Methods for replicating microstructure patterns

Abstract

A method for replicating a microstructured pattern includes the steps of providing a multi-layer structure including a substrate, a thin film, and a positive photoresist, providing a mold having a microstructured pattern, and applying the mold to the multi-layer structure under pressure and temperature, where the microstructured pattern of the mold is replicated on the positive photoresist of the multi-layer structure. An article including a substrate and a thin film having a microstructured pattern is also disclosed.

Description

Technical Field

[0001] [Related Applications] This application claims priority to U.S. Patent Application No. 17 / 338,118, filed on June 3, 2021, the entire disclosure of which is incorporated herein by reference.

[0002] The present disclosure generally includes steps of preparing a multilayer structure including a substrate, a thin film, and a positive-tone photoresist, preparing a mold having a microstructural pattern, and depositing the mold onto the multilayer structure under pressure and temperature, wherein the microstructural pattern of the mold is replicated onto the positive-tone photoresist of the multilayer structure, and relates to a method of replicating a microstructural pattern. Articles including the replicated microstructural pattern are also disclosed.

Background Art

[0003] The polymer-on-glass replication process or stamping process can be used to create a diffuser structure. When following an etching process, it is desirable to have a base portion of the polymer layer with a zero base or negligible thickness (e.g., on the order of hundreds of nanometers). In an etching process following the replication of the microstructures, the etching process window needs to be centered on the depressions / protrusions of the microstructures within the polymer layer. Controlling the base portion of the polymer layer after replication is difficult, making it difficult to control subsequent etching processes for thin films such as high refractive index materials.

Brief Description of the Drawings

[0004] The features of the present disclosure are exemplarily shown in the following figures, and are not limited thereto. In these figures, like numerals indicate like elements, that is, [Figure 1A] A view of depositing a mold having a microstructural pattern onto a multilayer structure according to one aspect of the present invention. [Figure 1B]This figure shows the removal of molds and the replication of microstructure patterns in multilayer photoresist layers. [Figure 1C] This figure shows the irradiation of a collimated light source and the development of the photoresist layer. [Figure 1D] This is a diagram showing the etching of a thin film. [Overview of the project]

[0005] In one embodiment, a method for replicating a microstructure is disclosed, comprising the steps of preparing a multilayer structure including a substrate, a thin film, and a positive-type photoresist; preparing a mold having a microstructure pattern; and depositing the mold onto the multilayer structure under pressure and temperature, wherein the microstructure pattern of the mold is replicated on the positive-type photoresist of the multilayer structure.

[0006] In another embodiment, an article comprising a substrate and a thin film having a microstructure pattern is disclosed.

[0007] Additional features and advantages of various embodiments are described in part below, or will become apparent from the description or through the implementation of various embodiments. The objectives and other advantages of various embodiments are realized and achieved by the elements and combinations specifically noted in this description. [Modes for carrying out the invention]

[0008] For the purposes of simplification and illustration, this disclosure is described primarily by reference to its embodiments. The following description includes numerous specific details to provide a complete understanding of the disclosure. However, it will be readily apparent that the disclosure may be implemented without being limited to these specific details. In other examples, some methods and structures are not described in detail to avoid unnecessarily obscuring the disclosure.

[0009] Furthermore, the elements depicted in the attached figures may include additional components, and some of these components may be removed and / or modified without departing from the scope of this disclosure. In addition, the elements depicted in the figures may not be drawn to scale, and therefore the elements may have different sizes and / or configurations than those shown in the figures.

[0010] It should be understood that both the general description above and the detailed description below are illustrative and descriptive only, and are intended to provide an explanation of various embodiments of this teaching. In its wide and diverse embodiments, disclosed herein are articles, as well as methods for manufacturing and using articles.

[0011] This disclosure describes a method for which the microstructure pattern 20a of the mold 18 is replicated as a replica pattern 20b on the positive photoresist 10 of the multilayer structure 16, as shown in Figure 1A, comprising the steps of preparing a multilayer structure 16 comprising a substrate 14, a thin film 12, and a positive photoresist 10; preparing a mold 18 having a microstructure pattern 20a; and depositing the mold 18 onto the multilayer structure 16 under pressure and temperature.

[0012] The multilayer structure 16 may include a substrate 14, a thin film 12, and a positive photoresist layer 10. The thin film 12 may be any thin film including a single layer and / or a multilayer stack of material. In one embodiment, the thin film 12 may be present on the surface of the substrate 14 and receive the positive photoresist 10 on the support on the opposite side. In one embodiment, the thin film 12 may be a high refractive index material thin film, i.e., a thin film made of a material having a refractive index of about 2 to about 4 around 940 nm. In one embodiment, the thin film 12 may have a refractive index gradient or continuous change or a periodic refractive index profile in the material. The thin film 12 may be present in thickness in the range of about 1 micron to about 20 microns, for example, about 1 micron to about 15 microns, and as a further example, about 3 microns to about 10 microns. The thin film may be present on the surface of the substrate 14 and / or on the surface of the photoresist 10.

[0013] In another embodiment, the thin film 12 can be a multilayer stack. The multilayer stack may include one or more layers of a reflector material, a magnetic material, a dielectric material, and an absorbing material.

[0014] The substrate 14 may be any material capable of withstanding multiple layers. In one embodiment, the thin film 12 may be present on the surface of the substrate. In one embodiment, the substrate 14 may be a transparent material. Non-limiting examples of suitable substrate materials include glass and polymers, such as polycarbonate, polymethyl methacrylate, polyethylene terephthalate, polyethylene, amorphous copolyester, polyvinyl chloride, liquid silicone rubber, cyclic olefin copolymer, ionomer resin, transparent polypropylene, fluorinated ethylene propylene, styrene-methyl methacrylate, styrene-acrylonitrile resin, polystyrene, methyl methacrylate-acrylonitrile-butadiene-styrene, and the like. The substrate 14 may be present in thicknesses ranging from about 50 microns to about 2000 microns, for example, from about 100 microns to about 1500 microns, and in further examples, from about 150 microns to about 1000 microns.

[0015] The substrate 14 can have a thickness ranging from approximately 50 microns to approximately 2000 microns, for example, from approximately 100 microns to approximately 1500 microns, and as a further example, from approximately 150 microns to approximately 1000 microns.

[0016] In one embodiment, the positive photoresist 10 may be adjacent to (sharing a common boundary with) the thin film 12 and / or may be present on the surface of the thin film 12. The positive photoresist may be a low-contrast photoresist with photosensitivity similar to or identical to low-contrast photoresists used in grayscale lithography. The positive photoresist may be DNQ-novolac (a mixture of diazonaphthoquinone (DNQ) and novolac resin (phenol-formaldehyde resin)). Examples of low-contrast photoresists include the registered trademark AZ product available from Merck KGaA and MEGAPOSIT available from Dow Chemical. TM SPR TM Examples of products include the photoresist, which can be spin-coated onto the surface of the thin film 12 to a thickness of several microns to tens of microns. In one embodiment, the photoresist 10 can be spray-coated onto the surface of the thin film 12. The thickness of the photoresist 10 can be greater than the height from the apex to the valley of the structure on the mold 18 for high-quality and effective embossing / stamping.

[0017] As shown in Figure 1A, the mold 18 may have a microstructure pattern 20a. The mold 18 can be made of a material that can receive and hold the microstructure pattern 20a. Non-limiting examples of materials include metals, semiconductors, dielectrics such as nickel, silicon, and fused silica, glass, quartz, and combinations thereof. In one embodiment, the mold 18 may be made of a conductive material. In another embodiment, the mold 18 may be made of a thermally conductive material and have a microstructure pattern 20a.

[0018] The microstructure pattern 20a can be random or periodic. In one embodiment, the microstructure pattern 20a can be a binary (two-value) pattern. In another embodiment, the microstructure pattern 20a can be a grayscale non-binary pattern. The microstructure pattern 20a can include various shapes, forms, images, depressions, protrusions, and combinations thereof of various sizes. The microstructure pattern 20a can include uniform and irregular parts. For example, as shown in Figure 1A, the microstructure pattern 20a includes three distinct triangular depressions uniformly separated from each other by a planar portion.

[0019] In one embodiment, the mold 18 may include a release agent (not shown) applied as a coating on the microstructure pattern 20a. The release agent may be a hydrophobic self-assembled monolayer such as a low surface energy fluoropolymer or hydrophobic silane. The release agent may be applied to the mold 18 by any deposition process that can deposit the release agent into depressions / protrusions of the microstructure pattern 20a. Non-limiting examples of suitable deposition processes include spin coating and dip coating, chemical vapor deposition, physical vapor deposition such as sputtering or thermal evaporation, and physical coating such as buffing the surface of the microstructure pattern 20a with the release agent.

[0020] As shown in FIG. 1A, the mold 18 can be deposited on the surface of the photoresist 10 of the multilayer structure 16. The method can include the step of applying pressure and temperature to the mold 18 and / or the multilayer structure 16. In one aspect, the step of depositing the mold 18 on the multilayer structure 16 can be an embossing process or a stamping process. The heated mold 18 can be brought into contact with the photoresist surface and placed there for about 1 second to about 10 seconds before applying pressure. The embossing process time after pressure is applied to the mold 18 can take values in the range of about 1 second to about 30 seconds. The temperature can take values in the range of about 60°C to about 90°C. The pressure can take values in the range of about 5 PSI to about 60 PSI. In one aspect, the process conditions included a pressure of about 10 PSI for about 20 seconds at a temperature of about 167°F (75°C). In another aspect, the process conditions included a pressure of about 20 PSI for about 20 seconds at a temperature of about 167°F (75°C).

[0021] In this way, the fine structure pattern 20a of the mold 18 can be replicated and / or substantially replicated on the positive photoresist 10 of the multilayer structure 16. In one aspect, the replicated fine structure pattern 20b can have a phase and / or polarity opposite to that of the original fine structure pattern 20a.

[0022] The method includes the step of removing the mold 18 from the multilayer structure 16, as shown in FIG. 1B. The positive photoresist 10 can have the replicated fine structure pattern 20b and can also include the base portion 22 of the positive photoresist 10 that does not have the replicated fine structure pattern 20b. The base portion 22 of the positive photoresist 10 can have an initial thickness in the range of about 0.001 μm to about 10 microns, such as about 0.01 micron to about 8 microns, and as a further example, about 0.1 micron to about 5 microns.

[0023] The replicated microstructural pattern 20b can be the inverse pattern of the microstructural pattern 20a of the mold 18. For example, while the microstructural pattern 20a of the mold 18 can include three separate parts of triangular depressions, the microstructural pattern 20b of the photoresist 10 can include three separate parts of triangular protrusions.

[0024] As shown in FIG. 1C, the method can include the step of irradiating the multilayer structure 16 with flood exposure by using a collimated light source 24, and the collimated light 24 exposes the replicated microstructural pattern 20b and the base portion 22 of the photoresist 10 that does not have the replicated microstructural pattern 20b. The collimated light source 24 can be a light source that emits collimated light, such as a photomask aligner lamp, a dedicated i-line UV exposure tool, or a UV-LED / laser setup. In another aspect, the collimated light source can be a light source that emits collimated light, such as a lens or a mirror that receives diffused light and emits collimated light.

[0025] The application of flood exposure can follow a subsequent development step. In particular, the method can include the step of developing the base portion 22 of the positive photoresist 10 at a uniform rate. The development of the base portion 22 can be completed, for example, as shown in FIG. 1C, until the surface portion 26 of the underlying thin film 12 is completely exposed so that there is no base portion 22 between the microstructural pattern 20b and the surface of the thin film 12. In one aspect, the development of the base portion​​​The developing step may include applying an aqueous-alkaline-based developer to the photoresist 10. In one embodiment, after irradiation with collimating light, the structure includes a substrate 14, a thin film 12, and a replicated microstructure pattern 20b adjacent to or on the surface of the thin film 12. In one embodiment, the base portion 22 of the photoresist 10 is absent after development following exposure to collimating light. In another embodiment, the base portion 22 after exposure to collimating light and development may have a reduced thickness compared to the initial thickness of the base portion 22 after the molding 18 is attached.

[0027] As shown in Figure 1D, the method also includes the step of etching the photoresist 10 and the thin film 12 to form an etched microstructure pattern 20c on the thin film 12. After etching, the thin film 12 includes portions having the replicated microstructure pattern 20c and / or portions having the original thickness of the thin film 12. There may be portions that do not contain the thin film 12 at all, i.e., portions where the thin film 12 is absent. The etching step can be carried out using any technique for etching the photoresist material. Non-limiting examples of suitable etching techniques include reactive ion etching (RIE), inductively coupled plasma-reactive ion etching (ICP-RIE), and ion milling. Etching can remove any remaining photoresist 10 from the multilayer structure 16, such as the surface of the thin film 12. Etching can transfer the morphology of the microstructure pattern 20b in the photoresist to the thin film 12.

[0028] The etched microstructure pattern 20c of the thin film 12 may have opposite polarity to the microstructure pattern 20a of the mold 18, and may also have the same aspect ratio or not. The etched microstructure pattern 20c of the thin film 12 may have the same polarity to the microstructure pattern 20a of the mold 18, and may also have the same aspect ratio or not.

[0029] From the above description, those skilled in the art will understand that these teachings can be implemented in various forms. Therefore, although these teachings have been described in relation to their specific embodiments and examples, the true scope of these teachings should not be limited in this way. Various changes and modifications can be made without departing from the scope of the teachings herein.

[0030] This disclosure is to be interpreted broadly. This disclosure is intended to disclose equivalents, means, systems, and methods for achieving the coatings, devices, activities, and mechanical actions disclosed herein. With respect to each of the disclosed coatings, devices, articles, methods, means, mechanical elements, or mechanisms, this disclosure is also intended to include and teach equivalents, means, systems, and methods for carrying out many of the embodiments, mechanisms, and devices disclosed herein.

Claims

1. The method involves the following steps, namely, The steps of preparing a multilayer structure comprising a substrate, a thin film, and a positive-type photoresist, wherein the thin film is a multilayer stack disposed between the substrate and the positive-type photoresist, and comprises one or more layers of a reflector material, a magnetic material, or a dielectric material, and the material of the thin film has a refractive index gradient or continuous change, or a periodic refractive index profile, The steps include preparing a mold having a microstructure pattern, The steps include applying pressure and temperature to adhere the mold to the multilayer positive-type photoresist, A step of removing the mold from the positive-type photoresist, wherein the fine structure pattern of the mold is replicated on the multilayer positive-type photoresist, The process involves exposing a replicated microstructure pattern by irradiating it with flood exposure using a collimated light source, The process involves developing the positive-type photoresist by applying an aqueous-alkaline-based developer to the positive-type photoresist, The steps include etching the thin film to transfer the morphology of the microstructure pattern replicated on the positive photoresist to the thin film, A method for providing this.

2. The method according to claim 1, wherein the thin film is a high refractive index thin film.

3. A method according to claim 1, wherein the mold having the microstructure pattern is coated with a release agent.

4. The method according to claim 1, wherein the microstructure pattern of the mold is a grayscale pattern.

5. The method according to claim 1, wherein the microstructure pattern of the mold is a random pattern.

6. A method according to claim 1, wherein the step of adhering the mold to the multilayer structure is an embossing process.

7. The method according to claim 1, wherein the positive photoresist having the replicated microstructure pattern includes a base portion of the positive photoresist not having the replicated microstructure pattern.

8. The method according to claim 7, A method wherein the collimating light exposes the replicated microstructure pattern and the base portion of the positive photoresist.

9. A method according to claim 8, further comprising the step of developing the base portion of the positive photoresist at a uniform speed.

10. A method according to claim 9, wherein the step of developing the base portion is to reduce the thickness of the base portion of the positive photoresist, thereby exposing the surface portion of the thin film.

11. The method according to claim 1, wherein the etching is a method for removing all of the remaining positive-type photoresist from the multilayer structure.

12. In the method according to claim 1, The step of transferring the morphology of the replicated microstructure pattern to the thin film is performed when the phase / polarity is opposite to that of the microstructure pattern of the mold, or A method comprising the step of transferring the morphology of the replicated microstructure pattern to the thin film, wherein the replicated microstructure pattern of the positive photoresist is identical in terms of phase / polarity and does not have the same aspect ratio.

13. The method according to claim 1, wherein the replicated microstructure pattern of the positive photoresist is the same as the microstructure pattern of the mold and has the opposite phase / polarity.

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