JP2019114667A - Method for manufacturing imprint mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture an imprint mold capable of forming a concavo-convex structure on a convex structure portion by an inversion process with high accuracy and suppressing curing of an imprint resin protruding outward from a concavo-convex pattern forming region of the convex structure portion. Provide a method. SOLUTION: A mold base material having a convex structure portion protruding from a first surface of a base portion and a hard mask layer covering the upper surface and side surfaces of the convex structure portion is prepared, and a master mold is formed on an imprint resin on the convex structure portion. The uneven pattern of the above is transferred to form a transfer pattern, an inverted layer is formed on the transfer pattern, the inverted layer is embedded in the concave portion of the transfer pattern, the top of the convex portion is exposed, and the inverted layer covers the second upper surface. The inverted layer is etched so that the remaining inverted layer is etched, the inverted layer pattern is formed by etching with the remaining inverted layer as a mask, the hard mask pattern is formed by etching with the inverted layer pattern as a mask, and the hard mask pattern is used as a mask. An uneven structure is formed on the convex structure portion by the etching. [Selection diagram] Fig. 2

Description

  The present disclosure relates to a method of manufacturing an imprint mold.

  In recent years, in the manufacturing process of semiconductor devices (for example, semiconductor memory etc.), using a mold member (imprint mold) in which a concavo-convex pattern is formed on the surface of a substrate, the concavo-convex pattern is equally transferred onto a workpiece such as a substrate The nanoimprint technology which is a pattern formation technology is used.

  The mold having a concavo-convex pattern used in the nanoimprint technology can be manufactured by, for example, electron beam lithography or the like. The mold manufactured in this manner has a concavo-convex pattern such as a shape and a dimension with high accuracy. However, while the manufacturing cost of the mold is increased, a transfer pattern formed on a workpiece (such as a resin for imprint) may have defects after passing through a predetermined number of transfer steps, or an uneven pattern of the mold May be damaged.

  If a defect in the transfer pattern or damage to the uneven pattern of the mold occurs, replacement with a new mold each time increases the manufacturing cost of the product manufactured through the nanoimprint process. Therefore, when performing a nanoimprint process on an industrial scale, generally, a mold manufactured by electron beam lithography or the like as described above is used as a master mold, and a replica mold or the like manufactured by nanoimprint lithography using the master mold is used. (See Patent Document 1).

  By the way, in recent years, a technology that applies a so-called inversion process to the nanoimprint technology has been proposed (see Patent Document 2 and Non-Patent Document 1). The inversion process includes the steps of forming an inversion layer on the transfer pattern on the substrate on which the uneven pattern of the mold has been transferred, etching back the inversion layer to expose the top of the transfer pattern, and the remaining inversion layer. Etching the transfer pattern using as a mask. By etching the substrate using the inversion layer obtained by this inversion process as a mask, the concavo-convex pattern of the mold is transferred to the substrate. By using a reverse process in the nanoimprint technology, it is possible to produce a replica mold having a concavo-convex pattern of the same shape as the master mold. For example, in the case of producing a replica mold having a hole pattern by a nanoimprint technique, it is necessary to use a master mold having a pillar pattern in which physical strength is a problem, but by applying a reverse process, a hole pattern is provided. A master mold can be used to make a replica mold having a hole pattern.

WO 2011/155602 pamphlet JP, 2009-38085, A

"Reverse-tone ultraviolet nanoimprint lithography with fluorescent UV-curable resins", Japanese Journal of Applied Physics, 54, 06FM02, 2015

  In Patent Document 2 and Non-patent Document 1 described above, an ultraviolet curable resin having a sufficient selectivity to the imprint resin layer is applied by spin coating as a material constituting the reversal layer, and the ultraviolet curable resin layer is It is formed. The ultraviolet curable resin layer formed by the spin coating method has slight unevenness on the surface due to the influence of the uneven pattern transferred to the imprint resin layer, so a flat quartz substrate is pressed against the ultraviolet curable resin layer. Thus, the ultraviolet curable resin layer is planarized, and ultraviolet light is irradiated in this state to form an inversion layer.

  It is considered to apply the above-mentioned inversion process to a manufacturing process of a replica mold. In the ordinary nanoimprint technology, if the concavo-convex pattern of the master mold is a concave pattern such as a hole pattern, the concavo-convex pattern of the replica mold is a convex pattern such as a pillar pattern. In the case of a convex pattern such as a pillar pattern, in particular a convex pattern having a dimension of about 20 nm to 40 nm, there is a problem of physical strength, so from the viewpoint of the life of the master mold and replica mold, both the master mold and replica mold In both cases, it is desirable to have a concave pattern such as a hole pattern as the uneven pattern. From such a point of view, it can be said that it would be very useful if the inversion process could be applied to the replica mold manufacturing process.

  Usually, the mold base includes a base having a first surface and a second surface opposed thereto, and a convex structure (so-called mesa structure) which protrudes from the first surface and on which a concavo-convex pattern is formed. Imprinting is performed by transferring the concavo-convex pattern of the master mold to the imprint resin layer on the convex structure of the mold substrate and applying an ultraviolet curable resin on the imprint resin layer by spin coating to form a reverse layer. The film thickness of the outer periphery of the inversion layer formed on the resin layer will increase more than the film thickness of the inner side. That is, the film thickness unevenness occurs in the inversion layer formed on the imprint resin layer.

  In the replica mold, since a concavo-convex pattern may be formed extremely close to the outer peripheral edge on the convex structure, the film of the outer peripheral edge of the inversion layer formed on the imprint resin layer is the film on the inner side By increasing the thickness, the dimensional accuracy of the concavo-convex pattern formed on the convex structure portion is reduced by the etching process using the inversion layer as a mask. In particular, the dimensional accuracy of the concavo-convex pattern located in the vicinity of the outer peripheral edge of the convex structure portion is significantly reduced.

  On the other hand, at the time of the imprint process using the replica mold which has a convex structure, there exists a problem that imprint resin will protrude outside from convex structure top, and it may swell along the side of a convex structure. The imprint resin protruding to the outside of the convex structure portion is cured together with the imprint resin filled in the concavo-convex pattern. As a result, when the imprinting process is performed by the so-called step-and-repeat method, it is necessary to separate the imprint region so that it does not overlap with the cured imprint resin when the imprint region protrudes outside the convex structure. The number of times the imprint process can be performed on the transfer substrate is limited.

  In addition, when the imprint resin and the imprint mold come into contact with the convex structure, protruding into the outer side of the convex structure and rising along the side surface, the imprint mold may be damaged or a defect of the cured imprint resin may occur. There is also a possibility that foreign matter may be generated by

  In order to solve such a problem, by forming a light shielding film continuous from the side surface of the convex structure so as to surround the outer side of the convex structure, the imprint resin protruding to the outer side of the convex structure is not cured. Technologies have been proposed. However, it is extremely difficult to form a uniform light shielding film on the side surface of the convex structure having a height of about 10 μm to 50 μm, and there is a problem that film formation defects are caused. In the light shielding film in which the film formation defect is generated, a sufficient light shielding effect can not be obtained, and there is a problem that the imprint resin which is protruded to the outside of the convex structure is cured.

  In view of the above problems, according to the present disclosure, the concavo-convex structure can be formed with high accuracy on the convex structure portion by the inversion process, and the imprint resin protruding to the outside from the concavo-convex pattern formation region of the convex structure portion is cured. It is an object of the present invention to provide a method of manufacturing an imprint mold that can suppress the

  In order to solve the above problems, according to an embodiment of the present disclosure, a base including a first surface and a second surface opposite to the first surface, and a convex structure that protrudes from the first surface of the base; A substrate preparation step of preparing a mold substrate comprising the first surface of the base and a hard mask layer covering the upper surface and the side surface of the convex structure; imprint resin applied to the upper surface of the convex structure A transfer pattern forming step of forming a transfer pattern on the convex structure by transferring the concavo-convex pattern of the master mold onto the convex structure, and supplying a reverse layer forming material on the transfer pattern to cover the transfer pattern. An inversion layer forming step of forming a layer, and an etch back for etching the inversion layer so as to expose a top of the convex portion in a state where the inversion layer is embedded in the concave portion of the transfer pattern Approximately, an inversion layer pattern forming step of forming an inversion layer pattern on the upper surface of the convex structure portion by etching the transfer pattern using the etched inversion layer as a mask; and the hard layer using the inversion layer pattern as a mask A step of forming a hard mask pattern on the upper surface of the convex structure portion by etching the mask layer; and etching the convex structure portion using the hard mask pattern as a mask; Forming a concavo-convex structure on the top surface, wherein the top surface of the convex structure has a first top surface including a pattern area on which the concavo-convex structure can be formed, and the base surface of the base than the first top surface A second upper surface including a non-pattern area located on the first surface side and surrounding the periphery of the pattern area; Is formed in the pattern area of the first upper surface, and the inversion layer is etched so as to leave the inversion layer covering the second upper surface in the etch back step, and in the hard mask pattern forming step A method of manufacturing an imprint mold is provided in which the hard mask layer is left on the second upper surface by etching the hard mask layer using the inversion layer remaining on the second upper surface as a mask. .

  In the inversion layer forming step, the inversion layer may be formed such that the height of the inversion layer on the second upper surface is higher than the height of the inversion layer on the first upper surface, and the convex structure The side surface of the portion includes a first side surface continuing from the outer peripheral edge of the first upper surface to the second upper surface, and a second side surface connecting the outer peripheral edge of the second upper surface to the first surface of the base, The hard mask layer is formed to cover at least the first upper surface, the first side surface, and the second upper surface, and the inversion remaining on the second upper surface in the hard mask pattern formation step The hard mask layer may be etched using the layer as a mask to leave the hard mask layer covering the first side surface and the second upper surface.

  The imprint mold is used for a light imprint process of curing an imprint resin by irradiating a light beam through the imprint mold, and the hard mask layer is made of a material capable of blocking the light beam. Just do it.

  The difference in height between the first upper surface and the second upper surface may be 1 μm to 10 μm, and between the outer edge of the first upper surface and the outer edge of the second upper surface in a plan view of the mold substrate The length may be 1 μm to 1000 μm.

  The inversion layer forming material may contain Si and a thermosetting resin, and the size of the concavo-convex area in which the concavo-convex pattern is formed in the master mold is physically on the first upper surface of the convex structure. It is sufficient that the size is included.

  According to the present disclosure, the concavo-convex pattern can be formed with high accuracy on the convex structure portion by the inversion process, and the curing of the imprint resin which has protruded outside from the concavo-convex pattern formation region of the convex structure portion can be suppressed. It is possible to provide a method of manufacturing an imprint mold.

FIGS. 1 (A) to 1 (E) are process flow diagrams showing each process of a method of manufacturing an imprint mold according to an embodiment of the present disclosure in a cut end view. 2 (A) to 2 (E) are process flow diagrams following FIG. 1 (E) showing the respective processes of the method of manufacturing an imprint mold according to an embodiment of the present disclosure in a cut end view. Drawing 3 (A)-(E) is a process flow figure showing each process of a manufacturing method of a mold substrate in one embodiment of this indication with a cutting end figure. FIG. 4 is a partially enlarged cut end view showing a schematic configuration of a convex structure of a mold base according to an embodiment of the present disclosure. FIG. 5 is a plan view showing a schematic configuration of a convex structure of a mold base according to an embodiment of the present disclosure.

  Embodiments of the present invention will be described with reference to the drawings. In the drawings attached to the present specification, the shapes, scales, dimensional ratios of dimensions, etc. of the respective parts may be changed or exaggerated from the actual ones for easy understanding. The numerical range represented using "-" in this specification etc. means that it is the range which includes each of the numerical value described before and behind "-" as a lower limit and an upper limit. In the present specification and the like, terms such as "film", "sheet", "plate" and the like are not distinguished from each other based on difference in designation. For example, "plate" is a concept that also includes members that can be generally called "sheet" and "film".

  1 (A) to 1 (E) are process flow diagrams showing each step of the method for producing an imprint mold according to the present embodiment in a cut end view, and FIGS. 2 (A) to 2 (E) are It is a process flowchart following FIG.1 (E) which shows each process of the manufacturing method of the imprint mold which concerns on embodiment with a cut end view, and FIG.3 (A)-(E) are the molds in this embodiment. FIG. 4 is a process flow diagram showing each process of a method of manufacturing a base material in a cut end view, and FIG. 4 is a partially enlarged cut end view showing a schematic configuration of a convex structure of a mold base in the present embodiment, 5 is a top view which shows schematic structure of the convex structure part of the mold base material in this embodiment.

[Preparation of mold base material]
First, a base 21 having a first surface 21A and a second surface 21B opposite to the first surface 21A, and a convex structure 22 located at a substantially central portion in plan view on the first surface 21A side of the base 21 and projecting from the first surface 21A. And prepare a mold base 20 (see FIG. 1A). In the illustrated example, the recess 23 is formed on the second surface 21B side of the base 21. However, the present invention is not limited to this aspect, and the recess 23 is provided on the second surface 21B of the base 21. It does not have to be formed.

  The material which comprises the base 21 of the mold base 20 is not specifically limited, It is general as a mold base. For example, the base 21 is a substrate generally used when manufacturing an imprint mold (for example, glass such as quartz glass, soda glass, fluorite, calcium fluoride substrate, magnesium fluoride substrate, acrylic glass, etc. Substrates, resin substrates such as polycarbonate substrates, polypropylene substrates, polyethylene substrates, and transparent substrates such as laminated substrates formed by laminating two or more substrates arbitrarily selected therefrom; such as nickel substrates, titanium substrates, aluminum substrates, etc. Metal substrate; silicon substrate, semiconductor substrate such as gallium nitride substrate, and the like). In the present embodiment, “transparent” means that the transmittance of light having a wavelength of 300 nm to 450 nm is 85% or more, preferably 90% or more, and particularly preferably 95% or more.

The thickness T ₂₁ of the base portion 21 of the mold base 20 may be appropriately set, for example, in the range of about 300 μm to 10 mm, in consideration of strength, handleability, and the like. The size (the size in plan view) of the base 21 of the mold base 20 is not particularly limited, but when the base 21 is made of quartz glass, for example, the size of the base 21 is 152 mm × It is about 152 mm.

  It does not specifically limit as planar view shape of the base 21 of the mold base material 20, For example, substantially rectangular shape, substantially circular shape, etc. are mentioned. When the imprint mold 1 (see FIG. 2E) manufactured in the present embodiment is made of quartz glass generally used for light imprinting, the plan view shape of the base 21 is generally substantially rectangular. It is a shape.

  The convex structure 22 which protrudes from the first surface 21A of the base 21 of the mold base 20 is provided substantially at the center of the base 21 (first surface 21A) in a plan view. The shape of the convex structure 22 may be, for example, a substantially rectangular shape or a substantially circular shape. The convex structure 22 may be formed integrally with the base 21, or the convex structure 22 separate from the base 21 may be attached to the first surface 21 A of the base 21. It may be

  The size of the convex structure portion 22 is appropriately set in accordance with a product or the like manufactured through an imprinting process using the imprint mold 1 (see FIG. 2E). For example, a 34 mm × 26 mm substantially rectangular convex structure 22 can be mentioned.

The height T ₂₂ (see FIG. 4) of the convex structure 22 is not particularly limited as long as the imprint mold 1 (see FIG. 2 (E)) can serve the purpose of including the convex structure 22; , 10 μm to 50 μm or so. In the present embodiment, “the height T 22 of the convex structure ₂₂ ” refers to the height based on the first surface 21 A of the base 21, that is, the first surface 21 A and the upper surface of the convex structure 22 1 means the length between the plane including the upper surface 221) (the length in the direction perpendicular to the first surface 21A).

  As shown in FIGS. 4 and 5, the convex structure 22 of the mold base 20 in the present embodiment has a first upper surface 221T and a second upper surface 222T located closer to the first surface 21A than the first upper surface 221T. Side surface 22S including the upper surface 22T, the first side surface 221S continuous from the outer peripheral edge 221E of the first upper surface 221T to the second upper surface 222T, and the second side surface 222S continuous from the outer peripheral edge 222E of the second upper surface 222T to the first surface And. In other words, the convex structure 22 of the mold base 20 includes the first convex structure 221 having the first upper surface 221T and the first side surface 221S, and the second convex structure 222 having the second upper surface 222T and the second side 222S. And.

  The shape (plan view shape) of the first upper surface 221T is not particularly limited, and may be, for example, a substantially rectangular shape, a substantially circular shape, or the like. Further, the shape of the second upper surface 222T (the shape of the outer periphery in plan view) is not particularly limited, and may be, for example, a substantially rectangular shape, a substantially circular shape, or the like.

A difference between the height of the first upper surface 221T (the height T 22 of the convex structure ₂₂ ) and the height of the second upper surface 222T (the height T _{222 of} the second convex structure ₂₂₂ ), that is, the first convex structure 221 The height T ₂₂₁ of H may be about 0.5 μm to 5 μm, and preferably about 1.0 μm to 2.0 μm (see FIG. 4). If the difference in height (height T ₂₂₁ ) is less than 0.5 μm, the imprint mold 1 is bent during the transfer step of transferring the concavo-convex pattern 2 to the workpiece such as a substrate, and the outer surface of the second upper surface 222 T The peripheral edge may come in contact with the workpiece to damage the imprint mold 1 or the workpiece, or particles may be attached thereto. On the other hand, when the height difference (height T ₂₂₁ ) exceeds 5 μm, it may be difficult to form the substantially uniform hard mask layer 24 (light shielding film 3) on the first side surface 221S.

The width W _222T (see FIG. 5) of the second upper surface 222T may be 1 μm to 1000 μm, and preferably about 50 μm to 500 μm. When the width W _222T is less than 1 μm, light irradiated to the imprint resin through the imprint mold 1 in order to cure the imprint resin wraps around from the outside of the second side surface 222S, and the first upper surface There is a possibility that the imprint resin slightly protruding from the 221 T may be exposed and cured.

  In the present embodiment, the hard mask layer 24 is formed on the first upper surface 221 T, the first side surface 221 S, the second upper surface 222 T and the second side surface 222 S of the convex structure 22 of the mold base 20, and the first surface 21 A of the base 21. Is formed. Examples of the material constituting the hard mask layer 24 include metals such as chromium, titanium, tantalum, silicon, and aluminum; chromium compounds such as chromium nitride, chromium oxide, and chromium oxynitride, tantalum oxide, tantalum oxynitride, and copper oxide. Tantalum nitride, tantalum compounds such as tantalum oxynitride and titanium nitride, silicon nitride, silicon oxynitride and the like can be used alone or in combination of two or more selected arbitrarily.

  The hard mask layer 24 is patterned in a process described later (see FIG. 2C), and is used as a mask when etching the mold base 20. Therefore, it is preferable to select the constituent material of the hard mask layer 24 in consideration of the etching selectivity and the like according to the type of the mold base 20. For example, when the mold base 20 is a quartz glass substrate, a metal chromium film or the like may be suitably selected as the hard mask layer 24.

  In addition, the light shielding film 3 located on the first side surface 221S and the second upper surface 222T of the imprint mold 1 in the present embodiment is formed by leaving the hard mask layer 24 covering the first side surface 221S and the second upper surface 222T. Be done. Therefore, the hard mask layer 24 is preferably made of a material that can function as the light shielding film 3. In that sense, the hard mask layer 24 is preferably made of metal chromium or the like.

  The thickness of the hard mask layer 24 is appropriately set in consideration of the etching selectivity according to the type of the mold substrate 20, the aspect ratio of the concavo-convex pattern in the imprint mold 1 to be manufactured, and the like. For example, when the mold base 20 is a quartz glass substrate and the hard mask layer 24 is a metal chromium film, the thickness of the hard mask layer 24 may be set to about 3 nm to 20 nm.

  It does not specifically limit as a method to form the hard mask layer 24 on the convex structure part 22 of the mold base 20, For example, publicly known sputtering, PVD (Physical Vapor Deposition), CVD (Chemical Vapor Deposition), etc. Film formation methods.

The mold base 20 can be produced, for example, as follows.
First, a base material 20 ′ having a first surface 20A ′ and a second surface 20B ′ opposed thereto is prepared, and a first mask pattern 51 is formed on the first surface 20A ′ (see FIG. 3A). The base 20 ′ may be made of the same material as the material of the base 21 described above. The first mask pattern 51 plays a role of defining the second convex structure portion 222 (second upper surface 222T) of the convex structure portion 22. Therefore, the shape (planar shape) and size of the first mask pattern 51 May be appropriately set according to the shape and size of the second upper surface 222T. The constituent material of the first mask pattern 51 may be appropriately selected in consideration of the etching selectivity according to the type of the constituent material of the base 20 ′. For example, when the constituent material of the base 20 'is quartz glass, metal chromium or the like may be suitably selected as a constituent material of the first mask pattern 51.

Next, the first surface 20A ′ of the base 20 ′ is etched using the first mask pattern 51 as a mask to form a convex portion 22 ′ projecting from the first surface 21A of the base 21 (FIG. 3 (B )reference). 'Height T ₂₂ of _the' convex portion 22 may be appropriately set according to the height of the second convex portions 222 (see FIG. 5).

  Subsequently, the second mask pattern 52 is formed on the upper surface of the convex portion 22 ′ (see FIG. 3C), and the first surface 20A ′ of the base 20 ′ and the convex portion are used with the second mask pattern 52 as a mask. By etching the exposed portion of the upper surface 22 ', the convex structure 22 is formed (see FIG. 3D). The second mask pattern 52 plays a role of defining the first convex structure portion 221 (first upper surface 221T) of the convex structure portion 22. Therefore, the shape (plan view shape) and size of the second mask pattern 52 May be appropriately set according to the shape and size of the first upper surface 221T. The constituent material of the second mask pattern 52 may be appropriately selected in consideration of the etching selectivity according to the type of the constituent material of the base 20 ′. For example, when the constituent material of the substrate 20 'is quartz glass, metallic chromium or the like may be suitably selected as a constituent material of the second mask pattern 52.

  Finally, the second mask pattern 52 is removed, and the recess 23 is formed on the second surface 21B side of the base 21 as desired, whereby the mold base 20 in the present embodiment is manufactured.

  Next, the imprint resin 30 is supplied to the first upper surface 221T of the convex structure 22 (hard mask layer 24) of the mold base 20 by an inkjet method, a spin coat method, or the like (see FIG. 1B). The supply amount of the imprint resin 30 may be appropriately set in accordance with the pattern density and the like of the concavo-convex pattern 12 of the master mold 10 (see FIG. 1C).

  The imprint resin 30 (resist material) is not particularly limited, and a resin material (for example, an ultraviolet curable resin, a thermosetting resin, or the like) generally used for imprint processing can be used. The imprint resin 30 includes a release agent for easily separating the master mold 10, an adhesive for improving the adhesion of the mold base 20 to the convex structure 22 (hard mask layer 24), and the like. It may be

[Preparation of master mold]
A master mold 10 (see FIG. 1 (see FIG. 1 (see FIG. 1)) has a base 11 having a first surface 11A and a second surface 11B opposite to the first surface 11A. Prepare C).

  The material which comprises the base 11 of the master mold 10 is not specifically limited, It is general as a mold base. For example, the base 11 is a substrate generally used when manufacturing an imprint mold (for example, glass such as quartz glass, soda glass, fluorite, calcium fluoride substrate, magnesium fluoride substrate, acrylic glass, etc. Substrates, resin substrates such as polycarbonate substrates, polypropylene substrates, polyethylene substrates, and transparent substrates such as laminated substrates formed by laminating two or more substrates arbitrarily selected therefrom; such as nickel substrates, titanium substrates, aluminum substrates, etc. Metal substrate; silicon substrate, semiconductor substrate such as gallium nitride substrate, and the like).

The thickness T ₁₁ of the base 11 of the master mold 10 may be appropriately set, for example, in the range of about 300 μm to 10 mm, in consideration of strength, handling aptitude, and the like. In the present embodiment, “transparent” means that the transmittance of light having a wavelength of 300 nm to 450 nm is 85% or more, preferably 90% or more, and particularly preferably 95% or more.

  The size (size in plan view) of the base 11 of the master mold 10 is also not particularly limited, but when the base 11 is made of quartz glass, for example, the size of the base 11 is 152 mm × 152 mm It is an extent.

  It does not specifically limit as planar view shape of the base 11 of the master mold 10, For example, substantially rectangular shape, substantially circular shape, etc. are mentioned. When the master mold 10 is made of quartz glass generally used for light imprinting, the plan view shape of the base 11 is generally rectangular.

  The shape, dimensions, and the like of the concavo-convex pattern 12 formed in the pattern area set on the first surface 11A side of the base 11 of the master mold 10 are the imprint mold 1 (FIG. 2 (E (FIG. ) Can be appropriately set according to the shape, dimensions, etc. required by For example, examples of the shape of the concavo-convex pattern 12 include a line and space shape, a pillar shape, a hole shape, and a lattice shape. In the illustrated example, the concavo-convex pattern 12 is a concave pattern. The dimension of the concavo-convex pattern 12 may be, for example, about 10 nm to 200 nm. The size of the pattern region in which the concavo-convex pattern 12 is formed is a size that can be physically included in the first upper surface 221 T of the convex structure 22 of the mold base 20. The size is slightly smaller than the size of the upper surface 221T, and is about 1 μm to 100 μm from the outer peripheral edge 221E of the first upper surface 221T.

  The concavo-convex pattern 12 may be a resist pattern formed of a negative or positive electron beam reactive resist material, an ultraviolet reactive resist material, or the like, using a known method such as, for example, electron beam lithography or photolithography. And through the etching process.

[Formation of resist pattern]
The concavo-convex pattern 12 formed on the first surface 11 A of the master mold 10 is brought into contact with the imprint resin 30, and the concavo-convex pattern 12 is filled with the imprint resin 30. Then, the concavo-convex pattern 12 of the master mold 10 is transferred to the imprint resin 30 by curing the imprint resin 30 (see FIG. 1C).

  Subsequently, the master mold 10 is pulled away from the cured imprint resin 30 (see FIG. 1D). Thereby, the concavo-convex pattern 12 of the master mold 10 is transferred to the first upper surface 221 (hard mask layer 24) of the convex structure 22 of the mold base 20, and the concavo-convex pattern 32 including a plurality of concave portions and convex portions is formed. A resist pattern 31 can be formed. The concavo-convex pattern 32 included in the resist pattern 31 has a shape in which the concavo-convex pattern 12 of the master mold 10 is inverted. In the illustrated example, the concavo-convex pattern 32 is a convex pattern.

  An outer peripheral edge of a concave portion or a convex portion located on the outermost side of the concavo-convex pattern 32 of the resist pattern 31 formed on the first upper surface 221T (hard mask layer 24) of the convex structure 22 and an outer peripheral edge of the first upper surface 221T of the convex structure 22 The distance between it and 221E (the distance in the direction parallel to the first upper surface 221A) is about 1 μm to 100 μm.

[Formation of Inversion Layer]
Next, a reverse layer forming material is applied to the upper surface 22T (hard mask layer 24) of the convex structure 22 of the mold base 20 so as to cover the concavo-convex pattern 32 of the resist pattern 31 to form a reverse layer 41 ( See FIG. 1 (E)). The inversion layer 41 is formed to cover the resist pattern 31 and the hard mask layer 24 located on the first side surface 221S and the second upper surface 222T.

  As a method of forming the inversion layer 41 on the upper surface 22T of the convex structure 22, for example, a method of supplying an inversion layer forming material on the upper surface 22T (resist pattern 31) of the convex structure 22 by spin coating, In addition to the method of discretely supplying the droplets of the reversal layer forming material onto the upper surface 22T (resist pattern 31) of the convex structure 22 from the ink jet nozzle, the plate printing method such as stencil printing (screen printing), die coating method, etc. Can be mentioned.

  After the etching process of the resist pattern 31 described later, a reversal layer residue 43 for preventing the hard mask layer 24 covering the second upper surface 222T and the first side surface 221S from being exposed is formed from the reversal layer 41 (FIG. B) see). The inversion layer residue 43 covers the first side surface 221S and the second upper surface 222T when forming the concavo-convex pattern 2 on the first upper surface 221T by an etching process using the hard mask pattern 25 formed from the hard mask layer 24 as a mask. It can function as a protective film to prevent the hard mask residue 26 from being exposed to etching. Therefore, as the inversion layer forming material, a material having a sufficient etching selectivity with respect to the material forming the convex structure 22 can be used.

The inversion layer forming material is also a material forming the inversion layer pattern 42 located on the first upper surface 221T, which is formed in a process described later, and the inversion layer pattern 42 is a resist pattern using the inversion layer 41 as a mask. It is formed by the etching process 31 (see FIG. 2B). Therefore, as the inversion layer forming material, a material having sufficient etching selectivity with the imprint resin 30 constituting the resist pattern 31 can be used. For example, as the reversal layer forming material, an active energy ray curable resin (for example, an electron beam curable resin, an ultraviolet curable resin, etc.) containing silicon such as Si, SiO ₂ , SiN, etc. may be mentioned.

  In forming the inversion layer 41, the height of the portion located on the second upper surface 222T is made equal to or higher than the height of the portion located on the first upper surface 221T (resist pattern 31). preferable. Since the inversion layer residue 43 is formed from the portion located on the second upper surface 222T, the hard mask residue 26 covering the first side surface 221S and the second upper surface 222T is etched because the height of the portion is sufficiently high. It can fully function as a protective film to prevent exposure.

  When the inversion layer forming material is supplied or coated on the upper surface 22T (resist pattern 31) of the convex structure 22, the supply amount of the inversion layer forming material according to the pattern density and the like of the concavo-convex pattern 32 in the surface of the resist pattern 31. Alternatively, the application amount may be controlled. By controlling the supply amount or the application amount of the inversion layer forming material according to the pattern density of the concavo-convex pattern 32 or the like, the film thickness of the inversion layer 41 formed on the resist pattern 31 can be made substantially uniform.

[Formation of Inversion Layer Pattern]
The inversion layer 41 is cured by irradiating the inversion layer 41 with active energy rays such as ultraviolet light. At this time, the inversion layer 41 may be cured in a state where a flat plate is pressed against the inversion layer 41 from above. When droplets of the inversion layer forming material are supplied onto the resist pattern 31 by an inkjet method or the like, the droplets of the inversion layer forming material are naturally wetted by capillary force so that the recesses of the concavo-convex pattern 32 of the resist pattern 31 are filled. Although it spreads, a region in which the inversion layer forming material is not present partially on the resist pattern 31 can also be formed. In addition, even if the material for forming the inversion layer spreads all over the resist pattern 31, the height of the inversion layer 41 located on the second upper surface 222T may be insufficient. Therefore, by bringing a flat plate into contact with the droplets of the inversion layer forming material supplied to the resist pattern 31, the inversion layer forming material can be spread on the resist pattern 31 and the upper surface of the inversion layer 41 is smoothed. be able to. In addition, the inversion layer 41 having a sufficient height can be reliably formed on the second upper surface 222T.

  When the reversal layer forming material is applied on the resist pattern 31 by a spin coating method or the like, the reversal layer 41 whose upper surface is corrugated along the concavo-convex pattern 32 of the resist pattern 31 is formed. By pressing a flat plate against the inversion layer 41, the upper surface of the inversion layer 41 can be smoothed, and the inversion layer 41 having a sufficient height can be reliably formed on the second upper surface 222T.

  The flat plate to be pressed (contacted) with the reversal layer forming material is not particularly limited, but if the reversal layer forming material is irradiated with active energy rays through the flat plate in order to cure the reversal layer 41 It is preferable to use a transparent substrate such as quartz glass. Of course, if the base 21 of the mold base 20 is transparent and the active energy ray can be irradiated from the side of the second surface 21B of the base 21 to cure the inversion layer 41, it is opaque as the above flat plate ( A substrate with low transmittance (eg, less than 85%) of active energy rays may be used. Furthermore, the surface roughness (Ra) of the surface on the side to be pressed (contacted) to the inversion layer forming material in a flat plate is preferably 0.1 nm to 1.0 nm, and 0.2 nm to 0.5 nm Is more preferred. A flat plate having a surface whose surface roughness (Ra) is less than 0.1 nm is originally difficult to produce. On the other hand, when the surface roughness (Ra) exceeds 1.0 nm, the dimensional accuracy and the like of the concavo-convex pattern 2 of the imprint mold 1 to be manufactured may be deteriorated.

  A mold release layer or the like may be formed on the surface of the flat plate on the side to be pressed (contacted) with the inversion layer forming material, in order to facilitate separation from the hardened inversion layer 41.

[Formation of Inversion Layer]
The inversion layer 41 formed as described above is filled in the concave portion of the concavo-convex pattern 32 of the resist pattern 31 and is also present on the convex portion. The inversion layer 41 is etched to such an extent that the inversion layer 41 present on the convex portion is removed to expose the top of the convex portion and the inversion layer 41 filled in the concave portion is left (FIG. 2A) reference).

  As a method of etching the inversion layer 41, a dry etching method using an etching gas which can be appropriately selected according to the type of inversion layer forming material constituting the inversion layer 41 can be employed. As an etching gas, for example, a fluorine-based gas, oxygen, argon, a mixed gas of oxygen and argon, or the like can be used.

  Subsequently, the exposed resist pattern 31 (convex portion) is removed by a dry etching method using the inversion layer 41 filled in the concave portion as a mask (see FIG. 2B). As described above, since the inversion layer forming material forming the inversion layer 41 is a material having a sufficient etching selectivity with the imprint resin forming the resist pattern 31, the material of the resist pattern 31 (convex portion) is By the removal, the inversion layer pattern 42 can be formed on the first upper surface 221T (hard mask layer 24) of the convex structure portion 22. The inversion layer pattern 42 is a pattern in which the concavo-convex pattern 32 of the resist pattern 31 is reversed and has the same concavo-convex structure as the concavo-convex pattern 12 of the master mold 10. In the illustrated example, the inversion layer pattern 42 is a concave pattern. In addition, the inversion layer 41 located on the second upper surface 222T remains even after the removal of the resist pattern 31. Thereby, the inversion layer residue 43 is formed on the second upper surface 222T.

  The etching gas for etching the resist pattern 31 may be appropriately selected according to the type of imprint resin 30 constituting the resist pattern 31. For example, chlorine gas, oxygen, argon, and a mixture of oxygen and argon Gas can be used. Although a gas different from the etching gas for etching the inversion layer 41 may be used as an etching gas for etching the resist pattern 31, a constituent material of the inversion layer 41 (for example, Si-containing ultraviolet curable resin) Since the etching selectivity between the resist pattern 31 and the constituent material of the resist pattern 31 (for example, an ultraviolet curable resin) is sufficiently large, the same gas may be used as the etching gas for the both. By using the same gas as both etching gases, the steps shown in FIGS. 2A and 2B can be implemented as the same step.

[Form hard mask pattern]
A hard mask formed on the first upper surface 221T of the convex structure 22 of the mold base 20 by dry etching using, for example, a chlorine-based (Cl ₂ + O ₂ ) etching gas, using the inversion layer pattern 42 as a mask The layer 24 is etched to form a hard mask pattern 25 (see FIG. 2C). At this time, since the hard mask layer 24 located on the first side surface 221S and the second upper surface 222T is covered by the inversion layer residue 43 as a protective film, it remains as a hard mask residue 26 without being etched.

[Etching of mold substrate]
Finally, dry etching is applied to the mold base 20 using the hard mask pattern 25 as a mask to form the concavo-convex pattern 2 on the first upper surface 221T of the convex structure 22 (see FIG. 2D). At this time, since the hard mask residue 26 located on the first side surface 221S and the second upper surface 222T is covered with the inversion layer residue 43, it remains without being etched. Then, the hard mask pattern 25 is removed. In this manner, the imprint mold 1 including the first convex structure 221 and the second convex structure 222 and having the light shielding film 3 formed on the first side surface 221S and the second upper surface 222T is manufactured (FIG. 2). See (E)).

  According to the method for manufacturing an imprint mold according to the present embodiment, the light shielding film can be reliably formed on the second upper surface 222T and the first side surface 221S of the convex structure 22 of the mold base 20, so It is possible to suppress curing of the imprint resin which has been protruded outside from the concave and convex pattern forming region of the convex structure portion at the time of the imprint processing using the mold 1.

  Further, according to the method for manufacturing an imprint mold according to the present embodiment, using the so-called inversion process, using the master mold 10 having the concave pattern as the concave and convex pattern 12, the concave pattern as the concave and convex pattern 2 is obtained. The imprint mold 1 which has it can be manufactured. Therefore, even if the master mold 10 and the imprint mold 1 are repeatedly used for the imprinting process, it is difficult to cause a defect or the like of the concavo-convex pattern 12 and 2, and the life of the master mold 10 and the imprint mold 1 can be extended.

  The embodiments described above are described to facilitate the understanding of the present invention, and are not described to limit the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents that fall within the technical scope of the present invention.

  In the above embodiment, a mold base in which the hard mask layer 24 is formed on the first surface 21A of the base 21 and the first upper surface 221T, the first side 221S, the second upper surface 222T and the second side 222S of the convex structure 22. Although the material 20 has been described as an example, it is not limited to this embodiment. The hard mask layer 24 may be formed at least on the first upper surface 221T, the first side surface 221S, and the second upper surface 222T of the convex structure 22, and the first surface 21A of the base 21 and the second side of the convex structure 22 It does not need to be formed in 222S.

  The present invention is useful as a method of manufacturing an imprint mold used in a manufacturing process of a semiconductor device or the like.

DESCRIPTION OF SYMBOLS 1 imprint mold 2 uneven pattern 3 light shielding film 10 master mold 11 base 11A first surface 11B second surface 12 uneven pattern 20 mold base 21 base 21A first surface 21B first 2 surface 22 convex structure portion 221 T first upper surface 222 T second upper surface 24 hard mask layer 25 hard mask pattern 26 hard mask residue 31 resist pattern 41 inversion layer 42 inversion layer pattern 43 inversion layer residue

Claims (8)

A base having a first surface and a second surface opposite to the first surface, a convex structure projecting from the first surface of the base, the first surface of the base, and an upper surface of the convex structure A substrate preparation step of preparing a mold substrate comprising a hard mask layer covering side surfaces;
A transfer pattern forming step of forming a transfer pattern on the convex structure by transferring the concavo-convex pattern of the master mold to the imprint resin applied on the upper surface of the convex structure;
An inversion layer forming step of forming an inversion layer covering the transfer pattern by supplying an inversion layer forming material onto the transfer pattern;
An etch back step of etching the inversion layer so as to expose a top of the convex portion in a state in which the inversion layer is embedded in the concave portion of the transfer pattern;
An inversion layer pattern forming step of forming an inversion layer pattern on the upper surface of the convex structure portion by etching the transfer pattern using the etched inversion layer as a mask;
Forming a hard mask pattern on the upper surface of the convex structure by etching the hard mask layer using the inversion layer pattern as a mask;
Etching the convex structure using the hard mask pattern as a mask to form a concavo-convex structure on the top surface of the convex structure;
The upper surface of the convex structure portion is a first upper surface including a pattern region where the uneven structure can be formed, and a non-upper surface located closer to the first surface side of the base than the first upper surface and surrounding the periphery of the pattern region And a second top surface including a pattern area,
The inversion layer pattern is formed in the pattern area of the first upper surface,
Etching the inversion layer so as to leave the inversion layer covering the second upper surface in the etch back step;
An imprint mold for leaving the hard mask layer on the second upper surface by etching the hard mask layer using the inversion layer remaining on the second upper surface as a mask in the hard mask pattern forming step Manufacturing method. The inversion layer according to claim 1, wherein in the inversion layer forming step, the inversion layer is formed such that the height of the inversion layer on the second upper surface is higher than the height of the inversion layer on the first upper surface. Method of manufacturing an imprint mold The side surface of the convex structure portion is a first side surface continuous from the outer peripheral edge of the first upper surface to the second upper surface, and a second side surface continuous from the outer peripheral edge of the second upper surface to the first surface of the base Including
The hard mask layer is formed to cover at least the first upper surface, the first side surface, and the second upper surface.
In the hard mask pattern forming step, the hard mask layer is etched using the inversion layer remaining on the second upper surface as a mask to leave the hard mask layer covering the first side surface and the second upper surface. The method for producing an imprint mold according to claim 1 or 2, The said imprint mold is used for the optical imprint process which hardens imprint resin by irradiating a light ray through the said imprint mold,
The method for manufacturing an imprint mold according to any one of claims 1 to 3, wherein the hard mask layer is made of a material capable of blocking the light beam. The method for manufacturing an imprint mold according to any one of claims 1 to 4, wherein a difference in height between the first upper surface and the second upper surface is 0.5 μm to 5 μm. The manufacturing of the imprint mold according to any one of claims 1 to 5, wherein a length between an outer edge of the first upper surface and an outer edge of the second upper surface is 1 μm to 1000 μm in a plan view of the mold base. Method. The method for producing an imprint mold according to any one of claims 1 to 6, wherein the inversion layer forming material contains Si and a thermosetting resin. The size of the concavo-convex area in which the concavo-convex pattern is formed in the master mold is a size physically included in the first upper surface of the convex structure. Method of manufacturing an imprint mold

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