A doped IZO target material for sputtering thin film transistors and a preparation method thereof

Abstract

The present application relates to the technical field of sputtering targets, and specifically discloses a doped IZO target for sputtering thin-film transistors and a preparation method thereof. A doped IZO target for sputtering thin-film transistors comprises a multicomponent oxide powder, a binder, and a plasticizer; the multicomponent oxide powder comprises the following raw materials in parts by weight: 86-89.6 parts indium oxide, 9.5-12.8 parts zinc oxide, 0.5-1.2 parts zirconium oxide, and 0.1-0.4 parts thallium oxide. The specific surface area of ​​the multicomponent oxide powder is 8 m 2 / g‑20m 2 / g, and the bulk density is 0.91g / cm 3 ‑1.55g / cm 3 The doped IZO target material for sputtering thin-film transistors disclosed herein is made by adding zirconium and thallium elements to a multinary oxide powder. The low melting point of thallium oxide causes a liquid phase reaction, forming a low-melting eutectic with zirconium oxide. The eutectic is then compounded with indium oxide and zinc oxide. This reduces the porosity and resistivity of the target material, thereby improving the electrical and optical stability of the sputtered film.

Description

Technical Field

[0001] The present application relates to the field of target material technology, and more specifically, to a doped IZO target material for sputtering thin film transistors and a preparation method thereof. Background Art

[0002] Thin-film transistors (TFTs) are the active switching elements of current flat-panel displays, and their performance determines the quality of the display. The performance of the target material, the sputtering substrate required for sputtering film formation of TFT devices, directly determines the quality of the sputtered film. The performance of the target material affects the coating effect. Target materials with high density, uniform target grains, low resistivity, and high strength can help improve the performance of the sputtered film. Display technology is constantly evolving, and many panel manufacturers are moving towards large-size, ultra-high-definition technology. Ultra-high-definition and ultra-large-size display devices place higher demands on the performance of TFT devices.

[0003] Amorphous indium gallium zinc oxide (IGZO) films have excellent properties such as high transmittance in the visible light range, low-temperature preparation, low preparation cost, and good uniformity due to the amorphous state. They have gradually been commercialized and mass-produced, but are still mostly used in small-size and flexible display fields. In the field of ultra-large-size and ultra-high display, higher mobility and higher optical and electrical stability than IGZO films are required to replace them.

[0004] IZO thin films have been extensively studied both domestically and internationally. While they offer high mobility, the lack of oxygen vacancy inhibitors leads to high oxygen vacancy concentrations, resulting in increased carrier concentrations within the film. This can cause negative shifts in the threshold voltage of TFT devices, resulting in low electrical stability and unstable device on / off states, leading to degraded display quality. Currently, doped IZO targets produced by existing institutions or target manufacturers have yet to achieve high densification levels. Conventional sintering of targets consumes high energy and suffers from issues such as uneven grain structure and grain growth within the target. Summary of the Invention

[0005] In order to solve the problems of low density, uneven grain structure and high resistivity of the current doped IZO target, the present application provides a doped IZO target for sputtering thin film transistors and a preparation method thereof.

[0006] In a first aspect, the present application provides a doped IZO target for sputtering thin film transistors, which adopts the following technical solution:

[0007] A doped IZO target for sputtering thin film transistors, comprising a multi-component oxide powder, a binder, and a plasticizer; the multi-component oxide powder comprises the following raw materials in parts by weight: 86-89.6 parts of indium oxide, 9.5-12.8 parts of zinc oxide, 0.5-1.2 parts of zirconium oxide, and 0.1-0.4 parts of thallium oxide; the specific surface area of ​​the multi-component oxide powder is 8m 2 / g-20m 2 / g, and the bulk density is 0.91g / cm 3 -1.55g / cm 3 .

[0008] By adopting the above technical solution, thallium oxide is added as a sintering aid to promote the sintering reaction. Thallium oxide has a melting point of 718°C, much lower than that of indium oxide and zinc oxide. During sintering, thallium oxide undergoes a liquid-phase reaction within the target body, increasing interparticle fluidity. Liquid-phase mass migration is faster than solid-phase diffusion, and the liquid phase fills the pores within the target sintered body, effectively eliminating the pores within the target body. Zirconium and oxygen form strong ionic bonds. While the liquid-phase reaction of thallium oxide promotes interparticle fluidity, the addition of zirconium oxide forms a low-melting eutectic with thallium oxide. The secondary phase formed by thallium oxide and zirconium oxide within the target is evenly distributed within the target grains, avoiding the problem of uneven distribution of target grains caused by the irregular flow of the liquid-phase reaction of thallium oxide. Adding thallium oxide and zirconium oxide to IZO targets can significantly reduce target porosity, significantly improve target density, and reduce target resistivity.

[0009] Controlling the multicomponent oxide powder to have a large specific surface area can increase the contact area between particles, promote uniform sintering of the multicomponent oxide powder, improve sintering diffusion efficiency, reduce the generation of large pores and the total number of pores, thereby increasing the density of the multicomponent oxide powder and the density of the target material, reducing the resistivity of the sputtered film, and improving the electrical and optical stability of the sputtered film. Controlling the bulk density of the multicomponent oxide powder within a reasonable range can adjust the flowability of the oxide powder, thereby facilitating subsequent sintering and forming of the oxide powder.

[0010] Preferably, the D50 of the multi-component oxide powder is ≤80%.

[0011] Preferably, the mass of the binder is 0.2-1.2% of the mass of the multinary oxide powder, and the mass of the plasticizer is 0.2-1.5% of the mass of the multinary oxide powder.

[0012] Preferably, the binder is one of polyvinyl alcohol, sodium carboxymethyl cellulose, polyvinyl chloride and hydroxypropyl methylcellulose.

[0013] By adopting the above technical solution, the binder can promote close bonding between the multi-component oxide powder particles, resulting in greater strength and easier molding of the sintered target blank. The binder, primarily composed of polyvinyl alcohol, sodium carboxymethyl cellulose, polyvinyl chloride, and hydroxypropyl methylcellulose, promotes the compaction of the oxide powder while reducing reactions with the elements in the oxide powder, thereby increasing target strength and reducing delamination.

[0014] Preferably, the plasticizer is polyethylene glycol.

[0015] By adopting the above technical solution, polyethylene glycol is added as a plasticizer to the multi-component oxide powder system to adjust the viscosity and melting point, promote the molding of the multi-component oxide powder, increase the density of the target material, and thereby improve the electrical and optical stability of the IZO target material.

[0016] In a second aspect, the present application provides a method for preparing a doped IZO target for sputtering thin film transistors, using the following technical solution:

[0017] A method for preparing a doped IZO target for sputtering a thin film transistor comprises the following specific steps:

[0018] Preparation of mixed doped IZO powder: Indium oxide, zinc oxide, zirconium oxide, and thallium oxide are mixed in advance, a dispersant is added and ground, a binder and a plasticizer are added and mixed to form a mixed slurry, and the mixed slurry is spray granulated to obtain mixed doped IZO powder;

[0019] Pressing and molding: The mixed doped IZO powder is pressed and molded by cold isostatic pressing at a pressure of 120-350 MPa to form a target blank;

[0020] Sintering: First, the target blank is degreased and pre-sintered in sequence, and then the target is sintered at high temperature;

[0021] Finally, the sintered target material is polished, assembled and tested to obtain the doped IZO target material for sputtering thin film transistors.

[0022] By adopting the above-mentioned technical solution, the multi-oxide powder prepared by wet mixing and grinding and spray drying and granulation in this application has a good molding effect and a high density, and then is made into a doped IZO target material through static pressing, degreasing, pre-sintering and high-temperature sintering. Under the synergistic effect of various components, it has a good density, reduces the resistivity, and improves the optical and electrical stability of the target material.

[0023] Preferably, the grinding process uses a front-end and back-end mixed grinding method, using zirconium beads with a diameter of 1.2-1.4 mm, a grinding time of 6-8 hours per time, and 6-8 cycles of grinding to complete the front-end grinding; after the front-end grinding is completed, the back-end grinding is entered, using zirconium balls with a diameter of 0.8-1 mm for grinding, a grinding time of 8-10 hours per time, and 8-10 cycles of grinding, that is, the grinding process.

[0024] By adopting the above technical solution and using zirconium balls of different sizes in the front and back stages to grind the multi-element oxide powder, it is possible to promote the full and uniform dispersion of each oxide powder, while enhancing the uniformity of each oxide powder, thereby improving the density of the target material and enhancing the optical and electrical stability of the target material.

[0025] Preferably, the debinding sintering temperature is 550-700° C., and the debinding sintering heating rate is 0.8-3.5° C. / min; the pre-sintering temperature is 750-900° C., and the pre-sintering heating rate is 0.4-1.2° C. / min.

[0026] By adopting the above technical solution, the target material blank is pre-degreased and pre-sintered, replacing the existing process of pressing oxide powder into shape and then directly sintering it in one step. This reduces the problem of a large number of pores in the target material after the traditional one-step sintering process, which affects the target material density.

[0027] The degreasing process can promote the oxidation and volatilization of high molecular chemical reagents in the multi-element oxide powder. At the same time, the large number of pores in the target blank can be removed through pre-sintering, thereby increasing the density of the target material, reducing the resistivity of the sputtered film, and improving the electrical and optical stability of the sputtered film.

[0028] Preferably, the high-temperature sintering adopts microwave sintering technology, and the microwave sintering technology uses a microwave sintering furnace for closed sintering, the microwave frequency is 30Ghz-80Ghz, the heating rate is 10.0-25.0°C / min, and the maximum microwave sintering temperature is 1050-1200°C.

[0029] By adopting the above technical solution, closed sintering in a microwave sintering furnace replaces traditional high-temperature sintering at normal pressure, which can reduce the volatilization of indium oxide and zinc oxide, reduce the holes in the target material, and improve the densification of the target material; microwave sintering makes the particles inside the target material evenly heated, the growth rate between the grains is uniform, and the microscopic grain structure is relatively more uniform. The uniform structure of the target material can improve the electrical stability of the thin film after sputtering coating; using microwave sintering technology to sinter the target material is fast and has high energy utilization, which significantly reduces energy consumption and production costs.

[0030] Preferably, when the target blank is sintered at a high temperature, zirconium oxide is laid between the target and the setter in advance.

[0031] By adopting the above technical solution, laying zirconium oxide on the setter can reduce adhesion between the target and the setter, reducing the contact area between the target and the setter. This in turn reduces the thermal stress caused by target shrinkage when the target cools down after high-temperature sintering, improving the stability and densification of the target forming, and thus improving the electrical and optical stability of the sputtered film. Using zirconium oxide particles instead of traditional aluminum oxide can avoid the phenomenon of target and aluminum oxide reacting at high temperatures, promote target forming, and improve target stability.

[0032] In summary, this application has the following beneficial effects:

[0033] 1. This application utilizes thallium oxide and zirconium oxide powders, which form a low-melting eutectic during sintering. This liquid-phase reaction effectively eliminates pores and improves target density. Thallium oxide and zirconium oxide form a secondary phase that is evenly distributed within the target grains, enhancing target performance. Adjusting the multicomponent oxide powder to have a larger specific surface area increases the contact area between particles, thereby improving the density of the multicomponent oxide powder, increasing the density of the target, and reducing the resistivity of the sputtered film.

[0034] 2. In this application, it is preferred to perform degreasing and pre-sintering before high-temperature sintering of the target blank to oxidize and volatilize the polymer chemical reagents in the multi-component oxide powder, which can reduce the generation of pores in the target material and improve the density of the target material.

[0035] 3. The microwave sintering technology used in this application allows the particles inside the target material to be evenly heated, the growth rate between the grains to be uniform, the target material to be fired with uniform grain size, and fine grain strengthening, which can improve the strength of the target material. At the same time, the uniform grain size of the target material is conducive to improving the composition uniformity of the film after coating. On the other hand, the microwave sintering technology can sinter doped IZO targets at a maximum temperature of 1050-1200°C, with a fast sintering speed and high energy utilization, which significantly reduces energy consumption and production costs. DETAILED DESCRIPTION

[0036] The present application is further described in detail below with reference to the embodiments.

[0037] The purity of indium oxide, zinc oxide, zirconium oxide and thallium oxide powders is uniformly 4N.

[0038] The molecular weight of polyvinyl alcohol is 170,000.

[0039] The polyethylene glycol selected was PEG400.

[0040] The molecular weight of polyvinyl chloride is 70,000.

[0041] Example

[0042] Example 1

[0043] This embodiment provides a doped IZO target for sputtering thin film transistors, comprising multinary oxide powder, a binder, and a plasticizer, wherein the binder is polyvinyl alcohol, the plasticizer is polyethylene glycol, the binder mass is 0.7% of the multinary oxide powder mass, and the plasticizer mass is 0.9% of the multinary oxide powder mass;

[0044] The multi-component oxide powder includes the following raw materials in parts by weight: 87.8 kg of indium oxide, 11.15 kg of zinc oxide, 0.85 kg of zirconium oxide, and 0.25 kg of thallium oxide.

[0045] A method for preparing a doped IZO target for sputtering a thin film transistor comprises the following specific steps:

[0046] S1: Preparation of mixed doped IZO powder: Indium oxide, zinc oxide, zirconium oxide, and thallium oxide were mixed in advance, and sodium dodecylbenzenesulfonate was added as a dispersant for grinding. The grinding was carried out in a ball mill with zirconium beads of 1.2 mm in diameter. The speed was set to 600 rpm, the grinding time was 6 h, and the grinding cycle was repeated 6 times. After the ball milling was completed, the D50 of the multi-component oxide powder was ≤80%, and the specific surface area of ​​the multi-component oxide powder was 15 m 2 / g, bulk density is 1.25g / cm 3 , then add binder and plasticizer and stir for 4 hours to form a mixed slurry; then spray granulate the mixed slurry to obtain mixed doped IZO powder, the total impurity content of the powder is ≤200ppm, and the specific surface area of ​​the powder is 8m 2 / g-20m 2 / g, the powder bulk density is 0.91g / cm 3 -1.55g / cm 3 between.

[0047] S2: Pressing and molding: The mixed doped IZO powder is pressed by wet cold isostatic pressing, and the molding pressure is set to 185 MPa to form a target blank. The height of the target blank after molding is 300 mm.

[0048] S3: Degrease the target blank at a degreasing temperature of 630°C and a sintering heating rate of 2.15°C / min. After degreasing, pre-sintering is performed at a sintering temperature of 825°C and a pre-sintering heating rate of 0.8°C / min. After pre-sintering, the target is sintered at a normal pressure and high temperature at a sintering temperature of 1520°C and a heating rate of 2.5°C / min to complete the high temperature sintering.

[0049] S4: The sintered target material is polished and inspected to obtain a doped IZO target material for sputtering thin film transistors.

[0050] Example 2

[0051] The difference between Example 2 and Example 1 is that the amount of indium oxide used in the multi-element oxide powder raw material is 86 kg, the amount of zinc oxide used is 12.8 kg, the amount of zirconium oxide used is 0.5 kg, and the amount of thallium oxide used is 0.4 kg.

[0052] Example 3

[0053] The difference between Example 3 and Example 1 is that the amount of indium oxide used in the multi-element oxide powder raw material is 89.6 kg, the amount of zinc oxide used is 9.5 kg, the amount of zirconium oxide used is 1.2 kg, and the amount of thallium oxide used is 0.1 kg.

[0054] Example 4

[0055] The difference between Example 4 and Example 1 is that the binder in the doped IZO target raw material is sodium carboxymethyl cellulose.

[0056] Example 5

[0057] The difference between Example 5 and Example 1 is that the binder in the doped IZO target raw material is polyvinyl chloride.

[0058] Example 6

[0059] The difference between Example 6 and Example 1 is that the binder in the doped IZO target raw material is hydroxypropyl methylcellulose.

[0060] Example 7

[0061] The difference between Example 7 and Example 1 is that the front-end and back-end mixed grinding method is used in the preparation method of the doped IZO target.

[0062] A method for preparing a doped IZO target for sputtering a thin film transistor comprises the following specific steps:

[0063] S1: Preparation of mixed doped IZO powder: Indium oxide, zinc oxide, zirconium oxide and thallium oxide are mixed in advance, and sodium dodecylbenzene sulfonate is added as a dispersant for grinding. The ball mill is used for grinding. The front stage uses zirconium beads with a diameter of 1.2 mm, the speed is set to 600 rpm, the grinding time is 6 hours, and the grinding cycle is repeated 6 times. After the front stage ball milling is completed, the back stage grinding is carried out. Zirconium balls with a diameter of 1 mm are used for ball milling. The speed is set to 650 rpm. The grinding time is 10 hours, and the grinding cycle is repeated 8 times to complete the front-back stage mixed grinding. After the ball milling is completed, the multi-element oxide powder D50 ≤ 80%, and the specific surface area of ​​the multi-element oxide powder is 20m 2 / g, bulk density is 1.55g / cm 3, then add binder and plasticizer and stir for 4 hours to form a mixed slurry; then spray granulate the mixed slurry to obtain mixed doped IZO powder, the total impurity content of the powder is ≤200ppm, and the specific surface area of ​​the powder is 8m 2 / g-20m 2 / g, the powder bulk density is 0.91g / cm 3 -1.55g / cm 3 between.

[0064] S2: Pressing and molding: The mixed doped IZO powder is pressed by wet cold isostatic pressing, and the molding pressure is set to 185 MPa to form a target blank. The height of the target blank after molding is 300 mm.

[0065] S3: Degrease the target blank at a degreasing temperature of 630°C and a sintering heating rate of 2.15°C / min. After degreasing, pre-sintering is performed at a sintering temperature of 825°C and a pre-sintering heating rate of 0.8°C / min. After pre-sintering, the target is sintered at a normal pressure and high temperature at a sintering temperature of 1520°C and a heating rate of 2.5°C / min to complete the high temperature sintering.

[0066] S4: The sintered target material is polished and inspected for use as a doped IZO target material for sputtering thin film transistors.

[0067] Example 8

[0068] The difference between Example 8 and Example 1 is that the high-temperature sintering in the preparation method of the doped IZO target material adopts microwave sintering technology.

[0069] A method for preparing a doped IZO target for sputtering a thin film transistor comprises the following specific steps:

[0070] S1: Preparation of mixed doped IZO powder: Indium oxide, zinc oxide, zirconium oxide and thallium oxide are mixed in advance, and sodium dodecylbenzene sulfonate is added as a dispersant for grinding. The ball mill is used for grinding. The front stage uses zirconium beads with a diameter of 1.2 mm, the speed is set to 600 rpm, the grinding time is 6 hours, and the grinding cycle is repeated 6 times. After the front stage ball milling is completed, the back stage grinding is carried out. Zirconium balls with a diameter of 1 mm are used for ball milling. The speed is set to 650 rpm. The grinding time is 10 hours, and the grinding cycle is repeated 8 times to complete the front-back stage mixed grinding. After the ball milling is completed, the multi-element oxide powder D50 ≤ 80%, and the specific surface area of ​​the multi-element oxide powder is 20m 2 / g, bulk density is 1.55g / cm 3 , then add binder and plasticizer and stir for 4 hours to form a mixed slurry; then spray granulate the mixed slurry to obtain mixed doped IZO powder, the total impurity content of the powder is ≤200ppm, and the specific surface area of ​​the powder is 8m2 / g-20m 2 / g, the powder bulk density is 0.91g / cm 3 -1.55g / cm 3 between.

[0071] S2: Pressing and molding: The mixed doped IZO powder is pressed by wet cold isostatic pressing, and the molding pressure is set to 185 MPa to form a target blank. The height of the target blank after molding is 300 mm.

[0072] S3: Degrease the target blank at a degreasing temperature of 630°C and a sintering heating rate of 2.15°C / min. After degreasing, pre-sinter the target blank at a sintering temperature of 825°C and a pre-sintering heating rate of 0.8°C / min. After pre-sintering, the target blank is sintered in a closed manner in a microwave sintering furnace at a heating rate of 17.5°C / min, a maximum sintering temperature of 1125°C, and a microwave frequency of 60Ghz to complete high-temperature sintering.

[0073] S4: The sintered target material is polished and inspected to obtain a doped IZO target material for sputtering thin film transistors.

[0074] Example 9

[0075] The difference between Example 9 and Example 8 is that in the preparation method of the doped IZO target, zirconium oxide is used to separate the target blank from the setter plate, wherein the diameter of the zirconium oxide particles is 0.5 mm.

[0076] A method for preparing a doped IZO target for sputtering a thin film transistor comprises the following specific steps:

[0077] S1: Preparation of mixed doped IZO powder: Indium oxide, zinc oxide, zirconium oxide and thallium oxide are mixed in advance, and sodium dodecylbenzene sulfonate is added as a dispersant for grinding. The ball mill is used for grinding. The front stage uses zirconium beads with a diameter of 1.2 mm, the speed is set to 600 rpm, the grinding time is 6 hours, and the grinding cycle is repeated 6 times. After the front stage ball milling is completed, the back stage grinding is carried out. Zirconium balls with a diameter of 1 mm are used for ball milling. The speed is set to 650 rpm. The grinding time is 10 hours, and the grinding cycle is repeated 8 times to complete the front-back stage mixed grinding. After the ball milling is completed, the multi-element oxide powder D50 ≤ 80%, and the specific surface area of ​​the multi-element oxide powder is 20m 2 / g, bulk density is 1.55g / cm 3 , then add binder and plasticizer and stir for 4 hours to form a mixed slurry; then spray granulate the mixed slurry to obtain mixed doped IZO powder, the total impurity content of the powder is ≤200ppm, and the specific surface area of ​​the powder is 8m 2 / g-20m 2 / g, the powder bulk density is 0.91g / cm 3 -1.55g / cm 3 between.

[0078] S2: Pressing and molding: The mixed doped IZO powder is pressed by wet cold isostatic pressing, and the molding pressure is set to 185 MPa to form a target blank. The height of the target blank after molding is 300 mm.

[0079] S3: Evenly lay a layer of zirconium oxide particles on the support plate, and then lay the target blank on the surface of the zirconium oxide particles, and then degrease the target blank. The degreasing temperature is 630℃, and the sintering heating rate is 2.15℃ / min. After degreasing, pre-sintering is performed, and the sintering temperature is 825℃, and the pre-sintering heating rate is 0.8℃ / min. After pre-sintering, the target material is closed-type sintered in a microwave sintering furnace with a heating rate of 17.5℃ / min, the maximum sintering temperature is 1125℃, and the microwave frequency is 60Ghz to complete high-temperature sintering.

[0080] S4: The sintered target material is polished and inspected to obtain a doped IZO target material for sputtering thin film transistors.

[0081] Example 10

[0082] The difference between Example 10 and Example 9 is that in the preparation method of the doped IZO target material, aluminum oxide particles of equal size are used instead of zirconium oxide.

[0083] Comparative Example

[0084] Comparative Example 1

[0085] The difference between Comparative Example 1 and Example 1 is that in the preparation method of the doped IZO target, after grinding, the specific surface area of ​​the multi-component oxide powder is 5m 2 / g.

[0086] Performance testing

[0087] According to the doped IZO target materials for sputtering thin film transistors provided in Examples 1-10 and Comparative Example 1 of the present application, the following performance tests were performed, and the specific test results are shown in Table 1.

[0088] Detection method

[0089] 1. Transparency and Mobility

[0090] Using polyethylene terephthalate as a substrate, a magnetron sputtering device was used to sputter-coat the thin-film transistor channel layer using the doped IZO target prepared in this application. Then, the insulating layer, ITO pixel electrode and gate of the TFT were coated. The sputtering power was 6.0 kW, and the deposited IZO film thickness was 100 nm. The thin film mobility of the TFT was tested using a Hall effect tester, and the transmittance of the film was tested using an ultraviolet spectrophotometer.

[0091] 2. Target Density

[0092] The relative density of the doped IZO target prepared in this application was measured using the Archimedes drainage method.

[0093] 3. Resistivity

[0094] The resistivity of the doped IZO target prepared in this application was tested using a four-probe tester (TYJX-CZ type).

[0095] Table 1: Performance test data table

[0096]

[0097] Performance test results show that the doped IZO target prepared in this application for sputtering thin-film transistors has high film mobility and transmittance. At the same time, the doped IZO target prepared in this application has high density and low resistivity, which can meet the performance requirements of thin-film transistors for high mobility and stable optical and electrical properties. In Examples 1-3 of this application, the amount of each raw material in the multi-component oxide powder in the doped IZO target raw material varies, among which the amount of each component used in Example 1 is more appropriate.

[0098] By comparing Examples 4, 5, and 6 with Example 1, it can be seen that Examples 4, 5, and 6 use different binders. As can be seen from the performance test results in Table 1, the targets prepared with the binders used in Examples 4 and 1 have better overall performance. This may be because carboxymethyl cellulose and polyvinyl alcohol can better promote the bonding and molding of multi-component oxide powders, increase the viscosity of the multi-component oxide powder system, and thus improve the density of the target. At the same time, hydroxypropyl methylcellulose as a binder may need to be used in combination with other binders, thereby increasing processing costs.

[0099] In the preparation method of the doped IZO target material in Example 7, a front-end and back-end mixed grinding method is used for the multi-element oxide powder. From the performance test results, it can be seen that the density of the target material is further improved, the resistivity is significantly reduced, and the electrical and optical properties of the sputtered film are improved.

[0100] In the preparation method of the doped IZO target in Example 8, microwave sintering technology is used instead of traditional atmospheric high-temperature sintering. Performance test results show that the overall performance of the target and sputtered film is improved. This further illustrates that the microwave sintering technology used in this application can reduce the volatilization of indium oxide and zinc oxide, thereby facilitating the improvement of target density.

[0101] Comparison of Examples 9 and 10 with Example 8 shows that in Example 9, paving zirconium oxide on the setter plate can reduce target shrinkage after high-temperature sintering, thereby improving the stability of the electrical and optical properties of the sputtered film. In contrast, in Example 10, alumina was used instead of zirconium oxide particles. Performance test results show that the overall performance of the target prepared in Example 10 is significantly reduced, further indicating that the IZO target may react with alumina at high temperatures, thereby affecting the overall performance of the target and causing a decrease in the electrical and optical properties of the sputtered film.

[0102] By comparing Comparative Example 1 with Example 1, it can be seen that Comparative Example 1 uses multi-element oxide powders with different specific surface areas. From the performance test results, it can be seen that the comprehensive performance of the target material is significantly reduced, among which the density of the target material is low, which affects the performance of the sputtered film.

[0103] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A doped IZO target for sputtering thin film transistors, characterized in that: The invention comprises multi-component oxide powder, a binder and a plasticizer; the multi-component oxide powder comprises the following raw materials in parts by weight: 86-89.6 parts of indium oxide, 9.5-12.8 parts of zinc oxide, 0.5-1.2 parts of zirconium oxide, and 0.1-0.4 parts of thallium oxide; the specific surface area of ​​the multi-component oxide powder is 8 m 2 / g-20m 2 / g, and the bulk density is 0.91g / cm 3 -1.55g / cm 3 .

2. The doped IZO target for sputtering thin film transistors according to claim 1, characterized in that: The D50 of the multi-component oxide powder is ≤80%.

3. The doped IZO target for sputtering thin film transistors according to claim 1, characterized in that: The mass of the binder is 0.2-1.2% of the mass of the multinary oxide powder, and the mass of the plasticizer is 0.2-1.5% of the mass of the multinary oxide powder.

4. The doped IZO target for sputtering thin film transistors according to claim 1, characterized in that: The binder is one of polyvinyl alcohol, sodium carboxymethyl cellulose, polyvinyl chloride and hydroxypropyl methylcellulose.

5. The doped IZO target for sputtering thin film transistors according to claim 1, characterized in that: The plasticizer is polyethylene glycol.

6. A method for preparing a doped IZO target for sputtering a thin film transistor according to any one of claims 1 to 5, characterized in that: The specific steps include: Preparation of mixed doped IZO powder: Indium oxide, zinc oxide, zirconium oxide, and thallium oxide are mixed in advance, a dispersant is added and ground, a binder and a plasticizer are added and mixed to form a mixed slurry, and the mixed slurry is spray granulated to obtain mixed doped IZO powder; Pressing and molding: The mixed doped IZO powder is pressed and molded by cold isostatic pressing at a pressure of 120-350 MPa to form a target blank; Sintering: First, the target blank is degreased and pre-sintered in sequence, and then the target is sintered at high temperature; Finally, the sintered target material is polished and tested to obtain the doped IZO target material for sputtering thin film transistors.

7. The method for preparing a doped IZO target for sputtering a thin film transistor according to claim 6, characterized in that: The grinding process uses a front-end and back-end mixed grinding method, uses zirconium beads with a diameter of 1.2-1.4 mm, a grinding time of 6-8 hours, and 6-8 cycles of grinding to complete the front-end grinding; After the pre-grinding is completed, the post-grinding begins, using zirconium balls with a diameter of 0.8-1mm. The grinding time is 8-10 hours per cycle, and the grinding process is completed after 8-10 cycles of grinding.

8. The method for preparing a doped IZO target for sputtering a thin film transistor according to claim 6, wherein: The degreasing sintering temperature is 550-700° C., and the degreasing sintering heating rate is 0.8-3.5° C. / min; the pre-sintering temperature is 750-900° C., and the pre-sintering heating rate is 0.4-1.2° C. / min.

9. The method for preparing a doped IZO target for sputtering a thin film transistor according to claim 6, wherein: The high-temperature sintering adopts microwave sintering technology, and the microwave sintering technology uses a microwave sintering furnace for closed sintering. The microwave frequency is 30Ghz-80Ghz, the heating rate is 10.0-25.0°C / min, and the maximum temperature of the microwave sintering is 1050-1200°C.

10. The method for preparing a doped IZO target for sputtering a thin film transistor according to claim 6, wherein: When the target blank is sintered at high temperature, zirconium oxide is laid between the target and the setter in advance.

Images