JP2021086964A - Electrostatic chuck - Google Patents

Abstract

To provide an electrostatic chuck with which the local distortion of a substrate during a time when the substrate is sucked can be suppressed so that the substrate surface can be straightened.SOLUTION: Each first sub-electrode 22 of a first electrode is connected to a first main electrode 21 at a base end portion and extends linearly. Each second sub-electrode 32 of a second electrode is connected to a second main electrode 31 at a base end portion and extends linearly. Each first sub-electrode 22 and each sub-electrode 32 each have a width of 0.3-2.0 mm. Each first sub-electrode 22 faces the second sub-electrode 32 adjacent thereto in the state where both are 0.3-2.5 mm apart in a width direction from each other. The tip of each first sub-electrode 22 faces the second main electrode 31 in the state where both are 0.3-2.5 mm apart from each other. The tip of each second sub-electrode 32 faces the first main electrode 21 in the state where both are 0.3-2.5 mm apart from each other. When W1 and L1 represent the width and the length of the first sub-electrode 22, respectively, and W2 and L2 represent the width and the length of the second sub-electrode 32, respectively, 5 mm2≤W1×L1≤50 mm2 and 5 mm2≤W2×L2≤50 mm2 are satisfied.SELECTED DRAWING: Figure 2

Description

The present invention relates to an electrostatic chuck used for electrostatically adsorbing an insulating substrate in a semiconductor manufacturing process or the like.

Conventionally, an electrostatic chuck for sucking an insulating substrate has been disclosed in which a pair of electrodes are arranged in a straight line or a circumferential shape so as to face each other on the opposite surface of the suction surface, and are provided alternately intertwined. For example, see Patent Document 1).

Japanese Patent No. 3805134

It is said that it is effective to exert Coulomb force and gradient force to electrostatically adsorb an insulating substrate such as a glass substrate. At that time, the Coulomb force is attracted by the electrostatic force between the electrodes and the substrate in anticipation of the slight conductivity of the insulating substrate, and the gradient force is in the electric field formed by the pair of electrodes. It is said that the insulating substrate is polarized and a force acts in the direction of inclination of the electric field strength. That is, adsorption by Coulomb force cannot be expected on a substrate with high insulating properties.

In the electrode pattern of the electrostatic chuck for adsorbing an insulating substrate described in Patent Document 1, the electrodes are arranged so as to effectively exert the gradient force, and the gradient force is mainly located at a separation position between the pair of electrodes. appear. For example, in the electrode pattern shown in FIG. 4 of Patent Document 1, a periodic force of 1 is applied to the x-axis along the direction in which the linear patterns of the pair of electrodes face each other on the xy plane. A uniform force is exerted on the y-axis along the extending direction of the linear pattern of the pair of electrodes.

When the insulating substrate is adsorbed and fixed, it is desirable to uniformly flatten the entire substrate on the adsorption surface and adsorb and fix the substrate without distorting the substrate. When there is a force acting only on a portion in a specific plane on the surface, there is a problem that the substrate may be locally slightly distorted and adsorbed when the substrate is adsorbed. In particular, such distortion is recognized when the pair of electrode patterns are uniformly opposed to each other and the pair of electrode patterns facing each other are long in a specific direction, as in the electrode pattern of the electrostatic chuck of Patent Document 1. There was a case.

The present invention has been made by paying attention to such a problem, and an object of the present invention is to provide an electrostatic chuck capable of suppressing local distortion of a substrate during substrate adsorption and correcting a flat surface.

In order to achieve the above object, the electrostatic chuck according to the present invention has an insulating substrate and a pair of first and second electrodes, and the insulating substrate has a plate-like and insulating substrate. It has a mounting surface for mounting and a back surface opposite to the previously described mounting surface, and the inside of the insulating substrate or the inside of the insulating substrate so that the first electrode and the second electrode electrostatically attract the substrate to the previously described mounting surface. An electrostatic chuck provided on the back surface, wherein the first electrode has a first main electrode and a plurality of first sub-electrodes, and the first main electrode extends in a first direction. Each first sub-electrode has a base end portion and a tip end portion, and is connected to the first main electrode at the base end portion of the first sub-electrode to be linearly formed in a second direction different from the first direction. Extending, the second electrode has a second main electrode and a plurality of second sub-electrodes, the second main electrode extends in a third direction, and each second sub-electrode has a proximal end and a plurality of sub-electrodes. It has a tip and is connected to the second main electrode at the base end of the second sub-electrode, extending linearly in the fourth direction different from the third direction, and each of the first sub-electrode and Each second sub-electrode has a width of 0.3 to 2.0 mm, and each first sub-electrode faces the adjacent second sub-electrode at a distance of 0.3 to 2.5 mm in the width direction. The tip of each first sub-electrode faces the second main electrode at a distance of 0.3 to 2.5 mm, and the tip of each second sub-electrode is 0.3 to 2. When facing each other with a distance of 5 mm, the width of the first sub-electrode is W1, the length is L1, the width of the second sub-electrode is W2, and the length is L2, 5 mm ² ≤ W1 x L1 ≤ 50 mm. It is characterized in that ² and 5 mm ² ≦ W2 × L2 ≦ 50 mm ^{2 are satisfied.}

The electrostatic chuck according to the present invention functions by applying a voltage from an external power source to the first electrode and the second electrode. Each first sub-electrode faces the second sub-electrode in a state of being separated from each other in the width direction, and a potential difference is generated between the two. By setting the electrode width and the separation distance within the above-mentioned predetermined ranges, the gradient force can be effectively exerted on the substrate mounted on the mounting surface, and electrostatic adsorption can be performed. At this time, the gradient force is mainly expressed in the separated region in the electrode width direction.

Since the tip of the first sub-electrode faces the second main electrode at the predetermined distance, a potential difference is generated between the tip of the first sub-electrode and the second main electrode. Further, since the tip of the second sub-electrode faces the first main electrode at the predetermined distance, a potential difference is also generated between the tip of the second sub-electrode and the first main electrode. As a result, a gradient force is also exhibited in the region at the tip of the first sub-electrode and the second sub-electrode.

By setting the product of the width and the length of the first sub-electrode and the product of the width and the length of the second sub-electrode within the above-mentioned predetermined ranges, the region of the tip of the first sub-electrode and the second sub-electrode becomes an electrode. Since it increases in the plane on which the electrodes are arranged, the gradient force is effectively exerted not only in the region separated in the width direction of the auxiliary electrode but also in the tip region, and the gradient force is applied more evenly on the entire surface of the substrate. be able to.
As a result, it is possible to prevent the substrate from being locally distorted when the substrate is adsorbed, and to electrostatically adsorb the substrate in a state where the substrate is flattened by an even force.

In the electrostatic chuck according to the present invention, it is preferable that the first electrode has a plurality of the first main electrodes and the second electrode has a plurality of the second main electrodes.
In this case, since it becomes easy to balance the region separated in the width direction of the auxiliary electrode and the region at the tip portion, local distortion of the substrate during substrate adsorption is less likely to occur, and the substrate is more flattened. It can be electrostatically adsorbed.

In the electrostatic chuck according to the present invention, the first direction and the third direction are radial directions of the same circle, and the second direction and the fourth direction are along the circumference of the same circle. It is preferable that the first main electrode and the second main electrode are alternately arranged in the circumferential direction.
In this case, since it is easy to balance the region separated in the width direction of the auxiliary electrode and the region of the tip portion on the circular mounting surface, local distortion of the substrate during substrate adsorption is caused by the circular mounting surface. It is less likely to occur, and the substrate can be electrostatically adsorbed in a more flattened state.

According to the present invention, it is possible to provide an electrostatic chuck capable of flattening by suppressing local distortion of the substrate when the substrate is adsorbed.

It is (A) plan view and (B) vertical sectional view which shows the schematic structure of the electrostatic chuck of embodiment of this invention. It is a top view which shows a part of the electrode pattern of the electrostatic chuck shown in FIG. It is explanatory drawing which shows (A) suitable example, (B) unsuitable example 1, (C) unsuitable example 2 of the electrode pattern shown in FIG. It is a top view which shows the other electrode pattern of the electrostatic chuck shown in FIG. It is a top view which shows a part of the electrode pattern of the conventional example of an electrostatic chuck.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the electrostatic chuck according to the embodiment of the present invention has an insulating substrate 1 and a pair of a first electrode 2 and a second electrode 3. The insulating substrate 1 is formed by providing an insulating layer 12 on a disk-shaped substrate 11. The insulating substrate 1 has a mounting surface 1a for mounting an insulating substrate and a back surface 1b on the opposite side of the mounting surface 1a. The first electrode 2 and the second electrode 3 are connected to a DC power supply or an AC power supply by a terminal 4. The first electrode 2 and the second electrode 3 are provided inside the insulating substrate 1 or on the back surface 1b so as to electrostatically attract the substrate to the mounting surface 1a.

The first electrode 2 has a plurality of first main electrodes 21 and a plurality of first sub-electrodes 22. The first main electrode 21 extends linearly in the radial direction (first direction) from the center of the concentric circles along the outer circumference of the disk-shaped insulating substrate 1. Each first sub-electrode 22 has a base end portion 22a and a tip end portion 22b, and is connected to both sides of the first main electrode 21 in the width direction by the base end portions 22a of the first sub-electrode 22 to be connected to the first direction. Extends linearly in a different second direction. The second direction is a circumferential direction along the circumference of the same circle, which is a concentric circle along the outer circumference of the disk-shaped insulating substrate 1.

The second electrode 3 has a plurality of second main electrodes 31 and a plurality of second sub-electrodes 32. Like the first main electrode 21, the second main electrode 31 extends linearly in the radial direction (third direction) from the center of the concentric circles along the outer circumference of the disk-shaped insulating substrate 1. The first main electrode 21 and the second main electrode 31 are alternately arranged at equal intervals in the circumferential direction of the same circle.

Each second sub-electrode 32 has a base end portion 32a and a tip end portion 32b. Each of the second sub-electrodes 32 is connected to both sides of the second main electrode 31 in the width direction by the proximal end portion 32a of the second sub-electrode 32 and extends linearly in a fourth direction different from the third direction. doing. The fourth direction is a circumferential direction along the circumference of the same circle, which is a concentric circle along the outer circumference of the disk-shaped insulating substrate 1. The first sub-electrode 22 and the second sub-electrode 32 are alternately arranged at equal intervals in the radial direction of the same circle.

Each of the first sub-electrode 22 and each second sub-electrode 32 has a width of 0.3 to 2.0 mm. Each of the first sub-electrodes 22 faces the adjacent second sub-electrodes 32 in a state of being separated from each other by 0.3 to 2.5 mm in the width direction. Each of the first sub-electrodes 22 faces the second main electrode 31 with the tip end portion 22b separated from the second main electrode 31 by 0.3 to 2.5 mm. Each of the second sub-electrodes 32 faces the first main electrode 21 with the tip end portion 32b separated from the first main electrode 21 by 0.3 to 2.5 mm. When the width of the first sub-electrode 22 is W1, the length is L1, the width of the second sub-electrode 32 is W2, and the length is L2, 5 mm ² ≦ W1 × L1 ≦ 50 mm ² and 5 mm ² ≦ W2 × L2 ≤50 mm ² is satisfied.

Next, the action will be described.
The electrostatic chuck functions by applying a voltage from an external power source to the first electrode 2 and the second electrode 3. Each of the first sub-electrodes 22 faces each of the second sub-electrodes 32 in a state of being separated from each other in the width direction, and a potential difference is generated between the two. By setting the electrode width and the separation distance within the above-mentioned predetermined ranges, a gradient force can be effectively exerted on the substrate mounted on the mounting surface 1a, and electrostatic adsorption can be performed. At this time, the gradient force is expressed in the separation region between the first sub-electrode 22 and the second sub-electrode 32.

Since the tip 22b of the first sub-electrode 22 faces the second main electrode 31 at the predetermined distance, there is a potential difference between the tip 22b of the first sub-electrode 22 and the second main electrode 31. .. Further, since the tip portion 32b of the second sub-electrode 32 faces the first main electrode 21 at the above-mentioned predetermined distance, the tip portion 32b of the second sub-electrode 32 and the first main electrode 21 are also formed. A potential difference occurs. As a result, a gradient force is also exhibited in the separation region between the tip portions 22b and 32b of the first sub-electrode 22 and the second sub-electrode 32 and the first main electrode 21 and the second main electrode 31.

5 mm ² ≤ W1 x L1 ≤ 50 mm ² and 5 mm ² ≤ W2 x L2 ≤ 50 mm In ^{the formula 2} , when the length L1 of the first sub-electrode 22 or the length L2 of the second sub-electrode 32 becomes smaller, the first sub-electrode The number of regions of the tip portions 22b and 32b of the 22 and the second sub-electrode 32 increases in the entire insulating substrate 1. As a result, a large amount of gradient force is generated in the separated region between the tip portions 22b and 32b of the auxiliary electrodes 22 and 32 and the first main electrode 21 or the second main electrode 31 facing each other on the extension line thereof, and electrostatic adsorption is performed. The power becomes stronger.

However, when the product of the length L1 and the width W1 of the first sub-electrode 22 or the product of the length L2 and the width W2 of the second sub-electrode 32 (that is, corresponding to the electrode area) ^{becomes larger than 50 mm 2} , it becomes larger. While the effect of the Coulomb force is large, the gradient force is relatively small, which is not preferable for adsorption of an insulating substrate.
Further, if the width W1 of the first sub-electrode 22 or the width W2 of the second sub-electrode 32 is too large, the number of separation regions between the first sub-electrode 22 and the second sub-electrode 32 that face each other adjacent to each other becomes large. The total amount of the insulating substrate 1 is reduced. As a result, the gradient force itself does not work sufficiently, and the substrate cannot be sufficiently electrostatically adsorbed.

FIG. 3A shows a preferred example of the electrostatic chuck according to the embodiment of the present invention. In FIGS. 3A to 3C, the broken line region 5 shows the separated region in the width direction of the first sub-electrode 22 and the second sub-electrode 32, and the broken line region 6 is the first sub-electrode 22 and the second sub-electrode 32. The separated regions of the tip portions 22b and 32b of the above are shown. As shown in FIG. 3A, by setting the product of the width and the length of the first sub-electrode 22 and the product of the width and the length of the second sub-electrode 32 within the above-mentioned predetermined ranges, the first sub-electrode Since the regions of the tip portions 22b and 32b of the 22 and the second sub-electrode 32 increase in the plane on which the electrodes are arranged, not only the regions separated in the width direction of the sub-electrodes 22 and 32 but also the regions of the tip portions 22b and 32b The gradient force can be effectively exerted, and the gradient force can be applied more evenly on the entire surface of the substrate.
As a result, it is possible to prevent the substrate from being locally distorted when the substrate is adsorbed, and to electrostatically adsorb the substrate in a state where the substrate is flattened by an even force.

On the other hand, in the unsuitable example 1 shown in FIG. 3B, the first sub-electrode 22 and the second sub-electrode 32 are separated from each other in the width direction (broken line region 5), and the first sub-electrode 22 and the second sub-electrode 32 are 32. Since the separation region (broken line region 6) between the tip end portion and the first main electrode 21 and the second main electrode 31 is unbalanced, local distortion is likely to occur. Further, in the unsuitable example 2 shown in FIG. 3C, since the width of the first sub-electrode 22 and the second sub-electrode 32 is too wide, the number of regions where the gradient force acts is reduced, and the electrostatic adsorption force is reduced. Is weak.

In the electrostatic chuck according to the embodiment of the present invention, in particular, since the first electrode 2 has a plurality of first main electrodes 21 and the second electrode 3 has a plurality of second main electrodes 31, adjacent first sub electrodes Since it becomes easy to balance the separation region between the 22 and the second sub-electrode 32 and the region between the tip portions 22b and 32b and the first main electrode 21 and the second main electrode 31, the substrate at the time of substrate adsorption Local distortion is less likely to occur, and the substrate can be electrostatically attracted in a more flattened state.

Further, the extending directions (first direction, third direction) of the first main electrode 21 and the second main electrode 31 are radial directions of the same circle, and the first sub-electrode 22 and the second sub-electrode 32 The extending directions (second direction, fourth direction) are circumferential directions along the circumference of the same circle, and the first main electrode 21 and the second main electrode 31 are alternately arranged in the circumferential direction. Therefore, it is easy to balance the separation region between the sub-electrodes 22 and 32 and the separation region between the tip portions 22b and 32b and the main electrodes 21 and 31 on the circular mounting surface 1a. Therefore, local distortion of the substrate at the time of substrate adsorption on the circular mounting surface 1a is less likely to occur, and the substrate can be electrostatically adsorbed in a more flattened state.

As shown in FIG. 4, the connecting line 23 connecting the plurality of first main electrodes 21 and / or the connecting line 33 connecting the plurality of second main electrodes 31 may be provided.
Further, the electrode pattern is not limited to the pattern shown in FIGS. 2 and 4, and may be another pattern.
The first sub-electrode 22 and / or the second sub-electrode 32 may have a linear shape, a bent shape, or a further branched shape as well as an arc shape.
The first main electrode 21, the second main electrode 31, the first sub-electrode 22, and the second sub-electrode 32 may be arranged substantially evenly in the region substantially the same as the region of the mounting surface 1a regardless of the shape. preferable.

(Manufacturing method by green sheet molding method)
For example, an electrostatic chuck was manufactured by the ceramic green sheet molding method shown in Japanese Patent Application Laid-Open No. 2008-147549.
The ceramic green sheet _{preferably contains Al 2} O ₃ and Al N as main components. In this example, Al ₂ O ₃ having a purity of 99.5% was used as a raw material powder. Al ₂ O ₃ , a binder, a plasticizer, a dispersant, and a solvent were slurried and a green sheet was formed by a doctor blade. The thickness of the green sheet to be molded is preferably 0.5 to 2 mm. In this example, the thickness was 0.65 mm.

W (tungsten) paste was printed on a ceramic green sheet using a screen mask to form a pair of layered electrodes. The design of the screen mask was appropriately adjusted so that the pattern to be printed was the pattern shown in FIG.
Further, for comparison, as shown in FIG. 5, a product printed with the electrode pattern of the conventional example was produced. The electrode pattern of the conventional example has a first main electrode 41 and a second main electrode 51 extending from the center side of the circle to opposite sides in the radial direction, and is an arc obtained by cutting out a part of a plurality of concentric circles having a common center. It is a pattern of the shape in which the first sub-electrode 42 and the second sub-electrode 52 of the shape are alternately connected to the first main electrode 41 and the second main electrode 51.

A laminate in which the produced ceramic green sheet is laminated with another ceramic green sheet (including a via hole filled with W paste serving as a via conductor) so that a pair of electrodes is sandwiched between the two ceramic green sheets. Formed. If necessary, a blind hole was machined on the back surface of the laminate to insert a terminal conducting with the electrode via a via conductor, and W paste was applied to the surface defining the hole. Then, it was calcined at 1600 ° C. for 3 hours in a reducing atmosphere to obtain a ceramic sintered body. After that, the outer shape was machined.
With the terminal (manufactured by Kovar) inserted into the blind hole on the back surface of the ceramic sintered body, the electrode and the terminal were joined by silver brazing to complete the electrostatic chuck. At this time, the diameter of the center line of the outermost periphery of the electrode pattern of the electrostatic chuck was set to 300 mm, the thickness of the insulating layer was set to 0.1 mm, and the surface roughness Ra of the mounting surface was set to 0.1 μm.

In the electrode pattern of the conventional example, the sub-electrode 42 is branched from the main electrode 41 extending in the 12 o'clock direction. Further, the sub-electrode 52 is branched from the main electrode 51 extending in the 6 o'clock direction on the opposite side of the main electrode 41. The length of the auxiliary electrodes 42 and 52 is approximately 1/2 of the circumference. The gradient force is mainly expressed in the separation region between the electrodes. Therefore, the gradient force is periodically unevenly distributed in the radial direction.

In this embodiment, twelve first main electrodes 21 and twelve second main electrodes 31 extending in the radial direction from the center of the circle are alternately arranged in the circumferential direction. The first sub-electrode 22 and the second sub-electrode 32 extend from the first main electrode 21 and the second main electrode 31 to both sides along the circumferences of a plurality of concentric circles having a common center, respectively, and alternate in the radial direction of the same circle. Are evenly spaced. The pattern of the first sub-electrode 22 and the second sub-electrode 32 is an arc shape as if a plurality of concentric circles were each divided into 24. The sub-electrodes 22 and 32 are branched in the circumferential direction from the main electrodes 21 and 31 extending in the radial direction. The length of the auxiliary electrodes 22 and 32 is approximately the arc length obtained by dividing the circumference into 24 parts. The gradient force is mainly expressed in the separation region between the electrodes.

In the electrode pattern of the present embodiment shown in FIG. 2, as compared with the conventional electrode pattern shown in FIG. 5, one of the tip portions 22b, 32b from the branched positions (base end portions 22a, 32a) of the sub-electrodes 22 and 32 The length L up to is short, and the number of locations of the tip portions 22b, 32b of one of the auxiliary electrodes 22 and 32 is increasing. One of the tip portions 22b and 32b of the sub-electrodes 22 and 32 is surrounded by the opposing electrodes, and the electric field of the tip portions 22b and 32b of the sub-electrodes 22 and 32 mainly exists on the extension line of the sub-electrode tip portion. It is formed between the counter electrode (second main electrode 31 and first main electrode 21), and a gradient force is exhibited.

5 mm ² ≤ W1 x L1 ≤ 50 mm ² and 5 mm ² ≤ W2 x L2 ≤ 50 mm ^{By satisfying the equation 2} , it exists on the extension lines of the tip portions 22b and 32b of the sub-electrodes 22 and 32 and the tip end portion of the sub-electrode. Since the number of separation points from the counter electrode (second main electrode 31, first main electrode 21) can be increased, the places where the gradient force is exhibited can be made more uniform than before, and as a result, the insulating substrate can be made more uniform. It becomes possible to adsorb without distortion.

(Evaluation)
For the manufactured electrostatic chuck of this example and the electrostatic chuck of the conventional example, a DC voltage of ± 3 kV is applied to a pair of terminals, and a non-alkali glass substrate (diameter 300 mm, thickness 0.7 mm) is electrostatically adsorbed. The result was observed.
Hereinafter, Examples 1 to 10 and Comparative Examples 1 to 7 are the results of evaluation by changing the sub-electrode length L and the sub-electrode width W. The length of the auxiliary electrode in the table below is the longest in the pattern.

表１のとおり、副電極長さＬと副電極幅Ｗの積が５０ｍｍ^２以下であると、静電吸着された基板の平面度が３μｍ未満となり、基板の局所的な平面度が改善されていることが示された。
なお、比較例４は吸着力が小さく、比較例５は電極間の絶縁不良が生じたため平面度の矯正を行うことができず、平面度の測定を行うことができなかった。

As shown in Table 1, when the product of the sub-electrode length L and the sub-electrode width W is 50 mm ² or less, the flatness of the electrostatically adsorbed substrate is less than 3 μm, and the local flatness of the substrate is improved. It was shown to be.
In Comparative Example 4, the adsorption force was small, and in Comparative Example 5, the flatness could not be corrected due to the poor insulation between the electrodes, and the flatness could not be measured.

1 Insulation base 2 1st electrode 3 2nd electrode 11 Base 12 Insulation layer 1a Mounting surface 1b Back side 4 terminals 21 1st main electrode 22 1st sub-electrode 22a Base end 22b Tip 31 2nd main electrode 32 2nd sub Electrode 32a Base end 32b Tip

Claims (3)

It has an insulating substrate and a pair of first and second electrodes, and the insulating substrate has a plate-like shape and a mounting surface for mounting an insulating substrate and a back surface opposite to the above-mentioned mounting surface. The electrostatic chuck is provided inside or on the back surface of the insulating substrate so that the first electrode and the second electrode electrostatically attract the substrate to the above-mentioned mounting surface.
The first electrode has a first main electrode and a plurality of first sub-electrodes, the first main electrode extends in a first direction, and each first sub-electrode has a base end portion and a tip end portion. Then, it is connected to the first main electrode at the base end portion of the first sub-electrode and extends linearly in a second direction different from the first direction.
The second electrode has a second main electrode and a plurality of second sub-electrodes, the second main electrode extends in a third direction, and each second sub-electrode has a base end portion and a tip end portion. Then, it is connected to the second main electrode at the base end portion of the second sub-electrode and extends linearly in the fourth direction different from the third direction.
Each first sub-electrode and each second sub-electrode has a width of 0.3-2.0 mm.
Each first sub-electrode faces the adjacent second sub-electrode at a distance of 0.3 to 2.5 mm in the width direction, and the tip of each first sub-electrode is 0.3 to 0.3 to the second main electrode. Facing with a distance of 2.5 mm,
The tip of each second sub-electrode faces the first main electrode at a distance of 0.3 to 2.5 mm.
When the width of the first sub-electrode is W1, the length is L1, the width of the second sub-electrode is W2, and the length is L2, 5 mm ² ≦ W1 × L1 ≦ 50 mm ² and 5 mm ² ≦ W2 × L2. Satisfying ≤50 mm ²
Characterized electrostatic chuck. The electrostatic chuck according to claim 1, wherein the first electrode has a plurality of the first main electrodes, and the second electrode has a plurality of the second main electrodes. The first direction and the third direction are radial directions of the same circle, and the second direction and the fourth direction are circumferential directions along the circumference of the same circle, and the first direction. The electrostatic chuck according to claim 2, wherein the main electrode and the second main electrode are alternately arranged in the circumferential direction.

Images