JP2009161848A - Method for manufacturing inner member of plasma treatment vessel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing an inner member of a plasma treatment vessel which has a thermal-sprayed film of Y<SB>2</SB>O<SB>3</SB>thereon with an atmospheric plasma spraying method, and is resistant to plasma erosion. <P>SOLUTION: The method for manufacturing the inner member of the plasma treatment vessel includes: forming the thermal-sprayed film 21 of Y<SB>2</SB>O<SB>3</SB>containing a porosity of 5% or more by using a plasma spraying device having one set of an anode 11 and a cathode 12 in the same manner as in a conventional method; and subsequently forming a thermal-sprayed film 22 of Y<SB>2</SB>O<SB>3</SB>having a porosity of less than 5% on the thermal-sprayed film 21. The method for forming the thermal-sprayed film having the porosity of less than 5% is described below. A powdery base material of Y<SB>2</SB>O<SB>3</SB>having a particle size of 10 to 45 μm is supplied to a plasma which is generated by causing electric discharge between the anode and the cathode of the one set and supplying an operation gas to the space. The thermal-sprayed film 22 of Y<SB>2</SB>O<SB>3</SB>having the porosity of less than 5% can be formed by making the particle size smaller than that in a normal plasma spraying method. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an inner member of a plasma processing container, and particularly used in a plasma processing container in which a plasma atmosphere of a process gas containing a halogen element is formed, for example, a deposition shield, an exhaust plate, a focus ring, an electrode plate, and an electrostatic chuck The present invention also relates to a method for manufacturing a plasma processing container inner member such as a processing container inner wall material.

Various members used in the plasma processing container of a semiconductor manufacturing apparatus are covered with an anodic oxide film of aluminum, a sprayed film such as boron carbide, or sintered with Al ₂ O ₃ or Si ₃ N _4. Covering with a body film, and also with a polymer film such as a fluorine resin or an epoxy resin.

However, these materials use a gas containing a halogen element such as a fluoride such as C ₄ F ₈ or NF ₃ , a chloride such as BCl ₃ or SnCl _4, or a bromide such as HBr in a processing container. Therefore, it is known that erosion damage is caused by ions excited by plasma.

  The environment in which the plasma is generated is ionized even by a non-corrosive gas such as Ar gas, which strongly collides with the solid surface. Receive.

  Therefore, for example, plasma erosion resistance is strongly required for plasma processing container inner members such as deposition shields, exhaust plates, focus rings, electrode plates, electrostatic chucks, and processing container inner wall materials.

In order to increase the plasma erosion resistance, conventionally, an alumite treatment (Al ₂ O ₃ film) has been applied to the surface of a member in the processing vessel.

However, alumite treatment has a problem that its life is short when it is subjected to plasma erosion in an atmosphere containing a halogen gas. Further, since the film contains aluminum, there is a problem that AlF ₃ particles are generated and adhere to the semiconductor product to be manufactured.

  In order to solve this problem, Patent Document 1 (Japanese Patent Laid-Open No. 7-176524) proposes to form a sprayed film by spraying alumina on the surface of the inner member of the plasma processing container.

However, the plasma sprayed alumina was improved in plasma erosion resistance than anodized, but was not sufficient. On the other hand, since Y ₂ O ₃ has a strong chemical bonding force with oxygen, it has a property that it can maintain a stable state even if it is subjected to a plasma erosion action in an atmosphere containing a halogen gas. Therefore, Patent Document 2 (Japanese Patent No. 3510993) proposes an inner member of a plasma processing container covered with a Y ₂ O ₃ sprayed film having a porosity of 5 to 10%.

In Patent Document 2, the reason for setting the upper limit of the porosity to 10% is that if it exceeds 10%, the plasma erosion resistance is inferior. That is, the smaller the porosity, the better the plasma erosion resistance. Further, the Y ₂ O ₃ sprayed film requires a thickness of about 200 μm. However, in the atmospheric plasma spraying method, it is difficult to manufacture a sprayed film having a thickness of about 200 μm and a porosity of less than 5%.

  When the low-pressure plasma spraying method is used, since it is performed in an atmosphere close to a vacuum, the molten particles collide with the substrate at a high speed without decreasing. Moreover, since the heat loss is small, the temperature of the molten particles when reaching the substrate is high. Since the vacuum is applied, an oxide film cannot be formed on the molten particles, resulting in a dense sprayed film. For these reasons, it is possible to form a sprayed film having a porosity of less than 5% by low pressure plasma spraying.

However, the low-pressure plasma spraying method requires a high-vacuum decompression chamber of about several tens of Pa and requires equipment costs. Moreover, since it is necessary to maintain a high vacuum while injecting a plasma jet, running costs such as operation of a vacuum pump are also increased. In addition, since thermal spraying is performed in a decompression chamber, continuous processing cannot be performed, and batch processing is performed, which is inefficient. For these reasons, the low pressure plasma spraying method is not suitable for mass production.
JP-A-7-176524 Patent 3510993

The present invention was conceived from the above situation, and has an object to provide a method for manufacturing a member in a plasma processing container that has a low-porosity Y ₂ O ₃ sprayed film and that can be easily manufactured. Yes.

In order to achieve the above object, the method for producing an inner member of a plasma processing container of the present invention forms a Y ₂ O ₃ sprayed coating having a porosity of 5% or more by air plasma spraying on the surface of a ceramic substrate, It is characterized in that a Y ₂ O ₃ sprayed coating having a porosity of less than 5% is formed on the sprayed coating.

An Al ₂ O ₃ sprayed coating is formed on the surface of a ceramic substrate by atmospheric plasma spraying, and a Y ₂ O ₃ sprayed coating having a porosity of less than 5% is formed on the sprayed coating. Alternatively, an intermediate layer may be formed between the Y ₂ O ₃ sprayed film having a porosity of 5% or more and the substrate surface.

Further, after forming a sprayed coating of Y ₂ O ₃ having a porosity of 5% or more and a thickness of 50 to 170 μm on the surface of a ceramic substrate, discharge is performed between a pair of anode and cathode, and the working gas A powdery material of Y ₂ O ₃ having a particle size of 10 to 45 μm is supplied to the plasma generated by supplying the material with a porosity of less than 5% and a thickness of 10 to 10 on the surface of the substrate under atmospheric pressure. It is characterized by forming a sprayed coating of 70 μm Y ₂ O ₃ .

According to the method for producing an inner member of the plasma processing container of the present invention, a ceramic substrate is used, and a sprayed film of Y ₂ O ₃ having a porosity of 5% or more is formed by a normal atmospheric plasma spraying method, A Y ₂ O ₃ sprayed film having a porosity of less than 5% is formed thereon. Therefore, it is possible to obtain a plasma processing container inner member that is resistant to plasma erosion by covering the sprayed film with a low porosity so as to seal the pores of the sprayed film with a high porosity.

Even if the porosity is small, it is eroded by the plasma gas gradually ionized from the surface, so the thickness of the sprayed film is also required. On the other hand, a sprayed film with a low porosity takes time to form the film. Therefore, by forming a Y ₂ O ₃ sprayed film having a porosity of 5% or more with a short film formation time, a sufficiently thick sprayed film can be secured. The same effect can be obtained even if the lower Y ₂ O ₃ sprayed film is Al ₂ O ₃ sprayed film.

In a normal atmospheric plasma spraying method, a sprayed film of Y ₂ O ₃ having a porosity of less than 5% can be formed by reducing the particle size of the powder raw material to be supplied. The normal particle size is about 70 μm, but this is reduced to about 10 to 45 μm. When the particle size is reduced, when the powder material of the thermal spray material enters the plasma jet generated between the anode and the cathode, it softens instantaneously and becomes high temperature and the viscosity decreases. When such small, high-temperature, low-viscosity molten particles ride on the plasma jet and collide with the substrate, they can spread thinly on the substrate and form a sprayed film with a low porosity. With such a sprayed film, a sealing process is performed to block holes in the sprayed film having a high porosity. However, if the particles are made smaller, it takes time to form the sprayed coating. Therefore, a thin sprayed coating with a small porosity is formed as a sealing process for forming a thicker sprayed coating with a higher porosity and then sealing the pores of the sprayed coating. Form.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a diagram showing the structure of a general plasma spraying apparatus. The plasma spraying apparatus 10 has a pair of electrodes of a nozzle-like anode 11 and a cathode 12 arranged at the center thereof. The plasma is generated by flowing an inert gas such as argon, nitrogen, or hydrogen from the gas introducing portion 13 into a donut-shaped gap between the anode and the cathode, and ionizing the gas by DC arc discharge. The plasma gas is ejected as a plasma jet 15 from the nozzle-shaped anode 11 to the outside of the plasma spraying apparatus. The vicinity of the anode 11 is cooled by cooling water flowing from the water pipes 16 to 17.

  The powder raw material is placed on the carrier gas through the powder injection pipe 18 connected in the vicinity of the outlet of the nozzle-shaped anode 11 and is generally input from an angle close to the perpendicular to the plasma jet. Thereby, the powder raw material is heated and softened in the plasma, and the powder particles in a semi-molten state are ejected on the plasma jet from the nozzle-like anode 11 to form a sprayed film 21 on the surface of the substrate 20.

  The base material 20 constitutes an inner member of the plasma processing container, but the surface thereof is roughened to an appropriate roughness by sandblasting. The reason for roughening is to increase the bonding force with the sprayed film 21. At this time, if a small sprayed film formed of one molten particle is referred to as a sprayed scale, the sprayed scales are randomly overlapped to form the sprayed film 21.

  At this time, the particle size of the powder raw material is about 70 μm. With such a particle size, the sprayed film 21 having a thickness of 200 μm can be formed in a relatively short time, but the porosity is 5% or more.

  In order to increase the plasma erosion resistance, it is desirable that the porosity is small. The porosity is influenced by the shape of the sprayed scale formed by one molten particle, and the shape of the sprayed scale is greatly influenced by the temperature and viscosity of the molten particle. The temperature and viscosity of the molten particles greatly depend on the particle size of the thermal spray raw material powder. When the particle size of the conventional thermal spray raw material powder is about 70 μm, the temperature of the molten particles becomes low and the viscosity thereof is high. For this reason, when the molten particles collide with the surface of the base material 21, the sprayed scale cannot be expanded greatly, and becomes thick and small. And according to such a thermal spray scale, since the magnitude | size of a thermal spray scale is large, the speed | rate at which a thermal spray film is formed becomes quick, and it can form the thermal spray film about 200 micrometers thick in a short time. And since the thick and small spray scales overlap, it becomes the sprayed film 21 with a high porosity.

In the present invention, formed to form a sprayed film 21 of the _Y 2 _{O 3} with a thickness of 50~170μm in the above conventional method, on which, by the following method, the sprayed film 22 of less _Y 2 _{O 3} having porosity To do.

In order to form a sprayed film of Y ₂ O ₃ having a low porosity, the same plasma spraying apparatus as in FIG. 1 is used, but the particle size of the spraying raw material powder is made as small as 10 to 45 μm. Since the volume (weight) of the particles becomes smaller in proportion to the cube of the particle size, when such small particles are supplied to the hot part of the plasma jet, they melt in a much shorter time than conventional particles. . Moreover, the melting temperature becomes high. As the melting temperature increases, the viscosity also decreases. When the molten particles having a low viscosity at a high temperature collide with the surface of the previously formed sprayed film having a high porosity, the sprayed scale formed by the molten particles becomes thin and spreads widely. This thermal spray scale is laminated | stacked in the state which also covered the part of a void | hole, and the whole thermal spray film | membrane with a large porosity below. That is, the pores of the sprayed film 21 having a high porosity are sealed with the sprayed film 22 of Y ₂ O ₃ having a low porosity.

  When the particle size of the thermal spray raw material powder is 10 to 45 μm, the porosity can be made less than 5%, but it takes time to form the thermal spray film. When the required thickness of the sprayed film is about 200 μm, it takes too much time for the sprayed material powder having a size of 10 to 45 μm.

  Therefore, in the present invention, in the spraying raw material powder of 10 to 45 μm, the thickness of the sprayed film 22 is set to 10 to 70 μm, preferably 30 to 50 μm. On the other hand, the thickness of the sprayed film 21 of the conventional spraying raw material powder having a particle size of 70 μm is 50 to 170 μm, preferably 100 to 150 μm.

  This is because if the thickness of the thermal sprayed film 22 is less than 10 μm, it is too thin and the sealing effect is not sufficient. This is because if the thickness exceeds 70 μm, it takes too much time to form the sprayed film 22.

  This is because if the thickness of the sprayed film 21 is less than 50 μm, the thickness of the sprayed film is too thin and the plasma erosion resistance decreases. This is because if it exceeds 170 μm, it takes too much time in consideration of the formation time of the next sprayed film to be formed.

  The plasma processing vessel inner member is made of a metal such as aluminum, aluminum alloy, stainless steel, or ceramic, and is roughened in advance by sandblasting as necessary to increase the adhesion to the sprayed film. Has been.

Y ₂ O ₃ needs to have a purity of 95% or more. This is because the plasma erosion resistance is lowered when impurities such as Fe, Mg, Cr, Al, Ni and Si are contained as oxides.

Further, the Y ₂ O ₃ sprayed film 21 may be formed directly on the inner member of the plasma processing container using a metal base material or a ceramic base material, but as a pre-process, a sprayed film such as Al ₂ O ₃ is used. It may be formed as an intermediate layer. Al ₂ O ₃ is chemically stable, has little change even in atmospheric plasma spraying, and can compensate for the plasma erosion resistance of Y ₂ O ₃ . In this case, the sprayed film has a three-layer structure.

Further, instead of the sprayed film 21 having a porosity of 5% or more, an Al ₂ O ₃ sprayed film may be formed. In this case, the sprayed film has a two-layer structure.

Next, the method for measuring porosity in the present invention will be described.
FIG. 2 is a diagram schematically showing a cross-sectional view of the sprayed film in FIG. As described above, the surface of the metal or ceramic substrate 20 is roughened by sandblasting or the like. Moreover, since the molten particles adhere and solidify, the sprayed films 21 and 22 are not flat on the surface, and have a shape rich in unevenness. FIG. 2 shows a cross section in which the sprayed film 22 is cut along a plane perpendicular to the surface of the base material (inner member of the plasma processing container) 20. Although FIG. 2 shows the case where there is no sprayed film 21 and only the sprayed film 22, the measuring method is the same for the sprayed film 21.

  A test piece is prepared by cutting the sprayed film 22 along a plane perpendicular to the surface of the substrate 20, embedded in a resin, polished on the surface, magnified in cross section with a microscope, and photographed with a digital camera. The digital image thus obtained is subjected to binarization processing by image processing, whereby the same one as schematically shown in FIG. 2 can be obtained.

  In the actual photograph, the pores 22a are shown in a different color from the surroundings, and the total area S of the pores 22a as the portions of different colors is obtained and divided by the cross-sectional area A of the sprayed film 22 in the measurement target area A number that is multiplied by 100%, that is, a numerical value obtained by the following formula

(S / A) x 100%
Is the porosity of the thermal sprayed films 21 and 22 in the present invention.

It is a figure which shows typically the structure of the plasma spraying apparatus which enforces the thermal spraying method of this invention. It is the figure which showed typically sectional drawing of the sprayed film in Example 1. FIG.

Explanation of symbols

11 sprayed film 22a pores of the anode 12 cathode 5% to 20 base member 21 porosity of _Y 2 _{O 3} sprayed coating of less than 22 porosity 5% _Y 2 _{O 3}

Claims (4)

Porosity to form a 5% or more of Y ₂ O ₃ sprayed coating by air plasma spraying onto the surface of the ceramic substrate, on top of the solution morphism film, the porosity is less than 5% of Y ₂ O ₃ sprayed coating A method for producing an inner member of a plasma processing container, wherein the member is formed by overlapping. Forming a sprayed coating of Al ₂ O _{3 on} the surface of a ceramic substrate by atmospheric plasma spraying, and forming a Y ₂ O ₃ sprayed coating having a porosity of less than 5% on the sprayed coating; A method for producing a member in a plasma processing container. The method for producing an inner member of a plasma processing container according to claim 1, wherein an intermediate layer is formed between the sprayed film of Y ₂ O ₃ having a porosity of 5% or more and the substrate surface. After forming a sprayed coating of Y ₂ O ₃ with a porosity of 5% or more and a thickness of 50 to 170 μm on the surface of a ceramic substrate, discharge is performed between a pair of anode and cathode to supply a working gas A powdery material of Y ₂ O ₃ having a particle size of 10 to 45 μm is supplied to the generated plasma, and the surface of the substrate has a porosity of less than 5% and a thickness of 10 to 70 μm under atmospheric pressure. A method for producing an inner member of a plasma processing container, wherein a sprayed coating of Y ₂ O ₃ is formed.

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