JP2007217723A - Method for manufacturing pressure-sintered target material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a pressure-sintered target material by which a plurality of sintered compacts being close to a final shape can be obtained. <P>SOLUTION: The method for manufacturing the pressure-sintered target material includes: filling a raw material powder composed mainly of refractory metal elements and plate-like spacers each having, in its central part, a plane surface more recessed than its peripheral part into the mold of a hot press in such a way that they are alternately laminated with respect to the axial direction of pressure application; carrying out pressure sintering; and separating the spacers to obtain the plurality of sintered compacts. Moreover, the method for manufacturing the pressure-sintered target material in which the spacers are composed of silicon carbide is also provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing a target material by pressure sintering.

  A sputtering method, which is a kind of physical vapor deposition method for forming a thin film, uses a target material as a base material. Generally, as a method for producing a target material, a method of processing an ingot obtained by melting and casting a raw material into a plate shape, or a method of processing a sintered body obtained by sintering raw material powder into a plate shape Has been adopted. In particular, a target material mainly composed of a refractory metal element has a high melting temperature and is difficult to cast. Therefore, a sintered body produced by a powder sintering method is used.

At present, in a target material manufactured by a powder sintering method, a method for producing a large number of target materials in a single sintering process has been attempted in order to increase productivity. For example, in a hot press which is a kind of pressure sintering method, a raw material powder and a plate-like graphite spacer are alternately stacked and filled in a mold, and a plurality of target materials are simultaneously sintered by hot pressing. A method is disclosed (for example, see Patent Document 1).
JP 2005-60745 A

In the method for producing a target material described in Patent Document 1, a plurality of target materials can be obtained by one-time pressure sintering by alternately filling a plurality of raw material powders and plate-like spacers into a hot-press carbon mold. Since it can be manufactured, it is advantageous in improving the production efficiency.
On the other hand, the target material has been conventionally attached to the sputtering apparatus in a state where the target material is bonded to a backing plate made of copper or aluminum via a brazing material. Recently, as shown in FIG. In the peripheral part of the material 1, the thing of the shape which formed the collar part 2 is increasing. When the target material having such a shape is produced from a flat plate-like sintered body obtained by the method described in Patent Document 1, the collar portion must be formed by cutting, and the cutting time is reduced. There is an unfavorable problem in terms of production efficiency, such as an increase or a portion that is removed by cutting, resulting in a decrease in material yield.

  An object of the present invention is made in view of the above-described problems, and is to provide a method for producing a pressure sintered target material that can obtain a plurality of sintered bodies close to the final shape.

As a result of examining the above problems, the present inventor has found that the spacer filled with the raw material powder in the hot press mold can be improved to have a specific shape, and has reached the present invention.
That is, the present invention provides a hot-press mold in which a raw material powder mainly composed of a refractory metal element and a plate-like spacer having a flat surface recessed from the peripheral part in the central part with respect to the pressure axis direction. This is a method for producing a pressure sintered target material, in which a plurality of sintered bodies are obtained by separating and filling the spacers after alternately laminating and filling and then pressure sintering.
Preferably, the spacer is made of silicon carbide. Also preferably, a film made of silicon carbide is formed on the surface of the spacer. Preferably, the spacer has a surface roughness (Ra) of 0.5 μm or less. Preferably, the refractory metal element is Ru.

  The method for producing a pressure-sintered target material of the present invention can produce sintered bodies close to a plurality of final shapes by using a plate-like spacer having a flat surface recessed from the peripheral part in the central part. Therefore, the target material can be stably manufactured at a low cost.

As described above, the important feature of the present invention is that the spacer has a plate-like shape having a flat surface recessed from the peripheral portion at the central portion as shown in the schematic diagram of FIG. Filling the spacer with the above shape together with the raw material powder into the hot press mold, the target is formed when a target material having a stepped shape with respect to the central portion is formed in the peripheral portion and a step is formed. A sintered body close to the final shape of the material can be manufactured.
In the present invention, as shown in FIG. 3, the spacer 3 and the raw material powder 5 made of a refractory metal element are alternately stacked in the hot press mold 4 in the direction of the pressing axis. To do. Thereafter, as shown in FIG. 4, while the entire mold is heated by an external heater and subjected to pressure sintering through the upper punch 7 and the lower punch 6, the obtained sintered body 8 and the spacer 3 are separated. Thus, a sintered body close to a plurality of final shapes can be obtained at a time.

  Note that the raw material powder mainly composed of a refractory metal element is made of a composition mainly composed of a refractory metal element having a melting point higher than about 1535 ° C. of Fe, and the target material can be produced by a melt casting method. This is because it is particularly difficult and the powder sintering method is suitable. Examples of the raw material powder mainly composed of a refractory metal element include pure metal powders such as Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ru, Rh, Pd, Re, Os, Ir, and Pt. Alternatively, a mixed powder or alloy powder containing these elements at 50 atomic% or more can be used.

  Moreover, the shape of the spacer of this invention should just be a plate shape which has the plane recessed from the peripheral part in the center part, and the side surface which leads to the flat surface recessed from the peripheral part is shown in FIG. 2 with respect to this plane. It may be configured vertically or may be tapered as shown in FIG. When the side surface extending from the peripheral part to the recessed plane is sintered using a spacer configured perpendicular to the plane, a sintered body closer to the final shape can be manufactured. In addition, when using a spacer configured in a tapered shape, the removal portion by cutting increases compared to using a vertically configured spacer, but there is an effect of improving the releasability of the sintered body and the spacer. .

  Moreover, as a material of the spacer of the present invention, carbon or carbide having high mechanical strength and thermal conductivity and a small thermal expansion coefficient is preferable.

  When pressure-sintering the raw material powder mainly composed of a refractory metal element, it is preferable to keep the heating temperature high. In the case of sintering at such a high temperature, if carbon is used as a spacer, the carbon may diffuse into the sintered body and become contaminated. In particular, among the refractory metals, Zr, Hf, V, Nb, Ta, Cr, Mo, and W easily generate carbides, and Ru, Rh, Pd, Re, Os, Ir, and Pt include carbon. Because it dissolves in a certain amount, contamination due to carbon diffusion is likely to occur. Generally, in order to form a high-quality thin film using a target material, it is desirable to reduce the impurities in the target material. Therefore, the part contaminated by carbon diffusion in the sintered body is machined. It may be necessary to scrape off, etc., which may lead to a decrease in material yield.

  Therefore, it is necessary to reduce the contamination of the sintered body as much as possible. For this purpose, it is desirable to use a spacer made of carbide, which is a highly stable substance with high bonding force between atoms. In particular, among carbides, silicon carbide is difficult to decompose even at high temperatures, and Si and C (carbon) hardly diffuse and become contaminated during sintering. More desirable. Moreover, silicon carbide has a desirable property as a spacer, ie, high temperature strength.

  In addition, when silicon carbide is used as a spacer in the present invention, the entire spacer may be made of silicon carbide from the effect of suppressing the diffusion of carbon into the sintered body, but it is in contact with the sintered body. A film made of silicon carbide may be formed only on the surface portion.

Moreover, if the surface form of the spacer is large, the spacer and the sintered body are firmly bonded, and it may be difficult to release the spacer. Therefore, the surface of the spacer is desirably smooth, and preferably the surface roughness (Ra) is 0.5 μm or less. When the surface roughness (Ra) is 0.5 μm or less, the release of the spacer and the sintered body becomes very easy and the surface of the sintered body becomes smooth, so that machining to the sintered body is minimized. This is because it can be limited.
In the present invention, the surface roughness (Ra) is a calculated average roughness defined in Japanese Industrial Standard (JIS) B0601: 2001, and is defined as an average of absolute values of a roughness curve at a reference length. As the method for measuring the surface roughness (Ra), the most widely used stylus roughness measuring method is suitable.

Among the above-mentioned refractory metal elements, Ru, Rh, Pd, Re, Os, Ir, and Pt have a carbon solid solubility limit as large as several atomic%, and thus cause contamination due to carbon diffusion during sintering. It is an easy element.
In particular, since Ru is poor in ductility, densification due to plastic deformation can hardly be expected during the powder sintering process. For this reason, in order to achieve complete densification of the sintered body, it is necessary to set the heating temperature high during pressure sintering, which is particularly susceptible to contamination by the carbon. Moreover, since Ru is an expensive noble metal with a small output, the production method of the present invention is very suitable for the purpose of improving the material yield.

It is a schematic diagram which shows a target material. It is a schematic diagram which shows an example of the spacer of this invention. It is a schematic diagram which shows the state which filled the raw material powder and the spacer in the pressure sintering mold of the hot press of this invention. It is a schematic diagram which shows the state of the pressure sintering of this invention. It is a schematic diagram which shows an example of the spacer of this invention.

Explanation of symbols

1. 1. Target material, Collar part, 3. Spacer, 4. Mold, 5. Raw powder,
6). 6. Lower punch, Top punch, 8. Sintered body

Claims (5)

Fill the hot press mold with raw material powder mainly composed of refractory metal elements and plate-like spacers with a flat surface that is recessed from the peripheral part in the center part, alternately overlapping the pressure axis direction. Then, after pressure-sintering, the spacer is separated to obtain a plurality of sintered bodies. The method for producing a pressure sintered target material according to claim 1, wherein the spacer is made of silicon carbide. The method for producing a pressure sintered target material according to claim 1, wherein a film made of silicon carbide is formed on a surface of the spacer. The method for producing a pressure-sintered target material according to any one of claims 1 to 3, wherein the spacer has a surface roughness (Ra) of 0.5 µm or less. The method for producing a pressure-sintered target material according to any one of claims 1 to 4, wherein the refractory metal element is Ru.