JP2019114685A - Electrostatic chuck - Google Patents

Abstract

To provide an electrostatic chuck capable of holding a substrate even in a wet environment for a long time after being disconnected from a power supply.SOLUTION: An electrostatic chuck 10 includes: a substrate 11 made of a flat insulator having an attracting surface 11a for attracting a substrate W; and a conductor unit 13 including at least a pair of electrostatic chuck electrodes 12 embedded in the substrate 11. All the outer surfaces of the conductor unit 13 embedded in the substrate 11 are covered with the insulator. Volume resistivity of the insulator is greater than 1×10Ωcm.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an electrostatic chuck for holding a substrate such as a semiconductor wafer.

  Conventionally, for example, an electrostatic chuck is used to hold a substrate such as a semiconductor wafer in a semiconductor manufacturing apparatus.

  U.S. Pat. No. 6,095,095 discloses a static circuit comprising two planar electrodes connected to a power supply, each configured to hold opposite charges, and a capacitor electrically connected in parallel with the two electrodes. An electric chuck is disclosed. In this electrostatic chuck, even if the connection with the electrode is cut off, the electrostatic chuck chucking force for the substrate is maintained for a while by discharge from the capacitor.

  Patent Document 2 discloses an electrostatic attraction tray disposed between an electrostatic chuck and an attraction target (substrate). The tray incorporates electrodes of upper and lower two layers connected by wiring, and holds an object to be adsorbed placed on the upper surface by electrostatic potential given from the lower surface side. Further, it is also disclosed that the electrostatic chuck tray can be made of a low-resistance dielectric to transmit a high electrostatic potential and to improve the adsorption force.

JP 2002-299426 A JP, 2016-9715, A

  However, in the configuration disclosed in Patent Document 1, an electrical short circuit occurs between the terminals of the electrostatic chuck in a wet environment such as grinding a substrate in a wet state with a processing fluid, and There is a problem that the electrostatic adsorption force is lost by the rapid disappearance of the charge accumulated between the substrate and the substrate, and the substrate may not be held.

  Furthermore, in the configuration disclosed in Patent Document 2, since the electrostatic chuck tray is made of a low-resistance dielectric, the accumulated charge disappears quickly and the electrostatic attraction is lost in a short time. There is a problem that it can not be held for a long time.

  The present invention has been made in view of the problems of the prior art described above, and provides an electrostatic chuck capable of holding a substrate even in a wet environment for a long time after being disconnected from a power supply. The purpose is

The electrostatic chuck of the present invention comprises a base member made of a flat plate-like insulator having an adsorption surface for adsorbing a substrate, and a conductor portion including at least a pair of electrostatic chuck electrodes embedded in the substrate. In the electrostatic chuck, the entire outer surface of the conductor portion embedded in the base material is covered with the insulator, and the volume resistivity of the insulator is greater than 1 × 10 ¹⁵ Ωcm. It is characterized by

According to the electrostatic chuck of the present invention, since the substrate is made of a high resistivity insulator having a volume resistivity of more than 1 × 10 ¹⁵ Ωcm, electrical shorting between electrostatic chuck electrodes and the like is less likely to occur. The substrate can be adsorbed well even under the environment, and the disappearance of the accumulated charge can be delayed, and the electrostatic attraction can be maintained for a long time.

  Furthermore, since only at least a pair of electrostatic chuck electrodes are embedded in the base as a conductor portion, the thickness of the electrostatic chuck can be reduced as compared with the configurations described in Patent Documents 1 and 2. It becomes.

  Further, in the electrostatic chuck according to the present invention, the conductor portion embedded in the base includes at least the pair of electrostatic chuck electrodes and at least the pair of capacitor electrodes, and the suction surface includes a first region and the first region. It has a second region different from the first region, and the pair of electrostatic chuck electrodes is composed of a first electrostatic chuck electrode and a second electrostatic chuck electrode, and the pair of capacitor electrodes are the first one. It consists of a first capacitor electrode facing the electrostatic chuck electrode and a second capacitor electrode facing the second electrostatic chuck electrode, in a first direction from the suction surface to the surface opposite to the suction surface The first internal region in the base material overlapping the first region includes the first electrostatic chuck electrode and the first capacitor electrode, and the second region in the first direction A second internal region in the base material having the second electrostatic chuck electrode and the second capacitor electrode, and the first chuck electrode and the second capacitor electrode are electrically connected It is preferable that the second chuck electrode and the first capacitor electrode are electrically connected.

  In this case, the charge can be accumulated also in the first inner region and the second inner region, and the electrostatic attraction can be maintained for a longer time.

FIG. 1 is a schematic cross-sectional view of an electrostatic chuck according to a first embodiment. The model top view of the electrostatic chuck of FIG. FIG. 2 is a schematic view of an equivalent circuit when a substrate is placed on the electrostatic chuck of FIG. 1. FIG. 2 is a schematic cross-sectional view of an electrostatic chuck device. FIG. 5 is a schematic view of an equivalent circuit when a substrate is placed on the electrostatic chuck of FIG. 1 in the electrostatic chuck device of FIG. 4. FIG. 7 is a schematic cross-sectional view of an electrostatic chuck according to a second embodiment. FIG. 7 is a schematic top view of the electrostatic chuck of FIG. 6. FIG. 7 is a schematic view of an equivalent circuit when the substrate is placed on the electrostatic chuck of FIG. 6.

  An electrostatic chuck 10 according to a first embodiment of the present invention will be described with reference to the drawings.

  As shown in FIGS. 1 and 2, the electrostatic chuck 10 is provided with a flat substrate 11 such as a disk or a rectangular plate. The base material 11 has an adsorption surface 11a for adsorbing a substrate W such as a semiconductor wafer as an upper surface 11a and a surface opposite to the upper surface 11a as a lower surface 11b.

The substrate 11 is made of an insulator, and its volume resistivity is greater than 1 × 10 ¹⁵ Ωcm. The base 11 is made of, for example, a ceramic sintered body of alumina (Al ₂ O ₃ ), aluminum nitride (AlN), silicon carbide (SiC) or the like. The height in the vertical direction of the substrate 11, that is, the thickness is preferably 1.3 mm or less.

  The electrostatic chuck 10 further includes a conductor portion 13 including a pair of electrostatic chuck electrodes 12 embedded in the substrate 11. The electrostatic chuck electrode 12 is a thin film or thin plate metal electrode embedded in the base material 11 and extending in the direction along the upper surface 11 a and the lower surface 11 b. The electrostatic chuck electrode 12 is made of, for example, tungsten (W) or molybdenum (Mo).

  The electrostatic chuck electrodes 12 are juxtaposed in the direction along the upper surface 11a, and are composed of a first electrostatic chuck electrode 12A and a second electrostatic chuck electrode 12B electrically isolated from each other. For example, when the substrate 11 has a disk shape, the first and second electrostatic chuck electrodes 12A and 12B have a substantially semicircular shape. A gap T of preferably 3 mm or more, more preferably 5 mm or more, is provided between the first and second electrostatic chuck electrodes 12A and 12B.

  The entire outer surface of conductor portion 13 embedded in base material 11 is covered with the insulator constituting base material 11, and is not exposed to the outside at all, and is connected to an external power supply or the like. It is not configured to be able to connect to the terminal etc.

  The equivalent circuit when the substrate W is mounted on the electrostatic chuck 10 is, as schematically shown in FIG. 3, between the substrate W and the electrostatic chuck electrode 12 on the first electrostatic chuck electrode 12A. The capacitor C1 is formed in the region S1, and the capacitor C2 is formed in the region S2 on the second electrostatic chuck electrode 12B. Then, on the upper surface 11a of the electrostatic chuck 10, an insulator constituting the base material 11 between the area SA1 on the first electrostatic chuck electrode 12A and the area SA2 on the second electrostatic chuck electrode 12B. It is connected by the substrate W which consists of a conductor or semiconductor whose electrical resistance is negligibly small compared to the above. Furthermore, in the case of passing from the first electrostatic chuck electrode 12A to the substrate W through the region S1 and going to the substrate W from the second electrostatic chuck electrode 12B in the direction to the substrate W. Can be regarded as the formation of the electric resistance R2.

  In electrostatic chuck 10, a potential difference is applied between electrostatic chuck electrodes 12A and 12B, and when charges are stored in capacitors C1 and C2, a Coulomb force acts between electrostatic chuck electrode 12 and substrate W. The substrate W is attracted to the attraction surface 11a. The electrostatic chuck 10 is a so-called bipolar electrostatic chuck in which voltages having opposite polarities are applied to the first electrostatic chuck electrode 12A and the second electrostatic chuck electrode 12B.

In the electrostatic chuck 10 having such a circuit configuration, the capacitors C1 and C2 gradually attenuate the charge according to the electric resistances R1 and R2 connected in parallel. However, since the volume resistivity of the insulator constituting the substrate 11 is larger than 1 × 10 ¹⁵ Ωcm, the electric resistances R1 and R2 become very large, so the charge decay speed becomes very slow. Further, since the volume resistivity of the insulator is sufficiently large, it is possible to suppress the leak current flowing between the electrostatic chuck electrodes 12A and 12B.

  Therefore, even in a wet environment, the residual adsorption force does not rapidly disappear, and the residual adsorption force lasts for a long time, so that the substrate W can be adsorbed continuously for a long time. Furthermore, the thickness of the electrostatic chuck 10 can be reduced compared to the electrostatic adsorption tray disclosed in the above-mentioned Patent Document 2, and in the state where the substrate W is adsorbed to the electrostatic chuck 10, The present invention can be applied to a system used when transporting and storing the substrate W with the substrate W alone.

  Next, an example of an electrostatic chuck device 100 using the electrostatic chuck 10 of the present invention will be described with reference to the drawings.

  As shown in FIG. 4, the electrostatic chuck apparatus 100 includes an electrostatic chuck 20 in addition to the electrostatic chuck 10. The electrostatic chuck 20 is a conventional one, and a commercially available product may be used.

  The electrostatic chuck 20 is provided with a flat substrate 21 having the same or larger shape as the substrate 11 of the electrostatic chuck 10 in a top view. The base 21 has a mounting surface 21a on which the lower surface 11b of the electrostatic chuck 10 is mounted as the upper surface 21a, and a surface opposite to the upper surface 21a as the lower surface 21b.

The substrate 21 is made of an insulator, and the volume resistivity may be the same as, larger than, or smaller than the volume resistivity of the substrate 11. The base 21 is made of, for example, a ceramic sintered body such as aluminum nitride (AlN) or aluminum oxide (Al ₂ O ₃ ) silicon carbide (SiC).

  The electrostatic chuck 20 further includes at least a pair of electrostatic chuck electrodes 22 embedded in the substrate 21. The electrostatic chuck electrode 22 is a thin film metal electrode embedded in the base 21 and extending in the direction along the upper surface 21 a and the lower surface 21 b. The electrostatic chuck electrode 22 is made of, for example, tungsten (W) or molybdenum (Mo).

  The electrostatic chuck electrodes 22 are juxtaposed in the direction along the upper surface 21a, and are composed of a first electrostatic chuck electrode 22A and a second electrostatic chuck electrode 22B electrically insulated from each other. For example, when the substrate 21 has a disk shape, the first and second electrostatic chuck electrodes 22A and 22B have a substantially semicircular shape.

  The electrostatic chuck 20 further includes a feed terminal 23. One end of the power supply terminal 23 is electrically connected to the electrostatic chuck electrode 22, and the other end is exposed at the lower surface 21 b of the base 21. The feed terminal 23 is configured to be connectable to the power supply PS at the end exposed from the base 21.

  The feed terminal 23 includes a first feed terminal 23A whose one end is connected to the first electrostatic chuck electrode 22A, and a second feed terminal 23B whose one end is connected to the second electrostatic chuck electrode 22B. It consists of The first and second feed terminals 23A and 23B are connected to power supplies PS of different polarities. Thus, voltages of different positive and negative polarities can be applied to the first and second electrostatic chuck electrodes 22A and 22B through the first and second feed terminals 23A and 23B, respectively. .

  The equivalent circuit of the electrostatic chuck apparatus 100 formed by mounting the electrostatic chuck 10 on which the substrate W is mounted on the mounting surface 21a of the electrostatic chuck 20 is, as schematically shown in FIG. A capacitor C3 is formed in a region S3 under the first electrostatic chuck electrode 12A between the electrode 12 and the lower surface 11b of the electrostatic chuck 10, and a capacitor C4 is in a region S4 under the second electrostatic chuck electrode 12B. It is formed. The capacitor C5 is formed in the region S5 on the first electrostatic chuck electrode 22A between the lower surface 11b of the electrostatic chuck 10 and the electrostatic chuck electrode 22, and the region on the second electrostatic chuck electrode 22B. Capacitor C6 is formed at S6.

  Furthermore, when passing from the lower surface 11b of the electrostatic chuck 10 to the area S3 toward the first electrostatic chuck electrode 12A, the electric resistance R3 passes from the lower surface 11b of the electrostatic chuck 10 to the area S4 and the second static In the case of going to the electric chuck electrode 12B, it can be considered that the electric resistance R4 is formed. Then, when passing from the first electrostatic chuck electrode 22A to the area S5 and going to the lower surface 11b of the electrostatic chuck 10, the electrical resistance R5 passes from the second electrostatic chuck electrode 22B to the area S6 and the electrostatic chuck In the case of going to the lower surface 11b of 10, it can be considered that the electrical resistance R6 is formed.

  As described above, in the electrostatic chuck device 100, the capacitors C1, C3, and C5 are connected in series, and the capacitors C2, C4, and C6 are connected in series.

  As described above, when the power supply PS is connected to the feeding terminal 23 to load a voltage, charges are accumulated in the capacitors C1 to C6. Thereafter, when the electrostatic chuck 10 is separated from the electrostatic chuck 20, the charges accumulated in the capacitors C1 and C2 decay as time passes, but as described above, the charges accumulated in the capacitors C1 and C2 disappear The substrate W can be adsorbed by the electrostatic chuck 10 up to the point.

  Next, an electrostatic chuck 10A according to a second embodiment of the present invention will be described with reference to the drawings.

  The first region of the present invention corresponds to a region SA1 (a region surrounded by a dotted line indicating a symbol 12A in FIG. 7) overlapping with the first electrostatic chuck electrode 12A of the suction surface 11a in top view. The second region corresponds to a region SA2 (a region surrounded by a dotted line indicating a symbol 12B in FIG. 7) overlapping with the second electrostatic chuck electrode 12B of the suction surface 11a in top view. The first direction of the present invention corresponds to the downward direction from the upper surface 11a to the lower surface 11b.

  As shown in FIGS. 6 and 7, the electrostatic chuck 10 </ b> A includes a base 11 and a pair of electrostatic chuck electrodes 12 similar to the above-described electrostatic chuck 10. Further, the electrostatic chuck 10A, as the conductor portion 13A, includes the pair of electrostatic chuck electrodes 12 and a wire 15 electrically connecting the pair of capacitor electrodes 14 and the electrostatic chuck electrodes 12 to the capacitor electrode 14 Have.

  Here, the first and second electrostatic chuck electrodes 12A and 12B are embedded along the upper surface 11a so that the heights of the base material 11 in the vertical direction are equal. The capacitor electrode 14 is embedded in the base 11 along the upper surface 11a at a position farther from the upper surface 11a than the first electrostatic chuck electrode 12A and at a position facing the first electrostatic chuck electrode 12A. The base material along the upper surface 11a at a position farther from the upper surface 11a than the first capacitor electrode 14A and the second electrostatic chuck electrode 12B, and at a position facing the second electrostatic chuck electrode 12B And 11, a second capacitor electrode 14B built in. The capacitor electrode 14 is made of, for example, tungsten (W) or molybdenum (Mo). For example, when the first and second electrostatic chuck electrodes 12A and 12B have a substantially semicircular plate shape, the first and second capacitor electrodes 14A and 14B have a substantially semicircular shape, respectively.

  The first inner region SI1 of the present invention corresponds to a region S1 and a region S7 overlapping the first electrostatic chuck electrode 12A of the substrate 11 in top view, and the second inner region SI2 of the present invention is top view Corresponds to a region S2 and a region S8 overlapping the second electrostatic chuck electrode 12B of the substrate 11.

  Wiring 15 includes first wiring 15A electrically connecting first electrostatic chuck electrode 12A and second capacitor electrode 14B, second electrostatic chuck electrode 12B and first capacitor electrode 14A. It is comprised from the 2nd wiring 15B electrically connected. The structure of the wiring 15 is not limited as long as the wiring 15 electrically connects the electrostatic chuck electrode 12 and the capacitor electrode 14. The wiring 15 is, for example, a metal layer formed in a via hole extending in the vertical direction in the base 11, and the metal layer is electrically connected to the electrostatic chuck electrode 12 and the capacitor electrode 14. May be

  The equivalent circuit of the electrostatic chuck 10A when the substrate W is mounted is, as shown in FIG. 8, between the electrostatic chuck electrode 12 and the capacitor electrode 14 below the first electrostatic chuck electrode 12A. Capacitor C7 is formed in region S7, and capacitor C8 is formed in the region below second capacitor electrode 12B.

  Furthermore, when passing from the first electrostatic chuck electrode 12A to the first capacitor electrode 14A through the region S7, the electric resistance R7 passes from the second electrostatic chuck electrode 12B to the region S8 to the second In the case of going to the capacitor electrode 14B, the electric resistance R8 can be considered to be formed, respectively. The capacitors C7 and C8 and the electrical resistors R7 and R8 are connected in parallel.

  When the power supply PS is connected to the feeding terminal 23 and a voltage is applied while the electrostatic chuck 10A having such a configuration is mounted on the electrostatic chuck 20, charges are accumulated in the capacitors C1, C2, C7, and C8. . Thereafter, when the electrostatic chuck 10A is separated from the electrostatic chuck 20, the capacitors C1 and C2 gradually attenuate the charge according to the electric resistances R1 and R2 connected in parallel. However, the charges accumulated in the capacitors C7 and C8 move to the capacitors C1 and C2. Therefore, as compared with the electrostatic chuck 10 described above, the substrate W can be adsorbed for a longer time.

  Similarly to the electrostatic chuck 10 described above, the electrostatic chuck 10A uses, for example, the above-described electrostatic chuck device 100 to apply voltages opposite to each other between the first electrostatic chuck electrode 12A and the second electrostatic chuck electrode 12B. Should be applied.

  Each composition mentioned above is an example, and each composition may be changed by a use etc.

Example 1
A ceramic green sheet made of aluminum nitride for forming the electrostatic chuck 10 was prepared. Each ceramic green sheet was a disk-shaped ceramic green sheet having a thickness of 0.65 mm and a radius of 200 mm. The electrostatic chuck electrode 12 was formed by screen printing on one surface of one of the ceramic green sheets. The first and second electrostatic chuck electrodes 12A and 12B are each formed of tungsten and formed in a semicircular disk shape having a thickness of 20 μm and a radius of 147 mm after firing, and have a gap T of 5 mm between them. It was done.

With the ceramic green sheet formed by screen printing the electrostatic chuck electrode 12 as the third from the top, five ceramic green sheets were stacked and pressure bonded, and firing was performed at 1800 ° C. for 4 hours in a furnace. The upper and lower surfaces were ground so that the height from the electrostatic chuck electrode 12 to the upper surface 11a was 0.3 mm and the total thickness of the electrostatic chuck 10 was 1.3 mm. Thus, the electrostatic chuck 10 is completed. The volume resistivity of the insulator of the base material 11 of the electrostatic chuck 10 was 2 × 10 ¹⁵ Ωcm when it was measured at 500 V at room temperature using a Hyrester manufactured by Dia Instruments.

Then, as the substrate W, a disk-shaped one made of a silicon wafer and having a thickness of 0.7 mm and a radius of 150 mm was prepared. As the electrostatic chuck 20, one having an insulator obtained by adding titanium nitride (TiN) to aluminum nitride and having a volume resistivity of 1 × 10 ¹³ Ωcm was prepared.

  The electrostatic chuck 10 was placed on the upper surface 21 a of the electrostatic chuck 20, and the substrate W was placed on the upper surface 11 a of the electrostatic chuck 10. Then, voltages of +5 kV and −5 kV were applied to the electrostatic chuck 20 by the two power sources PS connected to the electrostatic chuck 20. 60 seconds after the start of the application, the connection between the power source PS and the electrostatic chuck 20 was cut off, and immediately thereafter, the electrostatic chuck 10 in a state where the substrate W was adsorbed was separated from the electrostatic chuck 20.

  The electrostatic chuck 10 in a state where the substrate W was adsorbed was transported using a transport system, and was temporarily stored in a portion for storing the substrate W of the substrate storage device. Thereafter, the electrostatic chuck 10 in a state where the substrate W was adsorbed was carried out from the substrate storage device, and was transferred to a machining device for grinding the upper surface of the substrate W using a transfer system. Then, in this machining device, grinding was performed in a wet environment where the machining fluid is in contact with the machining surface.

  Even after 600 seconds have elapsed since the electrostatic chuck 10 was separated from the electrostatic chuck 20, the state in which the substrate W was attracted to the electrostatic chuck 10 was maintained.

  As described above, in the electrostatic chuck 10 of Example 1, the substrate W can be adsorbed even in a wet environment, and the substrate W can be adsorbed for a long time of 600 seconds.

(Example 2)
In Example 2, an electrostatic chuck 10 was manufactured in the same manner as in Example 1 using a ceramic green sheet different in material from Example 1 and made of alumina (Al ₂ O ₃ ).

The ceramic green sheet had a thickness of 0.4 mm. The ceramic green sheet having the electrostatic chuck electrode 12 formed by screen printing as the third from the top was fired at 1600 ° C. for 4 hours in a furnace in a state where five ceramic green sheets were stacked. Then, the upper and lower surfaces were ground so that the height from the electrostatic chuck electrode 12 to the upper surface 11 a was 0.2 mm and the total thickness of the electrostatic chuck 10 was 0.8 mm. The volume resistivity of the insulator of the base material 11 of the electrostatic chuck 10 was 8 × 10 ¹⁵ Ωcm when it was measured at 500 V at room temperature using a Hyrester manufactured by Dia Instruments.

  Then, using the same substrate W and electrostatic chuck 20 as in the first embodiment, the same voltage was applied to the electrostatic chuck 20. Then, in the same manner as in the first embodiment, the power supply PS was disconnected, the electrostatic chuck 10 was separated, the electrostatic chuck 10 was transported and stored, and the substrate W was ground.

  In the second embodiment, as in the first embodiment, the state in which the substrate W is attracted to the electrostatic chuck 10 is maintained even if 600 seconds have elapsed since the electrostatic chuck 10 is separated from the electrostatic chuck 20. It was

(Example 3)
In Example 3, an electrostatic chuck 10 was manufactured in the same manner as in Example 1 using a ceramic green sheet made of the same material as that in Example 1.

However, with the ceramic green sheet on which the electrostatic chuck electrode 12 was formed by screen printing as the third from the top, five ceramic green sheets were laminated, and firing was performed at 1800 ° C. for 4 hours in a furnace. Then, the upper and lower surfaces were ground so that the height from the electrostatic chuck electrode 12 to the upper surface 11 a was 0.3 mm and the total thickness of the electrostatic chuck 10 was 1.6 mm. The volume resistivity of the insulator of the base material 11 of the electrostatic chuck 10 was 2 × 10 ¹⁵ Ωcm when it was measured at 500 V at room temperature using a Hyrester manufactured by Dia Instruments.

  Then, using the same substrate W and electrostatic chuck 20 as in the first embodiment, the same voltage was applied to the electrostatic chuck 20. Then, in the same manner as in Example 1, the disconnection of the power supply PS and the separation of the electrostatic chuck 10 were performed. However, since the thickness of the electrostatic chuck 10 was too thick, it was not possible to transport the electrostatic chuck 10 in a state where the substrate W is adsorbed using the transport system and to store using the substrate storage device.

  However, using the same machining apparatus as in Example 1, it was possible to grind the substrate W adsorbed by the electrostatic chuck 10 in a wet environment where the machining fluid is in contact with the machining surface.

  In the third embodiment, even after 600 seconds have elapsed since the electrostatic chuck 10 was separated from the electrostatic chuck 20, the state in which the substrate W was attracted to the electrostatic chuck 10 was maintained.

(Comparative example)
In the comparative example, the electrostatic chuck 10 is manufactured in the same manner as in Example 1 using a ceramic green sheet made of aluminum nitride different in material from Example 1 and added with 3% by weight of samarium oxide (Sm ₂ O ₃ ). did.

The ceramic green sheet had a thickness of 0.65 mm. The ceramic green sheet having the electrostatic chuck electrode 12 formed by screen printing as the third from the top was fired at 1800 ° C. for 4 hours in a furnace in a state where five ceramic green sheets were laminated. Then, the upper and lower surfaces were ground so that the height from the electrostatic chuck electrode 12 to the upper surface 11 a was 0.5 mm and the total thickness of the electrostatic chuck 10 was 1.0 mm. The volume resistivity of the insulator of the base material 11 of the electrostatic chuck 10 was 3 × 10 ¹³ Ωcm when it was measured at 500 V at room temperature using a Hyrester manufactured by Dia Instruments.

  Then, using the same substrate W and electrostatic chuck 20 as in the first embodiment, the same voltage was applied to the electrostatic chuck 20. Then, in the same manner as in the first embodiment, the power supply PS was disconnected, the electrostatic chuck 10 was separated, the electrostatic chuck 10 was transported and stored, and the substrate W was ground.

  In the comparative example, the substrate W was removed from the electrostatic chuck 10 during the grinding process after 120 seconds had elapsed since the electrostatic chuck 10 was separated from the electrostatic chuck 20.

  The above results are summarized in Table 1. The “insulator thickness” in Table 1 and Table 2 described later means the thickness of the insulator between the upper surface 11 a of the substrate 11 and the electrostatic chuck electrode 12.

(Example 4)
A ceramic green sheet of aluminum nitride was prepared to constitute the electrostatic chuck 10A. Each ceramic green sheet was a disk-shaped ceramic green sheet having a thickness of 0.65 mm and a radius of 200 mm. The first electrostatic chuck electrode 12A and the second electrostatic chuck electrode 12B were formed by screen printing on one surface of one of the ceramic green sheets. Further, the first capacitor electrode 14A and the second capacitor electrode 14B were formed by screen printing on one surface of another ceramic green sheet.

  The first and second electrostatic chuck electrodes 12A and 12B and the first and second capacitor electrodes 14A and 14B are each made of tungsten so as to have a thickness of 20 μm and a semicircular plate with a radius of 147 mm after firing. It formed. After firing, gaps of 5 mm are provided between the first electrostatic chuck electrode 12A and the second electrostatic chuck electrode 12B and between the first capacitor electrode 14A and the second capacitor electrode 14B. Thus, electrostatic chuck electrodes 12A and 12B and capacitor electrodes 14A and 14B are provided.

  Note that, in order to connect the electrostatic chuck electrodes 12A and 12B and the capacitor electrodes 14A and 14B via first and second wires 15A and 15B described later, the first in the vertical direction when the ceramic green sheets are stacked, The electrostatic chuck electrode 12A, the second electrostatic chuck electrode 12B partially overlaps the second electrostatic chuck electrode 14B, and the second electrostatic chuck electrode 12B partially overlaps the first capacitor electrode 14A. Asperities were provided on part of the outer edge of each of 12B and capacitor electrodes 14A and 14B. The first wiring 15A is connected to the portion where the first electrostatic chuck electrode 12A and the second capacitor electrode 14B partially overlap in the vertical direction, and the second electrostatic chuck electrode 12B and the first capacitor electrode 14A The second wiring 15B was connected to a portion where the portions partially overlap.

  A ceramic green sheet on which the first electrostatic chuck electrode 12A and the second electrostatic chuck electrode 12B are formed by screen printing, and a ceramic green sheet on which the first capacitor electrode 14A and the second capacitor electrode 14B are formed by screen printing And stacked. Then, via holes vertically penetrating through the stacked ceramic green sheets are formed, and a layer made of tungsten metal is formed in the via holes, thereby forming the first and second wirings 15A and 15B. Further, after pressure bonding was performed in a state where a plurality of plain ceramic green sheets were stacked one on top of the other, firing was performed at 1800 ° C. for 4 hours in a furnace.

The upper and lower surfaces were ground so that the height from the first electrostatic chuck electrode 12A to the upper surface 11a was 0.3 mm and the total thickness of the electrostatic chuck 10A was 1.3 mm. Thus, the electrostatic chuck 10A is completed. The height from the first electrostatic chuck electrode 12A to the first capacitor electrode 14A was 0.5 mm. The volume resistivity of the insulator of the base material 11 of the electrostatic chuck 10A was 2 × 10 ¹⁵ Ωcm when it was measured at 500 V at room temperature using a hi-rester manufactured by DI.

  Then, using the same substrate W and electrostatic chuck 20 as in the first embodiment, the same voltage was applied to the electrostatic chuck 20. Then, in the same manner as in Example 1, the power supply PS was disconnected, the electrostatic chuck 10A was separated, the electrostatic chuck 10A was transported and stored, and the substrate W was ground.

  In the fourth embodiment, longer than the first embodiment, the state in which the substrate W is attracted to the electrostatic chuck 10A is maintained even if 900 seconds have elapsed since the electrostatic chuck 10A is separated from the electrostatic chuck 20. It was

  From the above, in the electrostatic chuck 10A of Example 4, the substrate W can be adsorbed even in a wet environment, and the substrate W can be adsorbed for a long time of 900 seconds.

(Example 5)
In Example 5, an electrostatic chuck 10A was manufactured in the same manner as in Example 4 using a ceramic green sheet which is different in material from Example 1 and made of alumina.

  However, with the ceramic green sheet on which the first electrostatic chuck electrode 12A and the second electrostatic chuck electrode 12B are formed by screen printing as the second from the top, the first capacitor electrode 14A and the second capacitor electrode 14B are screened. With the ceramic green sheets formed by printing as the third from the top, five ceramic green sheets were laminated, and firing was performed at 1600 ° C. for 2 hours in a furnace.

The upper and lower surfaces were ground so that the height from the first electrostatic chuck electrode 12A to the upper surface 11a was 0.2 mm and the total thickness of the electrostatic chuck 10A was 0.8 mm. Thus, the electrostatic chuck 10A is completed. The height from the first electrostatic chuck electrode 12A to the first capacitor electrode 14A was 0.3 mm. The volume resistivity of the insulator of the base material 11 of the electrostatic chuck 10A was 8 × 10 ¹⁵ Ωcm when it was measured at 500 V at room temperature using a hi-rester manufactured by DI.

  Then, using the same substrate W and electrostatic chuck 20 as in Example 4, the same voltage was applied to the electrostatic chuck 20. Then, in the same manner as in Example 1, the power supply PS was disconnected, the electrostatic chuck 10A was separated, the electrostatic chuck 10A was transported and stored, and the substrate W was ground.

  In the fifth embodiment, as in the fourth embodiment, the state in which the substrate W is attracted to the electrostatic chuck 10A is maintained even after 900 seconds have elapsed since the electrostatic chuck 10A is separated from the electrostatic chuck 20. It was

  The above results are summarized in Table 2. The “inter-electrode thickness” in Table 2 means the thickness of the insulator between the first electrostatic chuck electrode 12A and the first capacitor electrode 14A.

  DESCRIPTION OF SYMBOLS 10, 10A, 20 ... electrostatic chuck, 11 ... base material, 11a ... upper surface, adsorption surface, 11b ... lower surface, 12 ... electrostatic chuck electrode, 12A ... 1st electrostatic chuck electrode, 12B ... 2nd electrostatic Chuck electrode 13 conductor portion 14 capacitor electrode 14A first capacitor electrode 14B second capacitor electrode 15 wiring 15A first wiring 15B second wiring 21 base Material: 21a: upper surface, 21b: lower surface, 22: electrostatic chuck electrode, 22A: first electrostatic chuck electrode, 22B: second electrostatic chuck electrode, 23: feeding terminal, 23A: first feeding terminal, 23B: second power supply terminal 100: electrostatic chuck device C1 to C8: capacitor PS: power source R1 to R8: electrical resistance S1 to S8: area SI1: first internal region , SI2 ... second interior region, SA1 ... region (first region), SA2 ... region (second region), W ... substrate.

Claims (2)

An electrostatic chuck comprising: a base made of a flat plate-like insulator having an adsorption surface for adsorbing a substrate; and a conductor portion including at least a pair of electrostatic chuck electrodes embedded in the base,
An electrostatic chuck characterized in that the entire outer surface of the conductor portion embedded in the base material is covered with the insulator, and the volume resistivity of the insulator is larger than 1 × 10 ¹⁵ Ωcm. . The conductor portion embedded in the substrate includes at least the pair of electrostatic chuck electrodes and the at least pair of capacitor electrodes.
The suction surface has a first area and a second area different from the first area,
The pair of electrostatic chuck electrodes comprises a first electrostatic chuck electrode and a second electrostatic chuck electrode,
The pair of capacitor electrodes includes a first capacitor electrode facing the first electrostatic chuck electrode and a second capacitor electrode facing the second electrostatic chuck electrode,
The first electrostatic chuck electrode and the first capacitor electrode in a first internal region in the base material overlapping the first region in a first direction from the suction surface to a surface opposite to the suction surface Have
A second internal region in the base material overlapping the second region in the first direction, the second electrostatic chuck electrode and the second capacitor electrode;
The first chuck electrode and the second capacitor electrode are electrically connected, and the second chuck electrode and the first capacitor electrode are electrically connected. The electrostatic chuck described in.