High-conductivity and high-density tin oxide-based target material as well as preparation method and application thereof

Abstract

The invention discloses a high-conductivity and high-compactness tin oxide-based target material as well as a preparation method and application thereof, and belongs to the technical field of tin oxide target materials. The stannic oxide-based target material is prepared from the following raw materials in percentage by mass: 0.2%-1% of lead dioxide, 0.2%-0.5% of cadmium oxide, 0.5%-1% of copper, 1%-1.5% of antimony trioxide and the balance of stannic oxide. The tin oxide target material has relatively high density and relatively low resistivity, and can be used for preparing a transparent conductive film.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tin oxide target material, in particular to a high-conductivity and high-density tin oxide-based target material and a preparation method and application thereof. BACKGROUND

[0002] Due to excellent photoelectric properties, ITO target material is widely used in the fields of display, photovoltaic, sensor, detector and the like. However, since indium in the ITO target material is expensive and has a low reserve, the industry needs a transparent conductive film that can replace or partially replace ITO to reduce costs and expand application fields.

[0003] The price of tin oxide is about one-eighth of the price of indium oxide. The tin oxide-based target material can be prepared into a transparent conductive film with good photoelectric properties through a magnetron sputtering process, thereby partially replacing the application of ITO in the fields of photovoltaic and sensor to achieve the effect of cost reduction and efficiency increase.

[0004] In the existing preparation process of the tin oxide-based target material, the tin oxide target material prepared by slip casting has a low density, generally less than 90%, and the target material is prone to abnormality such as sparking and nodulation during film plating, thereby affecting the performance of the film. The tin oxide target material prepared by cold isostatic pressing combined with a sintering process generally has high resistivity and low density. Due to the reasons such as easy volatilization of tin oxide at more than 1100℃, low grain boundary mobility, high lattice energy and poor conductivity of tin oxide, sintering is difficult to densify. In addition, the target material with low conductivity and low density has poor photoelectric properties after magnetron sputtering deposition of a transparent oxide film, and it is difficult to achieve the effect of replacing ITO.

[0005] In view of this, the present application is provided. SUMMARY

[0006] The present application aims to provide a high-conductivity and high-density tin oxide-based target material and a preparation method and application thereof to solve or improve the above technical problems.

[0007] The present application can be achieved as follows: In a first aspect, the present application provides a high-conductivity and high-density tin oxide-based target material. The preparation raw material of the tin oxide-based target material includes 0.2% to 1% of lead dioxide, 0.2% to 0.5% of cadmium oxide, 0.5% to 1% of copper and 1% to 1.5% of antimony sesquioxide, and the balance is tin dioxide.

[0008] In an optional embodiment, the particle size of the lead dioxide, the cadmium oxide, the copper, the antimony sesquioxide and the tin dioxide is independently not more than 1 μm. And / or, the purity of the lead dioxide, the cadmium oxide, the copper, the antimony sesquioxide and the tin dioxide is independently not less than 99.95%.

[0009] In an optional embodiment, the density of the tin oxide-based target is not less than 99.6%. And / or, the resistivity of the tin oxide-based target is not more than 1.5 mΩ·cm.

[0010] In a second aspect, the present application provides a method for preparing the tin oxide-based target according to any one of the preceding embodiments, comprising the following steps: grinding, drying, cold isostatic pressing and debinding sintering of a slurry containing lead dioxide, cadmium oxide, copper, antimony trioxide and tin dioxide.

[0011] In an optional embodiment, the slurry comprises at least one of the following features: Feature 1: the solid content of the slurry is 40wt%-45wt%; Feature 2: the slurry further contains 0.5wt%-0.7wt% of a dispersant; preferably, the dispersant comprises D134C.

[0012] In an optional embodiment, the grinding comprises at least one of the following features: Feature 3: the grinding is performed by sand milling; Feature 4: the grinding time is 40min-70min; Feature 5: the spindle speed of the grinding equipment is 1500r / min-1800r / min; Feature 6: the diameter of the grinding medium is 0.15μm-0.3μm; preferably, the grinding medium is zirconia beads; Feature 7: during the grinding, the ball-to-material ratio is 5:3 to 7:3; Feature 8: after the grinding, the D 50 of the solid in the slurry is 0.2μm-0.3μm.

[0013] In an optional embodiment, the drying comprises at least one of the following features: Feature 9: the drying is performed by spray drying; wherein the inlet air temperature of the spray drying equipment is 190℃-210℃, the outlet air temperature is 95℃-105℃, and the atomizer speed is 13000r / min-15000r / min; Feature 10: the particle size of the dry powder obtained after the drying is 10μm-20μm, and the water content is 0.3wt%-0.7wt%; Feature 11: before the drying, the ground slurry obtained by the grinding is further mixed with a binder.

[0014] In an optional embodiment, the mass of the binder is 1%-3% of the ground slurry; In an optional embodiment, the binder comprises polyvinyl alcohol.

[0015] In an optional embodiment, the cold isostatic pressing is performed at a pressure of 270 MPa to 300 MPa for 30 min to 60 min.

[0016] In an optional embodiment, the debinding and sintering is performed by first heating at a rate of 1 ℃ / min to 2 ℃ / min to 600 ℃ to 650 ℃ under a protective atmosphere, holding for 3 h to 6 h, then heating at a rate of 2 ℃ / min to 3 ℃ / min to 900 ℃ to 1000 ℃, and then heating at a rate of 1 ℃ / min to 2 ℃ / min to 1500 ℃ to 1550 ℃, followed by changing the protective atmosphere to an oxygen atmosphere, holding for 20 h to 25 h after the temperature drops to 1400 ℃ to 1450 ℃, then cooling at a rate of 1 ℃ / min to 2 ℃ / min to 900 ℃ to 1000 ℃, and then cooling at a rate of 2 ℃ / min to 3 ℃ / min to 500 ℃ to 600 ℃, changing the oxygen atmosphere to the protective atmosphere, and naturally cooling to 50 ℃ to 100 ℃.

[0017] In a third aspect, the application provides a use of the tin oxide-based target material according to any one of the preceding embodiments in the preparation of a transparent conductive thin film.

[0018] The application has the following advantages: The addition of lead dioxide in the tin oxide-based target material preparation material can improve the density of the tin oxide target material. Since the melting point of lead dioxide is low, a liquid phase can be formed during sintering. The molten liquid phase acts as a lubricant, and under the driving force of capillary force, the solid particles can more easily slide and rearrange, filling the gaps between the particles, thereby reducing the porosity. Generally, solid particles have higher solubility in liquid phase. The dissolved substances are transported through the liquid phase and then precipitate on the surface of other particles (positions with smaller radius of curvature and lower energy). This process migrates the substances at the particle contact points, promotes neck growth and grain growth, and further densifies the material. The liquid phase wets the surface of the solid particles, forms a meniscus between the particles, and generates capillary pressure, which pulls the particles closer and accelerates the densification.

[0019] Cadmium oxide can improve the conductivity of tin oxide. Since the band gap of cadmium oxide is 2.3 eV, while the band gap of tin oxide is 3.6 eV, doping cadmium oxide can reduce the potential barrier and facilitate electron migration, thereby improving the carrier mobility. In addition, cadmium oxide can also passivate the grain boundaries, further promoting the movement of electrons.

[0020] Copper can melt into a liquid phase at 1500 ℃ to 1550 ℃ under oxygen conditions, which can promote sintering. In addition, the copper liquid can react with oxygen to release heat, promoting the densification of the tin oxide substrate. Copper oxide can also react with antimony trioxide to form a second phase, preventing the sublimation of tin oxide.

[0021] The antimony trioxide can also improve the conductivity of the tin oxide. The ion radius of the antimony is similar to that of the tin, so the lattice distortion caused by the substitution is small. Since the ion valence of the antimony is +5 and the ion valence of the tin is +4, one free electron is released after the substitution, which enters the conduction to significantly improve the conductivity of the tin oxide. In addition, the antimony trioxide is oxidized into antimony pentoxide under a high-temperature oxygen environment, and the process synchronously generates oxygen vacancies to further improve the conductivity.

[0022] The raw material ratio and the method provided by the application can prepare the tin oxide-based target material with low resistivity and high density. The low resistivity is beneficial to the series resistance of the photovoltaic cell, thereby improving the photoelectric conversion efficiency. The high density can improve the performance and yield of the sputtered thin film and reduce the abnormality such as target material nodulation and cracking. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical scheme and advantages of the embodiments of the application more clear, the technical scheme of the embodiments of the application will be clearly and completely described below. If the specific conditions are not specified in the embodiments, the conventional conditions or the conditions suggested by the manufacturer are adopted. If the reagents or instruments are not specified by the manufacturer, they are all conventional products that can be purchased in the market.

[0024] The high-conductivity and high-density tin oxide-based target material provided by the application and the preparation method and application thereof will be described below.

[0025] The application provides a high-conductivity and high-density tin oxide-based target material. The preparation raw material of the tin oxide-based target material comprises 0.2% to 1% of lead dioxide, 0.2% to 0.5% of cadmium oxide, 0.5% to 1% of copper and 1% to 1.5% of antimony trioxide, and the balance is tin dioxide.

[0026] The addition of the lead dioxide can improve the density of the tin oxide target material. Since the melting point of the lead dioxide is low, a liquid phase can be formed during sintering. The molten liquid phase plays a lubricating role, and under the driving of the capillary force, the solid particles can more easily slide and rearrange to fill the interstitial space, thereby reducing the porosity. Generally, the solid particles have a higher solubility in the liquid phase. The dissolved substances are transported through the liquid phase and then precipitate on the surface of other particles (positions with smaller curvature radius and lower energy). This process migrates the substances at the particle contact points, promotes the neck growth and grain growth, and further densifies. The liquid phase wets the surface of the solid particles, forms a meniscus between the particles, generates a capillary pressure, and pulls the particles closer to accelerate the densification.

[0027] The cadmium oxide can improve the conductivity of the tin oxide because the band gap of the cadmium oxide is 2.3 eV, while the band gap of the tin oxide is 3.6 eV. The doping of the cadmium oxide can reduce the potential barrier and facilitate the electron migration, thereby improving the carrier mobility. Meanwhile, the cadmium oxide can also passivate the grain boundaries, further promoting the movement of the electrons.

[0028] The copper can be melted into liquid phase at 1500-1550 °C in the presence of oxygen, which can promote the sintering. Meanwhile, the copper liquid can react with the oxygen to release heat, thereby promoting the densification of the tin oxide substrate. The copper oxide can also react with the antimony trioxide to form a second phase, thereby preventing the sublimation of the tin oxide.

[0029] The antimony trioxide can also improve the conductivity of the tin oxide. The ionic radius of the antimony is similar to that of the tin, and the lattice distortion caused by the substitution is small. Since the valence of the antimony ion is +5, and the valence of the tin ion is +4, the substitution can release a free electron, which can enter the conduction, thereby significantly improving the conductivity of the tin oxide. In addition, the antimony trioxide can be oxidized to antimony pentoxide in the high-temperature oxygen environment, and the process can simultaneously generate oxygen vacancies, thereby further improving the conductivity.

[0030] In some optional embodiments, the lead dioxide contained in the raw material for preparing the tin oxide-based target material can be 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95% or 1%, or other values within the range of 0.2%-1%.

[0031] If the mass of the lead dioxide is less than 0.2%, the effect of promoting densification is poor. If the mass of the lead dioxide is greater than 1%, the high impurity content will generate a second phase, which is not conducive to improving the conductivity.

[0032] The amount of the cadmium oxide contained in the raw material for preparing the tin oxide-based target material can be 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45% or 0.5%, or other values within the range of 0.2%-0.5%.

[0033] If the mass of the cadmium oxide is less than 0.2%, the content in the substrate is too small to have a significant effect on the conductivity of the target material. If the mass of the cadmium oxide is greater than 0.5%, the +2 valence cadmium will capture electrons after replacing the +4 valence tin, thereby reducing the carrier concentration and being not conducive to improving the conductivity.

[0034] The amount of the copper contained in the raw material for preparing the tin oxide-based target material can be 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95% or 1%, or other values within the range of 0.5%-1%.

[0035] If the mass of copper is less than 0.5%, it is not conducive to play the role of copper to promote densification; if the mass of copper is higher than 1%, it will lead to a large number of copper elements enrichment in the grain boundary to form a second phase, which is not conducive to improve the conductivity of the target material.

[0036] The amount of antimony trioxide contained in the preparation raw material of the tin oxide-based target material can be 1%, 1.05%, 1.1%, 1.15%, 1.2%, 1.25%, 1.3%, 1.35%, 1.4%, 1.45% or 1.5%, etc., or other values within the range of 1%~1.5%.

[0037] If the mass of antimony trioxide is less than 1%, the carrier concentration in the base material will be reduced, which is not conducive to improve the conductivity of the target material; if the mass of antimony trioxide is higher than 1.5%, due to the difficulty of sintering of antimony trioxide to be dense, it is not conducive to improve the density of the target material.

[0038] In some optional embodiments, the particle size of the lead dioxide, cadmium oxide, copper, antimony trioxide and tin dioxide is independently not more than 1 μm.

[0039] In some optional embodiments, the purity of the lead dioxide, cadmium oxide, copper, antimony trioxide and tin dioxide is independently not less than 99.95%.

[0040] In some optional embodiments, the density of the tin oxide-based target material is not less than 99.6%, for example, it can be 99.6%~99.8%.

[0041] In some optional embodiments, the resistivity of the tin oxide-based target material is not more than 1.5 mΩ·cm, for example, it can be 0.4 mΩ·cm~1.5 mΩ·cm.

[0042] As mentioned above, the tin oxide-based target material provided by the present application has the characteristics of low resistivity and high density, wherein the low resistivity is conducive to the series resistance of the photovoltaic cell, thereby improving the photoelectric conversion efficiency; the high density can improve the performance and yield of the sputtered thin film, and reduce the abnormality such as target material nodulation and cracking.

[0043] Correspondingly, the present application also provides a preparation method of the above-mentioned tin oxide-based target material, which can include the following steps: grinding, drying, cold isostatic pressing and debinding sintering of the slurry containing lead dioxide, cadmium oxide, copper, antimony trioxide and tin dioxide.

[0044] In some optional embodiments, the solid content of the slurry can be 40wt%~45wt%, such as 40wt%, 41wt%, 42wt%, 43wt%, 44wt% or 45wt%, etc., or other values within the range of 40wt%~45wt%.

[0045] The slurry may also contain a dispersant, the amount of which can be 0.5wt% to 0.7wt%, such as 0.5wt%, 0.55wt%, 0.6wt%, 0.65wt%, or 0.7wt%, or other values ​​within the range of 0.5wt% to 0.7wt%. Examples of dispersants, but not limited to them, include D134C.

[0046] In some alternative implementations, grinding may be performed using a sand mill.

[0047] In practice, the slurry can be stirred for 30 to 60 minutes to make it completely homogenized before being poured into a nano-sand mill for grinding.

[0048] The grinding time can be 40min~70min, such as 40min, 45min, 50min, 55min, 60min, 65min or 70min, or other values ​​within the range of 40min~70min.

[0049] The spindle speed of the grinding equipment can be 1500r / min to 1800r / min, such as 1500r / min, 1550r / min, 1600r / min, 1650r / min, 1700r / min, 1750r / min or 1800r / min, or other values ​​within the range of 1500r / min to 1800r / min.

[0050] The diameter of the polishing media can be 0.15μm to 0.3μm, such as 0.15μm, 0.2μm, 0.25μm or 0.3μm, or other values ​​within the range of 0.15μm to 0.3μm. For example, the polishing media can be zirconia beads.

[0051] During the grinding process, the ball-to-material ratio can be from 5:3 to 7:3, such as 5:3, 5.5:3, 6:3, 6.5:3 or 7:3, or other values ​​within the range of 5:3 to 7:3.

[0052] D of solids in the ground slurry 50 It can be 0.2μm to 0.3μm, such as 0.2μm, 0.25μm or 0.3μm, or other values ​​in the range of 0.2μm to 0.3μm.

[0053] In some alternative implementations, drying may be performed using spray drying.

[0054] The inlet air temperature of the spray drying device can be 190-210°C, such as 190°C, 195°C, 200°C, 205°C, or 210°C, or other values within the range of 190-210°C. The outlet air temperature can be 95-105°C, such as 95°C, 98°C, 100°C, 102°C, or 105°C, or other values within the range of 95-105°C. The atomizer rotation speed can be 13,000-15,000 r / min, such as 13,000 r / min, 13,500 r / min, 14,000 r / min, 14,500 r / min, or 15,000 r / min, or other values within the range of 13,000-15,000 r / min.

[0055] The particle size of the dry powder obtained after drying can be 10-20 μm, such as 10 μm, 15 μm, or 20 μm, or other values within the range of 10-20 μm. The water content of the dry powder obtained after drying can be 0.3-0.7 wt%, such as 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, or 0.7 wt%, or other values within the range of 0.3-0.7 wt%.

[0056] In some optional embodiments, before drying, the ground slurry obtained by grinding can be mixed with a binder and stirred for 40-60 min to mix thoroughly.

[0057] The mass of the binder can be 1-3% of the mass of the ground slurry, such as 1%, 1.5%, 2%, 2.5%, or 3%, or other values within the range of 1-3%. The binder can exemplarily but not limitatively include polyvinyl alcohol, or the like.

[0058] As described above, the dry powder obtained by spray drying has good flowability.

[0059] In some optional embodiments, the pressure of cold isostatic pressing can be 270-300 MPa, such as 270 MPa, 275 MPa, 280 MPa, 285 MPa, 290 MPa, 295 MPa, or 300 MPa, or other values within the range of 270-300 MPa. The pressure holding time can be 30-60 min, such as 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, or 60 min, or other values within the range of 30-60 min.

[0060] The cold isostatic pressing process can be carried out in a round silica gel mold. Specifically, the granulated powder can be loaded into a silica gel mold with a diameter of 100 mm, and the powder filling height can be 12 mm. The mold is sealed and placed in a cold isostatic pressing machine, and then cold isostatic pressing is carried out.

[0061] In some optional embodiments, the debinding and sintering can be carried out in an atmosphere sintering furnace, and the process can include: (1) Under a protective atmosphere (such as argon), first increase the temperature to 600-650°C (such as 600°C, 620°C, 620°C, 630°C, 640°C, or 650°C, etc.) at a rate of 1-2°C / min (such as 1°C / min, 1.5°C / min, or 2°C / min, etc.), and keep the temperature for 3-6h (such as 3h, 4h, 5h, or 6h, etc.); This process mainly removes organic solvents in the target material.

[0062] (2) Increase the temperature to 900-1000°C (such as 900°C, 950°C, or 1000°C, etc.) at a rate of 2-3°C / min (such as 2°C / min, 2.5°C / min, or 3°C / min, etc.), and then increase the temperature to 1500-1550°C (such as 1500°C, 1510°C, 1520°C, 1530°C, 1540°C, or 1550°C, etc.) at a rate of 1-2°C / min (such as 1°C / min, 1.5°C / min, or 2°C / min, etc.); This process can prevent the copper from being oxidized in large quantities; (3) Then, the protective atmosphere is replaced with an oxygen atmosphere, and after the temperature drops to 1400-1450°C (such as 1400°C, 1410°C, 1420°C, 1430°C, 1440°C, or 1450°C, etc.), keep the temperature for 20-25h (such as 20h, 21h, 22h, 23h, 24h, or 25h, etc.); In this process, the copper powder melts into a liquid phase, which can promote sintering, and the copper liquid can react with oxygen to release heat, promoting the densification of the tin oxide substrate. The copper oxide may also chemically react with antimony trioxide to form a second phase, preventing the sublimation of tin oxide.

[0063] (4) cooling to 900-1000°C (for example, 900°C, 950°C or 1000°C) at a rate of 1-2°C / min (for example, 1°C / min, 1.5°C / min or 2°C / min), then cooling to 500-600°C (for example, 500°C, 550°C or 600°C) at a rate of 2-3°C / min (for example, 2°C / min, 2.5°C / min or 3°C / min), changing the oxygen atmosphere to a protective atmosphere (for example, argon), and naturally cooling to 50-100°C (for example, 50°C, 60°C, 70°C, 80°C, 90°C or 100°C).

[0064] The protective gas is introduced when the temperature in the sintering cooling section is reduced to 500-600°C, which can place the tin oxide target in a protective atmosphere, increase oxygen vacancies, and partially decompose copper oxide in the target into cuprous oxide, which also has a certain conductivity, thereby further improving the conductivity of the target.

[0065] Further, the sintered target can be ground and polished.

[0066] In addition, the application also provides a use of the above-mentioned tin oxide-based target in the preparation of a transparent conductive film. The transparent conductive film prepared from the target can be used in the fields of photovoltaics (for example, heterojunction cells, perovskite cells, etc.), flat panel displays, infrared detectors, etc.

[0067] The features and properties of the application are further described in detail below in conjunction with examples.

[0068] Example 1 The present example provides a tin oxide-based target. The raw materials for preparing the tin oxide-based target include 0.5% lead dioxide powder, 0.5% cadmium oxide powder, 0.5% copper powder and 1.25% antimony sesquioxide powder, with the balance being tin dioxide powder.

[0069] The preparation method of the tin oxide-based target includes: S1: 6g of lead dioxide powder, 6g of cadmium oxide powder, 6g of copper powder, 15g of antimony sesquioxide powder and 1167g of tin dioxide powder are weighed, and the purity of all the raw material powders is higher than 99.95wt%, and the particle size of all the raw material powders is less than 1μm.

[0070] S2: all the powders are mixed and poured into a stirring barrel, 1722g of pure water is added, and a slurry with a solid content of about 41wt% is obtained. 18g of a dispersant (model D134C) is added to the slurry (the amount of the dispersant is about 0.6wt% of the slurry), and the slurry is stirred for 40min using a stirrer.

[0071] S3: The stirred slurry was poured into the circulating barrel of the sand mill, and the sand mill was started. The sand mill medium used was zirconia beads with a particle size of 0.2 μm, the ball-to-material ratio was 7:3, and the main shaft rotation speed was 1800 r / min. The slurry was ground for 60 min. The D50 of the solid in the ground slurry was 0.22 μm. 50 The D50 of the solid in the ground slurry was 0.22 μm.

[0072] S4: The ground slurry was added with 60 g of polyvinyl alcohol (about 2 wt% of the ground slurry) as a binder, and the slurry was continuously stirred for 30 min with a stirrer. Then, spray drying was started. The inlet temperature was 200 ℃, the outlet temperature was 105 ℃, the atomizer rotation speed was 14000 r / min, and the peristaltic pump rotation speed was 27 r / min.

[0073] S5: The spray-dried powder was loaded into a circular silica gel mold with a diameter of 100 mm, and the powder filling height was 12 mm. The mold was sealed and placed in a cold isostatic press. The pressure was set to 280 MPa, and the pressure holding time was 30 min.

[0074] S6: The cold isostatic pressing formed target blank was placed in an atmosphere sintering furnace. The temperature was raised to 600 ℃ at a rate of 2 ℃ / min, and the temperature was kept for 4 h. After the temperature keeping, the temperature was raised to 1000 ℃ at a rate of 3 ℃ / min, and then the temperature was raised to 1500 ℃ at a rate of 1 ℃ / min. The whole process was protected by argon. When the temperature was 1500 ℃, the heating was stopped, and the argon protection was stopped. Oxygen was introduced. When the temperature dropped to 1400 ℃, the temperature keeping program was started, and the temperature was kept for 20 h. Then, the temperature was lowered to 1000 ℃ at a rate of 1 ℃ / min, and then the temperature was lowered to 600 ℃ at a rate of 2 ℃ / min. The oxygen protection was stopped, and the argon protection was started. The heating system was turned off, and the furnace was naturally cooled to 100 ℃, and then the furnace was opened.

[0075] S7: The target after the furnace was opened was double ground.

[0076] Example 2 The present example provides a tin oxide-based target. The raw materials for preparing the tin oxide-based target include 0.2% of lead dioxide powder, 0.2% of cadmium oxide powder, 1% of copper powder, and 1.5% of antimony sesquioxide powder, and the balance is tin dioxide powder.

[0077] The difference between the preparation method of the tin oxide-based target and that of Example 1 is that in S1, the amounts of the raw materials are as follows: 2.4 g of lead dioxide powder, 2.4 g of cadmium oxide powder, 12 g of copper powder, 18 g of antimony sesquioxide powder, and 1165.2 g of tin dioxide powder.

[0078] Example 3 The embodiment provides a tin oxide-based target material, and preparation raw materials of the tin oxide-based target material include 0.3% lead dioxide powder, 0.5% cadmium oxide powder, 0.6% copper powder and 1.2% antimony sesquioxide powder, and the balance is tin dioxide powder.

[0079] The preparation method of the tin oxide-based target material is different from that of the embodiment 1, and in S1, the dosages of the raw materials are as follows: 3.6g of lead dioxide powder, 6g of cadmium oxide powder, 7.2g of copper powder, 14.4g of antimony sesquioxide powder and 1168.8g of tin dioxide powder.

[0080] Embodiment 4 The embodiment provides a tin oxide-based target material, and preparation raw materials of the tin oxide-based target material include 0.3% lead dioxide powder, 0.3% cadmium oxide powder, 0.6% copper powder and 1% antimony sesquioxide powder, and the balance is tin dioxide powder.

[0081] The preparation method of the tin oxide-based target material is different from that of the embodiment 1, and in S1, the dosages of the raw materials are as follows: 3.6g of lead dioxide powder, 3.6g of cadmium oxide powder, 7.2g of copper powder, 12g of antimony sesquioxide powder and 1173.6g of tin dioxide powder.

[0082] Embodiment 5 The embodiment provides a tin oxide-based target material, and preparation raw materials of the tin oxide-based target material include 0.4% lead dioxide powder, 0.4% cadmium oxide powder, 0.8% copper powder and 1.5% antimony sesquioxide powder, and the balance is tin dioxide powder.

[0083] The preparation method of the tin oxide-based target material is different from that of the embodiment 1, and in S1, the dosages of the raw materials are as follows: 4.8g of lead dioxide powder, 4.8g of cadmium oxide powder, 9.6g of copper powder, 18g of antimony sesquioxide powder and 1162.8g of tin dioxide powder.

[0084] Embodiment 6 The embodiment provides a tin oxide-based target material, and preparation raw materials of the tin oxide-based target material include 0.5% lead dioxide powder, 0.3% cadmium oxide powder, 1% copper powder and 1.3% antimony sesquioxide powder, and the balance is tin dioxide powder.

[0085] The preparation method of the tin oxide-based target material is different from that of the embodiment 1, and in S1, the dosages of the raw materials are as follows: 6g of lead dioxide powder, 3.6g of cadmium oxide powder, 12g of copper powder, 15.6g of antimony sesquioxide powder and 1162.8g of tin dioxide powder.

[0086] Embodiment 7 The embodiment is different from the embodiment 1 in that: S2: The solid content of the slurry is about 40wt%. After adding 0.5wt% dispersant into the slurry, the slurry is stirred for 30min.

[0087] S3: The sanding medium is zirconia bead with particle size of 0.15μm, the ball-to-material ratio is 7:3, the spindle speed is 1500r / min, and the sanding time is 70min. The D 50 of the solid in the ground slurry is 0.2μm.

[0088] S4: The ground slurry is added with 1wt% polyvinyl alcohol as binder, and the slurry is stirred for 40min by a stirrer, and then spray drying is started, the inlet temperature is 190℃, the outlet temperature is 95℃, the atomizer speed is 13000r / min, and the peristaltic pump speed is 27r / min.

[0089] S5: The spray-dried powder is loaded into a circular silica gel mold with a diameter of 100mm, the powder filling height is 12mm, the mold is sealed and placed in a cold isostatic press, the pressure is set to 270MPa, and the pressure holding time is 60min.

[0090] S6: The cold isostatic pressing formed target blank is placed in an atmosphere sintering furnace, heated to 620℃ at a heating rate of 2℃ / min, and held for 6h; after the holding is completed, the temperature is raised to 1000℃ at a heating rate of 3℃ / min, and then raised to 1520℃ at a heating rate of 1℃ / min, the whole process is protected by argon gas, when the temperature is 1520℃, the heating is stopped, and the argon gas is stopped, and the oxygen gas is switched on, when the temperature drops to 1420℃, the holding program is started, and the holding time is 20h. Then, the temperature is lowered to 1000℃ at a rate of 1℃ / min, and then lowered to 600℃ at a rate of 2.5℃ / min, the oxygen gas is stopped, the argon gas is switched on, and the heating system is turned off, and the furnace is naturally cooled to 100℃, and then taken out.

[0091] S7: The target after taking out of the furnace is double ground.

[0092] Example 8 The difference between this example and Example 1 is: S2: The solid content of the slurry is about 45wt%. After adding 0.7wt% dispersant into the slurry, the slurry is stirred for 60min.

[0093] S3: The sanding medium is zirconia bead with particle size of 0.3μm, the ball-to-material ratio is 7:3, the spindle speed is 1650r / min, and the sanding time is 40min. The D 50 of the solid in the ground slurry is 0.3μm.

[0094] S4: The sand-milled slurry was added with 3wt% polyvinyl alcohol as a binder, and the stirring was continued for 60 minutes, and then the spray drying was started, with an inlet temperature of 210°C, an outlet temperature of 100°C, an atomizer rotating speed of 15000r / min, and a peristaltic pump rotating speed of 27r / min.

[0095] S5: The spray-dried powder was loaded into a circular silica gel mold with a diameter of 100mm, and the powder filling height was 12mm. After the mold was sealed, it was placed in a cold isostatic pressing machine, and the pressure was set to 300MPa, and the pressure holding time was 45min.

[0096] S6: The cold isostatic pressing formed target blank was placed in an atmosphere sintering furnace, and the temperature was raised to 650°C at a rate of 2°C / min, and the temperature was kept for 3h. After the temperature keeping was completed, the temperature was raised to 1000°C at a rate of 3°C / min, and then the temperature was raised to 1550°C at a rate of 1°C / min, and the whole process was protected by argon gas from the start of heating to the temperature of 1550°C. When the temperature was 1550°C, the heating was stopped, and the argon gas was stopped, and the oxygen gas was switched on. When the temperature dropped to 1450°C, the temperature keeping program was started, and the temperature was kept for 25h. Then the temperature was lowered to 1000°C at a rate of 1°C / min, and then the temperature was lowered to 600°C at a rate of 3°C / min. At the same time, the oxygen gas was stopped, and the argon gas was switched on, and the heating system was turned off, and the furnace was naturally cooled to 100°C, and then the furnace was taken out.

[0097] S7: The target after being taken out of the furnace was double-sided polished.

[0098] Comparative Example 1 The present comparative example provides a tin oxide-based target, and the preparation raw materials of the tin oxide-based target include 0.3wt% lead dioxide powder, 0.3wt% cadmium oxide powder, 0.2wt% copper powder, and 1wt% antimony sesquioxide powder, and the balance is tin dioxide powder.

[0099] The difference between the preparation method of the tin oxide-based target and Example 1 is that in S1, the amount of each raw material is as follows: 3.6g of lead dioxide powder, 3.6g of cadmium oxide powder, 2.4g of copper powder, 12g of antimony sesquioxide powder, and 1178.4g of tin dioxide powder.

[0100] Comparative Example 2 The present comparative example provides a tin oxide-based target, and the preparation raw materials of the tin oxide-based target include 0.5wt% lead dioxide powder, 0.3wt% cadmium oxide powder, 1wt% copper powder, and 0.5wt% antimony sesquioxide powder, and the balance is tin dioxide powder.

[0101] The method for preparing the tin oxide-based target differs from that of Example 1 in that in S1, the amounts of the raw materials are as follows: lead dioxide powder 6 g, cadmium oxide powder 3.6 g, copper powder 12 g, antimony trioxide powder 6 g, and tin dioxide powder 1172.4 g.

[0102] Comparative Example 3 This comparative example differs from Example 1 in that the copper powder is replaced with an equal amount of zinc powder.

[0103] Comparative Example 4 This comparative example differs from Example 1 in that the antimony trioxide powder is replaced with an equal amount of niobium pentoxide powder.

[0104] Comparative Example 5 This comparative example differs from Example 1 in that: S6: The cold isostatic pressed target blank is placed in an atmosphere sintering furnace, and heated to 600°C at a heating rate of 2°C / min, and held for 4 h; after the holding period, heated to 1000°C at a heating rate of 3°C / min, and then heated to 1500°C at a heating rate of 1°C / min, and no gas is passed from the start of heating to 800°C, and oxygen is passed after 800°C, and heating is stopped when the temperature is 1500°C; when the temperature drops to 1400°C, a holding program is started, and held for 20 h. Subsequently, cooled to 1000°C at a cooling rate of 1°C / min, and then cooled to 600°C at a cooling rate of 2°C / min, and the oxygen is stopped, and argon is switched in, and the heating system is turned off, and naturally cooled to 100°C, and then taken out of the furnace.

[0105] Comparative Example 6 This comparative example differs from Example 1 in that: S6: The cold isostatic pressed target blank is placed in an atmosphere sintering furnace, and heated to 600°C at a heating rate of 2°C / min, and held for 4 h; after the holding period, heated to 1000°C at a heating rate of 3°C / min, and then heated to 1500°C at a heating rate of 1°C / min, and argon is passed throughout the process from the start of heating to 1500°C, and heating is stopped when the temperature is 1500°C, and the argon is stopped, and oxygen is switched in, and when the temperature drops to 1400°C, a holding program is started, and held for 20 h. Subsequently, cooled to 1000°C at a cooling rate of 1°C / min, and then cooled to 600°C at a cooling rate of 2°C / min, and the oxygen is stopped, and the heating system is turned off, and naturally cooled to 100°C, and then taken out of the furnace.

[0106] Test Example The tin oxide-based targets prepared in Examples 1-8 and Comparative Examples 1-6 are tested for performance, in which the density is tested by the Archimedes method, and the resistivity is tested by the four-probe method, and the results are shown in Table 1.

[0107] Table 1 test results

[0108] As can be seen from Table 1, the prepared tin oxide-based target material by the method provided in the embodiments of the present application can have higher density and lower resistivity than the comparative examples.

[0109] As can be seen from Example 1 and Comparative Examples 1-2, when the ratio of the raw materials for preparing the tin oxide-based target material is improper, the density of the tin oxide-based target material will decrease or the resistivity will increase. In Comparative Example 1, the density of the tin oxide-based target material is significantly lower than that of Example 1, which is mainly due to the insufficient amount of doped copper, which results in insufficient effect of promoting the density of the target material, so the density of the target material decreases significantly. In Comparative Example 2, the resistivity of the tin oxide-based target material is significantly higher than that of Example 1, which is mainly due to the insufficient amount of doped antimony trioxide, which results in insufficient carrier concentration in the target material, so the resistivity of the target material increases and the conductivity deteriorates significantly.

[0110] As can be seen from Example 1 and Comparative Examples 3-4, when the raw materials for preparing the tin oxide-based target material are not properly selected, the density of the tin oxide-based target material will decrease or the resistivity will increase. In Comparative Example 3, the copper powder is replaced by zinc powder, which results in lower density and higher resistivity of the tin oxide-based target material than those of Example 1. In Comparative Example 4, the antimony trioxide powder is replaced by niobium pentoxide powder, which results in lower density and significantly higher resistivity of the tin oxide-based target material than those of Example 1. This shows that the use of copper powder and antimony trioxide powder in the present application is beneficial to improving the density and reducing the resistivity of the tin oxide-based target material.

[0111] As can be seen from Example 1 and Comparative Examples 5-6, when the conditions during the sintering process are not properly controlled, the density of the tin oxide-based target material will decrease or the resistivity will increase. In Comparative Example 5, the density of the tin oxide-based target material is lower than that of Example 1, which is mainly due to the fact that the argon gas protection is not used during the heating process, which results in the oxidation of copper before the tin oxide reaches the densification temperature. Since the tin oxide has not started to densify at this time, the heat released by the oxidation of copper does not help the densification of the tin oxide target material, which results in a decrease in the density of the target material. In Comparative Example 6, the resistivity of the tin oxide-based target material is higher than that of Example 1, which is mainly due to the fact that copper oxide can decompose into cuprous oxide at high temperatures, and cuprous oxide has good conductivity. Since the protective atmosphere is not used during the cooling process after 600°C, the cuprous oxide reacts with oxygen in the air to form copper oxide again, which results in a decrease in the conductive phase in the target material and an increase in the resistivity. At the same time, the use of argon atmosphere at 600°C reduces the oxygen partial pressure, which can appropriately increase the oxygen vacancies in the target material. Oxygen vacancies are beneficial to conductivity, and the reduction of oxygen vacancies in the air environment will also result in an increase in the resistivity.

[0112] In summary, the tin oxide-based target provided by the application has the characteristics of low resistivity and high density, wherein the low resistivity is beneficial to the series resistance of the photovoltaic cell, thereby improving the photoelectric conversion efficiency; the high density can improve the performance and yield of the sputtered film, and reduce the abnormality such as target nodulation and cracking.

[0113] The preferred embodiments of the application are described above, but the application is not limited to the above. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the application shall be included in the protection scope of the application.

Claims

1. A high-conductivity high-density tin oxide-based target material, characterized by, The preparation raw material of the tin oxide-based target material includes 0.2% to 1% of lead dioxide, 0.2% to 0.5% of cadmium oxide, 0.5% to 1% of copper, and 1% to 1.5% of antimony trioxide in terms of mass percentage, and the balance is tin dioxide.

2. The tin oxide-based target according to claim 1, characterized in that, The particle size of the lead dioxide, the cadmium oxide, the copper, the antimony trioxide, and the tin dioxide is independently not more than 1 μm; And / or, the purity of the lead dioxide, the cadmium oxide, the copper, the antimony trioxide, and the tin dioxide is independently not less than 99.95%.

3. The tin oxide-based target according to claim 1 or 2, characterized in that, The density of the tin oxide-based target material is not less than 99.6%; And / or, the resistivity of the tin oxide-based target material is not more than 1.5 mΩ·cm.

4. A method of producing a tin oxide-based target according to any one of claims 1 to 3, characterized by, The method comprises the following steps: The slurry containing the lead dioxide, the cadmium oxide, the copper, the antimony trioxide, and the tin dioxide is grinded, dried, cold isostatic pressed, and debinded and sintered.

5. The preparation method according to claim 4, characterized in that, The slurry comprises at least one of the following characteristics: Characteristic 1: the solid content of the slurry is 40 wt% to 45 wt%; Characteristic 2: the slurry further contains 0.5 wt% to 0.7 wt% of a dispersant; preferably, the dispersant comprises D134C.

6. The preparation method according to claim 4, characterized in that, The grinding comprises at least one of the following characteristics: Characteristic 3: the grinding is performed in a sand grinding mode; Characteristic 4: the grinding time is 40 min to 70 min; Characteristic 5: the main shaft rotation speed of the grinding equipment is 1500 r / min to 1800 r / min; Characteristic 6: the diameter of the grinding medium is 0.15 μm to 0.3 μm; preferably, the grinding medium is zirconium oxide beads; Characteristic 7: during the grinding process, the ball-to-material ratio is 5:3 to 7:3; Characteristic 8: D50 of the solids in the slurry after milling 50 0.2 to 0.3 μm.

7. The preparation method according to claim 4, characterized in that, The drying comprises at least one of the following characteristics: Characteristic 9: the drying is performed in a spray drying mode; wherein, the air inlet temperature of the spray drying equipment is 190 ℃ to 210 ℃, the air outlet temperature is 95 ℃ to 105 ℃, and the atomizer rotation speed is 13000 r / min to 15000 r / min; Characteristic 10: the particle size of the dry powder obtained after the drying is 10 μm to 20 μm, and the water content is 0.3 wt% to 0.7 wt%; Characteristic 11: before the drying, the grinded slurry obtained by the grinding is further mixed with a binder; Preferably, the mass of the binder is 1% to 3% of the grinded slurry; Preferably, the binder comprises polyvinyl alcohol.

8. The preparation method according to claim 4, characterized in that, The cold isostatic pressing condition comprises: the pressure is 270 MPa to 300 MPa, and the pressure maintaining time is 30 min to 60 min.

9. The preparation method according to claim 4, characterized in that, The defatting sintering comprises: under a protective atmosphere, first heating at a rate of 1 ℃ / min~2 ℃ / min to 600 ℃~650 ℃, and keeping the temperature for 3h~6h; heating at a rate of 2 ℃ / min~3 ℃ / min to 900 ℃~1000 ℃; then heating at a rate of 1 ℃ / min~2 ℃ / min to 1500 ℃~1550 ℃; subsequently, the protective atmosphere is changed into an oxygen atmosphere, and after the temperature drops to 1400 ℃~1450 ℃, keeping the temperature for 20h~25h; then, heating at a rate of 1 ℃ / min~2 ℃ / min to 900 ℃~1000 ℃, and then heating at a rate of 2 ℃ / min~3 ℃ / min to 500 ℃~600 ℃, the oxygen atmosphere is changed into the protective atmosphere, and naturally cooling to 50 ℃~100 ℃.

10. Use of a tin oxide-based target according to any one of claims 1 to 3 for the production of a transparent conductive film.

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