A spacer stripe-shaped flexible substrate and a method for manufacturing the same

Abstract

The present application belongs to the field of flexible OLED design, and particularly relates to a spaced stripe-shaped flexible substrate and a preparation method thereof. The preparation method comprises the following steps: preparing a PI mixed solution, uniformly applying the PI mixed solution on a substrate, performing laser irradiation on the PI mixed solution on the dried substrate, adjusting the laser beam path to make the PI form spaced stripes, and obtaining the spaced stripe-shaped flexible substrate. The present application performs patterning on the PI substrate by laser. The stripe-shaped substrate structure proposed in the present application can control the stress displacement distribution in the stretching process, concentrate the deformation displacement distribution in the wire connection area, and relieve the deformation borne by the display device. The present application further proposes the fabrication of a thin film transistor TFT on the spaced stripe-shaped flexible substrate. Based on the obtained thin film transistor TFT, the stretching resistance performance can be quantified by measuring the threshold voltage offset before and after stretching 0.5 times displacement, and the on-off ratio electrical performance.

Description

[Technical Field]

[0001] This invention belongs to the field of flexible OLED design, specifically relating to a flexible substrate with spaced stripes and its preparation method. [Background Technology]

[0002] In the information age, flexible display technology has received increasing attention to meet the screen requirements in various scenarios. However, in daily use, flexible displays inevitably experience mechanical stress and stretching during bending, which can lead to issues such as wire breakage and TFT failure after prolonged use.

[0003] Currently, various technical solutions exist for stretchable wires, such as stretchable conductive films and wire structures with special structural morphologies. In 2011, Bao et al.'s team at Stanford University proposed a stretchable conductive film of carbon nanotubes (CNTs) that could be directly sprayed and deposited on a substrate. Although the resistance was affected by stretching, it exhibited good fracture resistance. Their 2017 proposal of poly(3,4-ethylenedioxythiophene) (PEDOT) conductive material maintained stable conductivity even with a stretching of up to 600%. However, for TFTs, their structure is more complex than that of wires and sensors. Multilayer film structures have significantly different elastic moduli, making it difficult to improve them through materials or structural modifications.

[0004] In 2014, Jeong et al. from Yonsei University in South Korea reported a polymer transistor with high stretchability based on an electrospun fiber structure. Although it has a high hole mobility when the stretch strain is 70%, the presence of the fibrous substrate causes defect contact at the interfaces of the functional layer during mechanical stretching, which seriously affects the stability of the device and results in a high subthreshold swing and off-state current. [Summary of the Invention]

[0005] This invention proposes a flexible substrate with spaced stripes and its preparation method, which solves the problem in the prior art that mechanical stretching will seriously affect the stability of the device and further lead to the device having a high subthreshold swing and off-state current.

[0006] This invention provides

[0007] A method for preparing a flexible substrate with spaced stripes includes:

[0008] Step 1: Dissolve YS-20 molding powder completely in N-methylpyrrolidone, and heat and stir to obtain a mixture; spin-coat the mixture onto the surface of the substrate, and dry the substrate after coating.

[0009] Step 2: After the mixture on the substrate is completely cured, it is annealed by laser irradiation. The laser beam path is adjusted to form equally spaced stripes on the substrate, and the substrate is cooled to obtain a flexible substrate with spaced stripes.

[0010] Preferably, the annealing wavelength of the laser in step 2 is 330nm, the scanning speed is greater than 50mm / s and less than 500mm / s, and the power is greater than 7W and less than 9W.

[0011] Preferably, step 3 is also included, specifically:

[0012] The flexible substrate with alternating stripes was ultrasonically cleaned in deionized water, acetone, isopropanol, and deionized water. After cleaning, the substrate was dried.

[0013] Preferably, step 4 is also included, specifically:

[0014] A water vapor barrier layer is prepared on the substrate, specifically as follows:

[0015] A moisture barrier layer was prepared on a substrate using PECVD under an environment with an air pressure of 800 Pa, a background temperature of 100 °C, a SiH4 to N2O flow ratio of 320:560, and an N2 flow rate of 400 sccm.

[0016] Preferably, the thickness of the water vapor barrier layer is 300 nm. Preferably, the method further includes step 5, preparing an IGZO layer on the substrate to obtain a substrate with an IGZO layer;

[0017] Source and drain electrodes and interconnecting lines are fabricated on a substrate with an IGZO layer to obtain a substrate with interconnecting lines.

[0018] A gate insulating layer is prepared on a substrate with connection lines to obtain a substrate with a gate insulating layer.

[0019] A thin-film transistor (TFT) is obtained by depositing a gate electrode and a wire connection layer on a substrate with a gate insulating layer.

[0020] Preferably, the preparation of the gate insulating layer specifically involves:

[0021] The gate insulating layer was prepared using PECVD process under the following conditions: pressure of 800 Pa, background temperature of 100 °C, flow ratio of SiH4 to N2O of 320:560, and flow rate of N2 of 400 sccm.

[0022] The thickness of the gate insulating layer is 150 nm.

[0023] A flexible substrate with spaced stripes, comprising:

[0024] Substrate, cured PI;

[0025] The substrate, cured PI, SiO2 filling layer, moisture barrier layer, IGZO layer, connection line layer, gate insulation layer and wire connection layer are fixedly connected in sequence.

[0026] The cured PI includes a high Young's modulus region and a low Young's modulus region, which are equally spaced on the substrate.

[0027] Preferably, it also includes a SiO2 filling layer, a moisture barrier layer, an IGZO layer, a connection layer, a gate insulation layer, and a wire connection layer;

[0028] The SiO2 filling layer, water vapor barrier layer, IGZO layer, connection line layer, gate insulation layer and conductor connection layer are fixedly connected in sequence, and the SiO2 filling layer is connected to the cured PI.

[0029] Preferably, the cured PI elastic modulus in the low Young's modulus region is 5.61 GPa; and the cured PI elastic modulus in the high Young's modulus region is 9.39 GPa.

[0030] Compared with the prior art, the present invention can achieve the following technical effects:

[0031] This invention proposes a method for fabricating a striped flexible substrate. By using laser to pattern a PI substrate on the substrate, a striped substrate structure is formed that allows for control of stress displacement distribution during the stretching process. This structure can be used in the fabrication of circuit devices to alleviate the deformation experienced by display devices. Based on the above method, a striped flexible substrate is proposed that utilizes the principle that the elastic modulus of PI before and after irradiation differs by nearly double to protect key circuit components.

[0032] In this invention, after the preparation of a spaced striped flexible substrate, a thin-film transistor (TFT) is fabricated on the spaced striped flexible substrate. Based on the obtained TFT, the tensile strength can be quantified by measuring the shift of the threshold voltage and the switching ratio electrical performance before and after a 0.5-fold stretching displacement.

[0033] Compared with traditional mechanical property improvement methods such as chemical modification and multilayer film modification, the above-mentioned laser preparation method has high processing precision, low cost, simple process, easy reproduction and large-scale preparation. At the same time, it can perform quantitative testing of tensile properties, making it easy to supervise and verify product quality.

[0034] Of course, any product implementing this invention does not necessarily need to achieve all of the technical effects described above at the same time. [Attached Image Description]

[0035] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of a process for fabricating a flexible substrate with spaced stripes.

[0037] Figure 2 This is a schematic diagram of the laser beam scanning path;

[0038] Figure 3 This is a schematic diagram of the finished product;

[0039] Figure 4 This is a comparison image before and after lateral stretching.

Detailed Implementation Methods

[0040] To better understand the technical solution of the present invention, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0041] It should be understood that the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0042] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0043] like Figure 1 As shown, the present invention provides a method for preparing a flexible substrate with spaced stripes, the specific steps of which are as follows:

[0044] Step 1: Add YS-20 molding powder (fusible polyimide) to N-methylpyrrolidone, ensuring that the YS-20 molding powder is completely dissolved in N-methylpyrrolidone, and heat and stir to obtain a mixture; spin-coat the mixture onto the surface of the substrate, and dry the substrate after coating.

[0045] Step 2: After the mixture on the substrate has completely cured, anneal it using laser irradiation. Adjust the laser beam extension curve path for scanning to ensure that evenly spaced stripes are formed on the substrate, such as... Figure 2As shown, PI substrate regions with different carbonization degrees are prepared, and the substrate is cooled. After the substrate is cooled, a flexible substrate with spaced stripes is obtained.

[0046] Step 3: The flexible substrate with spaced stripes is ultrasonically cleaned with deionized water, acetone, isopropanol, and deionized water. After cleaning, the substrate is dried.

[0047] In one specific embodiment, the present invention further includes step 4, preparing a water vapor barrier layer using PECVD (Plasma Enhanced Chemical Vapor Deposition) process;

[0048] The preparation pressure was 800 Pa and the background temperature was 100 °C. The specific processing steps were as follows: first, preheating and pre-cleaning were performed, and then PECVD process was used for 2 minutes and 30 seconds in an environment with a flow air ratio of SiH4:N2O of 320:560 and N2 flow rate of 400 sccm to obtain a substrate with the target film layer.

[0049] In one specific embodiment, the spin coating rate is 3000 rpm, the temperature is 100°C, and the spin coating time is 2 minutes.

[0050] In one specific embodiment, the spin coating operation is performed in a high-nitrogen environment within a glove box.

[0051] In one specific embodiment, the substrate is made of glass, silicon wafer, thermally oxidized silicon wafer, or quartz glass.

[0052] In one specific embodiment, the drying process in step one involves placing the substrate inside a drying oven.

[0053] In one specific embodiment, the laser annealing wavelength is 330nm, the scanning speed is greater than 50mm / s and less than 500mm / s, and the power is greater than 7W and less than 9W. Laser high-temperature annealing will cause changes in the structure of the PI molecular chain. Under high temperature conditions, a carbonization reaction will occur on the PI surface, which will lead to a significant change in hardness and elastic modulus. The principle is that the polyimide after irradiation annealing has a small amount of carbon powder dispersed. This small-sized powder particles will interact with the PI substrate, resulting in enhanced adhesion, which in turn affects the mechanical properties. By adjusting the power and wavelength of laser annealing, the carbonization doping ratio and the dopant particle size can be controlled.

[0054] PI films exhibit a high absorption coefficient for near-ultraviolet lasers, and using a 330nm laser can effectively improve processing efficiency. Appropriate doping ratios and smaller dopant particles can increase the elastic modulus of the composite material to some extent. The scanning rate of laser annealing affects the carbonization reaction depth; a slower scanning speed increases the annealing reaction time per unit area, thus affecting the reaction temperature and consequently the carbon powder particle size, ultimately impacting mechanical properties.

[0055] In one specific embodiment, the stripe width of the laser processing is 5 μm.

[0056] In one specific embodiment, the ultrasonic cleaning frequency is between 40 kHz and 200 kHz.

[0057] In one specific embodiment, the water vapor barrier layer is composed of SiO2 and NO2 and has a thickness of 300 nm.

[0058] In one specific embodiment, the present invention further includes step 5, such as... Figure 3 As shown, specifically: using magnetron sputtering technology to prepare an active layer, namely IGZO (indium gallium zinc oxide), on a substrate with a target film layer, to obtain a substrate with an IGZO layer. The IGZO layer contains metal atoms indium, gallium, and zinc. In order to maintain good on / off ratio and mobility performance, the composition ratio of indium, gallium, and zinc is 1:1:1, and the bonding ratio of metal atoms to oxygen atoms is greater than 53%.

[0059] After the above operations, source and drain electrodes and interconnects are fabricated on the substrate with the IGZO layer using mask evaporation to obtain a substrate with interconnects. A gate insulating layer is fabricated on the substrate with interconnects using PECVD technology. The process used is the same as that used in step 4 to prepare the moisture barrier layer, but the thickness of the gate insulating layer is different, being 150 nm, to obtain a substrate with a gate insulating layer. Finally, a gate electrode and a wire interconnect layer are deposited above the active layer using thermal evaporation deposition technology. The metal used for evaporation is usually aluminum or silver, to obtain a thin-film transistor (TFT).

[0060] The purpose of step 5 is to determine the tensile strength of the substrate itself by testing the electrical properties of the TFTs fabricated on the tensile display substrate. Specifically, it involves measuring the shift in threshold voltage and the on / off ratio electrical performance before and after a 0.5-fold stretch displacement to quantitatively compare the tensile strength. Devices with smaller threshold voltage shifts and smaller changes in the on / off ratio exhibit higher tensile strength.

[0061] The specific principle of this invention is as follows: Polyimide (PI) is an aromatic heterocyclic polymer compound containing imide chain segments. Under laser irradiation, a carbonization reaction occurs, leading to changes in the PI molecular chain. As the laser energy density increases, C=C double bonds gradually form. These structural changes can lead to enhanced adhesion, resulting in a significant increase in the hardness and elastic modulus of polyimide. For laser-guided polyimide films in the ultraviolet region (330 nm), the absorption coefficient is high. Under photon irradiation, the chemical bonds on the PI surface break, generating a local temperature that can reach 2500 degrees Celsius, reaching the temperature required for the carbonization of organic polymer materials. By processing with appropriate laser scanning speed and laser power, a striped region substrate with the desired mechanical properties is obtained.

[0062] After irradiation, the elastic modulus of PI increased from 5.61 GPa to 9.39 GPa, nearly doubling, with a tensile effect as follows: Figure 4 As shown, using this principle to prepare striped structures can effectively distribute deformation displacement and protect key components such as TFTs in display circuits.

[0063] The foregoing has provided a detailed description of an alternating striped flexible substrate and its fabrication method according to embodiments of this application. The descriptions of the embodiments above are merely illustrative of the methods and core concepts of this application; furthermore, those skilled in the art will recognize that variations in specific implementation methods and application scope may occur based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

[0064] Certain terms are used in the specification and claims to refer to specific components. Those skilled in the art will understand that hardware manufacturers may use different names to refer to the same component. This specification and claims do not distinguish components based on differences in name, but rather on differences in function. The terms "comprising" and "including" used throughout the specification and claims are open-ended and should be interpreted as "comprising / including but not limited to". "Approximately" means that within an acceptable margin of error, those skilled in the art can solve the technical problem and substantially achieve the technical effect within a certain margin of error. The following descriptions in the specification are preferred embodiments for carrying out this application; however, these descriptions are for the purpose of illustrating the general principles of this application and are not intended to limit the scope of this application. The scope of protection of this application shall be determined by the appended claims.

[0065] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a product or system comprising a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a product or system. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the product or system that includes said element.

[0066] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0067] The foregoing description illustrates and describes several preferred embodiments of this application. However, as previously stated, it should be understood that this application is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the application concept described herein through the foregoing teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of this application should be within the protection scope of the appended claims.

Claims

1. A method for preparing a flexible substrate with spaced stripes, characterized in that, include: Step 1: Dissolve YS-20 molding powder completely in N-methylpyrrolidone, and heat and stir to obtain a mixture; spin-coat the mixture onto the surface of the substrate, and dry the substrate after coating. Step 2: After the mixture on the substrate is completely cured, it is annealed by laser irradiation. The laser beam path is adjusted to form equally spaced stripes on the substrate, and the substrate is cooled to obtain a flexible substrate with spaced stripes.

2. The method for preparing a flexible substrate with spaced stripes as described in claim 1, characterized in that, The annealing wavelength of the laser mentioned in step 2 is 330nm, the scanning speed is greater than 50mm / s and less than 500mm / s, and the power is greater than 7W and less than 9W.

3. The method for preparing a flexible substrate with spaced stripes as described in claim 1, characterized in that, It also includes step 3, which is as follows: The flexible substrate with alternating stripes was ultrasonically cleaned in deionized water, acetone, isopropanol, and deionized water. After cleaning, the substrate was dried.

4. The method for preparing a flexible substrate with spaced stripes as described in claim 3, characterized in that, It also includes step 4, which is as follows: A water vapor barrier layer is prepared on the substrate, specifically as follows: A moisture barrier layer was prepared on a substrate using PECVD under an environment with an air pressure of 800 Pa, a background temperature of 100 °C, a SiH4 to N2O flow ratio of 320:560, and an N2 flow rate of 400 sccm.

5. The method for preparing a flexible substrate with spaced stripes as described in claim 4, characterized in that, The thickness of the water vapor barrier layer is 300 nm.

6. The method for preparing a flexible substrate with spaced stripes as described in claim 4, characterized in that, It also includes step 5, which involves preparing an IGZO layer on the substrate to obtain a substrate with an IGZO layer; Source and drain electrodes and interconnecting lines are fabricated on a substrate with an IGZO layer to obtain a substrate with interconnecting lines. A gate insulating layer is prepared on a substrate with connection lines to obtain a substrate with a gate insulating layer. A thin-film transistor (TFT) is obtained by depositing a gate electrode and a wire connection layer on a substrate with a gate insulating layer.

7. The method for preparing a flexible substrate with spaced stripes as described in claim 6, characterized in that, The preparation of the gate insulating layer is specifically as follows: The gate insulating layer was prepared using PECVD process under the following conditions: pressure of 800 Pa, background temperature of 100 °C, flow ratio of SiH4 to N2O of 320:560, and flow rate of N2 of 400 sccm. The thickness of the gate insulating layer is 150 nm.

8. A flexible substrate with spaced stripes, characterized in that, The spaced stripe-shaped flexible substrate is prepared by the preparation method according to any one of claims 1 to 7, comprising: Substrate, cured PI; The substrate, cured PI, SiO2 filling layer, moisture barrier layer, IGZO layer, connection line layer, gate insulation layer and wire connection layer are fixedly connected in sequence. The cured PI includes a high Young's modulus region and a low Young's modulus region, which are equally spaced on the substrate.

9. A flexible substrate with spaced stripes as described in claim 8, characterized in that, It also includes a SiO2 filling layer, a moisture barrier layer, an IGZO layer, a connection layer, a gate insulation layer, and a conductor connection layer; The SiO2 filling layer, water vapor barrier layer, IGZO layer, connection line layer, gate insulation layer and conductor connection layer are fixedly connected in sequence, and the SiO2 filling layer is connected to the cured PI.

10. A flexible substrate with spaced stripes as described in claim 8, characterized in that, The cured PI elastic modulus in the low Young's modulus region is 5.61 GPa; the cured PI elastic modulus in the high Young's modulus region is 9.39 GPa.

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