Power supply for electrostatic adsorption device, electrostatic adsorption device, and detachment adsorption control method

Abstract

The electrostatic adsorption device (1) of the present invention includes: a voltage application unit (3) that applies a desorption voltage used when the object to be held (K) is desorbed from adsorption. The desorption voltage is composed of a first AC voltage (Va1) applied to the first electrode (5) in a first waveform (W1) and a second AC voltage (Va2) applied to the second electrode (6) in a second waveform (W2) having a phase difference from the first waveform (W1). The electrostatic adsorption device has an information output unit that outputs correlation information at the timing when the first waveform (W1) intersects the second waveform (W2). The voltage application unit (3) stops applying the desorption voltage to the first electrode (5) and the second electrode (6) based on the information.

Description

Technical Field

[0001] The present invention relates to a power supply for an electrostatic adsorption (Chuck) device, an electrostatic adsorption device, and a dechuck control method. Background Art

[0002] As an existing electrostatic adsorption device, for example, there is an electrostatic holding device described in Patent Document 1. This existing electrostatic holding device includes: an electrostatic holding mechanism in which a plurality of electrodes are arranged in an insulator layer, and a switching mechanism that switches the connection state between the electrostatic holding mechanism and a DC power supply and an AC power supply. In this electrostatic holding device, when the object to be held is dechucked, an AC voltage is applied to the electrodes to remove the charge of the electrostatic holding mechanism.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent Publication No. 6-71944

[0006] Patent Document 2: Japanese Patent Application Laid-Open No. 62-44332 Summary of the Invention

[0007] Technical Problem to be Solved by the Invention

[0008] When removing charge using an AC voltage, currently, a method of gradually decreasing the AC voltage applied to the electrodes over time is adopted (for example, refer to Patent Document 2). However, with this existing method, it takes about several seconds for the charge of the holding part to be removed. Therefore, the technical problem is to shorten the time from when the object to be held starts to separate from the holding part until dechucking is completed.

[0009] The present invention is made to solve the above technical problem, and an object thereof is to provide a power supply for an electrostatic adsorption device, an electrostatic adsorption device, and a dechuck control method that can shorten the time from when the object to be held starts to separate from the holding part until dechucking is completed.

[0010] Technical Means for Solving the Technical Problem

[0011] A power supply for an electrostatic adsorption device according to one aspect of the present invention includes: a voltage application unit that applies a dechuck voltage used when an object to be held is dechucked to a first electrode and a second electrode, the dechuck voltage being composed of a first AC voltage applied to the first electrode in a first waveform and a second AC voltage applied to the second electrode in a second waveform having a phase difference from the first waveform, the power supply for the electrostatic adsorption device having an information output unit that outputs information based on the timing of the intersection of the first waveform and the second waveform, and the voltage application unit stops applying the dechuck voltage to the first electrode and the second electrode based on the information.

[0012] In the power supply for the electrostatic adsorption device, when releasing adsorption, based on the correlation information of the timing at which the waveform of the first AC voltage intersects with the waveform of the second AC voltage, the application of the release adsorption voltage to the first electrode and the second electrode is stopped. According to this configuration, without waiting for the first AC voltage and the second AC voltage to decay, the application of the release adsorption voltage to the first electrode and the second electrode can be actively stopped at a timing suitable for separating the object to be held. Therefore, the power supply for the electrostatic adsorption device can shorten the time from the start of releasing adsorption until the object to be held is separated from the holding portion.

[0013] The information output unit can obtain information by detecting the first AC voltage and the second AC voltage. In this case, the information output unit can appropriately output information, and the application of the release adsorption voltage can be stopped at a timing suitable for separating the object to be held. Therefore, the time from the start of releasing adsorption until the object to be held is separated from the holding portion can be shortened.

[0014] The information output unit can pre-hold information based on the first AC voltage and the second AC voltage. In this case, the information output unit can appropriately output information, and the application of the release adsorption voltage can be stopped at a timing suitable for separating the object to be held. Therefore, the time from the start of releasing adsorption until the object to be held is separated from the holding portion can be shortened.

[0015] The voltage application unit can apply the release adsorption voltage to the first electrode and the second electrode in such a way that the first waveform and the second waveform have opposite phases. In this case, since positive and negative potentials are alternately applied to the first electrode and the second electrode, the charge removal efficiency of the holding portion by the first AC voltage and the second AC voltage can be improved.

[0016] The voltage application unit can apply the release adsorption voltage to the first electrode and the second electrode in such a way that the values of the first AC voltage and the second AC voltage are both 0 when the first waveform and the second waveform intersect. In this case, since the application of the release adsorption voltage can be stopped when the voltage values of the first AC voltage and the second AC voltage become 0, the reliability of releasing adsorption can be improved.

[0017] When setting the period of the first waveform and the second waveform to 2π, the voltage application unit can apply the release adsorption voltage to the first electrode and the second electrode in such a way that the periods indicated by the first waveform and the second waveform at the start of applying the release adsorption voltage are 0 or more and less than 1 / 2π, and π or more and less than 3 / 2π. In this case, the time from the start of applying the release adsorption voltage until the positive and negative absolute values of the first AC voltage and the second AC voltage become the maximum values can be shortened. Therefore, the time from the start of releasing adsorption until the object to be held is separated from the holding portion can be more effectively shortened.

[0018] The voltage application unit can apply a release adsorption voltage to the first electrode and the second electrode in such a manner that the first waveform and the second waveform have the same amplitude. In this case, by making the first waveform and the second waveform have positive and negative symmetry, the charge removal efficiency of the holding unit by the first AC voltage and the second AC voltage can be improved.

[0019] When the voltage application unit switches the adsorption voltage used during the adsorption of the object to be held to the release adsorption voltage, it can reverse the polarity of the voltage applied to the first electrode and the polarity of the voltage applied to the second electrode. In this case, the charge removal of the holding unit can be started immediately after the release adsorption starts. Therefore, the time required to separate the object to be held from the holding part during release adsorption can be more effectively shortened.

[0020] An electrostatic adsorption device according to an aspect of the present invention includes the above-described power supply for the electrostatic adsorption device and a holding unit having a first electrode and a second electrode in an insulator.

[0021] During release adsorption, this electrostatic adsorption device stops applying the release adsorption voltage to the first electrode and the second electrode based on the correlation information of the timing at which the waveform of the first AC voltage and the waveform of the second AC voltage cross. According to this configuration, without waiting for the first AC voltage and the second AC voltage to decay, the application of the release adsorption voltage to the first electrode and the second electrode can be actively stopped at a timing suitable for separating the object to be held. Therefore, this electrostatic adsorption device can shorten the time required to separate the object to be held from the holding part during release adsorption.

[0022] A release adsorption control method according to an aspect of the present invention includes: an application step of the release adsorption voltage, which applies a first AC voltage to the first electrode with a first waveform and applies a second AC voltage to the second electrode with a second waveform having a phase difference from the first waveform; an information output step, which outputs the correlation information of the timing at which the first waveform and the second waveform cross; and a stop step, which stops the application of the release adsorption voltage to the first electrode and the second electrode based on the information output by the information output step.

[0023] During release adsorption, this release adsorption control method stops applying the release adsorption voltage to the first electrode and the second electrode based on the correlation information of the timing at which the waveform of the first AC voltage and the waveform of the second AC voltage cross. Thereby, without waiting for the first AC voltage and the second AC voltage to decay, the application of the release adsorption voltage to the first electrode and the second electrode can be actively stopped at a timing suitable for separating the object to be held. Therefore, this electrostatic adsorption device can shorten the time required to separate the object to be held from the holding part during release adsorption.

[0024] In the information output step, information obtained by detecting the first AC voltage and the second AC voltage can be output. In this case, the information can be output appropriately, and the application of the detachment adsorption voltage can be stopped at a timing suitable for separating the object to be held. Therefore, the time from the start of detachment adsorption until the object to be held is separated from the holding part can be shortened.

[0025] In the information output step, information pre-stored based on the first AC voltage and the second AC voltage can be output. In this case, the information can be output appropriately, and the application of the detachment adsorption voltage can be stopped at a timing suitable for separating the object to be held. Therefore, the time from the start of detachment adsorption until the object to be held is separated from the holding part can be shortened.

[0026] In the application step, the detachment adsorption voltage can be applied to the first electrode and the second electrode in such a way that the first waveform and the second waveform are opposite in phase. In this case, since positive and negative potentials are alternately applied to the first electrode and the second electrode, the charge removal efficiency of the holding part by the first AC voltage and the second AC voltage can be improved.

[0027] In the application step, the detachment adsorption voltage can be applied to the first electrode and the second electrode in such a way that the values of the first AC voltage and the second AC voltage are both 0 when the first waveform and the second waveform cross. In this case, since the application of the detachment adsorption voltage can be stopped when the voltage values of the first AC voltage and the second AC voltage are 0, the reliability of detachment adsorption can be improved.

[0028] In the application step, when the period of the first waveform and the second waveform is set to 2π, the detachment adsorption voltage can be applied to the first electrode and the second electrode in such a way that the periods indicated by the first waveform and the second waveform at the start of the application of the detachment adsorption voltage are 0 or more and less than 1 / 2π, and π or more and less than 3 / 2π. In this case, the time after the start of the application of the detachment adsorption voltage until the absolute values of the positive and negative of the first AC voltage and the second AC voltage become the maximum can be shortened. Therefore, the time from the start of detachment adsorption until the object to be held is separated from the holding part can be more effectively shortened.

[0029] In the application step, the detachment adsorption voltage can be applied to the first electrode and the second electrode in such a way that the first waveform and the second waveform have the same amplitude. In this case, by making the first waveform and the second waveform have positive and negative symmetry, the charge removal efficiency of the holding part by the first AC voltage and the second AC voltage can be improved.

[0030] In the application step, when switching from the adsorption voltage to the detachment adsorption voltage, the polarity of the voltage applied to the first electrode can be reversed from the polarity of the voltage applied to the second electrode. In this case, the charge removal of the holding part can be started immediately after the start of detachment adsorption. Therefore, the time from the start of detachment adsorption until the object to be held is separated from the holding part can be more effectively shortened.

[0031] Effect of the Invention

[0032] According to the present invention, the time from when the object to be held starts to be separated from the holding part until it is completely separated during the release of adsorption can be shortened. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 FIG. is a schematic cross-sectional view showing an embodiment of an electrostatic adsorption device.

[0034] Figure 2 FIG. is a circuit diagram showing a structural example of a voltage application unit.

[0035] Figure 3 FIG. is a diagram showing an example of various signals and output voltages used in the voltage application unit.

[0036] Figure 4 FIG. is a diagram showing an example of control of adsorption voltage and release adsorption voltage performed by the voltage application unit.

[0037] Figure 5 FIG. is a flowchart showing the operation of the electrostatic adsorption device.

[0038] Figure 6 FIG. is a diagram showing the verification result of the release adsorption condition of the object to be held.

[0039] Figure 7 FIG. is a circuit diagram showing a modified example of the voltage application unit. DETAILED DESCRIPTION OF THE INVENTION

[0040] Hereinafter, a preferred embodiment of a power supply for an electrostatic adsorption device, an electrostatic adsorption device, and a release adsorption control method according to an aspect of the present invention will be described in detail with reference to the accompanying drawings.

[0041] Figure 1 FIG. is a schematic cross-sectional view showing an embodiment of the electrostatic adsorption device 1. Figure 1 The illustrated electrostatic adsorption device 1 is a bipolar electrostatic adsorption device capable of switching between holding and non-holding of the object to be held K. The electrostatic adsorption device 1 is a device that holds the object to be held K by electrostatic force. The electrostatic adsorption device 1 can be applied to the transfer / processing of various objects to be held K such as silicon wafers or IC lead frames in a vacuum environment where it is difficult to perform adsorption by air. The structure of the electrostatic adsorption device 1 includes a holding part 2 and a power supply P for the electrostatic adsorption device (see Figure 2 ).

[0042] The holding part 2 includes an insulator 4, a first electrode 5, and a second electrode 6. The insulator 4 is formed in a plate shape from an insulating material such as ceramic or polyimide, for example. One side of the insulator 4 is a holding surface 2a of the holding part 2 for the object to be held K.

[0043] Both the first electrode 5 and the second electrode 6 are formed of a conductive material. The first electrode 5 and the second electrode 6 include a base portion extending in a trunk shape, and a plurality of comb-shaped electrodes protruding from the base portion in a direction substantially perpendicular to the relative extension direction. Figure 1 Only the comb-shaped electrodes are shown, and the base portion is omitted. The first electrode 5 and the second electrode 6 are arranged in such a manner that their comb-shaped electrodes are spaced apart at a certain interval and mesh with each other alternately and parallelly. The first electrode 5 and the second electrode 6 are encapsulated in the insulator 4. In the present embodiment, the number of comb-shaped electrodes arranged in the first electrode 5 is the same as the number of comb-shaped electrodes arranged in the second electrode 6. Figure 1 A and B in Figure 2 correspond to A and B in, and the first electrode 5 and the second electrode 6 are electrically connected to the voltage application unit 3.

[0044] The power supply P for the electrostatic adsorption device includes a part for applying a voltage to the first electrode 5 and the second electrode 6, that is, the voltage application unit 3. In the present embodiment, the voltage application unit 3 applies an adsorption voltage used when adsorbing the object to be held K and a desorption voltage used when detaching the object to be held K from the adsorption. The voltage application unit for applying the adsorption voltage used when adsorbing the object to be held K and the voltage application unit for applying the desorption voltage used when detaching the object to be held K from the adsorption may be different individuals.

[0045] In the present embodiment, the adsorption voltage is composed of a pair of DC voltages with positive and negative inversion, and the desorption voltage is composed of a pair of AC voltages with the same amplitude and opposite phases (refer to Figure 4 ). When the adsorption voltage is applied to the first electrode 5 and the second electrode 6, the holding surface 2a of the holding unit 2 becomes electrostatically charged, and the object to be held K is held by the holding surface 2a. When the desorption voltage is applied to the first electrode 5 and the second electrode 6, a voltage with positive and negative inversion is periodically applied to the first electrode 5 and the second electrode 6, and the static electricity is removed from the holding surface 2a of the holding unit 2. Thereafter, by stopping the application of the pair of AC voltages when their voltage values become 0 (become the ground voltage), the object to be held K can be separated from the holding surface 2a. The details will be described later.

[0046] Figure 2 is a circuit diagram showing a structural example of the voltage application unit 3. As shown in this figure, the voltage application unit 3 includes an AC power supply 21, a DC power supply 22, and a cross voltage adjustment unit 23. In addition, the voltage application unit 3 includes a comparator 24, a counter 25, a decoder 26, a first selector 27, a second selector 28, a first high-voltage amplifier 29, and a second high-voltage amplifier 30.

[0047] The AC power supply 21 is a single-phase power supply that outputs an AC voltage when detached from adsorption. The AC power supply 21 is connected to the comparator 24 and the first selector 27. The DC power supply 22 is a power supply that outputs a DC voltage when adsorbed. The DC power supply 22 is connected to the second selector 28. The cross voltage adjustment unit 23 is a DC power supply for adjusting the offset of the AC voltage when detached from adsorption. The cross voltage adjustment unit 23 is connected to the comparator 24, the first high-voltage amplifier 29, and the second high-voltage amplifier 30, respectively. The first high-voltage amplifier 29 is connected to the first electrode 5, and the second high-voltage amplifier 30 is connected to the second electrode 6.

[0048] The comparator 24 is a part that determines the positive and negative of the AC voltage input from the AC power supply 21. The comparator 24 compares the AC voltage output from the AC power supply 21 with the DC voltage from the cross voltage adjustment unit 23, and outputs an output signal corresponding to the period of the AC voltage to the counter 25. The counter 25 is a part that receives the input of the adsorption / detachment adsorption signal and measures the number of input times of the output signal from the comparator 24 during detachment from adsorption. The decoder 26 is a part that detects the number of times of polarity inversion of the AC voltage output from the AC power supply 21. When the number of times of polarity inversion reaches a preset number, the decoder 26 outputs an output signal indicating this to the first selector 27.

[0049] The comparator 24, the counter 25, and the decoder 26 constitute an information output unit 40 (to be described later), which outputs information related to the timing T at which the first waveform W1 of the first AC voltage Va1 and the second waveform W2 of the second AC voltage Va2 cross.

[0050] Based on the output signal from the decoder 26, the first selector 27 selectively inputs one of the AC power supply 21 and the ground voltage as the output voltage to the second selector 28. The second selector 28 receives the input of the adsorption / detachment adsorption signal, and selectively inputs the output voltage of one of the DC power supply 22 and the first selector 27 to the first high-voltage amplifier 29 and the second high-voltage amplifier 30. The first high-voltage amplifier 29 and the second high-voltage amplifier 30 amplify the input voltage from the second selector 28 and the cross voltage adjustment unit 23, and apply the amplified voltage to the first electrode 5 and the second electrode 6.

[0051] Figure 3 It is a diagram showing an example of various signals and output voltages used by the voltage application unit 3. The operation of the voltage application unit 3 is switched based on the adsorption / detachment adsorption signal input from the outside. The adsorption / detachment adsorption signal is as Figure 3As shown in (a), it is 0 during adsorption and 1 during desorption. That is, when the adsorption / desorption signal has a value of 0, it becomes an adsorption signal instructing the adsorption operation for the electrostatic adsorption device 1; when the value is 1 at time t0, it becomes a desorption signal instructing the desorption operation for the electrostatic adsorption device 1. The output voltage of the AC power supply 21 is as Figure 3 shown in (b), and becomes an AC voltage having a certain frequency and amplitude during both adsorption and desorption.

[0052] The output signal of the comparator 24 is as Figure 3 shown in (c), and is 1 during the period when the output voltage of the AC power supply 21 is positive (including 0), and is 0 during the negative period. The output signal of the decoder 26 is as Figure 3 shown in (d), and during desorption, after reaching the number of times of the preset polarity inversion of the AC voltage after time t1, it is 1 until the next adsorption signal arrives. The output signal of the decoder 26 is 0 during other periods.

[0053] The output signal of the second selector 28 is as Figure 3 shown in (e), and during adsorption, it takes a certain positive value; during desorption, it becomes an AC signal having the same waveform as the output voltage of the AC power supply 21. The output signal of the second selector 28 is 0 during the period when the output signal of the decoder 26 is 1 during desorption.

[0054] The output voltage of the first high-voltage amplifier 29 is the voltage applied to the first electrode 5. The output voltage of the first high-voltage amplifier 29 is as Figure 3 shown in (f), and is a positive DC voltage during adsorption, and during desorption at time t0, it is an AC voltage corresponding to the output signal of the second selector 28 (the first AC voltage Va1 described later). The output voltage of the second high-voltage amplifier 30 is the voltage applied to the second electrode 6. The output voltage of the second high-voltage amplifier is as Figure 3 shown in (g), and is a negative DC voltage during adsorption, and during desorption at time t0, it is an AC voltage with the positive and negative of the output signal of the second selector 28 reversed (the second AC voltage Va2 described later). Each of the output voltage of the first high-voltage amplifier 29 and the output voltage of the second high-voltage amplifier 30 is 0 during the period when the output signal of the decoder 26 is 1 during desorption at time t1.

[0055] Figure 4 It is a diagram showing an example of the control of the adsorption voltage and the desorption voltage by the voltage application unit 3. Figure 4 For easy understanding conceptually, compared with Figure 3Differently, the values of the output voltage of the first high-voltage amplifier 29 (the voltage applied to the first electrode 5) and the output voltage of the second high-voltage amplifier 30 (the voltage applied to the second electrode 6) at time t0 are both set to 0. As shown in this figure, during adsorption, a first DC voltage Vd1 is applied to the first electrode 5, and a second DC voltage Vd2 is applied to the second electrode 6. Here, the first DC voltage Vd1 is a positive voltage, and the second DC voltage Vd2 is a negative voltage. The polarities of the first DC voltage Vd1 and the second DC voltage Vd2 are different from each other. On the other hand, the absolute values of the voltages are equal. When switching from adsorption to desorption (switching from the adsorption signal to the desorption signal) at time t0, the voltages applied to the first electrode 5 and the second electrode 6 are switched from DC voltages to AC voltages.

[0056] During desorption, a first AC voltage Va1 is applied to the first electrode 5, and a second AC voltage Va2 is applied to the second electrode 6. In the present embodiment, the first waveform W1 shown by the first AC voltage Va1 and the second waveform W2 shown by the second AC voltage Va2 have the same amplitude and opposite phases to each other. The potential at the time when the first waveform W1 and the second waveform W2 cross is adjusted by the offset amounts of the first AC voltage Va1 and the second AC voltage Va2. Here, when the first waveform W1 and the second waveform W2 cross, the offset amounts of the first AC voltage Va1 and the second AC voltage Va2 are adjusted so that the voltage values of the first AC voltage Va1 and the second AC voltage Va2 become 0.

[0057] When one cycle of the first AC voltage Va1 and the second AC voltage Va2 is set to 2π, the periods shown by the first waveform W1 and the second waveform W2 at time t0 when starting to apply the desorption voltage are 0 or more and less than 1 / 2π, and π or more and less than 3 / 2π. Figure 4 In the example of, at time t0, the period shown by the first waveform W1 is π, and the period shown by the second waveform W2 is 0. Therefore, when switching from adsorption to desorption, that is, at time t0, the polarities of the voltage applied to the first electrode 5 and the voltage applied to the second electrode 6 are respectively reversed. The positive and negative absolute values of the first AC voltage Va1 and the second AC voltage Va2 are 0 at time t0. This absolute value gradually increases after time t0 and reaches the first peak after passing the time corresponding to 1 / 2π. Therefore, when starting to apply the desorption voltage, compared with the case where the periods shown by the first waveform W1 and the second waveform W2 at time t0 are 1 / 2π or more and less than π and 3 / 2π or more and less than 2π, the time for the positive and negative absolute values of the first AC voltage Va1 and the second AC voltage Va2 to reach the first peak is shortened.

[0058] After applying the desorption voltage, at the timing T when the first waveform W1 intersects with the second waveform W2, the application of the desorption voltage to the first electrode 5 and the second electrode 6 is stopped. Specifically, the information output unit 40 outputs a desorption voltage application stop signal Dt to the first selector 27 based on the timing signal Ts of the related information of the timing T when the first waveform W1 intersects with the second waveform W2. The first selector 27 receives the desorption voltage application stop signal Dt and inputs the ground voltage to the second selector 28. In addition, the second selector 28 receives the input of the desorption signal and inputs the ground voltage of the first selector 27 to the first high-voltage amplifier 29 and the second high-voltage amplifier 30. Thereby, the application of the desorption voltage to the first electrode 5 and the second electrode 6 is stopped (refer to Figure 2 ).

[0059] Figure 4 In the example of

[0060] , when the first waveform W1 and the second waveform W2 first intersect at time t0, the information output unit 40 obtains the timing signal Ts1 related to the timing T1. When the first waveform W1 and the second waveform W2 intersect for the second time after time t0, the information output unit 40 obtains the timing signal Ts2 related to the timing T2. When the first waveform W1 and the second waveform W2 intersect for the third time after time t0, the information output unit 40 obtains the timing signal Ts3 related to the timing T3. When the first waveform W1 and the second waveform W2 intersect for the fourth time at time t1, the information output unit 40 obtains the timing signal Ts4 related to the timing T4. The information output unit 40 receives the timing signal Ts4 and outputs the desorption voltage application stop signal Dt. Thereby, the application of the desorption voltage to the first electrode 5 and the second electrode 6 is stopped.

[0060] In the present embodiment, the first AC voltage Va1 and the second AC voltage Va2 are always controlled to be output in a desired state. Therefore, even without detecting the actual AC voltage, the related information of the timing T when the first waveform W1 intersects with the second waveform W2 can be output as the timing signal Ts from the comparator 24 of the information output unit 40. That is, the timing of the positive / negative determination of the AC voltage output from the AC power supply 21 (polarity inversion) is equal to the timing T when the first waveform W1 intersects with the second waveform W2. Therefore, the output signal of the comparator 24 is the timing signal Ts. The counter 25 receives the input of the desorption signal, measures the number of inputs of the timing signal Ts from the comparator 24 after the start of desorption, and outputs the measurement result to the decoder 26. The decoder 26 outputs the desorption voltage application stop signal Dt to the first selector 27 when the number of the timing signal Ts synchronized with the number of polarity inversions reaches the number preset in the decoder 26.

[0061] Regarding at which timing T when the first waveform W1 intersects with the second waveform W2 to stop applying the desorption electrode, it is appropriately determined according to, for example, the type of the object K to be held or the holding portion 2, the voltage value of the adsorption electrode, the amplitude / frequency of the desorption electrode, etc. In the case of the timing to stop applying the desorption voltage, that is, the timing to adjust the output of the desorption voltage application stop signal Dt by the information output unit 40, the number of intersections (the set number of times of the decoder 26) between the first waveform W1 and the second waveform W2 can be changed. By changing the voltage value, amplitude, or frequency of the first AC voltage Va1 and the second AC voltage Va2, the desorption conditions can also be adjusted. In this case, for example, the desorption conditions can be adjusted by changing the amplitude or frequency of the AC power supply 21.

[0062] Next, the operation of the above-described electrostatic adsorption device 1 will be described. Figure 5 It is a flowchart showing the operation of the electrostatic adsorption device 1.

[0063] As Figure 5 shown, in the electrostatic adsorption device 1, first, the adsorption conditions and the desorption conditions are set (step S01). In step S01, for example, the voltage values of the first DC voltage Vd1 and the second DC voltage Vd2 used during adsorption, the waveforms, frequencies, amplitudes, offsets of the first AC voltage Va1 and the second AC voltage Va2 used during desorption, and the timing to stop the desorption voltage are set.

[0064] After setting the adsorption conditions and the desorption conditions, it is determined whether an adsorption signal is input (step S02). In the case where an adsorption signal is not input, the determination in step S02 is repeated until an adsorption signal is input. In the case where an adsorption signal is input, an adsorption voltage (the first DC voltage Vd1 and the second DC voltage Vd2) is applied to the first electrode 5 and the second electrode 6 (step S03). By applying the adsorption voltage to the first electrode 5 and the second electrode 6, the holding surface 2a of the holding portion 2 is electrostatically charged, and the object K to be held is held by the holding surface 2a. Various processes such as conveying and processing are performed on the object K held on the holding surface 2a.

[0065] After applying the adsorption voltage, it is determined whether a desorption signal has been input (step S04). In the case where a desorption signal is not input, the object K is continuously held by the holding surface 2a, and the determination in step S04 is repeated until a desorption signal is input. In the case where a desorption signal has been input, a desorption voltage (the first AC voltage Va1 and the second AC voltage Va2) is applied to the first electrode 5 and the second electrode 6 (step S05). By applying the desorption voltage, a voltage that is periodically reversed in positive and negative is applied to the first electrode 5 and the second electrode 6, and the static electricity is removed from the holding surface 2a of the holding portion 2.

[0066] After starting to apply the detachment adsorption voltage, it is determined whether the timing for stopping the detachment adsorption voltage set in step S01 is reached (step S06). In the case where the set timing is not reached, the detachment adsorption voltage is continuously applied, and the determination in step S06 is repeatedly performed until the timing is reached. If the set timing has been reached, the application of the detachment adsorption voltage is stopped at the timing when the waveform of the first AC voltage Va1 intersects with the waveform of the second AC (step S07). By stopping the application of the first AC voltage Va1 and the second AC voltage Va2 when the voltage values of the first AC voltage Va1 and the second AC voltage Va2 become the ground voltage, the object to be held K can be separated from the holding surface 2a.

[0067] As described above, in the electrostatic adsorption device 1, during detachment adsorption, based on the information related to the timing when the first waveform W1 intersects with the second waveform W2, the application of the detachment adsorption voltage to the first electrode 5 and the second electrode 6 is stopped. According to this structure, without waiting for the first AC voltage Va1 and the second AC voltage Va2 to decay, the application of the detachment adsorption voltage to the first electrode 5 and the second electrode 6 can be actively stopped at the timing suitable for separating the object to be held K. Therefore, the electrostatic adsorption device 1 can shorten the time until the object to be held K is separated from the holding portion 2 during detachment adsorption.

[0068] In the present embodiment, the information output unit 40 pre - holds information based on the first AC voltage Va1 and the second AC voltage Va2. Thus, the information output unit 40 can appropriately output information, and further, the application of the detachment adsorption voltage can be stopped at the timing suitable for separating the object to be held K. Therefore, the time until the object to be held K is separated from the holding portion 2 during detachment adsorption can be shortened.

[0069] In the present embodiment, the voltage application unit 3 applies the detachment adsorption voltage to the first electrode 5 and the second electrode 6 such that the first waveform W1 and the second waveform W2 are in opposite phases. Therefore, since positive and negative potentials are alternately applied to the first electrode 5 and the second electrode 6, the charge removal efficiency of the holding portion 2 by the first AC voltage Va1 and the second AC voltage Va2 can be improved.

[0070] In the present embodiment, the voltage application unit 3 applies the detachment adsorption voltage to the first electrode 5 and the second electrode 6 such that the values of the first AC voltage Va1 and the second AC voltage Va2 both become 0 when the first waveform W1 intersects with the second waveform W2. Therefore, since the application of the detachment adsorption voltage can be stopped when the voltage values of the first AC voltage Va1 and the second AC voltage Va2 become 0, the reliability of detachment adsorption can be improved.

[0071] In the present embodiment, when the period of the first waveform W1 and the second waveform W2 is set to 2π, the voltage application unit 3 applies a desorption voltage to the first electrode 5 and the second electrode 6 such that the periods indicated by the first waveform W1 and the second waveform W2 at the start of the application of the desorption voltage are 0 or more and less than 1 / 2π, and π or more and less than 3 / 2π. Therefore, the time when the positive and negative absolute values of the first AC voltage Va1 and the second AC voltage Va2 become the maximum after the start of the application of the desorption voltage can be shortened. Therefore, the time until the object K to be held is separated from the holding unit 2 during desorption can be more effectively shortened.

[0072] In the present embodiment, the voltage application unit 3 applies a desorption voltage to the first electrode 5 and the second electrode 6 such that the first waveform W1 and the second waveform W2 have the same amplitude. Therefore, by making the first waveform W1 and the second waveform W2 have positive and negative symmetry, the charge removal efficiency of the holding unit 2 by the first AC voltage Va1 and the second AC voltage Va2 can be improved.

[0073] In the present embodiment, when the adsorption voltage used when adsorbing the object K to be held is switched to the desorption voltage, the voltage application unit 3 reverses the polarity of the voltage applied to the first electrode 5 and the polarity of the voltage applied to the second electrode 6. Thereby, charge removal from the holding unit 2 can be started immediately after the start of desorption. Therefore, the time until the object K to be held is separated from the holding unit 2 during desorption can be more effectively shortened.

[0074] Figure 6 It is a diagram showing the verification results of the desorption conditions of the object K to be held. In this verification test, the frequencies and amplitudes of the first AC voltage Va1 and the second AC voltage Va2 are used as parameters. And, with the object K to be held in a state of being held on the holding surface 2a facing vertically downward, a desorption voltage is applied to the first electrode 5 and the second electrode 6, and the condition for the shortest time (desorption time) from the application of the desorption voltage until the object K to be held falls from the holding surface 2a is obtained. Four types of objects K to be held are used: a copper frame, paper, glass, and a copper plate. The adsorption voltage is set to ±1200V.

[0075] Figure 6 As shown in the results, for the copper frame, the desorption time is the shortest when the frequencies of the first AC voltage Va1 and the second AC voltage Va2 are 1 Hz and the amplitude is 500 V. For paper, the desorption time is the shortest when the frequencies of the first AC voltage Va1 and the second AC voltage Va2 are 1 Hz and the amplitude is 250 V. For glass and the copper plate, the desorption time is the shortest when the frequencies of the first AC voltage Va1 and the second AC voltage Va2 are 0.1 Hz and the amplitude is 500 V. For any object K to be held, the desorption time is about 1 second.

[0076] The present invention is not limited to the above-described embodiments. In the above-described embodiments, the timing signal Ts is obtained by determining the positive and negative of the AC voltage output from the AC power supply 21 using the comparator 24. However, as Figure 7 shown, by using the detection unit 50 that directly detects the first AC voltage Va1 and the second AC voltage Va2 to detect the timing T at which the first waveform W1 and the second waveform W2 cross, the timing signal Ts can also be obtained. Specifically, in the comparator 32 that constitutes the detection unit 50, the timing at which the value of the first AC voltage Va1 becomes equal to the value of the second AC voltage Va2, that is, the timing T at which the first waveform and the second waveform W2 cross, can be detected and input to the third selector 33 as the detection signal Ds.

[0077] In this case, the third selector 33 also receives the Figure 2 signal described above from the comparator 24. The third selector 33 selects one of the signals input from the comparator 32 and the comparator 24, and outputs the corresponding timing signal Ts to the counter 25.

[0078] In addition, the third selector 33 may also receive an input of a detection unit use signal or a detection unit non-use signal, which is a signal indicating whether to use the detection unit 50. When the detection unit 50 is used, the third selector 33 receives an input of the detection unit use signal, selects the detection signal Ds input from the comparator 32, and outputs the timing signal Ts based on the detection signal Ds to the counter 25. When the detection unit 50 is not used, the third selector 33 receives an input of the detection unit non-use signal, selects the signal input from the comparator 24, and outputs the corresponding timing signal Ts to the counter 25. It may also be configured to stabilize the characteristics of the AC power supply 21 by adjusting the output of the AC power supply 21 using the detection information of the detection unit 50.

[0079] According to this method, the information output unit 40 obtains the timing signal Ts by detecting the first AC voltage Va1 and the second AC voltage Va2. Thus, the information output unit 40 can appropriately output the separation adsorption voltage application stop signal Dt, and can stop applying the separation adsorption voltage at the timing T suitable for separating the object to be held K. Therefore, the time until the object to be held K is separated from the holding unit 2 during separation adsorption can be shortened. In addition, by directly detecting the first AC voltage Va1 and the second AC voltage Va2, a preferable timing T can be obtained even in the case where, for example, the AC power supply 21 is particularly unstable.

[0080] In the above-described embodiment, the number of comb-shaped electrodes of the first electrode 5 in the insulator 4 is the same as the number of comb-shaped electrodes of the second electrode 6. However, these numbers of arrangements may also be different. The first electrode 5 and the second electrode 6 in the insulator 4 do not necessarily have a structure with comb-shaped electrodes, and the areas of the first electrode 5 and the second electrode 6 may be different when viewed from the normal direction of the holding surface 2a. In such a case, the first AC voltage Va1 and the second AC voltage Va2 used for releasing adsorption may be shifted from a state where their phases are opposite, or their amplitudes or frequencies may be different from each other. When releasing adsorption, the voltage value may be shifted to either positive or negative with respect to the voltage value being 0 when the waveforms of the first AC voltage Va1 and the second AC voltage Va2 cross each other.

[0081]

Reference Signs

[0082] 1... Electrostatic chucking device; 2... Holding part; 2a... Holding surface; 3... Voltage application part; 4... Insulator; 5... First electrode; 6... Second electrode; K... Object to be held; P... Power supply for electrostatic chucking device; Ts... Timing signal (information); Vd1... First DC voltage (adsorption voltage); Vd2... Second DC voltage (adsorption voltage); Va1... First AC voltage (release adsorption voltage); Va2... Second AC voltage (release adsorption voltage).

Claims

1. A power supply for an electrostatic adsorption device, wherein: It includes a voltage application unit that applies a desorption voltage used when the object to be held is desorbed from adsorption to the first electrode and the second electrode. The desorption voltage is composed of a first AC voltage applied to the first electrode in a first waveform and a second AC voltage applied to the second electrode in a second waveform having a phase difference from the first waveform. The power supply for the electrostatic adsorption device has an information output unit that outputs correlation information on the timing when the first waveform and the second waveform cross. Based on the information, the voltage application unit stops applying the desorption voltage to the first electrode and the second electrode.

2. The power supply for the electrostatic adsorption device according to claim 1, wherein: The information output unit obtains the information by detecting the first AC voltage and the second AC voltage.

3. The power supply for the electrostatic adsorption device according to claim 1, wherein: The information output unit pre-stores the information based on the first AC voltage and the second AC voltage.

4. The power supply for the electrostatic adsorption device according to claim 1, wherein: The voltage application unit applies the desorption voltage to the first electrode and the second electrode in such a way that the first waveform and the second waveform have opposite phases.

5. The power supply for the electrostatic adsorption device according to claim 2, wherein: The voltage application unit applies the desorption voltage to the first electrode and the second electrode in such a way that the first waveform and the second waveform have opposite phases.

6. The power supply for the electrostatic adsorption device according to claim 3, wherein: The voltage application unit applies the desorption voltage to the first electrode and the second electrode in such a way that the first waveform and the second waveform have opposite phases.

7. The power supply for the electrostatic adsorption device according to claim 4, wherein: The voltage application unit applies the desorption voltage to the first electrode and the second electrode in such a way that when the first waveform and the second waveform cross, the values of the first AC voltage and the second AC voltage both become 0.

8. The power supply for the electrostatic adsorption device according to claim 5, wherein: The voltage application unit applies the desorption voltage to the first electrode and the second electrode in such a way that when the first waveform and the second waveform cross, the values of the first AC voltage and the second AC voltage both become 0.

9. The power supply for the electrostatic adsorption device according to claim 6, wherein: The voltage application unit applies the desorption voltage to the first electrode and the second electrode in such a way that when the first waveform and the second waveform cross, the values of the first AC voltage and the second AC voltage both become 0.

10. The power supply for the electrostatic adsorption device according to claim 7, wherein: When the period of each of the first waveform and the second waveform is set to 2π, the voltage application unit applies the detachment adsorption voltage to the first electrode and the second electrode such that the periods indicated by the first waveform and the second waveform at the start of the application of the detachment adsorption voltage are 0 or more and less than 1 / 2π, and π or more and less than 3 / 2π.

11. The power supply for an electrostatic adsorption device according to claim 8, wherein When the period of each of the first waveform and the second waveform is set to 2π, the voltage application unit applies the detachment adsorption voltage to the first electrode and the second electrode such that the periods indicated by the first waveform and the second waveform at the start of the application of the detachment adsorption voltage are 0 or more and less than 1 / 2π, and π or more and less than 3 / 2π.

12. The power supply for an electrostatic adsorption device according to claim 9, wherein When the period of each of the first waveform and the second waveform is set to 2π, the voltage application unit applies the detachment adsorption voltage to the first electrode and the second electrode such that the periods indicated by the first waveform and the second waveform at the start of the application of the detachment adsorption voltage are 0 or more and less than 1 / 2π, and π or more and less than 3 / 2π.

13. The power supply for an electrostatic adsorption device according to any one of claims 1 to 12, wherein The voltage application unit applies the detachment adsorption voltage to the first electrode and the second electrode such that the first waveform and the second waveform have the same amplitude.

14. The power supply for an electrostatic adsorption device according to any one of claims 1 to 12, wherein When switching from the adsorption voltage used during adsorption of the object to be held to the detachment adsorption voltage, the voltage application unit reverses the polarity of the voltage applied to the first electrode and the polarity of the voltage applied to the second electrode.

15. The power supply for an electrostatic adsorption device according to claim 13, wherein When switching from the adsorption voltage used during adsorption of the object to be held to the detachment adsorption voltage, the voltage application unit reverses the polarity of the voltage applied to the first electrode and the polarity of the voltage applied to the second electrode.

16. An electrostatic adsorption device, wherein Comprises: The power supply for an electrostatic adsorption device according to any one of claims 1 to 15; and A holding unit having the first electrode and the second electrode in an insulator.

17. A detachment adsorption control method, wherein Comprises: A step of applying a detachment adsorption voltage, which applies a first AC voltage to a first electrode with a first waveform and applies a second AC voltage with a second waveform having a phase difference from the first waveform to a second electrode; An information output step, which outputs information related to the timing at which the first waveform and the second waveform cross; And A stop step, which stops the application of the detachment adsorption voltage to the first electrode and the second electrode based on the information output by the information output step.

18. The detachment adsorption control method according to claim 17, wherein, In the information output step, the information obtained by detecting the first AC voltage and the second AC voltage is output.

19. The detachment adsorption control method according to claim 17, wherein, in the information output step, the information pre-stored based on the first AC voltage and the second AC voltage is output.

20. The detachment adsorption control method according to claim 17, wherein, in the application step, the detachment adsorption voltage is applied to the first electrode and the second electrode in such a manner that the first waveform and the second waveform are in opposite phases.

21. The detachment adsorption control method according to claim 18, wherein, in the application step, the detachment adsorption voltage is applied to the first electrode and the second electrode in such a manner that the first waveform and the second waveform are in opposite phases.

22. The detachment adsorption control method according to claim 19, wherein, in the application step, the detachment adsorption voltage is applied to the first electrode and the second electrode in such a manner that the first waveform and the second waveform are in opposite phases.

23. The detachment adsorption control method according to claim 20, wherein, in the application step, the detachment adsorption voltage is applied to the first electrode and the second electrode in such a manner that when the first waveform and the second waveform cross, the values of the first AC voltage and the second AC voltage both become 0.

24. The detachment adsorption control method according to claim 21, wherein, in the application step, the detachment adsorption voltage is applied to the first electrode and the second electrode in such a manner that when the first waveform and the second waveform cross, the values of the first AC voltage and the second AC voltage both become 0.

25. The detachment adsorption control method according to claim 22, wherein, in the application step, the detachment adsorption voltage is applied to the first electrode and the second electrode in such a manner that when the first waveform and the second waveform cross, the values of the first AC voltage and the second AC voltage both become 0.

26. The detachment adsorption control method according to claim 23, wherein, in the application step, when one cycle of the first waveform and the second waveform is set to 2π, the detachment adsorption voltage is applied to the first electrode and the second electrode in such a manner that the cycles indicated by the first waveform and the second waveform at the start of the application of the detachment adsorption voltage are 0 or more and less than 1 / 2π, and π or more and less than 3 / 2π.

27. The detachment adsorption control method according to claim 24, wherein, in the application step, when one cycle of the first waveform and the second waveform is set to 2π, the detachment adsorption voltage is applied to the first electrode and the second electrode in such a manner that the cycles indicated by the first waveform and the second waveform at the start of the application of the detachment adsorption voltage are 0 or more and less than 1 / 2π, and π or more and less than 3 / 2π.

28. The detachment adsorption control method according to claim 25, wherein, In the application step, when one cycle of the first waveform and the second waveform is set to 2π, the detachment adsorption voltage is applied to the first electrode and the second electrode in such a manner that the periods indicated by the first waveform and the second waveform at the start of the application of the detachment adsorption voltage are 0 or more and less than 1 / 2π, and π or more and less than 3 / 2π.

29. The detachment adsorption control method according to any one of claims 17 to 28, wherein in the application step, the detachment adsorption voltage is applied to the first electrode and the second electrode in such a manner that the first waveform and the second waveform have the same amplitude as each other.

30. The detachment adsorption control method according to any one of claims 17 to 28, wherein in the application step, when switching from the adsorption voltage to the detachment adsorption voltage, the polarity of the voltage applied to the first electrode is reversed from the polarity of the voltage applied to the second electrode.

31. The detachment adsorption control method according to claim 29, wherein in the application step, when switching from the adsorption voltage to the detachment adsorption voltage, the polarity of the voltage applied to the first electrode is reversed from the polarity of the voltage applied to the second electrode.

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