CN109378274B - A method for preparing different types of indium gallium zinc oxide thin film transistors - Google Patents

Abstract

The invention belongs to the technical field of semiconductors, and particularly relates to a method for preparing different types of indium gallium zinc oxide thin film transistors. According to the invention, an enhancement transistor or a depletion transistor is obtained by adjusting the molar ratio of indium ions, gallium ions and zinc ions in the indium gallium zinc oxide film precursor solution; the method is simple, convenient and reliable, can reduce the preparation cost of the transistor, and is suitable for popularization and application.

Description

A method for preparing different types of indium gallium zinc oxide thin film transistors

technical field

The invention belongs to the technical field of semiconductors, and in particular relates to a method for preparing different types of indium gallium zinc oxide thin film transistors.

Background technique

In recent years, with the rapid development of flexible organic light-emitting diodes, quantum dots, electronic paper display technology and devices, people pay more attention to the development of thin film transistor technology. There are two types of transistors: depletion type and enhancement type. Among them, the depletion type transistor has a channel when the gate bias is 0. When the gate voltage is added, the majority carriers can flow out of the channel, so that the transistor can flow out of the channel. Commonly used. The depletion-mode transistors include AO3402, BSS229, etc.; and the enhancement-mode transistor is in the off state when the gate voltage is 0. After the gate voltage is added, the majority carriers are attracted to the gate, forming a conductive channel. Commonly used enhancement transistors are 10N60, 4N60F, etc. These two types of transistors have their own characteristics, so they have received extensive attention from researchers.

The oxide system has the advantages of flexible ratio and low process temperature, and is widely used in the field of semiconductor materials. For example, indium gallium zinc oxide is a relatively mature semiconductor material for thin film transistors. Existing indium gallium zinc oxide thin films are usually prepared by vacuum sputtering technology. Although this process can prepare different types of transistor materials, the preparation process is complicated and the cost is high.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a method for preparing different types of indium gallium zinc oxide thin film transistors. The method provided by the present invention can obtain different types of indium gallium zinc oxide thin film transistors by adjusting the amount of elements in the precursor solution. The method is simple, reliable.

In order to achieve the above object, the present invention provides the following technical solutions:

The invention provides a method for preparing different types of indium gallium zinc oxide thin film transistors, comprising the following steps:

The indium gallium zinc oxide thin film precursor solution comprising indium salt, gallium salt, zinc salt, stabilizer and alcohol ether solvent is coated on the substrate, and then dried and annealed in sequence to obtain the indium gallium zinc oxide thin film-substrate composite material;

and then preparing electrodes on the indium gallium zinc oxide thin film-substrate composite material to obtain an indium gallium zinc oxide thin film transistor;

When preparing the indium gallium zinc oxide thin film transistor, by adjusting the molar ratio of indium ions, gallium ions and zinc ions in the indium gallium zinc oxide thin film precursor solution, an enhancement mode transistor or a depletion mode transistor is obtained;

In the indium gallium zinc oxide thin film precursor solution, when the molar ratio of indium ion, gallium ion and zinc ion is (2-3):1:(6-7), an enhancement type indium gallium zinc oxide thin film transistor is obtained;

When the molar ratio of indium ion, gallium ion and zinc ion is (5-6):1:(3-4), a depletion mode indium gallium zinc oxide thin film transistor is obtained.

Preferably, the indium salt includes indium nitrate or indium acetate, the gallium salt includes gallium nitrate or gallium acetate, and the zinc salt includes zinc acetate or zinc nitrate.

Preferably, the stabilizer includes ethanolamine and glacial acetic acid.

Preferably, the volume ratio of the ethanolamine to the alcohol ether solvent is 1-1.5:5.

Preferably, the volume ratio of the glacial acetic acid to the alcohol ether solvent is 0.1-0.5:5.

Preferably, in the precursor solution of the indium gallium zinc oxide thin film, the concentration of the gallium salt is 0.02-0.03 mol/L.

Preferably, the substrate includes a Si/SiO ₂ substrate.

Preferably, the coating method of the indium gallium zinc oxide thin film precursor solution is spin coating, the speed of the spin coating is 2400-2600 r/min, the number of times of the spin coating is 2 times, and the time of a single spin coating is 25 ~35s.

Preferably, the annealing temperature is 500-600° C.; at the annealing temperature, the holding time is 0.5-1.5 h.

Preferably, the preparation method of the electrode comprises:

The indium gallium zinc oxide thin film-substrate composite material is sequentially subjected to photolithography, development, film-fixing and corrosion; then the corroded composite material is sequentially overetched, developed and metallized to obtain an electrode.

The invention provides a method for preparing different types of indium gallium zinc oxide thin film transistors: coating the indium gallium zinc oxide thin film precursor solution including indium salt, gallium salt, zinc salt, stabilizer and alcohol ether solvent on the substrate, Then, drying and annealing are performed in sequence, and electrodes are prepared on the obtained indium gallium zinc oxide thin film-substrate composite material to obtain an indium gallium zinc oxide thin film transistor. In the present invention, when the indium gallium zinc oxide thin film transistor is prepared, the molar ratio of indium ion, gallium ion and zinc ion in the indium gallium zinc oxide thin film precursor solution is adjusted to obtain an enhancement mode transistor or a depletion mode transistor; In the precursor solution of zinc oxide thin film, when the molar ratio of indium ion, gallium ion and zinc ion is (2～3):1:(6～7), an enhancement mode indium gallium zinc oxide thin film transistor is obtained; When the molar ratio of ions to zinc ions is (5-6):1:(3-4), the method for obtaining a depletion-type indium gallium zinc oxide thin film transistor is simple and reliable. The results of the embodiments of the present invention show that the above scheme can be used to obtain an enhancement-mode indium-gallium-zinc-oxide thin-film transistor or a depletion-mode indium-zinc-oxide thin film transistor with a high switching ratio.

Description of drawings

Fig. 1 is the output curve of the indium gallium zinc oxide thin film transistor obtained in Examples 1-4;

Fig. 2 is the transfer curve of the indium gallium zinc oxide thin film transistor obtained in Examples 1-4;

FIG. 3 is a graph showing the threshold voltages of the indium gallium zinc oxide thin film transistors calculated in Examples 1-4.

Detailed ways

In the following specific embodiments, the reagents described in the present invention are all commercially available products well known to those skilled in the art unless otherwise specified.

The invention provides a method for preparing different types of indium gallium zinc oxide thin film transistors, comprising the following steps:

The indium gallium zinc oxide thin film precursor solution comprising indium salt, gallium salt, zinc salt, stabilizer and alcohol ether solvent is coated on the substrate, and then dried and annealed in sequence to obtain the indium gallium zinc oxide thin film-substrate composite material;

and then preparing electrodes on the indium gallium zinc oxide thin film-substrate composite material to obtain an indium gallium zinc oxide thin film transistor;

When preparing the indium gallium zinc oxide thin film transistor, by adjusting the molar ratio of indium ions, gallium ions and zinc ions in the indium gallium zinc oxide thin film precursor solution, an enhancement mode transistor or a depletion mode transistor is obtained;

The indium gallium zinc oxide thin film precursor solution includes indium salt, gallium salt, zinc salt, stabilizer and alcohol ether solvent;

In the indium gallium zinc oxide thin film precursor solution, when the molar ratio of indium ion, gallium ion and zinc ion is (2-3):1:(6-7), an enhancement type indium gallium zinc oxide thin film transistor is obtained;

When the molar ratio of indium ion, gallium ion and zinc ion is (5-6):1:(3-4), a depletion mode indium gallium zinc oxide thin film transistor is obtained.

In the present invention, an indium gallium zinc oxide thin film precursor solution comprising indium salt, gallium salt, zinc salt, stabilizer and alcohol ether solvent is coated on a substrate, and then dried and annealed in sequence to obtain an indium gallium zinc oxide thin film-substrate composite Material.

In the present invention, indium salt, gallium salt and zinc salt in the indium gallium zinc oxide thin film precursor solution are used to provide indium ion, gallium ion and zinc ion respectively; wherein, the indium salt preferably includes indium nitrate or indium acetate; Gallium salts preferably include gallium nitrate or gallium acetate; zinc salts preferably include zinc acetate or zinc nitrate.

The invention prepares different types of indium gallium zinc oxide thin film transistors by adjusting the molar ratio of indium ion, gallium ion and zinc ion in the indium gallium zinc oxide thin film precursor solution. In the present invention, in the indium gallium zinc oxide film precursor solution, when the molar ratio of indium ion, gallium ion and zinc ion is (2～3):1:(6～7), the enhancement type indium gallium zinc is obtained Oxygen thin film transistor; the molar ratio of indium ion, gallium ion and zinc ion is preferably (2.2-2.8):1:(6.2-6.8), more preferably (2.3-2.7):1:(6.3-6.7). In the embodiment of the present invention, the molar ratio of the indium ion, gallium ion and zinc ion may specifically be 2:1:7, 2.1:1:6.9, 2.2:1:6.8, 2.3:1:6.7, 2.4:1 :6.6, 2.5:1:6.5, 2.6:1:6.4, 2.7:1:6.3, 2.8:1:6.2, 2.9:1:6.1, or 3:1:6.

In the present invention, when the molar ratio of the indium ion, gallium ion and zinc ion is (5-6):1:(3-4), a depletion-type indium gallium zinc oxide thin film transistor is obtained. In the present invention, the molar ratio of the indium ion, gallium ion and zinc ion is preferably (5.2-5.9):1:(3.1-3.8), more preferably (5.3-5.7):1:(3.3-3.7) . In the embodiment of the present invention, the molar ratio of the indium ion, gallium ion and zinc ion may specifically be 5:1:4, 5.1:1:3.9, 5.2:1:3.8, 5.3:1:3.7, 5.4:1 :3.6, 5.5:1:3.5, 5.6:1:3.4, 5.7:1:3.3, 5.8:1:3.2, 5.9:1:3.1, or 6:1:3.

In the present invention, in the indium gallium zinc oxide thin film precursor solution, the concentration of the gallium salt is preferably 0.02-0.03 mol/L, more preferably 0.023-0.028 mol/L, still more preferably 0.024-0.027 mol/L, Most preferably, it is 0.025 mol/L.

In the present invention, the indium gallium zinc oxide thin film precursor solution includes a stabilizer, and the stabilizer preferably includes ethanolamine and glacial acetic acid. In the present invention, the volume ratio of the ethanolamine to the alcohol ether solvent is preferably 1 to 1.5:5, more preferably 1.2 to 1.4:5; the volume ratio of the glacial acetic acid to the alcohol ether solvent is preferably 0.1 to 0.5:5 , more preferably 0.2 to 0.4:5. In the present invention, the mixture of ethanolamine and glacial acetic acid is preferably used as a stabilizer to improve the stability of the precursor solution and promote the rapid dissolution of the solute in the precursor solution.

In the present invention, the indium gallium zinc oxide thin film precursor solution includes an alcohol ether solvent, and the alcohol ether solvent preferably includes ethylene glycol methyl ether. In the present invention, alcohol ether solvent is preferably used as the solvent of the precursor solution of the indium gallium zinc oxide thin film, so that the stabilizer can be uniformly mixed with each component, thereby obtaining the indium gallium zinc oxide thin film with uniform components and properties.

The present invention has no special requirements on the provision of the indium gallium zinc oxide thin film precursor solution, and the method well known to those skilled in the art can be used. In the present invention, the indium gallium zinc oxide thin film precursor solution is preferably obtained by mixing indium salt, gallium salt, zinc salt and alcohol ether solvent, then adding a stabilizer, heating and stirring, and then standing and filtering in sequence.

In the present invention, the temperature during the heating and stirring is preferably 140-160°C, more preferably 145-155°C; the heating and stirring time is preferably 1-1.5h, more preferably 1-1.2h. The present invention does not have special requirements on the speed of the heating and stirring, and those skilled in the art may be used. The present invention preferably heats and stirs the mixture of indium salt, gallium salt, zinc salt, alcohol ether solvent and stabilizer, which can promote the dissolution and dispersion of each component, and is beneficial to obtaining an indium gallium zinc oxide film with uniform components.

After heating and stirring, the present invention preferably allows the material after heating and stirring to stand, and the standing time is preferably 20-30 hours, more preferably 22-26 hours, and more preferably 24-25 hours; the standing is preferably at room temperature proceed below.

After standing, the present invention preferably filters the materials after standing to remove undissolved impurities or particles in the mixture to obtain materials suitable for coating. In the present invention, the filtration is preferably performed through a filter, and the size of the filter is preferably 0.1-0.3 μm, more preferably 0.15-0.25 μm, still more preferably 0.18-0.23 μm, and most preferably 0.2 μm.

After obtaining the indium gallium zinc oxide thin film precursor solution, the present invention coats the indium gallium zinc oxide thin film precursor solution on the substrate, and then dries to obtain the precursor film-substrate composite material. In the present invention, the substrate preferably comprises a Si/SiO ₂ substrate. The present invention does not have special requirements on the specifications and dimensions of the substrate, which can be used by those skilled in the art. In a specific embodiment of the present invention, the size of the substrate is preferably 1.5 cm ² .

Before coating, in the present invention, the substrate is preferably cleaned, and the cleaning preferably includes acetone cleaning, absolute ethanol cleaning and deionized water cleaning in sequence. In the present invention, the methods of acetone cleaning, absolute ethanol cleaning and deionized water cleaning are preferably ultrasonic cleaning, and the time of the ultrasonic cleaning is independently preferably 10-15 minutes, more preferably 10-12 minutes; the ultrasonic cleaning The power of cleaning is preferably 80 to 150 kW independently, and more preferably 100 to 120 kW.

In the present invention, the coating method of the indium gallium zinc oxide thin film precursor solution is preferably spin coating; the speed of the spin coating is preferably 2400-2600 r/min, more preferably 2450-2550 r/min, still more preferably 2500r/min. In the present invention, the number of times of the spin coating is preferably 2 times, and the amount of the precursor solution of the indium gallium zinc oxide thin film for a single spin coating is preferably 0.04-0.06 mL, more preferably 0.045-0.055 mL, and more preferably 0.05 mL . In the present invention, the time for a single spin coating is preferably 25-35 s, more preferably 28-32 s, and even more preferably 30 s. After each spin coating, the present invention preferably dries the wet film formed by spin coating, the drying method is preferably drying, and the drying temperature is preferably 70-85°C, more preferably 75-82°C, More preferably, it is 78-80°C; the drying time is preferably 1.5-3 minutes, more preferably 2-2.5 minutes, and most preferably 2 minutes. In the present invention, the spin coating is preferably performed in a dispenser.

In the present invention, the indium gallium zinc oxide thin film precursor solution is preferably coated under the above conditions, so that the indium gallium zinc oxide thin film precursor solution can be uniformly attached to the substrate, which is beneficial to obtain a thin film transistor with stable performance.

After the precursor film-substrate composite material is obtained, the present invention anneals the precursor film-substrate composite material to obtain the indium gallium zinc oxide thin film-substrate composite material. In the present invention, the temperature of the annealing is preferably 540-560°C, more preferably 545-555°C, and more preferably 550°C; the rate of heating up to the annealing temperature is preferably 3-6°C/min, more preferably It is 3.5-5.5 degreeC/min, more preferably 4-5 degreeC/min. In the present invention, the temperature is preferably increased to the annealing temperature at the above-mentioned rate, which can improve the formation rate of the indium gallium zinc oxide thin film on the basis of not affecting the uniform heating of the precursor film.

After heating to the annealing temperature, the present invention preferably conducts heat preservation at the annealing temperature, and the heat preservation time is preferably 1 to 1.5 h, more preferably 1 to 1.2 h, and still more preferably 1 h. In the present invention, the annealing is preferably performed in an annealing furnace.

In the present invention, the precursor film-substrate composite material is preferably annealed under the above conditions, so that organic impurities in the precursor solution, such as alcohol ether solvent and stabilizer, can be decomposed to generate indium gallium zinc oxide, thereby obtaining indium gallium zinc oxide thin film - Substrate composite.

After obtaining the indium gallium zinc oxide thin film-substrate composite material, the present invention further prepares electrodes on the indium gallium zinc oxide thin film-substrate composite material to obtain an indium gallium zinc oxide thin film transistor.

In the present invention, the preparation method of the electrode preferably includes:

The indium gallium zinc oxide thin film-substrate composite material is sequentially subjected to photolithography, development, film-fixing and corrosion; then the corroded composite material is sequentially overetched, developed and metallized to obtain an electrode.

In the present invention, the method of photolithography preferably includes: dripping photoresist onto the indium gallium zinc oxide thin film-substrate composite material, and then performing uniform glue, drying and etching in sequence. In the present invention, the photoresist is preferably a positive photoresist, more preferably a commercially available photoresist using diazo as a photosensitive compound and phenolic resin as a matrix material.

In order to uniformly coat the photoresist on the indium gallium zinc oxide thin film, the present invention preferably conducts the photoresist at a stepped rotational speed; the stepped rotational speed preferably includes a first-stage rotational speed, a second-stage rotational speed, and a third-stage rotational speed;

The speed of the rotation speed of the first stage is preferably 80-120r/min, more preferably 90-110r/min, and more preferably 100r/min; the time of glue mixing under the rotation speed of the first stage is preferably 1-3s, More preferably 2s;

The speed of the second-stage rotating speed is preferably 280-350 r/min, more preferably 290-320 r/min, and more preferably 300 r/min; under the second-stage rotating speed, the glue mixing time is preferably 4-6 s, More preferably 5s;

The speed of the rotational speed in the third stage is preferably 450-600 r/min, more preferably 470-550 r/min, and more preferably 500-540 r/min; under the rotational speed of the first stage, the glue-spreading time is preferably 25-500 r/min 35s, more preferably 28 to 30s.

After gluing, the present invention preferably dries the homogenized material to obtain a cured material suitable for photolithography; the drying temperature is preferably 80-90°C, more preferably 85-90°C; the time is preferably 4 to 6 minutes, more preferably 5 minutes.

After drying, the present invention preferably etches the dried material to form an active layer pattern; the etching time is preferably 13-16s, more preferably 15s.

After the etching, the present invention preferably develops the etched material, the developer for development preferably includes a sodium hydroxide solution, and the mass concentration of the sodium hydroxide solution is preferably 4 to 6‰, more preferably 5‰ ; The development time is preferably 6-8s, more preferably 7s.

After the development, the present invention preferably solidifies the material after the development; the temperature of the solid film is preferably 80-100°C, more preferably 85-90°C; the time required for the film-fixing is preferably 2-4min, More preferably, it is 2.5 to 3.5 minutes.

After the film is solidified, the present invention preferably corrodes the material after the solid film to remove the redundant active layer; the corrosive agent for corrosion is preferably a hydrochloric acid solution, and the mass concentration of the hydrochloric acid solution is preferably 2-3‰, More preferably, it is 2.3-2.5‰; the time for the corrosion is preferably 2-3s, preferably 3s.

After etching, in the present invention, the etched material is preferably cleaned to remove the photoresist; the cleaning agent preferably includes acetone.

The present invention has no special requirements for the specific implementations of photolithography, development, film-fixing, etching, and cleaning described in the above technical solutions, and those skilled in the art can be used.

After the etching, the present invention preferably sequentially performs overlay etching, development and aluminum plating on the etched composite material to obtain an indium gallium zinc oxide thin film transistor. In the present invention, the embodiment of the overlay is preferably the same as the photolithography method described in the above technical solution; the embodiment of the development is preferably the same as the development of the indium gallium zinc oxide film-substrate composite material in the above technical solution the same way. After development, the present invention preferably coats a metal film on the surface of the material after development; the thickness of the metal film is preferably an aluminum film of 100 nm. In the present invention, the metal film is preferably obtained by electron beam evaporation coating equipment. The present invention has no special requirements on the specific evaporation process, as long as the metal film of the thickness described in the above technical solution can be obtained.

After the metal film is plated, the present invention preferably cleans the material after the metal film to remove the excess metal film. In the present invention, the cleaning is preferably ultrasonic cleaning of acetone solution; the power of ultrasonic cleaning is preferably 80-150kW, more preferably 100-120kW; the time of ultrasonic cleaning is preferably 10-15s, more preferably 10s.

In the present invention, it is preferable to obtain a transistor with a bottom-gate top-contact structure using indium-gallium-zinc-oxide as an active layer by the above method.

In order to further illustrate the present invention, the methods for preparing different types of indium gallium zinc oxide thin film transistors provided by the present invention are described in detail below with reference to the accompanying drawings and examples, but they should not be construed as limiting the protection scope of the present invention.

Example 1

Mix indium nitrate, gallium nitrate and zinc acetate with 5 mL of ethylene glycol methyl ether to obtain a mixed solution with an indium ion concentration of 0.05 mol/L, a gallium ion concentration of 0.025 mol/L and a zinc ion concentration of 0.175 mol/L, and then 1.2 mL of ethanolamine and 0.3 mL of glacial acetic acid were added to the above mixture, then heated and stirred at 150 °C for 1 h. After stirring, the solution was allowed to stand for 24 h and filtered with a 0.2 μm filter. The filtrate obtained by filtration was indium gallium Zinc oxide film precursor solution;

A Si/SiO ₂ substrate with a size of 1.5 cm ² was selected, and acetone, absolute ethanol and deionized water were used to ultrasonically clean the substrate in sequence, and each cleaning was performed for 10 min, and it was set aside for use;

The indium gallium zinc oxide thin film precursor solution obtained above was spin-coated onto the substrate using a homogenizer, the amount of each spin-coating solution was 0.05mL, the spin-coating speed was 2500r/min, the time was 30s, and the film was formed each time. Spin-coating twice, after each spin-coating, place the spin-coated base composite material on a hot plate at 80° C. to dry for 2 min to obtain a precursor film-base composite material;

The obtained precursor film-substrate composite material was placed in an annealing furnace, and annealed at 550 °C for 1 h to obtain an indium gallium zinc oxide film-substrate composite material;

In the following manner, the indium gallium zinc oxide thin film-substrate composite material is prepared into an indium gallium zinc oxide thin film transistor:

First carry out the glue, put the indium gallium zinc oxide film-substrate composite material into the glue dispenser, drop the photoresist (commercial photoresist AZ 50XT) for glue glue, the speed and time of the glue dispenser are as follows: 100r/min , 2s; 300r/min, 5s; 500r/min, 5s; 3000r/min, 30s; put the photoresist-coated material into an oven at 90 °C for 5min, and then put the dried material into the photolithography machine for 15s photolithography; immerse the photolithographic material in a 5‰ sodium hydroxide solution for 7s for development; put the developed material in an oven at 90°C for 3min to solidify the film; After the film, the obtained material was immersed in a 2.5‰ hydrochloric acid solution for 3s to remove the excess active layer; finally, the corroded material was washed in an acetone solution to remove the photoresist;

After the photolithography of the active layer is completed, perform secondary photolithography: uniform glue, and then put the spin-coated photoresist material into an oven at 90 ° C to dry for 5 minutes, and then perform photolithography and development. The resulting material was placed in an electron beam evaporation coating equipment to evaporate an aluminum electrode with a thickness of 100 nm, and then placed in an acetone solution to be cleaned with an ultrasonic cleaner for about 10 s, and the excess aluminum metal film was peeled off to obtain an indium gallium zinc oxide thin film transistor.

Examples 2 to 8

The indium gallium zinc oxide thin film transistor is prepared according to the method of embodiment 1, the difference is that the amount of raw materials is different. The concentration of gallium ion, indium ion, gallium ion and zinc The molar ratios of the ions are listed in Table 1.

Using Agilent B1500A, a semiconductor tester, by applying different gate voltages (V _g ), selecting a certain range of source-drain voltage (V _d ), and testing the source-drain current (I _d ), the output curve of the thin film transistor is obtained; by applying different The source-drain voltage (V _d ), select a certain range of gate voltage (V _g ), test the source-drain current (I _d ) to obtain the transfer curve of the thin film transistor. Fig. 1 is the output curve of the indium gallium zinc oxide thin film transistor obtained in Examples 1-4. In Fig. 1, different gate voltages (Vg: 0-40V) are applied, the source-drain voltage (V _d ) is selected from 0-40V, and the test source The value of the leakage current (I _d ) can be seen from the curve in FIG. 1 that the gate voltage (V _g ) of the indium gallium zinc oxide thin film transistors obtained in Examples 1 to 4 has a good control effect on the source-drain current (I _d ).

Fig. 2 shows the transfer curves of the indium gallium zinc oxide thin film transistors obtained in Examples 1-4. During the test, different source-drain voltages (V _d : 0V-40V) were applied to both ends of the thin-film transistor device to be tested to obtain the source-drain current (I _d ) Transfer curve (I _d - V _g ) as a function of gate voltage (V _g ).

By applying different source-drain voltages (V _d : 0-40V), the test range of V _g is selected as -20-40V, and the threshold voltage (V _T ) of the thin film transistor is calculated. Fitting is performed according to the transfer curve I _d ^1/2 -V _g under the action of V _SD in the saturation region, and the intercept on the horizontal axis of I _d =0 is V _T .

Fig. 3 is when the source-drain voltage V _d is 30V, according to the test results of the corresponding transfer curves of the indium gallium zinc oxide thin film transistors obtained in Examples 1-4, and the threshold voltage (V _T ) is calculated according to I _d ^1/2 -V _g , the V _T of the indium gallium zinc oxide thin film transistors obtained in Examples 1 to 4 correspond to 12V, 8.6V, -2.8V and -3.8V respectively; the test results of other embodiments are listed in Table 1.

In the present invention, the device type is judged by the threshold voltage of the indium gallium zinc oxide thin film transistor. When the threshold voltage of the device is greater than 0V, it means that the positive V _g applied to the gate attracts the electrons in the semiconductor to the side of the semiconductor near the insulating layer. In the conduction channel, the device is in enhancement mode. When the threshold voltage of the device is less than 0V, it means that a negative V _g is required to repel the existing holes in the conductive channel and keep them away from the conductive channel. At the same time, the acceptor ions in the space charge region are ionized, so a negative charge appears in the conductive channel. when the device is in depletion mode. The threshold voltage calculation results of Examples 1 to 8 are listed in Table 1.

The present invention also calculates the switching ratios of the indium gallium zinc oxide thin film transistors obtained in Examples 1 to 8 according to the transfer curves, so as to characterize the switching performance of the indium gallium zinc oxide thin film transistors. Devices with high switching ratios have better stability and Anti-interference ability.

Table 1 Examples 1-8 Indium Gallium Zinc Oxide Thin Film Precursor Solutions Composition Characteristics and Test Results of Transistor Devices

From the content of Table 1, it can be seen that the method provided by the present invention can prepare different types of ions without changing other parameters and only adjusting the molar ratio of indium ions, gallium ions and zinc ions in the indium gallium zinc oxide precursor solution. The transistor has the advantages of simple method, strong controllability and easy popularization, and the method provided by the present invention can reduce the preparation cost of the transistor device.

In addition, the indium gallium zinc oxide thin film transistor obtained by the invention also has better switching performance and higher mobility.

It can be seen from the above examples that the present invention can obtain two different types of enhancement type and depletion type by adjusting the amount of indium ion, gallium ion and zinc ion in the indium gallium zinc oxide precursor solution and changing the molar ratio of the elements. Indium gallium zinc oxide thin film transistor; the obtained transistor has better switching performance and mobility, and has a wider application range. The solution provided by the invention has simple and effective preparation process, does not adversely affect the basic performance of the transistor, and is suitable for large-scale popularization and use.

Although the above embodiment has made a detailed description of the present invention, it is only a part of the embodiments of the present invention, rather than all the embodiments. People can also obtain other embodiments according to the present embodiment without creativity. These embodiments All belong to the protection scope of the present invention.

Claims (4)

1. A method for preparing different types of indium gallium zinc oxide thin film transistors comprises the following steps:

coating an indium gallium zinc oxide film precursor solution comprising indium salt, gallium salt, zinc salt, a stabilizer and an alcohol ether solvent on a substrate, and then sequentially drying and annealing to obtain an indium gallium zinc oxide film-substrate composite material;

preparing an electrode on the indium gallium zinc oxide thin film-substrate composite material to obtain an indium gallium zinc oxide thin film transistor;

when the indium-gallium-zinc-oxygen thin film transistor is prepared, an enhancement transistor or a depletion transistor is obtained by adjusting the molar ratio of indium ions, gallium ions and zinc ions in the precursor solution of the indium-gallium-zinc-oxygen thin film;

the indium salt comprises indium nitrate or indium acetate, the gallium salt comprises gallium nitrate or gallium acetate, and the zinc salt comprises zinc acetate or zinc nitrate;

in the indium gallium zinc oxide film precursor solution, the concentration of gallium salt is 0.02-0.03 mol/L;

when the molar ratio of indium ions, gallium ions and zinc ions in the indium-gallium-zinc-oxygen thin film precursor solution is (2-3) to 1 (6-7), obtaining an enhanced indium-gallium-zinc-oxygen thin film transistor;

when the molar ratio of the indium ions to the gallium ions to the zinc ions is (5-6) to (1) (3-4), obtaining a depletion type indium gallium zinc oxide thin film transistor; the stabilizer comprises ethanolamine and glacial acetic acid; the volume ratio of the ethanolamine to the alcohol ether solvent is 1-1.5: 5; the volume ratio of the glacial acetic acid to the alcohol ether solvent is 0.1-0.5: 5;

the annealing temperature is 500-600 ℃; and keeping the temperature for 0.5-1.5 h at the annealing temperature.

2. The method of claim 1, wherein the substrate comprises Si/SiO₂A substrate.

3. The method of claim 1, wherein the indium gallium zinc oxide thin film precursor solution is applied by spin coating at a speed of 2400-2600 r/min for 2 times for 25-35 s per spin coating.

4. The method of claim 1, wherein the electrode is prepared by a method comprising:

sequentially carrying out photoetching, developing, film fixing and corrosion on the indium gallium zinc oxide film-substrate composite material; and then sequentially carrying out alignment, development and metal film plating on the corroded composite material to obtain the indium gallium zinc oxide thin film transistor.

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