Roll-to-roll imprint

Abstract

The present invention relates to roll-to-roll surface patterning by an imprinting method. A film of liquid resist is coated onto a traveling web and subsequently brought into contact with a rolling replication tool having patterned features on its outer surface. In a simultaneous step, the resist is cured, typically by heat or UV light, and the patterned features of the rolling replication tool are replicated in the resist film during contact with the replication tool. A major drawback of conventional roll-to-roll imprinting is the generation of defects in the pattern due to trapped air. To overcome this limitation, the present invention describes a method and apparatus for performing roll-to-roll imprinting under reduced pressure or vacuum conditions.

Description

Technical Field

[0001] The present invention relates to systems and methods related to creating microscale and nanoscale structures. More particularly, the present invention discloses systems and methods that can be used to rapidly and continuously manufacture micro- and nanostructures for various purposes while eliminating bubble formation in the resist.

Background Art

[0002] Imprinting, also known as nanoimprinting, is a method for manufacturing micro- and nanometer-scale patterns and / or structures. The imprint process is low-cost, high-throughput, and enables high resolution through direct mechanical deformation of the resist material. The imprinted patterns and / or structures have a wide range of applications in, for example, biomedicine, micro- and nanofluidics, data storage, electronic devices, and microelectromechanical devices. The resulting structures can be completely or at least partially flexible or stretchable or rigid.

[0003] Roll-to-roll imprinting has been developed to enable high-speed processing to meet the demand for low-cost patterning. A resist film, typically a monomer or polymer composition, is coated onto a web of substrate made of any suitable material that can be provided in roll form and does not interfere with the curing process of the resist material. For example, the substrate may be made of plastic such as polyethylene terephthalate (PET), cyclic olefin copolymer (COC), or polycarbonate (PC), but may also be made of paper, thin sheet, metal, etc., or any combination thereof. Next, a cylindrical replication tool having a predetermined morphological mold pattern on its outer surface is brought into contact with the resist and pressed against each other under a specific pressure. During the patterning stage of the imprint process, the resist is at least partially in a liquid form. During the contact time with the replication tool, the resist is cured by heat, UV light, IR, or other suitable electromagnetic radiation.

[0004] One problem in imprinting is that gas bubbles or air bubbles can become trapped within the resist or between the resist and the replication tool, potentially resulting in defective imprinted products. Solutions to reduce or eliminate bubble formation in batch imprinting have been provided previously. However, no practical solution to reduce or eliminate bubble formation in roll-to-roll imprinting has been provided.

[0005] Explanation of conventional technology Patent Document 1 discloses an imprint apparatus for ultraviolet roll-to-roll imprinting. By using a gas environment creation unit that creates a pseudo-enclosure with a localized gas environment by injecting an exotic gas at the points where the resist, plastic web, and mold come into contact with each other, the amount of air trapped within the plastic web is minimized. Thus, by eliminating air during the shrinkage of the plastic web and the imprint drum or sheet, bubble formation and oxygen inhibition are partially minimized.

[0006] Non-patent document 1 suggests that various solutions for suppressing gas confinement for batch-mode UV nanoimprinting may be adaptable to roll-to-roll nanoimprinting. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Singapore Patent No. 10201403829 [Non-patent literature]

[0008] [Non-Patent Document 1] "High resolution UV roll-to-roll nanoimprinting of resist molds and subsequent replication via thermal nanoimprint lithography" by J. Dumond et al., Nanotechnology 23(48):485310, November 2012. [Overview of the project] [Problems that the invention aims to solve]

[0009] The objective is to provide an apparatus and method for solving the problem of reducing bubble formation in the resist during roll-to-roll imprinting. [Means for solving the problem]

[0010] The object of the present invention is achieved by the apparatus described in claim 1. The object of the present invention is further achieved by the manufacturing method described in claim 6. The manufacturing method enables the production of nanostructures as defined in claim 11.

[0011] Preferred embodiments of the present invention are disclosed in the dependent claims.

[0012] According to a first embodiment, a roll-to-roll imprint apparatus is provided. The apparatus comprises an unwinding unit configured to unwind a substrate web, and optionally a substrate web pre-treatment unit configured to pre-treat the substrate web. The apparatus also comprises a mixing and coating unit configured to prepare a resist by mixing at least two component materials, or to obtain a single-component resist material and optionally stir it, and to coat the substrate web with the resist to form a resist film. The apparatus also comprises an impression roller unit configured to pattern a resist film in a continuous process by applying pressure to the resist film by pressing the resist film between the substrate web and a mold placed or formed on the outer surface of a rolling replication tool, the mold thereby defining a plurality of nanostructures within the resist; a curing unit associated with the impression roller unit and configured to at least partially cure the pattern resist having the mold pattern nanostructures before removing the pattern resist from the mold; and a rewinding unit configured to unwind the substrate web having the cured nanostructures.

[0013] The apparatus further comprises a vacuum chamber that encloses an unwinding unit, an optional pretreatment unit, a mixing and coating unit, an impression roller unit, a curing unit, and an unwinding unit during operation, wherein the vacuum chamber air pressure during operation of the enclosed units is between 0 atm and 0.5 atm, preferably between 0.1 atm and 0.5 atm.

[0014] According to a second embodiment, the roll-to-roll imprint apparatus further comprises a liner unwinding unit, which is enclosed in a vacuum chamber during operation and configured to unwind a protective liner from an unwinding substrate web before the substrate web is pre-treated by a pre-treatment unit and / or before the substrate web is coated with a resist film by a mixing and coating unit, and / or a liner unwinding unit, which is enclosed in a vacuum chamber during operation and configured to supply a protective liner onto a cured nanostructure on the substrate web before the substrate web having the cured nanostructure is unwinded. The liner unwinding unit and / or the liner unwinding unit are each enclosed in a vacuum chamber during their operation.

[0015] According to a third embodiment, the impression roller unit is configured to allow adjustment of at least one of the following: the cutting angle of the substrate web coated with a resist film; the pressure applied to the resist when pressed between the mold and the substrate web; the curing temperature used to cure the resist; the radiation intensity used to cure the resist; and the demolding angle of the substrate web having at least partially cured resist.

[0016] According to a fourth embodiment, the at least two component materials of the resist or the single component resist material are supplied to a mixing and coating unit by one or more pipelines, each coupled to its respective storage container. The storage containers are located either inside or outside a vacuum chamber. The internal pressure inside the storage containers is between 0 atm and 0.5 atm, preferably between 0.1 atm and 0.5 atm, and more preferably equal to the air pressure inside the vacuum chamber during operation of the roll-to-roll imprint apparatus.

[0017] According to the fifth aspect, the resist is an uncured monomer or prepolymer mixture prepared by mixing the at least two component materials, or the resist is a single-component resist material.

[0018] According to a first method embodiment, a roll-to-roll nanostructure manufacturing method is provided. The method includes the steps of unwinding a substrate web; optionally pre-treating the substrate web; preparing a resist by mixing at least two component materials or obtaining a single-component resist and optionally stirring it; coating the substrate web with the resist to form a resist film; patterning the resist film in a continuous process by applying pressure to the resist film by pressing the resist film between the substrate web and a mold placed or formed on the outer surface of a rolling replication tool, the mold thereby defining a plurality of nanostructures within the resist; curing a pattern resist film containing the pattern nanostructures, the curing being performed at least partially before removing the pattern resist from the mold; and unwinding the substrate web having the cured nanostructures. The method includes the steps of: enclosing an apparatus for performing a step in a vacuum chamber; reducing the air pressure in the vacuum chamber so that the air pressure in the vacuum chamber is between 0 atm and 0.5 atm, preferably between 0.1 atm and 0.5 atm; and, after the step of reducing the air pressure, performing a step of a roll-to-roll nanostructure manufacturing method using the apparatus enclosed in the vacuum chamber.

[0019] According to a second embodiment of the method, the method further includes at least one of the following steps: unwinding a protective liner from an unwound substrate web before performing an optional pretreatment of the substrate web by a pretreatment unit and / or before coating the substrate web with a resist film; and supplying the protective liner over the cured nanostructures on the substrate web before unwinding the substrate web having the cured nanostructures. Apparatus for performing the step of unwinding the protective liner and / or the step of supplying the protective liner is enclosed in a vacuum chamber, and the steps of unwinding the protective liner and / or supplying the protective liner are performed in the vacuum chamber after the step of reducing the air pressure.

[0020] According to a third method aspect, the method further includes at least one of the steps of adjusting the cutting angle of a substrate web coated with a resist film, adjusting the pressure applied to the resist when pressed between a mold and the substrate web, adjusting the curing temperature used to cure the resist, adjusting the radiation intensity used to cure the resist, and adjusting the release angle of the substrate web having at least partially cured resist.

[0021] According to a fourth method aspect, the method further includes the step of obtaining each of the substances of the resist mixed from respective storage containers, wherein the storage containers are inside a decompression chamber or the storage containers are outside the decompression chamber, and the internal pressure in the storage containers is between 0 atm and 0.5 atm, preferably between 0.1 atm and 0.5 atm, more preferably equal to the air pressure in the decompression chamber during operation of a roll-to-roll imprint apparatus.

[0022] According to a fifth method aspect, the resist is an uncured monomer or prepolymer mixture prepared by mixing the at least two component substances, or the resist is a single component substance.

[0023] According to another aspect, a nanostructure is provided, the nanostructure is manufactured by a manufacturing process according to any of the above method aspects, and the nanostructure includes any one of an optical nanostructure, an electronic nanostructure, a data storage nanostructure, a microelectromechanical nanostructure, a micro or nanofluidic nanostructure, and a biomedical nanostructure.

[0024] The present invention is based on the idea of arranging the entire roll-to-roll imprint process execution apparatus inside a decompression chamber and enabling the execution of the imprint process in a decompression or vacuum atmosphere.

[0025] The present invention has the advantage of enabling the imprinting of high-quality nano- and / or microstructures at high production speeds using a substrate web.

[0026] Hereinafter, the present invention will be described in more detail in connection with preferred embodiments, with reference to the accompanying drawings.

Brief Description of the Drawings

[0027] [Figure 1] It is a diagram showing the operation of a rolling replication tool in a normal ambient atmosphere. [Figure 2] It is a diagram showing the operation of a rolling replication tool in a reduced-pressure atmosphere or vacuum. [Figure 3] It is a schematic diagram of a typical implementation of a roll-to-roll imprint process according to the present invention.

Modes for Carrying Out the Invention

[0028] The term (one or more) nanostructures refers to (one or more) nano- and / or micro-patterns and structures.

[0029] Figure 1 schematically illustrates the operation of a rolling replication tool (15b) in a normal ambient atmosphere. A mold for defining one or more nanostructures is positioned or formed on the outer surface of the rolling replication tool, typically formed as a cylinder, which is rotated around its central axis during the imprint process. This simplified diagram shows the mold as multiple "teeth" on the outer surface of the rolling replication tool (15b). The rolling direction of the cylindrical rolling replication tool (15b) around its central axis of symmetry is indicated by a curved arrow (25). The substrate web (150) is coated with a resist (160). The resist, particularly a resist prepared from at least two component materials, may include, for example, an uncured monomer or prepolymer mixture, at least partially in liquid form. Alternatively, the resist may include any single-component resist known in the art, such as liquid silicone rubber. The substrate web having the resist (160) is transported across the rolling replication tool (15b) so that the resist (160) is pressed between the rolling replication tool (15b) and the substrate web (150) with a predetermined pressure, as indicated by arrow 26. The patterned mold on the outer surface of the rolling replication tool (15b) is thus pressed against the resist (160), thereby taking the shape defined by the mold pattern. The pattern resist (165') is cured to fix the imprinted nanostructure. The curing is performed at least partially before the pattern resist (165') is removed from the mold to avoid deformation of the nanostructure generated within the resist during removal.

[0030] When the imprint process is performed in a normal ambient atmosphere of approximately 1 atm, bubbles (10) can become trapped within the resist (160) during and / or after coating the resist layer of the substrate, and / or between the resist and the mold placed or formed on the outer surface of the rolling replication tool (15b). Such trapped bubbles (10) cause deformation of nanostructures within the pattern resist (165'). This is a major quality issue in roll-type imprinting, which allows for lower costs and higher imprint speeds compared to batch-type imprinting.

[0031] Figure 2 schematically illustrates the steps of the imprint process using a rolling replication tool (15b) in a reduced-pressure atmosphere or vacuum. A reduced-pressure atmosphere refers to an atmosphere with an air pressure significantly lower than the normal ambient pressure (1 atm), preferably 0.5 atm or less. The imprint process itself is essentially the same as in Figure 1. However, in a reduced-pressure atmosphere or vacuum, trapped bubbles (10) in the resist are removed, and no bubbles are trapped between the mold and the resist (160) on the surface of the rolling replication tool (15b). Therefore, the nanostructures formed within the cured resist (165) are essentially free from deformation caused by bubbles. Thus, performing the imprint process in a low atmospheric pressure or vacuum significantly improves the quality of products manufactured using the imprint process.

[0032] For most applications, reduced pressure is preferred over vacuum. Reduced pressure atmospheres are easier to achieve, and vacuum can cause problems with the resist. For example, vacuum can cause vaporization of components in the resist material, creating a new source of gas bubbles that can cause quality problems similar to those caused by bubbles. The preferred air pressure in a reduced pressure atmosphere is between 0.1 atm and 0.5 atm, but in some processes, even lower air pressures or vacuum may be preferred or required for best results.

[0033] Figure 3 shows a schematic diagram of a preferred embodiment of the present invention.

[0034] The substrate web (150), abbreviated as the substrate (150), is brought into the process on the unwinding unit (100). The substrate (150) may be covered with a protective liner (155), as indicated by the double line exiting the unwinding unit (100). The protective liner (155) is removed to expose the substrate material to the process, and the protective liner (155) is unwound by a liner unwinding unit (101). The imprint process is then applied to the substrate (150).

[0035] The substrate (150) may optionally be pre-treated by a pre-treatment unit (102) to pre-treat the substrate (150) for imprinting before the substrate (150) is coated with the resist (160). For example, the pre-treatment unit (102) may include a corona unit and / or a plasma treatment unit for treating the substrate (150). Corona and plasma treatments for improving wetting of the substrate web (150) by the subsequent resist (160) and / or adhesion between the substrate web (150) and the resist (160) are known in the art. Alternatively, the pre-treatment unit (102) may be omitted or simply not used if not necessary.

[0036] In the present example, the mixing and coating unit (103) receives component or single-component resist material for preparing a resist from one or more external storage containers (104a, 104b). The one or more external storage containers are preferably at the same pressure as the imprint apparatus during operation. This ensures controllable coating of the resist material and reduces air trapping within the resist. Thus, the amount of gas bubbles in the resist component or single-component resist material, and consequently the amount of gas in the resist, can be reduced, and the formation of bubbles during mixing of the resist is also reduced. If the resist is a mixture of at least two component materials, the received component materials are mixed by the mixing and coating unit (103) to prepare the resist (160). Single-component resists, such as liquid silicone rubber, do not require mixing but may be optionally agitated by the mixing and coating unit. A thin film of the resist (160) can be coated onto a substrate using, for example, a knife, a spiral bar, or any other applicable method known in the art. The resist (160) coated substrate (150) is then fed into an impression roller unit (105) comprising a set of impression rollers (15a, 15c) and a rolling replication tool (15b). A mold for defining a nanostructure is attached to or patterned on the outer surface of the rolling replication tool (15b) toward the resist so that the resist is pressed between the substrate web (150) and the rolling replication tool (15b) to generate pressure on the resist material pressed toward the mold pattern. The pattern is typically a microscale and / or nanoscale feature, but may be larger than and / or comprise an essentially flat pattern and / or microscale feature. Thus the mold presses the resist into the desired pattern, thus causing the resist to take on the shape of the desired topology. The impression rollers (15a, 15c) of the impression roller unit (105) are preferably adjustable so that both the cutting angle and the demolding angle and / or pressure can be adjusted.Before releasing the resist from the mold and rolling replication tool (15b), the resist is at least partially cured by a curing unit (not shown) to fix the nanostructure. The curing can be carried out by any suitable curing method, depending on the resist. For example, thermal curing, ultraviolet curing, infrared curing, or any other suitable radiation curing can be applied, which trigger curing processes such as polymerization and / or crosslinking. The curing of the nanostructure is initiated during the molding (patterning) stage, but it is sufficient for the nanostructure to be cured to a point where it can be demolded, in other words, removed from the mold, without deformation due to demolding, and the nanostructure may be further cured after demolding.

[0037] In the case of thermal curing, the curing temperature is preferably adjustable. The optimal curing temperature depends, for example, on the type of resist used and / or the thickness of the resist layer and / or the structural properties of the nanostructure and / or other processing parameters such as the web speed. For example, when using a silicone elastomer as the resist, the curing temperature is preferably between 135°C and 165°C, depending on the silicone resist used. The nanostructure (165) of the substrate web (150) is then cooled while being transported forward. Similarly, when curing with other types of radiation, such as UV radiation, the intensity of the radiation is preferably adjustable. The curing period can be adjusted, for example, by adjusting the sector width of the rolling replication tool on which curing is performed and / or by adjusting the rolling speed of the substrate.

[0038] The cured nanostructure supported by the substrate (150) may be protected by a protective liner (170) supplied from a liner supply unit (106) before the liner protective substrate (180) having the nanostructure is unwound on the unwinding unit (107). Multiple rollers (110) facilitate the guidance of the substrate web (150) throughout the process, ensuring that the substrate web (150) moves smoothly and that tension is applied appropriately and uniformly throughout the manufacturing process.

[0039] To suppress the generation of air or gas bubbles in the resist during the imprint process, the roll-to-roll imprint apparatus is enclosed in a reduced pressure or vacuum chamber (120) from the unwinding unit (100) to the unwinding unit (107). If liners (155, 170) are used, preferably the liner unwinding unit (101) and liner supply unit (106) are also enclosed in the reduced pressure chamber (120). The reduced pressure or vacuum chamber is preferably coupled to at least one pump for evacuating air, thus reducing the air pressure. As already mentioned above, the pressure in the reduced pressure chamber is preferably in the range of 0.1 atm to 0.5 atm. Vacuum may also be an applicable option, but it is not practical for all types of resists because some component materials in the resist tend to vaporize in a vacuum, which can generate gas bubbles in the resist itself. By running the entire roll-to-roll imprint process in a controlled environment, the imprint process can be run continuously in large quantities without compromising the quality of the resulting nanostructures.

[0040] As technology advances, it will be apparent to those skilled in the art that the fundamental concepts of the present invention can be realized in various ways. Therefore, the present invention and its embodiments are not limited to the examples given above and may vary within the scope of the claims.

Claims

1. A roll-to-roll imprinting device, An unwinding unit configured to unwind a circuit board web, A substrate web preprocessing unit configured to selectively preprocess the substrate web, A mixing and coating unit configured to prepare a resist by mixing at least two component materials, or to obtain a single-component resist material and optionally stir it, and to coat the substrate web with the resist to form a resist film, An impression roller unit is configured to pattern the resist film in a continuous process by applying pressure to the resist film by pressing the resist film between the substrate web and a mold placed or formed on the outer surface of a rolling replication tool, wherein the mold thereby defines a plurality of nanostructures within the resist. A curing unit associated with the impression roller unit and configured to at least partially cure the pattern resist comprising the mold pattern nanostructure before removing the pattern resist from the mold, The system comprises a rewinding unit configured to rewind the substrate web having the cured nanostructure, The apparatus further comprises a vacuum chamber containing the unwinding unit, the optional pretreatment unit, the mixing and coating unit, the impression roller unit, the curing unit, and the unwinding unit, wherein the air pressure in the vacuum chamber during the operation of the contained units is between 0.1 atm and 0.5 atm. Roll-to-roll imprinting machine.

2. The aforementioned device is A liner unwinding unit, which is sealed in the reduced pressure chamber during operation and configured to unwind a protective liner from the unwound substrate web before the substrate web is pre-treated by the pre-treatment unit and / or before the substrate web is coated with the resist film by the mixing and coating unit, and / or The liner unwinding unit is enclosed in the reduced pressure chamber during operation and is configured to supply a protective liner over the cured nanostructures on the substrate web before unwinding the substrate web having the cured nanostructures, The liner unwinding unit and / or the liner unwinding unit are each sealed within the depressurization chamber during their operation. The roll-to-roll imprint apparatus according to claim 1.

3. The impression roller unit is, The cutting angle of the substrate web coated with the resist film, The pressure applied to the resist when pressed between the mold and the substrate web, The curing temperature used to cure the resist, The radiation intensity used to cure the resist, The configuration allows adjustment of at least one of the demolding angles of the substrate web having the at least partially cured resist. The roll-to-roll imprint apparatus according to claim 1 or 2.

4. The at least two component materials of the resist or the single component resist material are supplied to the mixing and coating unit by one or more pipelines, each of which is coupled to its respective storage container. Each of the aforementioned storage containers is located either inside the vacuum chamber or outside the vacuum chamber. The internal pressure inside each of the aforementioned storage containers is between 0.1 atm and 0.5 atm. A roll-to-roll imprint apparatus according to any one of claims 1 to 3.

5. The resist is an uncured monomer or prepolymer mixture prepared by mixing the at least two component substances, or the resist is a single-component resist material. A roll-to-roll imprint apparatus according to any one of claims 1 to 4.

6. A method for manufacturing a roll-to-roll nanostructure, The steps of unwinding the circuit board web and A step of selectively pre-processing the substrate web, The steps include preparing a resist by mixing at least two component substances or by obtaining a single-component resist and optionally stirring it, The steps include coating the substrate web with the resist to form a resist film, A step of patterning the resist film in a continuous process by applying pressure to the resist film by pressing the resist film between the substrate web and a mold placed or formed on the outer surface of a rolling replication tool, wherein the mold thereby defines a plurality of nanostructures within the resist. A step of curing the pattern resist film containing the aforementioned type pattern nanostructure, wherein the curing is performed at least partially before removing the pattern resist from the mold. The step of unwinding the substrate web having the cured nanostructure is included, In the aforementioned method, The apparatus is sealed in a depressurized chamber to perform each of the above steps, The air pressure inside the vacuum chamber is reduced so that the air pressure inside the vacuum chamber is between 0.1 atm and 0.5 atm. After reducing the air pressure, the above steps of the roll-to-roll nanostructure manufacturing method are performed by the apparatus sealed in the depressurization chamber. A method for manufacturing roll-to-roll nanostructures.

7. The aforementioned method, Before performing the optional pretreatment on the substrate web by the pretreatment unit and / or before coating the substrate web with the resist film, the step of unwinding the protective liner from the unwound substrate web, and The process further includes at least one of the steps of supplying a protective liner over the cured nanostructures on the substrate web before unwinding the substrate web having the cured nanostructures, An apparatus for performing the steps of unwinding the protective liner and / or supplying the protective liner is enclosed within the vacuum chamber. The steps of unwinding the protective liner and / or supplying the protective liner are performed in the depressurization chamber after the air pressure has been reduced. The method for manufacturing a roll-to-roll nanostructure according to claim 6.

8. The aforementioned method, A step of adjusting the cutting angle of the substrate web coated with the resist film, A step of adjusting the pressure applied to the resist when pressed between the mold and the substrate web, A step of adjusting the curing temperature used to cure the resist, A step of adjusting the radiation intensity used to cure the resist, The step further includes at least one of adjusting the demolding angle of the substrate web having the at least partially cured resist, A method for manufacturing a roll-to-roll nanostructure according to claim 6 or 7.

9. The method further includes the step of obtaining each of the substances of the resist mixed from each storage container, Each of the storage containers is either located inside the vacuum chamber or outside the vacuum chamber, and the internal pressure inside each storage container is between 0.1 atm and 0.5 atm. A method for manufacturing a roll-to-roll nanostructure according to any one of claims 6 to 8.

10. The resist is an uncured monomer or prepolymer mixture prepared by mixing the at least two component substances, or the resist is a single component substance. A method for manufacturing a roll-to-roll nanostructure according to any one of claims 6 to 9.

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