Method for manufacturing a microlens master mold and microlens master mold

Abstract

An embodiment of the present invention discloses a method for manufacturing a microlens master mold and the microlens master mold, including: depositing a metal connection layer on a substrate; coating a photoresist on the metal connection layer; lithographing a pattern on the photoresist to form a lithographic image; etching the metal connection layer to remove the metal connection layer between adjacent lithographic images; removing the photoresist; implanting metal spheres on the metal connection layer; performing a high-temperature vacuum reflow treatment on the metal spheres to form metal hemispheres, the outer diameter of the metal hemispheres being equal to the radius of the lithographic images; and curing the metal hemispheres by cooling to obtain the microlens master mold. Using the embodiment of the present invention can not only simplify the manufacturing process, but also realize the manufacturing of a microlens master mold with high precision, high density and high duty cycle by using conventional semiconductor processing techniques, greatly reducing the production cost. At the same time, the high-temperature vacuum reflow technology can be used to make the surface of the metal hemispheres as smooth as a mirror, greatly reducing the roughness of the metal hemispheres.

Description

Technical Field

[0001] The present invention relates to the technical field of microlenses, and particularly to a method for manufacturing a microlens master mold and a microlens master mold. Background Art

[0002] Microlens array devices are increasingly widely used in aspects such as focal plane light collection, laser collimation, large area array display, light efficiency enhancement, optical computing, optical interconnection, and micro scanning, and their manufacturing methods and processes have been increasingly deeply studied.

[0003] Currently, the manufacturing method of microlens array devices is as follows: First, a casting mold or a hot pressing mold is made using a lens master mold, and then a resin lens is cast or hot pressed on the casting mold or the hot pressing mold using a resin material. The technical developers found that the lens master mold in the prior art is made by a milling and forging process, which requires repeated processing, has a complex process, and a high cost. Summary of the Invention

[0004] In view of this, embodiments of the present invention propose a method for manufacturing a microlens master mold and a microlens master mold to solve the above technical problems.

[0005] An embodiment of the present invention proposes a method for manufacturing a microlens master mold, including: depositing a metal connection layer on a substrate; coating a photoresist on the metal connection layer; lithographing a pattern on the photoresist to form a lithographic image; etching the metal connection layer to remove the metal connection layer between adjacent lithographic images; removing the photoresist; implanting metal spheres on the metal connection layer; performing a high-temperature vacuum reflow treatment on the metal spheres to form metal hemispheres, the outer diameter of the metal hemispheres being equal to the radius of the lithographic image; and curing the metal hemispheres by cooling to obtain a microlens master mold.

[0006] Optionally, implanting metal spheres on the metal connection layer includes: laying a wire mesh on the substrate, where the mesh holes of the wire mesh correspond one-to-one to the lithographic images; printing a soldering flux on the wire mesh, and the soldering flux passes through the mesh holes and is printed on the metal connection layer; removing the wire mesh; laying a steel mesh on the metal connection layer, where the mesh openings of the steel mesh correspond one-to-one to the lithographic images; the metal spheres pass through the mesh openings and fall on the soldering flux, and are fixed on the metal connection layer through the soldering flux; and removing the steel mesh.

[0007] Optionally, depositing a metal connection layer on a substrate includes: depositing a metal bonding layer on the substrate; and depositing an anti-diffusion layer on the metal bonding layer to form a metal connection layer.

[0008] Optionally, after removing the photoresist, it includes: performing plasma cleaning to remove residual photoresist.

[0009] An embodiment of the present invention further provides a microlens master mold manufactured by the microlens master mold manufacturing method as described above, which includes: a substrate, a metal connection layer, and at least one row of metal hemispheres. Each row of metal hemispheres includes at least one metal hemisphere, and the metal hemispheres correspond to the metal connection layer one by one. The metal hemispheres are fixed on the substrate through the metal connection layer.

[0010] Optionally, the metal connection layer includes a metal bonding layer and an anti-diffusion layer. The metal bonding layer is deposited on the substrate, the anti-diffusion layer is deposited on the metal bonding layer, and the metal hemispheres are disposed on the anti-diffusion layer.

[0011] Optionally, there are multiple rows of metal hemispheres on the substrate. The distance between adjacent two rows of metal hemispheres is equal. Each row of metal hemispheres includes multiple metal hemispheres, the distance between adjacent metal hemispheres is equal, and the distance between adjacent two rows of metal hemispheres is equal to the distance between adjacent metal hemispheres.

[0012] Optionally, the thickness of the anti-diffusion layer is ten times that of the metal bonding layer.

[0013] Optionally, the material of the anti-diffusion layer is gold, and the material of the metal bonding layer is titanium.

[0014] Optionally, the material of the metal hemisphere is a low-melting-point metal or alloy with a melting point lower than 500 °C.

[0015] The microlens master mold manufacturing method and the microlens master mold provided by the embodiment of the present invention deposit a metal connection layer on the substrate, coat a photoresist on the metal connection layer, form a photolithography image through a photolithography process, and then obtain a metal connection layer with the same shape and area as the photolithography image by removing the metal connection layer and the photoresist between adjacent photolithography images. A metal sphere is implanted on the metal connection layer, and the metal sphere is subjected to high-temperature reflow to obtain a metal hemisphere. The metal hemisphere is cooled and solidified to obtain the microlens master mold, which can not only simplify the manufacturing process, but also realize the manufacturing of a microlens master mold with high precision, high density and high duty cycle by using conventional semiconductor processing technology, greatly reducing the production cost. At the same time, the high-temperature vacuum reflow technology can be used to make the surface of the metal hemisphere as smooth as a mirror, greatly reducing the roughness of the metal hemisphere, realizing the manufacturing of a microlens master mold with ultra-low roughness, and being easy to clean and regenerate, and can be adapted to the manufacturing of various microlens master molds, with wide applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a flowchart of the microlens master mold manufacturing method according to the embodiment of the present invention.

[0017] Figure 2 is a manufacturing schematic diagram of the microlens master mold manufacturing method according to another embodiment of the present invention.

[0018] Figure 3 is a structural schematic diagram of the microlens master mold according to the embodiment of the present invention.

[0019] Figure 4 is Figure 2 An enlarged view of A in

[0020] Figure 5 is a cross-sectional view of the microlens master mold according to an embodiment of the present invention.

[0021] Figure 6 is Figure 5 An enlarged view of B in Detailed implementation manners

[0022] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. The same components are denoted by the same reference numerals. It should be noted that the terms "front", "rear", "left", "right", "upper" and "lower" used in the following description refer to the directions in the drawings, and the terms "inner" and "outer" refer to the directions towards or away from the geometric center of a specific component, respectively.

[0023] Figure 1 shows a flowchart of a method for manufacturing a microlens master mold according to an embodiment of the present invention. As Figure 1 shown, the method for manufacturing a microlens master mold according to an embodiment of the present invention includes:

[0024] S100, depositing a metal connection layer on a substrate;

[0025] As Figure 2 shown, the substrate 1 can be made of materials such as silicon, glass, and ceramic. The metal connection layer 3 is deposited on the substrate 1 by using an existing deposition process.

[0026] In this embodiment, the material of the metal connection layer 3 can be a metal such as titanium, nickel, chromium, molybdenum, aluminum, tantalum, or an alloy such as gold-titanium, tantalum-titanium, tungsten-titanium, nickel-titanium, tantalum-chromium, nickel-chromium, tungsten-chromium, palladium-titanium, palladium-chromium.

[0027] Preferably, the material of the metal connection layer 3 is a gold-titanium alloy to better bond the metal hemisphere 1.

[0028] S110, coating a photoresist on the metal connection layer;

[0029] As Figure 2 shown, the metal connection layer 3 is disposed on one of the plate surfaces and the circumferential end surface of the substrate 1 to better coat the photoresist 6. S120, lithographing a pattern on the photoresist to form a lithographic image;

[0030] As Figure 2 shown, a lithographic image is formed on the photoresist 6 by using an existing lithography process, and a lithographic window 7 is formed between adjacent lithographic images.

[0031] S130, Etch the metal connection layer to remove the metal connection layer between adjacent lithography images;

[0032] In this embodiment, an existing etching process can be used to remove the metal connection layer 3.

[0033] S140, Remove the photoresist;

[0034] In this embodiment, a stripping process is used to strip the photoresist 6 to remove the photoresist 6.

[0035] S150, Plant metal spheres on the metal connection layer;

[0036] After removing the photoresist 6, the shape and area of the remaining metal connection layer 3 are consistent with the lithography image. In this embodiment, the shape of the lithography image is circular.

[0037] In this embodiment, the metal spheres 8 can be planted on the metal connection layer 3 by using the BGA packaging technology (Ball Grid Array).

[0038] S160, Perform a high-temperature vacuum reflow process on the metal spheres to form metal hemispheres;

[0039] Among them, the outer diameter of the metal hemisphere 1 is equal to the radius of the lithography image, that is, the maximum cross-sectional area of the metal hemisphere 1 is equal to the area of the lithography image.

[0040] When performing high-temperature vacuum reflow on the metal spheres 8, different high-temperature temperatures and vacuum degrees can be set according to the different materials of the metal spheres, so as to precisely control the high-temperature temperature and vacuum degree, avoid oxidation of the metal spheres 8, and thus form metal hemispheres with excellent surface smoothness. Among them, the high-temperature vacuum reflow can adopt the high-temperature vacuum reflow technology in the existing technology.

[0041] In other embodiments, the metal spheres 8 can also be subjected to high-temperature reflow in an inert environment as long as oxidation of the metal spheres 8 can be avoided.

[0042] In this embodiment, the high temperature is a temperature higher than the melting point of the metal spheres 8, and the metal hemisphere 1 is half of the sphere.

[0043] S170, Cool and solidify the metal hemispheres to obtain the master mold of the microlens.

[0044] As Figure 3 shown, after cooling, the metal hemisphere 1 solidifies to obtain the master mold of the microlens.

[0045] The method for manufacturing a microlens master mold provided by the embodiment of the present invention deposits a metal connection layer on a substrate, coats a photoresist on the metal connection layer, forms a photolithographic image through a photolithography process, and then obtains a metal connection layer with the same shape and area as the photolithographic image by removing the metal connection layer and the photoresist between adjacent photolithographic images. Metal spheres are implanted on the metal connection layer, and the metal spheres are subjected to high-temperature reflow to obtain metal hemispheres. The metal hemispheres are cooled and cured to obtain the microlens master mold. This method can not only simplify the manufacturing process, but also use conventional semiconductor processing techniques to manufacture microlens master molds with high precision, high density, and high duty cycle, greatly reducing production costs. At the same time, the high-temperature vacuum reflow technology can be used to make the surface of the metal hemispheres as smooth as a mirror, greatly reducing the roughness of the metal hemispheres, realizing the manufacturing of microlens master molds with ultra-low roughness, and being easy to clean and regenerate, adaptable to the manufacturing of various microlens master molds, with wide applicability.

[0046] For the microlens master mold manufactured by the method for manufacturing a microlens master mold provided by the embodiment of the present invention, after long-term use, the surface finish of the metal hemisphere decreases. Processes such as semiconductor cleaning, remelting, and reducing the metal can be used to regenerate the metal hemisphere, further reducing production costs. In this embodiment, the sphere diameter of the metal hemisphere 1 can be several micrometers to several millimeters.

[0047] Now, taking the specific manufacturing process of a certain microlens master mold as an example, the method for manufacturing a microlens master mold of the present invention is described as follows: Figure 2 as shown below:

[0048] S200, select a substrate;

[0049] In this embodiment, the shape of the substrate 2 is a circular plate.

[0050] S210, deposit a metal connection layer on the substrate;

[0051] In a specific embodiment of the present invention, as Figure 4 shown, S210 specifically includes:

[0052] S211, deposit a metal bonding layer 4 on the substrate 2 by a deposition process;

[0053] S212, deposit an anti-diffusion layer 5 on the metal bonding layer 4.

[0054] By setting the metal connection layer 4 as the anti-diffusion layer 5 and the metal bonding layer 4, while ensuring the firm connection of the metal hemisphere 1, it can also prevent the metal hemisphere 1 from diffusing into the metal connection layer 3 or the substrate 2, further ensuring the formed sphere diameter of the metal hemisphere 1 and the surface finish of adjacent metal hemispheres 1.

[0055] S220, coat a photoresist on the metal connection layer;

[0056] S230, lithographically pattern the photoresist to form a lithographic image;

[0057] S240, etch the metal connection layer to remove the metal connection layer between adjacent lithographic images;

[0058] S250, perform a stripping process to remove the photoresist;

[0059] S260, perform plasma cleaning to remove the residual photoresist;

[0060] Use an existing plasma cleaning process to clean the photoresist and completely remove the residual photoresist.

[0061] S270, implant metal spheres on the metal connection layer;

[0062] In this embodiment, S270 specifically includes:

[0063] S271, lay a wire mesh on the substrate, where the mesh holes of the wire mesh correspond one-to-one with the lithographic images;

[0064] The wire mesh is laid on the substrate 1, and the mesh holes are sleeved on the metal connection layer 3 that has the same area and shape as the lithographic image.

[0065] S272, print a solder flux on the wire mesh, and the solder flux passes through the mesh holes and is printed on the metal connection layer;

[0066] S273, remove the wire mesh;

[0067] S274, lay a stencil on the metal connection layer, where the openings of the stencil correspond one-to-one with the lithographic images;

[0068] S275, the metal spheres pass through the openings and land on the solder flux, and are fixed on the metal connection layer through the solder flux;

[0069] S276, remove the stencil.

[0070] By printing the solder flux on the metal connection layer 3, the metal spheres can be prevented from moving, ensuring that the metal hemispheres 1 are formed on the metal connection layer 3. Moreover, by placing the metal spheres 8 through the stencil, the placement efficiency of the metal spheres 8 can be ensured, thereby improving the ball implantation efficiency and reducing the production cost.

[0071] S280, perform a high-temperature vacuum reflow process on the metal pillars to form metal hemispheres;

[0072] During the high-temperature reflow process, the solder flux evaporates and does not affect the surface smoothness of the metal hemispheres 1.

[0073] S290, the metal hemispheres are cooled and solidified to obtain a micro-lens master mold.

[0074] The method for manufacturing a microlens master mold provided by the embodiment of the present invention removes the photoresist through the film stripping and plasma cleaning processes, which can ensure the cleanliness of the microlens master mold, ensure better forming of the metal hemispheres and the smoothness of the surface.

[0075] Further, the thickness of the anti-diffusion layer 5 is greater than that of the metal bonding layer 4, so as to better prevent the metal hemispheres 1 from diffusing into the metal connection layer 3 or the substrate 2.

[0076] Preferably, the thickness of the anti-diffusion layer 5 is ten times the thickness of the metal bonding layer 4, which can further prevent the metal hemispheres 1 from diffusing into the metal connection layer 3 or the substrate 2.

[0077] Further, the thickness of the anti-diffusion layer is 480 - 510 nanometers, and the thickness of the metal bonding layer is 480 - 510 nanometers.

[0078] In this embodiment, the thickness of the anti-diffusion layer 5 is about 500 nanometers, and the thickness of the metal bonding layer 4 is about 50 nanometers.

[0079] Further, the material of the anti-diffusion layer 5 is gold, and the material of the metal bonding layer 4 is titanium to save costs.

[0080] Based on the above method for manufacturing a microlens master mold, the embodiment of the present invention further provides a microlens master mold, as Figure 3 shown, which includes: a substrate 1 and at least one row of metal hemisphere parts.

[0081] Each row of metal hemisphere parts includes at least one metal hemisphere 1, and the metal hemisphere 1 is fixed on the substrate 2 and is in surface contact with the substrate 1.

[0082] In Figure 3 the embodiment, multiple rows of metal hemisphere parts are arranged on the substrate 1, and there is a gap between adjacent two rows of metal hemisphere parts.

[0083] Preferably, the distance between adjacent two rows of metal hemisphere parts is equal to facilitate the arrangement of the metal hemisphere parts.

[0084] As Figure 5 shown, each row of metal hemisphere parts includes multiple metal hemispheres 1, and there is a gap between adjacent metal hemispheres 1.

[0085] Preferably, the distance between adjacent metal hemispheres 1 is equal to further facilitate the arrangement of the metal hemispheres 1.

[0086] Preferably, the distance between adjacent metal hemispheres 1 is equal to the distance between adjacent two rows of metal hemisphere parts, which can further facilitate the arrangement and setting of the metal hemispheres 1.

[0087] Further, as Figure 6As shown, the microlens master mold further includes a metal connection layer 3. The metal hemisphere 1 is fixed on the substrate 1 through the metal connection layer 3 to ensure the firm connection of the metal hemisphere 1.

[0088] In this embodiment, the material of the metal hemisphere 1 is a low-melting-point metal or alloy with a melting point lower than 500°C. For example, alloys such as gold-tin, tin-lead, tin-silver-copper, tin-silver, indium-tin, or metals such as indium, tin, aluminum, etc.

[0089] Preferably, the material of the metal hemisphere 1 is gold-tin or tin-lead alloy, which has the ability to form a smooth-surface metal hemisphere at the reflow temperature, forming a metal hemisphere with excellent surface finish.

[0090] In a preferred embodiment, the spacing between adjacent metal hemispheres 1 is equal to the sphere diameter of the metal hemisphere 1, which not only facilitates the setting of the metal hemisphere 1 but also can add as few metal hemispheres 1 as possible, reducing the production cost.

[0091] The microlens master mold provided by the embodiment of the present invention deposits a metal connection layer on the substrate, coats a photoresist on the metal connection layer, forms a photolithography image through a photolithography process, then removes the metal connection layer and the photoresist between adjacent photolithography images to obtain a metal connection layer with the same shape and area as the photolithography image, plants the metal sphere on the metal connection layer, and performs high-temperature reflow on the metal sphere to obtain a metal hemisphere. After the metal hemisphere cools and solidifies, the microlens master mold is obtained. It can not only simplify the manufacturing process but also use conventional semiconductor processing technology to manufacture a microlens master mold with high precision, high density, and high duty cycle, greatly reducing the production cost. At the same time, the high-temperature vacuum reflow technology can be used to make the surface of the metal hemisphere as smooth as a mirror, greatly reducing the roughness of the metal hemisphere, realizing the manufacture of a microlens master mold with ultra-low roughness, and is easy to clean and regenerate, and can adapt to the manufacture of various microlens master molds, with wide applicability.

[0092] Above, the technical solutions of the present invention have been introduced in detail in combination with specific embodiments, and the described specific embodiments are used to help understand the idea of the present invention. The derivations and modifications made by those skilled in the art based on the specific embodiments of the present invention also fall within the protection scope of the present invention.

Claims

1. A method for manufacturing a microlens master mold, characterized in that, Comprising: Depositing a metal connection layer on a substrate; Coating a photoresist on the metal connection layer; Lithographing a pattern on the photoresist to form a lithographic image; Etching the metal connection layer to remove the metal connection layer between adjacent lithographic images; Removing the photoresist; Planting metal spheres on the metal connection layer: laying a wire mesh on the substrate, wherein the mesh holes of the wire mesh correspond one by one to the lithographic images; Printing a solder flux on the wire mesh, and the solder flux passes through the mesh holes and is printed on the metal connection layer; Removing the wire mesh; Laying a stencil on the metal connection layer, and the openings of the stencil correspond one by one to the lithographic images; The metal spheres pass through the openings and land on the solder flux, and are fixed on the metal connection layer through the solder flux; Removing the stencil; Performing a high-temperature vacuum reflow treatment on the metal spheres to form metal hemispheres, and the outer diameter of the metal hemispheres is equal to the radius of the lithographic images; The metal hemispheres are cooled and solidified to obtain a micro-lens master mold.

2. The method for manufacturing a microlens master mold according to claim 1, wherein, Depositing a metal connection layer on a substrate includes: Depositing a metal bonding layer on the substrate; Depositing an anti-diffusion layer on the metal bonding layer to form a metal connection layer.

3. The method for manufacturing a microlens master mold according to claim 1 or 2, characterized in that, After removing the photoresist includes: Performing plasma cleaning to remove residual photoresist.

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