JP4846557B2 - Nitride-containing target material - Google Patents

Description

  The present invention relates to a sputtering target material, and in particular, an evaporation source at the time of coating by an arc ion plating method (hereinafter referred to as AIP method) or a magnetron sputtering method (hereinafter referred to as MS method). The present invention relates to an effective nitride-containing target material.

  In the coating using an alloy target material containing an Si component as an evaporation source, techniques for reducing the occurrence of droplets due to the Si component are disclosed in Patent Documents 1 and 2 below.

JP 2002-212708 A JP 2003-286666 A

The problem to be solved by the present invention is a target material used for the AIP method, which is suitable for forming a high-quality film with improved mechanical strength and suppressed generation of droplets. Is to provide materials.

The present invention relates to Si and M components, wherein the M component is a target material for arc ion plating having one or more elements selected from Periodic Tables 4a, 5a, and 6a group metals, B, and S. The target material has a Si and M component and a Si nitride, and the content of the Si nitride is 5% to 30% in mol%. It is. By adopting the above configuration, when coating is performed by the AIP method, the mechanical strength is improved, the generation of droplets is suppressed, and a suitable target material for forming a high-quality film is provided. Can do. Further, the nitride-containing target material has an M / N value of 0.3 ≦ M / N ≦ 3.0, where M is the content of Si nitride and N is the content of Si. Is preferred.

According to the present invention, in the target material used in the AIP method, it is possible to provide a target material suitable for forming a high-quality film in which mechanical strength is improved and generation of droplets is suppressed.

  The nitride-containing target material of the present invention is used for obtaining a film of nitride, carbonitride, or the like having Si and M components and B and S. In the AIP method, a target material, which is a raw material of a film, is instantaneously dissolved and ionized by arc discharge in a reduced-pressure reaction gas atmosphere, and adhered to a negatively applied coating substrate to form a film. At this time, the dissolved target material is ionized together with the reaction gas in the plasma generated between the coated base material and the target material. For example, a TiSiN hard film is used as a film nitrided using nitrogen as a reaction gas. When a TiSi-based target material is used and a hard film is coated by the AIP method, an arc spot at the time of arc discharge is formed as a site for emitting electrons on the target surface. One or a plurality of arc spots are present during the discharge at the same time, and it is necessary to move on the target surface at high speed and uniformly. However, when the movement of the arc spot is retained, a large dissolved portion is generated in the retained portion, and the dissolved droplet adheres to the substrate surface. The adhering dissolved droplets are called droplets, particles or macro particles, and cause the surface of the hard coating to be roughened. For example, when a coated tool is coated and a large number of droplets adhere, the tool performance is deteriorated. When the target material is homogeneous, such as a single metal or a single structure, the arc spot tends to move uniformly on the surface of the target material. However, when the target material is composed of a plurality of elements and includes a plurality of phases, the arc spot is difficult to move uniformly, and droplets are likely to be included on the surface of the coating. In particular, when the target used in the AIP method includes a component having a relatively low melting point such as Si, the component having a low melting point surrounds the M component element which is another constituent element as a binder and forms a compound at the interface. Thus, it is easy to form a plurality of phases. In the case of a target containing Si as a binder, the target contains an Si single phase, an M component element that is another constituent element, and a compound phase of Si and an M component. This compound is a SiM-based intermetallic compound, and when the M component element is composed of two or more elements, this compound is a SiMy1My2-based compound, provided that y1 ≠ y2. In this case, in the AIP method, arc discharge tends to concentrate particularly on the Si single phase portion. As a result, a lot of droplets are contained on the hard coating surface, resulting in deterioration of surface roughness and non-uniform composition. The hard film containing huge droplets has a drawback that the droplet portion becomes a macro defect and the hardness, heat resistance and fracture resistance are lowered.

  By using the nitride-containing target material of the present invention, the mechanical strength is improved, and a film with an extremely small amount of droplets can be obtained. This is because by including Si nitride in the target, it is possible to reduce the Si single phase that tends to be a droplet generation source without reducing the Si content in the entire target. Moreover, since Si nitride is dispersed in the Si single phase on the evaporation surface, the affinity between Si and Si nitride is high, thus preventing selective dissolution of the Si single phase and avoiding the concentration of arc discharge, The amount of droplets can be reduced. This is because Si nitride is a higher melting point material than Si single phase. As a result, the generation of huge droplets is suppressed. In addition, Si nitride has a high thermal conductivity, plays a role of conducting heat to the powder component constituting the target during sintering, and has an effect of promoting diffusion of target constituent elements. When diffusion of the target constituent element occurs, not only the bonding force between the powder components constituting the target is increased, but also the vacancies existing in the target are reduced, and the mechanical strength of the target itself is improved. Furthermore, there is an effect that the Si single phase having a low melting point is reduced and arc spot concentration is prevented. In addition, since Si nitride contained in the target is dispersed in the Si single phase, when a load is applied to the target, the propagation of cracks is suppressed by the Si nitride, which is a hard particle. It works to increase mechanical strength. Since the film with reduced droplets does not disrupt crystal growth, it forms a high-density film and has excellent mechanical strength.

  The nitride-containing target material of the present invention contains Si nitride, and the content thereof is preferably 5% or more and 30% or less in mol%. When the content of Si nitride is less than 5%, the effect of increasing the moving speed of the arc spot cannot be obtained, so the amount of droplets cannot be reduced. Moreover, there is no effect which raises mechanical strength. On the other hand, when it exceeds 30%, a denitrification phenomenon is likely to occur during the production of the target, and voids are formed inside the target. A large amount of oxygen is taken into the vacancies and a large amount of oxygen, which is an impurity, is taken in, and the mechanical strength deteriorates. As a result, not only instability factors such as local discharge and discharge stop increase at the time of discharge, but also there is a defect that cracking occurs due to impact by arc discharge.

  The nitride-containing target material of the present invention preferably has an M / N value of 0.3 ≦ M / N ≦ 3.0. By setting within this range, the mechanical strength of the target material can be maintained, and the effect of increasing the moving speed of the arc spot can be obtained. When the M / N value is less than 0.3, it is difficult to obtain an effect of improving the mechanical strength of the target material. On the other hand, when the M / N value is larger than 3.0, the proportion of the Si single phase serving as a binder is remarkably reduced, and the mechanical strength of the target is deteriorated.

The Si nitride particles in the nitride-containing target material of the present invention preferably have an average particle size of 5 μm or more and 100 μm or less. When the average particle size is less than 5 μm, the amount of impurities contained in the particles increases. This degrades the mechanical strength of the target material and has the disadvantage that cracks occur due to impacts such as arc discharge. On the other hand, when the thickness exceeds 100 μm, the target structure is not well dispersed, such as partial deviation of the target constituent elements in the target, and a high-quality film cannot be obtained.
The oxygen content in the nitride-containing target material of the present invention is mass% and preferably 0.7% or less. If the content exceeds 0.7%, not only the mechanical strength of the target material is inferior, but also oxygen ions generated during discharge oxidize the target surface, thus forming an electrical insulating material. As a result, the discharge becomes unstable, and an abnormally dissolved portion of the target is easily formed.
When manufacturing a target material containing Si, such as TiSi, a hot press method is used, and Si, which is a metal having a lower melting point than Ti and Cr, serves as a binder to bind other metal elements. For example, in the case of a TiSi-based alloy, a structure of a single Si phase is generated in addition to an intermetallic compound including a Ti phase, a TiSi2 phase, a TiSi phase, a Ti5Si4 phase, a Ti5Si3 phase, and the like. In this Si single phase, the arc spot is stagnated and a huge droplet exceeding 1 μm is generated. If this droplet is generated in a large amount, it will cause a decrease in the function of the hard film to be formed, so it is necessary to reduce the Si single phase. Therefore, in the powder metallurgy method by the hot press method, it is preferable to fabricate at 1200 ° C. or lower in which Si is not melted in an atmosphere containing Ar under reduced pressure. More preferably, the range of 1000 ° C. to 1200 ° C. can be realized by slowly raising the temperature. More preferably, it may be produced slowly at a temperature rising rate of about 150 ° C./hour from a temperature exceeding 800 ° C. When the sintering temperature exceeds 1200 ° C., the Si single phase starts to dissolve, and Si does not function as a binder. Further, a denitrification phenomenon of Si nitride occurs. In addition, when Si carbide or oxide is contained, the electric resistance of the target becomes high, and there is a drawback that discharge becomes difficult. The target material of the present invention can be produced not only by the hot press method by powder metallurgy but also by the HIP method. When applying the HIP method, it is preferable to perform pressurization in the range of 100 MPa to 300 MPa in an atmosphere containing Ar. Carbonitride may be present together with Si nitride. That is, the Si nitride in the target may include Si carbonitride obtained by carbonizing Si nitride particles and Si carbonitride obtained by nitriding Si carbide.
When the target of the present invention is used, the mechanical strength such as hardness, density, toughness, etc. of the resulting hard coating is increased, so it is effective to use it for coatings that require fracture resistance and wear resistance. is there. Furthermore, it is suitable for an application such as a drill, an end mill, or a micro-part, in which adhesion of droplets to a portion to be used is reduced. Hereinafter, the present invention will be described based on examples.

Example 1
An AIP target was produced by powder metallurgy. In production, in order to obtain a hard film having excellent wear resistance and heat resistance characteristics, Si, one or more raw material powders selected from Periodic Tables 4a, 5a, and 6a group metals, B and S, and Si3N4 Was mixed in an Ar atmosphere for 4 hours using a ball mill as a sealed container. In the case of containing S, it was difficult to handle the powder of S alone, so sulfide was used. In consideration of powder mixing properties, 99.999% or more of Al2O3 balls were used in order to avoid compositional deviation and mechanical strength reduction. A predetermined amount of the mixed powder was charged into a graphite mold and sintered using a hot press machine. In order to avoid the dissolution of Si during sintering, the sintering temperature was set to 1100 to 1200 ° C. In sintering under reduced pressure, sintering was performed in an Ar atmosphere in order to avoid the influence of oxygen incorporation into the target due to a trace amount of oxygen remaining in the sintering apparatus. The press load was set in the range of 50 MPa to 200 MPa. The sintering time was 1 to 3 hours. The target completed after sintering was processed into a shape suitable for a bending strength test piece and an AIP apparatus. A target was produced under the above conditions.

  The presence state of the phase containing Si3N4 and Si3N4 in the target structure was observed at an magnification of 2k using an electrolytic emission scanning electron microscope (S-4200, manufactured by Hitachi, Ltd., hereinafter referred to as FE-SEM). The component analysis of each phase was performed by the EDX analyzer equipped with FE-SEM. Thereafter, the surface of the target was treated with a hydrofluoric acid-based corrosive solution, and the same field of view was observed under the same conditions. In order to confirm Si3N4 and the Si phase, the structure of the produced target was observed with a transmission electron microscope (hereinafter referred to as TEM). In order to examine the strength of the target material, the bending strength test piece was measured by three-point bending.

  The target of the present invention was attached to an AIP apparatus, and the milling insert was coated. The coating treatment temperature was 600 ° C., the reaction pressure was 5 Pa, the bias voltage was 50 V, and the arc current value was 150 A. The substrate surface was coated with a film thickness of 3 μm. The amount of droplets adhering to the hard film was measured using FE-SEM at a magnification of 3k. The total amount contained in a 1 mm square was measured using a droplet having a particle size of 0.5 μm or more as a measurement target. Table 1 shows the target composition, the bending strength, and the droplet amount of the film.

As shown in Table 1, the target material of the present invention example containing Si3N4 showed superior bending strength compared to the target material of the conventional example. As a result of observing the structure on the surface of the target material of the example of the present invention by FE-SEM, a nitride-containing phase in which Si3N4 was dispersed in the Si single phase was present. In the structures of Invention Examples 2 to 4 containing Si3N4 in a TiSi target, observation with a TEM was performed 200,000 times, and a phase in which Si ₃ N ₄ was dispersed inside a single Si phase particle was formed. Was confirmed. The same phenomenon was confirmed for Examples 7 to 9 , 12 to 14 , 17 to 19 , and 22 to 24 of TiSiV, TiSiNbS, and ZrSiW targets containing Si ₃ N ₄ . Therefore, it is considered that high bending strength was obtained. Next, about the obtained film | membrane, the amount of droplets whose particle size contained in 1 mm square is 0.5 micrometer or more was measured. As shown in Table 1, the amount of droplets in the example of the present invention was remarkably reduced as compared with the conventional example. In particular, the number of droplets tended to decrease as the Si ₃ N ₄ content in the target increased. This is presumably because the inclusion of Si ₃ N ₄ in the target reduced the number of Si single phases that are likely to be droplet generation sources, thereby avoiding the concentration of arc spots. In Invention Examples 2 to 4 in which Si ₃ N ₄ was contained in the TiSi-based target, the smallest amount was 9,000 pieces / mm ² . Conventional Example 26 was 26000 pieces / mm ² , and the amount of droplets was reduced by 60% or more. This tendency, Invention Examples 7 ~ 9, 12 ~ 14, 17 ~ 19, 22 ~ 24 TiSiV system, TiSiNbS system were similar for ZrSiW system targets.

The present invention examples 2 to _{4, 7} to 9, 12 to 14, 17 to 19, 22 to 24 containing Si ₃ N ₄ have a content of Si ₃ N ₄ in the range of 5% to 30%. Some showed high flexural strength. The invention example 14 which was excellent in the bending strength with respect to the conventional examples 26-30 and showed the highest bending strength of 660 MPa in the examples of the present invention was 1.5 times better than the conventional example 28. Inventive Examples 9, 19, and 24 were also superior to Conventional Examples 27, 29, and 30 by 1.4 times, 1.5 times, and 1.5 times, respectively. This is probably because Si ₃ N ₄ contained in the target is dispersed in the Si single phase, so that the bonding strength of the elements constituting the target is remarkably increased.

(Example 2)
The insert for milling coated with the target material produced in Example 1 was cut under the following test conditions to evaluate the wear resistance of the hard coating. In the evaluation method, the presence or absence of peeling or breakage of the hard coating that occurred when the cutting length was 1 m was observed by magnifying the cutting blade flank portion 50 times using an optical microscope, and the wear width was measured. Further, the cutting was continued, and the performance was evaluated by comparing the cutting distance (m) up to that time when the chip life including the chipping of 300 μm or more was defined as the tool life.
(Test conditions)
Tool: Special face milling insert shape: SDE53 type special shape Cutting method: Center cut work material shape: width 125mm x length 300mm
Work material: Steel for press dies SKD11, 29HRC
Axial depth of cut: 1.0 mm
Cutting speed: 130 m / min Feed per tooth: 0.5 mm / blade cutting oil: None

As shown in Table 1, the target Si3N4 content affected the tool life on the coating surface. According to the comparison of the tool life of Invention Examples 2 to 4 and Conventional Example 26, although the elements constituting the hard coating are the same, the tool life is changed by the difference in the form of the target material used for coating the hard coating. did. In particular, when the content of Si ₃ N ₄ is in the range of 5% to 30%, the tool life is excellent. Among Invention Examples 2 to 4 in which Si ₃ N ₄ is contained in a TiSi-based target, Invention Example 4 having excellent tool life is 2.3 times superior to Conventional Example 26. As a result of confirming the damage state of the blade edge at the cutting distance of 1 m, the flank maximum wear widths of the inventive examples 2 to 4 were 0.113 m, 0.103 mm, 0.092 mm, 0.085 mm and 0.101 mm, respectively. On the other hand, the conventional example 26 was 0.160 mm. The film produced from the target of Conventional Example 26 was observed to be peeled off, but any sample having the Si3N4 content of Invention Examples 2 to 4 in the range of 5% or more and 30% or less was peeled from any sample. It was not recognized and was wearing normally. Eventually, the chip was damaged when the maximum flank wear width exceeded 0.500 mm. These tendencies were the same for coatings obtained from TiSiV-based, TiSiNbS-based, and ZrSiW-based target materials of Invention Examples 7-9 , 12-14, 17-19, 22-24. The above results show that the mechanical strength such as hardness, density and toughness of the hard coating is increased by reducing the number of droplets, and as a result, excellent tool life is shown. Among the examples of the present invention, a target having an M / N value of 0.3 ≦ M / N ≦ 3.0 has particularly excellent bending strength, a small amount of coating droplets, and good cutting performance. It was.

Claims (2)

Si and M components, wherein the M component is a target material for arc ion plating having one or more elements selected from Periodic Tables 4a, 5a, 6a group metals, B, S, A nitride-containing target material comprising Si, an M component, and Si nitride , wherein the Si nitride content is 5% or more and 30% or less in mol% .   2. The nitride-containing target material according to claim 1, wherein the M / N value is 0.3 ≦ M / N ≦ 3. Where M is the Si nitride content and N is the Si content. A nitride-containing target material, characterized in that it is zero.