JP2016192519A - Replica mold and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a replica mold capable of preventing a defect (transfer defective region) of a microstructure transferred to a mask material by entrainment of air bubbles or the like during contact of a transferred body and the replica mold via the mask material without requiring a complicated transfer device, and a manufacturing method thereof.SOLUTION: A replica mold 101 is formed from a soft material 103 and has the microstructure on a surface. A surface having the microstructure is curved so as to be projected by a residual stress. In the case where the replica mold is supported by jigs 104a and 104b including openings that are fixed horizontally, in addition to curvature X caused by the residual stress of the replica mold 101 itself, deadweight deflection W is generated that is deflection caused by a deadweight. A sum of the curvature X caused by the residual stress and the deadweight deflection W is from 2.0% to 6.0% with respect to a diameter of the opening.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a nanoimprint replica mold.

  The microfabrication technology based on the nanoimprint method is used for optical and lighting applications such as high-precision semiconductor integrated circuits, imparting anti-reflection properties, and improving the light extraction efficiency of LED substrates, and developing energy for secondary batteries, solar cells, and fuel cells. Introduction is being considered in a wide range of fields such as biotechnology.

  In a conventional nanoimprint method, there is a method for forming a mold by forming a fine structure on a substrate such as Si or quartz by a photolithography method, but there is a problem that the manufacturing cost is very high.

  In recent years, the nanoimprint method has attracted attention as an inexpensive fine structure forming technique that replaces a photolithographic technique with a high manufacturing cost. Therefore, a mold formed by a photolithography method or the like is used as a master mold, a fine structure on the surface of the master mold is transferred to a material such as a resin by a nanoimprint method, and the material such as the resin is used as a replica mold. It has been broken.

  The nanoimprint method will be described in detail. A mold (master mold) having a microstructure is formed, a replica mold is formed by transferring the microstructure from the master mold, and the microstructure is formed using the replica mold as a stamper. It prints on the transfer medium. As a method for printing the microstructure of the replica mold on the transfer object, the transfer object on which the photocurable resin is laminated as a mask material is pressed with a replica mold as a stamper, so that the fine structure is applied to the laminated photocurable resin. Transcript. In this state, the photo-curing resin is cured by irradiating light such as ultraviolet rays. Patterning is performed on the transfer object by a method such as etching using the cured photo-curing resin as a mask.

  Conventionally, in the nanoimprint method, a flat replica mold is pressed against a flat transfer target on which a mask material is laminated, and the mask material is spread out. Light irradiation is cured, the mold is peeled off, and the fine structure is transferred to the mask material. The fine structure can be transferred to the transfer object by etching the transfer object using the mask material to which the fine structure has been transferred. In such a transfer method, bubbles may be caught in the mask material at the time of contact between the replica mold and the transferred material via the mask material. When bubbles are involved in the mask material, there is a problem that a defect (transfer defective area) is generated in the fine structure transferred to the mask material, resulting in a defective product. In recent years, with the demand for manufacturing cost reduction, there has been a need for a replica mold having a large transfer area capable of transferring a fine structure to a transfer target having a larger area. However, the tendency of entrainment of bubbles becomes more prominent as the transfer area increases.

  Therefore, the inventor of the present application curves the flat replica mold toward the transferred body so that the surface having the fine structure is convex, and brings the replica mold curved so as to be convex into contact with the transferred body. I found a transcription method. In this transfer method, after the convex shape of the surface having the microstructure of the mold comes into contact with the central portion of the transferred body, the contact area is gradually expanded uniformly toward the outer peripheral portion. As a result, in this transfer method, the mask material flows uniformly toward the outer peripheral portion while filling the fine structure. As a result, entrainment of bubbles in the mask material is prevented, and defects in the fine structure (transfer defective areas) transferred to the mask material can be prevented.

  However, in order to realize a replica mold curved to have such a convex shape with a transfer device, for example, it may be possible to curve a flat replica mold into a convex shape by pressure, but the configuration of the device is complicated. It becomes. Further, since the flat replica mold is curved with pressure, the load applied to the replica mold is large, and the replica mold itself may be damaged. Furthermore, since the surface is curved by the external pressure, the pressure is not applied uniformly over the entire surface of the replica mold. That is, unevenness occurs in the convex shape, and the curvature of the curve is different within the surface. Defects (transfer defective areas) occur in the structure.

  Also, in the case of conventional hard replica molds, if there is warping, protrusions or foreign objects in the transferred object, the resin can be applied to a wide range of resin centering on the protrusions and foreign objects when the transferred object is contacted with the replica mold via the mask material. In some cases, defects in the transferred fine structure (transfer defective area) may occur.

  Therefore, the present invention does not require a complicated transfer device, and a fine structure defect (transfer defective area) transferred to the mask material due to entrainment of bubbles or the like when the transferred object and the replica mold are contacted via the mask material. The present invention provides a replica mold and a method for manufacturing the same.

  The replica mold of the present invention is a replica mold that is formed of a soft material and has a fine structure on the surface, and is curved so that the surface having the fine structure becomes convex due to residual stress. When a surface having a fine structure is placed downward on a jig having an opening and supported by the edge of the opening, the sum of the deflection of the replica mold due to its own weight and the bending due to residual stress is the sum of the opening of the jig. It is characterized by being 2.0% to 6.0% with respect to the diameter.

FIG. 1A is a schematic view of a replica mold according to the present invention. FIG. 1 (b) shows the curve (X) due to the residual stress of the replica mold itself, and FIG. 1 (c) shows the sum of the curve (X) due to the residual stress of the replica mold itself and its own deflection (W). 2A to 2E are cross-sectional views schematically showing the manufacturing process of the replica mold according to the present invention. 3A to 3E are cross-sectional views schematically showing the manufacturing process of the replica mold according to the present invention. 4A to 4C are cross-sectional views schematically showing the manufacturing process of the replica mold according to the present invention. FIG. 5 is a schematic diagram of a method of measuring curvature (X) and deflection due to self-weight (W) due to residual stress of the replica mold itself according to the present invention. FIGS. 6A to 6D are cross-sectional views showing a process of transferring the microstructure of the replica mold according to the present invention to a mask material laminated on the transfer target. FIGS. 7A to 7C are schematic views showing the transfer results of the fine structure on the transfer object using the replica mold according to the present invention. (A) Examples 1 to 6 of the present invention, (b) shows the results of Comparative Examples 1, 2, 3, 5, and (c) shows the results of Comparative Example 4. FIG. 8 is a schematic view showing an example of a transfer result of a fine structure formed using the replica mold according to the present invention.

  Hereinafter, embodiments of the present invention will be described in detail.

  FIG. 1A is a schematic diagram of a part extracted from a replica mold 101 according to an embodiment of the present invention. This replica mold is formed of a soft material, has a fine structure on the surface, and is curved so that the surface having the fine structure becomes convex due to residual stress. Since the replica mold 101 is formed of a soft material, the replica mold 101 has flexibility and has a fine structure on the surface of nanometer order to micrometer order.

  As the soft material, an organic resin material or a rubber material is used. Examples include using silicone rubber, fluorine rubber, urethane rubber, acrylic rubber, PVC (polyvinyl chloride) rubber, nitrile rubber, butyl rubber, ethylene propylene rubber, styrene butadiene rubber, heat shrinkable film, heat shrinkable resin, etc. Can do. These soft materials may be copolymers with other materials, or may contain various compounding agents such as scorch inhibitors, reinforcing materials, fillers, softeners, and colorants.

  The above-mentioned soft material is an example, and the fine structure of the master mold can be accurately transferred, and the shape of the replica mold in which the surface having the fine structure is curved in a convex shape due to residual stress can be transferred multiple times. There is no particular limitation as long as it is a soft material that can be held over the transfer to the body. As the soft material, a silicone rubber such as one containing dimethylsiloxane is particularly preferable.

  Silicone rubber is composed of a siloxane bond with a silicon-oxygen bond as a skeleton and has an organic group such as a methyl group or a phenyl group in its side chain. Therefore, unlike conventional organic materials whose main chain is a carbon chain, it has excellent heat resistance. It has characteristics such as cold resistance and chemical resistance. Furthermore, since the silicone rubber has a high gas permeability, it can easily pass through the air and the solvent of the gasified mask material. Therefore, even when a solvent is contained in the mask material, defects in the transfer shape due to bubbles can be prevented by allowing gas to permeate, and the curing speed of the laminated mask material can be increased. Furthermore, when using a photocurable resin for the mask material, the soft material preferably has high light (visible light, ultraviolet light, etc.) permeability.

  The residual stress generated in the replica mold of the present invention refers to the elastic force generated in the replica mold by configuring the second soft material 102 to have a higher shrinkage rate than the first soft material 103. . The shrinkage that occurs in the soft material includes shrinkage (molding shrinkage) caused by the hardening of the soft material from the liquid state to the solid state and shrinkage caused by the temperature change in the solid state.

  The replica mold of the present invention includes a two-layer soft material composed of a first soft material 103 and a second soft material 102 having different shrinkage rates. By configuring the first soft material 103 to have a higher shrinkage rate than the second soft material 102, the surface having a fine structure is curved so as to be convex due to residual stress. In this specification, only the two-layer structure of the first soft material 103 and the second soft material 102 is described as the structure of the replica mold. However, the curved surface in which the surface having the fine structure becomes convex due to the residual stress. If it is maintained, a structure of three or more layers may be used.

  In general, an important factor that determines the shrinkage ratio of a soft material such as silicone rubber is a curing temperature. Generally, silicone rubber is prepared by blending a curing agent, a filler, or the like with an organopolysiloxane serving as a base polymer, adding an additive such as a catalyst, and crosslinking and curing. First, regarding the influence of the curing temperature, generally, the higher the curing temperature, the greater the shrinkage rate. For example, even if the same addition reaction silicone rubber is used, it is a room temperature curable type rubber due to differences in the catalyst and the like and is molded by weak heating at 80 ° C. for 30 minutes (for example, polydimethylsiloxane (PDMS) manufactured by Shin-Etsu Chemical) 10: 1 (weight ratio) mixture of “SIM-360” and curing agent “CAT-360” and a heat-curing type rubber (for example, manufactured by Shin-Etsu Chemical Co., Ltd.) molded by strong heating at 150 ° C. for 30 minutes Polydimethylsiloxane (PDMS) “KE-106” and curing agent “RG” in a 10: 1 (weight ratio) mixture). In this case, since the room temperature curable silicone rubber can be molded at a temperature about 70 degrees lower than that of the heat curable type, the room temperature curable silicone rubber can be molded with a lower shrinkage rate from the viewpoint of the molding temperature.

  In the present invention, particularly focusing on the curing temperature of the soft material, the shrinkage rate is changed by raising the curing temperature of the second soft material 102 over the curing temperature of the first soft material 103, and the surface having a fine structure It has been found that it can be curved so as to be convex due to residual stress.

  In addition to the above-described method, the second soft material 102 is selected so that the contraction rate is higher than that of the first soft material 103, so that the surface having a fine structure is convex due to residual stress. It is possible to obtain a replica mold that is curved so that

  Also, by applying a heat-shrinkable resin as the second soft material and heat-shrinking, or by bonding a heat-shrinkable film and heat-shrinking, the surface having a fine structure is curved so as to be convex due to residual stress. A replica mold can be obtained.

  FIGS. 1B and 1C are schematic diagrams relating to bending (X) and deflection due to self-weight (W) due to residual stress of the replica mold 101 of the present invention. FIGS. 1B and 1C schematically show the entire replica mold 101 of FIG. As shown in FIG. 1B, the replica mold 101 of the present invention is curved so that the surface having a fine structure becomes convex due to residual stress. This curvature is defined as a curvature (X) due to residual stress.

  As shown in FIG. 1C, since the replica mold 101 is formed of a soft material, the surface of the first soft material 103 having a fine structure is placed downward on a jig having an opening and the opening. In addition to the curvature (X) due to the residual stress of the replica mold 101 itself, a self-weight deflection (W) which is a deflection due to its own weight occurs, and the curvature (X) due to the residual stress and its own-weight deflection (W). With the sag of the sum.

  The inventor has made various studies to solve the above-described problems of the conventional mold, and as a result, the sum of the curvature (X) due to the residual stress of the replica mold 101 and the self-weight deflection (W) of the jig is determined during the transfer. It has been found that when the content is 2.0% to 6.0% with respect to the diameter of the opening, the bubble entrainment can be effectively prevented. If a conventional hard replica mold is bent by 2.0% to 6.0% with respect to the diameter of the opening of the jig, the amount of deformation becomes too large, and the load applied to the replica mold during transfer is greatly damaged. It is difficult to connect. In addition, when a flat replica mold is used and a deflection of 2.0% to 6.0% with respect to the diameter of the opening of the jig is given only by external pressure and self-weight deflection (W), unevenness is generated in the convex surface. Yes, that is, there is a difference in the curvature of the curved state in each plane, and this difference causes a defect in the microstructure (transfer defective area) to be transferred. Therefore, the present inventors have found that there is no unevenness in the surface of the convex shape for the first time due to the bending due to the internal stress of the replica mold itself, there is no difference in the curvature of the curved state in each surface, and good transfer can be realized. .

  The curvature due to the residual stress increases as the thickness of the first soft material decreases and as the thickness of the second soft material increases.

(Replica mold manufacturing method)
(Embodiment 1)
A method for manufacturing the replica mold 101 according to the first embodiment of the present invention will be described with reference to the drawings. 2A to 2E are schematic views for explaining the procedure of the method for manufacturing the replica mold 101 according to the preferred embodiment 1 of the present invention.

  First, as shown in FIG. 2A, a first soft material 103 is laminated on a master mold 201 on which a predetermined microstructure is formed according to the purpose. Specific examples of the material constituting the master mold 201 include quartz glass, nickel, and a Si substrate excellent in workability.

  The lamination method of the first soft material 103 is not particularly limited. For example, a general lamination method such as spin coating, dip coating, bar coating, screen printing, and gravure printing may be used. It can be used depending on the thickness. In a simple manner, lamination can be performed by pouring the liquid first soft material 103 into the master mold. The laminated first soft material 103 spreads on the surface of the master mold 201 and fills the microstructure of the master mold 201.

  Next, as shown in FIG. 2B, the first soft material 103 is cured at room temperature, thermoset, or ultraviolet light in a state where the fine structure of the surface of the master mold 201 is filled with the first soft material 103. Harden. The curing method is not particularly limited. As a result, the fine structure formed in the master mold 201 is transferred to the first soft material 103, and the fine structure is fixed. The first soft material 103 used here is, for example, a 10: 1 (weight ratio) mixture of polydimethylsiloxane (PDMS) “SIM-360” manufactured by Shin-Etsu Chemical Co., Ltd. and a curing agent “CAT-360”. Commercial products such as can be used. This product is a liquid silicone rubber and is a room temperature curable addition reaction material. Here, the silicone rubber was cured by heat treatment at 80 ° C. for 30 minutes.

  Next, as shown in FIG. 2C, a second soft material is laminated on the surface of the cured first soft material opposite to the microstructure. Although the lamination method is not limited, for example, a general lamination method such as spin coating, dip coating, bar coating, screen printing, and gravure printing is used according to the viscosity and thickness of the second soft material to be laminated. be able to. In a simple manner, lamination can be performed by pouring the liquid second soft material 102 over the first soft material 103.

  Next, as shown in FIG. 2D, the first soft material is cured in a state where the second soft material is laminated on the surface of the cured first soft material opposite to the microstructure. Heat cure at a temperature higher than the applied temperature. Examples include a 10: 1 (weight ratio) mixture of polydimethylsiloxane (PDMS) “KE-106” and curing agent “RG” manufactured by Shin-Etsu Chemical Co., Ltd. This product is a liquid silicone rubber and a general-purpose heat-curing addition reaction material. Here, the silicone rubber was cured by heat treatment at 150 ° C. for 30 minutes. Here, as described above, soft materials such as silicone rubber generally have a higher shrinkage rate as the vulcanization temperature (molding temperature) is higher. In the case of this example, since the soft material of the second soft material 102 is molded at a temperature about 70 degrees higher than that of the first soft material 103, the second soft material 102 is more contracted from the viewpoint of the molding temperature. The rate is greatly increased. Here, a replica mold 101 is a laminate of the first soft material 103 and the second soft material 102.

  Here, the first soft material and the second soft material are different types of soft materials having a curing temperature as a physical property value of the second soft material higher than a curing temperature as a physical property value of the first soft material. A material may be used. Further, the first soft material and the second soft material may be the same soft material and the curing temperature may be increased.

  The replica mold 101 is cooled or naturally cooled, and residual stress is generated in the replica mold 101 due to the difference in thermal shrinkage between the first soft material 103 and the second soft material 102.

  Next, the replica mold 101 is separated from the master mold 201 as shown in FIG. The fine structure of the master mold 201 is accurately transferred to the surface of the first soft material 103 of the replica mold 101. Since the second soft material 102 is formed to have a larger shrinkage rate than the first soft material 103, the replica mold 101 is curved so that the surface having a fine structure becomes convex due to residual stress.

  Further, as shown in FIGS. 3A to 3E, after the first soft material 103 is formed, the first soft material 103 is separated from the master mold 201, and the second softening material 103 is placed on the mounting allowance 301. A soft material may be formed.

(Embodiment 2)
4A to 4C are schematic views for explaining the procedure of the method for manufacturing the replica mold 101 according to the preferred embodiment 2 of the present invention.

  First, as shown in FIG. 4A, a soft material 401 is laminated on a master mold 201 on which a predetermined microstructure is formed according to the purpose. Specific examples of the material constituting the master mold 201 include quartz glass, nickel, and a Si substrate excellent in workability. The method of laminating the soft material 401 is not particularly limited. For example, a general laminating method such as spin coating, dip coating, bar coating, screen printing, and gravure printing is performed according to the viscosity and thickness of the soft material 401. Can be used. In a simple manner, lamination can be performed by pouring a liquid soft material 401 into a master mold. The laminated soft material 401 spreads on the surface of the master mold 201 and fills the fine structure of the master mold 201.

  Next, as shown in FIG. 4B, the soft material 401 is heated from both the master mold side and the back side while the soft material 401 is filled in the fine structure of the surface of the master mold 201. The heating temperature of the soft material 401, for example, silicone rubber, is 70 degrees or more higher on the back side than on the master mold side. The thermosetting here may be performed first on the master mold side or the back surface side, or may be performed simultaneously. Although the method of thermosetting is not particularly limited, preferably, the back surface of the master mold and the back surface of the silicone rubber 401 are sandwiched simultaneously by two hot plates and adjusted to the respective target temperatures and heated.

  Examples of the soft material 401 used here include a 10: 1 (weight ratio) mixture of polydimethylsiloxane (PDMS) “KE-106” and a curing agent “RG” manufactured by Shin-Etsu Chemical Co., Ltd., and the like. This product is a liquid silicone rubber and a general-purpose heat-curing addition reaction material. Here, the soft material 401 was cured by heat treatment for 6 hours at 80 ° C. from the master mold side and 150 ° C. from the back side. Here, as described above, the soft material 401, for example, silicone rubber generally has a higher shrinkage rate as the vulcanization temperature (molding temperature) is higher. In the case of this example, the soft material on the back side is molded at a temperature 70 degrees lower than that on the master mold side, so that the master mold side is molded with a larger shrinkage rate from the viewpoint of molding temperature. Here, the layer regions on the master mold side and the back side where the difference in shrinkage occurs due to the difference in curing conditions are defined as a first soft material 103 ′ and a second soft material 102 ′, respectively.

  By the curing treatment, the base polymer in the soft material is crosslinked and cured by a curing agent and a catalyst. As a result, the fine structure formed in the master mold 201 is transferred to the soft material 401, and the fine structure is fixed. Here, the hardened soft material 401 is referred to as a replica mold 101 ′.

  The replica mold 101 ′ is cooled or naturally cooled, and residual stress is generated in the replica mold due to a difference in thermal shrinkage between the first soft material 103 ′ and the second soft material 102 ′.

  Next, as shown in FIG. 2C, the replica mold 101 ′ is separated from the master mold 201. The fine structure of the master mold 201 is accurately transferred to the surface of the first soft material 103 ′ of the replica mold 101 ′. Due to the difference in shrinkage rate inside the replica mold, the replica mold 101 ′ is curved so that the surface having a fine structure becomes convex due to residual stress.

(Measuring method of bending due to residual stress (X) and deflection of own weight (W))
FIG. 5 shows a schematic diagram of a method for measuring the curvature (X) and the self-weight deflection (W) due to the residual stress. Measurement of curvature (X) and deflection due to self-weight (W) due to residual stress was performed according to the following procedure.

  First, the replica mold is mounted on a jig (104a and 104b) having a horizontally fixed opening with a finely curved surface facing downward and supported by the edge of the opening. (State A). At this time, the replica mold is engaged with a jig having an opening at a position of 1 to 5% from the outermost periphery with respect to the diameter of the replica mold.

  Next, the displacement of the jig (104a and 104b) having the horizontally fixed opening and the most bent portion of the replica mold 101 was measured by a non-contact measurement method, for example, a laser displacement meter. The displacement at this time was defined as the sum (X + W) of the curvature (X) and the self-weight deflection (W) due to the residual stress.

  Next, the surface opposite to the surface having a microstructure that is curved so as to be convex to the jig (104a and 104b) having an opening fixed horizontally by inverting the front and back of the replica mold 101 is directed downward. And supported by the edge of the opening (state B). At this time, the replica mold is engaged with a jig having an opening at a position of 1 to 5% from the outermost periphery with respect to the diameter of the replica mold.

  Next, the displacement of the most bent portion of the jig (104a and 104b) having the horizontally fixed opening and the replica mold 101 was measured by a non-contact measurement method. The displacement at this time was defined as the difference (W−X) between the deflection due to its own weight (W) and the curvature (X) due to the residual stress.

  The value (1/2) of the difference between the measured value (X + W) in the state A and the measured value (W−X) in the state B is defined as the curvature (X) due to the residual stress of the replica mold. Further, a value ½ of the sum of the measured value (X + W) in the state A and the measured value (W−X) in the state B is defined as a self-weight deflection (W) of the replica mold 101.

  The shape of the opening of the jig (104a and 104b) having the opening is not limited to a circle, and may be an ellipse, a polygon, or the like in plan view according to the shape of the replica mold. The diameter of the jig having an opening when the jig is a polygon is the diameter of the largest circle inscribed in the polygon.

  The method of measuring the curvature (X) and the self-weight deflection (W) due to the residual stress is not limited to the above method. For example, in an environment where the replica mold is immersed in a liquid having a specific gravity equal to that of the replica mold, the deformation due to gravity does not occur. It can also be measured by a method such as measuring the curvature (X) due to residual stress by a non-contact measurement method.

(Microstructure transfer device)
Next, a fine structure transfer method using a fine structure transfer apparatus including the replica mold 101 according to the present embodiment will be described mainly with reference to FIGS. The vertical direction in the following description is based on the vertical direction shown in FIG.

  As shown in FIG. 6A, the microstructure transfer device is configured to transfer the microstructure of the replica mold 101 onto the surface of the transfer target 602 by bringing the replica mold 101 into contact with the transfer target 602. Yes.

  As shown in FIG. 6A, the replica mold 101 is disposed above the transfer target 602 and is held at its ends by holding jigs 604a and 604b. The holding jigs 604a and 604b preferably hold the entire circumference (outer peripheral portion) of the outer periphery of the replica mold 101, but may hold several end portions of the replica mold 101.

  The replica mold 101 desirably transmits ultraviolet light. When the replica mold 101 is UV transmissive, a photocurable resin can be used as a mask material. The replica mold 101 has a transfer region in which a fine structure is formed on a surface facing the transfer target 602. The replica mold 101 is curved so as to be convex downward (to the transfer target 602).

  The replica mold 101 in the present embodiment has a disk shape, but the shape of the replica mold 101 is not limited to this, and may be an ellipse, a polygon, or the like in plan view. Note that the replica mold 101 may have a shape and surface area different from those of the transfer target 602 as long as the fine structure can be transferred to a predetermined region of the transfer target 602. Moreover, a mold release process can be performed on the surface of the replica mold 101.

  The stage 601 can be moved up and down by a lifting device (not shown), and is configured to press the transferred body 1 against the replica mold 101 or separate the transferred body 602 from the replica mold 101.

  On the stage 601, a transfer target 602 to which a photocurable resin 603 is dropped is disposed.

  The photocurable resin 603 may be a known one, and includes a resin material added with a photosensitive substance. As this resin material, a radical polymerizable material, a cationic polymerizable material, an anion polymerizable material, or the like can be used. Examples of these materials include cycloolefin polymer, polymethyl methacrylate, polystyrene polycarbonate, polyethylene terephthalate (PET), polylactic acid, polypropylene, polyethylene, and polyvinyl alcohol. The photocurable resin 603 may be a mixture of monomers having a vinyl group, an epoxy group, an oxetanyl group, a methacrylate group, an acrylate group, or the like as appropriate. Although described as the transferred object 602 to which the photocurable resin 603 is dropped, the photocurable resin may be laminated on the transferred object in advance. The method for laminating the photocurable resin is not particularly limited, and for example, a dispensing method or a spin coating method can be used.

  Next, as shown in FIG. 6B, when the stage 601 is raised and the replica mold is pressed against the transfer target 1, the dropped photocurable resin is filled into the microstructure of the replica mold 101. . At this time, the replica mold 101 is deformed so as to follow the transfer target 602 and becomes flat.

  Then, as shown in FIG. 6C, when ultraviolet light (UV) is irradiated, the ultraviolet light passes through the replica mold 101 and irradiates the photocurable resin 603, whereby the photocurable resin 603 is cured. To do.

  As shown in FIG. 6D, when the transferred object 602 is peeled from the replica mold 101 by lowering the stage, the surface of the transferred object 602 has a hardened photocurable resin 603 and a microstructure of the replica mold 101. A pattern forming layer (mask layer) 603 to which is transferred is obtained.

  In the fine structure transfer device described above, the photocurable resin 603 is used as a mask material. However, a solvent-diluted thermoplastic resin may be applied on a transfer target and used as a mask material.

  Next, functions and effects of the microstructure transfer device according to the present embodiment will be described.

  The replica mold 101 of the present invention installed in this fine structure transfer apparatus is curved so as to be convex toward the transfer target. During the transfer of the fine structure, after the top of the curved replica mold 101 comes into contact with the central portion of the transfer body 603, the contact area is gradually expanded uniformly toward the outer periphery of the transfer body 602. Go. As a result, in this fine structure transfer apparatus, the photocurable resin 603 laminated on the transfer target 602 uniformly flows toward the outer peripheral portion while filling the fine structure. This prevents entrainment of bubbles in the photocurable resin 603. Therefore, according to this fine structure transfer apparatus, it is possible to form the pattern formation layer (mask layer) 603 that does not involve the formation of bubbles.

  In addition, since the replica mold 101 of the present invention is formed by bending a replica mold made of a soft material due to internal stress, it is easy to peel off when the replica mold 101 is peeled after the mask material is cured. Thus, the load applied to the end of the replica mold 101 is small and is not easily damaged.

  Hereinafter, the present invention will be described in detail with reference to examples.

[Examples 1 to 5, Comparative Examples 1 to 4]
Replica molds according to Examples 1 to 5 and Comparative Examples 1 to 4 were produced by the procedure of Embodiment 1 shown in FIGS. As the master mold 201 used for the production of the replica mold, a disk shape having a diameter of 150 mm, a thickness of 1.0 mm, and a material single crystal silicon was used. On the surface of the master mold, a fine structure of a dot pattern (diameter 1.8 μm, height 3 μm) formed by photolithography is formed in the outer diameter range of 74 mm from the center. First, as shown in FIG. 2 (a), each of the first soft materials 103 shown in Tables 1 and 2 is placed on the surface having the fine structure of the master mold in Examples 1, 3 to 5, and Comparative Examples 1 to 3. In Example 4, the thickness was 0.5 mm, and in Example 2, the thickness was 1.0 mm. Next, as shown in FIG. 2B, the first soft material 103 was cured under the respective curing conditions shown in Tables 1 and 2 to form the first soft material 103. The first soft material 103 of Example 4 and Comparative Example 3 was formed by irradiating with 200 mJ ultraviolet rays at a room temperature of 23 ° C.

  Next, as shown in FIG. 2C, the second soft material 102 is placed on the first soft material 103 in Examples 1 and 3 to 5 and Comparative Examples 1 to 4 is 1.5 mm. Laminated to a thickness of 1.0 mm. Next, as shown in FIG. 2D, the second soft material 102 was cured under the curing conditions shown in Tables 1 and 2 to form the second soft material 102. Next, as shown in FIG. 2E, the replica mold 101 having a thickness of 2.0 mm in which the first soft material 103 and the second soft material 102 are laminated is separated from the master mold 201. The replica mold 101 was produced with a diameter of 150 mm and a thickness of 2.0 mm.

[Example 6, Comparative Example 5]
Replica molds according to Example 6 and Comparative Example 5 were manufactured according to the procedure of Embodiment 2 shown in FIGS. First, as shown in FIG. 4A, the soft materials shown in Tables 1 and 2 were laminated to a thickness of 2.0 mm on the surface of the master mold having a fine structure. The master mold 201 used for manufacturing the replica mold was the same as that used in Examples 1 to 5 and Comparative Examples 1 to 4. Here, the areas of the soft material 401 on the master mold side and the back surface side thereof are defined as a first soft material 103 ′ and a second soft material 102 ′, respectively.

  Next, as shown in FIG. 4B, the soft material 401 is sandwiched between the master mold side and the back side by a hot plate and heated under the curing conditions shown in Tables 1 and 2, and the first soft material 103 ′ and The second soft material 102 ′ was heat cured. Next, as shown in FIG. 4C, the replica mold 101 ′ having a thickness of 2.0 mm in which the first soft material 103 ′ and the second soft material 102 ′ are laminated is separated from the master mold 201. The replica mold 101 ′ was manufactured to have a diameter of 150 mm and a thickness of 2.0 mm.

[Results of Examples 1 to 6 and Comparative Examples 1 to 5]
Tables 1 and 2 show the product names, the crosslinking type, the curing temperature, and the curing time of the first soft material and the second soft material used in the production of the replica molds according to Examples 1 to 6 and Comparative Examples 1 to 5. , Indicating thickness. Tables 1 and 2 also show that the replica molds according to Examples 1 to 6 and Comparative Examples 1 to 5 are curved due to residual stress (X), self-weight deflection (W), and the sum of curvature due to residual stress and self-weight deflection (X + W). , Showing transferability.

  Curvature due to residual stress (X), self-weight deflection (W) of replica mold, and sum of curvature due to residual stress and self-weight deflection (X + W) are determined by the method for measuring curvature (X) and self-weight deflection (W) due to residual stress described above. It was measured. These values are shown in Tables 1 and 2 as a percentage (%) to the diameter of the opening of the jig having the opening. The diameter of the opening of the jig having the opening used for measurement of the replica molds according to Examples 1 to 6 and Comparative Examples 1 to 5 was 145 mm.

  Regarding the transferability of Tables 1 and 2, according to the procedure of FIGS. 6A to 6D, photocurability on the transfer object using the replica molds according to Examples 1 to 6 and Comparative Examples 1 to 5. The transfer result at the time of performing transfer with respect to resin is shown. The transfer target was 0.65 mm thick and 100 mm in diameter. The photocurable resin (product name PAK-01, manufactured by Toyo Gosei Co., Ltd.) was used in an amount of 0.5 g and irradiated with 1000 mJ ultraviolet rays. The transferability is indicated by a circle (○) for those in which good transfer was obtained to the photo-curing resin on the transferred material, and a cross (×) for those in which bubbles were involved. Marked.

  FIGS. 7A to 7C are schematic views showing the transfer results of the fine structure on the transfer object using the replica mold according to the present invention. 7 (b) to 7 (c) indicate a portion where bubbles are involved in the mask material and a defect (transfer defective region) occurs in the fine structure of the transfer result. (A) Examples 1 to 6 of the present invention, (b) shows Comparative Examples 1, 2, 3, 5, and (c) shows the transfer results according to Comparative Example 4.

  In the examples and comparative examples, the first soft material and the second soft material used the following product name silicone rubber.

  SIM-360 (manufactured by Shin-Etsu Chemical Co., Ltd.), curing type: addition reaction, room temperature curing type.

  KE-106 (manufactured by Shin-Etsu Chemical Co., Ltd.), curing type: addition reaction, heat curing type.

X-34-4184A / B (manufactured by Shin-Etsu Chemical Co., Ltd.), curing type: addition reaction, ultraviolet curing type.

  In Examples 1 to 6 shown in Table 1 and FIG. 7A, bubbles are not entrained in the photocurable resin on the transfer target, and the replica mold has a fine structure on the entire surface of the mask material. Transferred well. From this, when the sum of the self-weight deflection of the replica mold and the curvature due to the residual stress is in the range of 2.0% to 6.0% with respect to the diameter of the opening of the jig (Examples 1 to 6), It can be seen that there is no fine structure defect (transfer defect region) transferred to the mask material due to entrainment of bubbles or the like.

  In Tables 1 to 6, in Examples 1 to 6, the second soft material is thermally cured at a temperature that is 70 ° C. higher than the temperature at which the first soft material is cured. The second soft material 102 is cured so as to have a larger shrinkage rate than the first soft material 103, so that the replica mold has a range of 1.0% to 5.0% with respect to the diameter of the opening of the jig. Curvature occurs due to the residual stress inside.

  In Comparative Examples 1 to 5 shown in Table 2 and FIGS. 7B and 7C, bubbles were involved in the photocurable resin on the transfer target. From this, when the sum of the self weight deflection of the replica mold and the curvature due to the residual stress is less than 2.0% with respect to the diameter of the opening of the jig (Comparative Examples 1 to 5), entrainment of bubbles occurs. I understand.

  Further, as shown in Table 2, in Comparative Examples 1 to 5, the second soft material is thermoset at a temperature difference of less than 70 ° C. than the first soft material. As a result, the second soft material 102 did not cure so as to have a sufficiently high shrinkage rate as compared with the first soft material 103. As a result, the replica molds according to Comparative Examples 1 to 5 were curved by a residual stress of less than 1.0% with respect to the diameter of the opening of the jig.

  In the transfer result of Comparative Example 4 shown in FIG. 7C, more bubbles were involved than in the transfer results of Comparative Examples 1, 2, 3, and 5 shown in FIG. This is because, in Comparative Examples 1, 2, 3, and 5, the sum of the bending due to the residual stress and the self-weight deflection shown in Table 2 is 1.5% to 1.7% with respect to the diameter of the opening of the jig. On the other hand, in Comparative Example 4, it is 1.0%. In the replica mold according to Comparative Example 4, since the convex curvature of the surface having the fine structure is small, it was not possible to prevent the entrainment of bubbles.

  In Examples 1 to 6 and Comparative Examples 1 to 5, examples in which silicone rubber is used for the first soft material and the second soft material are described, but the present invention is not limited to this. For example, a rubber material other than silicone rubber may be used for the other first and second soft materials, and the second soft material may be thermally cured at a temperature higher than the temperature at which the first soft material is cured. . Alternatively, the second soft material 102 may be compared with the first soft material 103 and a material having a large shrinkage rate may be selected and thermally cured. Alternatively, a heat-shrinkable resin may be applied as the second soft material and heat-shrinked, or a heat-shrinkable film may be bonded and heat-shrinked. Moreover, although the structure of the replica mold in Examples 1-6 and Comparative Examples 1-5 has described only the two-layer structure which consists of the 1st soft material 103 and the 2nd soft material 102, the surface which has a fine structure However, if a curved shape that is convex due to residual stress is maintained, a structure of three or more layers may be used.

  The replica molds described in Examples 1 to 6 in which the first soft material and the second soft material are silicone rubber are particularly preferable from the viewpoints of ultraviolet ray permeability, heat resistance, chemical resistance, gas permeability, and the like.

  FIG. 8 is a schematic diagram of a cross-sectional SEM photograph showing the fine structure on the transfer body created by the replica mold according to Example 1. FIG. Thus, a dot pattern (diameter 1.8 μm, height 3.0 μm) in which the fine structure of the master mold was precisely transferred was obtained.

  Therefore, according to the present invention, a complicated transfer device is not required for transfer to the transfer object, and a fine transfer that is transferred to the mask material by entrainment of bubbles or the like at the time of contact between the transfer object and the mold via the mask material. It is possible to provide a replica mold capable of preventing structural defects (transfer defective regions).

Claims (4)

A replica mold made of a soft material and having a fine structure on its surface,
The replica mold is curved so that the surface having the microstructure is convex due to residual stress,
When the replica mold is placed on a jig having an opening with the surface having the fine structure facing downward and supported by an edge of the opening, the replica mold is bent by its own weight and the residual stress. The replica mold is characterized in that the sum is 2.0% to 6.0% with respect to the diameter of the opening of the jig.   The replica mold according to claim 1, wherein the soft material includes a silicone rubber made of polydimethylsiloxane.   The replica mold according to claim 1, wherein the curvature of the replica mold due to the residual stress is 1.0 to 5.0% with respect to the diameter. A replica mold manufacturing method for transferring a fine structure in contact with a transfer object,
Laminating a first soft material on the master mold on which the microstructure is formed;
Forming the first soft material to which the fine structure is transferred by curing the first soft material at room temperature, thermosetting, or ultraviolet curing;
Laminating a second soft material on a surface opposite the microstructure of the cured first soft material;
Thermally curing the second soft material at a temperature higher than the temperature at which the first soft material is cured;
The replica mold made of the first and second soft materials is cooled or allowed to cool naturally, and residual stress is generated in the replica mold due to the difference in thermal shrinkage between the first soft material and the second soft material. Comprising the steps of:
A method of manufacturing a replica mold, wherein the first soft material side of the replica mold has a convex shape due to the residual stress.

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