The present invention relates to an apparatus and a method of step-and-repeat imprinting.
The imprinting technique is a micromachining technique in which a mold having a convex and concave pattern is pressed against a transfer material, such as a liquid resin, on a base, thereby transferring the mold pattern to the transfer material. Such a convex and concave micropattern ranges from patterns at the nanoscale, such as those at the 10 nm level, to patterns at approximately 100 μm. Such a technique is used in various fields, such as semiconductor materials, optical materials, recording media, micromachines, biotechnology, and environmental technology.
Molds having a convex and concave micropattern of nano order on a surface are very expensive because it takes time to form the pattern. Such molds having a convex and concave micropattern of nano order on a surface are thus difficult to be formed in a larger size (larger area).
PTL 1 enables imprinting in a large area by repeated imprinting using a small mold while moving the position of the mold not to overlap processing regions (step-and-repeat).
PTL 1: Japanese Patent No. 4262271
In the method of PTL 1, a procedure of exposing a transfer material to light while a convex and concave pattern of a mold is vertically pressed against the transfer material for curing to form a cured resin layer having a reverse pattern formed by reversing the convex and concave pattern and then vertically removing the mold from the cured resin layer is repeated.
In the method of PTL 1, when the mold is pressed against the transfer material, air is sometimes sandwiched between them, causing the convex and concave pattern not to be appropriately transferred. High pressure press for removal of air may cause the mold or the base to break. When the mold is removed after formation of the cured resin layer, the reverse pattern formed in the cured resin layer may be damaged. Further, flatness and parallelism of the upper and lower surfaces of the stage to place the base for application of the transfer material greatly affect the transfer accuracy. These problems become severer with an increase in size of the mold.
The present invention has been made in view of such circumstances and is to provide a step-and-repeat imprinting apparatus that is capable of restraining imprinting failures and mold breakage.
According to the present invention a step-and-repeat imprinting apparatus is provided that includes: a stage to place a stage base; a positioning mechanism configured to be relatively movable to the stage and to keep a flexible base to face the stage base; and a pressurizing mechanism to press, while deflecting the flexible base, the flexible base toward the stage base, wherein one of the stage base and the flexible base has a convex and concave pattern, and another of the stage base and the flexible base includes a transferred resin layer to have the convex and concave pattern transferred thereto, and the apparatus is so configured that the pressurizing mechanism presses, while deflecting, the flexible base toward the stage base, thereby transferring the convex and concave pattern to the transferred resin layer.
In the present invention, the convex and concave pattern is transferred by pressing, while deflecting, the flexible base kept by the positioning mechanism relatively movable to the stage against the stage base placed on the stage. Such a configuration facilitates removal of air between the flexible base and the stage base and facilitates separation of them after transfer. Compared with the method of PTL 1, the influence of flatness and parallelism of the upper and lower surfaces is less. Such a configuration facilitates an increase the size of the mold.
Various embodiments of the present invention are disclosed below as examples. The following embodiments may be combined with each other.
Preferably, the pressurizing mechanism is configured to be movable on the flexible base.
Preferably, the positioning mechanism is configured to be movable approximately vertically to a direction of movement of the pressurizing mechanism.
Preferably, the positioning mechanism configured to be movable in a direction approximately identical to a direction of movement of the pressurizing mechanism.
Preferably, the positioning mechanism performs positioning using a fixing mark provided on the stage and a movement mark provided in the positioning mechanism.
Preferably, the fixing mark is multiple squares provided on the stage.
According to another aspect of the present invention, a step-and-repeat imprinting method is provided that includes: transferring, while facing a stage base placed on a stage to a flexible base kept relatively movable to the stage, a convex and concave pattern provided in one of the stage base and the flexible base to a transferred resin layer provided in another of the stage base and the flexible base by pressing the flexible base toward the stage base while deflecting the flexible base; and repeating to perform the transferring step by moving the flexible base.
Preferably, the flexible base is pressed toward the stage base by moving a pressurizing mechanism on the flexible base.
Preferably, the repeating includes moving the flexible base approximately vertically to a direction of movement of the pressurizing mechanism, and performing the transferring.
Preferably, the repeating includes moving the flexible base in a direction approximately identical to a direction of movement of the pressurizing mechanism, and performing the transferring.
Preferred embodiments of the present invention are specifically described below with reference to the drawings.
As illustrated in
In the present embodiment, a partial region of the flexible base 9 is provided with a convex and concave pattern 10, and the stage base 3 is formed with a transferred resin layer 11 to have the convex and concave pattern 10 transferred thereto. Then, the pressurizing mechanism 7 is configured to press, while deflecting, the flexible base 9 toward the stage base 3, thereby transferring the convex and concave pattern 10 to the transferred resin layer 11. Accordingly, the flexible base 9 having the convex and concave pattern 10 functions as an imprinting mold.
More specifically, the positioning mechanism 5 includes a rear end holding unit 15 to keep a rear end side of the flexible base 9 and a front end holding unit 25 to keep a front end side of the flexible base 9. The rear end holding unit 15 includes a longitudinal driving unit 15a configured to be movable in a longitudinal direction of the stage 1 and a transverse driving unit 15b supported by the longitudinal driving unit 15a and configured to be movable in a transverse direction of the stage 1. The front end holding unit 25 includes a longitudinal driving unit 25a configured to be movable in the longitudinal direction of the stage 1, a transverse driving unit 25b supported by the longitudinal driving unit 25a and configured to be movable in the transverse direction of the stage 1, and a vertical driving unit 25c supported by the transverse driving unit 25b and configured to be movable in a vertical direction of the stage 1. The rear end side of the flexible base 9 is two dimensionally movable over the stage 1 by being supported by the transverse driving unit 15b. The front end side of the flexible base 9 is three dimensionally movable over the stage 1 by being supported by the vertical driving unit 25c. The configuration of the positioning mechanism 5 is not limited to those described here and various configurations are applicable. For example, the rear end holding unit 15 may be provided with a vertical driving unit to support the rear end side of the flexible base 9 by the vertical driving unit. In this case, the rear end side of the flexible base 9 also becomes three dimensionally movable over the stage 1 and thus the gap between the flexible base 9 and the stage base 3 is more readily adjusted. For step-and-repeat only in the transverse direction, the longitudinal driving units 15a and 25a do not have to be provided.
The pressurizing mechanism 7 is configured with a column roller 7b rotatable on the rotation shaft 7a. The rotation shaft 7a is supported by bearings of a support mechanism, not shown, movable in the longitudinal direction of the stage 1. Such a configuration causes the roller 7b to move on the flexible base 9 while rotating on the flexible base 9, thereby enabling pressing of the flexible base 9 against the stage base 3. The pressurizing mechanism 7 only has to press, while deflecting, the flexible base 9 toward the stage base 3, and thus the roller 7b does not have to rotate. The pressurizing mechanism 7 may be configured to move a blade in a plate shape instead of the roller 7b. Moreover, the pressurizing mechanism 7 may be configured to press, while deflecting, the flexible base 9 without moving. Further, if the pressurizing mechanism 7 presses, while deflecting, the flexible base 9 using a gas, such as air, toward the stage base 3, it does not have to contact the flexible base 9 with the pressurizing mechanism 7.
Here, using the imprinting apparatus in the present embodiment, a method of step-and-repeat imprinting is described.
First, as illustrated in
The stage base 3 may or may not be flexible and may or may not be transparent. To the stage base 3, various bases such as resin bases, quartz bases, silicone bases, and silicon bases are applicable.
The transferred resin layer 11 is formed by applying a photocurable resin composition on the stage base 3. Such a photocurable resin composition contains a monomer and a photoinitiator and has properties to be cured by irradiation with an activation energy line. “The activation energy line” is the generic name for energy lines capable of curing a photocurable resin composition, such as UV light, visible light, and electron beams. The transferred resin layer 11 is generally a transparent resin layer and generally has a thickness from 50 nm to 1 mm and preferably from 500 nm to 500 μm. A thickness in this range facilitates imprinting. In the present embodiment, every time imprinting is performed, a transferred resin layer 11 is formed in a region for the next imprinting. That is, imprinting and formation of the transferred resin layer 11 is alternately performed. The method is not limited to this embodiment, and the transferred resin layer 11 may be formed in the entire region for imprinting at first or the transferred resin layer 11 may be formed at once in a region equivalent to a plurality of imprinting procedures to reduce the number of the transferred resin layer 11 formation steps.
The flexible base 9 is a base has flexibility. The transferred resin layer 11 is generally irradiated with activation energy lines 27 (see
The convex and concave pattern 10 is formed on a resin layer formed by applying a thermoplastic resin, a thermosetting resin, or a photocurable resin on the flexible base 9. The resin to be applied is preferably a photocurable resin. Specific examples include an acrylic resin, a styrene resin, an olefin resin, a polycarbonate resin, a polyester resin, an epoxy resin, a silicone resin, and the like. The resin may contain a peeling component, such as a fluorine compound, a long chain alkyl compound, and wax. The convex and concave pattern 10 is not particularly limited, and preferably has intervals from 10 nm to 2 mm, a depth from 10 nm to 500 μm, and a transfer surface from 1.0 to 1.0×106 mm2, and more preferably intervals from 20 nm to 20 μm, a depth from 50 nm to 1 μm, and a transfer surface from 1.0 to 0.25×106 mm2. Such settings enable sufficient transfer of the convex and concave pattern 10 to a transfer body. Examples of the surface shape include moth eye patterns, lines, columns, monoliths, cones, polygonal pyramids, and microlens arrays.
Next, the positioning mechanism 5 and the pressurizing mechanism 7 are moved to the positions illustrated in
Then, from the state in
Then, as illustrated in
Then, if the pressurizing mechanism 7 is over the transferred resin layer 11, the pressurizing mechanism 7 is put back in a position close to the rear end holding unit 15 to raise the vertical driving unit 25c, thereby peeling the convex and concave pattern 10 from the cured resin layer 29. At this point, while the flexible base 9 is deflected, the peeling gradually proceeds from an end of the convex and concave pattern 10. The force for peeling is thus relatively small and a risk of damaging the convex and concave pattern 10 and the reverse pattern 10r is reduced.
Then, as illustrated in
After completion of step-and-repeat in the transverse direction, as illustrated in
By repeating the above procedure, a microstructure formed with the reverse pattern 10r of a desired area on the stage base 3 is formed. Such a microstructure is applicable to imprinting molds, stampers for microcontact printing, optical sheets (antireflective sheets, hologram sheets, lens sheets, and polarization separation sheets), water repellent sheets, hydrophilic sheets, cell culture sheets, and the like.
The order of step-and-repeat is not particularly limited and examples of the order include the order of A, B, C, D, E, and F in
In the first embodiment, the flexible base 9 is provided with the convex and concave pattern 10, and the stage base 3 is provided with the transferred resin layer 11. In the present embodiment, as illustrated in
The imprinting apparatus in the present embodiment has the same basic configuration as that in the first embodiment, and the descriptions in common are omitted. In the present embodiment, a micropattern in a large area is formed in the flexible base 9 by step-and-repeat imprinting, so that the flexible base 9 has to be larger than that in the first embodiment. In proportion to the increase in size of the flexible base 9, the transverse driving unit 15b and the vertical driving unit 25c, keeping the base 9, are made larger. As illustrated in
Here, a method of step-and-repeat imprinting using the imprinting apparatus in the present embodiment is described.
First, as illustrated in
Next, the positioning mechanism 5 and the pressurizing mechanism 7 are moved in a position illustrated in
Then, from the state in
Then, as illustrated in
Then, if the pressurizing mechanism 7 is over the transferred resin layer 11, the pressurizing mechanism 7 is put back in a position close to the rear end holding unit 15 to raise the vertical driving unit 25c, thereby peeling the convex and concave pattern 10 from the cured resin layer 29. At this point, while the flexible base 9 is deflected, the peeling gradually proceeds from an end of the convex and concave pattern 10. The force for peeling is thus relatively small and a risk of damaging the convex and concave pattern 10 and the reverse pattern 10r is reduced.
Then, as illustrated in
After completion of step-and-repeat in the transverse direction, as illustrated in
In the first and second embodiments, the position accuracy for movement of each driving unit of the rear end holding unit 15 and the front end holding unit 25 is dependent on the accuracy of a driving mechanism, such as screw feeding, whereas there is a problem that driving mechanisms with high accuracy are very expensive. The present embodiment is characterized by enabling high accuracy positioning relatively inexpensively. The present embodiment is applicable to the first and second embodiments and the descriptions in common are not repeated. Further,
In the present embodiment, a precision scale 41 is placed on the stage 1. On the precision scale 41, multiple squares 43 are drawn with high accuracy of dimension. The stage base 3 in the first and second embodiments is placed on the precision scale 41. A transparent base is used as the stage base 3, and the squares 43 are observable through the stage base 3. The squares 43 are immobile during the positioning of the positioning mechanism 5 and function as the “fixing mark” in the scope of claims.
The longitudinal driving unit 15a of the front end holding unit 15 has approximately both ends provided with transparent plates 31a and 31b having marks 33a and 33b. The marks 33a and 33b are marks that are moved during positioning of the positioning mechanism 5 and function as the “movement mark” in the scope of claims.
The stage 1 is provided with an imaging mechanism 35. The imaging mechanism 35 includes a longitudinal driving unit 35a. The longitudinal driving unit 35a includes imaging units 37a and 37b supported by supporting units 39a and 39b. The imaging units 37a and 37b are configured with a microscope and the like.
Then, a method of positioning with high accuracy using the squares 43 and the marks 33a and 33b is described. Here, positioning of the longitudinal driving unit 15a is described in detail while the same method is applicable to other driving units.
First, the longitudinal driving unit 15a is moved to a desired position in the longitudinal direction of the stage 1.
Next, the longitudinal driving unit 35a is moved to position the imaging units 37a and 37b right above the marks 33a and 33b, and the marks 33a and 33b and the squares 43 are imaged from right above the marks 33a and 33b.
Then, as illustrated in
Then, as illustrated in
1: Stage, 3: Stage Base, 5: A Positioning Mechanism, 7: Pressurizing Mechanism, 9: Flexible Base, 10: Convex and Concave Pattern, 10r: Reverse Pattern, 11: Transferred Resin Layer, 15: Rear End Holding Unit, 25: Front End Holding Unit, 29: Cured Resin Layer, 35: Imaging Mechanism
Number | Date | Country | Kind |
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2014-147211 | Jul 2014 | JP | national |
Filing Document | Filing Date | Country | Kind |
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PCT/JP2015/070365 | 7/16/2015 | WO | 00 |