IMPRINT TEMPLATE AND METHOD FOR PRODUCING THE SAME

Abstract

An imprint template is used for photocuring imprinting, and includes a support plate that is transparent with respect to an exposure wavelength used for photocuring imprinting, and has flexibility; a buffer resin layer that is formed on the support plate, and is formed of an elastic material that is transparent with respect to the exposure wavelength; and a resin film mold that is removably bonded to the buffer resin layer, and is transparent with respect to the exposure wavelength, wherein a concave-convex transfer pattern is formed on a surface of the resin film mold.

Claims

1. An imprint template comprising: a support plate that is transparent with respect to an exposure wavelength used for photocuring imprinting, and has flexibility; a buffer resin layer that is formed on the support plate, and is transparent with respect to the exposure wavelength; and a resin film mold that is removably bonded to the buffer resin layer, and is transparent with respect to the exposure wavelength, wherein a concave-convex transfer pattern is formed on a surface of the resin film mold.

2. The imprint template as defined in claim 1, wherein the support plate is formed of transparent glass or a transparent resin, and has a thickness of 0.1 mm or more and less than 0.5 mm.

3. The imprint template as defined in claim 1, further comprising: a release film that is formed on the surface of the resin film mold at least in an area in which the concave-convex transfer pattern is formed.

4. The imprint template as defined in claim 1, wherein the resin film mold is formed of a cyclo-olefin polymer resin.

5. A method for producing an imprint template comprising: forming a buffer resin layer on a surface of a support plate, the support plate being transparent with respect to an exposure wavelength used for photocuring imprinting, and having flexibility, and the buffer resin layer being formed of an elastic material that is transparent with respect to the exposure wavelength; and subjecting a back surface of a resin film mold that is transparent with respect to the exposure wavelength to a plasma treatment, and bonding the back surface of the resin film mold to a surface of the buffer resin layer, a concave-convex transfer pattern being formed on a front surface of the resin film mold.

6. The method for producing an imprint template as defined in claim 5, wherein the support plate is formed of transparent glass or a transparent resin, and has a thickness of 0.1 mm or more and less than 0.5 mm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0095] FIG. 1 illustrates an example of the structure of the imprint template according to the invention.

[0096] FIG. 2 illustrates an example of a method for producing an imprint template.

[0097] FIG. 3 illustrates an example of a transfer method that utilizes the imprint template according to the invention.

[0098] FIG. 4 illustrates a photograph of the outward appearance of the nanoimprint template according to the invention.

[0099] FIG. 5 is a birds-eye view obtained by observing a transfer pattern using a scanning probe microscope.

[0100] FIG. 6 is a schematic view illustrating an example in which a design is formed by combining a plurality of resin film molds.

[0101] FIG. 7 illustrates the relationship between the radius of curvature and the tensile stress with respect to the thickness of glass.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0102] FIG. 1 illustrates the structure of a replica template (imprint template) according to the invention.

[0103] The replica template includes a resin mold film 1a on which a concave-convex pattern is formed, and a support plate 1c that supports the resin mold film 1a. A transparent buffer resin layer 1b that exhibits flexibility and elasticity is provided between the resin mold film 1a and the support plate 1c.

[0104] The resin mold film 1a is formed using a cyclo-olefin polymer resin (e.g., ZEONOR manufactured by Zeon Corporation) that exhibits excellent transparency with respect to an exposure wavelength used for photocuring imprinting, heat resistance, and the like, for example.

[0105] The film 1a is required to exhibit flexibility, and has a thickness of 20 m to 0.5 mm, and preferably 20 m to 0.2 mm.

[0106] A ZEONOR series manufactured by Zeon Corporation includes films having a thickness of 40 m to 0.18 mm.

[0107] For example, ZEONOR 1060R has a thickness of 0.1 mm, and has the following properties.

[0108] Specifically, ZEONOR 1060R has a specific gravity of 1.01 g/cm.sup.3, a total light transmittance of 92% (thickness: 3 mm), a coefficient of linear expansion of 710.sup.5/ C., a deflection temperature under load of 99 C., a tensile strength of 53 MPa, and a flexural strength of 76 MPa. Note that the total light transmittance is measured by use of parallel and diffuse rays as incident rays, and is defined in JIS K 7375: 2008.

[0109] ZEONOR 1060R exhibits excellent chemical resistance, and is not eroded by acetone, methanol, isopropyl alcohol, and 10% sulfuric acid.

[0110] A PET film having the following properties may also be used as the film la. Specifically, a PET film having a specific gravity of 1.4 g/cm.sup.3, a total light transmittance of 89%, a coefficient of linear expansion of 1.510.sup.5/ C., a deflection temperature under load of 70 to 104 C., a tensile strength of 48 to 73 MPa, and a flexural strength of 96 to 131 MPa, may be used as the film la.

[0111] Such a PET film exhibits excellent chemical resistance with respect to ethanol, isopropyl alcohol, 10% sulfuric acid, and the like.

[0112] The transparent buffer resin layer 1b is an elastic body that is transparent with respect to the photocuring exposure wavelength that is employed during imprint. For example, the transparent buffer resin layer 1b may be formed using a dimethylpolysiloxane (PDMS) resin, an acrylic-based polymer pressure-sensitive adhesive resin, or the like. The transparent buffer resin layer 1b is required to exhibit a buffer capability, and has a thickness of 0.1 to 10 mm, and preferably 0.1 to 0.6 mm.

[0113] For example, a PDMS resin Sylgard 184 (manufactured by Dow Corning Corporation) has the following properties.

[0114] Specifically, Sylgard 184 has a specific gravity of 1.04 g/cm.sup.3, a hardness (JIS Type A) of 44, and a transmittance (380 nm) of 89.8%.

[0115] An acrylic-based polymer pressure-sensitive adhesive resin HRJ-40 (manufactured by Kyoritsu Chemical & Co., Ltd.) has the following properties.

[0116] Specifically, HRJ-40 has a specific gravity of 0.92 g/cm.sup.3, a hardness (JIS Type A) of 17, a modulus of elasticity of 0.6 MPa, and a transmittance (380 nm) of 90% or more.

[0117] The support plate 1c is preferably formed of glass. For example, quartz glass that is transparent with respect to light having a wavelength of 360 nm or more (e.g., D 263 Teco manufactured by Schott) may be used.

[0118] The support plate 1c is required to exhibit flexibility, and has a thickness of 0.1 mm or more and less than 0.5 mm, and preferably 0.1 to 0.25 mm.

[0119] D 263 Teco has the following properties. Specifically, D 263 Teco has a specific gravity of 2.51 g/cm.sup.3, a Young's modulus of 72.9 GPa, and a transmittance (380 nm) of 89.8%.

[0120] Quartz glass has a specific gravity of 2.2 g/cm.sup.3, a Young's modulus of 72 GPa, and a transmittance of 90% or more.

[0121] A resin film mold is normally produced by thermal nanoimprint technology that presses a resin film against a master mold that is produced using silicon or Ni electroforming to transfer the concave-convex pattern onto the resin film.

[0122] Since the thermal nanoimprint technology has an advantage in that the master mold is damaged to only a small extent, and a plurality of resin film molds can be mass-produced using the master mold, it is possible to provide an imprint mold at low cost.

Example of Production Method

[0123] FIG. 2 illustrates a method for producing the replica template according to the invention.

[0124] The steps illustrated in FIG. 2 are described below. [0125] 1. A support plate 2a (e.g., quartz glass) is cleaned by an oxygen plasma treatment. [0126] 2. A PDMS resin primer 2b is applied to the support plate 2a. [0127] 3. A SYLGARD (registered trademark) 184 SILICONE ELASTOMER KIT (PDMS resin 2d) is mixed in a beaker 2c in a weight ratio of 10:1. [0128] 4. Air is removed from the PDMS resin 2d by means of vacuum deaeration. [0129] 5. A weir (barrier) is formed in a peripheral area of the support plate using a rubber plate 2e having a height of 0.5 mm, for example, and the PDMS resin 2d is poured into the area surrounded by the weir. [0130] 6. A squeegee 2f is placed on the rubber weir to spread and smooth the PDMS resin 2d. [0131] 7. After the PDMS resin 2d has been smoothed to have the same height as that of the rubber weir 2e, the PDMS resin 2d is cured on a hot plate at 50 C. for 12 hours or more. [0132] 8. After confirming that the PDMS resin has been cured, the rubber weir is removed. [0133] 9. The back surface of a resin film mold 2g that is situated opposite to the main surface on which a concave-convex pattern is formed, is modified by a plasma treatment (e.g., oxygen plasma treatment).

[0134] The plasma treatment ensures that the back surface of the resin film mold 2g and the PDMS resin 2d exhibit adhesion sufficient to endure the imprinting step. [0135] 10. The back surface of the resin film mold 2g is placed on the PDMS resin 2d, and the resin film mold 2g is carefully bonded to the PDMS resin 2d that is provided on the support plate.

[0136] A hydrophobic release film may be formed on the surface of the resin film mold 2g in order to improve releasability when a pattern is transferred to a resist.

[0137] The hydrophobic release film is a monomolecular fluororesin film, for example. The hydrophobic release film may be formed of heptadecafluoro-1,1,2,2-tetrahydrodecyltrichloro silane (FDTS) or tridecafluoro-1,1,2,2-tetrahydrooctyltrichlorosilane (FOTS), for example.

[0138] The hydrophobic release film can be easily formed by a vapor deposition process or the like.

[0139] The invention is characterized in that the elastic intermediate layer 1b is formed on the support plate 1c that is a flexible support member, and the resin film 1a on which a pattern is formed is bonded to the intermediate layer 1b to provide a replica template that is flexible, has good controllability with respect to the pressurization conditions, and can be easily changed with respect to the transfer pattern.

[0140] According to the invention, since the replica template is flexible, the replica template can be caused to adhere to the substrate while preventing a situation in which air enters the space between the replica template and the substrate, and it is possible to select a release method that reduces the release force.

[0141] For example, it is possible to gradually bring the template into contact with the substrate from the edge of the substrate while controlling the speed and the pressure, and gradually remove the template from the substrate after exposure from the edge of the substrate while controlling the speed and the like.

[0142] It is also possible to allow the flexible replica template to follow the surface of the substrate even when the substrate is curved (warped).

[0143] This makes it possible to reduce the pressure to be applied, and reduce the amount of damage applied to the substrate and the pattern.

[0144] Since the replica template according to the invention is flexible, but exhibits uniform in-plane rigidity, the replica template is not affected by a variation in stress due to a variation in the size and the density of the concave-convex pattern that is formed on the main surface of the resin film mold.

[0145] Even when the surface of the resin film on which the pattern is formed has been contaminated by the resist or the like, it is possible to clean the surface of the resin film using a cleaning agent such as an organic solvent. Therefore, it suffices to replace only the resin film when the lifetime of the pattern layer has been reached.

[0146] It is possible to easily form the resin pattern layer as compared with the case of forming a coating-type resin pattern layer, reduce the replacement time, prevent a defect when forming the resin pattern layer, and obtain a stable mold pattern having a small lot-to-lot variation in shape.

[0147] Since the pattern is formed by the resin film mold that can be easily removed and bonded, it is possible to automate the film removal-bonding step and the cleaning step.

[0148] FIG. 3 illustrates a method for forming a nanopillar structure that utilizes a nanoimprint template that is produced according to the invention. [0149] 1. A nanoimprint resist 3b (XIP-3K6P manufactured by Kyoritsu Chemical & Co., Ltd.) is applied to a sapphire substrate 3a to a thickness of 100 to 200 nm using a spin coating method. [0150] 2. A replica template 3c produced according to the invention is placed at a distance of about 100 m from the surface of the nanoimprint resist 3b so as not to come in contact with the surface of the nanoimprint resist 3b. [0151] 3. The concave-convex pattern (back side) of the replica template 3c is slowly pressed against the resist 3b (from the left side in FIG. 3) by applying air pressure. [0152] 4. When the entire template has been pressed against the resist 3b, the resin is cured by applying broadband light from a high-pressure mercury lamp. [0153] 5. The replica template 3c is slowly removed (from the right side in FIG. 3) from the resist 3d onto which the pattern has been transferred. [0154] 6. The concave-convex pattern of the replica template is thus transferred onto the surface of the substrate by means of the resist 3d.

[0155] FIG. 4 illustrates the replica template used to form the nanopillar structure.

[0156] The concave-convex pattern is formed in the center circular area. The concave-convex pattern had the dimensions shown in Table 1.

TABLE-US-00001 TABLE 1 Area of pattern Diameter of pillar Height of pillar Pillar pitch 120 mm (diameter) 230 nm 200 nm 460 nm
An imprint experiment in which the pattern was imprinted on a 4-inch (diameter of 100 mm) sapphire substrate using the replica template was performed.

[0157] The imprint experiment was performed using a device MA6 SCIL (manufactured by Suss MicroTec).

[0158] FIG. 5 illustrates the pattern transferred onto the resist (observed using a scanning probe microscope (SPM)).

[0159] It was confirmed that the concave-convex pattern of the replica template was accurately transferred with respect to the shape and the dimensions. FIG. 6 illustrates a method for decorating a substrate that utilizes a nanoimprint template that is produced according to the invention.

[0160] The invention is characterized in that the replica template has a structure in which the resin film mold is bonded to the buffer resin layer.

[0161] According to this feature, the type of the resin film mold that is bonded to the buffer resin layer can be arbitrarily selected. It is also possible to bond a plurality of different patterns at arbitrary positions by combining a plurality of resin film molds (e.g., screen tone), and implement decoration that utilizes a structural color derived from the nano structure.

[0162] For example, it is possible to implement a design (e.g., illustration) by providing the patterns 6a and 6b illustrated in FIG. 6.

[0163] According to related-art technology, it is necessary to provide a master mold that has the desired design. According to the invention, however, it is possible to easily produce a replica template having an arbitrary design without requiring a considerable capital investment, by providing several screentones using an existing resin film mold.

[0164] It is also possible to easily implement automated nanostructure decoration technology by utilizing CAD or a cutting plotter.

[0165] The imprint template according to the invention is mainly useful for UV nanoimprint technology. but may also be appropriately applied to soft lithography (e.g., thermal nanoimprinting and contact printing).

[0166] The imprint template according to the invention may be used to produce a large-capacity recording disc, a semiconductor device, a bio device (e.g., biosensor and fluidic device), an optical device, and the like, and may also be used to implement decoration technology.

[0167] Although only some embodiments of the present invention have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within scope of this invention.