JP2012104511A - Noncontact electrostatic chuck - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a noncontact electrostatic chuck that holds even a soft, thin workpiece with low stiffness in a noncontact manner without causing a regional deformation in the workpiece.SOLUTION: A noncontact electrostatic chuck 1 allows a workpiece to be floated by air discharged from a nozzle 4 provided on a base surface 2a, and also allows the workpiece to be attracted to the base 2a by electrostatic force by applying voltages to electrodes 3 provided on the base surface 2a. The nozzle 4 surrounds at least part of a region where the electrodes 3 are provided, and extends at an angle with respect to the base surface 2a so as to open on the base surface 2a toward inside of the surrounded region X. Depending on distances from center thereof, the region X is divided into a plurality of subregions (X1, X2, X3, and X4). The noncontact electrostatic chuck 1 has an electrostatic force regulator 9 that controls electrostatic force independently in the respective subregions.

Description

  The present invention relates to a non-contact type electrostatic chuck.

  Conventionally, an apparatus described in Patent Document 1 below is known as an apparatus for holding a workpiece in a non-contact manner. This device has a configuration in which air is blown out from a nozzle provided on the base surface to float the work, and a voltage is applied to the electrode provided on the base surface to attract the work to the base surface with electrostatic force. Yes. According to this configuration, the workpiece can be handled while being held in a non-contact manner at an accurate position.

JP 2001-63824 A

By the way, in the structure of the said prior art, there exists a possibility that it cannot apply to a thin work with soft and low rigidity.
The above-described conventional technology has a configuration in which air is blown out straight with respect to the base surface to float the workpiece. If it does so, the pressure distribution of the air to spray will become non-uniform | heterogenous with respect to a workpiece | work, and in the case of a thin workpiece, it will deform | transform locally so that it may wave at an air spraying position. Thus, when the workpiece is locally deformed and the posture becomes unstable, handling is difficult, and a part of the workpiece may come into contact with the electrode.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a non-contact type electrostatic chuck that can be held in a non-contact manner without causing local deformation even with a thin workpiece having a soft and low rigidity.

In order to solve the above-described problems, the present invention is configured to eject air from a nozzle provided on a base surface to float the work, and apply a voltage to an electrode provided on the base surface to electrostatically charge the work. A non-contact electrostatic chuck that pulls toward the base surface with force, wherein the nozzle surrounds at least a part of the region in which the electrode is provided and faces the base surface toward the inside of the enclosed region. In the above-mentioned enclosed region, it is divided into a plurality of regions according to the distance from the center of the region, and the electrostatic force is independently adjusted for each of the plurality of regions. A configuration having an electrostatic force adjusting device is employed.
By adopting this configuration, the present invention forms an air reservoir in a region surrounded by a nozzle that extends obliquely with respect to the base surface and opens, and the workpiece is greatly bent in the enclosed region ( Let it rise). And this invention divides | segments into several area | region according to the distance from the center of this enclosed area | region, and adjusts the electrostatic force in this several area | region independently, and is suitable according to the bending of a workpiece | work. Pulling, minimizes bending of the workpiece and stabilizes the posture.

In the present invention, the electrostatic force adjusting device employs a configuration in which the electrostatic forces in the plurality of regions are independently adjusted so that the electrostatic force increases toward the center.
By adopting this configuration, in the present invention, the electrostatic force of the plurality of regions is independently adjusted so that the electrostatic force becomes larger toward the center of the region surrounded by the nozzles. Appropriate pulling according to the bending.

Further, in the present invention, a distance meter is provided in at least one of the plurality of regions and measures a distance between the workpiece and the base surface, and the electrostatic force adjusting device includes the distance meter. Based on the measurement result, a configuration is adopted in which the electrostatic forces in the plurality of regions are independently adjusted.
By adopting this configuration, the present invention independently adjusts electrostatic force in the plurality of regions based on an actual distance between at least one workpiece and the base surface among the plurality of regions, Optimize work drawing in the multiple areas.

Moreover, in this invention, the structure that the extending direction of the electrode in an adjacent area | region is a direction which mutually cross | intersects among said several area | regions is employ | adopted.
By adopting this configuration, the present invention suppresses unintentional slip in the direction along the base surface of the workpiece by intersecting the extending directions of the electrodes in adjacent regions among the plurality of regions.

In the present invention, the distance meter is provided in at least one of the plurality of regions, and is provided in at least one of the plurality of regions, and a distance meter for measuring a distance between the workpiece and the base surface. A configuration is adopted in which a second nozzle that sucks air or injects air between the workpiece and the base surface based on the measurement result of the distance meter is employed.
By adopting this configuration, the present invention is capable of inhaling air between the work and the base surface based on the actual distance between at least one work and the base surface among the plurality of regions. Use jetting to optimize the amount of air that lifts the workpiece.

According to the present invention, air is blown out from a nozzle provided on the base surface to float the work, and a voltage is applied to the electrode provided on the base surface to attract the work to the base surface with electrostatic force. In the non-contact electrostatic chuck, the nozzle surrounds at least a part of a region where the electrode is provided and opens obliquely with respect to the base surface toward the inside of the surrounded region. In the enclosed area, the apparatus is divided into a plurality of areas according to the distance from the center of the area, and has an electrostatic force adjusting device that independently adjusts the electrostatic force for each of the plurality of areas. By adopting the configuration, an air reservoir is formed in an area surrounded by nozzles that open obliquely with respect to the base surface. While greatly bent (while inflated) to float. And this invention divides | segments into several area | region according to the distance from the center of this enclosed area | region, and adjusts the electrostatic force in this several area | region independently, and is suitable according to the bending of a workpiece | work. Pulling, minimizes bending of the workpiece and stabilizes the posture.
Therefore, in the present invention, even a thin workpiece with soft and low rigidity can be held without contact without causing local deformation.

It is a top view which shows the structure of the non-contact-type electrostatic chuck in 1st Embodiment of this invention. It is arrow AA sectional drawing in FIG. It is sectional drawing which shows the structure of the non-contact-type electrostatic chuck in 2nd Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a plan view showing a configuration of a non-contact electrostatic chuck 1 according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the line AA in FIG. In FIG. 1, in order to improve visibility, the electrode 3 provided on the base surface 2a is hatched.
The non-contact type electrostatic chuck 1 of the present embodiment is a device that handles a thin workpiece W having a thickness of about 10 μm to 20 μm while supporting it in a non-contact manner.

  The non-contact type electrostatic chuck 1 has a configuration in which air is ejected from a nozzle 4 provided on the base surface 2a to float the workpiece W (see FIG. 2). The base surface 2 a constitutes the top part of the base part 2. As shown in FIG. 1, the nozzle 4 is provided so as to surround at least a part of a region where the electrode 3 is provided. The nozzle 4 of the present embodiment has a rectangular frame shape in plan view, and is open to the base surface 2a. Hereinafter, a region surrounded by the nozzle 4 is referred to as a region X. A region outside the nozzle 4 is referred to as a region Y.

  As shown in FIG. 2, the nozzle 4 opens obliquely with respect to the base surface 2 a toward the inside of the region X. Therefore, the nozzle 4 is configured to be able to eject air obliquely from four directions toward the region X. The nozzle channel 4 a is formed in the base portion 2. The nozzle channel 4a of the present embodiment is formed by inserting the convex member 6 into the concave member 5 with a gap. The nozzle flow path 4 a communicates with the inside of the chamber 7 connected to the back surface side of the base portion 2. In the chamber 7, air is pumped from an air supply source (not shown) (fan, blower, etc.).

  The non-contact type electrostatic chuck 1 applies a voltage to the electrode 3 provided on the base surface 2a, thereby attracting the workpiece W floating on the air to the base surface 2a by electrostatic force and holding the posture of the workpiece W horizontally. It is the composition to do. Specifically, the non-contact type electrostatic chuck 1 is configured to apply a voltage to the electrode 3 provided in the region X, inductively charge the workpiece W, and attract the workpiece W by electrostatic force. The electrode 3 provided in the region Y is configured to hold the position of the work W (position restoration) by applying an electric repulsive force to the end of the work W.

  As shown in FIG. 1, the region X is divided into a plurality of regions according to the distance from the center. Hereinafter, a central region including the center of the region X is referred to as a divided region X1, a region surrounding the divided region X1 is referred to as a divided region X2, and a region surrounding the divided region X2 is referred to as a divided region X3. A region surrounding the region X3 in a ring shape is referred to as a divided region X4.

  The electrode 3 extends linearly in a stripe shape with a predetermined pitch along the surface direction of the base surface 2a. Of the plurality of regions (X1, X2, X3, X4), the extending direction of the electrode 3 in the adjacent region is a direction crossing each other. In the present embodiment, the extending directions of the electrodes 3 in adjacent regions among the plurality of regions (X1, X2, X3, and X4) are orthogonal to each other. According to this configuration, since the arrangement of the electrodes 3 intersects, unintended slippage of the workpiece W in the direction along the base surface 2a can be suppressed when an electrostatic force is applied.

  The non-contact electrostatic chuck 1 includes an electrostatic force adjusting device 9 that independently adjusts electrostatic force for each of a plurality of regions (X1, X2, X3, X4). The electrostatic force adjusting device 9 includes a corresponding power supply device (not shown) for each of a plurality of regions (X1, X2, X3, X4), and is configured to variably control the voltage applied to the electrode 3 in each region. . If the electrostatic force becomes uniform for each of the plurality of regions, the electrodes 3 may be wired in series or in parallel for each of the plurality of regions, and the current may be independently applied to each of the electrodes 3. It is good also as a structure which flows.

  A distance meter 8 for measuring the distance between the workpiece W and the base surface 2a is provided in each of the plurality of regions (X1, X2, X3, X4). As the distance meter 8, for example, a non-contact type laser assembly sensor can be used. The electrostatic force adjusting device 9 is electrically connected to the distance meter 8 and is configured to receive measurement results in each region. And the electrostatic force adjustment apparatus 9 becomes a structure which adjusts the electrostatic force of several area | region (X1, X2, X3, X4) independently based on this measurement result.

Subsequently, a specific operation of the non-contact electrostatic chuck 1 having the above-described configuration will be described.
First, air is pumped from an air supply source (not shown), and the pressure in the chamber 7 is increased. When the pressure inside the chamber 7 is increased, air is introduced into the nozzle flow path 4a. The air introduced into the nozzle flow path 4a becomes an inward flow toward the region X and is ejected from each nozzle 4 to the base surface 2a. The air jetted from the nozzles 4 to the base surface 2 a forms an air reservoir G between the region X and the workpiece W. The air reservoir G causes the workpiece W to float with respect to the base surface 2a.

  In a state where no electrostatic force is applied, the air pocket G causes the workpiece W to float while being greatly bent (expanded) in the region X (indicated by a two-dot chain line in FIG. 2). That is, the air ejected from each nozzle 4 is directed from the four sides of the region X to the inside, and the air joins at the center of the region X. Therefore, as shown in FIG. It can be made simple. Thereby, the workpiece | work W can be levitated without accompanying local deformation like the past. In addition, by making the bending of the workpiece W accompanying the air levitation integral and simple, it is possible to easily perform appropriate pulling according to the bending of the workpiece W described below.

  The electrostatic force adjusting device 9 adjusts the electrostatic force independently for each of the plurality of regions (X1, X2, X3, X4), draws the workpiece W to the base surface 2a, and minimizes the deflection caused by air levitation, Stabilize the posture approximately horizontally. The deflection of the workpiece W due to air levitation has a distribution that is greatest at the center of the region X and gradually decreases toward the end. Since the region X of the present embodiment is divided into a plurality of regions (X1, X2, X3, X4) according to the deflection distribution of the work W accompanying air levitation, the electrostatic force is individually adjusted in each region. Thus, the posture of the workpiece W can be appropriately stabilized.

  Specifically, the electrostatic force adjusting device 9 develops the largest electrostatic force in the divided region X1 where the deflection of the workpiece W is the largest, and the electrostatic force decreases in the order of the divided regions X2, X3, and X4. A voltage is applied to the electrode 3 provided in each region. Thereby, suitable drawing according to bending of work W is performed. Further, the electrostatic force adjusting device 9 independently adjusts the electrostatic force in a plurality of regions (X1, X2, X3, X4) so that the difference between the measurement results output from the distance meter 8 is within a predetermined range. To do. Thereby, the workpiece | work W can be hold | maintained with a horizontal attitude | position accurately.

Therefore, according to the above-described embodiment, air is blown out from the nozzle 4 provided on the base surface 2a to float the work W, and a voltage is applied to the electrode 3 provided on the base surface 2a to thereby apply the work W Is a non-contact type electrostatic chuck 1 that draws an electrostatic force toward the base surface 2a, and the nozzle 4 surrounds at least a part of the region where the electrode 3 is provided and faces the inside of the enclosed region X. An opening extending obliquely with respect to the base surface 2a is divided into a plurality of regions (X1, X2, X3, X4) according to the distance from the center of the region X. By adopting a configuration in which the electrostatic force adjusting device 9 for independently adjusting the electrostatic force is provided for each of the regions, the region is surrounded by the nozzle 4 that extends obliquely with respect to the base surface 2a. Forming an air reservoir G in frequency X, in the region surrounded by X, (while inflated) while bending large workpiece W can be floated. And this embodiment divides | segments into several area | region (X1, X2, X3, X4) according to the distance from the center of this enclosed area | region X, and adjusts the electrostatic force in these several area | regions independently. Thus, appropriate pulling according to the deflection of the workpiece W can be performed, the deflection of the workpiece W can be minimized, and the posture can be stabilized.
Therefore, in this embodiment, even a thin workpiece W that is soft and has low rigidity can be held without contact without causing local deformation.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. In the following description, the same or equivalent components as those of the above-described embodiment are denoted by the same reference numerals, and the description thereof is simplified or omitted.
FIG. 3 is a cross-sectional view showing the configuration of the non-contact electrostatic chuck 1 in the second embodiment of the present invention.
As shown in the drawing, the non-contact type electrostatic chuck 1 of the second embodiment is provided in the divided region X1, and based on the measurement result of the distance meter 8, air is sucked between the workpiece W and the base surface 2a. A second nozzle 10 for injecting air is provided.

  The second nozzle 10 extends perpendicularly to the base surface 2a and opens in the divided region X1. The second nozzle 10 is provided at a position corresponding to the center of the region X. The second nozzle flow path 10 a is formed by a tube member 12 provided through the base portion 2 and the chamber 7. The pipe member 12 is connected to the pressure adjusting device 13. The pressure adjusting device 13 of this embodiment includes a chamber (not shown) that communicates with the second nozzle flow path 10a, and is configured to variably control the pressure in the chamber. The pressure adjusting device 13 is electrically connected to the distance meter 8 and is configured to control the pressure in the chamber based on the measurement result and perform suction or injection from the second nozzle 10.

Subsequently, a specific operation of the non-contact electrostatic chuck 1 having the above-described configuration will be described.
Although it is preferable that the workpiece W always maintain a constant distance with respect to the base surface 2a, in reality, a slight fluctuation (vibration) occurs. This is because the workpiece W is thin and the amount of air from the nozzle 4 is affected by mechanical vibration of an air supply source (fan, blower, etc.). Therefore, in the second embodiment, based on the distance between the workpiece W and the base surface 2a, the air is sucked or jetted from the second nozzle 10 between the workpiece W and the base surface. Optimize the amount of air to float.

  Specifically, the inside of the chamber (not shown) and the inside of the second nozzle channel 10a are kept at a predetermined pressure by the pressure adjusting device 13. This predetermined pressure is set to be an ideal pressure of the air reservoir G when the workpiece W is levitated at a predetermined distance from the base surface 2a. According to this configuration, when the amount of air from the nozzle 4 decreases and the pressure of the air reservoir G decreases below the set pressure due to the fluctuation, air is injected / supplied from the second nozzle 10 due to the pressure difference. . On the other hand, when the amount of air from the nozzle 4 increases due to the above fluctuation and the pressure of the air reservoir G increases above the set pressure, air is sucked into the second nozzle 10 due to the pressure difference. Thus, in 2nd Embodiment, the fluctuation | variation of the workpiece | work W can be reduced by optimizing the air quantity which floats the workpiece | work W with the 2nd nozzle 10. FIG. Therefore, it is possible to hold the workpiece W with high accuracy.

  As mentioned above, although preferred embodiment of this invention was described referring drawings, this invention is not limited to the said embodiment. Various shapes, combinations, and the like of the constituent members shown in the above-described embodiments are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

  For example, in the above embodiment, the configuration in which the electrostatic force is adjusted by dividing the region X into four regions (X1, X2, X3, and X4) according to the distance from the center has been described. However, the number of areas to be divided may be two or more.

  For example, in the above embodiment, the distance meter 8 is provided in each of the plurality of regions (X1, X2, X3, X4), but the present invention is not limited to this configuration, and the plurality of regions The structure provided in at least one may be sufficient.

  Further, for example, in the above embodiment, the nozzle 4 has been described as being configured to surround the region X in a rectangular shape in plan view, but the present invention is not limited to this configuration, and for example, a circle or other polygons It may be configured to enclose.

  For example, in the above-described embodiment, the configuration in which the second nozzle 10 is provided in the divided region X1 has been described, but the present invention is not limited to this configuration, and a plurality of regions (X1, X2, X3, A configuration may be provided in at least one of X4).

  DESCRIPTION OF SYMBOLS 1 ... Non-contact type electrostatic chuck, 2a ... Base surface, 3 ... Electrode, 4 ... Nozzle, 8 ... Distance meter, 9 ... Electrostatic force adjusting device, 10 ... Second nozzle, W ... Workpiece, X ... Area (enclosed) Area), X1, X2, X3, X4... Divided area (multiple areas)

Claims (5)

A non-contact electrostatic chuck that blows air from a nozzle provided on a base surface to float the work and applies a voltage to an electrode provided on the base surface to attract the work to the base surface by electrostatic force Because
The nozzle surrounds at least a part of a region where the electrode is provided, and opens obliquely with respect to the base surface toward the inside of the surrounded region,
The enclosed area is divided into a plurality of areas according to a distance from the center of the area, and has an electrostatic force adjusting device that independently adjusts the electrostatic force for each of the plurality of areas. Non-contact electrostatic chuck.   2. The non-contact type according to claim 1, wherein the electrostatic force adjusting device independently adjusts the electrostatic forces in the plurality of regions so that the electrostatic force increases toward the center. Electrostatic chuck. A distance meter that is provided in at least one of the plurality of regions and measures a distance between the workpiece and the base surface;
The non-contact electrostatic chuck according to claim 1, wherein the electrostatic force adjusting device independently adjusts the electrostatic force in the plurality of regions based on a measurement result of the distance meter. .   The non-contact electrostatic chuck according to any one of claims 1 to 3, wherein an extending direction of the electrodes in an adjacent region among the plurality of regions is a direction crossing each other. A distance meter that is provided in at least one of the plurality of regions and measures a distance between the workpiece and the base surface;
A second nozzle that is provided in at least one of the plurality of regions and performs air suction or air injection between the workpiece and the base surface based on a measurement result of the distance meter. The non-contact electrostatic chuck according to any one of claims 1 to 4, wherein

Images