JP2646058B2 - Sputter target material and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sputter target material, and more particularly, to a sputter target material made of a high-purity tungsten disk and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, tungsten used as a sputtering target material is obtained by sintering a tungsten powder by pressing or hot pressing, or manufactured by CVD.

[0003]

The following describes what a good sputter material is.

[0004] (1) The hardness was within H _v 400, can hold the material surface roughness required for sputtering material. Specifically, R _max can be set to 1 μm or less.

[0005] This is because particles are suppressed during sputtering (although this is not an absolute condition for particles).

(2) W originally has a high specific gravity, but it is most important to increase its density.

In general, the sputtered material is required to have a density of 85 to 90% or more of the theoretical density, and recently, 93 to 95% is desirable. This is because it is desired that the atoms do not fly evenly when sputtered. Therefore, when the target materials are viewed from above, it is preferable that the target materials be arranged as uniformly and densely as possible.

Further, W has a body-centered cubic type crystal structure, and it is rather good that the plane orientation is not deviated. In fact, the present invention also has a random orientation (non-oriented) as shown in the separate sheet.

[0009] (3) As the crystal grains, FIG. 3 (a) and FIG.
When considered as shown in FIG. 3 (b), it is considered that particles are less likely to be generated at the time of sputtering in the horizontal arrangement shown in FIG. 3 (b).

Further, when the particle size is 30 μm or less, the hardness of the material itself increases, and the particles are arranged in the same manner as the vertical arrangement, which is disadvantageous. The particle size is 300μ.
If it is more than m, a heat treatment cost is required, which is not appropriate.

As described above, tungsten used as a sputtering target material is obtained by pressing and sintering a tungsten powder, and also manufactured by CVD. Pressed and sintered products have the drawback that it is difficult to achieve a density of 97% or more of the theoretical density, resulting in low density products. Such a low-density sputter target material is not suitable for a high-quality product because the state of the material to be sputtered becomes uneven or bubbles when sputtered.

[0012] On the other hand, the latter manufactured by CVD has no drawbacks in terms of quality, but has the drawback that the manufacturing cost is high and expensive. In addition, a hot press cannot obtain a high-density product, and has not been sufficiently evaluated.

[0013] Therefore, the technical problem of the present invention is to provide a low-cost sputter target material that can satisfy the quality characteristics of the material for the sputter target, eliminates any troubles in the rolling process and the subsequent secondary process, and is practical. It is to provide a manufacturing method thereof.

[0014]

According to the present invention, there is provided a rolled material of a tungsten sintered body, wherein the rolled material has tungsten particles having a crystal grain size of 30 to 300 μm and is in a range of 360 to 400. possess a and hardness, 99.0% or more and the relative density, the tungsten particles are elongated
Consisting of crystal grains and aligned in the length direction along the plate surface
Thus , a tungsten target material characterized by being aligned horizontally can be obtained.

Further, according to the present invention, in a method for producing a rolled material of a tungsten sintered body in which a tungsten powder is press- molded by powder metallurgy, sintered, and hot-rolled, the method comprises the steps of: After performing heat treatment in the range of 1400 to 1700 ° C in the inside, sintering at 1800 ° C or more, and further rolling, and then in the range of 1200 to 1500 ° C
A method for producing a sputter target material, comprising a heat treatment step for adjusting crystal grains .

That is, in the present invention, after the tungsten powder is pressed and sintered, hot rolling or forging of the primary working is performed to secure a relative density (ratio to the theoretical density) of 99% or more, thereby achieving a high density. It is a high-density product, and furthermore eliminates contamination in the sintering process and ensures high purity.

Tungsten is difficult to process, and therefore, it is easy for cracks and cracks to occur in secondary processing after rolling or forging, such as cutting and drilling. The range of hardness and the range of recrystallized grain size that can be easily obtained were clarified, and troubles in secondary processing were eliminated.

Here, in the present invention, when pressing and sintering the high-purity tungsten powder obtained by the purification process of tungsten refining, first, the tungsten powder is placed in a vacuum atmosphere.
After performing heat treatment in the range of 400 ° C to 1700 ° C,
Sintering is performed at 1800 ° C. to 2100 ° C. to produce a sintered body. This heat treatment in a vacuum atmosphere is performed to prevent contamination of tungsten during sintering, and is a vacuum furnace that does not use heat-resistant bricks for furnaces or refractories for keeping heat. The heater is a tungsten heater or a molybdenum heater. The degree is 1.
A degree of vacuum of 30 × 10 ⁻³ Pa or more is secured. By performing the heat treatment in the vacuum atmosphere before sintering, the density of the pressed body is improved and the porosity of the pressed body is reduced, so that contamination from the atmosphere during sintering is reduced.

Next, the sintered body is hot-rolled, and the rolling ratio at this time is about 73.0% or more, thereby ensuring a relative density of 99.0% or more. Further, the hardness of the tungsten disk and the plate is increased from Hv 360 to 400 by heat treatment.
And the recrystallized grain size is from 30 μm to 300 μm.
By performing the secondary processing after setting the range, the secondary processing can be easily performed.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

When pressing and sintering using high-purity tungsten powder obtained by the purification process of tungsten refining, first, at 1400 ° C. and 1700 ° C. in a vacuum atmosphere.
After performing heat treatment at two different temperatures of 1 ° C., sintering was performed at 1800 ° C. and 2100 ° C. to produce a sintered body. Further, a sintered body manufactured by a conventional sintering method without performing heat treatment in a vacuum atmosphere was prepared as a comparative product with the product of the present invention.

The chemical components of the powder of the present invention and the comparative product and the sintered body were analyzed, and the results are shown in Table 1 below.

[0023]

[Table 1]

As shown in Table 1 above, the product of the present invention has no contamination at the time of sintering, and the comparative product obtained by the conventional sintering method has Al, Si and Fe at the time of sintering. You can see that it is contaminated.

It is considered that these contaminants are mixed in from a heat insulating material of an electric furnace, for example, a heat-resistant brick for a furnace or a refractory for keeping heat. Therefore, the heat treatment in the vacuum atmosphere is performed by an electric furnace that does not use a heat insulating material such as a brick. The heater is a tungsten heater or a molybdenum heater, and the degree of vacuum is 1.30 × 10 ⁻³ Pa or more. And reduced pollution from the atmosphere. By performing this heat treatment, the density of the pressed body before sintering of the product of the present invention was increased as compared with the conventional product, and the porosity of the pressed body was reduced as compared with the conventional product. Therefore, a sintered body with less contamination from the atmosphere during sintering than the conventional product was obtained.

Next, hot rolling was performed on the sintered body. The working method at that time was heating at 1200 ° C. and 1500 ° C. in a heating furnace in a hydrogen atmosphere, passing through a rolling mill once by one heating, and repeating the process to obtain a predetermined rolling ratio. The rolling ratio for each pass was reduced so that the thickness before rolling was reduced by about 2 mm after rolling. Table 2 shows the relationship between the rolling ratio and the specific gravity at this time.

[0027]

[Table 2]

If the points shown in Table 2 were plotted on a graph and the rolling reduction was performed at 73.0% or more, the specific gravity could be secured at 19.10 or more. Therefore, the relative density was 99.0% or more.

Further, the rolled plate and the circular plate were softened by heat treatment in the range of Hv 360 to 400. The recrystallized grain size at this time was within a uniform range of 30 μm to 300 μm. Table 3 shows the particle size and hardness by the heat treatment after the secondary sintering and the rolling.

[0030]

[Table 3]

The conditions of the heat treatment were set within the above hardness range by changing the temperature of the heat treatment depending on the hardness after rolling. When the secondary processing was performed in comparison with the hardness within this range,
In the above, secondary processing was easily performed. On the other hand, cracks and chippings occurred in the secondary processing of the later-mentioned ones. The secondary processing here means lathe processing, wire cutting,
It refers to water jet processing, drilling, and plane polishing.

Further, the sintered body at 1200 ° C. and 15
00 was boss measurement attached to the plane orientation of the sintered body in ℃. The results are shown in FIGS.

FIG. 1 is an X-ray diffraction profile of the sintered body at 1200 ° C. Table 4 shows data of each peak.

[0034]

[Table 4]

[0035] Further, X of the sintered body according to FIG. 2 1 5 00 ° C.
Table 5 shows the data of each peak in the line diffraction profile.

[0036]

[Table 5]

The relative intensity ratio I / I _o of the main diffraction surface by JCPPS card shown in Table 6 below, the present invention product shown in Figures 1 and 2 or Table 4 and Table 5 are the same random orientation (no Orientation).

[0038]

[Table 6]

[0039]

According to the present invention, according to the present invention, a tungsten disk and a plate manufactured by using a high-purity tungsten powder obtained by a scouring technique have a high purity.
It has a high density, satisfies the material quality characteristics for sputter targets, eliminates any troubles in rolling and subsequent secondary processing, and makes it possible to provide practical and low-cost materials.

[Brief description of the drawings]

FIG. 1 is a view showing an X-ray diffraction profile of a target material according to an example of the present invention which has been subjected to a reheating treatment at 1200 ° C.

2 is a diagram showing an X-ray diffraction profile of the target material according to an embodiment of the present invention conducted a reheating treatment in 1 5 00 ° C..

FIG. 3A is a view showing a vertically aligned state in which central axes of crystal grains are oriented in a plate thickness direction. (B) is a diagram showing a vertically aligned state in which the central axes of the crystal grains are oriented in the plate surface direction.

Claims (3)

(57) [Claims] 1. A rolled material of tungsten sintered compact, wherein the rolled material together with grain size having a tungsten particles 30 to 300 [mu] m, and hardness in the range of H _v 360~400, 99.0 possess% or more and the relative density, the
Tungsten particles consist of elongated crystal grains and
A tungsten target material, wherein the length direction is side-by-side along the plate surface . 2. A method for producing a rolled material of a tungsten sintered body in which a tungsten powder is pressed, sintered and hot-rolled by powder metallurgy, wherein the sintering is performed in a vacuum atmosphere at a temperature of 1400 to 1700 ° C. After sintering at 1800 ° C or higher, and after rolling , crystal grains in the range of 1200 to 1500 ° C
A method for producing a sputter target material, comprising a heat treatment step for adjustment . 3. The method for manufacturing a sputter target material according to claim 2, wherein the hot rolling has a workability of 73%.
The hot rolling was performed to increase the relative density to 99.0.
% Of the tungsten sputter target material.