KR20110099567A - An electrostatic chuck - Google Patents

Abstract

An electrostatic chuck which minimizes the occurrence of stress in a portion where the base member and the first insulating layer are in contact is disclosed. To this end, the electrostatic chuck includes a base member, a first insulating layer formed on the base member, an electrode layer formed on the first insulating layer, and a second insulating layer formed on the electrode layer, wherein the base member is formed of a first material. And a second base portion formed on the first base portion and a second material formed on the first base portion and having a lower thermal expansion coefficient than the first material. Accordingly, even if the electrostatic chuck receives heat and thermally expands the first insulating layer and the second base portion, the thermal expansion coefficient of the second base portion is smaller than that of the first base portion. Therefore, since the difference in thermal expansion rate can be minimized as compared with the case where the first insulating layer is formed on the first base portion, the second base is minimized by minimizing the stress generated at the portion where the second base portion and the first insulating layer are in contact. It is possible to prevent cracks or damage to the first insulating layer having a smaller rigidity than the negative portion.

Description

Electrostatic chuck

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic chuck, and more particularly, to an electrostatic chuck included in a substrate processing apparatus for treating a surface of a substrate and adsorbing a substrate.

In general, in the process of manufacturing a semiconductor wafer or flat panel display, various surface treatment processes such as deposition are repeatedly performed. These surface treatment processes are performed in a substrate processing apparatus, and an electrostatic chuck for adsorbing the object to be processed is disposed inside the substrate processing apparatus. Such an electrostatic chuck adsorbs a target object by electrostatic force. The structure of the electrostatic chuck forms a first insulating layer on the metal substrate. It is common to form a metal electrode layer on the first insulating layer and to form a second insulating layer on the metal electrode layer.

Meanwhile, heat may be generated inside the substrate treating apparatus while the surface of the object is processed by the substrate treating apparatus. Accordingly, heat is also transferred to the electrostatic chuck disposed in the substrate processing apparatus, so that the temperature inside the electrostatic chuck rises to a specific temperature, and the metal base material and the insulating layer are thermally deformed by this heat. Here, it is common for the metal base material and the insulating layer to have different thermal expansion coefficients. Therefore, the displacement in which the metal base material is deformed by heat and the displacement in which the insulating layer is deformed by heat are different. Therefore, stress due to the difference in thermal expansion is generated in a portion where the metal base material and the insulating layer contact, there is a problem that cracks or breakage occurs in the insulating layer.

An object of the present invention is to provide an electrostatic chuck which can minimize the occurrence of stress at the portion where the metal base material and the insulating layer contact.

The electrostatic chuck according to the present invention for achieving the above object includes a base member, a first insulating layer formed on the base member, an electrode layer formed on the first insulating layer, and a second insulating layer formed on the electrode layer; The base member includes a first base part made of a first material and a second base part made of a second material formed on the first base part and having a lower coefficient of thermal expansion than the first material.

In the electrostatic chuck according to the present invention, even if the electrostatic chuck receives heat in the process of processing the object to be treated and thermally expands the first insulating layer and the second base portion, the thermal expansion rate of the second base portion is smaller than that of the first base portion. . Therefore, since the difference in thermal expansion rate can be minimized as compared with the case where the first insulating layer is formed on the first base portion, the second base is minimized by minimizing the stress generated at the portion where the second base portion and the first insulating layer are in contact. It is possible to prevent cracks or damage to the first insulating layer having a smaller rigidity than the negative portion.

1 is a cross-sectional view showing a substrate processing apparatus including an electrostatic chuck in accordance with a preferred embodiment of the present invention.
2 is a vertical cross-sectional view of an electrostatic chuck in accordance with a preferred embodiment of the present invention.

Hereinafter, the technical configuration of the present invention according to the accompanying drawings in detail.

Referring to FIG. 1, the electrostatic chuck 100 according to an exemplary embodiment of the present invention may include a base member 110, a first insulating layer 120, an electrode layer 130, and a second insulating layer 140. It includes.

The base member 110 forms the body of the electrostatic chuck 100. When the electrostatic chuck 100 of the present invention is applied to a substrate processing apparatus of a capacitively coupled plasma (CCP) method, a voltage having a single frequency or a dual frequency may be applied to the base member 110.

On the other hand, the base member 110 according to an embodiment of the present invention includes a first base member 111 and the second base member 112. The first base member 111 is made of a first material. The second base member 112 is formed on the first base member 111 and is made of a second material having a lower coefficient of thermal expansion than the first material. The first material constituting the first base member 111 and the second material constituting the second base member 112 will be described later. That is, in the electrostatic chuck of the present invention, the base member 110 is formed by forming a second base member 112 having a relatively low coefficient of thermal expansion on the first base member 111.

The first insulating layer 120 is formed to be in close contact with the outer surface of the base member 110. An example of a method in which the first insulating layer 120 is formed on the base member 110 may be formed by a plasma spray method.

The electrode layer 130 is formed on the upper surface of the first insulating layer 120. The electrode layer 130 receives electric power from a power source not shown to generate electrostatic power. For example, the electrode layer 130 may be any one or more metal layers selected from W, Al, Cu, Nb, Ta, Mo, Ni, and an alloy containing one or more of these metal elements. The thickness of the electrode layer 130 is preferably about 5㎛ 100㎛. If the thickness of the electrode layer 130 is less than 5 µm, it becomes porous and the conductivity as the electrode is extremely reduced. In addition, when the thickness of the electrode layer 130 exceeds 100 μm, the effect of improving the conductivity is not large, and only the thickness is excessively thick, thereby increasing the manufacturing cost.

The second insulating layer 140 is formed on the upper surface of the electrode layer 130. The first insulating layer 120 and the second insulating layer 140 are formed on the upper and lower surfaces of the electrode layer 130, respectively, and require electrical insulation, corrosion resistance, and plasma corrosion resistance. Therefore, the first insulating layer 120 and the second insulating layer 140 are preferably high in purity and dense. For this purpose, as an example of the material of the first insulating layer 120 and the second insulating layer 140 may be any one of Al ₂ O ₃ , ZrO ₂ , Si ₃ N ₄ SiC. The purity of the first insulating layer 120 and the second insulating layer 140 is 98.0% or more, more preferably 99.0% or more, and the porosity of the thermal spray coating is 1% to 8%, more preferably 1% to It is preferred to be within 5%. In addition, the thickness of the first insulating layer 120 and the second insulating layer 140 is preferably about 100㎛ to 500㎛. If the thickness of the first insulating layer 120 and the second insulating layer 140 is less than 100 μm, electrical insulation may be insufficient, and power applied to the electrode layer 130 may leak. In addition, when the thickness of the first insulating layer 120 and the second insulating layer 140 exceeds 500㎛, the electrical insulation is not significantly increased, the thickness is excessively thick and only the manufacturing cost may be increased. More preferably, the thickness of the first insulating layer 120 and the second insulating layer 140 is 130 μm to 400 μm, which may be more advantageous in reducing manufacturing costs while maintaining electrical insulation. The volume resistivity of the first insulating layer 120 and the second insulating layer 140 having the above structure may be approximately 1 × 10 ¹³ to 1 × 10 ¹⁵ Ω · cm.

Meanwhile, in the electrostatic chuck 100 of the present invention, the surface of the second insulating layer 140 in contact with the object G to be processed may be ground by machining (grinding) to be parallel to the object G. have. In particular, the mechanically ground second insulating layer 140 has a liquid organic silicon compound (organic silicon resin such as methyl silyl tri-isocyanate, phenyl silyl tri-isocyanate) or inorganic silicon compound on the ground surface. For example, after applying a silicon alkoxide compound and an alkali metal silicon compound), the sealing process can be performed by heating at 120 to 350 degreeC for about 1 to 5 hours. Such a sealing process may prevent the adhesion of foreign matters and prevent the intrusion of corrosive gas in the working environment by filling silicon compounds in the minute pores remaining in the second insulating layer 140. In addition, the sealing process may be applied to the first insulating layer 120 below the electrode layer 130.

In the electrostatic chuck 100 having the above structure, even if the first insulating layer 120 and the second base portion 112 are thermally expanded by receiving heat, the thermal expansion of the second base portion 112 is performed. The rate is smaller than the thermal expansion rate of the first base portion 111. Therefore, since the difference in thermal expansion rate can be minimized than when the first insulating layer 120 is formed on the first base 111, the second base 112 and the first insulating layer 120 are in contact with each other. By minimizing the stress generated in the portion, it is possible to prevent cracking or damage to the first insulating layer 120 having a smaller rigidity than the second base portion 112.

Meanwhile, as an example of the first material and the second material, the first material may be aluminum, and the second material may be titanium. The thermal expansion rate of titanium is about one third of that of aluminum. In addition, as another example of the first material and the second material, the first material may be aluminum, and the second material may be stainless steel. In addition, as another example of the first material and the second material, the first material may be stainless steel, the first material may be titanium. Here, the thermal expansion rate of aluminum is 23.8 μm / m- ° C. (@ 100 ° C.), the thermal expansion rate of titanium is 8.9 μm / m- ° C. (@ 100 ° C.), and the thermal expansion rate of stainless steel is 11 to 17.3 μm / m. -° C (@ ~ 350 ° C).

Meanwhile, in the manufacturing of the electrode layer 130, the first insulating layer 120 and the second insulating layer 140 described above, plasma spraying, high speed frame spraying, explosion spraying, arc spraying, atmospheric plasma spraying, and reduced pressure plasma spraying may be used. Can be.

On the other hand, the gas passage may be formed in the electrostatic chuck 100 of the present invention. The gas flow path is formed to penetrate the base member 110, the first insulating layer 120, the electrode layer 130, and the second insulating layer 140 in the vertical direction. Helium (He) gas may be supplied from the gas supply unit, which is not shown, through the gas passage. This helium gas is supplied to the object to be processed G, and the object to be processed G is maintained at a predetermined temperature by the helium gas.

Meanwhile, a plurality of protrusions 150 may be formed on the second insulating layer 140. The protrusions 150 are spaced apart from the electrostatic chuck 100 and the object G to be processed. The helium gas supplied toward the object G through the gas passage by the protrusions 150 may be uniformly moved over the entire surface of the object G. The protrusion 150 may be a ceramic excellent in durability and corrosion resistance. The protrusion 150 may be formed by spraying the second insulating layer 140 integrally, and the second insulating layer 140 is formed on the electrode layer 130 and then on the second insulating layer 140. It is also possible to form the protrusions 150 in a specific pattern.

Returning to FIG. 1, an example of a structure of a substrate processing apparatus including an electrostatic chuck having the above structure will be described.

The substrate processing apparatus 10 may include a chamber body 11, a dielectric plate 14, an antenna 15, and a gas supply unit (not shown).

In the chamber main body 11, a processing space 12 for processing the object G is formed. The chamber main body 11 is formed so that an upper surface may open. The processing space 12 of the chamber body 11 may be maintained in a vacuum state by a vacuum pump (not shown). The lead plate 13 is disposed above the chamber body 11. The lead plate 13 is formed to support at least a portion of the edge of the lower surface of the dielectric plate 14 upwardly so that at least a portion of the lower surface of the dielectric plate 14, which will be described later, is exposed into the chamber body 11. The lead plate 13 may be an integral member made of the same material as the chamber body 11, or may be manufactured and coupled to the chamber body 11 and the lead plate 13, respectively.

When the lead plate 13 and the chamber body 11 are manufactured, the first sealing member 18a may be interposed between the contact surfaces to which the lead plate 13 and the chamber body 11 contact each other. In addition, a second sealing member 18b may be interposed between the contact surfaces between the lead plate 13 and the dielectric plate 14. The first and second sealing members 18b allow the vacuum state to be maintained when the processing space 12 of the chamber body 11 is vacuum. Meanwhile, a gas for generating plasma may be transferred through the inside of the lead plate 13 and injected into the processing space 12 of the chamber body 11.

The dielectric plate 14 is disposed on the upper side of the chamber body 11, preferably on the upper surface of the lead plate 13 so that the lower surface thereof is exposed to the inside of the chamber body 11. The dielectric plate 14 prevents the high frequency power applied to the antenna 15 from being transmitted to the chamber body 11 and shorting to the outside. To this end, the dielectric plate 14 is preferably made of an insulating material. In addition, the dielectric plate 14 is preferably made of a material having a plasma resistance. This is to minimize the damage of the dielectric plate 14 by the plasma generated under the dielectric plate 14 to maintain a certain number of objects (G) to be treated after the maintenance (maintenance) to replace the dielectric plate 14 This is to reduce the number of work. One example of the material of the dielectric plate 14 may be quartz or ceramic. Alternatively, the dielectric plate 14 may be made of a non-conductive metal having plasma resistance.

The antenna 15 is disposed above the dielectric plate 14. The antenna 15 receives high frequency power to generate an induction electric field for generating plasma in the processing space 12. The antenna 15 may be made of an electrically conductive metal so as to inductively supply a magnetic flux line of gas into the processing space 12 of the chamber body 11 serving as the processing chamber of the object G. The shape of the antenna 15 may be coiled. However, the antenna 15 is not limited to a coil type, and any shape may be used as long as it can generate a uniform plasma in the processing space 12 of the chamber described later.

The high frequency power of 13.56 MHz may be applied to the antenna 15. To this end, the antenna 15 is electrically connected to the power supply 17. The matching device 16 is disposed between the antenna 15 and the power supply unit 17. The antenna 15 may consist of a single antenna 15 line. Alternatively, the antenna 15 may be composed of a plurality of antenna 15 lines, and the matcher 16 serves to control the impedance of these antenna 15 lines. To this end, the matcher 16 may include at least one condenser or variable capacitor. For example, when the antenna 15 is composed of the inner antenna 15 and the outer antenna 15, and the inner antenna 15 and the outer antenna 15 are connected in parallel, a capacitor is attached to the inner antenna 15. The variable capacitor may be connected to the outer antenna 15, and the current flowing through the inner antenna 15 and the outer antenna 15 may be controlled by adjusting the variable capacitor. Accordingly, the plasma density distribution formed in the processing space 12 of the chamber can be controlled. Here, the matching unit 16 is not limited to including a condenser or a variable capacitor, and may be any one that can be used as an impedance adjusting means such as a variable coil and a resistor.

The gas supply unit is arranged such that one side is in communication with the inside of the chamber body 11 to supply gas into the chamber body 11. As the gas supplied to the chamber body 11, a halogen-based gas, an O ₂ gas, an Ar gas, or the like used to generate a plasma may be used.

The electrostatic chuck 100 of the present invention is disposed below the dielectric plate 14, that is, in the processing space 12 of the chamber body 11, and the object to be processed G is seated.

Meanwhile, the cover 19 may be disposed above the lead plate 13. The cover 19 shields the induction field generated from the antenna 15.

The processing of the object G to be processed in the substrate processing apparatus 10 having the above structure will be described.

First, the substrate G, which is the object G to be processed, is loaded into the chamber main body 11 and mounted on the upper surface of the electrostatic chuck 100. In addition, a DC power is applied to the electrode layer 130 of the electrostatic chuck 100, and electrostatic power is generated in the electrode layer 130, thereby restricting the movement of the substrate G. Next, the inside of the chamber main body 11 is evacuated to a predetermined vacuum degree by the vacuum pump which is not shown in figure. Thereafter, the processing gas is uniformly supplied throughout the substrate G into the chamber body 11 by a gas supply unit not shown. In this process, the pressure in the chamber body 11 is maintained at a predetermined value. Then, the high frequency power generated from the power supply unit 17 is applied to the antenna 15 via the matching unit 16, and an induction electric field is generated inside the chamber. By such an induction electric field, gas dissociates and becomes a plasma, and the process of the surface of the board | substrate G is performed by this.

After the treatment of the surface of the object to be processed G is completed, the application of the high frequency power to the antenna 15 is stopped, and after the gas injection is stopped, the pressure in the chamber main body 11 is reduced to a predetermined pressure. Then, the application of electric power to the electrode layer 130 of the electrostatic chuck 100 is stopped, and the substrate G is carried out from the inside of the chamber body 11.

On the other hand, the electrostatic chuck 100 according to an embodiment of the present invention is not limited to being applied only to the above-described substrate processing apparatus 10 of the Inductively Coupled Plasma (ICP) method, Capacitively Coupled Plasma using a single frequency ), CCP method using dual frequency, ECR (Electron Cyclotron Resonance) method, SWP (Surface Wave Plasma), Helicon Wave method, e-beam method and Pulsed DC method Can be.

Although the present invention has been described with reference to one embodiment shown in the accompanying drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. Could be. Accordingly, the true scope of protection of the present invention should be determined only by the appended claims.

10: substrate processing apparatus 11: chamber body
14: dielectric plate 15: antenna
100: electrostatic chuck 110: base member
120: first insulating layer 130: electrode layer
140: second insulating layer

Claims (4)

An electrostatic chuck comprising a base member, a first insulating layer formed on the base member, an electrode layer formed on the first insulating layer, and a second insulating layer formed on the electrode layer.
The base member is:
A first base part made of a first material; And
A second base part formed on the first base part and made of a second material having a lower coefficient of thermal expansion than the first material;
Electrostatic chuck characterized in that it comprises a. The method of claim 1,
Wherein said first material is aluminum and said second material is titanium. The method of claim 1,
Wherein said first material is aluminum and said second material is stainless steel. The method of claim 1,
Wherein said first material is stainless steel and said first material is titanium.

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