KR20100090561A - Electrostatic chuck having junction structure between different materals and fabrication method thereof - Google Patents

Abstract

PURPOSE: An electrostatic chuck including a junction structure between different materials and a method for manufacturing the same are provided to increase the junction strength by eliminating voids while a dielectric plate and an insulating plate are combined. CONSTITUTION: The surface roughness of a junction surface on a dielectric plate is between 0.5 and 1.0um. An insulating plate(102) is combined with the dielectric plate. A material forming the insulating plate is different from a material forming the dielectric plate. An electrode(101) is installed between the dielectric plate and the insulating plate or is installed inside the dielectric plate. The dielectric plate is composed of ceramics. The insulating plate is composed of a polymeric film.

Description

ELECTROSTATIC CHUCK HAVING JUNCTION STRUCTURE BETWEEN DIFFERENT MATERALS AND FABRICATION METHOD THEREOF}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic chuck, and more particularly, to an electrostatic chuck having an improved structure of an electrostatic plate for generating an electrostatic force for adsorbing a substance to be adsorbed, and a manufacturing method thereof.

An electrostatic chuck is a mechanism that adsorbs a substance to be adsorbed by using electrostatic force, and is widely used for fixing or moving a semiconductor substrate or a glass substrate for a display by chucking. In addition, the electrostatic chuck is applied to a plasma processing apparatus for forming or etching a thin film using plasma gas to provide wafer temperature control and chucking functions.

1 is a main configuration diagram of a general ceramic electrostatic chuck. As shown in FIG. 1, the electrostatic chuck has an electrostatic plate 10 having a metal electrode 13 in the form of a plate therein.

The electrostatic plate 10 includes a dielectric layer 11 positioned above and an insulating layer 12 positioned below the electrode 13, and a DC power supply 20 is connected to the electrode 13. .

Typically, the electrostatic plate 10 is manufactured integrally by inserting a high melting electrode 13 between the dielectric layer 11 and the insulating layer 12 and then sintering the ceramic at a high temperature of 1500 ° C. or higher. Here, the dielectric layer 11 and the insulating layer 12 are formed of the same ceramic.

According to the above configuration, when the substrate to be adsorbed is placed on the upper surface of the electrostatic plate 10 and a high voltage DC power is supplied, polarization occurs in the dielectric layer 11, and in this process, the surface of the electrostatic plate 10 Electrostatic charges are induced on the surface of the substrate so that the substrate is tightly absorbed and fixed to the top surface of the electrostatic plate 10 by the Coulomb force or the Johnsonsen-Rahbek force.

As shown in FIG. 2, the electrostatic plate 10 is generally used in the form of being bonded on the lower support 14 made of metal. When the electrostatic chuck is applied to the plasma processing apparatus, the DC power supply device 20 and the high frequency power supply device 30 for generating plasma are connected to the electrode 13 and the lower supporter 14 in the electrostatic plate 10, respectively. In this case, the electrostatic chuck may provide an electrostatic attraction force for tightly fixing the substrate and may serve as a bias electrode opposite to the electrode for generating plasma.

However, the conventional electrostatic plate 10 having the structure as described above is inconvenient to perform sintering two or more times in order to insert the electrode 13 therein, and between the dielectric layer 11 and the insulating layer 12 As shown in FIG. 3, a camber phenomenon in which the electrode 13 is warped and deformed due to a difference in thermal expansion coefficient between the electrostatic plate 10 and the electrode 13 may occur during sintering. .

Since the ceramic in the molded state shrinks by 20 to 30% or more during the sintering process, a shrinkage difference with the electrode 13 occurs, and thus the camber phenomenon of the electrode 13 is a problem inevitably occurring in the ceramic electrostatic plate 10. can do.

On the other hand, even if the ceramic is sintered to increase the density no matter how high the withstand voltage to 20V / ㎛ or more, there is a limit that the insulating layer 12 must maintain a thickness of at least 0.3mm. In addition, if the thickness of the insulating layer 12 is too thick, a fatal problem that cannot effectively transfer the temperature maintained by the lower support 14 to the adsorbed material placed on the electrostatic chuck.

As the public technical literature related to the structure improvement of the electrostatic chuck, Korean Patent Publication No. 2007-0106782, Patent Publication No. 1992-10714, etc. may be mentioned.

Patent Publication No. 2007-0106782 discloses a structure in which a metal plate having an insulator film formed on an upper surface by a thermal spray and a dielectric substrate having an electrode formed on an under surface thereof are bonded to each other through an insulating adhesive so that the insulator film and the electrode face each other. Through this, the electrostatic chuck which can improve plasma resistance and cooling performance is disclosed.

In Patent Publication No. 1992-10714, an electrode is provided between a first insulating layer and a second insulating layer or in a first insulating layer, and an adhesive layer of an organic material for bonding the first insulating layer and the second insulating layer is provided. An electrostatic chuck having a configuration in which an adsorbed body is positioned on a second insulating layer is disclosed. In addition, Korean Patent Publication No. 1992-10714 includes an electrostatic adsorption sheet having an adhesive layer of an organic material and a gas inlet for adhering a first insulating layer and a second insulating layer. Disclosed is an electrostatic chuck which supplies a gas for heat transfer between adsorption sheets.

As described above, the electrostatic chuck in which the adhesive is bonded between the substrates or the insulating layers by the adhesive needs to sufficiently secure the bonding strength, and a method for removing bubbles inevitably remaining at the interface during the bonding is required. In particular, if bubbles remain inside the electrostatic chuck after the joining process, a channel through which gas flows may be formed in the joining portion, and leakage of the cooling gas may occur. In the case of supplying the cooling gas from the lower part of the electrostatic chuck to the upper part, a fatal problem occurs that leaks from the joint and loses the cooling function before reaching the upper surface of the electrostatic chuck.

The present invention has been devised to solve the above problems, the upper and lower portions of the electrostatic plate relative to the electrode formed of a heterogeneous material is easy to control the physical properties, the electrostatic plate so that sufficient bonding strength can be given An object of the present invention is to provide an electrostatic chuck with improved internal structure and a method of manufacturing the same.

Another object of the present invention is to provide a method of manufacturing an electrostatic chuck which can bond dielectric elements and insulator elements constituting an electrostatic plate through a low temperature process, and can effectively remove bubbles generated during the bonding process.

In order to achieve the above object, the electrostatic chuck according to the present invention includes a dielectric plate having a surface roughness Ra of a bonding surface of 0.5 to 1.0 μm; An insulator plate bonded to the dielectric plate and formed of a different material from the dielectric plate; And an electrode provided between the dielectric plate and the insulator plate or inside the insulator plate.

Preferably, the dielectric plate is formed of a ceramic, and the insulator plate is formed of a polymer film.

As the ceramic, alumina (Al ₂ O ₃ ), aluminum nitride (AlN) or yttria (Y ₂ O ₃ ) may be selected.

It is preferable that the said polymer film is a polyimide film.

The volume resistance of the dielectric plate is preferably 10 ⁹ to 10 ¹⁷ Ω · cm.

The dielectric plate may be formed to a thickness of 0.5 ~ 3mm.

It is preferable that the said insulator plate has a withstand voltage at 200 V / micrometer or more, and a volume resistance is 10 ¹⁶ ohm * cm or more.

The electrode may be formed to a thickness within 50㎛.

The electrostatic chuck according to the present invention may further include a lower support joined to a lower portion of the insulator plate. Preferably, the insulator plate and the lower supporter are joined by a viscous gel type adhesive.

According to another aspect of the present invention, a method of manufacturing an electrostatic chuck for adsorbing an adsorbate using electrostatic force, the method comprising the steps of: (a) preparing a dielectric plate; (b) preparing an insulator plate having an electrode pattern formed thereon; And (c) injecting the dielectric plate and the insulator plate into an auto clave, and then joining the dielectric plate and the insulator plate while removing bubbles to provide a method of manufacturing an electrostatic chuck. do.

In the step (a), it is preferable to process the bonding surface to be bonded to the insulator plate in the dielectric plate so that the surface roughness Ra is 0.5 to 1.0 μm.

In the step (a), the dielectric plate is preferably formed by sintering any one ceramic selected from alumina (Al ₂ O ₃ ), aluminum nitride (AlN) and yttria (Y ₂ O ₃ ).

In the step (b), the insulator plate on which the electrode pattern is formed is preferably manufactured by bonding a thin plate-shaped electrode to a polyimide film or depositing an electrode material on a polyimide film.

In step (c), a curing process may be performed at a pressure of 50 psi or more and a temperature of 80 ° C. or more.

According to another aspect of the present invention, a method of manufacturing an electrostatic chuck for adsorbing an adsorbate using electrostatic force, the method comprising the steps of: (a) preparing a dielectric plate; (b) preparing an insulator plate having an electrode pattern formed thereon; And (c) bonding the dielectric plate and the insulator plate to each other. In the step (a), the surface roughness Ra of the dielectric plate bonded to the insulator plate in the dielectric plate is 0.5 to 1.0 μm. There is provided a manufacturing method of an electrostatic chuck, which is processed to be.

An electrostatic chuck having a junction structure between dissimilar materials according to the present invention and a method of manufacturing the same provide the following effects.

First, since the dielectric plate and the insulator plate can be made of different materials, a ceramic having a high dielectric constant is used as the dielectric plate and a polymer such as polyimide having voltage resistance, high resistance, and uniformity of thickness as the insulator plate. Material can be used.

Second, since the high temperature sintering is performed only during the molding of the dielectric plate, the manufacturing process may be simplified to increase productivity, and the high temperature sintering process for the electrode may be omitted, thereby preventing the camber phenomenon of the electrode.

Third, since the thickness of the insulator plate located under the electrode can be made very thin, the heat exchange efficiency with the cooling means provided from the lower support can be increased.

Fourth, since the bonding strength can be increased by removing bubbles at the time of bonding between the dielectric plate and the insulator plate, formation of a channel causing leakage of cooling gas can be suppressed.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in the specification and claims should not be construed as having a conventional or dictionary meaning, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention. Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention and do not represent all of the technical idea of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

4 is a cross-sectional view showing the main configuration of the electrostatic chuck in accordance with a preferred embodiment of the present invention.

Referring to FIG. 4, the electrostatic chuck bonds the dielectric plate 100, the insulator plate 102 having the electrode 101 formed thereon, the dielectric plate 100, and the insulator plate 102 on the upper surface thereof. An electrostatic plate comprising an adhesive layer 103 is provided.

The dielectric plate 100 is preferably formed of a ceramic material having excellent dielectric properties such as alumina (Al ₂ O ₃ ), aluminum nitride (AlN), yttria (Y ₂ O ₃ ), and the like. In order to effectively control the Coulomb force or the Johnsonsen-Rahbek force that may be provided by the dielectric plate 100, the volume resistance of the dielectric plate 100 is 10 ⁹ to 10 ¹⁷ Ω · cm, It is preferable that thickness is 0.5-3 mm.

The dielectric plate 100 has a structure that is machined such that the lower surface corresponding to the bonding surface has a surface roughness Ra of 0.5 to 1.0 μm. According to this structure, sufficient bonding strength may be provided when the dielectric plate 100 and the electrode 101 / insulator plate 102 are bonded through the adhesive layer 103. If the condition of the surface roughness (Ra) is not satisfied, not only the bonding strength may be poor, but the dielectric properties of the dielectric plate 100 and the uniformity of the electrostatic force may be deteriorated.

The insulator plate 102 is formed of a film by a polymer material. Here, it is preferable that a polyimide film having excellent breakdown voltage is used as the polymer film. Although the structure in which the electrode 101 is formed on the surface of the insulator plate 102 is shown in the drawing, it is also possible to alternatively install the electrode 101 inside the insulator plate 102.

In order to effectively prevent the occurrence of dielectric breakdown in providing an electrostatic force for adsorbing a semiconductor substrate or a glass substrate, the insulator plate 102 has a voltage resistance at 200 V / µm or more, and a volume resistance of 10 ¹⁶ Ω · cm or more. desirable.

The electrode 101 is formed in a predetermined pattern by metals such as copper, gold, and silver having excellent conductivity. In order to increase the adhesion between the dielectric plate 100 and the insulator plate 102, the electrode 101 is preferably formed to a thickness within 50㎛. The electrode 101 is provided in a thin plate form and bonded to the insulator plate 102 by a silicone-based or acrylic-based adhesive, or formed by depositing an electrode material on the insulator plate 102 by vacuum sputtering or the like.

In order to connect the DC power supply 250 to the electrode 101, a predetermined through hole 102a is preferably formed at one side of the insulator plate 102.

The adhesive layer 103 for bonding the dielectric plate 100 and the insulator plate 102 is preferably formed of a silicon-based thin plate adhesive, but is not limited thereto.

5 shows a process of manufacturing an electrostatic chuck in accordance with a preferred embodiment of the present invention.

Referring to FIG. 5, the manufacturing process of the electrostatic chuck according to the preferred embodiment of the present invention includes preparing a insulator plate 102 having a dielectric plate 100 and an electrode 101, and an insulator plate 102. A step (b) of applying an adhesive thereon and a step (c) of bonding the dielectric plate 100 and the insulator plate 102 in the vacuum autoclave 200.

In the manufacturing process of the dielectric plate 100, the ceramic corresponding to alumina (Al ₂ O ₃ ), aluminum nitride (AlN) or yttria (Y ₂ O ₃ ) is sintered to form a plate having a thickness of 0.5 ~ 3㎜ Do the work. As the sintering process, a conventional tape casting method or a pressure sintering method may be adopted. In order to effectively control the Coulomb force or the Johnson-Rahbek force, the dielectric plate 100 is preferably molded to have a volume resistance of 10 ⁹ to 10 ¹⁷ Ω · cm. After the sintering process, the joint surface of the dielectric plate 100 to be bonded with the insulator plate 102 is mechanically processed so that the dielectric plate 100 having the surface treatment part 100a having a surface roughness Ra of 0.5 to 1.0 μm. ).

In the manufacturing process of the insulator plate 102, the operation | work which forms the electrode 101 pattern in a polyimide film is performed. As a method of forming the electrode 101, a thin plate made of a metal having excellent conductivity such as copper, gold, silver, or the like is bonded to the surface of the insulator plate 102 using a silicon-based or acrylic-based thin plate adhesive, or a vacuum sputtering method A technique of depositing an electrode material on a polyimide film may be employed.

After preparing the dielectric plate 100 and the insulator plate 102, a silicone-based adhesive is applied on the electrode 101 of the insulator plate 102 to form an adhesive layer 103, and then a general vacuum autoclave 200 is formed. The process of joining the dielectric plate 100 and the insulator plate 102 within is performed. Here, the process of forming the adhesive layer 103 may be performed in the vacuum autoclave 200.

In the bonding process using the vacuum autoclave 200, the two plates 100 and 102 are pressed together while removing air bubbles existing at the bonding interface between the dielectric plate 100 and the insulator plate 102. In the bonding process, it is preferable to perform a curing treatment at a pressure of 50 Psi or more and a temperature of 80 ° C. or more for effective adhesion between the plates 100 and 102.

The electrostatic chuck manufactured by the above process is to put the adsorbed material corresponding to the semiconductor substrate or the glass substrate on the upper surface of the dielectric plate 100 when the high voltage DC power is supplied to the surface of the dielectric plate 100 and the adsorption Electrostatic charges of different polarities are induced on the surface of the water, and the Coulomb force or the Johnson-Rahbek force acts to closely adsorb the substance on the top surface of the dielectric plate 100 to fix it.

As shown in FIG. 6, the dielectric plate 100 is bonded to the lower support 104 made of metal by a silicone-based adhesive or an acrylic-based adhesive in the form of a gel having viscosity. According to this structure, it is possible to buffer thermal stress caused by the difference in coefficient of thermal expansion between different materials. When the electrostatic chuck is applied to the plasma processing apparatus, the DC power supply 250 and the high frequency power supply 300 for plasma generation are connected to the electrode 101 and the lower support 104 of the insulator plate 102, respectively. In this case, the electrostatic chuck may provide an electrostatic adsorption force for tightly fixing the adsorbate, and may serve as a bias electrode opposite to the electrode for generating plasma.

Although the present invention has been described above by means of limited embodiments and drawings, the present invention is not limited thereto and will be described below by the person skilled in the art to which the present invention pertains. Of course, various modifications and variations are possible within the scope of the claims.

The following drawings, which are attached to this specification, illustrate preferred embodiments of the present invention, and together with the detailed description of the present invention serve to further understand the technical spirit of the present invention, the present invention includes matters described in such drawings. It should not be construed as limited to.

1 is a cross-sectional view showing the main configuration of a ceramic electrostatic chuck according to the prior art.

2 is a cross-sectional view showing the main configuration of a ceramic electrostatic chuck applied to the plasma processing apparatus.

3 is a cross-sectional view illustrating an example in which the metal electrode of FIG. 1 is modified by a camber phenomenon.

4 is a cross-sectional view showing the main configuration of the electrostatic chuck in accordance with a preferred embodiment of the present invention.

5 is a process chart showing the manufacturing process of the electrostatic chuck in accordance with a preferred embodiment of the present invention.

6 is a cross-sectional view showing the main configuration of an electrostatic chuck according to a preferred embodiment of the present invention applied to a plasma processing apparatus.

<Description of Major Reference Marks in Drawings>

100 dielectric plate 101 electrode

102: insulator plate 103: adhesive layer

104: lower support 200: vacuum autoclave

250: DC power supply device 300: high frequency power supply device

Claims (15)

An electrostatic chuck for adsorbing a substance to be adsorbed using electrostatic force, A dielectric plate having a surface roughness Ra of the bonding surface of 0.5 to 1.0 µm; An insulator plate bonded to the dielectric plate and made of a different material from the dielectric plate; And And an electrode provided between the dielectric plate and the insulator plate or inside the insulator plate. The method of claim 1, The dielectric plate is formed of a ceramic, and the insulator plate is formed of a polymer film. The method of claim 2, The ceramic is an electrostatic chuck, characterized in that any one selected from alumina (Al ₂ O ₃ ), aluminum nitride (AlN) and yttria (Y ₂ O ₃ ). The method of claim 2, The polymer film is an electrostatic chuck, characterized in that the polyimide film. The method of claim 1, An electrostatic chuck, wherein the volume resistance of the dielectric plate is 10 ⁹ to 10 ¹⁷ Ω · cm. The method of claim 1, Electrostatic chuck characterized in that the thickness of the dielectric plate is 0.5 ~ 3mm. The method of claim 1, The insulator plate has a withstand voltage at 200 V / µm or more, and has a volume resistance of 10 ¹⁶ Ω · cm or more. The method of claim 1, The electrode has a thickness within 50 μm. The method of claim 1, A lower supporter joined to a lower portion of the insulator plate; Electrostatic chuck is characterized in that the insulator plate and the lower support is bonded by a viscous gel-type bonding agent. In the manufacturing method of the electrostatic chuck to adsorb the object to be adsorbed using an electrostatic force, (a) preparing a dielectric plate; (b) preparing an insulator plate having an electrode pattern formed thereon; And (c) injecting the dielectric plate and the insulator plate into an auto clave, and then joining the dielectric plate and the insulator plate while removing air bubbles. The method of claim 10, wherein in step (a), The method of manufacturing an electrostatic chuck, characterized in that for processing the surface of the dielectric plate bonded to the insulator plate so that the surface roughness (Ra) is 0.5 ~ 1.0㎛. The method of claim 10 or 11, wherein in step (a), A method of manufacturing an electrostatic chuck, wherein the dielectric plate is formed by sintering any ceramic selected from alumina (Al ₂ O ₃ ), aluminum nitride (AlN), and yttria (Y ₂ O ₃ ). The method of claim 10 or 11, wherein in step (b), A method of manufacturing an electrostatic chuck, comprising: bonding an electrode in the form of a sheet to a polyimide film or depositing an electrode material on a polyimide film to form an insulator plate having the electrode pattern. The method of claim 10 or 11, wherein in step (c), A process for producing an electrostatic chuck, characterized in that a curing process is performed at a pressure of 50 psi or higher and a temperature of 80 ° C. or higher. In the manufacturing method of the electrostatic chuck to adsorb the object to be adsorbed using an electrostatic force, (a) preparing a dielectric plate; (b) preparing an insulator plate having an electrode pattern formed thereon; And (c) joining the dielectric plate and the insulator plate; In step (a), The method of manufacturing an electrostatic chuck, characterized in that for processing the bonding surface to be bonded to the insulator plate in the dielectric plate so that the surface roughness (Ra) is 0.5 ~ 1.0㎛.

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