JP2000260849A - Electrostatically levitated carrying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To constantly maintain an initial gap between an object to be carried and an electrode for electrostatic levitation, without depending on positioning accuracy in robot control, when repeatedly carrying the object to be carried. SOLUTION: An applied voltage to electrodes 2a-2d for electrostatic levitating is controlled, based on the detection signal of displacement sensors 4a-4d for detecting the gap between the electrodes 2a-2d for electrostatic levitation and an object 3 to be carried, thus levitating and carrying the object 3 to be measured, using electrostatic force. In this case, the outer end part of the electrodes 2a-2d for electrostatic levitation is provided with a projection 7 for presetting the gap between the electrodes 2a-2d for electrostatic levitating the object 3 to be carried when lifting the object 3 to be measured, thus uniformly maintaining the initial gap between the electrodes 2a-2d for electrostatic levitation and the object 3 to be carried, and setting the levitating to a constant start voltage when levitating the object 3 to be carried.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic levitation transfer apparatus for transferring an object to be transferred such as a silicon wafer or a glass substrate for liquid crystal in a non-contact manner by electrostatic attraction.

[0002]

2. Description of the Related Art Conventionally, in an extremely clean work environment such as the semiconductor industry, an electrostatic levitation transfer device for transferring a plate-like transferred object such as a silicon wafer in a non-contact manner as shown in FIG. Has become. In the figure, reference numeral 1 denotes an electrostatic levitation transfer device, 2 denotes a circular electrode plate made of an insulating substrate, 2a, 2b, 2c, and 2d denote four equally divided portions sandwiching a separation band P on the electrode plate 2. Positive and negative voltages are alternately applied to each electrode by fan-shaped electrostatic levitation electrodes. Reference numeral 3 denotes an object to be conveyed arranged so as to face the electrodes 2a, 2b, 2c and 2d for electrostatic levitation, and the figure shows the case of a silicon wafer. Reference numerals 4a, 4b, 4c, and 4d denote displacement sensors for measuring a gap between the electrostatic levitation electrodes 2a, 2b, 2c, and 2d and the transferred object 3. 5 is the transferred object 3
Electrostatic levitation electrode 2 so that it can float to the target gap
a, a controller for controlling the voltage applied to 2b, 2c, 2d; and 6, a transfer means for holding the upper surface of the electrode plate 2 and transferring the electrode plate 2 by handling. The figure shows an articulated (6-axis) robot. Is shown. In such a configuration, first, the transported object 3 and the electrostatic levitation electrodes 2a, 2b, 2c, 2d are connected to each other by the electrostatic levitation electrodes 2a, 2b, 2c, 2d held at the distal end of the robot 6. The inclination of the electrode plate 2 is adjusted so that the initial gap (for example, 400 μm) is uniform. Then, the electrode 2 for electrostatic levitation
a, a positive bias voltage + V _bias is applied to 2c,
A negative bias voltage -V _{bias is} applied to the electrodes 2b and 2d for electrostatic levitation.
Is applied. Thereafter, when a PID control start signal is input to the controller 5 by a timer (not shown) built in the controller 5, each of the electrostatic levitation electrodes 2a, 2b, 2c,
PID control of an independent feedback loop is started every 2d. After the start of the PID control, the transferred object 3 starts to float because electrostatic force acts between each of the electrostatic levitation electrodes,
Eventually, the levitation becomes stable at the position where the gap signal from the displacement sensors 4a, 4b, 4c, and 4d matches the target gap (for example, 200 μm). The electrode plate 2 on which the transported object 3 is levitated in a non-contact manner is moved by the robot 6
It is transported to the position of the target processing process.

[0003]

However, in the prior art, when an object to be conveyed is levitated and conveyed by an electrode plate held by an articulated robot many times without contact, the object to be conveyed and electrostatic levitation The initial gap between the electrodes for use varies, and in severe cases, the maximum gap changes by about several 100 μm. This is because the repeatability of the initial gap between the transferred object and the electrode for electrostatic levitation depends on the positioning accuracy when controlling the robot. The floating start voltage when the object starts floating also changes by several hundred volts at the maximum. As a result, when the initial gap is narrowed, there is a problem that the transported object rapidly floats at the moment when the bias voltage is applied, and comes into contact with the electrostatic levitation electrode. Also,
Conversely, if the initial gap is wide, the control voltage applied to the controller is insufficient, so that there is a problem that the transferred object does not float. As described above, when the floating control is repeatedly performed on the object to be conveyed by the above-mentioned electrostatic levitation conveyance device, there is a problem that the levitation conveyance cannot be reliably performed. Therefore, the present invention
When repeatedly transporting the transferred object, the initial gap between the transferred object and the electrode for electrostatic levitation can be kept constant without depending on the positioning accuracy at the time of robot control,
It is an object of the present invention to provide an electrostatic levitation transfer device capable of performing stable and stable levitation transfer.

[0004]

According to a first aspect of the present invention, there is provided an electrode plate connected to a holding portion of a transporting means and comprising an insulating substrate; Electrostatic levitation electrodes arranged separately,
An object to be conveyed facing the electrode for electrostatic levitation, a displacement sensor for detecting a gap between the electrode for electrostatic levitation and the object to be conveyed, and a controller for controlling a voltage applied to the electrode for electrostatic levitation And a stage provided on the opposite side of the electrostatic levitation electrode with the object to be transported therebetween, and supporting the object to be transported, wherein the static sensor is provided based on a detection signal of each of the displacement sensors. By controlling the voltage applied to the electrode for electro-levitation, in an electrostatic levitation transport device that levitates and transports the object to be transported using electrostatic attraction, the electrostatic levitation electrode provided on the electrode plate At least one of an outer edge portion and an outer edge portion of the position where the transferred object is supported on the stage, a gap between the electrostatic levitation electrode and the transferred object when floating the transferred object. Provide protrusions for presetting It is characterized in. According to a second aspect of the present invention, there is provided the electrostatic levitation transfer device according to the first aspect, wherein a force in a compression direction is not transmitted between a grip portion of the transfer means and the electrode plate in a tension direction. Is provided with a tension transmitting means for transmitting only the force of
According to a third aspect of the present invention, in the electrostatic levitation and transfer device according to the second aspect, the tension transmitting means includes a first jig including an engagement portion having a substantially U-shaped cross section, and It is constituted by a joint consisting of a second jig having a T-shaped cross section that engages with an engagement portion of one jig, and one of the first jig and the second jig is attached to a grip portion of the transporting means. And the other is connected to the electrode plate. According to a fourth aspect of the present invention, there is provided the electrostatic levitation and transport device according to the first aspect, wherein an elastic member is provided between the grip portion of the transport means and the electrode plate. According to a fifth aspect of the present invention, in the electrostatic levitation transfer device according to any one of the first to fourth aspects, the electrode plate is fixed by a separate support plate, and the electrode plate is fixed to the support plate. The projection is formed integrally. Claim 6
According to the present invention, in the electrostatic levitation transfer device according to any one of the first to fifth aspects, an elastic member is inserted inside the stage. By the above means, even if the transported object is repeatedly transported, the initial gap is always set to be constant, so the initial gap becomes narrower,
There is a problem that the transferred object quickly floats and contacts the electrode for electrostatic levitation at the moment when the bias voltage is applied, and the problem that the initial gap is widened, the control voltage is insufficient, and the transferred object does not float. Floating transfer can be performed without any need.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of an electrostatic levitation transfer device according to a first embodiment of the present invention. 2A and 2B show details of the electrode plate, wherein FIG. 2A is a side view showing a state in which an object to be conveyed is set on a stage so as to face the electrode plate, and FIG. 2B is a plan view of the electrode plate. is there. The same components as those in the related art are denoted by the same reference numerals, and the description thereof will be omitted. Only different points will be described. That is, the electrode plate 2
The point is that a ring-shaped projection 7 is provided so as to surround the outer edges of the electrodes 2a, 2b, 2c, and 2d for electrostatic levitation. In FIG. 2, when a stage 8 on which the transferred object 3 is placed is placed below the transferred object 3, the height h of the projection 7 becomes The thickness of each of the electrostatic levitation electrodes 2a to 2d and the transported object 3 are set so that the distance between the electrostatic levitation electrodes 2a, 2b, 2c, and 2d and the transported object 3 becomes a uniform initial gap (for example, 400 μm). It is designed to have a length that is obtained by adding the initial gap to the thickness. Next, the operation will be described. First, electrode plate 2
The electrode plate 2 is moved toward the stage 8 while the inclination of the electrode plate 2 is adjusted by the robot 6 so that the upper projection 7 contacts the stage 8. After the projection 7 provided on the electrode plate 2 and the stage 8 are completely contacted by the position control of the robot 6, the electrostatic levitation electrodes 2a, 2
The gap between b, 2c, 2d and the transferred object 3 is necessarily set to 400 μm. After that, the electrode 2 for electrostatic levitation
a, 2c are applied with a positive bias voltage + V _bias and the electrostatic levitation electrodes 2b, 2d are applied with a negative bias voltage -V _bias .
Subsequently, when a PID control start signal is input to the controller 5 by a timer in the controller 5, PID control of an independent feedback loop is started for each electrostatic levitation electrode. After the start of the PID control, the transferred object 3 starts to float, and the floating of the transferred object 3 is stabilized at a position where the gap signal from the displacement sensors 4a, 4b, 4c, and 4d matches the target gap (for example, 200 μm). Then, after the transferred object 3 floats, the transferred object 3 is transferred to a target position by the robot 6 connected to the electrode plate 2. With the first embodiment having such a configuration, the initial gap between the transferred object and the electrode for electrostatic levitation does not vary when the transferred object is repeatedly transferred,
Since the uniform initial gap is maintained, the floating start voltage when floating the transported object can be set to be constant. In addition, when the initial gap becomes too small, the problem that the transferred object rapidly floats and contacts the electrostatic levitation electrode at the moment when the bias voltage is applied is solved. Conversely, when the initial gap becomes excessively large, the problem that the transferred object does not float because the control voltage applied to the controller is insufficient is solved. Thus, the present invention is more reliable and stable. Electro-levitation transport can be performed.

Next, a second embodiment of the present invention will be described. 3A and 3B show an electrostatic levitation device according to a second embodiment of the present invention, wherein FIG. 3A is a side view showing a state in which an object to be carried is set on a stage so as to face an electrode plate, and FIG. Is a plan view of the stage. In the present embodiment, a controller is omitted for simplification of the drawing, and the same applies to the third and subsequent embodiments. In the figure, the difference from the first embodiment is that the outer edge of the transferred object 3 placed on the stage 8 is replaced with the configuration in which the projection is provided on the electrode plate 2 shown in the first embodiment. This is a point in which hemispherical projections 9 are provided at equal intervals in the portion, and here, an example in which three projections 9 are provided is shown. The height h of the projection 9 is such that when the projection 9 comes into contact with the electrode plate 2, each of the electrostatic levitation electrodes 2a, 2b, 2c,
The thickness of each electrode for electrostatic levitation and the thickness of the object to be transported are designed so that the initial gap is added so that the distance between 2d and the object to be transported 3 becomes a uniform initial gap (for example, 400 μm). Have been. Next, the operation will be described. First, so that the electrode plate 2 comes into contact with the projection 9 on the stage 8,
The electrode plate 2 is moved toward the stage 8 while the inclination of the electrode plate 2 is adjusted by the robot 6.
By controlling the position of the robot 6, the electrostatic levitation electrodes 2a, 2a
The gap between b, 2c, 2d and the transferred object 3 is necessarily set to 400 μm. Note that the subsequent operation relating to the levitation control is the same as that of the first embodiment, and a description thereof will be omitted. In the second embodiment, with such a configuration, the initial gap between the transferred object and the electrode for electrostatic levitation varies when the transferred object is repeatedly transported, similarly to the first embodiment. Therefore, the initial gap is maintained at a uniform value, so that the floating start voltage for floating the transferred object can be set to be constant.

Next, a third embodiment of the present invention will be described.
FIG. 4 is a configuration diagram of an electrostatic levitation transport apparatus according to a third embodiment of the present invention. FIG. 5 is a schematic view of the electrostatic levitation transport apparatus shown in FIG. It is a side view which shows the state which set the thing. In the figure, the first,
The differences from the second embodiment are as follows. The outer periphery of the electrode plate 2 and the electrostatic levitation electrodes 2a, 2b, 2c,
It is a point that hemispherical protrusions 10 are provided at equal intervals along the circumferential direction between the outer periphery of the protrusions 2d and the height h of the protrusions 10 as in the first embodiment. Stage 8
The height is set in consideration of the case of contact with. Also,
Instead of the vertical articulated robot used in the first and second embodiments, the robot uses a θ-Z type robot 61 having two motion functions of a turning motion and a vertical motion in a horizontal plane. It is. The gripper 6a is configured to indirectly move up and down and rotate via an elevating shaft 12 and a turning arm 13 provided on the robot 61. Further, between the electrode plate 2 and the grip portion 6a connecting the robot 61, a tension transmitting means for transmitting no force in the compression direction to the electrode plate 2 and transmitting only a force in the tension direction to the electrode plate 2; In that the joint 11 is provided. As shown in FIG. 5, the structure of the joint 11 includes a first jig 11a having a substantially U-shaped cross section, having an engaging portion connected to the grip portion 6a of the robot 61 and opening downward, and an electrode plate. 2 and is engaged with the engagement portion of the first jig 11a.
And a second jig 11b having a U-shaped cross section. When tension is applied between the two jigs of the joint 11. 2nd jig 11b
Point B contacts point A of the first jig 11a to transmit the force. Conversely, when a compressive force acts from the first jig 11a toward the electrode plate 2 between the two jigs, the second jig 1
The point B of 1b and the point A of the first jig 11a do not transmit a separating force. Next, the operation will be described with reference to FIG. FIGS. 6A and 6B are diagrams showing an operation process in which an object is levitated by an electrode plate, wherein FIG. 6A shows step 1 of the operation process, FIG.
(C) is step 3 of the operation process, and (d) is step 4 of the operation process. (Step 1) The robot 61 moves the electrode plate 2 onto the stage 8. (Step 2) As the gripping portion 6a of the robot 61 is gradually lowered, the projection 10 on the electrode plate 2 comes into contact with the stage 8 until the point B of the second jig 11b and the first jig 11a.
Point A leaves. At this point, the protrusions 1 on the electrode plate 2
0 comes into contact with the stage 8, and the gap between the electrostatic levitation electrodes 2a, 2b, 2c, 2d and the object 3 is
It is inevitably set to 400 μm. (Step 3) A positive bias voltage + V _bias is applied to the electrostatic levitation electrodes 2a and 2c, and a negative bias voltage -V _bias is applied to the electrostatic levitation electrodes 2b and 2d. Thereafter, when a PID control start signal is input to a controller (not shown) by a timer in a controller (not shown), PID control of an independent feedback loop is started for each electrostatic levitation electrode. After the start of the PID control, the transferred object 3 starts to float,
Eventually, at a position where the gap signal from the displacement sensor (not shown) matches the target gap (for example, 200 μm), the floating of the transferred object 3 becomes stable. (Step 4) After the transferred object 3 has floated, the gripping portion 6a of the robot is gradually raised upward, and the second
The point B of the jig 11b comes into contact with the point A of the first jig 11a, and the electrode plate 2 also starts to rise. Thereafter, the transferred object 3 is transferred to a target position by the connected robot (not shown). In the third embodiment, by adopting such a configuration, similar to the first and second embodiments, when the object to be transported is repeatedly transported, the initial distance between the object to be transported and the electrode for electrostatic levitation is reduced. Since the gap does not vary and the uniform initial gap is maintained, the floating start voltage for floating the transported object can be set constant. Also,
Compared to the first and second embodiments, the insertion of the joint between the electrode plate and the gripper allows the robot to tilt the electrode plate when setting the initial gap between the electrode plate and the object to be transferred. Since the trouble of performing the adjustment can be omitted, an inexpensive robot having a small degree of freedom can be used as the transfer means.

Next, a fourth embodiment of the present invention will be described. FIG. 7 is a configuration diagram of an electrostatic levitation transfer device according to a fourth embodiment of the present invention. In the figure, the electrostatic levitation electrode 2
The configuration of the protrusions provided on the outer edges of a to 2d and the setting of the height of the protrusions are the same as those in the third embodiment. The fourth embodiment is different from the third embodiment in that between the electrode plate 2 and the holding portion 6a of the robot 61, there are two connecting members 15 which are rigid bodies made of metal, and between the connecting members 15. The elastic member 16 made of rubber sandwiched is inserted and provided. Next, the operation will be described. The robot 61 moves the electrode plate 2 held by the holding portion 6 a of the robot by gradually lowering it toward the stage 8. At this time,
When at least one of the protrusions 10 on the electrode plate 2 contacts the stage 8, the rubber 16 is compressed. When the gripper 6a of the robot is sufficiently lowered, the entire rubber 16 is compressed, and all the protrusions 10 on the electrode plate 2 come into contact with the stage 8. At this time, the electrostatic levitation electrodes 2a,
The gap between 2b, 2c, 2d and the transferred object 3 is necessarily set to 400 μm. Note that the subsequent operation relating to the levitation control is the same as in the third embodiment, and a description thereof will be omitted. In the fourth embodiment, by adopting such a configuration, similar to the first to third embodiments,
When transporting the transported object repeatedly, the initial gap between the transported object and the electrode for electrostatic levitation does not vary, and the uniform initial gap is maintained. The flying start voltage can be set constant. Also, compared to the first to third embodiments, the insertion of the elastic member between the electrode plate and the gripper allows the robot to use the electrode when setting the initial gap between the electrode plate and the transferred object. Since the trouble of adjusting the inclination of the plate can be omitted, an inexpensive robot having a small degree of freedom can be used as the transfer means.

Next, a fifth embodiment of the present invention will be described. FIG. 8 is a cross-sectional view of the electrostatic levitation device according to the fifth embodiment. In the figure, the configuration of the protrusions provided on the outer edges of the electrostatic levitation electrodes 2a to 2d and the setting of the heights of the protrusions are the same as in the third and fourth embodiments. The fifth embodiment is different from the third and fourth embodiments in that an elastic member 17 made of rubber is provided between the stages 8. Next, the operation will be described. The electrode plate 2 is moved on the stage 8 by the robot 6. As the gripper 6a of the robot is gradually lowered, at least one of the protrusions 10 on the electrode plate 2 comes into contact with the stage 8 and a part of the rubber 17 is compressed. Subsequently, when the gripper 6 a of the robot 6 is sufficiently lowered, the entire rubber 17 is compressed, and all the protrusions 10 on the electrode plate 2 come into contact with the stage 8. At this time, the electrodes 2a, 2b, 2c, 2
The gap between d and the transferred object 3 is necessarily set to 400 μm. Note that the subsequent operation relating to the levitation control is the same as that of the third embodiment, and a description thereof will be omitted. Since the fifth embodiment has such a configuration, similar to the first to fourth embodiments, when the object to be transported is repeatedly transported, the initial gap between the object to be transported and the electrode for electrostatic levitation is set. Since the initial gap is maintained without variation, the floating start voltage when floating the transported object can be set to be constant. In addition, the rubber laid inside the stage allows
Since the compression force when the projection of the electrode plate comes into contact with the stage can be reduced, damage to the projection of the electrode plate can be prevented, and highly reliable electrostatic levitation conveyance can be performed. In the fifth to fifth embodiments, the following configuration may be adopted. (1) A plurality of hemispherical protrusions may be provided on the outer edge of the electrode for electrostatic levitation instead of having a ring-shaped protrusion on the electrode plate side. (2) If the stage has a hemispherical projection on the stage side, a ring-shaped projection may be provided on the outer edge of the electrode for electrostatic levitation instead. (3) If the electrode plate has a ring-shaped or hemispherical projection, a support plate made of an insulator or a conductor for supporting the electrode plate is arranged above the electrode plate, and an initial gap setting is formed on the support plate. May be integrally formed. (4) When hemispherical projections are provided on the electrode plate or stage, the number of projections is preferably three, but may be any other number as needed. (5) Although the description has been made on the assumption that the transferred object is a silicon wafer, when a liquid crystal glass or the like, which is a dielectric, is used as the transferred object, the shape of the electrode for electrostatic levitation may be changed to, for example, a rectangular shape. Good. (6) When setting by repeatedly setting the parallelism between the transferred object and the electrode for electrostatic levitation, the trouble of adjusting the inclination of the electrode plate is simplified, so that the θ-Z robot can be used without using an expensive articulated robot. Alternatively, a slider may be used. (7) In addition to a silicon wafer, a glass plate for liquid crystal or an Al-Ti-carbide wafer may be used as the transferred object, and the present invention is not limited thereto. (8) When adjusting the inclination of the electrode plate, force control may be performed instead of position control of the robot. Further, in the third embodiment, the tension transmitting means may be a flexible and flexible chemical fiber string, wire, rope or other chain. Further, in the fourth and fifth embodiments, an elastic mechanical part such as a coil spring or a leaf spring or a bellows may be used instead of rubber. Further, particularly in the fourth embodiment, at least one of the two rigid bodies sandwiching the elastic member may be omitted, and the rubber may be directly attached to the grip portion or the electrode plate of the robot.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As a first embodiment, the first embodiment shown in FIGS.
The electrostatic levitation transfer of the silicon wafer was carried out using the embodiment. The protrusion 7 is made of aluminum and fixed to the electrode plate 2. The height of the protrusion 7 from the electrode plate surface is 725 ± 25 μm, which is the thickness of the silicon wafer.
Initial setting gap 400μm, Electrostatic levitation electrode thickness 3
The following equation was calculated from 5 μm, and was set to 1160 μm.
The target gap during flying was set to 200 μm. (725 ± 25) + 400 + 35 = 1160 ± 25 Using a 6-axis industrial robot, a floating test was repeated 200 times. Displacement sensor 4a,
The variation of the initial gap confirmed in 4b, 4c, and 4d was within ± 25 μm. This variation was mainly due to variation in the thickness of the silicon wafer,
As a result of the levitation test, the problem that the transferred object was in contact with the electrode for electrostatic levitation and that the transferred object did not float on the contrary never occurred, and the levitation transfer was reliably performed. As another embodiment, as shown in FIG. 9, in this electrostatic levitation transfer device, a support plate 18 made of aluminum is provided above the electrode plate 2, and the projections 7 are cut out of the support plate 18 to be integrally processed. In this case, the silicon wafer was transported reliably by electrostatic levitation.

As a second example, an electrostatic levitation transfer of a silicon wafer was performed using the second embodiment shown in FIG. The protrusion 9 was made of metal having a diameter of 1200 μm and three hemispherical balls were arranged at equal intervals, and bonded to the stage 8.
Therefore, the following formula was calculated from the thickness 725 ± 25 μm of the silicon wafer and the thickness 35 μm of the electrode for electrostatic levitation, and the initial gap set was 440 ± 25. The target gap during flying was set to 200 μm. 1200− (725 ± 25) −35 = 440 ± 25 As the transfer means 6, a 6-axis industrial robot was used.
Actually, the floating test was repeated 200 times. The variation of the initial gap confirmed by the displacement sensors 4a, 4b, 4c, and 4d was within ± 25 μm. This variation was mainly due to the variation in the thickness of the silicon wafer.However, as a result of the floating test, the problem that the transferred object comes into contact with the electrode for electrostatic levitation or that the transferred object did not float was confirmed. It never occurred once, and it was possible to carry out levitation reliably.

As a third example, electrostatic levitation transfer of a silicon wafer was performed using the third embodiment shown in FIGS. The protrusion 10 was formed by bonding three hemispherical balls made of metal having a diameter of 1200 μm to the electrode plate 2. Therefore, the set initial gap is set to the thickness 725 of the silicon wafer.
The following equation was calculated from ± 25 μm and the thickness of the electrode for electrostatic levitation of 35 μm, and was 440 ± 25. The target gap during flying was set to 200 μm. 1200− (725 ± 25) −35 = 440 ± 25 As the transfer means 6, a θ-Z robot was used. Here, the electrostatic levitation test was actually repeated 200 times by the electrode plate 2 via the joint 11 connected to the holding portion of the robot 61. Displacement sensors 4a, 4b, 4
c, variation of the initial gap confirmed in 4d is ± 25
It was within μm. This variation was mainly due to the variation in the thickness of the silicon wafer. However, as a result of the floating test, as in the first and second embodiments, the transferred object came into contact with the electrostatic levitation electrode, The problem that the conveyed object does not float at all has never occurred. Also, during the setting of the initial gap, reliable floating conveyance was performed without adjusting the inclination of the electrode plate by the robot.

As a fourth example, a silicon wafer was electrostatically levitated and transported using the fourth embodiment shown in FIG. The protrusion 10 was formed by bonding three spherical balls made of metal having a diameter of 1200 μm to the electrode plate 2. Therefore, the set initial gap is 725 ± 25 of the thickness of the silicon wafer.
The following equation was calculated based on μm and the thickness of the electrostatic levitation electrode of 35 μm, and the result was 440 ± 25. The target gap during flying was set to 200 μm. 1200− (725 ± 25) −35 = 440 ± 25 Between the gripping part of the robot and the electrode plate, the one in which rubber 16 was sandwiched between two aluminum rigid bodies 15 was connected. The thickness of the rubber 16 is 100 mm. At the time of the initial gap setting, the gripper 6a of the robot 61
When it came into contact with the electrode plate 2 via the joint 11 and descended sufficiently, the rubber 16 was compressed by about several mm. Here, the floating test was actually repeated 200 times. The variation of the initial gap confirmed by the displacement sensors 4a, 4b, 4c, and 4d was within ± 25 μm. This variation was mainly due to the variation in the thickness of the silicon wafer. However, as a result of the levitation test, as in the first to third embodiments, the transferred object came into contact with the electrostatic levitation electrode, or the reverse. The problem that the conveyed object does not float at all has never occurred.
Also, during the setting of the initial gap, reliable floating conveyance was performed without adjusting the inclination of the electrode plate by the robot.

As a fifth example, an electrostatic levitation transfer of a silicon wafer was performed using the fifth embodiment shown in FIG. The protrusion 10 was formed by bonding three spherical balls made of metal having a diameter of 1200 μm to the electrode plate 2. Therefore, the set initial gap is 725 ± 25 of the thickness of the silicon wafer.
The following equation was calculated based on μm and the thickness of the electrostatic levitation electrode of 35 μm, and the result was 440 ± 25. The target gap during flying was set to 200 μm. 1200− (725 ± 25) −35 = 440 ± 25 Rubber 1 between the aluminum stage 8 and the iron base 18
7 was laid. The thickness of the rubber 17 is 100 mm,
Several millimeters have been compressed due to the weight of the stage 8. When the gripper 6a of the robot 6 was sufficiently lowered toward the electrode plate during the initial gap setting, the rubber 17 was further compressed by several mm. Actually, the floating test was repeated 200 times. Displacement sensors 4a, 4b, 4c, 4
The variation of the initial gap confirmed in d was within ± 25 μm. This variation is mainly due to the variation in the thickness of the silicon wafer. As a result of the levitation test, as in the first to fourth embodiments, the transferred object comes into contact with the electrode for electrostatic levitation or, conversely, The problem that the transferred object does not float has never occurred. Also, during the setting of the initial gap, reliable floating conveyance was performed without adjusting the inclination of the electrode plate by the robot.

[0015]

As described above, according to the present invention, in the electrostatic levitation transport device, the outer edge of the electrostatic levitation electrode provided on the electrode plate or the outer edge of the transferred object provided on the stage. In any one, so that the electrode for electrostatic levitation does not contact the object to be transported, so as to have a configuration provided with a projection for presetting the gap between the electrode for electrostatic levitation and the object to be transported, repeatedly When the transported object is transported, the initial gap between the transported object and the electrode for electrostatic levitation does not vary. As a result, the uniform initial gap is maintained, so that the floating start voltage for floating the transported object can be set to be constant. In addition, when the initial gap becomes too small, the problem that the transferred object rapidly floats and contacts the electrostatic levitation electrode at the moment when the bias voltage is applied is solved. Conversely, when the initial gap becomes excessively large, the problem that the transferred object does not float because the control voltage applied to the controller is insufficient is solved. Thus, the present invention is more reliable and stable. There is an effect that electro-levitation transport can be performed. In addition, by inserting a joint between the electrode plate and the gripper of the robot, or by inserting an elastic member between the electrode plate and the gripper, the initial gap between the electrode plate and the transferred object can be set. This eliminates the need for the robot to adjust the inclination of the electrode plate, so that an inexpensive robot with a small degree of freedom can be used as a transport means.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an electrostatic levitation transfer device according to a first embodiment of the present invention.

FIG. 2 shows details of an electrode plate,
(A) is a side view which shows the state which carried the to-be-transferred object on the stage facing an electrode plate, (b) is a top view of an electrode plate.

FIG. 3 is an electrostatic levitation apparatus according to a second embodiment of the present invention, in which (a) is a side view showing a state in which an object to be conveyed is set on a stage so as to face an electrode plate, and (b). Is a plan view of the stage.

FIG. 4 is a configuration diagram of an electrostatic levitation transfer device according to a third embodiment of the present invention.

5 is a side view showing a state in which an object to be transferred is set on a stage so as to face an electrode plate in the electrostatic levitation transfer device shown in FIG. 4;

FIGS. 6A and 6B are diagrams showing an operation process in which an object is levitated by an electrode plate, wherein FIG. 6A is step 1 of the operation process, FIG. 6B is step 2 of the operation process, and FIG.
Is step 3 of the operation process, and (d) is step 4 of the operation process.

FIG. 7 is a configuration diagram of an electrostatic levitation transfer device according to a fourth embodiment of the present invention.

FIG. 8 is a sectional view of an electrostatic levitation device according to a fifth embodiment of the present invention.

FIG. 9 is a cross-sectional view of an electrostatic levitation and conveyance device showing another embodiment of the first embodiment.

FIG. 10 is a configuration diagram of an electrostatic levitation transfer device showing a conventional example.

[Explanation of symbols]

 1: Electrostatic levitation transport device 2: Electrode plate 2a, 2b, 2c, 2d: Electrostatic levitation electrode 3: Transferred object 4a, 4b, 4c, 4d: Displacement sensor 5: Controller 6: Transport means (robot) 7: Projection 8: Stage 8: Projection 10: Projection 11: Joint 11a: First jig 11b: Second jig 12: Elevating shaft 13: Swivel arm 15: Connecting member 16: Elastic member (rubber) 17: Elastic member (rubber) 18) Support plate

Claims (6)

[Claims] An electrode plate connected to a grip portion of a transporting means and formed of an insulating substrate; an electrode for electrostatic levitation divided and arranged on the electrode plate; and an electrode facing the electrode for electrostatic levitation. The transferred object, a displacement sensor that detects a gap between the electrostatic levitation electrode and the transferred object, a controller that controls a voltage applied to the electrostatic levitation electrode, and the transferred object A stage provided on the opposite side of the electrostatic levitation electrode, and supporting the transferred object,
By controlling the voltage applied to the electrode for electrostatic levitation based on the detection signal of each of the displacement sensors, in the electrostatic levitation transport device to levitate and transport the transported object using electrostatic suction force, The static movement at the time of floating the transferred object to at least one of the outer edge of the electrode for electrostatic levitation provided on the electrode plate and the outer edge of the position on the stage where the transferred object is supported. An electrostatic levitation transport device, wherein a projection for presetting a gap between an electrode for electrolevitation and the object to be transported is provided. 2. The static electricity transmission device according to claim 1, further comprising a tension transmission means for transmitting only a force in a tension direction without transmitting a force in a compression direction, between the grip portion of the transport means and the electrode plate. Electro-levitation transfer device. 3. A first jig having an engaging portion having a substantially U-shaped cross section, and a second jig having a T-shaped cross section engaged with the engaging portion of the first jig. 3. The electrostatic levitation transfer according to claim 2, wherein one of the first jig and the second jig is connected to a grip portion of the transfer means and the other is connected to the electrode plate. apparatus. 4. The electrostatic levitation transfer device according to claim 1, wherein an elastic member is provided between a grip portion of the transfer means and the electrode plate. 5. The electrostatic levitation transfer device according to claim 1, wherein the electrode plate is fixed by a separate support plate, and the support plate and the projection are integrally formed. 6. The electrostatic levitation transfer device according to claim 1, wherein an elastic member is inserted inside the stage.