JPH07238303A - Method for forming metallic target material having high melting point - Google Patents

Abstract

PURPOSE:To mass-produce high density compacts each uniform in particle diameter and having a large diameter, especially a high purity target material in a short time. CONSTITUTION:A proper amt. of granular or powdery starting material made of a metal or alloy having a high m.p. of >=1,800 deg.C is housed in a metallic capsule. After degassing and hermetical sealing, this capsule is heated, highly pressed in dies for compression, taken out and cooled. A metallic part derived from the capsule is removed and the objective high density compact is obtd. The capsule is made of a malleable metal, the heating temp. of the capsule is regulated to >=1,000 deg.C and the capsule is highly pressed under Fkgf/mm<2> pressure [F>=1.2XFT (FT is the strength of the material of the capsule at the heating temp. of the capsule heated to >=1,000 deg.C)].

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming various sputtering target materials used in the process of manufacturing thin films such as semiconductors, photomasks, hard disks, and resistance films, that is, a high-density lump formed by compression molding of raw materials. With regard to the molding method of the molded body, it is a material that is difficult to produce by the casting method because of its high melting point, a material that is castable but difficult to avoid uneven crystal grains due to casting defects and solidification segregation, or high purity The present invention relates to a method for forming a high-melting-point metal target material by forming a material or the like that needs to be formed without remelting a high-purity raw material in order to obtain a high density into a uniform lump of crystal grains and in mass production.

[0002]

2. Description of the Related Art Conventionally, since pure metals Cr, W, Mo and Nb have high melting points, it has been difficult to form a sputtering target material by a casting method. Therefore, Cr, W, Mo, Nb, which are pure metals having such a high melting point, and alloys of these refractory metals are molded by the isotropic hot isostatic pressing (commonly called "HIP") method. . However, the HIP method is generally industrially time-consuming and costly, and cannot be said to be suitable for mass production. Further, although a special melting and casting method is used only in part, it is costly and it is difficult to avoid the generation of uneven crystal grains due to the difference in cooling rate during solidification.

In addition, in the HIP method, there is a restriction on the size of the apparatus, and therefore the size of the target material to be manufactured is about 12 inches in diameter at the maximum, and is not limited to the diameter of 12 inches or less. There is.

The pure metal target material is required to have a high purity of about 3 nines. Since the melting temperature is extremely high in the melting casting method using refractory, it is unavoidable to react with the crucible, which is a refractory, and it is mixed into the target material as impurities such as reaction products of refractory and metals and oxygen. However, it was difficult to manufacture a high-purity target material.

In the conventional melt casting method as described above, it is difficult to avoid the uneven crystal grains caused by the difference in the cooling rate depending on the portion of the ingot generated during solidification, and therefore, the method for producing the agglomerated material having a uniform crystal grain size. Was desired to be developed.

As described above, the HIP method generally takes time and cost industrially and is not suitable for mass production. Particularly, the time required for one cycle from the start of heating to pressurization and cooling is several times. It has been desired to develop a manufacturing method which requires time and can be molded in a shorter time.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for mass-producing a large-sized high-density compact having a uniform crystal grain size, particularly a high-purity target material in a short time. Is.

[0008]

The means for solving the problems of the present invention are to use an appropriate amount of powder or briquette-like raw material of a refractory metal or alloy having a melting point of 1800 ° C. or higher produced by an electrolysis method or by an electrolysis method. Generated 1800 ℃
An appropriate amount of the above-mentioned high-melting-point metal or alloy powder that has been sintered and preformed into small pieces is placed in a metal capsule in an appropriate amount, degassed and sealed, and the capsule is heated to produce a compression metal. A high-melting-point metal target material forming method characterized by obtaining a high-density formed body of the above raw material by removing the metal portion derived from the capsule by strongly pressing in a mold, then taking out and cooling this capsule, Also, the metal capsule in the above is a malleable metal capsule in the method for forming a high melting point metal target material according to claim 1, or the heating temperature of the capsule in the above is 1000 ° C. The method is a method for forming a high-melting-point metal target material, which is characterized in that the heating temperature is as described above.
kgf / mm ² {F = 1.2 × F _T (F _T is 1000 ° C
The strength of the material at the heating temperature of the capsule heated above)} or more} is the method for forming a high melting point metal target material.

[0009]

In the method for forming a high melting point metal target material of the present invention, granular or powdery raw materials produced by various production methods such as atomizing method and pulverizing method are enclosed and sealed in a malleable metal capsule, and the capsule is heated. Then, the mixture is subjected to strong pressure in a press-compression die, and then the capsule is taken out and cooled to remove the metal portion derived from the capsule to obtain a uniform high-density molded product of the above raw material.

The malleable metal capsule used here may be any material that can be easily compositionally deformed by heat, such as machine structural steel and stainless steel, as long as it is inexpensive and easily available. Good.

The filling density of the raw material in the malleable metal capsule is preferably high, and usually 50% or more of the true density. If the packing density is less than 50%, the malleable metal capsule will buckle during pressure molding, and a part of the malleable metal capsule will be trapped inside the desired high-density molded body as impurities. There is a risk of contamination.

The degree of vacuum for degassing and sealing the capsule filled with the granular or powdery raw material may be a vacuum degree of 10 ^-1 Torr or less. If the degree of vacuum is lower than this and the pressure is kept close to the atmospheric pressure, it is dangerous because the internal pressure of the capsule rises at the time of heating up before the hot pressing in the next step,
Further, the filled high-purity raw material reacts with oxygen remaining inside the capsule to increase the oxygen value of the target high-density molded article, so that a high-purity high-density molded article cannot be obtained.

The hot strengths of pure W, pure Mo and pure Nb are shown in FIG.
~ The values are clarified as shown in Fig. 4. The strength of pure Cr, pure W, pure Mo, and pure Nb at the capsule heating temperature of 1000 ° C. is 180 MPa, 200 MPa, 1
80 MPa, 65 MPa, which is lower than the pressure generated during pressurization of hot working techniques that are usually used industrially,
It can be seen that hot plastic deformation is possible at this temperature. Therefore, pressure Fkgf / mm ² {F = 1.2 × F _T (where F _T is 1000
Strength at heating temperature of capsules heated above ℃)}
If the above-mentioned strong pressure is applied, the filled raw material is effectively plastically deformed.

Needless to say, the upper limit of the capsule heating temperature is lower than the melting point of the metal that is the capsule material.

[0015]

【Example】

Example 1. Approximately 1 inch square pure W briquette with an outer diameter of 20
54 kg of a 6 mm thick, 4 mm thick, 150 mm long carbon steel capsule was filled and degassed and sealed by TIG welding at a vacuum degree of 2 × 10 ^-2 Torr. The capsule was heated to 1300 ° C., inserted into a container having an inner diameter of 215 mm, punched, and a total pressure of 2000 tons was applied for about 5 seconds by a pressing machine. After cooling, it is cut into a disc shape into a disc body, and the metal portion derived from the capsule on the outer periphery of the disc body is cut off with a wire cut,
After that, both sides of the disc body are polished with a flat surface polishing machine to obtain a diameter of 20.
A target material for 3.2 mm, commonly called 8 inches, was obtained. When a part of the target material was cut out and the density thereof was measured by the Archimedes method, the density was not different from the density of the pure W ingot material, and the crystal grain size was uniform.

Example 2. About 1 inch square of pure Mo briquette was filled in 28 kg in a capsule made of carbon steel having an outer diameter of 206 mm, a wall thickness of 4 mm and a length of 150 mm, and degassed and sealed by TIG welding at a vacuum degree of 3 × 10 ^-2 Torr. The capsule was heated to 1250 ° C., inserted into a container having an inner diameter of 215 mm, punched, and a total pressure of 2000 tons was applied for about 5 seconds by a pressing machine. After cooling, it is cut into a disc shape to make a disc body, and the metal part derived from the capsule on the outer periphery of the disc body is cut by wire cutting, and then both sides of the disc body are polished by a plane polishing machine, and the diameter is 203.2 mm. A so-called 8-inch target material was obtained. When a part of the target material was cut out and the density thereof was measured by the Archimedes method, the density was not different from the density of the ingot material of pure Mo, and the crystal grain size was uniform.

Embodiment 3. About 1 inch square briquette of pure Nb was filled in a capsule made of carbon steel having an outer diameter of 206 mm, a wall thickness of 4 mm and a length of 150 mm (24 kg), and degassed and sealed by TIG welding at a vacuum degree of 3 × 10 ^-2 Torr. The capsule was heated to 1280 ° C., inserted into a container having an inner diameter of 215 mm, punched, and a total pressure of 2000 tons was applied for about 5 seconds by a press machine. After cooling, it is cut into a disc shape to make a disc body, and the metal part derived from the capsule on the outer periphery of the disc body is cut by wire cutting, and then both sides of the disc body are polished by a plane polishing machine, and the diameter is 203.2 mm. A so-called 8-inch target material was obtained. When a part of the target material was cut out and the density thereof was measured by the Archimedes method, the density was not different from the density of the pure Nb ingot material, and the crystal grain size was uniform.

Example 4. About 1 inch square of pure Cr briquette was filled into a carbon steel capsule with an outer diameter of 206 mm, a wall thickness of 4 mm, and a length of 150 mm in an amount of 19.9 kg, and 2 × 10 ^-2 Torr.
It was degassed and sealed by TIG welding at a vacuum degree of. The capsule was heated to 1100 ° C., inserted into a container having an inner diameter of 215 mm, punched, and a total pressure of 2000 tons was applied for about 5 seconds by a pressing machine. After cooling, it is cut into a disc shape to make a disc body, and the metal part derived from the capsule on the outer periphery of the disc body is cut by wire cutting, and then both sides of the disc body are polished by a plane polishing machine, and the diameter is 203.2 mm. A so-called 8-inch target material was obtained. When a part of the target material was cut out and the density thereof was measured by the Archimedes method, the density was not different from the density of the pure Cr ingot material, and the crystal grain size was uniform. The micrograph of the obtained target material is shown in FIG.
a) is a microstructure of the billet outer peripheral portion, and b) is a microstructure of the billet central portion.

Example 5. About 1 inch square of pure Cr briquette was filled in a carbon steel capsule having an outer diameter of 390 mm, a wall thickness of 4 mm and a length of 200 mm of 99 kg, and was degassed and sealed by TIG welding at a vacuum degree of 3 × 10 ^-2 Torr. This capsule is heated to 1100 ° C, inserted into a container with an inner diameter of 405 mm, punched, and a total pressure of 2000 tons is applied with a press machine to about 1
It took 0 seconds. After cooling, the metal part derived from the capsule on the outer periphery of the cylindrical body was removed by a lathe, and cut into a disc shape into a disc body, and then both sides of the disc body were polished by a flat surface polishing machine to obtain a diameter of 3
A target material for 81 mm, commonly called 15 inches, was obtained. When a part of the target material was cut out and the density thereof was measured by the Archimedes method, the density was not different from that of the pure Cr ingot material, and the crystal grain size was uniform.

Example 6. The alloy ratio is 20% by weight of Cr,
Mo is composed of two elements of 80% by weight and has a melting point of 1870 ° C.
And a CrMo alloy powder with a particle size of 1 mm or less has an outer diameter of 20
30 kg of a 6 mm thick, 4 mm thick, 150 mm long carbon steel capsule was filled and degassed and sealed by TIG welding at a vacuum degree of 3 × 10 ^-2 Torr. The capsule was heated to 1200 ° C., inserted into a container having an inner diameter of 215 mm, punched, and a total pressure of 2000 tons was applied for about 10 seconds by a pressing machine. After cooling, the metal part derived from the capsule on the outer periphery of the cylindrical body was removed by a lathe, and cut into a disk shape into a disk body, and then both surfaces of the disk body were polished by a flat surface polishing machine, and a diameter of 203.2 mm, commonly known as 8 I got a target material for inches. When a part of the target material was cut out and its density was measured by the Archimedes method, the density was not different from that of the CrMo alloy ingot,
The crystal grain size was uniform.

Example 7. The alloy ratio is 10% by weight of Cr,
Mo is composed of 90% by weight of two elements and has a melting point of 1700 ° C.
And a CrMo alloy powder with a particle size of 1 mm or less has an outer diameter of 20
23 kg of a 6 mm thick, 4 mm thick, 150 mm long carbon steel capsule was filled and degassed and sealed by TIG welding at a vacuum degree of 3 × 10 ^-2 Torr. The capsule was heated to 1200 ° C., inserted into a container having an inner diameter of 215 mm, punched, and a total pressure of 2000 tons was applied for about 10 seconds by a press machine. After cooling, the metal part derived from the capsule on the outer periphery of the cylindrical body was removed by a lathe, and cut into a disk shape into a disk body, and then both surfaces of the disk body were polished by a flat surface polishing machine, and a diameter of 203.2 mm, commonly known as 8 I got a target material for inches. When a part of the target material was cut out and its density was measured by the Archimedes method, the density was not different from that of the CrMo alloy ingot,
The crystal grain size was uniform.

Example 8. Approximately 1 inch square pure Cr briquette with external dimensions of 70mm in height, 235mm in width, 4mm in wall thickness and 2 in length.
Filling 11.7 kg in a capsule made of carbon steel of 00 mm, 3 × 1
It was degassed and sealed by TIG welding at a vacuum degree of 0 ^-2 Torr. This capsule is heated to 1100 ° C and the inside dimension is 75
mm, insert it in the container of 245 mm in width, hit the punch,
A total pressure of 2000 tons was applied for about 10 seconds with the press machine. This billet is taken out of the container, and after cooling, a rectangular parallelepiped is cut into a plate shape by a cutting machine, the outer peripheral portion of the plate is further cut, and then both sides of the plate are polished by a flat surface polishing machine, and the length is 50.8 mm, width 2
A target material for 2 inch x 10 inch having a thickness of 03.2 mm and a thickness of 6 mm was obtained. A part of the target material was cut out and its density was measured by the Archimedes method.
The density was not different from the density of the ingot, and the crystal grains were uniform.

Example 9. About 1 inch square of pure Cr briquette was filled into a carbon steel capsule having an outer diameter of 390 mm, a wall thickness of 4 mm and a length of 200 mm of 99 kg, which was degassed and sealed by TIG welding at a vacuum degree of 3 × 10 ^-2 Torr. 1 capsule
Heat to 100 ° C, insert into a container with an inner diameter of 405 mm, apply a punch, and press the press to a total pressure of 2000 tons of about 1
It took 0 seconds. Take this billet out of the container, and put the outer circumference on the anvil of a press machine in a length of 280 mm and a width of 420 mm.
mm, thickness 142 mm. After cooling, the rectangular parallelepiped is cut into a plate shape with a cutting machine, the outer peripheral portion of the plate is further cut, and then both sides of the plate are polished with a flat surface polishing machine to obtain a length of 254 mm and a width of 38 mm.
A target material having a size of 1 mm and a thickness of 6 mm for commonly known 10 inches × 15 inches was obtained. When a part of the target material was cut out and the density thereof was measured by the Archimedes method, the density was not different from that of the pure Cr ingot material, and the crystal grains were uniform.

As described above, according to the present invention, the granular or powdery raw material is housed and sealed in a malleable metal capsule, and the capsule is heated and strongly pressed in a press-compression die, and then The capsule is taken out and cooled, and the metal part derived from the capsule is removed to obtain a uniform high-density molded product of the above-mentioned raw material, so that there is no irregularity of crystal grains in the melting method, and a uniform crystal grain size is obtained. The target material which is a high-density molded body can be obtained, and the present invention can obtain a high-density molded body in a short time and at low cost without requiring time and cost as in the HIP method, and is suitable for mass production. ing.
Further, according to the present invention, it is possible to easily manufacture a target material that is a high-density molded body having a large diameter of 12 inches or more.

[Brief description of drawings]

FIG. 1 is a photomicrograph showing the metallographic structure of a pure Cr target material, where a) shows the microstructure around the billet and b) shows the microstructure at the center of the billet.

FIG. 2 is a graph showing the relationship between temperature and strength of pure W.

FIG. 3 is a graph showing the relationship between temperature and strength of pure Mo.

FIG. 4 is a graph showing a relationship between temperature and strength of pure Nb.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshikazu Tanaka 3007 Nakajima, Nakajima, Shikama-ku, Himeji City, Hyogo Prefecture Sanyo Special Steel Co., Ltd.

Claims (4)

[Claims] 1. An appropriate amount of a granular or powdery raw material of a high melting point metal or alloy having a melting point of 1800 ° C. or more is contained in a metal capsule and degassed and hermetically sealed, and the capsule is heated to be pressurized and compressed in a mold. A high-melting-point metal target material forming method, characterized in that a high-density formed body of the above raw material is obtained by removing the metal part derived from the capsule by removing the metal part derived from the capsule. 2. The method for molding a high melting point metal target material according to claim 1, wherein the metal capsule is a malleable metal capsule. 3. The heating temperature for heating the capsule is 1000.
3. The method for forming a refractory metal target material according to claim 1, wherein the temperature is not less than 0 ° C. 4. The pressure for applying a strong pressure in the pressure compression mold is Fkg.
The pressure of f / mm ² {F = 1.2 × F _T (where F _T is the strength of the material at the heating temperature of the capsule heated to 1000 ° C. or more)} or more}. A method for forming a refractory metal target material according to any one of claims.