JP2013083000A - METHOD OF MANUFACTURING SINTERED Mo ALLOY SPUTTERING TARGET MATERIAL - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method by which a sintered Mo alloy sputtering target material with low oxygen can be produced even by simplified manufacturing step.SOLUTION: This method is used to manufacture an Mo alloy sputtering target material which contains 0.5-60 atom% of one or more metal elements M selected from a group (Ti, Nb, Ta) and the balance being Mo and inevitable impurities. The Mo material powder and powder of the hydrogenated metal element M with an average particle size of 200 μm or less are mixed, and the mixed powder is put in a pressurizing container. While the pressurizing container is heated, it is decompressed and deaerated, and the powder is pressurized and sintered by hot isostatic pressing to manufacture an Mo alloy sintered body.

Description

  The present invention relates to a method for producing a sputtering target material used for forming Mo alloy thin films such as MoTi, MoNb, and MoTa used for electrical wiring, electrodes and the like of flat display devices.

  At present, refractory metal films such as Mo having a small electric resistance are widely used for thin film electrodes and thin film wirings of a liquid crystal display (Liquid Crystal Display) which is a kind of flat display device. These thin film electrodes, thin film wirings, and the like have requirements for heat resistance and corrosion resistance during the manufacturing process of thin film formation. For example, Mo alloys to which transition metal elements having high melting points such as Ti, Nb and Ta are added (For example, refer to Patent Document 1).

  As a method of forming the Mo alloy as a wiring, a method of forming a sputtering target material having the same composition by sputtering is generally used. And about the sputtering target material of Mo alloy, various proposals are made regarding a component structure, reduction of impurities contained in the sputtering target material, and the like.

For the production of a Mo alloy sputtering target material mainly composed of Mo having a high melting point, a powder sintering method is generally used. Mo alloy sputtering target materials used for forming thin film electrodes and thin film wirings are required to reduce the oxygen content affecting the electrical resistance of the thin film as much as possible, but the raw material powder is sintered to produce the sputtering target material. In the powder sintering method, there is a limit in reducing the oxygen content.
Further, the applicant of the present application, in a Mo alloy containing Nb or the like having a high affinity with oxygen, causes a splash when a coarse oxygen-concentrated phase is formed around Nb grains in the microstructure. A method for producing a Mo alloy sputtering target by reducing the oxygen content of the Mo raw material powder before sintering as much as possible has been proposed (for example, see Patent Document 2).
Patent document 2 pays attention to the oxygen content of Mo powder used as a sintering raw material in order to reduce the oxygen content contained in the MoNb sputtering target material. Thereafter, the secondary powder of the pulverized Mo is used as a raw material powder for the MoNb sputtering target. This Mo secondary powder can reduce the surface area of the powder and reduce the oxygen content present on the surface of the Mo powder compared to the Mo raw material powder, which is agglomerated fine Mo primary particles produced by a commercially available chemical manufacturing method. Therefore, it is proposed that the oxygen content of the Mo raw material powder itself can be reduced and the oxygen content of the sputtering target material as the final product can be reduced.

Japanese Patent No. 3859119 JP 2008-280570 A

The method disclosed in Patent Document 2 is an effective invention for producing a low oxygen Mo alloy sputtering target containing an additive element such as Nb. On the other hand, this method does not simply mix and sinter raw material powders, but sinters Mo raw material powders once to make Mo sintered bodies, and then pulverizes and heats them again to produce reduced Mo powders. As described above, it is necessary to pre-process the raw material powder in order to reduce oxygen in the sputtering target material, and there is a problem that the manufacturing cost increases as the number of steps increases.
In addition, transition metal elements having a high melting point such as Ti, Nb, and Ta that form Mo alloys have a high affinity for oxygen, a high oxygen content in the powder state, and an oxygen content during handling of the powder. Since it rises easily, when producing the sintered body of Mo alloy with a powder sintering method, there exists a subject that it is difficult to reduce oxygen.

  In view of the above problems, an object of the present invention is to provide a manufacturing method capable of obtaining a low-oxygen sintered Mo alloy sputtering target material even in a simplified manufacturing process.

  As a result of various investigations on the above problems, the present inventors have performed dehydrogenation treatment by performing depressurization treatment on a pressure vessel filled with the mixed powder in addition to using the hydrogenated metal element M powder. At the same time, it has become possible to reduce the oxygen content of the sintered Mo alloy sputtering target material, and found that the above-mentioned problems can be solved, thereby reaching the present invention.

  That is, the present invention contains 0.5 to 60 atomic% of one or more metal elements M selected from the group of (Ti, Nb, Ta), the balance being Mo and Mo consisting of inevitable impurities. A method for producing an alloy sputtering target material, wherein a mixed powder obtained by mixing a Mo raw material powder and a hydrogenated metal element M powder having an average particle size of 200 μm or less is filled in a pressure vessel, and then the pressure vessel Is a method for producing a sintered Mo alloy sputtering target material in which a Mo alloy sintered body is produced by subjecting to vacuum degassing while heating and then pressure sintering with a hot isostatic press.

  Moreover, as a manufacturing method of the sintering Mo alloy sputtering target material of this invention, it is preferable to perform the said pressure reduction deaeration process, heating in the range of 300-1000 degreeC.

  By applying the manufacturing method of the present invention, the oxygen content of the sintered Mo alloy sputtering target material can be reduced. In addition, the production method of the present invention can eliminate the preliminary sintering step for reducing the oxygen content of the raw material powder disclosed in Patent Document 2 described above, thereby contributing to the reduction in production cost associated with the reduction in man-hours. It becomes a technique useful for the manufacturing method of sintered Mo alloy sputtering target material.

  The sintered Mo alloy sputtering target material in the production method of the present invention contains 0.5 to 60 atom% of one or more metal elements M selected from the group of (Ti, Nb, Ta), and the balance Consists of Mo and inevitable impurities. In particular, sputtering targets used for forming thin film electrode films and thin film wiring films have demands for heat resistance and corrosion resistance of electrodes and wiring, and in order to improve the corrosion resistance and heat resistance of Mo, Ti, Nb, Ta Etc. are required to be added. It is particularly desirable to select Nb as an additive element to Mo because heat resistance and corrosion resistance can be improved while suppressing an increase in electrical resistance when forming an electrode / wiring film.

In the present invention, first, a powder of one or more metal elements M selected from the group of Mo raw material powder and hydrogenated (Ti, Nb, Ta) having an average particle size of 200 μm or less is mixed. The mixture powder is filled into a pressurized container.
Ti, Nb, and Ta are elements having high affinity with oxygen. When a sputtering target material is manufactured by a powder sintering method, if a single metal is used as a raw material powder, the amount of oxygen increases when handling the powder. Therefore, it is difficult to reduce the oxygen content of the sputtering target material. Therefore, in reducing the oxygen content as a sputtering target material, the production method of the present invention using a hydrogenated metal element M powder is effective.
The reason why the powder of the metal element M hydrogenated in the present invention is used is that, in addition to the low oxygen content in the powder state, the increase in the oxygen content of the powder accompanying handling can be suppressed. Note that Ti, Nb, and Ta, which are metal elements M, are all metal elements that are easily hydrogenated because of their high affinity with hydrogen, and are convenient for hydrogenation for the above purpose.
As the particle size of the metal element M powder, when the particle size of the metal element M powder is coarse, the metal element M tends to segregate in the sputtering target structure obtained after sintering. For this reason, in this invention, the average particle diameter of the powder of the metal element M was 200 micrometers or less. Further, when the particle size of the powder of the metal element M is fine, the specific surface area per unit volume is increased, and oxygen adsorbed on the powder surface tends to increase, so that the amount of oxygen in the powder tends to increase. Become. For this reason, it is desirable to use a powder having an average particle size of 10 μm or more as the powder of the metal element M applied in the present invention.
Moreover, as Mo raw material powder, it is desirable to use the powder of the average particle diameter of 2-15 micrometers which can be generally purchased.

In the present invention, the degassing treatment is performed while heating the pressurized container filled with the above mixed powder. As a result, the present invention eliminates the need to produce a reduced powder by re-grinding and heat-treating the raw material powder once, and even in a simplified process, the hydrogenated metal element M in the mixed powder At the same time that the hydrogen contained in the powder is removed, the amount of oxygen in the mixed powder can also be reduced.
Here, the vacuum degassing treatment is desirably performed in a temperature range of 300 to 1000 ° C. This is because the effect of removing hydrogen is extremely small even if the vacuum degassing treatment is performed at a temperature less than 300 ° C. On the other hand, when the vacuum degassing treatment is performed at a temperature exceeding 1000 ° C., the mixed powder in the pressurized container is sintered and a large number of pores remain, which is then applied by hot isostatic pressing (hereinafter referred to as HIP). This is because the density of the sintered body may not increase even when pressure sintering is performed. Moreover, since the pressurized container may be rapidly oxidized when the temperature of the vacuum degassing treatment exceeds 1000 ° C., this may damage the pressurized container and make subsequent HIP difficult.
In addition, as a depressurization condition in the depressurization treatment, if the temperature range is as described above, the higher the depressurization level, the easier it is to remove oxygen and hydrogen present in the pressurized container. A vacuum degassing process is desirable. Thereby, oxygen and hydrogen present in the pressurized container can be removed. Further, considering the equipment capacity of a pump or the like used for vacuum degassing, it is more desirable to perform the vacuum degassing treatment until the vacuum pressure is reached from 0.1 Pa.

As pressure sintering, hot press, HIP, etc. can be applied. In the present invention, a high-density sintered body is obtained by sintering raw material powder by applying a three-dimensionally high pressure. HIP that can be applied. As conditions for pressure sintering with HIP, it is desirable to apply conditions of a temperature of 1000 to 1500 ° C. and a pressure of 100 MPa or more. This is because it is difficult to produce a sintered body having a relative density of 98% or more required for the sputtering target material even when HIP is performed at a pressure less than 100 MPa and a temperature less than 1000 ° C.
Further, in order to obtain a sintered body made of Mo having a high melting point and Ti, Nb and / or Ta, it is desirable to perform the treatment at as high a temperature as possible and at a high pressure. However, since there are restrictions on the equipment as well as the materials used for the pressurized container, the HIP conditions are such that when an existing general HIP apparatus is used, the temperature is 1500 ° C. and the pressure is 200 MPa.

First, commercially available Mo raw material powder having an average particle size of 6 μm (oxygen amount: 349 mass ppm, hydrogen content: 15 mass ppm) and hydrogenated Nb powder having an average particle size of 90 μm obtained by sieving commercially available powder (oxygen amount: 588 mass ppm) , 10800 mass ppm of hydrogen) was prepared, weighed to 90% Mo-10% Nb in atomic%, and then mixed with a V-type mixer to obtain a mixed powder. Here, an oxygen amount was measured from a part of the obtained mixed powder by an inert gas melting-non-dispersive infrared absorption method, and a hydrogen amount was measured by heating in an inert gas / melting column separation-thermal conductivity method. The measurement results are shown in Table 1.
Next, after filling the obtained mixed powder into a pressure vessel made of mild steel, it was sealed by performing vacuum degassing to 0.1 Pa while heating at a temperature of 450 ° C. Then, it pressure-sintered with HIP hold | maintained for 5 hours on the conditions of temperature 1250 degreeC and pressure 150MPa, and obtained Mo alloy sintered compact. This Mo alloy sintered body was cut and machined to obtain a sintered Mo alloy sputtering target material having a diameter of 50 mm and a thickness of 50 mm.
In addition, a test piece was collected from the Mo alloy sintered body obtained above, and the oxygen content was measured by inert gas melting-non-dispersive infrared absorption method, heating in inert gas / melting column separation-thermal conductivity method. The amount of hydrogen was measured. The results are shown in Table 1. Moreover, when the relative density was measured by the Archimedes method using the said test piece, the relative density was 99.3%. Here, the relative density is 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 sintered Mo alloy sputtering target material. The value obtained by multiplying 100 by 100.

As a comparative example, a Mo alloy sputtering target material containing Nb was produced by the following conventional manufacturing method.
Commercially available Mo powder having an average particle size of 6 μm (oxygen amount: 349 mass ppm, hydrogen content: 15 mass ppm) and commercially available non-hydrogenated Nb powder having an average particle size of 90 μm (oxygen amount: 920 mass ppm, hydrogen content: 16 mass ppm) After being weighed so as to be 90% Mo-10% Nb in atomic%, a granulated powder obtained by pulverizing a compact obtained by compression molding the mixed powder mixed to obtain a powder again was produced. The granulated powder was filled in a pressure vessel made of mild steel, and then subjected to vacuum degassing treatment to 0.1 Pa while being heated at a temperature of 450 ° C. and sealed. Then, it pressure-sintered with HIP hold | maintained for 5 hours on the conditions of temperature 1250 degreeC and pressure 150MPa, and obtained Mo alloy sintered compact. This Mo alloy sintered body was cut and machined to obtain a sintered Mo alloy sputtering target material of 960 mm × 855 mm × 6 mm.
In addition, using the sample of the mixed powder obtained above and the test piece collected from the Mo alloy sintered body, the amount of oxygen was determined by inert gas melting-non-dispersive infrared absorption method, and the heating / melting column in inert gas was used. The amount of hydrogen was measured by a separation-thermal conductivity method. The results are shown in Table 1. Moreover, when the relative density was measured by the Archimedes method using the said test piece, the relative density was 99.2%.

  As shown in Table 1, when looking at the sintered Mo alloy sputtering target material obtained by the production method of the present invention, the amount of oxygen compared to that obtained by applying the vacuum degassing treatment to the conventional production method as well Further, the effect of reducing the amount of hydrogen was remarkable, and the effectiveness of the production method of the present invention was confirmed.

First, a commercially available Mo raw material powder having an average particle size of 6 μm (oxygen amount 548 mass ppm, hydrogen amount 15 mass ppm) and a hydrogenated Ta powder having an average particle size of 30 μm obtained by sieving commercially available powder (oxygen amount 1070 mass ppm) , 4700 mass ppm of hydrogen) was prepared, weighed so that it would be 90% Mo-10% Ta in atomic%, and then mixed with a V-type mixer to obtain a mixed powder. Here, an oxygen amount was measured from a part of the obtained mixed powder by an inert gas melting-non-dispersive infrared absorption method, and a hydrogen amount was measured by heating in an inert gas / melting column separation-thermal conductivity method. The measurement results are shown in Table 2.
Next, after filling the obtained mixed powder into a pressure vessel made of mild steel, it was sealed by performing vacuum degassing to 0.1 Pa while heating at a temperature of 450 ° C. Then, it pressure-sintered with HIP hold | maintained for 5 hours on the conditions of temperature 1250 degreeC and pressure 150MPa, and obtained Mo alloy sintered compact. This Mo alloy sintered body was cut and machined to obtain a sintered Mo alloy sputtering target material having a diameter of 50 mm and a thickness of 50 mm.
In addition, a test piece was collected from the Mo alloy sintered body obtained above, and the oxygen content was measured by inert gas melting-non-dispersive infrared absorption method, heating in inert gas / melting column separation-thermal conductivity method. The amount of hydrogen was measured. The results are shown in Table 2. Moreover, when the relative density was measured by the Archimedes method using the said test piece, the relative density was 99.2%.

As a comparative example, a Mo alloy sputtering target material containing Ta was produced by the following conventional manufacturing method.
Commercially available Mo powder with an average particle size of 6 μm (oxygen amount 548 mass ppm, hydrogen amount 15 mass ppm) and commercially available non-hydrogenated Ta powder with an average particle size 30 μm (oxygen amount 1575 mass ppm, hydrogen amount 16 mass ppm) After being weighed so as to be 90% Mo-10% Ta in atomic%, a granulated powder obtained by pulverizing a molded body obtained by compression molding the mixed powder mixture to obtain a powder again was produced. The granulated powder was filled in a pressure vessel made of mild steel, and then subjected to vacuum degassing treatment to 0.1 Pa while being heated at a temperature of 450 ° C. and sealed. Then, it pressure-sintered with HIP hold | maintained for 5 hours on the conditions of temperature 1250 degreeC and pressure 150MPa, and obtained Mo alloy sintered compact. This Mo alloy sintered body was cut and machined to obtain a sintered Mo alloy sputtering target material having a diameter of 50 mm and a thickness of 50 mm.
In addition, using the sample of the mixed powder obtained above and the test piece collected from the Mo alloy sintered body, the amount of oxygen was determined by inert gas melting-non-dispersive infrared absorption method, and the heating / melting column in inert gas was used. The amount of hydrogen was measured by a separation-thermal conductivity method. The results are shown in Table 2. Moreover, when the relative density was measured by the Archimedes method using the said test piece, the relative density was 99.2%.

  As shown in Table 2, when looking at the sintered Mo alloy sputtering target material obtained by the production method of the present invention, the amount of oxygen is higher than that obtained by applying the vacuum degassing treatment to the conventional production method. Further, the effect of reducing the amount of hydrogen was remarkable, and the effectiveness of the production method of the present invention was confirmed.

Claims (2)

  Production of Mo alloy sputtering target material containing 0.5-60 atomic% of one or more metal elements M selected from the group of (Ti, Nb, Ta), with the balance being Mo and inevitable impurities A mixed powder obtained by mixing Mo raw material powder and the hydrogenated metal element M powder having an average particle size of 200 μm or less is filled in a pressure vessel, and then the pressure vessel is depressurized while being heated. A method for producing a sintered Mo alloy sputtering target material, characterized in that a Mo alloy sintered body is produced by pressure sintering with a hot isostatic press after performing gas treatment.   The method for producing a sintered Mo alloy sputtering target material according to claim 1, wherein the vacuum degassing treatment is performed while heating in a range of 300 to 1000 ° C.