Preparation method for indium-free high-density high-conductivity PVD target and product thereof
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2025-07-09
- Publication Date
- 2026-08-13
Smart Images
Figure CN2025107660_13082026_PF_FP_ABST
Abstract
Description
A method for preparing indium-free high-density, high-conductivity PVD target and its product Technical Field
[0001] This application relates to the field of optoelectronic materials technology, and in particular to a method for preparing an indium-free high-density, high-conductivity PVD target and its product. Background Technology
[0002] Transparent conductive oxide (TCO) is a thin-film material with high transmittance and low resistivity in the visible light spectrum. It can be widely used as a transparent conductive functional layer in optoelectronic devices such as flat panel displays, touch screens, energy-saving glass, and photovoltaic cells. In traditional industrial applications, TCO thin films are generally prepared using magnetron sputtering. Magnetron sputtering is a physical vapor deposition (PVD) deposition method. It uses an electron gun system to emit and focus electrons onto the sputtering source material, causing the sputtered atoms to follow the momentum conversion principle and fly with high kinetic energy to the substrate to deposit into a film. The sputtering source material used is a high-density target (close to the theoretical density of the material). Indium tin oxide (ITO) is currently the most widely used TCO thin film material on the market. It has good optical and electrical properties. However, due to the extremely limited reserves of indium, and the large-scale use of indium in solar cells in recent years, as well as its important application prospects in flat panel displays, LEDs, transparent thin film transistors and flexible electronics, the demand for indium has increased significantly, resulting in a sharp decrease in indium reserves, which can no longer meet market demand. Therefore, it is necessary to find new materials to replace ITO.
[0003] Currently, indium-free targets such as aluminum-doped zinc oxide (AZO) and Al / Ga co-doped zinc oxide (AGZO) have been developed on the market. Although they possess certain photoelectric properties, their resistivity is high, and their conductivity and relative density need further improvement, making it difficult to meet the requirements of market applications. Therefore, this application proposes a method for preparing an indium-free, high-density, high-conductivity PVD target and its product. Summary of the Invention
[0004] The main objective of this application is to provide a method for preparing indium-free, high-density, high-conductivity PVD sputtering targets and the products thereof, aiming to solve the technical problem that the electrical properties and relative density of existing PVD sputtering targets need to be improved.
[0005] To achieve the above objectives, this application proposes a method for preparing an indium-free, high-density, high-conductivity PVD target, comprising the following steps:
[0006] Modified tetraneedle-shaped zinc oxide whiskers were prepared by using zinc as raw material, molecular sieve as nucleating agent, and inert gas through heating reaction.
[0007] The modified tetra-needle zinc oxide whiskers were mixed with the doped material, and a wetting agent and a dispersant were added. The mixture was then ball-milled to obtain a doped slurry.
[0008] The doped and mixed slurry is milled to obtain a milled slurry;
[0009] After drying the sand-milled slurry, it is granulated to obtain granules;
[0010] A molding agent is added to the granules and then pressed to obtain a green body.
[0011] The green body is degummed and then sintered in sections to obtain a PVD target material.
[0012] Optionally, the step of preparing modified tetraneedle-shaped zinc oxide whiskers by using zinc as a raw material, molecular sieve as a nucleating agent, and introducing an inert gas through heating reaction includes:
[0013] Zinc granules were placed on molecular sieve particles and then placed in a box-type resistance furnace. Inert gas was introduced at a flow rate of 10 mL / min to 100 mL / min, and the temperature was raised to 500℃ to 1100℃. After reacting for 10 min to 25 min, modified tetraneedle-shaped zinc oxide whiskers were obtained.
[0014] Optionally, the zinc granules have a purity of 99% and a diameter of 2.5 mm to 3.5 mm; the molecular sieve particles have a diameter of 2.2 mm to 2.8 mm and a loose bulk density of ≥0.66 g / mL; and the modified tetraneedle-shaped zinc oxide whiskers have a needle diameter of 8 μm to 20 μm.
[0015] Optionally, the doping material includes at least one of aluminum oxide, gallium oxide, germanium oxide, selenium oxide, tin oxide, tantalum oxide, nickel, copper, strontium, yttrium, zirconium, niobium, molybdenum, rhodium, palladium, silver, cadmium, antimony, iridium, platinum, gold, lead, graphene, and silicon.
[0016] Optionally, the step of mixing the modified tetraneedle-shaped zinc oxide whiskers with the doped material, adding a wetting agent and a dispersant, and ball milling the mixture to obtain a doped slurry includes:
[0017] The modified tetra-needle zinc oxide whiskers and doped materials were mixed at a mass ratio of (95-99):(1-5), and then a wetting agent and a dispersant were added to obtain a mixture.
[0018] Mechanical ball milling was used, and alumina grinding balls were selected. The mixture, alumina grinding balls, and water were ball milled at a mass ratio of (1-2):(2-3):(2-3) for 15-25 hours to obtain a mixed slurry.
[0019] The wetting agent is a mixture of triethanolamine and tromethamine; the dispersant includes at least one of polyvinylpyrrolidone, hexadecyltrimethylammonium bromide, organophosphonates, and sodium aluminate.
[0020] Optionally, the step of drying the sand-milled slurry and then granulating it to obtain granules includes:
[0021] After drying the sand-milled slurry at 80℃-90℃ for 40h-50h, it is passed through a 200-300 mesh sieve and then rolled into granules for 15min-30min to obtain granules.
[0022] Optionally, the step of adding a molding agent to the granules and pressing them to obtain a green body includes:
[0023] The dry pressing method is used, in which a molding agent is added to the granules and bidirectional pressure is applied under a pressure of 3MPa-5MPa, and the pressure holding time is 2min-4min to obtain a green body;
[0024] The molding agent is a mixture of polyacrylic acid, dioctyl ester and sodium dodecylbenzene sulfonate.
[0025] Optionally, the step of degumming the green body includes:
[0026] The green blank is heated to 350℃-400℃ at a rate of 2℃ / min-3℃ / min and held at that temperature for 1h-2h. Then, it is heated to 500℃-600℃ at a rate of 5℃ / min-7℃ / min and held at that temperature for 2h-3h.
[0027] Optionally, the step of performing segmented sintering to obtain the PVD target material includes:
[0028] The degummed green body is heated to 700℃-800℃ at a rate of 8℃ / min-12℃ / min and held at that temperature for 1h-2h for low-temperature sintering.
[0029] The green blank after low-temperature sintering is then heated to 1100℃-1300℃ at a rate of 15℃ / min-25℃ / min and held for 1h-2h for high-temperature sintering. Then it is cooled by spark plasma sintering furnace to obtain PVD target material.
[0030] This application also proposes an indium-free high-density, high-conductivity PVD target product, obtained by the above-mentioned preparation method of indium-free high-density, high-conductivity PVD target.
[0031] This application includes at least the following beneficial effects:
[0032] This application uses modified tetraneedle-shaped zinc oxide whiskers as the main raw material for PVD targets. Molecular sieves are used as nucleating agents, and an inert gas is introduced to prepare the modified tetraneedle-shaped zinc oxide whiskers. The unique adsorption and sieving properties of molecular sieves provide nucleation sites for the tetraneedle-shaped zinc oxide and regulate its crystal morphology. Furthermore, the introduction of molecular sieves introduces impurity energy levels into the band gap of the tetraneedle-shaped zinc oxide whiskers, allowing them to respond to longer wavelength photons, thus broadening their light utilization range and acting as traps for electrons or holes to extend carrier lifetime, thereby improving the photoelectric performance of the target material. Simultaneously, the inert gas reduces the oxygen concentration in the furnace, controlling the reduction of the whisker diameter. This reduction in whisker diameter facilitates the uniform filling of the target powder into the mold and reduces damage to the whiskers during pressing, thereby improving the quality of the target product.
[0033] This application prepares PVD targets by blending doped materials with modified tetra-needle zinc oxide whiskers. The doped materials help to adjust the electronic structure of the modified tetra-needle zinc oxide whiskers, affect their electrical conductivity, reduce oxygen vacancies in the modified tetra-needle zinc oxide whiskers, improve their optical properties, and help reduce pores or cracks that may occur during sintering, increase the density of the target material, increase its mechanical strength, and improve the thermal stability of the target material.
[0034] This application involves sequentially ball milling and sand milling the target material raw material. This process refines the modified tetra-needle zinc oxide whisker powder through friction and prevents agglomeration, which would hinder breakage during molding and impede sintering, thus affecting the target material's relative density. Further debinding of the green body removes organic solvents such as forming agents and dispersants, further increasing the target material's relative density. Finally, segmented sintering of the green body facilitates the transition of the modified tetra-needle zinc oxide whiskers from the early to the middle and even late stages of sintering, promoting uniformity and density in powder sintering, thereby further improving the target material's relative density. Therefore, the preparation method described in this application yields a PVD target material with high electrical conductivity and high density, exhibiting excellent electrical and optical properties. Attached Figure Description
[0035] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.
[0036] Figure 1 is a flowchart of the preparation method of indium-free high-density high-conductivity PVD target according to the embodiments of this application;
[0037] Figure 2 is a scanning image of the modified tetrane needle-like zinc oxide whiskers of Example 1 of this application under a 10 μm electron microscope;
[0038] Figure 3 shows the scanning image of the four needle-like zinc oxide whiskers of Comparative Example 1 under a 20 μm electron microscope.
[0039] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation
[0040] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.
[0041] To address the technical problems existing in the prior art, embodiments of this application provide a method for preparing an indium-free, high-density, high-conductivity PVD target, comprising the following steps:
[0042] S10. Modified tetraneedle-shaped zinc oxide whiskers are prepared by using zinc as raw material, molecular sieve as nucleating agent, and inert gas through heating reaction.
[0043] In the specific implementation process, in order to improve the effective separation of photogenerated electrons and holes in the tetra-needle zinc oxide whiskers and broaden the spectral response range, this application modifies the tetra-needle zinc oxide whiskers to prepare modified tetra-needle zinc oxide whiskers. The specific steps are as follows:
[0044] Zinc granules are placed on molecular sieve particles, which are then placed at the bottom of a crucible. The crucible is then placed in a box-type resistance furnace, and an inert gas is introduced at a flow rate of 10 mL / min to 100 mL / min. The temperature is raised to 500℃ to 1100℃, and the reaction is carried out for 10 min to 25 min to obtain modified tetraneedle-shaped zinc oxide whiskers.
[0045] After the reaction is complete, the molecular sieve particles remain in the crucible. The four-needle zinc oxide whiskers are removed, and zinc particles are added in a certain amount. The temperature is raised as required to continue preparing four-needle zinc oxide whiskers. This process is repeated three times before new molecular sieve particles are added to the crucible for repeated use.
[0046] Specifically, the mass ratio of zinc particles to molecular sieve particles is 2:1; nitrogen or argon is used as the inert gas.
[0047] The zinc granules have a purity of 99% and a diameter of 2.5mm-3.5mm; the molecular sieve particles have a diameter of 2.2mm-2.8mm and a loose bulk density of ≥0.66g / mL.
[0048] Because molecular sieves possess strong polarity and a Coulomb field, they preferentially adsorb polar and unsaturated molecules, which is beneficial for the nucleation process of tetraneedle zinc oxide. Furthermore, the uniform pore size distribution of molecular sieves allows only molecules with diameters smaller than the pore size to enter the crystal cavities, influencing the nucleation density and morphology of tetraneedle zinc oxide. The channels and cavities of the molecular sieve provide ideal nucleation sites for tetraneedle zinc oxide, promoting the uniform distribution and growth of tetraneedle zinc oxide crystals. Simultaneously, the polarity and pore size of the molecular sieve interact to affect the crystal morphology of tetraneedle zinc oxide, contributing to the formation of tetraneedle zinc oxide crystals with specific properties. It can serve as a nucleating agent for tetraneedle zinc oxide. Furthermore, this application utilizes inert gas to consume some of the oxygen in the surrounding air, thereby reducing the oxygen concentration in the furnace and meeting the conditions required for the growth of tetraneedle zinc oxide whiskers. This also reduces the diameter of the generated tetraneedle zinc oxide whiskers. The reduced whisker diameter is more beneficial in minimizing damage to the whiskers during the pressing and molding process when the target material is filled into the mold. Specifically, the modified tetraneedle zinc oxide whiskers obtained in this application have a needle diameter of 8μm-35μm, which is lower than the needle diameter of tetraneedle zinc oxide whiskers prepared without the introduction of molecular sieves (35μm-200μm).
[0049] S20. The modified tetraneedle zinc oxide whiskers are mixed with the doped material, and a wetting agent and a dispersant are added. The mixture is then ball-milled to obtain a doped slurry.
[0050] In the specific implementation process, the modified tetra-needle zinc oxide whiskers and the doped material are mixed at a mass ratio of (95-99):(1-5), and then a wetting agent and a dispersant are added to obtain a mixture;
[0051] Mechanical ball milling was employed, and a material with a density of 3.9 g / cm³ was selected. 3 The mixture is ball-milled with alumina grinding balls and water at a mass ratio of (1-2):(2-3):(2-3) for 15-25 hours to obtain a mixed slurry.
[0052] The doped material includes at least one of aluminum oxide, gallium oxide, germanium oxide, selenium oxide, tin oxide, tantalum oxide, nickel, copper, strontium, yttrium, zirconium, niobium, molybdenum, rhodium, palladium, silver, cadmium, antimony, iridium, platinum, gold, lead, graphene, and silicon.
[0053] Doping materials can be selected based on the target material performance requirements. For example, doping with copper or silver can significantly alter the light absorption range of modified tetra-needle zinc oxide whiskers, enabling them to operate over a wider spectral range, or modulating their photoluminescence properties. Doping with aluminum oxide or gallium oxide can reduce oxygen vacancies in the modified tetra-needle zinc oxide whiskers, thereby improving their luminescence efficiency, especially in the ultraviolet and visible light ranges. Doping with copper or nickel can introduce additional electrons or change the valence state of the modified tetra-needle zinc oxide whiskers, thereby improving their conductivity or altering their semiconductor properties. Doping with aluminum oxide, gallium oxide, or germanium oxide can enhance the n-type conductivity of the modified tetra-needle zinc oxide whiskers, improving their performance in certain optoelectronic applications. By mixing the above doping materials with modified tetra-needle zinc oxide whiskers to prepare PVD targets, the doping materials do not change the tetra-needle crystal structure of zinc oxide and help improve the overall performance of the PVD target.
[0054] Specifically, the wetting agent is a mixture of triethanolamine and tromethamine; both triethanolamine and tromethamine contain hydroxyl and amino groups in their molecular structure, which can form an adsorbed hydration layer on the surface of the modified tetraneedle zinc oxide whisker powder particles. At the same time, the combined use of triethanolamine and tromethamine can further form a "hydrogen bond"-like effect, thereby further enhancing the wetting effect on the modified tetraneedle zinc oxide whisker powder.
[0055] The dispersant includes at least one of polyvinylpyrrolidone, hexadecyltrimethylammonium bromide, organophosphonates, and sodium aluminate. Polyvinylpyrrolidone improves the dispersibility of modified tetraneedle-shaped zinc oxide whisker powder, prevents powder agglomeration, and enhances its flowability. Hexadecyltrimethylammonium bromide has a certain wetting effect on the modified tetraneedle-shaped zinc oxide whisker powder, significantly reducing the surface tension of the liquid and strengthening the dispersion of the modified tetraneedle-shaped zinc oxide whisker powder. During dispersion, organophosphonates provide an electrostatic or steric barrier through chemical adsorption to the surface of the modified tetraneedle-shaped zinc oxide whiskers, preventing the re-agglomeration of the modified tetraneedle-shaped zinc oxide whisker particles, thus allowing the modified tetraneedle-shaped zinc oxide whisker powder to be more uniformly dispersed in the matrix. Specific organophosphonates can be selected from tris(2-ethylhexyl)phosphonic acid, di(2-ethylhexyl)phosphonic acid, tris(n-octyl)phosphonic acid, and tris(dodecyl)phosphonic acid, etc. Sodium aluminate can provide aluminate ions (AlO2). - Sodium aluminate interacts electrostatically with the surface of modified tetraneedle zinc oxide whiskers to adjust the charge density on the surface of the modified tetraneedle zinc oxide whiskers, thereby enhancing the repulsive force between particles, reducing agglomeration, and thus improving the dispersibility and stability of the modified tetraneedle zinc oxide whiskers. At the same time, sodium aluminate can also enhance the electrical and optical properties of the modified tetraneedle zinc oxide whiskers.
[0056] S30. The doped and mixed slurry is milled to obtain a milled slurry.
[0057] Specifically, zirconia beads with a particle size of 0.5 mm to 1.0 mm are used as the grinding media, and the rotation speed is controlled at 500 rpm to 900 rpm. The doped and mixed slurry is ground for 2.0 h to 3.0 h to obtain the grinding slurry. In this application, ball milling is used to eliminate soft agglomerates in the modified tetraneedle zinc oxide whisker powder and reduce hard agglomerates. Then, grinding is used to further remove hard agglomerates, which is beneficial to the subsequent pressing and forming of the target material.
[0058] S40. After drying the sand-milled slurry, granulate it to obtain granules.
[0059] Specifically, the slurry is dried at 80℃-90℃ for 40-50 hours, then passed through a 200-300 mesh sieve, and subsequently granulated by rolling for 15-30 minutes to obtain granules. This drying, sieving, and granulation process increases the flowability of the modified tetra-needle zinc oxide whisker powder, facilitating its uniform filling of the mold during subsequent pressing and molding, thereby increasing the green body's forming density and promoting subsequent sintering.
[0060] S50. Add a molding agent to the granules and press them to obtain a green body.
[0061] In the specific implementation process, the dry pressing method is adopted. A molding agent is added to the granules and bidirectional pressure is applied under a pressure of 3MPa-5MPa, with a holding time of 2min-4min, to obtain a green body.
[0062] The molding agent is a mixture of polyacrylic acid, dioctyl ester and sodium dodecylbenzene sulfonate.
[0063] To facilitate the pressing process, this application adds a molding agent and adopts a bidirectional pressing method. The pressing pressure and holding time have a significant impact on the performance of the green body. If the pressing pressure is too low or too high, the ideal green body cannot be achieved. If the holding time is too short, the pressure is difficult to transmit to the required depth. If the holding time is too long, the pressing will be too deep. Therefore, this application preferably uses a pressing pressure of 4 MPa and a holding time of 3 min.
[0064] The molding agent in this application is a mixture of polyacrylic acid, dioctyl ester, and sodium dodecylbenzenesulfonate. Polyacrylic acid provides good adhesion and flowability to the granules, helping them to be more evenly distributed in the mold, which helps to form a dense target structure and provides appropriate flowability during sintering. Dioctyl ester, as a plasticizer, improves the flexibility of polyacrylic acid, reduces the pressure required during molding, prevents the granules from cracking or unevenly distributing during molding, and enhances the stability of the green body after molding. Sodium dodecylbenzenesulfonate, as a surfactant, can reduce the surface tension between granules, enhance the flowability and plasticity of the granules, and also improve the dispersibility between granules, preventing agglomeration. The combination of polyacrylic acid and dioctyl ester enables good adhesion between the granules, while sodium dodecylbenzenesulfonate reduces the friction between particles, allowing the granules to achieve high density during molding and reducing porosity and cracks during target sintering, thereby significantly improving the relative density of the target. At the same time, this molding agent can decompose or volatilize at high temperatures to avoid remaining in the target and affecting its purity.
[0065] S60. The green blank is degummed and then sintered in sections to obtain a PVD target material.
[0066] Specifically, the step of degumming the green body includes:
[0067] The green blank is heated to 350℃-400℃ at a rate of 2℃ / min-3℃ / min and held at that temperature for 1h-2h. Then, it is heated to 500℃-600℃ at a rate of 5℃ / min-7℃ / min and held at that temperature for 2h-3h.
[0068] This application employs a thermal degumming method to degumme the green body. To prevent excessive evaporation of organic solvents such as molding agents and dispersants due to rapid heating, which could lead to a large accumulation of gas inside the green body, causing cracks and affecting the strength of the PVD target material, this application uses a slow heating method. When the temperature reaches 350℃-400℃, it is held at that temperature for 1-2 hours until the quality of the green body stabilizes. Then, the temperature is further increased to 500℃-600℃, at which point the quality change of the green body slows down, thus completing the degumming process.
[0069] Specifically, the step of performing segmented sintering to obtain the PVD target material includes:
[0070] The degummed green body is heated to 700℃-800℃ at a rate of 8℃ / min-12℃ / min and held at that temperature for 1h-2h for low-temperature sintering.
[0071] The green blank after low-temperature sintering is then heated to 1100℃-1300℃ at a rate of 15℃ / min-25℃ / min and held for 1h-2h for high-temperature sintering. Then it is cooled by spark plasma sintering furnace to obtain PVD target material.
[0072] During low-temperature sintering, the modified tetraneedle zinc oxide whiskers begin to react violently. Preferably, the heating rate is 10℃ / min, the temperature is raised to 750℃, and held for 1.5h before high-temperature sintering. Since zinc oxide volatilizes in large quantities at 1350℃, the preferred high-temperature sintering temperature in this application is 1200℃. The combination of low-temperature sintering and high-temperature sintering facilitates the modified tetraneedle zinc oxide whiskers to progress from the early stage of sintering to the middle stage or even the late stage of sintering, promoting the uniformity of the modified tetraneedle zinc oxide whisker powder sintering, thereby further improving the relative density of the PVD target material. The final target material product has a relative density of 97%-99%.
[0073] The embodiments of this application also provide an indium-free high-density, high-conductivity PVD target product, obtained by the above-described method for preparing indium-free high-density, high-conductivity PVD targets.
[0074] The application areas of the target material products in this application may include:
[0075] 1. In the photovoltaic industry, applications include: front electrodes in perovskite solar cells (PSCs) to provide conductivity and light transmission; transparent conductive layers in thin-film solar cells (CIGS, a-Si, etc.) to ensure light transmission and current collection; heterojunction cells and back contact cells in crystalline silicon cells (such as HJT, IBC, etc.) to enhance conductivity and efficiency; and tandem solar cells, such as perovskite / silicon tandems, to improve efficiency and optimize conductivity and light transmittance.
[0076] 2. Display and touch technologies, such as: the transparent conductive layer in OLED displays for current collection, ensuring display quality and transparency; the conductive layer in LCD displays for current distribution, maintaining screen clarity and transparency; and the electrode in touchscreens (such as smartphones and tablets) to provide touch response capabilities.
[0077] 3. Emerging technologies, such as: Quantum Dot Films, which optimize color performance and brightness to improve display effects; Flexible Displays, which support screen bending or folding while maintaining high transparency and conductivity; Smart Windows, which are used to adjust light transmittance and provide intelligent control functions (such as electrochromic windows); and Solar Window Films, which serve as integrated transparent conductive materials to generate photovoltaic power while maintaining the window's light transmittance.
[0078] 4. Automotive industry, such as: for in-vehicle displays and HUD (head-up display) systems, providing transparent electrode functionality; for heated windows to prevent frost and freezing.
[0079] The technical solutions described above in this application will be explained in detail below with reference to specific embodiments.
[0080] Example 1
[0081] A method for preparing an indium-free, high-density, high-conductivity PVD target includes the following steps:
[0082] Zinc granules were placed on molecular sieve particles, and then the molecular sieve particles were placed at the bottom of a crucible. The crucible was then placed in a box-type resistance furnace, and nitrogen gas was introduced at a flow rate of 50 mL / min. The temperature was raised to 800℃ and the reaction was carried out for 17 min to obtain modified tetraneedle-shaped zinc oxide whiskers.
[0083] The zinc granules have a purity of 99% and a diameter of 3.0 mm; the molecular sieve particles have a diameter of 2.3 mm and a loose bulk density of ≥0.66 g / mL.
[0084] The modified tetraneedle-shaped zinc oxide whiskers were mixed with aluminum oxide and gallium oxide at a mass ratio of 98.5:0.5:1, and then a wetting agent and a dispersant were added to obtain a mixture; wherein the wetting agent was a mixture of triethanolamine and tromethamine; and the dispersant was a mixture of polyvinylpyrrolidone and organophosphonates.
[0085] Mechanical ball milling was used, and alumina grinding balls were selected. The mixture was ball milled with alumina grinding balls and water at a mass ratio of 1:2:3 for 20 hours to obtain a mixed slurry.
[0086] The doped and mixed slurry is milled to obtain a milled slurry;
[0087] After drying the sand-milled slurry at 85°C for 45 hours, it is passed through a 250-mesh sieve and then rolled and granulated for 20 minutes to obtain granules.
[0088] The material is subjected to dry pressing, in which a molding agent is added to the granules and bidirectional pressure is applied at 4 MPa for 3 minutes to obtain a green body; wherein the molding agent is a mixture of polyacrylic acid, dioctyl ester and sodium dodecylbenzene sulfonate.
[0089] The green compact is heated to 370°C at a rate of 2.5°C / min and held for 1.5 hours, then heated to 550°C at a rate of 6°C / min and held for 2.5 hours, then heated to 750°C at a rate of 10°C / min and held for 1.5 hours for low-temperature sintering.
[0090] The green blank after low-temperature sintering is then heated to 1200℃ at a rate of 20℃ / min and held for 1.5h for high-temperature sintering. It is then cooled by a spark plasma sintering furnace to obtain PVD target material.
[0091] Example 2
[0092] A method for preparing an indium-free, high-density, high-conductivity PVD target includes the following steps:
[0093] Zinc granules were placed on molecular sieve particles, and then the molecular sieve particles were placed at the bottom of a crucible. The crucible was then placed in a box-type resistance furnace, and argon gas was introduced at a flow rate of 10 mL / min. The temperature was raised to 960℃ and the reaction was carried out for 25 min to obtain modified tetraneedle-shaped zinc oxide whiskers.
[0094] The zinc granules have a purity of 99% and a diameter of 2.5 mm; the molecular sieve particles have a diameter of 2.2 mm and a loose bulk density of ≥0.66 g / mL.
[0095] The modified tetraneedle-shaped zinc oxide whiskers were mixed with alumina and graphene at a mass ratio of 96:2:2, and then a wetting agent and a dispersant were added to obtain a mixture; wherein the wetting agent was a mixture of triethanolamine and tromethamine; and the dispersant was a mixture of hexadecyltrimethylammonium bromide and sodium aluminate.
[0096] Mechanical ball milling was used, and alumina grinding balls were selected. The mixture was ball milled with alumina grinding balls and water at a mass ratio of 2:2:2 for 15 hours to obtain a mixed slurry.
[0097] The doped and mixed slurry is milled to obtain a milled slurry;
[0098] After drying the sand-milled slurry at 80°C for 50 hours, it is passed through a 200-mesh sieve and then rolled and granulated for 15 minutes to obtain granules.
[0099] The material is subjected to a dry pressing process, in which a molding agent is added to the granules and bidirectional pressure is applied at 3 MPa for 4 minutes to obtain a green body; wherein the molding agent is a mixture of polyacrylic acid, dioctyl ester and sodium dodecylbenzene sulfonate.
[0100] The green compact is heated to 350°C at a rate of 2°C / min and held for 2 hours, then heated to 500°C at a rate of 5°C / min and held for 3 hours, and then heated to 700°C at a rate of 8°C / min and held for 2 hours for low-temperature sintering.
[0101] The green blank after low-temperature sintering is then heated to 1100℃ at a rate of 15℃ / min and held for 2 hours for high-temperature sintering. It is then cooled by a spark plasma sintering furnace to obtain PVD target material.
[0102] Example 3
[0103] A method for preparing an indium-free, high-density, high-conductivity PVD target includes the following steps:
[0104] Zinc granules were placed on molecular sieve particles, and then the molecular sieve particles were placed at the bottom of a crucible. The crucible was then placed in a box-type resistance furnace, and nitrogen gas was introduced at a flow rate of 100 mL / min. The temperature was raised to 1100℃ and the reaction was carried out for 25 min to obtain modified tetraneedle-shaped zinc oxide whiskers.
[0105] The zinc granules have a purity of 99% and a diameter of 3.5 mm; the molecular sieve particles have a diameter of 2.8 mm and a loose bulk density of ≥0.66 g / mL.
[0106] The modified tetraneedle-shaped zinc oxide whiskers were mixed with gallium oxide, germanium oxide, aluminum oxide, and tin oxide in a mass ratio of 96:1:1:1:1, and then a wetting agent and a dispersant were added to obtain a mixture. The wetting agent was a mixture of triethanolamine and tromethamine, and the dispersant was a mixture of hexadecyltrimethylammonium bromide, tris(n-octyl)phosphonic acid, and sodium aluminate.
[0107] Mechanical ball milling was used, and alumina grinding balls were selected. The mixture was ball milled with alumina grinding balls and water at a mass ratio of 1:3:3 for 25 hours to obtain a mixed slurry.
[0108] The doped and mixed slurry is milled to obtain a milled slurry;
[0109] After drying the sand-milled slurry at 90°C for 40 hours, it is passed through a 300-mesh sieve and then rolled and granulated for 30 minutes to obtain granules.
[0110] The material is subjected to dry pressing, in which a molding agent is added to the granules and bidirectional pressure is applied at 5 MPa for 2 minutes to obtain a green body; wherein the molding agent is a mixture of polyacrylic acid, dioctyl ester and sodium dodecylbenzene sulfonate.
[0111] The green blank is heated to 400°C at a rate of 3°C / min and held for 1 hour, then heated to 600°C at a rate of 7°C / min and held for 2 hours, and then heated to 800°C at a rate of 12°C / min and held for 1 hour for low-temperature sintering.
[0112] The green blank after low-temperature sintering is then heated to 1300℃ at a rate of 25℃ / min and held for 1 hour for high-temperature sintering. It is then cooled by a spark plasma sintering furnace to obtain the PVD target material.
[0113] Comparative Example 1
[0114] A method for preparing an indium-free, high-density, high-conductivity PVD target includes the following steps:
[0115] After placing the zinc granules at the bottom of the crucible, it was placed in a box-type resistance furnace, heated to 800℃, and reacted for 17 minutes to obtain four needle-like zinc oxide whiskers.
[0116] The subsequent steps are the same as in Example 1.
[0117] Comparative Example 2
[0118] Compared to Example 1, the modified tetraneedle zinc oxide whiskers were replaced with zinc oxide, while the other steps remained the same.
[0119] Experimental Example 1
[0120] The modified tetra-needle zinc oxide whiskers of Example 1 and the tetra-needle zinc oxide whiskers of Comparative Example 1 were subjected to electron microscopy to observe their microstructure, and the electron microscopy scan images shown in Figure 2 and Figure 3 were obtained. Figure 2 is the scan image of the modified tetra-needle zinc oxide whiskers of Example 1 under a 10 μm electron microscope, and Figure 3 is the scan image of the tetra-needle zinc oxide whiskers of Comparative Example 1 under a 20 μm electron microscope.
[0121] As shown in Figures 2 and 3, Pa and R represent different whisker groups, Pa represents the microscopic diameter of each whisker group, and Pb represents the included angle of each whisker group. In Figure 2, the lowest microscopic diameter of the whisker group is 8.990 μm, and the highest is 32.10 μm. In Figure 3, the lowest microscopic diameter of the whisker group is 37.75 μm, and the highest is 56.44 μm. It can be seen that this application uses molecular sieves as nucleating agents and introduces inert gas to reduce the oxygen concentration, resulting in modified tetraneedle-shaped zinc oxide whiskers with smaller needle diameters. The smaller diameter whiskers are more beneficial in reducing damage to the needles during target pressing.
[0122] Experiment Example 2
[0123] The PVD targets in Example 1 and Comparative Examples 1-2 were magnetron sputtered to obtain three different thin films. The sheet resistance, carrier mobility, and average transmittance in the 200nm-800nm wavelength range of each group of thin films were then tested. The test results are shown in Table 1 below.
[0124] Table 1
[0125] As shown in Table 1, the electron mobility of the PVD target material in Example 1 of this application after magnetron sputtering coating is 24.5 cm⁻¹. 2 The sheet resistance of the film prepared in Example 1 is only 20.1 Ω / m, which is higher than that of the films in Comparative Example 1 and Comparative Example 2. 2The transmittance of the film in Example 1 is significantly lower than that of the other two films, indicating that the film exhibits excellent conductivity. Furthermore, its average transmittance in the 200nm-800nm wavelength range reaches 80.12%, which is also higher than that of the other two films, demonstrating superior light transmission performance. This indicates that compared to PVD targets prepared from tetra-needle zinc oxide whiskers and zinc oxide, the PVD target prepared by this application using modified tetra-needle zinc oxide whiskers can significantly improve the electrical properties of the target.
[0126] The above are merely optional embodiments of this application and do not limit the patent scope of this application. Any equivalent structural transformations made based on the inventive concept of this application and the contents of the specification and drawings of this application, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this application.
Claims
1. A method for preparing an indium-free, high-density, high-conductivity PVD target, characterized in that, Includes the following steps: Modified tetraneedle-shaped zinc oxide whiskers were prepared by using zinc as raw material, molecular sieve as nucleating agent, and inert gas through heating reaction. The modified tetraneedle zinc oxide whiskers were mixed with the doped material, and a wetting agent and a dispersant were added. The mixture was then ball-milled to obtain a doped slurry. The doped and mixed slurry is milled to obtain a milled slurry; After drying the sand-milled slurry, it is granulated to obtain granules; A molding agent is added to the granules and then pressed to obtain a green body. The green body is degummed and then sintered in sections to obtain a PVD target material.
2. The method for preparing indium-free high-density, high-conductivity PVD target material according to claim 1, characterized in that, The step of preparing modified tetraneedle-shaped zinc oxide whiskers by using zinc as raw material, molecular sieve as nucleating agent, and introducing inert gas through heating reaction includes: Zinc granules were placed on molecular sieve particles and then placed in a box-type resistance furnace. Inert gas was introduced at a flow rate of 10 mL / min to 100 mL / min, and the temperature was raised to 500℃ to 1100℃. After reacting for 10 min to 25 min, modified tetraneedle-shaped zinc oxide whiskers were obtained.
3. The method for preparing indium-free high-density, high-conductivity PVD target material according to claim 2, characterized in that, The zinc granules have a purity of 99% and a diameter of 2.5 mm to 3.5 mm; the molecular sieve particles have a diameter of 2.2 mm to 2.8 mm and a loose bulk density of ≥0.66 g / mL; the modified tetraneedle-shaped zinc oxide whiskers have a needle diameter of 8 μm to 20 μm.
4. The method for preparing indium-free high-density, high-conductivity PVD target material according to claim 1, characterized in that, The doped material includes at least one of aluminum oxide, gallium oxide, germanium oxide, selenium oxide, tin oxide, tantalum oxide, nickel, copper, strontium, yttrium, zirconium, niobium, molybdenum, rhodium, palladium, silver, cadmium, antimony, iridium, platinum, gold, lead, graphene, and silicon.
5. The method for preparing indium-free high-density, high-conductivity PVD target material according to claim 4, characterized in that, The step of mixing the modified tetra-needle-shaped zinc oxide whiskers with the doped material, adding a wetting agent and a dispersant, and ball milling the mixture to obtain a doped slurry includes: The modified tetra-needle zinc oxide whiskers and doped materials were mixed at a mass ratio of (95-99):(1-5), and then a wetting agent and a dispersant were added to obtain a mixture. Mechanical ball milling was used, and alumina grinding balls were selected. The mixture, alumina grinding balls, and water were ball milled at a mass ratio of (1-2):(2-3):(2-3) for 15-25 hours to obtain a mixed slurry. The wetting agent is a mixture of triethanolamine and tromethamine; the dispersant includes at least one of polyvinylpyrrolidone, hexadecyltrimethylammonium bromide, organophosphonates, and sodium aluminate.
6. The method for preparing indium-free high-density, high-conductivity PVD target material according to claim 1, characterized in that, The step of drying the sand-milled slurry and then granulating it to obtain granules includes: After drying the sand-milled slurry at 80℃-90℃ for 40h-50h, it is passed through a 200-300 mesh sieve and then rolled into granules for 15min-30min to obtain granules.
7. The method for preparing indium-free high-density, high-conductivity PVD target material according to claim 1, characterized in that, The step of adding a molding agent to the granules and pressing them to obtain a green body includes: The dry pressing method is used, in which a molding agent is added to the granules and bidirectional pressure is applied under a pressure of 3MPa-5MPa, and the pressure holding time is 2min-4min to obtain a green body; The molding agent is a mixture of polyacrylic acid, dioctyl ester and sodium dodecylbenzene sulfonate.
8. The method for preparing indium-free high-density, high-conductivity PVD target material according to claim 1, characterized in that, The step of degumming the green body includes: The green blank is heated to 350℃-400℃ at a rate of 2℃ / min-3℃ / min and held at that temperature for 1h-2h. Then, it is heated to 500℃-600℃ at a rate of 5℃ / min-7℃ / min and held at that temperature for 2h-3h.
9. The method for preparing indium-free high-density, high-conductivity PVD target material according to claim 1, characterized in that, The step of performing segmented sintering to obtain the PVD target material includes: The degummed green body is heated to 700℃-800℃ at a rate of 8℃ / min-12℃ / min and held at that temperature for 1h-2h for low-temperature sintering. The green blank after low-temperature sintering is then heated to 1100℃-1300℃ at a rate of 15℃ / min-25℃ / min and held for 1h-2h for high-temperature sintering. Then it is cooled by spark plasma sintering furnace to obtain PVD target material.
10. An indium-free, high-density, high-conductivity PVD target product, characterized in that, The indium-free high-density, high-conductivity PVD target was prepared using the method described in any one of claims 1-9.