Igzo ceramic target and method for manufacturing the same

Abstract

The application discloses an IGZO ceramic target material and a preparation method thereof. The method comprises the following steps: performing chemical modification on praseodymium oxide and cerium oxide powders by using triethanolamine chelating agent to form Pr / Ce double rare earth complex; mixing indium oxide, gallium oxide, zinc oxide and modified rare earth powders according to an atomic ratio of In:Ga:Zn:Pr:Ce (40-60):(20-40):(5-15):(0.1-2.5):(0.1-2.5), and adding graphene nanosheets; realizing nanoscale homogenization through ball milling and ultrasonic dispersion; and performing hot-pressing sintering under an inert atmosphere, and performing annealing to control oxygen partial pressure. The obtained target material has high density, low resistivity, excellent carrier concentration and mobility, and is suitable for high-performance thin film transistors.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ceramic target materials, and particularly relates to an IGZO ceramic target material and a preparation method thereof. BACKGROUND

[0002] With the rapid development of display technology and flexible electronic devices, amorphous oxide semiconductor materials, especially indium gallium zinc oxide (IGZO) ceramic targets, have become the key components for the preparation of high-performance thin-film transistors (TFTs) by magnetron sputtering. Since Nomura et al. first reported amorphous IGZO thin-film transistors deposited at room temperature in 2004, the field has undergone significant evolution from basic material synthesis to industrial-scale applications. Early research focused on the amorphous phase stability of IGZO and its potential in transparent electronic devices, with thin films deposited from ceramic targets using radio frequency (RF) or direct current (DC) sputtering techniques to achieve high electron mobility (>10 cm 2 / V·s) and low leakage current characteristics. Subsequently, the preparation method was gradually optimized, including hot-press sintering, sol-gel precursor synthesis, and the assistance of plasma-enhanced chemical vapor deposition, aiming to improve the density and micro-uniformity of the target material. For example, by adjusting the proportion of metal ions in the target material, researchers achieved fine tuning of the thin film band gap and optical transmittance, promoting the commercial application of IGZO in liquid crystal display (LCD) and organic light-emitting diode (OLED) panels. In recent years, with the integration of nanoscale doping and surface modification technologies, the performance of IGZO targets has been further improved, such as the introduction of rare earth elements to stabilize the lattice structure, or the use of multi-layer composite targets to improve ion bombardment response during sputtering. These advances not only reduce the energy consumption of preparation, but also expand the potential of IGZO in the field of flexible display and sensors, making it a mainstream choice for semiconductor materials in the post-silicon era.

[0003] Despite the achievements of IGZO ceramic targets and their preparation methods, the existing technical system still faces some structural challenges, especially the precise regulation of oxygen vacancies (Oxygen Vacancies, Vo), which directly restricts the electrical stability of the target and the overall performance of the sputtered film. In traditional preparation processes such as magnetron sputtering or vacuum hot pressing, the generation of oxygen vacancies mainly depends on atmosphere control (such as oxygen partial pressure) and post-processing (such as annealing), but these methods often have difficulty in achieving fine intervention at the molecular level, resulting in large fluctuations in oxygen vacancy concentration, which in turn leads to non-uniform distribution of carrier concentration. Generally, too high oxygen vacancies will produce shallow donor states, increase the free electron density, but at the same time introduce deep trap defects, causing the decrease of electron mobility and the abnormal increase of resistivity, affecting the on-off ratio and response speed of the film in TFT devices. Conversely, a low oxygen vacancy environment can suppress defect states, but may lead to too low carrier concentration, weakening the conductivity of the film, and amplifying the interference effect of environmental factors (such as humidity or light) on electrical parameters. In addition, the existing doping strategies (such as Ga 3+ inhibit Vo formation) can partially alleviate this problem, but often accompanied by lattice distortion and phase separation risks, further amplifying the instability of carriers, especially in the industrial production of large-size targets (>300mm). These shortcomings not only reduce the reliability and life of IGZO films, but also limit their potential in high-resolution display and high-frequency electronic applications, and new regulation mechanisms are needed to achieve dynamic balance of oxygen vacancies and precise stability of carrier concentration to improve overall electrical properties. SUMMARY

[0004] The present application provides a preparation method of an IGZO ceramic target, the preparation method comprising the following steps: step S1. chemically modifying praseodymium oxide and cerium oxide powders, forming metal-organic complexes by coordination of chelating agents with praseodymium ions and cerium ions, and obtaining modified rare earth powders by centrifugal separation and vacuum drying, wherein Pr 4+ and Ce 4+10wt% to 20wt% of the total praseodymium ions and the total cerium ions; step S2. In oxide, gallium oxide, zinc oxide, and the modified rare earth powder are mixed in a preset ratio to form a precursor mixture, wherein the preset ratio is In:Ga:Zn:Pr:Ce atomic ratio is (40-60):(20-40):(5-15):(0.1-2.5):(0.1-2.5), the purity of the indium oxide, gallium oxide, zinc oxide, praseodymium oxide, and cerium oxide powder is ≥99.99%; step S3. The precursor mixture is uniformly nano-sized by ball milling and ultrasonic dispersion; step S4. The precursor mixture is subjected to hot-press sintering under an inert atmosphere, the temperature is controlled at 800-1200℃, the pressure is 20-50MPa, and subsequent annealing treatment is performed to control the oxygen partial pressure, to obtain the IGZO ceramic target material.

[0005] It should be noted that in step S1, the praseodymium oxide and cerium oxide form metal-organic complexes through chelating agents, and the high valence characteristics (10-20wt%) of Pr 4+ and Ce 4+ are used to control the surface activity of the powder, enhance the uniformity of subsequent mixing, and inhibit the disordered generation of oxygen vacancies. Step S2 uses the accurate In:Ga:Zn:Pr:Ce atomic ratio to optimize the carrier concentration and electron mobility of the target material by using the oxygen vacancy inhibition effect of gallium and the lattice stability effect of rare earth elements. Step S3 ensures uniform distribution of nano-sized particles through ball milling and ultrasonic dispersion, reducing grain boundary defects. Step S4 promotes the formation of amorphous or c-axis oriented crystal phases through segmented temperature control and low oxygen partial pressure environment, reducing deep trap defect density, thereby significantly improving the electrical stability, mechanical strength of the target material, and uniformity of the sputtered thin film, overcoming the problem of resistivity fluctuation caused by the difficulty of controlling oxygen defects in the prior art.

[0006] As a preferred technical solution of the method for preparing an IGZO ceramic target material, the chemical modification step comprises: stepwise adding praseodymium oxide and cerium oxide powder in a mass ratio of 1:1 to 2:1 in a chelating agent solution containing 0.05-0.2mol / L triethanolamine, first reacting at 40-60℃ for 1-2 hours to form a praseodymium-organic complex, then increasing the temperature to 60-80℃ for 1-2 hours to introduce cerium ions to form a double rare earth complex; at the same time, adding 0.1wt%-0.5wt% of polyethylene glycol surfactant, using low-frequency ultrasonic waves with a frequency of 15-25kHz and a power of 100-300W.

[0007] It should be noted that in the solution containing 0.05-0.2 mol / L TEA, praseodymium oxide and cerium oxide powders are added step by step in a mass ratio of 1:1 to 2:1, first reacted at 40-60°C for 1-2 hours, and TEA is coordinated with Pr 3+ / Pr 4+ to form a praseodymium-organic complex, Pr 4+ The high valence state (accounting for 10-20 wt%) induces local lattice distortion, enhances the surface chemical activity of the powder, and inhibits the disordered generation of oxygen vacancies; then, the temperature is raised to 60-80°C for 1-2 hours to introduce Ce 3+ / Ce 4+ to form a double rare earth complex, and the multi-valence redox characteristics of Ce 4+ synergize with Pr 4+ to dynamically regulate the electronic structure of the powder through electron transfer and oxygen vacancy capture mechanisms, significantly reducing the deep trap defect density. Adding 0.1-0.5 wt% polyethylene glycol (PEG) surfactant further improves the dispersibility of the powder through steric hindrance effects, and 15-25 kHz, 100-300 W low-frequency ultrasound generates local high temperature and pressure through acoustic cavitation effects, promoting the uniform coordination of TEA with Pr and Ce ions, and refining the particle size. The synergistic effect of Pr and Ce optimizes the chemical uniformity and reactivity of the modified rare earth powder through the lattice stability of Pr 4+ and the oxygen defect regulation ability of Ce 4+ , providing a stable precursor for subsequent IGZO target material preparation.

[0008] As a preferred technical solution of the method for preparing an IGZO ceramic target, in the chemical modification step, the pH value of the solution is dynamically regulated, first maintained at pH 4.0 to 5.0 to form a praseodymium-organic complex, and then adjusted to pH 5.5 to 6.5 to introduce cerium ions.

[0009] It should be noted that in the acidic environment of pH 4.0 to 5.0, the amine and hydroxyl groups of TEA are preferentially coordinated with Pr 3+ / Pr 4+ to form a stable praseodymium-organic complex, and this pH range is conducive to the stability of the high valence state of Pr 4+ , inducing local lattice stress, reducing the surface energy of the powder, and inhibiting particle agglomeration. Subsequently, by adjusting the pH value to 5.5 to 6.5, the solution environment becomes more suitable for the coordination reaction of Ce 3+ / Ce 4+ , and TEA is further coordinated with Ce ions to form a double rare earth complex, and the multi-valence characteristics of Ce 4+ are dynamically balanced through redox, synergizing with Pr 4+The generation of oxygen vacancies is regulated, and deep trap defects are reduced. This pH gradient regulation strategy precisely matches the coordination chemical properties of rare earth ions, optimizes the structural stability of the complex, and enhances the chemical uniformity and reactivity of the powder, providing a high-quality precursor for subsequent IGZO target material preparation.

[0010] As a preferred technical solution of the preparation method of the IGZO ceramic target material, the centrifugal separation speed is 5000 rpm to 8000 rpm, and the time is 10 minutes to 15 minutes; the vacuum drying temperature is 60°C to 80°C, the vacuum degree is 0.01 Pa, and the time is 6 hours to 12 hours.

[0011] It should be noted that by efficiently separating and removing the solvent, the purity and uniformity of the modified rare earth powder are ensured, providing a high-quality precursor for the subsequent preparation of the IGZO ceramic target material.

[0012] As a preferred technical solution of the preparation method of the IGZO ceramic target material, the ball milling step uses zirconia balls as the grinding medium, the ball-to-material ratio is 10:1 to 20:1, the ball milling time is 4 hours to 8 hours, and the ultrasonic dispersion is combined, the frequency is 20 kHz to 40 kHz, the power is 200 W to 400 W, and the time is 1 hour to 2 hours.

[0013] It should be noted that by mechanical grinding and acoustic cavitation effect, the precursor mixture is uniformly nano-sized, reducing particle agglomeration and grain boundary defects, providing a basis for densification and performance optimization of the IGZO ceramic target material.

[0014] As a preferred technical solution of the preparation method of the IGZO ceramic target material, the hot-pressing sintering process adopts a stepwise heating strategy, the initial temperature is 600°C to 800°C, maintained for 1 hour to 2 hours, the middle temperature is 900°C to 1100°C, maintained for 2 hours to 4 hours, and the final temperature is 1100°C to 1200°C, maintained for 1 hour to 3 hours.

[0015] It should be noted that by gradually controlling the temperature, the uniform diffusion and combination of precursor particles are promoted, the density and microstructure stability of the IGZO ceramic target material are optimized, and thermal stress defects are reduced.

[0016] As a preferred technical solution of the preparation method of the IGZO ceramic target material, the annealing treatment is carried out in a nitrogen or argon atmosphere, the oxygen partial pressure is controlled at 0.001 Pa to 0.1 Pa, the annealing temperature is 600°C to 900°C, and the time is 2 hours to 6 hours.

[0017] It should be noted that by precisely controlling the oxygen partial pressure and temperature, the oxygen defect distribution and crystal structure of the IGZO ceramic target material are optimized, and the electrical performance and sputtering stability are improved.

[0018] As a preferred technical solution of the preparation method of the IGZO ceramic target, 0.01wt%-0.1wt% graphene nanosheets are added into the precursor mixture as an auxiliary dopant.

[0019] It should be noted that the addition of graphene nanosheets forms a uniformly dispersed conductive network in the mixture through its high specific surface area, effectively improves the interface contact between the precursor particles, promotes the rearrangement and diffusion of the particles during hot-pressing sintering, and reduces the grain boundary resistance and defect density. At the same time, the carbon atoms of graphene form weak chemical bonds with the oxygen atoms in IGZO, which helps to control the oxygen vacancy concentration, thereby stabilizing the carrier concentration and improving the electron mobility.

[0020] In addition, the IGZO ceramic target prepared by the above preparation method.

[0021] The beneficial effects of the present application are that by introducing Pr / Ce double-rare earth complex chelated by triethanolamine and ultrasonic dispersion treatment into the IGZO ceramic target, and combining with graphene nanosheet auxiliary doping, not only the surface activity and dispersibility of the powder are effectively improved, and the disordered generation of oxygen vacancies is inhibited, but also the precise control of the carrier concentration is realized by the lattice stabilization of Pr 4+ and the oxygen defect regulation ability of Ce 4+ , thereby significantly improving the density and microstructure uniformity of the target; at the same time, the conductive network of graphene reduces the grain boundary defects and resistivity, further enhancing the electron mobility. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 It is a spectrum analysis diagram of Pr / Ce-complex+PEG in Example 1 of the present application. DETAILED DESCRIPTION

[0023] In order to make the above-mentioned objects, features and advantages of the present application more apparent and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the description of the embodiments.

[0024] In the following description, many specific details are set forth in order to provide a thorough understanding of the present application. However, the present application can be practiced in other manners different from those described herein, and those skilled in the art can make similar generalizations without departing from the scope of the present application, so the present application is not limited to the specific embodiments disclosed below.

[0025] Secondly, the "one embodiment" or "embodiment" referred to herein means that the specific features, structures or characteristics can be included in at least one implementation of the present application. "In one embodiment" appearing in different places in the specification does not mean the same embodiment, nor is it an embodiment that is separate or selectively excluded from other embodiments.

[0026] Embodiment

[0027] Embodiment 1

[0028] The embodiment provides an IGZO ceramic target and a preparation method thereof, comprising the following steps:

[0029] Step S1: chemical modification: take praseodymium oxide (Pr6O 11 ) and cerium oxide (CeO2) powder (purity ≥ 99.99%) and weigh 50 g of each with a mass ratio of 1:1, and add them into 500 mL of an aqueous solution containing 0.05 mol / L triethanolamine (TEA). First, stir the solution at 40°C for 1 hour, keep the pH of the solution at 4.0, and form a praseodymium-organic complex by coordination of TEA and Pr 3+ / Pr 4+ , wherein Pr 4+ accounts for 15wt% of the total praseodymium ions. Then, increase the temperature to 60°C, react for 1 hour, adjust the pH to 5.5, and introduce Ce 3+ / Ce 4+ to form a double rare earth complex, wherein Ce 4+ accounts for 10wt% of the total cerium ions. Add 0.1wt% polyethylene glycol (PEG, molecular weight 2000) as a surfactant during the reaction, and use low-frequency ultrasonic waves (frequency 15 kHz, power 100 W) to assist dispersion for 30 minutes. Centrifugal separation is performed at 5000 rpm for 10 minutes, the precipitate is collected, and drying is performed at 60°C under a vacuum degree of 0.01 Pa for 6 hours to obtain modified rare earth powder.

[0030] Step S2: precursor mixing: mix indium oxide (In2O3, purity ≥ 99.99%), gallium oxide (Ga2O3, purity ≥ 99.99%), zinc oxide (ZnO, purity ≥ 99.99%), and the modified rare earth powder according to an atomic ratio of In:Ga:Zn:Pr:Ce of 40:20:5:0.1:0.1, with a total mass of 100 g, and add 0.01wt% graphene nanosheets (thickness 1-3 nm, specific surface area >1000 m 2 / g) as an auxiliary dopant, and pre-mix in a planetary ball mill for 30 minutes to form a precursor mixture.

[0031] Step S3: nanoscale homogenization: use zirconium oxide balls (diameter 5 mm) as grinding media, with a ball-to-material ratio of 10:1, and ball mill in a planetary ball mill at 300 rpm for 4 hours. Then, place the mixture in deionized water and treat it with ultrasonic dispersion (frequency 20 kHz, power 200 W) for 1 hour to ensure that the particle size is uniformly distributed in the range of 50-100 nm.

[0032] Step S4: hot-pressing sintering and annealing: the precursor mixture is placed in a hot-pressing furnace for hot-pressing sintering under an argon atmosphere, using a stepwise temperature increase: 600°C for 1 hour, 900°C for 2 hours, 1100°C for 1 hour, and a pressure of 20 MPa. After sintering, annealing is performed under a nitrogen atmosphere at an oxygen partial pressure of 0.001 Pa and a temperature of 600°C for 2 hours, to obtain an IGZO ceramic target.

[0033] Example 2

[0034] This example provides an IGZO ceramic target and a method for preparing the same, comprising the following steps:

[0035] Step S1: chemical modification: take praseodymium oxide (Pr6O 11 ) and cerium oxide (CeO2) powders (purity ≥ 99.99%) and weigh 60 g and 40 g of the powders in a mass ratio of 1.5:1, and add them to 600 mL of an aqueous solution containing 0.1 mol / L TEA. First, stir the solution at 50°C for 1.5 hours to form a praseodymium-organic complex, Pr 4+ , which accounts for 18wt% of the total praseodymium ions. Then, increase the temperature to 70°C, react for 1.5 hours, adjust the pH to 6.0, and introduce Ce 3+ / Ce 4+ to form a double rare earth complex, Ce 4+ , which accounts for 15wt% of the total cerium ions. Add 0.3wt% PEG (molecular weight 4000) and use ultrasonic waves (frequency 20 kHz, power 200 W) to assist dispersion for 45 minutes. Centrifugal separation is performed at 6000 rpm for 12 minutes, and drying is performed at 70°C under a vacuum degree of 0.01 Pa for 8 hours, to obtain modified rare earth powders.

[0036] Step S2: precursor mixing: mix indium oxide (In2O3), gallium oxide (Ga2O3), zinc oxide (ZnO), and the modified rare earth powders in an atomic ratio of In:Ga:Zn:Pr:Ce of 50:30:10:1:1, with a total mass of 150 g, and add 0.05wt% graphene nanosheets, and pre-mix for 45 minutes to form a precursor mixture.

[0037] Step S3: nanoscale homogenization: use zirconia balls (diameter 3 mm) and ball-to-material ratio of 15:1, and ball mill for 6 hours (400 rpm). Then, use ultrasonic dispersion (frequency 30 kHz, power 300 W) to treat for 1.5 hours, and the particle size distribution is 80-150 nm.

[0038] Step S4: Hot pressing sintering and annealing: Hot pressing sintering was performed under an argon atmosphere. The heating strategy was as follows: 700℃ for 1.5 hours, 1000℃ for 3 hours, and 1150℃ for 2 hours, with a pressure of 35 MPa. Annealing was performed under an argon atmosphere with an oxygen partial pressure of 0.05 Pa, a temperature of 750℃, and a holding time of 4 hours to obtain the IGZO ceramic target.

[0039] Example 3

[0040] This embodiment provides an IGZO ceramic target and its preparation method, including the following steps:

[0041] Step S1: Chemical modification: Take praseodymium oxide (Pr6O) 11 80 g and 40 g of cerium oxide (CeO2) powder (purity ≥99.99%) were weighed at a mass ratio of 2:1 and added to 800 mL of an aqueous solution containing 0.15 mol / L LTEA. The mixture was reacted at 55 °C for 2 hours at pH 4.8 to form a praseodymium-organic complex. 4+ The total praseodymium ion content was 20 wt%. The temperature was raised to 75°C, and the reaction was carried out for 2 hours. The pH was adjusted to 6.2, and Ce was introduced. 3+ / Ce 4+ Ce 4+ The total cerium ion content was 18 wt%. 0.4 wt% PEG (molecular weight 6000) was added, and the mixture was dispersed using ultrasonication (frequency 22 kHz, power 250 W) for 1 hour. The mixture was then centrifuged at 7000 rpm for 15 minutes and dried at 75°C under a vacuum of 0.01 Pa for 10 hours to obtain modified rare earth powder.

[0042] Step S2: Precursor mixing: Indium oxide (In2O3), gallium oxide (Ga2O3), zinc oxide (ZnO) and modified rare earth powder are mixed in an atomic ratio of In:Ga:Zn:Pr:Ce of 55:35:12:2:2, with a total mass of 200g. 0.08wt% graphene nanosheets are added and premixed for 1 hour to form a precursor mixture.

[0043] Step S3: Nanoscale homogenization: Using zirconia balls (2 mm in diameter), with a ball-to-material ratio of 18:1, ball milling was performed for 7 hours (350 rpm). Ultrasonic dispersion (frequency 35 kHz, power 350 W) was then performed for 2 hours, resulting in a particle size distribution of 100-180 nm.

[0044] Step S4: Hot pressing sintering and annealing: Hot pressing sintering was performed under a nitrogen atmosphere. The heating strategy was as follows: 750℃ for 2 hours, 1050℃ for 3.5 hours, and 1200℃ for 3 hours, with a pressure of 45 MPa. Annealing was performed under a nitrogen atmosphere with an oxygen partial pressure of 0.08 Pa, a temperature of 850℃, and a holding time of 5 hours to obtain the IGZO ceramic target.

[0045] Example 4

[0046] This embodiment provides an IGZO ceramic target and its preparation method, including the following steps:

[0047] Step S1: Chemical modification: Take praseodymium oxide (Pr6O) 11 100g each of praseodymium oxide (CeO2) powder (purity ≥99.99%) and cerium oxide (CeO2) powder (mass ratio 1:1) were weighed and added to 1000mL of an aqueous solution containing 0.2mol / L LTEA. The mixture was reacted at 60℃ for 2 hours at pH 5.0 to form a praseodymium-organic complex. 4+ The total praseodymium ion content was 20 wt%. The temperature was raised to 80°C, and the reaction was carried out for 2 hours. The pH was adjusted to 6.5, and Ce was introduced. 3+ / Ce 4+ Ce 4+ The total cerium ion content was 20 wt%. 0.5 wt% PEG (molecular weight 8000) was added, and the mixture was dispersed using ultrasonication (frequency 25 kHz, power 300 W) for 1 hour. The mixture was then centrifuged at 8000 rpm for 15 minutes and dried at 80°C under a vacuum of 0.01 Pa for 12 hours to obtain modified rare earth powder.

[0048] Step S2: Precursor mixing: Indium oxide (In2O3), gallium oxide (Ga2O3), zinc oxide (ZnO) and modified rare earth powder are mixed in an atomic ratio of In:Ga:Zn:Pr:Ce of 60:40:15:2.5:2.5, with a total mass of 250g. 0.1wt% graphene nanosheets are added and premixed for 1.5 hours to form a precursor mixture.

[0049] Step S3: Nanoscale homogenization: Using zirconia balls (1 mm in diameter), with a ball-to-material ratio of 20:1, ball milling was performed for 8 hours (400 rpm). Ultrasonic dispersion (frequency 40 kHz, power 400 W) was then performed for 2 hours, resulting in a particle size distribution of 120-200 nm.

[0050] Step S4: Hot pressing sintering and annealing: Hot pressing sintering was performed under an argon atmosphere. The heating strategy was as follows: 800℃ for 2 hours, 1100℃ for 4 hours, and 1200℃ for 3 hours, with a pressure of 50 MPa. Annealing was performed under an argon atmosphere with an oxygen partial pressure of 0.1 Pa, a temperature of 900℃, and a holding time of 6 hours to obtain the IGZO ceramic target.

[0051] Comparison Example

[0052] Compare with Example 1

[0053] Compared with Example 1, in this Comparative Example 1, only praseodymium oxide was used for chemical modification in step S1, omitting cerium oxide, and maintaining the total rare earth content consistently.

[0054] Compare with Example 2

[0055] This comparative example 2 is compared with example 1, in step S1, only using cerium oxide for chemical modification, omitting praseodymium oxide, keeping the total rare earth content consistent.

[0056] Comparative example 3

[0057] This comparative example 3 is compared with example 1, in step S1, omitting the chemical modification process of praseodymium oxide and cerium oxide powder (i.e. not using triethanolamine chelating agent, dynamic pH control, low-frequency ultrasonic and polyethylene glycol surfactant), directly using the original praseodymium oxide and cerium oxide powder.

[0058] Comparative example 4

[0059] This comparative example 3 is compared with example 1, omitting the addition of 0.01wt% graphene nanosheet as an auxiliary dopant.

[0060] Performance test method

[0061] 1. Densification: The densification of the target material is measured by the Archimedes method. A high-precision electronic balance (accuracy 0.0001g) is used to measure the dry weight, wet weight and suspended weight of the sample. The sample is placed in a constant temperature tank of deionized water to ensure stable water temperature. The sample surface needs to be cleaned and dried to avoid air bubble interference, and the test is repeated multiple times to take the average value.

[0062] 2. Resistivity: The resistivity of the target material is measured using the four-probe method. A four-probe tester (such as Keithley 2400 source meter) is used to apply a constant current to the sample surface and measure the voltage between the two probes. The test is carried out at room temperature (25°C), and the sample surface needs to be polished and cleaned to remove the oxide layer to ensure accurate results.

[0063] 3. Carrier concentration and mobility: The carrier concentration and mobility of the target material are evaluated by the Hall effect test. A Hall effect test system (such as Lakeshore 8400 series) is used to apply a current under a constant magnetic field of 0.5-1T, and the Hall voltage of the sample is measured. The sample needs to be cut into a size of 10mm×10mm×1mm, the surface is polished and cleaned to remove impurities, and the test is carried out in vacuum or inert atmosphere (such as nitrogen or argon) to avoid oxygen adsorption interference. The test is repeated multiple times to take the average value to ensure data reliability.

[0064] Table 1

[0065]

[0066] Figure 1The infrared (IR) spectra of three species in the chemical modification process in Step S1 of Example 1 are shown, including pure triethanolamine (TEA, blue curve as a reference), praseodymium-organic complex (Pr-complex, 40°C, pH 4.0, red curve), and praseodymium / cerium double rare earth complex plus polyethylene glycol (Pr / Ce-complex+PEG, 60°C, pH 5.5, orange curve). As can be seen from the figure, the TEA reference spectrum shows a wide and strong O-H stretching vibration peak (intensity about 0.8-1.0) near 3300 cm -1 , reflecting the hydrogen bonding of hydroxyl groups; there is a C-H stretching vibration peak (intensity about 0.6) at 2950 cm -1 , corresponding to the alkyl chain; there is a C-H bending vibration (intensity about 0.4-0.5) near 1400 cm -1 ; there is a C-N stretching vibration peak (intensity about 0.7-0.8) at 1300 cm -1 , which is a typical tertiary amine characteristic; there is a C-O stretching vibration peak (intensity about 0.9-1.0) at 1100 cm -1 , which is the strongest peak. These peaks are sharp in shape, with a flat baseline and less noise. In contrast, the Pr-complex spectrum shows that the main functional group peaks are red-shifted to lower wave numbers, with the O-H peak shifted to about 3270 cm -1 (red shift about 30 cm -1 ), slightly increased peak width (about 65 cm -1 ), and slightly reduced intensity (about 0.85), indicating that Pr 3+ / Pr 4+ coordination weakens the O-H bond strength and enhances hydrogen bonding interference; the C-N peak is shifted to about 1275 cm -1 (red shift about 25 cm -1 ), with an intensity of about 0.7, reflecting the change in electron density caused by nitrogen atom coordination; the C-O peak is shifted to about 1065 cm -1 (red shift about 35 cm -1 ), with an intensity of about 0.85, slightly widened peak shape (about 26 cm -1 ), and slightly increased overall spectral noise, with impurity peaks appearing near 2000-2500 cm -1 and 1500 cm -1 , which may be caused by by-products due to incomplete coordination under the conditions of 40°C and pH 4.0. The Pr / Ce-complex+PEG spectrum further enhances the red shift effect, with the O-H peak shifted to about 3265 cm -1 (red shift about 35 cm -1 ), with a peak width of about 75 cm -1 , and an intensity of about 0.8, showing that Ce 3+ / Ce 4+ addition enhances intermolecular interactions; the C-N peak is shifted to about 1265 cm-1 (red shift about 35 cm -1 ), intensity about 0.65; C-O peak shifted to about 1060 cm -1 (red shift about 40 cm -1 ), intensity about 0.8; in addition, a weak PEG C-O-C asymmetric stretching peak (intensity about 0.2-0.3, shifted to about 1130 cm -1 ) appeared near 1150 cm -1 , and a PEG end hydroxyl O-H peak (intensity about 0.15, shifted to about 3415 cm -1 ) near 3450 cm -1 , the appearance of these peaks confirmed the steric hindrance and dispersion of 0.1 wt% PEG; the overall baseline of the spectrum slightly drifted, and more noise and impurity peaks (e.g. in 2800-3000 cm -1 and 1200-1400 cm -1 ) appeared, possibly due to the dynamic coordination process under the assistance of 60 °C temperature rise and ultrasound (15 kHz, 100 W). These red shifts, peak width increase and intensity attenuation collectively verified the coordination mechanism of rare earth ions with TEA, and the synergistic effect of Pr 4+ and Ce 4+ optimized the complex structure through electron transfer and lattice stress, while PEG improved the powder dispersibility and reduced agglomeration, providing a uniform modified rare earth powder basis for subsequent IGZO target material preparation.

[0067] It can be seen from Examples 1 to 4 and Table 1 that the experimental data of Examples 1 to 4 range from: density 6.10-6.25 g / cm 3 , resistivity 1.90-2.50 x 10 -4 Ω·cm, carrier concentration 1.80-2.10 x 1020cm-3, mobility 12.0-13.5 cm2 / V·s.

[0068] It can be seen from Examples 1, Comparative Examples 1 and 2, and Table 1 that the performance of Example 1 is significantly better than that of Comparative Examples 1 and 2: the density is 6.10 g / cm 3 , higher than 5.95 g / cm 3 of Comparative Example 1 and 5.90 g / cm 3 of Comparative Example 2; the resistivity is 2.50 x 10 -4 Ω·cm, lower than 3.50 x 10 -4 Ω·cm of Comparative Example 1 and 3.70 x 10 -4 Ω·cm of Comparative Example 2; the carrier concentration is 1.80 x 10 20 cm -3 , higher than 1.50 x 10 20 cm-3 and 1.45 x 10 20 cm -3 ; the mobility is 12.0 cm 2 / V·s, higher than 10.0 cm 2 / V·s of Comparative Example 1 and 9.8 cm 2 / V·s of Comparative Example 2. The performance of Example 1 is improved by 5%-20%, reflecting the advantages of double rare earth doping. Example 1 forms a Pr / Ce double rare earth complex through triethanolamine chelating agent and ultrasonic assistance, Pr 4+ and Ce 4+ enhance the powder surface activity, inhibit the generation of oxygen vacancy disorder, improve the density and conductivity; the In:Ga:Zn:Pr:Ce ratio (40:20:5:0.1:0.1) combines with graphene to optimize the lattice, reduce deep trap defects, and improve the carrier and mobility. Comparative Example 1 (only Pr) and Comparative Example 2 (only Ce) lack synergistic effect, oxygen defect regulation is insufficient, and lattice distortion or particle agglomeration leads to performance decline. Pr 4+ stabilizes the lattice, Ce 4+ dynamically regulates oxygen vacancies, both of which optimize the electronic structure through electron transfer coupling, reduce defect scattering, significantly improve the electrical performance, overcome the limitations of single doping, and enhance the application potential of the target material in sputtered thin films.

[0069] As can be seen from Example 1, Comparative Example 3 and Table 1, the performance of Example 1 is significantly better than that of Comparative Example 3: the density is 6.10 g / cm 3 , higher than 5.80 g / cm 3 of Comparative Example 3; the resistivity is 2.50 x 10 -4 Ω·cm, lower than 4.00 x 10 -4 Ω·cm of Comparative Example 3; the carrier concentration is 1.80 x 10 20 cm -3 , higher than 1.30 x 10 20 cm -3 of Comparative Example 3; the mobility is 12.0 cm 2 / V·s, higher than 9.0 cm 2 / V·s of Comparative Example 3, with a performance improvement of about 10%-30%. Example 1 forms a Pr / Ce double rare earth complex through the chemical modification of step S1, Pr 4+ and Ce 4+The enhanced powder surface activity, the inhibition of oxygen vacancy disorder generation, the promotion of uniform particle diffusion in hot-press sintering, the reduction of grain boundary defects, the improvement of density and conductivity; In:Ga:Zn:Pr:Ce ratio (40:20:5:0.1:0.1) and 0.01wt% graphene doping optimize the lattice, reduce deep trap defects, improve carrier concentration and mobility. Example 3 omits chemical modification and directly uses original Pr6O 11 and CeO2 powder, resulting in serious particle agglomeration, low surface activity, large oxygen vacancy fluctuation, increased grain boundary defects and deep trap defects during sintering, resulting in reduced density, increased resistivity, and significantly reduced carrier and mobility.

[0070] As can be seen from Example 1, Comparative Example 4 and Table 1, the performance of Example 1 is significantly better than that of Comparative Example 4: the density is 6.10 g / cm 3 , higher than 6.00 g / cm 3 of Comparative Example 4; the resistivity is 2.50×10 -4 Ω·cm, lower than 3.00 × 10 -4 Ω·cm of Comparative Example 4; the carrier concentration is 1.80×10 20 cm -3 , higher than 1.60×10 20 cm -3 of Comparative Example 4; the mobility is 12.0 cm 2 / V·s, higher than 10.5 cm 2 / V·s of Comparative Example 4, with a performance improvement of about 5%-15%. Example 1 adds 0.01 wt% graphene nanoplatelets as an auxiliary dopant in the precursor mixture, while Comparative Example 4 omits this step, resulting in performance differences; the high specific surface area of graphene forms a uniform conductive network, promotes particle rearrangement and diffusion during hot-press sintering (600-1100℃, 20 MPa), reduces grain boundary resistance and defect density, and at the same time forms weak chemical bonds with oxygen atoms in IGZO, auxiliary control of oxygen vacancy concentration, stabilizing carrier concentration and improving electron mobility, thereby improving density, reducing resistivity, increasing carrier concentration and mobility. The lack of graphene conductive network and interface optimization in Comparative Example 4 results in weak particle contact, insufficient oxygen vacancy regulation, and increased grain boundary defects, resulting in overall electrical performance.

[0071] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent replacements to some technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing an IGZO ceramic target, characterized in that, The preparation method includes the following steps: Step S1. Chemically modifying praseodymium oxide and cerium oxide powders, forming a metal-organic complex through the coordination of praseodymium ions and cerium ions with a chelating agent, and obtaining modified rare earth powder by centrifugation and vacuum drying, wherein Pr 4+ and Ce 4+ Each of the praseodymium ions and cerium ions accounts for 10wt% to 20wt% of the total praseodymium ions and cerium ions, respectively; Step S2. Indium oxide, gallium oxide, zinc oxide and the modified rare earth powder are mixed in a preset ratio to form a precursor mixture, wherein the preset ratio is an atomic ratio of In:Ga:Zn:Pr:Ce of (40-60):(20-40):(5-15):(0.1-2.5):(0.1-2.5), and the purity of the indium oxide, gallium oxide, zinc oxide, praseodymium oxide and cerium oxide powder is ≥99.99%; Step S3. The precursor mixture is homogenized at the nanoscale by ball milling and ultrasonic dispersion; Step S4. The precursor mixture is hot-pressed and sintered in an inert atmosphere, with the temperature controlled at 800℃ to 1200℃ and the pressure at 20MPa to 50MPa, and then subjected to subsequent annealing treatment to regulate the oxygen partial pressure, to obtain the IGZO ceramic target material; The chemical modification steps include: adding praseodymium oxide and cerium oxide powder in steps at a mass ratio of 1:1 to 2:1 to a chelating agent solution containing 0.05 mol / L to 0.2 mol / L triethanolamine; first reacting at 40°C to 60°C for 1 to 2 hours to form a praseodymium-organic complex; then heating to 60°C to 80°C and reacting for 1 to 2 hours to introduce cerium ions to form a dual rare earth complex; simultaneously adding 0.1 wt% to 0.5 wt% polyethylene glycol surfactant; and using low-frequency ultrasound with a frequency of 15 kHz to 25 kHz and a power of 100 W to 300 W.

2. The method for preparing the IGZO ceramic target according to claim 1, characterized in that, In the chemical modification step, the pH value of the solution is dynamically controlled. First, the pH is maintained at 4.0 to 5.0 to form a praseodymium-organic complex, and then the pH is adjusted to 5.5 to 6.5 to introduce cerium ions.

3. The method for preparing the IGZO ceramic target according to claim 1, characterized in that, The centrifugation speed is 5000 rpm to 8000 rpm, and the time is 10 minutes to 15 minutes; the vacuum drying temperature is 60°C to 80°C, the vacuum degree is 0.01 Pa, and the time is 6 hours to 12 hours.

4. The method for preparing the IGZO ceramic target according to claim 1, characterized in that, The ball milling step uses zirconia balls as the grinding medium, with a ball-to-material ratio of 10:1 to 20:1, a milling time of 4 to 8 hours, and is combined with ultrasonic dispersion at a frequency of 20 kHz to 40 kHz, a power of 200 W to 400 W, and a time of 1 to 2 hours.

5. The method for preparing the IGZO ceramic target according to claim 1, characterized in that, The hot pressing sintering process adopts a segmented heating strategy: the initial temperature is 600℃ to 800℃ and held for 1 to 2 hours, the middle temperature is 900℃ to 1100℃ and held for 2 to 4 hours, and the final temperature is 1100℃ to 1200℃ and held for 1 to 3 hours.

6. The method for preparing the IGZO ceramic target according to claim 1, characterized in that, The annealing process is carried out in a nitrogen or argon atmosphere, with the oxygen partial pressure controlled at 0.001 Pa to 0.1 Pa, the annealing temperature at 600°C to 900°C, and the time at 2 to 6 hours.

7. The method for preparing the IGZO ceramic target according to claim 1, characterized in that, The precursor mixture contains 0.01 wt% to 0.1 wt% of graphene nanosheets as an auxiliary dopant.

8. An IGZO ceramic target prepared by any one of the preparation methods described in claims 1 to 7.

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