JPH0355547B2 - - Google Patents

Description

[Detailed description of the invention]

``Industrial Application Field'' The present invention relates to a method for producing a tellurium or tellurium alloy target material used when forming a tellurium or tellurium alloy thin film layer, which is a recording medium of an optical disk, by a sputtering method. "Prior Art" As is well known, tellurium or a tellurium alloy has been put to practical use as a suitable material for the recording medium thin film layer of an optical disk, and the thin film layer is generally manufactured by a sputtering method. The target material used in this sputtering method consists of a circular or square plate and a packing plate (cooling plate) soldered to it. Conventionally, a melt casting method or a powder sintering method has been adopted as a method for manufacturing such a target material made of tellurium or a tellurium alloy for sputtering. "Problems to be Solved by the Invention" Among the conventional manufacturing methods mentioned above, in one method, the melting casting method, as is well known, tellurium itself is very brittle and easily cracks together with the alloy, and as a result, the number of products produced is low. Very bad. Especially tellurium
Tellurium alloy containing more than 50% by weight is difficult to manufacture, and the diameter of a circular product is 100 mm (70 x 100 mm for a square product).
It was almost impossible to manufacture products that exceeded this. Therefore, the diameter of the target has become small, reducing the efficiency of sputtering and the efficiency of using the target. The solid line in the attached drawing shows the transverse rupture strength of products manufactured by melting and casting using various compositions of Te (tellurium) and Se (selenium). If the content of is 50% by weight or more,
It can be seen that the transverse rupture strength of the alloy is also low. Since the strength is thus low, cracks occur early due to thermal stress during sputtering, shortening the life of the target and further reducing usage efficiency. The other powder sintering method is based on a method in which powder is made into a sintered body by a hot pressing method and this sintered body is used as a target material. Generally, in the conventional hot press method, the raw material powder is pressurized from two directions and exposed to high temperatures, so the resulting sintered body is relatively small due to the shape of the hot press, and there is no contamination from the press container. It is difficult to avoid non-uniform density due to adsorption and volatilization of adsorbed gas, deviation from the compound composition, etc. Therefore, it is impossible to simultaneously produce a large number of target materials with the same shape and performance from such a sintered body, and the sputtered film using the obtained target material has a uniform thickness. ,
It has drawbacks such as variations in surface smoothness and electrical characteristics. This invention was made in view of the above circumstances,
The object of the present invention is to provide a method that can efficiently produce a tellurium or tellurium alloy target material with high density, uniformity, and large dimensions at a low cost. "Means for Solving the Problems" The method of the present invention involves pulverizing a lump of tellurium or a tellurium alloy using a crusher such as a ball mill, sieving this powder to make the particle size within a predetermined range,
The obtained powder is packed into a container made of elastic material, sealed in a vacuum, placed in a cold isostatic press, and pressurized, and the obtained high-density uniform compact is machined to become the target material. , If necessary, a step of vacuum degassing the powder and a step of sintering the powder after cold isostatic press molding are added. The present invention will be further explained in detail. First, in the method of the present invention, the tellurium alloy used as a raw material is an alloy containing 50% by weight or more of tellurium,
The tellurium or tellurium alloy used is a powder of 60 to 635 mesh, preferably 100 to 635 mesh. This means that the powder is more than 60 mesh,
If coarse particles of 60 mesh or more are mixed in, the strength of the press-formed product obtained will not increase, and it will crack during processing or during sputtering, and uneven density will occur, resulting in variations in sputtering speed, This is because abnormal discharge may occur during sputtering.
On the other hand, if the particles are too fine to 635 mesh or less, the density of the molded product will be low and it will be difficult to mold and become brittle, resulting in cracking during processing and cracking during sputtering. In addition, when powder of 100 to 635 meshes is used as raw material, under certain conditions the variation in density ratio can be suppressed to ±3% within a lot, between lots, and within a plane, and even press forming with high strength can be achieved. You can get a body. Following the powder preparation as described above, in the method of the present invention, the powder raw material is packed into an elastic material container such as rubber or urethane, sealed in a vacuum, and then placed in a cold isostatic press and completely heated at room temperature. Obtain a press molded body from the direction. Therefore, this press molded body is much more uniform and denser than the molded body obtained by the conventional hot pressing method. In addition, the above container made of elastic material is 60 cm
Since it is possible to make large-capacity items of about φ x 100cm,
The resulting press molded product can be produced in a larger capacity than in the case of the conventional hot pressing method. Furthermore, since the raw material powder has a very large surface area and a high gas adsorption property, it is desirable to perform vacuum degassing treatment as a pretreatment for cold isostatic pressing. This vacuum degassing process makes it possible to provide a target material that is more dense and uniform than cold isostatic pressing alone. The optimum conditions for this vacuum degassing treatment are a temperature range from 100℃ or higher to a temperature at which the vapor pressure of the powder itself is 1 Torr or less, a vacuum degree of 1 Torr or less, and a treatment time of 1 to 5 hours. good. In some cases, this vacuum degassing treatment may be applied to the target material before sputtering. In addition, in the method of the present invention, by sintering the press molded body obtained by cold isostatic pressing, the density of the molded body obtained can be increased by several percent to several tens of percent.
can be improved. If oxidation is not desirable for the target material, the atmosphere during sintering should be an inert gas atmosphere. As described above, the method of the present invention applies the cold isostatic pressing method after adjusting the particle size of the powder to a certain range in order to produce the press-formed body that is the material of the target material. Accordingly, vacuum degassing treatment and heat treatment are appropriately combined. "Action" According to the method of the present invention described above, the following effects can be obtained. () Since cold isostatic pressing is carried out at room temperature, there is no volatilization of adsorbed gas from the powder raw materials during pressing, and since the press is performed in all directions using hydrostatic pressure, the obtained press molded product cannot be processed using conventional methods. It is much more uniform and has higher density and strength than the obtained molded body, and therefore can be processed into a desired shape with high dimensional accuracy by ordinary machining. In other words, the press-formed product of the present invention can be processed using most methods such as plane milling to achieve smoothness, cylindrical grinding to achieve roundness, and diamond cutters and hand saws to cut out many pieces of a certain thickness. Machining can be applied. On the other hand, when producing a sintered body using the conventional hot pressing method, the adsorbed gas in the powder raw material evaporates during pressing, resulting in the resulting sintered body having uneven density and becoming brittle. . () Cold isostatic pressing is performed at room temperature, but powders with high vapor pressure can also be pressed. Therefore, even in the case of a compound, the composition ratio of the powder as the starting material remains and is maintained in the molded product after cold isostatic pressing. On the other hand, in the conventional hot pressing method, powders with high vapor pressures will volatilize due to the high temperature during pressing, and especially in the case of alloys, the composition will shift, making them unsuitable as target materials. . () Since cold isostatic pressing is carried out at room temperature, there is little contamination from the press container, and even if there is contamination, it is limited to the surface layer of the press-formed product. Therefore, surfaces contaminated by post-processing such as machining, degreasing, and pickling in subsequent steps can be easily removed, and a target material with extremely high purity, which cannot be obtained by conventional methods, can be obtained. () As is clear from the descriptions in () to () above, a large number of target materials with the same shape, uniformity, high density, high strength, and high dimensional accuracy can be produced at the same time by machining from a large-capacity press-formed body. Can be produced individually. Therefore, these target materials are easy to handle, and there is no need to reset the sputtering conditions for each target material, making it possible to efficiently provide a uniform, high-quality optical recording medium thin film layer. On the other hand, when using the conventional hot press method,
As mentioned above, the obtained sintered body is relatively small in shape, has uneven density due to contamination from the press container and volatilization of adsorbed gas, and has a deviation from the compound composition, and has poor workability. Therefore, it is impossible to produce a large number of target materials with the same shape and performance at once, and the obtained target materials must be handled carefully, and sputtering conditions must be reset for each target material. be. Next, examples of the method of the present invention will be shown. “Example” As shown in Table 1, eight types (Example 1 to
8) The composition and particle size of the raw material powder were adjusted, and among them, Examples 1, 6, and 7 were not subjected to vacuum degassing treatment.

【table】

[Table] Examples 2, 3, 4, 5, and 8 were each subjected to vacuum degassing treatment at 1 Torr or less and at each temperature and time shown in the table. Thereafter, each raw material powder was packed in a rubber container with a capacity shown in Table 1 in the amount shown in the same table, and cold isostatically pressed at each press pressure for 5 minutes to obtain a molded body. The molded bodies of Examples 7 and 8 obtained as described above were machined as they were to the dimensions shown in Table 1, and the molded bodies of other Examples were machined at the temperatures shown in Table 1.
Each sintered body was machined to the dimensions shown in the table. Table 1 from each molded body before machining
The number of target materials shown in was obtained. The obtained target material had no cracks due to machining. Furthermore, when each target material was sputtered, no cracks occurred. On the other hand, when a comparative example was prepared using the manufacturing method, conditions, coarse grain size, and machining dimensions shown in Table 2, cracks due to mechanical and sputtering occurred as shown in Table 2. In this table, the number yield indicates the yield in machining. Ma

[Table] In addition, Comparative Examples 1 to 5 (first group) are those manufactured by a melt casting method or a hot press method using components corresponding to the examples of the present invention, and Comparative Examples 6 to 9.
(2nd group) is an alloy of Te and Se, Comparative Example 10 ~
No. 13 (third group) is an alloy of Se manufactured by melting and casting or hot pressing, respectively. According to these results, materials containing Te not only have a high incidence of cracking during sputtering, but also
The yield is very low compared to Se alloy. This shows that Te compared to Se as shown in the drawing.
This is thought to be due to the extremely low transverse rupture strength. For reference, the values of transverse rupture strength when the present invention is applied to compositions of the second group (manufacturing conditions are the same as in Example 7) are shown by broken lines in the drawing, and the transverse rupture strength is significantly improved. ing. "Effects of the Invention" As explained above, according to the method of the present invention, a tellurium target material or tellurium for sputtering that is uniform, high density, relatively large capacity, high performance, and easy to handle can be produced. A large number of alloy target materials having the main composition can be efficiently produced at the same time, and as a result, a large quantity of optical recording medium thin films of consistent high quality can be provided.

[Brief explanation of drawings]

The attached drawing is a graph showing the transverse rupture strength values of the conventional example and the example.

Claims (1)

[Claims] 1. Powder of tellurium or an alloy containing at least 50% by weight of tellurium is adjusted to a particle size of 60 to 635 mesh, and then packed in an elastic container and sealed in a vacuum. 1. A method for producing a tellurium or tellurium alloy target material, which comprises uniformly pressurizing a container by cold isostatic pressing, and machining the obtained high-density uniform molded body to obtain a sputtering target material. 2. After adjusting the powder of tellurium or an alloy containing at least 50% by weight of tellurium to a particle size of 60 to 635 mesh, vacuum degassing treatment is performed, and then the powder is packed in an elastic container and A method for producing a tellurium or tellurium alloy target material, which comprises sealing the container in a vacuum, uniformly pressurizing the container using a cold isostatic press, and machining the obtained high-density uniform molded body to make a sputtering target material. . 3 After adjusting the powder of tellurium or an alloy containing at least 50% by weight of tellurium to a particle size of 60 to 635 mesh, it is packed into a container made of an elastic material, sealed, and the container is pressed using a cold isostatic press. 1. A method for producing a tellurium or tellurium alloy target material, which comprises applying uniform pressure, sintering the obtained high-density uniform compact, and then machining it into a sputtering target material. 4 Powder of tellurium or an alloy containing at least 50% by weight of tellurium is adjusted to a particle size of 60 to 635 mesh, then subjected to vacuum degassing treatment, and then packed in a container made of an elastic material. After sealing in a vacuum and applying uniform pressure to this container using a cold isostatic press and sintering the resulting high-density uniform molded body,
A method for producing a tellurium or tellurium alloy target material, which comprises machining it into a sputtering target material.