JP5454623B2 - Sintered body and manufacturing method thereof - Google Patents

Description

  The present invention relates to a sintered body having excellent corrosion resistance and thermal conductivity against halogen-based corrosive gases and their plasmas, and also having excellent conductivity, and a method for producing the same. A sintered body suitable for halogen-based corrosive gases and members exposed to these plasmas, such as constituent materials of vacuum processing apparatuses such as etching apparatuses, sputtering apparatuses, and CVD apparatuses applied to the present invention, and a method for manufacturing the same It is.

  2. Description of the Related Art Conventionally, in production lines for semiconductor devices such as IC, LSI, and VLSI, ceramics such as alumina have been used as members used under severe conditions such as exposure to halogen-based corrosive gases such as chlorine and fluorine and plasmas thereof. Members made of materials are widely used. Examples of the ceramic parts in the semiconductor manufacturing apparatus include an electrostatic chuck, a clamp ring, a focus ring, and an etching electrode. As materials constituting these parts, ceramic materials having improved corrosion resistance have been proposed (see, for example, Patent Documents 1 and 2).

  Further, in the process using the halogen-based corrosive gas and the plasma described above, a member that requires conductivity in addition to corrosion resistance, such as an etching electrode or a wafer chuck, is used. As such a member, for example, a member obtained by adding a carbon nanotube to aluminum oxide or a member obtained by adding silicon carbide to aluminum nitride has been reported (for example, see Patent Documents 3 and 4).

Japanese Patent Laid-Open No. 11-246263 JP 2002-255647 A JP 2004-244273 A JP 2003-152062 A

  However, when silicon carbide is added as a conductive substance, the corrosion resistance against halogen-based plasma is not sufficient, and when used as a corrosion-resistant member for semiconductor applications, it becomes difficult to apply because it becomes a source of particles. Further, since silicon carbide is mainly spherical particles, in order to develop conductivity, the silicon carbide content needs to be 20% by volume or more with respect to 100% by volume of aluminum nitride serving as a base material. Therefore, there has been a problem that the corrosion resistance of the composite material composed of aluminum nitride and silicon carbide is greatly reduced.

In addition, since the carbon nanotube has a high aspect ratio, the sintered body produced with the carbon nanotube content in the base material of 0.01 to 10% by volume can exhibit conductivity of 10 ⁷ Ω · cm or less. It has been reported that this can be done (see, for example, Patent Document 3).
However, such a sintered body contains a large number of aggregates of carbon nanotubes having a diameter of several tens of μm or more. Such agglomeration of carbon nanotubes is caused when the dispersibility of the carbon nanotubes decreases and aggregates again when the base material and the carbon nanotubes are combined. Such aggregates react and disappear in a halogen-based plasma atmosphere, but due to the disappearance of the aggregates, the sintered body has problems such as reduced conductivity, generation of particles, and reduced corrosion resistance. Arise. As described above, the sintered body in which the base material and the carbon nanotube are combined has a problem that the conductivity and the corrosion resistance are lowered as the time of use in the halogen-based plasma atmosphere is increased.

  The present invention has been made in view of the above circumstances, and provides a sintered body in which conductivity and corrosion resistance are prevented from decreasing with time in a halogen-based plasma atmosphere and a method for manufacturing the same. With the goal.

  As a result of intensive studies to solve the above problems, the present inventors have found that a sintered body obtained by combining yttrium oxide or an yttrium-aluminum composite oxide and fibrous carbon has a corrosive gas or plasma atmosphere. Even when applied to members used below, the inventors have found that the conductivity and corrosion resistance do not decrease with time, and have completed the present invention.

The sintered body of the present invention is a sintered body comprising yttrium oxide or an yttrium-aluminum composite oxide and fibrous carbon, and is located at a grain boundary of the yttrium oxide or the yttrium-aluminum composite oxide. The fibrous carbon is three-dimensionally dispersed, the aggregated diameter of the fibrous carbon is 10 μm or less, and the yttrium-aluminum composite oxide is Y ₃ Al ₅ O ₁₂ or Y ₄ Al ₂ O _9. The fibrous carbon is one or more selected from the group of single-walled carbon nanotubes, double-walled carbon nanotubes, and multi-walled carbon nanotubes, and the diameter of the fibrous carbon is 50 nm or less, The length of the fibrous carbon is 25 μm or less, and the content of the fibrous carbon is the yttrium oxide or the yttrium. - not more than 0.01 vol% and 5 vol% relative to aluminum composite oxide 100 vol%, the center line surface roughness (Ra) is 24.5nm or less, volume resistivity 10 ⁴ Ω · 1 × The center line surface roughness after corrosion resistance test exposed to plasma for 8 hours in a mixed gas of halogenated hydrocarbon gas, oxygen gas and argon gas is 597.2 nm or less, and the volume resistivity is Ri 1 × 10 ⁴ Ω · cm der below, the relative density is equal to or less than 95%.

The relative density may be 97%.
The yttrium-aluminum composite oxide is preferably Y ₃ Al ₅ O ₁₂ or Y ₄ Al ₂ O ₉ .
The fibrous carbon is preferably one or more selected from the group of single-walled carbon nanotubes, double-walled carbon nanotubes, and multi-walled carbon nanotubes.

The diameter of the fibrous carbon may be larger than 50 nm .
The fibrous carbon content is preferably 0.01% by volume to 5% by volume with respect to 100% by volume of the yttrium oxide or the yttrium-aluminum composite oxide.

The method for producing a sintered body according to the present invention is a method for producing the sintered body according to the present invention, in which a yttrium oxide slurry containing yttrium oxide or an yttrium-aluminum composite oxide and a fibrous material containing fibrous carbon. A slurry preparing step for individually preparing a carbon slurry, a mixed slurry preparing step for preparing a mixed slurry by mixing the yttrium-based oxide slurry and the fibrous carbon slurry after the slurry preparing step, and spray drying and granules manufacturing process by law and granulation to obtain granules from the mixed slurry, and sintering the granules possess a sintered body producing step for producing a sintered body, a, in the sintered body production process, The granule is sintered at 1600 ° C. or higher and 1850 ° C. or lower in an inert atmosphere .

  In the slurry preparation step, the solid content of the fibrous carbon slurry is 0.1% by mass or more and 1% by mass or less, and the fibrous carbon slurry is subjected to a pulverization treatment of the fibrous carbon, and then the fibers It is preferable to remove the residual aggregates of the fibrous carbon slurry after the dispersion treatment of the fibrous carbon in the solvent.

According to the sintered body of the present invention, it is a sintered body containing yttrium oxide or an yttrium-aluminum composite oxide and fibrous carbon, and the particles of the yttrium oxide or the yttrium-aluminum composite oxide. Since the fibrous carbon is three-dimensionally dispersed in the boundary, and the aggregate diameter of the fibrous carbon is 10 μm or less, the fibrous carbon is uniformly distributed to the grain boundary of the yttrium-based oxide to several μm or less. Distributed to form a network structure. As a result, the sintered body of the present invention has an excellent feature of having corrosion resistance against halogen-based corrosive gases and their plasmas and high conductivity of 10 ⁴ Ω · cm or less, and a relative density of 95% or more. Therefore, it can be applied not only as a structural member in a semiconductor manufacturing apparatus, but also to an etching electrode, a dielectric material for an electrostatic chuck, and the like, and its usefulness is very large. Also, no special equipment is required for production, and conventional powder production equipment and sintering equipment can be used as they are.

  According to the method for producing a sintered body of the present invention, it is a method for producing the sintered body of the present invention, comprising yttrium oxide slurry containing yttrium oxide or yttrium-aluminum composite oxide, and fibrous carbon. A slurry preparing step for individually preparing a fibrous carbon slurry, and a mixed slurry preparing step for preparing a mixed slurry by mixing the yttrium-based oxide slurry and the fibrous carbon slurry after the slurry preparing step; Since it has a granule production process for producing granules from the mixed slurry by spray drying and granulation, and a sintered body production process for producing sintered bodies by sintering the granules, it is matched to the plasma atmosphere used. It is also possible to change the yttrium oxide or yttrium-aluminum composite oxide which is a corrosion resistant material. In addition, since the same manufacturing process can be applied even if the constituent materials are changed, the present invention can be widely applied to the manufacture of sintered bodies as long as the constituent materials do not react with each other.

It is a scanning electron microscope (SEM) image which shows the presence state of the fibrous carbon in the sintered compact of Example 1 of this invention.

The best mode of the sintered body and the manufacturing method thereof of the present invention will be described.
This embodiment is specifically described for better understanding of the gist of the invention, and does not limit the present invention unless otherwise specified.

"Sintered body"
The sintered body of the present invention is a sintered body comprising yttrium oxide or an yttrium-aluminum composite oxide and fibrous carbon, and is located at a grain boundary of the yttrium oxide or the yttrium-aluminum composite oxide. The fibrous carbon is three-dimensionally dispersed, and the aggregate diameter of the fibrous carbon is 10 μm or less.

In the sintered body of the present invention, “the fibrous carbon is three-dimensionally dispersed in the grain boundary of yttrium oxide or yttrium-aluminum composite oxide” means that the carbon fiber exhibits a specific orientation. Without being dispersed in the grain boundary portion of the yttrium oxide particles or the yttrium-aluminum composite oxide particles. That is, when a certain volume of the sintered body of the present invention is taken and an average value in the direction of all the carbon fibers contained therein is taken, the value becomes 0 (zero).
Further, the fibrous carbon is not necessarily present between the yttrium oxide particles or the yttrium-aluminum composite oxide particles (grain boundaries), and there may be a grain boundary in which no fibrous carbon exists. That is, fibrous carbon is present randomly at the grain boundary of each particle. The fibrous carbons are in contact with each other to form a network, and a conductive path is formed at the grain boundary.

In the sintered body of the present invention, yttrium oxide (Y ₂ O ₃ ) or yttrium-aluminum complex oxide, which has particularly high corrosion resistance against halogen-based plasma, constitutes the matrix.
As the yttrium-aluminum composite oxide, Y ₃ Al ₅ O ₁₂ (YAG) or Y ₄ Al ₂ O ₉ is preferably used.
In this specification, yttrium oxide and yttrium-aluminum composite oxide may be collectively referred to as “yttrium-based oxide”.

The average particle diameter of the yttrium-based oxide particles is preferably 0.1 μm or more and 10 μm or less, more preferably 0.5 μm or more and 5 μm or less.
The reason why the average particle diameter of the yttrium-based oxide particles is preferably 0.1 μm or more and 10 μm or less is that when the particle diameter is less than that, the total number of grain boundaries of the yttrium-based oxide is increased in the sintered body, and the electrical conductivity is increased. The addition of carbon nanotubes increases and the corrosion resistance decreases. On the other hand, at 10 μm or more, conductivity is exhibited by the addition of a small amount of carbon nanotubes, but the presence of carbon nanotubes is reduced due to a decrease in the total number of grain boundaries. This is because it becomes local and the conductivity in the sintered body is biased.

Further, in the sintered body of the present invention, the fibrous carbon is present as a simple substance or an aggregate in which a plurality of simple fibrous carbons are aggregated in a matrix made of yttrium oxide.
And when fibrous carbon makes an aggregate, the diameter (aggregation diameter) of the aggregate is 10 micrometers or less, Preferably it is 2 micrometers or less.
The reason why the agglomerated diameter of the fibrous carbon is preferably 10 μm or less is that when the agglomerated diameter of the fibrous carbon exceeds 10 μm, the corrosion resistance to the halogen-based plasma is lowered, and the fibrous carbon disappears in the halogen-based plasma atmosphere. This is because it tends to reduce the conductivity, the generation of particles, and the corrosion resistance.

  As the fibrous carbon, single-walled carbon nanotubes (SWCNT: Single Walled Carbon Nanotube), double-walled carbon nanotubes (DWCNT: Double Walled Carbon Nanotube), multi-walled carbon nanotubes (MWCNT: selected from the group of multi-walled carbon nanotubes) 1 type (s) or 2 or more types are used.

Moreover, in the sintered body of the present invention, it is effective to increase the aspect ratio of the fibrous carbon in order to lower the fibrous carbon content and develop conductivity.
Therefore, the diameter of fibrous carbon such as single-walled carbon nanotube, double-walled carbon nanotube, and multi-walled carbon nanotube is preferably 50 nm or less and the length is preferably 25 μm or less, more preferably the diameter of fibrous carbon is 1 nm or more and 30 nm. It is as follows.

The content of fibrous carbon is preferably 0.01% by volume or more and 5% by volume or less, more preferably 0.01% by volume or more and 3% by volume or less.
The reason why the content of fibrous carbon is preferably 0.01% by volume or more and 5% by volume or less is that the sintered carbon is required when the content of fibrous carbon is less than 0.01% by volume. This is because conductivity cannot be expressed. On the other hand, when the content of fibrous carbon exceeds 5% by volume, excessive fibrous carbon is present at the grain boundaries of the yttrium-based oxide, and the aggregate diameter of the fibrous carbon tends to be 10 μm or more, thereby providing corrosion resistance. This is because of a decrease. In particular, since carbon nanotubes have a low thermal conductivity in the radial direction, the thermal conductivity of the sintered body decreases as the carbon nanotube content increases, and heat distribution occurs in the thickness direction of the sintered body during plasma irradiation. This is because the sintered body breaks due to the difference in thermal expansion.

The sintered body of the present invention not only has excellent corrosion resistance against halogen-based corrosive gases and these plasmas, but also has a relative density of 95% and a high conductivity of 1 × 10 ⁴ Ω · cm or less. Have both.

"Sintered body manufacturing method"
The method for producing a sintered body according to the present invention is a method for producing the sintered body according to the present invention, in which a yttrium oxide slurry containing yttrium oxide or an yttrium-aluminum composite oxide and a fibrous material containing fibrous carbon. A slurry preparing step for individually preparing a carbon slurry, a mixed slurry preparing step for preparing a mixed slurry by mixing the yttrium-based oxide slurry and the fibrous carbon slurry after the slurry preparing step, and spray drying It is a method which has a granule preparation process which produces a granule from the mixed slurry by a method and granulation, and a sintered compact production process which sinters the granule and produces a sintered compact.

  In order to form a composite with yttrium oxide without agglomerating the fibrous carbon, a slurry is prepared in which the fibrous carbon is uniformly dispersed in the dispersion in advance (without other dispersed solid components). It is preferable to keep it. Therefore, in a slurry preparation process, the slurry containing only an yttrium-type oxide and the slurry containing only fibrous carbon are prepared separately.

In the slurry preparation step, to prepare an yttrium-based oxide slurry, an yttrium-based oxide (solid content) is added to the dispersion medium so that the content thereof is 40% by mass or more and 70% by mass. A dispersion containing an yttrium oxide is mixed.
The reason why the yttrium oxide content in the yttrium oxide slurry is 40 mass% or more and 70 mass% is that when the mixed slurry is prepared by mixing the yttrium oxide slurry and the fibrous carbon slurry, This is to prevent the slurry from becoming highly viscous.
A method for mixing the dispersion containing the yttrium-based oxide is not particularly limited. For example, a method in which a rotating two-blade homogenizer and a wet ball mill are combined is used.

Moreover, in the slurry preparation step, in order to prepare a fibrous carbon slurry, fibrous carbon (solid content) is added to the dispersion medium so that the content is 0.1 mass% or more and 1 mass% or less. Then, the fibrous carbon-containing dispersion (fibrous carbon slurry) is subjected to a pulverization treatment of the fibrous carbon, and then subjected to a dispersion treatment of the fibrous carbon, and then the fibrous carbon slurry is filtered. And remove coarse agglomerates.
The reason why the content of fibrous carbon in the fibrous carbon slurry is 0.1% by mass or more and 1% by mass or less is that when the content of fibrous carbon exceeds 1% by mass, the fibrous carbon may agglomerate again. This is because the fibrous carbon slurry becomes highly viscous. In addition, if the content rate of the fibrous carbon in the fibrous carbon slurry is 1% by mass or less, there is no particular problem. However, if the content rate of the fibrous carbon is lowered more than necessary, the amount of the solvent used becomes excessive and the production Since problems, such as an increase in cost, arise, it is preferable that the content rate of fibrous carbon is 0.1 mass% or more.

The fibrous carbon has a strong cohesive force, and when the aggregate is spherical, the content of the fibrous carbon necessary for causing the sintered body to exhibit conductivity increases. On the other hand, when the aggregate diameter of the fibrous carbon exceeds 10 μm, the aggregate has a reduced corrosion resistance against the halogen-based plasma and tends to disappear in the halogen-based plasma atmosphere.
Therefore, it is necessary to unravel the aggregates of fibrous carbon until the aggregate diameter reaches a level of several μm. For this purpose, mechanical force must be applied to the dispersion containing fibrous carbon (fibrous carbon slurry) to break up the aggregation. Specifically, after roughly crushing the fibrous carbon with a rotating two-blade homogenizer, the fibrous carbon is finely dispersed with an ultrasonic homogenizer. Apply distributed processing. And the fibrous carbon slurry which performed the crushing process and the dispersion process is filtered with a 45 micrometer mesh filter.
By such pulverization treatment, dispersion treatment and filtration of the fibrous carbon, the aggregate diameter of the fibrous carbon contained in the fibrous carbon slurry becomes 45 μm or less.
The pulverization treatment of fibrous carbon is not limited to a method using a rotating two-blade homogenizer, and any method can be applied as long as the same action can be obtained. Further, the dispersion treatment of fibrous carbon is not limited to a method using an ultrasonic homogenizer, and any method can be applied as long as the same action can be obtained.

  In the slurry preparation step, water and an organic solvent can be used as the solvent. Examples of the organic solvent include monohydric alcohols such as methanol, ethanol, 2-propanol, butanol, and octanol and modified products thereof; alcohols belonging to monocyclic monoterpenes such as α-terpineol; carbs such as butyl carbitol. Tolls; Esters such as ethyl acetate, butyl acetate, ethyl lactate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, butyl carbitol acetate, γ-butyrolactone; diethyl ether, ethylene glycol monomethyl ether (methyl cellosolve), Ethylene glycol monoethyl ether (ethyl cellosolve), ethylene glycol monobutyl ether (butyl cellosolve), diethylene glycol monomethyl ether Ethers such as diethylene glycol monoethyl ether; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, acetylacetone, and cyclohexanone; aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene; dimethylformamide, N, N-dimethylacetoacetamide Amides such as N-methylpyrrolidone are preferably used, and one or more of these solvents can be used.

In the slurry preparation step, a dispersant or a binder may be added to the yttrium oxide slurry and the fibrous carbon slurry.
As the dispersant and binder, for example, polycarboxylic acid ammonium salts, organic polymers such as polyethylene glycol, polyvinyl alcohol, and polyvinylpyrrolidone are used.

  In the mixed slurry preparation step, the method of mixing the yttrium-based oxide slurry and the fibrous carbon slurry is not particularly limited. For example, a method in which a rotating two-blade homogenizer and a wet ball mill are combined is used.

In the granule preparation process, from the mixed slurry prepared in the mixed slurry preparation process, by drying the composite particles of yttrium oxide and fibrous carbon by the spray drying method, and granulating the composite particles, A granule having a particle diameter of 30 μm or more and 100 μm or less is prepared by combining yttrium oxide and fibrous carbon.
According to the spray drying method, by spraying the mixed slurry into the heated gas, the composite particles composed of these are rapidly dried while maintaining the dispersibility of the yttrium oxide and the fibrous carbon in the mixed slurry. be able to.
In addition, the particle size of the granules is appropriately adjusted to such a size that good characteristics can be obtained in the subsequent steps such as molding, degreasing, and sintering, after the granule preparation step.

In the sintered body production step, it is preferable that the granules produced in the granule production step are sintered at 1600 ° C. or higher and 1850 ° C. or lower in an inert atmosphere such as nitrogen (N ₂ ) or argon (Ar).
In the sintered body preparation process, it is preferable to sinter the granule at 1600 ° C. or higher and 1850 ° C. or lower. If the sintering temperature is lower than 1600 ° C., the fibrous carbon inhibits the sintering of the yttrium oxide. This is because a sintered body having a sufficient relative density (relative density of 95% or more) cannot be obtained. On the other hand, when the sintering temperature exceeds 1850 ° C., the yttrium-based oxide and the fibrous carbon react directly to form a carbide. It is because it forms.

  According to the method for producing a sintered body of the present invention, a sintered body in which fibrous carbon having an aggregate diameter of 10 μm or less is present at the grain boundary of the yttrium-based oxide can be obtained. Moreover, by controlling the aggregate diameter of fibrous carbon as described above, a sintered body having excellent corrosion resistance against halogen plasma and excellent conductivity and thermal conductivity can be obtained.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further more concretely, this invention is not limited to a following example.

[Production of sintered body]
"Example 1"
Multi-walled carbon nanotubes having a diameter of 10 nm to 50 nm and a length of 1 μm to 25 μm are added to denatured ethanol so that the solid content is 0.5 mass%, and further a dispersant is added. Then, by a rotating two-blade type homogenizer device, 20 The multi-walled carbon nanotubes were crushed with respect to the modified ethanol containing multi-walled carbon nanotubes for a minute. Next, the denatured ethanol was subjected to a dispersion treatment of multi-walled carbon nanotubes with an ultrasonic homogenizer for 1 hour, and then passed through a 45 μm mesh filter to prepare a carbon nanotube slurry.
In addition, yttrium oxide powder (average particle size 3 μm, manufactured by Japan Yttrium Co., Ltd.) is added to denatured ethanol so that the solid content is 60% by mass, and the yttrium oxide powder is contained for 10 minutes with a rotating two-blade homogenizer. A dispersion of yttrium oxide powder was applied to the modified ethanol to prepare a slurry of yttrium oxide.
Next, the carbon nanotube slurry and the yttrium oxide slurry were stirred and mixed with a stirring blade so that the carbon nanotube content was 0.01% by volume to prepare a mixed slurry.
Next, this mixed slurry was treated for 10 minutes with a rotating two-blade homogenizer, and then wet-mixed for 18 hours with a rotating ball mill.
Next, the composite particles of carbon nanotubes and yttrium oxide are dried from the mixed slurry in a nitrogen atmosphere by spray drying, and the composite particles are granulated to form composites of carbon nanotubes and yttrium oxide. Thus, granules having a particle size of 30 μm or more and 100 μm or less were prepared.
Subsequently, this granule was degreased at 500 ° C. under an argon atmosphere.
Next, the degreased granules were uniaxially pressed at a pressure of 5 MPa, and then hot-press sintered at 1850 ° C. for 2 hours under an argon atmosphere at a pressure of 20 MPa to obtain a disk-like sintered product having a diameter of 50 mm and a thickness of 6 mm. A ligature was obtained.

"Example 2"
A sintered body was produced in the same manner as in Example 1 except that the carbon nanotube content was set to 0.1% by volume.

"Example 3"
A sintered body was produced in the same manner as in Example 1 except that the carbon nanotube content was 3% by volume.

Example 4
A sintered body was produced in the same manner as in Example 1 except that the carbon nanotube content was set to 5% by volume.

"Example 5"
A sintered body was prepared in the same manner as in Example 1 except that the solid content of the carbon nanotube was changed to 1% by mass in the carbon nanotube slurry.

"Example 6"
A sintered body was produced in the same manner as in Example 1 except that the sintering temperature was 1600 ° C.

"Example 7"
A sintered body was produced in the same manner as in Example 1 except that single-walled carbon nanotubes having a diameter of 10 nm to 50 nm and a length of 1 μm to 25 μm were used as the carbon nanotubes.

"Example 8"
Instead of yttrium oxide, Y ₃ Al ₅ O ₁₂ (YAG, average particle size of 3 μm, which is an yttrium-aluminum composite oxide), which is obtained by pulverizing yttrium oxide and aluminum oxide reacted at 1500 ° C. in the atmosphere. The raw material is that of Example 1.
A sintered body was produced in the same manner as in Example 1 except that the aluminum oxide raw material was manufactured by Daimei Chemical Co., Ltd., with an average particle size of 0.2 μm.
Table 1 shows the compositions and production methods of the sintered bodies of Examples 1 to 8.

"Comparative Example 1"
A sintered body was produced in the same manner as in Example 1 except that only the yttrium oxide slurry was used without using the carbon nanotube slurry.

"Comparative Example 2"
A sintered body was produced in the same manner as in Example 1 except that the carbon nanotube content was 0.005% by volume.

“Comparative Example 3”
A sintered body was produced in the same manner as in Example 1 except that the carbon nanotube content was 8% by volume.

“Comparative Example 4”
Sintered body in the same manner as in Example 1 except that the carbon nanotube content was 3% by volume, the carbon nanotube slurry was not treated with an ultrasonic homogenizer, and was not passed through a 45 μm mesh filter. Was made.

"Comparative Example 5"
The carbon nanotube content is 3% by volume, the carbon nanotube slurry is not treated with a rotating two-blade homogenizer, not treated with an ultrasonic homogenizer, and not passed through a 45 μm mesh filter. In addition, a sintered body was produced in the same manner as in Example 1 except that only the treatment with ultrasonic waves for 10 minutes was performed.

“Comparative Example 6”
Without using the spray drying method, the mixed slurry was naturally dried, and the lump obtained by drying was granulated with a sieve to produce granules having a particle size of 250 μm or less. A ligature was prepared.

“Comparative Example 7”
A sintered body was produced in the same manner as in Example 1 except that the solid content of the carbon nanotube was changed to 1.5 mass% in the carbon nanotube slurry.
Table 2 shows the compositions and manufacturing methods of the sintered bodies of Comparative Examples 1 to 7.

[Evaluation of sintered body]
For the sintered bodies of Examples 1 to 8 and Comparative Examples 1 to 7, the aggregated diameter, relative density, volume resistivity (Ω · cm), thermal conductivity, surface roughness, corrosion resistance, and corrosion resistance test of carbon nanotubes The appearance was evaluated.
The volume resistivity and surface roughness were evaluated for changes before and after the corrosion resistance test.
Note that Comparative Example 7 was not evaluated because the carbon nanotubes were extremely agglomerated and gelled at the stage of producing the carbon nanotube slurry, and a sintered body could not be produced.
Table 3 shows the evaluation results of Examples 1-8 and Table 4 shows the evaluation results of Comparative Examples 1-7.

The evaluation method is as follows.
(1) Agglomerated diameter of carbon nanotubes The surface of the sintered body whose surface was lapped and polished was used to create a color map showing the carbon distribution state by an electron probe microanalyzer (EPMA), and the agglomerated diameter of the carbon nanotubes was measured.
Moreover, about Example 1, the torn surface of the sintered compact was observed using the scanning electron microscope (SEM).

(2) the true density of the relative density sintered body of _{(d 0)} was measured by the Archimedes method, it represents the ratio _(d 0 / _{d r)} with respect to the theoretical density _{(d r)} of the true density _{(d 0)} in percentage, Relative density (%) was used.

(3) Volume resistivity value Japanese Industrial Standard: According to the method specified in JIS C2141, the volume resistivity value of 10 ⁷ Ω · cm or less is the 4-terminal method, and the volume resistivity value is more than the 3-terminal method. It was measured by. The measurement voltage was 10V.

(4) Thermal conductivity Japanese Industrial Standard: Measured according to a method (laser flash method) defined in JIS R1611. The shape of the test piece was 10 mm in diameter × 2 mm in length.

(5) Surface roughness Japanese Industrial Standards: Centerline average roughness (Ra value) was measured according to the method (stylus type) defined in JIS B0651.

(6) Corrosion resistance The sintered body was exposed to plasma for 8 hours in a mixed gas of halogenated carbon gas, oxygen gas and argon gas, the consumption depth per hour was measured, and the corrosion resistance was evaluated.

(7) Evaluation of appearance The appearance after the corrosion resistance test was visually evaluated.
Here, “◯” indicates that no surface roughness is observed, “Δ” indicates that voids or depressions are observed on the sample surface, and “x” indicates that cracks or fractures are observed in the sample.

From the results of Tables 3 and 4, from the measurement results of the aggregate diameter of carbon nanotubes by EPMA, (a) the content of carbon nanotubes was 5% by volume or less with respect to 100% by volume of yttrium oxide, and (b) The slurry is processed by a rotating two-blade homogenizer and an ultrasonic homogenizer, and then prepared by a method of passing through a 45 μm mesh filter. (C) Granules are granulated from the mixed slurry by spray drying. In the sintered body produced through all of the steps, the aggregate diameter of the carbon nanotubes is 10 μm or less, whereas in the sintered body produced without passing through one of the three steps, the carbon nanotubes It was found that the aggregate diameter exceeded 10 μm.
FIG. 1 is a scanning electron microscope image (SEM image) of the fracture surface of the sintered body of Example 1.
In FIG. 1, what is indicated by an arrow is a carbon nanotube. According to this SEM image, it was found that carbon nanotubes exist at the grain boundaries of yttrium oxide.

In the sintered bodies sintered at 1850 ° C. in Examples 1 to 5, 7, 8, and Comparative Examples 1 to 6, the relative density was 97% or more.
In the sintered body sintered at 1600 ° C. in Example 6, the relative density decreased to 95.1%. When the relative density of the sintered body is less than 95%, the open pores on the surface are connected to the vacancies inside the sintered body, and the plasma that has entered the inside of the sintered body reacts with the carbon nanotubes to reduce the conductivity. Sintering in the temperature range of 1600 ° C. to 1850 ° C. is considered essential.

The relationship between the electrical conductivity indicated by the volume resistivity and the aggregation state of the carbon nanotubes was as follows.
As shown in Examples 1 to 4, among the sintered bodies in which the carbon nanotube content is 5% by volume or less with respect to 100% by volume of yttrium oxide, the aggregate diameter of the carbon nanotubes is 10 μm or less, That is, when the carbon nanotube was well dispersed, the volume resistivity of the sintered body was 10 ⁴ Ω · cm or less, and it was found that this conductivity hardly changed even after the corrosion resistance test.

In the sintered body of Comparative Example 2 in which the carbon nanotube content is 0.005% by volume or less, the aggregate diameter of the carbon nanotubes is 2 μm or less, and the dispersion state is good, but the absolute amount of the carbon nanotubes is Since it was insufficient, the required conductivity (10 ⁴ Ω · cm or less) was not exhibited.
In the sintered body of Comparative Example 3 in which the content of carbon nanotubes is 8% by volume or less, although some carbon nanotubes with an aggregate diameter of 20 μm are seen, the aggregate diameter of most carbon nanotubes is 10 μm or less. Thus, it was found that there was little change in conductivity before and after the corrosion resistance test.
In the sintered body of Comparative Example 6 in which the content of carbon nanotubes was 3% by volume or less and the mixed slurry was not dried by the spray drying method, the aggregate diameter of the carbon nanotubes was the same as that of the sintered body of Comparative Example 3 Therefore, it was found that there was little change in conductivity before and after the corrosion resistance test.

In the sintered body of Comparative Example 4, carbon nanotubes having an aggregate diameter of 10 μm or more account for the majority, and these carbon nanotubes disappeared in the corrosion resistance test, and the conductivity decreased after the corrosion resistance test.
In the sintered body of Comparative Example 5, the aggregate diameter of the carbon nanotubes was 50 μm to 1500 μm, and the aggregates were hardly crushed into fibers, so the absolute amount of carbon nanotubes dispersed at the grain boundaries of yttrium oxide was The required conductivity (10 ⁴ Ω · cm or less) was not developed.
In addition, the sintered body of Comparative Example 1 that does not include carbon nanotubes as a conductive material did not exhibit conductivity.

Further, when the solid content in the carbon nanotube slurry was changed, the conductivity of the sintered body was as follows.
The sintered body of Example 1 using a carbon nanotube slurry having a solid content of 0.5% by mass and the sintered body of Example 5 using a carbon nanotube slurry having a solid content of 1% by mass are corrosion resistant. Since there is little change in conductivity before and after the test, if the solid content of the carbon nanotube slurry is 1% by mass or less, the carbon nanotube slurry is exposed to the halogen-based plasma by using the above-described manufacturing process of the carbon nanotube slurry. It was also found that a sintered body that does not lose its conductivity can be obtained.

Moreover, when the content rate of the carbon nanotube in a sintered compact was changed, the heat conductivity of the sintered compact became as follows.
In Examples 1 to 4 and Comparative Examples 1 and 2, if the carbon nanotube slurry manufacturing process is the same, the phonon scattering at the grain boundary of yttrium oxide increases as the content of carbon nanotubes increases. It was found that the thermal conductivity of the body showed a downward trend.
Further, in Example 3 and Comparative Examples 4 and 5, it was found that if the carbon nanotube content was 3% by volume, the thermal conductivity of the sintered body was not greatly different regardless of the manufacturing process of the carbon nanotube slurry. It was.

Regarding the corrosion resistance of the sintered body, in Examples 1 to 8 in which the aggregate diameter of the carbon nanotubes is 10 μm or less, the surface roughness of the halogen plasma is not visually observed, and the center line average roughness after the test is observed. The thickness (Ra value) also remained in the range of several hundreds of nanometers, and the wear depth was a good value of 2.1 to 2.2 μm / hr.
On the other hand, in Comparative Examples 3 to 6 in which the aggregate diameter of the carbon nanotubes exceeds 10 μm, many disappearance marks of carbon nanotubes of 10 μm to 1500 μm are visually observed on the halogen-based plasma irradiation surface, and the centerline average roughness after the test is observed. (Ra value) was reduced to several μm, and the depth of consumption was also reduced to 2.5 to 3.0 μm / hr.

  Further, the sintered body of Comparative Example 3 having a carbon nanotube content of 8% by volume or less was broken during the corrosion resistance test. This is considered to be due to the thermal expansion due to the temperature difference between the halogenated plasma irradiated surface and the non-irradiated surface due to a decrease in thermal conductivity due to the addition of a large amount of carbon nanotubes, causing the sintered body to warp and break.

  The sintered body of the present invention contains an yttrium-based oxide and fibrous carbon, and is formed by three-dimensionally dispersing the fibrous carbon at the grain boundary of the yttrium-based oxide, and the aggregate diameter of the fibrous carbon. Since it has an excellent feature that it has both high corrosion resistance and corrosion resistance to halogen-based corrosive gases and their plasma by having a configuration of 10 μm or less, as a structural member in a semiconductor manufacturing apparatus, In addition, the present invention can be applied to various members such as etching electrodes and dielectric materials for electrostatic chucks that are simultaneously required to have corrosion resistance and conductivity other than the semiconductor manufacturing apparatus, and its usefulness is very large.

Claims (5)

A sintered body comprising yttrium oxide or an yttrium-aluminum composite oxide and fibrous carbon,
The fibrous carbon is three-dimensionally dispersed at grain boundaries of the yttrium oxide or the yttrium-aluminum composite oxide, and the aggregate diameter of the fibrous carbon is 10 μm or less.
The fibrous carbon is one or more selected from the group of single-walled carbon nanotubes, double-walled carbon nanotubes, and multi-walled carbon nanotubes,
The content of the fibrous carbon is 0.01 vol% or more and 5 vol% or less with respect to 100 vol% of the yttrium oxide or the yttrium-aluminum composite oxide,
The center line surface roughness (Ra) is 24.5 nm or less, the volume resistivity is 1 × 10 ⁴ Ω · cm, and the plasma is mixed for 8 hours in a mixed gas of halogenated gas, oxygen gas and argon gas. center line surface roughness of the corrosion resistance after the test exposure is not more than 597.2Nm, volume resistivity Ri der 1 × 10 ⁴ Ω · cm or less,
A sintered body having a relative density of 95% or more . The sintered body according to claim 1, wherein the diameter of the fibrous carbon is larger than 50 nm . The sintered body according to claim 1 or 2, wherein the relative density is 97% or more . A method for producing the sintered body according to any one of claims 1 to 3,
A slurry preparation step of individually preparing an yttrium oxide slurry containing yttrium oxide or an yttrium-aluminum composite oxide and a fibrous carbon slurry containing fibrous carbon, and after the slurry preparation step, the yttrium oxide A mixed slurry preparing step of preparing a mixed slurry by mixing the slurry and the fibrous carbon slurry, a granule preparing step of preparing granules from the mixed slurry by spray drying and granulation, and sintering the granules a sintered body producing step for producing a sintered body, was closed,
In the sintered body manufacturing step, the granule is sintered at 1600 ° C. or higher and 1850 ° C. or lower in an inert atmosphere .   In the slurry preparation step, the solid content of the fibrous carbon slurry is 0.1% by mass or more and 1% by mass or less, and the fibrous carbon slurry is subjected to a pulverization treatment of the fibrous carbon, and then the fibers The method for producing a sintered body according to claim 4, wherein after the dispersion treatment of the carbon-like carbon in the solvent is performed, the residual aggregates of the fibrous carbon slurry are removed.