JPH05132772A - Production of high density target material by powder method - Google Patents

Abstract

PURPOSE:To execute compacting to a target material as a sintered body having high density close to theoretical one as well as uniform in the compsn. and density value and high in strength, at the time of manufacturing a target material by a powder method by using powder forming eutectic crystals with each other at a low temp. and powder having a high difference in the m.p. with each other. CONSTITUTION:At the time of using >=two kinds of raw material powder forming eutectic crystals at a temp. range lower than that in the optimum compacting conditions, the mixed powder of the above raw material powder is subjected to preliminary compacting under the condition of temp. in which the liquid phase is formed or below, and after that, this preliminary compact is subjected to hot isostatic pressing treatment under the condition of temp. in which the liquid phase is partially formed. Furthermore, at the time of using >=two kinds of raw material powder having a high difference in the m.p. including powder having the m.p. lower than that in the optimum compacting conditions, the raw material powder is mechanically mixed with each other by a high energy mill, and after that, this mixed powder is subjected to hot isostatic pressing treatment under the condition of temp. in which the liquid phase is partially formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a high-density target material by a powder method, and more specifically to a target material used for thin film formation by sputtering in the fields of electronics, optics, precision machinery, cutting tools and the like. The present invention relates to a manufacturing method of.

[0002]

2. Description of the Related Art A target material used for forming a thin film in the fields of electronics, optics, precision machinery, cutting tools, etc. is usually manufactured by a melting method or a powder method. Further, since the compositions of these target materials are diverse, they are often manufactured by the powder method which allows relatively easy preparation of various compositions.

[0003]

The quality of the target material produced by the powder method is required to be of a dense density close to the theoretical density and to have a uniform composition and structure and high strength. However, in order to satisfy the requirement, a particular problem is in the case of solidifying and molding powders which form eutectic at low temperature or powders having a low melting point and having a large melting point difference.

That is, when solidification molding is performed in a temperature range below the temperature at which a liquid phase is generated as in ordinary sintering, the temperature cannot be raised, so these powders are sufficiently diffused and sintered to a density close to the theoretical density. It cannot be solidified and molded, and the obtained material becomes inferior in strength due to insufficient density. As a result, problems such as chipping during machining and chipping of the target support during use frequently occur, and since many voids are included, the sputtering processing speed during film formation is reduced and continuous multilayer films are formed. At the time of molding, the target material controls the flow of the line at a low rate to significantly reduce the productivity. On the other hand, if liquid phase sintering is used, it is possible to solidify and mold to a density close to the theoretical density, but the composition component of the molten one moves under pressure and is unevenly distributed, resulting in large variations in composition and density values and strength. Also, it is likely to be inferior in terms of use, and sometimes the film forming accuracy due to sputtering is lowered to make it unusable.

The present invention has been made to solve the above-mentioned conventional problems. For powders which produce eutectic crystals at low temperatures and for powders having a large melting point difference, the density is close to the theoretical density and the composition is high. Another object of the present invention is to provide a method for producing a high-density target material by the powder method, which can be solidified and molded as a sintered body having a uniform density value and high strength.

[0006]

In order to achieve the above object, the present invention has the following constitution. That is, the method for producing a high-density target material by the powder method according to claim 1, is a method of mixing two or more kinds of raw material powders which form eutectic in a temperature range lower than the optimum solidification molding condition for obtaining a density close to the theoretical density. Regarding the hot isostatic pressing of the powder for solidification and molding, the mixed powder is hot pressed or hot isostatically pressed under a temperature condition of a temperature at which a liquid phase occurs or less, and then prepressed, The preliminary pressure-molded product is subjected to hot isostatic pressing under a temperature condition in which a liquid phase is partially generated, and solidified and molded. Further, the method for producing a high-density target material by the powder method according to claim 2 includes a powder having a melting point lower than the optimum solidification molding condition for obtaining a density close to the theoretical density,
Regarding hot isostatic pressing of a mixed powder of two or more raw material powders having a large difference in melting point and solidification molding, the raw material powders are mechanically mixed with each other by a high energy mill, and then the mixed powder is partially Under a temperature condition in which a liquid phase is generated, hot isostatic pressing is performed and solidification molding is performed.

In the method for producing a high-density target material by the powder method according to the third aspect, the pressure applied in the hot isostatic pressing is 1000 kg / cm ² or less.

[0008]

The inventors of the present invention solidify and mold powders which form a eutectic at low temperature and powders having a large difference in melting point by using a hot isostatic pressing device and have a high density target material having a high density close to the theoretical density. As a method of obtaining the above, we considered hot isostatic pressing using a liquid phase. However, in this case, a density close to the theoretical density can be obtained by simply performing hot isostatic pressing under a temperature condition in which a liquid phase partially occurs, but compositional variations and variations in density values occur. , It turns out that a satisfactory product cannot be obtained.

Therefore, in order to understand the cause of the variation in the composition and the density value, the present inventor carries out hot isostatic pressing treatment on these powders by changing the pressurizing pressure and temperature variously and at the same time, We investigated the organization and obtained the following findings from the results. In the hot isostatic pressing process using the liquid phase,
The liquid phase fills and eliminates the voids existing inside, and promotes the sintering of powders with poor wettability due to the pressure. The components of the above composition excessively move and are unevenly distributed under high pressure, resulting in variations in composition and density values. On the other hand, when the pressurizing pressure and temperature are lowered, these variations tend to decrease, but it becomes difficult to obtain a high density close to the theoretical density. That is, in this method, the distribution and movement state of the liquid phase generated during the hot isostatic pressing process have a great influence on the internal quality of the obtained product.

As a result of further study from this point of view, these powders were subjected to hot isostatic pressing under a temperature condition in which a liquid phase was partially produced, and the powders were of a high density close to the theoretical density and a composition and In order to solidify and form a sintered body with a uniform density value, it is necessary to prevent the liquid composition from moving excessively while causing the liquid phase to have an even distribution. , It is effective to raise the density of the powders sufficiently under the solid phase, or to incorporate the liquid phase powder into the matrix powder that maintains the solid phase in advance. Reached

The present invention has been completed on the basis of the conditions grasped from the above-mentioned investigation and examination results. That is, in the invention according to claim 1, a mixed powder of two or more kinds of raw material powders which causes eutectic in a temperature range lower than the solidification molding condition optimal for obtaining a density close to the theoretical density is subjected to hot isostatic pressing. For solidification and molding, the mixed powder is pre-press-molded under a temperature condition below the temperature at which the liquid phase occurs, so the densities of the powders are sufficiently increased in the solid phase, which results in hot isostatic pressing. During the pressure treatment, while the liquid phase is generated under an even distribution, it suppresses the excessive movement of the melted composition, and there is no bias of the composition and a high density and uniform internal structure is obtained. It can be solidified and molded as a sintered body.

According to the second aspect of the invention, a mixture of two or more kinds of raw material powders having a large melting point difference is included, which includes a powder having a melting point lower than the optimum solidification molding condition for obtaining a density close to the theoretical density. Regarding solidification by hot isostatic pressing of powders, the raw material powders are mechanically mixed with each other by a high-energy mill. As a result, during hot isostatic pressing, the liquid phase is generated with an even distribution, while the molten composition is prevented from excessive movement, and there is no bias in the composition. It can be solidified and molded as a sintered body having a high density and uniform structure.

Further, when the pressurizing pressure is set high, the movement of the liquid phase is promoted. However, in the invention according to claim 3, the pressurizing force in the hot isostatic pressing process is 1000 kg / cm ² or less. In the hot isostatic pressing process, it is possible to more reliably prevent the melted component from excessively moving.

[0014]

EXAMPLES Examples of the method for producing a high density target material according to the present invention will be described below.

First Example: A Si-Al alloy forms a eutectic of Si and Al at a temperature of about 580 ° C., but a mixed powder of Si powder and Al powder is subjected to a temperature condition below the eutectic temperature. Even with hot isostatic pressing (hereinafter abbreviated as HIP), it is difficult to obtain a high density close to the theoretical density. In this example, a mixed powder of Si powder and Al powder having such characteristics has a uniform structure with no compositional deviation, and its density value is the theoretical density.
The goal was to obtain a high-density target material (Si-29wt% Al alloy) close to (2.44 g / cm ³ ).

First, a mixed powder of Si powder and Al powder, which were uniformly mixed so that the Si content was 71 wt% and the Al content was 29 wt%, was filled in a mild steel capsule and deaerated, and then placed in a HIP device. Pre-press molding was carried out under the conditions that the pressing pressure was 1800 kg / cm ² and the heating temperature was 550 ° C./2Hr. It should be noted that the heating temperature in this pre-press molding is about higher than the temperature at which the eutectic of Si and Al occurs.
While the temperature value is about 30 ° C lower, the pressurizing pressure sufficiently increases the density of the powders in the temperature range where eutectic does not occur.
It was set to a relatively high value.

Next, the pre-pressurized body is subjected to a pressurizing pressure.
HI under the conditions of 500kg / cm ² and heating temperature of 600 ℃ / 1Hr.
P treated. The heating temperature in this HIP treatment is a temperature value at which a part of the Al powder having a low melting point causes a liquid phase, while the pressurizing pressure is set as low as possible within the range in which the desired high density is obtained. However, the pressure prevented the movement of molten Al from being promoted.

On the other hand, for comparison, the same mixed powder as described above was similarly filled in a mild steel capsule and deaerated, and the pressurizing pressure was 1000 kg / cm ² and the heating temperature without prepressurizing. Was subjected to HIP treatment under the condition of 600 ° C./1 Hr.

Then, the density and structure of the sample collected from the obtained pressure-molded body were investigated in comparison with those of the comparative example. Note that the sample is an explanatory view thereof (a) in FIG.
As shown in the figure, the disk-shaped upper and lower sample materials (T) and (B) cut out for decapsulation by slicing the upper and lower parts of the pressure-molded body (S) before decapsulation, respectively. About (b), as shown in the figure, samples were taken from 6 places in total, 2 places on the outer circumference and 1 place on the center (No.1 to No.6 samples), and the cross-sectional structure of these samples was observed with a microscope. In addition, its density (g / cm ³ ) and Al content (wt%) were investigated. The results of investigation of the density and Al content are shown in [Table 1].

[0020]

[Table 1]

As shown in [Table 1], in the comparative example, a large deviation was observed in the Al content in the upper part and in the lower part. Was small and almost uniform, the density value was also higher than the theoretical value (2.44) calculated, and the variation was much smaller than that of the comparative example, which was a stable value.

On the other hand, the microscopic observation of the structure shows that the variation of the density value in the comparative example is related to both the composition distribution and the cavity, and particularly the comparative example showing a value lower than the theoretical value. Remaining cavities were clearly observed in the No. 3 sample. On the other hand, in the case of the present example, a uniform and dense structure in which no cavities were present was observed, and the excellent effect of the method of the present invention could be confirmed.

[Second Embodiment]: A Cr-Cu alloy is an alloy of metals having a large difference in melting point. Cr has a melting point of about 1800 ° C, whereas Cu has a remarkably low melting point of about 1080 ° C. Also, Cr
Even if the mixed powder of the powder and the Cu powder is subjected to the HIP treatment under the temperature condition below the melting point of Cu, it is difficult to obtain a high density close to the theoretical density. In this example, from the mixed powder of the Cr powder and the Cu powder having such characteristics, a uniform structure with no bias of the composition, the density value of which is theoretical density (7.257 g / c
The goal was to obtain a high-density target material (Cr-5wt% Cu alloy) close to m ³ ).

First, a mixed powder of Cr powder and Cu powder having a Cr content of 95 wt% and a Cu content of 5 wt% was put into an attritor (high energy ball mill) and subjected to a 24 hr mixing treatment at a rotation speed of 240 rpm. Then, the Cu powder was incorporated into the base Cr powder to form a composite. The mixing process using this attritor was performed at a rotational speed and for a time period that activated the surfaces of the Cr powder and the Cu powder, and generated sufficient energy to form a metal-to-metal bond between them to form a composite.

Next, this composite powder was filled in a mild steel capsule and deaerated, and then the pressurizing pressure was 1800 kg / c.
HIP treatment was carried out under the conditions of m ² and heating temperature of 1100 ° C./2Hr. The heating temperature in this HIP treatment was a temperature value at which a liquid phase was partially generated in Cu powder having a low melting point.

On the other hand, for comparison, the same powder mixture as above was filled and deaerated in a mild steel capsule without being mixed with an attritor, and the pressurizing pressure was 1800 kg / cm ² ,
The HIP treatment was performed under the condition that the heating temperature was 1300 ° C / 2Hr.

Then, disk-shaped upper and lower sample materials (T ') and (B') cut out from the obtained pressure-molded body in the same manner as in the above-mentioned first embodiment (FIG. 1). of
(c) As shown in the figure, samples were collected from 5 locations, 4 locations on the outer circumference and 1 location on the center, totaling 10 locations (No.1 to No.10 samples),
As in the first embodiment, the cross-sectional structures of these samples were observed with a microscope, and their density (g / cm ³ ) and Al content were determined.
(wt%) was investigated. The results of investigation of the density and Al content are shown in [Table 1].

[0028]

[Table 2]

In the case of the comparative example, the presence of cavities was not recognized at all by microscopic observation of the structure, but as shown in [Table 2], the Cu content greatly varied in each part, and the density value also varied in each part. Was changing drastically.

On the other hand, in the present embodiment, as is clear from [Table 2], the composition of each part is uniform, and the variation in the density value is small enough to be neglected. The structure observation also showed a uniform and dense structure in which no cavities were present, confirming the excellent effect of the method of the present invention.

In this example, the pressurizing pressure in the HIP process was set to a relatively high pressure value of 1800 kg / cm ² , but the composite powder obtained by the mixing process in the attritor was such that This is because the layered structure is insensitive to pressure, and the uniformity of composition can be stably obtained even under a slightly higher pressure. However, depending on the type of powder to be applied and the temperature of the HIP treatment that accompanies it, the movement of the molten composition under that pressure may be promoted.
It is more desirable to set it to kg / cm ² or less. In addition, since the powder surface is activated in the composite powder that has been mixed with an attritor, as long as it is HIP-treated under the temperature conditions in which a liquid phase is partially generated even under a pressure of 1000 kg / cm ² or less, the theoretical It can be solidified and molded as a high-density sintered body close to the density.

[0032]

As described above, according to the method for producing a high-density target material by the powder method according to the present invention, the theory can be applied to the powders which form eutectic at low temperature and the powders having a large melting point difference. It can be solidified and molded as a high-strength sintered body with a high density close to the density and a uniform composition and density value. Therefore, the composition range of the target material can be expanded and the high density which was not obtained by the conventional technology. It is possible to manufacture various target materials, and it is possible to greatly contribute to expansion of applications and improvement of performance of the target material by the powder method.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a sampling position of a sample according to an example of the present invention.

[Explanation of symbols]

 (S) --Press-formed body (T) --Upper sample material (B) --Lower sample material (T ') --Upper sample material (B') --Lower sample material

Claims (3)

[Claims] 1. A mixed powder of two or more kinds of raw material powders which form a eutectic in a temperature range lower than an optimum solidification molding condition for obtaining a density close to a theoretical density, is subjected to hot isostatic pressing to be solidified and molded. With respect to the mixed powder, after hot pressing or hot isostatic pressing by hot pressing under a temperature condition not higher than a temperature at which a liquid phase is generated, the preliminary pressure molding is performed under a temperature condition where a liquid phase is partially generated. A method for producing a high-density target material by a powder method, which comprises hot isostatic pressing and solidifying and molding under the same. 2. Hot isostatic pressing of a mixed powder of two or more raw material powders having a large melting point difference, including a powder having a melting point lower than the optimum solidification molding condition for obtaining a density close to the theoretical density. Regarding the treatment and solidification molding, the raw material powders are mechanically mixed with each other by a high energy mill, and then the mixed powder is hot isostatically pressed and solidified and molded under a temperature condition where a liquid phase is partially generated. A method for producing a high-density target material by the powder method, which is characterized by the above. 3. The method for producing a high-density target material by the powder method according to claim 1, wherein the pressurizing pressure in the hot isostatic pressing process is 1000 kg / cm ² or less.