JP2009054746A - Electrostatic chuck, and electrostatic chucking method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology for attracting and separating a sample to and from an electrostatic chuck quickly and surely, thus shortening the time required for attraction and separation. <P>SOLUTION: The electrostatic chuck includes a lift pin for holding a sample and moving it to a dielectric surface, and a chuck electrode control section for applying a third voltage when the tip of a lift pin is remote from the dielectric surface, applying a first voltage when the tip of the lift pin is in flush with the dielectric surface, and applying a second voltage lower than the first voltage when the tip of the lift pin comes into the dielectric surface. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electrostatic chuck capable of electrostatically adsorbing a sample and an electrostatic chuck method for chucking a sample.

In a semiconductor device manufacturing process, for example, when processing such as etching or CVD (chemical vapor deposition) is performed, an electrostatic chuck is used as a wafer mounting table. For example, Patent Document 1 discloses extreme ultraviolet light (Extreme) used in a vacuum.
An electrostatic chuck for use in EUV lithography using UV (EUV) is disclosed. The electrostatic chuck has a configuration in which a sheet-like chuck electrode having conductivity is sandwiched between insulating layers made of a dielectric material such as polyimide. After placing the wafer on the surface of the insulating layer, a DC voltage (chuck voltage) is applied from the DC power source to the chuck electrode to generate a Coulomb force in an area sandwiched between the chuck electrode and the wafer. Is configured to adsorb and hold.

  In addition, as disclosed in Patent Document 2, a semiconductor stacking apparatus that superimposes wafers in order to manufacture a three-dimensional mounting semiconductor in a semiconductor device manufacturing process has been proposed. In an apparatus as shown in Patent Document 2, a mounting table for transferring a wafer while it is mounted is necessary, and an electrostatic chuck is used instead of a vacuum chuck in consideration of ease of transfer.

Now, when electrostatically adsorbing a wafer on the mounting table, generally, the higher the applied voltage, the higher the Coulomb force. Therefore, it is desirable to apply a high voltage to securely hold the wafer. On the other hand, if a voltage higher than necessary is applied, it takes time to reduce the residual holding power even when the voltage application is stopped when the wafer is peeled from the mounting table after performing various processes. In addition, there is a possibility that breakage due to mechanical stress (strain) or wafer displacement on the lift pins may occur due to the forced peeling by the lift pins before the voltage application is stopped and the holding force is reduced. For this reason, a voltage slightly higher than the minimum voltage required for holding is applied to the mounting table.
JP 2006-040993 A JP 2005-251972 A

  However, if the wafer is lowered to the surface of the mounting table with the lift pins, and a voltage slightly higher than the necessary minimum voltage is applied, and then the lift pins are immediately lowered from the surface of the mounting table and then retracted, Therefore, the wafer may be displaced in the lateral direction because the holding force of the wafer is weak. Therefore, after a waiting time of about several seconds until the wafer is securely held on the mounting table, the lift pins must be lowered from the surface of the mounting table and then evacuated, which is one factor that decreases the processing speed. It was.

  The present invention has been made based on such circumstances, and the purpose thereof is to quickly and surely adsorb the sample to the electrostatic chuck, and to peel off the sample from the electrostatic chuck. It is to provide a technique capable of shortening the time required for the process.

In the electrostatic chuck according to the first aspect, a dielectric surface is provided on the surface of the chuck electrode, and a sample is electrostatically attracted to the dielectric surface by applying a voltage to the chuck electrode. The electrostatic chuck holds a sample and moves the sample relative to the dielectric surface, and applies a first voltage during a first time when the sample held by the lift pin comes into contact with the dielectric surface, A chuck electrode control unit that applies a second voltage lower than the first voltage after the first time has elapsed.
According to such a configuration, the first voltage which is a high voltage is applied when the sample comes into contact with the dielectric surface, and then the voltage is lowered after the first time has elapsed. Since a high voltage is first applied, a Coulomb force can be quickly generated between the dielectric surface and the sample.

The electrostatic chuck according to the second aspect applies a third voltage when the tip of the lift pin that holds the sample and moves the sample relative to the dielectric surface and the tip of the lift pin moves away from the dielectric surface, A chuck electrode control unit is provided that applies a first voltage when it is on the same plane as the dielectric surface, and applies a second voltage lower than 1 voltage when the tip of the lift pin enters the dielectric surface.
With this configuration, the third voltage is applied before the lift pin abuts the sample against the dielectric surface, and a high first voltage is applied when the tip of the lift pin is on the same surface as the dielectric surface. Is possible. In addition, since a low voltage is finally applied to the chuck electrode, quick separation is possible even when the sample is detached.

An electrostatic chuck method according to a third aspect includes a step of applying a third voltage to the chuck electrode before the sample is electrostatically attracted to the dielectric surface, and a method of applying the third voltage to the chuck electrode when the sample contacts the dielectric surface. A step of applying a first voltage for a first time, and a step of applying a second voltage lower than the first voltage to the chuck electrode after the elapse of the first time.
According to such an electrostatic chuck method, the third voltage is applied before the sample is electrostatically attracted to the dielectric surface, and a high first voltage is applied when the sample contacts the dielectric surface. The sample can be quickly adsorbed. In addition, since a low voltage is finally applied to the chuck electrode, the sample can be quickly detached even when the sample is detached, and the throughput can be improved.

<Configuration of electrostatic chuck>
The configuration of the electrostatic chuck 100 according to the present invention will be described with reference to FIGS. 1A and 1B.
FIG. 1A is a cross-sectional view showing the overall structure of the electrostatic chuck 100 of this embodiment, and FIG. 1B shows that the wafer holder 20 and the holder holding base 40 of the electrostatic chuck 100 are separated, and the wafer holder 20 is supported by the wafer holder transfer arm 71. FIG.

The wafer holder 20 has a columnar support 21, a chuck electrode 23, and a first connection terminal 25. The support base 21 is made of an insulator made of alumina (Al ₂ O ₃ ) ceramic, for example, and has a holder surface that holds the 300 mm wafer W. A first through hole 24 is formed in the support base 21 for a lifting pin 30 described later.

The holder surface is polished to ensure uniform surface accuracy. The chuck electrode 23 is made of, for example, a sheet-like metal and is covered with an insulator. The chuck electrode 23 is connected to the first connection terminal 25 by internal wiring. Note that the volume specific resistance value of the insulator is preferably 10 ¹² Ωcm or more. When a DC voltage is applied to the chuck electrode 23, the surface of the support base 21, that is, the holder surface becomes a dielectric surface.

  The holder holding table 40 includes a columnar holding table 41, a moving plate 46, a shaft 47 that moves the moving plate 46, and a drive motor 48. Furthermore, the holder holding base 40 has, for example, three elevating pins 30 for transferring the wafer W to and from a transfer arm (not shown) provided outside. The elevating pins 30 are movably provided through a first through hole 24 formed in the support base 21 and a second through hole 44 formed in the holding base 41 of the holder holding base 40. The lower ends of the elevating pins 30 are fixed to the moving plate 46, and the elevating pins 30 also move up and down as the shaft 47 moves up and down as the drive motor 48 rotates. The holding table 41 and the moving plate 46 are made of a metal material such as a stainless material. A conductive member 37 is formed at the tip of the elevating pin 30, and its wiring is connected to the switch 13.

  The shaft 47 and the drive motor 48 can move the lifting pins 30 to arbitrary positions (heights), and can be temporarily stopped. Instead of the shaft 47 and the drive motor 48, a multistage air cylinder having a first stroke and a second stroke may be used.

  As shown in FIG. 1B, the support base 21 of the wafer holder 20 and the holding base 41 of the holder holding base 40 are detachable. Positioning pins 49 are provided on the holding base 41, and positioning holes 29 are provided on the support base 21. For this reason, when the wafer holder 20 is installed on the holder holding table 40, the positioning of the support table 21 with respect to the holding table 41 is completed. Accordingly, the axes of the first through hole 24 formed in the support base 21 and the second through hole 44 formed in the holding base 41 coincide with each other so that the lifting pin 30 can move. When the positioning of the support base 21 with respect to the holding base 41 is completed, the second connection terminal 45 provided on the holding base 41 and the first connection terminal 25 provided on the support base 21 coincide with each other to complete electrical conduction. Will do. The wiring connected to the second connection terminal 45 is connected to the changeover switch 11.

  Further, the electrostatic chuck 100 has a control unit 50. The control unit 50 can send signals to the changeover switch 11 and the switch 13, and can further send a drive signal to the drive motor 48. By switching the connection of the changeover switch 11, the chuck electrode 23 can be connected to the DC power source DC via the first connection terminal 25 and the second connection terminal 45. When the wafer W is attracted, a DC electric field is applied from the DC power source DC to the chuck electrode 23, and when the wafer W is attracted, the electric charge of the wafer holder 20 is released to the ground. The DC power source DC can change the DC voltage from 80V to 240V.

  By switching the connection of the changeover switch 13, the conductive member 37 at the tip of the elevating pin 30 can be grounded (grounded). The conductive member 37 is not grounded (earth) when the wafer W is attracted, and when the wafer W is detached, the electric charge accumulated on the surface of the wafer holder 20 and the wafer W can be released to the ground. The control unit 50 moves the lifting pin 30 up and down by sending a driving signal to the driving motor 48. An external signal is input to the control unit 50 so that it can operate in synchronization with EUV lithography, CVD, or a semiconductor stacking apparatus.

  In FIG. 1B, the wafer holder 20 can be attached to and detached from the holder holding base 40 by the wafer holder transfer arm 71. This is because the wafer holder 20 is moved while holding the wafer W. The wafer holder transfer arm 71 is also provided with a third connection terminal 75 that is electrically connected to the first connection terminal 25 of the wafer holder 20, and a DC voltage is supplied from a DC power source (not shown) to move the wafer W while the wafer holder 20 is moving. Adsorption can be performed.

<Configuration of lifting pins>
Next, the detail of the raising / lowering pin 30 is demonstrated. FIG. 2 is a cross-sectional view of one of the plurality of lifting pins 30.

  The elevating pin 30 attached to the moving plate 46 has a hollow tube structure, and a vacuum pulling tube 33 is formed at the center of the elevating pin 30. The vacuum pipe 33 is connected to a pipe PI, and the pipe PI is connected to the vacuum pump PO. Although not shown, a two-port solenoid valve is arranged in the pipe PI, and the release of the atmospheric pressure and the evacuation are switched by the solenoid valve.

  The elevating pins 30 themselves are made of a metal rod 31 such as stainless steel, but the periphery thereof is covered with insulating plastic or insulating rubber which is an elastic insulating member 35. A conductive member 37 is formed at the tip of the lift pins 30 that are in contact with the wafer W. The conductive member 37 uses an alloy such as copper (Cu) or aluminum (Al). The conductive member 37 is connected to the switch 13. Since the elevating pin 30 itself is conductive, it may be formed integrally with the conductive member 37.

<Adsorption operation of electrostatic chuck: Example 1>
FIG. 3A is a timing chart for explaining an adsorption operation of the electrostatic chuck 100 according to the first embodiment, and FIG. 3B is a flowchart thereof. The controller 50 performs the suction operation of the electrostatic chuck 100. As described above, the wafer holder 20 can be attached to and detached from the holder holding base 40, but FIG. 3 shows the operation with the wafer holder 20 mounted on the holder holding base 40.

  In the upper chart of FIG. 3A, the horizontal axis represents time, and the vertical axis represents the voltage applied to the chuck electrode 23. In the middle chart of FIG. 3A, the horizontal axis represents time, and the vertical axis represents the height of the lifting pins 30. In the middle chart of FIG. 3A, the horizontal axis represents time, and the vertical axis represents the degree of vacuum of the elevating pins 30. Hereinafter, the flowchart of FIG. 3B will be described with reference to FIG.

  In step S <b> 12, the lift pins 30 vacuum-suck the wafer W on the wafer holder 20. That is, at time t 1, the lift pins 30 are at the delivery position Pa on the wafer holder 20 by the drive motor 48. Then, the wafer W is transferred to and from a transfer arm (not shown). When the wafer W is delivered, it can be vacuum-sucked by the vacuum pump PO, and the wafer W is vacuum-sucked by the tip of the lift pins with the degree of vacuum Pt. In the first embodiment, no DC voltage is applied to the chuck electrode 23 from the DC power source DC at time t1.

  In step S <b> 14, the lift pins 30 lower the wafer W to the contact position Pc of the wafer holder 20. And the raising / lowering pin 30 stops at the contact position Pc. That is, between time t1 and time t2, the lift pins 30 are lowered from the transfer position Pa to the contact position Pc in a state where the wafer W is vacuum-sucked. The time t1 to the time t2 is, for example, about 1 second to 5 seconds. The contact position Pc of the elevating pin 30 is substantially the same height as the surface of the support base 21, but cannot be exactly the same surface. In the first embodiment, the contact position Pc is in a range from −0.1 mm to 0.2 mm from the same surface.

In step S <b> 16, since the elevating pin 30 has reached the contact position Pc, the control unit 50 connects the changeover switch 11 to the DC power source DC and applies the voltage V <b> 2 to the chuck electrode 23 of the wafer holder 20. This is because charges are not accumulated in the wafer holder 20 immediately after the voltage V2 is applied to the chuck electrode 23. When the voltage V2 is applied to the chuck electrode 23, the insulating support 21 made of alumina (Al ₂ O ₃ ) ceramic is polarized to generate charges, and the surface of the support 21 becomes a dielectric surface. Then, a Coulomb force is generated between the dielectric surface of the support table 21 and the wafer W, and the wafer W is attracted and attracted to the surface of the support table 21. The voltage V2 is, for example, a DC voltage from 150V to 200V.

  In step S18, a predetermined time TA1 is waited for the wafer W to be attracted to the dielectric surface of the support 21 and stably electrostatically attracted. The vacuum degree Pt of the elevating pin 30 continues as it is even during the time TA1, that is, the period from the time t2 to the time t3. The time TA1 is about 2 to 5 seconds depending on the voltage. If a minimum voltage V1 is applied so that the wafer W does not deviate from the surface of the support base 21, it takes a long time for stable electrostatic adsorption, so a higher voltage is applied.

  In step S20, the control unit 50 changes the voltage of the chuck electrode 23 from the voltage V2 to the minimum voltage V1. The minimum voltage V1 is such a voltage that the wafer W does not deviate from the surface of the support table 21, and is, for example, about 100V to about 150V. This is because, if the voltage V2 is kept applied to the chuck electrode 23, it takes a long time to remove electricity even if the electricity removal plasma is generated when the wafer W is detached from the surface of the support base 21.

In step S22, the vacuum suction of the elevating pins 30 is stopped and released to the atmospheric pressure At. As a result, the wafer W and the lift pins 30 are separated. The release to the atmospheric pressure At is performed at the same time t3 as the voltage change of the chuck electrode 23 in step S20.
In step S24, the elevating pin 30 is lowered from the delivery position Pa to the retracted position Pe. As described above, the elevating pins 30 cannot be exactly flush with the surface of the support base 21. If the elevating pins 30 are higher than the surface of the support base 21, the wafer W is warped. Therefore, the elevating pin 30 is lowered to the retracted position Pe.

<Adsorption operation of electrostatic chuck: Example 2>
FIG. 4A is a timing chart for explaining an adsorption operation of the electrostatic chuck 100 according to the second embodiment, and FIG. 4B is a flowchart thereof. The controller 50 performs the suction operation of the electrostatic chuck 100. In this embodiment, the operation is also performed with the wafer holder 20 mounted on the holder holding base 40.

  All the charts in FIG. 4A are the same as those in FIG. 3A, and time is taken on the horizontal axis. Hereinafter, the flowchart of FIG. 4B will be described with reference to FIG.

  In step S <b> 32, the lift pins 30 vacuum-suck the wafer W on the wafer holder 20. That is, at time t 1, the lift pins 30 are at the delivery position Pa on the wafer holder 20 by the drive motor 48. Then, the wafer W is transferred to and from a transfer arm (not shown). When the wafer W is delivered, it can be vacuum-sucked by the vacuum pump PO, and the wafer W is vacuum-sucked by the tips of the lift pins.

  In step S <b> 34, when the elevating pins 30 receive the wafer W, the control unit 50 applies a voltage V <b> 3 from the DC power source DC to the chuck electrode 23. The voltage V3 may be changed depending on the difference between time t1 and time t2 or the charge accumulation state of the support base 21. For example, the control unit 50 may apply the voltage V <b> 4 drawn with a dotted line to the chuck electrode 23. That is, the voltage V3 or the voltage V4 can set an arbitrary DC voltage from 80V to 200V.

  In step S <b> 36, the lift pins 30 lower the wafer W to the contact position Pc of the wafer holder 20. And the raising / lowering pin 30 stops at the contact position Pc. That is, between time t1 and time t2, the lift pins 30 are lowered from the transfer position Pa to the contact position Pc in a state where the wafer W is vacuum-sucked. The time t1 to the time t2 is, for example, about 1 second to 5 seconds. The contact position Pc of the elevating pin 30 is substantially the same height as the surface of the support base 21, but cannot be exactly the same surface. In the second embodiment, the contact position Pc is in the range of −0.1 mm to 0.2 mm from the same surface.

  In step S38, since the elevating pin 30 has reached the contact position Pc, the control unit 50 changes the voltage of the chuck electrode 23 from the voltage V3 to the voltage V2. Unlike the first embodiment, in the second embodiment, since the voltage V3 has already been applied to the chuck electrode 23, charges are accumulated on the support base 21. Therefore, the charge generated on the support base 21 immediately affects the wafer W. A Coulomb force is generated between the dielectric surface of the support table 21 and the wafer W, and the wafer W is attracted and attracted to the dielectric surface of the support table 21. The voltage V2 is, for example, a DC voltage from 150V to 200V.

  In step S40, a predetermined time TA2 is waited for the wafer W to be attracted to the dielectric surface of the support 21 and stably attracted electrostatically. Even during the period of time TA2, that is, from time t2 to t3, the vacuum suction of the elevating pin 30 is continued as it is. A time shorter than the time TA1 of the first embodiment is sufficient as the time TA2. This is because the voltage V3 was applied to the chuck electrode 23 from time t1 to time t2.

  In step S42, the control unit 50 changes the voltage of the chuck electrode 23 from the voltage V2 to the minimum voltage V1. The minimum voltage V1 is such a voltage that the wafer W does not deviate from the surface of the support table 21, and is, for example, about 100V to about 150V.

In step S44, at the same time t3 as the voltage change of the chuck electrode 23 in step S42, the vacuum suction of the elevating pins 30 is stopped and released to the atmospheric pressure At.
In step S46, the elevating pin 30 is lowered from the delivery position Pa to the retracted position Pe.

<Adsorption operation of electrostatic chuck: Example 3>
FIG. 5A is a timing chart for explaining an adsorption operation of the electrostatic chuck 100 according to the third embodiment, and FIG. 5B is a flowchart thereof. The controller 50 performs the suction operation of the electrostatic chuck 100. In this embodiment, the operation is also performed with the wafer holder 20 mounted on the holder holding base 40.

  All of the charts in FIG. 5A are the same as those in FIG. 3A, and time is taken on the horizontal axis. Hereinafter, the flowchart of FIG. 5B will be described with reference to FIG.

  In step S <b> 52, the lift pins 30 vacuum-suck the wafer W on the wafer holder 20. That is, at time t 1, the lift pins 30 are at the delivery position Pa on the wafer holder 20 by the drive motor 48. Then, the wafer W is transferred to and from a transfer arm (not shown). When the wafer W is delivered, it can be vacuum-sucked by the vacuum pump PO, and the wafer W is vacuum-sucked by the tips of the lift pins.

  In step S54, when the elevating pins 30 receive the wafer W, the control unit 50 applies a voltage V3 from the DC power source DC to the chuck electrode 23. The voltage V3 varies from voltage t1 to voltage V2 from time t1 to time t2. As shown in FIG. 5A, the voltage may be linearly varied, or may be sequentially varied from the voltage V3 to the voltage V2 on a staircase. The voltage V3 can set an arbitrary DC voltage from 80V to 200V. The voltage V2 is, for example, a DC voltage from 150V to 200V.

  In step S <b> 56, the lift pins 30 lower the wafer W to the contact position Pc of the wafer holder 20. And the raising / lowering pin 30 stops at the contact position Pc. That is, between time t1 and time t2, the lift pins 30 are lowered from the transfer position Pa to the contact position Pc in a state where the wafer W is vacuum-sucked. The time t1 to the time t2 is, for example, about 1 second to 5 seconds. The contact position Pc of the elevating pin 30 is substantially the same height as the surface of the support base 21, but cannot be exactly the same surface. In the third embodiment, the contact position Pc falls within the range of −0.1 mm to 0.2 mm from the same surface.

  In step S58, the elevating pin 30 reaches the contact position Pc, and the voltage of the chuck electrode 23 is the voltage V2. Unlike the first embodiment, in the third embodiment, the voltage V <b> 2 to the voltage V <b> 2 has already been applied to the chuck electrode 23. Therefore, the charge generated on the support base 21 immediately affects the wafer W. A Coulomb force is generated between the dielectric surface of the support table 21 and the wafer W, and the wafer W is attracted and attracted to the dielectric surface of the support table 21.

  In step S60, a predetermined time TA3 is waited for the wafer W to be attracted to the dielectric surface of the support 21 and stably electrostatically attracted. Even during the period of time TA3, that is, from time t2 to t3, the degree of vacuum Pt of the elevating pin 30 continues as it is. The time TA3 may be shorter than the time TA1 of the first embodiment. This is because a variable voltage from voltage V2 to voltage V3 was applied to the chuck electrode 23 from time t1 to time t2.

  In step S62, the control unit 50 changes the voltage of the chuck electrode 23 from the voltage V2 to the minimum voltage V1. The minimum voltage V1 is such a voltage that the wafer W does not deviate from the surface of the support table 21, and is, for example, about 100V to about 150V.

In step S64, the vacuum pin 30 is stopped from being sucked and released to the atmospheric pressure At. This is performed at time t3 at the same time as the voltage change of the chuck electrode 23 in step S62.
In step S66, the elevating pin 30 is lowered from the delivery position Pa to the retracted position Pe.

  As described above, according to the chucking operation of the electrostatic chucks of the first to third embodiments, the time for chucking the wafer W to the electrostatic chuck 23 can be shortened and the wafer W is detached from the support base 21. In this case, since the minimum voltage is applied to the electrostatic chuck 23, the time required for peeling can be shortened.

<Removal operation of electrostatic chuck>
FIG. 6A is a timing chart for explaining the separation operation of the electrostatic chuck 100, and FIG. 6B is a flowchart thereof. The controller 50 performs the separation operation of the electrostatic chuck 100.

  All the charts in FIG. 6A are the same as those in FIG. 3A, and time is taken on the horizontal axis. Hereinafter, the flowchart of FIG. 6B will be described with reference to FIG.

  In step S <b> 102, the control unit 50 switches the changeover switch 11 from the DC power source DC to the ground, and releases the charge accumulated in the support base 21 to the ground. That is, electrostatic adsorption is stopped at time t5.

In step S <b> 104, the lift pins 30 are raised to the contact position Pc of the wafer holder 20.
In step S106, the conductive member 37 at the tip of the elevating pin 30 is grounded by switching the connection of the changeover switch 13. The charges accumulated on the wafer W are also released to the ground.

  In step S108, the apparatus waits for a predetermined time TA5 to discharge the charges on the wafer W and the support table 21. As described above, since the voltage of the chuck electrode 23 that electrostatically attracts the wafer W is set to the minimum voltage V1, the time for discharging the charge can be shortened. In addition to discharging the charge of the support base 21, the charge is released using the conductive member 37 at the tip of the elevating pin 30, so that the charge can be quickly released. In addition, in order to release electric charges earlier, static elimination plasma may be generated to release electric charges on the support table 21 and the wafer W.

  In step S110, the lift pins 30 are vacuum-sucked to suck the wafer W. That is, when the conductive member 37 of the lift pins 30 contacts the wafer W at time t7, vacuum suction of the wafer W is started.

  In step S112, when the time TA5 has elapsed, that is, when time t8 is reached, the elevating pins 30 are raised to the delivery position Pa, and the wafer W is delivered to and from a transfer arm (not shown).

  In the above, as means for positively promoting the charge removal of the residual charges on the wafer W and the wafer holder 20, the grounding of the support base 21, the grounding by the conductive member 37, and the generation of the discharge plasma are mentioned. By vibrating the wafer holder 20, it is possible to weaken the localized residual charge adsorption force.

It is sectional drawing which shows the whole structure of the electrostatic chuck 100 which concerns on this invention. 4 is a cross-sectional view in which the wafer holder 20 and the holder holding base 40 of the electrostatic chuck 100 are separated and the wafer holder 20 is supported by a wafer holder transfer arm 71. FIG. 3 is an enlarged view showing a cross-sectional view of one lifting pin 30. FIG. 2 is a timing chart for explaining an adsorption operation of the electrostatic chuck 100 according to the first embodiment, and FIG. It is a timing chart explaining the adsorption | suction operation | movement of the electrostatic chuck 100 of Example 2, (b) is the flowchart. It is a timing chart explaining the adsorption | suction operation | movement of the electrostatic chuck 100 of Example 3, (b) is the flowchart. 4 is a timing chart for explaining the detachment operation of the electrostatic chuck 100, and FIG.

Explanation of symbols

W ... Semiconductor wafer 11, 13 ... Changeover switch 20 ... Wafer holder 21 ... Supporting part 23 ... Chuck electrode 25, 45, 75 ... First connection terminal, second connection terminal, third connection terminal 30 ... Lifting pin 35 ... Elastic insulating member 37 ... Conductive member 40 ... Holder holding base 41 ... Holding base 46 ... Moving plate 47 ... Shaft 50 ... Control unit 71 ... Wafer holder transfer arm 100 ... Electrostatic chuck DC ... DC power supply

Claims (8)

In the electrostatic chuck in which a dielectric surface is provided on the surface of the chuck electrode, and a sample is electrostatically attracted to the dielectric surface by applying a voltage to the chuck electrode.
A lift pin that holds the sample and moves the sample relative to the dielectric surface;
A chuck electrode control unit that applies a first voltage during a first time when the sample held by the lift pin contacts the dielectric surface, and applies a second voltage lower than the first voltage after the first time has elapsed. And an electrostatic chuck.   2. The electrostatic chuck according to claim 1, wherein the lift pin stops for the first time in a state where a tip of the lift pin is located on the same plane as the dielectric surface.   The electrostatic chuck according to claim 1, wherein the chuck electrode controller applies a third voltage before the sample is electrostatically attracted to the dielectric surface. In the electrostatic chuck in which a dielectric surface is provided on the surface of the chuck electrode, and a sample is electrostatically attracted to the dielectric surface by applying a voltage to the chuck electrode.
A lift pin that holds the sample and moves the sample relative to the dielectric surface;
A third voltage is applied when the tip of the lift pin is moving away from the dielectric surface, a first voltage is applied when the tip of the lift pin is flush with the dielectric surface, and the tip of the lift pin is An electrostatic chuck comprising: a chuck electrode control unit that applies a second voltage lower than the first voltage when entering from a dielectric surface.   2. A vacuum suction hole is formed at a tip of the lift pin, and the hole sucks the sample in a vacuum when the tip of the lift pin moves away from the dielectric surface. Item 5. The electrostatic chuck according to any one of items 4 to 5. A conductive surface is formed at the tip of the lift pin,
The electrostatic chuck according to any one of claims 1 to 5, further comprising a switch for bringing the conductive surface into a grounded state or a non-grounded state.   2. The electrostatic chuck can separate a support base for supporting the sample and the lift pin, and the support base is movable while electrostatically attracting the sample. The electrostatic chuck according to claim 6. Applying a third voltage to the chuck electrode before the sample is electrostatically attracted to the dielectric surface;
Applying a first voltage to the chuck electrode for a first time when the sample contacts a dielectric surface;
Applying a second voltage lower than the first voltage to the chuck electrode after the first time has elapsed. An electrostatic chuck method comprising: