US20090101070A1

US20090101070A1 - Member for a Plasma Processing Apparatus and Method of Manufacturing the Same

Info

Publication number: US20090101070A1
Application number: US12/224,784
Authority: US
Inventors: Tadahiro Ohmi; Masafumi Kitano; Yoshihumi Tsutai; Keisuke Satou; Mabito Iguchi
Original assignee: Tohoku University NUC; Nihon Ceratec Co Ltd
Current assignee: Tohoku University NUC; NTK Ceratec Co Ltd
Priority date: 2006-03-27
Filing date: 2007-02-20
Publication date: 2009-04-23
Also published as: KR101030937B1; KR20080111086A; JP2007258634A; WO2007111058A1; JP5014656B2; CN101432461A

Abstract

A member for a plasma processing apparatus, which is excellent in film-formability, durability, and reliability, is provided.

On a substrate, a ceramic film having a purity not less than 98% is provided. In the ceramic film, grains constituting the film have a grain diameter not greater than 50 nm and the amount of moisture released from the film is not more than 10¹⁹molecules/cm².

Description

TECHNICAL FIELD

This invention relates to a member for a plasma processing apparatus for manufacturing an electronic component, such as a semiconductor device and a liquid crystal panel, and to a method of manufacturing the same.

BACKGROUND ART

As a process of manufacturing a semiconductor device, a liquid crystal panel, and the like, there are a film forming process and a dry etching process which are carried out by plasma processing on a Si wafer and a glass substrate. Upon the plasma processing, various corrosive gases are used. A conventional chamber inner wall is made of metal and exposed in an uncovered state inside a chamber. However, with recent improvement of an integration degree of the semiconductor device and the like, a permissible level of metal contamination is becoming extremely low. Further, in order to achieve a higher quality of the plasma processing, plasma having a higher density is used year after year.
Therefore, as a member exposed inside the chamber (plasma processing chamber) in a plasma processing apparatus, a ceramic sintered body is becoming used which exhibits high corrosion resistance against the plasma and the corrosive gases. For example, an electronic component manufacturing apparatus disclosed in Patent Document 1 uses a member using the ceramic sintered body.
It has been comparatively easy to manufacture the plasma processing chamber having a size corresponding to 5-inch and 6-inch Si wafers by a member made of the ceramic sintered body. However, it is extremely difficult to manufacture a recent large-scaled plasma processing chamber corresponding to 8-inch and 12-inch Si wafers and a large-sized liquid crystal substrate by the member made of the ceramic sintered body. This is attributed to a problem of a low yield and a high manufacturing cost.
Under the circumstances, for the plasma processing chamber, use is made of a member comprising a metallic substrate low in cost, excellent in workability, and easily increased in size and a ceramic film formed on the substrate by using a spraying method. Such a member has corrosion resistance similar to that of the ceramic sintered body. For example, an electronic component manufacturing apparatus disclosed in Patent Document 2 has a member obtained by forming a ceramic film (sprayed film) by using the spraying method.
In the spraying method, ceramic powder having a high melting point is melted by electric energy or gas energy and sprayed onto a substrate. Therefore, insufficient melting of a ceramic material is easily caused to occur. In case where melting of the ceramic material is insufficient, open pores or consecutive pores are generated on the sprayed film. Also, countless microcracks are generated on the sprayed film due to quenching from a molten state. In a plasma processing chamber manufactured by using the member having the sprayed film, when a corrosive gas and plasma are brought into contact with the sprayed film, the corrosive gas penetrates the consecutive pores or the microcracks of the sprayed film to cause corrosion of the substrate to occur. Eventually, there arises a problem of peeling of the sprayed film or the like. Further, in the spraying method, the sprayed film is formed to have a thickness of 100 μm or more in order to cover those defects due to the countless pores or microcracks. Between such a thick sprayed film and the metallic substrate, mismatch in linear expansion coefficient occurs. After repetition of temperature rising and cooling in plasma processing, the sprayed film is peeled off due to the mismatch in linear expansion coefficient.
In view of the above, it is proposed to form the ceramic film by PVD or CVD instead of the sprayed film. However, in both of the methods, it is required to provide a vacuum environment at the time of film formation, to controllably position a material nozzle at a fixed distance from a surface on which the film is to be formed, and to heat the substrate to a high temperature. Therefore, these techniques are not effective as a method of manufacturing a member for a large-sized and complicated-shaped plasma processing apparatus.
Alternatively, it is proposed to form the ceramic film by preparing a solution (sol) in which a metallic compound or a fine powder raw material is dispersed, applying the solution to a surface of the substrate by a simple device, such as a spray nozzle, and carrying out heat treatment. Such a method is called a sol-gel method. Although the method is a prior and existing technique, it is possible to form a ceramic film excellent in film formability, durability, and reliability.
Patent Document 1: JP-B-3103646
Patent Document 2: JP-A-2001-164354
Non-Patent Document 1: “Sintering of Ceramics” written by Yusuke Moriyoshi et al, published by Uchida Rokakuho on Dec. 15, 1995

DISCLOSURE OF THE INVENTION

Problem to be Solved by the Invention

However, use of the sol-gel method as a method of forming the ceramic film of the member for a plasma processing apparatus has the following problems.
The ceramic film of the member for a plasma processing apparatus is required to have a purity not less than 98%. When the sol-gel method is executed by using a high purity material, heat treatment at a high temperature (for example, 700° C. or higher) is required.
However, as the substrate of the member for a plasma processing apparatus, a substrate made of Al is often used. Since Al has a low melting point (approximately 600° C.), the substrate made of Al is susceptible to deformation or composition change if it is exposed to a temperature not lower than 400° C.
Alternatively, in order to execute the sol-gel method at a low temperature capable of preventing deformation or composition change of Al, it is necessary to mix various impurities, such as alkali metal and heavy metal, into a sol or to form a glass layer in the film. In this case, a high purity ceramic film having high corrosion resistance can not be formed. Further, in the ceramic film formed at a comparatively low temperature, bonding strength between granular components is low. Therefore, generation of particles is highly possible.
Thus, heretofore, when the sol-gel method is used as a method of manufacturing the member for a plasma processing apparatus in order to obtain the member excellent in film formability, durability, and reliability, there is a problem in obtaining a high purity ceramic film and in preventing deformation or composition change of a substrate made of low-melting-point metal.
It is therefore an object of the present invention to solve the problem in the conventional technique and to provide a member for a plasma processing apparatus, which is excellent in film formability, durability, and reliability.
It is another object of the present invention to provide a method of manufacturing a member for a plasma processing apparatus, which is capable of manufacturing such a member as mentioned above.

Means to Solve the Problem

According to the present invention, at least the following aspects (1) through (24) are obtained.
(1) A member for a plasma processing apparatus, the member comprising a substrate and a ceramic film formed thereon and having a purity not less than 98%, in which the ceramic film is constituted by grains having a grain diameter not greater than 50 nm, the amount of moisture released from the film being not more than 10¹⁹molecules/cm².
(2) The member for a plasma processing apparatus according to the aspect (1), the member comprising, as the ceramic film, a sol-gel film formed by a sol-gel method.
(3) The member for a plasma processing apparatus according to the aspect (1), in which the substrate is made of metal, ceramics, glass, or a composite material thereof, the ceramic film being a film comprising at least one kind of element selected from group II-VI elements, group XII-XIV elements, and rare-earth elements in the periodic table.
(4) The member for a plasma processing apparatus according to the aspect (1), in which the ceramic film is a film comprising at least one kind of element selected from Mg, Al, Si, Ti, Cr, Zn, Y, Zr, W, and the rare-earth elements.
(5) The member for a plasma processing apparatus according to the aspect (1), in which the ceramic film has translucency represented by a transmittance not less than 80% in a visible light range at a wavelength between 400 and 800 nm when a film thickness is not greater than 5 μm.
(6) The member for a plasma processing apparatus according to the aspect (1), in which the ceramic film is formed in an oxygen-containing atmosphere in a temperature range between 250 and 1200° C.
(7) The member for a plasma processing apparatus according to the aspect (1), in which the ceramic film has a purity not less than 99.5%.
(8) The member for a plasma processing apparatus according to the aspect (1), in which the substrate is made of metal, the substrate being provided with a film formed on its surface and obtained by passivation of the surface of the substrate.
(9) The member for a plasma processing apparatus according to the aspect (1), in which the substrate is made of aluminum, the substrate being provided with an anodic oxidation film formed on its surface.
(10) The member for a plasma processing apparatus according to the aspect (1), in which the substrate is made of metal, the substrate being provided with a film formed on its surface by heat treatment.
(11) The member for a plasma processing apparatus according to the aspect (1), the member comprising, as the ceramic film, a sprayed film formed on the substrate by a spraying method and a sol-gel film formed on the sprayed film by a sol-gel method.
(12) The member for a plasma processing apparatus according to the aspect (1), the member comprising, as the ceramic film, a sol-gel film formed on the substrate by a sol-gel method and a sprayed film formed on the sol-gel film by a spraying method.
(13) The member for a plasma processing apparatus according to the aspect (1), in which the substrate has a plate-like shape having pores, a tubular shape, or a container shape.
(14) A method of manufacturing a member for a plasma processing apparatus, comprising the step of forming a ceramic film having a purity not less than 98% on a substrate, in which the forming of the ceramic film is carried out so that grains constituting the film have a grain diameter not greater than 50 nm and the amount of moisture released from the film is not more than 10¹⁹molecules/cm².
(15) The method of manufacturing a member for a plasma processing apparatus according to the aspect (14), in which, as the ceramic film, a sol-gel film is formed by a sol-gel method.
(16) The method of manufacturing a member for a plasma processing apparatus according to the aspect (14), comprising the steps of forming the substrate made of metal, ceramics, glass, or a composite material thereof; and forming, as the ceramic film, a film comprising at least one kind of element selected from group II-VI elements, group XII-XIV elements, and rare-earth elements in the periodic table.
(17) The method of manufacturing a member for a plasma processing apparatus according to the aspect (14), comprising the step of forming, as the ceramic film, a film comprising at least one kind of element selected from Mg, Al, Si, Ti, Cr, Zn, Y, Zr, W, and rare-earth elements.
(18) The method of manufacturing a member for a plasma processing apparatus according to the aspect (14), in which the ceramic film is formed in an oxygen-containing atmosphere in a temperature range between 250 and 1200° C.
(19) The method of manufacturing a member for a plasma processing apparatus of the aspect (14), in which the ceramic film has a purity not less than 99.5%.
(20) The method of manufacturing a member for a plasma processing apparatus of the aspect (14), comprising the steps of forming the substrate made of metal; and forming, on a surface of the substrate, a film obtained by passivation of the surface of the substrate.
(21) The method of manufacturing a member for a plasma processing apparatus of the aspect (14), comprising the steps of forming the substrate made of aluminum; and forming an anodic oxidation film on a surface of the substrate.
(22) The method of manufacturing a member for a plasma processing apparatus of the aspect (14), comprising the steps of forming the substrate made of metal; and forming a film formed by a heat treatment on a surface of the substrate.
(23) The method of manufacturing a member for a plasma processing apparatus of the aspect (14), comprising, as the forming of the ceramic film, the steps of forming a sprayed film on the substrate by a spraying method and forming a sol-gel film on the sprayed film by a sol-gel method.
(24) The method of manufacturing a member for a plasma processing apparatus of the aspect (14), comprising, as the forming of the ceramic film, the steps of forming a sol-gel film on the substrate by a sol-gel method and forming a sprayed film on the sol-gel film by a spraying method.

EFFECT OF THE INVENTION

The member for a plasma processing apparatus according to the present invention is excellent in film formability, durability, and reliability.
The sol-gel film in the present invention is highly dense and highly flat and smooth and therefore has high plasma resistance in a high density plasma environment. Further, also in a corrosive gas environment and in a chemical environment, the sol-gel film exhibits high gas resistance and high chemical resistance because the film is highly dense so as to protect a substrate.
In the conventional technique, uniform film formation onto a complicated configuration, an inner surface of a pipe, or the like is impossible. According to the present invention, film formation is easily performed by pouring a liquid sol or by dipping.
Further, by forming the highly dense sol-gel film on a surface of a sprayed film, particle generation from the sprayed film can be suppressed.
Furthermore, when a composite film obtained by pretreatment or surface treatment of the sprayed film or a composite film having a sandwich structure is exposed to a corrosive gas, peeling of the sprayed film can be suppressed because the dense sol-gel film blocks the corrosive gas.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph for describing a characteristic of a member for a plasma processing apparatus according to a first example of the present invention, showing measurement data of the amount of moisture released from an Y₂O₃film.

FIG. 2 is a graph for describing the characteristic of the member for a plasma processing apparatus according to the first example of the present invention, showing the amount of moisture released at each of temperature rising stages.

FIG. 3 is a graph for describing the characteristic of the member for a plasma processing apparatus according to the first example of the present invention, showing a relationship between a firing temperature and the amount of moisture released when a temperature is increased up to 500° C.

FIG. 4 is a schematic sectional view showing a member for a plasma processing apparatus according to a second example of the present invention.

FIG. 5 is a schematic sectional view showing a member for a plasma processing apparatus according to a third example of the present invention.

FIG. 6 is a schematic sectional view showing a member for a plasma processing apparatus according to a fourth example of the present invention.

FIG. 7 is a schematic sectional view showing a member for a plasma processing apparatus according to a fifth example of the present invention.

FIG. 8 is a schematic sectional view showing a member for a plasma processing apparatus according to a sixth example of the present invention.

FIG. 9 is a schematic sectional view showing a member for a plasma processing apparatus according to a seventh example of the present invention.

FIG. 10 is a table showing evaluation results for the members for a plasma processing apparatus according to the present invention together with evaluation results for comparative examples.

FIG. 11 is a graph for describing a characteristic of the member for a plasma processing apparatus according to the example of the present invention, showing a transmittance of a sample 10 as the example at a visible light wavelength in a range between 400 and 800 nm.

FIG. 12 is a graph for describing a characteristic of the member for a plasma processing apparatus according to the example of the present invention, showing a transmittance of a sample 11 as the example at a visible light wavelength in a range between 400 and 800 nm.

FIG. 13 is a graph for describing a characteristic of the member for a plasma processing apparatus according to the example of the present invention, showing a transmittance of a sample 12 as the example at a visible light wavelength in a range between 400 and 800 nm.

FIG. 14 is a graph for describing a characteristic of the member for a plasma processing apparatus according to the example of the present invention, showing a transmittance of a sample 37 as a comparative example at a visible light wavelength in a range between 400 and 800 nm.

BEST MODE FOR EMBODYING THE INVENTION

A member for a plasma processing apparatus according to the present invention has a ceramic film which is formed by a sol-gel method, which has a purity not less than 98%, and which has plasma resistance and corrosive gas resistance.
Further, a method of manufacturing a member for a plasma processing apparatus according to the present invention comprises a step of forming a ceramic film on a substrate by the sol-gel method, which has a purity not less than 98% and has plasma resistance and corrosive gas resistance.
Specifically, according to the present invention, there is provided a member for a plasma processing apparatus, which comprises a substrate made of a material, such as metal, ceramics, and glass, generally used as a structural material and having a surface coated with a ceramic film made of an oxide formed of group II-VI elements, group XII-XIV elements, and rare-earth elements, or a composite oxide formed of two or more kinds of the above-mentioned elements. In this technique, the sol-gel method is used. By coating the substrate by using a spraying method, a dipping method, or the like, and then performing heat treatment in an oxygen-containing atmosphere at a temperature not lower than 250° C., oxide ceramics can be obtained.
For the spraying method, use of a specially designed and optimized nozzle is recommended. Instead, also by using an airbrush and a spray gun commercially available, a similar film can be obtained. The dipping method is a method of coating a substrate surface with a uniform sol film by dipping a substrate into a solution and thereafter pulling out the substrate at a low speed (10 to 50 mm per minute) and at a constant rate.
As a heat treatment condition, it is necessary to heat at a firing temperature between 250 and 1200° C. for 1 to 5 hours by using an oven or an electric furnace.
Further, this technique is characterized in that a ceramic thin film having a high purity from 98% to 99.99% can be obtained at such a low temperature of 250° C.
Other than direct film formation onto the substrate, the above-mentioned technique is applicable to composite formation by surface coating onto a sprayed film, composite formation by application of a sprayed film after formation of a sol-gel film on a substrate, and a composite film formed by film formation for passivation of a substrate, such as an anodic oxidation film and a fluoride film.
Incidentally, a grain diameter of the sol-gel film in the present invention was observed by using a field-emission-type scanning electron microscope (JEM-6700F manufactured by JEOL Ltd.). As a result, it was confirmed that all grains constituting the film had a grain diameter not greater than 50 nm. In a conventional film formation method, a grain diameter of a ceramic film is not smaller than 100 nm. In contrast, in the present invention, by achieving a grain diameter not greater than 50 nm, it is possible to perform film formation with a high purity (98% or more) and at a low temperature of 250° C. This is because, by microparticulation of the sol-gel film into a grain diameter of 50 nm or less, a sintering temperature is drastically lowered and sintering is started at approximately 250° C. Non-Patent Document 1 describes that, as grains become smaller, grain boundary diffusion and volume diffusion contributing to sintering are relatively increased and this relationship is extremely effective when a material having a high steam pressure and difficult to be densified is sintered and that, when a grain diameter becomes smaller, the number of contact points per unit volume is increased and the number of generation points and disappearance points of atoms involved in mass transfer is increased, thereby providing a state preferable for densification. Thus, even at a low processing temperature lower than 700° C., a high purity can be achieved only by the sol-gel method.

EXAMPLES

Hereinbelow, a member for a plasma processing apparatus and a method of manufacturing the member for a plasma processing apparatus according to examples of the present invention will be described with reference to the drawing.
Samples 1 to 29 as examples of the present invention and samples 31 to 37 as comparative examples were manufactured. For those samples, some characteristics were verified and evaluated. Results thereof are shown in a table of FIG. 10.
Each of the samples 1 to 29 as the examples of the present invention comprises a substrate made of one of various materials shown in a substrate-column in the table and having a 50 to 200 mm square size and a ceramic film formed on a surface of the substrate by a film formation method including at least a sol-gel method. By a device used in forming the ceramic film by the sol-gel method, film formation was carried out by spraying a sol as a raw material onto the substrate by a spray nozzle. Further, an electric furnace was used for heat treatment.

First Example

As measurement of a basic property of the ceramic film of the present invention, the amount of moisture released from a ceramic film formed on a Si substrate was observed. The amount of released moisture was measured by an atmospheric pressure ionization mass spectrometry device (APIMS: UG-302P manufactured by Renesas Eastern Japan Semiconductor, Inc.).
Each sample is placed in a reactor tube manufactured by using an electrolytically-polished pipe of SUS316L having a size of ½ inch. A high-purity Ar gas having an impurity concentration of 1 ppb or less is used as a carrier gas. This is a system in which the Ar gas is made to pass over the sample at a flow rate of 1.2 L/min and the amount of moisture released from the sample is measured by the APIMS.
A temperature profile at a time of measurement of the amount of moisture released from the ceramic film was set as follows. After the ceramic film was kept at a temperature of 25° C. for 10 hours, the temperature was increased up to 100° C. in 10 minutes. Then, the ceramic film was kept at 100° C. for 1 hour and 50 minutes. Thereafter, the temperature was increased stepwise by every 100° C. up to 500° C. During the above-mentioned period, the amount of released moisture was measured.
FIG. 1 shows measurement data of the amount of moisture released from an Y₂O₃film. A horizontal axis shows a measurement time by the APIMS and a vertical axis shows the number of water molecules released per unit area. Using the sol-gel method, the samples were prepared by firing at 300° C., 600° C., and 900° C. in the atmosphere and had a film thickness of 1 μm.
FIG. 2 shows a graph plotting the amount of released moisture at each temperature rising stage with respect to temperature reciprocals (1/K) for 25° C., 100° C., 200° C., 300° C., 400° C., and 500° C. It was confirmed that an activation energy Ea of moisture desorption was 0.055 eV regardless of a firing temperature. This suggests that a film quality of a surface is not changed at all and only an effective surface area is decreased. Further, it was confirmed that the amount of moisture released during the temperature rising up to 500° C. was 4.23×10¹⁸molecules/cm²for the samples fired at 300° C., 1.75×10¹⁸molecules/cm²for the samples fired at 600° C., and 6.31×10¹⁷molecules/cm²for the samples fired at 900° C.
FIG. 3 shows a relationship between the firing temperature and the amount of moisture released when the temperature is raised up to 500° C. As the firing temperature is increased, a bonding strength at a grain boundary between Y₂O₃crystal grains is increased and the effective surface area is decreased. Hence, it is understood that the amount of released moisture is significantly decreased. Further, it is understood that, with the firing temperature not lower than 300° C., the amount of moisture released from the film is not more than 10¹⁹molecules/cm².

Second Example

With respect to the samples 1 to 14 as a second example of the present invention, only a sol-gel film was formed on each of various kinds of substrates as shown in FIG. 4, and evaluation was performed.

Third Example

With respect to the samples 15 to 29 as a third example of the present invention, a passivation film or the like was formed as a base on a surface of a substrate made of aluminum (Al) or stainless steel (SUS) and a sol-gel film was formed on the base, as shown in FIG. 5. Then, evaluation was performed. With respect to a SUS substrate of the sample 15, a passivation film made of Cr₂O₃was formed as a base on a surface of the substrate and a sol-gel film was further formed thereon. Then, evaluation was performed. With respect to an Al metal substrate of each of the samples 16 and 17, an anodic oxidation film was formed as a base by oxidizing Al of a substrate surface by electric field treatment in a solution and a sol-gel film was further formed. Then, evaluation was performed. With respect to an Al metal substrate of the sample 18, a MgF₂film was formed as a base by fluoridizing a substrate surface, and a sol-gel film was further formed. Then, evaluation was performed.

Fourth Example

With respect to a composite of a sprayed film and a sol-gel film of each of the samples 19 to 23 as a fourth example of the present invention, evaluation was performed on a composite film obtained by forming the sprayed film and thereafter forming the sol-gel film on a surface thereof, as shown in FIG. 6.

Fifth Example

With respect to a composite of a sol-gel film and a sprayed film of each of the samples 24 and 25 as a fifth example of the present invention, evaluation was performed on a composite film obtained by forming the sol-gel film as a base and forming the sprayed film thereon, as shown in FIG. 7.

Sixth Example

With respect to a composite with a sprayed film of each of the samples 26 and 27 as a sixth example of the present invention, evaluation was performed on a composite film having a sandwich structure obtained by forming a sol-gel film as a base, forming a sprayed film thereon, and forming another sol-gel film on a surface thereof, as shown in FIG. 8.

Seventh Example

With respect to a composite with a sprayed film of each of the samples 28 and 29 as a seventh example of the present invention, evaluation was performed on a composite film obtained by forming an anodic oxidation film as a base, forming the sprayed film thereon, and further forming a sol-gel film formed on a surface thereof, as shown in FIG. 9.

Comparative Examples

In contrast, the samples 31 to 37 as comparative examples were made of various substrates shown in the table of FIG. 10 and ceramic films were formed by using the spraying method, a thermal CVD method, or a conventional sol-gel method. It is noted here that the conventional sol-gel method is a method in which a structure and a purity of the ceramic film are out of the scope of the present invention.
Hereinbelow, description will be made about verification and evaluation results for the samples 1 to 29 as the examples of the present invention and the samples 31 to 37 as the comparative examples.
(Film Purity)
Purity analysis was performed on each of the ceramic films. As a method of analysis, GDMS (glow-discharge mass spectrometry) was used and, as an analyzer, VG9000 manufactured by Fl. Elemental was used.
A plasma processing apparatus requires severer impurity control with miniaturization of a printed circuit and so on. Hence, in order to improve a yield of an electronic component, a higher-purity ceramic film is required.
The sol-gel film in each of the samples 1 to 29 as the examples of the present invention has a purity not less than 99%.
In contrast, the conventional sol-gel film in each of the samples 31 and 32 as the comparative examples contains a large amount of alkali metal for the purpose of technically enabling low-temperature film formation. Accordingly, the purity is about 85% and does not reach 98% or more. The sprayed film in each of the samples 33 and 34 as the comparative examples has a purity of 99%. The CVD film in each of the samples 35 to 37 as comparative examples has a purity of 95%.
(Etching Rate)
In a chamber of a parallel plate type RIE etching apparatus, a 6-inch silicon wafer was placed and a mirror-polished test specimen was placed thereon. Then, a corrosion test was performed by plasma exposure in plasma of CF₄+O₂for 10 hours. During the test, a part of a polished surface was masked with a polyimide tape and a silicon wafer. A difference in level between the masked part and an unmasked part was measured by a stylus method to calculate an etching rate.
Ceramics used herein as the examples is an oxide comparatively resistant against the plasma. Therefore, the amount of etching of its surface is very small.
On the other hand, for the samples 31 to 34 as the comparative examples, Y₂O₃and Al₂O₃are similar to each other. For the films formed by the CVD method in the samples 35 to 37 as the comparative examples, variation is observed.
(The Number of Particles)
With respect to the silicon wafer after the above-mentioned plasma test, the number of grains having a size of 0.5 micron or more was measured by using a particle counter (Surfscan6420 manufactured by Tencor).
With respect to the number of particles, an excellent result was obtained by the sol-gel film which is a dense and flat film in comparison with other film formation methods. It is noted here that, since each of the samples 19 to 23 as the examples of the present invention has the sprayed film as the outermost surface, the number of particles is increased similarly to the samples 33 and 34 as the comparative examples. However, in each of the samples 19 to 23 and 26 and 27 as the examples of the present invention in which the sol-gel film is formed on a surface of the sprayed film, the number of particles is decreased to about one third of that of the samples with the sprayed film only, although the number of particles is increased in comparison with the simple sol-gel films. Thus, by applying the sol-gel film, an effect of decreasing the particles was obtained.
(Chlorine Gas Exposure)
Among electronic component manufacturing apparatuses, an apparatus for manufacturing a semiconductor device has an internal environment constantly exposed to a corrosion gas in each process. In view of the above, a film in each of the examples was exposed to a Cl₂gas to evaluate corrosion gas resistance.
As an evaluation method, a test specimen was placed in a sample mounting cell and a gas exposure test was carried out in an air stream containing 100% Cl₂gas and having a pressure of 0.3 MPa for 24 hours. A temperature in the cell was kept at 100° C. A surface condition after the gas exposure was checked and presence or absence of surface corrosion or presence or absence of peeling was used as an evaluation criterion.
With respect to each of the samples 1 to 29 as the examples of the present invention in which the sol-gel film was formed, no peeling occurs and no change in surface condition was observed even after the Cl₂gas exposure. Thus, it was confirmed that, even if the Al metal substrate having low Cl₂gas resistance was used as the base, formation of a dense sol-gel film prevented corrosion of the substrate and durability and reliability as the member for a plasma processing apparatus were improved.
In contrast, in the conventional sol-gel films or the single layer sprayed films in the samples 31 to 34 as the comparative examples, film peeling occurred. As a cause of this, it is presumed that, since the film itself has a large number of pores, a Cl₂gas passing through consecutive pores directly corrodes the Al metal substrate to bring about peeling of the film.
For the CVD films in the samples 35 to 37 as the comparative examples, no peeling of the film occurred. However, deterioration in quality of a surface of the film was observed.
(Film Formability to a Complex Configuration)
Judgment was made about whether or not film formation is possible onto a complicated configuration, such as two or more steps and an inner surface of a box shape, an inner surface of a cylinder having a small diameter (for example, a gas pipe having an inner diameter of about 5 mm), an inside of a porous body, and an inside of a fibrous filter.
In the examples 1 to 18, film formation was easily possible onto the two or more steps and the inner surface of the box shape. In case of the composite film with the sprayed film in each of the samples 19 to 29 as the examples of the present invention, film formability depends on whether or not the sprayed film can be formed on an object surface. Therefore, those samples were excepted from the present evaluation. However, the sol-gel film could be formed throughout an entire surface onto a complicated configuration partly containing the sprayed film.
In contrast, in case of the comparative examples, the conventional sol-gel film could flexibly be formed onto a comparatively complicated configuration. However, in case of film formation with corners or a sharp R shape, film peeling occurred due to low adhesion. In case of the sprayed film, film formation is performed only in a region where a frame with a sprayed material melted thereon can be linearly irradiated. Therefore, film formation was impossible onto a substrate with a shaded part formed therein. The CVD film is not formed unless a surface on which a film is to be formed is completely exposed to a material gas supplied. Further, in case where a film formation surface has both a parallel plane and an orthogonal plane, film formation rates thereof are extremely widely varied. Therefore, uniform film formation was impossible.
Next, with respect to the inner surface of the cylinder having a small diameter, the inside of the porous body, and the inside of the fibrous filter, a material solution (sol) was supplied to pass therethrough, dried, and thereafter fired. By using the sol-gel method, film formation was possible onto those members having the above-mentioned configurations although it was impossible by the conventional technique. By the spraying method and the CVD method in the comparative examples, film formation throughout the entire surface was impossible in principle. Although film formation was possible by using the conventional sol-gel method, application to the member for a plasma processing apparatus is difficult in view of purity and particles.
(Transmission, Transmittance)
Regarding the samples 10 to 13 as the examples of the present invention and the sample 37 as the comparative example, the substrates themselves exhibit translucency. Therefore, a transmittance at a visible light wavelength between 400 and 800 nm was measured. In the measurement, a self-recording spectrophotometer (U-3500 manufactured by Hitachi, Ltd.) was used. Results of transmittances of the samples 10 to 12 are shown in FIGS. 11 to 13, respectively. As a comparative example, a transmittance of the CVD film is shown in FIG. 14.
When a transmittance in a visible light range falls below 80%, a film starts to look cloudy in visual observation. Further, when the transmittance falls below 60%, the film obviously looks cloudy. Thus, in case of application to a member required to have translucency, a transmittance not less than 80% is necessary in order to obtain excellent translucency.
When the conventional technique is used, it is general that, as a film thickness increases, a transmittance decreases. However, regarding the sol-gel film of the present invention, decrease in transmittance in a visible light range does not substantially occur if a film thickness is between 1 μm and 5 μm, as shown in FIGS. 11 to 13. Further, the transmittance is kept at about 90% throughout an entire wavelength range. Considering that 4 mm thick quartz as a substrate has a transmittance of about 93% throughout an entire wavelength range, it is understood that a transmittance of the film alone is calculated to about 97%.
In contrast, as shown in FIG. 14, the CVD film has a transmittance which remarkably decreases to about 50 to 80% at a film thickness of 1 μm. Further, the sprayed film and the conventional sol-gel film do not exhibit translucency because a large number of pores are contained and the film is thick.
(Comprehensive Evaluation)
With respect to the sol-gel single layer films or the multilayer composite films containing no sprayed film in the samples 1 to 18 as the examples of the present invention and the samples 31 to 37 as the comparative examples, comprehensive evaluation of O is given to those films which exhibit excellent plasma corrosion resistance represented by an etching rate of 10 nm/minute or less, which exhibit low dusting characteristics represented by the number of generated particles not more than 50, and which can be processed into a complicated configuration. Further, with respect to the composite films including the sprayed film combined with the sol-gel film in the samples 19 to 29 as the examples of the present invention, comprehensive evaluation of O is given to those films improved in the number of particles and in chlorine gas exposure characteristics in comparison with the simple sprayed film.

INDUSTRIAL APPLICABILITY

The present invention is applicable not only to an electronic component manufacturing apparatus, such as a semiconductor element and a liquid crystal panel, but also to a member for use in all apparatuses for conducting plasma processing or the like with a corrosive atmosphere and to a method of manufacturing the same.

Claims

1. A member for a plasma processing apparatus, the member comprising a substrate and a ceramic film formed thereon and having a purity not less than 98%, wherein:

the ceramic film is constituted by grains having a grain diameter not greater than 50 nm, the amount of moisture released from the film being not more than 10¹⁹molecules/cm².

2. The member for a plasma processing apparatus as claimed in claim 1, the member comprising, as the ceramic film, a sol-gel film formed by a sol-gel method.

3. The member for a plasma processing apparatus as claimed in claim 1, wherein:

the substrate is made of metal, ceramics, glass, or a composite material thereof;

the ceramic film being a film comprising at least one kind of element selected from group II-VI elements, group XII-XIV elements, and rare-earth elements in the periodic table.

4. The member for a plasma processing apparatus as claimed in claim 1, wherein the ceramic film is a film comprising at least one kind of element selected from Mg, Al, Si, Ti, Cr, Zn, Y, Zr, W, and the rare-earth elements.

5. The member for a plasma processing apparatus as claimed in claim 1, wherein the ceramic film has translucency represented by a transmittance not less than 80% in a visible light range at a wavelength between 400 and 800 nm when a film thickness is not greater than 5 μm.

6. The member for a plasma processing apparatus as claimed in claim 1, wherein the ceramic film is formed in an oxygen-containing atmosphere in a temperature range between 250 and 1200° C.

7. The member for a plasma processing apparatus as claimed in claim 1, wherein the ceramic film has a purity not less than 99.5%.

8. The member for a plasma processing apparatus as claimed in claim 1, wherein:

the substrate is made of metal;

the substrate being provided with a film formed on its surface and obtained by passivation of the surface of the substrate.

9. The member for a plasma processing apparatus as claimed in claim 1, wherein:

the substrate is made of aluminum;

the substrate being provided with an anodic oxidation film formed on its surface.

10. The member for a plasma processing apparatus as claimed in claim 1, wherein:

the substrate is made of metal;

the substrate being provided with a film formed on its surface by heat treatment.

11. The member for a plasma processing apparatus as claimed in claim 1, the member comprising, as the ceramic film, a sprayed film formed on the substrate by a spraying method and a sol-gel film formed on the sprayed film by a sol-gel method.

12. The member for a plasma processing apparatus as claimed in claim 1, the member comprising, as the ceramic film, a sol-gel film formed on the substrate by a sol-gel method and a sprayed film formed on the sol-gel film by a spraying method.

13. The member for a plasma processing apparatus as claimed in claim 1, wherein the substrate has a plate-like shape having pores, a tubular shape, or a container shape.

14. A method of manufacturing a member for a plasma processing apparatus, comprising the step of forming a ceramic film having a purity not less than 98% on a substrate, wherein:

the forming of the ceramic film is carried out so that grains constituting the film have a grain diameter not greater than 50 nm and the amount of moisture released from the film is not more than 10¹⁹molecules/cm².

15. The method of manufacturing a member for a plasma processing apparatus as claimed in claim 14, wherein, as the ceramic film, a sol-gel film is formed by a sol-gel method.

16. The method of manufacturing a member for a plasma processing apparatus as claimed in claim 14, comprising the steps of:

forming the substrate made of metal, ceramics, glass, or a composite material thereof; and

forming, as the ceramic film, a film comprising at least one kind of element selected from group II-VI elements, group XII-XIV elements, and rare-earth elements in the periodic table.

17. The method of manufacturing a member for a plasma processing apparatus as claimed in claim 14, comprising the step of forming, as the ceramic film, a film comprising at least one kind of element selected from Mg, Al, Si, Ti, Cr, Zn, Y, Zr, W, and rare-earth elements.

18. The method of manufacturing a member for a plasma processing apparatus as claimed in claim 14, wherein the ceramic film is formed in an oxygen-containing atmosphere in a temperature range between 250 and 1200° C.

19. The method of manufacturing a member for a plasma processing apparatus as claimed in claim 14, wherein the ceramic film has a purity not less than 99.5%.

20. The method of manufacturing a member for a plasma processing apparatus as claimed in claim 14, comprising the steps of:

forming the substrate made of metal; and

forming, on a surface of the substrate, a film obtained by passivation of the surface of the substrate.

21. The method of manufacturing a member for a plasma processing apparatus as claimed in claim 14, comprising the steps of:

forming the substrate made of aluminum; and

forming an anodic oxidation film on a surface of the substrate.

22. The method of manufacturing a member for a plasma processing apparatus as claimed in claim 14, comprising the steps of:

forming the substrate made of metal; and

forming a film formed by a heat treatment on a surface of the substrate.

23. The method of manufacturing a member for a plasma processing apparatus as claimed in claim 14, comprising, as the forming of the ceramic film, the steps of forming a sprayed film on the substrate by a spraying method and forming a sol-gel film on the sprayed film by a sol-gel method.

24. The method of manufacturing a member for a plasma processing apparatus as claimed in claim 14, comprising, as the forming of the ceramic film, the steps of forming a sol-gel film on the substrate by a sol-gel method and forming a sprayed film on the sol-gel film by a spraying method.