Sputtering target and method for manufacturing the same

Abstract

This disclosure provides a sputtering target and a method for manufacturing the same, characterized in that the sputtering target contains 55 to 80% by weight of Ni, the remainder being W and common impurities, the sputtering target includes a W phase and a Ni(W) solid solution phase, does not include a pure Ni phase, and the average area ratio of the intermetallic compound phase measured in the cross-section of the target material is 5% or less.

Description

Technical Field

[0001] The present invention relates to a sputtering target and a method for manufacturing the sputtering target.

Background Art

[0002] The W-Ni alloy is an alloy having high melting point, high hardness, and high corrosion resistance, and is widely applied to machinery, electronics, medical equipment, automobile parts, aerospace industry, daily hardware parts, industrial processing dies, and the like.

[0003] An electrochromic layer made of a W-Ni mixed oxide has been known for many years. In NiOx (W-Ni mixed oxide) alloyed with W, an atomic ratio of W / Ni of about 0.33 is particularly advantageous. At this ratio, the charge transfer resistance becomes optimal, and a very fast optical switching behavior of the electrochromic layer is ensured. The electrochromic layer thus produced is produced, for example, using a sputtering target made of a W-Ni alloy, and this W-Ni alloy is ablated by reactive magnetron sputtering under oxygen to form a W-Ni mixed oxide layer. This oxide target is also known from the prior art.

[0004] Furthermore, the W-Ni alloy can also be used as a barrier layer in Cu / Sn bonding applications, and overcomes the physical limit of 5 μm of Cu / Sn by means of a submicron Cu / Sn bond with a transient Ni diffusion buffer layer at 225°C. A 10-nm Ni layer suppresses significant interdiffusion of Cu / Cn in the pre-process of the main bonding process. When the temperature is close to the melting point of Sn, the Ni layer dissolves, and the molten Sn realizes a submicron-sized Cu / Sn bond. The excellent mechanical strength and electrical performance of this scheme indicate great potential for high-density 3D interconnects. From the same principle, the W-Ni alloy can also be used as a bonding layer between a TFT and an LED cell.

[0005] For sputtering targets made of W-Ni alloy, conventional applications have employed powder hot spraying, which can result in high levels of chemical impurities and low density. High levels of chemical impurities cause variations in coating speed, negatively impacting the homogeneity of the deposited layer. Similarly, low density of the sputtering target material negatively affects the coating speed. Furthermore, the spraying method limits the material utilization rate and service life of the target, as only material of a limited thickness can be produced.

[0006] When sputtering targets made of W-Ni alloy, currently in use, are manufactured by thermal spraying, using Ni powder and W powder as starting materials for manufacturing the target may result in the presence of ferromagnetic pure nickel in the target material. These ferromagnetic regions lead to variations in coating speed, which unfavorably affects the uniformity of the deposited layer and is therefore unfavorable for magnetron sputtering.

[0007] In addition, the thermal spraying process yields only materials with limited density. Low density of the sputtering target material similarly negatively affects the coating speed. Furthermore, thermal spraying limits the thickness of the material that can be produced, which restricts the material utilization rate and lifespan of the target.

[0008] A further disadvantage is that metal impurities present in the spray powder as a result of the manufacturing process migrate directly into the target material being manufactured. Impurities in the sputtered layer can adversely affect the optical layer properties.

[0009] Furthermore, non-metallic inclusions or phases, particularly oxides or dielectrics, that may be mixed into the target material during thermal spraying lead to an increase in the number of particles during sputtering. This can negatively affect the properties of the sputtered layer (adhesion, specific electrical resistance, and layer uniformity) and the coating process (high arc velocity). [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] International Publication No. 2015 / 089533 [Overview of the project] [Problems that the invention aims to solve]

[0011] To overcome the drawbacks of thermal spraying as described above, Patent Document 1 (WO2015 / 089533A1) describes a sputtering target with a low nickel (Ni) content and a high tungsten (W) content. In the defined sintering process, the oxygen content can be controlled to within 100 μg / g, and the density can reach 90% by weight or more. However, this process has the following drawbacks: the W phase as a second phase may cause a non-uniform distribution on the sputtered surface; the W phase is of high purity; and the sputtering target contains a high-purity Ni phase, which reduces the uniformity of the material and affects the sputtering effect.

[0012] This disclosure aims to overcome, at least partially, the shortcomings of the prior art by providing improved sputtering targets and processes for manufacturing sputtering targets. [Means for solving the problem]

[0013] A first aspect of this disclosure relates to a sputtering target containing 55% to 80% by weight of Ni, with the remainder being W and common impurities. This sputtering target comprises a W phase and a Ni(W) solid solution phase, but does not contain a pure Ni phase, and contains or does not contain intermetallic compound phases in an average area of ​​5% or less as measured in the cross-section of the target material.

[0014] Alternatively, the sputtering target may contain 60% to 70% by weight of Ni. Alternatively, the sputtering target may contain 60% to 65% by weight of Ni. Alternatively, the sputtering target has an oxygen content of less than 50 μg / g. Alternatively, the sputtering target has an oxygen content of less than 40 μg / g. Alternatively, the sputtering target has a hardness of less than 500 HV10. Alternatively, the intermetallic compound phase is one or more selected from the group consisting of Ni4W, WNi, or W2Ni. Alternatively, the sputtering target has an average W-phase particle size of less than 40 μm. Alternatively, the sputtering target has a relative density exceeding 90%. Alternatively, the sputtering target has a relative density exceeding 99.5%.

[0015] A second aspect of this disclosure relates to a process for manufacturing a sputtering target, such as that described in the first aspect of this disclosure, using a powder metallurgy route, the following steps: Performing a compression process to obtain a compacted blank by applying pressure, heat, or both to a mixed powder of W powder and Ni powder; and This includes performing a cooling process in which the compacted blank is cooled to a temperature range of 750°C to 1000°C at a cooling rate of 3K / min or more.

[0016] When the compression process is carried out at a sintering temperature of 1100°C to 1450°C, the sintering atmosphere is a combination of a first gas and / or vacuum. Preferably, the sintering atmosphere is changed from vacuum to the first gas, i.e., sintering is carried out sequentially using vacuum and the first gas.

[0017] Alternatively, the method further includes performing thermomechanical treatment or heat treatment of the blank between the compression step and the cooling step. However, when such thermomechanical treatment or heat treatment is performed after the sintering step, the cooling rate in the cooling step is changed to exceed 30 K / min in at least the temperature range of 900 to 750 °C.

[0018] Alternatively, the method further includes performing thermomechanical treatment or heat treatment at a temperature in the range of 970 °C to 1450 °C.

[0019] Alternatively, the thermomechanical treatment or heat treatment includes at least one forging step or rolling step.

Brief Description of the Drawings

[0020] [Figure 1] FIG. 1 shows a Ni-W phase diagram marked with the composition range by the sputtering target of the first aspect of the present disclosure. [Figure 2] FIG. 2 shows a microscope view of the sputtering target manufactured in Examples 1 to 3 relating to the method for manufacturing the sputtering target of the second aspect of the present disclosure. [Figure 3A] FIG. 3A shows a microscope view of the sputtering target manufactured in Example 4 relating to the method for manufacturing the sputtering target of the second aspect of the present disclosure. [Figure 3B] FIG. 3B shows a microscope view of the sputtering target manufactured in Example 4 relating to the method for manufacturing the sputtering target of the second aspect of the present disclosure.

Modes for Carrying Out the Invention

[0021] Hereinafter, first, the sputtering target according to the first aspect of the present invention will be described in detail.

[0022] As shown in Figure 1 (see ASM Handbook Vol. III, Alloy Phase Diagrams 1992), the sputtering target contains a W phase and a Ni(W) solid solution phase, but does not contain a Ni phase, and the Ni(W) solid solution phase has a W alloy Ni mixed crystal, preferably a W-saturated Ni mixed crystal.

[0023] The sputtering target according to this disclosure preferably contains an average of less than 5 area percent of the intermetallic phase measured in the cross-section of the target material. The sputtering target according to this disclosure preferably has an average area content of less than 5 area percent of the pure W phase.

[0024] To determine the proportion of intermetallic compound phases present in the sputtering target according to this disclosure, the area-average proportion in the cross-section is analyzed. For this purpose, a metallographic polished cross-section is prepared and examined by an optical microscope or electron microscope. The metallographic polished cross-section is a two-dimensional cross-section of the three-dimensional target material. Area analysis can be performed on the micrograph thus prepared using commercially available image analysis software. This is performed by image analysis, and typically, the proportion of individual phases in the microstructure described above is determined by the contrast of phases to be identified. Phases that are difficult to identify can be further contrasted by means of an appropriate etching process. In this case, by etching with a suitable etching solution (e.g., 85 ml of ammonia solution, 5 ml of 30% hydrogen peroxide solution), the intermetallic compound phase can be distinguished from the Ni mixed crystal (Ni(W) phase, W-saturated Ni mixed crystal), and the area ratio can be determined. However, alternative etching solutions and processes can be considered depending on the state of the microstructure. The average area fraction is calculated as the arithmetic mean of five measurements of area fractions measured in five 100 × 100 μm image regions of a polished metallographic cross section recorded at 1000x magnification. When the intermetallic phase is less than 5%, it results in a uniform elemental distribution on the sputtered surface. The maximum deviation of the Ni content of the manufactured sputtering target is much lower than that of those manufactured by the process of Patent Document 1, and the uniformity of Ni at different locations on the sputtering target is very high. Alternatively, the appearance of the intermetallic phase in the sputtering target can be very easily confirmed or eliminated by means of X-ray diffraction (XRD) using the relevant JCPDS card (considering the respective X-ray detection limits).

[0025] The intermetallic phase can be selected from, for example, Ni4W, WNi, or W2Ni.

[0026] As can be seen from the phase diagram in Figure 1, the brittle Ni4W phase preferentially forms when the Ni content in the sputtering target exceeds 55 mass%. At even higher Ni content levels, a ferromagnetic Ni phase may be formed.

[0027] The sputtering targets of this disclosure contain 55% to 80% by weight of Ni, the remainder being W and common impurities. The term "common impurities" refers to contamination associated with the manufacturing process by gases or associated elements derived from the raw materials used. The proportion of such impurities in the sputtering targets of this disclosure is preferably in the range of less than 100 μg / g (equivalent to ppm) for gases (C, H, N, O) and less than 500 μg / g for other elements. It is known that the appropriate method of chemical elemental analysis depends on the chemical element being analyzed. The sputtering targets of this disclosure have a high Ni content and a low W content. In the Ni-W layer manufactured by the sputtering target described in the claims, Ni can be used as a buffer layer to dissolve molten Sn, thereby effectively achieving a submicron Cu / Sn junction, which can provide excellent mechanical strength and electrical properties. The Ni-W layer manufactured from this target can be used for TFT electrode bonding and semiconductor 3D integration. This effectively solves the technical problems of reduced material uniformity and impact on the sputtering effect in existing sputtering targets, and has high purity, high density, and good application performance. The sputtering target of this disclosure more preferably contains 60% to 70% by weight of Ni, and even more preferably contains 60% to 65% by weight of Ni, and this content leads to further improvements in material uniformity and application properties.

[0028] The sputtering target of this disclosure preferably has an oxygen content of less than 50 μg / g, and particularly preferably less than 40 μg / g.

[0029] Oxygen content can be measured in a simple manner using ICP-OES.

[0030] The sputtering target of this disclosure preferably has a Vickers hardness of less than 500 HV10.

[0031] It has been found that the target material can be optimally guaranteed to have sufficient toughness if its hardness is less than 500 HV10. This simplifies handling during the manufacturing process, for example, in any mechanical molding process. In particular, in one embodiment, when used as a one-piece tubular target, handling is significantly simplified if the hardness is less than 500 HV10.

[0032] The hardness of HV10 (Vickers hardness) is, for the purposes of this invention, an arithmetic mean determined from five hardness measurements.

[0033] The sputtering targets of this disclosure preferably have a relative density of over 90%, more preferably over 92%, and most preferably over 99.5%. The higher the density of the target, the more advantageous its properties are. Targets with low relative density have a relatively high proportion of pores, which can become a substantial source of leakage and / or impurities and particles during the sputtering process. Furthermore, low-density targets tend to absorb water or other impurities, which can result in process parameters that are difficult to control. In addition, materials with relatively high relative density have a lower ablation rate during the sputtering process than slightly higher-density materials.

[0034] It is well known that relative density can be easily measured using the buoyancy method and Archimedes' principle.

[0035] In order to install the sputtering target according to this disclosure in various coating plants and to coat substrates having various shapes, various shape requirements are imposed on the sputtering target according to this disclosure. Therefore, this type of target can take the form of a flat plate target such as a plate or disc, a rod-shaped target, a tubular target, or an object shape having other complex shapes.

[0036] The sputtering target according to this disclosure preferably has an average particle size of W phase of less than 40 μm, more preferably less than 20 μm.

[0037] When the average particle size of the W phase is less than 40 μm, more preferably less than 20 μm, a particularly uniform sputtering behavior is brought about, whereby a particularly uniform layer having a particularly uniform thickness can be deposited. Further, thereby the notch effect of the W phase is suppressed low, and as a result, good toughness of the target material is optimally ensured.

[0038] Aggregates of a plurality of particles of the W phase may exceed a size of 40 μm in diameter, but such aggregates are not regarded as individual particles of the W phase in the sputtering target according to the present disclosure.

[0039] The average particle size of the W phase can be easily determined by the line section method on the metal polished cross section.

[0040] As described above, the sputtering target according to the first aspect of the present disclosure effectively solves the technical problem of reducing the material homogeneity and affecting the sputtering effect, and has high density and good application performance.

[0041] Such a sputtering target of the present disclosure is used in the following fields: - Bonding solutions in display applications such as LED chips on TFT backplanes; - As a thin layer in stacks of electrochromic devices or solar control coatings; - As a cover layer for protecting underlying metal lines, such as layers based on copper or aluminum, from exposure to and oxidation by the surrounding environment; - As a buffer layer for controlling diffusion of elements between different layers by applying a specific thickness (for example, 5 nm < t < 50 nm); - As a Ni source for packaging and soldering applications; - Depositing oxides or nitrides in a reactive sputtering process; - As a barrier layer to prevent cross-diffusion of elements in thin-film stacks (for example, interdiffusion of elements into copper metal wires during the metallization of semiconductor materials or thin-film transistors, which degrades electrical performance), It can be applied to this.

[0042] The following describes a method for manufacturing a sputtering target according to a second aspect of the present invention.

[0043] A manufacturing method for producing a sputtering target according to a first aspect of this disclosure, using a powder metallurgy route according to a second aspect of this disclosure, comprises at least the following steps: A compression process is carried out to obtain a compressed blank by compressing a powder mixture of W powder and Ni powder by pressure, heat, or pressurization and heating; and A cooling process is performed in which the compressed blank is cooled to a temperature range of 750°C to 1000°C at a cooling rate exceeding 3K / min. It is characterized by including.

[0044] As part of the process for manufacturing a W-Ni sputtering target according to the present invention, a compression step is performed to compress a suitable powder mixture by applying pressure, heat, or both pressure and heat to form a blank. This compression step can be performed by means of various processing steps, such as pressing and sintering, cold isostatic pressing, hot isostatic pressing, hot pressing, or spark plasma sintering (SPS), or by a combination of these methods or a further method for compressing the powder mixture.

[0045] The production of a powder mixture that can be used in the method of this disclosure is preferably carried out by weighing appropriate amounts of W powder and Ni powder into a suitable mixing apparatus and mixing until a uniform distribution of the components in the powder mixture is ensured. For the purposes of this disclosure, the expression "powder mixture" includes pre-alloyed or partially alloyed powders containing the components W and Ni.

[0046] The powder mixture thus produced is preferably introduced into a mold to carry out a compression process. Here, suitable molds are dies or flexible tubes in a cold isostatic press, dies in a hot press or spark plasma sintering plant, and also cans in a hot isostatic press.

[0047] As part of the process according to this disclosure for manufacturing a W-Ni sputtering target, a cooling step is performed in which the blank is cooled to a temperature range of 750°C to 1000°C at a cooling rate of more than 3 K / min to avoid the formation of undesirable intermetallic phases. In a preferred embodiment, the blank is held in this temperature range for 15 minutes to 3 hours, more preferably 45 minutes to 2 hours, and even more preferably 45 minutes to 90 minutes. If the proportion of intermetallic phase in a W-Ni sputtering target manufactured by the means of processing according to the present invention is excessively large, firstly, it can cause a different sputtering rate than the rest of the target, thereby resulting in non-uniform ablation on the target material and, consequently, variations in the thickness of the deposited layer. Furthermore, the presence of brittle intermetallic phases in the microstructure of the target material can lead to increased arc formation or particle formation. Secondly, the low toughness of the intermetallic compound phase makes such sputtering targets more difficult to handle.

[0048] As outlined earlier, when thermomechanical or heat treatment is performed after the compression process (e.g., sintering process), the cooling rate to a temperature in the range of 900-750°C is changed to exceed 30 K / min. It is also preferable to cool the resulting blank to a temperature range of 750-900°C at a cooling rate exceeding 50 K / min during such a cooling process. This is because the aforementioned material properties and the microstructure of the target can be set in a particularly optimized manner. This type of cooling process can be achieved, for example, by cooling in air, water, or oil. Such a cooling step optimally avoids the formation of intermetallic phases and ensures that the sputtering target produced by this process has the best possible combination of microstructure and mechanical properties.

[0049] Preferably, the compression step is carried out by sintering at a temperature of 1100°C to 1450°C, and the sintering atmosphere is combined with a first gas and / or vacuum. In preferred embodiments, both the first gas and vacuum are used in the sintering process. In the method according to this disclosure for manufacturing a W-Ni sputtering target, it has been found to be particularly advantageous to carry out the compression step by sintering at a temperature of 1100°C to 1450°C, where the sintering is a sintering process called unpressurized sintering at a pressure of less than 2 MPa, preferably less than atmospheric pressure.

[0050] Compression at these temperatures ensures optimal solid-phase sintering to a very high relative density within the existing powder mixture. Compression below 1100°C may result in densities that are too low, while temperatures above 1450°C may lead to a decrease in the mechanical stability of the target material. Compression within the above temperature range ensures an optimal combination of high density achieved and optimal mechanical properties. Due to the high Ni content in the manufactured sputtering target, conventional processes make it difficult to control the oxygen (O) content to a low value and achieve density under closed-hole conditions. By performing sintering at temperatures between 1100°C and 1450°C and combining a first gas and / or vacuum in the sintering atmosphere, the oxygen content can be substantially reduced. The first gas is preferably a mixture of gases mainly composed of hydrogen, and the mixture of gases may include, but is not limited to, argon, for example, and may include other suitable gases.

[0051] In the method according to this disclosure for manufacturing a W-Ni sputtering target, preferably, the obtained ingot is subjected to thermomechanical or heat treatment between the compression and cooling steps. Such thermomechanical or heat treatment can result in advantageous properties such as a further increase in the density of the microstructure and / or further homogenization.

[0052] Furthermore, it is preferable that the trace amounts of intermetallic compound phases be uniformly distributed within the microstructure of the target material, and the adverse effects of these phases can be minimized by such thermomechanical or heat treatments. This fine dispersion ensures uniform ablation without the formation of irregularities during sputtering.

[0053] In the manufacturing method of a W / Ni sputtering target, it has been found that the thermomechanical treatment or thermal treatment is particularly advantageous when performed at a temperature in the range of 970°C to 1450°C.

[0054] The thermomechanical or heat treatment within the indicated temperature range is carried out in the two-phase region W(Ni)+Ni(W) and preferably does not generate any, or substantially any, further undesirable brittle intermetallic phases. In optimal cases, any intermetallic phases that may exist after compression can be largely dissolved by such thermomechanical or heat treatment.

[0055] The substantial avoidance of such undesirable brittle intermetallic compound phases allows W-Ni sputtering targets produced by the processing methods of the present invention to be particularly well shaped by molding. This, in turn, simplifies the production of large sputtering targets, especially long, preferably integral tubular targets, and has a favorable effect on the proximity to the final shape that can be achieved.

[0056] Preferably, the thermomechanical treatment or heat treatment includes at least one forging or rolling step.

[0057] Thermomechanical treatments or heat treatments for the purposes of this disclosure can be carried out as a single-step or multi-step process. Multiple suitable processes can also be combined. Therefore, a thermomechanical treatment or heat treatment may include one or more substeps that do not, or are not inherently, involve deformation of the target material.

[0058] It has been found to be particularly advantageous that the thermomechanical treatment or heat treatment in the method according to this disclosure includes at least one rolling or forging step to produce a W-Ni sputtering target.

[0059] Thermomechanical or heat treatment, including at least one rolling or forging step, can introduce a predetermined degree of deformation into a target material in a particularly targeted manner. This can, for example, avoid excessive strengthening and, consequently, exceeding the applicable deformation force.

[0060] A thermomechanical or heat treatment method, including at least one rolling or forging step, can introduce a desired microstructure into the target material. This can positively influence both the mechanical and sputtering properties of the target material.

[0061] Furthermore, one or more rolling or forging processes make it possible to vary the thickness of the formed material over its length and set this thickness as desired.

[0062] Furthermore, rolling or forging can achieve uniform surface quality, high straightness, and good roundness, which are favorable for further mechanical processing or further thermomechanical or heat treatment of the target material.

[0063] Preferably, the processing means for manufacturing a sputtering target according to the present disclosure can be used to manufacture a sputtering target containing 55-80% by mass of W, the remainder being Ni and ordinary impurities. In this case, the W-Ni sputtering target obtained by the method of the present disclosure contains a W phase and a Ni(W) solid solution phase, but does not contain a Ni phase, and does not contain an intermetallic compound phase, or contains an intermetallic compound phase of less than 5 area percent on average as measured in the cross-section of the target material. Here, the area percentage is the average area percentage calculated as the arithmetic mean of five measurements of the area percentage measured in five image portions of a 100 × 100 μm metallographic polished cross-section, recorded at a magnification of 1000x.

[0064] The method for manufacturing a W-Ni sputtering target according to this disclosure makes it possible to guarantee a relative density of over 90%, preferably over 92%, and most preferably over 99.5% in the W-Ni sputtering target manufactured by this method. Furthermore, the purity and mechanical properties of the target material obtained by the method for manufacturing a W-Ni sputtering target according to this disclosure are also optimized.

[0065] Therefore, the processing according to this disclosure results in a very low amount of impurities in the sputtering target produced thereby. For example, the oxygen content is preferably less than 50 μg / g, and particularly preferably less than 40 μg / g. Substantially avoiding the formation of brittle intermetallic phases also leads to optimizing the hardness of the W-Ni sputtering target produced by the processing means according to the present invention.

[0066] The manufacturing method according to this disclosure preferably achieves a hardness of less than 500HV10.

[0067] The manufacturing method according to this disclosure can achieve an average particle size of the W phase that is preferably less than 40 μm, and more preferably less than 20 μm.

[0068] The present invention will be described below based on embodiments. [Examples]

[0069] Example 1: As raw materials, W metal powder with a particle size of 4 μm measured by the Fischer method and Ni metal powder with a particle size of 4.2 μm measured by the Fischer method were used. 40% by weight of tungsten powder and 60% by weight of nickel powder were mixed using a mixer at a rotation speed of 12 rpm for 1 hour.

[0070] The powder mixture was introduced into the rubber, and the open end of the rubber was closed with a rubber cap. The sealed rubber was placed in a cold isostatic press and pressed at a pressure of 200 MPa for a holding time of 1 minute to obtain a green block with a relative density of 67%, a thickness of 23 mm, a width of 158 mm, and a length of 748 mm.

[0071] Next, the green block was sintered in a vacuum by heating it to 1350°C at a rate of 3°C / min and holding it at 1350°C for 1 hour. Then, the sintering atmosphere was changed to the first gas and held for 3 hours, then cooled to 980°C at a rate of 8°C / min, the sintering atmosphere was changed back to an H2 gas atmosphere and held for 1 hour, and then cooled to room temperature at 10°C / min. After sintering, the sintered block was 20 mm thick, 144 mm wide, and 665 mm long, with a relative density of 90.6% and an oxygen content of 23.6 μg / g.

[0072] After sintering, the sintered block is machined to dimensions of 15 mm thickness, 128 mm width, and 620 mm length. The uniformity of the sputtering target after sintering in Example 1 is very high, and the maximum deviation of Ni content at different length positions of the sputtering target is only 0.1% to 0.3%.

[0073] X-ray fluorescence spectroscopy (XRF) is performed to measure the percentage of Ni content at different lengths of the sintered sputtering target (1 / 4 length, 1 / 2 length, and 3 / 4 length, respectively), and the maximum deviation is calculated. A sputtering target with 40 wt% W and 60 wt% Ni, manufactured by the process described in Patent Document 1 (Comparative Example 5), is also inspected at the same location for comparison. Verification is performed based on the test results.

[0074] [Table 1]

[0075] As can be seen from the figure, the maximum deviation of the Ni content in the sputtering target manufactured in Example 1 was much lower than that of the control group, with a maximum deviation of only 0.28%, resulting in very high Ni uniformity at different locations. Furthermore, when XRD measurements were performed separately on both Example 1 and Comparative Example 5, no pure Ni phase was observed in the sputtering target manufactured in Example 1, while a pure Ni phase was observed locally in the sputtering target manufactured in the control group.

[0076] The left column of Figure 2 shows optical microscope and scanning electron microscope (SEM) images of the microstructure of Example 1. In the optical microscope image, the Ni(W) solid solution phase appears as light gray. The pure W phase appears as patterned dark gray. Pores (resulting from the powder metallurgy manufacturing method) and / or other artifacts (resulting from the preparation) appear black. In the SEM image, the light gray represents the Ni(W) solid solution phase, the pores and / or artifacts appear black, and the pure W phase appears white.

[0077] Comparative Example 5 (an example prepared by the process described in Patent Document 1; see also Table 1 and Example 4 of Patent Document 1): The raw materials used were W metal powder with a particle size of 4 μm, measured by the Fischer method, and Ni metal powder sieved to a particle size of less than 160 μm. 43 wt% tungsten powder was mixed with 57 wt% nickel powder in a mixer. A green block with a diameter of 25 mm and a thickness of 13.5 mm was obtained by cold isostatic pressing at a pressure of 200 MPa. The green block was then sintered by heating to 1350°C over 2 hours, holding at that temperature for 4 hours, and then cooling over 2 hours. The relative density of the sintered block was 73.7%, and the oxygen content was 268 μg / g. Intermetallic compound phases were detected by XRD measurement.

[0078] Example 2: As raw materials, W metal powder with a particle size of 4 μm measured by the Fischer method and Ni metal powder with a particle size of 4.2 μm measured by the Fischer method were used. 35 wt% tungsten powder and 65 wt% nickel powder were mixed using a mixer at a rotation speed of 12 rpm for 1 hour.

[0079] The powder mixture was introduced into the rubber, and the rubber was closed at its open end with a rubber cap. The sealed rubber was placed in a cold isostatic press and compressed at a pressure of 200 MPa for 1 minute to obtain a green block with a relative density of 66%, a thickness of 25 mm, a width of 160 mm, and a length of 750 mm.

[0080] Next, the green block was sintered in a vacuum by heating it to 1350°C at a heating rate of 3°C / min and holding it at 1350°C for 1 hour. Then, the sintering atmosphere was changed to the first gas and held for 3 hours, then cooled to 980°C at a rate of 8°C / min, the sintering atmosphere was changed back to an H2 gas atmosphere and held for 1 hour, and then cooled to room temperature at 10°C / min. After sintering, the sintered block had a thickness of 22 mm, a width of 142 mm, and a length of 667 mm, a relative density of 90.8%, and an oxygen content of 29.8 μg / g. The uniformity of the sputtering target after sintering in Example 2 was very high, and the maximum deviation of Ni content at different length positions of the sputtering target was only 0.1% to 0.3%.

[0081] X-ray fluorescence spectroscopy (XRF) is performed to measure the percentage of Ni content at different lengths of the sintered sputtering target (1 / 4 length, 1 / 2 length, and 3 / 4 length, respectively), and the maximum deviation is calculated. A sputtering target with 35 wt% W and 65 wt% Ni (Comparative Example 6), manufactured by the process described in Patent Document 1, is also inspected at the same location for comparison. Verification is performed based on the test results.

[0082] [Table 2]

[0083] As can be seen from the figure, the maximum deviation of the Ni content in the sputtering target manufactured in Example 2 was much lower than that of the control group, with a maximum deviation of only 0.15%, resulting in very high Ni uniformity at different locations. Furthermore, when XRD measurements were performed separately on both Example 2 and Comparative Example 6, no pure Ni phase was observed in the sputtering target manufactured in Example 2, while a localized pure Ni phase was observed in the sputtering target manufactured in the control group. In Example 2, the intermetallic phase or pure W could not be detected by XRD measurement.

[0084] The central column of Figure 2 shows the microstructure of Example 2 in optical microscope and scanning electron microscope (SEM) images. In the optical microscope image, the Ni(W) solid solution phase appears as light gray. Pores (resulting from the powder metallurgy manufacturing method) and / or other artifacts (resulting from the preparation) appear black. Pure W phase is not shown in this image. In the SEM image, the light gray indicates that the Ni(W) solid solution phase, pores, and / or artifacts appear black. Although the image shows a white pure W phase, the W phase was not detected by XRD in this example, i.e., the W phase was below the detection limit.

[0085] Comparative Example 6 (Example prepared by the process described in Patent Document 1): W metal powder with a particle size of 4 μm, measured by the Fischer method, and Ni metal powder with a particle size of less than 160 μm, which was sieved, were used as raw materials. 35% by weight of tungsten powder was mixed with 65% by weight of nickel powder in a mixer. Cold isostatic pressing was performed at a pressure of 200 MPa to obtain a green block with a diameter of 25 mm and a thickness of 14.1 mm. The green block was then sintered by heating to 1350°C for 2 hours, holding at that temperature for 4 hours, and then cooling for 2 hours. The relative density of the sintered block was 85.2%, and the oxygen content was 82 μg / g.

[0086] Example 3: As raw materials, W metal powder with a particle size of 4 μm measured by the Fischer method and Ni metal powder with a particle size of 4.2 μm measured by the Fischer method were used. 30% by weight of tungsten powder and 70% by weight of nickel powder were mixed in a mixer at a rotation speed of 12 rpm for 1 hour.

[0087] This mixed powder was introduced into rubber, and the open end of the rubber was closed using a rubber stopper. The closed rubber was placed in a cold isohydrostatic press and pressed at a pressure of 200 MPa for a holding time of 1 minute to obtain a green block with a relative density of 67% and dimensions of φ15 × 50.

[0088] Next, the green block was sintered in a vacuum at a heating rate of 3°C / min to 1350°C, and held at 1350°C for 1 hour. Then, the sintering atmosphere was changed back to the initial gas atmosphere and held for 3 hours, then cooled at a rate of 8°C / min to 980°C, the sintering atmosphere was changed back to an H2 gas atmosphere and held for 1 hour, and then held at a cooling rate of 10°C / min to room temperature. The unsintered block after sintering had a size of approximately 13 × 44 in length, a relative density of 92%, and an oxygen content of 32 μg / g. The uniformity of the sputtering target after sintering in Example 3 was very high, and the maximum deviation of Ni content at different length positions of the sputtering target was only 0.1% to 0.3%.

[0089] X-ray fluorescence spectroscopy (XRF) is performed to measure the percentage of Ni content at different lengths of the sintered sputtering target (1 / 4 length, 1 / 2 length, and 3 / 4 length, respectively), and the maximum deviation is calculated. Ni produced by the process described in Patent Document 1 for 30 wt% W and 70 wt% sputtering targets (Comparative Example 7) is also examined at the same location for comparison. Validation is based on the test results.

[0090] [Table 3]

[0091] As can be seen from the figure, the maximum deviation of the Ni content in the sputtering target manufactured in Example 3 was much lower than that of the control group, with a very low maximum deviation of only 0.15%, resulting in very high uniformity of Ni at different locations. Furthermore, when XRD measurements were performed separately on both Example 3 and Comparative Example 7, no pure Ni phase was observed in the sputtering target manufactured in Example 3, while a localized pure Ni phase was observed in the sputtering target manufactured in the control group. In Example 3, the intermetallic phase or pure W could not be detected by XRD measurement.

[0092] The right-hand column of Figure 2 shows the microstructure of Example 3 in optical microscope and scanning electron microscope (SEM) images. In the optical microscope image, the Ni(W) solid solution phase appears as light gray. Pores (resulting from the powder metallurgy manufacturing method) and / or other artifacts (resulting from the preparation) appear black. In this image, the pure W phase is not detectable. In the SEM image, the light gray indicates that the Ni(W) solid solution phase, pores, and / or artifacts appear black. This image shows small white pure W phase particles, but the W phase is not detectable by XRD in this example, i.e., the W phase is below the detection limit.

[0093] Comparative Example 7 (Example prepared by the process described in Patent Document 1): As raw materials, W metal powder with a particle size of 4 μm, measured by the Fischer method, and Ni metal powder with a particle size of less than 160 μm, which was sieved, were used. Nickel powder in a mixer mixed with 30% by weight of tungsten powder at a ratio of 70% by weight. To obtain a green body block with a diameter of 25 mm and a thickness of 14.6 mm, cold isostatic pressing was performed at a pressure of 200 MPa. The green body block was then heated to 1350°C for 2 hours, held at that temperature for 4 hours, and then sintered by cooling for 2 hours. The relative density of the sintered block was 85.7%, and the oxygen content was 120 μg / g.

[0094] Example 4 As raw materials, W metal powder with a particle size of 4 μm measured by the Fischer method and Ni metal powder with a particle size of 4.2 μm measured by the Fischer method were used. 35 wt% tungsten powder was mixed with 65 wt% nickel powder in a mixer at a rotation speed of 12 rpm for 1 hour.

[0095] The powder mixture was introduced into the rubber, and the rubber was closed at its open end by means of a rubber cap. The closed rubber was placed in a cold isostatic press and pressed at a pressure of 200 MPa for a holding time of 1 minute to obtain a green block with a thickness of 22 mm. The green block was then sintered in a vacuum at a heating rate of 3°C / min to 1350°C, held at 1350°C for 1 hour, then the sintering atmosphere was changed back to the initial gas atmosphere and held for 3 hours, then it was cooled at a rate of 8°C / min to 980°C, the sintering atmosphere was changed back to an H2 gas atmosphere and held for 1 hour, and then it was cooled to room temperature at a cooling rate of 10°C / min. The sintered block after sintering was 22 mm thick, 142 mm wide, and 667 mm long. After sintering, two-pass rolling was performed to obtain a thickness of 15 mm. Next, the rolled block was annealed at 1300°C for 30 minutes and then further two-pass rolling was performed to obtain a thickness of 10 mm. Next, the material was processed in a planarization apparatus and finally annealed at 1200°C for 30 minutes. After annealing, a cooling rate of at least 34 K / min was achieved in the temperature range of 900-750°C. The relative density of the green block after this treatment was 99.8%, and the oxygen content was 15.9 μg / g.

[0096] The method for manufacturing a sputtering target according to a second aspect of this disclosure effectively solves the technical problem of reduced material homogeneity affecting the sputtering effect, and therefore the sputtering target has high density and good application performance.

[0097] Figure 3A shows the microstructure of Example 4 in an optical microscope image, where the particle orientation and material density are evident.

[0098] Figure 3B shows the microstructure of Example 4 in optical microscope and scanning electron microscope (SEM) images. In the optical microscope image, the Ni(W) solid solution phase appears as a light gray. Due to the high density of this material, pores are hardly visible in this image. No pure W phase is detected in this image. The SEM image shows that the crystal grains are oriented in the longitudinal direction. One pure W- crystal grain is still visible in this image, but it is below the detection level of XRD.

[0099] Furthermore, in this Example 4 as well, the pure Ni phase, the pure W phase, and the intermetallic compound phase cannot be detected.

[0100] Due to its ferromagnetic properties, pure nickel can interfere with the normal operation of magnetron sputtering; therefore, the technical solution described in Patent Document 1 employs a lower W-Ni ratio with less nickel content. At the same time, it is generally recognized in the art that when it is necessary to increase the uniformity of the elemental distribution of the material, it is necessary to reduce the content of the desired alloying elements. In other words, to increase the uniformity of the nickel distribution, it is necessary to further reduce the nickel content.

[0101] However, in this study, the inventors found that further reducing the Ni content according to existing knowledge leads to a problem in which the Ni content of the W-Ni phase acting as the second phase is low in certain regions, resulting in an uneven distribution of Ni elements in different parts of the target material.

[0102] This disclosure employs a technical solution opposite to that of Patent Document 1 by using a higher Ni content, which presents the following problems: 1) High Ni content leads to the generation of magnetism due to the formation of a pure Ni phase in the material, which is unfavorable for magnetron sputtering. 2) Because the element Ni has a stronger affinity for oxygen, it can lead to an increase in the oxygen content in the material. In other words, it is difficult to obtain a material that does not contain a pure Ni phase in a W-Ni target with a high Ni content, and how to control the formation of the pure Ni phase becomes a technical challenge to overcome. The inventors of this disclosure can effectively solve the technical problem of reducing the uniformity of the material and affecting the sputtering effect, and as a result the sputtering effect has high density and good application performance. The improved techniques demonstrated in the first and second embodiments described above precisely overcome the above technical challenges.

[0103] The sputtering target and method for manufacturing the sputtering target according to this disclosure effectively solve the technical problem of reducing the homogeneity of the material and affecting the sputtering effect, and have high density and good application performance.

[0104] While this disclosure has been illustrated and described by reference to certain preferred embodiments thereof, it should be understood by those skilled in the art that various modifications may be made to them in form and detail without departing from the spirit and scope of this disclosure.

Claims

1. A sputtering target containing 55% to 80% by weight of Ni, with the remainder being W and ordinary impurities, It contains a W phase and a Ni(W) solid solution phase, but does not contain a pure Ni phase, and does not contain an intermetallic compound phase, or contains an average of 5 area percent or less of the intermetallic compound phase as measured in the cross-section of the target material. Sputtering target.

2. The sputtering target is characterized by containing 60% to 70% by weight of Ni. The sputtering target according to claim 1.

3. The sputtering target is characterized by containing 60% to 65% by weight of Ni. The sputtering target according to claim 2.

4. The sputtering target is characterized by having an oxygen content of less than 50 μg / g. A sputtering target according to any one of claims 1 to 3.

5. The sputtering target is characterized by having an oxygen content of less than 40 μg / g. The sputtering target according to claim 4.

6. The sputtering target is characterized in that its hardness is less than 500 HV10. A sputtering target according to any one of claims 1 to 5.

7. The aforementioned intermetallic phase is Ni 4 W, WNi, or W 2 It is characterized by being one or more selected from the group consisting of Ni. A sputtering target according to any one of claims 1 to 6.

8. The sputtering target is characterized in that the average particle size of the W phase is less than 40 μm. A sputtering target according to any one of claims 1 to 7.

9. The sputtering target is characterized by having a relative density exceeding 90%. A sputtering target according to any one of claims 1 to 8.

10. The sputtering target is characterized by having a relative density exceeding 99.5%. The sputtering target according to claim 9.

11. A method for manufacturing a sputtering target according to any one of claims 1 to 10 by powder metallurgy, comprising the following steps: A compression step is performed in which a powder mixture of W powder and Ni powder is compressed by applying pressure, heat, or both pressure and heat to obtain a compressed blank, and The compressed blank is subjected to a cooling process in which it is cooled to a temperature range of 750°C to 1000°C at a cooling rate exceeding 3 K / min. A method characterized by including

12. The compression step is carried out by sintering at a temperature of 1100°C to 1450°C, and the sintering atmosphere is characterized by being combined with a first gas and / or vacuum. The method for manufacturing a sputtering target according to claim 11.

13. A method for manufacturing a sputtering target according to any one of claims 1 to 10 by powder metallurgy, comprising the following steps: A compression process is performed to obtain a compressed blank by applying pressure, heat, or both pressure and heat to a powder mixture of W powder and Ni powder. After the compression step, the compressed blank is subjected to thermomechanical treatment or thermal treatment, and A cooling process is carried out to cool the compressed blank to a temperature range of at least 900°C to 750°C at a cooling rate exceeding 30 K / min. A method characterized by including

14. The compression process is carried out by sintering at a temperature of 1100°C to 1450°C. The sintering atmosphere is combined with a first gas and / or vacuum. A method for manufacturing a sputtering target according to claim 13, characterized in that

15. Furthermore, the thermomechanical treatment or the heat treatment is characterized by being performed at a temperature in the range of 970°C to 1450°C. A method for manufacturing a sputtering target according to claim 13 or 14.

16. The thermomechanical treatment or heat treatment is characterized by including at least one forging or rolling step. A method for manufacturing a sputtering target according to claim 14.

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