JP2020077690A - Substrate for imprint mold, imprint mold, and manufacturing method thereof - Google Patents

Abstract

To provide an imprint mold capable of forming a pattern with high accuracy, a substrate for an imprint mold capable of manufacturing the imprint mold, and a method for manufacturing the imprint mold and the substrate without spending a lot of cost or time.SOLUTION: A substrate for an imprint mold includes a base material having a first surface and a second surface facing the first surface, a pattern area that is formed on the first surface of the base material, and in which an uneven pattern can be formed, and a recess formed on the second surface of the base material, and the recess includes a bottom surface and a peripheral wall surface standing from the outer peripheral edge of the bottom surface toward the second surface side, and in a projection area where the pattern area is projected on the bottom surface side of the recess, the bottom surface of the recess has substantially no inflection point.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to an imprint mold substrate, an imprint mold, and a method for manufacturing the same.

  The nanoimprint technology known as a microfabrication technology is a pattern forming technology that uses an imprint mold in which a concavo-convex pattern is formed on the surface of a base material and transfers the concavo-convex pattern onto a workpiece at the same size. In particular, along with further miniaturization of wiring patterns and the like in semiconductor devices, nanoimprint technology has attracted attention in its manufacturing process and the like.

  An imprint mold generally used in the nanoimprint technology includes, for example, a base material having a first surface and a second surface facing the first surface, a convex structure portion protruding from the first surface of the base material, and an upper surface portion of the convex structure portion. It is known that the concave and convex pattern is formed and the depression is formed on the second surface of the base material (see Patent Document 1). By using such an imprint mold, the concavo-convex pattern of the imprint mold is brought into contact with the imprint resin as the workpiece supplied onto the substrate to be transferred, so that the concavo-convex pattern is filled with the imprint resin. Then, the imprint resin is cured in that state, and then the imprint mold is separated from the cured imprint resin, whereby a pattern structure in which the concavo-convex pattern of the imprint mold is transferred is formed.

  In the releasing step of separating the imprint mold from the imprint resin, pattern defects (dimensional variation, deterioration of positional accuracy, pattern collapse, etc.) may occur due to adhesion of the imprint resin to the imprint mold. By forming the depression on the second surface of the base material of the imprint mold, the imprint mold is imprinted by curving (bending) the upper surface of the convex structure portion on which the concavo-convex pattern is formed. It can be separated from the resin, and as a result, it is possible to prevent the pattern defect from occurring.

JP, 2011-245787, A

  In the above imprint mold in which a recess is formed on the second surface of the base material, the upper surface of the convex structure is uniformly curved (bent) to effectively prevent the occurrence of the pattern defect. You can Therefore, it is an ideal structure in the imprint mold that the thickness of the substrate in the upper surface of the convex structure is uniform and that the thickness of the substrate in the area around the convex structure is uniform. It can be said that there is. That is, it is ideal that the upper surface portion of the convex structure portion, the first surface of the base material around the convex structure portion, and the bottom surface of the concave portion are parallel to each other.

  The recessed portion is generally formed by grinding (machining) the second surface of the base material, but it is difficult to hold a milling head (grinding head) used in the grinding horizontally. Due to the device factor of the grinding device (the habit of the device), undulations are present on the bottom surface of the formed recess. The undulations present on the bottom surface of the recessed portion cause a problem that a pattern defect is generated in the concave-convex pattern at the time of releasing after the concave-convex pattern is transferred to the imprint resin. Specifically, due to the undulations existing on the bottom surface of the recessed portion, the thickness of the base material in the plane of the upper surface portion (region in which the concavo-convex pattern is formed) of the convex structure portion varies. Therefore, when the imprint mold is separated from the imprint resin, it becomes difficult to maintain the mold release speed at a desired speed, and a rapid change in stress applied to the imprint resin occurs, resulting in a pattern. Defects will occur. In particular, at a position where the imprint mold is finally separated from the imprint resin (final mold release position), the imprint mold is likely to be rapidly peeled off and a large stress is applied to the imprint resin, which easily causes a pattern defect. There is. If the undulations are removed by subjecting the bottom surface of the recess formed in the grinding process to polishing or the like, and the bottom surface is formed parallel to the upper surface of the convex structure and the first surface of the base material in the periphery thereof, the above problem occurs. Can be solved, but it is not easy in terms of cost and time.

  In view of the above problems, the present disclosure provides an imprint mold capable of forming a pattern with high accuracy, a substrate for an imprint mold capable of manufacturing the imprint mold, and a method for manufacturing them without enormous cost or time. The purpose is to provide.

  In order to solve the above problems, as one embodiment of the present disclosure, a base material having a first surface and a second surface facing the first surface, and the first surface of the base material, A pattern region in which a concavo-convex pattern can be formed, and a recessed portion formed on the second surface of the base material are provided. The recessed portion extends from a bottom surface and an outer peripheral edge of the bottom surface toward the second surface side. For the imprint mold, wherein the bottom surface of the recess has substantially no inflection point in a projection area in which the pattern area is projected to the bottom surface side of the recess. A substrate is provided.

  The radius of curvature of the bottom surface of the recess in the projection region may be larger than the radius of curvature of the bottom surface outside the projection region, and the radius of curvature of the bottom surface of the recess at the center of the projection region is The maximum value can be shown in the projection area.

  The substrate may further include a convex structure portion having an upper surface portion protruding from the first surface of the base material, wherein the pattern region may be set on the upper surface portion of the convex structure portion, and the base material may be quartz. It may be made of glass.

  As one embodiment of the present disclosure, there is provided an imprint mold having an uneven pattern formed in the pattern region of the imprint mold substrate.

  As an embodiment of the present disclosure, there is provided a method of manufacturing the substrate for imprint mold, comprising a step of preparing a substrate having one surface and a facing surface facing the one surface, and grinding the facing surface of the substrate. A step of forming a recess by performing a process and a step of forming the recess by smoothing a bottom surface of the recess, and the one surface of the substrate is provided with the imprint mold substrate. For the imprint mold in which the pattern area is set and at least the bottom surface of the recess is smoothed so that there is substantially no inflection point in the projection area where the pattern area is projected to the bottom surface side of the recess. A method of manufacturing a substrate is provided.

  As one embodiment of the present disclosure, there is provided an imprint mold manufacturing method including a step of forming an uneven pattern in the pattern region of the imprint mold substrate manufactured by the above manufacturing method.

  According to the present disclosure, there are provided an imprint mold capable of forming a pattern with high accuracy, a substrate for an imprint mold capable of manufacturing the imprint mold, and a method for manufacturing them without spending a great deal of cost or time. You can

FIG. 1 is a cut end view showing a schematic configuration of an imprint mold substrate according to an embodiment of the present disclosure. FIG. 2 is a partially enlarged cut-away end view showing a schematic configuration in the vicinity of the convex structure portion of the imprint mold substrate shown in FIG. FIG. 3 is a cut end view showing a schematic configuration of an imprint mold substrate according to an embodiment of the present disclosure. FIG. 4 is a partially enlarged cut end view showing a schematic configuration in the vicinity of the convex structure portion of the imprint mold substrate shown in FIG. 3. FIG. 5 is a cut end view showing a schematic configuration of an imprint mold substrate according to an embodiment of the present disclosure. FIG. 6 is a partially enlarged cut-away end view showing a schematic configuration in the vicinity of a convex structure portion of the imprint mold substrate shown in FIG. FIG. 7 is a cut end view showing a schematic configuration of an imprint mold substrate having an inflection point on the bottom surface in a projection region in which the top surface portion of the convex structure portion is projected on the bottom surface side of the depression portion. FIG. 8 is a partially enlarged cut end view showing a schematic configuration in the vicinity of the convex structure portion of the imprint mold substrate shown in FIG. 7. FIG. 9 is a cut end view showing a schematic configuration of an imprint mold according to an embodiment of the present disclosure. FIG. 10 is a partially enlarged cut-away end view showing a schematic configuration in the vicinity of the convex structure portion of the imprint mold shown in FIG. 9. 11A to 11E are process flow charts showing the respective processes of the method for manufacturing the imprint mold substrate according to the embodiment of the present disclosure.

Embodiments of the present disclosure will be described with reference to the drawings.
In the drawings, in order to facilitate understanding, the shape, scale, vertical / horizontal dimensional ratio, and the like of each portion may be changed or exaggerated from the actual product. In this specification and the like, a numerical range represented by "to" means a range including the numerical values before and after "to" as a lower limit value and an upper limit value, respectively. In this specification and the like, terms such as “film”, “sheet”, and “plate” are not distinguished from each other based on their different names. For example, the term “plate” is a concept that also includes members that can be generally called “sheet” and “film”.

[Substrate for imprint mold]
FIG. 1 is a cut end view showing a schematic configuration of a first aspect of the imprint mold substrate according to the present embodiment, and FIG. 2 is a schematic configuration near a convex structure portion of the imprint mold substrate shown in FIG. 4 is a partially enlarged cut-away end view showing the above, FIG. 3 is a cut-away end view showing a schematic configuration of a second aspect of the imprint mold substrate according to the present embodiment, and FIG. 4 is the imprint mold shown in FIG. FIG. 6 is a partially enlarged cut-away end view showing a schematic configuration in the vicinity of a convex structure portion of a substrate for printing, and FIG. FIG. 6 is a partially enlarged cut-away end view showing a schematic configuration in the vicinity of the convex structure portion of the imprint mold substrate shown in FIG. 5.

  As shown in FIGS. 1 to 6, an imprint mold substrate 1 according to this embodiment includes a base material 2 having a first surface 21 and a second surface 22 facing the first surface 21, and a base material 2 of the base material 2. The convex structure 3 protruding from the first surface 21 and the recess 4 formed on the second surface 22 side are provided.

  The base material 2 is generally used as an imprint mold substrate, for example, a quartz glass substrate, a soda glass substrate, a fluorite substrate, a calcium fluoride substrate, a magnesium fluoride substrate, barium borosilicate glass, aminoborosilicate glass. , Glass substrates such as non-alkali glass substrates such as aluminosilicate glass, polycarbonate substrates, polypropylene substrates, polyethylene substrates, polymethylmethacrylate substrates, resin substrates such as polyethylene terephthalate substrates, the above substrates at least partially metal-doped, A transparent substrate or the like such as a laminated substrate formed by laminating two or more substrates arbitrarily selected from the above can be used. In addition, in this embodiment, “transparent” means that light having a wavelength capable of curing the imprint resin can be transmitted, and means that the transmittance of light having a wavelength of 150 nm to 400 nm is 60% or more. However, it is preferably 90% or more, particularly preferably 95% or more.

  The planar view shape of the base material 2 is not particularly limited, and examples thereof include a substantially rectangular shape. When the base material 2 is made of a quartz glass substrate generally used for optical imprint, the shape of the base material 2 in plan view is generally a substantially rectangular shape.

  The size of the base material 2 (size in plan view) is also not particularly limited, but when the base material 2 is made of the above quartz glass substrate, for example, the size of the base material 2 is about 152 mm × 152 mm. .. Further, the thickness of the base material 2 can be appropriately set in the range of, for example, 300 μm to 10 mm in consideration of strength, handling suitability, and the like.

  In the present embodiment, at least the second surface 22 of the base material 2 is not required to have a shape protruding from the central portion toward the peripheral portion in a convex shape. When the second surface 22 of the base material 2 has a shape that protrudes from the central portion toward the peripheral portion in a convex shape, the second surface of the imprint mold manufactured from the imprint mold substrate 1 is connected to the imprint apparatus. When sucked and held by the holding mechanism, the central portion of the first surface is recessed and the peripheral portion of the first surface is convex. When the imprint process is performed on the transferred substrate in such a state, the outer peripheral portion of the convex structure portion of the imprint mold or the outer peripheral portion of the imprint mold comes into contact with the transferred substrate, and the transferred substrate or the imprint mold is May be damaged.

  The convex structure portion 3 projecting from the first surface 21 of the base material 2 is provided substantially in the center of the base material 2 in a plan view. The shape of the convex structure 3 in a plan view is a substantially rectangular shape. The size of the convex structure portion 3 is appropriately set in accordance with a product or the like manufactured through the imprint process using the imprint mold substrate 1, and is set to, for example, about 30 mm × 25 mm.

  The protrusion height of the convex structure portion 3 (the length along the thickness direction of the base material 2 between the first surface 21 of the base material 2 and the upper surface portion 31 of the convex structure portion 3) is the imprint according to the present embodiment. The molding substrate 1 is not particularly limited as long as it can serve the purpose of including the convex structure portion 3, and can be set to, for example, about 10 μm to 100 μm. On the upper surface portion 31 of the convex structure portion 3, a pattern area in which the concave / convex pattern 11 (see FIGS. 9 and 10) is to be formed is set.

  The second surface 22 of the base material 2 is provided with a recess 4 having a predetermined size. Since the recessed portion 4 is formed, particularly during the imprint process using the imprint mold 10 (see FIGS. 9 and 10) produced from the imprint mold substrate 1 according to the present embodiment, the imprint resin is particularly preferable. When the second surface 22 of the base material 2 is held by a suction chuck or the like during contact with the imprint mold 10 or when the imprint mold 10 is peeled off, pressure is applied to the recess 4 to form a substrate formed by the recess 4. Only the thin portion (thin plate portion) of the material 2 can be curved. As a result, when the upper surface portion 31 of the convex structure portion 3 and the imprint resin are brought into contact with each other, gas is trapped between the uneven pattern 11 formed on the upper surface portion 31 of the convex structure portion 3 and the imprint resin. It is possible to prevent the imprint mold 10 from being covered, and it is possible to easily separate the imprint mold 10 from the pattern obtained by transferring the uneven pattern 11 to the imprint resin.

  It is preferable that the plan view shape of the recess 4 is substantially circular. The substantially circular shape allows the imprint mold 10 to be subjected to an imprint process, particularly when the upper surface portion 31 of the convex structure 3 is brought into contact with the imprint resin or when the imprint mold 10 is separated from the imprint resin. The thin plate portion and the upper surface portion 31 of the convex structure portion 3 can be curved substantially uniformly in the plane.

  The size of the recessed portion 4 in a plan view is particularly limited as long as the projection structure portion 3 is included in the projection area where the recessed portion 4 is projected on the first surface 21 side of the base material 2. It is not something that will be done. If the projection area has a size that cannot cover the convex structure 3, the entire upper surface 31 of the convex structure 3 of the imprint mold 10 may not be curved effectively.

  The recessed portion 4 is configured by a bottom surface 41 and a peripheral wall surface 42 that stands from the outer peripheral edge of the bottom surface 41 toward the second surface 22 side of the base material 2. The bottom surface 41 of the recessed portion 4 is wholly or partially substantially convex toward the first surface 21 side of the base material 2 (see FIGS. 1 to 4; concave toward the second surface 22 side) or concave. (Refer to FIG. 5 and FIG. 6. It has a curved shape that is convex toward the second surface 22 side), but the pattern region (the upper surface portion 31 of the convex structure portion 3) is projected onto the bottom surface 41 side of the recess portion 4. In the projection area, the bottom surface 41 of the recess 4 does not substantially have an inflection point. In the imprint process using the imprint mold 10 (see FIGS. 9 and 10) produced from the imprint mold substrate 1 according to the present embodiment, when the imprint mold 10 is separated from the cured imprint resin, The imprint mold 10 is separated while curving the upper surface portion 31 of the convex structure portion 3. In general, since the imprint mold 10 is separated from the peripheral edge of the pattern region (the upper surface portion 31 of the convex structure portion 3) toward the geometric center, the geometric center is the imprint mold 10 from the imprint resin. It becomes the part to leave. However, for example, as in the imprint mold manufactured from the imprint mold substrate 100 as shown in FIGS. 7 and 8, the pattern region (the upper surface portion 310 of the convex structure portion 300) is formed on the bottom surface 410 side of the recess portion 400. When an inflection point 411 is present on the bottom surface 410 of the recess 400 in the projection area projected on the release area, a parting line (contact between the imprint mold and the imprint resin) is formed on a portion of the pattern area facing the inflection point 411. When the boundary line) is approaching, the stress applied to the imprint resin changes rapidly due to mold release. This sudden change in stress causes pattern defects. In this respect, since the imprint mold substrate 1 according to the present embodiment has substantially no inflection point on the bottom surface 41 of the recessed portion 4 in the projection region, the imprint mold 10 manufactured therefrom has a It is possible to make it difficult to cause a rapid change in stress from the start to the end of the mold. Therefore, it is possible to form a highly accurate pattern by the imprint process using the imprint mold 10. In addition, in the present embodiment, an inflection point 41A may be present on the bottom surface 41 of the hollow portion 4 outside the projection region (see FIGS. 3 to 6). This is because such an inflection point 41A does not cause a rapid change in stress at the time of mold release.

  In the present embodiment, the radius of curvature of the bottom surface 41 of the recessed portion 4 in the projection area obtained by projecting the pattern area (the top surface portion 31 of the convex structure portion 3) on the bottom surface 41 side of the recessed portion 4 is the bottom surface 41 outside the projection area. Is preferably larger than the radius of curvature of More preferably, the radius of curvature of the bottom surface 41 of the recess 4 at the geometric center of the projection area has the maximum value among the radii of curvature of the bottom surface 41 of the recess 4 in the projection area. Generally, the imprint mold 10 is finally separated from the imprint resin at the geometric center of the pattern region (the upper surface portion 31 of the convex structure portion 3). Therefore, the radius of curvature of the bottom surface 41 of the recess 4 at the geometric center of the projection region exhibits the maximum value, and the radius of curvature of the bottom surface 41 decreases from that point toward the peripheral wall surface 42, which is a highly accurate pattern formation. From this viewpoint, it can be said that the shape of the bottom surface 41 is ideal. Therefore, as in the present embodiment, there is substantially no inflection point on the bottom surface 41 of the depression 4 in the projection area, and the radius of curvature of the bottom surface 41 of the depression 4 in the projection area is the projection area. Since the radius of curvature of the outer bottom surface 41 is larger, it is possible to form a highly accurate pattern by the imprinting process using the imprint mold 10, and further, the bottom surface 41 of the recessed portion 4 at the geometric center of the projection region. Since the radius of curvature exhibits the maximum value, it is possible to form a pattern with higher accuracy by the imprint process using the imprint mold 10.

  Within the projection area, the radius of curvature of the bottom surface 41 of the recess 4 is preferably 20 m or more, and more preferably 40 m or more. When the radius of curvature of the bottom surface 41 of the recess 4 is less than 20 m, the stress applied to the imprint resin during the release of the imprint mold 10 becomes relatively large, which may cause pattern defects.

  In addition, in this embodiment, although the aspect which has the convex structure part 3 which protrudes from the 1st surface 21 of the base material 2 was mentioned as an example, it is not limited to such an aspect, For example, a base material. It is not necessary to have the convex structure 3 on the side of the first surface 21 of No. 2. In this case, an inflection point is substantially present in the projection area in which the pattern area on the first surface 21 of the base material 2 (the area where the concavo-convex pattern 11 is to be formed) is projected toward the second surface 22 side. The radius of curvature of the bottom surface 41 is preferably within a predetermined range (20 m or more).

[Imprint mold]
FIG. 9 is a cut end view showing a schematic configuration of the imprint mold in the present embodiment, and FIG. 10 is a partially enlarged cut end view showing a schematic configuration in the vicinity of the convex structure portion of the imprint mold in the present embodiment. ..
The imprint mold 10 in the present embodiment has an uneven pattern 11 formed on the upper surface portion 31 of the convex structure portion 3 of the imprint mold substrate 1.

  The shape, dimensions, etc. of the concavo-convex pattern 11 can be appropriately set according to the shape, dimensions, etc. required for a product etc. manufactured using the imprint mold 10 in the present embodiment. For example, the shape of the concavo-convex pattern 11 may be a line and space shape, a pillar shape, a hole shape, a lattice shape, or the like. Moreover, the dimension of the concavo-convex pattern 11 can be set to, for example, about 10 nm to 200 nm.

  The imprint mold 10 according to the present embodiment may not have the convex structure portion 3. In this case, the concavo-convex pattern 11 may be formed in the pattern area set on the first surface 21 of the base material 2, and the pattern area (the area in which the concavo-convex pattern 11 is formed) is defined as the second surface 22. It is sufficient that the inflection point does not substantially exist in the projection area projected toward the side, and preferably the radius of curvature of the bottom surface 41 is within a predetermined range (20 m or more).

  According to the imprint mold 10 in the present embodiment, the recessed portion is formed in the projection area where the pattern area (the upper surface portion 31 of the convex structure portion 3) on the first surface 21 side of the base material 2 is projected on the second surface 22 side. Since the bottom surface 41 of 4 does not substantially have an inflection point, a rapid change in stress applied to the imprint resin does not occur during imprint processing using the imprint mold 10, particularly when the imprint mold 10 is released. .. As a result, it is possible to effectively prevent the occurrence of pattern defects, and it is possible to form a highly accurate pattern.

[Method for manufacturing substrate for imprint mold]
An example of a method for manufacturing the imprint mold substrate 1 having the above-described configuration will be described. 11A to 11E are process flow charts showing the respective processes of the method for manufacturing an imprint mold substrate according to the present embodiment.

[Substrate preparation process]
First, a base material 2'having a first surface 21 'and a second surface 22' facing it is prepared, and a hard mask layer 70 and a resist layer 80 are laminated in this order on the first surface 21 'of the base material 2'. (See FIG. 11A).

  The base material 2 ′ is generally used as a substrate for imprint mold, for example, quartz glass substrate, soda glass substrate, fluorite substrate, calcium fluoride substrate, magnesium fluoride substrate, barium borosilicate glass, aminoborosilicate. Glass, a glass substrate such as a non-alkali glass substrate such as aluminosilicate glass, a polycarbonate substrate, a polypropylene substrate, a polyethylene substrate, a polymethylmethacrylate substrate, a resin substrate such as polyethylene terephthalate substrate, the above substrate at least a portion of which metal is doped, these A transparent substrate such as a laminated substrate formed by laminating two or more substrates arbitrarily selected from the above can be used.

  The plan view shape of the base material 2 ′ is not particularly limited, and examples thereof include a substantially rectangular shape. When the base material 2 ′ is made of a quartz glass substrate generally used for optical imprint, the base material 2 usually has a substantially rectangular shape in plan view.

  The size of the base material 2 ′ (size in plan view) is not particularly limited, but when the base material 2 ′ is made of the above quartz glass substrate, for example, the size of the base material 2 ′ is 152 mm × 152 mm. It is a degree. Further, the thickness of the base material 2 ′ 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.

  Examples of the material forming the hard mask layer 70 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 boron oxide. Tantalum compounds such as tantalum oxide and tantalum oxynitride, 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 70 is patterned in a step described later (see FIG. 11C), and is a mask pattern when the convex structure portion 3 (see FIG. 11D) of the imprint mold substrate 1 is formed by etching. Is used as. Therefore, it is preferable to select the constituent material of the hard mask layer 70 in consideration of the etching selection ratio and the like according to the constituent material of the base material 2 '. For example, when the base material 2'is a quartz glass substrate, a chromium oxide film or the like can be suitably selected as the hard mask layer 70.

  The thickness of the hard mask layer 70 is appropriately set in consideration of the etching selection ratio according to the constituent material of the base material 2 '. For example, when the base material 2'is a quartz glass substrate and the hard mask layer 70 is a chromium oxide film, the thickness of the hard mask layer 70 can be appropriately set within the range of about 0.5 nm to 200 nm.

  The method of forming the hard mask layer 70 on the first surface 21 ′ of the base material 2 ′ is not particularly limited, and for example, known methods such as sputtering, PVD (Physical Vapor Deposition), and CVD (Chemical Vapor Deposition) are known. Film forming method.

  The material forming the resist layer 80 formed by the spin coating method or the like so as to cover the hard mask layer 70 on the first surface 21 ′ of the base material 2 ′ is not particularly limited, and may be, for example, a negative type. Alternatively, a positive photosensitive material or the like can be used, but a negative photosensitive material is preferably used. The film thickness of the resist layer 80 is not particularly limited, and can be appropriately set according to the selection ratio or the like according to the constituent material of the hard mask layer 70.

[Resist pattern forming step]
By performing an exposure process and a development process on the resist layer 80 through a photomask (not shown) having a predetermined opening, a resist pattern 81 corresponding to the convex structure portion 3 is formed (FIG. 11B). reference).

  In this embodiment, the hard mask layer 70 is dry-etched using the resist pattern 81 as a mask to form the mask pattern 71 corresponding to the convex structure 3. That is, the size (size) of the resist pattern 81 and the size (size) of the mask pattern 71 are substantially the same. Then, as will be described later, the size (size) of the mask pattern 71 is larger than the size (size) of the convex structure portion 3 and is configured to include the upper surface portion 31 of the convex structure portion 3. .. Therefore, the size (size) of the resist pattern 81 is also larger than the size (size) of the convex structure portion 3, and is configured to include the upper surface portion 31 of the convex structure portion 3.

[Mask pattern forming step]
By using the resist pattern 81 formed as described above as an etching mask, the hard mask layer 70 exposed from the opening is dry-etched using, for example, a chlorine-based (Cl ₂ + O ₂ ) etching gas. A mask pattern 71 is formed on the first surface 21 'of the material 2' (see FIG. 11C).

  The mask pattern 71 is used as a mask for forming the convex structure portion 3 in a wet etching process described later. Then, in the wet etching process for forming the convex structure portion 3, so-called side etching occurs, and the base material 2'is laterally (in-plane direction) etched. Therefore, the size (size) of the upper surface part 31 of the convex structure part 3 is smaller than the size (size) of the mask pattern 71. That is, the size (size) of the mask pattern 71 is configured to be larger than the size (size) of the upper surface portion 31 of the convex structure portion 3. The size of the mask pattern 71 may be set according to the amount of side etching of the base material 2 ′, for example, about 1 μm to 200 μm.

[Wet etching process]
Using the mask pattern 71 formed as described above as a mask, the base material 2'is subjected to a wet etching process to remove the remaining mask pattern 71. Hydrofluoric acid or the like is preferably used as the etching solution in the wet etching process. As a result, the convex structure portion 3 is formed (see FIG. 11D).

[Cavity forming step]
Subsequently, the second surface 22 ′ of the base material 2 ′ is subjected to a grinding process to form a recess (a recess corresponding to the recess 4), and then a smoothing process (smoothing) including a first polishing process and a second polishing process. Process) is applied to the bottom surface of the recess to form the recess 4 (see FIG. 11E).

  Generally, in the grinding process for the second surface 22 ′ of the base material 2 ′, after forming a bottomed hole having a predetermined depth and diameter in a region of the second surface 22 ′ where the recess 4 is to be formed, A milling head (grinding head) is inserted into the bottomed hole and is ground in the thickness direction (depth direction of the bottomed hole) and in-plane direction (radial direction of the bottomed hole) of the base material 2 ′. The bottomed hole may be formed substantially in the center of the second surface 22 ′ as long as it is in the area where the recess 4 is to be formed, or at a predetermined position along the outer periphery of the area. It may be formed. In this way, minute scratches (irregularities) are formed on the bottom surface and the peripheral wall surface of the recess formed on the second surface 22 'of the base material 2'. When the imprint process is performed using the imprint mold in which such minute scratches (irregularities) are formed on the bottom surface or the peripheral wall surface of the recessed portion, the light irradiated through the recessed portion is irregularly reflected and the imprinting process is performed. There is a risk of causing poor curing of the print resin. Therefore, first, a first polishing process for removing fine scratches (irregularities) formed on the bottom surface or the peripheral wall surface of the concave portion of the second surface 22 ′ of the base material 2 ′ is performed on the bottom surface or the peripheral wall surface (at least the bottom surface). ). As a result, the minute scratches (irregularities) are removed. The first polishing process can be performed using, for example, a polishing slurry containing an abrasive having a predetermined particle size, but is not limited to this method. Further, by performing a wet etching process instead of the first polishing process, fine scratches (concavities and convexities) on the bottom surface of the concave portion and the peripheral wall surface may be removed.

  On the other hand, the concave portion formed by the grinding process has a bottom surface that is inclined toward the in-plane direction with the maximum center or the maximum depth at the substantially center thereof, and the device factor of the grinding device (apparatus). The inflection point will occur on the bottom surface of the recess. However, it is difficult to prevent such an inflection point from existing in the first polishing process. Therefore, a second polishing process is performed on the bottom surface of the recess to prevent the inflection point from existing. This makes it possible to form the depression 4 having the bottom surface 41 that does not substantially have an inflection point. The second polishing process may be performed at least in the projection area where the upper surface portion 31 of the convex structure portion 3 is projected on the bottom surface of the concave portion, but may be performed on the entire bottom surface of the concave portion.

  In the second polishing process, the radius of curvature of the bottom surface 41 of the recess 4 in the projection region obtained by projecting the top surface 31 of the convex structure 3 toward the bottom surface 41 of the recess 4 is preferably 20 m or more. The bottom surface of the recess may be polished so that it is preferably 40 m or more.

  The second polishing process can be performed using a polishing slurry containing an abrasive having a larger particle size than the abrasive that can be used in the first polishing process. The second polishing treatment is performed so that at least a part of the bottom surface 41 (within the projection area where the top surface portion 31 of the convex structure portion 3 is projected on the bottom surface 41) does not substantially have an inflection point. However, the polishing process is not performed until the bottom surface 41 is parallel to the first surface 21 of the base material 2 and the upper surface portion 31 of the convex structure portion 3. Therefore, the cost and time required to manufacture the imprint mold substrate 1 can be relatively reduced. That is, according to this embodiment, it is possible to manufacture an imprint mold substrate capable of manufacturing an imprint mold capable of forming a pattern with high accuracy, without spending a lot of cost and time. After the smoothing process, at least the mirror polishing process may be performed in the projection area in which the upper surface portion 31 of the convex structure portion 3 is projected onto the bottom surface of the concave portion. By performing such mirror polishing, it is possible to reduce the surface roughness of at least the bottom surface 41 of the recess 4 of the imprint mold substrate 1. Therefore, during the optical imprint process using the imprint mold 10 (see FIGS. 9 and 10) manufactured from such an imprint mold substrate 1, the imprint resin is irradiated through the imprint mold 10. It is possible to more effectively suppress irregular reflection of light on the bottom surface 41 and the peripheral wall surface 42 of the recess 4. This mirror-polishing treatment may be performed on the entire bottom surface of the recess, or may be further performed on the peripheral wall surface 42.

[Method for manufacturing imprint mold]
A hard mask pattern corresponding to the concavo-convex pattern 11 is formed on the upper surface portion 31 (pattern area) of the convex structure portion 3 of the imprint mold substrate 1 manufactured as described above, and the hard mask pattern is used as a mask for imprinting. The imprint mold 10 (see FIGS. 9 and 10) can be manufactured by performing dry etching on the molding substrate 1 and forming the concavo-convex pattern 11 on the upper surface of the convex structure 3. The dry etching of the imprint mold substrate 1 can be performed by appropriately selecting an etching gas according to the type of the constituent material of the imprint mold substrate 1. As the etching gas, for example, a fluorine-based gas or the like can be used.

  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-described embodiment is intended to include all design changes and equivalents within the technical scope of the present invention.

  In the above-described embodiment, an example has been described in which the geometric center from the periphery of the pattern region (the upper surface portion 31 of the convex structure portion 3) is the portion where the imprint mold 10 is finally separated from the imprint resin. However, the present invention is not limited to such an aspect. For example, a position away from the geometric center (for example, near the peripheral edge of the upper surface portion 31 of the convex structure portion 3) may be a portion where the imprint mold 10 is finally separated from the imprint resin. In this case, the radius of curvature of the bottom surface 41 of the recessed portion 4 in the portion facing the last separated portion (for example, in the vicinity of the peripheral edge of the upper surface portion 31 of the convex structure portion 3) is the bottom surface 41 of the recessed portion 4 in the projection region. It is only necessary to show the maximum value within the radius of curvature of.

  In the above embodiment, the imprint mold substrate 1 and the imprint mold 10 each having the one-step convex structure portion 3 protruding from the first surface 21 of the base material 2 have been described as an example. It is not limited. For example, the imprint mold substrate 1 and the imprint mold 10 have a plurality of steps of convex structure portions 3 including a first step rising from the first surface 21 of the base material 2 and a second step protruding from the first step. The pattern area may be set on the upper surface of the second step, and the concavo-convex pattern 11 may be formed. The number of steps of the convex structure 3 is not limited to two, and may be three or more, and a pattern formation region is set on the upper surface of the uppermost step of the convex structures 3 having a plurality of steps or the uneven pattern 11 is formed. Should be formed.

  Hereinafter, the present disclosure will be described in more detail with reference to Examples and the like, but the present disclosure is not limited to the following Examples and the like.

[Example 1]
1 and 2, an imprint mold substrate 1 having substantially no inflection point on the bottom surface 41 of the recess 4 is prepared, and the upper surface portion 31 of the convex structure 3 of the imprint mold substrate 1 is prepared. Then, the imprint mold 10 was produced by forming the line-and-space uneven pattern 11 having a half pitch of 26 nm. The imprint mold 10 was used to transfer the concavo-convex pattern 11 to the imprint resin supplied on the quartz substrate as the substrate to be transferred to form a transfer pattern. When the transfer pattern was observed with an optical microscope, pattern defects such as defects, collapses, and deformations of the transfer pattern (convex pattern) did not occur.

[Example 2]
Substrate 1 for imprint mold shown in FIGS. 3 and 4 in which there is substantially no inflection point on the bottom surface 41 of the recessed portion 4 (in the projection region in which the upper surface portion 31 of the convex structure portion 3 is projected on the bottom surface 41 side). Then, the imprint mold 10 was produced by forming the line-and-space uneven pattern 11 having a half pitch of 26 nm on the upper surface 31 of the convex structure 3 of the imprint mold substrate 1. The imprint mold 10 was used to transfer the concavo-convex pattern 11 to the imprint resin supplied on the quartz substrate as the substrate to be transferred to form a transfer pattern. When the transfer pattern was observed with an optical microscope, pattern defects such as defects, collapses, and deformations of the transfer pattern (convex pattern) did not occur.

[Comparative Example 1]
Prepare the imprint mold substrate 100 shown in FIGS. 7 and 8 in which the inflection point 411 exists on the bottom surface 410 of the recessed portion 400 (in the projection area in which the top surface portion 310 of the convex structure portion 300 is projected on the bottom surface 410 side). Then, an imprint mold was produced by forming a line-and-space concave-convex pattern with a half pitch of 26 nm on the upper surface portion 310 of the convex structure portion 300 of the imprint mold substrate 100. Using the imprint mold, the concavo-convex pattern was transferred to the imprint resin supplied on the quartz substrate as the transfer target substrate to form a transfer pattern. When the transfer pattern was observed with an optical microscope, pattern defects occurred in five independent areas (areas of φ1 μm or more) in the transfer pattern.

  As is clear from the results of Examples 1 and 2 and Comparative Example 1 described above, in the projection region where the upper surface portion of the convex structure portion of the imprint mold is projected to the bottom surface side, the bottom surface of the depression has an inflection point. It was confirmed that a pattern can be formed with high accuracy by not having it substantially.

DESCRIPTION OF SYMBOLS 1 ... Imprint mold substrate 2 ... Base material 21 ... 1st surface 22 ... 2nd surface 3 ... Convex structure part 31 ... Upper surface part 4 ... Recessed part 41 ... Bottom surface 42 ... Perimeter wall surface 10 ... Imprint mold 11 ... Concavo-convex pattern

Claims (8)

A base material having a first surface and a second surface facing the first surface;
A pattern area in which a concavo-convex pattern can be formed, which is set on the first surface of the base material;
A recess formed on the second surface of the substrate,
The recessed portion includes a bottom surface and a peripheral wall surface standing from the outer peripheral edge of the bottom surface toward the second surface side,
The imprint mold substrate, wherein the bottom surface of the recess has substantially no inflection point in a projection area in which the pattern area is projected to the bottom surface side of the recess. The substrate for imprint mold according to claim 1, wherein a radius of curvature of the bottom surface of the recess in the projection area is larger than a radius of curvature of the bottom surface outside the projection area. The substrate for imprint mold according to claim 2, wherein a radius of curvature of the bottom surface of the recess at the center of the projection region shows a maximum value in the projection region. Further comprising a convex structure portion having an upper surface portion protruding from the first surface of the base material,
The imprint mold substrate according to claim 1, wherein the pattern region is set on the upper surface portion of the convex structure portion. The substrate for imprint mold according to claim 1, wherein the base material is made of quartz glass.   An imprint mold having a concavo-convex pattern formed in the pattern region of the imprint mold substrate according to claim 1. A method for manufacturing the substrate for imprint mold according to any one of claims 1 to 5, comprising:
A step of preparing a substrate having one surface and a facing surface facing the one surface,
A step of forming a concave portion by subjecting the facing surface of the substrate to grinding,
A step of forming the recess by smoothing the bottom surface of the recess,
On the one surface of the substrate, the pattern region of the substrate for imprint mold is set,
At least a method for manufacturing an imprint mold substrate, which smoothes the bottom surface of the recess so that an inflection point does not substantially exist in a projection area in which the pattern area is projected on the bottom surface side of the recess. A method for manufacturing an imprint mold, comprising a step of forming an uneven pattern in the pattern region of the substrate for imprint mold manufactured by the method according to claim 7.

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