JP7776306B2 - Sintered bodies and semiconductor manufacturing equipment components - Google Patents

Description

The present invention relates to a sintered body and a component for semiconductor manufacturing equipment.

Plasma using fluorine-based corrosive gases is used in various processes in semiconductor manufacturing, particularly in dry etching, plasma etching, and cleaning processes.

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

As such a bulk material, a sintered body containing yttrium oxyfluoride has been proposed (see Patent Document 1).

Patent No. 5911036

However, although Patent Document 1 describes the corrosion resistance of the YOF sintered body as an yttrium oxyfluoride against plasma, it does not consider the corrosion resistance of the Y ₅ O ₄ F ₇ sintered body against plasma, and there is a need to further improve the corrosion resistance.

In view of the above problems, the present invention aims to improve the plasma resistance of a sintered body of yttrium oxyfluoride (Y ₅ O ₄ F ₇ ).

The sintered body of the present invention for solving the above problems is a sintered body made of yttrium oxyfluoride (Y ₅ O ₄ F ₇ ), characterized in that the average particle size of the yttrium oxyfluoride (Y ₅ O ₄ F ₇ ) crystals in the sintered body is 10 μm or more.
It is believed that corrosion by plasma begins at triple junctions formed by yttrium oxyfluoride (Y ₅ O ₄ F ₇ ) crystals, and when the average particle size of the crystals is large, the density of triple junctions per unit area decreases, making it difficult for corrosion by plasma to progress.
Therefore, by adjusting the average particle size of the crystals of yttrium oxyfluoride (Y ₅ O ₄ F ₇ ) to 10 μm or more, the corrosion resistance to plasma can be improved.
In the present invention, it is desirable to adjust the average particle size of the yttrium oxyfluoride (Y ₅ O ₄ F ₇ ) crystals to 70 μm or more.
Furthermore, it is desirable to adjust the average particle size of the yttrium oxyfluoride (Y ₅ O ₄ F ₇ ) crystals to 100 μm or less, because if the average particle size is too large, the fracture toughness value of the sintered body decreases.

It is desirable that no peaks due to yttrium fluoride (YF ₃ ) crystals are observed in the powder X-ray diffraction chart of the sintered body of the present invention.
This is because by growing yttrium oxyfluoride (Y ₅ O ₄ F ₇ ) crystals preferentially over yttrium fluoride (YF ₃ ) crystals, the average particle size of the yttrium oxyfluoride (Y ₅ O ₄ F ₇ ) crystals can be increased.

Furthermore, in the sintered body of the present invention, the amount of yttrium fluoride ( _YF3 ) crystal particles present in the sintered body made of _yttrium oxyfluoride ( _Y5O4F7 ) is reduced to a level that cannot be confirmed by powder X-ray diffraction, thereby eliminating _the opportunity for selective etching by plasma of the yttrium fluoride ( _YF3 ) crystal particles and the particle boundaries between the yttrium fluoride ( _YF3 ) crystal particles and _yttrium oxyfluoride ( _{Y5O4F7 )} , _and preventing the generation of voids in the sintered body, thereby improving the corrosion resistance of the sintered body made of _yttrium oxyfluoride ( _Y5O4F7 ).

In the sintered body of the present invention, the powder X-ray diffraction chart of the sintered body is preferably measured using a powder X-ray diffractometer with CuKα X-rays, an X-ray tube voltage of 40 kV, a current of 20 mA, a scanning range of 2θ = 10 to 70°, and a scanning speed of 10°/min. This is because these are the most standard measurement conditions for powder X-ray diffraction charts.

In the sintered body of the present invention, it is desirable that only peaks based on yttrium oxyfluoride ( _Y5O4F7 ) crystals are confirmed in _the powder X-ray diffraction chart of the sintered body. _This is because impurity crystal particles other than yttrium oxyfluoride ( _Y5O4F7 ), not limited to yttrium fluoride ( _{YF3 )} , form particle boundaries with _yttrium oxyfluoride ( _Y5O4F7 ) _{, and} corrosion by plasma easily progresses from these particle boundaries, forming voids.

The semiconductor manufacturing equipment member of the present invention comprises the above-mentioned sintered body of yttrium oxyfluoride (Y ₅ O ₄ F ₇ ).
The sintered body of yttrium oxyfluoride (Y ₅ O ₄ F ₇ ) has high corrosion resistance against plasma, and therefore can provide a semiconductor manufacturing equipment member having excellent corrosion resistance and impact resistance.

FIG. 1 is an electron microscope photograph of the surface of the sintered body of yttrium oxyfluoride (Y ₅ O ₄ F ₇ ) according to Example 1. FIG. 2 is an electron microscope photograph of the surface of the sintered body of yttrium oxyfluoride (Y ₅ O ₄ F ₇ ) according to Test Example 1. FIG. 3 is a powder X-ray diffraction chart of the sintered body according to Test Example 1. FIG. 4 is a powder X-ray diffraction chart of the sintered body according to Example 1.

(Sintered body of yttrium oxyfluoride (Y ₅ O ₄ F ₇ ))
The sintered body of the present invention is a sintered body made of yttrium oxyfluoride (Y ₅ O ₄ F ₇ ), and is characterized in that the average particle size of the yttrium oxyfluoride (Y ₅ O ₄ F ₇ ) crystals in the sintered body is 10 μm or more.
It is believed that corrosion by plasma begins at triple junctions formed by yttrium oxyfluoride (Y ₅ O ₄ F ₇ ) crystals, and when the average particle size of the crystals is large, the density of triple junctions per unit area decreases, making it difficult for corrosion by plasma to progress.
Therefore, by adjusting the average particle size of the crystals of yttrium oxyfluoride (Y ₅ O ₄ F ₇ ) to 10 μm or more, the corrosion resistance to plasma can be improved.
It is also desirable to adjust the average particle size of the yttrium oxyfluoride (Y ₅ O ₄ F ₇ ) crystals to 70 μm or more.
Furthermore, it is desirable to adjust the average particle size of the yttrium oxyfluoride (Y ₅ O ₄ F ₇ ) crystals to 100 μm or less, because if the average particle size is too large, the fracture toughness value of the yttrium oxyfluoride (Y ₅ O ₄ F ₇ ) sintered body will decrease.

Furthermore, in the sintered body of the present invention, it is desirable to reduce the amount of yttrium fluoride (YF ₃ ) crystal particles present in the sintered body made of yttrium oxyfluoride (Y ₅ O ₄ F ₇ ) to a level that cannot be confirmed by powder X-ray diffraction. This is because by growing yttrium oxyfluoride (Y ₅ O ₄ F ₇ ) crystals preferentially over yttrium fluoride (YF ₃ ) crystals, the average particle size of the yttrium oxyfluoride (Y ₅ O ₄ F ₇ ) crystals can be increased.
_Furthermore , when yttrium fluoride ( _YF3 ) crystal particles are present in a sintered body made of yttrium oxyfluoride ( _Y5O4F7 ) to an extent that they can be confirmed by powder X-ray diffraction, the plasma will preferentially etch the _yttrium fluoride ( _YF3 ) crystal particles and _the particle boundaries between the _yttrium fluoride ( _YF3 ) crystal particles and yttrium oxyfluoride ( _Y5O4F7 ), causing voids in the sintered body that may further accelerate the etching; however, the occurrence of such voids can be suppressed by reducing the amount of yttrium fluoride ( _YF3 ) crystal particles to an extent that they cannot be confirmed by powder X-ray diffraction.

In the sintered body of the present invention, the powder X-ray diffraction chart of the sintered body is preferably measured under the conditions of a powder X-ray diffractometer using CuKα X-rays, an X-ray tube voltage of 40 kV, a current of 20 mA, a scanning range of 2θ = 10 to 70°, and a scanning speed of 10°/min, because these are the most standard measurement conditions for powder X-ray diffraction charts.
The phrase "no peaks based on yttrium fluoride (YF ₃ ) crystals are observed" means that no peaks are observed at the peak appearance positions (2θ) specified by JCPDS card number 32-1431, which is the diffraction profile of yttrium fluoride (YF ₃ ), or even if a peak is observed, the S/N ratio is less than 2, and the peak can be treated as not being present.
Furthermore, the powder X-ray diffraction apparatus used may be the most standard one, SmartLab manufactured by Rigaku Corporation.

In the present invention, it is desirable that only peaks based on yttrium oxyfluoride ( _Y5O4F7 ) crystals are confirmed in the powder X-ray diffraction chart of the sintered body. _{This is} because impurity crystal particles other than yttrium oxyfluoride ( _Y5O4F7 ), not limited to _yttrium fluoride ( _YF3 ), form particle boundaries with _{yttrium oxyfluoride} ( _Y5O4F7 ), _and corrosion from these particle boundaries is likely to progress by _CF4 plasma or _O2 plasma, forming voids.
"Only peaks based on yttrium oxyfluoride (Y ₅ O ₄ F ₇ ) crystals are observed" means that peaks are observed at the peak appearance positions (2θ) specified by JCPDS card number 01-080-1124, which is the diffraction profile of yttrium oxyfluoride (Y ₅ O ₄ F ₇ ), and no peaks are observed at other positions (2θ), or even if peaks are observed, the S/N ratio is less than 2, and therefore it can be treated as if no peaks exist.

(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.
In the present invention, a sintered body _made of _Y5O4F7 can be obtained by combining _Y2O3 and _YF3 as raw materials _and sintering _them .

Furthermore, when Y ₂ O ₃ and YF ₃ are combined, a molar ratio of Y ₂ O ₃ :YF ₃ = 100:175 to 200 is preferred. In a sintered body obtained by sintering this raw material composition, YF ₃ crystal particles are not generated in the Y ₅ O ₄ F ₇ matrix, or even if they are generated, they can be suppressed to an extent that no peaks due to the YF ₃ crystal particles are observed on a powder X-ray diffraction chart, and the average particle size of the Y ₅ O ₄ F ₇ crystal particles can be adjusted to 10 μm or more.

Furthermore, by setting the sintering temperature to a temperature higher than 950° C., the average particle size of the Y ₅ O ₄ F ₇ crystal particles can be adjusted to 10 μm or more. The sintering temperature is preferably 1000° C. or higher. The sintering temperature is preferably 1200° C. or lower.

In addition to the above-mentioned fluorides such as Y ₂ O ₃ , Y ₅ O ₄ F ₇ and YF ₃ , additives such as organic binders, lubricants, dispersion media and molding aids may be added to the raw material composition as appropriate.
The organic binder is not particularly limited, and examples thereof include polyacrylonitrile (PAN), acrylic resin, phenol resin, epoxy resin, imide resin, and furan resin.
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, and alcohols such as methanol.
The molding aid is not particularly limited, and examples thereof include ethylene glycol, dextrin, fatty acids, fatty acid soaps, polyalcohols, and the like.

The particle size (average particle diameter) of the powder obtained by granulating the raw material composition is preferably, for example, 10 to 200 μm.

The process for producing a sintered body of yttrium oxyfluoride will be described.
The powder of the raw material composition described above is pre-molded into a predetermined shape to produce a pre-molded body. The pre-molding method is not particularly limited, but methods such as embossing and CIP molding can be used.

The resulting molded body is degreased and fired to bond the particles together and sinter, thereby obtaining the sintered body of yttrium oxyfluoride of the present invention.
The firing temperature and atmosphere are not particularly limited, but the atmosphere is preferably an inert atmosphere such as argon, and the firing temperature is preferably above 950°C and 1100°C or less.
The pressure during firing may be normal pressure, or alternatively, hot isostatic pressing (HIP), in which particles are sintered while applying pressure to the molded body, or spark plasma sintering (SPS), in which particles are sintered by mechanical pressure and pulse current heating, may be used.

The semiconductor manufacturing equipment member of the present invention is characterized by comprising the above-mentioned sintered body of yttrium oxyfluoride (Y ₅ O ₄ F ₇ ).
The yttrium oxyfluoride sintered body is made of Y ₅ O ₄ F ₇ , and since the average particle size of the yttrium oxyfluoride (Y ₅ O ₄ F ₇ ) crystals in the sintered body is 10 μm or more, it has high corrosion resistance to plasma.
Therefore, by using the above-mentioned sintered body of yttrium oxyfluoride (Y ₅ O ₄ F ₇ ), it is possible to provide a member for a semiconductor manufacturing device used in a plasma atmosphere.
Examples of plasma include _CF4 plasma and _O2 plasma.

Specific semiconductor manufacturing equipment components of the present invention are not particularly limited, but include, for example, a stage for placing 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. However, the present invention is not limited to the following examples.

Example 1
46.2 parts by weight of _Y2O3 , 53.8 _parts by weight of _YF3 (molar ratio of _Y2O3 : _YF3 = ₁₀₀ :179, i.e., the composition after the firing reaction is molar ratio of _Y5O4F7 : _YF3 = _{100 :} 2), 3.0 parts by weight of acrylic resin as an organic binder, and 40 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 resulting granular particles were adjusted for particle size by removing particles with 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.

Next, the granulated particles were 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 the air at 600° C. for 2 hours, and then fired in an argon atmosphere at 1000° 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.
In addition, an electron microscope photograph was taken at a magnification of 500 times under the conditions for taking electron microscope photographs described later, and the average particle size of the Y ₅ O ₄ F ₇ crystals was measured from this electron microscope photograph according to the method for measuring the average particle size described later, and was found to be 85.1 μm. The electron microscope photograph is shown in Figure 1.

(Test Example 1)
36.3 _parts by weight of _Y2O3 , 63.7 parts by weight of _YF3 (molar ratio of _Y2O3 : _YF3 = ₁₀₀ :270, i.e., the composition after the firing reaction is molar ratio of _Y5O4F7 : _YF3 = _{100 :} 35), 3.0 parts by weight of acrylic resin as an organic binder, and 40 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 resulting granular particles were adjusted for particle size by removing particles with 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.

Next, the granulated particles were 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 the air at 600° C. for 2 hours, and then fired 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.
In addition, an electron microscope photograph was taken at a magnification of 5000 times under the conditions for electron microscope photographs described later, and the average particle size of the Y ₅ O ₄ F ₇ crystals was measured from this electron microscope photograph according to the method for measuring the average particle size described later, and was found to be 3.0 μm. The electron microscope photograph is shown in FIG.

(Comparative Example 1)
A plate of sintered Y ₂ O ₃ (N-100Y manufactured by Nishimura Porcelain Co., Ltd.) was cut into a size of 20 mm×20 mm using a diamond cutter, and further polished to a thickness of 1 mm using a diamond lapping polisher.

The obtained sintered bodies of Example 1, Test Example 1, and Comparative Example 1 were subjected to etching treatment using _CF4 plasma and _O2 plasma under the following conditions, and the etching amount for each was shown in Table 1, assuming that the etching amount for Comparative Example 1 was 1.

(Electron microscope imaging conditions)
Equipment: Hitachi High-Tech S-4800
Acceleration voltage: 3.0 kV
Magnification: 500x and 5000x

(Measuring conditions for average particle size)
The surfaces of the sintered bodies of Example 1 and Test Example 1 were polished to a mirror finish using a diamond lapping polisher. They were observed under an electron microscope (under the above conditions) at 500x or 5000x magnification, and the major axes of any 10 particles observed within the field of view were measured, and the average value over four fields of view was taken as the average particle diameter.
However, when the total diameters of all 10 particles could not be confirmed within one visual field, another visual field was additionally observed to confirm the diameters of the 10 particles.

(Plasma etching conditions)
Plasma etching equipment: EXAM manufactured by Shinko Seiki Co., Ltd.
Etching method: parallel plate type (Capacitive Coupled Plasma-RIE)
It should be noted that RIE is an abbreviation for Reactive Ion Etching.
Substrate temperature: 20℃
Power supply: High frequency 13.56MHz
Power: 350W
Etching time: 6 hours Sample: The sintered bodies of Example 1 and Test Example 1 were polished with a diamond lapping polisher to adjust the thickness to 1 mm, and masking tape (Kapton tape) was attached to the plasma contact surface of each sintered body of Example 1, Test Example 1, and Comparative Example 1. Since the area covered with Kapton tape is not etched, this area becomes the reference surface. The step between the reference surface and the etched area is measured as the etching amount. The step was measured with a laser microscope (KEYENCE VK-X200 series).

As shown in Table 1, the etching amount of the sintered body according to Comparative Example 1 was the largest, followed by the etching amount of the sintered body according to Test Example 1, and the etching amount of the sintered body according to Example 1 was the smallest. In other words, it can be said that the sintered body according to Example 1 is a sintered body having high corrosion resistance against _CF4 plasma and _O2 plasma.

FIG. 1 is an electron microscope photograph of the surface of the sintered body of yttrium oxyfluoride (Y ₅ O ₄ F ₇ ) according to Example 1.
FIG. 2 is an electron microscope photograph of the surface of the sintered body of yttrium oxyfluoride (Y ₅ O ₄ F ₇ ) according to Test Example 1.

Furthermore, powder X-ray diffraction (XRD) was performed on the sintered bodies obtained in Example 1 and Test Example 1 under the following conditions, and powder X-ray diffraction charts were obtained. Figure 3 is a powder X-ray diffraction chart of the sintered body _according to Test Example 1, and Figure 4 is a powder X-ray diffraction chart of the sintered body according to Example 1. The crystal structure of _Y5O4F7 was confirmed in both charts. Furthermore, while peaks of _YF3 were observed in _the powder X-ray diffraction chart shown in Figure 3, neither peaks due to _YF3 nor peaks due to impurity crystals were observed in the powder X-ray diffraction _chart shown in Figure ₄ , and only the crystal structure of _Y5O4F7 was confirmed.
The crystal structure of Y ₅ O ₄ F ₇ in Figures 3 and 4 was identified using JCPDS card number 01-080-1124. The crystal structure of YF ₃ in Figure 3 was identified using JCPDS card number 32-1431.

The measurement conditions for powder X-ray diffraction are as follows.
Equipment: Rigaku Corporation SmartLab
Voltage: 40 kV, Current: 20 mA
X-ray source: CuKα
Scanning range: 2θ = 10 to 70°
Scanning speed: 10°/min

As can be seen from Example 1 and Test Example 1, _{the Y5O4F7} sintered body according to Example 1 has a large average _particle size of 85.1 μm for the _{Y5O4F7 crystals} , a relatively lower density of triple junctions per unit area than _{the Y5O4F7 sintered} body according to Test Example 1 _, and is less susceptible to corrosion originating from triple junctions due to _CF4 plasma and _O2 plasma. Furthermore, impurity crystal particles such as _YF3 crystal particles are absent, or their abundance is suppressed to an extent that they are not detectable by powder X-ray diffraction. This prevents preferential corrosion due to plasma that occurs at the grain boundaries between impurity crystal particles other than _Y5O4F7 , such as _YF3 crystals, _{and Y5O4F7 .} Therefore, the sintered body according to Example 1 can _be said to be suitable for use in _a plasma atmosphere.

Claims (5)

A sintered body made of yttrium oxyfluoride (Y ₅ O ₄ F ₇ ), wherein the average particle size of the yttrium oxyfluoride (Y ₅ O ₄ F ₇ ) crystals in the sintered body is 70 μm or more and 100 μm or less . 2. The sintered body according to claim 1 , wherein a peak based on yttrium fluoride ( _YF3 ) crystals is not observed in a powder X-ray diffraction chart of _the sintered body made of _yttrium oxyfluoride ( _Y5O4F7 ). The powder X-ray diffraction chart of the sintered body according to claim 2 is measured under the conditions of a powder X-ray diffractometer using CuKα rays, an X-ray tube voltage of 40 kV, a current of 20 mA, a scanning range of 2θ = 10 to 70°, and a scanning speed of 10°/min. 4. The sintered body according to claim 1 , wherein only peaks based on yttrium oxyfluoride (Y ₅ O ₄ F ₇ ) crystals are confirmed in a powder X-ray diffraction chart of the sintered body. A member for semiconductor manufacturing equipment, comprising the sintered body according to any one of claims 1 to 4 .