Preparation method of BIM mask for replacing HTM in field of FPD

Abstract

The invention provides a BIM (Building Information Modeling) mask plate preparation method for replacing HTM (Hypertext Markup) in the field of FPD (Fabry-Perot Display), which is applied to a one-time graphical forming process of a PDL (Pixel Definition Layer) and a PS (Poly Styrene) in OLED (Organic Light Emitting Diode) manufacturing, and comprises the following steps: taking a binary mask plate BIM as a substrate, and determining a light-proof region and a full-light-transmitting region of the mask plate: setting a region corresponding to a PS structure as the light-proof region with the transmittance of 0%; an area corresponding to the PDL structure is set as a full-light-transmitting area, and the transmittance is 100%; a grating structure is additionally arranged at the transition position between the light-proof area and the all-transparent area; according to the coating thickness of the photoresist, adaptive process parameters are set, and the process parameters comprise exposure dose, development time, hard baking temperature and ultraviolet irradiation dose. According to the preparation method disclosed by the invention, the PDL and PS one-time patterning effect which is completely the same as that of HTM is realized, the mask cost is greatly reduced, and meanwhile, various advantages of an original HTM process are kept.

Description

Technical Field

[0001] This application relates to the technical field of advanced packaging design, and more particularly to a method for checking multilayer layout connectivity across EDA tools. This application also relates to the technical field of flat panel display (FPD) manufacturing, and more particularly to a method for preparing a BIM mask in the FPD field that replaces the halftone mask (HTM), applicable to the one-step patterning process of the pixel defining layer (PDL) and support pillars (PS) in OLED manufacturing. Background Technology

[0002] In OLED manufacturing processes, the patterning of the pixel defining layer (PDL) and support pillars (PS) is one of the core steps. In existing technologies, the halftone mask (HTM) process can achieve patterning of PDL and PS in one step, replacing the cumbersome process of "two coatings and two masks" in the traditional process, and has become the mainstream process solution.

[0003] The core principle of the HTM process is as follows: Both the PDL and PS regions use photosensitive polyimide (PSPI) as the molding material. This material has photosensitive groups, and its solubility differs after exposure. Through a single coating, exposure, and development process using the HTM mask, the patterning of both layers can be completed simultaneously without additional dry or wet etching steps. Specifically, after being exposed to a higher exposure dose, the PDL region develops into an inverted conical opening that is narrower at the top and wider at the bottom. This ensures that the bottom is hydrophilic for ink droplet spreading while the top is hydrophobic to prevent overflow, meeting the stringent requirements of inkjet printing for droplet morphology. After being exposed to a lower exposure dose or partially shaded by the mask, the PS region develops into a columnar structure with a height of 1.5–2.0 µm. This structure supports the metal mask (FMM) in subsequent vapor deposition processes, preventing the mask from sinking and scratching the PDL and organic functional layers.

[0004] Compared to traditional processes, the HTM process offers significant simplification: the traditional route requires sequential steps of organic resin coating → first mask exposure and development → dry etching → cleaning → inorganic layer coating → second mask exposure and development, totaling two masks, two coatings, and two dry etchings. The HTM process compresses this process to "one coating + one mask + one development," reducing equipment footprint by over 30% and cycle time by approximately 25%, while effectively reducing alignment errors and particle contamination risks. Furthermore, the HTM process produces PDL / PS structures with strong compatibility. In the inkjet route, the inverted conical opening of the PDL guides precise RGB ink filling, while in the evaporation route, the PS pillars support the FMM, ensuring mask sag is <5µm during evaporation of 8-Gen and larger substrates, thus avoiding color mixing issues.

[0005] However, the existing HTM process has a core flaw: the production cost of HTM masks is extremely high, with each HTM mask costing approximately 1 million yuan, while the cost of a regular binary mask (BIM) is only 300,000 yuan. The high cost of HTM masks significantly increases the total manufacturing cost of OLED products, becoming a cost bottleneck for the large-scale production of FPD products. Therefore, it is urgent to develop a low-cost mask and preparation method to replace HTM and achieve the same process effect. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this application aims to provide a BIM mask preparation method that replaces HTM in the field of FPD. Based on BIM, through reasonable graphic design and process parameter matching, it achieves the same PDL and PS one-time graphicization effect as HTM, significantly reducing mask costs while maintaining the advantages of the original HTM process.

[0007] To achieve the above objectives, this application provides a BIM mask fabrication method in the field of FPD that replaces HTM, applied to the one-step patterning process of pixel defining layer (PDL) and support pillar (PS) in OLED manufacturing, comprising the following steps: Using a binary photomask BIM as the base, the opaque and fully transparent areas of the photomask were determined: the area corresponding to the PS structure was set as the opaque area with a transmittance of 0%; the area corresponding to the PDL structure was set as the fully transparent area with a transmittance of 100%. A grating structure is added at the transition position between the opaque area and the fully transparent area; Based on the coating thickness of the photoresist, appropriate process parameters are set, including: exposure dose, development time, hard baking temperature, and ultraviolet irradiation dose.

[0008] Furthermore, the grating is a slit structure, and its line width and spacing are designed to be 0.5 to 0.7 times the actual resolution of the lithography machine. The grating width is adapted to the characteristics of the exposure equipment and photoresist material used in FPD manufacturing.

[0009] Furthermore, the grating structure utilizes the light interference effect of the slit to attenuate the incident light energy, achieving a gradient distribution of transmittance between 0% and 100%. The grating structure is provided at all locations on the entire BIM mask except for the opaque area with 0% transmittance and the fully transparent area with 100% transmittance.

[0010] Furthermore, the transmittance of the grating structure is 15%, so that the incident light forms a stepped light energy distribution after passing through the mask, with 0% in the PS region, 15% in the grating transition region, and 100% in the PDL region.

[0011] Furthermore, the step of setting appropriate process parameters based on the photoresist coating thickness also includes: The exposure dose and the development time are adjusted according to the photoresist thickness to achieve the target critical size of the photoresist; The hard baking temperature is the curing temperature of the photoresist; The ultraviolet irradiation dose is selected based on the photoresist thickness and material properties.

[0012] Furthermore, the photoresist is a photosensitive polyimide, which forms a stepped contour after exposure and development through the mask. The PDL region forms an inverted conical opening that is narrow at the top and wide at the bottom, while the PS region retains a columnar structure with a height of 1.5 to 2.0 µm.

[0013] Furthermore, it also includes: installing the prepared BIM film onto the exposure machine, exposing the 8-GenOLED substrate coated with photoresist once, and then performing development, hard baking and UV irradiation treatment after exposure. After development, the photoresist forms a stepped contour morphology: the PS region retains a columnar structure with a height of 1.8µm, and the PDL region forms an inverted conical opening that is narrow at the top and wide at the bottom, with hydrophilic bottom and hydrophobic top, meeting the process requirements of OLED manufacturing.

[0014] To achieve the above objectives, this application also provides a BIM mask that replaces HTM in the field of FPD, which is prepared using the BIM mask preparation method for replacing HTM in the field of FPD as described above.

[0015] To achieve the above objectives, this application also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the BIM mask preparation method for replacing HTM in the FPD field as described above.

[0016] To achieve the above objectives, this application also provides a computer-readable storage medium storing a computer program that is loaded and executed by a processor to implement the BIM mask preparation method in the field of FPD as described above, which replaces HTM.

[0017] Compared with the prior art, the photomask preparation method of this application has the following significant advantages: Replacing HTM with BIM, which costs approximately 300,000 yuan, with HTM, which costs approximately 1 million yuan, can directly save 700,000 yuan in mask costs per product, significantly reducing mask costs. For a large number of product factories in the FPD industry, the cumulative cost savings are extremely considerable, effectively solving the industry pain point of high HTM mask costs. By utilizing the light interference effect of the grating structure, a stepped distribution of incident light energy is achieved. With appropriate process parameters, the PSPI photoresist, after exposure and development, forms PDL and PS structures that are completely consistent with the HTM process. The inverted conical opening of the PDL meets the droplet morphology requirements of inkjet printing, and the columnar structure of the PS (1.5 to 2.0 µm) can effectively support the FMM, ensuring that the mask droop is <5µm when evaporating large-size substrates of 8-Gen and above, avoiding color mixing, and completely replicating the HTM process effect. This application still adopts the process flow of "one coating + one mask + one development", which does not change the simplicity of the original HTM process. The advantages of reducing equipment occupation by 30% and shortening cycle time by about 25% remain unchanged. At the same time, it can still reduce the risk of alignment error and particulate contamination, thus retaining all the advantages of the HTM process. The mask design method of this application is fully compatible with the manufacturing processes of inkjet OLED and vapor-deposited OLED products. It does not require major modifications to existing production lines. Mass production can be achieved simply by replacing the mask and fine-tuning the process parameters. The industrial transformation cost is low and it has strong product compatibility.

[0018] Except for the 0% and 100% transparent areas, grating structures can be set on all other parts of the entire BIM mask. The line width, spacing, and width of the gratings can be flexibly adapted according to the characteristics of the exposure equipment and photoresist materials, making it suitable for the manufacturing of FPD products of different specifications.

[0019] Other features and advantages of this application will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing this application. Attached Figure Description

[0020] The accompanying drawings are provided to further illustrate the present application and form part of the specification. Together with the embodiments of the present application, they serve to explain the present application but do not constitute a limitation thereof. In the drawings: Figure 1 A flowchart illustrating the BIM mask fabrication method for replacing HTM in the field of FPD according to embodiments of this application; Figure 2 This is a schematic diagram of the overall structure of the BIM mask in an embodiment of this application; Figure 3 This is a schematic diagram of the stepped distribution of the photoresist outline on the BIM mask according to an embodiment of this application. Figure 4 This is a schematic diagram of the spatial image simulation result behind the BIM mask in an embodiment of this application; Figure 5 This is a schematic diagram of the contour simulation result after photoresist development according to an embodiment of this application. Figure 6This is a schematic diagram of an electronic device structure according to an embodiment of this application.

[0021] The above figures are only used to illustrate the technical solution of this application and are not intended to limit the scope of protection of this application. Detailed Implementation

[0022] The preferred embodiments of this application are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit this application.

[0023] Embodiments of this application will now be described in more detail with reference to the accompanying drawings. While some embodiments of this application are shown in the drawings, it should be understood that this application can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of this application. It should be understood that the drawings and embodiments of this application are for illustrative purposes only and are not intended to limit the scope of protection of this application.

[0024] The term "comprising" and its variations as used in this application are open-ended, meaning "including but not limited to". The term "based on" means "at least partially based on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments". Definitions of other terms will be given in the description below.

[0025] It should be noted that the terms "first" and "second" may be used in this application only to distinguish different devices, components or parts, and are not used to define the order of functions performed by these devices, components or parts or their interdependence.

[0026] It should be noted that the terms "one" and "more" used in this application are illustrative rather than restrictive, and those skilled in the art should understand that, unless explicitly stated otherwise in the context, they should be understood as "one or more". "More" should be understood as two or more.

[0027] The method approach of the embodiments of this application includes: Photosensitive polyimide (PSPI) is selected as the photoresist. Its exposure dose-dependent solubility characteristics are utilized to transform the gradient distribution of light energy into a physical contour step distribution of the photoresist, eliminating the need for additional dry and wet etching steps and maintaining consistency with the material principles of the HTM process.

[0028] PSPI has the following photosensitive properties: PSPI has its own photosensitive group, and its solubility in the developer is positively correlated with the exposure dose received - the higher the exposure dose, the more fully the photosensitive group reacts, the greater the solubility of the photoresist in the developer, and the more it is etched after development; the lower the exposure dose, the lower the solubility, and the more it is retained after development.

[0029] Gradient energy corresponds to a stepped profile: Combining the three-level stepped distribution of light energy described above, the PSPI photoresist forms a precise structural morphology after development. PS area (0% transmittance, 0 exposure energy): The photoresist has no photosensitive reaction, the lowest solubility, and is completely retained after development, forming a columnar support structure with a height of 1.5 to 2.0 µm, which meets the requirements of supporting the FMM in the subsequent evaporation process; The grating transition area (15% transmittance, low dose exposure): the photoresist undergoes a slight photosensitivity reaction, with moderate solubility. After development, it is partially etched to form a smooth transition structure between PS and PD, avoiding process defects caused by abrupt contour changes. PDL area (100% transmittance, high dose exposure): The photoresist reacts fully and has the highest solubility. After development, it is deeply etched to form an inverted conical opening that is narrow at the top and wide at the bottom, achieving the functional requirements of being hydrophilic at the bottom (facilitating the spread of ink droplets in inkjet printing) and hydrophobic at the top (preventing ink droplet overflow).

[0030] Mask area design principle: functional partitioning and global adaptation of the grating.

[0031] The mask design precisely partitions functions on the BIM substrate and enables flexible adaptation of the grating, ensuring coverage of all PDL / PS graphical requirements in OLED manufacturing. The specific design principles are as follows: Each functional area corresponds to a process requirement: Opaque area: Strictly corresponds to the position of the PS support pillar to ensure that the photoresist is completely preserved and forms a columnar structure; Fully transparent area: Strictly corresponds to the position of the PDL pixel boundary layer to ensure high-dose exposure and form an inverted cone opening; Grating transition region: Set at the junction of PS and PDL to achieve a smooth transition of light energy and photoresist contour, avoiding edge defects.

[0032] Global adaptability of gratings: On the entire BIM mask, except for the 0% opaque area and the 100% fully transparent area, all other positions can be set with grating structures according to process requirements. It can adapt to the PDL / PS graphic design of different specifications of FPD products, and its flexibility is on par with HTM.

[0033] To ensure that the light energy gradient distribution can be accurately converted into the stepped profile of the photoresist, the method in the embodiments of this application needs to be matched with appropriate photolithography process parameters to achieve synergy between light energy, material photosensitivity, and process operation. The parameter settings are all based on the characteristics of PSPI photoresist and the target structural morphology, and the core principle is "matching as needed and avoiding over-matching". Exposure dose (Dose) & development time (Dev): Adjusted according to the actual coating thickness of PSPI photoresist, with the target critical size (CD value) required by the process as the standard, to ensure the dimensional accuracy of the PDL inverted conical opening and the height accuracy of the PS columnar structure; Hard baking temperature (HB): The curing temperature of PSPI photoresist is directly adopted to ensure the structural stability of the photoresist after development and prevent deformation and peeling in subsequent processes; Ultraviolet (UV) irradiation dose: The dose should be selected based on the thickness and material properties of the photoresist. It is not always better to have a higher dose. Excessive UV irradiation can degrade the hydrophilic / hydrophobic properties of PSPI and affect the inkjet printing effect.

[0034] The above process parameters complement the light energy distribution of the grating, ensuring that the final PDL / PS structure is completely consistent with the HTM process in terms of size, morphology, and function.

[0035] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0036] Example 1 The technical solution of this application will be described in detail below with reference to specific embodiments. Figure 1 This is a flowchart of a BIM mask fabrication method for replacing HTM in the field of FPD according to an embodiment of this application. The following will be combined with... Figure 1 The method for preparing a BIM mask that is an alternative to HTM in the field of FPD in this application is described in further detail.

[0037] This embodiment uses the one-step patterning process of PDL and PS on an 8-Gen OLED substrate as an example. The photoresist used is photosensitive polyimide (PSPI), and the lithography machine resolution is 2µm. The specific implementation steps are as follows: First, in step 101, the mask area is divided using a binary photomask (BIM) as the base.

[0038] In this embodiment, a binary photomask (BIM) is used as the base. The area on the BIM photomask corresponding to the PS support column is made into an opaque pattern with a transmittance of 0%; the area corresponding to the PDL pixel boundary layer is made into a fully transparent area with a transmittance of 100%.

[0039] In step 102, a grating structure is added at the transition position between the opaque PS region and the fully transparent PDL region.

[0040] In this embodiment, the line width and spacing of the grating are designed to be between 0.5 and 0.7 times the resolution of the lithography machine (for example, if the resolution of the lithography machine is 1.5 μm, then the line width and spacing of the grating are designed to be between 0.75 and 1.05 μm).

[0041] In this embodiment, a slit grating structure is added at the transition position between the opaque PS region and the fully transparent PDL region. Based on the 2µm resolution of the lithography machine, the line width and spacing of the grating are designed to be 0.6 times the resolution of the lithography machine, that is, the line width and spacing are both 1.2µm. Combining the existing exposure equipment and the characteristics of PSPI photoresist, the grating width is adapted to 50µm.

[0042] Verified using Litho simulation software, the grating structure achieves approximately 15% transmittance due to optical interference, resulting in a stepped light energy distribution after the incident light passes through the mask, with 0% in the PS region, 15% in the grating transition region, and 100% in the PDL region, thus meeting the requirements for forming the stepped contour of the photoresist.

[0043] In step 103, appropriate process parameters are set according to the coating thickness of the photoresist.

[0044] The exposure dose and development time settings depend on the specific thickness of the photoresist. For photoresist of normal thickness, the dose and development time should be sufficient to achieve the target critical size (CD value). The hard bake (HB) temperature is the curing temperature of the photoresist. The ultraviolet (UV) irradiation dose needs to be selected considering the photoresist thickness and material properties.

[0045] In this embodiment, the coating thickness of the PSPI photoresist is 2.0µm, and the appropriate process parameters are set according to this thickness: Exposure dose: set to 1200 mJ / cm 2 This ensures that the PDL area receives sufficient exposure dose, forming an inverted conical opening after development; Developing time: set to 60s to achieve a target critical size (CD value) of 10µm for the photoresist; Hard baking (HB) temperature: The curing temperature of this PSPI photoresist is 230℃, and the baking time is 30 min to ensure the structural stability of the photoresist after molding; Ultraviolet (UV) radiation dose: set to 800 mJ / cm 2 The selection should be based on the characteristics of PSPI material to avoid excessive irradiation that could degrade the hydrophobic / hydrophilic properties of the photoresist.

[0046] In step 104, the prepared BIM mask is installed on the exposure machine for exposure and development.

[0047] In this embodiment, the fabricated BIM mask is mounted on an exposure machine to expose the 8-Gen OLED substrate coated with PSPI photoresist once. After exposure, it undergoes development, hard baking, and UV irradiation. After development (Dev), the photoresist forms a stepped contour morphology: the PS region retains a columnar structure with a height of 1.8µm, and the PDL region forms an inverted conical opening that is narrow at the top and wide at the bottom. The bottom is hydrophilic and the top is hydrophobic, which fully meets the process requirements for OLED manufacturing.

[0048] In step 105, the formed PDL / PS structure is applied to inkjet OLED and vapor deposition OLED processes respectively to verify compatibility with subsequent processes.

[0049] In this embodiment of the application, the formed PDL / PS structure is applied to inkjet OLED and vapor deposition OLED processes, respectively, specifically including: Inkjet path: The PDL inverted conical opening can accurately guide the RGB ink filling, eliminating ink droplet overflow and uneven spreading issues; Evaporation route: The PS columnar structure effectively supports the metal mask (FMM). During evaporation of the 8-Gen substrate, the FMM sag is 3.5µm < 5µm, and there is no color mixing problem.

[0050] Example 2 This application provides a BIM mask that replaces HTM with FPD field, which is prepared using the BIM mask preparation method for replacing HTM with FPD field in Example 1.

[0051] Figure 2 This is a schematic diagram of the overall structure of the BIM mask in an embodiment of this application. Figure 3 This is a schematic diagram of the stepped distribution of the photoresist outline on the BIM mask according to an embodiment of this application, as shown below. Figure 2 and 3As shown, by adding a suitable grating design in the middle of the pattern, a gradient distribution of the plaza distribution is achieved, ultimately realizing a stepped distribution of the PR (photoresist) profile. The black area in the image represents an opaque pattern, which can be understood as 0% transmittance. The blank area on the right is the fully transparent area corresponding to the PDL (photoresist layer), with 100% transmittance. Although the area with the slit on the left has 100% transmittance, the area with the diagonal line in the middle represents the added grating structure area. However, the light passing through this area experiences interference due to the slit, resulting in energy attenuation. This can be understood as a transmittance value between 0% and 100%, the specific value depending on the slit width. Therefore, after exposure to light with different transmittances, the energy reaching the PR will change in a gradient, resulting in different morphologies in the photosensitive PR.

[0052] The slit is the grating. The specific grating width needs to be adapted according to the equipment and PR material. The line width and spacing of the grating are designed to be between 0.5 and 0.7 times the resolution of the lithography machine. Except for the 0% and 100% transparent areas, all other areas on the entire BIM mask (Halftone Mask) can be made into gratings.

[0053] Figure 4 This is a schematic diagram of the spatial image simulation results behind the BIM mask in an embodiment of this application. The vertical axis represents light intensity, and the horizontal axis represents the substrate position. Figure 4 As shown, a stepped distribution can be clearly seen with 0 light intensity in the PS region, approximately 15% light intensity in the grating transition region, and 100% light intensity in the PDL region, achieving the result of replacing HTM.

[0054] Figure 5 This is a schematic diagram of the contour simulation results of the photoresist after development, as shown in the embodiment of this application. The vertical axis represents the height of the photoresist, and the horizontal axis represents the position of the substrate. Figure 5 As shown, a columnar structure with a height of 1.5-2.0µm is formed in the PS region, and an inverted conical opening with a narrow top and wide bottom is formed in the PDL region. The grating transition region achieves a smooth stepped transition between the two.

[0055] Verification shows that the BIM mask fabrication method in the field of FPD that replaces HTM fully achieves the process effect of HTM using BIM. It saves 700,000 yuan in mask costs for a single 8-Gen OLED product. Moreover, the process is simplified, the product is highly compatible, and it is fully suitable for mass production.

[0056] Example 3 In embodiments of this application, an electronic device is also provided. Figure 6 This is a schematic diagram of the electronic device structure according to an embodiment of this application, such as... Figure 6 As shown, the electronic device of this application includes a processor 601 and a memory 602, wherein, The memory 602 stores a computer program, which, when read and executed by the processor 601, performs the steps described above in the embodiment of the BIM mask preparation method for replacing HTM in the FPD field.

[0057] Example 4 In the embodiments of this application, a computer-readable storage medium is also provided, which stores a computer program, wherein the computer program is configured to execute the steps in the embodiments of the BIM mask preparation method for replacing HTM with FPD field as described above when running.

[0058] In this embodiment, the aforementioned computer-readable storage medium may include, but is not limited to, various media capable of storing computer programs, such as USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, or optical disks.

[0059] It will be understood by those skilled in the art that the above descriptions are merely preferred embodiments of this application and are not intended to limit this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for fabricating a BIM mask to replace HTM in the field of FPD, applied to the one-step patterning process of pixel defining layer (PDL) and support pillar (PS) in OLED manufacturing, comprising the following steps: Using a binary photomask BIM as the base, the opaque and fully transparent areas of the photomask were determined: the area corresponding to the PS structure was set as the opaque area with a transmittance of 0%; the area corresponding to the PDL structure was set as the fully transparent area with a transmittance of 100%. A grating structure is added at the transition position between the opaque area and the fully transparent area; Based on the coating thickness of the photoresist, appropriate process parameters are set, including: exposure dose, development time, hard baking temperature, and ultraviolet irradiation dose.

2. The method for preparing a BIM mask to replace HTM in the field of FPD according to claim 1, characterized in that, The grating has a slit structure, and its line width and spacing are designed to be 0.5 to 0.7 times the actual resolution of the lithography machine. The grating width is adapted to the characteristics of the exposure equipment and photoresist material used in FPD manufacturing.

3. The method for preparing a BIM mask to replace HTM in the field of FPD according to claim 2, characterized in that, The grating structure utilizes the light interference effect of the slit to attenuate the incident light energy, achieving a gradient distribution of transmittance between 0% and 100%. The grating structure is installed on all positions on the entire BIM mask except for the opaque area with 0% transmittance and the fully transparent area with 100% transmittance.

4. The method for preparing a BIM mask to replace HTM in the field of FPD according to claim 1, characterized in that, The transmittance of the grating structure is 15%, so that the incident light forms a stepped light energy distribution after passing through the mask, with 0% in the PS region, 15% in the grating transition region, and 100% in the PDL region.

5. The method for preparing a BIM mask to replace HTM in the field of FPD according to claim 1, characterized in that, The step of setting appropriate process parameters based on the photoresist coating thickness further includes: The exposure dose and the development time are adjusted according to the photoresist thickness to achieve the target critical size of the photoresist; The hard baking temperature is the curing temperature of the photoresist; The ultraviolet irradiation dose is selected based on the photoresist thickness and material properties.

6. The method for preparing a BIM mask to replace HTM in the field of FPD according to claim 1, characterized in that, The photoresist is a photosensitive polyimide, which forms a stepped contour after exposure and development through the mask. The PDL region forms an inverted conical opening that is narrow at the top and wide at the bottom, while the PS region retains a columnar structure with a height of 1.5 to 2.0 µm.

7. The method for preparing a BIM mask to replace HTM in the field of FPD according to claim 1, characterized in that, Also includes: The prepared BIM stencil is installed into the exposure machine, and the 8-Gen OLED substrate coated with photoresist is exposed once. After exposure, it is developed, hard baked and UV irradiated. After development, the photoresist forms a stepped contour morphology: the PS region retains a columnar structure with a height of 1.8µm, and the PDL region forms an inverted conical opening that is narrow at the top and wide at the bottom. The bottom is hydrophilic and the top is hydrophobic, which meets the process requirements of OLED manufacturing.

8. A BIM mask for use in the field of FPD as an alternative to HTM, characterized in that, It is prepared using the BIM mask preparation method that replaces HTM in the FPD field as described in any one of claims 1-6.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, The processor is configured to execute a computer program stored in the memory to implement the BIM mask preparation method for replacing HTM in the FPD field as described in any one of claims 1-6.

10. A computer-readable storage medium storing a computer program, characterized in that, The computer program is loaded and executed by a processor to implement the BIM mask preparation method for replacing HTM in the FPD field as described in any one of claims 1-6.

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