrates 33 and 34. The substrate holding claws 40 can be retracted so as not to be in the way.
[0038]
Next, the pressing plate 16 is suspended and fixed to a later-described central guide plate 29 of the Z-axis moving stage unit S3 via a plurality of support columns 27. Above the central guide plate 29, four pressing mechanisms 41 to 44 project outward from the surface of the central guide plate 29 (outward from the support pillars 27), and one pressing mechanism 45 is provided substantially at the center of the surface. Is provided. Further, a linear guide that can move up and down with respect to the frame 3 is attached to the center guide plate 29. The drive units of the pressurizing mechanisms 41 to 45 are fixed to fixed support members 46a, 46b, 46c, 46d, 47 provided on the frame 3.
[0039]
The drive unit of this pressurizing mechanism is composed of motors 41a, 42a, 43a, 44a, 45a with encoders and ball screws 41b, 42b, 43b, 44b, 45b, and the action of force of each ball screw on the central guide plate 29. Load cells 41c, 42c, 43c, 44c, and 45c are provided at the point portions.
[0040]
The linear guide 30 for moving in the Z-axis direction is provided on the central guide plate 29 or the auxiliary member 48 for applying a force to the central guide plate 29. The linear guide 30 is movable along a rail provided on the frame 3. By operating each pressing mechanism to move the central guide plate 29 downward, the pressing plate 16 fixed to the support column 27 is pushed down, and the upper substrate adsorbed by the pressing plate 16 is pressed down. 34 is pressed against the lower substrate 33 and pressed. In the present embodiment, five pressure mechanisms are provided. However, a configuration in which forces are evenly applied to the four corners of a square substrate, that is, four pressure mechanisms may be provided. As described above, since the forces can be individually applied to the four corners of the pressing plate, even if the substrate spacing becomes uneven during pressing, the substrate spacing can be made uniform by changing the force applied to the four corners. It is possible to hold.
[0041]
Furthermore, in the present embodiment, the force is applied to the pressing plate 16 via the central guide plate 29, but the pressing mechanism may be configured to directly apply the force to the pressing plate 16. In this case, the central guide plate 29 becomes unnecessary and the number of parts is reduced, but the mechanism for maintaining the degree of pressure reduction in the chamber and the disassembly for maintenance are deteriorated.
[0042]
Next, the table 9 is provided with an electrostatic suction mechanism and a plurality of suction suction holes having the same configuration as the pressing plate 16 disposed on the upper surface of the table 9 in order to suction the lower substrate 33. I have.
[0043]
Each of the suction holes is connected to a suction valve (not shown) provided outside the bonding chamber 15 via a pipe 18 and connected to a vacuum pump (not shown) via the suction valve. In this case, a bypass pipe is provided in the middle of the pipe 18 through the valve for releasing suction and adsorption similarly to the pressurizing plate 16 to open to the atmosphere. The suction state has been forcibly released. The table 9 configured as described above is fixed on the θ stage 4c via the support pillar 10 as described above.
[0044]
Next, the operation of the substrate bonding apparatus of the present embodiment will be described. Here, an example in which a substrate for a liquid crystal panel is used as a substrate to be bonded will be described.
[0045]
In advance, when one of the two substrates to be bonded is to be bonded to each other, the liquid crystal is confined in a predetermined frame and sealed with a single line of adhesive. Keep it. Then, a predetermined amount of liquid crystal is dropped on the lower substrate 33 at a position where the liquid crystal can be accommodated in the frame of the adhesive.
[0046]
First, using a hand of a transfer machine (not shown) provided outside the bonding chamber 15, the peripheral portion of the upper substrate 34 with the film surface directed downward is suction-adsorbed from below. Then, the gate valve 17 provided at the opening 15a of the bonding chamber 15 is opened, the hand of the transfer machine is inserted into the bonding chamber 15 from the opening 15a, and The pressure plate 16 is pressed against the upper substrate 34. Thereafter, the suction suction of the hand is released, and the vacuum pump is operated to supply a negative pressure from the pipe 19, so that the upper substrate 34 is suction-suck to the pressure plate 16 by the suction suction holes provided in the pressure plate. When the suction of the upper substrate 34 is completed, the hand is retracted out of the bonding chamber 15.
[0047]
Subsequently, the cylinder 36 is actuated so that the tip of each lifting pin 35 projects from the upper surface of the table 9 to raise each lifting pin 35. Then, the peripheral edge of the lower substrate 33 with the surface on which the liquid crystal has been dropped is suction-adsorbed from below by the hand of the transfer machine, and the hand is inserted into the bonding chamber 15 to move the lower substrate 33 to each of the lifting pins. 35. When the transfer of the lower substrate 33 is completed, the hand is retracted out of the bonding chamber 15 and the gate valve 17 is closed. Thereafter, each of the elevating pins 35 is lowered to place the lower substrate 33 on the table 9, and the vacuum pump is operated to suck the lower substrate 33 onto the table 9 through the suction holes.
[0048]
As described above, when the adsorption of the substrates 33 and 34 to the table 9 and the pressure plate 16 is completed, the valve provided in the exhaust pipe 20a or 20b connected to the vacuum pump is opened, and the inside of the bonding chamber 15 is opened. Pressure for adhering the substrates 33 and 34 by exhausting the gas (about 5 × 10 ^-3 The pressure in the bonding chamber 15 is reduced to Torr).
[0049]
Here, since the pressure in the bonding chamber 15 is lower than the suction attraction force of the upper substrate 33 under the pressure, the upper substrate 34 separates from the pressure plate 16. However, the above-described substrate holding claw 40 is provided on the lower surface side of the pressing plate 16, and the upper substrate 34 is held by moving the substrate holding claw 40 with the above-described rotary actuator or elevating actuator. The substrate 34 is not separated from the pressure plate 16.
[0050]
As described above, when the decompression in the bonding chamber 15 is completed, the bipolar type static electrode provided on the table 9 and the pressurizing plate 16 is used to adsorb and hold the substrates 33 and 34 on the table 9 and the pressurizing plate 16 even in the decompressed atmosphere. Electrodes to be operated are selected and determined in advance according to the size of each of the substrates 33 and 34 from the electrodes of the electro chuck, and a voltage is applied to the determined pair of electrodes to electrostatically attract the substrates 33 and 34. I do. Thereafter, the motors 41a, 42a, 43a, 44a, and 45a of the respective pressing mechanisms are driven to lower the pressing plate 16 and bring the upper substrate 34 closer to the lower substrate 33. Then, the alignment mark provided on each of the substrates 33 and 34 is observed using the recognition camera 26, and the positional deviation between the upper and lower substrates 33 and 34 is measured. Based on the measured values, the operation of the X stage 4a, the Y stage 4b, and the θ stage 4c is controlled to move the table 9 horizontally, and the lower substrate 33 and the upper substrate 34 are aligned.
[0051]
When the alignment is completed, the pressure plate 16 is further lowered, and the upper substrate 34 crushes the adhesive to perform primary pressure. After the primary press, the voltage applied to the electrostatic attraction electrode of the press plate 16 is cut off, and the electric motor 32 is driven to raise the press plate 16.
[0052]
In this case, the interval between the substrates 33 and 34 after the primary pressurization is, for example, about 15 μm, which is not the desired interval yet. For this reason, the amount of crushing of the adhesive is small and the contact area of the adhesive with each of the substrates 33 and 34 is small, so that the bonding state is incomplete. Further, the liquid crystal in the frame of the adhesive does not spread, and a large decompressed space is formed between the liquid crystals. In such a case, in order to apply a desired pressing force to the substrate, the apparatus itself may be enlarged so that a large pressing force can be applied. However, since the size of the device is increased, the entire device must be rebuilt, which is expensive.
[0053]
Here, when the pressure in the bonding chamber 15 is changed from the reduced pressure state to the atmospheric pressure, the space between the substrates 33 and 34 (the above-described reduced pressure air space portion) is in a reduced pressure state. A large pressure is applied to the outside 34 substantially uniformly. For example, when the size of each of the substrates 33 and 34 is 1200 mm × 1000 mm, a force of 121.6 kN can be applied by applying atmospheric pressure when the space between the substrates 33 and 34 is in a reduced pressure state. For this reason, in the present embodiment, after the primary pressurization is completed, the valve 22 of the pipe 21 is opened, and the gas pressurized from the pressure source connected to the pipe 21 is introduced into the bonding chamber 15, so that the bonding is performed. The inside of the chamber 15 is returned to the atmospheric pressure and bonding is performed (secondary pressurization). If it is desired to rapidly increase the atmospheric pressure, it can be realized by opening the atmosphere release valve 23.
[0054]
When the bonding is completed and the pressure in the bonding chamber 15 becomes the atmospheric pressure, the gate valve 17 is opened. Then, after the voltage applied to the electrostatic suction electrode of the table 9 is cut off and the suction in the suction suction hole is released, the lifting pins 35 are raised to push up the cell from above the table 9. Thereafter, the hand of the transfer machine is inserted into the lower part of the cell (between the cell and the table 9) through the opening 15a, and the cell is transferred onto the hand and carried out of the bonding chamber 15.
[0055]
As described above, by arranging the electrode pair for electrostatic adsorption provided on the pressing plate or the table in a plurality of parts, a large substrate of 1200 × 1000 mm or more and a substrate smaller than the same can be obtained by using the same device, the pressing plate, or The bonding operation can be performed without replacing the electrostatic chuck, and the time required for bonding substrates of different sizes can be greatly reduced.
[0056]
【The invention's effect】
As described above, by using the substrate bonding method and the apparatus according to the present invention, regardless of the size of the substrate and the shape of the conductive film formed on the substrate, various substrates are surely absorbed and held in a reduced-pressure atmosphere. be able to. As a result, it is possible to obtain an unprecedented excellent substrate bonding method and apparatus capable of bonding substrates with high accuracy.
[Brief description of the drawings]
FIG. 1 is a partial cross-sectional view illustrating a configuration of an embodiment of a substrate bonding apparatus according to the present invention.
FIG. 2 is a plan view of a pressure plate provided with a general bipolar electrode as viewed from the substrate side, and FIG. 2A is a diagram showing a pressure plate provided with a pair of substantially rectangular electrodes; FIG. 2B is a diagram showing a pressure plate provided with a pair of comb-shaped electrodes.
FIG. 3 is a plan view of a pressing plate provided with a general bipolar electrode as viewed from the substrate side, and FIG. 3 (a) illustrates electrostatic pressing of a small substrate by the pressing plate shown in FIG. 2 (a). FIG. 3B is an explanatory view showing a state in which a small substrate is to be electrostatically attracted by the pressing plate shown in FIG. 2B, and FIG. FIG. 4 is an explanatory view showing a state in which a large substrate on which two conductive films are formed is to be electrostatically attracted by a pressure plate provided with a large, substantially rectangular electrode.
FIG. 4 is a plan view of a pressure plate provided with a bipolar electrode according to the present embodiment as viewed from the substrate side, and FIG. 4A illustrates a case where a large substrate on which one conductive film is formed is electrostatically attracted; FIG. 4B is an explanatory diagram when a small substrate on which one conductive film is formed is electrostatically attracted.
[Explanation of symbols]
9: table, 15: chamber, 16: pressure plate, 23D ₁ , 23D ₂ , 24D ₁ , 24D ₂ ... electrodes, 33: lower substrate, 34: upper substrate.

Claims (4)

An adhesive is provided on at least one of the substrates, and the other substrate disposed oppositely is positioned in a bonding chamber in a decompressed state, and then is subjected to pressure to perform bonding.
Before carrying the substrate into the substrate bonding apparatus, the size of the substrate is measured, and the substrates are respectively held by applying a suction force until the inside of the bonding chamber becomes a predetermined reduced pressure state. When a voltage is applied, a voltage is applied to a desired electrode pair according to the measured size of the substrate among the electrodes of the bipolar electrostatic chuck having a plurality of pairs of electrodes provided on the substrate holding means for holding the substrate. A substrate bonding method characterized by applying and holding. A bonding chamber provided with a pipe for setting the inside to a reduced-pressure atmosphere, a table disposed in the bonding chamber, which holds one substrate and is horizontally movable with respect to the surface of the one substrate, In a substrate bonding apparatus having a substantially rectangular pressure plate that faces one substrate and holds the other substrate, and a drive mechanism for moving the pressure plate in the direction of the one substrate,
At least one of the table and the pressure plate is provided with a bipolar electrostatic chuck having a plurality of pairs of electrodes for electrostatically holding the substrate and a plurality of suction holes for sucking and sucking the substrate by negative pressure. A substrate bonding apparatus, further comprising a voltage applying means for applying a voltage to a desired electrode pair of the plurality of pairs of electrodes in response. The substrate bonding apparatus according to claim 2,
The pressing plate has a configuration in which a pressing shaft for individually pressing the four corners of the quadrangular shape, a driving mechanism for each, and a pressing shaft and a driving mechanism for pressing the center of the pressing plate are provided. Substrate bonding apparatus. The substrate bonding apparatus according to claim 2,
The plurality of suction holes are provided so as to surround the periphery of the electrode.

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