Photoetching mask plate, metal film layer structure preparation method and metal film layer structure

Abstract

The invention relates to the technical field of coating, in particular to a photoetching mask plate, a preparation method of a metal film layer structure and the metal film layer structure, and the photoetching mask plate is characterized in that a circular through hole is formed in the central position of a first mask plate; the second mask plate and the first mask plate are oppositely arranged; wherein the first mask plate and the second mask plate jointly form an accommodating space which is used for fixing a curved-surface substrate; the first mask plate is provided with a first inner surface, and the curvature radius of the first inner surface is matched with the curvature radius of the first surface of the curved-surface substrate; the second mask plate is provided with a second inner surface, and the curvature radius of the second inner surface is matched with the curvature radius of the second surface of the curved-surface substrate. The method has the advantages that the traditional mechanical etching and mask coating are replaced by the photoetching process, so that the edge halation and mechanical error are fundamentally eliminated, and the pattern size and position precision of the circular hole can be within + / -50 microns. And physical vapor deposition and hardening treatment are combined, so that a uniform and compact metal film layer with high adhesive force is obtained.

Description

Technical Field

[0001] This invention relates to the field of coating technology, and in particular to photolithography masks, methods for preparing metal film structures, and metal film structures. Background Technology

[0002] In the manufacturing of core components such as optical elements, sensors, and electronic devices, it is common to fabricate a specific patterned metal film structure on the substrate surface, where the central area retains a blank substrate layer and the surrounding area is covered with a metal film layer. This structure is a key basic component for realizing functions such as signal transmission, optical filtering, and sensing detection. With the development of technology, the performance requirements of these components in application scenarios are becoming increasingly demanding. In many cases, the fabrication of the above structure needs to be completed on non-planar substrates with curvature, which poses a severe challenge to traditional patterning processes.

[0003] Currently, the existing technologies for fabricating metal film structures with central circular holes on curved substrates mainly include the following two similar implementation schemes: Mechanical etching method: This method employs a process of "first overall coating, then mechanical processing." First, a metal film layer (such as aluminum, gold, silver, copper, etc.) is completely deposited on the surface of the curved substrate. Then, according to the size of the target circular hole, a precise mechanical etching device is used to remove the metal film layer in the central area, exposing the substrate material. Finally, the target structure is obtained by wiping and cleaning. However, this method has significant drawbacks: First, the mechanical positioning accuracy is limited, resulting in poor positional accuracy of the central circular hole; second, over-etching or under-etching occurs during processing, leading to large dimensional errors in the circular hole (typically ±200μm); more importantly, the mechanical force acts directly on the brittle curved substrate, posing a high risk of substrate scratches or microcracks, severely affecting the yield of the finished product.

[0004] Mask coating method: This method employs a "mask coverage first, then coating selection" process. First, a physical mask (usually a thin metal sheet or a high-temperature resistant polymer film) adapted to the curvature of the curved substrate is prepared. Then, the mask is precisely adhered to the curved substrate, completely covering the central area that needs to be left blank. Next, overall metal coating is performed, depositing a metal film layer on the peripheral areas not covered by the mask. Finally, the mask is removed to obtain the desired structure. While this method avoids mechanical damage, its drawbacks are equally significant: due to the inherent curvature of the curved surface, rigid or flexible masks are difficult to achieve a completely seamless and tight fit with the substrate surface. During the coating process, metal particles can deposit through these micron-sized gaps onto the edges of the blank areas that should be protected, forming edge halos approximately 5μm-20μm wide. This results in blurred pattern boundaries and poor clarity, failing to meet the requirements for high-precision components.

[0005] In summary, existing technologies struggle to stably fabricate centrally located circular hole metal film structures with high dimensional accuracy, high positional accuracy, and excellent edge quality on complex curved substrates. Therefore, a new technological solution is urgently needed to overcome the inherent limitations of existing technologies. Summary of the Invention

[0006] Based on this, the present invention proposes a photomask, a method for fabricating a metal film structure, and the metal film structure itself. This is achieved by sequentially performing photoresist coating, pre-baking, exposure, development, hardening, deposition, and resist removal steps on a curved substrate. The photomask is specifically designed for achieving high-precision photolithography on curved surfaces. This method enables the fabrication of metal film structures with high precision in the central circular hole pattern and excellent edge quality.

[0007] To achieve the above objectives, the technical solution created by this invention is as follows: a photolithographic mask for fabricating circular hole patterns on a curved substrate, comprising: A first mask has a circular through-hole at its center; a second mask is disposed opposite to the first mask; the first and second masks together form a receiving space for fixing a curved substrate; the side of the first mask facing the curved substrate has a first inner surface, the radius of curvature of which matches the radius of curvature of the first surface of the curved substrate; the side of the second mask facing the curved substrate has a second inner surface, the radius of curvature of which matches the radius of curvature of the second surface of the curved substrate.

[0008] A method for fabricating a metal film structure with a central circular hole on a curved substrate, using the aforementioned photolithographic mask, is characterized by comprising the following steps: S1: Perform ultrasonic cleaning on the curved substrate.

[0009] S2: Spin-coat photoresist onto the surface of the curved substrate and perform pre-baking treatment.

[0010] S3: Use a photomask to expose and develop the curved substrate coated with photoresist to form a circular hole pattern.

[0011] S4: Perform hardening treatment on the developed curved substrate.

[0012] S5: A metal film is deposited on the surface of a curved substrate using physical vapor deposition.

[0013] S6: Remove residual photoresist to obtain the metal film structure with a central circular hole in the curved substrate.

[0014] Furthermore, in step S2, the photoresist is a negative photoresist, the spin coating speed is 1000 r / min to 2000 r / min, the photoresist layer thickness is 1 μm to 5 μm, the pre-baking temperature is 80℃ to 100℃, and the time is 20 to 40 minutes.

[0015] Furthermore, in step S3, 365nm ultraviolet light is used for exposure, followed by development with an alkaline developer.

[0016] Furthermore, in step S4, the hardening treatment temperature is 100°C to 150°C, and the time is 30 to 40 minutes.

[0017] Furthermore, in step S5, the physical vapor deposition method is vacuum deposition, with a vacuum degree of 1×10⁻⁶. -4 Pa to 5×10 - 4 Pa, with deposition rates ranging from 30 nm / s to 45 nm / s.

[0018] Furthermore, in step S6, the photoresist is removed by immersion in an organic solvent for 50 to 80 minutes.

[0019] A curved substrate central circular hole metal film structure prepared by the above-described preparation method includes: a curved substrate having a predetermined radius of curvature; a metal film covering the surface of the curved substrate; wherein the metal film has a circular hole to expose the surface of the curved substrate.

[0020] Furthermore, the radius of curvature of the upper surface of the curved substrate is not equal to the radius of curvature of the lower surface of the curved substrate.

[0021] Furthermore, the material of the metal film is one of aluminum, gold, silver or copper; the thickness of the metal film is 100nm to 500nm.

[0022] This invention achieves the following beneficial effects: by replacing traditional mechanical etching and mask coating with photolithography, it fundamentally eliminates "edge halos" and mechanical errors, enabling the size and positional accuracy of circular holes to reach within ±50μm. Combined with physical vapor deposition and hardening treatment, it yields a uniform, dense, and strongly adherent metal film.

[0023] The design of the receiving part of the special mask plate is precisely adapted to the curvature of the substrate, solving the problem of surface fitting and achieving high-precision graphics on curved surfaces comparable to those on flat surfaces.

[0024] The entire process has clear parameters, strong controllability, good repeatability, and high stability and mass production capability. Attached Figure Description

[0025] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of the structure of the mask plate and the curved substrate provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the metal film layer with a central circular hole in a curved substrate provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of a curved substrate provided according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of the first mask plate provided according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the structure of the second mask plate provided according to an embodiment of the present invention.

[0026] The reference numerals in the attached figures include: 1, curved substrate; 2, metal film layer; 21, circular hole; 3, first mask plate; 31, circular through hole; 32, first receiving part; 33, first inner surface; 4, second mask plate; 41, second receiving part; 42, second inner surface. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0028] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0029] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, 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, and therefore should not be construed as a limitation on this invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0030] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0031] The invention will now be described in detail with reference to specific embodiments.

[0032] like Figures 1 to 5 As shown in the figure, an embodiment of the present invention provides a photolithographic mask for fabricating circular hole patterns on a curved substrate, comprising: a first mask 3 and a second mask 4 disposed opposite to each other, which are detachably connected by connecting bolts. A curved substrate 1 coated with photoresist is disposed between the first mask 3 and the second mask 4.

[0033] Specifically, a circular through-hole 31 is provided at the center of the first mask 3 for forming a circular hole pattern on the curved substrate 1 coated with photoresist. A first receiving portion 32 is provided on the side of the first mask 3 facing the curved substrate 1. A second receiving portion 41 is provided on the side of the second mask 4 facing the curved substrate 1. The first receiving portion 32 and the second receiving portion 41 together form a receiving space for fixing the curved substrate 1 coated with photoresist. The first receiving portion 32 has a first inner surface 33, the radius of curvature of which matches the radius of curvature of the first surface of the curved substrate 1 coated with photoresist. The second receiving portion 41 has a second inner surface 42, the radius of curvature of which matches the radius of curvature of the second surface of the curved substrate 1.

[0034] In this embodiment, both the first mask 3 and the second mask 4 are designed as circular structures. The first mask 3 has four through holes evenly distributed around its circumference, while the second mask 4 has four stepped holes distributed around its circumference. During fixing, the curved substrate 1 coated with photoresist is placed between the two masks, and connecting bolts are passed through the stepped holes of the second mask 4 and the through holes of the first mask 3, and then tightened with nuts to reliably clamp and fix the entire assembly.

[0035] A method for preparing a metal film structure with a central circular hole on a curved substrate, comprising the following steps: S1: Perform ultrasonic cleaning on the curved substrate 1.

[0036] Specifically, the curved substrate 1 was ultrasonically cleaned sequentially with a cleaning agent, deionized water, and anhydrous ethanol (15 minutes each) to remove oil and impurities from its surface. Afterward, the curved substrate 1 was wiped clean and dried in an 80°C oven for 40 minutes. S2: Spin-coat photoresist onto the surface of curved substrate 1 and perform pre-baking treatment.

[0037] The photoresist is a negative photoresist, the spin coating speed is 1000 r / min to 2000 r / min, the photoresist layer thickness is 1 μm to 5 μm, the pre-baking temperature is 80℃ to 100℃, and the time is 20 to 40 minutes.

[0038] In this embodiment, the spin coating speed is 1500 r / min, the adhesive layer thickness is 2 μm, the pre-baking temperature is 85℃, and the time is 30 minutes.

[0039] S3: Expose and develop the photoresist-coated curved substrate 1 using a photomask to form a circular hole pattern with clear edges. Exposure is performed using 365nm ultraviolet light for 5 to 15 seconds; development is performed using ZX-238 alkaline developer for 20 to 30 seconds. Using a photomask has two major advantages: firstly, it provides good adhesion to the curved substrate 1; secondly, it avoids damage to the photoresist and the curved substrate 1; and thirdly, the dimensional accuracy of the circular holes can be within ±50μm.

[0040] In this embodiment, the exposure time is 10 seconds. The development time is 25 seconds.

[0041] S4: Perform a hardening treatment on the developed curved substrate 1. The hardening treatment temperature is 100℃ to 150℃, and the time is 30 to 40 minutes.

[0042] In this embodiment, the curved substrate 1 with the circular hole pattern, which has already been exposed and developed in step S3, is heat-treated at 100 degrees Celsius for 35 minutes. This treatment further cross-links the photoresist molecules, thereby hardening and enhancing the adhesion strength between the photoresist and the curved substrate 1.

[0043] S5: A metal film layer 2 is deposited on the surface of the curved substrate 1 using physical vapor deposition.

[0044] Physical vapor deposition is a vacuum deposition method with a vacuum level of 1×10⁻⁶. -4 Pa to 5×10 -4 Pa, with deposition rates ranging from 30 nm / s to 45 nm / s.

[0045] In this embodiment, the vacuum degree is 3×10 -4 Pa, deposition rate is 40 nm / s.

[0046] S6: Remove residual photoresist to obtain the metal film structure with a central circular hole in the curved substrate.

[0047] The photoresist is removed by immersion in an organic solvent for 50 to 80 minutes.

[0048] In this embodiment, the soaking time is 60 minutes.

[0049] A curved substrate central circular hole metal film structure prepared by the above-described preparation method includes: a curved substrate 1 and a metal film 2, wherein the curved substrate 1 has a predetermined radius of curvature. The metal film 2 covers the surface of the curved substrate 1. The metal film 2 has a circular hole 21 to expose the surface of the curved substrate 1.

[0050] The radius of curvature of the upper surface of the curved substrate 1 is not equal to the radius of curvature of the lower surface of the curved substrate 1. In this embodiment, the diameter of the curved substrate 1 is φ72mm and the thickness is 5mm. The radius of curvature of the upper surface of the curved substrate 1 is 652.03mm, and the radius of curvature of the lower surface of the curved substrate 1 is 446.23mm.

[0051] The metal film 2 is made of aluminum, gold, silver, or copper. The thickness of the metal film 2 is between 100 nm and 500 nm. In this embodiment, the metal film 2 is an aluminum film with a thickness of 300 nm.

[0052] In summary, the curved substrate central circular hole metal film structure, preparation method, and dedicated mask provided by this invention have the following outstanding advantages: By replacing traditional mechanical etching and mask coating with photolithography, "edge halos" and mechanical errors are fundamentally eliminated, enabling the size and positional accuracy of circular holes to reach within ±50μm. Combined with physical vapor deposition and hardening treatment, a uniform, dense, and strongly adherent metal film layer is obtained.

[0053] The design of the receiving part of the special mask plate is precisely adapted to the curvature of the substrate, solving the problem of surface fitting and achieving high-precision graphics on curved surfaces comparable to those on flat surfaces.

[0054] The entire process has clear parameters, strong controllability, good repeatability, and high stability and mass production capability.

[0055] This method is compatible with traditional microfabrication processes, has controllable costs, and provides a reliable solution for the manufacture of high-performance curved surface optoelectronic devices, with broad market prospects.

[0056] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A photomask for preparing a round hole pattern on a curved substrate, characterized by, The application relates to a mask plate for preparing a curved surface substrate with a central hole. The application relates to a mask plate for preparing a curved surface substrate with a central hole. The application relates to a mask plate for preparing a curved surface substrate with a central hole. The application relates to a mask plate for preparing a curved surface substrate with a central hole. The application relates to a mask plate for preparing a curved surface substrate with a central hole. The application relates to a mask plate for preparing a curved surface substrate with a central hole.

2. A method for preparing a curved substrate central circular hole metal film layer structure, using the photolithography mask plate of claim 1, characterized in that, The application relates to a mask plate for preparing a curved surface substrate with a central hole. The application relates to a mask plate for preparing a curved surface substrate with a central hole. The application relates to a mask plate for preparing a curved surface substrate with a central hole. The application relates to a mask plate for preparing a curved surface substrate with a central hole. The application relates to a mask plate for preparing a curved surface substrate with a central hole. The application relates to a mask plate for preparing a curved surface substrate with a central hole. The application relates to a mask plate for preparing a curved surface substrate with a central hole.

3. The method of claim 2, wherein the method further comprises: The application relates to a mask plate for preparing a curved surface substrate with a central hole.

4. The method of claim 2, wherein the method further comprises: The application relates to a mask plate for preparing a curved surface substrate with a central hole.

5. The method of claim 2, wherein the method further comprises: The application relates to a mask plate for preparing a curved surface substrate with a central hole.

6. The method of claim 2, wherein the method further comprises: In step S5, the physical vapor deposition method is vacuum plating, the vacuum degree is 1 x 10 -4 Pa to 5 x 10 -4 Pa, and the deposition rate is 30 nm / s to 45 nm / s.

7. The method of claim 2, wherein the method further comprises the step of: The application relates to a mask plate for preparing a curved surface substrate with a central hole. ​ 8. A structure of a metal film layer on a central hole of a curved substrate, prepared by the method of any one of claims 2 to 7, characterized in that, The application relates to a mask plate for preparing a curved surface substrate with a central hole. The application relates to a mask plate for preparing a curved surface substrate with a central hole. The application relates to a mask plate for preparing a curved surface substrate with a central hole.

9. The curved substrate center hole metal film layer structure of claim 8, wherein, The application relates to a mask plate for preparing a curved surface substrate with a central hole.

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