JP5874248B2 - Electrostatic chuck and manufacturing method thereof - Google Patents

Description

  The present invention relates to an electrostatic chuck and a manufacturing method thereof. More specifically, the present invention relates to an electrostatic chuck used for holding a semiconductor wafer or the like in a semiconductor manufacturing apparatus and a manufacturing method thereof.

A chuck apparatus is used to hold a wafer in a film forming apparatus such as a CVD apparatus or a sputtering apparatus used in a semiconductor manufacturing process or an etching apparatus for performing fine processing.
Conventionally, a vacuum chuck method or a mechanical clamp method has been adopted as the chuck device. However, as the semiconductor manufacturing process has become more advanced in recent years, an electrostatic chuck (Electro) that attracts a semiconductor wafer by electrostatic attraction (Coulomb force). The Static Chuck (ESC) method has been used. This electrostatic chuck method exhibits superior characteristics compared to the conventional vacuum chuck method and mechanical clamp method in terms of wafer flatness correction and soaking. As for the operation characteristics of the electrostatic chuck, a large chucking force is generated while a voltage is applied to prevent the object to be attracted from dropping, and immediately after the voltage application is canceled, the chucking force is reduced. It is desirable that the object to be adsorbed can be easily removed.

Dielectric loss is achieved by precipitating a samarium-aluminum oxide phase in the grain boundary phase of alumina (Al ₂ O ₃ ) ceramics or aluminum nitride (AlN) ceramics for the purpose of stabilizing the adsorption and desorption performance of the electrostatic chuck. In addition, a technique for reducing volume resistivity has been reported (see, for example, Patent Document 1).

On the other hand, in semiconductor production lines such as IC, LSI, VLSI, etc., there are processes using halogen-based corrosive gases such as fluorine-based corrosive gases and chlorine-based corrosive gases and their plasmas, especially dry etching and plasma etching. In the cleaning process, fluorine gas such as CF ₄ , SF ₆ , HF, NF ₃ , and F ₂ and chlorine gas such as Cl ₂ , SiCl ₄ , BCl ₃ , and HCl are used. Corrosion of components such as an electrostatic chuck in a semiconductor manufacturing apparatus due to corrosive gas or plasma is a problem.
Therefore, as a corrosion resistant material for an electrostatic chuck, for example, yttrium aluminum garnet or yttrium aluminum garnet added with a rare earth oxide excluding yttrium is used (for example, see Patent Document 2).

  Patent Document 2 discloses that corrosion resistance is improved by compounding rare earth elements excluding yttrium with yttrium aluminum complex oxide. Specifically, as the rare earth element excluding the yttrium (Y), one selected from lanthanum (La), neodymium (Nd), samarium (Sm), gadolinium (Gd), and dysprosium (Dy) or It is described that two or more are preferable, and among them, samarium (Sm) and gadolinium (Gd) are described to have a remarkable effect of improving the corrosion resistance.

JP 2007-258505 A JP 2004-315308 A

In the method described in Patent Document 1, the volume resistivity is stabilized by dispersing the samarium-aluminum oxide phase in the ceramic, but a high adsorption force cannot be obtained as an electrostatic chuck.
Further, according to the method described in Patent Document 2, it is possible for the yttrium aluminum oxide material to maintain a sufficient attracting force and workability as an electrostatic chuck. When manufacturing large-sized products, it may be difficult to control the particle size and the amount of oxygen defects between the center and the periphery of the sintered body produced in that process. The yield of the semiconductor product is likely to be reduced due to the non-uniformity. For this reason, a post-processing step such as post-annealing is required to make the in-plane characteristics uniform, and the cost is inevitably increased.

  The present invention has been made in view of the above circumstances, and is used in halogen-based corrosive gases such as fluorine-based corrosive gases and chlorine-based corrosive gases, and in these plasmas, and has sufficient adsorption power. In addition, it is an object of the present invention to provide an electrostatic chuck having a uniform attraction force in the surface and excellent mechanical strength, and a method for manufacturing the electrostatic chuck. It is another object of the present invention to provide an electrostatic chuck and a method of manufacturing the same that can easily remove the object to be attracted by reducing the chucking force immediately when the voltage application is released.

As a result of intensive studies to achieve the above object, the inventors of the present invention have determined that at least a portion of the electrostatic chuck exposed to a corrosive gas or plasma thereof has a yttrium aluminum crystal phase or yttrium aluminum yttrium. A rare earth element-aluminum oxide excluding yttrium (hereinafter referred to as “REAlO ₃ ”) may be included in a crystal phase obtained by partially replacing the rare earth element excluding yttrium (hereinafter sometimes referred to as “RE”). It has been found that by introducing a crystal phase at a predetermined ratio, even if the relative dielectric constant is low, sufficient adsorption force, the adsorption force is uniform in the plane, and excellent mechanical strength can be obtained. The invention has been completed.

That is, the present invention is as follows.
[1] Yttrium aluminum oxide crystal phase (A) or a crystal phase (B) obtained by replacing a part of yttrium of yttrium aluminum oxide with a rare earth element that is not yttrium, and a rare earth element-aluminum oxide crystal phase excluding yttrium (C And a content of the crystal phase (C) calculated by the following formula (1) based on an X-ray diffraction profile is 0.05% or more and 10% or less. Electric chuck.
Content (%) of crystal phase (C) = [(highest peak intensity based on crystal phase (C)) / (highest peak intensity based on yttrium aluminum oxide)] × 100 (1)

[2] The electrostatic chuck according to [1], wherein the rare earth element excluding the yttrium is at least one of samarium and gadolinium.
[3] The electrostatic chuck according to [1] or [2], wherein the crystal structure of the crystal phase (C) includes at least one of an orthorhombic crystal phase and a trigonal crystal phase.

[4] The method for manufacturing an electrostatic chuck according to any one of [1] to [3] above,
(A) a slurry preparation step of preparing a slurry in which raw material powder is dispersed in a solvent; (b) a molding step of granulating the slurry into granules and then forming the granules into a predetermined shape; (C) a firing step of firing the molded body,
The method for producing an electrostatic chuck, wherein the raw material powder in the slurry preparation step is an aluminum oxide powder, an yttrium oxide powder, and a rare earth element-aluminum oxide powder excluding yttrium.

[5] The method for manufacturing an electrostatic chuck according to [4], wherein the raw material powder further includes a rare earth element oxide powder excluding yttrium.

  According to the present invention, it is used in halogen-based corrosive gases such as fluorine-based corrosive gas and chlorine-based corrosive gas, and plasma thereof, and has a sufficient adsorbing force, and the adsorbing force is uniform in the plane. Thus, an electrostatic chuck excellent in mechanical strength and a method for manufacturing the same can be provided. In addition to the above-described effects, there is also provided an electrostatic chuck having a low residual attracting force and a method for manufacturing the same that can easily remove an object to be attracted by immediately reducing the chucking force when voltage application is canceled. Can do.

Hereinafter, the present invention will be described with reference to embodiments.
<Electrostatic chuck>
The electrostatic chuck of the present embodiment includes a yttrium aluminum oxide crystal phase (A) or a crystal phase (B) obtained by substituting a part of yttrium of yttrium aluminum oxide with a rare earth element that is not yttrium, and a rare earth element-aluminum other than yttrium. The composite oxide sintered body containing the oxide crystal phase (C) is included, and the content of the crystal phase (C) calculated by the following formula (1) based on the X-ray diffraction profile is 0.05% or more 10% or less.

Content (%) of crystal phase (C) = [(highest peak intensity based on crystal phase (C)) / (highest peak intensity based on yttrium aluminum oxide)] × 100 (1)

If the content of the crystal phase (C) is less than 0.05%, sufficient adsorption force as an electrostatic chuck cannot be obtained, and if it exceeds 10%, REAlO ₃ grows abnormally and mechanical strength decreases. Invite. The content of the crystal phase (C) is preferably 1% or more and 8% or less, and more preferably 1% or more and 5% or less.

The conventional electrostatic chuck having a metal oxide sintered body has a volume resistance value of 1 × 10 ¹⁴ Ω · cm or more, and exhibits the characteristics of a Coulomb-type electrostatic chuck. Therefore, the attractive force is proportional to the dielectric constant and the applied voltage, and inversely proportional to the thickness. The present inventors have found that even if the applied voltage and thickness are adjusted, a sufficient adsorption force cannot be obtained if the dielectric constant is less than 10 in the frequency region of 1 MHz or less and less than 30 in the frequency region of 1 kHz or less. It was.
In view of this, even if the dielectric constant is less than 10 in the frequency region of 1 MHz or less and less than 30 in the frequency region of 1 kHz or less by various trials and errors, for example, REAlO ₃ is introduced as a raw material and REALO is introduced into the sintered body. It has been found that a sufficient adsorption force can be obtained by the presence of ₃ .
This is considered to be because when a predetermined amount of REAlO ₃ is present in the sintered body, a new conductive layer is formed by this REAlO ₃ and the effect of lowering the volume resistivity of yttrium aluminum oxide contained in the sintered body is exhibited. . As a result, in addition to the Coulomb force originally generated by dielectric polarization of yttrium aluminum oxide, a Johnson-Rahbek force that involves electronic conduction is applied, and it is assumed that the adsorption force increases.

The crystal phase (B) formed by substituting a part of the yttrium aluminum oxide crystal phase (A) or yttrium of the yttrium aluminum oxide contained in the composite oxide sintered body with a rare earth element (RE) excluding yttrium has a crystal structure. Although it is not specifically limited, since it is excellent in mechanical strength, it is preferable that it is a garnet-type single phase. However, it may be a perovskite crystal phase or a monoclinic crystal phase, and may include these two crystal structures. In the composite oxide sintered body according to the present embodiment, the mechanical strength having no practical problem can be obtained when the crystal phase (A) or the crystal phase (B) has the above crystal structure.
Here, “single phase” refers to a state in which the presence of other components is not recognized in the X-ray diffraction pattern of this composite oxide sintered body. Therefore, the garnet-type crystal phase is represented by a composition formula of 5Al ₂ O _3. (3-x) Y ₂ O ₃ .xRE ₂ O ₃ (where 0.01 <x <1.20).

The rare earth element (RE) excluding yttrium (Y) in the present embodiment is not particularly limited, and scandium (Sc) and lanthanoid (Ln) lanthanum (La) belonging to Group 3 of the periodic table; cerium ( Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprodium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), and the like, but lanthanum (La), neodymium (Nd), samarium (Sm) from the standpoint of availability and the effect of improving corrosion resistance. ), Gadolinium (Gd), or one or more selected from the group of dysprosium (Dy) Masui.
Among these, at least one of samarium (Sm) and gadolinium (Gd) is preferable. By including these rare earth elements, the corrosion resistance is improved as compared with the single phase of yttrium aluminum oxide.

  Regarding the crystal phase (C), the crystal structure is preferably composed of at least one of an orthorhombic crystal phase and a trigonal crystal phase. This is because these crystal structures exhibit a sufficient attracting force as an electrostatic chuck.

  Whether the crystal phase (C) is orthorhombic or trigonal depends on the type of rare earth element (RE) excluding yttrium (Y). For example, when the rare earth element (RE) excluding yttrium (Y) is any one of lanthanum (La), praseodymium (Pr), and neodymium (Nd), a trigonal crystal phase is adopted and yttrium (Y) is excluded. When the rare earth element (RE) is samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprodium (Dy), holmium (Ho), erbium (Er), thulium (Tm) An orthorhombic crystal phase is adopted.

In the present embodiment, the rare earth element-aluminum oxide excluding yttrium in the crystalline phase (C) is expressed as REAlO ₃ , but RE in REAlO ₃ is not particularly limited, and the rare earth elements (RE) listed for the crystalline phase (B) are used. ) As well.
The REAlO ₃ is preferably selected from SmAlO ₃ (RE is Sm) and GdAlO ₃ (RE is Gd). Further, SmAlO ₃ and GdAlO ₃ may be included at the same time. Sufficient adsorptive power can be obtained by including these compounds.

The method for introducing the crystal phase (C) (REAlO ₃ ) into the crystal phase (A) or the crystal phase (B) is not particularly limited, but a method of adding REAlO ₃ powder to the raw material is preferable. In the method of producing by reacting raw material powders during firing, the amount of REAlO ₃ produced varies depending on the temperature difference or pressure difference between the center and the periphery when a large sintered body having a diameter of about 300 mm is produced. There is a possibility that the crystal phase (C) cannot be set to a desired content based on this, or the content in the sintered body may vary.

  In the electrostatic chuck of this embodiment, at least a portion of the electrostatic chuck exposed to the halogen-based corrosive gas or plasma thereof is a part of the yttrium aluminum oxide crystal phase (A) or yttrium aluminum oxide. As long as it is a composite oxide sintered body including a crystal phase (B) obtained by substituting a rare earth element excluding yttrium and a rare earth element-aluminum oxide crystal phase (C) excluding yttrium. There are no particular restrictions.

<Manufacturing method of electrostatic chuck>
Next, a method for manufacturing an electrostatic chuck according to the present invention will be described in the same manner by embodiments.
The manufacturing method of the electrostatic chuck of the present embodiment is a method of manufacturing the electrostatic chuck of the present embodiment described above, and (a) a slurry preparation step of preparing a slurry in which raw material powder is dispersed in a solvent; (B) After the slurry is granulated into granules, the molding step includes forming the granules into a molded body having a predetermined shape, and (c) a firing step of firing the molded body. As the raw material powder in the slurry preparation step, aluminum oxide powder, yttrium oxide powder, and rare earth element-aluminum oxide powder excluding yttrium are used. The raw material powder may further contain rare earth element oxide powder excluding yttrium.

As described above, as the method of introducing crystal phase (A) or a crystal phase to a crystal phase (B) (C) (REAlO 3), control of the REAlO ₃ content of the product amounts and in the sintered body of the REAlO ₃ A method of adding REAlO ₃ powder to the raw material is preferable from the viewpoint of ease of treatment.

For example, Patent Document 1 reports a corrosion-resistant material containing yttrium aluminum oxide in which part of yttrium oxide is replaced with samarium oxide, orthorhombic aluminum oxide, and samarium oxide. In the manufacturing method in γ, yttrium aluminum oxide and SmAlO ₃ are simultaneously produced by reaction by firing raw material mixed powder (mixture of Y ₂ O ₃ powder, Al ₂ O ₃ powder and Sm ₂ O ₃ powder). Here, the Sm ₂ O ₃ powder reacts with the Al ₂ O ₃ powder to produce SmAlO ₃ , but it also dissolves in the crystal structure of yttrium aluminum oxide, so this method controls the amount of SmAlO ₃ produced. It is difficult. Further, with regard to yttrium aluminum oxide, the Al ₂ O ₃ powder decreases with the formation of SmAlO ₃ , which may cause compositional deviation.

On the other hand, in this embodiment, REAlO ₃ powder is added to the raw material, so that a crystal phase obtained by substituting a part of yttrium aluminum oxide crystal phase (A) or yttrium of yttrium aluminum oxide with a rare earth element excluding yttrium ( A composite oxide sintered body containing B) and the rare earth element-aluminum oxide crystal phase (C) excluding yttrium can be efficiently produced.
Hereafter, each process is demonstrated concretely.

-(A) Slurry preparation process-
In this step, a slurry is prepared by mixing and dispersing powder as a raw material for each crystal phase in a solvent.
First, the average particle diameter of the primary particles of the raw material powder, aluminum oxide powder, yttrium oxide powder, rare earth element-aluminum oxide powder excluding yttrium, and rare earth element oxide powder excluding yttrium, It is preferable that it is about 0.01-1.0 micrometer. By being about 0.01 to 1.0 μm, the handling is prevented from being lowered, the sinterability is deteriorated, the density is prevented from being lowered, and the corrosive gas due to the increase in the particle diameter in the sintered body or its Degradation in plasma can also be effectively prevented.
As the raw material powder, commercially available powders can be used.

The SmAlO ₃ powder and the GdAlO ₃ powder may be prepared by mixing raw material powders at a predetermined ratio and calcining. The calcination is performed in the range of 800 ° C. to 1600 ° C., preferably in the range of 1000 ° C. to 1400 ° C. for 1 hour to 10 hours, whereby REAlO ₃ powder (RE is Sm and Gd) is obtained. If the temperature is less than 800 ° C., the reaction may not proceed and the desired powder may not be obtained. If the temperature exceeds 1600 ° C., grain growth occurs and the dispersibility decreases when dispersed in a solvent in the next step. There is a case.

  A solvent is used to mix the raw material powders into a slurry. There is no restriction | limiting in particular in this solvent, For example, water, alcohol, etc. are mentioned. Moreover, you may use a dispersing agent for mixing of raw material powder. There are no particular restrictions on the dispersant, and those that adsorb on the particle surface and increase the dispersion efficiency are used, but in order to reduce metal impurities, those that do not contain metal ions as counter ions are desirable. It is preferable to add a dispersant also in the sense of preventing heteroaggregation of different particles.

  It is efficient to use a disperser for mixing the raw material powder and preparing the slurry. The use of the disperser improves the adsorption efficiency of the dispersant on the particle surface, and enables uniform mixing of different particles. The disperser is not particularly limited, and for example, a disperser using a medium such as an ultrasonic wave, a planetary ball mill, a ball mill, or a sand mill, or a medialess disperser such as an ultra-high pressure pulverizer can be suitably used. The above-mentioned medialess disperser is less advantageous in the production of electrostatic chucks for semiconductor manufacturing apparatuses because of less contamination during dispersion.

-(B) Molding process-
In this step, the slurry obtained in the step (a) is granulated into granules, and the granules are further formed into a molded body.
The method of granulating the slurry from the above into a granule shape is not particularly limited, and includes known granulation methods such as rolling granulation method, fluidized bed granulation method, stirring granulation method, spray drying granulation method, As a granulator, a spray dryer etc. are used suitably, for example. As for the particle size of the granule after granulation, it is desirable that it is the range of 50 micrometers-100 micrometers. The average particle diameter of the granules can be obtained as an average obtained by measuring the maximum diameter of 100 particles using an optical microscope.
Next, this granule is molded into a predetermined shape by a known molding means.

-(C) Firing step-
In this step, the molded body obtained above is fired.
First, the molded body is degreased in the air at about 50 to 600 ° C., and then in the air or in an inert gas atmosphere, about 1400 ° C. to 1800 ° C., preferably 1550 ° C. to 1750 ° C. for about 1 to 10 hours. By firing, a dense sintered body having a relative density of 98% or more can be produced. If the temperature is less than 1400 ° C., sintering does not proceed and the density may not increase. Moreover, since melting | dissolving will occur when it exceeds 1800 degreeC, it is unpreferable.
As a firing method, normal pressure firing may be used, but in order to obtain a dense sintered body, a pressure firing method such as hot pressing or hot isostatic pressing (HIP) is preferable. The pressure applied during pressure firing is not particularly limited, but is usually about 10 to 40 MPa.

  The electrostatic chuck of the present embodiment obtained as described above includes, for example, a plate-like body having a sample mounting surface for electrostatically adsorbing a sample, and an internal electrode for electrostatic adsorption provided on the back surface thereof. It is used for an electrostatic chuck device comprising an electrostatic chuck member having a layer and an insulating material layer. Specifically, in this electrostatic chuck device, at least the sample mounting surface of the plate-like body having the sample mounting surface used for the electrostatic chuck member constitutes the electrostatic chuck of the present embodiment described above. The composite oxide sintered body, and the plate-like body itself may be a layer of the composite oxide sintered body.

In the electrostatic chuck device having the above configuration, the thickness of the composite oxide sintered body constituting the plate-like body in the electrostatic chuck member is 0.3 to 2 from the viewpoint of the applied voltage and the electrostatic adsorption force. A range of 0.0 mm is preferable, and a range of 0.3 to 1.0 mm is more preferable.
In the electrostatic chuck apparatus, for example, an electrostatic chuck member having a plate-like body made of a complex oxide sintered body layer having a thickness of 0.5 mm is applied to a sample mounting surface temperature of 25 ° C. at 1.5 kV. The electrostatic attraction force when a voltage is applied can be set to 10 to 30 kPa.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
In addition, the various characteristics in each example were measured according to the method shown below.
(1) Primary average particle diameter of metal oxide powder raw material Using a transmission electron microscope (manufactured by Hitachi, Ltd., model name: H-800), the maximum diameter was measured for 50 particles, and the average was obtained.
(2) Relative Density of Sintered Body The density of the sintered body was measured by the Archimedes method, and the ratio (relative density) to the theoretical density determined by the following formula (2) was calculated.
<Theoretical density>
Theoretical density = unit cell weight (g) / unit cell volume (cm ³ ) (2)
Unit cell weight: (unit cell weight of yttrium aluminum oxide crystal phase × mol% of each crystal phase) + (unit cell weight of REAlO ₃ crystal phase × mol% of each crystal phase)
Unit cell volume: (each unit cell volume of yttrium aluminum oxide crystal phase × mol% of each crystal phase) + (unit cell volume of REAlO ₃ crystal phase × mol% of each crystal phase)
The mol% of each crystal phase of yttrium aluminum oxide and REAlO ₃ was calculated from the charged amount of raw material powder.

(3) Identification of crystal phase in sintered body and content of crystal phase (C) Using powder X-ray diffractometry, as an X-ray diffractometer, using PAnalytial, model name “X'Pert PRO MPD” The crystal phase was identified. In Table 1, the crystal phase (I) represents an yttrium aluminum oxide crystal phase, G represents a garnet crystal phase, and M represents a monoclinic crystal phase. The crystal phase (II) indicates a REAlO ₃ crystal phase, where O is an orthorhombic crystal phase and T is a trigonal crystal phase. The identified crystal phase was common at the center and the periphery of the sintered body.
The content of the crystal phase (C) (REAlO ₃ crystal phase) is determined from the highest peak intensity ratio (crystal phase (II) / crystal phase (I)) of the crystal phase (I) and the crystal phase (II). It calculated | required by Formula (1).
(4) Relative dielectric constant of sintered body The dielectric constant in a frequency range from 40 Hz to 1 MHz was measured using a model name “Agilent 4294A Precision Impedance Analyzer” manufactured by Agilent as a measuring instrument. The sintered body was processed into 60 mm × 60 mm × 2 mm.

(5) Adsorption power and residual adsorption power of sintered body (i) Adsorption power of sintered body The sintered body is processed to a thickness of 0.5 mm and bonded with an alumina ceramic / electrode / sintered structure. The adsorption force with respect to a 1 inch silicon wafer was measured under the conditions of an applied voltage of 1.5 kV, an applied time of 60 seconds, and a vacuum (<0.5 Pa) at a mounting surface temperature of 25 ° C. The measurement was performed by peeling using a load cell, and the maximum peeling stress generated at that time was taken as the adsorption force.
(Ii) Residual adsorption force of the sintered body The sintered body is processed to a thickness of 0.5 mm and bonded with the structure of alumina ceramics / electrode / sintered body, in vacuum (<0.5 Pa), sample mounting surface After applying an applied voltage of 5.0 kV for 60 seconds at a temperature of 25 ° C., the voltage application was canceled and measurement was performed immediately thereafter. The measurement was performed by peeling using a 1-inch silicon wafer, and the maximum peeling stress generated at that time was defined as the residual adsorption force.

(6) Four-point bending strength of sintered body A test piece according to JIS R1601 was cut out from the sample, and the bending strength was measured in a four-point bending test using the model name “Instron 4206 Universal Material Testing Machine” manufactured by INSTRON. (Average of 10) was measured.
Note that (3) X-ray diffraction and (5) adsorption force measurement were performed at the center and the periphery of a sintered body having a diameter of 300 mm. Here, the center is a range within 50 mm from the center point, and the periphery is a range within 50 mm from the outer periphery. Moreover, (2) relative density, (4) relative dielectric constant, and (6) four-point bending strength were measured at the periphery.

<Preparation of raw material powder>
(1) Production of SmAlO ₃ powder Both commercially available aluminum oxide (Al ₂ O ₃ ) powder having an average primary particle diameter of 0.1 μm measured by a transmission electron microscope and commercially available samarium oxide (Sm ₂ O). ₃ ) The powder was weighed so that the molar ratio was 50/50, and then wet-mixed by a well-known dispersion method using water as a solvent. The obtained slurry was evaporated to dryness on a hot plate, and the dried product was pulverized in a mortar. The pulverized powder was divided into 2 minutes and calcined separately at 1000 ° C. and 1200 ° C., respectively, and then made into type I and type II SmAlO ₃ powders, respectively. As a result of powder X-ray diffraction, the obtained SmAlO ₃ powder was an orthorhombic crystal phase and type II was a trigonal crystal phase.

(2) Production of GdAlO ₃ powder Both commercially available aluminum oxide (Al ₂ O ₃ ) powder having an average primary particle size of 0.1 μm measured by a transmission electron microscope and commercially available gadolinium oxide (Gd ₂ O) ₃ ) The powder was weighed so that the molar ratio was 50/50, and then wet-mixed by a well-known dispersion method using water as a solvent. The obtained slurry was evaporated to dryness on a hot plate, and the dried product was pulverized in a mortar. The pulverized powder was calcined at 1200 ° C. and then made into GdAlO ₃ powder. The obtained GdAlO ₃ powder was a perovskite crystal phase as a result of powder X-ray diffraction.

<Examples 1 to 11, Comparative Examples 1 to 6, Reference Examples 1 and 2>
(Preparation of slurry)
In each case, a commercially available aluminum oxide (Al ₂ O ₃ ) powder and a commercially available yttrium oxide (Y ₂ O ₃ ) powder in which the average particle diameter of primary particles measured by a transmission electron microscope (TEM) is 0.1 μm. , And a commercially available samarium oxide (Sm ₂ O ₃ ) powder and a commercially available gadolinium oxide (Gd ₂ O ₃ ) powder were weighed so as to have the composition shown in the raw material (I) in Table 1 below. Next, the weighed raw material (I) and the prepared REAlO ₃ powder (RE is at least one of Sm and Gd) shown in the raw material (II) in Table 1 were mixed in the ratio shown in the table.
These mixed powders were dispersed with an optimizer using water as a solvent and wet-mixed to obtain a mixed powder slurry.

(Production and firing of molded body)
Thereafter, the slurry was granulated with a spray dryer to obtain granules. Next, this granule was molded into a predetermined shape by a known molding means. Next, using a hot press, it was pressure fired at 1600 ° C. for 2 hours in an argon gas to obtain a sintered body having a diameter of 300 mm. In addition, the applied pressure in this case is 20 MPa.
The obtained sintered body is processed to a thickness of 0.5 mm and used for X-ray diffraction measurement and relative dielectric constant measurement, and bonded with an alumina ceramic / electrode / sintered structure to be used for evaluation of adsorption force measurement. It was.
The composition of each example and comparative example and the characteristics of the sintered body are summarized in Table 1 below.

From the evaluation results shown in Table 1, the following matters were found.
In the case where 10% by mass of SmAlO ₃ is added to yttrium aluminum oxide alone as in Example 1, the relative density is 99.5% or more, and the yttrium aluminum oxide is garnet structure, and SmAlO ₃ is orthorhombic. System structure. Although the dielectric constant at a frequency of 40 Hz is as low as 12, the attractive force is as large as 25 kPa, and the residual attractive force is as low as 0.6 kPa, and there is no difference between the center and the periphery.
The attractive force of the Coulomb force type electrostatic chuck is expressed by the following formula (3). Since the calculated value estimated from this is about 1 kPa, the sintered body of this example has a value of about 25 times. ing.
F = 1 / 2ε ₀ ε _r (V / d) ² (3)
In the above equation, ε ₀ is the dielectric constant of vacuum, ε _r is the dielectric constant of the dielectric, V is the applied voltage (V), and d is the thickness (m) of the dielectric.

In addition, in the case where SmAlO ₃ was added to 5% by mass to 30% by mass of the yttrium aluminum oxide of Examples 2 to 5 added to Sm, the result was almost the same as that of Example 1.
In Examples 6 to 8, the rare earth element of Example 3 was changed from Sm to a part or all of Gd, and in Examples 9 and 10, the SmAlO ₃ crystal phase was changed to an orthorhombic crystal phase and a trigonal crystal phase. However, as in Example 3, the adsorptive power was a high value. Further, in Example 11, the yttrium aluminum oxide crystal phase was changed from a garnet single phase to a mixed crystal of a garnet crystal phase and a monoclinic crystal phase, but the same result was obtained.

On the other hand, as in Comparative Examples 1 to 4, when REAlO ₃ is not added and the N _RE / N _Y + N _RE ratio is low, the relative density, crystal structure, and relative dielectric constant are almost the same as in the above examples. However, the attractive force decreases to about 1/10. This is presumed that the Johnson Rahbek force, which was manifested by the addition of REAlO ₃ , was reduced to approximate the attractive force of the original relative dielectric constant. Further, in the case of a large amount of SmAlO ₃ as in Comparative Examples 5 and 6, the adsorption force is high, but the residual adsorption force increases to 1 kPa or more, and the four-point bending strength decreases to 150 MPa or less. It is thought that the increase in the residual adsorption force is due to the SmAlO ₃ particles being charged by applying a high voltage, and the decrease in the four-point bending strength is because the abnormally grown particles of SmAlO ₃ became the starting point of the fracture. It is believed that there is. The above N _RE / N _Y + N _RE is the samarium with respect to the sum (N _Y + N _RE ) of the number of yttrium atoms (N _Y ) and one or both of samarium and gadolinium (N _RE ). And the ratio of the number of atoms (N _RE ) of either one or both of gadolinium.

Further, as in Reference Examples 1 and 2, rare earth elements (RE) are added beyond the solid solution limit by increasing the N _RE / N _Y + N _RE ratio without adding REAlO _3, and during sintering It is possible to produce REAlO ₃ . However, in this manufacturing method, in-plane uniformity is lost because the amount of REAlO ₃ produced varies depending on the temperature difference or pressure difference between the center and the periphery. The causes suction force is high, the introduction of REAlO ₃ in the sintered body, because the REAlO ₃ to form a new conductive layer, to exhibit the effect of lowering the volume resistivity of the yttrium oxide aluminum. Therefore, it is presumed that the adsorption power is increased because the Johnson-Rahbek force, which involves electronic conduction, is added in addition to the Coulomb force inherently generated by dielectric polarization of yttrium aluminum oxide.

As described above, according to the electrostatic chuck of the present invention and the electrostatic chuck apparatus including the same, the portion exposed to the halogen-based corrosive gas or the plasma thereof is made of yttrium aluminum oxide crystal phase or yttrium aluminum oxide. By introducing a rare earth element-aluminum oxide (REAlO ₃ ) crystal phase excluding yttrium into a crystal phase obtained by substituting a part of yttrium with a rare earth element (RE) excluding yttrium, the above corrosive gas or Semiconductor manufacturing that does not cause degradation or generation of particles even when exposed to plasma, has a commercially sufficient adsorption power of 10 kPa or more at an applied voltage of 1.5 kV, and has almost no variation in the in-plane adsorption force. An electrostatic chuck can be obtained.
Moreover, since the thickness of the dielectric layer can be increased as compared with the conventional metal oxide due to the increase in the adsorption power, the withstand voltage is increased and the risk of breakage during operation is reduced. It also reduces the risk of cracking during processing.

Claims (5)

A crystal phase (B) obtained by replacing a part of yttrium aluminum oxide crystal phase (A) or yttrium of yttrium aluminum oxide with a rare earth element other than yttrium, and a rare earth element-aluminum oxide crystal phase (C) excluding yttrium Including a complex oxide sintered body,
The crystalline phase which is calculated by the following equation based on X-ray diffraction profile (1) the content of (C) is state, and are 10% less than 0.05%,
The crystal phase (C) is REAlO ₃ ( wherein RE is any of Sc, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) electrostatic chuck it expresses at or represents).
Content (%) of crystal phase (C) = [(highest peak intensity based on crystal phase (C)) / (highest peak intensity based on yttrium aluminum oxide)] × 100 (1)   The electrostatic chuck according to claim 1, wherein the rare earth element excluding yttrium is at least one of samarium and gadolinium.   The electrostatic chuck according to claim 1, wherein the crystal structure of the crystal phase (C) is at least one of an orthorhombic crystal phase and a trigonal crystal phase. It is a manufacturing method of the electrostatic chuck according to any one of claims 1 to 3,
(A) a slurry preparation step of preparing a slurry in which raw material powder is dispersed in a solvent; (b) a molding step of granulating the slurry into granules and then forming the granules into a predetermined shape; (C) a firing step of firing the molded body,
The raw material powder in the slurry preparation step, an aluminum oxide powder, yttrium oxide powder, and rare earth elements except yttrium - Ri powder Der aluminum oxide,
The rare earth element-aluminum oxide powder excluding the yttrium is REAlO ₃ (wherein RE is Sc, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, tm, Yb, and a manufacturing method of an electrostatic chuck express either represent a) of Lu.   The method for manufacturing an electrostatic chuck according to claim 4, wherein the raw material powder further contains a rare earth element oxide powder excluding yttrium.