JP2006307298A - Nitride film and film-forming method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nitride film which has a high nitride content and is thick and dense, and to provide a method for easily forming the nitride film on a substrate. <P>SOLUTION: The method for forming the nitride film includes thermal-spraying a mixture substantially composed of a powder of a metallic element or a non-metallic element, which is a raw material for thermal spraying, and a powder of the nitride of the element. The method inhibits a nitriding reaction between element powders and the coagulation of the powders due to consequent crystal growth, by the existence of the nitride powder, and as a result, can easily provide the dense and thick nitride film. The film-forming method also includes previously mixing the nitride powder, thereby increases a nitride content in the film and simultaneously relatively decreases a ratio of an unreacted element powder, and consequently provides the thick film with the high nitride content. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a thick and dense nitride film having a high nitride content, and a film forming method capable of easily forming such a nitride film on a substrate.

  Nitride is used in various fields because of various excellent characteristics. For example, aluminum nitride has a thermal conductivity that is about 10 times better than that of alumina, so that it is conventionally used for a soaking plate of a heater or a heat dissipation board in a semiconductor manufacturing apparatus.

  In addition, since this aluminum nitride has insulating properties and high corrosion resistance against halogen-based plasma, for example, in a semiconductor manufacturing apparatus as described in JP-A-05-251365 (Patent Document 1). Can also be used as a plasma resistant member.

  On the other hand, nitrides other than aluminum nitride also have some excellent characteristics. For example, silicon nitride is excellent in terms of thermal shock resistance, titanium nitride is excellent in terms of wear resistance, and iron nitride is excellent in terms of magnetic properties.

  In recent years, high nitride content (high nitride purity) and durability on base materials such as metals and ceramics for the purpose of more widely using nitrides having excellent properties as described above In view of the above, there is an increasing demand for a technique for forming (forming) a thick nitride film.

  Generally, a PVD method (physical vapor deposition method) or a CVD method (chemical vapor deposition method) is used to obtain a nitride film having a high nitride purity. However, these methods can obtain a nitride film having a high nitride purity, but a thin film is obtained, which is insufficient in terms of durability.

  Thermal spraying is known as one of the methods suitable for forming a thick film on a substrate such as metal or ceramics at high speed. This thermal spraying method is a method of forming a film by melting a thermal spray raw material and spraying and depositing the melted thermal spray raw material on a substrate at a high speed.

  However, when the thermal spraying method is applied to form a nitride film, most of the nitrides have a decomposition temperature lower than the melting point, so that the decomposition of the nitride occurs during the thermal spraying, resulting in the formation of the nitride film. There was a general problem that was difficult.

  Thus, several techniques have been proposed to solve such problems. For example, in Japanese Patent Laid-Open No. 06-49617 (Patent Document 2), an oxide that functions as a binding aid (binder) is nitrided. It is described that a film containing silicon nitride can be formed by a thermal spraying method using a mixture of silicon as a thermal spraying raw material.

Japanese Patent Laid-Open No. 2004-83929 (Patent Document 3) discloses that an aluminum nitride film is formed on a substrate by supplying a thermal spray raw material into aluminum powder and supplying the aluminum powder into a thermal plasma containing nitrogen. How to do is described.
JP 05-251365 A Japanese Patent Laid-Open No. 06-49617 JP 2004-83929 A

  However, since the sprayed film described in Patent Document 2 contains an additive such as an oxide in the spraying raw material, the nitride (silicon nitride) content in the film is naturally low. Therefore, under a situation where a high nitride content is required, even if a thick film is obtained, such a low nitride content is a serious problem.

  On the other hand, when an aluminum nitride film is formed by the method described in Patent Document 3, a nitride film having a relatively high nitride (aluminum nitride) content is obtained, but unreacted aluminum is contained in the film. In order to mix in, there was a problem that the height of the nitride content was still insufficient.

  Further, when the method described in Patent Document 3 is used, there is a problem that the aluminum powder in the thermal plasma containing nitrogen easily forms aggregates due to crystal growth accompanying the nitriding reaction. Therefore, although the nitride film obtained by this method is a thick film, it is a rough film that can be confirmed to form aggregates at a glance, and has a problem that it is peeled off even by slight friction.

  The present invention has been made to solve the above-mentioned problems, and has a high nitride content and a thick and dense nitride film, and such a nitride film can be easily formed on a substrate. An object of the present invention is to provide a film forming method that can be formed.

  In order to achieve this object, the nitride film according to claim 1 is a thermal spraying method in which a mixture substantially composed of a powder of a metal element or a nonmetallic element and a nitride powder of the element is used as a thermal spraying raw material. The film thickness is 1 μm or more and 3 mm or less, and the nitride content is 25 mol% (mol%) or more and 100 mol% or less.

  In the claims and the following description, the term “nitride film” intends a film containing nitride as a main component, and is not intended to be a film formed only of nitride. .

  The film forming method according to claim 2 is a method of forming a nitride film containing a nitride of a metal or a nonmetallic element on a substrate by a thermal spraying method, and in this method, thermal plasma containing nitrogen is generated. In the thermal plasma containing nitrogen, the mixture is sprayed by supplying a mixture substantially composed of a powder of a metal element or a non-metal element and a nitride powder of the element as a spraying raw material, The nitride film is formed on a substrate.

  The film forming method according to claim 3 is the film forming method according to claim 2, wherein the thermal spraying is performed while bringing thermal plasma into contact with the surface of the nitride film formed on the substrate.

  The film forming method according to claim 4 is the film forming method according to claim 3, wherein a temperature of a contact portion between the thermal plasma and the surface of the nitride film is equal to or lower than a decomposition temperature of the nitride or less than a decomposition temperature. is there.

  The film forming method according to claim 5 is the film forming method according to claim 3 or 4, wherein a temperature of a contact portion between the thermal plasma and the surface of the nitride film is equal to or higher than a melting point of the metal element or the nonmetal element. Or the melting point is exceeded.

  A film forming method according to a sixth aspect is the film forming method according to any one of the second to fifth aspects, wherein the nitride film formed on the substrate is further brought into contact with the thermal plasma.

  The film formation method according to claim 7 is the film formation method according to any one of claims 2 to 6, wherein a particle size of the powder of the metal element or the nonmetal element and the nitride powder of the element is 0.00. 1 μm or more and 200 μm or less.

  According to the nitride film according to claim 1, since a mixture substantially composed of a powder of a metal element or a non-metal element and a nitride powder of the element is used as a thermal spraying raw material for the thermal spraying method, the metal element In addition, the film is dense because the nonmetallic element powder is prevented from agglomerating due to crystal growth accompanying the nitriding reaction, and the contamination of the unreacted metallic element or nonmetallic element is suppressed in the film. There is an effect that the nitride content is high.

  Further, since the film thickness is 1 μm or more, there is an effect that the durability against wear and the like is excellent. On the other hand, since the film thickness is 3 mm or less, there is an effect that demand is high and economical in the market.

  Furthermore, since it is a film formed by a thermal spraying method, there is an effect that a film having a film thickness of 1 μm or more which is excellent in durability against abrasion or the like can be obtained.

  In addition, since the nitride content in the film is as high as 25 mol% or more and 100 mol% or less, there is an effect that the excellent characteristics exhibited by the nitride can be effectively expressed.

  According to the film forming method of claim 2, a mixture substantially composed of a powder of a metal element or a nonmetal element which is a spraying raw material and a nitride powder of the element is sprayed, whereby the base material is sprayed. A nitride film is formed thereon.

  Therefore, a powder of a metal element or a non-metal element (hereinafter sometimes referred to as “element powder” if necessary) and a nitride powder of the element (hereinafter referred to as “nitride powder” if necessary) Therefore, the presence of the nitride powder suppresses the formation of aggregates due to crystal growth associated with the nitridation reaction of the element powder. There is an effect that a thick film can be easily obtained.

  In addition, by mixing the nitride powder in advance, the nitride content can be increased and the proportion of the relatively unreacted element powder can be reduced. There is an effect that a film can be obtained.

  In addition to the effect of the film forming method according to claim 2, the film forming method according to claim 3 performs thermal spraying while bringing thermal plasma into contact with the surface of the nitride film formed on the substrate. The nitridation of elements contained in the nitride film formed on the substrate is promoted, and as a result, the nitride content in the nitride film is increased and the denseness can be improved. is there.

  According to the film forming method of claim 4, in addition to the effect of the film forming method of claim 3, the temperature of the contact portion between the thermal plasma and the surface of the nitride film is equal to or lower than the decomposition temperature of the nitride. Alternatively, since the temperature is lower than the decomposition temperature, decomposition of the nitride generated by the nitriding reaction of the element powder is suppressed, and as a result, a dense nitride film having a high nitride content can be formed on the substrate. effective. Further, when the surface of the formed nitride film is further brought into contact with thermal plasma, there is an effect that the decomposition of the nitride in the film can be suppressed.

  According to the film forming method of claim 5, in addition to the effect of the film forming method of claim 3 or 4, the temperature is included in the thermal spray raw material at the contact portion between the thermal plasma and the surface of the nitride film. Therefore, the element powder is reliably melted on the surface of the base material or the surface of the nitride film. As a result, the nitriding reaction can surely proceed, so that there is an effect that a dense nitride film having a high nitride content can be obtained. Further, when the surface of the formed nitride film is further brought into contact with thermal plasma, there is an effect that nitridation of an unreacted metal element or nonmetal element remaining in the film can be promoted.

  According to the film-forming method of Claim 6, in addition to the effect which the film-forming method in any one of Claim 2 to 5 shows, the nitride film formed on the base material further includes thermal plasma and Since contact is made, the unreacted metal element or nonmetal element remaining in the film is nitrided, and as a result, there is an effect that a nitride film having a higher nitride content can be obtained.

  According to the film-forming method of Claim 7, in addition to the effect which the film-forming method in any one of Claim 2 to 6 shows, element powder (metallic element or non-metallic element) contained in the mixture which is a thermal spray raw material ) And nitride powder (nitride powder of the element) are 200 μm or less, so that the reactivity with thermal plasma is high, and as a result, the nitride content is high and the dense nitride film There is an effect that can be obtained.

  On the other hand, since the particle size of the element powder and nitride powder is 0.1 μm or more, the fluidity of the thermal spray raw material is excellent, so even if a simple thermal spray raw material feeder is used, a nitride film is easily formed. There is an effect that can be made.

The present invention is described in detail below.
[Nitride film]
The nitride film of the present invention is a film obtained by a thermal spraying method (especially a plasma spraying method). In the PVD method or the CVD method generally used for obtaining a nitride film having a high nitride content, It has a thick film thickness that could not be obtained.

  Here, the film thickness of the nitride film of the present invention is preferably about 1 μm or more and about 3 mm or less, and more preferably about 100 μm or more and about 1 mm or less. If the thickness of the nitride film is less than about 1 μm, the film is thin and durability against abrasion or the like is insufficient. On the other hand, a nitride film having a film thickness exceeding about 3 mm is not generally required and is not economical in the technical field using the nitride film of the present invention.

  In addition, the nitride film of the present invention uses a mixture substantially composed of a powder of a metal element or a non-metal element and a nitride powder of the element in a thermal spraying method, and the details will be described later. However, when the spraying raw material is only element powder (aluminum powder) (the method of Patent Document 3), it has a denseness that cannot be obtained. The nitride film of the present invention does not particularly limit the density value for defining the density, but is preferably a film that is dense enough not to have vacancies. It is more preferable that the film does not have.

  Although details will be described later, the nitride film of the present invention is a nitride in order to use a mixture substantially composed of a powder of a metal element or a non-metal element and a powder of a nitride of the element as a thermal spraying raw material. High content.

  Here, in the nitride film of the present invention, the nitride content is preferably not less than about 25 mol% and not more than about 100 mol%, whereby excellent characteristics of the nitride contained in the film (for example, In the case of aluminum nitride, thermal conductivity, insulation and corrosion resistance can be effectively utilized. A more preferable nitride content is about 40 mol or more and about 100 mol% or less, and still more preferably about 90 mol or more and about 100 mol% or less.

  Examples of the nitride constituting the nitride film of the present invention include aluminum nitride, titanium nitride, chromium nitride, silicon nitride, and iron nitride. When the nitride film of the present invention is an aluminum nitride film, for example, it is substantially composed of an aluminum powder as a metal element powder and an aluminum nitride powder that is a nitride powder of the element powder. This mixture will be used as a thermal spray raw material. On the other hand, for example, when the nitride film of the present invention is a silicon nitride film, it is substantially composed of a silicon powder as a nonmetallic element powder and a silicon nitride powder that is a nitride powder of the element powder. The resulting mixture is used as a thermal spray raw material.

  In addition, components other than nitride in the nitride film of the present invention are only constituent elements. That is, the nitride film of the present invention is a film containing only a nitride generated by a reaction between a thermal spraying raw material and reactive plasma and a component derived from the thermal spraying raw material (such as a metal element or a nonmetallic element itself or its oxide). For example, it is a film that does not contain a different component due to an additive such as a binding aid contained in the sprayed film described in Patent Document 2. As a result, since the nitride content in the nitride film of the present invention can be increased, the excellent characteristics of the nitride contained in the film can be effectively utilized.

[Film formation method]
The nitride film forming method of the present invention is a method of forming a nitride film on a substrate using a thermal spraying method using thermal plasma. Here, the film forming method of the present invention will be described with reference to FIGS.

  FIG. 1 is a schematic view showing an apparatus 100 for performing plasma spraying of a thermal spray material on a substrate 101 under reduced pressure as an example of an apparatus for forming a nitride film of the present invention on a substrate.

  As shown in FIG. 1, the apparatus 100 is installed adjacent to the vacuum chamber 103 in which the base material holder 102 etc. which hold | maintain the base material 101 etc. were installed in the inside of the vacuum chamber 103, and in the inside. It comprises a quartz tube 113 that generates thermal plasma 104.

  A plasma gas line 109 a is communicated with the quartz tube 113, and a plasma gas 109 (to be described later) serving as a generation source of the thermal plasma 104 is introduced into the quartz tube 113 through the plasma gas line 109 a.

  Here, a high frequency coil 110 is installed around the quartz tube 113, and thermal plasma 104 is generated from the plasma gas 109 introduced into the quartz tube 113 by applying a high frequency to the high frequency coil 110.

  Further, a sheath gas line 108 a is communicated with the quartz tube 113, and a sheath gas 108 such as argon gas for protecting the quartz tube 113 when the thermal plasma 104 is generated is introduced through the sheath gas line. .

  Further, a thermal spray raw material supply line 112 b is communicated with the quartz tube 113. At the other end of the thermal spray raw material supply line 112b, a thermal spray raw material feeder 111 containing a thermal spray raw material (not shown: one corresponding to the thermal spray raw material M in FIG. 2 described later) is installed. By introducing the carrier gas 112 into the thermal spray raw material supplier 111 through the introduction pipe 112a, the thermal spray raw material (not shown) is supplied to the quartz tube 113 via the thermal spray raw material supply line 112b.

  The thermal spray raw material supplied to the quartz tube 113a is melted by the thermal plasma 104 and sprayed onto the base material 101 held on the base material holder 102 installed in the vacuum chamber 103 by the air flow of the thermal plasma 104, As a result, in the present invention, a sprayed film 116 that is a nitride film (hereinafter, may be referred to as “nitride film 116” if necessary) is formed on the substrate 101.

  Since the apparatus 100 shown in FIG. 1 is an apparatus that performs plasma spraying under reduced pressure as described above, a rotary pump 107 that reduces the pressure inside the vacuum chamber 103 is connected to the apparatus 100.

  Here, as a pressure condition in the low-pressure plasma spraying performed in the apparatus 100, the pressure in the apparatus 100 is reduced to 0.5 Torr or less by the rotary pump 107, and then the plasma gas 109 and the sheath gas 108 are introduced into the apparatus 100. For example, the sprayed film 100 is formed at a pressure of 20 to 150 Torr.

  In addition, the pressure conditions in the plasma spraying for obtaining the nitride film of the present invention are not particularly limited, and may be the above-described reduced pressure plasma spraying with reference to FIG. 1, and then refer to FIG. However, it may be plasma spraying at normal pressure (atmospheric pressure) described below or pressurized plasma spraying.

  FIG. 2 is a schematic view showing an apparatus 200 for performing plasma spraying of a thermal spray material on the base material 25 at normal pressure (atmospheric pressure) as another example of the apparatus for forming the nitride film of the present invention on the base material. is there. In the apparatus 200 shown in FIG. 2, the same parts as those of the apparatus 100 (see FIG. 1) described above are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 2, the apparatus 200 includes a cathode 20, an anode 21, and a power supply 27 for applying a voltage between the cathode 20 and the anode 21 as a part for generating thermal plasma at normal pressure. , A plasma gas line 109a for supplying the plasma gas 109, and a carrier gas (not shown) corresponding to the carrier gas 112 in FIG. 1 (corresponding to the raw material supplier 111 in FIG. 1). And a thermal spray raw material supply line 112b for supplying the thermal spray raw material M from the one) and a base material holder (not shown) for holding the base material 25.

  In the apparatus 200, a plasma gas 109, which will be described later, which is a generation source of the thermal plasma 104, is introduced through a plasma gas line 109 a at normal pressure, and a voltage is applied between the cathode 20 and the anode 21 to generate a direct current arc. The thermal plasma 104 is generated.

  In this apparatus 200, the method of generating the thermal plasma 104 is a direct current arc. On the other hand, in the apparatus 100 described above with reference to FIG. 1, the thermal plasma 104 is generated by a high frequency. As described above, the generation method of the thermal plasma 104 is not particularly limited, and may be a direct current arc that is a generation method of the thermal plasma 104 in the apparatus 200 or a generation method of the thermal plasma 104 in the apparatus 100 (see FIG. 1). In addition to a certain high frequency, an AC arc or the like can be used.

  While the thermal plasma 104 is generated as described above, when the thermal spray raw material M is supplied from the thermal spray raw material supply line 112b, the thermal spray raw material M melted by the thermal plasma 104 is sprayed onto the substrate 101, and as a result, In the present invention, a sprayed film 116 (nitride film 116) that is a nitride film is formed on the substrate 101.

  Here, the thermal spray raw material (thermal spray raw material M) for obtaining the nitride film of the present invention is a mixture substantially composed of a powder of a metallic element or a nonmetallic element and a nitride of the element. Examples of the metal element or nonmetal element powder that can be used to obtain the nitride film of the present invention include powders of aluminum, titanium, chromium, silicon, iron, and the like.

  On the other hand, as a powder of a nitride of a metal element or a nonmetal element, a powder of aluminum nitride, titanium nitride, chromium nitride, silicon nitride, iron nitride, or the like, which is a nitride of the elements listed above, can be used.

  As a thermal spraying raw material, the nitride content of the element is previously mixed with the element powder, so that the nitride content can be increased and the ratio of the relatively unreacted element powder can be reduced. A nitride film having a high nitride content can be obtained.

  In addition, the presence of the nitride powder suppresses aggregation due to crystal growth accompanying the nitriding reaction of the element powder during spraying, so that a dense nitride film 116 can be obtained. In addition, according to the film forming method of the present invention, a dense film can be easily formed as compared with a conventional method using only aluminum powder as a thermal spray raw material (method described in Patent Document 3). .

  Note that the preferable mixing ratio of the element powder and the nitride powder in the mixture to be the spraying raw material varies depending on various factors such as the flow rate of the plasma gas 109 and the supply power, but a wide range of mixing ratios (for example, Element powder: nitride powder (weight ratio) = about 2: about 8 to about 8: about 2), a dense thick film having a high nitride content can be formed.

  As a mixing method of the element powder and the nitride powder, a simple mixing method in which two kinds of powders are put in one container and simply mixed, or a mechanical mixing method such as a mechanical alloying method can be used. . Here, the simple mixing has an advantage that the mixing is easy, and the mechanical mixing has an advantage that the sprayed raw material can be easily supplied because the powder is rounded and rounded. In particular, mixing by the mechanical alloying method is preferable because two kinds of powders having completely different specific gravity and melting point can be mixed uniformly.

  In the film forming method of the present invention, the particle sizes of the element powder and the nitride powder in the mixture that is the thermal spraying raw material are preferably about 0.1 μm or more and about 200 μm or less, and about 1 μm or more and about 200 μm. The following is more preferable. The average particle diameter can be used as the “particle diameter”, and in this case, the particle diameter can be measured by a general light transmission type particle size distribution measuring apparatus.

  If the particle size of the element powder and the nitride powder is less than about 0.1 μm, it is difficult to supply the sprayed material to the apparatus 100 even if the structure of the sprayed material supply device 111 is devised. The formation of 116 becomes impossible. On the other hand, when the particle size of the element powder and the nitride powder exceeds about 200 μm, the reactivity between the thermal spray raw material and the thermal plasma 104 is deteriorated. As a result, the nitride content is lowered and a coarse nitride film is formed. Will be.

  Here, it is preferable that the supply rate when supplying the thermal spray raw material to the apparatus 100 (quartz tube 113) is constant. By making the supply rate of the thermal spray raw material constant, the nitridation reactivity of the element powder in the thermal plasma can be made uniform, and as a result, a dense nitride film 116 can be formed and nitriding with a uniform thickness can be performed. A material film 116 can be formed.

  The substrate 101 covered with the nitride film 116 by the film forming method of the present invention is not particularly limited, and is a metal substrate such as stainless steel or carbon steel, a graphite substrate, a quartz substrate, or a ceramic. Various base materials, such as a base material, can be used. In order to improve the adhesion of the base material 101 to the nitride film 116 formed by the film forming method of the present invention, it is preferable to roughen the surface in advance by a blast method or the like before spraying.

  In the film forming method of the present invention, since the elemental powder is subjected to the nitriding reaction in the thermal plasma 104, the thermal plasma 104 may contain a nitrogen atom-containing gas (for example, nitrogen gas or ammonium gas). It is essential. Therefore, the plasma gas 109 contains at least a nitrogen atom-containing gas such as nitrogen gas or ammonium gas as an essential component.

  The plasma gas 109 may be a mixed gas with a gas other than the nitrogen atom-containing gas which is an essential component. For example, a gas having an action of improving the stability of the thermal plasma 104 (for example, argon gas) may be mixed with nitrogen gas.

  Hydrogen gas is particularly preferable as a gas mixed with the plasma gas 109 other than the nitrogen-containing gas. By mixing the hydrogen gas with the plasma gas 109, the oxide film coated on the surface of the element (metal element or non-metal element) contained in the generated nitride film 116 can be removed. Therefore, when the thermal plasma 104 is brought into contact with the nitride film 116, elements in the nitride film 116 are easily nitrided, and as a result, an increase in the nitride content in the nitride film 116 is promoted. Can do.

  Here, when the nitride film 116 is formed on the substrate 101, it is preferable to perform thermal spraying while bringing the thermal plasma 104 containing nitrogen into contact with the surface of the nitride film 116. By performing thermal spraying while contacting the thermal plasma 104 containing nitrogen and the surface of the nitride film 116, an element (metal element or non-metal element) contained in the nitride film 116 formed on the substrate 101. Nitriding is promoted, and as a result, the nitride content in the nitride film 116 increases, and the denseness can be improved.

  Note that in the case where the surface of the nitride film 116 and the thermal plasma 104 are brought into contact with each other, it is more preferable that the surface of the nitride film 116 is brought into contact with at least a bright portion having high plasma density and high activity in the thermal plasma 104. . When the bright portion of the thermal plasma 104 is brought into contact with the surface of the nitride film 116, the nitridation of the element can be particularly promoted.

  In order to spray the thermal plasma 104 and the surface of the nitride film 116 in contact with each other, the state of the thermal plasma 104 is confirmed by visual observation through sunglasses, and the outlet of the thermal plasma 104 and the surface of the substrate 101 are observed. The distance L (hereinafter, this distance is referred to as “spraying distance L”) may be adjusted. In addition, since the distinction between the bright part in the thermal plasma 104 and the low bright part around it can also be confirmed by visual observation through sunglasses, the bright part of the thermal plasma 104 and the surface of the nitride film 116 are observed. Also, the thermal spray distance L can be adjusted while visually observing through sunglasses.

  For example, as shown in FIG. 1, the spraying distance L is adjusted by providing a height-adjustable spacer 105 as a part of a pedestal that supports the substrate holder 102 from below, and appropriately changing the height of the spacer 105. Can be done. 1 is the distance between the outlet of the thermal plasma 104 and the surface of the substrate 101.

  It is preferable that the spray distance L is as short as possible because the thermal plasma 104 can be sufficiently brought into contact with the surface of the sprayed film 116.

  Here, for example, in the case of the apparatus 100 (see FIG. 1) that performs low-pressure plasma spraying, the spraying distance L is preferably about 10 mm to 100 mm, and more preferably about 20 mm to 60 mm.

  On the other hand, in the case of the apparatus 200 (see FIG. 2) that performs plasma spraying at normal pressure, the spraying distance L is about 10 mm to 300 mm regardless of whether the thermal plasma 104 is in contact with the substrate 101 or not. It is preferable that the thickness is about 20 mm to 200 mm.

  However, since the preferred spraying distance L can vary depending on various factors such as the generation method of the thermal plasma 104, plasma conditions and materials, the spraying distance L is particularly limited to the above range in the film forming method of the present invention. It is not something.

  When thermal spraying is performed while the thermal plasma 104 containing nitrogen is in contact with the surface of the nitride film 116, the nitridation that forms the nitride film 116 at the contact portion between the thermal plasma 104 and the surface of the nitride film 116 being formed. It is preferable that the temperature is lower than the decomposition temperature of the product or lower than the decomposition temperature.

  As described above, the temperature at the contact portion between the thermal plasma 104 and the surface of the nitride film 116 being formed is set to be equal to or lower than the decomposition temperature of the nitride constituting the nitride film 116 or less than the decomposition temperature. Decomposition of nitrides during film formation, that is, nitrides generated by nitriding reaction of elemental powder can be suppressed. As a result, a dense nitride film 116 having a high nitride content can be obtained.

  Further, from the viewpoint of suppressing the decomposition of nitride during film formation, not only the contact portion between the thermal plasma 104 and the surface of the nitride film 116 during film formation, but also the nitride film formed on the substrate 101. Throughout 116, it is preferred that the temperature be below or below the decomposition temperature of the nitride.

  On the other hand, when thermal spraying is performed while the thermal plasma 104 containing nitrogen is in contact with the surface of the nitride film 116, the thermal spray material M is formed at the contact portion between the thermal plasma 104 and the surface of the nitride film 116 being formed. It is preferable that the temperature be higher than or higher than the melting point of the metal element or non-metal element contained in the metal.

  As described above, the temperature at the contact portion between the thermal plasma 104 and the surface of the nitride film 116 being formed is set to be equal to or higher than the melting point of the metal element or the non-metal element contained in the thermal spray raw material M. The element powder during film formation by thermal spraying can be reliably melted. There are some nitrides (for example, titanium nitride) in which the nitriding reaction proceeds in the solid state below the melting point of the element, but for many nitride films, the element powder is reliably melted as described above By doing so, the nitriding reaction can surely proceed, so that a dense nitride film 116 with a high nitride content can be obtained, which is effective.

  In addition, in order to promote melting of a metal element or a non-metal element during film formation, not only a contact portion between the thermal plasma 104 and the surface of the nitride film 116 during film formation, but also a substrate 101 is formed. Further, it is more preferable that the temperature of the entire nitride film 116 is equal to or higher than the melting point or higher than the melting point of the metal element or non-metal element contained in the thermal spray material M.

  When the decomposition temperature of the nitride constituting the nitride film 116 is equal to or lower than the melting point or lower than the melting point of the metal element or non-metal element contained in the thermal spray raw material, the substrate holder 102 is provided with a cooling function, and at least It is preferable to set the temperature of the surface of the substrate 101 to be equal to or lower than the decomposition temperature of nitride.

  The nitride film 116 formed on the substrate 101 by the film forming method of the present invention described above may be further brought into contact with the thermal plasma 104. That is, after the nitride film 116 is formed on the substrate 101 while supplying the thermal spraying material M into the thermal plasma 104 containing nitrogen, the formed nitride film 116 is subjected to thermal plasma without supplying the thermal spraying material M. 104 may be further contacted.

  In this way, the nitride film 116 formed on the base material 101 is further brought into contact with the thermal plasma 104 containing nitrogen, thereby nitriding the unreacted metal element or nonmetal element remaining in the nitride 116. As a result, the nitride content in the nitride film 116 can be further improved. In this case, it is more preferable to contact at least a bright portion in the thermal plasma 104 because nitriding of the element is particularly promoted.

  Note that, when the nitride film 116 is further brought into contact with the thermal plasma 104, as described above, the decomposition of the nitride contained in the nitride film 116 is suppressed, so that the surface of the thermal plasma 104 and the nitride film 116 is reduced. In the contact portion, the temperature is preferably equal to or lower than the decomposition temperature of the nitride constituting the nitride film 116 or lower than the decomposition temperature.

  Similarly, as described above, the temperature of the contact portion between the thermal plasma 104 and the surface of the nitride film 116 depends on the temperature of the thermal spray raw material M from the point of promoting the nitriding reaction by promoting the melting of the metal element or the nonmetal element. It is preferable that the melting point is higher than or higher than the melting point of the metal element or non-metal element contained in.

  Here, the nitride film 116 obtained by the film forming method of the present invention may be formed by depositing a plurality of sprayed films. In that case, after forming the one-layer sprayed film 116 by the above-described film forming method of the present invention, the surface is further brought into contact with the thermal plasma 104 without supplying the spraying material M, and remains in the nitride film 116. It is preferable to nitride the unreacted metal element or non-metal element to be deposited, and then deposit the next nitride film 116 layer.

  As described above, by further bringing the surface of the nitride film 116 of each layer into contact with the thermal plasma 104, a thick film of the nitride film 116 having an extremely high nitride content can be obtained.

  Alternatively, after the plurality of nitride films 116 are deposited, the surface of the deposited nitride film 116 may be further brought into contact with the thermal plasma 104 without supplying the thermal spray material M as a finish.

  In addition, when the nitride film 116 is obtained by depositing a plurality of sprayed films, so-called “plasma-laser hybrid spraying” may be applied. In other words, the plasma spraying apparatus such as the apparatus 100 and the apparatus 200 was combined with an apparatus capable of irradiating a high-power laser, and the sprayed film 116 was formed during or after the formation of the sprayed film 116 for each layer. A layer of the nitride film 116 may be deposited by irradiating the sprayed film 116 with a laser using nitrogen gas. Thus, by performing laser irradiation using nitrogen gas on the formed sprayed film 116, the unreacted metal element or nonmetal element remaining in the nitride film 116 is melted, and the adhesion of each layer is increased. Improvement, densification of the film, and improvement of reactivity can be achieved. In this case, the temperature of the laser irradiation part is preferably a temperature equal to or lower than the decomposition temperature of the nitride or lower than the decomposition temperature, and preferably higher than or higher than the melting point of the metal element or nonmetal.

  In the film forming method of the present invention, at the time of thermal spraying, the position of the base material 101 may be fixed, or the position may be moved back and forth and right and left. By moving the base material 101 back and forth and right and left during thermal spraying, the entire base material 101 can be irradiated with the thermal plasma 104, and uniform thermal spraying and heating can be performed, so that a uniform nitride film 116 is formed on the base material 101. be able to.

  As described above, according to the film forming method of the present invention, a mixed powder composed of a powder of a metal element or a nonmetal element and a nitride powder of the element is used as a thermal spray raw material, and the thermal spray raw material is contained in a thermal plasma containing nitrogen. By performing plasma spraying by introducing into the substrate, a high nitride content and a dense nitride film can be obtained on the base material.

  In addition, since the nitride film of the present invention is a film obtained by plasma spraying using a powder of a metal element or a non-metal element and a mixed powder composed of the nitride powder of the element as a spraying raw material, the nitride content is It is a high and dense film with a thick film. Therefore, the excellent characteristics exhibited by the nitride can be effectively expressed and the durability is excellent.

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

[Example 1]
Using the apparatus 100 shown in FIG. 1, an aluminum nitride sprayed film was formed as a nitride film 116 on a quartz base material as the base material 101.

  First, a 20 mm square quartz substrate 101 whose surface was roughened by blasting was mounted on a water-cooled substrate holder 102 in a vacuum chamber 103. After the spraying distance L was previously adjusted to 60 mm, the rotary pump 107 was evacuated to 0.5 Torr or less.

  Next, a sheath gas 108 and a plasma gas 109 were introduced, and the pressure was set to 60 Torr. Here, when the sheath gas 108 and the plasma gas 109 are introduced, the flow rate of argon gas as the sheath gas 108 is 10 L / min, and the flow rate of argon gas as the plasma gas 109 is 10 L / min. The flow rate of nitrogen gas was 1 L / min.

  After introducing the sheath gas 108 and the plasma gas 109 to a pressure of 60 Torr, a high frequency with a power of 5 kW was applied to the high frequency coil 110 to generate the thermal plasma 104. The thermal plasma 104 generated under these conditions was in sufficient contact with the sprayed film 116 formed on the quartz substrate 101.

  Next, the thermal plasma 104 was irradiated to the quartz substrate 101 on the substrate holder 102. In this case, since the quartz substrate 101 was cooled from the back surface by the water-cooled substrate holder 102, preheating was not performed.

  Next, a fine powder feeder manufactured by Technoserve is used as the powder feeder 111, and argon gas is introduced at a flow rate of 1 L / min as the carrier gas 112, whereby the aluminum / aluminum nitride mixed powder is heated at about 1 g / min. The plasma 104 was supplied. Here, the aluminum / aluminum nitride mixed powder is obtained by simply mixing aluminum powder having an average particle diameter of about 3 μm and aluminum nitride powder at a weight ratio of 1: 1.

  Then, spraying was repeated on the quartz substrate 101 while moving the thermal plasma 104 under the above conditions, and 10 layers of the aluminum nitride film 116 were deposited.

  The obtained aluminum nitride film 116 had a thickness of 200 μm, and formation of aggregates was not confirmed. Further, when the composition of the obtained aluminum nitride film 116 was analyzed by a fluorescent X-ray method, it contained about 75 mol% of aluminum nitride. Further, the analysis result by X-ray diffraction was mainly composed of aluminum nitride peaks and also aluminum peaks. Further, as a result of SEM observation of the cross section of the obtained aluminum nitride film 116, the film structure was dense.

[Example 2]
An aluminum nitride film 116 was produced under the same conditions as in Example 1 except that the mixing ratio of aluminum and aluminum nitride in the aluminum / aluminum nitride mixed powder as the thermal spraying raw material was 2: 8 (weight ratio).

  The obtained aluminum nitride film 116 had a thickness of 300 μm, and formation of aggregates was not confirmed. Further, when the composition of the obtained aluminum nitride film 116 was analyzed by the fluorescent X-ray method, it contained about 94 mol% of aluminum nitride. The analysis result by X-ray diffraction was almost the peak of aluminum nitride. Further, as a result of SEM observation of the cross section of the obtained aluminum nitride film 116, the film structure was dense.

  The present invention has been described above based on the embodiments. However, the present invention is not limited to the above-described embodiments, and various modifications and changes can be easily made without departing from the spirit of the present invention. Can be inferred.

It is a schematic diagram which shows the apparatus which plasma-sprays a thermal spray raw material on a base material under reduced pressure as an example of the apparatus which forms the nitride film of this invention on a base material. It is a schematic diagram which shows the apparatus which performs the plasma spraying of the thermal spray raw material on a base material as an example of the apparatus which forms the nitride film of this invention on a base material.

Explanation of symbols

101 Substrate 104 Thermal plasma 116 Thermal spray film (nitride film)

Claims (7)

  The film is formed by a thermal spraying method using a mixture substantially composed of a powder of a metal element or a non-metal element and a nitride powder of the element as a thermal spray material, and the film thickness is 1 μm or more and 3 mm or less. A nitride film having a nitride content of 25 mol% or more and 100 mol% or less. In a film forming method for forming a nitride film containing a nitride of a metal or a nonmetallic element on a substrate by a thermal spraying method,
Generating a thermal plasma containing nitrogen and supplying a mixture substantially composed of a powder of a metal element or a nonmetallic element and a powder of a nitride of the element as a thermal spray material in the thermal plasma containing nitrogen A film forming method in which the mixture is thermally sprayed to form the nitride film on the substrate.   The film forming method according to claim 2, wherein the thermal spraying is performed while bringing thermal plasma into contact with a surface of a nitride film formed on the substrate.   The film forming method according to claim 3, wherein a temperature of a contact portion between the thermal plasma and the surface of the nitride film is equal to or lower than a decomposition temperature of the nitride or less than a decomposition temperature.   5. The film forming method according to claim 3, wherein the temperature of the contact portion between the thermal plasma and the surface of the nitride film is equal to or higher than or exceeds the melting point of the metal element or nonmetal element.   6. The film forming method according to claim 2, wherein the nitride film formed on the base material is further brought into contact with the thermal plasma. 7. The composition according to claim 2, wherein a particle size of the powder of the metal element or the non-metal element and the powder of the nitride of the element is 0.1 μm or more and 200 μm or less. Membrane method.

Images