Tungsten-based ceramic target material and preparation method and application thereof

Abstract

The invention discloses a tungsten-based ceramic target material and a preparation method and application thereof. Relates to the technical field of powder metallurgy. The tungsten-based ceramic target material comprises the following components: a tungsten-oxygen mixture, a first doping agent and a second doping agent, the tungsten-oxygen mixture is selected from a Magneli phase tungsten-oxygen mixture, and / or the tungsten-oxygen mixture is selected from elemental tungsten and tungsten oxide; the first dopant comprises at least one of oxides of Zr, Co, Cu and Zn; the second dopant includes at least one of oxides of Mo, Ta, Nb, V, Y, and Ti. According to the invention, high conductivity, high light transmittance and corrosion resistance are realized through cooperation of the tungsten-oxygen mixture conductive substrate and the double dopants.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of powder metallurgy, in particular to a tungsten-based ceramic target material and a preparation method and application thereof. BACKGROUND

[0002] Low-reflection tungsten-based ceramic target material as a new type of material has important application prospects in modern electronics and optics. Tungsten and its oxide materials have been widely used in many fields due to their excellent electrical, optical and mechanical properties. Especially in optoelectronics and electronic devices, tungsten-based materials have become an important direction for research and development due to their high heat resistance, good electrical conductivity and electrochromic properties. With the progress of science and technology, tungsten-based ceramic target materials are increasingly widely used in semiconductor thin film preparation, displays, solar cells, integrated circuits and other fields, and the development of low-reflection tungsten-based ceramic target materials brings more optimized performance to these applications.

[0003] Tungsten-based materials have been used in the application of optoelectronics and electronic devices by preparing thin films through sputtering technology. In particular, tungsten trioxide (WO3) as an excellent optoelectronic material has been widely used in smart materials, devices and surface decoration. Tungsten trioxide has good reversible electrochromic properties and can adjust the transmittance, absorptance and reflectance under a specific voltage, which makes tungsten trioxide thin film material suitable for various optical and electronic devices such as light modulation, display devices, solar cells, etc. Especially in the application of organic electroluminescent devices (OLED), tungsten trioxide as a hole injection layer can effectively reduce the electron transport loss and improve the OLED luminous efficiency, and has the characteristics of low power consumption, wide color gamut and high response rate under low DC current, which has become an indispensable part of the device structure.

[0004] However, in the preparation process of tungsten trioxide thin film, tungsten and tungsten alloy targets are usually used for magnetron sputtering in an argon-oxygen mixed atmosphere. Although this method can effectively prepare tungsten trioxide thin film, the oxidation reaction occurs on the surface of the metal target at the same time, which easily leads to excessive oxidation of the target surface and forms a target poisoning phenomenon, affecting the quality and stability of the thin film. In addition, it is difficult to control the oxygen concentration, and hysteresis phenomenon is easy to occur, making it difficult to stably obtain the required tungsten trioxide film. In order to avoid these problems, tungsten oxide target material becomes a more ideal choice. By using tungsten oxide target for sputtering coating, target poisoning phenomenon can be effectively avoided, and the deposition efficiency of the film layer can be improved, and the stability and reliability of the whole preparation process can be improved.

[0005] In the prior art, there is a scheme of high-temperature activation of tungsten oxide powder and doped powder in an inert or vacuum atmosphere, followed by reduction hot-pressing sintering, which successfully obtains doped tungsten oxide target material with high density (> 90%) and high conductivity (< 8.3 mΩ·cm). Although this method can obtain relatively excellent target material performance, the high-temperature treatment of the activation process makes the stability of the tungsten oxide particles poor, and the reduction hot-pressing sintering has high requirements for equipment, which limits its application in large-scale industrial production.

[0006] In addition, in the preparation process of the low-reflection tungsten-based ceramic target material, in addition to considering the high density and excellent conductivity of the target material, the reflectivity, absorptivity and other optical properties of the target material need to be optimized through specific process means. Pure tungsten oxide (WO3) has a relatively high resistivity, but its resistivity is extremely high at room temperature, and its conductivity is poor. The stability of the amorphous tungsten oxide thin film obtained after magnetron sputtering is poor, and it is easily affected by changes in environmental temperature and humidity, thereby affecting the stability of the film performance and the stable operation of the entire device.

[0007] Therefore, finding a more efficient, stable and easy-to-industrialize production process for preparing a low-reflection tungsten-based ceramic target material has become the focus of research. SUMMARY

[0008] The purpose of the present application is to provide a tungsten-based ceramic target material with good conductivity, high light transmittance and good stability.

[0009] The first aspect of the present application is to provide a tungsten-based ceramic target material. The present application provides a tungsten-based ceramic target material.

[0010] The second aspect of the present application is to provide a preparation method of a tungsten-based ceramic target material. The present application provides a tungsten-based ceramic target material.

[0011] The third aspect of the present application is to provide an application of the tungsten-based ceramic target material. The third aspect of the present application is to provide an application of the tungsten-based ceramic target material.

[0012] Specifically, the technical scheme adopted according to the first aspect of the present application is as follows: A tungsten-based ceramic target material, the components of the tungsten-based ceramic target material include tungsten-oxygen mixture, first dopant and second dopant; The tungsten-oxygen mixture is selected from Magneli phase tungsten-oxygen mixture, and / or the tungsten-oxygen mixture is selected from tungsten single substance and tungsten oxide; The first dopant includes at least one of oxides of Zr, Co, Cu and Zn; The second dopant includes at least one of oxides of Mo, Ta, Nb, V, Y and Ti.

[0013] According to embodiments of the present invention, one of the technical solutions has at least one of the following advantages or beneficial effects: This invention achieves high conductivity, high light transmittance, and corrosion resistance through the synergistic effect of a tungsten-oxygen mixture conductive matrix and dual dopants.

[0014] Specifically: This invention uses a tungsten-oxygen mixture to replace the pure tungsten metal target. Due to the presence of oxygen vacancies in the sintered body structure of the tungsten-oxygen mixture, the thin film formed by the tungsten-based ceramic target after sputtering still has high conductivity. This invention employs a first dopant for doping, which is capable of solid-dissolving in a tungsten-oxygen mixture conductive matrix (WO). x The crystal lattice improves the corrosion resistance of the tungsten-based ceramic target and its transmittance in the visible light wavelength range; This invention employs a second dopant to dope the tungsten-based ceramic target material, thereby introducing specific cations and controlling the valence state of W in the system to maintain a certain reduced state, thus increasing the W content in the tungsten-based ceramic target material. 5+ :(W 5+ +W 6+ ) proportion, W 5+ It can capture charges to become active centers that suppress carrier recombination, thereby enabling carriers to have higher migration efficiency and enhancing the optical and electrical properties of the tungsten-based ceramic target.

[0015] According to one embodiment of the present invention, the W:O atomic ratio of the tungsten-oxygen mixture is 0.33-0.40. The present invention limits the W:O ratio of the tungsten-oxygen mixture to 0.33-0.40. By adjusting the W:O atomic ratio, the Magneille phase structure is modified, allowing oxygen vacancies to form donor levels, providing free electrons and improving conductivity. Furthermore, by controlling the W:O atomic ratio of the tungsten-oxygen mixture, the number of low-valence ions is controlled. A suitable number of low-valence ions, due to their lower lattice energy, diffuse more easily, thereby improving the sinterability of the tungsten-based ceramic target.

[0016] According to one embodiment of the present invention, the particle size D50 of the tungsten-oxygen mixture is 300-1000 nm.

[0017] According to one embodiment of the present invention, the particle size D50 of the tungsten-oxygen mixture is 300-350 nm.

[0018] According to one embodiment of the present invention, the Magnelie phase tungsten-oxygen mixture comprises W 18 O 49 W 18 O 49It is a stable Magneille phase that is not prone to physicochemical changes during storage, transportation, mixing, and molding, which is beneficial for the stable control of material properties during preparation. 18 O 49 It has excellent electrical conductivity and better sinterability compared to traditional tungsten targets, which is beneficial for the preparation of sintered bodies.

[0019] According to one embodiment of the present invention, the W 18 O 49 The particle size is 1-1.5 μm.

[0020] According to one embodiment of the present invention, the tungsten-oxygen mixture accounts for >60% by mass in the tungsten-based ceramic target.

[0021] According to one embodiment of the present invention, the tungsten-oxygen mixture is W 18 O 49 A mixture of WO3 and elemental tungsten, where W:W 18 O 49 The mass ratio of WO3 is 1:4-10:5-10. This invention optimizes the Magneille phase ratio to ensure the sintering activity and conductivity of the tungsten-based ceramic target.

[0022] According to one embodiment of the present invention, the first dopant is selected from at least one of ZnO, ZrO2, and Cu2O. According to one embodiment of the present invention, the particle size D50 of the first dopant is 2-10 μm.

[0023] According to one embodiment of the present invention, the mass ratio of the first dopant in the tungsten-based ceramic target is 5-25 wt%.

[0024] According to one embodiment of the present invention, the particle size D50 of the ZnO is 2-2.5 μm.

[0025] According to one embodiment of the present invention, the particle size D50 of the ZrO2 is 10-10.5 μm.

[0026] According to one embodiment of the present invention, the second dopant is selected from at least one of Y₂O₃, TiO₂, and MoO₂. Different types and concentrations of doped oxides will change the tungsten oxide W 5+ →W 6+ The reduction reaction process improves its optical and electrical properties.

[0027] According to one embodiment of the present invention, the particle size D50 of the second dopant is 2-2.5 μm.

[0028] According to one embodiment of the present invention, the second dopant is present in the tungsten-based ceramic target at a mass ratio of 1-10 wt%. Increasing the amount of the second dopant also increases the number of defects inside the tungsten oxide in the tungsten-oxygen mixture, replacing external charges in the exchange, reducing the amount of charge required for exchange, and improving electrical performance.

[0029] According to one embodiment of the present invention, the relative density of the tungsten-based ceramic target is ≥95%. The tungsten-based ceramic target of the present invention has high density, thereby ensuring the uniformity of the sputtered film.

[0030] According to one embodiment of the present invention, the tungsten-based ceramic target material further includes additives.

[0031] According to one embodiment of the present invention, the additive includes at least one of a binder, a dispersant, and a defoamer.

[0032] Specifically, the technical solution adopted according to the second aspect of the present invention is as follows: A method for preparing the tungsten-based ceramic target material includes the following steps: The components of the tungsten-based ceramic target are mixed, granulated, and sintered at normal pressure in a protective atmosphere to obtain the tungsten-based ceramic target.

[0033] According to embodiments of the present invention, one of the technical solutions has at least one of the following advantages or beneficial effects: The tungsten-based ceramic target of the present invention can be prepared by atmospheric pressure sintering, replacing the traditional hot pressing sintering method for preparing metallic tungsten targets or tungsten oxide targets. This method offers advantages such as low preparation cost and the ability to mass-produce. Furthermore, a protective atmosphere is used for sintering to prevent oxidation of the Magneille phase, thereby maintaining the conductivity of the tungsten-based ceramic target.

[0034] According to one embodiment of the present invention, the mixing of the components of the tungsten-based ceramic target material includes dry mixing and wet mixing.

[0035] According to one embodiment of the present invention, the gas in the protective atmosphere includes at least one of Ar and N2.

[0036] According to one embodiment of the present invention, the temperature of the atmospheric pressure sintering is 1000-1500℃. This further ensures that a high-density product is achieved under atmospheric pressure sintering.

[0037] According to one embodiment of the present invention, the granulation is carried out using a spray granulation method. Spray granulation controls powder flowability, reduces compression porosity, thereby increasing the green body density and ensuring that the final sintering density meets the requirements.

[0038] According to one embodiment of the present invention, during the spray granulation process, the atomizer speed is 5000-20000 rpm, the outlet air temperature is 120-170℃, and the granulation particle size is 20-80μm.

[0039] Another aspect of the present invention also provides a WO 3-x A thin film, 0≤x≤1, is prepared by DC magnetron sputtering from the tungsten-based ceramic target. Since this application employs all the technical solutions described above for the tungsten-based ceramic target, it possesses at least all the beneficial effects brought about by the technical solutions of the above embodiments.

[0040] According to one embodiment of the present invention, the WO 3-x The thickness of the thin film is 120-150 nm, where 0 ≤ x ≤ 1.

[0041] According to one embodiment of the present invention, the DC magnetron sputtering has a sputtering power of 1200-1300KW and / or a substrate temperature of 300-320℃.

[0042] In another aspect, the present invention also provides an organic electroluminescent device. This includes the aforementioned WO. 3-x The thin film with 0≤x≤1 serves as the hole injection layer.

[0043] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the discovery. Attached Figure Description

[0044] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a SEM image of the target material in Example 5.

[0045] Figure 2 This is a reflectance test graph of the thin film in Example 5. Detailed Implementation

[0046] The terms "preferred," "more preferred," etc., used in this invention refer to embodiments of the invention that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this invention.

[0047] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0048] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of the present invention.

[0049] Unless otherwise specified, the reagents, methods and equipment used in this invention are all conventional reagents, methods and equipment in this technical field.

[0050] The raw materials used in the following examples and comparative examples are as follows: The tungsten elemental powder was prepared by two-stage reduction of tungsten oxide with hydrogen. It is a cubic crystalline nano-tungsten powder with strong surface activity, a purity of 99.99%, and a particle size D50 of 300 nm.

[0051] The WO3 powder has a purity of 99.99% and a particle size D50 of 300 nm.

[0052] W 18 O 49 The powder has a purity of 99.99% and a particle size of 1μm.

[0053] The ZnO powder has a purity of 99.9% and a particle size D50 of 2μm.

[0054] The ZrO2 powder has a purity of 99.9% and a particle size D50 of 10 μm.

[0055] The Y2O3 powder has a purity of 99.9% and a particle size D50 of 2μm.

[0056] The targets in the following examples and comparative examples were prepared using the following methods. Each component was weighed according to the weight ratios in Table 1. The specific steps are as follows: S1. A mixture of tungsten oxide, a first dopant, and a second dopant is dry-premixed using an LJB horizontal plow mixer for 4-24 hours to obtain a premixed powder. The premixed powder is then wet-mixed in a shear mixer at a water-to-powder mass ratio of 2:1. Conventional additives of this technical field, accounting for less than 5% of the total powder mass, are added sequentially: a binder (containing polyvinyl alcohol and polyethylene glycol), a dispersant (containing polyacrylic acid and polyacrylamide), and a defoamer (polyoxyethylene-polyoxypropylene block copolymer). The shearing and emulsification time is 8-12 hours to obtain a mixed slurry. The mixed slurry is then transported through pipelines to a spray granulation tower for regranulation. The particle size of the granulated powder is adjusted by controlling the atomizer speed and the inlet and outlet air temperature. The atomizer speed is set at 5000-20000 rpm, and the outlet air temperature is set at 120-170℃. The required particle size of the granulated powder is 20-80 μm. S2, the granulated powder is pressed longitudinally in a single axis by a powder tablet press, and then densified by a cold isostatic press to ensure the strength and density of the formed green body (the relative density of the green body after pressing is greater than 60%), and a sample block with a diameter of 3 inches is prepared. S3, the above sample is placed in a protective atmosphere and sintered at normal pressure to obtain the above target material.

[0057] The following examples and comparative examples all prepared WO3 using the following methods. 3-x For a thin film with 0 ≤ x ≤ 1, the specific steps are as follows: The target material was surface-machined and dimensionally cut to obtain a 3-inch target material, which was then used to fabricate WO4 on the surface of UTG glass (Wog Optoelectronics) by DC sputtering. 3-x Thin films with 0 ≤ x ≤ 1 were sputtered at a power of 300 W under a pure argon atmosphere at a pressure of 0.5 Pa. The substrate temperature was maintained at room temperature using a DC sputtering equipment to obtain WO3 films with a thickness of 40-200 nm. 3-x ,0≤x≤1 film.

[0058]

[0059] In Table 1, NP represents atmospheric pressure sintering conditions, HP represents high pressure sintering conditions, HT represents sintering at 1100℃, and Air represents sintering in air.

[0060] Performance testing: The films prepared in Examples 1-5 and Comparative Examples 1-10 were subjected to the following tests, and the test results are shown in Table 2.

[0061] The surface resistance of the thin film was measured using a four-probe sheet resistance tester (4D TECHNOLOGY 280SI), and the light reflectance (Rlum) of the coated glass in the wavelength range of 380-780nm was determined using a spectrophotometer (Hitachi UH5700).

[0062] The corrosion test of UTG glass WO3 under artificial atmosphere was performed according to GB / T 10125-2021. 3-x For films with a thickness of 0 ≤ x ≤ 1, corrosion tests were conducted on one side. A neutral salt spray test (NSS test) was performed using a NaCl solution with a pH of 6.5-7.2. The adhesion grades (0B-5B) of the films before and after corrosion were compared according to ASTM D3359 Adhesion Test Method B to evaluate corrosion resistance.

[0063] The density of the sintered target material was measured using the Archimedes displacement method at room temperature (25℃), and the relative density was calculated.

[0064] m is the mass (g) of the sample at room temperature, m1 is the mass (g) of the sample in water, and p0 is the theoretical density of the sintered body.

[0065] Table 2

[0066] As shown in Table 2, the incorrect first and second dopant were selected in Comparative Examples 1-6, resulting in low density of the prepared target material, making it difficult to perform DC magnetron sputtering coating. This indicates that the dopant combinations in some combinations cannot meet the conditions for preparing target materials by atmospheric pressure sintering.

[0067] The sintered body of Comparative Example 7 was sintered in an air atmosphere, and the film prepared from the target material obtained did not have conductive properties, indicating that WO 3-x The conductivity of 0≤x≤1 should be determined by the oxygen vacancy mechanism in the tungsten-oxygen sintered body. Therefore, in this invention, the tungsten-oxygen sintered body needs to be sintered in a protective atmosphere such as N2 or Ar to ensure that there is enough Magneille phase for conductivity in the target material and subsequent coating process.

[0068] The difference in relative density of the sintered body caused by the different amounts of tungsten powder added in Comparative Example 7 and Comparative Example 8 indicates that excessive tungsten powder mixing may reduce the sintering activity of the shaped blank.

[0069] In Examples 1-4, the addition of different proportions of TiO2 all showed good shrinkage effects and could meet the requirements of magnetron sputtering targets, but the visible light transmittance was slightly poor.

[0070] In Example 5, by adding appropriate proportions of ZnO and Y2O3, the sintered body prepared under normal pressure has a uniform and dense grain structure, and the film obtained by sputtering has excellent comprehensive optoelectronic properties, meeting the requirements of the low-reflection functional layer of OLED devices and achieving optimal performance.

[0071] The target material of Example 5 was subjected to SEM testing, and the test results are as follows:Figure 1 As shown. Figure 1 By observing the distribution of pores, it can be intuitively determined that the target material of the present invention is a target material with fine and uniform grains and high density.

[0072] The reflectance of the thin film in Example 5 was tested, and the test results are as follows: Figure 2 , Figure 2 In this context, wavelength refers to the wavelength and reflectionance refers to the reflection ratio. Figure 2 In the figure, the vertical axis "reflectivity" is basically maintained at around 10-20%, indicating that the film has a weak ability to reflect visible light in the 360-710nm range. Most of the incident light is not directly reflected by the surface. Therefore, the film of the present invention has high transmittance.

[0073] The above are merely embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent modifications made based on the content of the present invention specification, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A tungsten-based ceramic target material, characterized in that: The components of the tungsten-based ceramic target include a tungsten-oxygen mixture, a first dopant, and a second dopant. The tungsten-oxygen mixture is selected from Magneille phase tungsten-oxygen mixtures, and / or the tungsten-oxygen mixture is selected from elemental tungsten and tungsten oxide; The first dopant includes at least one of oxides of Zr, Co, Cu, and Zn; The second dopant includes at least one oxide of Mo, Ta, Nb, V, Y, and Ti.

2. The tungsten-based ceramic target material according to claim 1, characterized in that: The W:O atomic ratio of the tungsten-oxygen mixture is 0.33-0.

40.

3. The tungsten-based ceramic target material according to claim 1, characterized in that: The Magneille phase tungsten oxide mixture includes W 18 O 49 .

4. The tungsten-based ceramic target material according to claim 1, characterized in that: The tungsten-oxygen mixture accounts for >60% of the mass of the tungsten-based ceramic target.

5. The tungsten-based ceramic target material according to claim 1, characterized in that: The tungsten-oxygen mixture is W 18 O 49 A mixture of WO3 and elemental tungsten, where W:W 18 O 49 The mass ratio of WO3 is 1:4-10:5-10.

6. The tungsten-based ceramic target material according to claim 1, characterized in that: The first dopant is selected from at least one of ZnO, ZrO2, and Cu2O.

7. The tungsten-based ceramic target material according to claim 1, characterized in that: The second dopant is selected from at least one of Y2O3, TiO2, and MoO2.

8. A method for preparing a tungsten-based ceramic target material as described in any one of claims 1 to 7, characterized in that: Includes the following steps: The components of the tungsten-based ceramic target are mixed, granulated, and sintered at normal pressure in a protective atmosphere to obtain the tungsten-based ceramic target.

9. The method according to claim 8, characterized in that: The temperature for atmospheric pressure sintering is 1000-1500℃.

10. A type of WO 3-x The thin film, 0≤x≤1, is prepared by DC magnetron sputtering from a tungsten-based ceramic target as described in any one of claims 1 to 7.

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