TWI598987B - Electrostatic chuck device and its control method - Google Patents

Description

Electrostatic chuck device and control method thereof

The invention relates to an electrostatic chuck device for electrostatically adsorbing and holding an adsorbate (workpiece), and for positioning the adsorbate for fixing, or for transporting the adsorbed object to a specific purpose, particularly An electrostatic chuck device excellent in suction release when the workpiece is detached and a control method thereof.

In a semiconductor manufacturing process for manufacturing a semiconductor (integrated circuit) such as an IC or an LSI by forming an integrated circuit on a semiconductor wafer such as a semiconductor wafer, an etching device or a thin film formed by chemical vapor deposition (CVD) is used. An apparatus such as a slurry processing apparatus, an electron exposure apparatus, an ion drawing apparatus, and an ion implantation apparatus, and an ion doping apparatus is used in the manufacture of a liquid crystal panel for manufacturing a liquid crystal display panel used for a television screen or a computer monitor. An apparatus such as a substrate bonding apparatus used for injecting a liquid crystal into an insulating substrate such as glass, for the purpose of holding or transporting a wafer or glass for positioning. Electrostatic chucks are widely used. This system does not cause damage to adsorbed objects (workpieces) such as wafers or glass because the electrostatic chuck is held by a mechanical mechanism. From the viewpoint of the problem of the generation of fine particles caused by mechanical damage, or the compensation of the flatness of the adsorbed material to be retained, the performance is further improved.

Then, the electrostatic chuck has a Coulomb force type using an insulating material as a dielectric body due to its adsorption mode or adsorption principle, and the fixed resistance value is 10 ⁸ ~ 10 ¹³ Ω. The Johnson-Rahbek force type of the semiconductor of cm, the various patterns and the constituent electrodes of the comb-tooth shape or the multi-layer electrode structure form an uneven electric field on the adsorption surface, and absorb the gradient of the insulating material such as glass. (Gradient) force type, etc., when leaving the workpiece such as wafer or glass, the charge remains between the adsorption surface of the electrostatic chuck and the workpiece, and the residual charge is difficult to separate from the adsorption surface of the electrostatic chuck. In this case, when the workpiece is difficult to be detached from the adsorption surface of the electrostatic chuck, a large obstacle is caused to the holding or transport of the workpiece.

Here, even in the past, there are several proposals for solving such problems.

For example, in Patent Document 1, it is proposed that, in addition to a power source that applies a voltage between each pair of electrodes of the electrostatic adsorption device, when it is connected to the power source, it is applied between the pair of electrodes based on the zero potential. A series circuit of a resistor and a coil in which the voltage is positively and negatively alternately attenuated and vibrated. When the object to be processed is placed on the adsorption surface of the electrostatic chuck, the voltage between the electrodes is turned off, and the series circuit and the electrostatic chuck are formed. The RLC discharge circuit composed of the electrostatic capacitance causes the voltage between the electrodes to alternately attenuate and vibrate, and the insulator covering the electrode is electrically neutral, thereby avoiding the phenomenon that the object to be processed is difficult to be detached from the adsorption surface.

Further, in Patent Document 2, when the detachment is electrostatically adsorbed on the adsorbed body of the carrier, the charge supply source is cut off, and the neutralization capacitor is connected to the electrostatic chuck with reverse polarity, and the neutralization capacitor is used The electric charge accumulated between the carrier and the adsorbed body is neutralized, whereby the electrostatic chuck in which the detachment time of the adsorbed body is shortened can be achieved.

Further, Patent Document 3 proposes a system for detecting and removing a residual charge by applying a reverse polarity to an electrode of an electrostatic chuck when a semiconductor process component held in an electrostatic chuck in a reaction chamber is released by a chuck. Discharging the DC voltage and providing the residual charge grounding outlet by the rising pin unit to remove the residual charge. At this time, the rising pin unit is held at the same potential as the pedestal of the electrostatic chuck to prevent sparking when the RF power is applied. The parameter of the discharge voltage of the opposite polarity in the next suction release process is adjusted by the charge sensor detecting and measuring the amount of residual charge.

Further, Patent Document 4 proposes a bipolar electrostatic chuck in which a first electrode portion and a second electrode portion of a bipolar electrostatic chuck are applied with voltages having mutually different polarities, and are configured to have one polarity. An electrode having the other polarity is disposed around the electrode, and accordingly, the amount of residual electric charge remaining on the adsorption surface when the power line generated by applying the voltage stays in the vicinity of the adsorption surface and the workpiece is detached is minimized, and remains in a certain The charge of the electrode and the charge of the electrode remaining at the periphery of the electrode are efficiently offset each other, and the residual charge can be quickly eliminated when the workpiece is detached.

The method proposed in the above Patent Documents 1 to 3 is to block the electrical circuit of the electrostatic chuck when the workpiece of the electrostatic chuck is detached. The residual charge remaining on the adsorption surface or the workpiece of the electrostatic chuck is grounded and discharged, or neutralized by causing charges of opposite polarity to flow into the adsorption surface or the workpiece having residual charges, but in recent years, due to the requirement for the electrostatic chuck The method of increasing the adsorption force or the adsorption and detachment of the workpiece, and the structure of the electrostatic chuck is complicated, so that the method of grounding only the charge is discharged or the method of neutralizing the charge of the opposite polarity is used for neutralization. In it, it is difficult to remove the residual charge quickly and completely.

Further, in the methods of Patent Documents 1 to 3, since the effect of removing residual charges as expected from any one cannot be obtained, it has hardly been put into practical use or product production, and it is expected to be more effective. The solution to sex.

Further, in the method of Patent Document 4, the technique of processing the electrode portion of the bipolar electrostatic chuck, the amount of residual electric charge remaining on the adsorption surface when the workpiece is detached is minimized, and the technique is quickly eliminated. The technical feature lies in the pattern formation of the electrode structure of the electrostatic chuck, and it is desired to develop a solution that is based on the additional technical aspects of the electrical circuit processing of the electrostatic chuck.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Laid-Open Patent Publication No. 06-244270

[Patent Document 2] Japanese Patent Laid-Open No. Hei 11-040660

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2010-258452

[Patent Document 4] Japanese Patent Publication No. 2010-004915

Here, the present inventors have carefully studied the various problems caused by the residual charge when the workpiece of the electrostatic chuck is detached, and the electrostatic capacitance which can be changed by connecting the electrostatic capacitor in series between the electrostatic chuck and the DC power source can be used. The present invention has been accomplished by modifying the means and/or the capacitor to find out the suction release of the electrostatic chuck by a simple construction and indeed solving the problem caused by the residual charge when the workpiece is detached.

Furthermore, the inventors have found that when the electrostatic capacitance variable means in which the electrostatic capacitance can be changed is connected in series between the electrostatic chuck and the DC power source, the electrostatic capacitance of the electrostatic capacitance variable means is changed, so that it is not necessary to block the static electricity. The voltage applied to the suction cup can change the charge amount of the electrostatic chuck between the high value of the workpiece suction and the low value when the work is released (that is, the charge amount control of the electrostatic chuck), thereby not only solving the problem when the workpiece is detached. The problem caused by the residual charge improves the release of the suction cup of the electrostatic chuck, and can also solve various problems caused by the turning on and off of the power source (that is, when the electrostatic chuck is repeatedly used, the workpiece is attracted by the electrostatic chuck every time. In addition, the power supply needs to be turned on and off each time it is detached. However, each time the power is turned on when the power is turned on or off, a large inrush current flows into the circuit of the electrostatic chuck, which becomes an arc. The present invention has been completed by the cause of malfunction of the electrostatic chuck, or the cause of the failure of the power source due to the increase in the load on the power source.

Accordingly, an object of the present invention is to provide an electrostatic chuck device which is excellent in suction release property due to a problem caused by residual charges when a workpiece of an electrostatic chuck is detached.

Furthermore, another object of the present invention is to provide an electrostatic chuck device which is excellent in not only the problem of residual electric charge when the workpiece of the electrostatic chuck is detached, but also the release of the suction cup due to the problem of turning on or off the power source. .

Moreover, the other object of the present invention is to provide an electrostatic chuck connected to a DC power source, which can provide an action of adsorbing the workpiece of the electrostatic chuck and the workpiece detachment without blocking the application of a voltage to the electrostatic chuck, so that the charge amount of the electrostatic chuck is adsorbed on the workpiece. A method of controlling the electrostatic chuck device that changes between the high value of the time and the low value when the workpiece is detached (that is, the charge amount control of the electrostatic chuck).

That is, the present invention is an electrostatic chuck device excellent in suction release property, comprising: an electrostatic chuck, a DC power source of the electrostatic chuck, and a capacitance changing means connected in series between the electrostatic chuck and a DC power source, By changing the electrostatic capacitance of the electrostatic capacitance variable means, a voltage is applied to the electrostatic chuck, and the amount of charge of the electrostatic chuck is changed between a high value when the workpiece is adsorbed and a low value when the workpiece is detached. .

Furthermore, the present invention is an electrostatic chuck device excellent in suction release property, comprising: an electrostatic chuck, a DC power source of the electrostatic chuck, And a capacitor connected in series between the electrostatic chuck and the DC power source.

Then, the present invention is a method for controlling an electrostatic chuck device, which is a method for controlling an electrostatic chuck connected to a DC power source, characterized in that a capacitive variable means is connected in series between an electrode of the electrostatic chuck and a DC power source. By changing the electrostatic capacitance of the electrostatic capacitance variable means, in the state in which the voltage is applied to the electrostatic chuck, the operation of the workpiece suction and the workpiece detachment of the electrostatic chuck is performed, so that the charge amount of the electrostatic chuck is absorbed by the workpiece. The high value changes between the low value and the low value of the workpiece.

In the present invention, it is preferable to connect the electrostatic capacitance variable means in series between the electrode of the electrostatic chuck and the DC power source, and the electrostatic capacitance of the electrostatic chuck is set to C ₁ by the electrostatic capacitance variable means, and ₂ means the capacitance of the variable capacitance is C, the capacitance of the variable capacitance means C ₂ C ₁ is controlled to be at the workpiece suction <C _2, C ₁ becomes the disengaged the workpiece> C _2. By controlling the electrostatic capacitance of the electrostatic capacitance variable means to change, the electrostatic chuck sucks and holds the workpiece while the workpiece is being sucked, and when the workpiece is detached, the DC power supply is not cut while maintaining the voltage applied to the electrostatic chuck. In this case, it is possible to prevent the charge amount of the electrostatic chuck from being forcibly lowered, and the problem caused by the residual charge or the power source being turned on or off when the workpiece is detached.

In the present invention, the type of the electrostatic chuck to be used is not particularly limited, and in the case of an electrostatic chuck, even if it is a Coulomb type electrostatic chuck using an insulating material as a dielectric, the inherent resistance value is used. 10 ⁸ ~ 10 ¹³ Ω. The electrostatic chuck of the Johnson & Johnson Baker type of the semiconductor of cm, and the electrostatic chuck of the gradient force type which forms an uneven electric field on the adsorption surface even by using various patterns and constituent electrodes having a comb shape or a multi-layer electrode configuration. Also. In particular, when a gradient force type electrostatic chuck is used as the electrostatic chuck, there is an advantage that the amount of change in electrostatic capacitance is small and easy to control.

Furthermore, even for the electrostatic capacitance variable means used in the present invention, the electrostatic capacitance of the electrostatic chuck can be changed. If the charge amount of the electrostatic chuck is combined with the workpiece suction of the electrostatic chuck and the workpiece is detached, The value of the high value when the workpiece is adsorbed and the low value when the workpiece is detached are not particularly limited. However, since the operation or control is easy when the electrostatic capacitance is changed, the variable capacitor is preferable, and further, The Coulomb force type or Johnson & Johnson type auxiliary electrostatic chuck which is capable of detachably adsorbing the conductor to the adsorption surface having a specific adsorption area and changing the adsorption area of the conductor to the adsorption surface, and the capacitance easily changes.

In the present invention, the capacitance variable means for controlling the amount of charge of the electrostatic chuck may be constituted by one element of a capacitance variable means such as a variable capacitor or an auxiliary electrostatic chuck, and further, even if they are mutually The plurality of capacitance-capable means may be configured as a constituent element in series, and may be constituted by a plurality of capacitance-capable means constituent elements connected in parallel to each other.

In the present invention, the capacitance variable means and/or the capacitor may be assembled to the side of the electrostatic chuck, and may be incorporated in the DC power supply side. When the DC power supply device of the electrostatic capacitance variable means is included, it should be built in The range of the variable capacitance of the electrostatic capacitance variable means is used as a DC power supply device of an electrostatic chuck having various types or various adsorption properties, and can be utilized for the charge amount control of the electrostatic chuck.

In the electrostatic chuck device of the present invention, since the electrostatic capacitance changing means and/or the capacitor are connected in series between the electrostatic chuck and the DC power source, various problems caused by residual charges when the workpiece of the electrostatic chuck is detached are solved, and the suction plate release property is excellent.

Furthermore, in the case where the electrostatic capacitance variable means is connected in series between the electrostatic chuck and the DC power source, it is easy to control the amount of charge of the electrostatic chuck by changing the electrostatic capacitance of the electrostatic capacitance variable means, and thus it is not necessary to block the static electricity. The voltage applied by the suction cup can be matched with the action of the workpiece suction of the electrostatic chuck and the detachment of the workpiece, so that the charge amount of the electrostatic chuck changes between the high value of the workpiece suction and the low value when the workpiece is detached, and the workpiece of the electrostatic chuck is not only solved. At the time of the problem of residual charge and excellent suction release, it is also possible to solve various problems caused by the turning on and off of the power source.

Moreover, according to the control method of the electrostatic chuck device of the present invention, the electrostatic chuck connected to the DC power source can be used to prevent the voltage applied to the electrostatic chuck, and the electrostatic chuck can be combined with the workpiece suction of the electrostatic chuck and the workpiece to be detached. The amount of charge changes between the high value at the time of workpiece adsorption and the low value at which the workpiece is detached, and does not cause various problems caused by residual charge or power-on or disconnection due to the workpiece of the electrostatic chuck being detached.

1a, 1b, 1c, 1d, 1f‧‧‧ electrostatic chuck device

2‧‧‧Electrostatic suction cup

2a‧‧‧Dielectric body

2b‧‧‧ positive electrode

2c‧‧‧negative electrode

2x‧‧‧ capacitor

2y‧‧‧resistance

3‧‧‧DC power supply

4‧‧‧Solid capacitance means

4a, 4b‧‧‧variable capacitors

4c‧‧‧ capacitor

4x‧‧‧Auxiliary electrostatic chuck

4y‧‧‧Electrical conductor

W‧‧‧Workpiece

C ₁ , C ₂ , C ₃ ‧‧‧ electrostatic capacitors

Figure 1

Description (a) and circuit diagram (b) for explaining the first embodiment of the present invention.

Figure 2

It is an explanatory diagram for explaining the second embodiment of the present invention.

Figure 3

Description (a) and circuit diagram (b) for explaining the third embodiment of the present invention.

Figure 4

It is an explanatory view for explaining the fourth embodiment of the present invention.

Figure 5

It is explanatory drawing for explaining the fifth embodiment of the present invention.

Figure 6

It is explanatory drawing for explaining the sixth embodiment of the present invention.

Figure 7

It is explanatory drawing for explaining the seventh embodiment of the present invention.

Figure 8

Fig. 8 is an explanatory view showing an electrostatic chuck device according to an embodiment of the present invention.

[First embodiment]

Fig. 1(a) shows an electrostatic chuck device 1a according to a first embodiment of the present invention. The electrostatic chuck device 1a is a bipolar electrostatic chuck 2 composed of a dielectric body portion 2a and a positive electrode 2b and a negative electrode 2c embedded in the dielectric body portion 2a, and an electrostatic chuck 2 for the electrostatic chuck 2 A DC power source 3 to which a DC voltage is applied between the electrodes 2b and 2c, and a variable capacitor as a capacitance variable means 4 connected between the positive electrode 2b of the electrostatic chuck 2 and the positive electrode of the DC power source 3 in series 4a is composed.

Here, the bipolar electrostatic chuck 2 in which the two electrodes 2b and 2c are buried in the dielectric body portion 2a can be regarded as a pair of capacitors 2X and a resistor 2y present therebetween when viewed electrically. Since the electrostatic chuck device 1a related to the first embodiment in which the bipolar electrostatic chuck 2 is assembled can be used as an equivalent circuit shown in Fig. 1(b).

Here, in the electrostatic chuck device 1a according to the first embodiment, the electrostatic capacitance of the electrostatic chuck 2 is set to C ₁ , the electrostatic capacitance of the variable capacitor 4a is set to C ₂ , and further, from the direct current. When the DC voltage applied to the power source 3 is set to V, when the workpiece that adsorbs the workpiece W by the electrostatic chuck 2 is detached from the workpiece from which the workpiece W is detached from the electrostatic chuck 2, by using the electrostatic capacitance variable means 4 The electrostatic capacitance C _{2 of the} variable capacitor 4a is changed so that the charge amount Q of the electrostatic chuck 2 can be increased to the state A when the workpiece of the sufficient charge amount Q ₁ required for adsorbing the workpiece W is adsorbed, and the workpiece W can be easily separated from the workpiece W. The state B of the charge amount Q ₂ which does not cause the problem of residual charge changes when the workpiece is detached.

Here, the control of the capacitance C ₂ in the variable capacitor 4 is preferably controlled to be C ₁ <C ₂ when the workpiece is adsorbed, and C ₁ >C ₂ when the workpiece is detached. the amount of charge between the electrostatic chuck of the charge amount Q 2 in its state of work required and the adsorption a sufficient amount of charge Q ₁ and no problems in the state of the residual electric charge from the workpiece B, Q ₂ do Variety.

[Second embodiment]

Fig. 2 shows an electrostatic chuck device 1b according to a second embodiment of the present invention. The electrostatic chuck device 1b is different from the electrostatic chuck device 1a according to the first embodiment described above, and the electrostatic chuck 2 is embedded in the dielectric portion 2a with only one electrode (the positive electrode 2b in this embodiment). The unipolar electrostatic chuck 2 is constructed. Then, in the electrostatic chuck device 1b according to the second embodiment, a variable capacitor 4a serving as the capacitance variable means 4 is connected in series between the electrostatic chuck 2 and the positive electrode of the DC power source 3 to which the negative electrode is grounded. When the electrostatic chuck device 1b that performs adsorption and detachment of the workpiece W is operated, the workpiece W is used in a state where the workpiece W is grounded.

Even in the electrostatic chuck device 1b according to the second embodiment, as in the case of the electrostatic chuck device 1a according to the first embodiment described above, a positive electrode 2b can be buried in the dielectric body portion 2a. The unipolar electrostatic chuck 2 is regarded as a capacitor (electrostatic capacitor C ₁ ), so that the electrostatic chuck 2 can be charged by changing the electrostatic capacitance C ₂ of the variable capacitor 4a serving as the electrostatic variable means 4 The amount Q changes between the state A of the charge amount Q ₁ when the workpiece is adsorbed and the state B of the charge amount Q ₂ when the workpiece is detached, and further, even if the electrostatic capacitance C _{2 of} the variable capacitor 4a is controlled, it is ideal. It is also controlled to become C ₁ <C ₂ when the workpiece is adsorbed, and it is preferable to become C ₁ >C ₂ when the workpiece is detached.

[Third to Fifth Embodiments]

Fig. 3 is a view showing an electrostatic chuck device 1c according to a third embodiment of the present invention. Unlike the electrostatic chuck device 1a according to the first embodiment of the first embodiment, the electrostatic capacitance changing means 4 is connected in series. a variable capacitor 4a between the positive electrode 2b of the electrostatic chuck 2 and the positive electrode of the DC power source 3, and two variable capacitors of the variable capacitor 4b connected in series between the negative electrode 2c and the negative electrode of the DC power source 3 Composition. Further, Fig. 4 is a view showing an electrostatic chuck device 1d according to a fourth embodiment of the present invention. Unlike the electrostatic chuck device 1a according to the first embodiment of the first embodiment, the electrostatic capacitance changing means 4 is composed of Two variable capacitors composed of two variable capacitors 4a and 4b connected in parallel to each other are formed. Further, Fig. 5 is a view showing an electrostatic chuck device 1e according to a fourth embodiment of the present invention. Unlike the electrostatic chuck device 1a according to the first embodiment of the first embodiment, the electrostatic capacitance varying means 4 is The two variable capacitors 4a and 4c are connected in parallel to each other.

Even in the electrostatic chucks 1c, 1d, and 1e relating to the third to fifth embodiments, the electrostatic chuck device 1a according to the first embodiment described above is the same as the electrostatic capacitance. The electrostatic capacitance C ₂ of the variable capacitors 4a, 4b of the means 4 is changed, and the state A of the charge amount Q ₁ of the electrostatic chuck 2 when the workpiece is adsorbed, and the state B of the charge amount Q ₂ when the workpiece is detached can be made. Change between.

[Sixth embodiment]

Figure 6 is a view showing an electrostatic chuck device 1f according to a sixth embodiment of the present invention. The electrostatic chuck device 1f is different from the electrostatic chuck device 1a according to the first embodiment of the first embodiment. 4 is composed of an auxiliary electrostatic chuck 4x composed of a Coulomb type electrostatic chuck, and an electric conductor 4y such as an aluminum plate or a copper foil which is adsorbed on the adsorption surface of the auxiliary electrostatic chuck 4x by a specific area, and the electric conductor 4y is made. The change of the adsorption area of the adsorption surface of the auxiliary electrostatic chuck 4x changes the electrostatic capacitance C _{2 of} the electrostatic chuck 4x, thereby causing the state A of the charge amount Q ₁ of the electrostatic chuck 2 when the workpiece is adsorbed, and the workpiece to be separated from the workpiece. B change between the time the charge amount Q ₂ of the state.

In the electrostatic chuck device 1f according to the sixth embodiment, the electrostatic capacitance C _{2 of the} auxiliary electrostatic chuck 4x can be easily changed by changing the adsorption area of the conductor 4y to the adsorption surface of the auxiliary electrostatic chuck 4x. Therefore, the adsorption area when the workpiece is adsorbed and detached from the workpiece is set to an optimum value by the relationship with the workpiece W that is adsorbed and detached by the electrostatic chuck 2, whereby the electrostatic capacitance C _{2 of the} auxiliary electrostatic chuck 4x is controlled, which is ideal. the controlled adsorption of the workpiece becomes C ₁ <C _2, C ₁ becomes the disengaged the workpiece> C ₂ preferably.

Figure 7 is a diagram showing the seventh embodiment of the present invention. The electrostatic chuck device 1g is composed of a capacitor 4c having a capacitance variable means 4 mounted on the side of the electrostatic chuck 2 and/or the DC power source 3, and the residual charge is reduced by the presence of the capacitor 4c. The problem is to improve the suction of the suction cup of the electrostatic chuck 2.

[Examples]

As shown in Fig. 8, as the electrostatic chuck 2, an electrode layer having a pattern in which an insulating layer is interposed between the electrodes and patterned on the side of the workpiece adsorption surface is laminated, and another electrode layer is laminated on the opposite side. A gradient force type electrostatic chuck (ESC) having an adsorption surface of a size of 220 mm × 58 mm (see, for example, Patent No. 4825220), and further, as an auxiliary electrostatic chuck 4x of the capacitance variable means 4 In other words, a Coulomb type electrostatic chuck having an adsorption surface of a size of 300 mm × 300 mm is used, and as the conductor 4y adsorbed to the adsorption surface thereof, an aluminum plate of 350 mm × 350 mm × 1.1 mm is used, and as the DC power source 3, 1 kV is used. DC power supply, then, the positive electrode 2b of the electrostatic chuck 2 is connected to the negative electrode of the auxiliary electrostatic chuck 4x, the positive electrode of the auxiliary electrostatic chuck 4x is connected to the positive electrode of the DC power source 3, and the negative electrode of the DC power source 3 is connected to The negative electrode 2c of the electrostatic chuck 2 constitutes an electrostatic chuck device 1f according to this embodiment.

[Evaluation test of suction release performance]

With respect to the electrostatic chuck device 1f described above, first, the workpiece W is not adsorbed on the adsorption surface of the electrostatic chuck 2, and the conductor 4y is placed on the auxiliary body. In the initial state of the adsorption surface of the auxiliary electrostatic chuck 4x, the adsorption surface of the electrostatic chuck 2 is adsorbed, and a wafer having a size of 20 mm × 20 mm × 0.5 mm is used as the workpiece W to be removed. The suction release performance in the electrostatic chuck device 1f was sequentially investigated.

Sequence 1: The electrostatic chuck 2, the auxiliary electrostatic chuck 4x, the conductor 4y, and the workpiece W of the electrostatic chuck device 1f are cleaned by IPA (isopropyl alcohol).

In the second step, the workpiece W is placed on the adsorption surface of the electrostatic chuck 2 while the DC power source 3 is turned off.

Sequence 3: The DC power source 3 is turned on.

Sequence 4: The voltage of the DC power source 3 is stabilized at about 1 kV (after about 2 seconds), and the electrostatic chuck 2 is rotated by 90° so that the adsorption surface thereof becomes vertical.

Sequence 5: The conductor 4y adsorbed to the adsorption surface of the auxiliary electrostatic chuck 4x was peeled off and removed, and the falling state of the workpiece W at this time was observed.

Sequence 6: The DC power source 3 is turned off, and the falling state of the workpiece W at this time is observed.

[Measurement of changes in charge amount of electrostatic chucks and auxiliary electrostatic chucks]

In the above evaluation test of the suction-release performance, first, a copper foil having a size of 155 mm × 60 mm × 55 μm is placed on the electrostatic chuck 2 as a workpiece W, and further, the conductor 4y is placed on the auxiliary electrostatic chuck 4x, and the above-described order is measured. The change in the charge amount Q of the electrostatic chuck 2 and the auxiliary electrostatic chuck 4x before and after the measurement, the amount of charge Q ₁ when the workpiece is adsorbed, and the amount of charge Q ₂ when the workpiece is detached.

The results are shown in Table 1.

Next, one piece of the above-described workpiece W was prepared, and an aluminum plate of the above-mentioned conductor 4y was prepared. The suction cup release performance evaluation test was performed in accordance with the sequence 1 to 6 in which the workpiece W was repeated five times, and the suction release performance at this time was investigated. In this case, in the comparative example, only the electrostatic chuck 2 and the DC power source 3 are used as the electrostatic chuck device except for the auxiliary electrostatic chuck 4x and the conductor 4y, in accordance with the above sequence 1 → sequence 2 → sequence 3 → Sequence 4 → Sequence 6 to evaluate the suction release performance of the electrostatic chuck 2.

Further, for the evaluation of the suction performance of the suction cup, the case where the workpiece W was dropped from the adsorption surface of the electrostatic chuck 2 within 5 seconds was evaluated as ○, and the case where the workpiece W was not dropped was evaluated as ×.

These results are shown in Table 2.

As is apparent from the results shown in Table 1, when the electrostatic chuck device 1f of the embodiment is used, the workpiece W can be controlled by the adsorption and detachment of the auxiliary electrostatic chuck 4x by the conductor 4y (aluminum plate). Adsorption and detachment of the adsorption surface of 2, and further, by peeling off the conductor 4y (copper foil) adsorbed on the adsorption surface of the auxiliary electrostatic chuck 4x, the adsorption force of the workpiece in the adsorption surface of the electrostatic chuck 2 is lowered, and the workpiece is detached. When the suction cup is liberating, in addition to the excellent release performance of the suction cup, it can solve various problems caused by residual charge when the workpiece of the electrostatic chuck is detached, and the DC power supply is not required to be turned on or off, and the power supply can be solved. And disconnect the various problems caused. Further, when the drop rate after the sequence 6 is observed, the case where the electrostatic chuck device 1f of the embodiment is used is significantly improved in comparison with the comparative example, and since only the auxiliary electrostatic chuck 4x is present, the suction cup can be seen. The release performance is improved, so it is understood that the suction release performance can be improved even if a capacitor is connected in series between the electrostatic chuck and the DC power source.

1a‧‧‧Electrostatic suction cup device

2‧‧‧Electrostatic suction cup

2a‧‧‧Dielectric body

2b‧‧‧ positive electrode

2c‧‧‧negative electrode

2x‧‧‧ capacitor

2y‧‧‧resistance

3‧‧‧DC power supply

4‧‧‧Solid capacitance means

4a‧‧‧Variable Capacitors

W‧‧‧Workpiece

C ₁ , C ₂ ‧‧‧ electrostatic capacitor

Claims (9)

An electrostatic chuck device comprising: an electrostatic chuck, a DC power source of the electrostatic chuck, and a capacitive variable means connected in series between the electrostatic chuck and a DC power source, wherein the electrostatic capacitance variable means The electrostatic capacitance changes, and in a state where a voltage is applied to the electrostatic chuck, the amount of charge of the electrostatic chuck is changed between a high value when the workpiece is adsorbed and a low value when the workpiece is detached. The electrostatic chuck device according to claim 1, wherein the electrostatic capacitance variable means is provided when the electrostatic capacitance of the electrostatic chuck is C ₁ and the electrostatic capacitance of the electrostatic capacitance means is C ₂ C ₂ of the capacitance C is controlled to become adsorbed while the workpiece ₁ <C _2, while the workpiece becoming _{disengaged. 1} C> C _2. The electrostatic chuck device according to claim 1 or 2, wherein the capacitance variable means is a variable capacitor. The electrostatic chuck device according to claim 1 or 2, wherein the electrostatic capacitance changing means is a Coulomb force type or Johnson-Rahbek in which an electric conductor is detachably adsorbed to an adsorption surface having a specific adsorption area (Johnson-Rahbek) The auxiliary electrostatic chuck of the type changes the electrostatic capacitance of the electrostatic chuck by changing the adsorption area of the conductor to the adsorption surface of the auxiliary electrostatic chuck. Such as the electrostatic chuck installed in the scope of claim 1 or 2 The electrostatic capacitance changing means is composed of a plurality of variable capacitors and/or auxiliary electrostatic chucks connected in series with each other, and the auxiliary electrostatic chuck is a Coulomb force that the conductor can be detachably adsorbed to the adsorption surface having a specific adsorption area. The type or Johnson-Rahbek type changes the electrostatic capacitance of the electrostatic chuck by changing the adsorption area of the conductor to the adsorption surface of the auxiliary electrostatic chuck. The electrostatic chuck device according to claim 1 or 2, wherein the electrostatic capacitance changing means comprises a plurality of variable capacitors and/or an auxiliary electrostatic chuck connected in parallel with each other, and the auxiliary electrostatic chuck is an electric conductor. A Coulomb force type or a Johnson-Rahbek type that is adsorbed to an adsorption surface having a specific adsorption area, and the electrostatic adsorption surface is electrostatically changed by causing the electric conductor to change the adsorption area of the adsorption surface of the auxiliary electrostatic chuck. Capacitance changes. The electrostatic chuck device according to claim 1 or 2, wherein the capacitance variable means is mounted on a DC power source side. A control method for an electrostatic chuck device is a method for controlling an electrostatic chuck connected to a DC power source, characterized in that a capacitance variable means is connected in series between the electrostatic chuck and a DC power source, by making the electrostatic capacitance variable The electrostatic capacitance of the means changes While maintaining a voltage applied to the electrostatic chuck, the charge of the electrostatic chuck is changed between the high value of the workpiece suction and the low value of the workpiece when the workpiece is adsorbed and the workpiece is detached. The control method of the electrostatic chuck device according to the eighth aspect of the invention, wherein the electrostatic capacitance of the electrostatic chuck is C ₁ and the electrostatic capacitance of the variable capacitance means is C ₂ the variable capacitance means C ₂ C controlled to become adsorbed while the workpiece ₁ <C _2, while the workpiece becoming _{disengaged. 1} C> C _2.