JP7585574B2 - Powder for cold spray, cold spray film, and method for producing the film - Google Patents

Description

The present invention relates to powders for cold spray, cold spray films, and methods for producing films.

The cold spray method is a system that accelerates raw material particles to near the speed of sound and causes them to collide with a substrate in a solid phase to form a film. In the cold spray method, a supersonic nozzle (Laval nozzle) is usually used to generate a high-speed gas flow, and powder particles are injected into the gas flow to increase the collision speed, causing the material particles to collide with the substrate at high speed.
Cold spray is a coating technology classified as a type of thermal spraying. However, it differs from conventional thermal spraying in that a coating is formed by colliding raw material in a molten or semi-molten state with a substrate, whereas cold spray adheres the raw material to the substrate without melting it.

Conventionally, the cold spray method has generally been used to form metal films, which have excellent ductility, and there have been very few examples of forming ceramic films, which are brittle materials.
However, in recent years, the applicant has found that it is possible to form a film by the cold spray method for powder of an yttrium compound having a specific specific surface area or more (Patent Document 1).

Meanwhile, there are reports of adding alumina powder to metal powders used in cold spraying to eliminate nozzle clogging and improve the hardness of the resulting film (for example, Non-Patent Document 1).
Furthermore, Patent Document 2 describes a thermal spray powder containing yttrium oxide, which has a pore radius distribution peak of 0.2 μm or more, as a thermal spray powder that can provide a dense coating in plasma spraying with suppressed spitting.

WO2020/090528 publication JP 2006-200005 A

Tetsuya Sonoda et al., "Preparation and Evaluation of NiAl High-Temperature Corrosion-Resistant Coating by Cold Spray Method," Journal of the Japan Welding Society, Vol. 28 (2010) No. 4, pp. 376-382

The applicant has found that with respect to the cold spray material described in Patent Document 1, depending on the film formation conditions, there may be room for improvement in terms of material supplyability, such as the occurrence of nozzle clogging during film formation.
On the other hand, Non-Patent Document 1 describes the use of alumina powder as a supply aid for the metal film-forming raw material when the metal film-forming raw material is used to form a film by a cold spray method, but does not consider what kind of supply aid is suitable when a specific rare earth compound such as yttrium is used to form a film by a cold spray method.
Furthermore, Patent Document 2 does not relate to powders for cold thermal spraying, and the document makes no mention of the pore volume having a pore diameter of less than 0.3 μm, which is essential for obtaining a coating having higher hardness than conventional coatings in cold thermal spraying.

Therefore, an object of the present invention is to provide a material for cold spray that is excellent not only in film-forming properties but also in supplyability, by using a compound of a specific rare earth element such as yttrium as a film-forming compound.
Another object of the present invention is to provide a film having a hardness that has heretofore been difficult to obtain as a cold spray film of a compound of a specific rare earth element such as yttrium, and a method for producing the same.

The present invention provides a powder for cold spraying, which contains a compound of at least one film-forming element selected from Y, Yb, and Gd,
The present invention provides a powder for cold spray, in which at least one peak is observed in a pore size range of 0.3 μm or more and 2.0 μm or less in a distribution of pore volume versus pore size measured by mercury intrusion porosimetry, and the pore volume of pores with a pore size of less than 0.3 μm is 0.1 ml/g or more and 0.5 ml/g or less.

The present invention also provides a cold spray film formed using the cold spray powder.

The present invention further provides a method for producing a film, which includes a step of performing a cold spray method using the powder.

The present invention further provides a cold spray coating comprising one or more elements selected from Y ₅ O ₄ F ₇ , YOF and YF ₃ and having a Vickers hardness of 70 or more and 500 or less.

According to the present invention, a material for cold spraying that is excellent not only in film-forming properties but also in supplyability can be provided by using a compound of a specific rare earth element such as yttrium as a film-forming compound.
Furthermore, the present invention can provide a cold spray film of a specific rare earth compound such as yttrium that has a hardness that has been difficult to obtain in the past, and a method for producing the same.

FIG. 4 is a schematic diagram illustrating a powder supply method during film formation in the examples. 1 is a chart showing the pore volume distribution of the powder for cold spray in Example 1. 1 is a chart showing the pore volume distribution of the powder for cold spray in Example 2. 1 is a chart showing the pore volume distribution of the powder for cold spray in Comparative Example 1. 1 is a chart showing the pore volume distribution of the powder for cold spray in Comparative Example 2. 1 is a chart showing the particle size distribution of the powder for cold spray in Example 1. 1 is a chart showing the particle size distribution of the powder for cold spray in Example 2. 1 is a chart showing the particle size distribution of a powder for cold spray in Comparative Example 1. 1 is a chart showing the particle size distribution of a powder for cold spray in Comparative Example 2.

The present invention will now be described based on its preferred embodiments.
First, the powder for cold spray of the present invention will be described. Hereinafter, "cold spray" may be abbreviated as "CS". The powder for CS of the present invention has excellent film-forming and supplying properties by the CS method, and can obtain a cold spray film (CS film) with a hardness that has been difficult to obtain in the past as a CS film containing a specific rare earth compound.

(1) Compound of Rare Earth Element One of the features of the CS powder of the present invention is that it contains a compound of a film-forming element of at least one rare earth element selected from Y, Yb, and Gd (hereinafter also referred to as " ^Ln1 ").

In the present invention, the compound of Ln ¹ is preferably an oxide of Ln ¹ , a fluoride of Ln ¹ , or an oxyfluoride of Ln ¹ , in that excellent corrosion resistance can be obtained when the CS powder is used for coating a semiconductor manufacturing device, and in particular, from the viewpoint of chemical stability against fluorine-based plasma, it is preferable that the compound is an oxide of Ln 1, a fluoride of Ln ¹ , or an oxyfluoride of Ln ¹ .
The oxide of ^Ln1 includes a _{sesquioxide (Ln12O3} ⁾ _and a composite oxide of ^Ln1 and Al, etc. The fluoride of ^Ln1 is preferably represented _by ^Ln1F3 .

The oxyfluoride of Ln ¹ is a compound (hereinafter also referred to as "Ln ¹ -O-F") consisting of a specific rare earth element (Ln ¹ ) such as Y, oxygen (O), and fluorine (F). Ln ¹ -O-F may be a compound (Ln ¹ OF) in which the molar ratio of the rare earth element (Ln ¹ ), oxygen (O), and fluorine (F) is Ln ¹ :O:F=1:1:1, or may be an oxyfluoride of a rare earth element in another form (Ln ¹ ₅ O ₄ F ₇ , Ln ¹ ₇ O ₆ F ₉ , Ln ¹ ₄ O ₃ F _6, etc.). From the viewpoint of availability of oxyfluorides and from the viewpoint of achieving the effect of the present invention, namely, high film-forming property and supplyability, Ln ¹ -O-F is preferably represented by Ln ¹ O _x F _y (0.3≦x≦1.7, 0.1≦y≦1.9). In particular, from the viewpoint above, in the above formula, it is more preferable that 0.35≦x≦1.65, and even more preferable that 0.4≦x≦1.6. Also, it is more preferable that 0.2≦y≦1.8, and even more preferable that 0.5≦y≦1.5. In addition, in the above formula, it is also preferable that 2.3≦2x+y≦5.3, particularly 2.35≦2x+y≦5.1 is satisfied, and it is particularly preferable that 2x+y=3 is satisfied. In particular, it is preferable to use one where x<1 and y>1, in terms of chemical stability against both fluorine-based plasma and oxygen-based plasma.

It is most preferable that Ln ¹ is Y, since it is suitable for use as a corrosion-resistant member of semiconductor manufacturing equipment and has an excellent effect of improving the supplyability and the resulting hardness of the film according to the present invention.

(2) Pore volume distribution The CS powder of the present invention is characterized in that, in the distribution of pore volume versus pore diameter measured by mercury intrusion porosimetry, at least one peak is observed in the pore diameter range of 0.3 μm to 2.0 μm, and the volume of pores with a pore diameter of less than 0.3 μm is 0.1 ml/g to 0.5 ml/g. Note that the pore diameter in this specification refers to the pore diameter.
The present inventors have intensively studied a configuration for improving the supplyability of a powder of a specific rare earth compound such as conventional yttrium without clogging a nozzle (supply pipe) during film formation while maintaining the film-forming properties. As a result, it has been found that a powder having a peak of pore diameters of 0.3 μm or more and 2.0 μm or less in the distribution of pore volume, and a pore volume of pores with diameters of less than 0.3 μm falling within the above range, improves the supplyability during film formation by the CS method, and by subjecting the powder to the CS method, a film having a higher hardness than the CS film of the conventional Ln ¹ compound can be obtained.

In the pore volume distribution, a powder that has a peak in the pore diameter range of 0.3 μm to 2.0 μm and has a pore volume of less than 0.3 μm at the above-mentioned specified amount usually contains two or more types of particles (powders) with different particle sizes. Specifically, in the pore volume distribution, the peak in the pore diameter range of 0.3 μm to 2.0 μm is derived from the interparticle voids of the primary particles of the powder with a relatively large particle size (primary particle size). Also, the pore volume within the above range in the pore diameter range of less than 0.3 μm is derived from the interparticle voids of the primary particles of the powder with a relatively small particle size (primary particle size).

In the pore volume distribution of the CS powder, the powder that gives a pore volume in the above range of pore diameters less than 0.3 μm has a relatively small primary particle size as described above, and as a result has a specific surface area of a certain level or more. A high specific surface area is important for the film-forming properties of the CS powder. On the other hand, a powder having such a specific surface area may cause clogging in an acceleration nozzle for colliding the powder with a substrate at high speed during film formation by the CS method, thereby reducing the supplyability. In this regard, the CS powder of the present invention contains a powder with a relatively large particle size (primary particle size) that gives a peak in the pore diameter range of 0.3 μm to 2.0 μm. The presence of this relatively large particle size (primary particle size) improves nozzle clogging during powder supply in the CS method using a specific rare earth Ln ^1. As a result, the collision speed of the film-forming powder with the substrate during film formation by the CS method is stable at a high speed, and it is considered that the hardness of the obtained CS film is increased.

In the powder for CS of the present invention, the particles that give the pore volume with a pore diameter of less than 0.3 μm preferably contain Ln ^1. The fact that the particles that give the pore volume with a pore diameter of less than 0.3 μm contain Ln ¹ can be confirmed, for example, by observing the powder spread on a carbon tape with a scanning electron microscope (SEM) at a magnification of 1500 times and performing a point analysis of energy dispersive X-ray analysis (EDX) on the observed powder. For example, it is preferable to observe two or more types of particles with large and small aggregate diameters (secondary particle diameters), and to perform a point analysis on the particles having the large aggregate diameter, and it is more preferable that the particles with the large aggregate diameter have an aggregate diameter corresponding to a D ₅₀ measured by a laser diffraction/scattering type particle size distribution measurement method of more than 10 μm. An example of a particle that gives a pore volume with a pore diameter of less than 0.3 μm is the first powder described later. On the other hand, a powder that gives at least one peak in the pore volume distribution at a pore diameter of 0.3 μm to 2.0 μm is preferably a ceramic powder. A suitable example of the powder is the second powder described below.

In the present invention, the CS powder has a pore size in the range of 0.3 μm to 2.0 μm, and in particular, it is preferable for the CS powder to have a peak in the range of 0.6 μm to 1.8 μm in order to further improve supplyability, and it is even more preferable for the powder to have a peak in the range of 0.8 μm to 1.4 μm.

In the present invention, it is preferable from the viewpoint of fluidity that the falling point (end point) of the pore volume peak in the pore diameter range of 0.3 μm to 2.0 μm is located on the larger diameter side of the pore diameter of 0.3 μm. Here, the falling point of the peak is the pore diameter equal to or greater than the intersection point of the descending slope of the peak from the larger diameter side to the smaller diameter side and the baseline, and is the smallest pore diameter at which the log differential pore volume decreases by 70% or less compared to the log differential pore volume at a point 20 nm larger than that pore diameter.
In addition, the pore volume distribution of the CS powder is preferably such that the ratio IB/IA of the pore volume IB of pores with diameters less than 0.3 μm to the pore volume IA in the pore diameter range of 0.3 μm to 2.0 μm is 5 or less in terms of eliminating clogging during film formation and improving film hardness, more preferably 3 or less, particularly preferably 2 or less, and even more preferably 1.8 or less. The lower limit of IB/IA is preferably 0.1 or more in terms of suppressing peeling of the substrate and the film, and even more preferably 0.3 or more.

The CS powder of the present invention has the advantage that the film hardness is excellent when the pore volume IB of pores with diameters of less than 0.3 μm is 0.1 ml/g or more, and has the advantage that a thick film can be easily obtained when the pore volume IB is 0.5 ml/g or less. From this viewpoint, it is more preferable that the pore volume IB of pores with diameters of less than 0.3 μm is 0.12 ml/g or more and 0.4 ml/g or less, and even more preferable that it is 0.14 ml/g or more and 0.3 ml/g or less.

In terms of eliminating clogging during film formation, film hardness, and film-forming properties, the CS powder of the present invention preferably has a pore volume IA of pores with diameters of 0.3 μm to 2.0 μm of 0.05 ml/g to 0.25 ml/g, more preferably 0.12 ml/g to 0.2 ml/g.

The CS powder of the present invention may have at least one peak in the pore volume distribution at a pore diameter of less than 0.3 μm. Alternatively, it may have a broad protuberance at a pore diameter of less than 0.3 μm. When the CS powder of the present invention has at least one peak in the pore volume distribution at a pore diameter of less than 0.3 μm, the peak position of the peak may be in the range of 5 nm or more and less than 300 nm, and more preferably in the range of 10 nm or more and 200 nm or less.

CS powder having the above pore volume distribution can be obtained by a suitable manufacturing method described below.

(3) BET Specific Surface Area In order to obtain film-forming and supplying properties and thus high film hardness, the CS powder preferably has a BET specific surface area within a specific range. Specifically, the BET specific surface area of the CS powder is preferably 3 ^m2 /g or more and less than 30 ^m2 /g, more preferably 5 ^m2 /g or more and 25 ^m2 /g or less, and particularly preferably 7.5 ^m2 /g or more and 20 ^m2 /g or less.

CS powder having the above BET specific surface area can be obtained by a suitable manufacturing method described below.

(4) Particle size distribution It is preferable that the CS powder has at least one peak in the volumetric particle size distribution measured by a laser diffraction/scattering particle size distribution measurement method in the range of 1 μm to 10 μm. A powder with a particle size of 1 μm to 10 μm is likely to give a peak in the pore diameter range of 0.3 μm to 2.0 μm in the pore volume distribution. By adopting such a configuration, the CS powder can further increase the fluidity. In order to further improve the above effect, it is more preferable that the CS powder has a peak in the volumetric particle size distribution measured by a laser diffraction/scattering particle size distribution measurement method in the range of 1 μm to 10 μm, particularly in the range of 1.5 μm to 8 μm, and it is even more preferable that at least one peak is observed in the range of 2 μm to 5 μm.
In this specification, the particle size distribution of the powder for CS by the laser diffraction/scattering particle size distribution measurement method is measured on a sample that has not been subjected to ultrasonic pretreatment.

It is preferable that the CS powder has at least one peak in the volumetric particle size distribution measured by a laser diffraction/scattering particle size distribution measurement method in the range of more than 10 μm to 100 μm. In the above particle size distribution, the secondary particles having a particle size peak in the range of more than 10 μm to 100 μm tend to provide a pore volume in the above range with a pore diameter of less than 0.3 μm in the above-mentioned pore volume distribution. Secondary particles of such a particle size are preferable because they have fluidity and excellent film forming properties. From this perspective, it is more preferable that the CS powder has a peak in the volumetric particle size distribution measured by a laser diffraction/scattering particle size distribution measurement method in the range of more than 10 μm to 100 μm, particularly in the range of 20 μm to 80 μm, and even more preferably in the range of 25 μm to 50 μm. The secondary particles having the above-mentioned secondary particle size may be a granulated powder obtained by a granulation process, or may be an agglomerated powder in which primary particles are aggregated without going through a granulation process. Granulated powders are sometimes called granules.

(5) First Powder and Second Powder The powder for CS of the present invention preferably contains a first powder having a compound of Ln ¹ and having a D ₅₀ of more than 10 μm and not more than 100 μm in a volume-based particle size distribution measured by a laser diffraction/scattering type particle size distribution measurement method (a particle size at which the cumulative volume from the small diameter side by a laser diffraction/scattering type particle size distribution measurement method is 50%), and a second powder having a D ₅₀ of 1 μm or more and not more than 10 μm in the particle size distribution. The D ₅₀ of the second powder is preferably 1.5 μm or more and not more than 8 μm in terms of film-forming properties and supply properties, and more preferably 2 μm or more and not more than 5 μm. The D ₅₀ of the first powder is preferably 20 μm or more and not more than 80 μm in terms of film-forming properties and supply properties, and more preferably 25 μm or more and not more than 50 μm.
In this specification, the D ₅₀ of the first powder measured by the laser diffraction/scattering particle size distribution measurement method is measured on a sample that has not been subjected to ultrasonic pretreatment.
The first powder may be in the form of granules or agglomerated powder.

The first powder has a compound of Ln ¹ and is a film-forming powder for forming a CS film. The first powder gives a peak in the particle size distribution of the CS powder in the range of more than 10 μm to 100 μm. From the viewpoint of achieving both film-forming property and supply property, the first powder preferably has a BET specific surface area of 10 m ² /g or more and 50 m ² /g or less, and more preferably 15 m ² /g or more and 30 m ² /g or less.

The second powder acts as a supply aid. The second powder gives a peak in the particle size distribution of the CS powder in the range of 1 μm to 10 μm. The second powder preferably has a BET specific surface area of 1 ^m2 /g to 10 ^m2 /g in terms of excellent supplyability of the CS powder, and more preferably has a BET specific surface area of 2 ^m2 /g to 5 ^m2 /g.
In this specification, the D ₅₀ of the second powder measured by the laser diffraction/scattering particle size distribution measurement method is measured on a sample that has not been subjected to ultrasonic pretreatment.
The form of the second powder is not particularly limited, but it is preferable that the second powder is not in granular form in terms of improving supplyability.

The second powder is preferably a ceramic powder in terms of improving nozzle clogging when forming a film from the Ln ¹ compound by the CS method and improving the film hardness, and is particularly preferably made of at least one of rare earth compounds, silicon compounds, and aluminum compounds in terms of preventing impurity contamination of silicon wafers. The second powder is preferably made of at least one of rare earth compounds, silicon compounds, and aluminum compounds, which means that the second powder has at least one of rare earth compounds, silicon compounds, and aluminum compounds as its main phase, specifically, when the second powder is subjected to X-ray diffraction measurement under the following conditions, its main peak is derived from a rare earth compound, a silicon compound, or an aluminum compound.

The rare earth element Ln ² in the rare earth compound constituting the second powder includes 16 elements, namely, scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb) and lutetium (Lu). The compound of the rare earth element Ln ² constituting the second powder includes an oxide of the rare earth element Ln ² , a fluoride of the rare earth element Ln ² , and an oxyfluoride of the rare earth element Ln ² . As the oxide of the rare earth element ^Ln2 , the fluoride of the rare earth element ^Ln2 , and the oxyfluoride of the rare earth element ^Ln2 , the oxides, fluorides, and oxyfluorides of the above-mentioned 16 kinds of rare earth elements ^Ln2 can be used without any particular limitation.

The oxide of the rare earth element ^Ln2 may be a sesquioxide ( ^Ln22O3 , ^Ln2 being _the above rare earth element) except for cerium (Ce _{), praseodymium (Pr), and terbium (Tb). Cerium oxide is usually CeO2 , praseodymium oxide} is usually _Pr6O11 , and terbium oxide is usually _Tb4O7 . The oxide of the rare earth element ^Ln2 may be a composite oxide of two or more rare earth elements, or a composite oxide of a rare earth element and Al, etc.

The fluoride of the rare earth element ^Ln2 is preferably represented _by ^Ln2F3 . In addition, the same description as for the specific rare earth element ^Ln1 applies to the oxyfluoride of the rare earth element ^Ln2 , except that the rare earth elements are expanded to the above 16 types. In other words, the oxyfluoride of ^Ln2 is a compound consisting of a rare earth element ( ^Ln2 ), oxygen (O), and fluorine (F) (hereinafter also referred to as " ^Ln2 -O-F"). Ln ² -O-F may be a compound (Ln ² OF) in which the molar ratio of rare earth element (Ln ² ), oxygen (O), and fluorine (F) is Ln ² : O: F = 1: 1: 1, or may be an oxyfluoride of a rare earth element in another form (Ln ² ₅ O ₄ F ₇ , Ln ² ₇ O ₆ F ₉ , Ln ² ₄ O ₃ F _6, etc.). From the viewpoint of achieving a higher effect of ease of production and high supplyability of the oxyfluoride, it is preferable that Ln ² -O-F is represented by Ln ² O _x F _y (0.3≦x≦1.7, 0.1≦y≦1.9). In particular, from the above viewpoint, in the above formula, it is more preferable that 0.35≦x≦1.65, and even more preferable that 0.4≦x≦1.6. It is more preferable that 0.2≦y≦1.8, and even more preferable that 0.5≦y≦1.5. In the above formula, it is also preferable that 2.3≦2x+y≦5.3, particularly 2.35≦2x+y≦5.1, and it is particularly preferable that 2x+y=3 is satisfied. In particular, it is preferable to use a compound in which x<1 and y>1 is satisfied, in terms of chemical stability against both fluorine-based plasma and oxygen-based plasma.

The compound of the rare earth element ^Ln2 of the second powder may be the same as or different from the compound of the film-forming element ^Ln1 . It is preferable that the compound of the rare earth element ^Ln2 of the second powder is the same as the compound of the film-forming element ^Ln1 , since this makes it easier to form a film composition consisting of a single compound.
In the present invention, the second powder may constitute the obtained CS film, or may act only as an auxiliary agent for improving the supplyability, without constituting a film.

The silicon compound may be _SiO2 .

The aluminum compound includes Al ₂ O ₃ , AlF ₃ , and AlOF.

As the second powder, among the ^Ln2 compounds, it is preferable to use at least one rare earth element compound selected from Y, Y and Gd in terms of suitability for use in corrosion-resistant coating members of semiconductor devices and in terms of raw material prices, and it is preferable to use at least one rare earth element fluoride or _oxyfluoride selected from Y, Yb and Gd, and it is particularly preferable to use a Y compound in terms of chemical and physical stability against plasma. Also, it is preferable to use _Al2O3 as the second powder in terms of improving the hardness of the film.

In order to maintain film-forming properties while improving supplyability, the amount of the first powder in the CS powder is preferably 10% by mass or more and 90% by mass or less, preferably 20% by mass or more and 80% by mass or less, and particularly preferably 30% by mass or more and 70% by mass or less. The amount of the first powder is also preferably 10% by mass or more and 90% by mass or less, preferably 20% by mass or more and 80% by mass or less, and particularly preferably 30% by mass or more and 70% by mass or less, based on the total amount of the first powder and the second powder.

In order to maintain film-forming properties while improving supplyability, the amount of the second powder in the CS powder is preferably 10% by mass or more and 90% by mass or less, preferably 20% by mass or more and 80% by mass or less, and particularly preferably 30% by mass or more and 70% by mass or less. The amount of the second powder is also preferably 10% by mass or more and 90% by mass or less, preferably 20% by mass or more and 80% by mass or less, and particularly preferably 30% by mass or more and 70% by mass or less, based on the total amount of the first powder and the second powder.

The amount of powders other than the first powder and the second powder in the CS powder is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 2% by mass or less.

Next, a preferred method for producing the powder for CS will be described. The method for producing the powder for CS of the present invention includes a method in which the first powder and the second powder having the above-mentioned _D50 and composition are produced and mixed. The mixing ratio can be the preferred ratio described above.
The first powder can be produced by a conventionally known method, for example, a method similar to the method for producing a rare earth compound powder described in Patent Document 1.
The manufacturing method of the second powder is also not particularly limited, but a preferred manufacturing method in the case where the second powder is made of an oxyfluoride or fluoride of ^Ln2 will be described below.

When the second powder is made of an oxyfluoride or fluoride of ^Ln2, a suitable method for producing the second powder is to mix a fluoride of a rare earth element and an oxide of a rare earth element, sinter the mixture at 600°C to 1000°C, and then grind the mixture to have a D50 of 1 _μm to 10 μm.
The firing temperature is more preferably 700° C. or higher and 900° C. or lower. The firing atmosphere may be air.

(6) Film Formation by CS Method Next, a film formation method by the CS method will be described.
In this film formation method, the CS powder of the present invention is used as a raw material powder, and the raw material powder is heated and accelerated by a heated and pressurized gas, and caused to collide with a substrate to form a film.
An example of a film formation device used in film formation by the CS method is one that has a generation section that generates high-temperature, high-pressure gas, a gas acceleration section that receives the high-temperature, high-pressure gas from the generation section and accelerates the gas, and a substrate holding section that holds a substrate, and in which raw material powder is injected into the high-temperature, high-pressure gas flow to cause the raw material powder to collide with the substrate.

The gas temperature in the high-temperature, high-pressure gas generation section is preferably 150°C or higher in order to facilitate adhesion of rare earth compound particles to the substrate, and 800°C or lower in order to prevent metal impurity contamination from the acceleration nozzle. From these perspectives, the gas temperature is more preferably 160°C or higher and 750°C or lower, and particularly preferably 180°C or higher and 700°C or lower.

The gas pressure in the high-temperature, high-pressure gas generating section is preferably 0.1 MPa or more since it allows the particles to easily adhere to the substrate, and is preferably 10 MPa or less since it makes it easier to prevent shock waves generated near the substrate surface from causing the particles to collide with the substrate. From this perspective, the gas pressure is more preferably 0.2 MPa or more and 8 MPa or less, and particularly preferably 0.3 MPa or more and 6 MPa or less.

The gas acceleration section can be an acceleration nozzle, and the shape and structure thereof are not limited.
The substrate may be made of metal such as aluminum, aluminum alloy, stainless steel, or carbon steel; ceramics such as graphite, quartz, or alumina; or plastics.
The gas may be compressed air, nitrogen, helium, or the like.

The position of the substrate in the substrate holder may be any position that is exposed to the high-temperature, high-pressure gas flow. The substrate holder and substrate may be fixed, but it is preferable to move the substrate and/or the gun vertically and/or horizontally to expose the entire substrate to the high-temperature, high-pressure gas flow and form a uniform film. The distance between the ejection portion of the raw powder and the substrate (hereinafter also referred to as the "film formation distance") is preferably, for example, 10 mm or more and 50 mm or less in terms of ease of film formation, and more preferably 15 mm or more and 45 mm or less.

The thickness of the film obtained above is preferably 20 μm or more in terms of obtaining sufficient halogen plasma resistance by coating the components of the semiconductor manufacturing equipment, and 500 μm or less in terms of economical viewpoints and thickness suitable for the purpose. From this viewpoint, 100 μm or more and 300 μm or less are more preferable. Furthermore, from the viewpoint of durability against the physical sputtering action applied to the film during etching, the film obtained by the present invention preferably has a Vickers hardness of 70 or more, more preferably 90 or more, and even more preferably 100 or more. From the viewpoint of ease of production, the upper limit of the Vickers hardness is 500. The method for measuring the Vickers hardness can be the method described in the examples below.

The coating obtained above is composed of a compound of Ln ¹ , and preferably composed of an oxyfluoride or fluoride of Ln ^1. The coating or powder composed of a compound of Ln ¹ preferably means that the compound of Ln ¹ is the main phase, specifically, that when the coating or powder is subjected to X-ray diffraction measurement under the following conditions, the main peak is derived from the compound of Ln ^1. In particular, the coating obtained above is preferably composed of one or more selected from Y ₅ O ₄ F ₇ , YOF and YF ₃ , in terms of obtaining a relatively hard film in a CS film composed of these compounds, being chemically stable against any of fluorine-based plasma, chlorine-based plasma and oxygen-based plasma, and being suitable as a corrosion-resistant coating for members such as chambers of semiconductor manufacturing equipment.

The coating obtained above can be used for coating components of various plasma processing equipment and chemical plants in addition to components of semiconductor manufacturing equipment.

The present invention will be described in more detail below with reference to examples. However, the scope of the present invention is not limited to these examples. Unless otherwise specified, "%" means "mass %." The BET specific surface areas described below were all measured by the method described below. Figures 1 to 9 show the pore volume distribution and particle size distribution of Examples 1 and 2 and Comparative Examples 1 and 2.

Example 1
[First powder]
The first powder was prepared according to the following procedure.
1.6 kg of yttrium oxide powder was dissolved in 10 kg of 30% acetic acid aqueous solution heated to 100° C. The resulting solution was cooled, and the precipitated yttrium acetate hydrate was fired in an air atmosphere at 650° C. Yttrium oxide powder was obtained by this process.
The obtained yttrium oxide powder was dispersed in pure water at a concentration of 70 g/L, and 50% hydrofluoric acid was added thereto so that 25 g of hydrogen fluoride was obtained per 100 g of yttrium oxide, and the mixture was stirred at 25° C. for 24 hours to obtain an yttrium oxyfluoride precursor. The obtained precursor was dehydrated and then dried at 120° C. for 24 hours in an air atmosphere. The obtained dried powder was calcined at 400° C. for 5 hours in an air atmosphere, and then crushed with a pin mill to obtain an yttrium oxyfluoride powder.
The obtained yttrium oxyfluoride powder was dispersed in pure water at a concentration of 35%, and then granulated using a FOC-16 spray dryer manufactured by Okawara Kakakuki Co., Ltd. to obtain yttrium oxyfluoride (Y ₅ O ₄ F ₇ ) granulated powder (granules). The operating conditions of the spray dryer were a slurry supply rate of 245 ml/min, an atomizer rotation speed of 20,000 min ^-1 , and an inlet temperature of 250°C.

[Second Powder]
As the second powder, alumina powder DTS-A35-10/0 manufactured by Fujimi Incorporated was used.

500 g of the first powder and 500 g of the second powder obtained above were shaken in a vinyl bag for 3 minutes to obtain a mixed powder for CS. In the mixed powder for CS obtained in Example 1, the ratio IB/IA of the pore volume IB to the pore volume IA was 5 or less. In the powder for CS, the falling point (end point) of the pore volume peak in the pore diameter range of 0.3 μm to 2.0 μm was located on the larger diameter side than the pore diameter of 0.3 μm. In addition, in the pore volume distribution, a pore volume peak was observed in the pore diameter range of 10 nm to 200 nm.

Example 2
[First powder]
The first powder was the same as that used in Example 1.
[Second Powder]
The second powder was prepared according to the following procedure.
1.0 kg of yttrium oxide powder manufactured by Nippon Yttrium Co., Ltd. and 1.1 kg of yttrium fluoride powder were mixed using an Ishikawa-type mixing and crushing machine manufactured by Ishikawa Kogyo Co., Ltd., and fired at 900°C for 24 hours in an air atmosphere. The fired product was coarsely crushed using a mass colloider manufactured by Masuko Sangyo Co., Ltd. Pure water was added to the coarsely crushed product to make a 30% slurry, and then wet-pulverized using a ball mill until _D50 was 2.5 μm. The crushed product was dried at 150°C for 24 hours in an air atmosphere, and then finely crushed using a pin mill to obtain the desired second powder.

500 g of the first powder and 500 g of the second powder obtained above were shaken in a plastic bag for 3 minutes to prepare a mixed powder for CS.

Example 3
[First powder]
The first powder was prepared according to the following procedure.
1.6 kg of yttrium oxide powder was dissolved in 10 kg of 30% aqueous acetic acid solution heated to 100° C. The resulting solution was cooled, and the precipitated yttrium acetate hydrate was fired in an air atmosphere at 650° C. By this process, yttrium oxide powder was obtained.
The obtained yttrium oxide powder was dispersed in pure water at a concentration of 70 g/L, and 50% hydrofluoric acid was added thereto so that 18 g of hydrogen fluoride was added per 100 g of yttrium oxide, and the mixture was stirred at 25° C. for 24 hours to obtain an yttrium oxyfluoride precursor. The obtained precursor was dehydrated and then dried at 120° C. for 24 hours in an air atmosphere. The obtained dried powder was calcined at 400° C. for 5 hours in an air atmosphere, and then crushed with a pin mill to obtain an yttrium oxyfluoride powder.
The obtained yttrium oxyfluoride powder was dispersed in pure water at a concentration of 35%, and then granulated using a FOC-16 spray dryer manufactured by Okawara Kakakuki Co., Ltd. to obtain yttrium oxyfluoride (YOF) granulated powder (granules). The operating conditions of the spray dryer were a slurry supply rate of 245 ml/min, an atomizer rotation speed of 20,000 min ^-1 , and an inlet temperature of 250°C.

[Second Powder]
The second powder was prepared according to the following procedure.
1.0 kg of yttrium oxide powder manufactured by Nippon Yttrium Co., Ltd. and 0.6 kg of yttrium fluoride powder were mixed using an Ishikawa-type mixing and crushing machine manufactured by Ishikawa Kogyo Co., Ltd., and fired at 900°C for 24 hours in an air atmosphere. The fired product was coarsely crushed using a mass colloider manufactured by Masuko Sangyo Co., Ltd. Pure water was added to the coarsely crushed product to make a 30% slurry, and then wet-pulverized using a ball mill until _D50 was 2.5 μm. The crushed product was dried at 150°C for 24 hours in an air atmosphere, and then finely crushed using a pin mill to obtain the desired second powder.

500 g of the first powder and 500 g of the second powder obtained above were shaken in a plastic bag for 3 minutes to prepare a mixed powder for CS.

Example 4
[First powder]
The first powder was prepared according to the following procedure.
1.6 kg of yttrium oxide powder was dissolved in 10 kg of 30% aqueous acetic acid solution heated to 100° C. The resulting solution was cooled, and the precipitated yttrium acetate hydrate was fired in an air atmosphere at 650° C. By this process, yttrium oxide powder was obtained.
The obtained yttrium oxide powder was dispersed in pure water at a concentration of 70 g/L, and 50% hydrofluoric acid was added thereto so that 35 g of hydrogen fluoride was added per 100 g of yttrium oxide, and the mixture was stirred at 25° C. for 24 hours to obtain an yttrium oxyfluoride precursor. The obtained precursor was dehydrated and then dried at 120° C. for 24 hours in an air atmosphere. The obtained dried powder was calcined at 400° C. for 5 hours in an air atmosphere, and then crushed with a pin mill to obtain a powder containing yttrium oxyfluoride and yttrium fluoride.
The obtained powder was dispersed in pure water at a concentration of 35%, and then granulated using an FOC-16 spray dryer manufactured by Okawara Kakakuki Co., Ltd. to obtain granulated powders (granules) of yttrium oxyfluoride (Y ₅ O ₄ F ₇ ) and YF _3. The operating conditions of the spray dryer were a slurry supply rate of 245 ml/min, atomizer rotation speed of 20,000 min ^-1 , and inlet temperature of 250°C.
The resulting powder was subjected to X-ray diffraction measurement under the conditions described below, which revealed that the main phase was Y ₅ O ₄ F ₇ (YO _0.8 F _1.4 ) and the subphase was YF ₃ .

[Second Powder]
The second powder was prepared according to the following procedure.
1.0 kg of yttrium oxide powder manufactured by Nippon Yttrium Co., Ltd. and 2.6 kg of yttrium fluoride powder were mixed using an Ishikawa-type stirring and crushing machine manufactured by Ishikawa Kogyo Co., Ltd., and fired at 900°C for 24 hours in an air atmosphere. The fired product was coarsely crushed using a mass colloider manufactured by Masuko Sangyo Co., Ltd. Pure water was added to the coarsely crushed product obtained to make a 30% slurry, and then wet-pulverized using a ball mill until _D50 was 2.5 μm. The resulting pulverized product was dried at ₁₅₀ °C for 24 hours in an air atmosphere, and then finely crushed using a pin mill to obtain the desired second powder. The obtained second powder was subjected to X-ray diffraction measurement under the following conditions, and _the main phase was _Y5O4F7 ( _YO0.8F1.4 ) and _the subphase was _YF3 .

500 g of the first powder and 500 g of the second powder obtained above were shaken in a plastic bag for 3 minutes to prepare a mixed powder for CS.

Example 5
[First powder]
A precipitate of yttrium fluoride was obtained by reacting 2.2 kg of an aqueous solution of yttrium nitrate having a concentration of 300 g/L in terms of yttrium oxide with 0.5 kg of 50% hydrofluoric acid. The precipitate was dehydrated and washed, and then dried at 150° C. for 24 hours in an air atmosphere. The dried powder was crushed in a grinder to obtain a powder of yttrium fluoride.
The obtained powder was dispersed in pure water at a concentration of 35%, and then granulated using a spray dryer FOC-16 manufactured by Okawara Kakakuki Co., Ltd. to obtain a granulated powder (granules) of yttrium fluoride _YF3 . The operating conditions of the spray dryer were a slurry supply rate of 245 ml/min, an atomizer rotation speed of 20,000 min ^-1 , and an inlet temperature of 250°C.
The obtained powder was subjected to X-ray diffraction measurement under the following conditions, and the main phase was found to be _YF3 .

[Second Powder]
The second powder was prepared according to the following procedure.
The first powder of this example was sintered at 900°C for 24 hours in an air atmosphere to obtain a sintered product, which was then roughly crushed using a mass colloider manufactured by Masuko Sangyo Co., Ltd. The resulting roughly crushed product was mixed with pure water to obtain a 30% slurry, which was then wet-pulverized using a ball mill until the _D50 reached 2.5 μm. The resulting pulverized product was dried at 150°C for 24 hours in an air atmosphere, and then finely crushed using a pin mill to obtain the desired second powder.

500 g of the first powder and 500 g of the second powder obtained above were shaken in a plastic bag for 3 minutes to prepare a mixed powder for CS.

Example 6
[First powder]
The first powder was prepared according to the following procedure.
1.6 kg of yttrium oxide powder was dissolved in 10 kg of 30% aqueous acetic acid solution heated to 100° C. The resulting solution was cooled, and the precipitated yttrium acetate hydrate was fired in an air atmosphere at 650° C. By this process, yttrium oxide powder was obtained.
The obtained yttrium oxide powder was dispersed in pure water at a concentration of 70 g/L, and 50% hydrofluoric acid was added thereto so that 25 g of hydrogen fluoride was obtained per 100 g of yttrium oxide, and the mixture was stirred at 25° C. for 24 hours to obtain an yttrium oxyfluoride precursor. The obtained precursor was dehydrated and then dried in an air atmosphere at 120° C. for 24 hours. The obtained dried powder was calcined in an air atmosphere at 900° C. for 5 hours, and then crushed in a pin mill to obtain an yttrium oxyfluoride powder.
The obtained dry powder was dispersed in pure water at a concentration of 35%, and then granulated using a spray dryer FOC-16 manufactured by Okawara Kakakuki Co., Ltd. to obtain yttrium oxyfluoride ( _Y5O4F7 ) granulated powder ( _granules ). The operating conditions of the spray dryer were a slurry supply rate of 245 ml/min, atomizer rotation speed of _20,000 min ^-1 , and inlet temperature of 250°C.

[Second Powder]
The second powder was prepared according to the following procedure.
1.0 kg of yttrium oxide powder manufactured by Nippon Yttrium Co., Ltd. and 1.1 kg of yttrium fluoride powder were mixed using an Ishikawa-type mixing and crushing machine manufactured by Ishikawa Kogyo Co., Ltd., and fired at 900°C for 24 hours in an air atmosphere. The fired product was coarsely crushed using a mass colloider manufactured by Masuko Sangyo Co., Ltd. Pure water was added to the coarsely crushed product to make a 30% slurry, and then wet-pulverized using a ball mill until _D50 was 2.5 μm. The crushed product was dried at 150°C for 24 hours in an air atmosphere, and then finely crushed using a pin mill to obtain the desired second powder.

500 g of the first powder and 500 g of the second powder obtained above were shaken in a plastic bag for 3 minutes to prepare a mixed powder for CS.

<Comparative Example 1>
[First powder]
The first powder was the same as that used in Example 1.
In this example, the second powder was not used, and 500 g of the first powder was used as the CS powder.

<Comparative Example 2>
[First powder]
The first powder was that described in Example 1.

[Second Powder]
As the second powder, alumina powder DTS-A150-45-45/10 manufactured by Fujimi Incorporated was used.

500 g of the first powder and 500 g of the second powder obtained above were shaken in a plastic bag for 3 minutes to prepare a mixed powder for CS.

The specific surface area and particle size of the first powder, second powder, and CS powder obtained in the examples and comparative examples were measured by the following method. The pore volume of the CS powder was also measured by the following method. The compositions of the first powder and second powder were also confirmed by the following method. The measurement results of the first powder and second powder are shown in Table 1, and the results of the CS powder are shown in Table 2.
<Method for measuring specific surface area by BET method>
The measurement was performed by the BET single point method using a fully automatic specific surface area meter Macsorb model-1201 manufactured by Mountech Co., Ltd. The gas used was a nitrogen/helium mixed gas (nitrogen 30 vol%).

<Conditions for X-ray diffraction measurement>
・Apparatus: Ultima IV (manufactured by Rigaku Corporation)
Radiation source: CuKα radiation Tube voltage: 40 kV
Tube current: 40mA
Scan speed: 2 degrees/min
Step: 0.02 degree Scan range: 2θ = 10 degrees to 90 degrees 50 g of the powder to be measured was collected and placed in an agate mortar. Ethanol was added dropwise in an amount sufficient to completely immerse the powder, and the powder was manually crushed in the agate mortar for 10 minutes. The powder was then dried, and the powder that had sieved to a mesh size of 250 μm or less was subjected to X-ray diffraction measurement.

<Pore volume by mercury intrusion porosimetry>
An Autopore IV manufactured by Micromeritics was used.
The range in which the pore diameter was 0.001 μm or more and 100 μm or less was measured, and the cumulative volume in the range in which the pore diameter was less than 0.3 μm was taken as pore volume IB, and the cumulative volume in the range in which the pore diameter was 0.3 μm or more and 2 μm or less was taken as pore volume IA.

<Method of measuring _D50 and particle size distribution>
_D50 and particle size distribution were measured by feeding the powder into the chamber of the sample circulator of a Microtrac 3300EXII manufactured by Nikkiso Co., Ltd., which contained 0.2% by mass of sodium hexametaphosphate aqueous solution, until the device determined that the concentration was appropriate. Note that since the powder was fed into the chamber of the sample circulator of the Microtrac 3300EXII, no dispersion treatment was performed using an external ultrasonic dispersion device, and no ultrasonic dispersion was performed inside the Microtrac 3300EXII.

The CS powders obtained in the Examples and Comparative Examples were subjected to the following evaluations. The results are shown in Table 3.
<Film formation evaluation>
The film formation evaluation was carried out according to the following procedure.
The deposition apparatus used was a high-pressure cold spray apparatus, CGT-KINETICS4000, and the substrate used was 25 mm x 25 mm x 5 mm aluminum A5052 that had been roughened using steel grit GH10 (manufactured by Shinto Kogyo Co., Ltd.).
Nitrogen was used as the working gas. The gas pressure was 3.0 MPa, the gas temperature was 500° C., and the deposition distance was 25 mm. The gun scanning speed was 10 mm/s.
Powder was fed to the nozzle using the device shown in Figure 1 according to the following procedure. First, 0.5 kg of powder was charged into powder feeder 11, which was then fed to tube 12 by vibration. The powder fed to tube 12 was carried to nozzle 14 by being accompanied by gas fed to nozzle 14 from gas pipe 13, and was then ejected from nozzle 14 toward substrate 15.
Regarding nozzle clogging during application, the powder supplyability (supply stability) when a single layer was formed on the surface of the above-mentioned aluminum substrate was observed and classified according to the following criteria.
◯: No clogging occurred during film formation.
×: Clogging occurred temporarily during film formation, or clogging occurred and film formation could not be continued.

Regarding the film formability, the cross section of the film was polished with diamond slurry, and then the cross section of the film and the substrate-film interface were observed using a scanning electron microscope, and classified according to the following criteria.
◯: A thick film having a thickness of 100 μm or more was obtained without cracks or peeling from the substrate.
×: Although a thick film having a thickness of 100 μm or more was obtained, cracks in the film or peeling from the substrate was observed, or the film deposition was insufficient, and a thick film having a thickness of 100 μm or more was not formed.

The hardness of the film was measured at 10 points under the following conditions and evaluated as an average value.
・Equipment: Shimadzu HMV-1
Pressure: HV0.1
Hold time: 10 seconds

50 g of the membrane was collected, placed in an agate mortar, and ethanol was added dropwise in an amount that completely immersed the membrane. The membrane was then crushed by hand with an agate pestle for 10 minutes, dried, and the membrane that passed through a sieve with an opening of 250 μm or less was subjected to X-ray diffraction measurement under the above conditions.

11 Powder feeder 12 Tube 13 Gas pipe 14 Nozzle 15 Substrate

Claims (10)

A powder for cold spray containing a compound of at least one film-forming element selected from Y, Yb, and Gd,
A powder for cold spray, in which at least one peak is observed in a pore size range of 0.3 μm or more and 2.0 μm or less in a distribution of pore volume versus pore size measured by mercury intrusion porosimetry, and the pore volume of pores with a pore size of less than 0.3 μm is 0.1 ml/g or more and 0.5 ml/g or less. 2. The powder for cold spray according to claim 1, having a BET specific surface area of 3 m ² /g or more and less than 30 ^{m 2} /g. The powder for cold spray according to claim 1 or 2, in which at least one peak is observed in the range of 1 μm to 10 μm in volume-based particle size distribution measured by a laser diffraction/scattering particle size distribution measurement method. Furthermore, the powder for cold spray according to claim 3 has at least one peak observed in the range of more than 10 μm and not more than 100 μm in the volume-based particle size distribution measured by a laser diffraction/scattering particle size distribution measurement method. The powder for cold spray according to any one of claims 1 to 4, comprising: a first powder containing a compound of the film-forming element and having a particle size ( _D50 ) at which an integrated volume from the small diameter side becomes 50% as measured by a laser diffraction/scattering particle size distribution measurement method, the _{particle size} being more than 10 μm and not more than 100 μm; and a second powder consisting of at least one of a rare earth compound, a silicon compound, and an aluminum compound and having a D50 of 1 μm or more and not more than 10 μm as measured by the laser diffraction/scattering particle size distribution measurement method. The powder for cold spray according to any one of claims 1 to 5, wherein the compound of at least one element selected from Y, Yb, and Gd is a fluoride or oxyfluoride. The powder for cold spray according to any one of claims 1 to 6, which contains a compound of Y. The powder for cold spray according to claim 5 , wherein the proportion of the second powder is 10% by mass or more and 90% by mass or less. A method for producing a film comprising a step of performing a cold spray method using the powder described in any one of claims 1 to 8. _{10. The method for producing a film according to claim 9, which produces a cold spray film comprising one or more selected from Y5O4F7 , YOF} and _YF3 and having a Vickers hardness of 70 or more and 500 or less.