KR20220164979A - Electrostatic chuck, alumina sintered body and manufacturing method therefof - Google Patents

Abstract

The present invention provides an alumina sintered body. In one embodiment, the alumina sintered body includes: coarse powder of which the diameter is in a range of 150 to 300 nm; and nanopowder of which the diameter is 100 nm or less. According to one embodiment of the present invention, a high-density pure alumina sintered body can be obtained.

Description

Electrostatic chuck, alumina sintered body and manufacturing method thereof

The present invention relates to an alumina sintered body and a method for producing the same.

Since the alumina sintered body is excellent in heat resistance, chemical resistance, and plasma resistance, and has a small dielectric loss tangent (tan δ) in a high frequency region, it is suitable for, for example, plasma processing devices, semiconductor/liquid crystal display device manufacturing etchers, CVD devices, etc. It is also used for materials to be used, substrates for plasma-resistant members to be coated, and the like. In particular, the alumina sintered body is applied as a dielectric of an electrostatic chuck (ESC).

The more dense the alumina sintered body (the higher the density), the higher the corrosion resistance. Various attempts have been made to obtain a dense structure by increasing the density of the alumina sintered body. For example, as disclosed in Korean Patent Publication No. 2020-0045558, in order to increase the density of the alumina sintered body, a large amount of ZrO2 of about 30wt% is mixed, or SiO2, Y2O3, MgO, etc. of about 1wt% are added. However, in this method, even if the sintering density increases, the electrical properties such as the dielectric constant and insulation resistance of the sintered body change due to the additive material, and the characteristics in functioning as an electrostatic chuck (ESC) change. It may be precipitated and react with plasma during the semiconductor manufacturing process to affect etching resistance, and may also act as a process particle.

In order to solve this problem, in order to obtain high density without adding additives to alumina, CIP (cold Isostatic Pressing) in the molding step and high-temperature HIP (Hot Isostatic Pressing) in the sintering step have been used. cause an increase in

An object of the present invention is to provide a high-density pure alumina sintered body and a manufacturing method thereof.

An object of the present invention is to provide a manufacturing method capable of obtaining a high-density pure alumina sintered body without increasing the cost required in the sintering step.

An object of the present invention is to provide an electrostatic chuck with high substrate processing efficiency and low manufacturing cost because electrical characteristics such as dielectric constant and insulation resistance of an alumina sintered body provided in the electrostatic chuck are not changed.

The object of the present invention is not limited thereto, and other objects not mentioned will be clearly understood by those skilled in the art from the following description.

The present invention provides an alumina sintered body. In one embodiment, the alumina sintered body, coarse powder having a diameter of 150nm to 300nm; Contains nanopowders of 100 nm or less.

In one embodiment, the nanopowder may be provided in an amount corresponding to the pores of the coarse powder.

In one embodiment, based on 100 parts by weight of the alumina sintered body, 70 to 90 parts by weight of the coarse powder; and 10 to 30 parts by weight of the nanopowder.

The present invention provides a method for producing an alumina sintered body. In one embodiment, the manufacturing method of the alumina sintered body, preparing a coarse powder having a diameter of 150nm to 300nm; preparing a nanopowder of 100 nm or less; wet grinding the nanopowder; and mixing, shaping, and sintering the wet-pulverized nanopowder and the coarse powder.

In one embodiment, the nanopowder is provided in an amount corresponding to the pores of the coarse powder.

In one embodiment, based on 100 parts by weight of the alumina sintered body, 70 to 90 parts by weight of the coarse powder; and 10 to 30 parts by weight of the nanopowder.

In addition, the present invention provides an electrostatic chuck. In one embodiment, the electrostatic chuck includes a dielectric substrate made of the alumina sintered body; and an electrode provided on a lower surface of the dielectric substrate.

According to one embodiment of the present invention, a high-density pure alumina sintered body can be obtained.

According to one embodiment of the present invention, while obtaining a high-density pure alumina sintered body, the cost required in the sintering step is not high.

According to one embodiment of the present invention, an electrostatic chuck capable of efficiently processing a substrate can be obtained without a change in electrical characteristics such as dielectric constant and insulation resistance of an alumina sintered body.

The effects of the present invention are not limited to the above effects, and should be understood to include all effects that can be inferred from the detailed description of the present invention or the configuration of the invention described in the claims.

1 is a view schematically showing the structure of an alumina sintered body manufactured by a conventional sintering method.
2 is a view schematically showing the structure of an alumina sintered body according to an embodiment of the present invention.
3 illustrates the particle distribution of nanopowder by the pulverization process of the conventional nanopowder agglomerate and the nanopowder agglomerate according to an embodiment of the present invention.
4 is a graph showing the change in sintering density according to the size of the coarse powder and the nanopowder when 10wt% of the nanopowder and 90wt% of the coarse powder are mixed in an embodiment of the present invention.
5 is a cross-sectional view of an electrostatic chuck according to an embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings, embodiments of the present invention will be described in detail so that those skilled in the art can easily carry out the present invention. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. In addition, in describing preferred embodiments of the present invention in detail, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description will be omitted. In addition, the same reference numerals are used throughout the drawings for parts having similar functions and actions.

'Including' a certain component means that other components may be further included, rather than excluding other components unless otherwise stated. Specifically, terms such as "comprise" or "having" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, but one or more other features or It should be understood that the presence or addition of numbers, steps, operations, components, parts, or combinations thereof is not precluded.

Singular expressions include plural expressions unless the context clearly dictates otherwise. In addition, shapes and sizes of elements in the drawings may be exaggerated for clearer description.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms may be used for the purpose of distinguishing one component from another. For example, a first element may be termed a second element, and similarly, the second element may also be termed a first element, without departing from the scope of the present invention.

It is understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, but other elements may exist in the middle. It should be. On the other hand, when a component is referred to as “directly connected” or “directly connected” to another component, it should be understood that no other component exists in the middle. Other expressions describing the relationship between components, such as "between" and "directly between" or "adjacent to" and "directly adjacent to", etc., should be interpreted similarly.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and unless explicitly defined in this application, they are not interpreted in an ideal or excessively formal meaning. .

1 is a view schematically showing the structure of an alumina sintered body manufactured by a conventional sintering method. An alumina sintered body molded from the molded coarse powder 1 having a single size does not have a high density due to voids between the powders.

2 is a view schematically showing the structure of an alumina sintered body according to an embodiment of the present invention. An alumina sintered body according to an embodiment of the present invention includes a coarse powder (1) and a nano powder (2).

Coarse powder 1 is provided having a diameter of 150 nm to 300 nm (based on average particle diameter (D50), which is the particle diameter at which 50% by weight of particles from the finest particle side are accumulated in the particle size distribution measured by the laser diffraction scattering method) ).

The nanopowder 2 is provided having a diameter of 100 nm or less. The nanopowder 2 is wet-pulverized before being mixed with the coarse powder 1. In an embodiment, wet grinding may be performed by a grinder such as a ring mill, a rotate mill, or a batch mill.

3 illustrates the particle distribution of nanopowder by the pulverization process of the conventional nanopowder agglomerate and the nanopowder agglomerate according to an embodiment of the present invention. Even if the alumina powder is prepared as nanopowder, since the nanopowder forms aggregates, even if the particle size is nano-sized, the size is 1 μm or more, at a maximum of 10 μm or more due to the agglomerates in the process of forming the sintered body, and a distribution having an average of 3.4 μm. It has (D50 standard). Even if these nanopowder agglomerates are mixed with the coarse powder, it is difficult to function as particles smaller than the coarse powder, and as a result, it is difficult to obtain the required sintered density.

According to an embodiment of the present invention, prior to mixing the coarse powder and the nanopowder, the nanopowder is wet-pulverized to disperse the nanopowder, thereby obtaining a nanopowder having particles of 100 nm or less. According to experiments, the size is less than 100 nm by wet grinding. Particles with an average size of 23 nm were obtained (based on D50). In the experiment, wet grinding was performed for 70 hours or more. However, unlike the experimental example, the grinding time may vary depending on the grinding method or strength.

4 is a graph showing changes in sintering density according to the size of coarse powder and nanopowder in an experiment in which 10 wt% of nanopowder and 90 wt% of coarse powder were mixed in an embodiment of the present invention. The sintering conditions were sintering at normal pressure and 1550°C for 10 hours.

When the 550 nm coarse powder and each nanopowder are mixed, the sintered density is about 95.7% when only the pure coarse powder is mixed. A mixture of 550 nm coarse powder and 20 nm nano powder has a sintered density of about 92.4%. A mixture of 550 nm coarse powder and 40 nm nano powder has a sintered density of about 97.7%. A mixture of 550 nm coarse powder and 80 nm nano powder has a sintered density of about 97.7%. When 550 nm coarse powder was applied, when mixed with 20 nm nanopowder, the sintered density was rather reduced, and when 40nm and 80nm nanopowders were mixed, respectively, the sintered density was lower than that of 150nm and 250nm coarse powders described later.

When the 250 nm coarse powder and each nanopowder are mixed, the sintered density is about 96.9% when only the pure coarse powder is mixed. A mixture of 250 nm coarse powder and 20 nm nano powder has a sintered density of about 95%. A mixture of 250 nm coarse powder and 40 nm nano powder has a sintered density of about 96.9%. A mixture of 250 nm coarse powder and 80 nm nano powder has a sintered density of about 98.3%.

When the 150 nm coarse powder and each nanopowder are mixed, the sintered density is about 96.5% when only the pure coarse powder is mixed. A mixture of 150 nm coarse powder and 20 nm nano powder has a sintered density of about 97.1%. A mixture of 150 nm coarse powder and 40 nm nano powder has a sintered density of about 98%. A mixture of 150 nm coarse powder and 80 nm nano powder has a sintered density of about 98.7%.

According to the results examined through the experiment, when the size of the coarse powder is relatively larger than 300 nm, such as 500 nm, the change in sintering density is relatively large when the nanopowder is mixed, and the sintering density is lower than when sintering only pure coarse powder. There is a possibility of obtaining

When the 250 nm coarse powder was applied, the change in sintered density according to the mixing of the nanopowder was relatively small, and when the 40nm and 80nm nanopowders were mixed, the sintered density increased.

20 nm when 150 nm of coarse powder is applied. In all cases where 40 nm and 80 nm nanopowders were applied, the sintered density showed an increase, and it was confirmed that the sintered density was higher than when only pure coarse powder was mixed.

As described above, 10 wt% of the nanopowder and 90 wt% of the coarse powder were mixed, but this is an experimental example. can be derived as For example, 10 wt% to 30 wt% of the nanopowder and 70wt% to 90 wt% of the coarse powder may be mixed.

When alumina is sintered by the method according to the present embodiment, a high sintered density of 98% or more can be obtained even when sintered under normal pressure. That is, high-density pure alumina can be produced without expensive manufacturing facilities.

5 is a cross-sectional view of an electrostatic chuck according to an embodiment of the present invention.

According to one example, the electrostatic chuck 20 is disposed in a chamber (not shown) of a plasma processing device (not shown).

In the electrostatic chuck 20, an insulator film 22 is formed on the surface of a metal plate 21 by thermal spraying, and a dielectric substrate 24 is formed on the insulator film 22 via an insulating adhesive layer 23. The surface of the dielectric substrate 24 serves as a receiving surface for the adsorbed material W such as a semiconductor wafer, and electrodes 25 and 25 are provided on the lower surface. Lead wires 26 and 26 for supplying power to these electrodes 25 and 25 are provided extending downward through the metal plate 21 . The lead wire 26 and the metal plate 21 are provided insulated.

The metal plate 21 is made of a metal with excellent thermal conductivity, such as aluminum alloy or copper, has a refrigerant passage 21a formed therein, and the insulator film 22 formed on the upper surface of the metal plate 21 by spraying It may be an inorganic material, for example, alumina (Al2O3).

As a method for manufacturing the dielectric substrate 24, a method for manufacturing an alumina sintered body in which the above-described coarse powder 1 and nanopowder 2 are mixed is adopted. In one example, the dielectric substrate 24 is sintered by including 90wt% of the coarse powder (1) and 10wt% of the nanopowder (2). When such a dense dielectric substrate is used, plasma resistance is improved, and the change in surface roughness of the electrostatic chuck is suppressed to a very small level without using a dummy wafer.

For the electrode 25, a predetermined electrode pattern can be obtained by grinding the surface of the dielectric substrate 24, forming a conductive film such as TiC or Ti by CVD or PVD, and sandblasting or etching the conductive film. .

When assembling the electrostatic chuck 20, a metal plate 21 on which an insulator film 22 is formed and a dielectric substrate 24 on which an electrode 25 is formed are prepared in advance, and the insulator film 22 and the dielectric of the metal plate 21 are prepared. The electrodes 25 of the substrate 24 may face each other, and the two may be bonded via the insulating adhesive 23 . As the insulating adhesive 23, alumina or aluminum nitride can be used as a filler, for example.

Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art to which the present invention pertains can be implemented in other specific forms without changing the technical spirit or essential features of the present invention. will be able to understand Therefore, the embodiments described above should be understood as illustrative in all respects and not limiting. The scope of the present invention is indicated by the claims to be described later rather than the detailed description above, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the present invention. do.

The above detailed description is illustrative of the present invention. In addition, the foregoing is intended to illustrate and describe preferred embodiments of the present invention, and the present invention can be used in various other combinations, modifications and environments. That is, changes or modifications are possible within the scope of the concept of the invention disclosed in this specification, within the scope equivalent to the written disclosure and / or within the scope of skill or knowledge in the art. The written embodiment describes the best state for implementing the technical idea of the present invention, and various changes required in the specific application field and use of the present invention are also possible. Therefore, the above detailed description of the invention is not intended to limit the invention to the disclosed embodiments. Also, the appended claims should be construed to cover other embodiments as well.

Claims (7)

coarse powder having a diameter of 150 nm to 300 nm;
An alumina sintered body containing nanopowder of 100 nm or less. According to claim 1,
The nanopowder is provided in an amount corresponding to the voids of the coarse powder. According to claim 1,
With respect to 100 parts by weight of the alumina sintered body,
70 parts by weight to 90 parts by weight of the coarse powder; and
An alumina sintered body comprising 10 parts by weight to 30 parts by weight of the nanopowder. preparing a coarse powder having a diameter of 150 nm to 300 nm;
preparing a nanopowder of 100 nm or less;
wet grinding the nanopowder; and
A method for producing an alumina sintered body comprising the step of mixing the wet-pulverized nanopowder and the coarse powder, molding and sintering. According to claim 4,
The nanopowder is provided in an amount corresponding to the pores of the coarse powder. According to claim 4,
With respect to 100 parts by weight of the alumina sintered body,
70 to 90 parts by weight of the coarse powder; and
Method for producing an alumina sintered body containing 10 to 30 parts by weight of the nanopowder. A dielectric substrate made of the alumina sintered body of any one of claims 1 to 3;
An electrostatic chuck comprising an electrode provided on a lower surface of the dielectric substrate.

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