JP2003146755A - Plasma resistant member, method of manufacturing the same, and semiconductor manufacturing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma-resistant member which has an excellent corrosion resistance to plasma or a corrosive gas and a low dust-emitting property and which is suitable as a member constituting a plasma-processing apparatus, and to provide a method of producing the same and a semiconductor manufacturing apparatus. SOLUTION: The plasma-resistant member is made of a yttrium fluoride sintered compact characterized in that the relative density is >=95%, and the three-point bending strength is >=150 MPa. The method of producing the plasma- resistant member comprises a process for preparing a formed body by using, as a base material, an yttrium fluoride powder having particle diameters of <=20 μm and a process for sintering the formed body under pressure and a non-oxidizing atmosphere at 600 to 1,000 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a yttrium fluoride sintered body having excellent plasma resistance, a method for manufacturing the same, and a semiconductor manufacturing apparatus.

[0002]

2. Description of the Related Art In the manufacture of semiconductor devices, halogen-based corrosive gases and plasma of halogen-based corrosive gases are used in dry etching processes and film forming processes.
That is, for the purpose of high integration of the workpiece, the semiconductor manufacturing apparatus has a structure including a plasma generating mechanism. For example, an etching apparatus using an electron cyclotron resonance, which has a microwave generation chamber 1 and a processing chamber 2 as shown in FIG. 1, is known.

Here, the microwave generation chamber 1 and the processing chamber 2 are separated by a microwave introduction window 3, and a coil 4 for forming a magnetic field is arranged on the outer periphery of the processing chamber 2. Further, the processing chamber 2 has a gas supply port 5 for supplying an etching gas and a gas exhaust port 6 for evacuating the inside of the processing chamber 2.
And a monitoring window 7 for monitoring the inside of the processing chamber 2. on the other hand,
In the processing chamber 2, there is installed a support / mounting table 9 that supports a workpiece 8 such as a semiconductor wafer directly or via a susceptor (not shown).

Then, the etching process by this etching apparatus is performed as follows. That is, for example, the semiconductor wafer 8 is mounted on the surface of the support / mounting table 9, the inside of the processing chamber 2 is evacuated, and then a halogen-based corrosive gas is supplied. On the other hand, from the microwave generation chamber 1 to the microwave introduction window 3
Microwave is introduced into the processing chamber 2 via
By energizing the coil 4 to generate a magnetic field, high-density plasma is generated. The plasma energy decomposes the halogen-based corrosive gas into an atomic state to etch the surface of the semiconductor wafer 8.

By the way, in this type of manufacturing apparatus, chlorine-based gas such as boron chloride gas, or fluorine-based gas such as fluorocarbon is used. Therefore, the components such as the inner wall surface of the processing chamber 2, the monitoring window 7, the microwave introduction window 3, the susceptor, the clamp ring, and the support / mounting table 9 are exposed to plasma in a corrosive gas atmosphere, so that they are plasma resistant. Sex is required. Alumina-based sintered bodies, silicon nitride-based sintered bodies, aluminum nitride-based sintered bodies, and the like are used as plasma resistant members that meet such requirements.

[0006]

However, the plasma-resistant members such as the alumina-based sintered body, the silicon nitride-based sintered body, and the aluminum nitride-based sintered body are gradually exposed to plasma in a corrosive gas atmosphere. Corrosion progresses and the crystal grains forming the surface are detached, resulting in so-called particle contamination. For example, in the case of an alumina-based sintered body, aluminum fluoride having a low vapor pressure is generated due to the reaction of the fluorine-based gas with plasma, and the aluminum fluoride is deposited in a region (site) in which the plasma resistance is poor.

Since the above-mentioned deposits are peeled off due to a difference in thermal expansion and cause particle contamination, the inside of the chamber needs to be cleaned in order to avoid the contamination, the maintenance work frequency increases, and the productivity is adversely affected. Exert.
That is, the detached particles are the semiconductor wafer 8
The problem of particle contamination is becoming more serious because it adheres to the support / mounting table 9 or the like and adversely affects etching accuracy and the like, and the performance and reliability of the semiconductor are easily impaired.

In order to avoid the occurrence of contamination by the above-mentioned deposits, the deposits or deposits which become the pollution source are cleaned by periodically exposing them to highly corrosive fluorine-based gas such as fluorine nitride gas and fluorine carbide gas. It is also being removed. Corresponding members are required to have corrosion resistance in this cleaning process. Note that the consumption of the constituent members in the chamber progresses due to, for example, repeated generation of fluoride by the reaction of the fluorine-based gas with plasma and decomposition / scattering of the generated fluoride. Therefore, the rate of progress of decomposition / scattering of reaction products greatly affects the corrosion resistance to plasma.

Even when placed in a CVD apparatus, since it is exposed to plasma of a fluorine-based gas such as fluorine nitride during cleaning, it must have corrosion resistance as in the case of an etching apparatus.

To solve the above corrosion resistance problem, a plasma resistant member made of yttrium aluminate garnet (so-called YAG) sintered body has been proposed (for example, Japanese Patent Laid-Open Nos. 10-45461 and 10-). 236871). That is, the surface exposed to plasma in a halogen-based corrosive gas atmosphere is formed of a sintered body mainly composed of complex oxides such as spinel, cordierite, yttrium aluminate garnet having a porosity of 3% or less, and the surface There is known a plasma resistant member having a center line average roughness (Ra) of 1 μm or less.

However, although yttrium aluminate garnet sintered bodies and the like are excellent in plasma resistance, in the dry process in the manufacture of semiconductor devices, etc., particularly, in the etching process, the fine etching process, When increasing the diameter of a work piece, low-pressure high-density plasma is used, and more excellent plasma resistance is desired as compared with conventional plasma etching conditions.

Further, an aluminum fluoride-based sintered body has been proposed as a plasma-resistant member that substitutes for an alumina-based sintered body, a silicon nitride-based sintered body, etc. (for example, Japanese Patent Laid-Open No. 8-91932). However, although the aluminum fluoride-based sintered body is excellent in plasma resistance itself,
Since it has a melting point of 1040 ° C. and sublimes at a relatively low temperature, it is difficult to prevent sublimation in normal pressure firing or hot press firing, and it can be said that it is difficult to manufacture a dense and high-density sintered body. Further, the problem of the sublimation is that it shows instability in a high temperature region,
Practicality is inferior because the use area or place is restricted.

The present invention has been made in consideration of the above circumstances and has excellent corrosion resistance to plasma and corrosive gas.
An object of the present invention is to provide a plasma-resistant member having low dust resistance, which is suitable as a constituent member of a plasma processing apparatus, a method for manufacturing the same, and a semiconductor manufacturing apparatus capable of meeting severe manufacturing condition settings.

[0014]

The invention according to claim 1 is a yttrium fluoride sintered body having a relative density of 95% or more and a three-point bending strength of 150 MPa or more. It is a plasma resistant member.

According to a second aspect of the present invention, a step of producing a molded body made of yttrium fluoride powder having a particle diameter of 20 μm or less and the molded body in a non-oxidizing atmosphere of 600 to 100
And a step of firing under pressure at a temperature of 0 ° C.

A third aspect of the present invention is a semiconductor manufacturing apparatus having at least a region exposed to a halogen-based corrosive gas or plasma thereof, wherein the region exposed to the halogen-based corrosive gas or plasma thereof has a relative density. 95%
The above is a semiconductor manufacturing apparatus characterized in that it is composed of an yttrium fluoride sintered body having a characteristic that the three-point bending strength is 150 MPa or more.

The inventions of claims 1 to 3 are based on the following findings. That is, the inventors of the present invention have eagerly developed a material having a high corrosion resistance and a low dust resistance suitable for a component member of a semiconductor manufacturing apparatus in which severe manufacturing conditions are set, and a fluorine vapor having a vapor pressure lower than that of aluminum fluoride is further developed. Attention was paid to a single-phase yttrium oxide polycrystal (sintered body). When the yttrium fluoride sintered body is repeatedly examined from the viewpoint of physical properties, the relative density is 95% or more and the three-point bending strength is 150 MPa or more.
The present invention has been found out that it functions as a structural material having high corrosion resistance and low dust resistance, which is suitable for a constituent member of a semiconductor manufacturing apparatus in which severe manufacturing conditions are set.

More specifically, the relative density is 95% or more,
The yttrium fluoride sintered body, which has a characteristic of 96% or more, more preferably 98% or more, and a three-point bending strength of 150 MPa or more, has excellent corrosion resistance even with highly corrosive fluorine-based gas. It was confirmed that it was suitable for precision structural members because of its remarkable reduction in dustiness and high mechanical strength. On the other hand, yttrium fluoride powder having a particle size of 20 μm or less
When pressure-calcined at a temperature of 600 to 1000 ° C., a yttrium fluoride sintered body having a relative density of 95% or more and a three-point bending strength of 150 MPa or more can be easily obtained with high yield and in mass production. It was confirmed.

In the invention of claim 2, since the yttrium fluoride powder forming the material is made into a dense sintered body, its particle size distribution is within the range of 20 μm or less, more preferably within the range of 18 μm or less. To be chosen. The yttrium fluoride powder can be obtained by controlling the production conditions of yttrium fluoride, pulverizing yttrium fluoride, etc., but in any case, it is desirable to avoid mixing of impurities.

In the second aspect of the present invention, the pressurizing and firing means makes the powder particles of the raw material dense and facilitates sintering.
A hot press method (HP) or a hot isostatic press method (HIP) is mentioned. Here, the material to be pressure-fired may be pressure-fired while molding yttrium fluoride powder, or yttrium fluoride powder may be primary-molded and the molded body may be pressure-fired.

In the primary molding, the yttrium fluoride powder is mixed with a lubricant such as water and alcohol, and a binder such as polyvinyl butyral which is volatile at low temperature and does not leave a residue, and is pressed. Prior to firing, heat treatment is performed in an inert atmosphere to degrease. The primary molding includes means such as press molding such as uniaxial pressing and hydrostatic pressing, injection molding, extrusion molding, and casting molding. Molding is preferred.

Further, the atmosphere for the pressure firing is selected to be a reduced pressure or an inert atmosphere in order to suppress or avoid the oxidation of yttrium fluoride. Here, in a reduced pressure atmosphere, yttrium fluoride may be decomposed, so the firing temperature range cannot be set wide, but in an inert atmosphere, there are no such restrictions, and this is more preferable.
Further, the pressure firing temperature is in the range of 600 to 1000 ° C.,
It is preferably set within the range of 700 to 900 ° C. The reason is that if the temperature is lower than 600 ° C., the densification is insufficient, while if the temperature exceeds 1000 ° C., yttrium fluoride is decomposed remarkably, and a desired sintered body cannot be obtained.

In a third aspect of the present invention, the semiconductor manufacturing apparatus is a dry etching apparatus, a film forming apparatus or the like that uses a halogen-based corrosive gas or plasma, and the region exposed to the halogen-based corrosive gas or plasma is, for example, They are the inner wall surface of the processing chamber, the monitoring window, the microwave introduction window, the susceptor, the clamp ring, and the support / mounting table. Therefore,
The portion exposed to plasma under these corrosive gas atmospheres is composed of the yttrium fluoride sintered body.

According to the first aspect of the present invention, yttrium fluoride itself has high corrosion resistance as well as excellent mechanical strength, so that it is easy to perform processing, and precision and plasma resistance are required. Function as.

According to the second aspect of the present invention, a yttrium fluoride sintered body having a relative density of 95% or more and a mechanical strength of 150 MPa or more can be provided in good yield and mass-produced.

According to the third aspect of the present invention, the portion / region exposed to the halogen-based corrosive gas or its plasma is made of the yttrium fluoride sintered body which is excellent in mechanical strength in addition to high corrosion resistance. . In other words, since the parts and regions exposed to plasma etc. are made of yttrium fluoride sintered compact with high corrosion resistance and low dust resistance, maintenance is labor-saving, and durability and long life are planned. Function as a fixed device.

[0027]

Embodiments of the invention will be described below.

Yttrium fluoride having a purity of 99.99% and a grain size of 20 μm or less is prepared as a raw material, and the pressure is 2.94 M.
Pa (300 kg / cm ² ), firing temperature 500-110
At 0 ° C in a reduced pressure atmosphere (6.67 Pa (0.05 Tor)
r)) or hot pressing in an argon gas atmosphere to produce a yttrium fluoride sintered body having a thickness of 5 mm and a length and width of 50 × 50 mm. Table 1 shows the results of test evaluations of the relative density% and the three-point bending strength MPa of the manufactured sintered body.

[0029]

[Table 1]

As can be seen from Table 1, the firing temperature is 600
If the temperature is lower than 0 ° C, sufficient relative density and three-point bending strength cannot be obtained due to insufficient sintering. On the other hand, if the temperature exceeds 1100 ° C, yttrium fluoride is decomposed, and a desired sintered body cannot be obtained. That is, in the case of a reduced pressure atmosphere, the range of about 600 to 900 ° C. is preferable, and in the case of an argon gas atmosphere, it is 7
The range of 00 to 1000 ° C. is preferable. In the pressure firing in a reduced pressure atmosphere, the firing temperature was 1000 ° C. or higher, decomposition occurred, and a desired sintered body could not be obtained.

Next, the surface of the yttrium fluoride sintered body (relative density 99.9%, three-point bending strength 191 MPa) that was pressure-fired at a firing temperature of 800 ° C. in the above-mentioned argon gas atmosphere was mirror-polished to obtain a helicon. It was installed in a wave plasma etcher device, exposed to plasma for 4 hours, and the corrosion resistance (etching rate (μm / h)) of the exposed surface was tested and evaluated. As a result, it was 141 μm / h. The conditions of the plasma exposure test are as follows: frequency 13.56 MHz, high frequency source 500 W, high frequency bias 40 W, CF ₄ gas, 0.5.
It is 3 Pa (4 mTorr).

For comparison, an alumina sintered body and quartz glass were prepared and subjected to a plasma exposure test under the same conditions as above to perform corrosion resistance (etching rate (μm / h)) on the exposed surface.
Test evaluation, the alumina sintered body was 1200 μm
/ H, and the quartz glass was 11000 μm / h.

In the above, the corrosion resistance of the yttrium fluoride sintered body which has been pressure-fired at a firing temperature of 800 ° C. in an argon gas atmosphere has been exemplified, but when the relative density is 95% or more,
Also, in the case of the yttrium fluoride sintered body having a mechanical strength of 150 MPa or more, similarly excellent corrosion resistance was confirmed.

The present invention is not limited to the above embodiments, but various modifications can be made without departing from the gist of the invention.

[0035]

According to the invention of claim 1, while having excellent mechanical strength, it has high corrosion resistance against corrosive gas,
Provided is a low-dust structural member. Further, this structural member, in combination with the above mechanical strength, high corrosion resistance, and low dust resistance, contributes greatly to omission of maintenance operation and improvement of durability of the plasma processing apparatus.

According to the second aspect of the present invention, it is possible to mass-produce the yttrium fluoride sintered body which is suitable for the plasma resistant member and has a high corrosion resistance and a low dust content, in a good yield.

According to the third aspect of the present invention, in a semiconductor manufacturing apparatus using a halogen-based corrosive gas or its plasma, a portion / region exposed to plasma or the like has high corrosion resistance,
It is composed of low dust and plasma resistant material. Therefore, a high-quality semiconductor device can be obtained with high yield, and productivity can be secured by labor saving of maintenance.

[Brief description of drawings]

FIG. 1 is a sectional view showing a schematic configuration of a plasma etching apparatus.

[Explanation of symbols]

1 ... Microwave generator 2 ... Processing room 3 ... Microwave introduction window 4 ... Magnetic field forming coil 5: Gas supply port 6 ... Gas outlet 7 ... Monitoring window 8 ... Workpiece 9: Workpiece support / mounting table

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Claims (3)

[Claims] 1. A yttrium fluoride sintered body having a relative density of 95% or more and a three-point bending strength of 150 MPa.
A plasma resistant member having the above characteristics. 2. A step of producing a molded body made of yttrium fluoride powder having a particle size of 20 μm or less, and a step of press-baking the molded body at a temperature of 600 to 1000 ° C. in a non-oxidizing atmosphere. A method of manufacturing a plasma resistant member, comprising: 3. A semiconductor manufacturing apparatus having at least a region exposed to a halogen-based corrosive gas or plasma thereof, wherein a region exposed to the halogen-based corrosive gas or plasma thereof has a relative density of 95% or more, Also, a semiconductor manufacturing apparatus comprising a yttrium fluoride sintered body having a three-point bending strength of 150 MPa or more.