Ink for preparing semiconductor film, semiconductor film and preparation method thereof

Abstract

The invention provides ink for preparing a semiconductor film, the semiconductor film and a preparation method of the semiconductor film, and belongs to the field of semiconductors. The invention provides ink for preparing a semiconductor film. The ink comprises the following components: indium salt, polyethylene glycol, a surfactant and an inorganic solvent, the molecular weight of the polyethylene glycol ranges from 20000 to 50000, or the molecular weight of the polyethylene glycol ranges from 1000000 to 5000000; when the molecular weight of the polyethylene glycol is 20000-50000, the mass of the polyethylene glycol is 1% of the mass of the indium nitrate; and when the molecular weight of the polyethylene glycol is 1000000-5000000, the mass of the polyethylene glycol is 1-2% of the mass of the indium nitrate. A weak coordinate bond is formed by an ether oxygen group of PEG and In < 3 + >, hydrolytic agglomeration of indium salt is inhibited, the dispersed state and ordered structure of indium oxide nanocrystals are regulated and controlled, and the carrier mobility is improved by adjusting the molecular weight and dosage of polyethylene glycol.

Description

Technical Field

[0001] This invention relates to the field of semiconductors, and more specifically to inks for preparing semiconductor thin films, semiconductor thin films, and methods for preparing the same. Background Technology

[0002] Currently, metal oxide semiconductors (such as indium oxide) are widely considered to be the core material for the active layer of TFT arrays in the flat panel display field due to their high carrier mobility, excellent optical transmittance, and chemical stability. However, pure indium oxide thin films still suffer from low carrier mobility in practical applications: when pure indium oxide materials are deposited using a sol-gel system, the resulting films often contain a large number of disordered grain boundaries and defects (such as oxygen vacancies and metal ion vacancies), which leads to severe grain boundary scattering and trapped state capture during carrier transport, making it difficult to meet the fast response speed requirements of high-resolution displays. Summary of the Invention

[0003] This invention provides an ink for preparing semiconductor thin films, a semiconductor thin film, and a method for preparing the same. The semiconductor thin film prepared using the ink of this invention has high carrier mobility.

[0004] This invention provides an ink for preparing semiconductor thin films, comprising the following components: Indium salts, polyethylene glycol, surfactants, and inorganic solvents; The molecular weight of the polyethylene glycol is 20,000 to 50,000 or 1,000,000 to 5,000,000. When the molecular weight of the polyethylene glycol is 20,000 to 50,000, the mass of the polyethylene glycol is 1% of the mass of indium nitrate; When the molecular weight of the polyethylene glycol is 1,000,000 to 5,000,000, the mass of the polyethylene glycol is 1 to 2% of the mass of indium nitrate.

[0005] Preferably, the indium salt comprises indium nitrate.

[0006] Preferably, the concentration of indium salt in the ink is 0.1~0.3 mol / L.

[0007] Preferably, the surfactant includes surfactant FSO.

[0008] Preferably, the mass of the surfactant is 0.1 to 0.2% of the total mass of the indium salt, polyethylene glycol, and inorganic solvent.

[0009] Preferably, the inorganic solvent includes water.

[0010] The present invention also provides a method for preparing a semiconductor thin film, comprising the following steps: The ink described in the above technical solution is coated onto a substrate to form a film. The resulting wet film is then heat-treated to generate amorphous indium oxide and indium oxide nanocrystals, thus obtaining the semiconductor thin film.

[0011] Preferably, the heat treatment temperature is 200~250℃ and the time is 30min.

[0012] The present invention also provides a semiconductor thin film prepared by the preparation method described in the above technical solution.

[0013] The present invention also provides a TFT device, comprising the semiconductor thin film described above and an electrode located on the semiconductor thin film.

[0014] This invention utilizes the ether group of polyethylene glycol (PEG) and In 3+ By forming weak coordination bonds, the hydrolysis and aggregation of indium salt are suppressed, and the dispersion state and ordered structure of indium oxide nanocrystals are regulated. Furthermore, the carrier mobility is improved by adjusting the molecular weight and amount of polyethylene glycol. This invention overcomes the bottleneck of electrical performance in solution-processed pure indium oxide thin films through an inorganic / polymer composite system.

[0015] Furthermore, by controlling the molecular weight and concentration of polyethylene glycol, this invention can effectively control the morphology and dispersion state of indium oxide nanocrystals in the film, thereby constructing a continuous carrier transport channel and forming an amorphous indium oxide / indium oxide nanocrystal composite structure. The structural characteristics of the amorphous indium oxide / indium oxide nanocrystal composite effectively improve the carrier migration efficiency.

[0016] Furthermore, this invention uses deionized water as the main solvent to replace the toxic organic solvents used in traditional organometallic precursors, thereby reducing VOC emissions; PEG has high biocompatibility and is easily degradable, avoiding the risk of heavy metal pollution, and the ink preparation process has a low environmental impact.

[0017] Furthermore, this invention completes indium oxide crystallization at a low temperature of 200~250℃, eliminating the need for high-temperature annealing (>300℃), effectively reducing energy consumption, and is compatible with flexible plastic substrates (such as PI, PET), expanding the application scenarios of the device.

[0018] Therefore, this invention achieves high mobility (>4 cm⁻¹) through the synergistic effect of PEG and indium oxide. 2 / V·s, compared to pure indium oxide TFTs (approximately 0.9 cm⁻¹). 2 ( / V·s), significantly improved), high on / off ratio (>10) 7 While achieving core electrical properties such as [insert specific properties here], it also enables environmentally friendly ink preparation and low-energy film formation, providing technical support for the green manufacturing of semiconductor thin films and the application of flexible electronic devices. Attached Figure Description

[0019] Figure 1 The mobility curves of the TFT devices prepared in Examples 1-2 and Comparative Examples 1-2 are shown as a function of polymer mass fraction. Figure 2 The transfer characteristic curves are for composite TFT devices with different combinations of polyethylene glycol molecular weight and mass fraction. Detailed Implementation

[0020] This invention provides an ink for preparing semiconductor thin films, comprising the following components: Indium salts, polyethylene glycol, surfactants, and inorganic solvents; The molecular weight of the polyethylene glycol is 20,000 to 50,000 or 1,000,000 to 5,000,000. When the molecular weight of the polyethylene glycol is 20,000 to 50,000, the mass of the polyethylene glycol is 1% of the mass of indium nitrate; When the molecular weight of the polyethylene glycol is 1,000,000 to 5,000,000, the mass of the polyethylene glycol is 1 to 2% of the mass of indium nitrate.

[0021] The ink provided by this invention comprises an indium salt, preferably indium nitrate, more preferably indium nitrate hexahydrate; the concentration of the indium salt in the ink is preferably 0.1~0.3 mol / L, and in specific embodiments of this invention it can be 0.15 mol / L, 0.2 mol / L or 0.25 mol / L. The ink provided by this invention comprises polyethylene glycol (PEG), wherein the molecular weight of PEG is 20,000-50,000 or 1,000,000-5,000,000; when the molecular weight of PEG is 20,000-50,000, the mass of PEG is 1% of the mass of indium nitrate; when the molecular weight of PEG is 1,000,000-5,000,000, the mass of PEG is 1-2% of the mass of indium nitrate. PEG can regulate the ink viscosity, is compatible with printing processes such as spin coating and inkjet printing, and acts as a film-forming aid during spin coating to promote the leveling of the liquid film, avoiding fluctuations in electrical properties caused by uneven film thickness after curing. Furthermore, the presence of PEG also acts as a physical barrier, affecting the oxide lattice structure and thus generating an amorphous phase in some areas; in addition, the molecular weight of PEG selected in this invention, and by adjusting its dosage, achieves a good nanocrystalline morphology and a good relative distribution of nanocrystalline and amorphous phases, improving carrier migration efficiency.

[0022] The ink provided by the present invention comprises a surfactant, preferably a surfactant FSO, wherein the mass of the surfactant is preferably 0.1 to 0.2% of the total mass of the indium salt, polyethylene glycol and inorganic solvent.

[0023] The ink provided by the present invention comprises an inorganic solvent, which preferably includes water.

[0024] The present invention also provides a method for preparing a semiconductor thin film, comprising the following steps: The ink described in the above technical solution is coated onto a substrate to form a film. The resulting wet film is then heat-treated to generate amorphous indium oxide and indium oxide nanocrystals, thus obtaining the semiconductor thin film.

[0025] Before coating, the substrate is preferably cleaned and dried.

[0026] In this invention, the substrate preferably comprises glass with a Mo thin film and a SiOx / SiNx composite dielectric thin film stacked on its surface; the Mo thin film is preferably in contact with the glass phase.

[0027] In this invention, the coating preferably includes spin coating, and the spin coating speed is preferably 3000~5000 rpm, and the time is preferably 25~40s.

[0028] In this invention, the heat treatment temperature is preferably 200~250℃ and the time is 30min. In specific embodiments of this invention, the heat treatment temperature can be 210℃, 220℃, 230℃ or 240℃.

[0029] The present invention also provides a semiconductor thin film prepared by the preparation method described in the above technical solution.

[0030] The present invention also provides a TFT device, comprising the semiconductor thin film described above and an electrode located on the semiconductor thin film.

[0031] The following detailed description, in conjunction with embodiments, of the ink for preparing semiconductor thin films, the semiconductor thin films, and the preparation method thereof provided by the present invention, should not be construed as limiting the scope of protection of the present invention.

[0032] Indium nitrate hydrate, analytical grade, purity ≥99.0%; Polyethylene glycol with molecular weights of 4,000, 35,000, 100,000 and 5,000,000; Deionized water; Fluorocarbon surfactant FSO.

[0033] The methods for preparing the composite semiconductor thin films and devices in the examples and comparative examples are as follows: Step 1: Cleaning the substrate and container Cleaning the finger bottles and magnetic rotor: Unscrew the caps of the finger bottles to be cleaned and immerse them in a large beaker containing deionized water. Place the caps and magnetic rotor in the beaker as well, ensuring the bottle is completely filled with water and free of air bubbles. Then, ultrasonically vibrate for 20 minutes, followed by another 20 minutes with anhydrous ethanol. When using tweezers to transfer the bottles, avoid touching the inner walls of the bottles. After cleaning, place the bottles and rotor in an oven to dry.

[0034] Substrate cleaning: 10mm substrate A 10mm glass slide with a pre-formed Mo thin film and SiO2 on its surface. x / SiN x Composite dielectric film (substrate purchased from Guangzhou New Vision Co., Ltd.). The substrate to be cleaned was sequentially placed into a beaker containing alkaline cleaning solution, deionized water, and ethanol for ultrasonic vibration, with each cleaning lasting 20 minutes. After cleaning, it was placed in an oven to dry.

[0035] Step 2: Solution preparation The solvent used is deionized water. Indium nitrate hydrate is added and the mixture is magnetically stirred for 10 minutes to dissolve it. Then, polyethylene glycol with mass fractions of 0%, 1%, 2%, 3%, 4%, and 5% of indium nitrate hydrate is added, and the mixture is stirred at room temperature for 30 minutes to ensure complete dissolution. Finally, 0.1% of the solution of fluorocarbon surfactant FSO is added, and the mixture is magnetically stirred for 5 minutes to ensure homogeneity, yielding the ink (the concentration of indium nitrate in the ink is 0.1 mol / L).

[0036] Step 3: Fabrication of composite semiconductor thin films and devices The prepared ink was spin-coated onto the cleaned substrate at a speed of 5000 rpm for 30 seconds, resulting in a thickness of 5 nm. After spin-coating, the substrate was placed on a hot plate and heated at 215°C for 30 minutes to allow the film to fully cure.

[0037] Comparative Example 1 The method for preparing the composite semiconductor thin film is as described above, wherein the molecular weight of polyethylene glycol is 4000.

[0038] Example 1 The method for preparing the composite semiconductor thin film is as described above, wherein the molecular weight of polyethylene glycol is 35,000.

[0039] Comparative Example 2 The method for preparing the composite semiconductor thin film is as described above, wherein the molecular weight of polyethylene glycol is 100,000.

[0040] Example 2 The method for preparing the composite semiconductor thin film is as described above, wherein the molecular weight of polyethylene glycol is 5,000,000.

[0041] A pair of Mo electrodes were fabricated on the semiconductor thin films prepared in Examples 1-2 and Comparative Examples 1-2 using a vacuum sputtering apparatus and a mask to obtain thin film transistor devices for testing the performance of composite semiconductor thin films.

[0042] The output and transfer characteristics of TFT devices were analyzed using a semiconductor parameter analyzer.

[0043] Figure 1 The migration rate of the TFT devices prepared in Examples 1-2 and Comparative Examples 1-2 varies with the polymer mass fraction. Figure 1 In the text, (a) to (d) represent Comparative Example 1, Example 1, Comparative Example 2, and Example 2, respectively.

[0044] Depend on Figures 1-2 It is known that the mobility of composite TFT devices is highly correlated with the molecular weight and amount of polymer. Only under certain combinations of molecular weight and amount parameters can the performance be better than that of pure indium oxide devices. Under other parameters, the blocking effect of polymer on the indium oxide structure is more significant, which is reflected in the decline of device performance.

[0045] When the molecular weight of polyethylene glycol is 35,000 and the mass fraction is 1%, ( Figure 2 In (a), the mobility of the composite TFT reaches 4.3 cm⁻¹. 2 / V·s, the on / off ratio (Ion / Ioff) reaches 10. 7 The molecular weight of polyethylene glycol is 5,000,000, and its mass fraction is 1%. Figure 2 (b) and 2% Figure 2 In (c) mode, the mobility of the composite TFT reaches 1.4 cm⁻¹. 2 / V·s and 2.1 cm 2 / V·s, the on / off ratio (Ion / Ioff) both reach 10. 7 Overall, TFT devices fabricated from composite semiconductor thin films basically meet the electrical performance requirements of TFT arrays for flat panel displays.

[0046] Figure 2 The transfer characteristic curves are for composite TFT devices with different combinations of polyethylene glycol molecular weight and mass fraction. Figure 2 In the diagram, (a) represents a molecular weight of 35,000 & 1%, (b) represents a molecular weight of 5,000,000 & 1%, and (c) represents a molecular weight of 5,000,000 & 2%.

[0047] 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 ink for preparing semiconductor thin films, characterized in that, Includes the following components: Indium salts, polyethylene glycol, surfactants, and inorganic solvents; The molecular weight of the polyethylene glycol is 20,000 to 50,000 or 1,000,000 to 5,000,000. When the molecular weight of the polyethylene glycol is 20,000 to 50,000, the mass of the polyethylene glycol is 1% of the mass of indium nitrate; When the molecular weight of the polyethylene glycol is 1,000,000 to 5,000,000, the mass of the polyethylene glycol is 1 to 2% of the mass of indium nitrate.

2. The ink according to claim 1, characterized in that, The indium salt includes indium nitrate.

3. The ink according to claim 1 or 2, characterized in that, The concentration of indium salt in the ink is 0.1~0.3 mol / L.

4. The ink according to claim 1, characterized in that, The surfactant includes surfactant FSO.

5. The ink according to claim 1 or 4, characterized in that, The mass of the surfactant is 0.1 to 0.2% of the total mass of the indium salt, polyethylene glycol, and inorganic solvent.

6. The ink according to claim 1, characterized in that, The inorganic solvent includes water.

7. A method for preparing a semiconductor thin film, characterized in that, Includes the following steps: The ink described in any one of claims 1 to 6 is coated onto a substrate to form a film, and then the resulting wet film is heat-treated to generate amorphous indium oxide and indium oxide nanocrystals, thereby obtaining the semiconductor thin film.

8. The preparation method according to claim 7, characterized in that, The heat treatment is performed at a temperature of 200~250℃ for 30 minutes.

9. The semiconductor thin film prepared by the preparation method according to claim 7 or 8.

10. A TFT device, characterized in that, It includes the semiconductor thin film of claim 9 and the electrode located on the semiconductor thin film.

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