KR100706021B1 - Method for manufacturing esc - Google Patents

Abstract

The present invention relates to a method of manufacturing an electrostatic chuck for fixing a silicon wafer or a glass substrate.

In the present invention,

1) forming an electrode from a conductive metal whose top surface is flat;

2) a pretreatment step of heating the upper surface of the metal to a high temperature;

3) forming an insulating layer on the upper surface of the metal by a spray coating method;

4) forming a lower dielectric layer on the upper surface of the insulating layer by thermal spray coating;

5) an electrode pattern forming step of forming an electrode pattern of a predetermined pattern on the upper surface of the lower dielectric layer by a spray coating method;

6) forming an upper dielectric layer on the upper surface of the lower dielectric layer and the upper surface of the electrode pattern by a spray coating method.

Electrostatic chuck, electrode, insulation layer, thermal spray coating, plasma

Description

Electrostatic chuck manufacturing method {METHOD FOR MANUFACTURING ESC}

1 is a cross-sectional view schematically illustrating the structure of an electrostatic chuck.

2 is a process chart of a conventional electrostatic chuck manufacturing method.

3 is a cross-sectional view schematically showing the structure of a conventional thermal spray coating surface.

4 is a process chart of the electrostatic chuck manufacturing method according to an embodiment of the present invention.

5 is a cross-sectional view schematically showing a contact surface of an electrode and an insulating layer coated according to an embodiment of the present invention.

<Description of Symbols for Major Parts of Drawings>

1 electrostatic chuck 10 electrode

20: insulating layer 30: lower dielectric layer

40: electrode pattern 50: upper dielectric layer

D: residue

The present invention relates to a method of manufacturing an electrostatic chuck for fixing a silicon wafer or a glass substrate.

In recent years, with the rapid spread of information media such as computers, semiconductors and LCDs are rapidly developing. In the semiconductor and LCD manufacturing process, as the amount of information processed increases rapidly, technology is being developed to improve integration and reliability.

However, in order to improve the integration and reliability, the precision of the unit process must be increased, and to increase the precision of the unit process, it is required to more accurately fix the semiconductor wafer and the LCD substrate during the unit process. Generally, a device for fixing a semiconductor wafer and an LCD substrate includes a vacuum chuck for fixing a wafer using mechanical properties and an electrostatic chuck (ESC) for fixing a wafer using electrical properties. This is widely used.

The vacuum chuck has a limitation in use because no pressure difference is generated between the vacuum chuck and the external vacuum when the unit processes are performed under vacuum conditions. In addition, since the wafer or substrate is fixed by the local suction action, there is a drawback in that precise fixing is impossible.

Electrostatic chucks, on the other hand, use the principles of dielectric polarization and electrostatic forces generated by potential differences to fix adsorbates such as substrates. This allows the electrostatic chuck to be subjected to microfabrication of a semiconductor or LCD substrate without being affected by pressure.

As an example of an electrostatic chuck, US Pat. No. 6,134,096 discloses an electrostatic chuck consisting of an insulating layer, an electrode layer, and a dielectric layer for adsorbing a substrate using electrostatic energy. In addition, US Pat. No. 6,141,203 discloses an electrostatic chuck that forms a capacitor plate having a plurality of structures to adsorb a substrate with electrostatic energy.

Hereinafter, a general electrostatic chuck will be described with reference to FIG. 1. 1 is a cross-sectional view schematically showing the electrostatic chuck 1.

First, a metal electrode 10 is formed at the lowermost portion. This electrode 10 is a component to which RF power is applied for plasma processing. Therefore, it is formed of a conductive material. The insulating layer 20 is formed on the electrode 10. The insulating layer 20 is for preventing electrical contact between the electrode to which the RF power is applied and the electrostatic chuck electrode pattern 40 to which the DC power is applied for the electrostatic chuck operation. AlN (aluminum nitride) is widely used as the insulating layer 20, and is formed by a spray coating method.

The lower dielectric layer 30 is formed on the insulating layer 20. The lower dielectric layer 30 has a structure surrounding the electrode pattern 40 formed thereon from below, and is also formed by a spray coating method. In addition, a specific electrode pattern 40 is formed on the lower dielectric layer 30. The electrode pattern 40 is a component to which a DC power source for driving an electrostatic chuck is applied, and is patterned in a predetermined shape according to the shape of a member to be fixed by the electrostatic chuck. Next, an upper dielectric layer 50 is formed on the electrode pattern 40. The upper dielectric layer 50 is provided in a structure surrounding the electrode pattern on the top, and is formed by a spray coating method. More precisely, the electrode pattern 40 is floating between the lower dielectric layer 30 and the upper dielectric layer 50. Therefore, the electrode pattern 40 is not exposed to the outside, but takes the form of being entirely covered by the dielectrics 30 and 50. The pinned member is positioned and fixed on the upper surface of the upper dielectric layer 50.

Hereinafter, a method of manufacturing such an electrostatic chuck will be described with reference to FIG. 2. 2 is a process chart of a conventional electrostatic chuck manufacturing method.

First, a step (S 10) of forming a metal electrode is performed. At this time, the electrode has a circular shape when processing a circular semiconductor wafer, and a rectangular shape when processing a rectangular flat panel display element substrate. Next, the process (S20) of removing the foreign material on the upper surface of this electrode is advanced. In this process, a process of pretreating the upper surface of the electrode in order to improve the adhesion of the coated insulating layer before the thermal spray coating on the electrode, and removes foreign substances on the electrode by sanding or chemical cleaning process. Next, an insulating layer formation process (S30) advances. In this process, an insulating layer is formed using a thermal spray coating method. The insulating layer has a plate shape and is generally formed to a thickness of about 80 m.

Next, a process (S 40) of forming a lower dielectric layer on the insulating layer is performed. In this process, the insulating layer is formed by a spray coating method, and generally, the lower dielectric layer is formed to a thickness of 500 mu m. In operation S50, an electrode pattern is formed on the lower dielectric layer. In this step, electrodes are formed in a desired pattern shape. This electrode pattern takes the shape of a thin plate and is generally formed to a thickness of about 20 mu m. The electrode pattern is formed of tungsten material.

Next, a process (S 60) of forming an upper dielectric layer on the electrode pattern is performed. In this process, the upper dielectric layer is formed using a thermal spray coating method to completely surround the electrode pattern formed on the lower dielectric layer. The upper dielectric layer is generally formed to a thickness of about 400 mu m.

However, in the case of simply sanding the surface or performing only a chemical cleaning process in the sprayed surface cleaning process, which is conventionally performed before forming an insulator layer using the sprayed coating method on the electrode, as illustrated in FIG. 3, the electrode ( 10) Between the surface and the sprayed surface 20, there is a problem in that moisture in the air or the residue D of the cleaning process is interposed to impair the function of the electrostatic chuck.

It is an object of the present invention to provide an electrostatic chuck manufacturing method in which a functional problem does not occur even when an insulating layer is formed by spray coating at a high temperature of 1000 ° C. or higher.

In the present invention, to achieve the above object,

1) forming an electrode from a conductive metal whose top surface is flat;

2) a pretreatment step of heating the upper surface of the metal to a high temperature;

3) forming an insulating layer on the upper surface of the metal by a spray coating method;

4) forming a lower dielectric layer on the upper surface of the insulating layer by thermal spray coating;

5) an electrode pattern forming step of forming an electrode pattern of a predetermined pattern on the upper surface of the lower dielectric layer by a spray coating method;

6) forming an upper dielectric layer on the upper surface of the lower dielectric layer and the upper surface of the electrode pattern by a spray coating method.

In the present invention, in step 2), pretreatment by heating the electrode at a temperature of 800 to 1200 ° C. is preferable because it can completely remove moisture in the air or residues on the metal surface.

In the present invention, it is preferable to form the electrode from aluminum because the weight of the device can be reduced while ensuring sufficient conductivity.

The insulating layer is preferably made of aluminum nitride (AlN) because it can secure all of electrostatic power, thermal conductivity, and plasma resistance.

And in the present invention, before the surface of the electrode is pretreated to a high temperature. The cleaning step of removing foreign matters from the upper surface of the electrode is further preferred, since the adhesion between the upper surface of the electrode and the insulating layer may be improved.

In this case, in the cleaning step, the electrode surface may be sanded , or the surface of the electrode may be chemically cleaned to remove foreign substances.

Hereinafter, with reference to the accompanying drawings will be described in detail a specific embodiment of the present invention.

Electrostatic chuck manufacturing method according to the embodiment

1) forming an electrode from a conductive metal having a flat upper surface (S110);

2) a pretreatment step of heating the metal upper surface to a high temperature (S130);

3) forming an insulating layer on the upper surface of the metal by a spray coating method (S140);

4) forming a lower dielectric layer on the upper surface of the insulating layer by a spray coating method (S150);

5) an electrode pattern forming step (S160) of forming an electrode pattern of a predetermined pattern on the upper surface of the lower dielectric layer by a spray coating method;

6) forming an upper dielectric layer on the upper surface of the lower dielectric layer and the upper surface of the electrode pattern by a spray coating method (S170).

Here, steps 1), 3), 4), 5), and 6) are the same processes as those of the conventional method for manufacturing an electrostatic chuck, and thus will not be repeated here.

In the method of manufacturing an electrostatic chuck according to the present embodiment, a predetermined pretreatment 130 is performed on the upper portion of the electrode before forming the insulating layer on the upper portion of the electrode (S130). This is to remove moisture from the process residue or air present on the upper surface of the electrode. In this embodiment, a high temperature treatment is performed in which the electrode is heated to a temperature of 800 to 1200 ° C in this pretreatment step. The high temperature treatment is pretreatment at a temperature similar to that of the thermal spray coating process so that moisture is not present on the surface of the electrode during the thermal spray coating process performed at 800 to 1200 ° C. At this time, the electrode is preferably made of a metal material, and particularly preferably aluminum that can ensure both conductivity and light weight.

The insulating layer is preferably made of aluminum nitride because it can secure all of electrostatic power, thermal conductivity, and plasma resistance. Since these electrostatic chucks are used in dry processes, accurate and uniform heating / cooling, temperature distribution and electrostatic power under vacuum are required to reduce film uniformity, thermal stress and defect density. Therefore, a material having excellent dielectric properties and thermal conductivity should be used. In this regard, aluminum nitride is most preferable as an insulating layer.

Also in the electrostatic chuck manufacturing method according to the present embodiment, a cleaning step (S120) for removing foreign matter on the upper surface of the electrode between 1) the electrode forming step (S110) and 2) the spray surface pretreatment step (S130) is It is preferable to further advance because the bonding force between the electrode and the insulating layer can be further improved. In this embodiment, the cleaning step proceeds to a sanding process of the metal surface or a chemical cleaning of the metal surface.

According to the present invention, since the metal surface is pretreated at a high temperature before the insulating layer is formed by the spray coating method, as shown in FIG. 5, all moisture in the air and residues from the cleaning process are removed to improve the bonding strength between the electrode and the insulating layer. In addition to improving the characteristics of the electrostatic chuck itself has the advantage.

Claims (7)

In the electrostatic chuck manufacturing method comprising the electrode forming, insulating layer forming, dielectric layer forming and electrode pattern forming step, 1) a cleaning step of removing foreign substances on the electrode upper surface between the electrode forming step and the insulating layer forming step; And 2) a pre-treatment step of heating the upper surface of the electrode to a high temperature; electrostatic chuck manufacturing method comprising a. The method of claim 1, wherein in step 2), Electrostatic chuck manufacturing method characterized in that for heating the electrode to 800 ~ 1200 ℃ temperature. delete delete delete delete The method of claim 1, wherein the cleaning step, Electrochemical chuck manufacturing method characterized in that the step of chemically washing the metal surface.

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