JP2004111533A - Electrostatic attraction apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic attraction apparatus in which heat conduction with an object to be treated is prevented from being lowered and the cost of parts can be reduced. <P>SOLUTION: The electrostatic adsorption apparatus is provided with an electrode 5 which is connected to an external variable DC power source 9 via a lead wire 8, and a protecting film 6 which covers the electrode 5 and is composed of a dielectric body, and the protecting film 6 is formed on a surface of the electrode 5 except for the surface to place the object 2 to be treated. The dielectric body to be used for the protecting film 6 is composed of quartz or a polyimide resin, ceramic (e.g., alumina (Al<SB>2</SB>O<SB>3</SB>), aluminum nitride (AlN), zinc oxide (Zn<SB>2</SB>O<SB>3</SB>) and boron nitride (BN, PBN)) and the like. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electrostatic attraction device for an object to be processed, and more particularly, to an electrostatic attraction device for attracting a thinned object to be processed by an electrostatic force.
[0002]
[Prior art]
2. Description of the Related Art A semiconductor manufacturing apparatus generally includes a chamber that is evacuated to a reduced pressure, and a holding device for holding an object to be processed is arranged in the chamber.
[0003]
FIG. 3 is a vertical cross-sectional view showing a schematic configuration of an object-to-be-processed holding device provided with a conventional electrostatic attraction device.
[0004]
In FIG. 3, a holding device 21 is directly joined to a base member 23 made of a metal (for example, aluminum, stainless steel, nickel, or the like) and an upper surface of the base member 23, and sucks a wafer 22, which is an object to be processed. And an electrostatic attraction device 24 for holding.
[0005]
It is assumed that the wafer 22 is subjected to processing by plasma or the like on a surface (hereinafter, referred to as “pattern back surface”) opposite to a surface on which a circuit pattern is formed (hereinafter, referred to as “pattern surface”). A protective film 27 made of a dielectric having the same outer diameter as the wafer 22 is bonded to the pattern surface. The wafer 22 is placed so that the lower surface of the protective film 27 is in close contact with the upper surface of the electrostatic attraction device 24.
[0006]
The electrostatic attraction device 24 has an electrode 25 connected to an external variable DC power supply 29 via a conducting wire 28, a protective film 26 made of a dielectric material similar to the protective film 27 while covering the entire surface of the electrode 25. When a DC current is applied to the electrode 25 by the variable DC power supply 29, the electrostatic attraction device 24 generates an electrostatic force caused by the electric charge given from the electrode 25 to the protective film 26 and the electric charge polarized near the surface of the protective film 27. As a result, a suction force is generated, and the wafer 22 is suction-held.
[0007]
Since the surface of the wafer 22, the protective film 27, and the electrostatic attraction device 24 actually have many minute irregularities and are not flat, for example, the upper surface of the electrostatic attraction device 24 and the lower surface of the protection film 27 are provided. Is in point contact, and there is a possibility that heat conduction between them will decrease.
[0008]
In view of this, there has been proposed an electrostatic attraction device having a structure in which a joining portion between the wafer 22 and the electrostatic attraction device 24 is filled with helium gas or the like and improving the heat conduction thereof (for example, Patent Document 1). ).
[0009]
[Patent Document 1]
JP 2001-110883 A
[Problems to be solved by the invention]
However, in the above-mentioned conventional holding device 21, the wafer 22 to be processed is placed on the electrostatic attraction device 24 via the protective film 26 and the protective film 27 made of a dielectric while covering the entire surface of the electrode 25. Therefore, there is a problem that heat conduction between the wafer 22 and the electrostatic attraction device 24 is reduced, for example, the cooling efficiency of the wafer 22 is reduced during the plasma etching process, and the temperature control of the wafer 22 becomes difficult.
[0011]
The present invention has been made in view of the above problems, and an object of the present invention is to provide an electrostatic attraction device that can prevent a decrease in heat conduction between an object to be processed and reduce the cost of components. Aim.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, an electrostatic attraction device according to claim 1 includes an electrode, a protective film that covers the electrode and is made of a dielectric material, and electrostatically attracts and holds an object to be processed by electrostatic force. In the apparatus, the protective film is formed on a surface of the electrode other than the surface on which the object to be processed is placed.
[0013]
According to a second aspect of the present invention, in the electrostatic attraction device according to the first aspect, the object to be processed has a protective film made of a dielectric adhered to a joint surface with the electrode. I do.
[0014]
According to a third aspect of the present invention, in the electrostatic attraction device according to the first or second aspect, the dielectric is made of any one of quartz, polyimide resin, and ceramic.
[0015]
According to a fourth aspect of the present invention, in the electrostatic attraction device according to any one of the first to third aspects, the object to be processed is a semiconductor wafer having a thickness of 50 to 100 μm. And
[0016]
According to a fifth aspect of the present invention, in the electrostatic attraction device according to any one of the second to fourth aspects, the protection film is formed on a surface of the workpiece on which a circuit pattern is formed. It is characterized by having been done.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
An electrostatic chuck according to an embodiment of the present invention will be described with reference to the drawings.
[0018]
FIG. 1 is a vertical cross-sectional view showing a schematic configuration of an object-to-be-processed holding device provided with an electrostatic suction device according to an embodiment of the present invention. The object-to-be-processed holding device is arranged, for example, in a plasma etching device (not shown).
[0019]
In FIG. 1, an object-to-be-processed holding device 1 is, for example, a base member 3 formed of a metal such as aluminum, stainless steel, nickel or the like, and directly joined to an upper surface of the base member 3 to adsorb the object to be processed 2. And an electrostatic suction device 4 for holding.
[0020]
The object 2 is made of a semiconductor wafer such as silicon (Si) or gallium arsenide (GaAs), and a circuit pattern is formed on one of the surfaces. In the present embodiment, a plasma etching process is performed on a surface (hereinafter, referred to as a “pattern back surface”) of the processing target 2 opposite to a surface on which a circuit pattern is formed (hereinafter, referred to as a “pattern surface”). In this case, a protective film 7 made of a dielectric having the same outer diameter as the object 2 is adhered to the pattern surface.
[0021]
The electrostatic attraction device 4 has an electrode 5 connected to an external variable DC power supply 9 via a conducting wire 8, and a protective film 6 covering the electrode 5 and made of the same dielectric material as the protective film 7. The electrode 5 is made of a conductor such as copper (Cu) having a thickness of 20 to 30 μm. The dielectric material used for the protective film 6 is quartz (quartz), polyimide resin, ceramic (for example, alumina (Al ₂ O ₃ ), aluminum nitride (AlN), zinc oxide (Zn ₂ O ₃ ), and boron nitride ( BN, PBN)) and the like.
[0022]
The protective film 6 is formed on a surface of the electrode 5 other than the surface on which the object 2 is placed. Therefore, the object 2 is placed on the electrode 5 so as to be in close contact with the surface of the electrode 5 via the protective film 7.
[0023]
When a DC current is applied to the electrode 5 by the variable DC power supply 9, the electrostatic attraction device 4 generates an attraction force due to an electrostatic force caused by an electric charge applied to the protective film 7 from the electrode 5, and Is held by suction. The required attraction force varies depending on the material and thickness of the dielectric used for the protective film 7, but can be obtained by adjusting the potential difference between the electrode 5 and the processing target 2.
[0024]
The processing object holding device 1 includes a gas ejection device that fills a gas at a bonding portion between the processing object 2 and the electrostatic suction device 4 and / or a bonding portion between the electrostatic suction device 4 and the base member 3. The gas ejection device fills a small gap between the joints by filling the joint with a gas such as helium, thereby improving the thermal conductivity and cooling the workpiece 2. Thus, even if the object 2 is placed on the object holding device 1 via the protective film 7 and the dielectric covering the electrode 5, the heat between the object 2 and the electrostatic attraction device 4 can be maintained. Since the conductivity does not decrease, the cooling efficiency of the object 2 during the plasma etching process can be improved, and the temperature of the object 2 can be easily controlled.
[0025]
In the present embodiment, the processing target 2 is assumed to have an outer diameter of 8 inches φ, but may have any outer diameter. The thickness of the processing target 2 is usually about 750 μm, but the back surface of the pattern is polished and ground, and the thickness is reduced to about 50 to 100 μm.
[0026]
The protective film 7 is required to have a high physical strength so that the workpiece 2 is not easily damaged by external force during the transport of the workpiece 2 or plasma etching. A device that is easily attracted and held by the table or the electrostatic attraction device 4 is required.
[0027]
As the dielectric used for the protective film 7, similarly to the protective film 6, quartz (quartz), polyimide resin, ceramic (for example, alumina (Al ₂ O ₃ ), aluminum nitride (AlN), zinc oxide (Zn ₂ O) ₃ ), and boron nitride (BN, PBN)) are suitable. These are excellent in dielectric constant and thermal conductivity, and are appropriately selected according to the size of the processing target 2, the state at the time of plasma etching processing, the type of semiconductor manufacturing apparatus, and the like.
[0028]
The thickness of the protective film 7 is set according to the physical strength of the dielectric, but is preferably 100 to 500 μm for quartz and 300 to 600 μm for polyimide resin. In the case of ceramic, the thickness is preferably 100 to 500 μm.
[0029]
In particular, quartz has good workability compared to other dielectrics, and polyimide resin is good because it has a large dielectric constant. Further, ceramics are preferable because they have higher thermal conductivity and dielectric constant than other dielectrics.
[0030]
According to the above-described embodiment, in the electrostatic adsorption device 4 including the electrode 5 connected to the external variable DC power supply 9 via the conducting wire 8 and the protective film 6 made of a dielectric while covering the electrode 5, Since the film 6 is formed on the surface of the electrode 5 other than the surface on which the processing target 2 is placed, it is possible to prevent a decrease in heat conduction between the processing target 2 and the protective film 6 covering the electrode 5. Thus, the cost of parts can be reduced.
[0031]
In the above embodiment, the protective film 6 also covers the outer peripheral surface of the electrode 5, but does not cover the outer peripheral surface of the electrode 5 as shown in FIG. May be set to the same length in the radial direction. The electrode 5 is made of copper (Cu), but may be another conductor.
[0032]
The adhesive that bonds the object 2 and the protective film 7 is preferably one that can be easily peeled off by heat, a solvent, or the like in consideration of the processing in the post-process after the plasma etching processing. Further, the processing target 2 may be simply placed on the upper surface of the protective film 7 without bonding. In this case, the workpiece 2 and the protective film 7 are attracted to each other by residual static electricity, so that the protective film 7 can be prevented from dropping during transportation or the like.
[0033]
Further, the protective film 7 may be formed by heating and drying after the liquid protective film material is applied to the processing target 2.
[0034]
Although the protective film 7 has the same outer diameter as the object 2 to be processed, it is needless to say that the protective film 7 is not limited to this. Although the protective film 7 is adhered to the pattern surface of the processing target 2, the effect of the present invention can be obtained even if the protective film 7 is adhered to the pattern back surface.
[0035]
Although the object holding apparatus 1 in the above embodiment is provided in a plasma etching apparatus, it goes without saying that the object holding apparatus 1 can be applied to a semiconductor manufacturing apparatus other than the plasma etching apparatus, for example, CVD.
[0036]
【The invention's effect】
As described above in detail, according to the apparatus of the present invention, since the protective film covering the electrode and made of a dielectric is formed on the surface of the electrode other than the mounting surface of the object to be processed, the object to be processed is In addition to preventing a decrease in heat conduction between the electrodes, a dielectric covering the electrodes is not required, and the cost of parts can be reduced.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view illustrating a schematic configuration of a workpiece holding device including an electrostatic chuck according to an embodiment of the present invention.
FIG. 2 is a longitudinal sectional view showing a modification of the electrostatic suction device in FIG.
FIG. 3 is a longitudinal sectional view showing a schematic configuration of a processing target object holding device including a conventional electrostatic suction device.
[Explanation of symbols]
1, 21 Workpiece holding device 2, 22 Workpiece 3, 23 Base member 4, 24 Electrostatic attraction device 5, 25 Electrode 6, 26 Protective film 7, 27 Protective film

Claims (5)

An electrostatic attraction device that includes an electrode and a protective film that covers the electrode and is made of a dielectric material, and that holds the object to be processed by electrostatic force, wherein the protective film is a mounting surface of the electrode on which the object to be processed is placed. An electrostatic attraction device characterized by being formed on a surface other than the surface. The electrostatic attraction device according to claim 1, wherein a protection film made of a dielectric is adhered to a surface of the object to be bonded to the electrode. 3. The electrostatic chuck according to claim 1, wherein the dielectric is made of one of quartz, polyimide resin, and ceramic. 4. The electrostatic chuck according to claim 1, wherein the object to be processed is a semiconductor wafer having a thickness of 50 to 100 μm. 5. 5. The electrostatic attraction device according to claim 2, wherein the protection film is formed on a surface of the object on which a circuit pattern is formed. 6.

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