A method of substrate surface treatment and a printing method for thin film patterning

Abstract

This invention provides a method for substrate surface treatment and a method for thin film patterning printing, belonging to the field of surface treatment technology. The invention involves ultrasonically treating the substrate in a polar solvent, utilizing the ultrasonic waves to remove polar contaminants adhering to the substrate surface, resulting in a pre-treated substrate with high surface cleanliness. After the pre-treated substrate surface is dried with nitrogen to remove the polar solvent, it is left to stand in a sealed container. During this process, the surface of the pre-treated substrate continuously adsorbs non-polar molecules from the air, forming a monomolecular adsorption layer composed of multiple gas molecules. This adsorption layer has a stable surface free energy, effectively optimizing the surface free energy of the substrate. Because the substrate surface obtained using this method has a stable surface free energy, when used for thin film patterning printing, it can suppress excessive ink droplet diffusion, resulting in more uniform ink spreading on the substrate and achieving the desired printed pattern shape.

Description

Technical Field

[0001] This invention relates to the field of surface treatment technology, and more particularly to a method for substrate surface treatment and a method for printing thin film patterning. Background Technology

[0002] In recent years, TFTs (Thin Film Transistors) have received widespread attention and research as active-mode switching devices for liquid crystal displays and organic light-emitting diodes. Currently, the patterning between layers in thin film transistors uses traditional photolithography, which involves multiple steps such as exposure, development, etching, and cleaning. This process adds a complex and environmentally polluting patterning step. Inkjet printing, as a digitally controlled and cost-effective technology, can be used for precise material assembly without vacuum deposition of thin films and allows for the creation of customizable patterns on different substrates, making it suitable for patterning processes.

[0003] However, in inkjet printing, the wettability of the hydrophilic substrate surface has a significant impact on ink overspreading behavior. This is because an overly hydrophilic substrate leads to excessive ink spreading, which in turn affects the resolution of the printed pattern. Therefore, controlling the substrate surface wettability (surface free energy) to control ink overspreading behavior is of great importance for improving the resolution of thin film patterns. Currently, existing methods for adjusting the substrate surface free energy include spin-coating an ultrathin organic wetting layer suitable for the printed pattern to improve the substrate's hydrophilicity. For example, Chinese patent CN 202310445470.8 discloses a fingerprint-resistant modified glass and its process, specifically disclosing that a PE film is applied to the cleaned substrate glass using an automatic laminating machine to perform surface treatment on the substrate glass, thereby improving the surface energy of the substrate glass. Another example is Chinese patent CN 202010039729.5, which discloses a hydrophobic substrate and its preparation method, as well as an electronic screen and electronic device. This method utilizes atom transfer radical polymerization (ATRP) to graft a hydrophobic polymer layer onto the substrate to adjust its surface free energy. While this method can adjust the surface free energy of the substrate, it requires the introduction of a wetting layer, which introduces new impurities that negatively impact device performance. Furthermore, the introduction of a wetting layer increases costs. Additionally, some researchers have adjusted the surface structure of the substrate to regulate its surface energy. For example, Chinese patent CN 201710735820.9 discloses a superhydrophobic transparent glass and its preparation method; Chinese patent CN 201611179426.3 discloses a method for achieving controllable inversion of superhydrophilicity and superhydrophobicity of glass surface. Both methods adjust the structure of the glass surface to regulate the hydrophilicity or hydrophobicity of the substrate glass. However, these methods have the problems of relatively complex processes and high preparation costs.

[0004] Therefore, there is an urgent need to provide a surface treatment method that is simple to operate, low in cost, and can effectively stabilize the surface free energy of a substrate. Summary of the Invention

[0005] The purpose of this invention is to provide a surface treatment method that is simple to operate, low in cost, and can effectively stabilize the surface free energy of a substrate.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] This invention provides a method for substrate surface treatment, comprising the following steps:

[0008] (1) The substrate is placed in a polar solvent and subjected to ultrasonic treatment to obtain a pretreated substrate;

[0009] (2) After the pretreated substrate obtained in step (1) is dried by nitrogen, it is placed in a sealed container and left to stand to obtain a surface treated substrate; the atmosphere in the sealed container is air and the air humidity is 20-30%.

[0010] Preferably, the substrate in step (1) includes a glass substrate, a metal substrate, a silicon oxide substrate, or a silicon nitride substrate.

[0011] Preferably, the polar solvent in step (1) includes deionized water, ethanol, or acetone.

[0012] Preferably, the ultrasonic power of the ultrasonic treatment in step (1) is 35-60W.

[0013] Preferably, the ultrasonic treatment time is 10 to 15 minutes.

[0014] Preferably, the temperature inside the sealed container in step (2) is 23-27°C.

[0015] Preferably, the settling time in step (2) is 3 to 5 hours.

[0016] The present invention also provides a printing method for thin film patterning, comprising the following steps:

[0017] (a) The substrate is processed according to the substrate surface treatment method described in the above technical solution to obtain a surface-treated substrate;

[0018] (b) Place the surface-treated substrate obtained in step (a) on the printer table of the inkjet printer, move the nozzle of the inkjet printer to perform inkjet printing, and obtain a thin film pattern.

[0019] Preferably, the parameters for inkjet printing in step (b) include: the distance between the ink cartridge of the inkjet printer and the printer table is 900-1200 μm; and the jetting frequency of the inkjet printer nozzle is 1.5-10 kHz.

[0020] Preferably, the inkjet printing is performed line-by-line printing; the droplet spacing of the line-by-line printing is 20–40 μm.

[0021] This invention provides a method for substrate surface treatment, comprising the following steps: placing the substrate in a polar solvent and performing ultrasonic treatment to obtain a pretreated substrate; drying the pretreated substrate with nitrogen gas and then placing it in a sealed container for settling to obtain a surface-treated substrate; the atmosphere in the sealed container is air with a humidity of 20-30%. This invention utilizes the propagation of ultrasound in a polar solvent to cause the liquid particles to vibrate violently, removing polar contaminants adhering to the substrate surface, resulting in a high surface cleanliness of the pretreated substrate. After drying the pretreated substrate surface with nitrogen gas to remove the polar solvent, during settling in the sealed container, the surface of the pretreated substrate continuously adsorbs non-polar molecules (N2, O2, CO2, and Ar, etc.) from the air, forming a monomolecular adsorption layer composed of multiple gas molecules. This adsorption layer has a stable surface free energy, which can effectively optimize the surface free energy of the substrate. Because the substrate surface obtained by the method of this invention has a stable surface free energy, when used for thin film patterning printing, it can suppress excessive diffusion of ink droplets, making the ink spread more evenly on the substrate, thereby achieving an ideal shape for the printed pattern. The results of the embodiments show that after the substrate is treated with the method provided by the present invention, the surface free energy of the substrate after surface treatment is 43.63 mJ / m. 2 The surface free energy of the untreated substrate is 60.22 mJ / m². 2 It is evident that the method provided by the present invention can reduce the surface free energy of the substrate; after printing thin film patterning using a surface-treated substrate, the shape, outline and size of the printed pattern can be controlled more precisely. Attached Figure Description

[0022] Figure 1 The contact angles of the substrate used in Embodiment 1 of the present invention and the prepared surface-treated substrate;

[0023] Figure 2 A photograph of the pattern printed according to Embodiment 2 of the present invention;

[0024] Figure 3 This is a photograph of the printed pattern of Comparative Example 1 of the present invention. Detailed Implementation

[0025] This invention provides a method for substrate surface treatment, comprising the following steps:

[0026] (1) The substrate is placed in a polar solvent and subjected to ultrasonic treatment to obtain a pretreated substrate;

[0027] (2) After the pretreated substrate obtained in step (1) is dried by nitrogen, it is placed in a sealed container and left to stand to obtain a surface treated substrate; the atmosphere in the sealed container is air and the air humidity is 20-30%.

[0028] Unless otherwise specified, all reagents used in this invention are commercially available products commonly used in the field.

[0029] In this invention, the substrate is placed in a polar solvent and subjected to ultrasonic treatment to obtain a pretreated substrate.

[0030] In this invention, the substrate preferably includes a glass substrate, a metal substrate, a silicon oxide substrate, or a silicon nitride substrate; the glass substrate is made of ordinary glass or ITO conductive glass. The method provided by this invention can remove polar contaminants from the substrate surface and form a stable monomolecular adsorption layer, thus it is applicable to the above-mentioned types of substrates. This invention does not impose any special limitations on the size and type of the substrate; it can be selected as needed.

[0031] The present invention preferably involves first cleaning and drying the substrate. The present invention does not specify a particular method for cleaning and drying; any conventional method for cleaning the substrate is acceptable.

[0032] In this invention, the polar solvent preferably includes deionized water, ethanol, or acetone. Using these polar solvents during ultrasonic treatment in this invention is more beneficial for promoting the removal of polar contaminants adhering to the substrate surface under the action of ultrasound.

[0033] In this invention, the ultrasonic power of the ultrasonic treatment is preferably 35-60W, more preferably 35-50W; the ultrasonic treatment time is preferably 10-15min, more preferably 12-15min. Controlling the ultrasonic power and time within the above ranges in this invention is more conducive to thoroughly removing polar contaminants adhering to the substrate surface.

[0034] In this invention, the substrate after ultrasonic treatment is preferably removed from the polar solvent to obtain a pretreated substrate.

[0035] After obtaining the pretreated substrate, the present invention dries the pretreated substrate with nitrogen gas and places it in a sealed container for static treatment to obtain a surface-treated substrate.

[0036] This invention uses nitrogen blowing to dry the pre-treated substrate and prevent dust or other impurities from contaminating its surface. The invention does not specify a particular method for nitrogen blowing; any conventional method that can dry the pre-treated substrate surface is acceptable.

[0037] The present invention does not have a special limitation on the size of the sealed container. It can be adjusted according to the size of the pre-processed substrate, as long as it can accommodate the pre-processed substrate.

[0038] In this invention, the sealed container can prevent the surface of the substrate from being contaminated during the resting process.

[0039] In this invention, the atmosphere inside the sealed container is air. Air contains various gas molecules, and because impurities on the pretreated substrate are thoroughly removed, it has a strong adsorption effect on gas molecules (N2, O2, CO2, and Ar, etc.) in the air, thus adsorbing gas molecules and forming a monomolecular adsorption layer on the surface of the pretreated substrate.

[0040] In this invention, the air humidity is 20-30%, preferably 20-25%. When the air humidity is within the above range, the presence of moisture in the air can prevent the pre-treated substrate from affecting the adsorption of gas molecules.

[0041] In this invention, the temperature inside the sealed container is preferably 23–27°C, more preferably 25–27°C; the settling time is preferably 3–5 hours, more preferably 4–5 hours. By controlling the temperature inside the sealed container and the settling time within the above ranges, this invention enables the surface of the pretreated substrate to be fully covered by a monolayer of gas molecules.

[0042] The method provided by this invention is simple to operate, low in cost, and can effectively optimize the surface free energy of the substrate because the monomolecular adsorption layer has a stable surface free energy.

[0043] The present invention also provides a printing method for thin film patterning, comprising the following steps:

[0044] (a) The substrate is processed according to the substrate surface treatment method described in the above technical solution to obtain a surface-treated substrate;

[0045] (b) Place the surface-treated substrate obtained in step (a) on the printer table of the inkjet printer, move the nozzle of the inkjet printer to perform inkjet printing, and obtain a thin film pattern.

[0046] The present invention processes the substrate according to the substrate surface treatment method described in the above technical solution to obtain a surface-treated substrate.

[0047] In this invention, the method for surface treatment of the substrate is the same as that described above, and will not be repeated here.

[0048] After obtaining the surface-treated substrate, the present invention places the surface-treated substrate on the printer table of an inkjet printer, moves the nozzle of the inkjet printer to perform inkjet printing, and obtains a thin film pattern.

[0049] This invention does not specify a particular model of inkjet printer; any conventional inkjet printer can be used. In this invention, the inkjet printer is preferably a Dimatix 2850 series piezoelectric inkjet printer.

[0050] In this invention, the preferred parameters for inkjet printing include: the distance between the ink cartridge and the printer stage is preferably 900–1200 μm, more preferably 1000–1200 μm; the ejection frequency of the inkjet printer nozzle is preferably 1.5–10 kHz, more preferably 2.5–10 kHz; the inkjet printing preferably employs line-by-line printing; and the droplet spacing in line-by-line printing is preferably 20–40 μm, more preferably 30–40 μm. Controlling the inkjet printing parameters within the above ranges in this invention is more conducive to controlling the shape of the pattern.

[0051] This invention does not impose any particular limitation on the ink used for inkjet printing; any conventional ink can be used. In this invention, the preferred method for preparing the ink includes: dissolving hafnium chloride octahydrate and aluminum sec-butoxide in a solvent to obtain the ink (referred to as HAO solution).

[0052] In this invention, the solvent is preferably a mixed solution of ethylene glycol methyl ether, ethylene glycol, and glycerol, and the volume ratio of ethylene glycol methyl ether, ethylene glycol, and glycerol is preferably (5-10):(0-5):(0-5), more preferably 7:1:2. The solvents used in this invention are alcohol ether solvents or alcohol solvents, and are all polar solvents, making it easier to control the pattern morphology on the surface-treated substrate.

[0053] In this invention, the molar ratio of hafnium chloride octahydrate to aluminum sec-butoxide is preferably (1-2):(0.5-1), more preferably 2:1. In this invention, the solute concentration in the ink is preferably 0.05-0.1 mol / L, more preferably 0.07-0.1 mol / L. In this invention, when the ink concentration is within the above range, the viscosity of the prepared dielectric layer ink is 6.46 cP, and the ink tension is 34.55 mN / m, making it easier to control the pattern morphology on the surface-treated substrate.

[0054] The surface treatment method provided by this invention produces a surface-treated substrate with a monomolecular adsorption layer. This adsorption layer has a stable surface free energy, which can effectively control the spreading of ink on the substrate, thus making it more conducive to achieving the ideal shape of the printed pattern during thin film patterning printing.

[0055] 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.

[0056] Example 1

[0057] A method for surface treatment of a substrate, comprising the following steps:

[0058] (1) The substrate (ordinary glass substrate) is cleaned and dried in sequence with pure acetone, alcohol and deionized water, then placed in deionized water and sonicated for 15 minutes (at power), and then taken out to obtain the pretreated substrate.

[0059] (2) After the pretreated substrate obtained in step (1) is dried by nitrogen, it is placed in a sealed container at a temperature of 25°C and left to stand for 5 hours to obtain a surface treated substrate; the atmosphere in the sealed container is air and the air humidity is 20%.

[0060] Example 2

[0061] A method for surface treatment of a substrate, comprising the following steps:

[0062] (1) The substrate (ITO conductive glass substrate) was cleaned and dried with pure acetone, alcohol and deionized water, then placed in deionized water and sonicated for 15 minutes (at power) before being taken out to obtain the pretreated substrate.

[0063] (2) After the pretreated substrate obtained in step (1) is dried by nitrogen, it is placed in a sealed container at a temperature of 25°C and left to stand for 5 hours to obtain a surface treated substrate; the atmosphere in the sealed container is air and the air humidity is 20%.

[0064] Example 3

[0065] A method for surface treatment of a substrate, comprising the following steps:

[0066] (1) The substrate (silicon oxide substrate) was cleaned and dried with pure acetone, alcohol and deionized water, then placed in deionized water and sonicated for 15 minutes (at power) before being taken out to obtain the pretreated substrate.

[0067] (2) After the pretreated substrate obtained in step (1) is dried by nitrogen, it is placed in a sealed container at a temperature of 25°C and left to stand for 5 hours to obtain a surface treated substrate; the atmosphere in the sealed container is air and the air humidity is 20%.

[0068] Test Example 1

[0069] The contact angles of the substrate used in Example 1 and the prepared surface-treated substrate were tested using the seated drop method. The test method employed three solvents: 1. deionized water (DI water), 2. ethylene glycol (EG), and 3. HAO solution (Ink). Contact angle tests were conducted on substrates with two different surface free energies. The test results... Figure 1 As shown. Using the Owens-Wendt (OW) formula, the surface free energy of the untreated substrate was calculated to be 60.22 mJ / m based on the contact angles of the first two solvents (deionized water and ethylene glycol). 2 The surface free energy was reduced to 43.63 mJ / m after surface treatment. 2 The hydrophobicity is appropriately increased.

[0070] Example 4

[0071] (a) A surface-treated substrate was prepared using the method of Example 1;

[0072] (b) A Dimatix 2850 series piezoelectric inkjet printer was used, with HAO solution as the printing ink material. The inkjet printing conditions were: nozzle and printer stage temperatures at room temperature; ink cartridge distance to printer stage set at 1000 μm; ejection frequency at 2.5 kHz; the designed printable graphic was a square pattern with sides of 500 μm, printed line by line with a droplet spacing of 30 μm; the printed pattern is shown below. Figure 2 As shown.

[0073] Comparative Example 1

[0074] The difference from Example 4 is that in step (b), the untreated substrate (i.e., ordinary glass) from Example 1 is used instead of the surface-treated substrate; the remaining steps and parameters are the same as in Example 4; the printed pattern result is as follows: Figure 3 As shown.

[0075] from Figure 2 and Figure 3 As can be seen, printing a square pattern on ordinary glass results in further diffusion and overflow of excess material based on the designed printed pattern. However, the pattern printed on the surface-treated substrate obtained by the surface treatment method provided in this invention allows for more precise control over the shape, outline, and size of the printed pattern, achieving the desired design result. This is because the processing method provided in this invention can form a monomolecular adsorption layer on the substrate surface, possessing stable surface free energy. The reduced surface free energy and increased hydrophobicity of the substrate suppress further ink diffusion, thus enabling more precise control over the shape of the printed pattern.

[0076] 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. A method for printing patterned thin films, comprising the following steps: (a) The substrate is processed according to the substrate surface treatment method to obtain a surface-treated substrate; (b) Place the surface-treated substrate obtained in step (a) on the printer table of the inkjet printer, move the nozzle of the inkjet printer to perform inkjet printing, and obtain a thin film pattern. The method for preparing the ink used in inkjet printing includes: dissolving hafnium chloride octahydrate and aluminum sec-butoxide in a solvent to obtain the ink; The solvent is a mixed solution composed of ethylene glycol methyl ether, ethylene glycol and glycerol; The method for surface treatment of the substrate includes the following steps: (1) The substrate is placed in a polar solvent and subjected to ultrasonic treatment to obtain a pretreated substrate; (2) After the pretreated substrate obtained in step (1) is dried by nitrogen, it is placed in a sealed container and left to stand to obtain a surface treated substrate; the atmosphere in the sealed container is air and the air humidity is 20~30%. The ultrasonic power of the ultrasonic treatment in step (1) is 35~60W; the temperature inside the sealed container in step (2) is 23~27℃; and the settling time in step (2) is 3~5h.

2. The thin film patterning printing method according to claim 1, characterized in that, The parameters for inkjet printing in step (b) include: the distance between the ink cartridge and the printer table is 900~1200μm; the ejection frequency of the inkjet printer nozzle is 1.5~10kHz.

3. The thin film patterning printing method according to claim 2, wherein The inkjet printing uses line-by-line printing; the droplet spacing in the line-by-line printing is 20~40μm.

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