JP3748221B2 - Mo-based sputtering target and method for producing the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a Mo-based sputtering target particularly suitable for upsizing and a method for manufacturing the same.
[0002]
[Prior art]
Conventionally, powder metallurgy or melting methods have been used for the production of sputtering targets. In general, the melting method is a method in which a predetermined target shape is cut out from a cast ingot, or the ingot is processed into a predetermined shape by hot working or cold working. In addition, a composite target is known that is not a single-piece target but a combination of different types of target pieces manufactured by a melting method so that the entire target has a desired composition. For example, as disclosed in Japanese Patent Laid-Open No. 6-204226, there are a radial type, a target in which rectangular parallelepiped targets are arranged side by side, and the like.
[0003]
As for the powder metallurgy method, a method is known in which a powder obtained by pulverizing an alloy is manufactured by hot isostatic pressing in a high-temperature high-pressure gas atmosphere. For example, Japanese Patent Laid-Open No. 61-60803 is an example. The powder metallurgy method is used for a high-melting-point material that is difficult to manufacture by a melting method and an alloy-based material in which segregation easily occurs and a uniform structure is difficult to obtain in a target. In addition, by using the moldability of powder, the green compact molded into a shape close to the final shape of the target is consolidated, and a near-net process is also performed in which the target is manufactured with only a slight finishing process. .
[0004]
[Problems to be solved by the invention]
The general characteristics required for the target are that the target has the desired composition, no segregation, and crystal grains are fine in order to make the composition and structure of the formed film uniform. On the other hand, in recent years, there has been an increase in the size of targets for the purpose of increasing the size of products and reducing costs mainly in the liquid crystal display, and the demand for large Mo-based targets has increased. A large target includes a large target having a size of about 1000 mm × 700 mm and φ300 mm or more, and a large apparatus is required for manufacturing. In addition, in terms of characteristics, a uniform fine structure and low oxygen are also demanded as in the conventional case, and manufacturing conditions are severe.
[0005]
As described above, even in a large Mo-based target, a uniform and fine structure is required. However, in the melting method, as the size increases, it becomes difficult to prevent segregation in the ingot and it is difficult to obtain a uniform and fine structure. In order to solve this problem, there is a method of uniformly refining the structure by hot working or the like, but a large apparatus is required, and depending on the composition system, hot working may be difficult and can be applied to all compositions. That wasn't true.
[0006]
On the other hand, in the powder metallurgy method, as long as powder can be produced, it can be produced for most component systems. In this case, there is no problem as long as it is a single component or alloy powder, but when two or more types of powders are mixed and filled, separation may occur due to differences in the particle size distribution, specific gravity, and shape of the powder. . This is a problem that occurs even with a small target, but is a big problem because it appears more prominently with a large target.
[0007]
Furthermore, in the case of powder metallurgy, the larger the size, the more difficult it becomes to uniformly fill the powder, and the difference in packing density tends to occur. Therefore, there is a difference in shrinkage rate during consolidation. Deformation occurs. In particular, in the case of a Mo-based target, the particle size of the raw material powder to be used is generally as fine as 10 μm or less, and since the powder exists in an aggregated form, the packing density does not increase, for example, as low as about 40%, It is important to take measures against the above deformation.
[0008]
In general, a target having a plate shape is likely to warp or deform a corner portion. For this reason, it is necessary to add a correction process or increase the machining allowance in anticipation of this deformation at the time of manufacturing.Furthermore, in order to uniformly fill the powder, it is necessary to measure the filling height during the work. It was a big problem in production.
[0009]
Another problem with the powder metallurgy method is that it is difficult to reduce the oxygen content of the manufactured target. For example, when manufacturing using hot isostatic pressing, the raw material powder is filled into a predetermined pressurized container (capsule) and processed. However, since the powder is hermetically sealed, it is possible to remove oxygen during processing. Impossible. Therefore, it is difficult to obtain a target having an oxygen content equal to or lower than that of the raw material powder.
[0010]
An object of the present invention is to provide a Mo-based sputtering target suitable for increasing the size and achieving a reduction in the amount of oxygen, and a method for manufacturing the same.
[0011]
[Means for Solving the Problems]
As a result of examining the problem of segregation accompanying the enlargement of the target and deformation at the time of production, the present inventor has joined a plurality of blocks made of a compacted powder body, in particular, segregation of the Mo-based target, deformation during production. I found that I can greatly improve. And by reviewing the prepared block, the oxygen-based reduction of the Mo-based target can be achieved, and the present invention has been achieved.
[0012]
That is, in the present invention, after compressing and molding the raw material powder, a plurality of blocks having substantially the same composition formed by sintering in a hydrogen atmosphere are placed in a pressure vessel, and the plurality of the blocks are subjected to hot isostatic pressing. This is a method for manufacturing a Mo-based sputtering target in which blocks are joined to obtain a target material having an oxygen content of 100 ppm or less.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
One of the important features of the present invention is that the focus is on the Mo-based sputtering target, and the target is formed by joining a plurality of blocks made of a compacted body of the powder. That is, instead of manufacturing a single-piece target directly from the powder, the target is formed by bonding once after being consolidated.
[0016]
This eliminates deformation and lack of density, which was a problem when directly increasing the size of the powder target while maintaining the uniformity of the structure, which is a unique advantage of the powder, especially for the Mo-based target. Can do. Further, the filling operation into the pressurized container is also an easy operation of only laying the blocks, and it does not require man-hours such as measurement of the filling height for making the filling density uniform, and the workability is remarkably improved. Further, automation is possible by using a compacted body handling apparatus.
[0017]
And the further characteristic of this invention exists in the place which coped with the reduction | decrease with respect to the large oxygen content which was a problem in the powder metallurgy method. That is, the Mo-based sputtering target having an oxygen content of 100 ppm or less.
[0018]
As the powder compact in the present invention, a compact such as a press-molded body and its sintered body, a cold isostatic press (CIP) body and its sintered body, and a hot isostatic pressure (HIP) body are compressed or compressed. Sintered ones can be used. At this time, the compacted body is made into a sintered body, and in particular, sintered in a hydrogen atmosphere, so that the oxygen content can be reduced. As a result, the oxygen content is 100 ppm or less, further 80, 60 ppm or less. Can be achieved. Preferably, it is a consolidated body obtained by sintering in a hydrogen atmosphere after the CIP treatment, the packing density is improved by the CIP treatment, and it is effective in suppressing deformation of the target material after the HIP treatment.
[0019]
The present invention is effective for a pure Mo target or an alloy target containing one or more other elements in Mo. As an example of the alloy target, Mo is a target containing one or more elements of Cr, W, Zr in Mo, and a Mo-based target in which the Mo amount is 50% or more in atomic weight ratio. .
[0020]
For such a Mo-based target of the present invention, it is advantageous to obtain a large target having a uniform composition by making a plurality of blocks made of a powder compact into substantially the same composition. In the case of an alloy target, a compacted body of an alloy powder, a single powder of elements to be alloyed, or a compacted body in which alloy powders are mixed can be used as the powder.
[0021]
It is desirable that the joining method is carried out by hot isostatic pressing in a pressurized container in that it can be pressurized isotropically to simultaneously increase the density of the compacted body.
[0022]
【Example】
Example 1
Mo powder and W powder are mixed by a V-type mixer at a mixing ratio of atomic weight ratio of 65:35, formed into a block of 120 mm × 95 mm × 18 mm by a CIP apparatus, and then sintered in a hydrogen atmosphere to obtain a compact 2 Got. This was laid and filled in a 1200 mm × 950 mm pressurized container 1 as shown in FIG. 1, and the pressurized container was sealed and evacuated by a evacuating pipe 3 (FIG. 2), and then joined and consolidated by HIP treatment. . At this time, the warpage of the container after the HIP treatment was 5 mm or less. In addition, the density of the central part of the HIP body was 99% or more, and the density of the peripheral part was also 99% or more. There was no difference in the microstructure between the central part and the peripheral part, and the oxygen content was 80 ppm.
[0023]
When a target was cut out from this material, a 1080 mm × 930 mm × 8 mm target was prepared and a sputtering test was performed, a favorable result was obtained in which there was little variation in film composition and little change in composition due to sputtering time.
[0024]
For comparison, the same mixed powder was filled into a 1200 mm × 950 mm container using a small scoop, and was similarly evacuated, sealed, and HIP treated. At this time, warpage of about 10 mm occurred in the container after HIP treatment, and deformation due to insufficient filling occurred in the corner of the HIP body. The oxygen content was 600 ppm.
[0025]
(Example 2)
Pure Mo powder was formed into a 113 mm × 84 mm × 20 mm block by CIP treatment, and then sintered in a hydrogen atmosphere to obtain a consolidated body. These compacts were laid and filled in a 1130 mm × 1030 mm container, and the container was sealed and evacuated, and then joined and consolidated by HIP treatment. At this time, the warpage of the container after the HIP treatment was 4 mm or less. In addition, the density of the central part of the HIP body was 99% or more, and the density of the peripheral part was also 99% or more. There was no difference in the microstructure between the central part and the peripheral part, and the oxygen content was 50 ppm. And by cutting out from this material, a target of 1080 mm × 930 mm × 10 mm could be produced.
[0026]
For comparison, the same powder was filled into a 1130 mm × 1030 mm container using a small scoop, and was similarly evacuated, sealed, and HIP treated. At this time, the container after the HIP treatment was warped by about 30 mm, and the corners were deformed. Therefore, the target of 1080 mm × 930 mm × 10 mm could not be cut out, and the container had to be changed to a one size larger. The oxygen content was 500 ppm.
[0027]
【The invention's effect】
According to the present invention, separation due to differences in particle size distribution, specific gravity, and shape when mixing and filling two or more types of powder, which was a problem in the powder sintering method, can be prevented, and a reduction in oxygen content can also be achieved. . Furthermore, since the density of the individual compacts is constant, it is possible to prevent warping during shrinkage and deformation of the corners due to the density difference. Therefore, an extra correction process and processing cost can be reduced, and manufacturing cost can be reduced. Furthermore, the measurement of the filling height for uniformly filling the powder becomes unnecessary, and the workability is greatly improved. In particular, the present invention is effective for a large target having a large powder filling area.
[Brief description of the drawings]
FIG. 1 is a view showing a laying state of a compacted body according to the present invention.
FIG. 2 is a view showing a sealed state of a pressurized container according to the present invention.
[Explanation of symbols]
1. 1. pressurized container, 2. compacted body; Pipe for vacuuming

Claims (1)

After compression molding the raw material powder , a plurality of blocks having substantially the same composition formed by sintering in a hydrogen atmosphere are put into a pressure vessel, and the plurality of blocks are joined together by hot isostatic pressing. A method for producing a Mo-based sputtering target, wherein a target material having an oxygen content of 100 ppm or less is obtained .

Images