JP2009041106A - Sputtering target - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sputtering target which can provide film properties of being homogeneous and excellent in corrosion resistance, has excellent film deposition efficiency and reproducibility, and also has a long life. <P>SOLUTION: The sputtering target is provided which contains Cr of ≥45 atomic%, contains Al in the range of 1 to 50 atomic%, and also contains at least one kind of element selected from among Ti, Zr, Hf, V, Nb, Ta, W, Mo and B in the range of 1 to 50 atomic%. The sputtering target is characterized in that when the structural region of 200 μm square in the sputtering target is subjected to Cr element mapping at an accelerating voltage of 15 kV by an X-ray microanalyzer, the diameter of the segregated part in the Cr whose number of counts is ≥600 is ≤50 μm. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a sputtering target for forming a film on a surface of a metal member by a sputtering method or the like, and more particularly to a sputtering target capable of forming a hard film.

  Molds used when forging cold, warm, or hot metal parts such as automobile parts, machine parts, home appliance parts, etc., have a high temperature during use. Therefore, damage due to oxidation on the surface of a molding die or the like, generation of fatigue cracks due to repeated thermal stress, and the like occur, and a “skin roughness” (increase in surface roughness) phenomenon occurs on the molding surface. This “rough skin” progresses as the number of molding processes (shots) increases, and it becomes difficult to maintain dimensional accuracy.

  In order to delay such damage to the mold as much as possible and extend the service life, forging molds and the like are subjected to nitriding such as tuftride treatment (salt bath nitriding treatment), gas nitriding treatment, ion nitriding treatment, nitrosulphurizing treatment, etc. Processing is widely performed. The characteristics of these nitriding treatments are to diffuse and infiltrate nitrogen-based elements on the surface of a base metal such as a metal mold, increase the surface hardness, introduce surface compression stress, etc. Improves durability.

  However, the nitriding treatment cannot improve the oxidation resistance of the mold surface. For this reason, the surface of the mold or the like is oxidized, and this oxide layer grows and peels off, and oxidation occurs again. Such a cycle damages the surface of the mold or the like due to oxidation.

Examples of the surface treatment method other than the nitriding treatment include a method of forming a hard coating such as chromium nitride, titanium carbide, titanium nitride or the like by a chemical vapor deposition method (CVD method), a physical vapor deposition method (PVD method) or the like.
JP 2000-199055 A JP 2002-212707 A

  Examples of the member that needs to be coated with a hard coating include, for example, cutting tools, blades, and automobile parts in addition to the forging die described above. Members with these coatings formed on the surface are required to have further improved durability.

  Sputtering is employed as a method for forming a film on the metal member, and a sputtering target is used. As such a sputtering target, there is one described in Japanese Patent Application Laid-Open No. 9-95751, which discloses a sputtering target produced by a high frequency melting furnace containing Cr and Al and Si as a main component.

  In this sputtering, the properties of the sputtering target affect the properties of the coating film formed on the surface of the member, and in particular, a uniform dispersibility of the metal elements constituting the sputtering target is required. When sputtering is performed using a target in which segregation of a metal element occurs, partial deterioration in film characteristics occurs.

  However, it has not been said that the conventional sputtering target sufficiently satisfies the required characteristics. For example, when a Cr—Al—Si alloy is prepared by a melting method, materials having different melting points (Cr melting point: 1860 ° C., Al melting point: 660 ° C., Si melting point: 1410 ° C., see Riken) are uniformly dissolved and mixed. In addition, process management becomes complicated, leading to increased costs. Even with the dissolution method, a uniform structure has not necessarily been obtained. It has been found that when the number of segregated portions of Cr increases (or increases), when the portion is sputtered, a Cr-rich film is formed and the uniformity of the film cannot be maintained.

  The present invention has been made in consideration of the above-mentioned problems, and provides a sputtering target having a uniform film property with excellent corrosion resistance and excellent film forming efficiency and reproducibility when forming a film on a metal member. For the purpose.

  The inventors of the present invention have studied a method for solving the above-described problems, and have focused particularly on the dispersibility of Cr, Si, or Al, which are constituent metals of the sputtering target. As a result, the inventors have obtained the knowledge that the above problem can be effectively solved by defining the size of the Cr segregation part, and the present invention has been completed.

  That is, the sputtering target according to the present invention contains 45 atomic% or more of Cr, Al in the range of 1 to 50 atomic%, and Ti, Zr, Hf, V, Nb, Ta, W, Mo, B. A sputtering target containing 1 to 50 atomic% of at least one element selected from the following: a 200 μm square structure region of this sputtering target is mapped with Cr element at an acceleration voltage of 15 kV using an X-ray microanalyzer Is carried out, the diameter of the segregated portion of Cr having a count number of 600 or more is 50 μm or less.

  FIG. 1 schematically shows the result of EPMA mapping of the sputtering target. In FIG. 1, the observation surface of the sputtering target is composed of a Cr segregation portion 1 having a count number of 600 or more and a Cr—Al molten phase 2 having a count number of less than 600. Here, the diameter of the Cr segregating portion 1 is defined as an arithmetic average of the major axis (longest diagonal length) and the minor axis (diagonal length orthogonal to the midpoint of the major axis) of the Cr segregating portion 1.

  As shown in FIG. 1, the maximum diameter of the Cr segregation part 1 is 50 μm or less in the sputtering target of the present invention.

  When there are a large number of such Cr segregation parts, it is difficult to obtain uniform film characteristics when forming a film using a sputtering target. The reason why the diameter of the segregation part is defined to be 50 μm or less is that when the segregation part exceeds 50 μm, the properties of the obtained film are deteriorated.

  Further, in the sputtering target according to the present invention, when the Cr element is mapped at an accelerating voltage of 15 kV by an X-ray microanalyzer in the 200 μm square structure region of the sputtering target, the segregation of Cr having a count number of 600 or more. The variation in the area ratio of the part is preferably within 30%.

  The variation in the area ratio of the Cr segregation part is the measurement point of the sputtering target shown in FIG. 2, that is, the central part (position 1) and the four linear outer peripheral positions that divide the circumference evenly through the central part ( Sampling was performed at positions 2 to 9) and positions at a distance of 1/2 in the radial direction (positions 10 to 17), and the area ratios of Cr segregation portions of these sampling samples were measured and compared.

  The variation was calculated by the formula [(maximum value−minimum value) / (maximum value + minimum value) × 100 (%)] based on the maximum value and the minimum value of the sampling material. It is preferable that the variation value of the area ratio of the Cr segregation portion is 30% or less. If the variation exceeds 30%, uniform film characteristics cannot be obtained at the time of film formation, and the product yield decreases. The variation is more preferably 15% or less.

  Further, according to the knowledge of the present inventors, the sputtering target preferably contains Cr as a main component and at least one metal element selected from Al and Si. The content of at least one of Si and Al is preferably in the range of 1 to 50 atomic%. More preferably, it is 3-50 atomic%.

  Furthermore, the sputtering target is configured to contain 1 to 50 atomic% of at least one metal element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, B, Mo, B, and W. May be.

  Of the metal elements contained in the sputtering target, Al and Si are components that mainly improve the oxidation resistance of the formed film. Therefore, it is preferable that at least one metal element of Al and Si is contained in the sputtering target.

  Ti, Zr, Hf, Mo, W, and B are components that combine with the nitrogen gas existing under the sputtering conditions to generate nitrides and mainly improve the wear resistance of the film. V, Nb and Ta are effective components for enhancing the lubricity of the film.

  Which one of these elements is selected, the combination thereof, the abundance ratio of each element, and the like can be appropriately determined according to the specific purpose or use of the sputtering target, the characteristics of the film formed therefrom, and the like.

  Moreover, it is preferable that the diameter of the defect observed in arbitrary cross sections is 0.6 mm or less.

  According to the present inventors, the defect of the sputtering target is configured such that the diameter observed in an arbitrary cross section is 0.6 mm or less and there are no defects such as pores having a diameter exceeding 0.6 mm. It is possible to prevent deterioration of the film characteristics during film formation.

  Furthermore, the sputtering target of the present invention is used as a target for performing sputtering in a gas atmosphere to form a hard film having a Vickers hardness Hv0.05 of 500 or more. By using a nitrogen-containing or carbon-containing atmosphere such as nitrogen gas or methane gas as the atmosphere gas, it is possible to form a uniform and hard nitride film, carbonized film or nitrocarburized film.

  Moreover, the sputtering target of the present invention is used for various dry process deposition such as vacuum deposition, sputtering, or ion plating. Among them, the application to the arc ion plating method is most effective because the adhesion of the film is strong, the porosity is low, and the mechanical strength is also good.

  The sputtering target according to the present invention can be manufactured by any method. For example, a powder metallurgy method (sintering method) in which a mixed powder is used to perform atmospheric pressure sintering, a hot press (HP) method, a hot isostatic pressure (HIP) method, or a powder that has been previously alloyed is used. Powder metallurgy and melting methods. Particularly in the case of powder metallurgy using mixed powder, it is necessary to appropriately adjust the particle size of the metal raw material powder to be mixed, the mixing time by a ball mill, the sintering temperature, the sintering time, and the like. In the case of powder metallurgy, since raw material powders can be mixed uniformly, it is easy to keep the dispersed state of the segregated portion of Cr after sintering uniform. It is also effective to sinter using Cr alloy powder.

When these metal powders are sintered by, for example, a hot press method, it is preferable to perform a degassing process by heating in a vacuum (for example, a degree of vacuum of 5 × 10 ⁻² Pa or less) for a predetermined time. It is sufficient that this degassing treatment is carried out at a temperature of 300 to 500 ° C. for 2 to 10 hours. By performing degassing treatment, gas components such as nitrogen, hydrogen and oxygen can be removed, so that the maximum diameter of defects such as vacancies can be easily reduced to 0.6 mm or less.

  A case where a target is manufactured by a vacuum melting method will be described. The vacuum melting method includes various melting methods such as an arc melting method and an EB melting method, but the arc melting method is more preferable from the viewpoint of suppressing variation in the Cr segregation part.

  Needless to say, after sintering (after melting), the shape of the target may be adjusted by machining as necessary.

  On the other hand, the hard coating formed using the sputtering target of the present invention is a homogeneous and hard coating, and the hard coating member provided with the hard coating on the surface of the substrate is excellent in durability and corrosion resistance. It can be a member. The base material surface on which the hard coating is provided includes not only the base material (base material) surface constituting the hard coating member, but also includes a mode in which an intermediate layer is provided on the base material surface and a hard coating is provided on the intermediate layer. .

  According to the sputtering target, the hard coating, and the hard coating member according to the above configuration, when the film is formed on a base material such as a metal, uniform and excellent coating properties can be obtained, and the film forming efficiency and reproducibility are excellent. It is possible to provide a sputtering target and a long-life hard coating and hard coating member.

  Moreover, since the sputtering target which concerns on the said structure can be produced also by a powder metallurgy method (sintering method), it is also possible to produce it cheaply compared with the conventional melt | dissolution method.

  Next, specific examples of the present invention will be described. In the following embodiment, the symbols A and B attached to the sample numbers of the examples and comparative examples represent differences in the respective manufacturing methods. That is, A prepared a sputtering target using a material obtained by melting a metal material by a vacuum melting method, and using this as an alloy powder by a gas atomizing method, and B manufactured a sputtering target using a material obtained by mixing each metal powder with a ball mill. It shows that.

<Example A>
An electrolytic material having the composition shown in Table 1 was melted in vacuum, and an alloy powder was produced by a gas atomization method. Thereafter, the obtained powder was sieved and subjected to particle size selection. An alloy powder having a particle size shown in Table 1 is set in a carbon mold, and a degassing treatment is performed by maintaining the degree of vacuum at 2 × 10 ⁻² Pa, a heating rate of 5 ° C./minute, and holding at 500 ° C. for 5 hours. Hot pressing was performed at a sintering temperature of 1300 ° C. for 5 hours and a sintering pressure of 24.5 MPa.

  The obtained sintered body was machined to produce a sputtering target having a diameter of 5 inches and a thickness of 10 mm.

  Further, using these sputtering targets, a coating was formed on a hot metal mold made of Co-containing high-speed steel by arc ion plating.

In the ion plating, a reaction N ₂ gas pressure of 1 Pa and a bias voltage of −150 V were applied at a substrate temperature of 400 ° C., and processing was performed until the film thickness reached 10 μm. A film was formed on a total of 100 hot mold punches. Samples were cut out from the sputtering target after use, and EPMA analysis was performed on 200 μm square with the analysis conditions of acceleration voltage 15 kV, irradiation current 2 × 10 ⁷ A, time 30 msec, and the number of counts in the obtained Cr mapping diagram The diameter of the Cr segregation part having a thickness of 600 or more was measured. Moreover, the diameter of the Cr segregation part was measured about 17 measurement points shown in FIG. 2, and the dispersion | variation in the area ratio of a Cr segregation part was measured by the said formula.

  Die life evaluation during hot forging was actually performed. The mold life was determined by the number of continuous moldings (shots) until the hard coating formed on the mold surface was damaged and the dimensional accuracy of the workpiece (molded product) was outside the specified range.

<Example B>
The metal powder having the composition and particle size shown in Table 1 was subjected to ball mill mixing in an Ar atmosphere for the time shown in Table 1. Next, this mixed powder was set in a carbon mold, and degassing treatment was performed by maintaining the degree of vacuum at 2 × 10 ⁻⁴ Pa, the heating rate of 5 ° C./min, and at 500 ° C. for 5 hours, and the sintering temperature was 1300 Hot pressing was performed at 5 ° C. for 5 hours at a sintering pressure of 24.5 MPa to prepare a target sintered body.

  The obtained sintered body was machined to produce a sputtering target having a diameter of 5 inches and a thickness of 10 mm.

  Film formation, EPMA analysis, and mold life evaluation were performed in the same manner as in Example A.

<Example C>
A target having the same composition as that of Example A-1 was produced by an arc melting method.

  Film formation, EPMA analysis, and mold life evaluation were performed in the same manner as in Example A.

<Comparative Example B>
The metal powder having the composition and particle size shown in Table 1 was ball mill mixed in an Ar atmosphere over the time shown in Table 1. Next, the mixed powder is filled into a carbon mold, and degassing is performed by holding at 500 ° C. for 5 hours in the middle of a vacuum degree of 2 × 10 ⁻² Pa, a heating rate of 5 ° C./min, and a sintering temperature of 1300 Hot pressing was performed at 5 ° C. for 5 hours at a sintering pressure of 24.5 MPa.

  The obtained sintered body was machined to produce a sputtering target having a diameter of 5 inches and a thickness of 10 mm.

  Film formation, EPMA analysis, and mold life evaluation were performed in the same manner as in Example A.

<Comparative Example C>
A target having the same composition as that of Example A-1 was produced by the EB dissolution method.

  Film formation, EPMA analysis, and mold life evaluation were performed in the same manner as in Example A.

Table 1 shows the test results of Example A, Example B, Example C, Comparative Example B, and Comparative Example C.

  As shown in Table 1, as is clear from Example A-1 to Example A-9, the mold formed by sputtering target produced by sintering the alloy powder has a Cr segregation size of all implementations. In the example, it was 10 μm or less.

  Further, the variation was suppressed to a minimum of 2% in Example A-3, and 13% was also obtained in Example A-9 showing the maximum variation, indicating a very good result. The mold life evaluation was 12000 shots or more for all the examples A, and it was found that a strong and uniform metal film can be formed. That is, the life of the coating is long, and as a result, the life of the molding die can be extended.

  Further, in Example A in which an alloy powder was manufactured by a vacuum melting method and a gas atomizing method and a sputtering target was produced, the particle size was different with the same metal composition by comparison between Example A-1 and Example A-7. It has been found that sputtering targets produced from metal powders do not produce significant differences in their properties. This was considered because each metal element was uniformly dispersed by the vacuum melting method.

  On the other hand, in Example B-1 to Example B-17, film formation was performed on a mold using a sputtering target produced by mixing each metal powder material for 24 hours with a ball mill, and the performance was evaluated. According to this, first, when the performance of Example B having the same composition as that of Example A is compared, for example, in comparison between Example A-1 and Example B-1, Example B-1 Although the variation in the area ratio of the Cr segregation part is 10%, which is a little larger than 3% of Example A-1, it maintains good quality as a sputtering target, and other similar compositions are carried out. Also in the comparison between Example A and Example B, it was found that the influence on the quality of the sputtering target and the quality of the mold due to the difference in the manufacturing method between the gas atomizing method and the method using the ball mill was found to be small.

  Further, also in the comparison of the segregation sizes, in Example B-1 to Example B-17, the segregation size is suppressed to about 10 μm or less, and is about 20 μm at the maximum, which does not cause a quality problem as a sputtering target.

  That is, it was judged that a sputtering target having the same quality as the sputtering target manufactured by the vacuum melting method can be obtained by mixing the alloy powder for 24 hours or more as in Example B with a ball mill.

  As a result of studying Example A and Example B together, it was found that when the metal composition was changed in the range of Examples A and B, there was no significant difference in the quality of the sputtering target and the coating properties of the mold. did.

  Therefore, from the results of Example A and Example B, the present inventors have specified the addition amount of at least one of Al and Si as 1 to 50 atomic% as the composition of the sputtering target mainly composed of Cr. . Further, the composition range of Ti, Zr, Hf, V, Nb, Ta, W, Mo, and B was specified to be 1 to 50 atomic%.

  Furthermore, Comparative Example B-1 to Comparative Example B-23 were compared by changing the mixing time by the ball mill and changing the particle size of the alloy powder when producing the sputtering target by mixing the metal material powder. . According to this comparative example, for example, according to the data of comparative example B-8 and comparative example B-10, the Cr segregation of the sputtering target increases due to the difference in the particle size of the alloy powder.

  In Comparative Example B-1 to Comparative Example B-23, the variation of the diameter of the Cr segregation part and the area ratio is generally large, and the mold life evaluation is 6000 shots to 8000 shots as compared with the molds of the examples. It is about half. In particular, when the particle size is 150 μm or more and the mixing time by the ball mill is 5 hours as in Comparative Example B-15 or Comparative Example B-18, the Cr segregation size is 100 or more and the variation in the area ratio is 30% or more. Did not meet the required quality.

  That is, in the sputtering target of the present invention, when mixing the alloy powder by a ball mill, it was determined that a sufficient mixing time is required and that the powder particle size is preferably smaller. Further, when Example C and Comparative Example C were compared, it was found that the arc melting method is preferable when the vacuum melting method is used.

  As described above, according to the sputtering target, the hard coating, and the hard coating member according to the present invention, when forming a film on a metal member, uniform and excellent corrosion resistance can be obtained, and the deposition efficiency and reproducibility can be obtained. It is possible to provide an excellent sputtering target, and a long-life hard coating and hard coating member.

The figure which shows typically the mapping result by EPMA of a sputtering target. The top view which shows the investigation location of the dispersion | variation in the area ratio of Cr segregation part in a sputtering target.

Explanation of symbols

1 Cr segregation part 2 Cr-Al molten phase

Claims (9)

Contains at least one element selected from Ti, Zr, Hf, V, Nb, Ta, W, Mo, and B, containing 45 atomic% or more of Cr, Al in the range of 1 to 50 atomic% A sputtering target contained in the range of 1 to 50 atomic%, and when a Cr element is mapped with an acceleration voltage of 15 kV on a 200 μm square structure region of this sputtering target by an X-ray microanalyzer, the count number is 600 The diameter of the Cr segregation part as described above is 50 μm or less. When the Cr element mapping was performed on the 200 μm square structure region of the sputtering target with an X-ray microanalyzer at an acceleration voltage of 15 kV, the variation in the area ratio of the Cr segregation part with a count number of 600 or more was within 30%. The sputtering target according to claim 1, wherein: The sputtering target according to claim 1 or 2, wherein the maximum diameter of defects observed in an arbitrary cross-sectional structure of the sputtering target is 0.6 mm or less. The sputtering target according to claim 1 or 2, wherein the sputtering target is produced by a powder metallurgy method. The sputtering target according to claim 1 or 2, wherein a raw material powder subjected to degassing treatment is used. 6. The sputtering target according to claim 1, wherein the sputtering target is a target for performing sputtering in a gas-containing atmosphere to form a hard coating having a Vickers hardness Hv of 0.05 or more on the surface of the metal member. . The sputtering target according to any one of claims 1 to 6, wherein the sputtering target is used in a vacuum deposition method, a sputtering method, or an ion plating method. The said sputtering target contains W in 1-50 atomic%, The sputtering target of Claim 1 or Claim 2 characterized by the above-mentioned. The sputtering target according to claim 5, wherein the raw material powder has a particle size of 50 to 150 μm.

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