JP7598792B2 - Yttrium oxyfluoride sintered body and semiconductor manufacturing equipment component using said yttrium oxyfluoride sintered body - Google Patents

Description

The present invention relates to a sintered body of yttrium oxyfluoride and a component for semiconductor manufacturing equipment that uses the sintered body of yttrium oxyfluoride.

Fluorine-based corrosive gases, chlorine-based corrosive gases, and plasmas using these gases are used in various steps in semiconductor manufacturing, particularly in the dry etching, plasma etching, and cleaning steps.

When these corrosive gases and plasmas are used, the components of the semiconductor manufacturing equipment can corrode, and fine particles that detach from the surfaces of the components can adhere to the surface of the semiconductor, easily causing product defects. For this reason, ceramics that are highly resistant to corrosion by halogen-based plasmas must be used as bulk materials for the components of semiconductor manufacturing equipment.

As such a bulk material, Patent Document 1 describes a sintered body having a phase of a compound containing at least a rare earth element and fluorine, and having an L value of 70 or more in the L*a*b chromaticity display.
It is described that such a sintered body has an L* value of 70 or more due to the absence of elimination defects of fluorine or oxygen, and thus has high corrosion resistance to halogen-based plasma.

Furthermore, Patent Document 2 describes that when a ceramic used as a bulk material contains orthorhombic _YF3 , the plasma resistance can be increased by controlling the structure of _YF3 .

International Publication No. 2020/179296 JP 2018-82154 A

However, when the L value of a member used in semiconductor manufacturing equipment becomes high, the member is more likely to reflect light on its surface, and it takes longer for the member to heat up and dissipate heat by radiation.
In view of the above problems, the present invention aims to provide a sintered body of yttrium oxyfluoride that is easy to radiate heat and dissipate heat while maintaining a composition that can ensure corrosion resistance against plasma of halogens, oxygen, etc., and a semiconductor manufacturing equipment part using the same.

The yttrium oxyfluoride sintered body of the present invention for solving the above problems is a yttrium oxyfluoride sintered body mainly composed of Y ₅ O ₄ F ₇ and YF ₃ , containing 0.02 to 0.3 wt % carbon and having an L value of 20 to 55 in the Lab color system.

The yttrium oxyfluoride sintered body of the present invention contains 0.02 to 0.3 weight percent carbon and has an L value of 20 to 55 in the Lab color system. The carbon is unlikely to form a carbide with yttrium oxyfluoride and can exist as simple carbon in the sintered body, so the yttrium oxyfluoride sintered body of the present invention contains 0.02 to 0.3 weight percent carbon, which contributes to lowering the L value of the sintered body.

In addition, since the L value is 20 to 55, light absorption and radiation are easy, and when used as a component for semiconductor manufacturing equipment, it can be heated and cooled quickly, shortening the lead time for semiconductor manufacturing and reducing manufacturing costs.
Furthermore, since the yttrium oxyfluoride sintered body of the present invention is mainly composed of Y ₅ O ₄ F ₇ and YF ₃ , it can have strong resistance to halogen-based plasma.

In the yttrium oxyfluoride sintered body of the present invention, the carbon is preferably amorphous carbon.
Irregular carbon refers to carbon that does not have a crystal structure like graphite particles. When the carbon in the sintered body of the yttrium oxyfluoride of the present invention is irregular carbon, it is less likely to be unevenly distributed and spreads thinly and widely at the grain boundaries of the sintered body of the yttrium oxyfluoride of the present invention, and a small amount of carbon can efficiently reduce the L value.

The yttrium oxyfluoride sintered body of the present invention preferably has a porosity of 4% or less.
When the porosity of the yttrium oxyfluoride sintered body of the present invention is 4% or less, the diffuse reflection of light on the surface of the yttrium oxyfluoride is suppressed, and the color inside the sintered body is easily observed. In addition, when the porosity is 4% or less, oxygen is unlikely to penetrate into the sintered body even when heated in air, and carbon is unlikely to be oxidized, so that the L value in the Lab display system can be maintained at 20 to 55.

In the yttrium oxyfluoride sintered body of the present invention, the content of _YF3 is preferably 5 to 40% by weight.
In the yttrium oxyfluoride sintered body of the present invention, when the content ratio of _YF3 is within the above range, the yttrium oxyfluoride sintered body has high corrosion resistance against both halogen and oxygen plasma, and can prevent deterioration of the yttrium oxyfluoride sintered body.

The semiconductor manufacturing equipment member of the present invention is characterized by using the above-mentioned yttrium oxyfluoride sintered body.
According to the semiconductor manufacturing equipment member of the present invention, since the L value is 20 to 55, it can be heated and cooled quickly within the semiconductor manufacturing equipment, thereby shortening the lead time of semiconductor manufacturing and reducing costs.

According to the yttrium oxyfluoride sintered body of the present invention, since it contains 0.02 to 0.3 wt % of carbon and has an L value of 20 to 55, it is easy to absorb and radiate light by radiant heat transfer, and when used as a semiconductor manufacturing device part, it can be quickly heated and cooled, shortening the lead time of semiconductor manufacturing and reducing manufacturing costs.
In addition, since the yttrium oxyfluoride sintered body of the present invention is mainly composed of Y ₅ O ₄ F ₇ and YF ₃ , it can have strong resistance to halogen and oxygen plasma.

In addition, the semiconductor manufacturing equipment component of the present invention contains 0.02 to 0.3 weight percent carbon and has an L value of 20 to 55, so that the parts that will become semiconductors can be quickly heated and cooled in the semiconductor manufacturing equipment in which the semiconductor manufacturing equipment component is used, shortening the lead time for semiconductor manufacturing and reducing costs.

1 is a chart showing the results of X-ray diffraction analysis of powders obtained by pulverizing the sintered bodies of yttrium oxyfluoride according to Example 1 and Comparative Example. Photographs showing the surface state of yttrium oxyfluoride sintered bodies according to Examples 1 to 3 and a Comparative Example.

The yttrium oxyfluoride sintered body of the present invention is a sintered body of yttrium oxyfluoride mainly composed of Y ₅ O ₄ F ₇ and YF ₃ , and is characterized in that it contains 0.02 to 0.3 wt % of carbon and has an L value of 20 to 55 in the Lab color system.

The Lab color system is a system established by the CIE (International Commission on Illumination) consisting of a series of rules and definitions for quantitatively describing color, and expresses color using a luminance coordinate (L: brightness) and two chrominance coordinates (a: red-green axis, b: blue-yellow axis). The L value (brightness value) is defined as 0 to 100, and the higher the value, the brighter the color. The sintered body of yttrium oxyfluoride of the present invention has an L value (brightness value) of 20 to 55.

The yttrium oxyfluoride sintered body of the present invention is less likely to form carbides with yttrium oxyfluoride due to a reaction with the contained carbon, and carbon can exist as simple substance in the yttrium oxyfluoride sintered body. Even a small amount of carbon, 0.02 to 0.3 weight percent, can contribute to lowering the L value of the yttrium oxyfluoride sintered body of the present invention.

According to the yttrium oxyfluoride sintered body of the present invention, since the L value is 55 or less, light absorption and radiation are easily performed, and when used as a semiconductor manufacturing equipment part, it can be heated and cooled quickly, shortening the lead time of semiconductor manufacturing and reducing manufacturing costs.
Furthermore, since the L value is 20 or more, the amount of carbon added is not too large, carbon is unlikely to be exposed on the surface, oxidation over time is suppressed, and fluctuations in the L value can be prevented.
The L value can be measured by using a color difference meter.

Furthermore, since the yttrium oxyfluoride sintered body of the present invention is mainly composed of Y ₅ O ₄ F ₇ and YF ₃ , it can have strong resistance to halogen and oxygen plasma.
The _{yttrium oxyfluoride} sintered body of the present invention may contain, in addition to _Y5O4F7 , YF3 _, and carbon _, components such as _Y2O3 , _{Y7O6F9 ,} etc., as long as _they do not affect corrosion resistance. The content ratio of components other than _Y5O4F7 , _{YF3 ,} and carbon is preferably ₁₅ % by weight or less, more preferably 5% by weight or less, and even more preferably 1% by weight or less.

In the yttrium oxyfluoride sintered body of the present invention, it is preferable that the carbon is amorphous carbon.

In the obtained yttrium oxyfluoride sintered body, the carbon contained therein is amorphous carbon, which means that it does not have a crystal structure like graphite particles, that is, the hexagonal crystals have a certain size, and it is not a structure in which a peak is detected by X-ray diffraction, but is not detected by X-ray diffraction. Such amorphous carbon can be detected by quantitative analysis of infrared absorption method by combustion method in oxygen gas flow using a carbon/sulfur analyzer after crushing the sintered body to a particle size of 1 mm or less.
In addition, amorphous carbon spreads thinly over grain boundaries and is not easily unevenly distributed, so that it spreads thinly and widely over grain boundaries of the sintered body of yttrium oxyfluoride of the present invention, and the L value can be efficiently reduced with a small amount of carbon.

The yttrium oxyfluoride sintered body of the present invention preferably has a porosity of 4% or less.
In the yttrium oxyfluoride sintered body of the present invention, when the porosity is 4% or less, the diffuse reflection of light on the surface of the yttrium oxyfluoride is suppressed, and the color inside the sintered body is easily observed. In addition, when the porosity is 4% or less, oxygen is unlikely to penetrate into the sintered body even when heated in air, and carbon is unlikely to be oxidized, so that the L value in the Lab display system can be maintained at 20 to 55.
The porosity of the yttrium oxyfluoride sintered body of the present invention can be determined as follows.
The true density of Y ₅ O ₄ F ₇ and the true density of YF ₃ are multiplied by the volume ratio and added together to calculate the true density of the sintered body, and then the porosity can be determined as 1 - (bulk density/true density). The true density of Y ₅ O ₄ F ₇ is 5.14 g/cm ³ , and the true density of YF ₃ is 5.07 g/cm ³ .

The yttrium oxyfluoride sintered body of the present invention preferably has a _YF3 content of 5 to 40% by weight.
In the yttrium oxyfluoride sintered body of the present invention, when the content of _YF3 is within the above range, the yttrium oxyfluoride sintered body has high corrosion resistance against both halogen and oxygen plasma, and can prevent deterioration of the yttrium oxyfluoride sintered body. Furthermore, the content of _YF3 is preferably 10 to 20% by weight.

The content ratio of _YF3 in the yttrium _oxyfluoride sintered body of the present invention can be obtained by quantitative analysis using EPMA. That is, the sintered body containing two phases of _Y5O4F7 and _YF3 is analyzed using EPMA, and the content ratio _{of YF3} can be obtained from the oxygen content analysis. Prior to the analysis, the crystal phase contained in the yttrium _oxyfluoride sintered body is confirmed by X-ray diffraction to confirm that it is two phases of _{Y5O4F7 and YF3} .

(Method for producing sintered body of yttrium oxyfluoride)
The yttrium oxyfluoride sintered body of the present invention can be produced by the following production method.

"raw materials"
After sintering, the raw material components are mixed so that Y ₅ O ₄ F ₇ and YF ₃ are the main components. As the raw materials, Y ₅ O ₄ F ₇ and YF ₃ may be combined, YOF and YF ₃ may be combined, or Y ₅ O ₄ F ₇ , YOF and YF ₃ may be combined. By combining the above raw materials, a sintered body of yttrium oxyfluoride containing Y ₅ O ₄ F ₇ and YF ₃ as the main components can be obtained.

When _Y5O4F7 and _YF3 are combined, the molar ratio of _Y5O4F7 to _YF3 is preferably _{Y5O4F7 : YF3} =10:2 to 30. When _YOF and _YF3 are combined, the _molar ratio of _YOF to _YF3 is preferably YOF: _YF3 = ₁₀ : ₅ to 40.

It is also preferable to use an organic binder to granulate the raw material particles and to improve moldability. The organic binder can be carbonized and sealed in the sintered body to make the sintered body black.
The organic binder to be used is not particularly limited as long as it is carbonized by applying heat, but examples thereof include polyacrylonitrile (PAN), acrylic resin, phenolic resin, epoxy resin, imide resin, furan resin, etc., and two or more of these may be used in combination. Since these binders are resins, they can be dissolved in a solvent and thinly coated on the surface of the raw material particles. In addition, by carbonizing the thinly coated binder, a thin carbon layer of amorphous carbon can be formed at the interface of the particles, and the color of the sintered body of yttrium oxyfluoride can be efficiently blackened.

The raw materials may contain, as appropriate, additives such as a dispersion medium, a lubricant, a molding aid, etc., in addition to the above-mentioned fluorides such as Y ₅ O ₄ F ₇ , YOF, and YF _3, and the above-mentioned organic binder.
The lubricant is not particularly limited, and examples thereof include polyoxyalkylene compounds such as polyoxyethylene alkyl ether and polyoxypropylene alkyl ether.
The dispersion medium is not particularly limited, and examples thereof include water, organic solvents such as benzene, alcohols such as methanol, etc. The molding aid is not particularly limited, and examples thereof include ethylene glycol, dextrin, fatty acids, fatty acid soaps, polyalcohols, etc.

Raw material preparation process
In order to prevent segregation of the raw materials used and improve their ease of handling _, the raw materials may be granulated in the raw _material preparation process. In addition to fluorides such as _Y5O4F7 , YOF, and _YF3 , and organic binders for ensuring the moldability of the raw material particles and granulation, a dispersion medium such as water or an organic solvent, and a lubricant are mixed to disperse the raw material particles in the dispersion medium, and then the mixture is granulated to form the granules. The granulation method is not particularly limited, and for example, spray drying, rolling granulation, etc. can be used.
In this case, it is preferable to use 1 to 10 parts by weight of the organic binder and 5 to 50 parts by weight of the dispersion medium relative to 100 parts by weight of the raw materials.

The size of the granulated particles is preferably, for example, 10 to 200 μm.
Although raw material preparation by granulation is not essential, it is preferable to granulate the raw material during the raw material preparation process, since dissolving the binder in a dispersion medium liquid allows the raw material particles to be thinly coated with an organic binder.

<Molding process>
In the molding step, it is preferable to press mold the composition containing the raw material prepared. The method of press molding is not particularly limited, but embossing molding, CIP molding, etc. can be applied. The molding pressure at this time is preferably, for example, 50 to 500 MPa. In the case of embossing molding, the shape of the mold is transferred, and a molded body with high shape accuracy can be obtained, but it is likely to become anisotropic. In CIP molding, it is easy to obtain an isotropic material, but since it is filled into a rubber bag and molded, the shape accuracy is not very good. Since it becomes difficult to process after sintering, in the case of CIP molding, the outer shape may be processed after molding as necessary. In addition, it may be molded by applying high pressure by CIP molding after embossing molding at low pressure to adjust the shape. It is possible to obtain a molded body with high dimensional accuracy and high density.

<Degreasing process>
A degreasing process is carried out to remove the organic binder from the obtained molded body. If a large amount of binder remains after sintering, the bonding strength of ceramic particles such as _Y5O4F7 and _YF3 will deteriorate, so the unnecessary part of the organic binder is removed to make the color of _the sintered body black while maintaining the _bonding strength.
The degreasing conditions are, for example, 500 to 700° C. in air for 0.5 to 5 hours.

The ease of oxygen penetration during degreasing varies depending on the molding density of the molded body. When the molding density is high, there are fewer pores after molding, which makes it difficult for oxygen that oxidizes the binder to penetrate inside, and the binder is more likely to remain. On the other hand, when the molding density is low, there are more pores after molding, which makes it easier for oxygen to penetrate inside during degreasing. For this reason, the amount of remaining carbon can be adjusted by adjusting the molding density. There are no particular limitations on the molding density, but a desired molding density can be obtained by appropriately adjusting the molding pressure, particle size distribution of the raw materials, amount of binder, viscosity of the binder, etc.

<Firing (sintering) process>
The obtained degreased body is heated and fired to bond the particles together, eliminate internal pores, and sinter. The sintering temperature and atmosphere are not particularly limited, but the atmosphere is preferably an inert atmosphere such as argon, and the sintering temperature is preferably 800 to 1100° C.
The pressure during sintering may be normal pressure, or may be hot isostatic pressing (HIP), in which a compact is sintered while being pressurized, or discharge plasma sintering (SPS), in which a compact is sintered by mechanical pressure and pulse current heating, etc. When pressurizing by HIP, SPS, etc., the pressure is preferably 10 to 200 MPa, for example.

The semiconductor manufacturing equipment member of the present invention is characterized by using the above-mentioned yttrium oxyfluoride sintered body.
According to the semiconductor manufacturing equipment member of the present invention, the above-mentioned yttrium oxyfluoride sintered body is used, and since the L value is 20 to 55, it can be heated and cooled quickly within the semiconductor manufacturing equipment, thereby shortening the lead time of semiconductor manufacturing and reducing costs.

In addition, according to the semiconductor manufacturing equipment member of the present invention, a sintered body of _{yttrium oxyfluoride} is used as the semiconductor manufacturing equipment member, and since the main components are _Y5O4F7 and _YF3 , it is not easily corroded by halogen or oxygen plasma, has excellent resistance, and can be used for a long period of time.

Specific examples of the semiconductor manufacturing equipment components of the present invention include, but are not limited to, a stage for mounting semiconductor components such as wafers, an electrostatic chuck, a gas supply unit, a coolant supply unit, a transfer arm, a chamber inner wall material, an upper electrode, a shower plate, a focus ring, an edge plate, etc.

The following are examples that more specifically disclose the present invention. Note that the present invention is not limited to the following examples.

Example 1
70 parts by weight _{of Y5O4F7} , 30 parts by weight _{of YF3} , 2.6 parts by weight of acrylic resin as _an organic binder, and 16 parts by weight of an alcohol-based solvent as a dispersion medium were mixed, and then dried and granulated at 70°C using a spray dryer to prepare a granular raw material composition. The obtained granular granulated particles were cut off to a particle size of 80 μm or more. The alcohol-based solvent was 86% by weight of ethanol and 14% by weight of isopropyl alcohol, and the granulated particles were not completely dried by spray drying, and were moist. It is believed that isopropyl alcohol, which has a boiling point higher than the temperature of spray drying, remains.

The granulated particles were then filled into a φ25 mm mold and uniaxially molded at 6 MPa to adjust the overall shape, after which they were packed into a rubber bag and CIP molded at 200 MPa.

The above molded body was subjected to a degreasing treatment in air at 600° C. for 2 hours, and then sintered in an argon atmosphere at 950° C. for 2 hours to obtain a sintered body of yttrium oxyfluoride.
The obtained sintered body of yttrium oxyfluoride was in the form of a plate having a diameter of 19 mm and a thickness of 3 mm.

Example 2
A sintered body of yttrium oxyfluoride was produced in the same manner as in Example 1, except that the degreasing temperature was 550°C and the firing temperature was 950°C.

Example 3
A sintered body of yttrium oxyfluoride was produced in the same manner as in Example 1, except that the firing temperature was 1000°C.

Comparative Example
The obtained granular raw material composition was dried to complete drying, and a sintered body of yttrium oxyfluoride was produced in the same manner as in Example 1, except that the degreasing temperature was 500°C and the firing temperature was 1000°C.

[Measurement of L value]
The L values of the obtained samples according to Examples 1 to 3 and Comparative Example were measured using a Konica Minolta color difference meter (CR-200). The results are shown in Table 1.
2 is a photograph showing the surface state of the yttrium oxyfluoride sintered bodies of Examples 1 to 3 and the Comparative Example. It can be seen that the surfaces of the yttrium oxyfluoride sintered bodies of Examples 1 to 3 are black, whereas the yttrium oxyfluoride sintered body of the Comparative Example is grayish white despite being degreased at a lower temperature than Examples 1 to 3.

[Measurement of Carbon Content]
The obtained samples of the yttrium oxyfluoride sintered bodies according to Examples 1 to 3 and Comparative Example were divided into parts, and the carbon content of the yttrium oxyfluoride sintered bodies was measured by quantitative analysis using an oxygen flow combustion-infrared absorption method. The equipment used was a Horiba, Ltd. carbon and sulfur in materials analyzer EMIA-Step, and the combustion in the oxygen flow was performed at 1350°C for 2 minutes. The results are shown in Table 1.

[Measurement of _YF3 content]
EPMA was carried out to measure the oxygen content of the samples of the sintered bodies of yttrium oxyfluoride according to Examples 1 to 3 and the Comparative Example.
From the above content analysis, the content of _YF3 was calculated based on a calibration curve prepared in advance. The results are shown in Table 1.

1 is a chart showing the results of X-ray diffraction of the sintered bodies of yttrium oxyfluoride according to Example 1 and Comparative Example, and it was confirmed that the only peaks detected were YF ₃ and Y ₅ O ₄ F ₇ , and that the main components of both were YF ₃ and Y ₅ O ₄ F _7. Since no carbon peak was confirmed, it is believed that the carbon contained is amorphous carbon.

[Porosity measurement]
The porosity of the sintered bodies of yttrium oxyfluoride according to Examples 1 to 3 and Comparative Example was determined based on the content ratio of YF ₃ and Y ₅ O ₄ F ₇ , the true density and the bulk density by the above-mentioned method. The results are shown in Table 1.

[Flexural strength]
A three-point bending test was carried out on the sintered bodies of Examples 1 and 2. The results are shown in Table 1.

As is clear from Table 1 above, it was found that the yttrium oxyfluoride sintered bodies according to Examples 1 to 3 have a carbon content of 0.02 to 3 wt%, an L value of 20 to 55, a black color, a low porosity of 0.8 to 1.7%, and a _YF3 content of 14 to 15 wt%. Since the yttrium oxyfluoride sintered body has a sufficiently low porosity, it is presumed that it has sufficient bending strength and excellent mechanical properties to be used as a structural material.

On the other hand, the yttrium oxyfluoride sintered body according to Comparative Example 1 had a carbon content of less than 0.01% by weight, an L value of 55.7, a grayish white color, a porosity of 3.2%, and a _YF3 content of 25% by weight. The porosity was higher than those of the sintered bodies of Examples 1 to 3.

Claims (5)

A sintered body of _yttrium oxyfluoride mainly composed of _Y5O4F7 and _{YF3 ,}
Contains 0.02 to 0.3 weight percent carbon;
A sintered body of yttrium oxyfluoride, characterized in that the L value in the Lab color system is 20 to 55. The yttrium oxyfluoride sintered body according to claim 1, characterized in that the carbon is amorphous carbon. The yttrium oxyfluoride sintered body according to claim 1 or 2, characterized in that the porosity is 4% or less. The yttrium oxyfluoride sintered body according to any one of claims 1 to 3, characterized in that the content of the _YF3 is 5 to 40% by weight. A semiconductor manufacturing equipment component characterized by using a sintered body of yttrium oxyfluoride according to any one of claims 1 to 4.

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