JPH0677304A - Wafer conveying apparatus - Google Patents

Abstract

PURPOSE:To make it possible to hold wafer in vacuum and prevent the transfer of foreign matters to wafer. CONSTITUTION:A holding equipment 20 is formed with a dielectric having an electric resistivity of less than 10<10>OMEGA.cm and is equipped with a main body 21 having a holding surface 22, a positive electrode member 23 provided on the main surface at the opposite side of the holding surface 22 of the main body and a voltage generating device 26 for generating an electric potential between the positive electrode member 23 and a wafer 1; and a controller 30, which controls the wafer adsorption force of the holding equipment 20 to an optimum value by adjusting the voltage generating device 26 to a predetermined voltage value based on the relation between the potential difference and the wafer adsorption force of the holding equipment 20, is connected to the holding equipment 20. By doing this, a potential difference is generated between the wafer 1 and the positive electrode member 23 by the voltage generating device 26 and the wafer 1 is adsorbed to the main body 21 by an electrostatic force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer transfer device, and more particularly to a technique for holding and transferring a wafer as an object to be transferred by a holding device using static electricity. , Wafer) is effectively used for carrying in and out of a CVD apparatus or the like.

[0002]

2. Description of the Related Art In a semiconductor device manufacturing process, for example, when a wafer is carried in and out of a processing chamber of a CVD device, a holding device that automatically sucks and holds the wafer, and the holding device is used as a processing chamber in the CVD device. A moving device for moving between the loader and the unloader, and is configured to automatically carry the wafer in and out of the processing chamber by moving the holding device that sucks and holds the wafer by the moving device. Wafer transfer devices are commonly used.

Conventionally, in such a wafer transfer device, a holding device is used which holds the wafer by vacuum suction on the wafer.

On the other hand, it is generally practiced that a processing chamber such as a CVD apparatus is evacuated to maintain a low pressure atmosphere.

As an example of the wafer transfer technique, "Electronic Materials, November 1982, Separate Volume," published by the Industrial Research Institute, Inc., November 18, 1982, P109
~ P116.

Further, as an example in which a CVD apparatus is described, "Electronic Materials 1985 11
"Month issue separate volume" issued November 20, 1985, P53-P5
There are four.

[0007]

However, the present inventor has revealed that the wafer transfer device using the holding device for vacuum suction has the following problems.

In a holding device for vacuum-sucking a wafer, it is extremely difficult to control the vacuum pressure for obtaining the minimum necessary holding force, and therefore a vacuum pressure higher than necessary is applied. Therefore, the wafer that is vacuum-adsorbed is in a state of being strongly pressed against the holding surface. As a result of the wafer being strongly pressed against the holding surface, foreign matter on the holding surface is transferred to the wafer.

In a holding device for vacuum-adsorbing a wafer, it is inevitable that the wafer cannot be transferred in a vacuum such as a processing chamber of a CVD device.

It is an object of the present invention to provide a wafer transfer device which can prevent transfer of foreign matter to a wafer and can hold the wafer even in a vacuum.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0012]

The typical ones of the inventions disclosed in the present application will be outlined below. That is, in a wafer transfer device including a holding device that attracts and holds a wafer and a moving device that moves the holding device, the holding device has a resistivity of 10 ¹⁰ Ω.
A main body made of a dielectric material having a size of cm or less and having a holding surface for sucking and holding a wafer formed on one main surface thereof, and a main surface opposite to the wafer holding surface of the main body. And a voltage generator that generates a potential difference between the electrode member and the wafer, and a controller is connected to the voltage generator. The wafer attracting force of the holding device is controlled to an appropriate value by adjusting the voltage generating device to a predetermined voltage value based on the relationship between the wafer attracting force of the holding device and the potential difference. It is characterized by

[0013]

In the above means, when a potential difference is generated between the wafer and the electrode member by the voltage generator while the wafer is in contact with the holding surface of the main body, the wafer is attracted and held by the main body by electrostatic force. To be done.

Therefore, according to the above-mentioned means, the wafer is adsorbed and held on the main body by the electrostatic force, so that the adsorbing force can be controlled by controlling the voltage value for generating the electrostatic force. . And this voltage value can be changed and adjusted very easily by the voltage generator. Therefore, the wafer suction force of the holding device can be easily controlled by the voltage generator.

Then, by controlling the suction force of the holding device with respect to the wafer to the minimum necessary amount, it is possible to reduce the transfer of foreign matter from the holding surface to the wafer.

Further, since the electrostatic attraction of the wafer is effective even in a vacuum, according to the above-mentioned means,
The wafer can be transferred even in a vacuum.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic view including a circuit diagram showing a wafer transfer apparatus according to an embodiment of the present invention, and FIGS. 2 (a) and 2 (b) are a plan view and a front sectional view showing the holding apparatus. Three
(A), (b) is each line diagram for explaining the operation, and FIG. 4 is a partially omitted perspective view showing a CVD apparatus in which the wafer transfer apparatus is used.

In this embodiment, the wafer transfer apparatus according to the present invention is configured to automatically transfer the wafer 1 as the object to be processed between the processing chamber and the loader and unloader in the CVD apparatus. .

As shown in FIG. 4, the CVD apparatus 2
Includes a processing chamber 3, a loader unit 4, and an unloader unit (not shown). Although detailed description and illustration are omitted, the processing chamber 3 is configured such that the CVD process is performed in a vacuum atmosphere. The loader unit 4 is configured to pay out one wafer 1 stored in the wafer storage jig 5. The unloader unit is configured to store one wafer 1 in the wafer storage jig 5.

A Z-direction moving device 6 is installed in the loader unit 4, and the Z-direction moving device 6 is constructed so as to be capable of pitch-feeding the wafer storage jig 5 in the vertical direction. That is, the Z-direction moving device 6 includes the guide rail 7, and the guide rail 7 is laid in the vertical direction (Z direction). A feed screw shaft 8 is laid in parallel near the guide rail 7, and the feed screw shaft 8 is configured to be normally and reversely rotated by a pulse motor 9. Therefore, the Z-direction moving device 6 for the wafer storage jig has a structure for moving the wafer storage jig 3 upward or downward by the forward and reverse rotations of the pulse motor 9.

The push-up pin 3a is installed in the processing chamber 3 so as to move up and down.
Thus, the wafer 1 as the object to be processed is supported from the processing position (not shown) in the processing chamber 3 to the transfer / delivery position.

In this embodiment, the wafer transfer apparatus 10 according to the present invention is installed in this CVD apparatus 2. The wafer transfer device 10 includes an X-direction moving device 11, and the X-direction moving device 11 is installed on one side of the CVD device 2.

That is, this X-direction moving device 11 has a C
The VD device 2 is provided with a guide rail 12 laid across the processing chamber 3, the loader unit 4, and the unloader unit. The guide rail 12 has an X-direction moving block 13
Is movably mounted in the X direction. The X direction moving block 13 is moved in the X direction by a pulse motor 14.

A SCARA type robot 15 is installed on the X-direction moving block 13. The robot 15 includes a first arm 16 and a second arm 17. First
The arm 16 is supported by the main body of the robot 15 so as to be rotationally driven. The second arm 17 is supported so that one end thereof is rotationally driven by the free end of the first arm 16.

Then, at the free end of the second arm 17,
A holding device which is a main part of the wafer transfer device 10 according to the present embodiment is provided. Therefore, the X-direction moving device 1
1 and the robot 15 substantially constitute a moving device for moving the holding device.

Next, the holding device 20 according to this embodiment will be described.

The holding device 20 includes a main body, a pair of electrodes, a voltage generator, a changeover switch and a controller. The main body 21 is made of silicon carbide (SiC) and is formed in a substantially rectangular flat plate shape. This silicon carbide (Si
C) is an example of a dielectric having a resistivity of 10 ¹⁰ Ω · cm or less.

A holding surface 22 for supporting and holding the wafer 1 as an object to be held from below is formed at the tip of the upper surface of the main body 21. The holding surface 22 is the wafer 1
Is formed to be smaller than the area of the main surface of the wafer 1, and is configured to support the center of gravity of the wafer 1. Also,
This holding surface is configured to be smooth so as not to be damaged even if it contacts the main surface of the wafer 1.

A positive electrode member 23 as one electrode is laid at the tip of the lower surface of the main body 21 so as to face the holding surface 22. A voltage generator is electrically connected to the positive electrode member 23 as described later.

Further, the body 21 has a ground pin mounting member 2
5 is projectingly provided in parallel with the main body 21, and the mounting member 2
A ground pin 24, which serves as the other electrode, is provided at the tip of the No. 5 so as to project vertically upward. The ground pin 24 is adapted to be electrically connected to the wafer 1 by coming into contact with the lower surface of the wafer 1 mounted and held on the main body 21.

The voltage generator 26 is electrically connected to the ground pin 24 and the positive electrode member 23 via an electric circuit 27, and generates DC power to generate a potential difference between the ground pin 24 and the positive electrode member 23. Is configured to occur. Therefore, the wafer 1 placed on the holding surface 22 of the main body 21 and electrically connected to the ground pin 24, and the main body 2
Therefore, a potential difference is generated between the positive electrode member 23 which is laid on the main surface on the opposite side of the first holding surface 22 so as to face the holding surface 22.

In the electric circuit 27, a changeover switch 28 is provided on the positive electrode member 23 side of the voltage generator 26. This changeover switch 28 is grounded to a ground side contact 28a.
And a positive side contact 28b connected to the positive side of the voltage generator 26, and a movable iron piece 28c for switching between the two contacts. The movable iron piece 28c always closes the ground side contact 28a and adsorbs the wafer 1. Sometimes, the earth side contact 28
It is configured to open a and close the plus side contact 28b.

The controller 30 adjusts the voltage generator 26 to a predetermined voltage value based on the relationship between the wafer suction force of the holding device 20 and the potential difference which is obtained in advance, so that the holding device 20 has a predetermined voltage value. The wafer suction force is automatically controlled to an appropriate value.

That is, the electric circuit 2 of the voltage generator 26
7, a variable resistor 29 is connected in parallel between the voltage generator 26, the positive electrode member 23, and the ground pin 24, and the controller 30 connects the variable resistor 29 to the operation unit 3.
6 is used to control the voltage value of the voltage generator 26.

The controller 30 includes a setting unit, an ammeter, a storage unit, a calculation unit, a comparison unit and an operation unit.

As shown in FIG. 3 (a), the setting unit 31 determines a predetermined value based on the relationship between the wafer attraction force of the holding device 20 and the voltage between both electrodes corresponding to the potential difference, which is obtained in advance. The target voltage value is set to a variable resistance so that a potential difference due to the target voltage value is generated between the positive electrode member 23 and the wafer 1. Is configured to control the container 29.

The ammeter 32 is configured to measure the current value of the current flowing through the electric circuit 27 when a potential difference is generated between the wafer 1 and the positive electrode member 23 by the voltage generator 26.

As shown in FIG. 3B, for example, the relationship between the wafer suction force of the holding device 20 and the current value flowing in the electric circuit 27 at the time of the suction is obtained in the storage unit 33 in advance. Is remembered.

The calculation unit 34 collates the wafer attracting force according to the voltage value set by the setting unit 31 with the wafer attracting force in the storage unit 33, and the current value as the target value corresponding to the set voltage value. Is configured to calculate.

The comparing section 35 is configured to compare the target current value calculated by the calculating section 34 with the current value measured by the ammeter 32 and calculate the deviation value thereof. . Then, by operating the operation unit 36 of the variable resistor 29 based on the deviation value calculated by the comparison unit 35, the potential difference between the wafer 1 and the main body 21 by the voltage generator 27 is adjusted. It is like this.

Incidentally, the electric circuit 2 of the voltage generator 26
A voltmeter 37 is provided at 7 and is configured to measure the potential difference between the wafer 1 and the positive electrode member 23.

Next, the operation will be described. Here, the case where the wafer 1 of the loader unit 4 is automatically transferred to the processing chamber 3 of the CVD apparatus 2 by the wafer transfer apparatus 10 having the above-described configuration will be described.

In the loader section 4, the wafer storage jig 5 is set on the wafer storage jig Z-direction moving device 6.
When one wafer 1 is discharged from the wafer storage jig 5, the X-direction moving device 1 in the wafer transfer device 10
The No. 1 X-direction moving block 13 is driven by the pulse motor 14 and moved in front of the wafer storage jig Z-direction moving device 6.

Subsequently, the wafer storage jig 5 is moved to an appropriate height by the wafer storage jig Z-direction moving device 6, and the holding device 20 is inserted into the wafer storage jig 5 by the robot 15. . By these coordinated operations, the main body 21 of the holding device 20 is inserted under the wafer 1 to be paid out from the wafer storage jig 5.

Next, the wafer storage jig Z-direction moving device 6
Thus, the wafer storage jig 5 is lowered until the lower surface of the unloaded wafer 1 comes into contact with the surface of the holding device body 21 and the ground pin 24.

When the lower surface of the wafer 1 comes into contact with the main body 21 and the ground pin 24, the changeover switch 28 is changed over to close the plus side contact 28b. When the positive contact 28b of the switch 28 is closed, the voltage generator 26
Therefore, a potential difference is generated between the positive electrode member 23 and the ground pin 24.

Due to the potential difference between the positive electrode member 23 and the ground pin 24, the positive electrode member 23 and the ground pin 24 are
A potential difference is generated between the wafer 1 and the wafer 1 which is in contact with.
Since the main body 21 is made of silicon carbide, which is an example of a dielectric, static electricity is generated between the positive electrode member 23 and the wafer 1. The wafer 1 is attracted and held by the main body 21 by the attraction force due to the static electricity.

When the wafer 1 is adsorbed and held on the main body 21 of the holding device 20 by static electricity, the holding device 20 is retracted by the robot 15 with respect to the wafer storage jig 5. By this retreating operation, the wafer 1 sucked and held by the holding device 20 is unloaded from the wafer storage jig 5.

Subsequently, the X-direction moving block 13 of the X-direction moving device 11 is moved to the front of the processing chamber 3 by driving the pulse motor 14. When the X-direction moving block 13 moves to the front of the processing chamber 3, the holding device 20 holding the wafer 1 is advanced by the robot 15 and the wafer 1 is loaded into the processing chamber 3.

When the wafer 1 is loaded into the processing chamber 3 at a predetermined position, the changeover switch 28 is switched, the plus side contact 28b is opened and the ground side contact 28a is closed. At the same time, the push-up pin 3a in the processing chamber 3 is raised.

When the earth side contact 28a of the changeover switch 28 is closed, the positive electrode member 23 is earthed, so that static electricity is discharged. Therefore, the suction force holding the wafer 1 is released. With the release of the suction force, the wafer 1 is received from the main body 21 of the holding device 20 on the ascending push-up pin 3a of the processing chamber 3.

In the above-described transfer operation, the holding device 20 in the wafer transfer device 10 moves the wafer 1 as the transferred object.
Since the main body 21 supports the wafer 1 from below, the weight of the wafer 1 is mechanically supported by the robot 15 as a transfer device of the wafer transfer device 10.

Therefore, the holding device 20 should hold the wafer 1 by the electrostatic attraction force only by the external force such as the inertial force acting on the wafer 1 during the transfer operation, and the electrostatic attraction force must be kept to the minimum necessary level. The force is the force that can counter this external force.

This inertial force can be theoretically obtained in advance by the relationship between the mass of the wafer and the acceleration during the transfer. By the way, the friction force other than the inertial force can be applied to the wafer 1
It can be theoretically determined in advance by the friction coefficient due to the surface roughness of the main body 21 or the weight of the wafer 1.

Therefore, the minimum required suction force is theoretically calculated in advance for each of the various wafers 1 which are the objects to be conveyed.
Then, for example, the voltage value corresponding to the calculated attraction force is obtained from the inter-electrode voltage-adsorption force characteristic diagram shown in FIG. 3A, and is set as the target voltage value by the setting unit 31.

By the way, during the transfer operation, inertial force or the like acts on the wafer 1, so that the attraction force of the holding device 20 due to static electricity varies. At this time, in this embodiment, since the suction force is suppressed to the minimum necessary amount, the wafer 1 may float with respect to the main body 21 of the holding device 20. When the wafer 1 floats with respect to the main body 21, the main body 21
Since the position of the center of gravity of the wafer 1 and the like changes, the attraction force due to static electricity also varies, and the minimum required attraction force also varies.

When the electrostatic attraction force of the holding device 20 changes, the current value flowing between the wafer 1 and the positive electrode member 23 changes. In the present embodiment, this change in current value is measured by the ammeter 32. This measured value is transmitted from the ammeter 32 to the comparison unit 35.

On the other hand, the target current value is transmitted from the calculation unit 34 to the comparison unit 35. The calculation unit 34 includes a setting unit 3
The wafer attracting force according to the voltage value set by 1 and the wafer attracting force of the storage unit 33 are collated, a current value as a target value corresponding to the set voltage value is calculated in advance, and the current value is calculated. It is transmitted to the comparison unit 35.

The comparing section 35 compares the target current value calculated by the calculating section 34 with the current value of the current measured by the ammeter 32 to calculate the deviation value.

Then, based on the deviation value calculated by the comparison unit 35, the variable resistor 29 in the voltage generating device 26.
The operation unit 36 of is operated. By this operation, the voltage value by the voltage generator 26 is changed and adjusted to the target voltage value, so that the potential difference between the wafer 1 and the positive electrode member 24 is adjusted to an appropriate value.

In this way, the electrostatic attraction force of the holding device 20 is properly feedback-controlled. Therefore, during the transport operation, the holding device 20 is
In addition, the wafer 1 as the transferred object can be always held with the minimum necessary suction force.

That is, the wafer 1 is the main body 2 of the holding device 20.
1 is not excessively pressed, and is not accidentally moved, so that it is properly adsorbed and held. As a result, it is possible to prevent foreign matters in the main body 21 of the holding device 20 from being transferred to the wafer 1, and to prevent accidents such as the wafer 1 accidentally slipping off from the holding device 20 during transportation. can do.

According to the above embodiment, the following effects can be obtained. With the wafer 1 in contact with the holding surface 22 of the main body 21 made of a dielectric material, the wafer 1
Since a potential difference is generated between the positive electrode member 23 and the positive electrode member 23, the wafer 1 can be adsorbed and held on the main body 21 by electrostatic force.

As described above, the wafer 1 has the main body 21.
Since the electrostatic force is attracted and held by the electrostatic force, the attractive force can be controlled by controlling the voltage value for generating the electrostatic force.

Since the voltage value can be changed and adjusted very easily by the voltage generator 26,
The wafer attracting force of the holding device 20 can be easily controlled by the voltage generator 26.

As described above, by controlling the suction force of the holding device 20 with respect to the wafer 1 to a necessary minimum, it is possible to reduce the transfer of the foreign matter from the holding surface 22 to the wafer 1.

Further, the electrostatic attraction of the wafer is
Since it is effective even in a vacuum, the wafer can be transferred even in a vacuum such as the processing chamber 3 of the CVD apparatus.

The wafer 1 is held during electrostatic attraction and holding.
By measuring the change of the current value flowing between the positive electrode member 23 and the positive electrode member 23 with the ammeter 32, the fluctuation of the attraction force due to static electricity of the holding device 20 is detected, and the current measured current value of the ammeter 32, The target current value calculated by the calculation unit 34 is compared in the comparison unit 35 to calculate the deviation value,
By operating the operation unit 36 of the variable resistor 29 in the voltage generator 26 based on the deviation value calculated by the comparison unit 35 to change and adjust the voltage value of the voltage generator 26 to the target voltage value, Since the electrostatic attraction force of the device 20 can be appropriately feedback-controlled,
During the transfer operation, the holding device 20 can always hold the wafer 1 as the transferred object properly with the minimum necessary suction force.

FIG. 5 is a schematic diagram including a circuit diagram showing a wafer transfer apparatus which is Embodiment 2 of the present invention.

The second embodiment differs from the first embodiment in that
The controller 30A controls the potential difference generated by the voltage generator 26.

That is, the controller 30A according to the second embodiment includes a setting unit, a stress meter and a comparing unit. The setting unit 31A is configured to set a predetermined target voltage value based on the relationship between the wafer attraction force of the holding device 20A and the potential difference as shown in FIG.

The stress meter 32A is the main body 2 of the holding device 20A.
The current suction force of the holding device 20A is measured by contacting the wafer 1 attracted to No. 1 and the measured suction force is transmitted to the calculation unit 34A.

In the second embodiment, the stress gauge 32A is incorporated in the ground pin 24A of the holding device 20A, and the suction force applied to the wafer 1 via the ground pin 24A is measured. The stress gauge 32A can be configured by, for example, a strain gauge or a piezoelectric element.

In the storage unit 33A, as shown in FIG. 3A, for example, the relationship between the wafer attraction force of the holding device 20 and the voltage value at the time of attraction, which is obtained in advance, is stored. .

The calculation unit 34A is configured to collate the suction force measured by the stress meter 32A with the wafer suction force of the storage unit 33A and calculate a voltage value corresponding to the measured suction force. There is.

The comparing section 35A compares the voltage value set by the setting section 31A with the voltage value calculated by the calculating section 34A based on the current measured value of the suction force measured by the stress meter 32A. Then, the deviation value is calculated.

Then, the controller 30A uses the variable resistor 29 based on the deviation value calculated by the comparison section 35A.
By operating the operation unit 36 of the voltage generator 26
Is configured to adjust the voltage value of.

Next, the operation will be described. During the transfer operation, the electrostatic attraction force of the holding device 20 changes due to the inertial force acting on the wafer 1. In the second embodiment, the fluctuation of the attraction force due to static electricity is measured by the stress meter 32A. This measurement value is transmitted from the stress meter 32A to the calculation unit 34A.

The calculation unit 34A collates the suction force measured by the stress meter 32A with the wafer suction force of the storage unit 33A to calculate a voltage value corresponding to the measured suction force,
The calculated voltage value is transmitted to the comparison unit 35A.

The comparing unit 35A compares the voltage value preset by the setting unit 31A with the voltage value calculated by the calculating unit 34A based on the current measured value of the suction force measured by the stress meter 32A. Then, the deviation value is calculated.

Then, the variable resistor 2 in the voltage generator 26 is based on the deviation value calculated by the comparison section 35A.
The operation unit 36 of 9 is operated. By this operation, the voltage value by the voltage generator 26 is changed and adjusted to the target voltage value, so that the potential difference between the wafer 1 and the positive electrode member 24 is adjusted to an appropriate value.

As described above, also in the second embodiment, the electrostatic attraction force of the holding device 20A is properly feedback-controlled. Therefore, during the transportation operation, the holding device 20A has the minimum necessary suction force,
The wafer 1 as the transferred object can always be properly held.

That is, the wafer 1 is properly sucked and held without being excessively pressed against the main body 21 of the holding device 20A and without accidentally floating. As a result, it is possible to prevent foreign matter in the main body 21 of the holding device 20A from being transferred to the wafer 1, and to prevent an accident such as the wafer 1 accidentally slipping from the holding device 20A during transportation. can do.

According to the second embodiment, the same effect as that of the first embodiment can be obtained.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Needless to say.

For example, the main body and holding surface of the holding device,
The specific structures of the positive electrode member, the ground pin, the voltage generator, the variable resistor, etc. are not limited to those in the above-described embodiment, but it is desirable to appropriately select them according to the size and weight of the wafer to be held.

The voltage adjusting means for changing and adjusting the voltage value of the voltage generator is not limited to the variable resistor, but other adjusting means may be used.

In the above embodiment, the case where the wafer suction force is feedback-controlled to a proper value has been described, but it is also possible to set a proper value and perform sequence control.

The main body of the holding device is not limited to being formed of silicon carbide, but a resistance value of 10 Ω.
It may be formed of another dielectric material having a size of cm or less.

The moving device for moving the holding device is X
The configuration is not limited to the direction moving device, the SCARA robot, or the like, and may be the articulated robot or the like.

In the above description, the invention mainly made by the present inventor is the field of application which is the background of CVD.
The case where the present invention is applied to the wafer transfer device of the apparatus has been described, but the present invention is not limited to this, and the present invention can be applied to all transfer devices that transfer articles that can be adsorbed by static electricity. In particular, the wafer transfer device according to the present invention is used to transfer a wafer in a vacuum and exhibits excellent effects.

[0092]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows.

With the wafer in contact with the holding surface of the main body, a potential difference is generated between the wafer and the electrode member by the voltage generator, and the wafer is attracted and held by the main body by electrostatic force. Therefore, the attraction force can be controlled by controlling the voltage value for generating the attraction force due to static electricity. Since this voltage value can be changed and adjusted very easily by the voltage generator, the wafer suction force of the holding device can be easily controlled by the voltage generator.

Then, by controlling the suction force of the holding device with respect to the wafer to the minimum necessary amount, it is possible to reduce the transfer of foreign matter from the holding surface to the wafer.

Further, since the electrostatic attraction of the wafer is effective even in a vacuum, the wafer can be transported even in a vacuum.

[Brief description of drawings]

FIG. 1 is a schematic diagram including a circuit diagram showing a wafer transfer apparatus according to an embodiment of the present invention.

2A is a plan view showing the holding device, and FIG. 2B is a front sectional view thereof.

FIG. 3 is each diagram for explaining the operation.

FIG. 4 is a partially omitted perspective view showing a CVD apparatus in which a wafer transfer apparatus is used.

FIG. 5 is a schematic diagram including a circuit diagram showing a wafer transfer apparatus that is Embodiment 2 of the present invention.

[Explanation of sign]

1 ... Wafer, 2 ... CVD apparatus, 3 ... Processing chamber, 4 ... Loader section, 5 ... Wafer storage jig, 6 ... Z direction moving device, 7 ... Guide rail, 8 ... Feed screw shaft, 9 ... Pulse motor, 10
... Wafer transfer device, 11 ... X-direction moving device, 12 ... Guide rail, 13 ... X-direction moving block, 14 ... Pulse motor, 15 ... Robot, 16 ... First arm, 17 ... Second
Arm, 20 ... holding device, 21 ... main body, 22 ... holding surface,
23 ... Positive electrode member, 24 ... Ground pin (negative electrode), 25
... earth pin mounting member, 26 ... voltage generator, 27 ... electric circuit, 28 ... changeover switch, 29 ... variable resistor, 30
... controller, 31 ... setting unit, 32 ... ammeter, 33 ...
Storage unit, 34 ... Calculation unit, 35 ... Comparison unit, 36 ... Operation unit,
37 ... Voltmeter, 30A ... Controller, 31A ... Setting part, 32A ... Stress meter, 33A ... Storage part, 34A ... Calculation part, 35A ... Comparison part.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshiyuki Miyamoto 111 Nishiyokote-cho, Takasaki-shi Gunma Hitachi Takasaki Plant (72) Inventor Hiromitsu Tokisue 502 Kintate-cho, Tsuchiura-shi, Ibaraki Hitsuritsu Co., Ltd. (72) Inventor Hiroyuki Tachibana, 502 Kintate-cho, Tsuchiura-shi, Ibaraki Hiritsu Seisakusho Co., Ltd.

Claims (4)

[Claims] 1. A holding device for sucking and holding a wafer,
In a wafer transfer device including a moving device for moving a holding device, the holding device is formed of a dielectric material having a resistivity of 10 ¹⁰ Ω · cm or less, and a wafer is suction-held on one main surface thereof. A main body having a holding surface, an electrode member arranged on the main surface of the main body opposite to the wafer holding surface, and a voltage generator for generating a potential difference between the electrode member and the wafer are provided. Further, a controller is connected to the voltage generation device, and the controller determines the voltage generation device based on a predetermined relationship between the wafer attraction force of the holding device and the potential difference. By adjusting the voltage value,
A wafer transfer device configured to control the wafer suction force of the holding device to an appropriate value. 2. A controller configured to set a predetermined target voltage value based on a relationship between the wafer attracting force of the holding device and the potential difference, and a potential difference generated between the electrode member and the wafer. Ammeter that measures the current current value at the time, a storage unit that stores in advance the relationship between the wafer suction force of this holding device and the current value at the potential difference at the time of suction, and the storage unit that is set by the setting unit. A calculation unit that calculates a current value as a target value corresponding to the set voltage value by comparing the wafer suction force based on the voltage value with the wafer suction force of the storage unit, and the target current calculated by this calculation unit. A value is compared with a current value measured by the ammeter, and a comparing section for calculating a deviation value thereof is provided. Based on the deviation value calculated by the comparing section, a voltage of the voltage generator is provided. Adjust the value The wafer transfer apparatus according to claim 1, wherein the wafer transfer apparatus is configured as described above. 3. The controller includes a setting unit that sets a predetermined target voltage value based on the relationship between the wafer attracting force of the holding device and the potential difference; and the holding unit in contact with the wafer attracted to the main body. A stress meter that measures the current attraction force of the device, and an attraction force according to the voltage value set by the setting unit,
The present invention includes a comparison unit that compares the current attraction force measured by the stress meter and calculates a deviation value thereof, and the voltage value of the voltage generator based on the deviation value calculated by the comparison unit. The wafer transfer apparatus according to claim 1, wherein the wafer transfer apparatus is configured to adjust 4. The wafer transfer apparatus according to claim 1, wherein a stress gauge is incorporated in a main body of the holding device.