TW201834132A - Electrostatic chuck device and electrostatic adsorption method which can electrostatically adsorb an object to be held under an atmospheric pressure environment - Google Patents

Abstract

An object of the present invention is related to an electrostatic adsorption of an object to be held, such as semiconductors, insulators or others, even under an atmospheric pressure environment. The present invention provides an electrostatic chuck device that electrostatically adsorbs an object to be held under an atmospheric pressure environment. The electrostatic chuck device comprises an electrostatic chuck table including an electrode and a holding surface, and an ionized air supply unit for supplying the ionized air to an exposed surface of the object held by the holding surface, wherein the electrode has a function in that an electric charge is supplied when the object to be held is electrostatically adsorbed, and the ionized air supply unit has charged ions with a polarity opposite to a polarity of a charge supplied to the electrode to be supplied to the exposed surface of the object to be held and maintains the charge on the exposed surface side of the object to be held. The object to be held can be provided with a protective member on one surface thereof, and the object to be held can be electrostatically adsorbed to the holding surface via the protective member at the buildup area. The electrostatic adsorption method of the present invention comprises the steps of holding the object to be held on the holding surface of the electrostatic chuck table having the electrode and the holding surface, supplying charge to the electrode for generating a suction control of electrostatic attraction force, and supplying an ionized air with a polar charge opposite to the polarity of the charge supplying and supplied to the electrode to the exposed surface of the object to be held for maintaining the charge on the exposed surface of the object to be held and assisting the suction control of electrostatic attraction force.

Description

Electrostatic chuck device and electrostatic adsorption method

[0001] The present invention relates to an electrostatic chuck device and an electrostatic adsorption method.

[0002] Processing devices such as plasma etching devices that hold objects to be held such as semiconductor wafers for processing are electrostatic chuck devices having an electrostatic chuck table such as an electrostatic chuck table that electrostatically adsorbs the objects to be held. The electrostatic chuck device is fixed for processing. [0003] An electrostatic chuck device includes an electrode and a dielectric (insulator) on the electrode. The object to be held is placed above the electrode with the dielectric interposed therebetween. After the electrode is set to a predetermined potential, an electrostatic field or static electricity is generated in the object by the electric field generated from the electrode. Divided. Then, the object to be held is fixed to the electrostatic chuck device by a charge or a coulomb force (electrostatic force) between the electrode and the electrode of the electrostatic chuck device. [0004] The electrostatic adsorption caused by Coulomb force is particularly strong when the object being held is a conductor with free electrons. On the other hand, although the object to be held is a semiconductor or an insulator, although electrostatic polarization is generated, the electrostatic attraction caused by the electrostatic polarization is relatively weak. Therefore, for example, when the electrodes of the electrostatic chuck device in the processing device are set to a predetermined low potential to hold the semiconductor and insulator to be held, the inside of the processing device is set to a vacuum to generate a plasma in the processing device. The slurry supplies cations to the substrate. [0005] Then, an electrostatic polarization is generated on the upper side of the object to be held. This polarization is constituted by an electric dipole having a negative charge disposed above and a positive charge disposed below. The electrostatic polarization on the lower side of the held object, which is generated when a low-potential DC voltage is supplied to the electrodes of the electrostatic chuck device, is also composed of an electric dipole having a negative charge disposed above and a positive charge disposed below. Therefore, the electrostatic polarization at the lower side is assisted by the electrostatic polarization at the upper side of the object to be held, and the electrostatic adsorption caused by the Coulomb force is enhanced. [0006] At this time, even if the power supply of the electrostatic chuck device to the electrode is stopped, the adsorption force is difficult to completely disappear. Therefore, when the object to be held is peeled off, it is necessary to generate a plasma after stopping the power supply. Surface) to supply electrons to eliminate the potential remaining in the object. However, in order to use the plasma, it is necessary to place the electrostatic chuck device in a vacuum environment, and the control of electrostatic adsorption by the plasma cannot be performed under an atmospheric pressure environment. [0007] Therefore, in order to maintain the semiconductor and insulator holding objects under atmospheric pressure, the shape of the electrodes of the electrostatic chuck device has been worked on, and the static electricity of the holding objects can be maintained by the gradient force. Suction device. In addition, an electrostatic chuck device has been developed that improves the flatness of the holding surface and maintains the suction power even after the power supply is stopped. [Prior Art Document] [Patent Document] [0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-51836

[Problems to be Solved by the Invention] 000 [0009] However, in the situation where the gradient force is used and the flatness of the holding surface is improved, in the case where the object to be held is not a conductor and the power supply to the electrode is not maintained, the electrostatic chuck device It is difficult to say that the adsorption force is sufficient. [0010] The present invention was conceived by the inventor in view of the related problems, and its object is to provide an electrostatic chuck device and an electrostatic adsorption method that can electrostatically adsorb a substrate such as a semiconductor and an insulator even in an atmospheric pressure environment. [Means to Solve the Problem] 1 [0011] According to the present invention, an electrostatic chuck device is provided, which is an electrostatic chuck device that electrostatically adsorbs an object to be held in an atmospheric pressure environment, which is characterized by having an electrostatic chuck table, which is provided with electrodes and A holding surface; and an ionized air supply unit for supplying ionized air to the exposed surface of the object to be held held by the holding surface; the electrode having a function of supplying a charge during electrostatic adsorption of the object to be held; The ionized air supply unit has a function of supplying ions having a charge of a polarity opposite to the polarity of the charge supplied to the electrode to the exposed surface of the object to maintain the charge on the exposed surface side of the object. . [0012] In the aspect of the present invention, the object to be held may be provided with a protective member on one side, and the object to be held may be electrostatically adsorbed to the holding surface via the protective member. [0013] Furthermore, according to another aspect of the present invention, an electrostatic adsorption method is provided, comprising: a step of placing an object to be held on the holding surface of an electrostatic chuck table having an electrode and a holding surface; A suction control step in which the electrode supplies electric charges to generate an electrostatic attractive force; and an exposed surface of the held object is supplied with ionized air having a polarity opposite to the polarity of the charges supplied to the electrode to maintain the held The charge of the exposed surface of the object is a suction assisting step that assists in controlling the electrostatic attractive force. [Effects of the Invention] [0014] The electrostatic chuck device of the present invention includes an electrostatic chuck table including an electrode and a holding surface, and an ionized air supply unit capable of supplying ionized air. When electrostatically holding the electrostatic chuck device to the object to be held, the holding surface of the electrostatic chuck table of the electrostatic chuck device is brought into contact with the object to be charged, and the electrodes of the electrostatic chuck table are charged. [0015] Then, by an electric field generated from the charge, a charge or the like having a polarity opposite to the polarity of the charge is induced to a surface side of the held object facing the holding surface. Alternatively, polarization is generated on the side of the surface facing the holding surface. The polarization is arranged on the holding surface side by a charge having a polarity opposite to the polarity of the charge on the electrode, and a charge having the same polarity as the polarity of the charge on the electrode is arranged on the opposite side of the holding surface. Make up. Then, the object to be held is fixed to the electrostatic chuck device by a charge or a coulomb force (electrostatic force) between the electrode and the electrode of the electrostatic chuck device. [0016] Furthermore, the electrostatic chuck device can supply ionized air from the ionized air supply unit to the exposed surface (the surface not facing the holding surface) of the object to be held. At this time, from the ionized air supply unit, ionized air having a polarity opposite to the polarity of the electric charge supplied to the electrode is supplied to the object. Then, a charge having a polarity opposite to that of the ionized air is excited on the exposed surface side of the object to be held. Alternatively, a divided pole composed of the same electric dipole as the electric dipole of the polarized side of the object to be held facing the side of the holding surface is generated. [0017] Therefore, on the surface side of the object to be held facing the holding surface, the polarities of the charges excited respectively on the exposed surface side are opposite. Alternatively, the surface side of the object to be held facing the holding surface coincides with the direction of the polarizations generated on the exposed surface side. Therefore, the charged state of the object to be held is enhanced by the electric charge supplied from the ionized air. That is, the ionized air supply unit assists electrostatic adsorption of the object by Coulomb force. [0018] When the electrostatic adsorption is released and the object to be held is peeled from the electrostatic chuck table, a charge having a polarity opposite to the electric charge supplied to the electrostatic chuck table during electrostatic adsorption is supplied to the electrode. [0019] At this time, the ionized air remaining on the exposed surface of the object to be held is maintained by the ionized air supplied from the ionized air supply unit, so the object to be held faces the surface of the holding surface. The polarity of the electric charge and the like will coincide with the polarity of the electric charge newly supplied to the electrode. Then, a force is generated in a direction in which the electrode and the held object repel each other, so the held object is easily peeled from the electrostatic chuck table. [0020] Therefore, according to the present invention, an electrostatic chuck device capable of electrostatically adsorbing a holding object such as a semiconductor and an insulator even under an atmospheric pressure environment, and a suction control method for the electrostatic chuck table are provided.

[0022] An embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 (A) is a perspective view schematically illustrating an example of an object to be electrostatically attracted by the electrostatic chuck device according to the embodiment. As shown in FIG. 1 (A), the object to be held which is electrostatically adsorbed by the electrostatic chuck device of this embodiment is, for example, a wafer 1 made of a semiconductor. [0023] This wafer 1 has a substantially circular plate shape, and devices 5 such as ICs or LSIs are formed in each area divided by a plurality of predetermined dividing lines 3 arranged in a grid pattern on the surface 1a. This wafer 1 is thinned by polishing from the back surface 1b side. When the wafer 1 is divided along the predetermined dividing line 3, each device wafer can be formed. [0024] However, the object to be electrostatically attracted by the electrostatic chuck device according to this embodiment is not limited to a wafer formed of a semiconductor, and a disc-shaped substrate formed of a conductor such as a metal or an insulator such as glass. Yes. In the electrostatic chuck device of this embodiment, the object to be held can be electrostatically adsorbed regardless of whether the object to be held is a conductor, an insulator, or a semiconductor. In addition, a protection member may be provided on one side of the object to be held such as the wafer 1. In this case, the object to be held is electrostatically attracted to the electrostatic chuck device via the protection member. [0025] Next, an electrostatic chuck device according to this embodiment will be described. FIG. 1 (B) is a perspective view schematically illustrating an electrostatic chuck device 2 according to this embodiment. As shown in FIG. 1 (B), the electrostatic chuck device 2 includes an electrostatic chuck table 4 and an ionized air supply unit 6 provided above the electrostatic chuck table 4. [0026] FIG. 2 (A) is a schematic cross-sectional view illustrating the electrostatic chuck device 2. The electrostatic chuck table 4 has a function of electrostatically adsorbing objects to be held such as the wafer 1 on the holding surface 4a placed on the upper surface. An electrode 4c and an insulator 4b surrounding the electrode 4c are provided on the holding surface 4a side of the electrostatic chuck table 4. The electrode 4c is electrically connected to a power source 4d, and the power source 4d has a function of supplying a positive or negative charge to the electrode 4c. [0027] The ionized air supply unit 6 is, for example, a static eliminator, and has a function of supplying positive or negatively charged ionized air to the holding surface 4a of the electrostatic chuck table 4. As shown in FIG. 1 (B), the ionized air supply unit 6 is located above the electrostatic chuck table 4, and has an ionized air supply head 6a, and a positive or negatively charged ionized air is supplied to the ionized air supply head 6a. Ionized air supply source 6b. [0028] Generally, when a static eliminator is used for the static elimination of a given object, it is used in a manner that generates approximately the same amount of positively charged ionized air and negatively charged ionized air. On the other hand, in the ionized air supply unit 6 such as the electrostatic eliminator of the electrostatic chuck device 2 of the present embodiment, either positively charged ionized air or negatively charged ionized air is generated and supplied to the electrostatic chuck table. on. [0029] The ionized air supply source 6b has, for example, a discharge needle connected to a high-voltage power supply. The ionized air supply source 6b is configured to capture air from the outside, apply an AC voltage or a DC voltage from the discharge needle, and perform a corona discharge to positively or negatively charge the air to generate ionized air. [0030] When the ionized air supply source 6b uses, for example, a discharge pin connected to an AC power source, the AC voltage is boosted to an amplitude greater than the AC voltage so that the minimum voltage of the AC voltage supplied to the discharge pin is positive. . Alternatively, in a manner that the highest voltage of the AC voltage is negative, the AC voltage is stepped down to an amplitude greater than the AC voltage. Then, either positively charged ionized air or negatively charged ionized air is generated. [0031] In the ionized air supply source 6b, when two discharge needles connected to the positive electrode side of the DC power supply and the discharge needle connected to the negative side of the DC power supply are used, only one discharge needle is supplied. DC voltage. Then, either positively charged ionized air or negatively charged ionized air is generated. [0032] The ionized air generated in the ionized air supply source 6b is supplied to the ionized air supply head 6a, and from the supply port 6c provided below the ionized air supply head 6a to the electrostatic chuck table 4 The holding surface 4a is released. [0033] Next, a method for electrostatically attracting an object to be held by the electrostatic chuck device of this embodiment will be described. FIG. 2 (B) is a cross-sectional view schematically showing a state where the electrostatic chuck device 2 electrostatically attracts the wafer 1. [0034] As shown in FIG. 2 (B), in this method, first, a mounting step of placing the wafer 1 on the holding surface 4a of the electrostatic chuck table 4 is performed. After the mounting step, a suction control step of supplying electric charges to the electrodes 4c of the electrostatic chuck table 4 to generate an electrostatic attractive force is performed. After the placing step, the exposed surface of the wafer 1 is supplied with ionized air 8 having a polarity opposite to the polarity of the charge supplied to the electrode 4 c to maintain the exposed surface of the wafer 1. The charge-assisted assisted step assists the control of electrostatic attraction. [0035] Each step of the method of electrostatically attracting the wafer 1 to the electrostatic chuck device 2 will be described in detail. In the mounting step, the wafer 1 is placed on the electrostatic chuck table 4 such that a surface on the side that is not an object of processing the wafer 1 contacts the holding surface 4 a. Then, the surface on the processing object side of the wafer 1 becomes an exposed surface, and a predetermined processing can be performed on the surface. [0036] Next, a suction control procedure will be described. In this attraction control step, an electric charge is supplied from the power source 4d to the electrode 4c of the electrostatic chuck table 4, and an electrostatic attraction force to the wafer 1 is generated. When the electrode 4c has a predetermined potential, an electrostatic induction or electrostatic polarization is generated in the wafer 1 by an electric field generated from the electrode 4c. Then, the wafer 1 is fixed to the electrostatic chuck table 4 by the Coulomb force (electrostatic force) between the electric charge or the poles in the wafer 1 and the electrostatic chuck table 4. [0037] However, the adsorption force of electrostatic adsorption due to Coulomb force becomes stronger when the wafer 1 is a conductor with free electrons, but it is weaker when the substrate is a semiconductor or an insulator. When the electric charge is supplied, the adsorption force is greatly reduced. Therefore, a suction assisting step is implemented. [0038] Next, a suction assisting step will be described. In this suction assisting step, the ionized air supply unit 6 supplies ionized air 8 having a polarity opposite to the electric charge supplied to the electrode 4 c to the exposed surface of the wafer 1. For example, when a positive charge is supplied to the electrode 4c, negatively charged ionized air 8 is discharged from the ionized air supply head 6a, and when a negative charge is supplied to the electrode 4c, positively charged air is discharged from the ionized air supply head 6a. Ionized air 8. [0039] FIG. 3 (A) is a cross-sectional view schematically illustrating electric charges and the like during electrostatic adsorption of an object to be held. The relationship between the charge of the electrode 4c, the charge of the wafer 1, and the like, and the respective polarities of the charge 10 due to ionized air are revealed in the mode of FIG. 3 (A). The color of the circle showing the charge and the like in FIG. 3 (A) shows the polarity of the charge and the like. Circles of the same color are charges of the same polarity. When the two circles have different colors, they represent charges of opposite polarities. In addition, the circle system of the wafer 1 is a model of electric deviation due to electrostatic induction or electrostatic polarization as a charge. [0040] When the polarity of the charge 12 supplied to the electrode 4c of the electrostatic chuck table 4 is positive, the polarity of the charge 10 caused by the ionized air is set to negative. Thus, in addition to the negative polarity of the charge 7b under the wafer generated by the electrode 4c, the polarity of the charge 7a on the wafer due to the charge 10 caused by ionized air is positive. Therefore, the charges 7a on the wafer and the charges 7b on the wafer have opposite polarities. [0041] Compared with the situation where the electric charge 7a on the wafer and the electric charge 7b on the wafer have the same polarity, in a situation of the opposite polarity, the electrostatic induction or electrostatic polarization is more likely to become stronger. In addition, even if the supply of the electric charge (voltage) to the electrode 4c is stopped, the electric charge or classification in the wafer 1 will not be dissipated by the electric charge 10 caused by the ionized air, and the Coulomb force will still act on the wafer 1. Therefore, the wafer 1 is continuously electrostatically attracted by the electrostatic chuck table 4. [0042] Next, a description will be given of a state where the electrostatic adsorption of the wafer 1 is released and the wafer 1 is peeled from the electrostatic chuck table 4. When the wafer 1 is peeled from the electrostatic chuck table 4, the electrode 4 c of the electrostatic chuck table 4 is supplied with a charge having a polarity opposite to the polarity of the charge supplied during the electrostatic attraction to the electrode 4 c. FIG. 3 (B) is a cross-sectional view schematically illustrating a state where the wafer 1 is peeled from the electrostatic chuck table 4. [0043] As shown in FIG. 3 (B), the charge or polarization in the wafer 1 is not dissipated by the charge 10 caused by the ionized air. For example, when the polarity of the charge 12 supplied to the electrode 4c during electrostatic attraction is positive, the polarity of the charge 7b under the wafer caused by the electrode 4c is negative. [0044] Then, a negative charge is supplied to the electrode 4c. Then, the electric charges 7b on the lower surface of the wafer and the electric charges 14 supplied to the electrodes 4c have the same polarity as each other. Therefore, a repulsive force is generated between the electrode 4c and the wafer 1, and the wafer 1 is easily peeled. [0045] As described above, since the electrostatic chuck device 2 of this embodiment includes the electrostatic chuck table 4 including the electrode 1c and the ionized air supply unit 6, it is easy to perform electrostatic adsorption and peeling of the wafer 1. At this time, since no plasma is used, the electrostatic chuck device 2 can electrostatically adsorb the wafer 1 even under an atmospheric pressure environment. [0046] The wafer 1 electrostatically attracted by the electrostatic chuck device 2 is subjected to a predetermined process. For example, when the electrostatic chuck device 2 is incorporated into a grinding device for grinding the wafer 1, the wafer 1 is subjected to a grinding process. When the electrostatic chuck device 2 is incorporated into a cutting device for cutting the wafer 1, the wafer 1 is subjected to a cutting process. As described above, the electrostatic chuck device 2 can electrostatically adsorb the wafer 1 even when the electrostatic chuck device 2 is not in a vacuum environment. Therefore, the processing performed on the wafer 1 is not limited to processing performed in a vacuum. [0047] In addition, the present invention is not limited to the description of the aforementioned embodiment, and can be implemented with various changes. For example, the electrostatic chuck table 4 and the ionized air supply unit 6 may be used separately from each other, and may be used separately for other purposes. For example, when the ionized air supply unit 6 is an electrostatic eliminator, it may supply approximately the same amount of ionized air including ionized air of both polarities, and it may be used for static electricity removal of an object. [0048] The electrostatic chuck table 4 and the ionized air supply unit 6 which are independent of each other are used for electrostatic holding of the objects to be held such as the wafer 1, and when used as described in the foregoing embodiment, they constitute the electrostatic chuck device 2. [0049] The structures, methods, and the like of the aforementioned embodiments can be appropriately modified and implemented as long as they do not depart from the scope of the object of the present invention.

[0050]

1‧‧‧ wafer

1a‧‧‧ surface

1b‧‧‧ back

2‧‧‧ electrostatic chuck device

3‧‧‧ Scheduled dividing line

4‧‧‧ electrostatic chuck table

4a‧‧‧ keep face

4b‧‧‧ insulator

4c‧‧‧electrode

4d‧‧‧ Power

5‧‧‧ device

6‧‧‧ ionized air supply unit

6a‧‧‧ ionized air supply head

6b‧‧‧Ionized air supply source

6c‧‧‧Supply

7a‧‧‧ Charge on wafer

7b‧‧‧ Charge under the wafer

8‧‧‧ ionized air

10‧‧‧ Charge due to ionized air

12, 14‧‧‧ Charge supplied to the electrode

[0021] [FIG. 1] FIG. 1 (A) is a perspective view showing an example of an object to be electrostatically attracted by an electrostatic chuck device, and FIG. 1 (B) is a perspective view showing an electrostatic chuck device. [Fig. 2] Fig. 2 (A) is a cross-sectional view showing the electrostatic chuck device in a mode, and Fig. 2 (B) is a cross-sectional view showing the electrostatic adsorption of a held object in the electrostatic chuck device. [FIG. 3] FIG. 3 (A) is a cross-sectional view schematically illustrating electric charges and the like when the object to be held is electrostatically attracted, and FIG. 3 (B) is a cross-sectional view schematically illustrating electric charges and the like when the object is peeled.

Claims (3)

An electrostatic chuck device is an electrostatic chuck device that electrostatically adsorbs an object to be held under an atmospheric pressure environment, and is characterized by: having: an electrostatic chuck table with electrodes and a holding surface; and an ionized air supply unit for the holding surface The exposed surface of the object to be held supplies ionized air; 电极 The electrode has a function of supplying a charge during electrostatic adsorption of the object; 离子 The ionized air supply unit has a charge to be supplied to the electrode. The charged ions with opposite polarities are supplied to the exposed surface of the object to maintain the function of the charges on the exposed surface side of the object. According to the electrostatic chuck device described in item 1 of the scope of patent application, the object to be held is provided with a protective member on one side; and the object to be held is electrostatically adsorbed to the holding surface via the protective member. An electrostatic adsorption method, comprising: (1) a mounting step of placing an object to be held on the holding surface of an electrostatic chuck table having an electrode and a holding surface; and (2) an attraction control step of supplying an electric charge to the electrode to generate an electrostatic attractive force; And an ionized air having a polarity opposite to the polarity of the charge supplied to the electrode to the exposed surface of the object to maintain the charge on the exposed surface of the object and assist in controlling electrostatic attraction Attracting auxiliary steps.