JP5168543B2 - Inside the plasma processing vessel - Google Patents

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 relates to 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. However, in the atmospheric plasma spraying method, when the porosity is less than 5%, it is difficult to manufacture.

  FIG. 5 is a diagram showing the structure of a conventional 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. Plasma is generated by flowing an inert gas such as argon or nitrogen through the doughnut-shaped gap between the anode and the cathode from the gas inlet 13 and ionizing the gas by DC arc discharge. Plasma 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 put on the carrier gas through a powder injection pipe 18 connected in the vicinity of the outlet of the nozzle-like anode 11 and is generally charged almost vertically into the plasma jet. As a result, the powder raw material is melted in plasma to form droplets and ejected from the nozzle-like anode 11 to form a sprayed film 21 on the surface of the substrate 20.

  At this time, the speed of powder injection is greatly influenced by the particle diameter of the powder. Thus, powders having a uniform particle diameter by classification are used as the thermal spray raw material powder, but some variation is unavoidable. For this reason, the speed of the charged powder must be varied. Because the powder particles vary and the powder is injected perpendicularly to the plasma jet, it is difficult to concentrate all the powder in the hottest region of the plasma center and generate particles that do not melt. To do. Since it is atmospheric pressure, an oxide film is formed on the surface of the molten particles. It was difficult to reduce the porosity.

  When the low-pressure plasma spraying method is used, since it is close to a vacuum, the molten particles collide with the substrate at 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 has been conceived from the above circumstances, and an object thereof is to provide an inner member of a plasma processing vessel that is provided with a low-porosity Y ₂ O ₃ sprayed film and can be manufactured at low cost, and a method for manufacturing the same. .

In order to achieve the above object, the surface of the substrate of the inner member of the plasma processing container of the present invention is coated with a Y ₂ O ₃ sprayed coating by atmospheric plasma spraying, and the Y ₂ O ₃ sprayed coating has a porosity of 5 It is characterized by being less than%. An intermediate layer may be formed between the Y ₂ O ₃ sprayed film and the substrate surface.

In order to achieve the above object, a method for producing an inner member of a plasma processing container according to the present invention comprises arranging a plurality of sets of anodes and cathodes around a central axis extending in the spraying direction, and generating a plasma flow generated between each anode and cathode. Are joined by a converging device and radiated into the atmosphere from one nozzle opening at the tip on the central axis, and Y ₂ O ₃ from the rear of the nozzle on the central axis of the plasma spraying apparatus. The powdery material is supplied, and a sprayed coating having a porosity of less than 5% is formed on the surface of the substrate.

According to the method for manufacturing an inner member of a plasma processing container of the present invention, plasma flows from a plurality of anodes and cathodes are merged on the central axis by a converging device to form a high-temperature plasma flow. When Y ₂ O ₃ powder is supplied from the rear of the central axis, all particles move on the central axis regardless of the size of the Y ₂ O ₃ powder, so that it reaches the maximum temperature region of the plasma. And can be melted. The resulting molten particles are hot and have a low viscosity. The molten particles fly on the plasma jet from the nozzle and collide with the base material, whereby a sprayed film of Y ₂ O ₃ having a porosity of less than 5% can be formed.

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

  FIG. 1 is a diagram schematically showing the configuration of a plasma spraying apparatus that performs the thermal spraying method of the present invention. In this plasma spraying apparatus 100, three sets of an anode 101 and a cathode 102 are arranged around a center line a. Although not shown in the figure, each set of the anode 101 and the cathode 102 is provided with a gas introduction part 13 and cooling water pipes 16 and 17 as in the plasma spraying apparatus 10 of FIG.

  The plasma flow ejected from each anode 101 is collected on the center line a by the converging device 110 and is ejected to the outside from the nozzle 120 as one plasma jet. The number of sets of the anode 101 and the cathode 102 is three in this embodiment, and they are arranged at equal intervals on the same circle with the central axis a as the center. However, it is not limited to three sets, and a plurality of sets may be arranged around the central axis a.

  FIG. 2 is an enlarged perspective view of the concentrator 110 viewed from the cathode 102 side. FIG. 3 is an enlarged perspective view of the nozzle as seen from the converging device side. There are three holes 112 facing each anode 101 on the cathode 102 side of the concentrator 110. These holes 112 are formed obliquely and are connected to the hole 121 of the nozzle 120 by forming one on the nozzle side of the converging device 110.

The powder injection pipe 115 is on the central axis a, and supplies Y ₂ O ₃ powder to the upstream side of the confluence of the plasma flows from the three anodes 101 in the converging device 110 from behind the injection direction of the plasma jet. The powder input pipe 115 extends on the central axis a, and all of the supplied Y ₂ O ₃ powder travels on the central axis a and passes through the junction. Since the plasma flows from the three anodes 101 are merged at the junction, the temperature is highest. Therefore, all of the supplied Y ₂ O ₃ powder is melted to form low-viscosity droplets at high temperature, that is, molten particles.

Such molten particles of Y ₂ O ₃ are sprayed from the nozzle 120 on the plasma jet and adhere to the surface of the inner member of the plasma processing vessel as a base material, and a sprayed film having a porosity of less than 5% is formed. The

  The inner member of the plasma processing container is made of aluminum or an aluminum alloy, and is roughened in advance by sandblasting or the like in order to increase the adhesion with the sprayed film.

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.

Moreover, although a sprayed film of Y ₂ O ₃ may be directly formed on the inner member of the plasma processing vessel as a base material, a sprayed film of Al ₂ O ₃ or the like may be formed as an intermediate layer as a pre-process. 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 .

Below, the Example of the sprayed film formed with the plasma spraying apparatus shown in FIG. 1 and the example of the porosity are shown. The following examples are all Y ₂ O ₃ sprayed films. The working gas was 80% argon, 15% helium, and 5% hydrogen. The working gas amount and output are the total of the three sets of anode and cathode.
[Example 1]

Working gas flow rate 180 liters per minute Output 100 kW / h
Powder supply 38g / min
Thermal sprayed film thickness 220μm
Porosity 1.0%
[Example 2]

Working gas flow rate 180 liters per minute Output 98KW / h
Powder supply 38g / min
Sprayed film thickness 200μm
Porosity 1.2%
Example 3

Working gas flow rate 180 liters per minute Output 94KW / h
Powder supply 38g / min
Sprayed film thickness 200μm
Porosity 1.8%
Example 4

Working gas flow rate 180 liters per minute Output 85KW / h
Powder supply 38g / min
Sprayed film thickness 200μm
Porosity 4.5%
Example 5

Working gas flow rate 180 liters per minute Output 90KW / h
Powder supply 38g / min
Sprayed film thickness 200μm
Porosity 2.9%
Example 6

Working gas flow rate 180 liters per minute Output 86KW / h
Powder supply 38g / min
Sprayed film thickness 200μm
Porosity 4.5%

From the above examples, it can be seen that according to the method of the present invention, a Y ₂ O ₃ sprayed film having a porosity of less than 5% can be formed.

Next, the method for measuring porosity in the present invention will be described.
FIG. 4 is a diagram schematically showing a cross-sectional view of the sprayed film in the first embodiment. The surface of the substrate 150 is roughened by sandblasting or the like as described above. In addition, since the molten particles adhere and solidify, the sprayed film 160 does not have a flat surface and has a shape rich in irregularities. FIG. 4 shows a cross section obtained by cutting the thermal spray film 160 along a plane perpendicular to the surface of the base material (inner member of the plasma processing container) 150.

  In practice, a test piece is prepared by cutting the thermal spray film 160 along a plane perpendicular to the surface of the substrate 150, embedded in a resin, polished on the surface, magnified in cross section with a microscope, and photographed with a digital camera. The digital image obtained in this way is binarized by image processing, whereby the same one as schematically shown in FIG. 4 can be obtained.

  The total number S of the pores 162 shown in FIG. 4 is obtained, and a number obtained by multiplying the number divided by the cross-sectional area A of the sprayed film 160 in the measurement target region by 100%, that is, a value obtained by the following equation:

(S / A) x 100%
Was the porosity of the sprayed film 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 expansion perspective view which looked at the converging device from the cathode side. It is the expansion perspective view which looked at the nozzle from the converging device side. It is the figure which showed typically sectional drawing of the sprayed film in Example 1. FIG. It is a figure which shows the structure of the conventional general plasma spraying apparatus.

Explanation of symbols

101 sprayed film a central axis of the anode 102 cathode 110 concentrator 120 nozzle 150 substrate 160 _Y 2 _{O 3}

Claims (1)

An intermediate layer is formed on the substrate surface, the surface of the intermediate layer is covered by a Y ₂ O ₃ sprayed coating by air plasma spraying (excluding the electron beam treatment or laser beam processed ones after deposition), the Y ₂ A member in a plasma processing container, wherein the porosity of the O ₃ sprayed coating is less than 5%.

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