Preparation method of duplicated mold structure and nanoimprint structure

Abstract

The invention provides a preparation method of a nanoimprint structure. According to the preparation method, the duplicated mold structure provided by the invention is adopted; the method comprises the following steps: preparing a duplicated mold; coating the product glue on the surface of the product substrate to form the product glue layer; pressing the copying mold on the product glue layer, so that the product glue fills the nano structure of the mold glue layer and is cured to form a composite structure; the mold carrier is separated from the mold glue layer, and the composite structure is kept; based on the composite structure, selective etching is carried out, the mold glue layer is removed, and a target nano structure is formed on the surface of the product substrate. According to the method, the structure damage risk caused by the demolding process can be thoroughly avoided, and the integrity and consistency of the imprinting structure are improved. The duplicated mold structure provided by the invention has corresponding advantages.

Description

Technical Field

[0001] This invention belongs to the field of micro-nano manufacturing technology, specifically relating to a method for preparing a replica mold structure and a nanoimprint structure. Background Technology

[0002] Nanoimprint structure fabrication is a key technology in the field of micro-nano manufacturing. It uses physical imprinting to replace the photoresist exposure of traditional photolithography, which greatly reduces equipment and manufacturing costs, while achieving high-fidelity replication of submicron or even nanoscale structures.

[0003] Current nanoimprint structure fabrication processes involve two stages: mold preparation and product manufacturing. In existing processes, the demolding separation stage is prone to defects such as deformation and breakage due to the fragility of nanostructures, especially those with high aspect ratios and complex structures. Furthermore, the severity of defects varies depending on the imprint structure and aspect ratio. The industry is mitigating this through optimizing adhesive formulations, curing process parameters, and mold surface modification, but bottlenecks such as separation damage and short mold life remain. Even better existing technologies often increase process complexity and place higher demands on equipment and process control. Specifically, during demolding, interfacial separation between the replica mold and the product adhesive, or between the master mold and the mold adhesive, often leads to irreversible damage such as pull-out and deformation of the nanostructure. Conventional methods mitigate demolding problems by adjusting the surface energy properties of the imprint material, such as adding release agents or performing surface modification treatments. However, such methods not only require extensive experimental verification to determine the optimal formulation and process parameters, but also, in most cases, are only effective for one type of structure, making it difficult to adapt to nanostructures with different morphological characteristics. In particular, for complex nanostructures with high precision and high aspect ratio, the effectiveness of conventional demolding methods is extremely limited. Furthermore, modification methods that reduce the surface energy of materials are often accompanied by side effects such as decreased replication accuracy and reduced curing efficiency, putting process optimization in a dilemma of multi-objective trade-offs.

[0004] Due to the limitations of existing technology, the following main problems are faced: the mechanical stability of nanostructures is easily destroyed under the action of demolding force during demolding separation, especially for fragile structures such as high aspect ratio and cantilever, the probability of defects (such as collapse and fracture) is significantly increased, which in turn restricts the process yield and application expansion.

[0005] It is evident that existing technologies still have shortcomings, and there is an urgent need to develop a method for replicating mold structures and corresponding nanoimprinting structures that can completely avoid the structural damage risks caused by the demolding process and improve the integrity and consistency of the imprinted structure. This would promote the in-depth development of nanoimprinting structure fabrication technology in high-end applications such as semiconductors, memory chips, and micro-nano optics. Summary of the Invention

[0006] The present invention is intended to solve all or part of the problems of the prior art. On one hand, the present invention proposes a replica mold structure, which configures the adhesion force relationship of each interface, so as to realize the separation of the mold carrier and the mold adhesive layer, while the mold adhesive layer is still completely retained on the product adhesive layer.

[0007] In addition, this invention proposes a method for preparing nanoimprinted structures and a new nanoimprinting process. In the process of imprinting products, after applying adhesive, imprinting and bonding and curing, the demolding step is eliminated, thereby fundamentally avoiding the defects caused by the separation of mold adhesive and product adhesive.

[0008] One aspect of the present invention provides a replication mold structure, comprising: a mold carrier and a mold adhesive layer that are bonded together; the mold adhesive layer is used to press onto a product adhesive layer on the surface of a product to be prepared to obtain the target nanostructure of the product; the adhesive force between the surface of the mold adhesive layer away from the mold carrier and the contact surface of the product adhesive layer is configured as a first adhesive force; the contact surfaces of the mold adhesive layer and the mold carrier are bonded together by a second adhesive force; the first adhesive force is greater than the second adhesive force.

[0009] The mold adhesive layer is formed on the surface of the mold carrier away from the mold carrier and has a nanostructure based on the prefabricated master mold; the adhesive force between the contact surface of the mold adhesive layer and the master mold is configured as a third adhesive force; the second adhesive force is greater than the third adhesive force.

[0010] The mold carrier is a transparent film material, which includes an electrostatic adsorption film; the mold adhesive layer includes a UV-curable adhesive.

[0011] By precisely configuring the adhesive forces between the interfaces of the replica mold structure and controlling the relationship between different adhesive forces, controllable separation of the mold carrier and the mold adhesive layer is achieved. This simplifies the material system requirements, eliminates the need for complex low surface energy modification of the product adhesive, maintains product performance, and is compatible with existing UV embossing equipment, providing a preparation basis for realizing the process paradigm shift from destructive demolding to non-destructive transfer.

[0012] This invention provides a method for preparing a nanoimprint structure, employing a replication mold structure provided by this invention. The method includes: preparing a replication mold; coating a product adhesive onto the surface of a product substrate to form the product adhesive layer; pressing the replication mold onto the product adhesive layer, allowing the product adhesive to fill the nanostructure of the mold adhesive layer and cure it to form a composite structure; separating the mold carrier from the mold adhesive layer while maintaining the composite structure; and selectively etching based on the composite structure to remove the mold adhesive layer, thereby forming a target nanostructure on the surface of the product substrate.

[0013] Based on the constructed different adhesive force gradient systems, by pre-setting a triple interface energy level difference at the nanoscale, the structure transfer process is transformed from relying on the intrinsic demolding performance of the material into a designable and predictable interface engineering problem. This completely avoids the damage of demolding stress to fine nanostructures and achieves the unity of high-resolution structure replication and non-destructive transfer.

[0014] The mold carrier is an electrostatic adsorption film material; the method for separating the mold carrier from the mold adhesive layer includes: separating by controlling electrostatic force.

[0015] The method for preparing the replica mold includes: coating a pre-fabricated master mold with a UV-curable adhesive to form a mold adhesive layer; pressing the mold carrier and the mold adhesive layer together so that the UV-curable adhesive fully fills the nanostructure gaps of the master mold; curing and shaping the mold adhesive layer; forming a negative image structure of the nanostructure on the side surface of the mold adhesive layer facing the master mold; and separating the master mold from the mold adhesive layer to obtain the replica mold.

[0016] Before applying the UV-curable adhesive, the surface of the master mold is subjected to an anti-adhesion treatment; the anti-adhesion treatment includes: fluorination treatment, silane coupling agent treatment, or self-assembled monolayer treatment.

[0017] Before coating with UV-curable adhesive, the nanostructure is pre-deformed and compensated based on the thickness distribution model of the UV-curable adhesive in the nanostructure and the deformation characteristics of selective etching.

[0018] The selective etching method includes: based on the different etching rates of the UV-curable adhesive and the product adhesive, using plasma etching, wet etching or reactive ion etching to completely remove the mold adhesive layer.

[0019] The method for forming the product adhesive layer includes: applying the product to the surface of a product substrate by spin coating, spray coating or blade coating; the product substrate includes one of PET, glass, silicon wafer or metal substrate.

[0020] Compared with the prior art, the main beneficial effects of the present invention are: The present invention provides a replication mold structure in which the components form a hierarchical distribution of mechanical properties at the microscale, effectively avoiding stress concentration; the design of a reasonable interface bonding strength distribution helps to ensure the structural fidelity of nano-features in multiple imprinting cycles, and provides a basic solution to the problem of structural damage caused by interface failure during the use of traditional replication molds, significantly improving the reliability and reusability of nanoimprinting tools.

[0021] The present invention provides a method for preparing nanoimprint structures. By utilizing the triple adhesion gradient preset in the replication mold structure, the process route for transferring nanostructures is reconstructed. This method can reduce the sensitivity to demolding parameters (such as separation speed, angle, and ambient humidity), improve the yield of high aspect ratio structures, and only requires adding an etching process. This method is conducive to substantially improving the stability of mass production of complex nanostructures and achieves a balance between efficiency and quality optimization. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the conventional nanoimprint structure fabrication process.

[0023] Figure 2 This is a schematic diagram of the replication mold structure according to an embodiment of the present invention.

[0024] Figure 3 This is a schematic diagram of the nanoimprint structure preparation method according to an embodiment of the present invention.

[0025] Figure 4 This is a schematic diagram of the nanoimprint structure fabrication process steps according to an embodiment of the present invention. Detailed Implementation

[0026] The technical solutions in specific embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0027] like Figure 1 As shown, conventional processes typically involve two consecutive stages: mold fabrication and product manufacturing. Both stages follow the basic flow of adhesive application, imprinting and bonding, curing, and demolding. In mold fabrication, a master mold with a nanostructure is used as a base. Through steps such as applying mold adhesive, imprinting and filling, UV curing, and demolding, a replica mold is obtained and mounted on a mold carrier. In the product manufacturing stage, a product substrate (such as PET) is used as a carrier. Product adhesive is applied, and the aforementioned replica mold is used for imprinting. After UV curing, demolding occurs, ultimately forming the desired nanostructure on the product surface. During the separation process in conventional fabrication methods, excessive interfacial adhesion forces during the demolding of the replica mold from the master mold and the product adhesive from the replica mold can easily lead to breakage, collapse, deformation, or residue of the nanostructure. This can easily cause deformation and breakage of the nanoimprinted structure. Different structures and aspect ratios result in varying degrees of structural defects after imprinting. The demolding process remains crucial for the integrity of the nanostructure and product yield. In short, conventional nanoimprinting demolding methods have at least two main problems: First, the separation process can easily lead to risks such as breakage and deformation of the nanoimprinted structure. Second, in order to reduce the defects introduced by demolding, it is often necessary to adjust the demolding properties of the imprinting material (reduce surface energy), which requires a lot of verification and cannot be completely avoided.

[0028] This invention, through the following embodiments, exemplifies a method for fabricating nanoimprint structures, providing a specific solution to the structural damage problem during demolding. It aims to address the nanostructure damage caused by demolding operations in existing nanoimprint processes, offering a novel nanoimprint method that eliminates the need for traditional demolding steps and removes the temporary mold layer through etching to obtain the final pattern. This not only improves the quality and consistency of nanoimprinted products but also broadens the application scope of this technology in the manufacturing of high-precision, high aspect ratio structures. It has significant advantages, particularly in applications with stringent requirements for structural integrity, such as optical components, biomedical detection chips, and semiconductor lithography templates, thus driving the development of micro / nano manufacturing technology towards higher precision and efficiency.

[0029] refer to Figure 2 As shown, the replication mold structure exemplified in this embodiment of the invention includes: a mold carrier and a mold adhesive layer that are bonded together; the mold adhesive layer is used to press onto a product adhesive layer on the surface of the product to be prepared nanostructure to obtain the target nanostructure of the product. The adhesive force between the surface A of the mold adhesive layer away from the mold carrier and the contact surface of the product adhesive layer is configured as a first adhesive force; the contact surface B of the mold adhesive layer and the mold carrier that are bonded together is bonded by a second adhesive force; the first adhesive force is greater than the second adhesive force.

[0030] Figure 2 In the example case, the mold adhesive layer is formed on the surface of the mold carrier based on a prefabricated master mold with a nanostructure; the adhesive force between the contact surface of the mold adhesive layer and the master mold is configured as a third adhesive force; the second adhesive force is greater than the third adhesive force.

[0031] The mold carrier in the example is a transparent film material, which includes an electrostatic adsorption film; the mold adhesive layer includes a UV-curable adhesive.

[0032] In some embodiments, the mold carrier is a flexible transparent film material, which includes one of the following: polyimide film, polyester film, or polydimethylsiloxane film.

[0033] In some embodiments, the mold adhesive layer comprises a fluoropolymer or polymethyl methacrylate; the product adhesive layer comprises an organic resin that can be rapidly etched by oxygen plasma.

[0034] refer to Figure 3As shown in the example, this embodiment of the invention illustrates a method for preparing a nanoimprint structure, employing the replication mold structure provided in this embodiment. The example method includes: preparing a replication mold; coating a product adhesive onto the surface of a product substrate to form a product adhesive layer; pressing the replication mold onto the product adhesive layer, allowing the product adhesive to fill the nanostructure of the mold adhesive layer and cure to form a composite structure; separating the mold carrier from the mold adhesive layer while maintaining the composite structure; and based on the composite structure, selectively etching to remove the mold adhesive layer, thereby forming a target nanostructure on the surface of the product substrate.

[0035] In the example, instead of focusing on optimizing the demolding process (such as surface modification and the application of release agents), the demolding step was completely abandoned. Instead, etching technology, a traditional process that competes with imprinting, was introduced as a complementary means. By setting the adhesion force and configuring the interaction energy level difference between different interfaces at the nanoscale, a non-destructive transfer scheme for carrier peeling and etching removal of resist was achieved.

[0036] In some embodiments, the method for preparing the replica mold includes: coating a pre-formed nanostructured master mold surface with UV-curable adhesive to form a mold adhesive layer; pressing the mold carrier and the mold adhesive layer together so that the UV-curable adhesive fully fills the nanostructure gaps of the master mold; curing and shaping the mold adhesive layer; forming a negative image structure of the nanostructure on the side surface of the mold adhesive layer facing the master mold; and separating the master mold from the mold adhesive layer to obtain the replica mold.

[0037] In some embodiments, the surface of the master mold is subjected to an anti-adhesion treatment before the UV-curable adhesive is applied; the anti-adhesion treatment includes: fluorination treatment, silane coupling agent treatment, or self-assembled monolayer treatment.

[0038] In some embodiments, prior to coating the UV-curable adhesive, pre-deformation compensation is performed on the nanostructure based on the thickness distribution model of the UV-curable adhesive in the nanostructure and the deformation characteristics of selective etching.

[0039] In some specific embodiments, the selective etching method includes: based on the different etching rates of the UV-curable adhesive and the product adhesive, using plasma etching, wet etching, or reactive ion etching to completely remove the mold adhesive layer. In the example case, reactive ion etching with an O2 / CF4 mixed gas (ratio 8:2) is used, and the etching selectivity ratio of the mold adhesive (containing UV-curable adhesive) to the product adhesive (pure organic UV adhesive) needs to be ≥5:1, but the specific situation is not limited here.

[0040] In one specific embodiment, the method for forming the product adhesive layer includes: adhering the product to the surface of a product substrate by spin coating, spraying, or blade coating; the product substrate includes one of PET, glass, silicon wafer, or metal substrate.

[0041] In one specific embodiment, the mold carrier is an electrostatic adsorption film material; the method for separating the mold carrier from the mold adhesive layer includes: separating by controlling electrostatic force.

[0042] Reference Figure 3 and Figure 4 Based on the replication mold structure and nanoimprint structure preparation method in the embodiments, the specific implementation process of the new process route is illustrated below.

[0043] In the example scenario, during the demolding step, since the master mold typically undergoes surface anti-adhesion treatment to reduce the adhesion between the master mold and the mold adhesive, for the example process route to be feasible, the bonding force between the mold adhesive and the product adhesive must be greater than the adhesion force between the mold carrier and the mold adhesive, which in turn must be greater than the adhesion force between the mold adhesive and the master mold. In the separation stage between the mold carrier and the mold adhesive, the bonding force between the mold carrier and the mold adhesive is much smaller than the bonding force between the mold adhesive and the product adhesive. For example, an electrostatic adsorption film can be used to adsorb the mold adhesive, and after imprinting and curing, the electrostatic adsorption film can be removed to achieve the desired effect. During the etching process, there may be inconsistencies in the thickness of the mold adhesive in different areas, leading to changes in the morphology after etching. In the example scenario, this can be compensated for through targeted design of the master mold structure. For example, when the master mold has a grating structure with a 5μm period and a 1μm depth, the mold adhesive thickness in the edge area is 15% thicker than in the center. Therefore, the groove width in the edge area of ​​the master mold needs to be reduced by 8% beforehand to compensate for this, without limiting the specific situation.

[0044] Figure 4 In the example scenario, eliminating the demolding step in the product adhesive imprinting process (separating the mold adhesive from the mold carrier and adding an etching step to obtain the final pattern) solves all the defects introduced by the demolding process in nanoimprinting. First, a master mold is prepared. The master mold is a quartz or glass wafer with a microstructure on its surface. The master mold typically undergoes an anti-stick treatment to greatly reduce surface energy. Mold adhesive, usually a UV-curable adhesive, is spin-coated onto the master mold. The master mold with mold adhesive is placed on a chuck (a special clamping device for fixing and supporting), and a flexible transparent film is pressed onto the mold adhesive surface using rollers. Then, a UV lamp is used to irradiate the surface of the transparent film, allowing the UV light to penetrate and cure the mold adhesive. After curing, the flexible film is separated from the master mold, at which point the mold adhesive is transferred to the film. The film with mold adhesive is then pressed onto the product adhesive-coated product using a rolling press. After the same exposure and curing process, the film is removed from the mold adhesive. The product with both mold adhesive and product adhesive is then etched to obtain the final structure.

[0045] The mold material can be a transparent film with a small amount of adsorption, such as an electrostatic film. By ensuring that the bonding force between the mold adhesive and the product adhesive is greater than the adhesion force between the mold carrier and the mold adhesive, which is greater than the adhesion force between the mold adhesive and the master mold, the new process route can be realized.

[0046] In this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0047] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A replica mold structure, characterized in that, include: The mold carrier and mold adhesive layer are bonded together; The mold adhesive layer is used to press onto the product adhesive layer on the surface of the product to be prepared nanostructure to obtain the target nanostructure of the product; the adhesive force between the surface of the mold adhesive layer away from the mold carrier and the contact surface of the product adhesive layer is configured as a first adhesive force; the contact surface between the mold adhesive layer and the mold carrier is bonded by a second adhesive force; the first adhesive force is greater than the second adhesive force.

2. The replication mold structure according to claim 1, characterized in that, The mold adhesive layer is formed on the surface of the mold carrier away from the mold carrier and has a nanostructure based on the prefabricated master mold; the adhesive force between the contact surface of the mold adhesive layer and the master mold is configured as a third adhesive force; the second adhesive force is greater than the third adhesive force.

3. The replication mold structure according to claim 1 or 2, characterized in that, The mold carrier is a transparent film material, which includes an electrostatic adsorption film; the mold adhesive layer includes a UV-curable adhesive.

4. A method for preparing nanoimprint structures, characterized in that, The method employs the replication mold structure according to any one of claims 1 to 3; the method includes: A replica mold was prepared; The product adhesive is coated onto the surface of the product substrate to form the product adhesive layer; The replica mold is pressed onto the product adhesive layer, so that the product adhesive fills the nanostructure of the mold adhesive layer and is cured to form a composite structure. Separate the mold carrier from the mold adhesive layer while maintaining the composite structure; Based on the composite structure, selective etching is performed to remove the mold adhesive layer, thereby forming the target nanostructure on the surface of the product substrate.

5. The method for preparing nanoimprint structures according to claim 4, characterized in that, The method for preparing the replica mold includes: A UV-curable adhesive is coated onto the surface of a prefabricated master mold with a nanostructure to form the mold adhesive layer; The mold carrier is pressed together with the mold adhesive layer, so that the UV-curable adhesive fully fills the nanostructure gaps of the master mold; The mold adhesive layer is cured and shaped, and a negative image structure of the nanostructure is formed on the side surface of the mold adhesive layer facing the mother mold. The master mold is separated from the mold adhesive layer to obtain the replica mold.

6. The method for preparing nanoimprint structures according to claim 5, characterized in that, Before applying the UV-curable adhesive, the surface of the master mold is subjected to an anti-adhesion treatment; The anti-adhesion treatment includes: fluorination treatment, silane coupling agent treatment, or self-assembled monolayer treatment.

7. The method for preparing nanoimprint structures according to claim 5, characterized in that, Before coating with UV-curable adhesive, the nanostructure is pre-deformed and compensated based on the thickness distribution model of the UV-curable adhesive in the nanostructure and the deformation characteristics of selective etching.

8. The method for preparing nanoimprint structures according to claim 5, characterized in that, The selective etching method includes: based on the different etching rates of the UV-curable adhesive and the product adhesive, using plasma etching, wet etching or reactive ion etching to completely remove the mold adhesive layer.

9. The method for preparing nanoimprint structures according to any one of claims 4 to 8, characterized in that, The method for forming the product adhesive layer includes: applying the product to the surface of a product substrate by spin coating, spray coating or blade coating; the product substrate includes one of PET, glass, silicon wafer or metal substrate.

10. The method for preparing nanoimprint structures according to any one of claims 4 to 8, characterized in that, The mold carrier is an electrostatic adsorption film material; the method for separating the mold carrier from the mold adhesive layer includes: separating by controlling electrostatic force.

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