JP2008248345A - Member for plasma treatment apparatus, and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sprayed coating having a high nitride content since formation of a sprayed coating of nitride having excellent characteristics on the surface of a member used for an apparatus using plasma such as a plasma treatment apparatus (a plasma etching apparatus, a plasma cleaning apparatus, an ashing apparatus) in the fabrication of a semiconductor or the like, is desired. <P>SOLUTION: Disclosed is a member for a plasma treatment apparatus in which the sprayed coating is formed at least on a part of its surface, the surfaces of the grains constituting the sprayed coating are coated with components melted by thermal spraying, and further, the ratio of nitride in the sprayed coating is 50 to <100% by weight. The member can be produced by forming the sprayed coating on the surface of a base material in the member using nitride powder with the average grain size of 1 to 10 μm coated with melting components such as silicon dioxide upon thermal spraying. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a member used in a plasma processing apparatus (plasma etching apparatus, plasma cleaning apparatus, ashing apparatus) or the like in the manufacture of a semiconductor or the like, and in particular, imparts the characteristics of nitride to the surface of the member as a sprayed film. Therefore, it relates to a material having a high nitride content.

Corrosive gases are frequently used for plasma etching in the manufacturing process of semiconductor elements and the like, and for cleaning of CVD apparatuses. For these corrosive gases, fluorine-based or chlorine-based gases are used. For example, CF ₄ , C ₂ F ₆ , C ₃ F ₈ , CHF ₃ / CF ₄ , SF ₆ or the like is used as the fluorine-based gas, and examples of the chlorine-based gas include Cl ₂ , BCl ₃ , CCl _4. Etc., and the use of HF, F ₂ and NF ₃ has also been proposed.

  As a member used for such a semiconductor manufacturing apparatus, oxide ceramics such as quartz and alumina, or metals such as aluminum and stainless steel are used. However, when the purity of these components is low, or when the metal elements of the components are elements related to semiconductor product contamination, particles are generated by reacting with corrosive gas, and impurity components and constituent elements are generated on the semiconductor wafer. Product contamination due to adhesion was a problem.

  As ceramics having physical properties different from such oxide ceramics, there are nitride ceramics. For example, aluminum nitride is often used for members such as electrostatic chucks in semiconductor manufacturing equipment because of its high thermal conductivity and high resistance to halogen gas and plasma, but nitride ceramics are complex. There are problems that it is difficult to create a member having a simple shape and that the manufacturing cost is high.

  Therefore, it is conceivable to create a member having a desired shape by spraying nitride ceramics on the substrate and forming a sprayed film on the surface thereof. However, in general, it has been difficult to form a dense nitride sprayed film using only nitride powder. This is thought to be because the melting point of nitride is high and it is oxidized and decomposed before being melted during thermal spraying (for example, aluminum nitride is oxidized and decomposed at about 2300 ° C.). As a technique for forming the nitride sprayed film, thermal spraying with a mixed powder of a nitride powder and a powder other than a nitride serving as a binder has been mainly used.

  Specifically, for example, a technique of forming a ceramic sprayed film containing zirconia on an undercoat of a silicon-based cermet by spraying a mixed powder of metal silicon, silicon nitride and silicon oxide (see Patent Document 1) Has been reported. However, in this silicon nitride mixed film, metal silicon, which is one of the components, is easily corroded by a corrosive gas or plasma, so that the sprayed film may be unevenly corroded and particles may be generated.

_Further, the mixed powder of _{Si 3 N 4, Al 2 O} 3, Y 2 O 3, which was prepared α silicon nitride mixture by plasma spraying has been reported (e.g., see Non-Patent Document 1). However, since this is not a sprayed film of silicon nitride alone, a large amount of impurities such as Al ₂ O ₃ and Y ₂ O ₃ may cause particles and metal contamination.

Furthermore, as for AlN, a sprayed film having a mixed composition of AlN and Al ₂ O ₃ has been reported (for example, see Non-Patent Document 2). However, the AlN abundance in this sprayed film is about 47%, and a film having a higher aluminum nitride content has been desired.

In addition to a thermal spraying method using a mixed powder of a nitride powder and a powder other than a nitride serving as a binder, aluminum nitride may be deposited by performing reactive thermal spraying of metal aluminum powder by plasma spraying containing N ₂ gas. Although proposed (for example, refer to Patent Document 2), since the density of the sprayed film formed by reactive spraying tends to be relatively low, further improvement in film quality is desired.

JP 2003-313077 A JP 2004-083929 A Y. Bao, D.C. T.A. Gawne, T .; Zhang “The Inflation of Matrix Phase Visibility on the Plasma-Spray Deposition of Silicon-Nitride Composite Coatings,” (Ed.) Moreau and B.M. Marple, Publicized by ASM International, Materials Park, Ohio, USA, 2003, 263 (2003) H. Yang, W. Luan, ST Tu “AlN / Al2O3 Composite Coating Deposited by Plasma Spray” Proceedings of the 1st Asian Thermal Conference, 41 (200)

  As described above, when using a member related to nitride ceramics in a process using plasma treatment in a manufacturing process of a semiconductor element or the like, (1) it is expensive and complicated to use a nitride bulk body. There is a problem that it is difficult to mold the shape. (2) If you try to use a molded product with nitride sprayed on its surface, binder components other than nitride contained in the sprayed material become impurities and adhere to the wafer. In addition, there are problems such as contamination of semiconductor products and reduction in yield due to the generation of particles, and further, if a sprayed film with a reduced amount of impurities other than nitride is formed by reactive spraying, It was necessary to further increase the density of the film.

  An object of the present invention is to provide a member for a plasma processing apparatus having a nitride sprayed film coated on its surface with a small amount of components other than impurities and nitride, and a method for producing the same.

  As a result of intensive investigations in view of the above situation, the present inventors used a nitride powder coated with a small amount of a binder component on the surface as a thermal spray raw material, and spraying this onto the member surface, The present inventors have found that it is possible to provide a member having a nitride sprayed film formed with less components other than impurities and nitrides, and have completed the present invention.

  That is, according to the present invention, a sprayed coating containing 50% or more and less than 100% by weight of nitride is formed on at least a part of a member surface, and particles constituting the sprayed coating are coated with a component that melts by spraying. The present invention relates to a member for a plasma processing apparatus.

  Hereinafter, the member of this invention is demonstrated in detail.

  The member of the present invention is formed by forming a sprayed film on at least a part of the surface of the member, the surface of the particles constituting the sprayed film is covered with a component that melts by spraying, and nitrides in the sprayed film It is related with the member for plasma processing apparatuses characterized by comprising 50% or more and less than 100% by weight ratio.

Examples of the member for a plasma processing apparatus of the present invention include a member used for a plasma etching apparatus and a cleaning apparatus. Various characteristics can be imparted to the members by providing the surface of these members with the thermal spray film defined in the present invention.
A more preferable nitride content is 60% or more.

  For example, by providing a thermal spray film of aluminum nitride on the surface, a member having high thermal conductivity and high resistance to plasma can be obtained, and application to an electrostatic chuck or the like is possible. At this time, if the ratio of the nitride in the sprayed film is less than 50%, the characteristics as a nitride cannot be sufficiently obtained.

  According to the present invention, since the surface of the particles constituting the sprayed film is covered with a component that melts by thermal spraying, nitride particles that are easily decomposed and oxidized without melting are connected to each other by the molten component. Although it is thought that the film quality of a material sprayed film improves, such an idea does not limit this invention at all. Further, since the molten component exists only on the surface of the nitride particle, there are few molten components that become impurities. Examples of the molten component include metal oxides such as silicon dioxide and aluminum oxide. Since the metal oxide is less decomposed during spraying and easily melts, the surface of the nitride particles can be covered as a molten layer.

  As the base material of the member that forms the sprayed film, the temperature of the base material becomes 100 ° C. or higher by thermal spraying, and therefore it is necessary that cracking, alteration, deformation, etc. do not occur due to this temperature rise. Examples thereof include metals such as aluminum alloys and stainless steel, heat resistant glasses such as quartz glass and borosilicate glass, ceramics such as alumina and mullite, and the like.

  About the thickness of the nitride sprayed film of this member for plasma processing apparatuses, 1-1000 micrometers, especially 10-500 micrometers are preferable. If the nitride sprayed film is thinner than 1 μm, the function as a nitride cannot be obtained sufficiently. When the film thickness exceeds 1000 μm, the sprayed film tends to peel off due to the difference in thermal expansion coefficient between the nitride sprayed film and the substrate. The film thickness of the nitride sprayed film can be known by observing the cross section of the member with a microscope or measuring the thickness of the member before and after spraying.

  The surface roughness (arithmetic mean roughness) Ra of the nitride sprayed film of the plasma processing apparatus member is preferably 10 μm or less. If the surface roughness Ra is rougher than 10 μm, the plasma may concentrate on a part of the sprayed film during the plasma treatment, and a part of the sprayed film may be taken out to generate particles. The surface roughness (arithmetic average roughness) Ra as used in the present invention indicates a value measured according to JIS B 0601 (1994).

  Next, the manufacturing method of the member of this invention is demonstrated.

  The nitride sprayed film of the plasma processing apparatus member of the present invention is produced, for example, by using a nitride powder coated with a component that melts by spraying on the surface of the nitride powder as a raw material powder and spraying this raw material powder. be able to. By using such a raw material powder, it is considered that the coating component on the powder surface reacts and melts during thermal spraying, thereby connecting the normally non-melted nitride powders.

  Such a coating component may be any component that reacts and melts during thermal spraying, but is preferably a metal oxide, and specific examples thereof include silicon dioxide and aluminum oxide.

  The amount of the coating component on the nitride powder surface is not particularly specified, but is preferably 0.5 to 20% of the raw material powder weight. When the amount of the coating component is less than 0.5%, the role of connecting the nitrides is small, and it is difficult for the sprayed film to be deposited or the film quality may be deteriorated. On the other hand, when the amount of the coating component is more than 20%, the sprayed film formed on the member cannot sufficiently obtain the characteristics as a nitride.

  Examples of the powder in which the coating component is coated on the surface of the nitride powder include commercially available aluminum nitride powder coated with silicon dioxide. Although it is not certain by spraying aluminum nitride powder coated with silicon dioxide, a composite oxide of aluminum and silicon is generated as a reaction product due to the high temperature during spraying, and this composite oxide connects aluminum nitride to each other. It is considered to be a role.

  As another method for forming the sprayed film of the present invention on the substrate surface, a nitride powder slurry in which a metal such as a metal alkoxide is melted is put into a spray gun in a slurry state, and at the same time a metal oxide is generated during spraying. A method of forming a nitride sprayed film is also included.

  The average particle size of the thermal spray raw material powder used in the present invention is preferably 1 to 10 μm, more preferably 2.5 to 8 μm, as the average primary particle size. When powder having an average particle size larger than 10 μm is used, a nitride powder having a high melting point may not melt and a sprayed film may not be deposited. On the other hand, if the average particle size is less than 1 μm, the sprayed powder cannot be stably supplied to the spray gun, and it may be difficult to make the sprayed film uniform. In general, ceramics have a high melting point and low thermal conductivity, so it is difficult to obtain a uniform molten state, so finer-grained powder is used compared to metal powder. It is difficult to throw into the position, and problems such as troubles are likely to occur during feeding. Therefore, with normal plasma, powder with an average particle size of 30-50 μm and high-power high-efficiency water-stabilized plasma of about 100 μm (For example, see Yukio Oki et al., Japan Thermal Spray Association, “Introduction to Thermal Spray Technology” (2006), pages 191 to 192). On the other hand, the average particle diameter of the raw material powder used in the present invention is considerably finer than before.

  In the present invention, it is preferable that the temperature of the substrate surface is preheated and sprayed in advance when the sprayed film is formed on the member surface. Preheating the surface of the base material in advance is effective for preventing the base material from cracking due to heat shock and obtaining a thermal sprayed film having high adhesion. The preheating temperature varies depending on the type of base material to be used. For example, the range of 50 to 800 ° C. for a quartz glass base, 50 to 500 ° C. for a metal base, and 50 to 200 ° C. for a resin base is preferable. The preheating temperature can be measured with a thermocouple from the back surface of the substrate or with a non-contact radiation thermometer.

  As a preheating method, the base material may be heated by an external heater, or the thermal spray frame may be irradiated to the base material without supplying the raw material.

  Furthermore, it is preferable that the base material surface of a member is 1-15 micrometers as surface roughness Ra. If the surface roughness Ra is less than 1 μm, the substrate and the sprayed coating may be easily peeled off, and it may be difficult to uniformly coat the corrosion-resistant glass sprayed coating on the substrate. On the other hand, when the surface roughness Ra of the substrate surface exceeds 15 μm, the surface roughness Ra of the sprayed film exceeds 10 μm, so that a part of the sprayed film may be removed during etching to generate particles.

  As a method of setting the surface roughness Ra of the substrate surface to 1 to 15 μm, a method of spraying a sprayed film having such a surface roughness on the substrate in advance, a method of blasting the substrate itself, or a blasting treatment and hydrofluoric acid The method etc. which perform the chemical etching by etc. collectively can be illustrated.

  The thermal spray film forming method used in the present invention is preferably plasma spraying. In particular, it is preferable to perform thermal spraying with plasma having a high output and a high gas flow rate. Examples of the high output include plasma of 50 kw or more, and the high gas flow rate of 120 SLM (Standard Litter Per Minute) or more. Although the effect of increasing the output and gas flow rate is not clear, it is considered that increasing the gas flow rate shortens the time that the nitride powder stays in the plasma and suppresses oxidation and decomposition. Normally, when the gas flow rate is increased, the sprayed film is difficult to deposit because the powder does not melt, but it is considered that a molten layer is formed on the powder surface by increasing the output of the plasma.

  When plasma spraying is used in forming the nitride sprayed film on the surface of the base material, the base material temperature is preferably 100 to 800 ° C. when the base material is glass or ceramics. If the substrate temperature is lower than 100 ° C., the sprayed powder will not melt sufficiently, so the sprayed film may not adhere. If the substrate temperature is higher than 800 ° C., the difference in thermal expansion coefficient between the substrate and the sprayed film In some cases, cracks occur in the thermal sprayed film, resulting in a decrease in corrosion resistance, and the disappearance of nitrogen may occur due to the decomposition of the nitride as the thermal spray raw material. When the substrate is a metal material, the substrate temperature is preferably 50 to 400 ° C. Furthermore, when the substrate is a resin, the substrate temperature is preferably 50 to 300 ° C., although it depends on the type of resin.

In the production method of the present invention, the supply of the raw material powder to the spray gun is preferably a method of supplying the inside of the plasma. As a spray gun of a system for supplying powder into the plasma, for example, trade name “Axial III” manufactured by Northwest Mettech is mentioned. In this spray gun, since the three plasma electrodes are arranged at intervals of 120 degrees around the spray powder supply nozzle, since the spray powder is introduced into the plasma center, the plasma is N ₂ or H _2, etc. In the case of a reducing atmosphere, the thermal spraying powder can also prevent oxidation due to contact with oxygen. FIG. 1 shows a conceptual diagram of a plasma spraying apparatus of a powder supply system into the plasma. In the plasma spraying apparatus, a plasma jet formed by the plasma gas 12 flowing between the three anodes 11 and the cathode 10 being arc-discharged is collected by a convergence 14. Using the assembled plasma jet as a heat source, the sprayed powder 13 is introduced into the center and melted, and the melted sprayed powder collides with the base material 16 at the flow rate of the plasma gas.

In the production method of the present invention, an inert gas such as N ₂ or Ar or a reducing gas such as H ₂ can be used as the spray gas in forming the sprayed film. If oxygen is present in the spraying gas, the nitrogen in the spraying raw material powder is oxidized during the spraying, and the nitrogen content of the spraying film is greatly reduced, so the oxygen concentration in the spraying gas is preferably as low as possible, When spraying nitride powder in it, by increasing the power of spraying, a small amount of the surface of the sprayed powder that flies at high temperature and the sprayed powder after deposition changes to oxide, and this oxide is converted into nitride. It may be a role to connect each other. The presence and amount of nitride in the sprayed film can be confirmed on the surface of the sprayed film by X-ray diffraction, and the amount of nitrogen in the sprayed film can be measured by EPMA.

  In the production method of the present invention, the spray distance, which is the distance between the tip of the spray gun and the substrate under normal pressure, is preferably 40 to 150 mm. If the spraying distance exceeds 150 mm, the sprayed powder will be cooled until it adheres to the substrate, and the sprayed film may not be deposited on the substrate. If the spraying distance is shorter than 40 mm, the temperature of both the base material and the sprayed film will rise. Therefore, the cause of cracking of the sprayed film and the base material and the nitrogen content in the sprayed film may be reduced.

  Furthermore, although the spraying power to be charged when spraying the spray frame on the base material varies depending on the apparatus to be used, for example, in the case of a plasma spraying apparatus as shown in FIG. 1, 50 kW or more can be exemplified as the spraying power.

  The member for a plasma processing apparatus of the present invention is used for a plasma processing apparatus (plasma etching apparatus, plasma cleaning apparatus, ashing apparatus) in the manufacture of semiconductors and the like by imparting the excellent characteristics of nitride to the surface of the member by thermal spraying. In this case, it is possible to process many wafers in a short time because the contamination of the semiconductor product is reduced and an electrostatic chuck having high thermal conductivity can be formed.

  The present invention will be described in detail based on examples, but the present invention is not limited to these examples.

Example 1
Aluminum nitride powder FLC manufactured by Toyo Aluminum Co., Ltd. (average particle size 4.2 μm, aluminum nitride surface coated with 1.3 wt% silicon dioxide) on quartz glass substrate using Northwest Mettech Axial III thermal spraying device Thermal spraying was performed. As a fine powder supply, CPF-2HP manufactured by Thermico Corporation was used.

  As the quartz glass substrate used for thermal spraying, a quartz glass having a surface roughness Ra of 5 μm by blasting and treated with 5% hydrofluoric acid for 2 hours to have a surface roughness Ra of 8 μm was used.

Preheating at this time, as the spraying conditions, firstly, at atmospheric pressure, spraying distance 100 mm, the plasma power 140kW, _{N 2} and _{H 2} gas together flow 280SLM as spraying gas, the powder without supplying, the substrate preheating Went. Next, the aluminum nitride powder was flowed at a supply rate of 10 g / min, and 5-pass spraying was performed while moving the spray gun at a speed of 400 mm / sec. The conditions of spraying distance, plasma power, and spraying gas during spraying are the same as those for preheating.

The deposited thermal spray film has a film thickness of 100 μm and a surface roughness Ra of 9 μm. In the analysis of the constituent phases by the X-ray diffraction method, hexagonal aluminum nitride and ε-alumina were observed, and the hexagonal aluminum nitride 100 surface and ε The nitride content calculated from the peak area of the X-ray diffraction of the alumina 034 surface was 66% of the crystal phase of hexagonal aluminum nitride.

Example 2
Aluminum nitride powder FLC manufactured by Toyo Aluminum Co., Ltd. (average particle size 4.2 μm, aluminum nitride surface coated with 1.3 wt% silicon dioxide) on quartz glass substrate using Northwest Mettech Axial III thermal spraying device Thermal spraying was performed. As a fine powder supply, CPF-2HP manufactured by Thermico Corporation was used.

  As the quartz glass substrate used for thermal spraying, a quartz glass having a surface roughness Ra of 5 μm by blasting and treated with 5% hydrofluoric acid for 2 hours to have a surface roughness Ra of 8 μm was used.

Preheating at this time, as the spraying conditions, firstly, at atmospheric pressure, spraying distance 100 mm, the plasma power 145kW, _{N 2} and _{H 2} gas together flow 230SLM as spraying gas, the powder without supplying, the substrate preheating Went. Next, the aluminum nitride powder was flowed at a supply rate of 10 g / min, and 5-pass spraying was performed while moving the spray gun at a speed of 400 mm / sec. The conditions of spraying distance, plasma power, and spraying gas during spraying are the same as those for preheating.
The deposited thermal spray film had a film thickness of 100 μm and a surface roughness Ra of 9 μm. In the analysis of the constituent phases by the X-ray diffraction method, crystal phases of hexagonal aluminum nitride, ε alumina, and α alumina were observed. The nitride content calculated from the X-ray diffraction peak areas of the hexagonal aluminum nitride 100 surface, the ε alumina 034 surface, and the α alumina 104 surface was 51% hexagonal aluminum nitride. Further, the cross section of the sprayed film was observed with a scanning electron microscope (SEM) (FIG. 2) and the distribution of Si atoms was observed with EPMA (FIG. 3). In the EPMA image of the Si atom distribution, the bright part has a large proportion of Si atoms, but the periphery of the particle (grain boundary) is bright, indicating that there is a lot of Si, and the periphery of the particle is covered with a SiO ₂ compound. It looked like it was.

Comparative Example 1
For silicon nitride powder (average particle size 15 μm), the same substrate as in Example 1 was preheated and sprayed in the same manner as in Example 1, but the sprayed film did not adhere.

It is a figure which shows an example of a plasma spraying apparatus. The figure which measured the cross section of the produced aluminum nitride sprayed film by SEM is shown. It is a figure which shows the distribution state of Si which measured the cross section of the produced aluminum nitride sprayed film by EPMA.

Explanation of symbols

10: Cathode 11: Anode 12: Plasma gas 13: Thermal spray powder (supply port)
14: Convergence 15: Thermal spray distance 16: Base material 17: Thermal spray film 18: Power supply

Claims (11)

A sprayed coating containing 50% or more and less than 100% by weight of nitride is formed on at least a part of the surface of the member, and the particles constituting the sprayed coating are covered with a component that melts by spraying. A member for a plasma processing apparatus. The member for a plasma processing apparatus according to claim 1, wherein the nitride is aluminum nitride. The member for a plasma processing apparatus according to claim 1, wherein the component melted by thermal spraying is a metal oxide. The member for a plasma processing apparatus according to claim 3, wherein the component melted by thermal spraying is silicon dioxide. A nitride powder coated with a component that is melted by thermal spraying is used as a raw material powder, and sprayed onto the substrate surface by plasma spraying to form a thermal sprayed film. The thermal sprayed film has a nitride ratio of 50% to 100% by weight. The manufacturing method of the member for plasma processing apparatuses characterized by the particle | grains which contain less and comprise the thermal spraying film | membrane being coat | covered with the component fuse | melted by thermal spraying. 6. The method for producing a member for a plasma processing apparatus according to claim 5, wherein a raw material powder having an average particle diameter of 1 to 10 [mu] m is used. 6. The method for manufacturing a member for a plasma processing apparatus according to claim 5, wherein the raw material powder is supplied in the direction of the center of the plasma. The method for producing a member for a plasma processing apparatus according to claim 5, wherein the component melted by thermal spraying is a metal oxide. The method for producing a member for a plasma processing apparatus according to claim 5, wherein the metal oxide is silicon dioxide. The method for producing a member for a plasma processing apparatus according to claim 5, wherein the plasma output during plasma spraying is 50 kW or more. The method for manufacturing a member for a plasma processing apparatus according to claim 5, wherein a gas flow rate when performing plasma spraying is 120 SLM or more.

Images