KR102551215B1 - Ceramic Composition, Electrostatic Chuck, and Manufacturing Method of Electrostatic Chuck - Google Patents

Abstract

A ceramic composition according to an embodiment of the present invention contains Al ₂ O ₃ as a main component, contains SiO ₂ as a first subcomponent in an amount of 6 to 10% by weight, and TiO ₂ as a second subcomponent in an amount of 0.2 wt % based on the total composition. to 0.3% by weight.

Description

Ceramic Composition, Electrostatic Chuck, and Manufacturing Method of Electrostatic Chuck {Ceramic Composition, Electrostatic Chuck, and Manufacturing Method of Electrostatic Chuck}

The present invention relates to a ceramic composition, an electrostatic chuck, and a method for manufacturing the electrostatic chuck.

An electrostatic chuck included in a semiconductor manufacturing apparatus is a device that fixes a wafer by using an electrostatic force generated by a difference in electric potential. An electrostatic chuck is mainly used to horizontally fix a semiconductor wafer during plasma etching during a semiconductor process.

In comparison, a mechanical chuck using mechanical contact has a problem of generating large deformation or fine particles on a wafer surface, and a vacuum chuck has a problem of being usable only in a vacuum environment. Accordingly, as electrostatic chucks have recently been widely used in the semiconductor manufacturing field, the size of the electrostatic chuck market is also expected to rapidly expand.

Such an electrostatic chuck typically has a structure including a dielectric layer made of a ceramic composition and internal electrodes sealed therewith, and the performance of the electrostatic chuck is greatly affected by the electrical and physical properties of the ceramic composition.

Accordingly, the present invention intends to propose a ceramic composition for an electrostatic chuck having excellent sinterability, high density, and excellent resistivity characteristics, and also proposes an electrostatic chuck including the ceramic composition.

Furthermore, another embodiment of the present invention provides a manufacturing method capable of effectively implementing an electrostatic chuck.

As a method for solving the above problems, the present invention intends to propose a novel ceramic composition through one form. Specifically, the ceramic composition has Al ₂ O ₃ as a main component and SiO ₂ as a first subcomponent is added to the entire composition. 6 to 10% by weight relative to the composition, and 0.2 to 0.3% by weight of the second subcomponent TiO ₂ based on the total composition.

In this case, the ceramic composition may further include MgCO ₃ and CaCO ₃ as third and fourth subcomponents, respectively.

In addition, in the case of such a ceramic composition, a sintered body having a relative density of 95% or more can be formed. In addition, in the case of such a ceramic composition, a sintered body having a specific resistance of 5*10 ¹⁵ Ω·cm or more can be formed.

In addition, the main component Al ₂ O ₃ may be included in an amount of 85% by weight or more based on the total composition.

Another embodiment of the present invention provides an electrostatic chuck including the above-described ceramic composition, and specifically, includes an internal electrode generating electrostatic force and a dielectric layer sealing the internal electrode, wherein the dielectric layer is Al ₂ O ₃ as a main component, a first subcomponent, SiO ₂ , 6 to 10% by weight, based on the total composition, and a second subcomponent, TiO ₂ , 0.2 to 0.3% by weight, based on the total composition. to be

In this case, the internal electrode may include Ni.

In addition, another embodiment of the present invention provides a method of manufacturing an electrostatic chuck, specifically, including preparing a ceramic composition for a dielectric layer and a metal paste for internal electrodes, and firing the ceramic composition and the metal paste, The ceramic composition includes Al ₂ O ₃ as a main component, SiO ₂ as a first subcomponent in an amount of 6 to 10% by weight, and TiO ₂ as a second subcomponent in an amount of 0.2 to 0.3% by weight based on the total composition. characterized by

In this case, the ceramic composition and the metal paste may be simultaneously fired.

Also, the metal paste may include Ni, and in this case, the firing of the ceramic composition and the metal paste may be performed in a non-oxidizing atmosphere.

Meanwhile, the main component, Al ₂ O ₃ , may be provided in the form of a powder having a particle size distribution of 180 nm to 350 nm based on D50.

In the case of the ceramic composition proposed in one embodiment of the present invention, since it has excellent sinterability, high density, and excellent resistivity, performance can be improved when used in an electrostatic chuck.

1 is a schematic cross-sectional view of an electrostatic chuck according to an embodiment of the present invention.
2 is a photomicrograph showing the microstructure of a sample in which glass elution occurred due to an increase in the content of SiO ₂ among experimental examples of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to specific embodiments and accompanying drawings. However, the embodiments of the present invention can be modified in many different forms, and the scope of the present invention is not limited to the embodiments described below. In addition, the embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art. Therefore, the shape and size of elements in the drawings may be exaggerated for clearer explanation, and elements indicated by the same reference numerals in the drawings are the same elements.

In addition, in order to clearly describe the present invention in the drawings, parts irrelevant to the description are omitted, and the thickness is enlarged in order to clearly express various layers and regions, and components having the same function within the scope of the same idea are shown with the same reference. Explain using symbols. Furthermore, throughout the specification, when a certain component is said to "include", it means that it may further include other components without excluding other components unless otherwise stated.

ceramic composition and electrostatic chuck

1 is a schematic cross-sectional view of an electrostatic chuck according to an embodiment of the present invention. Referring to FIG. 1 , an electrostatic chuck 100 includes dielectric layers 101 and 102 and internal electrodes 103 generating electrostatic force as main components, and internal electrodes 103 are formed by upper and lower dielectric layers 101 and 102 . It may be provided in the form of sealing. The electrostatic chuck is a component that can fix the substrate to the lower electrode using the force of static electricity. When an electric signal is applied to the electrostatic chuck, the object is charged with an opposite potential, and the principle that a force that attracts each other is generated by the charged potential. Use Such an electrostatic chuck is mainly used to horizontally fix a wafer of a semiconductor or to hold a glass substrate of an LCD horizontally, and the wafer or glass substrate is disposed above the dielectric layer 101 in FIG. 1 .

The internal electrode 103 is provided to generate electrostatic force required for the aforementioned electrostatic adsorption, and as will be described later, in the present embodiment, it may be made of a material containing Ni. In addition, the internal electrode 103 may have a form fired at the same time as the ceramic material constituting the dielectric layers 101 and 102, and in this case, as will be described later, the firing temperature can be performed at a temperature of about 1350° C. or less.

On the other hand, if necessary for a semiconductor forming process or the like, the heating unit 104 may be buried inside the dielectric layers 101 and 102 . Also, as shown in FIG. 1 , the electrostatic chuck 100 may be disposed on the base plate 105 , and the electrostatic chuck 100 and the base plate 105 may be referred to as a chuck unit. In this case, the base plate 105 may generally be made of a high thermal conductivity metal having an aluminum alloy surface treated with an alumite. Also, although not shown, the base plate 105 has a cooling water passage for temperature control formed therein. may have been

The dielectric layers 101 and 102 may be made of different materials or made of the same material to form an integral structure, and a ceramic composition is sintered. As a result of studying the properties of the ceramic composition for an electrostatic chuck, the inventors of the present invention propose a composition capable of realizing a high-density sintered body and furthermore, having excellent electrical properties.

Specifically, in the present embodiment, the ceramic composition included in the dielectric layers 101 and 102 has Al ₂ O ₃ as a main component, SiO ₂ as a first subcomponent is 6 to 10% by weight based on the total composition, and the second subcomponent is SiO 2 . TiO ₂ is included in an amount of 0.2 to 0.3% by weight based on the total composition.

In the case of the ceramic composition of the present embodiment, it can be fired simultaneously with an internal electrode containing Ni, and can be sintered at a temperature condition of about 1350° C. or less, lower than a commonly used firing temperature, by adjusting the addition ratio of SiO ₂ and TiO ₂ . can Even when sintered at such a relatively low temperature, it was possible to secure high sintering power at a level where the relative density of the sintered body was 95% or more. Here, the relative density means the ratio of the actual density to the theoretical maximum density that the sintered body can have. In addition, the addition ratio of SiO ₂ and TiO ₂ needs to be adjusted in consideration of electrical properties, for example, specific resistance, etc., and in the case of the sintered body obtained from the ceramic composition of the present embodiment, a level of 5 × 10 ¹⁵ Ω cm or more Resistivity could be realized.

As described above, the ceramic composition of the present embodiment has Al ₂ O ₃ as a main component, and TiO ₂ is added in a small amount for the purpose of lowering the sintering temperature. In this case, TiO ₂ is effective in lowering the sintering temperature of Al ₂ O ₃ , but has a side effect of reducing specific resistance by increasing electrical conductivity by becoming a semiconductor when sintering in a reducing atmosphere. Since such a reducing atmosphere firing is necessary in the case of forming an internal electrode using a Ni component as in the present embodiment, the content of TiO ₂ is lowered in the present embodiment and the content of SiO ₂ is increased instead. In this way, as the content of TiO ₂ is lowered, resistivity characteristics are implemented, and sinterability can be improved by increased SiO ₂ , and the inventors of the present invention conducted experiments as follows to derive an optimal content range.

Experimental examples and analysis

Table 1 below shows specific resistance and relative density measured by sintering ceramic compositions obtained by varying the content of the main component and subcomponents. In this case, the content of each component is % by weight, and the units of resistivity and relative density are Ω·cm and %, respectively. In addition, the compositions of _the following experimental examples further include MgCO ₃ and CaCO ₃ as third and fourth subcomponents, respectively _. and the content of the fourth subcomponent was kept constant.

Describing the above test method in more detail, first, after weighing and mixing the mixing ratio of each powder raw material according to the standards of the above-described experimental example, an organic binder, plasticizer, dispersant, and solvent are added, and mixed to obtain a ceramic slurry produce Thereafter, the ceramic slurry is molded into a sheet shape to form a ceramic green sheet, and several sheets of the obtained ceramic green sheet are laminated and pressed as necessary to manufacture a ceramic laminate. The ceramic laminate thus obtained is degreased and fired in a non-oxidizing atmosphere to obtain a ceramic sintered body. In order to sinter under a non-oxidizing atmosphere, for example, sintering can be performed in a mixed gas of humidified hydrogen and nitrogen. Alternatively, any sintering can be performed under a non-oxidizing atmosphere, such as a method of sintering in an inert gas such as vacuum or argon gas. will be available And, as described above, the firing temperature may be set to a medium temperature firing region, for example, about 1350°C.

After obtaining the fired specimen in the above-described method, the density was obtained using the Archimedes method, and then the specific resistance was measured. Here, the resistivity measurement was performed after the electrode material was applied to the fired specimen and then fired to form an electrode layer.

As can be seen from the experimental results of Table 1 for 25 samples, when the TiO ₂ content is too low (less than 0.2% by weight), sufficient sintering power could not be secured at 1350 ° C or lower, but is not necessarily limited thereto. The inventors set a standard for sufficient sintering at a relative density of 95%. In addition, as described above, as the TiO ₂ content increased, there was a side effect of lowering the specific resistance, and based on the experimental results of Table 1, the preferred range of the TiO ₂ content was set to 0.2 to 0.3% by weight.

Next, examining the effect of SiO ₂ on the sintered body, it was confirmed that the relative density increased as the sintering characteristics improved as the TiO ₂ content was relatively lowered and the SiO ₂ was increased, and the resistivity property also tended to improve. seemed Although not necessarily limited thereto, the inventors of the present invention set a desirable level of specific resistance to about 5×10 ¹⁵ Ω·cm. As shown in the results of Table 1, this tendency was confirmed in the composition containing 6% by weight or more of SiO ₂ . However, when the amount of SiO ₂ exceeds the characteristic level (greater than 10% by weight) in the preferred range of TiO ₂ content presented above, it was confirmed that the specific resistance property deteriorated. This deterioration in resistivity can be interpreted as the fact that as the SiO ₂ content increases, as can be seen in the photo of the microstructure shown in FIG. According to these results, the content of SiO ₂ was set to 6 to 10% by weight with respect to the total composition.

In the case of the ceramic composition of the present embodiment in which TiO ₂ and SiO ₂ have _the above-described content ranges, even when a relatively small amount of TiO ₂ is added, the relative density and Resistivity characteristics could be improved. Additionally, looking at the preferred content range of the main component, Al ₂ O ₃ , it was confirmed that sufficient sintering properties and electrical properties were exhibited when it was included in an amount of about 85% by weight or more relative to the total composition.

electrostatic manufacturing method

A method of manufacturing an electrostatic chuck using the ceramic composition described above will be described. In the case of the manufacturing method of the electrostatic chuck according to the present embodiment, first, a ceramic composition for a dielectric layer and a metal paste for an internal electrode are prepared. Here, the ceramic composition for the dielectric layer may use the method used in the above-described experimental example, and the specific composition range is also under the above-described conditions, that is, Al ₂ O ₃ is the main component and the first sub-component SiO ₂ is 6 to 6 with respect to the entire composition. At 10% by weight, TiO ₂ as the second subcomponent may be contained in an amount of 0.2 to 0.3% by weight based on the total composition. The metal paste for the internal electrode may contain Ni, and may be sintered at a relatively low temperature compared to W or Mo.

In the next step, the ceramic composition and the metal paste are fired to form a sintered body. In this case, the ceramic composition and the metal paste may be calcined simultaneously, and the calcining step may be performed at a temperature condition of about 1350° C. or less. Also, as described above, this firing step can be performed in a non-oxidizing atmosphere, whereby Ni can be used as an internal electrode material.

Meanwhile, a particle size of the composition, ie, particle size distribution, may be mentioned as a factor affecting the firing temperature in addition to adjusting the content of components included in the ceramic composition. As described above, in the present embodiment, firing is performed at a temperature of about 1350 ° C. or less, which is lower than the case of using an internal electrode such as W or Mo. Specifically, in the present embodiment, the particle size distribution of Al ₂ O ₃ powder, which is the main component, is adopted at a level of 180 nm to 350 nm based on D50, which is finer than a conventional ceramic material for an electrostatic chuck that is a level of 500 nm or more. As the main component, Al ₂ O ₃ , has such an atomized particle size distribution, a more dense and high-strength sintered body can be obtained, and the firing temperature can be lowered to a level of about 1350° C. or less.

The present invention is not limited by the above-described embodiments and accompanying drawings, but is intended to be limited by the appended claims. Therefore, various forms of substitution, modification, and change will be possible by those skilled in the art within the scope of the technical spirit of the present invention described in the claims, which also falls within the scope of the present invention. something to do.

100: electrostatic chuck
101, 102: dielectric layer
103: internal electrode
104: heating unit
105: base plate

Claims (16)

Al ₂ O ₃ is included in the largest percentage by weight of the total composition,
SiO ₂ as a first subcomponent is 6 to 10% by weight based on the total composition,
A ceramic composition comprising 0.2 to 0.3% by weight of TiO ₂ as a second subcomponent based on the total composition.
According to claim 1,
A ceramic composition further comprising MgCO ₃ and CaCO ₃ as third and fourth subcomponents, respectively.
According to claim 1,
A ceramic composition forming a sintered body having a relative density of 95% or more.
According to claim 1,
A ceramic composition forming a sintered body having a specific resistance of 5*10 ¹⁵ Ω·cm or more.
According to claim 1,
A ceramic composition comprising 85% by weight or more of Al ₂ O ₃ based on the total composition.
Internal electrodes generating electrostatic force; and
A dielectric layer sealing the internal electrodes; includes,
The dielectric layer includes Al ₂ O ₃ in the largest percentage by weight of the total composition, SiO ₂ as a first subcomponent in an amount of 6 to 10 wt%, and TiO ₂ as a second subcomponent in an amount of 0.2 wt% with respect to the entire composition. An electrostatic chuck comprising a ceramic sintered body containing 0.3% by weight to 0.3% by weight.
According to claim 6,
The electrostatic chuck, characterized in that the internal electrode contains Ni.
According to claim 6,
The ceramic sintered body further includes MgCO ₃ and CaCO ₃ as third and fourth subcomponents, respectively.
According to claim 6,
The electrostatic chuck, characterized in that the ceramic sintered body has a relative density of 95% or more.
According to claim 6,
The electrostatic chuck, characterized in that the ceramic sintered body has a specific resistance of 5 * 10 ¹⁵ Ω cm or more.
According to claim 6,
The electrostatic chuck, wherein the ceramic sintered body contains 85% by weight or more of Al ₂ O ₃ based on the total composition.
preparing a ceramic composition for a dielectric layer and a metal paste for internal electrodes; and
Including; firing the ceramic composition and the metal paste,
The ceramic composition includes Al ₂ O ₃ in the largest percentage by weight of the total composition, SiO ₂ as a first subcomponent in an amount of 6 to 10 wt%, and TiO ₂ as a second subcomponent in an amount of 6 to 10 wt% with respect to the entire composition. A method for manufacturing an electrostatic chuck, characterized in that it comprises 0.2 to 0.3% by weight.
According to claim 12,
The method of manufacturing an electrostatic chuck, characterized in that the ceramic composition and the metal paste are fired simultaneously.
According to claim 12,
The method of manufacturing an electrostatic chuck, characterized in that the metal paste contains Ni.
According to claim 14,
The method of manufacturing an electrostatic chuck, characterized in that the firing of the ceramic composition and the metal paste is performed in a non-oxidizing atmosphere.
According to claim 12,
The method of manufacturing an electrostatic chuck, characterized in that the Al ₂ O ₃ is provided in the form of a powder having a particle size distribution of 180 nm to 350 nm based on D50.

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