JP6331125B2 - Target material manufacturing method - Google Patents

Description

  The present invention relates to a method for producing a target material used for forming a metal thin film used for electrical wiring, electrodes, etc., for example, for a large screen flat display device.

  Currently, a high-melting-point metal thin film such as Mo having a low electric resistance is used for a thin film electrode and a thin film wiring of a liquid crystal display (hereinafter referred to as “LCD”) which is a kind of flat display device. As a method for forming the metal thin film, a sputtering method is suitable, and a target material is widely used. In recent LCDs, as the glass substrate size is increased to 1500 mm × 1800 mm or more, the target material for forming the metal thin film is required to be increased in size.

  When a metal thin film is formed on the above ultra-large LCD, a sputtering apparatus that uses a long target material having a total length of 3000 mm or more, which is called a multi-cathode method, is used. ing.

Since Mo having a high melting point is difficult to produce by a melt casting method, a target material is generally produced by a powder sintering method. And generally, since the average particle diameter of the Mo raw material powder is as fine as 10 μm or less and the Mo raw material powder is present in an aggregated form, the packing density in the pressurized container does not increase, and after pressure sintering Since it is easy to deform, the countermeasure has been examined.
For example, it is proposed to put a plurality of compacts formed by compressing Mo raw material powder into a pressurized container and to join these compacts together by hot isostatic pressing (hereinafter referred to as “HIP”). (For example, refer to Patent Document 1).

JP 2006-28536 A

  According to the inventor's study, when the shape of the joint surface of the compacted compact is not flat or the shape of the outer peripheral surface is bent, the target material obtained when the compacts are joined together It was confirmed that bending may occur. This problem of bending requires cutting the target material to correct the shape, leading to a decrease in yield.

  In view of the above problems, an object of the present invention is a target material that is excellent in shape accuracy without causing bending in a long target material that is pressure-sintered by laminating and inserting compacted compacts obtained by compressing raw material powder. It is to provide a method for stably producing a product with a good yield.

  As a result of various studies on methods for solving the above problems, the present inventor first conceived of producing a compacted body obtained by compression-molding a raw material powder with a cold isostatic press (hereinafter referred to as “CIP”). Then, the compacted body is cut into a predetermined shape to form a molded body, and the molded body is laminated and inserted into a pressurized container, degassed and sealed, and then pressure-sintered with HIP, so that isotropic The present inventors have found that a long target material excellent in shape accuracy, which is a target structure, can be easily produced, and has reached the present invention.

That is, in the present invention, a raw material powder is compression-molded by a cold isostatic press to produce a compacted body, and then the compacted body is cut so as to have a predetermined shape dimension to form a compacted body. It is an invention of a method for producing a target material, in which a sintered body is obtained by pressure-sintering by hot isostatic pressing after laminating and inserting into a pressure vessel and sealing with deaeration.
In the present invention, the sintered body can be cut into a plurality of pieces in the longitudinal direction.
Moreover, in this invention, the said sintered compact can also be cut | disconnected into two or more by the orthogonal | vertical direction with respect to a longitudinal direction.

  According to the present invention, for example, a long target material having a total length of 3000 mm or more can be stably manufactured with high shape accuracy and good yield without causing bending. In addition, this makes it possible to provide a target material capable of stably forming a metal thin film on an ultra-large size LCD substrate, which is a useful technique for LCD production.

It is a schematic diagram which shows an example of the manufacturing method of this invention. It is a schematic diagram which shows another example of the manufacturing method of this invention.

In the method for producing a target material of the present invention, first, raw material powder is compression-molded by CIP to produce a consolidated body. When trying to obtain a compacted body by compression molding by uniaxial stress such as press molding, the total load as a whole becomes large, and there may be restrictions on equipment. In addition, there may be a difference in the density distribution inside the compact.
As a means for compression molding the raw material powder, there is a possibility that HIP can also be applied. However, the compacted body obtained by HIP has high hardness, and there is a case where a cutting process described later is performed by a wet process. For this reason, the process of removing the oil component adhering to the compacted body and the cutting powder and the process of pulverizing the cutting powder are essential, and there is a problem that it becomes difficult to join the compacted bodies during pressure sintering.
For this reason, in this invention, in order to compress-mold raw material powder, CIP which can apply a molding pressure isotropically and can obtain the compact with a uniform high relative density is employ | adopted. Thereby, this invention can arrange in the shape of the compact body suitable for carrying out lamination | stacking insertion at the next process. The CIP conditions are preferably performed under a pressure of 10 to 1000 MPa in order to obtain a consolidated body having sufficient strength and relative density required for handling the consolidated body and for cutting processing described later.
The relative density of the compacted body applied in the present invention is preferably 50% or more. This is because the strength of the compacted body is increased in advance to prevent breakage of the compacted body during handling such as transportation or cutting. In addition, the reason why the density of the compacted body is secured in advance is that, when hot isostatic pressing is performed on a plurality of compacts, the shrinkage of the individual compacts in the sintering proceeds excessively, and the compacts are deformed due to compression. This is also for suppressing problems such as bending and local shrinkage.

The shape of the compact that can be applied in the present invention is not particularly limited, for example, a flat target material is a cube or a cuboid, and a cylindrical target material is a cylinder or a column.
In addition, as the raw material powder applicable in the present invention, metal powder can be applied, for example, refractory metals such as Mo, Ti, Zr, Hf, V, Nb, Ta, Cr, W, or a mixture thereof. It may be an alloy or an alloy, and is not particularly limited. In addition, the average particle size of the metal powder applied in the present invention is not particularly limited, but it is preferable to use a metal powder having a size of 0.5 to 1000 μm. In addition, the average particle diameter as used in the field of this invention is represented by the spherical equivalent diameter by the light-scattering method using a laser beam prescribed | regulated by JISZ8901.

In the method for producing a target material of the present invention, the compacted body obtained above is cut into a molded body so as to have a predetermined shape dimension. As described above, when trying to obtain a long target material by stacking compacted compacts, etc., the shape of the joint surface of the compacted compact is not flat or the outer peripheral surface is bent. In some cases, the target material obtained when the compacted body is joined may be bent.
In the present invention, a surface to be a joint surface of the compacted body compression-molded with the CIP obtained above is cut in parallel, and a surface other than the joint surface is cut flat to form a predetermined shape and size. Get the body. As a result, the compacts can be stacked and inserted into the metal container without gaps, and the bending of the sintered body obtained in the longitudinal direction can be suppressed. As a result, a sintered body excellent in shape accuracy can be obtained, so that the machining allowance in the final cutting process can be reduced, which contributes to the improvement in yield.
Moreover, when the compacted body applied by this invention is a cylindrical shape, it is preferable to also cut an internal peripheral surface.

Further, in the present invention, since CIP is adopted for compression molding of the compacted body, the raw material powder or other materials used for producing the compacted body without subjecting the powder generated by the cutting process to grinding or washing. As a raw material powder, it can be reused as it is, and in addition to the reduction in man-hours, the reduction in the total yield of the target material can be suppressed.
When cutting the compacted body in the present invention, for example, when the compacted body is a cube or a rectangular parallelepiped, it is preferable to use a milling machine, and when the compacted body is a cylinder or a cylindrical shape, a lathe or the like is used. Is preferred.
In addition, in order to prevent damage to the compacted body and molded body due to handling, a calcining process is provided before cutting the compacted body or before sintering the molded body to harden the surface of the compacted body and the molded body to maintain shape retention. May be improved.

Next, in the present invention, the molded body obtained above is laminated and inserted into a pressure vessel, deaerated and sealed, and then subjected to pressure sintering with HIP to obtain a sintered body. FIG. 1 shows an example in which a rectangular parallelepiped is applied to a molded body in the production of a long target material.
In the present invention, for example, the molded body 1 made of a rectangular parallelepiped is stacked and inserted into the pressurized container 2 to be deaerated and sealed. In the present invention, it is preferable to increase the size of the molded body 1 within a range that does not impair the handling properties of the individual molded bodies 1 because the number of cutting steps and the number of laminating steps can be reduced.
In the present invention, the pressurized container 2 is deaerated from the deaeration pipe 3 while being heated. The deaeration condition is preferably reduced to a pressure lower than 1 kPa in a heating temperature range of 100 to 600 ° C.

Next, the depressurized and sealed pressurized container 2 is pressure-sintered with HIP. The HIP conditions are preferably a sintering temperature of 450 ° C. or higher, less than the melting point of the raw material powder, a pressure of 30 to 150 MPa, and a HIP time of 0.5 to 10 hours.
When the applied pressure exceeds 150 MPa, there is a problem that the devices that can withstand are limited. Moreover, if the sintering time is less than 0.5 hours, it is difficult to sufficiently advance the sintering, and it is difficult to obtain a high-density sintered body. On the other hand, sintering times exceeding 10 hours are better avoided in production efficiency.
In the present invention, by setting the temperature to 450 ° C. or higher and the applied pressure to 30 MPa or higher, in addition to improving the relative density, there is an effect that a sufficient bonding strength between the molded bodies 1 can be obtained.
In addition, by sintering at a temperature lower than the melting point of the raw material powder, it is possible to suppress the coarsening of crystal grains in the structure of the integrally molded sintered body. The effect that generation | occurrence | production can be reduced is also acquired. In the present invention, in order to obtain a target material having uniform fine crystal grains and sufficient bonding strength, the sintering temperature of HIP is more preferably 700 to 1250 ° C.

  In the present invention, when a plurality of molded bodies are stacked and inserted into a pressurized container, a raw material powder having the same composition as the molded body may be interposed between the molded bodies, that is, between the surfaces to which the molded bodies are joined. Good. When the surface of a compacted body having a low relative density is cut, the surface roughness of the resulting molded body may become rough. When only such a plurality of molded bodies are laminated and inserted into the metal capsule, a gap is formed on the joint surface between the molded bodies. When HIP is performed in such a state, sintering of the joint surface sufficiently proceeds. There is no possibility. In the present invention, by interposing the raw material powder having the same composition as the compacts between the compacts, it is possible to completely remove the gap between the joint surfaces and uniformly sinter the entire compact. The shape accuracy of the target material to be obtained can be further improved.

Moreover, in this invention, it can also cut | disconnect into plurality in a longitudinal direction, and can also be set as a flat target object of a flat form. At this time, after laminating a plurality of molded bodies in a pressure vessel so as to have a total length of 2000 mm or more in the laminating direction and performing pressure sintering, the sintered body is cut in the longitudinal direction to obtain an outer peripheral surface or a cut surface. Can be used as the sputtering surface of the target material, and even with a single pressure sintering, a plurality of target materials having a long and large area sputtering surface can be obtained, which is also useful in terms of production efficiency. .
The thickness of the target material varies depending on the sputtering apparatus, and in most cases is 20 mm or less. Therefore, in the present invention, by cutting the sintered body after pressure sintering into a plurality of pieces in a direction perpendicular to the longitudinal direction, a plurality of flat target materials can be obtained even by one pressure sintering. Therefore, it is useful also in terms of production efficiency.

First, a commercially available Mo powder having an average particle size of 5 μm was filled in a rubber mold, and CIP treatment was performed at 20 ° C. under a molding pressure of 225 MPa to prepare six cylindrical compacts.
Next, the cylindrical compacted body obtained above was cut with a lathe so that the dimensions of the cylindrical molded body 1 shown in FIG. 2 were an outer diameter = 188 mm, an inner diameter = 138 mm, and a height = 125 mm. .
Next, these cylindrical molded bodies 1 were calcined in a hydrogen atmosphere at 1200 ° C. for 10 hours to improve the shape retention of the cylindrical molded body 1. The relative density of the cylindrical molded body 1 at this time was measured by the Archimedes method, and as a result, it was 75.0%. The relative density as used herein refers to a value obtained by dividing the bulk density measured by the Archimedes method by the theoretical density obtained as a weighted average of elemental elements calculated by the mass ratio obtained from the composition ratio of the molded body. The value obtained by multiplying.

All six cylindrical shaped bodies 1 obtained above are inserted so as to be stacked on the cylindrical pressurized container 2 shown in FIG. 2, and are heated from the deaeration pipe 3 while being heated at a temperature of 450 ° C. Degassed and sealed.
Next, the pressurized container 2 is subjected to HIP treatment under the conditions of a temperature of 1250 ° C., a pressure of 145 MPa, and a holding time of 5 hours, and then the pressurized container 2 is removed by machining to obtain a cylindrical target material having a total length of 670 mm. Obtained.

The cylindrical target material obtained above does not show any abnormal parts on the appearance such as deformation due to breakage of the cylindrical molded body 1 or abnormal shrinkage locally, and the bending at the full length is less than 3 mm. It was confirmed that the target material had a good shape. Further, a test piece was collected from the cylindrical sintered body by machining, and the density of the sintered body was measured by Archimedes method. As a result, the relative density was 99.0%.
From the above results, it was confirmed that according to the manufacturing method of the present invention, a target material excellent in shape accuracy was obtained.

1 Molded body 2 Pressure vessel 3 Deaeration pipe

Claims (3)

The raw material powder is compression-molded by a cold isostatic press to produce a compacted body, and then the joint surface is cut in parallel so that the compacted body has a predetermined shape dimension , and the jointed surface The other surface is cut into a flat shape to form a molded body, and the molded body is stacked and inserted into a pressure vessel, deaerated and sealed, and then subjected to pressure sintering with a hot isostatic press to obtain a sintered body. A method for producing a target material.   The method for producing a target material according to claim 1, wherein the sintered body is cut into a plurality of pieces in the longitudinal direction.   The method for producing a target material according to claim 1, wherein the sintered body is cut into a plurality of pieces in a direction perpendicular to the longitudinal direction.