This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2008-087763, filed Mar. 28, 2008, the entire contents of which are incorporated herein by reference.
1. Field
One embodiment of the present invention relates to an imprinting method, and more particularly, to an imprinting method applied to the manufacture of a discrete track recording magnetic recording medium. Further, the present invention relates to a stamper used for the imprinting method.
2. Description of the Related Art
In recent years, in a manufacturing process of a semiconductor element or an information recording medium, formation of patterns microstructured to a nanometer size is required. As a method of forming a microstructure on a substrate, lithography such as ArF liquid immersion lithography and EUV lithography, and nanoimprint are proposed. The nanoimprint is a technique for transcribing micropatterns by pressing a stamper on which desired protruded patterns are formed against a resist applied to a substrate. Accordingly, nanoimprint is studied as a method advantageous in terms of cost and throughput to transcribe micropatterns on a large area.
As one of recording media requiring micropatterning as described above, there is known a discrete track recording magnetic recording medium (DTR medium).
Imprinting used in manufacturing a DTR medium will be described below. First, a resist is applied to both sides of a substrate. The substrate includes a glass substrate, a metallic substrate such as Si, a carbon substrate, and a resin substrate. The resist includes a thermosetting resin, an UV-curable resin, and a sol-gel material. The resist is applied by various methods such as the spin coating, dip coating, and an inkjet method. A thickness of the resist is set at 1 μm or less, and more preferably several hundred nm or less.
On the other hand, a stamper is prepared on a surface of which protruded micropatterns are formed. The material for the stamper includes Ni, Si, glass, quartz, and resin. On a stamper used for manufacturing, for example, a DTR medium, patterns corresponding to the recording tracks are formed with a track pitch of 100 nm or less.
Subsequently, each of protruded pattern surfaces of two stampers is opposed to the resist applied to each of both sides of the substrate from above and below, and is pressed against the resist, thereby transcribing the patterns of each of the stampers onto the resist. This step is performed in the following manner in accordance with the type of the resist. When the thermosetting resin is used as the resist, the stamper is pressed against the resist in a heated state, and then the resist is cooled, thereby transcribing the microstructures. When the UV-curable resin is used as the resist, in a state where the stamper is pressed against the resist, the resist is irradiated with UV-light through a transparent substrate, thereby transcribing the microstructures. When the sol-gel material is used as the resist, the microstructures are transcribed by pressing the stamper against the resist under high pressure. In this way, a structure formed by pressing the two stampers against both sides of the substrate with the resist layers sandwiched is obtained.
In order to form protruded patterns to be used as masks on the substrate, it is necessary to peel off the stamper from the resist. However, since the thickness of the resist is as thin as 1 μm or less, and the stampers are pressed against both sides of the substrate, it is difficult to peel off the stampers.
Conventionally, in order to manufacture an optical disk such as a DVD, a device and a method for peeling a dummy disk or a stamper from a substrate have been developed (see Jpn. Pat. Appln. KOKAI Publication No. 2001-52378, and Jpn. Pat. Appln. KOKAI Publication No. 2007-118552). In the case of manufacturing an optical disk, a gap between the substrate and the dummy disk or the stamper is about several μm, and the dummy disk or the stamper has only to be peeled off from only one surface of the substrate, and hence the work can be performed with relative ease.
However, it is difficult to apply the conventional device to the operation for peeling stampers from both sides of the substrate under the conditions that the resist between the substrate and the stampers have a small thickness of 1 μm or less as in the case of manufacturing a DTR medium.
A general architecture that implements the various feature of the invention will now be described with reference to the drawings. The drawings and the associated descriptions are provided to illustrate embodiments of the invention and not to limit the scope of the invention.
Various embodiments of the invention will be described hereinafter with reference to the accompanying drawings. In general, according to one embodiment of the invention, there is provided an imprinting method comprising; applying a resist to a substrate; imprinting a stamper on which protruded patterns are formed against the resist applied to the substrate; forcing a distal end of a peeling wedge into a part between the substrate and the stamper; and introducing a gas between the substrate and the stamper to peel off the stamper from the substrate, wherein a gap between the substrate and the stamper is made larger than a thickness of the resist at a part into which the distal end of the peeling wedge is forced.
In the following embodiments, a case where an annular substrate and annular stampers are used, and a peeling wedge is arranged in the central hole, and the substrate and the stamper are peeled from each other in the inner periphery will be described.
In a first embodiment, a stamper on which a step is provided by making a thickness of the inner periphery thinner than the other part is used.
With reference to
This structure is set on the peeling device, and the lower part and the upper part of the inner periphery of the structure are held with vacuum chucks 51 and 52. In this state, the peeling wedge 60 is arranged in the central hole of the structure, and the peeling wedge is positioned in such a manner that a distal end of the peeling wedge is positioned at a height between the substrate 10 and the upper stamper 30. As shown in
A method of peeling the stampers from the substrate will be described below with reference to
As shown in
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In this way, as shown in
It should be noted that the peeling wedge 60 may be forced into the imprinted structure from the outer periphery of the structure to peel off the stamper 30. In this case too, in the step corresponding to
Peeling the stampers was tried for comparison under the same conditions as in
In a second embodiment, a thickness of a resist to be applied to a substrate is made larger only in an inner periphery of the substrate. By adjusting the condition of spin coating, a thickness of the resist applied to the substrate can be made larger only in a part thereof.
As shown in
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In this way, as shown in
It should be noted that in the present invention, it may be made easier to force the distal end of the peeling wedge 60 into the gap between the substrate 10 and each of the stampers 30 by warping the inner periphery of each of the upper and lower stampers upwardly or downwardly.
As described above, by using the method of the present invention, it is possible to peel off the stampers from the imprinted structure, and uniformly transcribe micropatterns onto both sides of the substrate. The method of the present invention is not limited to the case where the substrate and the stampers having the annular shape are used, and can be applied to a substrate and stampers having any shape.
Next, a method of manufacturing a DTR medium using the imprinting method will be schematically described below with reference to
As shown in
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As shown in
Then, a carbon protective film is deposited, and a lubricant is applied to manufacture a DTR medium.
While certain embodiments of the inventions have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.
Number | Date | Country | Kind |
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2008-087763 | Mar 2008 | JP | national |