JPS63235407A - Production of highly brittle alloy target for sputtering - Google Patents

Abstract

PURPOSE:To suppress segregation in a target and to reduce voids as well as to lower the concn. of oxygen by combining chips obtd. by cutting an ingot so as to provided a prescribed shape and by subjecting the combined chips to hot isostatic pressing in a sealed state. CONSTITUTION:A prescribed alloy is melted and cast into an ingot in vacuum or in an inert gaseous atmosphere. The ingot is cut into chips and the chips are combined to form a flat plate. This plate is sealed in a vessel for hot isostatic pressing and subjected to hot isostatic pressing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a flat plate made of a highly brittle alloy, and particularly to a method for manufacturing a large diameter sputtering target made of a highly brittle alloy.

[Conventional technology]

The general manufacturing method for sputtering targets is to cast an ingot with a predetermined size and cut out a target-shaped disk from the ingot, or to shape the ingot into a predetermined shape by hot working or cold working. A method of processing was used. In addition, as a special example, JP-A-61-60803
As disclosed in the above publication, a method is known in which a sputtering target is manufactured by subjecting powder obtained by pulverizing an alloy to hot isostatic pressing in a high-temperature, high-pressure gas atmosphere.

Usually, the characteristics required of a target are that it has a desired composition, no segregation, and fine crystal powder. Furthermore, in addition to low impurities, there is now a need to reduce the concentration of oxygen that degrades the properties of the membrane.

Currently, the required target diameter is about 20 meters. For this reason, targets are manufactured by manufacturing an ingot with a diameter larger than the above diameter and cutting it into a predetermined shape, or by hot working or cold working for metal alloys with good workability. There is. Casting an ingot of such a size is likely to cause various casting defects such as voids and segregation, and measures to prevent this, such as rapid cooling, are taken. However, metal compounds such as sendust, which is a typical soft magnetic material, are brittle and susceptible to casting cracks like ceramics. Therefore, it is not considered to be an appropriate method to produce an ingot from which target plates with a diameter of about 20 mm can be cut out, taking into consideration the casting defects described above. Therefore, for metal alloys that exhibit high brittleness, hot pressing is performed after the ingot is crushed into powder and then filled into a target-shaped mold, or the ingot is vacuum-sealed in a metal container and left hot. Manufactured by applying hydraulic press treatment. However, when using such a powder metallurgy method, the surface of the powder is oxidized, so it is handled in an inert gas, but it is important to avoid increasing the oxygen concentration higher than that of the ingot. I can't. The concentration of oxygen in the ingot can be suppressed to 30 to 50 ppm or less by weight by increasing the purity of the raw materials and selecting melting conditions. However, the oxygen concentration contained in the target manufactured from the powder is 3 to 10 ppm higher than the oxygen concentration contained in the raw material ingot, which is undesirable.

For this reason, it is effective to set the particle size of the powder to several hundred μm, which is larger than the several tens of μm used in normal powder metallurgy, but on the other hand, the crystal grains of the target obtained with coarse particles are This causes problems such as the formation of voids and the formation of voids.

[Problem that the invention seeks to solve]

As mentioned above, in the conventional manufacturing method of sputtering targets, the powder obtained by crushing an alloy (ingot) is subjected to hot isostatic pressing treatment in a high temperature and high pressure gas atmosphere, that is, sintering. Although this method has the advantage of having a uniform composition and fine crystal grains, on the other hand, since the powder is pressed, the concentration of oxides and gases (oxygen) on the surface is high. In addition, when using coarse powder, there were problems such as the tendency to form rough pores.

This invention was made to solve this problem, and suppresses the increase in the oxygen concentration contained in the target,
The purpose of the present invention is to obtain a method for manufacturing a highly brittle alloy sputtering target that can simultaneously control the composition and reduce segregation and vacancies.

[Means for solving problems]

The method for manufacturing a highly brittle alloy sputtering target according to the present invention involves cutting an ingot into small pieces, combining the pieces into a predetermined shape, filling a metal container and sealing it, and then subjecting it to hot isostatic pressing. It is manufactured by

[Effect]

In the method for manufacturing a highly brittle alloy sputtering target of the present invention, the thickness t of the plate required as the target material is 2 to 5 m, and the diameter dimension φ of the target is 2 m.
Since it is uneconomical to manufacture from an ingot with a length of 00m or more, the ingot is cut into small pieces, assembled into a predetermined shape, filled into a metal container and sealed, and then hot-static. It is manufactured using a hydraulic press process. This eliminates the need for more ingots than necessary.
Casting cracks in the highly brittle alloy do not occur, and an increase in the oxygen concentration contained in the target can be suppressed.

〔Example〕

FIG. 1 is a diagram for explaining a manufacturing process in a method for manufacturing a highly brittle alloy sputtering target, which is an embodiment of the present invention. In the figure, 1 is a container made of metal such as stainless steel, 2 is the top lid of the metal container 1, 3 is a deaeration port, and 4 is a small piece obtained by cutting an ingot.

In the method for manufacturing a highly brittle alloy sputtering target according to the present invention, for example, the alloy has a purity of 99.99%.
% or more of F, , AI, Si is F,
-83wt%, Al 7wt%, and 8i 10wt% are melted in vacuum using high frequency, and cast into a 101-width water-cooled mold. The ingot thus obtained was processed at 25wX using a wire saw, electric discharge machine, or laser machine.
Cut into a small piece 4 of 25m x 5m, and this small piece 4
As shown in the figure, metal container 1 (inner volume 200TlrII
200 mm x 5 mm), and after welding the top lid 2 to the metal container 1, it is evacuated through the deaeration port 3 and sealed. Here, when filling the small pieces 4 into the metal container 1, BN is applied as a mold release agent to prevent welding of the small pieces 4 and stainless steel, which is the material of the metal container 1.

The small pieces 4 filled in the metal container 1 as described above are heated to 1200° C. by a hot isostatic press device (not shown).
, pressurized 7?0 for 1 hour under the condition of 2000Kgf15I
Apply heat treatment. The thus obtained sendust flat plate is cut into a disk having a diameter of 203 mm using a wire saw, and the surface is polished to finish the target. Here, the oxygen concentration contained in the obtained sendust target is about 30 ppm, which is approximately the same as the oxygen concentration contained in the ingot.

As mentioned above, in the method of manufacturing a target using a highly brittle alloy, it is important to minimize compositional deviation and segregation with respect to the highly brittle alloy, and to reduce the oxygen concentration contained therein. Currently, the diameter required for targets reaches 20 countries, so in order to suppress segregation with such a diameter, a rapid cooling process must be performed during casting. However, the rapid cooling process causes cracking and casting cracks in highly brittle alloys, making it extremely difficult to cast target-shaped discs. For this reason, a method of manufacturing the target by crushing and sintering the ingot has been considered, but crushing the ingot makes the powder surface more likely to oxidize, increasing the acid content. result.

On the other hand, the method for manufacturing a target according to the present invention is not affected by the shape of the target, which is a product obtained from an ingot, and is capable of reducing compositional deviations and segregation, and reducing the oxygen concentration contained therein. For this reason, casting defects are prevented and it is more economical than casting an ingot with a diameter of 203 or more, which has a large target diameter. Furthermore, the combination of the small pieces 4 cut from the ingot further reduces small segregations obtained by rapid cooling treatment.

In addition, a hot isostatic press device is used to obtain a flat plate necessary for the diameter of the target from the small piece 4. Therefore, defects such as holes in the completed target are likely to occur on the joint surfaces of the small pieces 4.

Since the pores in each piece 4 are eliminated by hot isostatic pressing, it is important to reduce the gap between each piece 4 as much as possible and to reduce the bonding length per unit area.

Therefore, it is not appropriate to use a small piece 4 that is too small relative to the diameter of the target.

On the other hand, increasing the size of the small piece 4 may lead to segregation and increase in the size of the ingot, resulting in casting cracks.
For 1), (10-50) diameter x 5 m
It is appropriate to set the value to (thickness).

The container 1 made of metal such as stainless steel has a flat shape reflecting the shape of the target as shown in FIG.
In order to reduce the degree of adhesion between the plates, a stainless steel plate with a thickness of 5111 mm is used, which has been surface-polished. After the upper lid 2 is welded to the four sides of the metal container 1, each metal container 1 is heated for dehydration, etc., and then evacuated from the stainless steel pipe serving as the degassing port 3 to 1×10 torr or less to seal it.

On the surface of the target obtained in this way, some pores can be seen on the fused surface of the small pieces 4, but these pores are all less than 100 μm in size, and there is no need to use it as a target. It's not a problem.

In addition, in the method for manufacturing a target according to the present invention,
The manufacturing method from the small piece 4 obtained by cutting the ingot is as follows:
It is effective not only for highly brittle alloys but also for C0-Zr-Nb, which is the material for thin film heads for perpendicular magnetic recording.

As described above, in the method of manufacturing a target according to the present invention, the problem of manufacturing from a combination of small pieces 4 is to prevent compositional deviation and segregation.

However, on the other hand, it is not possible to obtain ingots with exactly the same composition, and in order to meet the demands of targets with slightly different compositions, the composition must be controlled in some way.

As one method for this purpose, manufacturing from a combination of small pieces 4 is effective, and by combining the small pieces 4 so as to be macroscopically uniform, a target having a desired composition can be easily manufactured.

〔Effect of the invention〕

As explained above, the present invention is a method for manufacturing a highly brittle alloy sputtering target, in which an ingot is cut into small pieces, the pieces are assembled into a predetermined shape, filled in a metal container, sealed, and then hot-sealed. Since the target is manufactured using hydraulic press treatment, the oxygen contained in the target
! This has excellent effects in that it is possible to suppress the increase in the amount of carbon dioxide, simultaneously control the composition, reduce segregation and pores, and manufacture a target at low cost.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining a manufacturing process in a method for manufacturing a highly brittle alloy sputtering target, which is an embodiment of the present invention. In the figure, 1... gold f4!1 container, 2... upper lid, 3... deaeration port, 4... small piece.

Claims (1)

[Claims] The ingot melted in vacuum or in an inert gas atmosphere is cut into small pieces, the pieces are combined into a flat plate, sealed in a hot isostatic press container, and then subjected to hot isostatic press treatment. A method for producing a highly brittle alloy sputtering target, characterized by: