JP7060836B2 - Imprint mold manufacturing method - Google Patents

Description

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

In recent years, in the manufacturing process of semiconductor devices (for example, semiconductor memory, etc.), a mold member (imprint mold) having an uneven pattern formed on the surface of a substrate is used, and the uneven pattern is transferred to a workpiece such as a substrate at the same magnification. Nanoimprint technology, which is a pattern formation technology, is used.

The mold having an uneven pattern used in the nanoimprint technique can be manufactured by, for example, electron beam lithography or the like. The mold manufactured in this way has a concavo-convex pattern such as a highly accurate shape and dimensions. However, the manufacturing cost of the mold becomes high, and after a predetermined number of transfer steps, the transfer pattern formed on the workpiece (resin for imprint, etc.) becomes defective, or the uneven pattern of the mold becomes uneven. May be damaged.

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

By the way, in recent years, a technique for applying a so-called inversion process to a nanoimprint technique has been proposed (see Patent Document 2 and Non-Patent Document 1). This inversion process includes a step of forming an inversion layer on the transfer pattern on the substrate to which the uneven pattern of the mold is transferred, a step of etching back the inversion layer to expose the top of the transfer pattern, and a remaining inversion layer. Includes a step of etching the transfer pattern using the above as a mask. By etching the substrate using the inversion layer obtained by this inversion process as a mask, the uneven pattern of the mold is transferred to the substrate. By utilizing the inversion process for nanoimprint technology, it becomes possible to produce a replica mold having an uneven pattern having the same shape as the master mold. For example, when a replica mold having a hole pattern is manufactured by nanoimprint technology, it is necessary to use a master mold having a pillar pattern in which physical strength is an issue, but by applying an inversion process, the replica mold has a hole pattern. Using the master mold, it is possible to manufacture a replica mold having a hole pattern.

International Publication No. 2011/155602 Pamphlet Japanese Unexamined Patent Publication No. 2009-38085

"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, an ultraviolet curable resin having a sufficient selectivity with respect to the imprint resin layer is applied as a material constituting the inverted layer by a spin coating method to obtain an ultraviolet curable resin layer. It is formed. Since the ultraviolet curable resin layer formed by the spin coat method has slight irregularities on the surface due to the influence of the uneven pattern transferred to the imprint resin layer, a flat quartz substrate is pressed against the ultraviolet curable resin layer. As a result, the ultraviolet curable resin layer is flattened, and the inverted layer is formed by irradiating the ultraviolet curable resin layer with ultraviolet rays in that state.

Consider applying the above reversal process to the replica mold manufacturing process. In the usual nanoimprint technique, if the uneven pattern of the master mold is a concave pattern such as a hole pattern, the uneven pattern of the replica mold is a convex pattern such as a pillar pattern. Convex patterns such as pillar patterns, especially convex patterns with dimensions of about 20 nm to 40 nm, have problems with physical strength. Therefore, from the viewpoint of the life of master molds and replica molds, both master molds and replica molds are available. In both cases, it is desirable to have a concave pattern such as a hole pattern as the uneven pattern. From such a viewpoint, it can be said that it is very useful if the inversion process can be applied to the manufacturing process of the replica mold.

Usually, the mold base material includes a base portion having a first surface and a second surface facing the first surface, and a convex structure portion (so-called mesa structure) protruding from the first surface and forming an uneven pattern. When the uneven pattern of the master mold is transferred to the imprint resin layer on the convex structure of the mold base material and the ultraviolet curable resin is applied onto the imprint resin layer by the spin coating method to form an imprint. The film thickness of the outer peripheral edge of the inverted layer formed on the resin layer is larger than the film thickness of the inner periphery thereof. That is, the film thickness unevenness occurs in the inversion layer formed on the imprint resin layer.

In the replica mold, the uneven pattern may be formed very close to the outer peripheral edge on the convex structure portion, so that the film thickness of the outer peripheral edge of the inverted layer formed on the imprint resin layer is the inner film. If the thickness is increased, the dimensional accuracy of the uneven pattern formed on the convex structure portion by the etching process using the inverted layer as a mask is lowered. In particular, the dimensional accuracy of the uneven pattern located near the outer peripheral edge of the convex structure portion is significantly reduced.

On the other hand, during the imprint process using the replica mold having the convex structure portion, there is a problem that the imprint resin protrudes from the top of the convex structure portion to the outside and rises along the side surface of the convex structure portion. The imprint resin protruding to the outside of the convex structure portion is cured together with the imprint resin filled in the uneven pattern. As a result, when the imprint process is performed by the so-called step-and-repeat method, it is necessary to separate the imprint area so that the imprint area does not protrude to the outside of the convex structure portion and overlap with the cured imprint resin. The number of times the imprint process can be performed on the transfer substrate is limited.

In addition, if the imprint resin that protrudes to the outside of the convex structure and rises along the side surface and is cured comes into contact with the imprint mold, the imprint mold may be damaged or the cured imprint resin may be defective. There is also a possibility that foreign matter may be generated.

In order to solve such a problem, by forming a light-shielding film continuous from the side surface of the convex structure portion so as to surround the outside of the convex structure portion, the imprint resin protruding to the outside of the convex structure portion is not cured. The technology to make it is proposed. However, it is extremely difficult to form a uniform light-shielding film on the side surface of the convex structure portion having a height of about 10 μm to 50 μm, and there is a problem that a film-forming defect is generated. In the light-shielding film in which this film-forming defect occurs, there is a problem that a sufficient light-shielding effect cannot be obtained and the imprint resin protruding to the outside of the convex structure portion is cured.

In view of the above problems, in the present disclosure, a concavo-convex structure can be formed on the convex structure portion by an inversion process with high accuracy, and the imprint resin protruding outward from the concavo-convex pattern forming region of the convex structure portion is cured. It is an object of the present invention to provide a method for producing an imprint mold capable of suppressing the above.

In order to solve the above problems, as one embodiment of the present disclosure, a base portion having a first surface and a second surface facing the first surface, and a convex structure portion of the base portion protruding from the first surface are provided. A base material preparation step for preparing a mold base material including the first surface of the base portion and a hard mask layer covering the upper surface and the side surface of the convex structure portion, and an imprint resin applied to the upper surface of the convex structure portion. A transfer pattern forming step of forming a transfer pattern including concave portions and convex portions on the convex structure portion by transferring the uneven pattern of the master mold to the above, and supplying an inverted layer forming material on the transfer pattern, described above. The inversion layer forming step of forming the inversion layer covering the transfer pattern, and the inversion layer so as to expose the top of the convex portion of the transfer pattern in a state where the inversion layer is embedded in the recess 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, and the inversion layer pattern. By etching the hard mask layer with the above as a mask, a hard mask pattern forming step of forming a hard mask pattern on the upper surface of the convex structure portion, and by etching the convex structure portion with the hard mask pattern as a mask. It has a concavo-convex structure forming step of forming a concavo-convex structure on the upper surface of the convex structure portion, and the upper surface of the convex structure portion has a first upper surface including a pattern region in which the concavo-convex structure can be formed and the first upper surface. Is also located on the first surface side of the base and includes a second upper surface including a non-patterned region surrounding the pattern region, and the inverted layer pattern is formed in the pattern region of the first upper surface. In the etch back step, the inverted layer is etched so as to leave the inverted layer covering the second upper surface, and in the hard mask pattern forming step, the inverted layer remaining on the second upper surface is formed. Provided is a method for manufacturing an imprint mold in which the hard mask layer is left on the second upper surface by etching the hard mask layer as a mask.

In the inversion layer forming step, the inversion layer may be formed so 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 may be formed. The side surface of the portion includes 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 portion. The hard mask layer is formed so as 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 forming step. By etching the hard mask layer using the layer as a mask, the hard mask layer covering the first side surface and the second upper surface may remain.

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

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

The material for forming the inverted layer may contain Si and a thermosetting resin, and the size of the concavo-convex region in which the concavo-convex pattern is formed in the master mold is physically determined on the first upper surface of the convex structure portion. Any size may be included.

According to the present disclosure, it is possible to form a concavo-convex pattern on the convex structure portion by an inversion process with high accuracy, and it is possible to suppress the imprint resin protruding outward from the concavo-convex pattern forming region of the convex structure portion from being cured. It is possible to provide a method for manufacturing an imprint mold.

1 (A) to 1 (E) are process flow charts showing each step of the imprint mold manufacturing method according to the embodiment of the present disclosure in a cut end view. 2 (A) to 2 (E) are process flow charts following FIG. 1 (E) showing each step of the imprint mold manufacturing method according to the embodiment of the present disclosure in a cut end view. 3 (A) to 3 (E) are process flow charts showing each step of the method for manufacturing a molded base material according to the embodiment of the present disclosure in a cut end view. FIG. 4 is a partially enlarged cut end view showing a schematic configuration of a convex structure portion of a mold base material according to an embodiment of the present disclosure. FIG. 5 is a plan view showing a schematic configuration of a convex structure portion of a mold base material 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, in order to facilitate understanding, the shape, scale, aspect ratio, etc. of each part may be changed or exaggerated from the actual product. The numerical range represented by using "-" in the present specification and the like means a range including each of the numerical values described before and after "-" as a lower limit value and an upper limit value. In the present specification and the like, terms such as "film", "sheet", and "board" are not distinguished from each other based on the difference in designation. For example, "board" is a concept that also includes members that may be commonly referred to as "sheets" or "films".

1 (A) to 1 (E) are process flow diagrams showing each process of the manufacturing method of the imprint mold according to the present embodiment in a cut end plan, and FIGS. 2 (A) to 2 (E) are the present. It is a process flow diagram following FIG. 1 (E) which shows each process of the manufacturing method of the imprint mold which concerns on embodiment in the cut end plan, and FIGS. It is a process flow diagram which shows each process of the manufacturing method of a base material by the cut end view, and FIG. FIG. 5 is a plan view showing a schematic configuration of the convex structure portion of the mold base material in the present embodiment.

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

The material constituting the base 21 of the mold base material 20 is not particularly limited, and is generally used as a mold base material. For example, the base 21 is a glass such as a substrate generally used in manufacturing an imprint mold (for example, quartz glass, soda glass, fluorite, calcium fluoride substrate, magnesium fluoride substrate, acrylic glass, etc.). Transparent substrates such as substrates, polycarbonate substrates, polypropylene substrates, resin substrates such as polyethylene substrates, and laminated substrates made by laminating two or more substrates arbitrarily selected from these; nickel substrates, titanium substrates, aluminum substrates, etc. It may be composed of a metal substrate; a semiconductor substrate such as a silicon substrate or a gallium nitride substrate). In the present embodiment, "transparent" means that the transmittance of light rays 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 21 of the mold base material 20 can be appropriately set in the range of, for example, about 300 μm to 10 mm in consideration of strength, handling suitability, and the like. The size of the base 21 of the mold base material 20 (the size in a plan view) 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.

The plan view shape of the base portion 21 of the mold base material 20 is not particularly limited, and examples thereof include a substantially rectangular shape and a substantially circular shape. When the imprint mold 1 (see FIG. 2E) manufactured in the present embodiment is made of quartz glass generally used for optical imprinting, the plan view shape of the base 21 is usually substantially rectangular. The shape.

The convex structure portion 22 protruding from the first surface 21A of the base portion 21 of the mold base material 20 is provided substantially in the center of the base portion 21 (first surface 21A) in a plan view. The shape of the convex structure portion 22 can be exemplified by a substantially rectangular shape, a substantially circular shape, or the like. The convex structure portion 22 may be integrally configured with the base portion 21, or the convex structure portion 22 separate from the base portion 21 may be attached to the first surface 21A of the base portion 21. It may be.

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

The height T ₂₂ (see FIG. 4) of the convex structure portion 22 is not particularly limited as long as the imprint mold 1 (see FIG. 2 (E)) can serve the purpose of providing the convex structure portion 22, and is not particularly limited. It can be set to about 10 μm to 50 μm. In the present embodiment, the "height T ₂₂ of the convex structure portion 22" is the height based on the first surface 21A of the base portion 21, that is, the first surface 21A and the upper surface of the convex structure portion 22 (the first surface). 1 It shall mean 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 portion 22 of the mold base material 20 in the present embodiment has a first upper surface 221T and a second upper surface 222T located on the first surface 21A side of the first upper surface 221T. A side surface 22S including an upper surface 22T having a first side surface 221S continuous from the outer peripheral edge 221E of the first upper surface 221T to the second upper surface 222T and a second side surface 222S continuous from the outer peripheral edge 222E of the second upper surface 222T to the first surface 21A. And have. In other words, the convex structure portion 22 of the mold base material 20 has a first convex structure portion 221 having a first upper surface 221T and a first side surface 221S, and a second convex structure portion 222 having a second upper surface 222T and a second side surface 222S. And have.

The shape (planar 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 a plan view) is also not particularly limited, and may be, for example, a substantially rectangular shape, a substantially circular shape, or the like.

The difference between the height of the first upper surface 221T (height T _{22 of the convex structure portion 22} ) and the height of the second upper surface 222T (height T ₂₂₂ of the second convex structure portion 222), that is, the first convex structure portion 221. The height T ₂₂₁ may be about 0.5 μm to 5 μm, preferably about 1.0 μm to 2.0 μm (see FIG. 4). If the height difference (height T ₂₂₁ ) is less than 0.5 μm, the imprint mold 1 bends during the transfer process of transferring the uneven pattern 2 to the workpiece such as a substrate, and the imprint mold 1 bends outside the second upper surface 222T. The peripheral edge may come into contact with the work piece to damage the imprint mold 1 or the work piece, and thereby particles may adhere to the imprint mold 1. On the other hand, if the height difference (height T ₂₂₁ ) exceeds 5 μm, it may be difficult to form a 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, preferably about 50 μm to 500 μm. If the width W _222T is less than 1 μm, the light irradiated to the imprint resin via 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 thereof. There is a risk that the imprint resin that slightly protrudes from the 221T will be exposed to light and cured.

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

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

Further, 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. Will 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 metallic chromium or the like.

The thickness of the hard mask layer 24 is appropriately set in consideration of the etching selection ratio according to the type of the mold base material 20, the aspect ratio of the uneven pattern in the imprint mold 1 to be manufactured, and the like. For example, when the mold base material 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 can be set to about 3 nm to 20 nm.

The method for forming the hard mask layer 24 on the convex structure portion 22 of the mold base material 20 is not particularly limited, and for example, known examples such as sputtering, PVD (Physical Vapor Deposition), and CVD (Chemical Vapor Deposition). The film forming method of is mentioned.

The mold base material 20 can be manufactured, for example, as follows.
First, a base material 20'having a first surface 20A'and a second surface 20B' facing the first surface 20A'is prepared, and a first mask pattern 51 is formed on the first surface 20A' (see FIG. 3A). The base material 20'may be made of the same kind of material as the material of the base portion 21 described above. Since 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, the shape (planar view shape) and size of the first mask pattern 51 Can be appropriately set according to the shape and size of the second upper surface 222T. The constituent material of the first mask pattern 51 can be appropriately selected in consideration of the etching selection ratio according to the type of the constituent material of the base material 20'. For example, when the constituent material of the base material 20'is quartz glass, metallic chromium or the like can be suitably selected as the constituent material of the first mask pattern 51.

Next, by etching the first surface 20A'of the base material 20'with the first mask pattern 51 as a mask, a convex portion 22'protruding from the first surface 21A of the base portion 21 is formed (FIG. 3 (B). )reference). The height T _22'of the convex portion 22'can be appropriately set according to the height of the second convex structure portion 222 (see FIG. 5).

Subsequently, a second mask pattern 52 is formed on the upper surface of the convex portion 22'(see FIG. 3C), and the first surface 20A'and the convex portion of the base material 20'using the second mask pattern 52 as a mask. The convex structure portion 22 is formed by etching the exposed portion of the upper surface of the 22'(see FIG. 3D). Since 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, the shape (planar view shape) and size of the second mask pattern 52 Can be appropriately set according to the shape and size of the first upper surface 221T. The constituent material of the second mask pattern 52 can be appropriately selected in consideration of the etching selection ratio according to the type of the constituent material of the base material 20'. For example, when the constituent material of the base material 20'is quartz glass, metallic chromium or the like can be preferably selected as the constituent material of the second mask pattern 52.

Finally, the mold base material 20 according to the present embodiment is produced by removing the second mask pattern 52 and, if desired, forming the recessed portion 23 on the second surface 21B side of the base portion 21.

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

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

[Preparation of Master Mold]
A master mold 10 having a concavo-convex pattern 12 formed in a pattern region set on a base 11 having a first surface 11A and a second surface 11B facing the first surface 11A and a first surface 11A of the base 11 (FIG. 1 (FIG. 1). See C)).

The material constituting the base 11 of the master mold 10 is not particularly limited, and is generally used as a mold base material. For example, the base 11 is a glass such as a substrate generally used in manufacturing an imprint mold (for example, quartz glass, soda glass, fluorite, calcium fluoride substrate, magnesium fluoride substrate, acrylic glass, etc.). Transparent substrates such as substrates, polycarbonate substrates, polypropylene substrates, resin substrates such as polyethylene substrates, and laminated substrates made by laminating two or more substrates arbitrarily selected from these; nickel substrates, titanium substrates, aluminum substrates, etc. It may be composed of a metal substrate; a semiconductor substrate such as a silicon substrate or a gallium nitride substrate).

The thickness T ₁₁ of the base 11 of the master mold 10 can be appropriately set in the range of, for example, about 300 μm to 10 mm in consideration of strength, handling suitability, and the like. In the present embodiment, "transparent" means that the transmittance of light rays 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 of the base 11 of the master mold 10 (the size in a plan view) is 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. Degree.

The plan view shape of the base 11 of the master mold 10 is not particularly limited, and examples thereof include a substantially rectangular shape and a substantially circular shape. When the master mold 10 is made of quartz glass generally used for optical imprinting, the plan view shape of the base 11 is usually substantially rectangular.

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

The uneven pattern 12 masks a resist pattern composed of a negative or positive electron beam-reactive resist material, an ultraviolet-reactive resist material, or the like by using a known method such as an electron beam lithography method or a photolithography method. It can be produced through the etching process.

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

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

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

[Formation of inverted layer]
Next, an inversion layer forming material is applied to the upper surface 22T (hard mask layer 24) of the convex structure portion 22 of the mold base material 20 so as to cover the uneven pattern 32 of the resist pattern 31 to form the inversion layer 41 (the inversion layer 41 is formed). See FIG. 1 (E)). The inversion layer 41 is formed so as 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 inverted layer 41 on the upper surface 22T of the convex structure portion 22, for example, a method of supplying the inverted layer forming material onto the upper surface 22T (resist pattern 31) of the convex structure portion 22 by a spin coating method, or an inkjet method. In addition to a method of discretely supplying droplets of an inverted layer forming material from an inkjet nozzle onto the upper surface 22T (resist pattern 31) of the convex structure portion 22, a plate printing method such as stencil printing (screen printing), a die coating method, etc. Can be mentioned.

Through the etching process of the resist pattern 31, which will be described later, an inversion 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 inversion layer 41 (FIG. 2 (FIG. 2). B) See). The inverted layer residue 43 covers the first side surface 221S and the second upper surface 222T when the uneven pattern 2 is formed on the first upper surface 221T by the etching process using the hard mask pattern 25 formed from the hard mask layer 24 as a mask. It can serve as a protective film to prevent the hard mask residue 26 from being exposed to etching. Therefore, as the material for forming the inverted layer, a material having a sufficient etching selectivity with the material constituting the convex structure portion 22 can be used.

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

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

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

[Formation of inverted layer pattern]
The inverted layer 41 is cured by irradiating the inverted layer 41 with active energy rays such as ultraviolet rays. At this time, the inverted layer 41 may be cured while the flat plate is pressed against the inverted layer 41 from above. When a droplet of the inverted layer forming material is supplied onto the resist pattern 31 by an inkjet method or the like, the droplet of the inverted layer forming material is naturally wetted by the capillary force so as to be filled in the concave portion of the uneven pattern 32 of the resist pattern 31. Although it spreads, a region on the resist pattern 31 in which the material for forming the inverted layer is not partially formed may be formed. Further, even if the inversion layer forming material is spread over the entire resist pattern 31, the height of the inversion layer 41 located on the second upper surface 222T may be insufficient. Therefore, by bringing the flat plate into contact with the droplets of the inverted layer forming material supplied to the resist pattern 31, the inverted layer forming material can be wetted and spread on the resist pattern 31, and the upper surface of the inverted layer 41 is smoothed. be able to. Further, the inverted layer 41 having a sufficient height can be surely formed on the second upper surface 222T.

When a material for forming an inverted layer is applied onto the resist pattern 31 by a spin coating method or the like, an inverted layer 41 having a wavy upper surface is formed along the uneven pattern 32 of the resist pattern 31. By pressing the 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 inverted layer forming material is not particularly limited, but if the inverted layer forming material is irradiated with active energy rays via the flat plate in order to cure the inverted layer 41. , It is preferable to use a transparent substrate such as quartz glass. Of course, if the base 21 of the mold base material 20 is transparent and the inversion layer 41 can be cured by irradiating the inversion layer 41 with active energy rays from the second surface 21B side of the base 21, the flat plate is opaque (as described above). A substrate or the like having a low transmittance of active energy rays (for example, less than 85%) may be used. Further, the surface roughness (Ra) of the surface of the flat plate on the side pressed (contacted) with the inverted layer forming material is preferably 0.1 nm to 1.0 nm, preferably 0.2 nm to 0.5 nm. Is more preferable. A flat plate having a surface with a surface roughness (Ra) of less than 0.1 nm is difficult to produce in the first place. On the other hand, if the surface roughness (Ra) exceeds 1.0 nm, the dimensional accuracy of the uneven pattern 2 of the manufactured imprint mold 1 may deteriorate.

A mold release layer or the like for facilitating separation from the cured inversion layer 41 may be formed on the surface of the flat plate on the side pressed (contacted) with the inversion layer forming material.

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

As a method for etching the inverted layer 41, a dry etching method using an etching gas that can be appropriately selected depending on the type of the inverted layer forming material constituting the inverted layer 41 can be adopted. As the 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 inverted layer 41 filled in the concave portion as a mask (see FIG. 2B). As described above, since the inversion layer forming material constituting the inversion layer 41 is a material having a sufficient etching selectivity with the imprint resin constituting the resist pattern 31, the resist pattern 31 (convex portion) has a sufficient etching selectivity. By removal, the inverted 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 uneven pattern 32 of the resist pattern 31 is inverted and has the same uneven structure as the uneven pattern 12 of the master mold 10. In the illustrated example, the inverted layer pattern 42 is a concave pattern. Further, the inversion layer 41 located on the second upper surface 222T remains even after the resist pattern 31 is removed. As a result, the inverted layer residue 43 is formed on the second upper surface 222T.

The etching gas for etching the resist pattern 31 can be appropriately selected depending on the type of the imprint resin 30 constituting the resist pattern 31, and for example, chlorine-based gas, oxygen, argon, or a mixture of oxygen and argon. Gas can be used. As the etching gas for etching the resist pattern 31, a gas different from the etching gas for etching the inverted layer 41 may be used, but the constituent material of the inverted layer 41 (for example, Si-containing ultraviolet curable resin). Since the etching selectivity between the 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 both. By using the same gas as both etching gases, the steps shown in FIGS. 2 (A) and 2 (B) can be carried out as the same step.

[Formation of hard mask pattern]
A hard mask formed on the first upper surface 221T of the convex structure portion 22 of the mold base material 20 by a dry etching process using the inverted layer pattern 42 as a mask and using, for example, a chlorine-based (Cl ₂ + O ₂ ) etching gas. The layer 24 is etched to form the 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 with the inverted layer residue 43 as the protective film, it remains as the hard mask residue 26 without being etched.

[Etching of mold base material]
Finally, the mold base material 20 is subjected to a dry etching process using the hard mask pattern 25 as a mask to form the uneven pattern 2 on the first upper surface 221T of the convex structure portion 22 (see FIG. 2D). At this time, the hard mask residue 26 located on the first side surface 221S and the second upper surface 222T remains without being etched because it is covered with the inversion layer residue 43. Then, the hard mask pattern 25 is removed. In this way, an imprint mold 1 including the first convex structure portion 221 and the second convex structure portion 222 and having a 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, since a light-shielding film can be reliably formed on the second upper surface 222T and the first side surface 221S in the convex structure portion 22 of the mold base material 20, the imprint It is possible to prevent the imprint resin protruding outward from the uneven pattern forming region of the convex structure portion from being cured during the imprint process using the mold 1.

Further, according to the method for manufacturing an imprint mold according to the present embodiment, by using a so-called inversion process, a master mold 10 having a concave pattern as a concave-convex pattern 12 is used to form a concave pattern as a concave-convex pattern 2. The imprint mold 1 having the imprint mold 1 can be manufactured. Therefore, even if the master mold 10 and the imprint mold 1 are repeatedly used for the imprint process, the unevenness patterns 12 and 2 are less likely to be damaged, and the life of the master mold 10 and the imprint mold 1 can be extended.

The embodiments described above are described for facilitating the understanding of the present invention, and are not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

In the above embodiment, the mold group is formed by forming the hard mask layer 24 on the first surface 21A of the base portion 21, the first upper surface 221T, the first side surface 221S, the second upper surface 222T, and the second side surface 222S of the convex structure portion 22. Although the material 20 has been described as an example, the present invention is not limited to this aspect. 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 portion 22, and the first surface 21A of the base portion 21 and the second side surface of the convex structure portion 22 may be formed. It does not have to be formed in 222S.

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

1 ... Imprint mold 2 ... Concavo-convex pattern 3 ... Light-shielding film 10 ... Master mold 11 ... Base 11A ... First surface 11B ... Second surface 12 ... Concavo-convex pattern 20 ... Mold base material 21 ... Base 21A ... First surface 21B ... First surface 21B ... Two surfaces 22 ... Convex structure portion 221T ... First upper surface 222T ... Second upper surface 24 ... Hard mask layer 25 ... Hard mask pattern 26 ... Hard mask residue 31 ... Resist pattern 41 ... Inverted layer 42 ... Inverted layer pattern 43 ... Inverted layer residue

Claims (8)

A base having a first surface and a second surface facing the first surface, a convex structure portion protruding from the first surface of the base portion, the first surface of the base portion, and an upper surface of the convex structure portion. A substrate preparation step of preparing a molded substrate with a hard mask layer covering the sides,
A transfer pattern forming step of forming a transfer pattern including concave portions and convex portions on the convex structure portion by transferring the uneven pattern of the master mold to the imprint resin applied to the upper surface of the convex structure portion.
An inversion layer forming step of forming an inversion layer covering the transfer pattern by supplying an inversion layer forming material on the transfer pattern.
An etch-back step of etching the inverted layer so as to expose the top of the convex portion of the transfer pattern in a state where the inverted 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.
A hard mask pattern forming step of forming a hard mask pattern on the upper surface of the convex structure portion by etching the hard mask layer using the inverted layer pattern as a mask.
It has a concave-convex structure forming step of forming a concave-convex structure on the upper surface of the convex structure portion by etching the convex structure portion using the hard mask pattern as a mask.
The upper surface of the convex structure portion is located on the first upper surface including the pattern region where the uneven structure can be formed, and on the first surface side of the base portion with respect to the first upper surface, and surrounds the periphery of the pattern region. Including the second upper surface including the pattern area,
The inverted layer pattern is formed in the pattern region on the first upper surface, and is formed.
In the etch back step, the inverted layer is etched so as to leave the inverted layer covering the second upper surface.
In the hard mask pattern forming step, an imprint mold that leaves the hard mask layer on the second upper surface by etching the hard mask layer using the inverted layer remaining on the second upper surface as a mask. Manufacturing method. The first aspect of the present invention, wherein in the inversion layer forming step, the inversion layer is formed so 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. Manufacturing method of imprint mold. The side surface of the convex structure portion includes 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 portion. Including
The hard mask layer is formed so as to at least cover the first upper surface, the first side surface, and the second upper surface.
In the hard mask pattern forming step, by etching the hard mask layer using the inverted layer remaining on the second upper surface as a mask, the hard mask layer covering the first side surface and the second upper surface remains. The method for manufacturing an imprint mold according to claim 1 or 2. The imprint mold is used for an optical imprint process in which an imprint resin is cured by irradiating a light beam through the 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 light rays. The method for manufacturing an imprint mold according to any one of claims 1 to 4, wherein the height difference between the first upper surface and the second upper surface is 0.5 μm to 5 μm. The manufacture of the imprint mold according to any one of claims 1 to 5, wherein the length between the outer edge of the first upper surface and the outer edge of the second upper surface is 1 μm to 1000 μm in a plan view of the mold base material. Method. The method for producing an imprint mold according to any one of claims 1 to 6, wherein the inverted layer forming material contains Si and a thermosetting resin. The aspect according to any one of claims 1 to 7, wherein the size of the concavo-convex region in which the concavo-convex pattern is formed in the master mold is the size physically included in the first upper surface of the convex structure portion. Manufacturing method of imprint mold.

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