JP5002174B2 - Pattern forming method and mold manufacturing method - Google Patents

Description

  The present invention relates to a method for producing a microstructure that can be used as a mold for nanoimprinting.

  A nanoimprint method for producing a fine structure is known. However, in the nanoimprint method, a concave-convex mold corresponding to a structure to be manufactured is manufactured, and a concave-convex pattern is formed on the substrate surface using the mold. Therefore, it is necessary to create a reverse pattern having a desired structure as a mold.

On the other hand, an ink pattern forming method has been proposed in which a stretchable substrate is used, a printing ink pattern is formed on the surface, the substrate is stretched or contracted, and the pattern is transferred to the substrate to be printed (Patent Document 1). If this method is used, it is possible to further miniaturize a structure formed by lithography or the like.
Japanese Patent No. 30499947

  However, in the process of reducing the pattern by using a stretchable material as the substrate and reducing the substrate after forming the pattern on the substrate surface, the substrate is easily deformed when the substrate is fixed with a jig because of the expansion and contraction. Accordingly, when the substrate is pulled and stretched, if it is controlled by the pulling force or the stretch amount, it is difficult to detect the stretch amount of the substrate from before the substrate is fixed. For this reason, when the substrate is shrunk after the pattern is formed on the stretched substrate surface, the pattern formed on the substrate surface is distorted, and it is difficult to obtain a desired pattern.

  Therefore, an object of the present invention is to provide a method for accurately forming a desired pattern and a method for producing a mold using the method.

Accordingly, the present invention provides a pattern forming method using a stretchable substrate, the step of forming a pattern on the surface of the substrate in a state in which the substrate is stretched, and a displacement amount detection provided on the substrate. based on the detection result of the mark, there is provided a pattern forming method characterized by a step of controlling the amount of stretching of the substrate on which the pattern is formed.

  According to the present invention, even if the substrate is deformed when the substrate is fixed, the amount of distortion of the reduced pattern obtained by contraction of the substrate after pattern formation can be reduced.

The present invention will be described more specifically below.
First, a pattern forming method will be described. As the stretchable substrate, a material having a low elastic modulus of 1 to 20 MPa and rubber elasticity is suitable. It is preferable to stretch the substrate within the range of elastic deformation. However, the present invention is not limited to this, and any material may be used as long as the surface area is reduced by pressurization, a material that is reduced in area by heating, such as a heat-shrink film, or a material that is reduced in area by UV irradiation. May be used.

  The stretchable substrate is stretched by fixing a part of the substrate to a stretching apparatus or jig. The extending direction may be short axis or multi-axis. As the displacement detection mark formed on the stretchable substrate, a concave-convex structure formed on the substrate surface or a cavity inside the substrate such as a bubble can be used. Further, a light shielding material formed on the substrate surface or inside the substrate can be used as a displacement detection mark. It is also possible to use a translucent material or a reflective material as the light shielding material. A magnetic material can also be used.

  The displacement detection mark can detect the mark position by irradiating the mark with light, ions, electrons, and X-rays and observing the reflected or transmitted light. When a magnetic material is used as the displacement detection mark, the mark position can be detected using a probe whose surface is coated with a magnetic material. Further, when a diffraction grating is used as the displacement amount detection mark, a change in pitch of the diffraction grating due to stretching / reduction can be detected from the intensity distribution of the diffracted light. By forming the diffraction grating for each extending direction of the substrate, it can be used as a displacement detection mark even when extending in the multiaxial direction.

  An external force is applied to the elastic member (from a state in which an external force such as tension or compression is not applied) to make it deform. For example, the elastic member is pulled to a stretched state. At that time, a predetermined pattern is formed on the member itself or on the member. For example, a recess or a groove is formed directly on the outer member, or a pattern is formed on the member by film formation. Simultaneously with the formation of the pattern, the position of the member is recognized using the pattern itself or a position detection mark provided on the member. Thereafter, the applied external force is released or loosened to return the deformed state of the member to the state before deformation or a state close thereto.

  At that time, by using the detection mark or a plurality of detection marks, the return of deformation can be controlled while using the mark from the time of pattern formation until the member is returned to the state before deformation. Can do. For example, when a predetermined pattern is formed in a state where a strain is applied in the in-plane direction, the strain can be reduced isotropically while maintaining the strain in the in-plane direction. This means that the pattern can be reduced isotropically. Once a large pattern is created, a technique that can be reduced isotropically is important. Note that it is preferable to harden the member including the pattern after isotropic reduction.

[Example 1]
In the present invention, a silicon rubber sheet of 0.6 mm thickness and 100 mm square is used as the substrate. As shown in FIG. 1A, after forming copper to a thickness of 100 nm on a silicon rubber substrate by sputtering, circular copper patterns with a diameter of 5 μm are formed at the four corners of the substrate by photolithography and etching to form displacement detection marks. . Thereafter, a photosensitive material made of liquid rubber is formed on a silicon rubber sheet substrate by spin coating to have a thickness of 5 μm, the four corners of the substrate are clamped, and the substrate is stretched in the same plane (FIG. 1B). As the photosensitive material made of liquid rubber, for example, WL-5351 manufactured by Toray Dow Corning Co., Ltd. can be used. When stretching, the copper pattern formed at the four corners of the substrate is read from the back side of the processed surface of the substrate with a camera, and the substrate is stretched while controlling the relative position of the center of gravity of the mark. Shall. In order to increase the magnification to 1.5 times, the substrate is stretched so that the relative distance between the copper patterns is 1.5 times as much as before stretching. After fixing the substrate during stretching, a 5 mm square nickel mold formed on the surface of a slit pattern having a width of 150 nm and a height of 100 nm at a pitch of 300 nm is pressed against the liquid rubber layer. The liquid rubber layer is UV cured by irradiating with UV light (FIG. 1C). After curing, the mold is released to reduce the substrate. As a result, a microstructure having a concavo-convex pattern having a pitch of 200 nm and a width of 100 nm is formed on the substrate surface (FIG. 1D). After sputtering 200 nm of nickel on the concavo-convex pattern, electrolytic nickel plating is applied to a thickness of 50 μm by night of nickel flufamate plating. By peeling the nickel film from the silicon rubber, a nickel microstructure having a width of 100 nm is obtained at a pitch of 200 nm, which can be used as a mold.

[Example 2]
In the present invention, a thermoplastic elastomer molded into a 100 mm square with a thickness of 0.6 mm is used as the substrate. As the thermoplastic elastomer, for example, Quintac manufactured by Nippon Zeon, which is a copolymer of styrene-isoprene, can be used. For pattern formation, cylindrical projections with a diameter of 100 nm and a height of 100 nm arranged in a triangular lattice pattern at a pitch of 200 nm are formed in a 5 mm square area, and the apex of a square with a side of 20 mm is 10 μm in height and 10 μm in diameter. A Si mold having a protruding pattern is used. As shown in FIG. 2, after heating the Si mold to 100 ° C., the Si mold is pressed and released from a thermoplastic elastomer substrate stretched by 3 times. As a result, a concave pattern with a diameter of 100 nm is formed in a 5 mm square area on the substrate surface at a pitch of 200 nm but is formed in a square area with a side of 20 mm and a depth of 10 μm and a diameter of 10 μm. A concave pattern is formed. Thereafter, a concave pattern having a depth of 10 μm and a diameter of 10 μm is used as a displacement amount detection mark. When the substrate is reduced, the displacement amount detection mark is read by a camera, the position of the center of gravity of the concave pattern is detected, and the substrate stretching amount is controlled so that one side becomes a 10 mm square. At this time, the magnification of the substrate is reduced from about 3 times to about 1.5 times. Thereby, a fine structure composed of circular concave patterns arranged in a triangular lattice pattern at a pitch of 100 nm on the substrate surface is obtained.

  After sputtering nickel with a thickness of 200 nm on the circular concave pattern, electrolytic nickel plating is applied to a thickness of 50 μm by night of nickel flufamate plating. By peeling the silicon rubber, a fine structure composed of cylindrical patterns arranged in a triangular lattice pattern at a pitch of 100 nm can be obtained, and this can be used as a mold.

[Example 3]
In the present invention, a silicon rubber sheet of 0.6 mm thickness and 100 mm square is used as the substrate. After forming 20 nm thick cobalt on a silicon rubber substrate by sputtering, a cylindrical cobalt pattern having a diameter of 200 nm is formed at the four corners of the substrate by photolithography and etching to form a displacement detection mark. When the substrate is stretched, the displacement detection mark made of cobalt is read with a magnetic probe whose surface is coated with permalloy, and the relative position between the displacement detection marks is detected. Therefore, a fine structure can be formed on the silicon rubber sheet by the same method as in the first embodiment.

[Example 4]
In the present invention, a silicon rubber sheet of 0.6 mm thickness and 100 mm square is used as the substrate. The silicon rubber sheet is manufactured using liquid silicon rubber, and the silicon rubber sheet is thermally cured on a silicon wafer in which grooves are partially formed by dry etching, as shown in FIG. A diffraction grating is formed in part. As the liquid silicone rubber, for example, Sylguard 184 manufactured by Toray Dow Corning Co., Ltd. can be used. By stretching the substrate while irradiating the diffraction grating in the silicon rubber with light, it is possible to measure the amount of stretching of the substrate. A liquid silicon rubber is cured on a silicon wafer on which 1 μm pitch grooves are formed, and the silicon rubber is released from the silicon wafer to obtain a 1 μm pitch diffraction grating. When diffracted light is detected by irradiating light with a wavelength of 300 nm to 750 nm from the direction perpendicular to the substrate, the peak wavelength at which the intensity of the diffracted light at 30 ° with respect to the incident direction is maximum is 350 nm before stretching. It can be seen that the silicon rubber substrate on which the diffraction grating is formed by extending the diffracted light to 700 nm is stretched at a magnification of 2 times. A groove pattern with a pitch of 50 nm is obtained by forming a groove pattern with a pitch of 100 nm on the surface of the substrate by FIB in the direction perpendicular to the stretching direction during stretching, and reducing the substrate.

Explanatory drawing of one Embodiment of this invention Explanatory drawing of one Embodiment of this invention Explanatory drawing of one Embodiment of this invention

Claims (5)

A pattern forming method using a stretchable substrate ,
Forming a pattern on the surface of the substrate in a stretched state of the substrate;
Based on the displacement amount detection mark detection result provided in the substrate, a pattern forming method characterized by a step of controlling the amount of stretching of the substrate on which the pattern is formed. In the step of controlling the amount of stretching of the substrate,
The pattern forming method according to claim 1, wherein an extension amount of the substrate is controlled so that a pattern formed on the surface of the substrate is isotropically reduced. In the step of forming a pattern on a surface of the substrate, the pattern forming method according to claim 1 or 2, Features that you form a mark for simultaneously the displacement amount detection pattern formation. Claim 1 wherein the displacement amount detection mark is characterized that you detect the intensity distribution of the Ri Oh diffraction grating formed by the unevenness of the substrate, the diffracted light the pitch change of the diffraction grating due to the reduction of the substrate 4. The pattern forming method according to any one of items 1 to 3 . Forming a pattern on a substrate by the pattern forming method according to any one of claims 1 to 4,
Forming a metal film on the patterned surface,
Method for producing a metal mold, characterized in Rukoto which have a and Cheng Hao you separated from the substrate and the metal film.

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