Nanoimprint template and method for manufacturing the same

Abstract

This invention relates to a nanoimprint template and its preparation method. The preparation method of the nanoimprint template includes: providing a first substrate; the first substrate is an inorganic non-metallic substrate with a thickness on the order of millimeters; etching the first substrate to form a nanoimprint master with an original imprint pattern; the area containing the original imprint pattern is the imprint pattern area; forming a patterned first photoresist layer on the nanoimprint master, the patterned first photoresist layer at least exposing the imprint pattern area; coating the nanoimprint master with nanoimprint adhesive to completely fill the grooves located within the imprint pattern area; bonding a second substrate to the surface of the nanoimprint adhesive away from the nanoimprint master; curing the nanoimprint adhesive; and separating the second substrate from the nanoimprint master to obtain a nanoimprint template with a reversed pattern. This ensures the pattern accuracy of the transferred nanoimprint template and improves the repeatable imprinting life of the nanoimprint template.

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] In existing technologies, nanoimprint stencils are mainly produced by transferring patterns formed by the curing of nanoimprint adhesive onto a nanoimprint stencil. The nanoimprint stencil uses a silicon etching master as the original and is made by transferring patterns using nanoimprint adhesive. It is used to replace the easily cracked and costly silicon etching master, enabling the mass production of nanoimprint stencils. Thus, even if the nanoimprint stencil is damaged, it can be remade using the silicon etching master, reducing economic losses.

[0003] However, the nanoimprinting adhesive on the nanoimprinting plate is prone to wear, deformation or surface property degradation during multiple transfers, resulting in low pattern accuracy of the nanoimprinting template prepared from the nanoimprinting plate, which in turn significantly limits the number of times the nanoimprinting template can be repeatedly imprinted (usually less than 100 times). Summary of the Invention

[0004] Therefore, it is necessary to provide a nanoimprint template and its preparation method to address the problems of low pattern accuracy and significantly limited number of repetitive imprinting times in existing nanoimprint templates.

[0005] A method for preparing a nanoimprint template includes: providing a first substrate; the first substrate is an inorganic non-metallic substrate with a thickness on the order of millimeters; etching the first substrate to form a nanoimprint master with an original imprint pattern; the area where the original imprint pattern is located is an imprint pattern area; forming a patterned first photoresist layer on the nanoimprint master, the patterned first photoresist layer exposing at least the imprint pattern area; coating the nanoimprint master with nanoimprint adhesive, the nanoimprint adhesive completely filling the grooves located in the imprint pattern area; bonding a second substrate to the surface of the nanoimprint adhesive away from the nanoimprint master; curing the nanoimprint adhesive to solidify and shape it to form an integrated composite structure with the second substrate; separating the second substrate from the nanoimprint master, the second substrate and the cured nanoimprint adhesive together constituting the nanoimprint template with a reverse pattern.

[0006] In one embodiment, the first substrate is a quartz glass substrate, a borosilicate glass substrate, or a sapphire substrate.

[0007] In one embodiment, the first substrate is a quartz glass substrate; the thickness of the first substrate is 6mm-8mm.

[0008] In one embodiment, etching the first substrate includes: forming a patterned second photoresist layer on the first substrate; exposing a portion of the surface of the first substrate by the patterned second photoresist layer; forming a metal hard mask on the exposed surface of the first substrate; and etching the first substrate using the metal hard mask as an etching mask to form a plurality of grooves in the first substrate, the plurality of grooves constituting the original imprint pattern.

[0009] In one embodiment, the etching is a dry etching process; the etching gas used is a fluorocarbon-based gas, and the ratio of the number of fluorine atoms to the number of carbon atoms in the fluorocarbon-based gas is less than 4.

[0010] In one embodiment, the dry etching is inductively coupled plasma etching; the fluorocarbon-based gas is trifluoromethane or octafluorocyclobutane.

[0011] In one embodiment, the aspect ratio of the groove located within the embossed pattern area is less than or equal to 5.

[0012] In one embodiment, the patterned first photoresist layer exposes the imprinted pattern area and the non-patterned area surrounding the imprinted pattern area; the thickness of the patterned first photoresist layer is 50 μm-100 μm.

[0013] In one embodiment, before coating the nanoimprinting adhesive onto the nanoimprinting master, the method for preparing the nanoimprinting template further includes: performing an anti-adhesion treatment on the surface of the nanoimprinting master exposed by the patterned first photoresist layer.

[0014] A nanoimprint template is prepared using the nanoimprint template preparation method described in any of the above embodiments.

[0015] The method for preparing a nanoimprint template provided in this application uses an inorganic non-metallic substrate with a thickness of millimeters as the first substrate. The first substrate is etched to prepare a nanoimprint master with the original imprint pattern. Then, using the nanoimprint master as the original, a pattern transfer is performed using nanoimprint adhesive to obtain a nanoimprint template with a reversed imprint pattern. On the one hand, the inorganic non-metallic substrate has high hardness and wear resistance, which can ensure the pattern accuracy of the transferred nanoimprint template, thereby improving the repeatable imprint life of the nanoimprint template. On the other hand, the millimeter-thick first substrate can withstand the force generated when the second substrate and the nanoimprint master separate, effectively reducing the risk of cracking of the nanoimprint master. In addition, this method can also reduce the dependence on nanoimprint adhesive and save on expensive imprinting material costs. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 A schematic flowchart illustrating the preparation method of the nanoimprint template provided in the embodiments of this application;

[0018] Figures 2 to 9 A schematic cross-sectional view of the nanoimprint template provided in the embodiments of this application during the preparation process;

[0019] Figure 10 for Figure 9 The image shows a bottom view of the nanoimprint template. Detailed Implementation

[0020] To facilitate understanding of the present invention, it will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. Rather, these embodiments or examples are provided to make the disclosure of the present invention more thorough and complete.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments or examples only and is not intended to limit the invention. The optional scope of the term "and / or" as used herein includes any one of two or more of the related listed items, as well as any and all combinations of the related listed items, including any two related listed items, any more related listed items, or a combination of all related listed items.

[0022] In this invention, numerical ranges are involved. Unless otherwise specified, the numerical ranges are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe features or characteristics, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are included.

[0023] UV nanoimprint lithography (UV-NIL) is a micro-nano pattern transfer technology based on the principle of physical contact replication. This technology involves bonding a pre-prepared nanoimprint template with nanostructures (imprinted structures) to a nanoimprint adhesive (UV-curable functional layer) coated on a substrate surface. Under applied pressure, the nanoimprint adhesive fully fills the nanostructure cavities of the nanoimprint template. Subsequently, under UV light irradiation, the nanoimprint adhesive undergoes a photo-initiated polymerization reaction and solidifies. Finally, a demolding process is performed, transferring the nanostructures from the nanoimprint template to the substrate surface in a replication manner, thereby achieving high-precision, large-area batch fabrication of nanoscale patterns.

[0024] Nanoimprint lithography (NIL) technologies, such as UV-NIL, possess high resolution, high repeatability, and high-throughput replication capabilities, making them promising for applications in micro / nano optical devices, information display devices, optoelectronic devices, and functional material fabrication. In particular, it demonstrates significant advantages over traditional photolithography processes in the large-area, low-cost fabrication of complex nano-optical structures.

[0025] For example, in the field of augmented reality (AR) devices, nanoimprint lithography can be used to fabricate key optical components such as waveguide sheets in AR glasses. These components typically contain fine nanograting structures to achieve light coupling, transmission, and coupling-out functions, requiring high precision in structural dimensions and periodic consistency. Similarly, in the field of metasurface materials, by constructing subwavelength-scale nanoantenna array structures on planar substrates, the amplitude, phase, and polarization state of incident light can be precisely controlled, thereby forming novel planar optical devices such as ultrathin lenses and filters. Furthermore, in the manufacturing process of subwavelength optical components, it is necessary to construct micro / nano structures with periods smaller than the incident light wavelength to obtain specific diffraction, coupling, or modulation characteristics, placing even higher demands on the size control and replication precision of nanostructures.

[0026] It is evident that the nanoimprint template, as the core carrier for pattern replication, directly affects the quality and dimensional accuracy of the final imprinted pattern due to its structural precision, surface condition, and mechanical properties, making it a crucial element in the nanoimprinting process.

[0027] However, nanoimprint stencils prepared using nanoimprinting plates with nanoimprinting adhesive not only suffer from low pattern accuracy and significantly limited repeatability, but also experience stress concentration and increased demolding difficulty as the nanostructure size decreases or its complexity increases, making the nanoimprinting plates highly susceptible to cracking. Therefore, existing nanoimprinting plates face significant technical bottlenecks in terms of the lifespan of the nanoimprinting adhesive, pattern integrity retention, and the stability of high aspect ratio structures, making it difficult to meet the precision and consistency requirements of high-end optical devices.

[0028] Based on this, embodiments of this application provide a method for preparing a nanoimprint template. Figure 1 A schematic flowchart illustrating the preparation method of the nanoimprint template provided in this application embodiment; as shown in the figure, the preparation method of the nanoimprint template includes:

[0029] Step S101: Provide a first substrate; the first substrate is an inorganic non-metallic substrate with a thickness on the order of millimeters;

[0030] Step S102: Etch the first substrate to form a nanoimprint master with the original imprint pattern; the area where the original imprint pattern is located is the imprint pattern area;

[0031] Step S103: A patterned first photoresist layer is formed on the nanoimprint master, wherein the patterned first photoresist layer exposes at least the imprinted pattern area.

[0032] Step S104: Apply nanoimprinting adhesive to the nanoimprinting master, and the nanoimprinting adhesive completely fills the grooves located in the imprinting pattern area.

[0033] Step S105: Adhere the second substrate to the surface of the nanoimprinting adhesive away from the nanoimprinting master.

[0034] Step S106: The nanoimprint adhesive is cured to solidify and shape it, forming an integrated composite structure with the second substrate.

[0035] Step S107: Separate the second substrate from the nanoimprint master. The second substrate and the cured nanoimprint adhesive together form a nanoimprint template with a reverse pattern.

[0036] Understandably, the method for preparing the nanoimprint template provided in this application uses a millimeter-thick inorganic non-metallic substrate as the first substrate. The first substrate is etched to prepare a nanoimprint master with the original imprint pattern. Then, using the nanoimprint master as the original, a pattern transfer is performed using nanoimprint adhesive to obtain a nanoimprint template with a reversed imprint pattern. On one hand, the inorganic non-metallic substrate has high hardness and wear resistance, which can ensure the pattern accuracy of the transferred nanoimprint template, thereby improving the repeatable imprint life of the nanoimprint template. On the other hand, the millimeter-thick first substrate can withstand the forces generated when the second substrate and the nanoimprint master separate, effectively reducing the risk of the nanoimprint master cracking. Furthermore, this method can reduce dependence on nanoimprint adhesive, saving on expensive imprinting material costs.

[0037] It should also be understood that although the steps in the above flowchart are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Moreover, at least some of the steps in the above flowchart may include multiple steps or stages, and these steps or stages are not necessarily completed at the same time, nor are they necessarily performed sequentially.

[0038] Figures 2 to 9 A schematic cross-sectional view of the nanoimprint template provided in the embodiments of this application during the preparation process; Figure 10 for Figure 9 The image shows a bottom view of the nanoimprint template. Below, in conjunction with... Figures 2 to 10 The preparation method of the nanoimprint template provided in the embodiments of this application and its beneficial effects are further described in detail.

[0039] First, please refer to Figure 2 Step S101 is executed to provide a first substrate 100; the first substrate 100 is an inorganic non-metallic substrate with a thickness on the order of millimeters.

[0040] In some embodiments, the first substrate 100 may be a hard substrate such as a quartz glass substrate, a borosilicate glass substrate, or a sapphire substrate.

[0041] It should be noted that the aforementioned substrates also possess excellent light transmittance, meeting the exposure requirements of the nanoimprinting process. Specifically, the material of the first substrate 100 may also include glass materials such as aluminosilicate glass and borosilicate glass, as well as high-hardness single-crystal materials such as diamond.

[0042] In this application, taking a first substrate 100 as a quartz glass substrate with a thickness of 6mm-8mm as an example, the preparation method of the nanoimprint template is described in detail.

[0043] Understandably, this application chooses a quartz glass substrate as the first substrate 100 because it combines suitable hardness and structural rigidity, excellent etching performance, and moderate manufacturing cost, while also possessing good light transmittance and dimensional stability. Compared to materials such as sapphire and diamond, it is easier to achieve high-precision micro / nano structure processing, and compared to ordinary glass materials, it can ensure higher structural strength and stability. Furthermore, the thickness of the first substrate 100 is set to 6mm-8mm, such as 6mm, 6.5mm, 7mm, 7.5mm, and 8mm. This avoids the problem of insufficient rigidity due to an excessively thin first substrate 100, which increases the probability of cracking and deformation during imprinting or transport, while also avoiding the problems of an excessively thick first substrate 100, which results in a bulky overall structure, decreased alignment accuracy during imprinting, and excessively long exposure optical path affecting exposure uniformity.

[0044] Then, please refer to Figures 2 to 5 Step S102 is executed to etch the first substrate 100 to form a nanoimprint master 120 with the original imprint pattern; the area where the original imprint pattern is located is the imprint pattern area A1.

[0045] In some embodiments, please refer to Figures 2 to 5 The etching of the first substrate 100 may include the following steps: forming a patterned second photoresist layer 101 on the first substrate 100; exposing a portion of the surface of the first substrate 100 with the patterned second photoresist layer 101; forming a metal hard mask 103 on the exposed surface of the first substrate 100; and etching the first substrate 100 using the metal hard mask 103 as an etching mask to form a plurality of grooves 110 in the first substrate 100, wherein the plurality of grooves 110 constitute the original imprint pattern (nanoimprint pattern).

[0046] In some embodiments, please refer to Figure 2 The specific steps for forming a patterned second photoresist layer 101 on the first substrate 100 may include: uniformly coating the second photoresist layer on the first substrate 100; and performing patterning processing on the second photoresist layer through photolithography processes such as exposure and development to transfer a pre-designed nanopattern (the pattern of a nanoimprint master) onto the second photoresist layer, thereby forming the patterned second photoresist layer 101. The area covered by the patterned second photoresist layer 101 is the preset area to be etched, and the surface area of ​​the first substrate 100 exposed by the patterned second photoresist layer 101 is the non-etched area. Subsequently, by forming a metal hard mask 103 in the non-etched area and peeling off the patterned second photoresist layer 101 covering the preset area to be etched, precise etching of the preset area to be etched on the first substrate 100 can be achieved.

[0047] It should be noted that the aforementioned photolithography processes refer to patterning processes based on photoresist and exposure technology, including electron beam lithography, laser direct writing lithography, and (deep) ultraviolet lithography. The specific photolithography process used can be selected according to the feature linewidth of the nanoimprint template. Among them, electron beam lithography is usually used to achieve smaller feature linewidths, while laser direct writing and (deep) ultraviolet lithography are suitable for larger feature linewidths.

[0048] In some embodiments, please refer to Figure 3 and Figure 4 The specific steps for forming a metal hard mask 103 on the exposed surface of the first substrate 100 include: depositing a metal layer 102 on the patterned second photoresist layer 101 and the exposed surface of the first substrate 100. The material of the metal layer 102 can be a metal or metal alloy with a high etching selectivity compared to quartz glass, such as chromium (Cr), nickel (Ni), aluminum (Al) and their alloys; removing the patterned second photoresist layer 101 using an acetone solution. During this process, the metal layer 102 attached to the patterned second photoresist layer 101 will be peeled off along with the patterned second photoresist layer 101, thereby achieving synchronous removal of the patterned second photoresist layer 101 and the metal layer 102 above it; and forming the metal hard mask 103 with the remaining metal layer 102 covering the exposed surface of the first substrate 100. The metal hard mask 103 defines the pattern morphology of the nanoimprint master 120. In this way, the non-etched areas are basically not etched under the protection of the metal hard mask 103, and only the pre-etched areas are formed into the pre-defined micro-nano structures under the action of the subsequent etching process.

[0049] It should be noted that the etch selectivity of ordinary photoresist is extremely low when etching quartz glass substrates. Because etching quartz glass substrates requires high-energy ion bombardment, ordinary photoresist is consumed very quickly. Therefore, to obtain a smooth sidewall morphology and sufficient etching depth after etching, this application uses a metal hard mask 103 as the etching mask for the quartz glass substrate. Furthermore, the size range of the area to be etched can be set from 10mm×10mm to 70mm×70mm, and can be selected and adjusted according to the actual size of the pattern area.

[0050] In some embodiments, please refer to Figure 5 The specific steps for etching the first substrate 100 may include: using dry etching to etch a predetermined area of ​​the first substrate 100 to transfer a pre-designed nanopattern into the first substrate 100. The etching depth determines the depth to which the nanoimprint template 210 is pressed into the substrate during replication. Therefore, the first substrate 100 can be etched to a corresponding morphology and depth according to design requirements.

[0051] It should be noted that the imprinted pattern area A1 formed after etching the first substrate 100 is also called the "nanoimprint template area", while the area outside the imprinted pattern area A1 is the "non-nanoimprint template area".

[0052] In some embodiments, the etching gas used for etching is a fluorocarbon-based gas, and the ratio of the number of fluorine atoms to the number of carbon atoms in the fluorocarbon-based gas is less than 4; for example, the ratio of the number of fluorine atoms to the number of carbon atoms in the fluorocarbon-based gas can be 3, 2 or 1.

[0053] In the embodiments of this application, dry etching can be inductively coupled plasma etching; the fluorocarbon-based gas can be trifluoromethane (CHF3) or octafluorocyclobutane (C4F8).

[0054] It should be noted that the etching gas used in this application for etching the quartz glass substrate is significantly different from the conventional silicon wafer etching systems such as carbon tetrafluoride (CF4) and sulfur hexafluoride (SF6). SF6 has an extremely high etching rate for silicon, reaching several micrometers per minute, but its etching rate for materials such as quartz glass is extremely low, typically only a fraction of the etching rate for silicon. Furthermore, the sidewall perpendicularity of the quartz glass substrate after etching is highly dependent on the fluoropolymer protective layer formed by the decomposition of gases such as CHF3 and C4F8 during the etching process. If a gas with excessively high fluorine content (such as CF4) is used, insufficient polymer formation can easily occur, making it difficult to effectively protect the sidewalls, thus resulting in undesirable morphologies such as tilted or undercut etching profiles.

[0055] Therefore, this application selects a suitable fluorocarbon gas for etching the quartz glass substrate, which can form a stable polymer sidewall protection while ensuring a reasonable etching rate, significantly improving the sidewall perpendicularity and morphological regularity of the micro-nano structure, and is conducive to obtaining a high-precision nanoimprint master 120.

[0056] It should also be noted that the material, etching process, and etching gas of the metal layer 102 described above are merely illustrative examples. In practical applications, the material, etching process, and etching gas of the metal layer 102 can be adaptively selected according to the specific material of the first substrate 100, and this application does not impose any specific limitations on them.

[0057] It is understandable that by using the above-mentioned preparation process, the non-etched area can be reliably protected by the metal hard mask 103, avoiding damage to the area during the etching process; at the same time, precise etching is performed only on the preset area to be etched, which helps to improve the pattern etching accuracy, suppress over-etching and lateral etching, and ensure the sidewall verticality and morphological regularity of the micro-nano structure. Finally, a nanostructure consistent with the design pattern (master pattern) is formed on the surface of the first substrate 100, and the required nanoimprint master 120 is obtained.

[0058] In some embodiments, please refer to Figure 5 After etching the first substrate 100, the metal hard mask 103 remaining on the surface of the first substrate 100 can be stripped and removed using a corresponding metal removal liquid, thereby obtaining a nanoimprint master 120 with a complete pattern and a clean surface.

[0059] In some embodiments, the aspect ratio of the groove 110 located in the embossed pattern area A1 is less than or equal to 5; for example, the aspect ratio of the groove 110 located in the embossed pattern area A1 can be 5, 4, 3, 2, 1, etc.

[0060] Understandably, by limiting the aspect ratio (the maximum ratio of etching depth to linewidth) of the groove 110 to no more than 5, the pattern accuracy of the subsequently prepared nanoimprint template can be guaranteed to the greatest extent. This is because a high aspect ratio can easily cause deformation of the nanoimprint adhesive after demolding for small-sized structures, affecting the pattern accuracy of the nanoimprint template.

[0061] Next, please refer to Figure 6 In step S103, a patterned first photoresist layer 121 is formed on the nanoimprint master 120, wherein the patterned first photoresist layer 121 exposes at least the imprinted pattern area A1.

[0062] In some embodiments, the specific steps for forming the patterned first photoresist layer 121 may include: cleaning the nanoimprint master 120 to ensure the cleanliness of the surface of the nanoimprint master 120; uniformly coating the first photoresist layer on the surface of the nanoimprint master 120; and patterning the first photoresist layer through photolithography processes such as exposure and development to form the patterned first photoresist layer 121. The patterned first photoresist layer 121 covers the area outside the imprinted pattern area A1, precisely defining the "stamp" area range of the nanoimprint master 120; or, in other words, the patterned first photoresist layer 121 exposes the imprinted pattern area A1.

[0063] In some specific embodiments, the patterned first photoresist layer 121 exposes the imprinted pattern area A1 and the non-patterned area A2 surrounding the imprinted pattern area A1; the thickness H of the patterned first photoresist layer 121 is 50μm-100μm. Optionally, the thickness H of the patterned first photoresist layer 121 can be 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, etc.

[0064] It is understandable that setting the thickness H of the patterned first photoresist layer 121 to 50μm-100μm facilitates the formation of protrusions 1221 on the reverse imprint pattern formed when the nanoimprint master 120 is subsequently coated with nanoimprint adhesive 122 (please refer to...). Figure 7To achieve a stable bond between the nanoimprint adhesive 122 and the second substrate 200 (please refer to...) Figure 8 By setting the above parameters, on the one hand, it can be avoided that the boss 1221 is too thick, resulting in an excessively large contact area with the nanoimprint master 120, which could lead to problems such as adhesion, deformation, and pattern damage during subsequent demolding; on the other hand, it can be avoided that the boss 1221 is too thin, resulting in insufficient structural strength and difficulty in forming a stable bond with the second substrate 200.

[0065] It should be noted that, Figures 7 to 10 The nanoimprint adhesive 122 shown specifically refers to the imprint adhesive layer formed on the nanoimprint master 120 for preparing the nanoimprint template of this application; in the specific embodiments of this application, the nanoimprint adhesives not marked with this reference numeral generally refer to those that are not the same structure.

[0066] It is also understood that the patterned first photoresist layer 121 simultaneously exposes the imprinted pattern area A1 and the non-patterned area A2 surrounding the imprinted pattern area A1, so that the subsequently formed boss 1221 includes the main body b covering the reverse imprinted pattern and the extension a extending outward. The extension a and the reverse imprinted pattern together form a stepped support structure, which can effectively buffer stress and prevent the columnar structure at the edge of the reverse imprinted pattern from breaking.

[0067] In some specific embodiments, please refer to Figure 6 The ring width W of the non-patterned region A2 is greater than or equal to the thickness H of the patterned first photoresist layer 121; optionally, the ratio of the ring width W of the non-patterned region A2 to the thickness H of the patterned first photoresist layer 121 can be 1-1.2. In this way, edge stress can be fully dispersed, preventing the columnar structure at the edge of the reverse imprinted pattern from breaking, while avoiding excessive occupation of the effective pattern area, thus balancing structural strength and plate utilization.

[0068] Next, please refer to Figure 7 In step S104, nanoimprinting adhesive 122 is coated on nanoimprinting master 120, and nanoimprinting adhesive 122 completely fills the groove 110 located in the imprinting pattern area A1.

[0069] In some embodiments, when the patterned first photoresist layer 121 simultaneously exposes the imprinted pattern area A1 and the non-patterned area A2 surrounding the imprinted pattern area A1, nanoimprint adhesive 122 can be coated in the exposed area. Specifically, nanoimprint adhesive 122 (template nanoimprint adhesive) is cast into the nanoimprinted pattern area A1 and the non-patterned area A2 surrounding the imprinted pattern area A1. This casting area can also be called a "window area".

[0070] In some specific embodiments, the nanoimprint adhesive 122 completely fills a portion of the groove 110 within the imprinted pattern area A1 on the nanoimprint master 120, forming a reverse imprinted pattern. The nanoimprint adhesive 122 completely fills a portion of the semi-enclosed area formed by the patterned first photoresist layer and the nanoimprint master 120, forming a boss 1221 located on the reverse imprinted pattern. Furthermore, the nanoimprint adhesive 122 extends to cover the top of the partially patterned first photoresist layer 121, forming a connecting portion c. The top surface of this connecting portion c is higher than the top surface of the patterned first photoresist layer 121.

[0071] In some embodiments, before coating the nanoimprinting adhesive 122 onto the nanoimprinting master 120, the preparation method of the nanoimprinting template 210 further includes: performing an anti-adhesion treatment on the surface of the nanoimprinting master 120 exposed by the patterned first photoresist layer 121. The anti-adhesion treatment can be achieved by spin-coating or evaporating a fluorinated anti-adhesion agent to increase the hydrophobicity of the surface of the nanoimprinting master 120. This helps to reduce the adhesion between the nanoimprinting adhesive 122 and the surface of the nanoimprinting master 120, facilitating smooth demolding after the nanoimprinting adhesive 122 has cured, while reducing problems such as pattern damage, adhesive residue, and structural deformation, thereby improving the molding yield and structural integrity of the finally prepared nanoimprinting template.

[0072] Next, please refer to Figure 8 Step S105 is performed to bond the second substrate 200 to the surface of the nanoimprint adhesive 122 away from the nanoimprint master 120.

[0073] In some embodiments, the second substrate 200 may be a hard substrate such as a quartz glass substrate, a borosilicate glass substrate, or a sapphire substrate. The material of the second substrate 200 may be the same as or different from the material of the first substrate 100.

[0074] In this application, both the second substrate 200 and the first substrate 100 are made of quartz glass. This simplifies material selection and standardizes processing techniques, thereby effectively reducing production costs. Furthermore, both the first substrate 100 and the second substrate 200 are made of translucent materials, allowing the curing light of the nanoimprint adhesive 122 to enter from either substrate side, achieving bidirectional curing. This enhances the flexibility and adaptability of the curing process, ensures more thorough and uniform curing, and avoids problems such as incomplete curing and uneven internal stress caused by limited light transmission from one side. It also simplifies the curing light path design, further reducing production costs.

[0075] In some embodiments, before bonding the second substrate 200 to the surface of the nanoimprint adhesive 122 away from the nanoimprint master 120, an adhesion promoter can be spin-coated onto the side of the second substrate 200 that is to be bonded to the nanoimprint adhesive 122 to enhance the interfacial bonding force between the second substrate 200 and the nanoimprint adhesive 122 and improve the reliability and stability of the overall structure.

[0076] Next, please continue to refer to Figure 8 Step S106 is executed to cure the nanoimprint adhesive 122 so that the nanoimprint adhesive 122 is cured and shaped to form an integrated composite structure with the second substrate 200.

[0077] In some embodiments, when curing the nanoimprint adhesive 122, ultraviolet (UV) curing can be used to cure the nanoimprint adhesive 122 and form an imprint "stamp". During the curing process, a certain pressure can be applied to the nanoimprint adhesive 122 in the direction from the second substrate 200 to the first substrate 100, so that the nanoimprint adhesive 122 adheres tightly to each interface, further ensuring full pattern filling and tight interface bonding, while improving the uniformity and dimensional accuracy of the cured structure.

[0078] Finally, please refer to Figure 9 and Figure 10 In step S107, the second substrate 200 is separated from the nanoimprint master 120. The second substrate 200 and the cured nanoimprint adhesive 122 together form a nanoimprint template 210 with a reverse pattern.

[0079] In some embodiments, when the second substrate 200 is separated from the nanoimprint master 120, the nanoimprint adhesive 122 that has been cured is transferred to the bottom of the second substrate 200 by an adhesive to form a nanoimprint template 210 (nanoimprint step-replication template).

[0080] In practical applications, when using the nanoimprint template 210 with a "stamp" to imprint patterns, a one-to-one replication method can be selected to imprint a single chip on a single substrate, or a step-by-step repetitive imprinting method can be used to batch prepare multiple chips with the same pattern on the same substrate, thereby improving production efficiency and material utilization.

[0081] In summary, this application directly constructs nanostructures on a high-hardness, wear-resistant inorganic non-metallic substrate (inorganic substrate), that is, a nanoimprint master is formed on the first substrate. The traditional process of "nanoimprint sub-plate to nanoimprint template" transfer is transformed into "nanoimprint master to nanoimprint template" transfer, which effectively improves the structural fidelity and service life of the nanoimprint template and ensures better graphic accuracy.

[0082] Compared to conventional methods that use nanoimprint stencils to transfer nanoimprint patterns, this application does not rely on nanoimprint stencils. Instead, it directly uses an inorganic non-metallic substrate as the structural carrier and directly forms a reverse imprint pattern (nanoimprint template pattern) on the first substrate through a two-step photolithography and etching process, which significantly improves the structural stability and replication accuracy of the nanoimprint template.

[0083] Based on this, the present application also provides a nanoimprint template, which is prepared using the nanoimprint template preparation method in any of the above embodiments.

[0084] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0085] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for preparing a nanoimprint template, characterized in that, The method for preparing the nanoimprint template includes: A first substrate is provided; the first substrate is an inorganic non-metallic substrate with a thickness on the order of millimeters; The first substrate is etched to form a nanoimprint master with the original imprint pattern; the area where the original imprint pattern is located is the imprint pattern area; A patterned first photoresist layer is formed on the nanoimprint master, wherein the patterned first photoresist layer at least exposes the imprinted pattern area; A nanoimprinting adhesive is coated on the nanoimprinting master, and the nanoimprinting adhesive completely fills the grooves located in the imprinting pattern area; A second substrate is bonded to the surface of the nanoimprint adhesive away from the nanoimprint master. The nanoimprint adhesive is cured to solidify and shape it, thereby forming an integrated composite structure with the second substrate. The second substrate is separated from the nanoimprint master, and the second substrate and the cured nanoimprint adhesive together constitute the nanoimprint template with a reverse pattern.

2. The method for preparing a nanoimprint template according to claim 1, characterized in that, The first substrate is a quartz glass substrate, a borosilicate glass substrate, or a sapphire substrate.

3. The method for preparing a nanoimprint template according to claim 1, characterized in that, The first substrate is a quartz glass substrate; the thickness of the first substrate is 6mm-8mm.

4. The method for preparing a nanoimprint template according to claim 1, characterized in that, Etching the first substrate includes: A patterned second photoresist layer is formed on the first substrate; the patterned second photoresist layer exposes a portion of the surface of the first substrate; A hard metal mask is formed on the exposed surface of the first substrate; Using the metal hard mask as an etching mask, the first substrate is etched to form a plurality of grooves in the first substrate, and the plurality of grooves constitute the original embossed pattern.

5. The method for preparing a nanoimprint template according to claim 1, characterized in that, The etching is a dry etching process; the etching gas used is a fluorocarbon-based gas, and the ratio of the number of fluorine atoms to the number of carbon atoms in the fluorocarbon-based gas is less than 4.

6. The method for preparing a nanoimprint template according to claim 5, characterized in that, The dry etching method is inductively coupled plasma etching; the fluorocarbon-based gas is trifluoromethane or octafluorocyclobutane.

7. The method for preparing a nanoimprint template according to claim 1, characterized in that, The aspect ratio of the groove located within the embossed pattern area is less than or equal to 5.

8. The method for preparing a nanoimprint template according to claim 1, characterized in that, The patterned first photoresist layer exposes the imprinted pattern area and the non-patterned area surrounding the imprinted pattern area; the thickness of the patterned first photoresist layer is 50μm-100μm.

9. The method for preparing a nanoimprint template according to claim 8, characterized in that, Before coating the nanoimprinting adhesive onto the nanoimprinting master, the method for preparing the nanoimprinting template further includes: The surface of the nanoimprint master exposed by the patterned first photoresist layer is subjected to an anti-sticking treatment.

10. A nanoimprint template, characterized in that, The nanoimprint template is prepared using the method described in any one of claims 1 to 9.

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