V2o3 sintered compact, method for producing same, and v2o3 sputtering target

Abstract

The present disclosure addresses the problem of providing: a high-density V2O3 sintered compact; a method for producing a high-density V2O3 sintered compact; and a high-density V2O3 sputtering target. The V2O3 sintered compact has a relative density of 95% or more. The method for producing a V2O3 sintered compact comprises subjecting a V2O3 powder to hot press sintering at 1350-1450°C under vacuum or in an inert atmosphere gas.

Description

V2O3 sintered body, its manufacturing method, and V2O3 sputtering target

[0001] This disclosure relates to V ２ O ３ Sintered body and its manufacturing method, and V ２ O ３ Regarding sputtering targets.

[0002] Vanadium oxide undergoes a dynamic phase change in its crystal structure, and is therefore expected to be applied to MEMS (Micro Electro Mechanical Systems) devices such as microactuators. Regarding vanadium oxide, Patent Document 1 discloses that a metal-insulator transition occurs at 69°C, which is higher than room temperature, and that the latent heat storage function associated with this phase transition is applied to sputtering target materials.

[0003] In Patent Document 1, V ２ O ５ Powder and V ２ O ３ The mixed powder is mixed with VO powder to prepare a mixed powder, and reactive sintering is carried out in a non-oxidizing atmosphere. ２ Furthermore, Patent Document 2 discloses a semilac material containing vanadium oxide as the main component, which exhibits little variation in heat absorption when vanadium oxide is used in a cooling device. Specifically, vanadium dioxide (VO) containing 50 to 400 mass ppm of nitrogen is used. ２ ) has been disclosed.

[0004] Patent No. 7106138 International Publication No. 2016 / 009760

[0005] The present disclosure provides a high density V ２ O ３ Sintered body, its manufacturing method, and V ２ O ３ The object is to provide a sputtering target.

[0006] In order to solve the above problems, the present inventors have conducted extensive research and have found that by devising manufacturing methods and conditions, it is possible to fabricate high-density V ２ O ３It has been found that a sintered body and a sputtering target can be obtained. That is, the gist of the present disclosure is as follows. [1] V having a relative density of 95% or more ２ O ３ [2] The V according to [1], having a volume resistivity of 10 mΩ cm or less. ２ O ３ Sintered body. [3] V ２ O ３ The maximum XRD peak intensity in the range of 32.50°≦2θ≦33.50°, which is attributed to the (010) plane, is designated as I ＴＧ The average value of the XRD intensity in the range of 20.00°≦2θ≦20.50° is taken as the background I ＢＧ１ , the average value of the XRD intensity in the range of 27.50°≦2θ≦28.0° is used as the background I ＢＧ２ , then I ＴＧ / I ＢＧ１ ≧3.0 and I ＴＧ / I ＢＧ２ ≧3.0, ２ O ３ [4] The V according to any one of [1] to [3], wherein the proportion of defects is 5% or less. ２ O ３ [5] The V according to any one of [1] to [4], wherein the average grain size is 5 μm or less. ２ O ３ [6] The V according to any one of [1] to [5]. ２ O ３ A sputtering target made from a sintered body and having a circular plate shape, a rectangular plate shape, or a cylindrical shape. [7] V ２ O ３ The powder is hot-pressed and sintered at 1350 to 1450°C in a vacuum or inert gas atmosphere. ２ O ３ A method for manufacturing a sintered body.

[0007] According to the present disclosure, high density V ２ O ３ Sintered body and its manufacturing method, and V ２ O ３ A sputtering target can be provided.

[0008] 1 is an image analysis diagram (for reference) used when analyzing defects in a sintered body.

[0009] Below, the present disclosure will be described with reference to specific embodiments, but each configuration and combination thereof in each embodiment is merely an example, and addition, omission, substitution, and other modifications of configurations are possible as appropriate within the scope that does not deviate from the gist of the present disclosure.

[0010] V according to an embodiment of the present disclosure ２ O ３ The sintered body is characterized by having a relative density of 95% or more. When a low-density sintered body is used as a sputtering target, particles and arcing may occur during sputtering, which may deteriorate the device characteristics. Therefore, V ２ O ３ The relative density of the sintered body is set to 95% or more, preferably 98% or more.

[0011] V according to this embodiment ２ O ３ The sintered body preferably has a volume resistivity of 10 mΩ cm or less. When the volume resistivity is low, when the sintered body is used as a sputtering target, DC sputtering, which enables high-speed film formation, can be stably performed. The volume resistivity is more preferably 5 Ω cm or less, and particularly preferably 3 mΩ cm or less.

[0012] V according to this embodiment ２ O ３ The sintered body is V ２ O ３ It is preferable that the vanadium oxide is a single phase. ２ O ３ In addition to the phase, VO ２ Phase, V ２ O ５ Although there are phases, stable sputtering can be performed if there is a single phase. ２ O ３ The single phase is determined by X-ray diffraction analysis (XRD). ２ O ３ The maximum XRD peak intensity in the range of 32.95°≦2θ≦33.30°, which is attributed to the (010) plane, is designated as I ＴＧThe average value of the XRD intensity in the range of 20.12°≦2θ≦20.42° is taken as the background I ＢＧ１ , the average value of the XRD intensity in the range of 27.7°≦2θ≦28.0° is used as the background I ＢＧ２ , then I ＴＧ / I ＢＧ１ ≧3.0 and I ＴＧ / I ＢＧ２ ≧3.0, V ２ O ３ It is judged to be single phase.

[0013] V according to this embodiment ２ O ３ The sintered body preferably has a defect ratio of 5% or less on its surface (the surface corresponding to the sputtering surface). In the present disclosure, defects are mainly composed of micropores (tiny voids) or cracks (grain boundary cracks). The sputtering surface is the surface of a sputtering target that faces a substrate for depositing sputter particles. If many defects are present on the surface, arcing is more likely to occur from these defects when used as a sputtering target. The defect ratio is more preferably 4% or less.

[0014] V according to this embodiment ２ O ３ The sintered body preferably has an average grain size of 5 μm or less. If the grain size becomes too large, cracks are likely to occur in the sintered body, and arcing is likely to occur from these cracks during sputtering. The average grain size is more preferably 3 μm or less, and even more preferably 1 μm or less.

[0015] V according to this embodiment ２ O ３ The sputtering target is produced by machining the sintered body, and has the same physical properties as the sintered body described above. That is, the relative density is 95% or more, and preferably the volume resistivity is 10 mΩ cm or less. Also, preferably, I ＴＧ / I ＢＧ１ ≧3.0 and I ＴＧ / I ＢＧ２≧3.0. Preferably, the defect ratio is 5% or less. Preferably, the average grain size is 5 μm or less.

[0016] V according to an embodiment of the present disclosure ２ O ３ A method for manufacturing a sintered body will be described. However, the manufacturing conditions and the like below are not limited to the disclosed range, and it is clear that some omissions and modifications may be made. In addition, detailed descriptions of well-known manufacturing steps and processing operations will be omitted to avoid unnecessarily obscuring the disclosed manufacturing method.

[0017] (Raw material powder) Vanadium oxide powder is prepared as the raw material powder. ２ O ５ , V.O. ２ , V ２ O ３ , etc., but V ２ O ５ is a poisonous substance and is difficult to handle. ２ is sintered in air ２ O ５ It easily changes phase to V, and reacts with the sintered material (carbon). ３ O ５ Phase to V ２ O ３ Since the phase changes to V ２ O ３ Therefore, in the present disclosure, vanadium oxide powder is preferably V ２ O ３ Powder is used.

[0018] (Crushing step: optional) Vanadium oxide (V ２ O ３ ) powder is pulverized. Pulverization is an optional step. There are various pulverization methods depending on the desired particle size and the material to be pulverized, but wet or dry ball mills, vibration mills, bead mills, etc. can be used. The median diameter (D ５０ It is preferable to adjust the particle size so that the particle size is 50 μm or less. In the case of wet grinding, oxidation occurs during drying, so dry grinding is more preferable.

[0019] (Sintering process: hot press) V２ O ３ When the powder is sintered in the air, V, a toxic substance, ２ O ５ And V ２ O ３ In addition to not being able to obtain a single-phase sintered body, handling becomes difficult. ２ O ３ The powder is sintered at around 1400°C, and the Al of the sintered material (such as the breathable setter) ２ O ３ When the heating rate during sintering is 5°C / min, even if the temperature is less than 1400°C, Al ２ O ３ Therefore, the present disclosure performs hot press sintering in a vacuum or inert gas atmosphere.

[0020] Vanadium oxide (V ２ O ３ ) powder in a vacuum or inert gas atmosphere (Ar, N ２ It is preferable to perform hot press sintering at a sintering temperature of 1350°C or higher and 1450°C or lower under the following conditions: If the sintering temperature is too low, the density of the sintered body will not increase. In particular, if the sintering temperature is lower than 1350°C, the Al contained in the agent applied to the sintered body will ２ O ３ There is a concern that the sintering temperature may react with the melting point, resulting in contamination. Therefore, the sintering temperature is set to 1350°C or higher. On the other hand, the upper limit of the sintering temperature may be set to 200°C or lower than the melting point, and is preferably set to 1450°C or lower. The pressure during hot press sintering can be adjusted as appropriate, but is preferably set to 200 to 500 kgf / cm. ２ The sintering holding time is preferably 1 hour to 20 hours.

[0021] (Finishing Process) The sintered body obtained through the above sintering process is processed into a desired shape using a processing machine such as a surface grinder, a cylindrical grinder, or a machining device. There are no particular restrictions on the shape of the sputtering target, and it can be a circular flat plate, a rectangular flat plate, a cylindrical shape, or the like. In addition, the sputtering target can be used by bonding it to a backing plate.

[0022] The following description will be given based on examples and comparative examples. Note that these examples are merely examples and are not intended to limit the scope of the present invention. That is, the present invention is limited only by the scope of the claims, and includes various modifications other than the examples included in this disclosure.

[0023] The evaluation methods used in the examples and comparative examples are as follows. (Relative density) The relative density of the sintered body was calculated using the following formula: Relative density (%) = Archimedes density / Theoretical density × 100 Archimedes density: The top and bottom surfaces of the sintered body were ground to a thickness of 1 mm, and the outer peripheral surface was ground to a thickness of 5 mm to prepare a measurement sample, and the Archimedes density was calculated using the Archimedes method. Theoretical density: 5.02 g / cm ３

[0024] (Volume Resistivity) The volume resistivity of the sintered body was measured using the following device. For the measurement, the volume resistivity was measured three times at the center of the diagonal of a sintered body processed into a square shape, and the average value was calculated. Device: Resistivity measuring device Σ-5+ manufactured by NPS Co., Ltd. Method: Constant current application method Method: DC four-probe method Measurement temperature: Room temperature (20 to 25°C)

[0025] (Analysis of Crystalline Phase) Analysis of the crystalline phase was performed using the following equipment. Principle: X-ray diffraction method Equipment: Smart Lab manufactured by Rigaku Corporation Tube: Cu-Kα ray tube Voltage: 40 kV Current: 30 mA Measurement method: 2θ-θ reflection method Scan speed: 20° / min Sampling interval: 0.02° Measurement range (2θ): 10° to 60° Divergence slit: 1° Divergence vertical limiting slit: 10 mm Scattering slit: 8 mm Receiving slit: open state Goniometer: sample horizontal type Sample measurement location: cross section perpendicular to the sputtered surface

[0026] (Ratio of Defects) A sample for observation (10 mm x 10 mm, thickness: 3 to 20 mm) was cut out from the center of the sintered body, and a cross section perpendicular to the surface corresponding to the sputtered surface was mirror-polished. A backscattered electron image of the mirror-polished sample surface was taken at 2000x magnification (100 μm x 100 μm) using the following scanning electron microscope (SEM). At this time, the total number of pixels in the image was set to 750,000 or more. Apparatus used: JXA-8500F (manufactured by JEOL Ltd.) Acceleration voltage: 15.0 kV Beam current: 5.0 x 10 －８ A Total number of pixels: 1,209,600 pixels (horizontal: 1,280, vertical: 945)

[0027] The captured images were analyzed using ImageJ (image processing software). A reference diagram for ImageJ analysis is shown in Figure 1 (left: SEM micrograph, right: ImageJ image analysis diagram). As shown in Figure 1, analysis using ImageJ allows the frequency of brightness (horizontal axis) n (range = 0 to 255) of the captured image to be counted as the count number (vertical axis) An.

[0028] The brightness (n) at which the count number An is maximized ｍａｘ ) is 100≦n ｍａｘ ≦105 and the darkest brightness (n １ / １０ ) is 65≦n １ / １０ Three images with An<86 were selected. Since accurate measurement is not possible with images that have overexposed areas, images with An<1000 when the brightness n is between 250 and 255 were selected. The three selected images were binarized using ImageJ. The number of counts (A) of black areas (defects: pores, cracks) was calculated from the binarized images. ｄｅｆｅｃｔ ) and the count of the white part (A ｂｕｌｋ ) was read, and the proportion of defects was calculated using the following formula: (Proportion of defects) = A ｄｅｆｅｃｔ / (A ｄｅｆｅｃｔ +A ｂｕｌｋ )×100[%] The arithmetic mean value of the defect presence ratio calculated from the analysis of the three images was calculated.

[0029] (Average grain size) The average grain size was measured using the code method. In the code method, a line of any length was drawn from grain boundary to grain boundary, the number of intersections with the grain boundary was counted, and the average grain size was determined by dividing the length of the line by the number of intersections. A sample for observation was cut out from the sintered body, and the cross section of the cut sample (a cross section parallel to the sputtered surface) was mirror-polished. On the mirror-polished sample cross section, two fields of view were taken at a magnification of 4000x using a scanning electron microscope, for a total of six fields, at three positions: 2 mm from the top end, the center, and 2 mm from the bottom end. Three lines were drawn on the photographed images (in the direction of the long side of the image), and the arithmetic mean grain size of the lengths at which each line intersected the crystal grains was measured. The arithmetic mean value of the six fields of view was used as the average grain size. However, if the number of grains intersected by each line in the field of view is less than 10, magnifications of 3000x, 2000x, or 1000x can be used as appropriate.

[0030] (Example 1) V ２ O ３ The powder was weighed and crushed, and then the crushed powder was placed in a vacuum at a holding temperature of 1400°C and a surface pressure of 250 kgf / cm. ２ The sintering time was 2 hours, and the resulting V-shaped mold was 58 mm in diameter. ２ O ３ Sintered bodies were produced. The relative density, volume resistivity, and defect content of the obtained sintered bodies were measured. The results are shown in Table 1. As shown in Table 1, in Example 1, sintered bodies with good properties were obtained.

[0031]

[0032] (Comparative Examples 1 and 2) V was produced under the same conditions as in Example 1 except for the sintering temperature. ２ O ３ Sintered bodies were produced. The relative density, volume resistivity, and defect content of the obtained sintered bodies were measured. The results are shown in Table 1. The sintered bodies of Comparative Examples 1 and 2 had low relative densities.

[0033] According to one embodiment of the present invention, particles generated during sputtering can be suppressed, potentially improving product yield. Improving product yield leads to a stable supply of products and reduced loss of metal raw materials, which are limited resources. Therefore, one embodiment of the present invention may contribute to the achievement of Goal 9, "Build resilient infrastructure, promote inclusive and sustainable industrialization and foster innovation," and Goal 12, "Ensure sustainable consumption and production patterns," of the United Nations-led Sustainable Development Goals (SDGs).

[0034] V of this disclosure ２ O ３ The sintered body and sputtering target are expected to be applied to MEMS devices such as microactuators.

Claims

1. Relative density is 95% or more. ２ O ３ Sintered body.

2. The V according to claim 1, having a volume resistivity of 10 mΩ·cm or less. ２ O ３ Sintered body.

3. V ２ O ３ The maximum XRD peak intensity in the range of 32.50°≦2θ≦33.50°, which is attributed to the (010) plane, is designated as I ＴＧ The average value of the XRD intensity in the range of 20.00°≦2θ≦20.50° is taken as the background I ＢＧ１ , the average value of the XRD intensity in the range of 27.50°≦2θ≦28.0° is used as the background I ＢＧ２ , then I ＴＧ / I ＢＧ１ ≧3.0, and I ＴＧ / I ＢＧ２ ≧3.0 ２ O ３ Sintered body.

4. The V according to claim 1, wherein the defect ratio is 5% or less. ２ O ３ Sintered body.

5. The V of claim 1, wherein the average grain size is 5 μm or less. ２ O ３ Sintered body.

6. V according to any one of claims 1 to 5 ２ O ３ A sputtering target made from a sintered body, which has a circular plate shape, a rectangular plate shape, or a cylindrical shape.

7. V ２ O ３ The powder is hot-pressed and sintered at 1350 to 1450°C in a vacuum or inert gas atmosphere. ２ O ３ A method for manufacturing a sintered body.

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