A method for preparing a surface of an optical superabsorbent material

Abstract

A method for preparing a super-absorbing material surface, belonging to the field of micro-nano fabrication technology, addresses the problems of complex preparation methods, odd shapes, long processing times, and difficulty in large-area fabrication in existing technologies. This method is based on template manufacturing technology and high-temperature annealing to form metal microspheres, as well as nanoimprint transfer and isotropic chemical etching with moldable materials to form an ultra-high aspect ratio conical structure. The conical structure formed by the high-temperature annealing process and noble metal-induced etching in this invention has an ultra-high aspect ratio, achieving anti-reflection and super-absorption properties in the visible to infrared bands. This invention can be applied to infrared imaging, thermal emitters, electromagnetic shielding, photoelectric detection, and photoelectric signal detection. This invention has advantages such as super-absorption performance, good extinction properties, good durability, good adaptability, and high productivity, enabling large-scale production of super-absorbing material surfaces and allowing for their widespread application in various optical devices.

Description

Technical Field

[0001] This invention relates to a method for preparing the surface of a light superabsorbing material, belonging to the field of micro-nano fabrication technology. Background Technology

[0002] With the rapid development of micro-nano fabrication technology, it provides technical support for the development of metamaterials. Metamaterials are artificially manufactured materials that do not exist in nature and exhibit unique electromagnetic properties, including negative refractive index, electromagnetic wave masking, inverse Doppler effect, laser properties, asymmetric light transmission, and artificial magnetism. Among them, optical superabsorbing materials have been extensively studied. Optical superabsorbing materials are materials that, when illuminated, do not transmit light or exhibit blocky flares, and reflect light with minimal reflection after entering the material, thus improving the material's extinction performance and durability. The surface of optical superabsorbing materials has great application potential in fields such as photoelectric detection, biomedicine, refractive index sensors, solar energy absorption, and stealth technology. Traditional optical absorbing materials are produced by depositing single-layer or multi-layer thin films on their surface. However, single-layer films can only act on specific wavelengths, and multi-layer films suffer from mismatch and mechanical stability issues, preventing the widespread application of absorbing materials in various optical devices.

[0003] With the realization of metamaterials, a new type of light-absorbing material, namely superabsorbent materials, has attracted widespread attention. Superabsorbent material surfaces represent a novel light-absorbing method, inspired by the structure of a moth's eye. This involves making the structural period shorter than the wavelength in the visible light range and the height greater than half the wavelength in the near-infrared range, thereby achieving superabsorption properties. However, most current methods for preparing superabsorbent surfaces are complex, have unusual shapes, are time-consuming, and are difficult to fabricate on a large scale.

[0004] See the literature "Applied Physics Letters", in which the author Azar published a paper "Bull's eyegrating integrated with optical nanoantennas for plasmonic enhancement of graphene long-wave infrared photodetectors". This method designs a metal bullseye grating and introduces optical nanoantennas. However, this method of absorbing electromagnetic waves is complex, has an odd shape, is time-consuming, and is difficult to fabricate on a large scale. Summary of the Invention

[0005] This invention addresses the problems of complex preparation methods, odd shapes, long processing times, and difficulty in large-area fabrication in existing technologies. It provides a method for preparing the surface of a light-absorbing superabsorbent material that is efficient and suitable for large-scale production.

[0006] The technical solution of this invention to solve the technical problem is:

[0007] A method for preparing the surface of a light-absorbing superabsorbent material, characterized by the method being based on template manufacturing technology and high-temperature annealing to form noble metal microspheres and nanoimprint transfer with moldable materials to form an isotropic chemical etching ultra-high aspect ratio conical structure. The specific steps are as follows:

[0008] Step 1, Pre-treatment, coating an anti-reflection layer and photoresist on the surface of a single-crystal silicon substrate: The single-crystal silicon substrate coated with the anti-reflection layer and photoresist is exposed by a Talbot shift lithography machine to form a periodic dot matrix groove structure.

[0009] Step 2, coating, depositing a noble metal layer on a single crystal silicon substrate: deposit a noble metal layer on the substrate obtained in Step 1, and at the same time use a lift-off process to remove the photoresist, leaving a noble metal film matrix.

[0010] Step 3, noble metal layer is transformed into noble metal microspheres: noble metal microspheres are precipitated on the surface of the substrate with the deposited noble metal layer obtained in step 2 using a high-temperature annealing process;

[0011] Step 4, forming a deep hole array on a single-crystal silicon substrate: The substrate with noble metal spheres on the surface obtained in step 3 is placed in a mixture of hydrofluoric acid and hydrogen peroxide to perform anisotropic etching of noble metals to form a deep hole array.

[0012] Step 5, forming a cone-shaped structure on a single-crystal silicon substrate: using isotropic chemical etching, the substrate with deep hole array obtained in step 4 is placed in the etching solution for isotropic etching, forming a cone-shaped hole array on the basis of the deep holes.

[0013] Step 6, Pattern Transfer: The moldable material is placed in a nanoimprinting device, and the conical array obtained in step 5 is transferred onto the molding material through nanoimprinting to form the final shape.

[0014] In step 5, the concentration of the etchant used in the isotropic chemical etching is HF (49%): HNO3 (70%): HAc (100%).

[0015] A method for preparing a surface of a light-absorbing material produces a surface of a light-absorbing material characterized by forming a conical structure with an ultra-high aspect ratio on a single-crystal silicon substrate using template manufacturing technology and high-temperature annealing to form noble metal microspheres and nanoimprint transfer isotropic chemical etching with moldable materials.

[0016] The nanocone has a conical structure with the following structural parameters: the distance between the centers of the base surfaces of the cone is 100nm-1μm, the height is 400nm-5000nm, and the aspect ratio is approximately 3-10.

[0017] The moldable material is a mixture of carbon nanospheres and resin material, or a black silicone rubber material.

[0018] The beneficial effects of this invention are as follows:

[0019] (1) The cone-shaped structure formed by the high-temperature annealing process and noble metal induced etching in the method of the present invention has an ultra-high aspect ratio and can achieve anti-reflection and super absorption performance in the visible light to infrared band.

[0020] (2) The isotropic etching structure formed in this method is a conical structure, which can achieve a gradient refractive index.

[0021] (3) The method uses the controllable period of the structure formed by the Talber displacement lithography, which makes the final structure have good anti-reflection performance and the period of the unit array structure is controlled within the subwavelength range.

[0022] (4) This method uses nanoimprint technology to achieve large-area continuous production, reduce the manufacturing cost of devices, and can be used for large-scale preparation.

[0023] (5) This invention can be applied to fields such as infrared imaging, thermal emitters, electromagnetic shielding, photoelectric detection, and photoelectric signal detection. This invention has advantages such as super absorption performance, good extinction properties, good durability, good adaptability, and high productivity, which can realize the large-scale production of super absorption material surfaces, enabling the super absorption surfaces to be widely used in various optical devices. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the process for preparing a surface of a light superabsorbing material according to the present invention.

[0025] Figure 2 This is a schematic diagram of a sample after the present invention has been coated with an anti-reflective coating and photoresist.

[0026] Figure 3 This is a schematic diagram of a sample after exposure using Tiber displacement lithography according to the present invention.

[0027] Figure 4 This is a schematic diagram of a sample from which precious metal microspheres are precipitated using a high-temperature annealing process according to the present invention.

[0028] Figure 5 This is a schematic diagram of a sample after the deposition of a noble metal layer according to the present invention.

[0029] Figure 6 This is a schematic diagram of a sample after etching induced by precious metals according to the present invention.

[0030] Figure 7 This is a schematic diagram of a sample after being corroded using isotropic chemical etching according to the present invention.

[0031] Figure 8 This is a schematic diagram of the final form of the sample obtained by the present invention based on nanotechnology.

[0032] In the figure, the labels are as follows: 1 is photoresist; 2 is anti-reflective coating; 3 is single-crystal silicon substrate (single-sided polished silicon wafer); 4 is periodic dot lattice groove structure; 5 is noble metal layer; 6 is noble metal spheres; 7 is deep hole array; 8 is conical array; 9 is moldable material. Detailed Implementation

[0033] The following embodiments will further illustrate the present invention with reference to the accompanying drawings.

[0034] like Figure 1 As shown, a method for preparing the surface of a light-absorbing superabsorbent material is described. This method is based on template manufacturing technology and high-temperature annealing to form noble metal microspheres and a high aspect ratio conical structure formed by nanoimprint transfer isotropic chemical etching with moldable materials. The steps are as follows:

[0035] Step 1, Pre-treatment, coating an anti-reflection coating 2 and photoresist 1 on the surface of a single-crystal silicon substrate 3: expose the single-crystal silicon substrate 3 after coating with anti-reflection coating 2 and photoresist 1 through a Talbo shift lithography machine to form a periodic dot matrix groove structure 4.

[0036] Step 2, coating, depositing a noble metal layer 5 on a single crystal silicon substrate 3: deposit a noble metal layer 5 on the substrate with periodic dot lattice groove structure 4 obtained in Step 1, while using a lift-off process to remove the photoresist 1, leaving the noble metal film dot lattice.

[0037] Step 3, noble metal layer 5 is transformed into noble metal microspheres 6: noble metal microspheres 6 are precipitated on the surface of the substrate with the deposited noble metal layer 5 obtained in step 2 using a high-temperature annealing process.

[0038] Step 4, forming a deep hole array 7 on a single-crystal silicon substrate 3: The substrate with noble metal spheres 6 obtained in step 3 is placed in a mixture of hydrofluoric acid and hydrogen peroxide to perform anisotropic etching of noble metals to form a deep hole array 7.

[0039] Step 5, forming a cone array 8 on the single crystal silicon substrate 3: using isotropic chemical etching, the substrate with deep hole array 7 obtained in step 4 is placed in the etching solution for isotropic etching, forming a cone hole array 8 on the basis of the deep hole array 7.

[0040] Step 6, Pattern Transfer: Place the moldable material 9 into the nanoimprinting device, and transfer the cone array 8 obtained in step 5 onto the moldable material 9 through nanoimprinting to form the final shape.

[0041] The precious metal can be silver, gold, or copper.

[0042] The moldable material is a mixture of carbon nanospheres with a particle size of 20 nm and a silicone rubber film.

[0043] The nanocone structure is a cone structure with the following structural parameters: the distance between the centers of the cone base is 100nm-1000nm, the height is 300-5000nm, and the aspect ratio is 3-10.

[0044] The diameter of the precious metal microspheres formed by the high-temperature annealing is 40nm-150nm.

[0045] In step 5, the concentration of the etchant used in the isotropic chemical etching is HF (49%): HNO3 (70%): HAc (100%).

[0046] A method for preparing a super-absorbing light material surface produces a super-absorbing light material surface, which is a cone-shaped structure with an ultra-high aspect ratio formed on a single-crystal silicon substrate by template manufacturing technology, high-temperature annealing to form noble metal microspheres, and nanoimprint transfer isotropic chemical etching with moldable materials.

[0047] Example:

[0048] A method for preparing the surface of a light-absorbing superabsorbent material, the specific steps of which are as follows:

[0049] (1) Pretreatment: an anti-reflection layer 2 and photoresist 1 are coated on the surface of a single-crystal silicon substrate 3.

[0050] ① Select a single-sided polished silicon wafer as the substrate. Place the monocrystalline silicon substrate 3 in acetone, anhydrous ethanol, and deionized water respectively, and sonicate for 10 minutes each. Then dry it with nitrogen gas for later use.

[0051] ② Coating anti-reflective coating 2 and photoresist 1, such as Figure 2 Pre-baking involves exposing a circular dot matrix grating with a period of 300 nm using a mask via Taber shift lithography. Post-baking and development result in a periodic dot array groove structure with a period of 300 nm, as shown in Figure 4. Figure 3 .

[0052] (2) Coating: depositing a silver metal layer 5 on a single-crystal silicon substrate 3.

[0053] ① The substrate with the periodic lattice groove structure 4 obtained in step (1) is placed in a coating machine, and a silver metal layer 5 with a thickness of 10 nm is deposited on its surface. The single crystal silicon surface 3 exposed to air obtained in step (1) is then brought into contact with the silver metal layer 5. Figure 4 .

[0054] (3) The silver metal layer 5 is transformed into silver metal spheres 6.

[0055] ① The substrate obtained in step (2) is annealed at a high temperature of 400-420℃ to form silver metal spheres 6 with a diameter of 40nm-80nm, such as Figure 5 .

[0056] (4) A deep hole array 7 is formed on a single-crystal silicon substrate 3.

[0057] ① The substrate obtained in step (3) is placed in a mixture of hydrofluoric acid and hydrogen peroxide. Metal-induced etching is used to control the concentration of the mixture and the etching time to form a deep hole array 7, such as Figure 6 .

[0058] (5) A cone-shaped structure 8 is formed on the single-crystal silicon substrate 3.

[0059] ① The substrate obtained in step (4) is placed in an etching solution with a concentration ratio of HF (49%):HNO3 (70%):HAc (100%) = 27:46:27 for isotropic chemical etching. A conical structure 8 is formed based on the deep hole array 7, such as... Figure 7 .

[0060] (6) Graphic transfer.

[0061] The moldable material 9 is placed in a nanoimprinting device, and the cone-shaped structure 8 obtained in step (5) is transferred onto the moldable material 9 using nanoimprinting technology to form the final shape, such as... Figure 8 .

Claims

1. A method for preparing a surface of a light-absorbing superabsorbent material, characterized in that, This method is based on template manufacturing technology and high-temperature annealing to form metal microspheres, as well as nanoimprint transfer and isotropic chemical etching to form ultra-high aspect ratio conical structures with moldable materials. The steps are as follows: Step 1, Pre-treatment, coating an anti-reflection layer and photoresist on the surface of a single-crystal silicon substrate: The silicon substrate coated with the anti-reflection layer and photoresist is exposed by a Talbo shift lithography machine to form a periodic dot matrix groove structure. Step 2, film deposition, depositing a noble metal layer on the silicon substrate: deposit a noble metal layer on the substrate obtained in Step 1, and at the same time use the lift-off process to remove the photoresist, leaving the metal film layer array; Step 3, converting the metal layer into metal microspheres: using a high-temperature annealing process, silver metal microspheres are deposited on the surface of the substrate with the silver deposited layer obtained in step 2. Step 4, forming a deep hole array on the silicon substrate: The substrate with metal spheres on the surface obtained in step 3 is placed in a mixture of hydrofluoric acid and hydrogen peroxide to perform anisotropic etching of noble metals to form a deep hole array. Step 5, forming a cone-shaped structure on the silicon substrate: using isotropic chemical etching, the substrate with deep hole array obtained in step 4 is placed into the etching solution for isotropic etching, forming a cone-shaped hole array on the basis of the deep holes. Step 6, Pattern Transfer: The moldable material is placed in a nanoimprinting device, and the conical array obtained in Step 5 is transferred onto the molding material through nanoimprinting to form the final shape; In step 5, the concentration of the etchant used in the isotropic chemical etching is HF (49%):HNO3 (70%):HAc (100%). The parameters of the conical structure are as follows: the distance between the centers of the bottom surfaces of the cone is 100nm-1μm, the height is 400nm-5000nm, and the aspect ratio is 3-10.

2. The light-absorbing material surface prepared by the method for preparing a light-absorbing material surface according to claim 1, characterized in that, A high aspect ratio conical structure is formed on a silicon substrate by template manufacturing technology and high-temperature annealing to form metal spheres and nanoimprint transfer with moldable materials through isotropic chemical etching.

3. A super-absorbing light material surface prepared by the method for preparing a super-absorbing light material surface according to claim 1, characterized in that, The moldable material is a mixture of carbon nanospheres and resin material or a black silicone rubber material.

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