Oxide semiconductor target material powder and preparation method thereof, semiconductor target material, oxide semiconductor thin film and thin film transistor

Abstract

The invention provides oxide semiconductor target material powder and a preparation method thereof, a semiconductor target material, an oxide semiconductor thin film and a thin film transistor, and belongs to the technical field of semiconductor materials and devices and microelectronics. Trivalent and tetravalent Tb ions in the oxide semiconductor target material powder provided by the invention can effectively relax photon-generated carriers, and after the oxide semiconductor target material powder is prepared into an oxide semiconductor film, the Tb ions are used as relaxation channels and recombination centers of photo-generated electrons; the ionization of deep energy level defects (mainly neutral oxygen vacancies near valence band tops) in the oxide semiconductor thin film under NBIS is inhibited, so that the NBIS stability of the thin film transistor is improved, the problem of threshold voltage negative drift of the thin film transistor is solved, impurities or crystal field splitting energy level defects cannot be introduced into Tb ions, electron transport is not affected, and the performance of the thin film transistor is improved. A TFT having good NBIS stability and high mobility is achieved.

Description

Technical Field

[0001] This invention relates to the fields of semiconductor materials and devices and microelectronics, and particularly to an oxide semiconductor target powder and its preparation method, as well as semiconductor targets, oxide semiconductor thin films and thin film transistors. Background Technology

[0002] Thin-film transistors (TFTs), as core components of display drivers, have always attracted widespread attention. Among the currently commercially available backplane driving technologies, amorphous silicon TFTs have low field-effect mobility, making them unsuitable for the demands of new display drivers. The production of low-temperature polycrystalline silicon TFTs requires expensive crystallization equipment and faces significant challenges in large-area production. Oxide TFTs, on the other hand, possess high mobility, excellent large-area uniformity, and extremely low transient current, providing support for new high-resolution, low-power display technologies.

[0003] In traditional InGaZnO TFTs, a large amount of Ga is required to suppress carrier concentration within the semiconductor and adjust the threshold voltage. However, due to the significant difference in radii between Ga and In ions, the addition of a large amount of Ga affects the overlap of the 5s electron orbitals of In ions, resulting in a severe reduction in TFT carrier mobility. More importantly, oxide TFTs exhibit severe threshold voltage drift and even increased subthreshold swing under continuous illumination and negative gate bias stress (NBIS), and these phenomena cannot be recovered for several days after the bias stress is removed. This directly increases the design difficulty of the compensation circuit in the TFT driver backplane, increasing the manufacturing cost of AMOLED displays. Therefore, improving the carrier mobility and NBIS stability of oxide TFTs has become an urgent problem to be solved. Summary of the Invention

[0004] The purpose of this invention is to provide an oxide semiconductor target powder and its preparation method, as well as a semiconductor target, an oxide semiconductor thin film, and a thin film transistor. The oxide semiconductor target powder provided by this invention can yield a thin film transistor with both high mobility and high NBIS stability.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides an oxide semiconductor target powder, wherein the chemical structure of the oxide semiconductor target powder is In. α Zn β Sn γ Tb δ O ε , among them, 0.3≤α≤0.9, 0.01≤β≤0.3, 0.01≤γ≤0.3, 0.01≤δ≤0.3, α+β+γ+δ=1, 1≤ε≤1.8.

[0006] Preferably, the molar ratio of α, β, γ and δ is 12:3:1:1.

[0007] This invention provides a method for preparing the oxide semiconductor target powder described in the above technical solution, comprising the following steps: (1) Mix indium salt solution, zinc salt solution, tin salt solution and terbium salt solution, and then add ammonia water to carry out a co-precipitation reaction to obtain precursor powder; (2) The precursor powder obtained in step (1) is calcined to obtain oxide semiconductor target powder.

[0008] Preferably, the calcination temperature in step (2) is 1100~1300℃ and the calcination time is 2~5h.

[0009] The present invention provides a semiconductor target material, which is prepared from the oxide semiconductor target powder described in the above technical solution or the oxide semiconductor target powder prepared by the preparation method described in the above technical solution.

[0010] Preferably, the method for preparing the semiconductor target includes: Oxide semiconductor target powder is granulated to obtain powder particles, then the powder particles are pressed into shape to obtain a blank, and finally the blank is sintered in two stages to obtain a semiconductor target. or, Oxide semiconductor target powder is granulated to obtain powder particles, and then the powder particles are cold sintered to obtain a blank. Finally, the blank is sintered at high temperature to obtain a semiconductor target.

[0011] The present invention provides an oxide semiconductor thin film, wherein the preparation method of the oxide semiconductor thin film is as follows: firstly, a thin film is prepared by vacuum method or solution method using the semiconductor target material described in the above technical solution, and then the thin film is annealed to obtain the oxide semiconductor thin film.

[0012] Preferably, the annealing temperature is 200~500℃, the annealing time is 0.5~2h, the annealing gas pressure is 0.1~10 atmospheres, and the annealing atmosphere is a strong oxidizing atmosphere.

[0013] Preferably, Tb in the oxide semiconductor thin film exists in the form of trivalent, tetravalent, or a mixture of trivalent and tetravalent valence states.

[0014] This invention provides a thin-film transistor, which has a substrate, a gate, an insulating layer, a channel layer, a source, and a drain disposed sequentially from bottom to top; The gate is located in the middle of the substrate; the insulating layer is located above the gate and connected to the substrate; the channel layer is located above the insulating layer; the channel layer is the oxide semiconductor thin film described in the above technical solution; the source and drain are located at the two ends of the channel layer respectively.

[0015] This invention provides an oxide semiconductor target powder, wherein the chemical structure of the oxide semiconductor target powder is In. α Zn β Sn γ Tb δ O ε Wherein, 0.3≤α≤0.9, 0.01≤β≤0.3, 0.01≤γ≤0.3, 0.01≤δ≤0.3, α+β+γ+δ=1, 1≤ε≤1.8. The oxide semiconductor target powder provided by this invention comprises indium (In), zinc (Zn), tin (Sn), and terbium (Tb). When used to prepare oxide semiconductor thin films, In has a large ionic radius and an outermost 5s orbital, allowing for a large orbital overlap area and high electron mobility. Zinc oxide has a different crystal structure than indium oxide, which can suppress the crystallization of the oxide semiconductor thin film, resulting in a more uniform amorphous thin film. Simultaneously, the Sn ion substitution site for the In ion can provide an additional electron, further improving the electron mobility of the oxide semiconductor thin film. Mobility: Trivalent and tetravalent Tb ions in oxide semiconductor target powder can effectively relax photogenerated carriers. After being prepared into oxide semiconductor thin films, Tb ions act as relaxation channels and recombination centers for photogenerated electrons, suppressing the ionization of deep-level defects (mainly neutral oxygen vacancies near the valence band top) in the oxide semiconductor thin film under NBIS, thereby improving the NBIS stability of the thin film transistor and solving the problem of negative threshold voltage drift in thin film transistors. Furthermore, Tb ions do not introduce impurities or crystal field splitting defects, and do not affect electron transport, achieving a TFT with good NBIS stability and high mobility. The results of the examples show that the carrier mobility of the thin film transistor prepared using the oxide semiconductor target powder provided by the present invention is as high as 60 cm⁻¹. 2 / V∙s, switching current ratio higher than 10 8 The threshold voltage is close to 0V, and the absolute value of the threshold voltage drift under NBIS operating conditions is less than 0.5V per hour, indicating good NBIS stability. Attached Figure Description

[0016] Figure 1 A schematic diagram of the structure of the thin-film transistor provided by the present invention; Figure 1 In the diagram, 10 is the substrate, 11 is the gate electrode, 12 is the insulating layer, 13 is the channel layer, 14a is the source electrode, and 14b is the drain electrode. Figure 2The NBIS transfer characteristic curve of the thin-film transistor prepared in Application Example 1 of this invention; Figure 3 To compare the NBIS transfer characteristic curves of the thin-film transistor prepared in Application Example 1; Figure 4 To compare the NBIS transfer characteristic curves of the thin-film transistor prepared in Application Example 2; Figure 5 The NBIS transfer characteristic curve of the thin-film transistor prepared in Application Example 2 of this invention; Figure 6 The transfer characteristic curve of the thin-film transistor prepared in Application Example 3 of the present invention. Detailed Implementation

[0017] This invention provides an oxide semiconductor target powder, wherein the chemical structure of the oxide semiconductor target powder is In. α Zn β Sn γ Tb δ O ε , among them, 0.3≤α≤0.9, 0.01≤β≤0.3, 0.01≤γ≤0.3, 0.01≤δ≤0.3, α+β+γ+δ=1, 1≤ε≤1.8.

[0018] In one embodiment of the present invention, α can be 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9; β can be 0.01, 0.02, 0.03, 0.05, 0.07, 0.08, 0.1, 0.15, 0.2, 0.25, or 0.3; γ can be 0.01, 0.02, 0.03, 0.05, 0.07, 0.08, 0.1, 0.15, 0.2, 0.25, or 0.3; δ can be 0.01, 0.02, 0.03, 0.05, 0.07, 0.08, 0.1, 0.15, 0.2, 0.25, or 0.3; and ε can be 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, or 1.8.

[0019] In this invention, the preferred molar ratio of α, β, γ, and δ is 12:3:1:1. By controlling the amount of In, Zn, Sn, and Tb, this invention can further improve the NBIS stability of oxide semiconductor thin films.

[0020] In this invention, the Tb in the oxide semiconductor target powder preferably exists in a trivalent, tetravalent, or mixed valence state of trivalent and tetravalent, more preferably in a tetravalent or mixed valence state of trivalent and tetravalent. By controlling the valence state of Tb, this invention can fully utilize the characteristics of high oxygen binding energy and low charge transfer transition energy of Tb ions, thereby improving the electrical bias stability of thin-film transistors by doping with a small amount of terbium.

[0021] In this invention, the chemical structure of the oxide semiconductor target powder is In. α Zn β Sn γ Tb δ O ε The preferred value for δ is 0.0001 to 0.15. In one embodiment of the present invention, the Tb content in the oxide semiconductor target powder can be 0.0001, 0.0005, 0.001, 0.005, 0.01, 0.02, 0.03, 0.04, 0.05, 0.08, 0.10, 0.12, or 0.15. By controlling the Tb content in the oxide semiconductor target powder, the present invention can further improve the NBIS stability of the oxide semiconductor thin film.

[0022] The oxide semiconductor target powder provided by this invention comprises In, Zn, Sn, and Tb. When used to prepare an oxide semiconductor thin film, In has a large ionic radius and an outermost 5s orbital, allowing for a large orbital overlap area and high electron mobility. Zinc oxide has a different crystal structure than indium oxide, which can suppress the crystallization of the oxide semiconductor thin film, resulting in a more uniform amorphous thin film. Simultaneously, the Sn ion substitution site for In ions provides an additional electron, further improving the electron mobility of the oxide semiconductor thin film. The trivalent and tetravalent Tb ions in the oxide semiconductor target powder can effectively relax photogenerated carriers. After preparation into an oxide semiconductor thin film, Tb ions act as relaxation channels and recombination centers for photogenerated electrons, suppressing the ionization of deep-level defects (mainly neutral oxygen vacancies near the valence band top) in the oxide semiconductor thin film under NBIS, thereby improving the NBIS stability of the thin-film transistor and solving the problem of negative threshold voltage drift in thin-film transistors. Furthermore, Tb ions do not introduce impurities or crystal field splitting defects, and do not affect electron transport, achieving a TFT with good NBIS stability and high mobility.

[0023] This invention provides a method for preparing the oxide semiconductor target powder described in the above technical solution, comprising the following steps: (1) Mix indium salt solution, zinc salt solution, tin salt solution and terbium salt solution, and then add ammonia water to carry out a co-precipitation reaction to obtain precursor powder; (2) The precursor powder obtained in step (1) is calcined to obtain oxide semiconductor target powder.

[0024] This invention involves mixing indium salt solution, zinc salt solution, tin salt solution and terbium salt solution, and then adding ammonia water to carry out a co-precipitation reaction to obtain precursor powder.

[0025] In this invention, the indium salt solution is preferably an indium nitrate solution; the zinc salt solution is preferably a zinc nitrate solution; the tin salt solution is preferably a tin nitrate solution; and the terbium salt solution is preferably a terbium nitrate solution. This invention does not impose any particular limitations on the preparation method or concentration of the indium salt solution, zinc salt solution, tin salt solution, and terbium salt solution; they can be prepared using methods well-known to those skilled in the art, provided that the proportions of each component in the oxide semiconductor target powder meet the requirements. Using the above-mentioned components as raw materials in this invention is beneficial for the subsequent reactions.

[0026] In this invention, the preferred method for preparing the indium nitrate solution is to mix indium oxide nanopowder and nitric acid solution, perform a metathesis reaction, and then dilute with water to obtain the indium nitrate solution; the preferred method for preparing the zinc nitrate solution is to mix zinc oxide and nitric acid solution, perform a metathesis reaction, and then dilute with water to obtain the zinc nitrate solution; the preferred method for preparing the tin nitrate solution is to mix tin oxide and nitric acid solution, perform a metathesis reaction, and then dilute with water to obtain the tin nitrate solution; the preferred method for preparing the terbium nitrate solution is to mix terbium oxide and nitric acid solution, perform a metathesis reaction, and then dilute with water to obtain the terbium nitrate solution.

[0027] In this invention, the preparation method of the indium oxide nanopowder preferably includes the following steps: 1) Mix indium salt with a low-polarity alcohol to obtain an indium salt solution; 2) The indium salt solution obtained in step 1) is mixed with an alkaline alcohol solution and then subjected to a coordination reaction to obtain a precipitate; 3) The precipitate obtained in step 2) is calcined to obtain indium oxide nanopowder.

[0028] In this invention, it is preferred to mix indium salt and low-polarity alcohol to obtain indium salt solution.

[0029] In this invention, the indium salt is preferably indium nitrate; the low-polarity alcohol is preferably methanol, ethanol, or propanol; and the mass concentration of the indium salt in the indium salt solution is preferably 0.5% to 10%. As one embodiment of this invention, the mass concentration of the indium salt in the indium salt solution can be 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%. This invention does not impose any particular limitation on the specific method of mixing the indium salt and the low-polarity alcohol, as long as they are mixed uniformly.

[0030] After obtaining the indium salt solution, the present invention preferably mixes the indium salt solution with an alkaline alcohol solution and then performs a coordination reaction to obtain a precipitate.

[0031] In this invention, the concentration of the alkaline alcohol solution is preferably 0.4% to 7.5%; the solvent in the alkaline alcohol solution is preferably a low-polarity alcohol, more preferably methanol, ethanol, or propanol; the temperature of the alkaline alcohol solution is preferably 20°C ≤ the temperature of the alkaline alcohol solution < the boiling point of the low-polarity alcohol. As one embodiment of this invention, the concentration of the alkaline alcohol solution can be 0.4%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, or 7.5%.

[0032] In this invention, the preferred method for mixing the indium salt solution and the basic alcohol solution is to add the basic alcohol solution dropwise to the indium salt solution under stirring conditions. This invention does not impose a specific limitation on the stirring rate, as long as it ensures uniform mixing of the components. This invention also does not impose a specific limitation on the dropwise addition rate, which can be determined based on the technical knowledge of those skilled in the art. By employing the above-described mixing method, this invention can promote complete reaction and improve the utilization rate of raw materials.

[0033] In this invention, the equivalent of the strong base in the mixture of the indium salt solution and the basic alcohol solution is preferably 0.5 to 3, more preferably 1 to 2.5, and even more preferably 1.5 to 2. This invention does not impose any particular limitation on the specific amounts of the indium salt solution and the basic alcohol solution, as long as the equivalent of the strong base in the mixture meets the requirements. By controlling the equivalent of the strong base in the mixture, this invention can improve the reaction rate of indium ions.

[0034] The present invention preferably involves centrifuging, filtering, washing, vacuum filtering, drying, pulverizing, and sieving the products of the coordination reaction in sequence to obtain a precipitate.

[0035] The present invention does not impose any special limitations on the specific operations of centrifugation, filtration, vacuum filtration, pulverization and sieving, and any operations known to those skilled in the art can be used.

[0036] In this invention, the washing is preferably performed using a low-polarity alcohol; the low-polarity alcohol is preferably methanol, ethanol, or propanol. This invention does not have a specific limit on the number of washing cycles, as long as the residual impurities after filtration are completely removed.

[0037] In this invention, the drying temperature is preferably 90~100℃. This invention does not have a specific limitation on the drying time, as long as it is sufficient to dry to a constant weight.

[0038] After obtaining the precipitate, the present invention calcines the precipitate to obtain indium oxide nanopowder.

[0039] In this invention, the calcination temperature is preferably 300~500℃; the calcination time is preferably 0.5~2h. As one embodiment of this invention, the calcination temperature can be 300℃, 320℃, 350℃, 380℃, 400℃, 420℃, 450℃, 480℃, or 500℃; the calcination time can be 1~1.5h. This invention, through the calcination parameters, ensures that the precipitate is completely converted into indium oxide nanoparticles.

[0040] In this invention, the particle size of the indium oxide nanopowder is preferably 20~200 nm.

[0041] The present invention uses the above-mentioned process to prepare indium oxide nanopowder, which not only achieves a purity of ≥99.97%, but also exhibits good dispersibility and uniform morphology, enabling it to better cooperate with tin oxide and zinc oxide, thereby improving product quality. Moreover, the preparation process only requires inexpensive solvents, the reaction is carried out under normal pressure, avoiding the dangers of high pressure, and the calcination temperature is only 300~500℃, eliminating the need for high-temperature calcination. The reduced sintering temperature can correspondingly reduce production costs and extend equipment lifespan, making it suitable for industrial production.

[0042] The present invention does not have any special limitations on the specific operation of mixing the indium salt solution, zinc salt solution, tin salt solution and terbium salt solution. Conventional mixing methods can be used to ensure that they are mixed evenly.

[0043] The present invention does not impose any special limitations on the specific amounts of the indium salt solution, zinc salt solution, tin salt solution and terbium salt solution, as long as the amount of indium, zinc, tin and terbium elements meets the requirements.

[0044] This invention does not impose specific limitations on the concentration and amount of ammonia water added, as long as the coordination reaction is complete. By adding ammonia water, this invention enables indium, zinc, tin, and terbium to precipitate and mix uniformly, thereby facilitating the preparation of a uniformly mixed oxide semiconductor target powder.

[0045] In this invention, the temperature of the co-precipitation reaction is preferably 5-15°C, more preferably 8-12°C, and even more preferably 10°C. This invention does not have a specific limitation on the time of the co-precipitation reaction; it can be determined based on the technical knowledge of those skilled in the art, as long as the reaction is complete. This invention uses a co-precipitation method to prepare oxide semiconductor target powder, which allows for uniform mixing of the oxide powder, enhances the sintering activity of the oxide powder, and thus facilitates the subsequent preparation of semiconductor targets using the oxide semiconductor target powder.

[0046] After the coprecipitation reaction is completed, the product of the coprecipitation reaction is preferably spray-dried to obtain a precursor powder. The specific operation of the spray drying is not particularly limited in this invention; any spray drying method well known to those skilled in the art can be used. This invention removes the solvent by using spray drying to obtain a dry precursor powder.

[0047] After obtaining the precursor powder, the present invention calcines the precursor powder to obtain oxide semiconductor target powder.

[0048] In this invention, the calcination temperature is preferably 1100~1300℃, more preferably 1200℃; the calcination time is preferably 2~5h, more preferably 3h. Through calcination, this invention can transform the precursor powder into a metal oxide powder.

[0049] This invention uses a stepwise co-precipitation method to prepare oxide semiconductor target powder, which can make the oxide powder uniformly mixed and enhance the sintering activity of the oxide powder, thereby facilitating the subsequent preparation of semiconductor targets using the oxide semiconductor target powder.

[0050] The present invention also provides a semiconductor target material, which is prepared from the oxide semiconductor target powder described in the above technical solution.

[0051] In this invention, the method for preparing the semiconductor target preferably includes: Oxide semiconductor target powder is granulated to obtain powder particles, then the powder particles are pressed into shape to obtain a blank, and finally the blank is sintered in two stages to obtain a semiconductor target. or, Oxide semiconductor target powder is granulated to obtain powder particles, and then the powder particles are cold sintered to obtain a blank. Finally, the blank is sintered at high temperature to obtain a semiconductor target.

[0052] In this invention, the preferred granulation method is spray granulation. This invention does not impose any specific limitations on the specific operation of the spray granulation, as long as the loose packing density of the powder particles meets the requirements.

[0053] In this invention, the loose packing density of the powder particles is preferably ≥1.3 g / cm³. 3 More preferably, it is 1.3~2.0 g / cm³. 3 This invention controls the loose packing density of powder particles, which facilitates subsequent pressing and molding.

[0054] In this invention, the pressing molding method is preferably isostatic pressing; the pressing molding pressure is preferably 250~350MPa, more preferably 300MPa; the pressing molding time is preferably 600~1200s, more preferably 800~1000s. This invention promotes material transport and rearrangement between powder particles through pressing molding, thereby improving the initial density of the green body.

[0055] In this invention, the preferred method for the two-stage sintering is as follows: first, the temperature is raised to 1400~1500℃ and held for 0.5~5 hours for the first stage of sintering, and then the temperature is lowered to 1320~1360℃ and held for 8~14 hours for the second stage of sintering. In this invention, the preferred atmosphere for the two-stage sintering is any one or a mixture of two or more of air, water vapor, oxygen, and argon.

[0056] In this invention, the temperature of the cold sintering treatment is preferably 150-200℃, more preferably 170-180℃; the pressure of the cold sintering treatment is preferably 150-300MPa, more preferably 200-250MPa; and the time of the cold sintering treatment is preferably 1min-120min, more preferably 10-90min, and even more preferably 20-60min. This invention, through cold sintering treatment, can reduce the voids between powder particles and improve the density of the green body.

[0057] In this invention, the preferred high-temperature sintering temperature is 1150~1300℃, more preferably 1200~1250℃; the preferred high-temperature sintering time is 0.5~2h, more preferably 1~1.5h. This invention, through high-temperature sintering, can obtain high-performance semiconductor targets.

[0058] By employing the above-described sintering method, this invention can improve the density of semiconductor targets while preventing warping and cracking. By controlling the sintering process parameters, it can overcome the problems of element volatilization and segregation in multi-element oxide targets during sintering, prevent changes in the composition or phase transition of oxide targets, improve the sintering activity of oxide semiconductor target powder while ensuring the pressing performance of oxide semiconductor target powder, increase the initial density of semiconductor targets and reduce the sintering temperature for full densification, and prepare semiconductor targets with uniform structure, low trace impurity content and low resistivity.

[0059] In this invention, the relative density of the semiconductor target is preferably ≥99.9%; the purity of the semiconductor target is preferably ≥99.99%. The semiconductor target prepared by this invention has the characteristics of high density and high purity, which can reduce impurities in the semiconductor thin film in the subsequently prepared thin-film transistor.

[0060] The present invention also provides an oxide semiconductor thin film, which is prepared by first using the semiconductor target described in the above technical solution to prepare the thin film by vacuum method or solution method, and then annealing the thin film to obtain the oxide semiconductor thin film.

[0061] In this invention, the vacuum method is preferably magnetron sputtering, electron beam evaporation, pulsed laser deposition, atomic layer deposition, or chemical vapor deposition. In this invention, when the vacuum valve is magnetron sputtering, the magnetron sputtering is preferably single-target sputtering or multi-target sputtering.

[0062] In this invention, the solution method is preferably spin coating, inkjet printing, screen printing, scraping coating, or embossing.

[0063] In this invention, the annealing temperature is preferably 200~500℃; the annealing time is preferably 0.5~2h; the annealing gas pressure is preferably 0.1~10 atmospheres; and the annealing atmosphere is preferably a strong oxidizing atmosphere, more preferably oxygen, nitrogen dioxide, water vapor, air, or a mixed gas with an oxygen content greater than 20%. As one embodiment of this invention, the annealing temperature can be 200℃, 250℃, 300℃, 350℃, 400℃, 450℃, or 500℃; the annealing time can be 0.5h, 1h, 1.5h, or 2h; and the annealing gas pressure can be 0.1 atmospheres, 0.2 atmospheres, 0.5 atmospheres, 1 atmosphere, 2 atmospheres, 3 atmospheres, 4 atmospheres, 5 atmospheres, 6 atmospheres, 7 atmospheres, 8 atmospheres, 9 atmospheres, or 10 atmospheres. In this invention, since tetravalent Tb ions may be deoxygenated and transformed into trivalent Tb ions during the deposition of oxide semiconductor thin films, or only tetravalent Tb ions may be present or absent, thereby affecting the charge transfer process and reducing the NBIS stability of the oxide semiconductor thin film, this invention improves the NBIS stability of the oxide semiconductor thin film by annealing in a strong oxidizing atmosphere, thereby increasing the content of tetravalent Tb ions and reducing defects such as oxygen vacancies.

[0064] In this invention, the oxide semiconductor thin film is preferably composed of In. α Zn β Sn γ Tb δ O ε, among them, 0.3≤α≤0.9, 0.01≤β≤0.3, 0.01≤γ≤0.3, 0.01≤δ≤0.3, α+β+γ+δ=1, 1≤ε≤1.8. In one embodiment of the present invention, α can be 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9; β can be 0.01, 0.02, 0.03, 0.05, 0.07, 0.08, 0.1, 0.15, 0.2, 0.25, or 0.3; γ can be 0.01, 0.02, 0.03, 0.05, 0.07, 0.08, 0.1, 0.15, 0.2, 0.25, or 0.3; δ can be 0.01, 0.02, 0.03, 0.05, 0.07, 0.08, 0.1, 0.15, 0.2, 0.25, or 0.3; and ε can be 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, or 1.8.

[0065] In this invention, the molar ratio of α, β, γ and δ is preferably 12:3:1:1.

[0066] In this invention, Tb in the oxide semiconductor thin film preferably exists in a trivalent, tetravalent, or mixed valence state of trivalent and tetravalent, more preferably in a mixed valence state of trivalent and tetravalent. In this invention, the chemical structure of the oxide semiconductor target powder is In. α Zn β Sn γ Tb δ O ε The preferred value of δ is 0.0001 to 0.15. In one embodiment of the present invention, the Tb content in the oxide semiconductor target powder can be 0.0001, 0.0005, 0.001, 0.005, 0.01, 0.02, 0.03, 0.04, 0.05, 0.08, 0.10, 0.12, or 0.15.

[0067] In this invention, the thickness of the oxide semiconductor thin film is preferably 2~200 nm; the carrier concentration of the oxide semiconductor thin film is preferably <5×10⁻⁶. 19 cm -3 In one embodiment of the present invention, the thickness of the oxide semiconductor thin film can be 2nm, 5nm, 10nm, 20nm, 50nm, 80nm, 100nm, 120nm, 150nm, 180nm, or 200nm. The oxide semiconductor thin film provided by the present invention can be used as a channel layer material for transistors, and has the characteristics of good stability, simple preparation process, and strong applicability.

[0068] The present invention also provides a thin-film transistor, wherein a substrate, a gate, an insulating layer, a channel layer, a source, and a drain are disposed sequentially from bottom to top.

[0069] The structural schematic diagram of the thin-film transistor provided by this invention is shown below. Figure 1 As shown. Figure 1 In this configuration, the gate is located in the middle portion above the substrate; the insulating layer is located above the gate and connected to the substrate; the channel layer is located above the insulating layer; the channel layer is the oxide semiconductor thin film described in the above technical solution; and the source and drain are located at opposite ends of the channel layer.

[0070] The thin-film transistor provided by this invention includes a substrate. In this invention, the substrate preferably includes a substrate material and / or a buffer layer or water-oxygen barrier layer covering the substrate material; the substrate material is preferably made of glass, a flexible polymer substrate, a silicon wafer, p-type doped single-crystal silicon, a metal foil, or quartz. This invention does not impose any special limitations on the size of the substrate; substrate dimensions well known to those skilled in the art can be used.

[0071] The thin-film transistor provided by the present invention includes a gate; the gate is located in the middle portion above a substrate. In the present invention, the gate is preferably made of a conductive material, more preferably a superposition of one or more thin films selected from conductive metal, conductive alloy, conductive metal oxide, P-type doped single crystal silicon, and conductive polymer, and even more preferably metal Al; the thickness of the gate is preferably 300~350 nm.

[0072] The thin-film transistor provided by this invention includes an insulating layer; the insulating layer is located above the gate and connected to the substrate. In this invention, the insulating layer is preferably made of one or more of the following materials: silicon dioxide, silicon nitride, silicon oxynitride, aluminum oxide, aluminum oxide alloy, ytterbium oxide, titanium oxide, hafnium oxide, tantalum oxide, zirconium oxide, polymer insulating material, and photoresist; the thickness of the insulating layer is preferably 100-200 nm.

[0073] The thin-film transistor provided by this invention includes a channel layer; the channel layer is the oxide semiconductor thin film described in the above-mentioned technical solution. This invention does not impose any special limitation on the size of the channel layer; channel layer sizes well-known to those skilled in the art can be used.

[0074] The thin-film transistor provided by this invention includes a source and a drain; the source and drain are respectively located at both ends of a channel layer. In this invention, the material of the source and drain is independently preferably a conductive material, more preferably a superposition of one or more thin films of metal, alloy, conductive metal oxide and conductive polymer, and even more preferably metal Al; the thickness of the source and drain is independently preferably 80~100 nm.

[0075] The thin-film transistor provided by this invention has a carrier mobility as high as 60 cm⁻¹. 2 / V∙s, switching current ratio higher than 10 8 The threshold voltage is close to 0 V, and the absolute value of the threshold voltage drift under NBIS operating conditions is less than 0.5 V per hour, indicating good NBIS stability.

[0076] In this invention, the thin-film transistor is preferably used for active driving of organic light-emitting displays, liquid crystal displays or electronic paper, and integrated circuits.

[0077] This invention employs an oxide semiconductor thin film as the channel layer of a thin-film transistor (TFT). The oxide semiconductor thin film comprises In, Zn, Sn, and Tb. The addition of a large amount of In and a certain amount of Sn ensures high carrier transport capability. The trivalent and tetravalent Tb ions in the oxide semiconductor thin film can effectively relax photogenerated carriers. By using Tb ions as relaxation channels and recombination centers for photogenerated electrons, the ionization of deep-level defects (mainly neutral oxygen vacancies near the valence band top) in the oxide semiconductor thin film under NBIS is suppressed, solving the problem of negative threshold voltage drift in TFTs. Furthermore, it does not introduce impurities or crystal field splitting defects, and does not affect electron transport, thus achieving a TFT with good NBIS stability and high mobility. This improves the NBIS stability of the TFT, resulting in a TFT with both high mobility and high stability, characterized by good NBIS stability, simple fabrication process, and strong practicality.

[0078] The preparation method of the present invention is simple, has low requirements for experimental conditions, is highly controllable, low in cost, can be mass-produced on a large scale and has high repeatability, and meets environmental requirements.

[0079] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0080] The preparation method of indium oxide nanopowder described in the embodiments and comparative examples of this invention is as follows: 1) Mix indium nitrate and ethanol to obtain an indium salt solution with a mass concentration of 5%; 2) Under stirring conditions, the alkaline alcohol solution is added dropwise to the indium salt solution obtained in step 1) until the equivalent of the strong base in the mixture is 2 to carry out a coordination reaction. Then, the mixture is centrifuged, filtered, washed with ethanol, vacuum filtered, dried at 100°C, pulverized, and sieved to obtain a precipitate. The concentration of the alkaline alcohol solution is 4%, the solvent in the alkaline alcohol solution is ethanol, and the temperature of the alkaline alcohol solution is 20°C. 3) The precipitate obtained in step 2) is calcined to obtain indium oxide nanoparticles; the calcination temperature is preferably 400℃; the calcination time is 1h; and the particle size of the indium oxide nanoparticles is 20~200nm.

[0081] Example 1 An oxide semiconductor target powder, wherein the chemical structure of the oxide semiconductor target powder is In α Zn β Sn γ Tb δ O ε The molar ratio of α, β, γ and δ is 12:3:1:1, and α+β+γ+δ=1. The method for preparing the oxide semiconductor target powder is as follows: (1) Mix indium nitrate solution, zinc nitrate solution, tin nitrate solution and terbium nitrate solution, then add ammonia water and carry out co-precipitation reaction at 10°C, and finally spray dry to obtain precursor powder; (2) The precursor powder obtained in step (1) is calcined at a temperature of 1200°C for 3 hours to obtain oxide semiconductor target powder.

[0082] Comparative Example 1 An oxide semiconductor target powder, wherein the chemical structure of the oxide semiconductor target powder is In α Zn β Sn γ O ε The molar ratio of α, β and γ is 12:3:1, and α+β+γ=1. The method for preparing the oxide semiconductor target powder is as follows: (1) Mix indium nitrate solution, zinc nitrate solution and tin nitrate solution, then add ammonia water and carry out co-precipitation reaction at 10°C, and finally spray dry to obtain precursor powder; (2) The precursor powder obtained in step (1) is calcined at a temperature of 1200°C for 3 hours to obtain oxide semiconductor target powder.

[0083] Comparative Example 2 The molar ratio of α, β, γ and δ is 12:3:1:2, and α+β+γ+δ=1; other conditions are the same as in implementation 1.

[0084] Application Example 1 A structural schematic diagram is shown below. Figure 1The thin-film transistor shown comprises, from bottom to top, a substrate, a gate, an insulating layer, a channel layer, a source, and a drain; the gate is located at the center above the substrate; the insulating layer is located above the gate and connected to the substrate; the channel layer is located above the insulating layer; the channel layer is the oxide semiconductor thin film described in the above technical solution; the source and drain are located at opposite ends of the channel layer. The method for fabricating the thin-film transistor is as follows: I. A 300 nm thick thin film was prepared on a glass substrate using physical vapor deposition with conductive metal Al as the material. Then, the gate was patterned by ultraviolet lithography and wet etching. II. Using alumina as the material, a 200 nm thick alumina thin film is prepared on the substrate and gate by physical vapor deposition to obtain an insulating layer; III. First, a thin film is prepared on an insulating layer using magnetron sputtering with a semiconductor target. Patterning is then performed using a cutout mask. The film is then annealed to obtain an oxide semiconductor thin film. Finally, photolithography is used to pattern the film to obtain the channel layer. The annealing temperature is 300℃, the annealing time is 1 hour, and the annealing gas pressure is 6 atmospheres. The annealing atmosphere is air. The thickness of the oxide semiconductor thin film is 100 nm, and the carrier concentration of the oxide semiconductor thin film is <5 × 10⁻⁶. 19 cm; IV. Using metallic Al as the material, a thin film with a thickness of 80 nm is prepared on the channel layer by mask patterning. Then, the source and drain are obtained by photolithography, and finally a thin film transistor is obtained. The semiconductor target material is prepared from the oxide semiconductor target material powder provided in Example 1, and the preparation method is as follows: The oxide semiconductor target powder was spray-granulated to obtain a loose packing density ≥1.3 g / cm³. 3 The powder particles are then pressed into shape using an isostatic pressing process at a pressure of 300 MPa for 1200 s to obtain a blank. Finally, the blank is subjected to a two-stage sintering process: first, the temperature is raised to 1400℃ and held for 3 hours for the first stage of sintering, and then the temperature is lowered to 1350℃ and held for 12 hours for the second stage of sintering to obtain a semiconductor target material with a relative density ≥99.9% and a purity ≥99.99%.

[0085] The thin-film transistor provided by this invention has a carrier mobility as high as 60 cm⁻¹. 2 / V∙s, switching current ratio higher than 10 8 The threshold voltage is close to 0V, and the absolute value of the threshold voltage drift under NBIS operating conditions is less than 0.5V per hour, indicating good NBIS stability.

[0086] Application Example 2 A structural schematic diagram is shown below. Figure 1 The thin-film transistor shown is provided in which the semiconductor target is prepared from the oxide semiconductor target powder provided in Example 2, the annealing temperature in step III is 350°C, the annealing atmosphere is pure oxygen atmosphere, and other conditions are the same as in Application Example 1.

[0087] Application Example 3 A method for fabricating a thin-film transistor is as follows: I. Use P-type doped single-crystal silicon as the substrate and gate; II. Using silicon dioxide as the material, a silicon dioxide thin film with a thickness of 100 nm is prepared on the substrate and gate by thermal oxidation to obtain an insulating layer; III. First, a thin film is prepared on an insulating layer using magnetron sputtering with a semiconductor target. Patterning is then performed using a cutout mask. The film is then annealed to obtain an oxide semiconductor thin film. Finally, photolithography is used to pattern the film to obtain the channel layer. The annealing temperature is 350℃, the annealing time is 1 hour, and the annealing gas pressure is 6 atmospheres. The annealing atmosphere is pure oxygen. The thickness of the oxide semiconductor thin film is 100 nm, and the carrier concentration of the oxide semiconductor thin film is <5 × 10⁻⁶. 19 cm; IV. Using metallic Al as the material, a thin film with a thickness of 80 nm is prepared on the channel layer by mask patterning. Then, the source and drain are obtained by photolithography, and finally a thin film transistor is obtained. Other conditions are the same as in Application Example 1.

[0088] Comparative Application Example 1 A structural schematic diagram is shown below. Figure 1 The thin-film transistor shown is prepared from the oxide semiconductor target powder provided in Comparative Example 1, with other conditions the same as in Application Example 1.

[0089] Comparative Application Example 2 A structural schematic diagram is shown below. Figure 1 The thin-film transistor shown is wherein the semiconductor target is prepared from the oxide semiconductor target powder provided in Comparative Example 2, and the annealing temperature in step III is 350°C, with other conditions being the same as in Application Example 1.

[0090] The NBIS transfer characteristic curve of the thin-film transistor prepared by Example 1 of this invention is shown in the figure below. Figure 2 As shown; the NBIS transfer characteristic curve of the thin-film transistor prepared in Application Example 1 is shown in Figure 1. Figure 3As shown; the NBIS transfer characteristic curve of the thin-film transistor prepared in Application Example 2 is shown in Figure 2. Figure 4 As shown. By Figure 2 It can be seen that the thin-film transistor prepared in Example 1, due to the presence of Tb in the channel layer material, can effectively control the carrier concentration within the oxide semiconductor thin film, achieving a threshold voltage of approximately 0V, and exhibiting good NBIS stability; Figure 3 As shown, the thin-film transistor prepared in Comparative Application Example 1, due to the absence of Tb element in the channel layer material, has difficulty controlling the carrier concentration within the oxide semiconductor thin film, exhibits a threshold voltage less than -20V, and demonstrates poor NBIS stability; Figure 4 As shown, in the thin-film transistor prepared in Comparative Application Example 2, although increasing the Tb content in the channel layer can further enhance the NBIS stability of the oxide thin-film transistor, the excessive Tb content severely reduces the carrier concentration within the oxide semiconductor thin film, resulting in a decrease in transistor mobility to 15 cm⁻¹. 2 / V∙s.

[0091] The NBIS transfer characteristic curve of the thin-film transistor prepared in Example 2 of this invention is shown in the figure below. Figure 5 As shown. By Figure 5 It can be seen that the thin-film transistor prepared in Application Example 2 can be further oxidized to tetravalent Tb ions in the oxide semiconductor thin film by annealing in a strong oxidizing pure oxygen atmosphere, thereby obtaining better NBIS stability. The absolute value of the threshold voltage drift under the operating NBIS is less than 0.5V per hour.

[0092] The transfer characteristic curve of the thin-film transistor prepared in Example 3 of this invention is shown in the figure below. Figure 6 As shown. By Figure 6 It can be seen that the mobility of the thin-film transistor prepared by Example 3 is 52 cm⁻¹. 2 It has a voltage of / V∙s, a threshold voltage of around 0V, and excellent NBIS stability.

[0093] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An oxide semiconductor target material powder, characterized by comprising: The chemical structure of the oxide semiconductor target powder is In α Zn β Sn γ Tb δ O ε wherein 0.3≤α≤0.9, 0.01≤β≤0.3, 0.01≤γ≤0.3, 0.01≤δ≤0.3, α+β+γ+δ=1, 1≤ε≤1.

8.

2. The oxide semiconductor target material powder according to claim 1, wherein The molar ratio of the alpha, beta, gamma and delta substances is 12:3:1:

1.

3. The method for producing an oxide semiconductor target material powder according to claim 1 or 2, wherein The method comprises the following steps: (1) mixing indium salt solution, zinc salt solution, tin salt solution and terbium salt solution, and then adding ammonia water to perform co-precipitation reaction to obtain a precursor powder; (2) calcining the precursor powder obtained in the step (1) to obtain an oxide semiconductor target material powder.

4. The production method according to claim 3, characterized by, The calcination temperature in the step (2) is 1100-1300 DEG C, and the calcination time is 2-5 h.

5. A semiconductor target material, characterized by, The semiconductor target material is prepared from the oxide semiconductor target material powder of claim 1 or 2 or the oxide semiconductor target material powder prepared by the method of any one of claims 3-5.

6. The semiconductor target according to claim 5, wherein The method for preparing the semiconductor target material comprises: granulating the oxide semiconductor target material powder to obtain powder particles, then performing compression molding on the powder particles to obtain a green body, and finally performing two-stage sintering on the green body to obtain the semiconductor target material; or, granulating the oxide semiconductor target material powder to obtain powder particles, then performing cold sintering treatment on the powder particles to obtain a green body, and finally performing high-temperature sintering on the green body to obtain the semiconductor target material.

7. An oxide semiconductor thin film, characterized by The method for preparing the oxide semiconductor thin film comprises: first, using the semiconductor target material of claim 5 or 6 to prepare a thin film by a vacuum method or a solution method, and then performing annealing treatment on the thin film to obtain the oxide semiconductor thin film.

8. The oxide semiconductor film according to claim 7, wherein The annealing treatment temperature is 200-500 DEG C, the annealing treatment time is 0.5-2 h, the annealing treatment gas pressure is 0.1-10 atm, and the annealing treatment atmosphere is a strong oxidizing atmosphere.

9. The oxide semiconductor film according to claim 7, wherein The Tb in the oxide semiconductor thin film exists in the form of positive trivalence, positive tetravalence or a mixed valence of positive trivalence and positive tetravalence.

10. A thin film transistor, characterized by comprising: From bottom to top, a substrate, a gate, an insulation layer, a channel layer, a source and a drain are sequentially arranged; The gate is located at the middle part above the substrate; the insulation layer is located above the gate and connected with the substrate; the channel layer is located above the insulation layer; the channel layer is the oxide semiconductor thin film of claims 7-9; the source and the drain are respectively located at the two ends of the channel layer.

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