JPH0923670A - Electrostatic chuck - Google Patents

Abstract

PROBLEM TO BE SOLVED: To release an attraction object easily and quickly by rapidly lowering the remaining attraction force of an electrostatic chuck, with the attraction object being mounted on an attraction face of the electrostatic chuck. SOLUTION: In a dielectric 1, cavities for electrode 2.2, a liquid lead-in channel 7a and a liquid exhaust channel 7b for leading in and out a liquid which has an electric conductivity into or out of the cavities for electrode 2.2 are formed. In part of the cavities for electrode 2.2, electrodes for fixing a potential 3.3 to which DC voltage is to be applied from an electrostatic chuck power supply 6 are formed. For attracting an attraction object, the cavities for electrode 2.2 are filled with the liquid which has an electric conductivity. For releasing the attraction object, the liquid which has an electric conductivity is taken out of the cavities for electrode 2.2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic chuck for attracting and fixing an object to be attracted by electrostatic force.

[0002]

2. Description of the Related Art In recent years, electrostatic chucks for attracting and fixing objects to be attracted including semiconductors by electrostatic force have come to be used in various fields.
BACKGROUND ART An electrostatic chuck is effectively used as a fixing means for fixing an object to be processed such as a silicon wafer, correcting a warp, cooling an entire surface, heating an entire surface, and a conveyance means in various semiconductor manufacturing apparatuses such as an ion doping apparatus and an etching apparatus.

The electrostatic chuck uses an electrostatic force generated between the electrostatic chuck and an object to be attracted placed on the surface thereof, and there are a bipolar type and a unipolar type.

The bipolar electrostatic chuck is shown in FIGS. 2 and 3.
As shown in, basically, two internal electrodes 52, 52 made of metal are embedded in a dielectric 51, and a feedthrough (introduction terminal) is provided between the internal electrodes 52, 52.
The electrostatic chuck power supply 55 for applying a DC voltage is connected via 53, 53 and voltage application cables 54, 54.

As shown in FIG. 4, the unipolar type electrostatic chuck is basically such that an internal electrode 62 made of a single metal is embedded in a dielectric 61, and the internal electrode 62 and an object to be attracted are attracted. An electrostatic chuck power supply 63 for applying a DC voltage is connected to the object 50.

In either case of the unipolar type or the bipolar type, a structure in which the metal electrode is not embedded in the dielectric but a dielectric is formed on the surface of the metal electrode may be used.

In the electrostatic chuck having the above structure, the electrode 52
A dielectric polarization phenomenon occurs in the dielectric body 51 (61) enclosing (62), and an electrostatic force is generated between the dielectric body 51 (61) and the adsorption target object 50. Is adsorbed on. The electrostatic force acting on the attraction target 50 in contact with the attraction surface of the dielectric 51 (61), that is, the attraction force F (N) of the electrostatic chuck varies depending on various conditions, but generally, It is represented by equation (1).

F = ASε (V / d) ² (1) where ε = ε ₀ · ε _r A: proportional constant S: electrode area of electrostatic chuck (m ² ) V: to electrostatic chuck applied voltage (V) d: distance surface dielectric thickness of the electrostatic chuck, i.e. from the electrode to the suction surface (m) ε _0: dielectric constant of vacuum ^{(8.85 × 10 -12 C 2 N} -1 m - ² ) ε _r : Relative permittivity of dielectric material The attraction force of an electrostatic chuck depends on the amount of polarization charge that appears due to the dielectric polarization phenomenon, and this amount of polarization charge greatly depends on the dielectric constant of a substance.

By the way, in a semiconductor manufacturing apparatus or the like, the attachment / detachment of the wafer to / from the electrostatic chuck is automatically performed by using a wafer transfer mechanism. In this case, as shown in FIG. 5, the electrostatic chuck 70 has a wafer receiving member 72 that supports the edge portion of the wafer 71 and moves up and down, and a drive mechanism 73 that drives the wafer receiving member 72 up and down. And a wafer lifting mechanism including

When the wafer 71 is sucked and held by the electrostatic chuck 70, the wafer is transferred by the wafer transfer mechanism to the end of the wafer receiving member 72 which is displaced above the suction surface 70a of the electrostatic chuck 70. After placing 71, the wafer receiving member 72 is moved below the suction surface 70a, and the wafer 71 is accurately placed at a predetermined position on the suction surface 70a. As a result, the wafer 71 is attracted by the electrostatic chuck 70, and thereafter, necessary processing such as ion implantation is performed.

On the other hand, when the wafer 71 which has undergone the necessary processing is removed from the electrostatic chuck 70 and carried out, the voltage applied to the electrostatic chuck 70 is cut off and the wafer receiving member 72 is used.
And the wafer 71 is lifted above the suction surface 70a, and then is unloaded by the wafer transfer mechanism.

[0012]

However, when the wafer receiving member 72 is raised to separate the wafer 71 from the electrostatic chuck 70 as described above, some wafers 71 accumulate charges inside themselves (for example, as shown in FIG. Wafer 7
There is a case in which the back surface of No. 1 is covered with an oxide film.) Even if the voltage applied to the electrostatic chuck 70 is turned off, the wafer 71 may not be easily separated from the electrostatic chuck 70 due to the residual attraction force. . The residual suction force is
Depending on the situation, it will remain for a few seconds to a few minutes.

In this case, if the wafer receiving member 72 is raised against the residual suction force, the edge portion of the wafer 71 is forcibly lifted and the wafer 71 is warped. When the wafer 71 is further lifted with a force stronger than the residual suction force, the wafer 71 is separated from the suction surface 70a.
As shown in the above equation (1), the suction force decreases in inverse proportion to the square of the distance, so that the suction force sharply decreases. For this reason, the wafer 71 that has been warped until then makes a motion that jumps up due to the reaction force, and the position of the wafer 71 is displaced, which may hinder the transfer by the wafer transfer mechanism.
1 may fall from the wafer receiving member 72, and the detachment process of the wafer 71 may not be successful.

In order to avoid the above-mentioned inconvenient situation, it is necessary to wait until the residual suction force becomes small to some extent, but this requires a long time for the detachment process of the wafer 71 and the throughput is remarkably deteriorated. . For example, when looking at the current medium current ion implantation apparatus, the throughput that the maximum throughput exceeds 200 sheets / hour is also general, and the cycle time at this time (required for carrying / implanting one wafer 71) Time) is about 18 seconds. If a waiting time of 5 seconds is further added to the above cycle time in order to prevent the wafer 71 from being displaced or dropped, the cycle time becomes 23 seconds, so that the throughput is 156.5 wafers / second (200 wafers / second). (About 78.3% of the time)
It will be reduced to.

The present invention has been made in view of the above, and an object thereof is to rapidly reduce the residual suction force in a state in which an object to be adsorbed is placed on the surface to be adsorbed, and to remove the object to be adsorbed. An object is to provide an electrostatic chuck that can be easily and quickly performed.

[0016]

An electrostatic chuck according to the present invention is one for adsorbing an object to be adsorbed on the surface of a dielectric by an electrostatic force, and in order to solve the above problems, the following means are provided. It is characterized by being taken.

That is, inside the dielectric, an electrode cavity and a passage for introducing and leading out an electrically conductive liquid (for example, mercury or an electrolyte solution) into the electrode cavity are formed. In addition, a potential fixing electrode to which a DC voltage is applied from a power source is provided in a part of the electrode cavity, and the electrostatic chuck is electrically conductive to the electrode cavity through the passage. Filling means for filling the liquid (for example, a mechanism for sending an electrically conductive liquid to the electrode cavity by a pump) and discharging means for discharging the electrically conductive liquid from the electrode cavity through the passage (for example, gas (A mechanism for blowing out the electrically conductive liquid from the electrode cavity).

With the above arrangement, the electrode cavity formed inside the dielectric is filled with the electrically conductive liquid by a filling means such as a pump, and provided only in a part of the electrode cavity. When a voltage is applied from the power supply to the potential fixing electrode, the electric conductive liquid in the electrode cavity becomes almost the same potential as the potential fixing electrode, and like the conventional metal electrode, the internal electrode of the electrostatic chuck is formed. Will function as. Therefore, in this state, if an attraction target such as a silicon wafer is placed on the surface of the dielectric, the attraction target can be attracted by electrostatic force.

On the other hand, when the object to be adsorbed is separated from the electrostatic chuck, the voltage application to the potential fixing electrode is stopped, and the electroconductive liquid is discharged from the electrode cavity by the discharging means. The cavity for use loses its function as an internal electrode, and even if electric charges are accumulated inside the object to be adsorbed, almost no residual adsorption force remains.

That is, due to the discharge of the above-mentioned electrically conductive liquid, a gas having a low relative permittivity (usually, the relative permittivity of a gas is about 1, which is a fraction of that of the dielectric substance) in the electrode cavity. To less than a few tenths), the adsorption function as an electrostatic chuck (which is greatly affected by the dielectric constant as described above) is extremely reduced.

By the way, a phenomenon in which electric charges are accumulated inside the object to be attracted and the attracting force remains even when the voltage applied to the electrostatic chuck is turned off is a phenomenon between the charged object to be attracted and the internal electrode which is a conductor. Dielectric polarization occurs in the dielectric sandwiched between
This is due to the generation of electrostatic force. This is apparently because a voltage is applied to the attraction target and the attraction force acts on the internal electrodes of the electrostatic chuck (hence, the residual attraction force here is the attraction target). It can be regarded as the adsorption force seen from the side).

From the above, if the electrode cavity loses its function as an internal electrode as described above and becomes an electric insulator having a low relative dielectric constant and the adsorption function is extremely lowered, how much the object to be adsorbed will be. Even if the electric charge is accumulated inside, the residual adsorption force becomes sufficiently small (the adsorption force seen from the side of the object to be adsorbed becomes sufficiently small).

A potential fixing electrode is provided in a part of the electrode cavity, but this potential fixing electrode only fixes the potential of the electrically conductive liquid in the electrode cavity. However, it does not require such a large area and can be made sufficiently smaller than a normal internal electrode. Therefore,
The influence of the potential fixing electrode on the residual adsorption force is sufficiently small and can be almost ignored.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the invention will be described below with reference to FIG.

In this embodiment, a bipolar electrostatic chuck will be described as an example. As shown in FIG. 1, the electrostatic chuck according to the present embodiment includes a cylindrical dielectric body 1 in which electrode cavities 2 are formed. The upper smooth surface of the dielectric 1 serves as an adsorption surface 1a for adsorbing an adsorption object such as a placed wafer. Examples of the material of the dielectric 1 include alumina (Al ₂ O ₃ ), silicon carbide (S
Ceramic materials such as iC), calcium titanate (CaTiO ₃ ) can be used.

The dielectric 1 is supported by a support 4 which covers the portion other than the suction surface 1a. The support base 4 is made of a metal having a high thermal conductivity such as an aluminum alloy.

Also, the electrode cavities 2.2 in the dielectric 1
Has a semicircular shape similar to that of a conventional internal electrode (see FIG. 2), and a part of the lower part (cavity forming wall far from the adsorption surface 1a) in the cavity is sufficiently smaller than the cavity. Potential fixing electrodes 3 and 3 are provided.

A static voltage is applied to the potential fixing electrodes 3 and 3 via the introduction terminals 3a and 3a and the voltage applying cables 5 and 5 extending downward from the electrodes. The electric chuck power source 6 is electrically connected.

Further, the dielectric 1 and the support base 4 are
A liquid introducing passage 7a for introducing an electrically conductive liquid (mercury, electrolyte solution, etc.) from the outside into the electrode cavities 2.2 in the dielectric 1 and an electrically conductive liquid in the electrode cavities 2.2. A liquid discharge passage 7b for discharging to the outside is formed so as to communicate with the electrode cavities 2.2. It should be noted that the introduction port of the liquid introduction passage 7a into the electrode cavity 2 and the discharge port of the liquid discharge passage 7b from the electrode cavity 2 so that the electrically conductive liquid circulates in the electrode cavities 2, 2 without interruption. It is desirable to provide and as far apart as possible.

A pipe 8 having electrical conductivity is connected to the liquid introduction passage 7a and the liquid discharge passage 7b. The pipe 8 forms a circulation path for the electrically conductive liquid. The pipe 8 has a reservoir tank 9 for storing the electrically conductive liquid, a pump 10 for circulating the electrically conductive liquid, and an electrically conductive liquid. Stop valve 11 for stopping the inflow of liquid into the electrode cavities 2.2
Are connected in this order. Further, the reservoir tank 9 is provided with a heat exchanger (not shown).

In the present embodiment, the pipe 8, the reservoir tank 9, the pump 10 and the stop valve 1 described above are used.
1 constitutes the filling means described in the claims.

A purge valve 12 for introducing N ₂ gas as a purge gas is provided near the connection portion of the pipe 8 with the liquid introduction passage 7a. A gas discharge part (not shown) for discharging the N ₂ gas is provided above the reservoir tank 9.

In the present embodiment, the pipe 8, the reservoir tank 9, the stop valve 11, the purge valve 12, and the purge gas supply source (not shown) constitute the discharge means described in the claims. .

The operation of the electrostatic chuck having the above structure will be described below.

When an object (not shown) such as a wafer is adsorbed on the adsorption surface 1a of the electrostatic chuck, the pump 10 is driven with the purge valve 12 closed and the stop valve 11 open. Each electrode cavity 2 is filled with the electrically conductive liquid in the tank 9. At the same time, from the electrostatic chuck power source 6, the potential fixing electrode 3 in the electrode cavity 2
A voltage is applied to 3. As a result, the portion of the electrode cavity 2, 2 filled with the electrically conductive liquid becomes the potential fixing electrode 3.
The potential is substantially the same as that of 3, and it functions as an internal electrode of the electrostatic chuck. Therefore, if an attraction target such as a wafer is placed on the attraction surface 1a of the electrostatic chuck in this state, an electrostatic force is generated between the dielectric 1 and the attraction target due to the dielectric polarization phenomenon in the dielectric 1. The object to be adsorbed is adsorbed.

As a method of placing the object to be attracted on the attracting surface 1a of the electrostatic chuck, automatic transfer using a wafer transfer mechanism or a wafer lifting mechanism as shown in the section of the prior art is possible. .

By the way, when the above electrostatic chuck is applied to, for example, a wafer holding member (platen) of an ion implantation apparatus, a process of irradiating the wafer attracted by the electrostatic chuck with an ion beam is performed. During this process, the beam irradiation raises the temperature of the wafer, which needs to be cooled. In such a case, the pump 1 for circulation is always used.
Move 0 to circulate the electrically conductive liquid and remove heat through the heat exchanger. The cooling capacity in this case is higher than the cooling capacity of a cooling mechanism (a structure in which a refrigerant passage is formed in the wafer holding member to circulate a refrigerant such as water) provided in the conventional wafer holding member. In the case of the electrostatic chuck of the present embodiment, this is because the electrode cavities 2 and 2 formed at a position very close to the adsorption surface 1a have a function as a passage for the cooling liquid, and thus are adsorbed to the adsorption surface 1a. This is because the heat of the wafer is efficiently transferred to the electrically conductive liquid.

On the other hand, when the object to be adsorbed is separated from the electrostatic chuck, the pump 10 is stopped and the stop valve 11 is closed (the stop valve 11 is unnecessary if the pump 10 has a structure for preventing backflow). The purge valve 12 is opened and N _{2 is} supplied from a purge gas supply source (not shown).
Gas is injected into the pipe 8 to discharge the electrically conductive liquid from the electrode cavities 2 and 2. In the present embodiment, N ₂ gas which is an inert gas is used as the purge gas, but the purge gas is not limited to this, and if there is no problem with the electrically conductive liquid to be used, the pipe 8, etc. Air or other gas can also be used. At the same time when the electrically conductive liquid is discharged, the voltage application to the potential fixing electrodes 3 and 3 is stopped. As a result, the portion of the electrode cavities 2 and 2 whose interior is replaced with a gas having a low dielectric constant (N ₂ gas),
The function as an internal electrode is lost and the adsorption force is rapidly reduced. Further, in this case, as will be described in detail below, even if electric charges are accumulated inside the object to be adsorbed, almost no residual adsorption force remains.

The phenomenon in which electric charges are accumulated inside the object to be attracted to the electrostatic chuck and the attracting force remains even when the voltage applied to the electrostatic chuck is turned off is apparently because the voltage is not applied to the object to be attracted. It is as if an attractive force is applied to the internal electrodes of the electrostatic chuck (ie,
Dielectric polarization occurs in the dielectric sandwiched between the charged adsorption target and the internal electrode that is a conductor, and the internal electrode becomes the apparent adsorption target).

Therefore, considering the case where the electrically conductive liquid is filled in the electrode cavities 2.2 (when no voltage is applied to the potential fixing electrodes 3.3), the residual adsorption force is considered. F ₁ is given by the following expression (2).

F ₁ = AS ₁ ε (V ₁ / d _A ) ² (2) where ε = ε ₀ · ε _r A: proportional constant S ₁ : electrode area on the electrostatic chuck side (cavity for electrodes Area of cross section 2) (m ² ) V ₁ : apparent applied voltage (V) due to charging of the adsorption target (V) d _A : adsorption target and internal electrode (upper end of electrode cavity 2)
Distance (m) ε ₀ : Dielectric constant of vacuum (8.85 × 10 ^-12 C ² N ^-1 m ^-2 ) ε _r : Dielectric constant of the dielectric, that is, inside the electrode cavity 2.2 The residual attraction force F ₁ when the electrically conductive liquid is filled in is the same as that of the conventional electrostatic chuck having the metal electrode as the internal electrode.

Next, consider a case where the electrically conductive liquid in the electrode cavities 2 is discharged and replaced with a gas having a low dielectric constant (N ₂ gas). Here, the first conceivable thing is that the potential fixing electrodes 3.3 provided in the electrode cavities 2.2 function as internal electrodes. However, the area of the potential fixing electrode 3.3 is sufficiently small compared to the total area of the suction surface 1a, the distance between the adsorption object and the potential fixing electrode 3.3 d _B (see FIG. 1) Is larger than d _A in the above formula (2), and furthermore, the inside of the electrode cavities 2.2 is replaced with a gas having a low dielectric constant.
The effect of the on the residual adsorption force is almost negligible.

Next, the metal support 4 is considered to function as an electrode. Therefore, the residual adsorption force F ₂ when the electrically conductive liquid in the electrode cavities 2.2 is discharged is
It becomes like the following formula (3).

F ₂ = AS ₂ ε (V ₁ / d _C ) ² (3) where ε = ε ₀ · ε _r A: proportional constant S ₂ : electrode area on the electrostatic chuck side (adsorption surface 1 a (M ² ) V ₁ : apparent applied voltage (V) due to charging of the adsorption target (V) d _C : distance (m) ε ₀ between the adsorption target and the electrode (support 4) : Dielectric constant of vacuum (8.85 × 10 ^-12 C ² N ^-1 m ^-2 ) ε _r : Dielectric constant of dielectric (consisting of dielectric 1 and gas layer in electrode cavity 2) In this case The electrode area S ₂ on the electrostatic chuck side is not so different from S _{1 in the} above formula (2) (the area of the internal electrodes of the electrostatic chuck is only slightly smaller than the area of the adsorption surface 1a). On the other hand, the distance d _C between the object to be adsorbed and the electrode (support 4) is larger than d _{A in the} above equation (2). For example, when d _A = 5 mm and d _C = 15 mm, the suction force (residual suction force) is inversely proportional to the square of the distance. Therefore, considering only the influence of the distance, (5/15) ² = 1 / 9, the residual suction force F ₂ is reduced to 1/9 times that of F ₁ .

Furthermore, there is a large difference in the relative permittivity ε _r of the dielectric between the above equation (2) and the above equation (3). Normally, the relative permittivity of gas is about 1, which is a fraction to a few tenths or less of that of the dielectric, and the residual adsorption force F ₂ is smaller than that of F ₁ .

As described above, in the electrostatic chuck of this embodiment, the electrically conductive liquid in the electrode cavities 2 is discharged, so that the electrostatic chuck of the present embodiment is different from the conventional electrostatic chuck in which the metal electrode is used as the internal electrode. The residual adsorption force can be sufficiently reduced.

Therefore, after discharging the electrically conductive liquid in the electrode cavities 2 and 2, it is not necessary to wait until the residual suction force becomes small, and the edge of the wafer (suction target) is immediately lifted by a lifting mechanism or the like. Even if the wafer is lifted, the wafer is not warped, displaced, or dropped unlike the conventional case. Therefore, by using the electrostatic chuck of the present embodiment, the inconvenient situation that has occurred conventionally can be
It can be avoided without lowering the throughput.

As described above, in the electrostatic chuck of this embodiment, the electrode cavity 2 is provided inside the dielectric body 1 and the electrically conductive liquid is introduced into and taken out from the electrode cavity 2.2. The liquid introduction passage 7a and the liquid discharge passage 7b for performing the formation are formed, and the potential fixing electrodes 3.3 to which a DC voltage is applied from the electrostatic chuck power supply 6 to a part of the electrode cavity 2.2. Is provided to fill the electrode cavity 2.2 with the electrically conductive liquid when adsorbing the object to be adsorbed, while the electrically conductive liquid inside the electrode cavity 2.2 is released when the object is adsorbed. Is configured to be discharged to the outside.

As a result, the residual suction force can be rapidly reduced while the suction target object is placed on the suction surface 1a of the dielectric 1, so that the edge of the suction target object is lifted during the detachment process. However, the adsorption target does not warp, and the removal process of the adsorption target can be performed easily and quickly.

In addition, the electrostatic chuck of the present embodiment has the above-mentioned configuration, in which the electric conductive liquid circulation path including the electrode cavity 2, the liquid introduction passage 7a and the liquid discharge passage 7b as a part of the circulation passage is formed. A means for circulating the electrically conductive liquid in the circulation path during the adsorption operation of the object to be adsorbed (a pipe 8, a reservoir tank 9, a circulation pump 10 forming a part of the circulation path); A heat exchanger (for example, a reservoir tank 9) that is provided in the heat exchanger and removes heat from the electrically conductive liquid.
In addition, the cooling efficiency of the object to be adsorbed during the adsorbing operation can be improved.

In the present embodiment, the bipolar electrostatic chuck has been described as an example, but of course, the present invention can be applied to a monopolar electrostatic chuck. The above-described embodiment is merely to clarify the technical contents of the present invention, and should not be construed in a narrow sense by limiting only to such specific examples. The spirit of the present invention and the claims Various modifications can be made within the range.

[0052]

As described above, in the electrostatic chuck of the present invention, the electrode cavity and the passage for introducing and discharging the electrically conductive liquid into the electrode cavity are provided inside the dielectric. In addition to being formed, in a part of the electrode cavity,
A potential fixing electrode to which a DC voltage is applied from a power source is provided, and a filling means for filling the electrode cavity with the electrically conductive liquid through the passage, and the electrically conductive liquid being discharged from the electrode cavity through the passage. And a discharge means for

Therefore, the residual suction force can be rapidly reduced in a state where the suction target object is placed on the suction surface, and the desorption process of the suction target object is hardly affected by the residual suction force. The effect is that it can be performed easily and quickly.

[Brief description of drawings]

FIG. 1 is a diagram illustrating an embodiment of the present invention and is an explanatory diagram illustrating a vertical cross-section of an adsorption portion of an electrostatic chuck and a schematic configuration of the entire electrostatic chuck.

FIG. 2 is a schematic perspective view showing a conventional bipolar electrostatic chuck.

FIG. 3 is an explanatory diagram for explaining a suction principle of the conventional bipolar electrostatic chuck.

FIG. 4 is an explanatory diagram for explaining a suction principle of a conventional single-pole type electrostatic chuck.

FIG. 5 is a schematic configuration diagram showing an electrostatic chuck including a wafer lifting mechanism.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Dielectric 1a Adsorption surface 2 Electrode cavity 3 Potential fixing electrode 4 Support stand 6 Electrostatic chuck power supply (power supply) 7a Liquid introduction passage (passage for introducing electrically conductive liquid) 7b Liquid discharge passage (electrical conduction) 8) Pipe (filling means, discharging means) 9 Reservoir tank (filling means, discharging means) 10 Pump (filling means) 11 Stop valve (filling means, discharging means) 12 Purge valve ( Ejection means)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location H01L 21/68 H01L 21/68 A 21/302 B

Claims (1)

[Claims] 1. An electrostatic chuck for adsorbing an object to be adsorbed on the surface of a dielectric by an electrostatic force, wherein a cavity for an electrode is provided inside the dielectric, and an electrically conductive liquid is introduced into and led out from the cavity for the electrode. And a passage for performing is formed in a part of the electrode cavity,
A potential fixing electrode to which a direct current voltage is applied from a power source is provided, and a filling means for filling the electrode cavity with the electrically conductive liquid through the passage, and discharging the electrically conductive liquid from the electrode cavity through the passage. An electrostatic chuck comprising: