Nanoimprint template and preparation method thereof

Abstract

The invention relates to the technical field of nanoimprint, and discloses a nanoimprint template and a preparation method thereof.The nanoimprint template comprises a gas storage part and an imprint layer, and the imprint layer is provided with an imprint pattern; the gas storage part is provided with a first opening facing the imprinting layer, and the imprinting layer covers the first opening so that a gas storage cavity can be defined by the imprinting layer and the gas storage part. The air storage part is provided with an air inlet communicated with the air storage cavity. When air enters the air storage cavity from the air inlet, the pressure in the air storage cavity is gradually increased, the imprinting layer is driven to protrude outwards, the middle of the imprinting layer protrudes firstly and gradually protrudes towards the periphery along with increase of the air inflow, and in the process, the curvature of the imprinting layer can be controlled according to the air inflow of the air storage cavity; when the imprinting operation is carried out, the pattern in the middle of the imprinting layer is firstly imprinted on the substrate and then gradually imprinted towards the periphery, so that imprinting is carried out from the middle to the periphery in a stepping mode, air is gradually driven away, and the situation that the product yield is affected due to the fact that gas below the imprinting layer is not completely exhausted is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of nanoimprinting, and in particular to a nanoimprinting template and a preparation method thereof. Background Art

[0002] As the size of micro-nano devices continues to develop in a smaller direction, the processing difficulty is becoming increasingly higher. Although optical lithography is the mainstream lithography technology for micro-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. The advantages of nanoimprint technology include relatively simple and efficient processes (such as large-area production and high production capacity), low cost, and reusable imprint templates; hundreds or thousands of micro-nano structure devices can be produced at the same time, but do not require a complex optical system like optical exposure or a complex electromagnetic focusing system like electron beam exposure. In addition, since there is no diffraction phenomenon in optical exposure and scattering phenomenon in electron beam exposure, nanoimprint technology can produce high-resolution graphics with a resolution of less than 5nm.

[0003] Nanoimprint technology has become a strong competitor to photolithography technology due to its high resolution, low cost, few process steps, high speed, and ability to prepare various nano-scale structures. Among them, stepper imprint is compatible with large-scale silicon processes, has low mold making costs, and better graphics quality than optical exposure results of the same size. At the same time, the equipment cost and operating cost are also greatly reduced compared to optical exposure. However, since the transfer of microscopic graphics in stepper imprint requires a boss template to be completed, the production of high-precision, high-uniformity, high-flatness and high-fidelity imprint templates is one of the core issues of the entire process.

[0004] During multiple step-by-step stamping processes, if the air is not exhausted in time, the product yield will be insufficient. Summary of the invention

[0005] The invention discloses a nanoimprint template and a preparation method thereof, which are used for timely removing air during the nanoimprint template imprinting process to improve the yield.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] In a first aspect, a nanoimprint template is provided, which includes: an air storage portion and an imprinting layer, the imprinting layer having an imprinting pattern; the air storage portion has a first opening facing the imprinting layer, the imprinting layer covers the first opening to form an air storage cavity with the air storage portion; the air storage portion has an air inlet connected to the air storage cavity.

[0008] When air is introduced into the air storage cavity from the air inlet, the pressure in the air storage cavity gradually increases, and drives the imprinting layer to bulge outward, and the middle part of the imprinting layer bulges first, and then gradually bulges toward the surrounding areas as the air intake increases. In the above process, the curvature of the imprinting layer can be controlled by the amount of air intake into the air 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 toward the surrounding areas, so that the air is gradually driven away by imprinting from the middle to the surrounding areas in a step-by-step manner, so as to avoid the gas under the imprinting layer not being completely discharged, affecting the product yield.

[0009] Optionally, the air storage portion includes a rigid supporting layer and an elastic buffer layer, wherein the buffer layer is located between the supporting layer and the embossing layer; the buffer layer has a hollow structure, wherein one end of the hollow structure forms the first opening, and the other end forms the second opening, and the supporting layer covers the second opening, and the embossing layer, the buffer layer and the supporting layer form the air storage cavity; the air inlet is formed at a position opposite to the supporting layer and the hollow structure.

[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 embossing layer is greater than or equal to 120°.

[0013] Optionally, the support layer includes an acrylic plate, silica glass or quartz glass; and / or, the buffer layer includes aliphatic polyurethane acrylate; and / or, the embossing layer includes perfluoro-based acrylate.

[0014] In a second aspect, a method for preparing a nanoimprint template is provided, wherein the nanoimprint template comprises an air storage portion and an imprinting layer, wherein the imprinting layer has an imprinting pattern; the air storage portion has an air inlet and a first opening; the method comprises: covering and fixing the imprinting layer to the first opening so that the imprinting layer and the air storage portion form an air storage cavity, wherein the air inlet is connected to the air storage cavity.

[0015] Compared with the prior art, the nanoimprint template preparation method has the same advantages as the nanoimprint template, which will not be described in detail here.

[0016] Optionally, the gas storage portion includes a rigid supporting layer and an elastic buffer layer, the buffer layer has a hollow structure, one end of the hollow structure forms the first opening, and the other end forms the second opening, the supporting layer covers the second opening, and the position of the supporting layer relative to the hollow structure forms the air inlet; wherein the buffer layer comprises aliphatic polyurethane acrylate; the step of covering and fixing the embossing layer to the first opening specifically includes: placing the surface of the gas storage portion having the first opening on a silicon wafer spin-coated with perfluoroacrylate so that the perfluoroacrylate is adsorbed in the cross-linked network of the buffer layer; placing the perfluoroacrylate adsorbed on the buffer layer on a template having a preset pattern, curing the perfluoroacrylate, and forming an embossing layer having the embossing pattern, wherein the embossing layer, the buffer layer and the supporting layer surround the gas storage cavity.

[0017] Optionally, the gas storage portion includes an elastic buffer layer, the buffer layer has a hollow structure, one end of the hollow structure forms the first opening, wherein the buffer layer includes aliphatic polyurethane acrylate; covering and fixing the imprinted layer to the first opening specifically includes: placing the surface of the buffer layer having the first opening on a silicon wafer spin-coated with perfluoroacrylate, so that the perfluoroacrylate is adsorbed in the cross-linked 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 having the imprinted pattern.

[0018] Optionally, a second opening is formed at one end of the hollow structure away from the first opening, and before the stamping layer is covered and fixedly connected to the first opening, the method further includes: laminating a supporting layer to a surface of the buffer layer having the second opening; applying glue at the joint between the supporting layer and the buffer layer, and curing the glue; and removing the laminating supporting layer together with the buffer layer from the silicon wafer.

[0019] Optionally, before laminating 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 open holes in the support layer to form the air inlet at a position corresponding to the hollow structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic diagram of the structure of a nanoimprint template provided in an embodiment of the present application;

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

[0022] Figure 3a to Figure 3g In turn, Figure 1 Schematic diagram of each step of the method for preparing the nanoimprint template. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

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

[0025] refer to Figure 2 , from left to right, it shows the process of gradually filling the air storage chamber K through the air inlet 221, wherein the first state on the left is the unfilled state. When air is introduced into the air storage chamber K from the air inlet 221, the pressure in the air storage chamber K gradually increases, and the gas in the air storage chamber K expands, and the pressure in the air storage chamber K increases. Figure 2 In the second state from the left side, the pressure in the air storage cavity K drives the embossed layer 10 to bulge outward, and the middle part of the embossed layer 10 bulges first, and then Figure 2 In the third state on the left side, as the air intake increases, the raised part of the imprint layer 10 gradually diffuses from the middle to the surroundings. In the above process, the curvature of the imprint layer 10 can be controlled by the amount of air intake in the air storage chamber K; when the imprinting operation is performed, the middle pattern of the imprint layer 10 is first imprinted on the substrate, and then gradually imprinted to the surroundings, so that it contacts and imprints with the substrate from the middle to the surroundings in a step-by-step manner, thereby realizing the transfer of the nano-scale 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 discharged, affecting the product yield.

[0026] In a specific embodiment, the nanoimprint template may be a composite boss template, and the gas storage portion 20 includes a rigid support layer 22 ( Figure 2The structure is not shown in the figure) and an elastic buffer layer 21, the buffer layer 21 is located between the support layer 22 and the imprint layer 10; the buffer layer 21 has a hollow structure 211, one end of the hollow structure 211 forms a first opening P1, and the other end forms a second opening P2, the support layer 22 covers the second opening P2, and the imprint layer 10, the buffer layer 21 and the support layer 22 surround the gas storage cavity K; the position of the support layer 22 relative to the hollow structure 211 forms an air inlet 221. The rigid support layer 22 provides support for the buffer layer 21 and the imprint layer 10, and transmits the imprint force from the imprinting device to the buffer layer 21; the buffer layer 21 can provide elastic buffering for the imprint layer 10, so that the force from the buffer layer 21 borne by the imprint layer 10 is more uniform, so that the imprint layer 10 has a higher tolerance for the surface of the master template 41 to be copied, and the master template 41 can be made of different materials, such as metal, non-metal and silicone rubber, which can meet the needs of stepper lithography.

[0027] The support layer 22, the buffer layer 21 and the imprint layer 10 are all transparent structures to facilitate the passage of light from the light source during step imprint lithography. In a specific embodiment, the light transmittance of the support layer 22 is greater than or equal to 90%; the light transmittance of the buffer layer 21 is greater than or equal to 87%, and the light transmittance of the imprint layer 10 is greater than or equal to 87%. The nanoimprint structure has a high light transmittance, 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 meet the support and transmission of the 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 meet the elastic buffering effect while having a certain support effect. 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 the hardness is too large, it will be difficult to use air pressure to drive the bulge.

[0029] In a specific embodiment, the contact angle of the embossed layer 10 is greater than or equal to 120°, and may be 120°, 130°, 135°, 140°, 150°, etc., so that the embossed layer 10 has a lower surface energy and is easy to release after embossing.

[0030] In a specific embodiment, the support layer 22 includes an acrylic plate, silica glass or quartz glass, which has good light transmittance, high hardness, and is easily available on the market; and / or, the composition of the buffer layer 21 includes aliphatic polyurethane acrylate, which can simultaneously meet the above requirements for hardness and transparency, and has an acrylate group, which is convenient for combination under the action of light, thereby facilitating 3D printing molding, and in addition, it can also include a reactive diluent (for adjusting viscosity), aliphatic acrylate, initiator (facilitating initiation of photoreaction), etc.; and / or, the composition of the embossing layer 10 includes perfluoro-based acrylate, which can meet the above requirements for transparency and hardness, and also has an acrylate group, which is convenient for combination with the buffer layer 21. In the embodiments of the present application, A and / or B both represent three situations of A, B, and A and B.

[0031] The above-mentioned imprint template is a step-by-step imprint template with adjustable curvature, high precision, high uniformity, high flatness and high fidelity, and can be reused many times.

[0032] Based on the same inventive concept, the embodiment of the present 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 has 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 an air storage cavity K, wherein the air inlet 221 is connected to the air storage cavity K. The beneficial effects of the method can refer to the description of the relevant effects of the nanoimprint template provided in the previous embodiment.

[0033] In a specific embodiment, the gas storage portion 20 includes an elastic buffer layer 21, the buffer layer 21 has a hollow structure 211, and one end of the hollow structure 211 forms a first opening P1; wherein the component of the buffer layer 21 includes aliphatic polyurethane acrylate; the embossing layer 10 is covered and fixedly connected to the first opening P1, specifically including: referring to Figure 3d and Figure 3e , the surface of the buffer layer 21 having the first opening P1 is placed on the silicon wafer 31 spin-coated with perfluoroacrylate, so that the perfluoroacrylate is adsorbed in the cross-linked network of the buffer layer 21, and the two are combined by diffusion and absorption. Specifically, it can be placed for about 10 minutes; refer to Figure 3f and Figure 3g The perfluoroacrylate adsorbed on the buffer layer 21 is placed on a template with a preset pattern (called a master template 41), and the perfluoroacrylate is cured to form an imprinting layer 10 with an imprinting pattern 11, wherein the imprinting layer 10, the buffer layer 21 and the support layer 22 surround a gas storage cavity K.

[0034] In a specific embodiment, before the embossing layer 10 is covered and fixedly connected to the first opening P1, the following steps are further included: Figure 3a , the buffer layer 21 is formed by 3D printing on the fixed silicon wafer 31, which is convenient for flexible customization according to the specific shape of the buffer layer 21, and the processing technology is simple. Among them, 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 liquid for 3D printing the buffer layer 21 can be prepared as follows: dissolve 184 initiator in hydroxyethyl acrylate, then add 40% aliphatic polyurethane acrylate and stir evenly, and vacuum degassing treatment; and design and print the pattern contour of the 3D printing stepper imprinting workbench.

[0035] In a specific embodiment, a second opening P2 is formed at one end of the hollow structure 211 away from the first opening P1. Before the step of covering and fixing the embossed layer 10 to the first opening P1, the method further includes: Figure 3b , attach the rigid support layer 22 to the surface of the buffer layer 21 having the second opening P2; apply glue to the joint of the support layer 22 and the buffer layer 21, and cure; refer to Figure 3c , remove the laminated support layer 22 and the buffer layer 21 from the silicon wafer 31 together; so that the support layer 22 and the buffer layer 21 are first bonded together to form the gas storage portion 20.

[0036] In a specific embodiment, before the rigid support layer 22 is attached to the surface of the buffer layer 21 having the second opening P2, the method further includes: pre-cleaning the support layer 22 with alcohol or acetone, and then treating the support layer 22 with oxygen plasma to fully remove impurities on the surface of the support layer 22 to facilitate bonding with the buffer layer 21, and the oxygen plasma treatment time may be about 15 minutes; using laser cutting to open holes in the support layer 22, and forming the aforementioned air inlet 221 at a position corresponding to the hollow structure 211 to facilitate air intake into the air storage cavity K. Then align the support layer 22 with the air inlet 221 with the semi-hollow buffer layer 21 coated with glue, and UV cure them to facilitate stable bonding between the two.

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

Claims

1. A nanoimprint template, characterized in that: include: An air storage portion and an embossing layer, wherein the embossing layer has an embossing pattern; the air storage portion has a first opening facing the embossing layer, and the embossing layer covers the first opening to enclose an air storage cavity with the air storage portion; The air storage portion has an air inlet communicated with the air storage cavity.

2. The nanoimprint template according to claim 1, characterized in that: The gas storage portion includes a rigid support layer and an elastic buffer layer, wherein the buffer layer is located between the support layer and the embossing layer; The buffer layer has a hollow structure, one end of the hollow structure forms the first opening, and the other end forms the second opening, the support layer covers the second opening, and the embossing layer, the buffer layer and the support layer surround the air storage cavity; The air inlet is formed at a position where the supporting layer is opposite to the hollow structure.

3. The nanoimprint template according to claim 2, 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%.

4. The nanoimprint template according to claim 2, 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.

5. The nanoimprint template according to claim 2, characterized in that: The contact angle of the embossing layer is greater than or equal to 120°.

6. The nanoimprint template according to claim 2, characterized in that: The support layer includes an acrylic plate, silica glass or quartz glass; and / or, The buffer layer comprises aliphatic polyurethane acrylate; and / or, The composition of the embossing layer includes perfluoroacrylate.

7. A method for preparing a nanoimprint template, characterized in that: The nanoimprint template comprises an air storage portion and an imprint layer, wherein the imprint layer has an imprint pattern; the air storage portion has an air inlet and a first opening; The method comprises: The embossing layer covers and is fixedly connected to the first opening, so that the embossing layer and the air storage portion form an air storage cavity, wherein the air inlet is communicated with the air storage cavity.

8. The method for preparing a nanoimprint template according to claim 7, characterized in that: The gas storage portion includes an elastic buffer layer, the buffer layer has a hollow structure, one end of the hollow structure forms the first opening, wherein the buffer layer includes aliphatic polyurethane acrylate; The step of covering and fixing the embossing layer to the first opening specifically includes: Placing the surface of the buffer layer having the first opening on a silicon wafer spin-coated with perfluoroacrylate, so that the perfluoroacrylate is adsorbed in the cross-linked 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 embossing layer with the embossing pattern.

9. The method for preparing a nanoimprint template according to claim 8, characterized in that: The hollow structure has a second opening formed at one end away from the first opening, and before the embossing layer is covered and fixedly connected to the first opening, the method further includes: attaching a support layer to the surface of the buffer layer having the second opening; Applying glue at the joint of the support layer and the buffer layer, and curing the glue; The bonded support layer and the buffer layer are removed from the silicon wafer together.

10. The method for preparing a nanoimprint template according to claim 9, 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 cleaned with alcohol or acetone in advance, and then treated with oxygen plasma. The support layer is cut with a laser to open holes, so as to form the air inlet at a position corresponding to the hollow structure.

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