Nanoimprint template and method for manufacturing the same

Abstract

The application relates to the field of nano-imprinting technology and discloses a nano-imprinting template and a preparation method thereof. The nano-imprinting template comprises a gas storage part and an imprinting layer, and the imprinting layer has an imprinting pattern. The gas storage part has a first opening facing the imprinting layer, and the imprinting layer covers the first opening to form a gas storage cavity together with the gas storage part. The gas storage part has a gas inlet communicating with the gas storage cavity. When air is introduced into the gas storage cavity through the gas inlet, the pressure in the gas storage cavity gradually increases and drives the imprinting layer to protrude outward, and the middle part of the imprinting layer is first raised, and gradually raised to the periphery with the increase of the air amount. In the above process, the curvature of the imprinting layer can be controlled by the amount of air introduced into the gas storage cavity. When the imprinting operation is performed, the middle pattern of the imprinting layer is first imprinted on the substrate, and then gradually imprinted to the periphery, so that the air is gradually driven away in a step-by-step manner, and the gas under the imprinting layer is not completely removed, thereby affecting the product yield.

Description

Technical Field

[0001] This invention relates to the field of nanoimprint technology, and in particular to a nanoimprint template and its preparation method. Background Technology

[0002] As the size of micro and nano devices continues to shrink, the fabrication difficulty increases. Although optical lithography is the mainstream lithography technology for micro and nano manufacturing, the high operating and maintenance costs of the equipment, as well as the complex exposure optical system, are still limited by the diffraction limit of the exposure wavelength. Nanoimprint lithography offers advantages such as relatively simple and efficient processes (e.g., large-area fabrication and high throughput), low cost, and reusable imprint templates. It can simultaneously fabricate hundreds or thousands of micro and nano structures without requiring the complex optical systems of optical exposure or the complex electromagnetic focusing systems of electron beam lithography. Furthermore, due to the absence of diffraction phenomena in optical exposure and scattering phenomena in electron beam lithography, nanoimprint lithography can produce high-resolution patterns with a resolution below 5 nm.

[0003] Nanoimprint lithography, with its advantages of high resolution, low cost, fewer process steps, high speed, and the ability to fabricate various nanoscale structures, has become a strong competitor to photolithography. Step lithography is compatible with large-size silicon processes, offers low mold fabrication costs, and produces superior pattern quality compared to optical exposure of the same size, while significantly reducing equipment and operating costs. However, since the transfer of microstructures in step lithography requires a boss template, fabricating a high-precision, highly uniform, highly flat, and high-fidelity imprint template is one of the core challenges of the entire process.

[0004] If air is not removed in time during multiple step-by-step imprinting processes, it will lead to insufficient product yield. Summary of the Invention

[0005] This invention discloses a nanoimprint template and its preparation method, which is used to remove air in a timely manner during the nanoimprint template imprinting process to improve yield.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] In a first aspect, a nanoimprint template is provided, comprising: a gas storage portion and an imprint layer, the imprint layer having an imprint pattern; the gas storage portion having a first opening facing the imprint layer, the imprint layer covering the first opening to form a gas storage cavity with the gas storage portion; the gas storage portion having an air inlet communicating with the gas storage cavity.

[0008] When air is introduced into the gas storage chamber through the air inlet, the pressure inside the gas storage chamber gradually increases, driving the imprinted layer to bulge outward. The center of the imprinted layer bulges first, and then gradually bulges outward as the air intake increases. During the above process, the curvature of the imprinted layer can be controlled by the amount of air introduced into the gas storage chamber. When the imprinting operation is performed, the central pattern of the imprinted layer is first imprinted onto the substrate, and then gradually imprinted outward. In this way, the air is gradually driven away by imprinting from the center outward in a step-by-step manner, so as to avoid the gas under the imprinted layer not being completely removed, which would affect the product yield.

[0009] Optionally, the gas storage section includes a rigid support layer and an elastic buffer layer, the buffer layer being located between the support layer and the imprinted layer; the buffer layer has a hollow structure, one end of the hollow structure forming the first opening and the other end forming a second opening, the support layer covering the second opening, and the imprinted layer, the buffer layer, and the support layer forming the gas storage cavity; the position of the support layer opposite to the hollow structure forms the air inlet.

[0010] Optionally, the light transmittance of the support layer is greater than or equal to 90%; the light transmittance of the buffer layer is greater than or equal to 87%; and the light transmittance of the embossing layer is greater than or equal to 87%.

[0011] Optionally, the Young's modulus of the support layer is greater than or equal to 400 MPa, the Young's modulus of the buffer layer is greater than or equal to 50 MPa and less than or equal to 200 MPa, and the Young's modulus of the embossing layer is greater than or equal to 100 MPa and less than or equal to 350 MPa.

[0012] Optionally, the contact angle of the embossed layer is greater than or equal to 120°.

[0013] Optionally, the support layer comprises an acrylic sheet, silica glass, or quartz glass; and / or, the buffer layer comprises aliphatic polyurethane acrylate; and / or, the imprinting layer comprises perfluoroacrylate.

[0014] In a second aspect, a method for preparing a nanoimprint template is provided. The nanoimprint template includes a gas storage portion and an imprint layer, the imprint layer having an imprint pattern; the gas storage portion has an air inlet and a first opening; the method includes: covering and fixing the imprint layer to the first opening, so that the imprint layer and the gas storage portion form a gas storage cavity, wherein the air inlet is in communication with the gas storage cavity.

[0015] Compared with the prior art, the method for preparing nanoimprint templates has the same advantages as the nanoimprint templates themselves, and will not be elaborated further here.

[0016] Optionally, the gas storage unit includes a rigid support layer and an elastic buffer layer. The buffer layer has a hollow structure, with one end forming the first opening and the other end forming a second opening. The support layer covers the second opening, and the position of the support layer opposite to the hollow structure forms the air inlet. The buffer layer comprises aliphatic polyurethane acrylate. Covering and fixing the imprinted layer to the first opening specifically includes: placing the surface of the gas storage unit with the first opening on a silicon wafer spin-coated with perfluoroacrylate, so that the perfluoroacrylate is adsorbed into the crosslinked network of the buffer layer; placing the perfluoroacrylate adsorbed on the buffer layer onto a template with a preset pattern; curing the perfluoroacrylate to form an imprinted layer with the imprinted pattern, wherein the imprinted layer, the buffer layer, and the support layer enclose the gas storage cavity.

[0017] Optionally, the gas storage section includes an elastic buffer layer with a hollow structure, one end of which forms the first opening. The buffer layer is composed of aliphatic polyurethane acrylate. Covering and fixing the imprinted layer to the first opening specifically includes: placing the surface of the buffer layer with the first opening on a silicon wafer spin-coated with perfluoroacrylate, so that the perfluoroacrylate is adsorbed in the crosslinked network of the buffer layer; placing the perfluoroacrylate adsorbed on the buffer layer on a template with a preset pattern, and curing the perfluoroacrylate to form an imprinted layer with the imprinted pattern.

[0018] Optionally, the hollow structure has a second opening at the end away from the first opening. Before covering and fixing the imprinted layer to the first opening, the method further includes: attaching a support layer to the surface of the buffer layer with the second opening; applying adhesive to the joint between the support layer and the buffer layer and curing it; and removing the attached support layer and the buffer layer together from the silicon wafer.

[0019] Optionally, before attaching the rigid support layer to the surface of the buffer layer having the second opening, the method further includes: pre-cleaning the support layer with alcohol or acetone, treating the support layer with oxygen plasma, and using laser cutting to create an opening in the support layer to form the air inlet at a position corresponding to the hollow structure. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the nanoimprint template provided in the embodiments of this application;

[0021] Figure 2 express Figure 1 The inflation process of the structure shown;

[0022] Figures 3a to 3g In order to represent Figure 1 The diagram shows the steps involved in the preparation of the nanoimprint template. Detailed Implementation

[0023] 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.

[0024] refer to Figure 1 The nanoimprint template provided in this application includes: a gas storage portion 20 and an imprint layer 10, wherein the imprint layer 10 has an imprint pattern 11 (see reference). Figure 3g The gas storage section 20 has a first opening P1 facing the embossed layer 10, and the embossed layer 10 covers the first opening P1 to form a gas storage cavity K with the gas storage section 20; the gas storage section 20 has an air inlet 221 communicating with the gas storage cavity K. Specifically, the air inlet 221 can be connected to a pneumatic system to realize the inflation of the gas storage cavity K.

[0025] refer to Figure 2 From left to right, the diagram illustrates the process of gradually filling the air storage chamber K with air through the air inlet 221. The first state on the left represents the unfilled state. As air enters the air storage chamber K through the air inlet 221, the pressure inside the air storage chamber K gradually increases, causing the gas inside to expand. (Refer to...) Figure 2 In the second state starting from the left side, the pressure inside the gas storage chamber K drives the imprinted layer 10 to bulge outward, with the middle part of the imprinted layer 10 bulging first, and then... (referring to...) Figure 2 In the third state on the left, as the air intake increases, the raised part of the imprint layer 10 gradually diffuses from the center to the surrounding area. During the above process, the curvature of the imprint layer 10 can be controlled by the amount of air intake in the gas storage chamber K. When the imprinting operation is performed, the central pattern of the imprint layer 10 is first imprinted onto the substrate, and then gradually imprinted to the surrounding area. Thus, it contacts and imprints the substrate from the center to the surrounding area in a step-by-step manner, thereby realizing the transfer of the nanoscale imprint pattern 11 on the surface of the imprint layer 10, gradually driving away the air, and avoiding the gas under the imprint layer 10 not being completely removed, which would affect the product yield.

[0026] In one specific embodiment, the nanoimprint template can be a composite boss template, and the gas storage section 20 includes a rigid support layer 22. Figure 2(The structure is not shown in the diagram) and an elastic buffer layer 21, which is located between the support layer 22 and the imprint layer 10. The buffer layer 21 has a hollow structure 211, with a first opening P1 at one end and a second opening P2 at the other end. The support layer 22 covers the second opening P2. The imprint layer 10, the buffer layer 21, and the support layer 22 form a gas storage cavity K. An air inlet 221 is formed at the position opposite to the hollow structure 211 of the support layer 22. The rigid support layer 22 provides support for the buffer layer 21 and the imprint layer 10 and transmits the imprinting force from the imprinting equipment to the buffer layer 21. The buffer layer 21 can provide elastic buffering for the imprint layer 10, making the force borne by the imprint layer 10 from the buffer layer 21 more uniform and increasing the tolerance of the imprint layer 10 to the surface of the master template 41 to be replicated. The master template 41 can be made of different materials, such as metal, non-metal, and silicone rubber, all of which can meet the needs of stepper lithography.

[0027] The support layer 22, buffer layer 21, and imprint layer 10 are all transparent structures to facilitate the passage of light during step-imprint lithography. In one specific embodiment, the transmittance of the support layer 22 is greater than or equal to 90%; the transmittance of the buffer layer 21 is greater than or equal to 87%; and the transmittance of the imprint layer 10 is greater than or equal to 87%. The nanoimprint structure has high transmittance, which can meet the utilization of UV light and is energy-saving and environmentally friendly.

[0028] In a specific embodiment, the Young's modulus of the support layer 22 is greater than or equal to 400 MPa, and can be 400 MPa, 450 MPa, 500 MPa, and 600 MPa, etc., to satisfy the function of support and transmission of imprinting force. The Young's modulus of the buffer layer 21 is greater than or equal to 50 MPa and less than or equal to 200 MPa, and can be 50 MPa, 100 MPa, 150 MPa, and 200 MPa, etc., so as to satisfy the function of elastic buffering while also having a certain support function. The Young's modulus of the imprinting layer 10 is greater than or equal to 100 MPa and less than 350 MPa, and can be 100 MPa, 150 MPa, 200 MPa, 250 MPa, 300 MPa, and 350 MPa, etc. If it is too soft, the imprinting layer 10 will be too sensitive to air pressure and it will be difficult to control the curvature. If it is too hard, it will be difficult to use air pressure to drive the outward protrusion.

[0029] In one specific embodiment, the contact angle of the imprinted layer 10 is greater than or equal to 120°, and can be 120°, 130°, 135°, 140° and 150°, etc., thereby having a lower surface energy and being easy to detach after imprinting.

[0030] In one specific embodiment, the support layer 22 includes an acrylic sheet, silica glass, or quartz glass. These materials have good light transmittance, high hardness, and are readily available on the market. And / or, the buffer layer 21 comprises aliphatic polyurethane acrylate, which can simultaneously meet the above requirements for hardness and transparency, and has acrylate groups, facilitating bonding under light, thus facilitating 3D printing. In addition, it may also include a reactive diluent (for adjusting viscosity), aliphatic acrylate, an initiator (for initiating photoreaction), etc. And / or, the imprinting layer 10 comprises perfluoroacrylate, which can meet the above requirements for transparency and hardness, and also has acrylate groups, facilitating bonding with the buffer layer 21. In the embodiments of this application, A and / or B represent three cases: A, B, and A and B.

[0031] The aforementioned embossing template is a step embossing template with adjustable curvature, high precision, high uniformity, high flatness, and high fidelity, and can be reused multiple times.

[0032] Based on the same inventive concept, this application also provides a method for preparing a nanoimprint template. The nanoimprint template includes a gas storage portion 20 and an imprint layer 10, the imprint layer 10 having an imprint pattern 11; the gas storage portion 20 has an air inlet 221 and a first opening P1; the method includes: covering and fixing the imprint layer 10 to the first opening P1, so that the imprint layer 10 and the gas storage portion 20 form a gas storage cavity K, wherein the air inlet 221 communicates with the gas storage cavity K. The beneficial effects of this method can be referred to the description of the relevant effects of the nanoimprint template provided in the previous embodiments.

[0033] In one specific embodiment, the gas storage section 20 includes an elastic buffer layer 21, the buffer layer 21 having a hollow structure 211, one end of the hollow structure 211 forming a first opening P1; wherein, the component of the buffer layer 21 includes aliphatic polyurethane acrylate; covering and fixing the embossed layer 10 to the first opening P1 specifically includes: reference Figure 3d and Figure 3e The surface of the buffer layer 21 with the first opening P1 is placed on a silicon wafer 31 spin-coated with perfluoroacrylate, so that the perfluoroacrylate is adsorbed into the cross-linked network of the buffer layer 21, and the two are bonded by diffusion and adhesive absorption. Specifically, this can be left for about 10 minutes; Reference Figure 3f and Figure 3g The perfluoroacrylate adsorbed on the buffer layer 21 is placed on a template with a preset pattern (called the master template 41), and the perfluoroacrylate is cured to form an imprinted layer 10 with an imprinted pattern 11. The imprinted layer 10, the buffer layer 21 and the support layer 22 form a gas storage cavity K.

[0034] In one specific embodiment, before covering and fixing the imprint layer 10 to the first opening P1, the method further includes: referencing Figure 3a A buffer layer 21 is 3D printed on a fixed silicon wafer 31, which allows for flexible customization according to the specific shape of the buffer layer 21 and simplifies the processing technology. Before forming the buffer layer 21, the silicon wafer 31 can be pre-cleaned with alcohol or acetone and then treated with oxygen plasma for about 15 minutes to remove impurities. The printing solution for the 3D printed buffer layer 21 can be prepared as follows: 184 initiator is dissolved in hydroxyethyl acrylate, then 40% aliphatic polyurethane acrylate is added and stirred evenly, followed by vacuum degassing. The pattern outline is then designed and printed using a 3D printing stepper embossing stage.

[0035] In one specific embodiment, a second opening P2 is formed at the end of the hollow structure 211 away from the first opening P1. Before the step of covering and fixing the imprinted layer 10 to the first opening P1, the method further includes: referencing... Figure 3b The rigid support layer 22 is attached to the surface of the buffer layer 21 having the second opening P2; adhesive is applied to the joint between the support layer 22 and the buffer layer 21 and cured; (Refer to...) Figure 3c Remove the bonded support layer 22 and buffer layer 21 together from the silicon wafer 31 so that the support layer 22 and buffer layer 21 can be bonded together by adhesive to form the gas storage section 20.

[0036] In one specific embodiment, before attaching the rigid support layer 22 to the surface of the buffer layer 21 with the second opening P2, the process further includes: pre-cleaning the support layer 22 with alcohol or acetone, and then treating the support layer 22 with oxygen plasma to thoroughly remove impurities from the surface of the support layer 22, facilitating its bonding with the buffer layer 21. The oxygen plasma treatment time can be approximately 15 minutes. An opening is made in the support layer 22 using laser cutting, forming the aforementioned air inlet 221 at a position corresponding to the hollow structure 211, to facilitate air intake into the air storage chamber K. The support layer 22 with the air inlet 221 is then aligned with the adhesive-coated semi-hollow buffer layer 21 and UV-cured to ensure a stable bond between the two.

[0037] Obviously, those skilled in the art can make various modifications and variations to the embodiments of the present invention without departing from the spirit and scope of the invention. Therefore, if these modifications and variations fall within the scope of the claims of the present invention and their equivalents, the present invention also intends to include these modifications and variations.

Claims

1. A nanoimprint template, characterized in that, include: The gas storage section and the embossed layer have an embossed pattern; the gas storage section has a first opening facing the embossed layer, and the embossed layer covers the first opening to form a gas storage cavity with the gas storage section. The gas storage section has an air inlet that communicates with the gas storage cavity; The gas storage unit includes a rigid support layer and an elastic buffer layer, with the buffer layer located between the support layer and the imprinted layer; The buffer layer has a hollow structure, with one end of the hollow structure forming the first opening and the other end forming the second opening. The support layer covers the second opening, and the embossed layer, the buffer layer, and the support layer form the gas storage cavity. The air inlet is formed at the position where the support layer is opposite to the hollow structure.

2. The nanoimprint template according to claim 1, characterized in that, The light transmittance of the support layer is greater than or equal to 90%; the light transmittance of the buffer layer is greater than or equal to 87%; and the light transmittance of the embossing layer is greater than or equal to 87%.

3. The nanoimprint template according to claim 1, characterized in that, The Young's modulus of the support layer is greater than or equal to 400 MPa, the Young's modulus of the buffer layer is greater than or equal to 50 MPa and less than or equal to 200 MPa, and the Young's modulus of the embossing layer is greater than or equal to 100 MPa and less than or equal to 350 MPa.

4. The nanoimprint template according to claim 1, characterized in that, The contact angle of the embossed layer is greater than or equal to 120°.

5. The nanoimprint template according to claim 1, characterized in that, The support layer includes an acrylic sheet, silica glass, or quartz glass; and / or, The buffer layer comprises aliphatic polyurethane acrylate; and / or, The composition of the embossed layer includes perfluoroacrylate.

6. A method for preparing a nanoimprint template, characterized in that, The nanoimprint template includes a gas storage section and an imprint layer, the imprint layer having an imprint pattern; the gas storage section has an air inlet and a first opening; The method includes: The embossed layer is covered and fixedly connected to the first opening so that the embossed layer and the gas storage part form a gas storage cavity, wherein the air inlet is in communication with the gas storage cavity; The gas storage section includes an elastic buffer layer with a hollow structure. One end of the hollow structure forms the first opening. The buffer layer is composed of aliphatic polyurethane acrylate. The step of covering and fixing the imprinted layer to the first opening specifically includes: The surface of the buffer layer having the first opening is placed on a silicon wafer spin-coated with perfluoroacrylate, so that the perfluoroacrylate is adsorbed into the crosslinked network of the buffer layer; The perfluoroacrylate adsorbed on the buffer layer is placed on a template with a preset pattern, and the perfluoroacrylate is cured to form an imprinted layer with the imprinted pattern.

7. The method for preparing a nanoimprint template according to claim 6, characterized in that, The hollow structure has a second opening at the end away from the first opening. Before covering and fixing the imprinted layer to the first opening, the method further includes: The support layer is attached to the surface of the buffer layer having the second opening; Apply adhesive to the bonding area between the support layer and the buffer layer, and allow it to cure. The bonded support layer and the buffer layer are removed together from the silicon wafer.

8. The method for preparing a nanoimprint template according to claim 7, characterized in that, Before attaching the rigid support layer to the surface of the buffer layer having the second opening, the method further includes: The support layer is pre-cleaned with alcohol or acetone, then treated with oxygen plasma, and then laser-cut to create openings in the support layer to form the air inlet at a position corresponding to the hollow structure.

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