Pixel structure and preparation method thereof
By using a hot reflow process to form a microlens structure on the RGB color film layer, the problem of complex traditional RGB color film layer processes is solved, resulting in improved product brightness and reduced costs.
Patent Information
- Application Number
- CN202510973047.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-15
- Publication Date
- 2025-10-31
AI Technical Summary
The traditional RGB color film layer lens etching microlens process requires multiple steps, resulting in extended production cycle and high cost, and low product brightness.
A microlens structure is formed on the substrate using a hot reflow process, and then bonded to the color pixel layer with hot reflow adhesive. Hot reflow etching is used to form the structure, simplifying the process steps and increasing the product brightness.
While maintaining the color gamut, the product brightness was increased and the cost was reduced by simplifying the process steps and improving optical performance.
Smart Images
Figure CN120882259A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of Micro OLED module device technology, and particularly relates to a pixel structure and its fabrication method. Background Technology
[0002] In the process of realizing this invention, the inventors discovered that the prior art has at least the following problems:
[0003] Traditional RGB color film layer lens etching microlens process requires multiple steps (usually 8-10 steps) such as photoresist coating, mask exposure, development, and dry etching, and requires a high-precision alignment system, which leads to extended production cycle and problems such as high cost and low product brightness.
[0004] CN117479588A-OLED display panel and OLED display device disclose an OLED display panel and an OLED display device. The OLED display panel sets a light control structure between the light-emitting layer and the planarization layer, so that the light control structure includes a reflective structure and a microlens structure. The projection of the reflective structure on the substrate coincides with the projection of the pixel definition layer on the substrate, and the projection of the microlens structure on the substrate coincides with the projection of the light-emitting material layer on the substrate. This allows the light control structure to reflect large-angle light emitted by the sub-pixels through the reflective structure, but it still cannot solve the above-mentioned technical problems. Summary of the Invention
[0005] The technical problem to be solved by the present invention is to provide a pixel structure and its preparation method, which increases product brightness while ensuring color gamut; it has a good light-gathering effect, thereby further increasing product brightness.
[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a pixel structure having a wafer, an anode film layer, a vapor-deposited film layer and a transparent photoresist arranged sequentially, wherein an RGB color pixel layer is provided on the transparent photoresist, and the RGB color pixel layer has a microlens and an R film layer enclosing it, a microlens and a G film layer enclosing it, and a microlens and a G film layer enclosing it.
[0007] The RGB pixels are fabricated based on the completed microlens process: the hot reflow process is used for etching.
[0008] The preparation method includes the following steps:
[0009] 1) Fabrication of substrate microlenses; 2) Fabrication of RGB color pixel layer; 3) Microlens morphology transfer; 4) Formation of colored adhesive microlens morphology.
[0010] In step 1) above, a first microlens structure is formed on the substrate by a hot reflow etching process; the hot reflow film thickness is 1.5-4 μm, and the first microlens structure film thickness is 1.5-4 μm.
[0011] In step 2) above, the R / G / B pixel layer preparation method is the same. The R pixel layer preparation method includes the following steps: 2-1) coating R adhesive, 2-2) R adhesive exposure and curing.
[0012] In step 2-1) above, a layer of R-resin is spin-coated onto the film layer of the microlens structure. The thickness of the R-resin is 2.5-5 μm. The thickness of the R-resin = the thickness of the microlens structure + the final required thickness of the R layer of the product + the amount of etching loss.
[0013] In step 2-2) above, after spin coating, the R-adhesive is pre-baked and cured at a temperature of 80-90℃ for 60 seconds. Then, the entire surface is exposed to light to cure the color adhesive and the R-adhesive.
[0014] Step 3) above includes the following steps:
[0015] 3-1) Spin-coat the second layer of hot reflow photoresist with a film thickness of 2.5-5 μm. Exposure is performed with a Dose of 80-160 mJ / m^2. Development is performed with 2.38% TMAH developer for 80-100 s. After exposure, the microlens structure corresponding to the bottom layer is formed. The microlens structure is then cured in an oven at 80-90°C for 1 hour to completely evaporate the solvent in the photoresist and form a microlens morphology.
[0016] 3-2) After completing the microlens process, the R pixel is formed by coating Red adhesive + coating Positive adhesive + exposure + development + etching. Dry etching is simultaneously transferred to the R adhesive layer. The etching ratio of hot reflow adhesive to color adhesive is 1:1 to ensure that the hot reflow adhesive is completely removed and the R adhesive retains a thickness of 0.5~1um.
[0017] 3-3) Similarly, by forming G and B films and the hot reflow adhesive on them, R, G, and B adhesives can also be made into microlens morphologies at the same time.
[0018] In step 4) above, the product with the microlens morphology fabricated by the hot reflow adhesive is subjected to full-surface etching on a dry etching machine to transfer the microlens morphology of the hot reflow adhesive onto the RGB adhesive. The etching process transfers the microlens morphology of the hot reflow adhesive onto the RGB adhesive; the full-surface etching completely removes the hot reflow adhesive.
[0019] One of the above technical solutions has the following advantages or beneficial effects: it increases product brightness while ensuring color gamut; it has a good light-gathering effect, thereby further increasing product brightness. Attached Figure Description
[0020] Figure 1 This is a schematic diagram of the pixel structure fabrication method provided in the embodiments of the present invention;
[0021] Figure 2 for Figure 1 A schematic diagram of the pixel structure fabrication method;
[0022] Figure 3 for Figure 1 A schematic diagram of the pixel structure fabrication method;
[0023] Figure 4 for Figure 1 A schematic diagram of the pixel structure fabrication method;
[0024] Figure 5 for Figure 1 A schematic diagram of the pixel structure fabrication method;
[0025] Figure 6 for Figure 1 A schematic diagram of the pixel structure fabrication method;
[0026] The markings in the above figures are: 1. Wafer, 2. Anode film, 3. Evaporated film, 4. Transparent photoresist, 5. Microlens, 6. Color filter. Detailed Implementation
[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0028] Example 1
[0029] See Figures 1-6 A pixel structure comprises a wafer 1, an anode film layer 2, a vapor-deposited film layer 3, and a transparent photoresist 4 arranged sequentially. An RGB color pixel layer is disposed on the transparent photoresist 4. The RGB color pixel layer has microlenses 5 and an R film layer enclosing them, microlenses 5 and a G film layer enclosing them, and microlenses 5 and a G film layer enclosing them. This structure increases product brightness while maintaining the color gamut and has a good light-focusing effect, further increasing product brightness. By molding the RGB (color film photoresist) film layer on a Lens Layer (high refractive index film layer), and the morphology of the RGB layer also being the morphology of the microlens 5, this patent increases product brightness while maintaining the color gamut; moreover, the high refractive index of the RGB material provides a good light-focusing effect, further increasing product brightness.
[0030] Based on the completed microlens 5 process, RGB pixels are fabricated: shaped by hot reflow etching.
[0031] The preparation method includes the following steps:
[0032] 1) Fabrication of substrate microlenses; 2) Fabrication of RGB color pixel layer; 3) Microlens morphology transfer; 4) Formation of colored adhesive microlens morphology.
[0033] In step 1) above, a first-layer microlens structure is formed on the substrate using a thermal reflow etching process. The substrate microlens, as the core component of the optical structure, is used to converge or modulate incident light, improving the light absorption efficiency or light field control capability of the subsequent RGB color pixel layer. This provides a precise initial structure for subsequent steps (such as the microlens morphology transfer in step 3), ensuring the morphological consistency of the final color adhesive microlens. The thermal reflow film thickness is 1.5-4 μm. This thickness range balances material flowability (the surface tension of the molten polymer during thermal reflow) and structural stability, avoiding breakage due to excessive thinness or uncontrolled deformation due to excessive thickness. The first-layer microlens structure film thickness is 1.5-4 μm; this thickness matches the target microlens aperture (e.g., diameter 5-20 μm), ensuring the formation of a high-curvature, low-aberration hemispherical or parabolic structure after thermal reflow.
[0034] In step 2) above, the R / G / B pixel layer preparation method is the same. The R pixel layer preparation method includes the following steps: 2-1) coating R adhesive, 2-2) R adhesive exposure and curing.
[0035] In step 2-1) above, a layer of R-resin is spin-coated onto the film layer of the microlens structure. The thickness of the R-resin is 2.5-5 μm. This thickness range provides sufficient filter layer depth to ensure high transmittance of red light (>90%) and high cutoff of adjacent wavelengths (such as green / blue light) (<5%), reducing color crosstalk. Coating the R-resin onto the substrate microlens ensures that the R-pixel layer formed after subsequent exposure and curing works synergistically with the optical properties of the microlens (such as focusing effect), improving color purity and light utilization. The curvature of the substrate microlens (1.5-4 μm thick) affects the uniformity of R-resin coverage. A total thickness of 2.5-5 μm avoids film breakage or incomplete coverage due to microlens undulations. The thickness of the R-resin = the thickness of the microlens structure + the final required R-layer thickness + etching loss. Etching and development may result in a loss of 0.5-1 μm of film layer. A total thickness of 2.5-5 μm ensures a sufficient effective filter layer at the end.
[0036] In step 2-2) above, pre-baking the R-resist after spin coating evaporates residual solvents, preventing deformation or bubble formation during subsequent exposure or development. Pre-baking also allows for initial cross-linking of the R-resist molecules, optimizing the photoresist's photosensitivity, ensuring uniform reaction during exposure, and improving pattern accuracy. The temperature is 80–90°C, which prevents microlens deformation due to thermal reflow and protects the integrity of the underlying structure. The time is 60 seconds, sufficient for complete solvent evaporation (such as PGMEA or butyl acetate) and suitable for mass production. Excessive time may cause premature cross-linking of the R-resist, reducing exposure sensitivity. Then, full-area exposure is performed to photopolymerize the color photoresist and cure the R-resist. Full-area exposure allows for complete photopolymerization of the R-resist, forming a stable filter layer structure and ensuring the optical performance of the red pixel (such as transmittance and heat resistance).
[0037] Step 3) above includes the following steps:
[0038] 3-1) Spin-coating a second layer of hot reflow photoresist precisely transfers the morphology of the underlying microlens onto the second layer, forming a microlens array structure consistent with the underlying layer. This ensures consistent optical performance. Through exposure, development, and baking curing, a microlens structure with high mechanical strength and stable morphology is formed, providing a foundation for the formation of subsequent colored photoresist microlens morphologies. The film thickness is 2.5-5µm. This thickness matches the underlying microlens structure, ensuring complete coverage of the underlying structure during morphology transfer, avoiding insufficient filling or excessive accumulation. This thickness range also balances flowability (during hot reflow) and structural stability (after development), resulting in a high-precision microlens morphology. Exposure uses a dose of 80-160 mJ / m². This exposure dose ensures sufficient cross-linking of the photoresist, forming a clear microlens pattern and avoiding underexposure (incomplete pattern) or overexposure. Development uses 2.38% TMAH developer for 80-100 s. This development time completely removes the uncross-linked layer while avoiding microlens morphology collapse or dimensional deviations caused by overdevelopment. After exposure, development forms a microlens structure corresponding to the underlying layer. The substrate is then baked in an oven at 80-90°C for 1 hour to completely evaporate the solvent in the photoresist, preventing microlens deformation or degradation of the underlying R-resist due to high temperature. Long baking time ensures complete curing of the adhesive layer, forming a stable microlens structure and improving mechanical strength and chemical resistance.
[0039] 3-2) After completing the microlens process, the R pixel is formed by coating red resist + coating positive resist + exposure + development + etching. Dry etching is simultaneously transferred to the R resist layer. Through photolithography and etching processes, a precise R pixel pattern is formed on the microlens structure to ensure optical alignment with the underlying microlens. The etching ratio of hot reflow resist to color resist is 1:1 to ensure complete removal of hot reflow resist and avoid residue affecting the subsequent fabrication and optical performance of G / B pixel layers. The R resist is retained at a thickness of 0.5~1um to ensure that the transmittance and cutoff of the red filter layer meet the optical requirements.
[0040] 3-3) Similarly, by forming G and B films and the hot reflow adhesive on them, R, G, and B adhesives can also be made into microlens morphologies at the same time.
[0041] In step 4) above, the product with the microlens morphology fabricated by the hot reflow adhesive is subjected to full-surface etching on a dry etching machine to transfer the microlens morphology of the hot reflow adhesive onto the RGB adhesive. The etching process transfers the microlens morphology of the hot reflow adhesive onto the RGB adhesive, achieving optical synergy between color pixels and microlenses, maintaining the high curvature and low aberration characteristics of the microlenses, and ensuring light convergence efficiency. Full-surface etching completely removes the hot reflow adhesive, completing the morphology transfer in one go, which can avoid alignment errors caused by multiple patterning processes.
[0042] It increases product brightness while maintaining the color gamut; it has a good light-focusing effect, thereby further increasing product brightness.
[0043] Example 2
[0044] A method for fabricating a pixel structure includes the following steps:
[0045] 1. Substrate layer microlens fabrication: The first microlens structure (Lens Layer) is formed on the substrate using a thermal reflow etching process. The Lens film thickness is 1.5-4 μm, and the Reflow film thickness is 1.5-4 μm. Based on the completed Lens (microlens) fabrication, RGB pixels are then fabricated. After the Lens (microlens) etching is complete, as shown... Figure 1 .
[0046] 2. RGB (Red, Green, Blue) Color Pixel Layer Fabrication (Taking R-resin pixels as an example, the G / B pixel process is similar): First, R-resin is coated. On the Layer (film layer) after completing the Lens (microlens) process, a layer of R-resin is spin-coated. The thickness of the R-resin is 2.5-5um. The thickness of the Red-resin = the thickness of the Lens + the Red thickness required by the final product + the etching loss, ensuring that the film thickness after etching is 0.5~1um.
[0047] 3. RGB (Red, Green, Blue) Color Pixel Layer Preparation: The R (red) adhesive is exposed and cured. After spin coating, the R adhesive is pre-baked and cured (80-90℃, 60 seconds). Then, the entire surface is exposed (Dose 50-100 mJ / cm^2) for photocuring of the color adhesive. This full-surface exposure curing of the R adhesive prevents it from being developed away during the reflow process. After curing, as shown... Figure 2 .
[0048] 4. Microlens Morphology Transfer: A second layer of Reflow PR (photoresist) is spin-coated with a thickness of 2.5-5 μm. Exposure is performed with a Dose of 80-160 mJ / m², and development is done with 2.38% TMAH developer for 80-100 seconds. After exposure, the microlens structure corresponding to the underlying layer is formed. The layer is then cured in an oven (80-90°C) for 1 hour to completely evaporate the solvent in the PR (photoresist). The cured layer forms the lens morphology, resulting in a smoother surface. Figure 3 .
[0049] 5. Microlens Morphology Transfer: After completing the lens (microlens) process, an R (red) pixel is formed through a process of applying red resist + positive resist + exposure + development + etching. Dry etching is simultaneously transferred to the R resist layer. The etching ratio of Reflow PR (hot reflow resist) to color resist is 1:1, ensuring complete removal of Reflow PR and leaving a 0.5–1µm thickness of R resist. The Reflow PR Lens (R pixel) etching is complete. Figure 4 .
[0050] 6. Similarly, a GB layer (green-blue film) and its corresponding Reflow PR (thermal reflow adhesive) are formed. The RGB adhesive is simultaneously shaped into a microlens, facilitating simultaneous etching, reducing process steps, and lowering costs. Figure 5 .
[0051] 7. Formation of Colored Lens (Microlens): After the Reflow PR (thermal reflow adhesive) lens morphology is fabricated, the product undergoes full-surface etching on a dry etching machine to transfer the Reflow PR lens morphology onto the RGB (red, green, blue) adhesive. The etching process can uniformly transfer the Reflow PR lens morphology onto the RGB adhesive. Full-surface etching must completely remove the Reflow PR (thermal reflow adhesive) (incomplete etching and residue will affect the lens's performance). The etching is completed as follows... Figure 6 .
[0052] Using this process, RGB materials with microlens morphology can be etched into shape in one step, reducing process steps and lowering costs. At the same time, by stacking RGB materials and Lens materials to form microlens morphology, the brightness of the product is increased while ensuring the color gamut of the product.
[0053] In the description of this invention, it should be understood that the terms "coaxial," "bottom," "one end," "top," "middle," "other end," "upper," "side," "top," "inner," "front," "center," "both ends," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.
[0054] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "setting," "connection," "fixing," "screw connection," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components or the interaction between two components. Unless otherwise explicitly limited, those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.
[0055] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A pixel structure, characterized in that, The device comprises a wafer, an anode film layer, a vapor-deposited film layer, and a transparent photoresist layer arranged sequentially. An RGB color pixel layer is provided on the transparent photoresist layer. The RGB color pixel layer has a microlens and an R film layer enclosing it, a microlens and a G film layer enclosing it, and a microlens and a G film layer enclosing it.
2. The method for preparing the pixel structure as described in claim 1, characterized in that, The RGB pixels are fabricated based on the completed microlens process: the hot reflow process is used for etching.
3. The pixel structure and its fabrication method as described in claim 2, characterized in that, Includes the following steps: 1) Fabrication of substrate microlenses; 2) Fabrication of RGB color pixel layer; 3) Microlens morphology transfer; 4) Formation of colored adhesive microlens morphology.
4. The method for fabricating a pixel structure as described in claim 3, characterized in that, In step 1) above, a first microlens structure is formed on the substrate by a hot reflow etching process; the hot reflow film thickness is 1.5-4 μm, and the first microlens structure film thickness is 1.5-4 μm.
5. The method for preparing the pixel structure as described in claim 4, characterized in that, In step 2) above, the R / G / B pixel layer preparation method is the same. The R pixel layer preparation method includes the following steps: 2-1) coating R adhesive, 2-2) R adhesive exposure and curing.
6. The method for fabricating a pixel structure as described in claim 5, characterized in that, In step 2-1) above, a layer of R-resin is spin-coated onto the film layer of the microlens structure. The thickness of the R-resin is 2.5-5 μm. The thickness of the R-resin = the thickness of the microlens structure + the final required thickness of the R layer of the product + the amount of etching loss.
7. The method for fabricating a pixel structure as described in claim 6, characterized in that, In step 2-2) above, after spin coating, the R-adhesive is pre-baked and cured at a temperature of 80-90℃ for 60 seconds. Then, the entire surface is exposed to light to cure the color adhesive and the R-adhesive.
8. The method for fabricating a pixel structure as described in claim 7, characterized in that, Step 3) above includes the following steps: 3-1) Spin-coat the second layer of hot reflow photoresist with a film thickness of 2.5-5 μm. Exposure is performed with a Dose of 80-160 mJ / m^2. Development is performed with 2.38% TMAH developer for 80-100 s. After exposure, the microlens structure corresponding to the bottom layer is formed. The microlens structure is then cured in an oven at 80-90°C for 1 hour to completely evaporate the solvent in the photoresist and form a microlens morphology. 3-2) After completing the microlens process, the R pixel is formed by coating Red adhesive + coating Positive adhesive + exposure + development + etching. Dry etching is simultaneously transferred to the R adhesive layer. The etching ratio of hot reflow adhesive to color adhesive is 1:1 to ensure that the hot reflow adhesive is completely removed and the R adhesive retains a thickness of 0.5~1um. 3-3) Similarly, by forming G and B films and the hot reflow adhesive on them, R, G, and B adhesives can also be made into microlens morphologies at the same time.
9. The method for preparing a pixel structure as described in claim 8, characterized in that, In step 4) above, the product with the microlens morphology fabricated by the hot reflow adhesive is subjected to full-surface etching on a dry etching machine to transfer the microlens morphology of the hot reflow adhesive onto the RGB adhesive. The etching process transfers the microlens morphology of the hot reflow adhesive onto the RGB adhesive. The entire surface is etched to completely remove the hot reflow adhesive.