Imprint mold

Abstract

To provide an imprint mold capable of suppressing variation in shape.SOLUTION: An imprint mold 50 has a pattern surface 50S on which a pattern 50P is formed. The pattern 50P has a plurality of unit shapes U3 aligned in a first direction D1. The unit shape U3 has a concave-convex shape extending in a second direction D2 that intersects the first direction D1. The concave-convex shape includes a bottom flat surface 51, a top flat surface 52, an inclined surface 53, and a stepped surface 54. The bottom flat surface 51 is located at a bottom of the concave-convex shape, and the top flat surface 52 is located at a top of the concave-convex shape. When viewed from above, a ratio of an area of the bottom flat surface 51 to an entire area of the unit shape U3 is 10% or more, and a ratio of an area of the top flat surface 52 to an entire area of the unit shape U3 is 10% or more. Furthermore, a ratio of a total area of the bottom flat surface 51 and the top flat surface 52 to an entire area of the unit shape U3 is 50% or less.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present disclosure relates to an imprint mold. [Background technology]

[0002] Imprinting is known as a technique for forming fine circuit patterns for semiconductor devices and fine patterns for imparting optical functions. The imprinting method uses a metal mold on which a reverse pattern of the fine pattern to be ultimately formed is formed. The imprinting method transfers the pattern by pressing the mold into a resin such as resist and then curing the resin with heat or light (see, for example, Patent Document 1).

[0003] Diffractive optical elements (DOEs) are a well-known example of the application of fine patterns to impart optical functions. In recent years, a blazed diffraction grating, which has a sawtooth cross-sectional shape with asymmetric triangles arranged periodically and without gaps, has been proposed as a diffractive optical element to increase the diffraction efficiency in the intended direction. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-194142 Summary of the Invention [Problem to be solved by the invention]

[0005] The tops and bottoms of a blazed diffraction grating pattern are the vertices of a triangle. Therefore, the mold used to form the blazed diffraction grating must also have a steep shape that is the inverse of the shape of the top and bottom of the diffractive optical element. The pattern is formed on the mold by photolithography, but the steeply shaped portions of the mold are prone to variation in the pattern shape due to even slight variations in the photolithography processing conditions.

[0006] This problem is not limited to molds patterned by photolithography. For example, replica molds onto which a pattern from a master mold patterned by photolithography is transferred also have the common problem of pattern shape variation in portions of the mold that have steep shapes. [Means for solving the problem]

[0007] An imprint mold for solving the above problem has a pattern surface on which a pattern is formed, the pattern having a plurality of unit shapes aligned in a first direction, the unit shapes having a concave-convex shape extending in a second direction intersecting the first direction, the concave-convex shape having a bottom flat surface located at the bottom of the concave-convex shape and a convex portion including an inclined surface and a stepped surface, and when viewed from above from a viewpoint opposite to a plane including the first direction and the second direction, the ratio of the area of ​​the bottom flat surface to the total area of ​​the unit shapes is 10% or more and 50% or less.

[0008] According to the above configuration, no steep shape is formed at the bottom of the uneven shape of the unit shape, which reduces the shape variation within the pattern surface and the shape variation between lots at the bottom of the uneven shape of the unit shape.

[0009] An imprint mold for solving the above problem comprises a pattern surface on which a pattern is formed, the pattern having a plurality of unit shapes aligned in a first direction, the unit shapes having a concave-convex shape extending in a second direction intersecting the first direction, the concave-convex shape having a convex portion including a top flat surface, an inclined surface, and a step surface, the top flat surface being located at the top of the concave-convex shape, and the ratio of the area of ​​the top flat surface to the total area of ​​the unit shapes is 10% or more and 50% or less in a top view seen from a viewpoint opposite to a plane including the first direction and the second direction.

[0010] According to the above configuration, the peaks of the uneven shapes of the unit shapes do not have steep shapes, which reduces the variation in the shape of the peaks of the uneven shapes of the unit shapes within the pattern surface and between lots.

[0011] An imprint mold for solving the above problem comprises a pattern surface on which a pattern is formed, the pattern having a plurality of unit shapes aligned in a first direction, the unit shapes having a concave-convex shape extending in a second direction intersecting the first direction, the concave-convex shape comprising a bottom flat surface located at the bottom of the concave-convex shape, and a convex portion including a top flat surface, a sloping surface, and a step surface, the top flat surface being located at the top of the concave-convex shape, and in a top view seen from a viewpoint opposite to a plane including the first direction and the second direction, the ratio of the area of ​​the bottom flat surface to the total area of ​​the unit shapes is 10% or more, the ratio of the area of ​​the top flat surface to the total area of ​​the unit shapes is 10% or more, and the ratio of the sum of the area of ​​the bottom flat surface and the area of ​​the top flat surface to the total area of ​​the unit shapes is 50% or less.

[0012] According to the above configuration, the bottoms and tops of the uneven shapes of the unit shapes do not have steep shapes, which reduces the shape variations within the pattern surface and between lots at the bottoms and tops of the uneven shapes of the unit shapes.

[0013] In the imprint mold, the material constituting the pattern surface may be at least one of silicon, a silicon compound, diamond, a metal, a metal compound, ceramic, and a resin. By constituting the pattern surface with such a material, a pattern can be formed on the pattern surface by photolithography.

[0014] In the imprint mold, the pattern surface may include a first portion made of a first material and a second portion made of a second material that is less susceptible to etching than the first material under specific etching conditions, and the second portion may include the bottom flat surface. With this configuration, local variations in etching depth on the bottom flat surface can be absorbed, thereby further suppressing variations in shape on the bottom flat surface.

[0015] In the imprint mold, the pattern surface may include a first portion made of a first material and a second portion made of a second material that is less susceptible to etching than the first material under specific etching conditions, and the second portion may include the top flat surface. With this configuration, local variations in etching depth on the top flat surface can be absorbed, thereby further suppressing variations in shape on the top flat surface.

[0016] In the imprint mold, the pattern surface may include a first portion made of a first material and a second portion made of a second material that is less susceptible to etching than the first material under specific etching conditions, and the second portion may include the bottom flat surface and the top flat surface. This configuration can absorb local variations in etching depth on the bottom flat surface and the top flat surface, thereby further suppressing variations in shape on the bottom flat surface and the top flat surface. [Effects of the Invention]

[0017] According to the present disclosure, it is possible to suppress variation in the shape of the imprint mold. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a perspective view of AR glasses to which a diffractive optical element manufactured using an imprint mold is applied. [Figure 2] FIG. 2 is a cross-sectional view of the imprint mold of the first embodiment and a diffractive optical element onto which the pattern of the imprint mold is transferred. [Figure 3] FIG. 3 shows a modified example of the imprint mold of the first embodiment. [Figure 4] FIG. 4 is a cross-sectional view of an imprint mold according to the second embodiment and a diffractive optical element onto which the pattern of the imprint mold has been transferred. [Figure 5] FIG. 5 shows a modified example of the imprint mold of the second embodiment. [Figure 6] FIG. 6 is a cross-sectional view of an imprint mold according to the third embodiment and a diffractive optical element onto which the pattern of the imprint mold has been transferred. [Figure 7] FIG. 7 shows a modification of the imprint mold of the third embodiment. [Figure 8] FIG. 8 shows a modified example of the imprint mold of the third embodiment. [Figure 9] FIG. 9 shows a modified example of the imprint mold of the third embodiment. [Figure 10] FIG. 10 is a cross-sectional view showing a mold substrate and an electron beam resist layer used in a test example. [Figure 11] FIG. 11 is a cross-sectional view of the resist patterns employed in samples A1 to A7 in the test examples. [Figure 12] FIG. 12 is a cross-sectional view of the resist patterns employed in samples B1 to B7 in the test example. [Figure 13] FIG. 13 is a cross-sectional view of the mold substrate and the resist pattern in a state in which the samples B1 to B7 have been dry-etched in the test example. [Figure 14]FIG. 14 is a cross-sectional view of the mold substrate and the resist pattern in a state in which samples C1 to C7 have been dry-etched in the test example. [Figure 15] FIG. 15 is a cross-sectional view of the mold substrate in a state in which sample X1 has been dry-etched in a test example. [Figure 16] FIG. 16 is a table showing the design values ​​of the dimensions of each mold in the test example and the evaluation results. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, an embodiment of the imprint mold will be described with reference to FIGS. (Application example of a diffractive optical element manufactured using an imprint mold) First, with reference to FIG. 1, AR glasses 100 to which a diffractive optical element, which is an example of an optical element manufactured using an imprint mold, is applied will be described.

[0020] 1, the AR glasses 100 include a temple unit 101 and a glass unit 102. The AR glasses 100 also include a microdisplay unit 103 that outputs an image. For example, the microdisplay unit 103 is mounted on the temple unit 101.

[0021] The glass unit 102 has optical transparency that allows visible light to pass through, and displays an image output by the microdisplay unit 103. That is, the image output by the microdisplay unit 103 is displayed on the glass unit 102 so as to be superimposed on the real space image.

[0022] Glass section 102 includes incident diffraction grating section 104, waveguide diffraction grating section 105, and exit diffraction grating section 106. Incident diffraction grating section 104, waveguide diffraction grating section 105, and exit diffraction grating section 106 are diffractive optical elements that change the traveling direction of light L1 that constitutes an image on microdisplay section 103. Incident diffraction grating section 104, waveguide diffraction grating section 105, and exit diffraction grating section 106 are manufactured using an imprint mold according to any one of first to third embodiments described below.

[0023] The incident diffraction grating unit 104 introduces light L1, which constitutes an image on the microdisplay unit 103, into the glass unit 102. The waveguide diffraction grating unit 105 guides the light L1 introduced by the incident diffraction grating unit 104 to an arbitrary position within the glass unit 102. At this time, the waveguide diffraction grating unit 105 guides the light L1 so as to enlarge the image on the microdisplay unit 103. The arbitrary position within the glass unit 102 is a position within the glass unit 102 that is visible to a wearer wearing the AR glasses 100. The exit diffraction grating unit 106 outputs the light L1 guided by the waveguide diffraction grating unit 105 toward the wearer. In FIG. 1, the flow of movement of the light L1, which constitutes an image on the microdisplay unit 103, is indicated by arrows.

[0024] (Imprint mold 10 of the first embodiment) An imprint mold 10 of the first embodiment will be described with reference to Figure 2. The imprint mold 10 is used to transfer a fine pattern to a diffractive optical element. The imprint mold 10 can also be used to transfer a fine pattern to a replica mold, which serves as a duplication plate for transferring the pattern to a diffractive optical element.

[0025] The imprint mold 10 is manufactured by photolithography, for example, or may be a replica mold obtained by transferring a master mold manufactured by photolithography.

[0026] The imprint mold 10 has a pattern surface 10S on which a pattern 10P is formed. The pattern 10P has a plurality of unit shapes U1 repeatedly arranged in a first direction D1 at a predetermined pitch P1. The pitch P1 is, for example, not less than 300 nm and not more than 500 nm.

[0027] The unit shape U1 has a concave-convex shape extending in a second direction D2 that intersects with the first direction D1. As an example, the second direction D2 is a direction perpendicular to the first direction D1, and is the depth direction of the paper in FIG. 2. The first direction D1 and the second direction D2 are parallel to the plane on which the pattern surface 10S extends. The height direction is defined as a third direction D3.

[0028] The pattern 10P has a sawtooth cross section formed by arranging a plurality of unit shapes U1 in the first direction D1. The uneven shape of the unit shapes U1 includes a flat bottom surface 11, an inclined surface 12, and a stepped surface 13.

[0029] The flat bottom surface 11 is located at the bottom of the uneven shape. The flat bottom surface 11 connects the lower ends of the inclined surfaces 12 and the stepped surfaces 13. The flat bottom surface 11 is closer to being parallel to the plane on which the patterned surface 10S extends than the inclined surfaces 12 and the stepped surfaces 13. For example, the flat bottom surface 11 is parallel to the plane on which the patterned surface 10S extends.

[0030] The uneven shape of the unit shape U1 has convex portions including inclined surfaces 12 and stepped surfaces 13. In the pattern 10P, the flat bottom surfaces 11 are located between the convex portions of adjacent unit shapes U1. In the pattern 10P, the stepped surfaces 13, the flat bottom surfaces 11, and the inclined surfaces 12 are repeatedly arranged in this order along the first direction D1.

[0031] The inclined surface 12 is inclined with respect to the plane on which the pattern surface 10S extends. The inclination angle θ1 of the inclined surface 12 with respect to the pattern surface 10S is, for example, 20 degrees or more and 60 degrees or less. The lower limit of the inclination angle θ1 is more preferably 30 degrees or more. The upper limit of the inclination angle θ1 is more preferably 50 degrees or less.

[0032] The convex portion including the inclined surface 12 and the step surface 13 has a vertex 14. The vertex 14 is the intersection of the upper end of the inclined surface 12 and the upper end of the step surface 13. The inclined surface 12 is connected to the step surface 13 via the vertex 14. The height H1, which is the distance from the lower end to the upper end of the inclined surface 12 in the third direction D3, i.e., the distance from the bottom flat surface 11 to the vertex 14, is, for example, 100 nm or more and 300 nm or less.

[0033] The step surface 13 connects the upper end of the inclined surface 12 and the end of the bottom flat surface 11. The step surface 13 faces the opposite side to the direction in which the inclined surface 12 faces in the first direction D1. As an example, the step surface 13 is perpendicular to the plane on which the pattern surface 10S extends. However, the step surface 13 is not limited to this, and may have any angle with respect to the plane on which the pattern surface 10S extends that is greater than the inclination angle θ1 and less than 90 degrees, or may have any angle with respect to the plane on which the pattern surface 10S extends that is smaller than the inclination angle θ1.

[0034] The bottom flat surface 11 has a width W1 along the first direction D1. The width W1 is 10% to 50% of the pitch P1. That is, the ratio of the area of ​​the bottom flat surface 11 to the entire area of ​​the unit shape U1 is 10% to 50% in top view from a viewpoint opposite to the plane including the first direction D1 and the second direction D2. The ratio of the area of ​​the bottom flat surface 11 to the entire area of ​​the unit shape U1 is the value obtained by dividing the area of ​​the bottom flat surface 11 by the entire area of ​​the unit shape U1 in top view from a viewpoint opposite to the plane including the first direction D1 and the second direction D2.

[0035] The ratio of the area of ​​the bottom flat surface 11 to the entire area of ​​the unit shape U1 may be calculated, for example, from an image captured from a position facing a plane including the first direction D1 and the second direction D2. Alternatively, the ratio of the width W1 to the pitch P1 in a cross-sectional view perpendicular to the second direction D2 may be used as the ratio of the area of ​​the bottom flat surface 11 to the entire area of ​​the unit shape U1.

[0036] When the imprint mold 10 is a master mold manufactured by photolithography, the material constituting the pattern surface 10S includes at least one of silicon, silicon compounds, diamond, metal, metal compounds, ceramic, and resin. The silicon compounds include at least one of quartz and glass.

[0037] Furthermore, when the imprint mold 10 is a replica mold onto which a master mold has been transferred, the material constituting the pattern surface 10S may be, for example, a plating material obtained by plating the master mold and then releasing the plating from the master mold. An example of the plating material is a metal such as nickel. Furthermore, when the imprint mold 10 is a replica mold, the material constituting the pattern surface 10S may be, for example, a resin or diamond film onto which a fine pattern of the master mold has been transferred using an imprinting method. For example, the imprint mold 10 may be a master mold in which a pattern 10P has been formed by lithography on a photosensitive resin or an electron beam photosensitive resin.

[0038] The pattern 10P may include surfaces other than the bottom flat surface 11, the inclined surface 12, and the stepped surface 13. For example, a convex portion including the inclined surface 12 and the stepped surface 13 may have a top surface instead of the apex portion 14. The width of this top surface along the first direction D1 may be less than 10% of the pitch P1.

[0039] (Transfer recipient of the first embodiment) FIG. 2 shows a diffractive optical element 20, which is an example of a transfer target manufactured by the imprint method using the imprint mold 10. The diffractive optical element 20 can be used, for example, for the input diffraction grating portion 104, the waveguide diffraction grating portion 105, and the output diffraction grating portion 106. Note that the diffractive optical element 20 is not limited to being used in AR glasses 100, but can also be used in other devices such as displays, recording media, biochips, optical devices, diffraction grating devices, Fresnel lenses, lenticular lenses, and microlenses. The transfer target may also be a replica mold using the imprint mold 10 as a master mold.

[0040] The diffractive optical element 20 has a pattern surface 20S. A pattern 20P that is an inverse of the pattern 10P of the imprint mold 10 is formed on the pattern surface 20S. The pattern 20P has a top flat surface 21, an inclined surface 22, and a stepped surface 23 that are repeatedly arranged along the first direction D1. That is, the pattern 20P has an uneven shape in which the top flat surface 21, the inclined surface 22, and the stepped surface 23 form a repeating unit. The uneven shape extends along the second direction D2.

[0041] In the diffractive optical element 20, the pitch P2 between the repeating units of the pattern 20P is equal to the pitch P1 of the imprint mold 10. The inclination angle θ2 of the inclined surface 22 of the diffractive optical element 20 relative to the pattern surface 20S is equal to the inclination angle θ1 of the inclined surface 12 of the imprint mold 10. In the first direction D1, the width W2 of the top flat surface 21 is equal to the width W1 of the bottom flat surface 11 of the imprint mold 10. In the third direction D3, the height H2, which is the distance from the lower end to the upper end of the inclined surface 22 of the diffractive optical element 20, is equal to the height H1, which is the distance from the lower end to the upper end of the inclined surface 12 of the imprint mold 10.

[0042] The diffractive optical element 20 is a blazed diffraction grating configured to increase the diffraction efficiency of light having a specific wavelength (blaze wavelength). The diffractive optical element 20 is made of a light-transmitting resin material. In the diffractive optical element 20, the pitch P2, tilt angle θ2, width W2, height H2, and resin material of the diffractive optical element 20 are selected to increase the diffraction efficiency of light having a specific wavelength. For example, by changing the pitch P2, it is possible to change the diffraction angle of light having a specific wavelength.

[0043] (Actions and Effects of the First Embodiment) (1-1) In the imprint mold 10 of the first embodiment, a flat bottom surface 11 is formed at the bottom of the uneven shape of the pattern 10P. For example, assume that the flat bottom surface 11 is not provided at the bottom of the uneven shape of the unit shape U1, and the lower ends of the inclined surfaces 12 and the stepped surfaces 13 form an apex. In this case, when the pattern 10P is formed on the imprint mold 10 by photolithography, the shape of the apex formed by the lower ends of the inclined surfaces 12 and the stepped surfaces 13 is likely to vary due to variations in processing conditions in photolithography. For example, the apex formed by the lower ends of the inclined surfaces 12 and the stepped surfaces 13 is affected by both variations in processing conditions from the inclined surface 12 side and variations in processing conditions from the stepped surfaces 13 side, and therefore the shape is likely to become unstable, such as by unintended rounding.

[0044] In this regard, in the imprint mold 10 of the first embodiment, the ratio of the area of ​​the bottom flat surface 11 to the total area of ​​the unit shape U1 is 10% or more in a top view from a viewpoint opposite to the plane including the first direction D1 and the second direction D2. Therefore, a steep shape is not formed at the bottom of the uneven shape of the unit shape U1 of the pattern 10P. Therefore, at the bottom of the uneven shape of the unit shape U1, the variation in shape within the pattern surface 10S and the variation in shape between lots can be reduced. This ultimately improves the processing accuracy of the transfer object to which the pattern 10P of the imprint mold 10 is transferred.

[0045] The above-described effects are not limited to the case where the imprint mold 10 is manufactured by photolithography. For example, even when the imprint mold 10 is a replica mold manufactured by plating or an imprinting method, the variation in shape at the bottom of the concave-convex shape of the unit shape U1 can be suppressed.

[0046] (1-2) By using the imprint mold 10 to transfer the pattern 10P, on which the flat bottom surface 11 is formed, to the diffractive optical element 20 as the pattern 20P, a flat top surface 21 is formed at the top of the pattern 20P. That is, since a steep shape is not formed at the top of the uneven shape of the pattern 20P of the diffractive optical element 20, it is possible to prevent the top of the pattern 20P from being damaged or deformed when, for example, the diffractive optical element 20 is released from the imprint mold 10. That is, the accuracy of the shape of the diffractive optical element 20 can be improved.

[0047] (1-3) In the imprint mold 10 of the first embodiment, the ratio of the area of ​​the bottom flat surface 11 to the total area of ​​the unit shape U1 is configured to be 50% or less in a top view seen from a viewpoint opposite to the plane including the first direction D1 and the second direction D2. For example, assuming that the pitch P1 and height H1 are constant, as the bottom flat surface 11 increases, the inclination angle θ1 of the imprint mold 10 and the corresponding inclination angle θ2 of the diffractive optical element 20 increase. Furthermore, as the inclination angle θ2 approaches 90 degrees, the diffraction efficiency of the diffractive optical element 20 decreases. This is because the blazed diffraction grating of the diffractive optical element 20 approaches a diffraction grating with a rectangular concave-convex pattern.

[0048] As an example, a conventional blazed diffraction grating without a top flat surface 21 has approximately twice the diffraction efficiency for light having a specific wavelength compared to a diffraction grating configured with a rectangular concave-convex pattern. In contrast, a blazed diffraction grating in which the area ratio of the top flat surface 21 per repeating unit is 50% or less, as in the first embodiment, has approximately 1.5 times the diffraction efficiency for light having a specific wavelength compared to a diffraction grating configured with a rectangular concave-convex pattern. In other words, by setting the ratio of the area of ​​the bottom flat surface 11 to the total area of ​​the unit shape U1 to be 10% or more and 50% or less, it is possible to obtain the effects of (1-1) and (1-2) while improving the diffraction efficiency compared to a diffraction grating configured with a rectangular concave-convex pattern.

[0049] (1-4) The material constituting the pattern surface 10S includes at least one of silicon, silicon compounds, diamond, metal, metal compounds, ceramic, and resin. By constituting the pattern surface 10S with such materials, the pattern 10P can be formed on the pattern surface 10S by photolithography.

[0050] (Modification of the imprint mold 10 of the first embodiment) As shown in FIG. 3, in the first embodiment, the imprint mold 10 may include an etching stopper layer 15. The etching stopper layer 15 is located below the convex portion including the inclined surface 12 and the step surface 13 in the concave-convex shape of the unit shape U1. The etching stopper layer 15 forms a bottom flat surface 11 at the bottom of the concave-convex shape of the unit shape U1. The etching stopper layer 15 is disposed as a layer extending over the entire area of ​​the pattern 10P along the plane on which the pattern surface 10S extends.

[0051] In the imprint mold 10, portions other than the etching stopper layer 15 are made of a first material, and the etching stopper layer 15 is made of a second material different from the first material. The second material is a material that is less easily etched than the first material under predetermined etching conditions, i.e., a material with a slower etching rate. In this case, the imprint mold 10 is manufactured by forming a pattern 10P in a laminate having a layer made of the first material on the etching stopper layer 15 made of the second material. In the imprint mold 10, the layer below the etching stopper layer 15 may also be made of the first material.

[0052] The pattern surface 10S includes a first portion made of a first material and a second portion made of a second material. The first portion includes an inclined surface 12 and a stepped surface 13. The second portion includes a bottom flat surface 11.

[0053] By forming the flat bottom surface 11 from the second material that is difficult to etch, it is possible to absorb, for example, local variations in the etching depth on the flat bottom surface 11. In other words, variations in the shape of the flat bottom surface 11 can be further suppressed.

[0054] (Imprint mold 30 of the second embodiment) An imprint mold 30 of the second embodiment will be described with reference to Figure 4. The imprint mold 30 may be manufactured by photolithography, similar to the imprint mold 10 of the first embodiment, or may be a replica mold onto which a master mold manufactured by photolithography has been transferred.

[0055] The imprint mold 30 has a pattern surface 30S that extends in a plane including a first direction D1 and a second direction D2. A pattern 30P is formed on the pattern surface 30S. The pattern 30P has a plurality of unit shapes U2 that are repeatedly arranged in the first direction D1 at a predetermined pitch P3. The pitch P3 is, for example, not less than 300 nm and not more than 500 nm.

[0056] The unit shape U2 has a concave-convex shape extending in the second direction D2. The pattern 30P has a sawtooth cross-sectional shape formed by arranging a plurality of unit shapes U2 in the first direction D1. The concave-convex shape of the unit shape U2 has a convex portion including a flat top surface 31, an inclined surface 32, and a stepped surface 33. The flat top surface 31 forms the top surface of the convex portion of the concave-convex shape of the unit shape U2. In the pattern 30P, the inclined surface 32, the flat top surface 31, and the stepped surface 33 are repeatedly arranged in this order along the first direction D1.

[0057] The top flat surface 31 is located at the top of the uneven shape. The top flat surface 31 connects the upper ends of the inclined surfaces 32 and the step surfaces 33. The top flat surface 31 is closer to being parallel to the plane on which the pattern surface 30S extends than the inclined surfaces 32 and the step surfaces 33. For example, the top flat surface 31 is parallel to the plane on which the pattern surface 30S extends.

[0058] The inclined surface 32 is inclined with respect to the plane on which the pattern surface 30S extends. The inclination angle θ3 of the inclined surface 32 with respect to the pattern surface 30S can be in the same numerical range as the inclination angle θ1 in the first embodiment, for example.

[0059] The pattern 30P has a vertex 34 located between the convex portions of adjacent unit shapes U2. The vertex 34 is the intersection point between the lower end of the inclined surface 32 and the lower end of the step surface 33. The inclined surface 32 is connected to the step surface 33 via the vertex 34. The height H3, which is the distance from the lower end to the upper end of the inclined surface 32 in the third direction D3, i.e., the distance from the top flat surface 31 to the vertex 34, is, for example, 100 nm or more and 300 nm or less.

[0060] The step surface 33 connects the lower end of the inclined surface 32 and the end of the top flat surface 31. The step surface 33 faces in the first direction D1 opposite to the direction in which the inclined surface 32 faces. As an example, the step surface 33 is perpendicular to the plane in which the pattern surface 30S extends.

[0061] The top flat surface 31 has a width W3 along the first direction D1. The width W3 is 10% to 50% of the pitch P3. That is, in a top view seen from a viewpoint opposite to a plane including the first direction D1 and the second direction D2, the ratio of the area of ​​the top flat surface 31 to the total area of ​​the unit shape U2 is 10% to 50%. The ratio of the area of ​​the top flat surface 31 to the total area of ​​the unit shape U2 can be calculated using the same calculation method as in the first embodiment.

[0062] The material constituting the pattern surface 30S of the imprint mold 30 can be, for example, the same material as the material constituting the pattern surface 10S of the imprint mold 10 of the first embodiment.

[0063] The pattern 30P may include surfaces other than the top flat surface 31, the inclined surface 32, and the stepped surface 33. For example, the pattern 30P may have a bottom surface between the convex portions of adjacent unit shapes U2 instead of the vertices 34. The width of this bottom surface along the first direction D1 may be less than 10% of the pitch P3.

[0064] (Transfer recipient of the second embodiment) FIG. 4 shows a diffractive optical element 40, which is an example of a transfer target manufactured by the imprint method using the imprint mold 30.

[0065] The diffractive optical element 40 is a blazed diffraction grating. The diffractive optical element 40 has a pattern surface 40S. A pattern 40P that is an inverted version of the pattern 30P of the imprint mold 30 is formed on the pattern surface 40S. The pattern 40P has an uneven shape with a repeating unit of a bottom flat surface 41, an inclined surface 42, and a stepped surface 43 that are aligned along a first direction D1.

[0066] In the diffractive optical element 40, the pitch P4 at which the repeating units of the pattern 40P are arranged is equal to the pitch P3 of the imprint mold 30. The inclination angle θ4 of the inclined surface 42 of the diffractive optical element 40 with respect to the pattern surface 40S is equal to the inclination angle θ3 of the inclined surface 32 of the imprint mold 30. In the first direction D1, the width W4 of the bottom flat surface 41 is equal to the width W3 of the top flat surface 31 of the imprint mold 30. In the third direction D3, the height H4, which is the distance from the lower end to the upper end of the inclined surface 42 of the diffractive optical element 40, is equal to the height H3 of the imprint mold 30.

[0067] (Actions and Effects of the Second Embodiment) (2-1) In the imprint mold 30 of the second embodiment, the ratio of the area of ​​the top flat surface 31 to the total area of ​​the unit shape U2 is 10% or more in a top view from a viewpoint opposite to the plane including the first direction D1 and the second direction D2. Therefore, a steep shape is not formed at the top of the uneven shape of the unit shape U2 of the pattern 30P. Therefore, at the top of the uneven shape of the unit shape U2, the variation in shape within the pattern surface 30S and the variation in shape between lots can be reduced. This in turn improves the processing accuracy of the transfer object to which the pattern 30P of the imprint mold 30 is transferred.

[0068] The above-described effects are not limited to the case where the imprint mold 30 is manufactured by photolithography. For example, even when the imprint mold 30 is a replica mold manufactured by plating or an imprinting method, the variation in shape at the bottom of the concave-convex shape of the unit shape U2 can be suppressed.

[0069] (2-2) When the pattern 30P of the imprint mold 30 is transferred to a transfer target, the top flat surface 31 formed on the pattern 30P comes into strong contact with the transfer target. Therefore, the load applied to the top of the pattern 30P can be more dispersed than if the top of the uneven shape of the pattern 30P did not have the top flat surface 31 and the top end of the inclined surface 32 and the top end of the stepped surface 33 formed an apex. This improves the durability of the imprint mold 30.

[0070] (2-3) In the imprint mold 30 of the second embodiment, the ratio of the area of ​​the top flat surface 31 to the total area of ​​the unit shape U2 is set to 50% or less in a top view seen from a viewpoint opposite to the plane including the first direction D1 and the second direction D2. This makes it possible to obtain the effects of (2-1) and (2-2) while improving the diffraction efficiency of the imprint mold 30 compared to a diffraction grating configured with a rectangular concave-convex pattern.

[0071] (Modification of the imprint mold 30 of the second embodiment) As shown in FIG. 5, in the second embodiment, the imprint mold 30 may include an etching stopper layer 35. The etching stopper layer 35 is located at the top of the uneven shape of the unit shape U2. The etching stopper layer 35 forms a flat top surface 31 within the uneven shape of the unit shape U2. The etching stopper layers 35 are arranged intermittently along the first direction D1. Furthermore, each etching stopper layer 35 extends along the second direction D2.

[0072] In the imprint mold 30, the portions other than the etching stopper layer 35 are made of a first material, and the etching stopper layer 35 is made of a second material that has an etching rate slower than that of the first material. In this case, the etching stopper layer 35 of the imprint mold 30 is manufactured by, for example, forming a striped line pattern made of the second material on a layer made of the first material by lithography or the like.

[0073] The pattern surface 30S includes a first portion made of a first material and a second portion made of a second material. The first portion includes an inclined surface 32 and a stepped surface 33. The second portion includes a top flat surface 31. Note that an etching stopper layer 35 may form part of the inclined surface 32 and the stepped surface 33.

[0074] By forming the top flat surface 31 from the second material that is difficult to etch, it is possible to absorb, for example, local variations in the etching depth on the top flat surface 31. In other words, variations in the shape of the top flat surface 31 can be further suppressed.

[0075] (Imprint mold 50 of the third embodiment) An imprint mold 50 of the third embodiment will be described with reference to Fig. 6. The imprint mold 50 may be manufactured by photolithography, similar to the imprint mold 10 of the first embodiment, or may be a replica mold onto which a master mold manufactured by photolithography has been transferred.

[0076] The imprint mold 50 has a pattern surface 50S that extends in a plane including a first direction D1 and a second direction D2. A pattern 50P is formed on the pattern surface 50S. The pattern 50P has a plurality of unit shapes U3 that are repeatedly arranged in the first direction D1 at a predetermined pitch P5. The pitch P5 is, for example, not less than 300 nm and not more than 500 nm.

[0077] The unit shape U3 has a concave-convex shape extending in the second direction D2. The pattern 50P has a sawtooth cross-sectional shape formed by arranging a plurality of unit shapes U3 in the first direction D1. The concave-convex shape of the unit shape U3 includes a bottom flat surface 51, a top flat surface 52, an inclined surface 53, and a stepped surface 54.

[0078] The bottom flat surface 51 is located at the bottom of the uneven shape. The bottom flat surface 51 connects the lower end of the inclined surface 53 and the lower end of the stepped surface 54. The uneven shape of the unit shape U3 has a convex portion including the top flat surface 52, the inclined surface 53, and the stepped surface 54. In the pattern 50P, the bottom flat surface 51 is located between the convex portions of adjacent unit shapes U3. In the pattern 50P, the bottom flat surface 51, the inclined surface 53, the top flat surface 52, and the stepped surface 54 are repeatedly arranged in this order along the first direction D1.

[0079] The top flat surface 52 is located at the top of the uneven shape. The top flat surface 52 connects the upper ends of the inclined surfaces 53 and the step surfaces 54. The bottom flat surface 51 and the top flat surface 52 are closer to being parallel to the plane on which the pattern surface 50S extends than the inclined surfaces 53 and the step surfaces 54. For example, the bottom flat surface 51 and the top flat surface 52 are parallel to the plane on which the pattern surface 50S extends.

[0080] The inclined surface 53 is inclined with respect to the plane on which the pattern surface 50S extends. The step surface 54 faces in the first direction D1 opposite to the direction in which the inclined surface 53 faces. As an example, the step surface 54 is perpendicular to the plane on which the pattern surface 50S extends.

[0081] The inclination angle θ5 of the inclined surface 53 with respect to the pattern surface 50S can be, for example, in the same numerical range as the inclination angle θ1 in the first embodiment. The height H5, which is the distance from the lower end to the upper end of the inclined surface 53 in the third direction D3, i.e., the distance from the bottom flat surface 51 to the top flat surface 52, is, for example, 100 nm to 300 nm.

[0082] The bottom flat surface 51 has a width W5 along the first direction D1. The width W5 is 10% or more of the pitch P5. The top flat surface 52 has a width W6 along the first direction D1. The width W6 is 10% or more of the pitch P5. In other words, in a top view seen from a viewpoint opposite to a plane including the first direction D1 and the second direction D2, the ratio of the area of ​​the bottom flat surface 51 to the entire area of ​​the unit shape U3 and the ratio of the area of ​​the top flat surface 52 to the entire area of ​​the unit shape U3 are each 10% or more.

[0083] The sum of the widths W5 and W6 is 50% or less of the pitch P5. That is, in a top view seen from a viewpoint opposite to a plane including the first direction D1 and the second direction D2, the ratio of the sum of the area of ​​the bottom flat surface 51 and the area of ​​the top flat surface 52 to the entire area of ​​the unit shape U3 is 50% or less. The ratios of the area of ​​the bottom flat surface 51 and the area of ​​the top flat surface 52 to the entire area of ​​the unit shape U3 can be calculated using the same calculation method as in the first embodiment.

[0084] The material constituting the pattern surface 50S of the imprint mold 50 can be, for example, the same material as the material constituting the pattern surface 10S of the imprint mold 10 of the first embodiment.

[0085] (Transfer recipient of the third embodiment) FIG. 6 shows a diffractive optical element 60, which is an example of a transfer target manufactured by the imprint method using the imprint mold 50.

[0086] The diffractive optical element 60 is a blazed diffraction grating. The diffractive optical element 60 has a pattern surface 60S. A pattern 60P that is an inverted version of the pattern 50P of the imprint mold 50 is formed on the pattern surface 60S. The pattern 60P has an uneven shape with a top flat surface 61, a bottom flat surface 62, an inclined surface 63, and a stepped surface 64 arranged along a first direction D1 as repeating units.

[0087] In the diffractive optical element 60, the pitch P6 of the repeating units of the pattern 60P is equal to the pitch P5 of the imprint mold 50. The inclination angle θ6 of the inclined surface 63 of the diffractive optical element 60 with respect to the plane on which the pattern surface 60S extends is equal to the inclination angle θ5 of the inclined surface 53 of the imprint mold 50. In the first direction D1, the width W7 of the top flat surface 61 is equal to the width W5 of the bottom flat surface 51 of the imprint mold 50. In the first direction D1, the width W8 of the bottom flat surface 62 is equal to the width W6 of the top flat surface 52 of the imprint mold 50. In the third direction D3, the height H6, which is the distance from the lower end to the upper end of the inclined surface 63 of the diffractive optical element 60, is equal to the height H5 of the imprint mold 50.

[0088] (Actions and Effects of the Third Embodiment) (3-1) In the imprint mold 50 of the third embodiment, the ratio of the area of ​​the bottom flat surface 51 to the total area of ​​the unit shape U3 is 10% or more in a top view from a viewpoint opposite to the plane including the first direction D1 and the second direction D2. Furthermore, the ratio of the area of ​​the top flat surface 52 to the total area of ​​the unit shape U3 is 10% or more. This achieves both the effects (1-1) and (1-2) of the first embodiment and the effects (2-1) and (2-2) of the second embodiment. That is, since the bottoms and tops of the uneven shape of the unit shapes U3 of the pattern 50P do not have steep shapes, the in-plane shape variation of the pattern surface 50S and the shape variation between lots at the bottoms and tops of the uneven shape of the unit shapes U3 can be reduced. This ultimately improves the processing accuracy of the transfer object to which the pattern 50P of the imprint mold 50 is transferred.

[0089] The above-described effects are not limited to the case where the imprint mold 50 is manufactured by photolithography. For example, even when the imprint mold 50 is a replica mold manufactured by plating or an imprinting method, the variations in shape at the bottom and top of the concave-convex shape of the unit shape U3 can be suppressed.

[0090] (3-2) In the imprint mold 50 of the third embodiment, the ratio of the total area of ​​the bottom flat surface 51 and the top flat surface 52 to the total area of ​​the unit shape U3 is 50% or less in a top view seen from a viewpoint opposite to the plane including the first direction D1 and the second direction D2. This makes it possible to improve the diffraction efficiency of the imprint mold 50 compared to a diffraction grating configured with a rectangular concave-convex pattern, while also achieving the effect of (3-1).

[0091] (Modification of the imprint mold 50 of the third embodiment) 7, the imprint mold 50 of the third embodiment may include an etching stopper layer 55 similar to the etching stopper layer 15 of the first embodiment. The etching stopper layer 55 forms a bottom flat surface 51. In this case, the imprint mold 50 is configured such that the portions other than the etching stopper layer 55 are made of a first material, and the etching stopper layer 55 is made of a second material that has an etching rate slower than that of the first material.

[0092] In this case, the first portion of pattern surface 50S made of the first material includes top flat surface 52, inclined surface 53, and stepped surface 54. Furthermore, the second portion of pattern surface 50S made of the second material includes bottom flat surface 51. As described above, by making bottom flat surface 51 out of the second material that is difficult to etch, local variations in the etching depth on bottom flat surface 51 can be absorbed, and therefore variations in the shape of bottom flat surface 51 can be further suppressed.

[0093] 8, the imprint mold 50 of the third embodiment may include an etching stopper layer 56 similar to the etching stopper layer 35 of the second embodiment. The etching stopper layer 56 forms the top flat surface 52. In this case, the imprint mold 50 is configured such that the portions other than the etching stopper layer 56 are made of a first material, and the etching stopper layer 56 is made of a second material that has an etching rate slower than that of the first material.

[0094] In this case, the first portion of pattern surface 50S made of the first material includes bottom flat surface 51, inclined surface 53, and step surface 54. Furthermore, the second portion of pattern surface 50S made of the second material includes top flat surface 52. As described above, by making top flat surface 52 out of the second material that is difficult to etch, local variations in the etching depth at top flat surface 52 can be absorbed, and therefore variations in the shape of top flat surface 52 can be further suppressed.

[0095] 9, the imprint mold 50 of the third embodiment may include both an etching stopper layer 55 and an etching stopper layer 56. In this case, the imprint mold 50 is configured such that the portions other than the etching stopper layers 55, 56 are made of a first material, and the etching stopper layers 55, 56 are made of a second material having an etching rate slower than that of the first material. Note that the material constituting the etching stopper layer 55 and the material constituting the etching stopper layer 56 may be different materials.

[0096] In this case, the first portion of pattern surface 50S made of the first material includes inclined surface 53 and stepped surface 54. Furthermore, the second portion of pattern surface 50S made of the second material includes bottom flat surface 51 and top flat surface 52. As described above, by making bottom flat surface 51 and top flat surface 52 out of the second material that is resistant to etching, variation in the shapes of bottom flat surface 51 and top flat surface 52 can be further suppressed.

[0097] (Test example) A test example using the imprint mold will be described below. Note that the test example below is an example for explaining the effects of the above embodiment, and does not limit the present disclosure.

[0098] (Samples A1 to A7) In the test examples, molds having a flat bottom surface 11, like the imprint mold 10 of the first embodiment, were fabricated as samples A1 to A7. First, a mold substrate 200 was prepared as shown in FIG. 10. A 4-inch quartz wafer substrate (manufactured by Shin-Etsu Quartz Corporation) was used as the mold substrate 200. An electron beam resist layer 300 was then formed on the mold substrate 200. PMMA (polymethyl methacrylate resin, manufactured by Nippon Kayaku Co., Ltd.) was used as the electron beam resist layer 300. The electron beam resist layer 300 was formed by spin coating on the mold substrate 200 to a thickness of 300 nm.

[0099] As shown in FIG. 11 , a resist pattern was then formed on the electron beam resist layer 300 by gradation drawing using an electron beam lithography machine and spray development using MIBK (methyl isobutyl ketone, manufactured by Kanto Chemical Co., Inc.) as a developer. The cross-sectional shape of the resist pattern was a blazed shape having an inclined surface 301 and a stepped surface 302. The blazed shape has a sawtooth shape having at least an inclined surface 301 and a stepped surface 302. The spray development treatment time was set to 180 seconds so that a portion of the surface of the mold substrate 200 was exposed between the lower ends of the inclined surface 301 and the stepped surface 302. The pitch of the blazed shape formed on the electron beam resist layer 300 was set to 500 nm.

[0100] In this state, the mold substrate 200 was dry-etched using an ICP dry etching apparatus, thereby transferring the blazed shape of the electron beam resist layer 300 to the underlying mold substrate 200. The etching conditions for the mold substrate 200 were such that the etching selectivity with respect to the electron beam resist layer 300 was approximately 1. Specific dry etching conditions were a C3F8 flow rate of 30 sccm, an O2 flow rate of 5 sccm, an Ar flow rate of 15 sccm, a pressure of 2 Pa, an ICP power of 300 W, and an RIE power of 150 W. The dry etching time was set until the electron beam resist layer 300 was completely removed. The remaining electron beam resist layer 300 was then peeled off from the mold substrate 200 by wet cleaning with SPM (sulfuric acid / hydrogen peroxide solution).

[0101] Using the above procedure, molds having a flat bottom surface 11 as shown in FIG. 2 were fabricated for samples A1 to A7. For samples A1 to A7, the pitch P1 of the blazed shape was 400 nm, and the height H1 of the blazed shape was 200 nm. For samples A1 to A7, the design dimensions (target values) were changed so that the width W1 of the flat bottom surface 11 was different from one another. The width W1 of the flat bottom surface 11 was set to 20 nm, 40 nm, 80 nm, 120 nm, 160 nm, 200 nm, and 240 nm in the order of samples A1 to A7.

[0102] (Samples B1 to B7) In the test example, molds having a flat top surface 31, like the imprint mold 30 of the second embodiment, were fabricated as samples B1 to B7. For samples B1 to B7, a mold substrate 200 having an electron beam resist layer 300 formed thereon was prepared, similar to samples A1 to A7 (see FIG. 10).

[0103] 12, a resist pattern was then formed on the electron beam resist layer 300 by gradation drawing and spray development. For samples B1 to B7, the resist pattern was formed in the same manner as for samples A1 to A7, except that the spray development treatment time was set to 120 seconds so that the surface of the mold substrate 200 would not be exposed between the lower end of the inclined surface 301 and the lower end of the stepped surface 302.

[0104] As shown in Fig. 13, the mold substrate 200 was then dry-etched using an ICP dry etching device, thereby transferring the blazed pattern of the electron beam resist layer 300 to the underlying mold substrate 200. The etching conditions for the mold substrate 200 were the same as those for samples A1 to A7. The dry etching time was set so that the electron beam resist layer 300 was not completely removed, but rather a portion remained. Thereafter, the remaining electron beam resist layer 300 was peeled off from the mold substrate 200 by wet cleaning.

[0105] Using the above procedure, molds having a top flat surface 31 as shown in FIG. 4 were fabricated for samples B1 to B7. For samples B1 to B7, the pitch P3 of the blazed shape was 400 nm, and the height H3 of the blazed shape was 200 nm. For samples B1 to B7, the design dimensions (target values) were changed so that the width W3 of the top flat surface 31 differed from one another. The width W3 of the top flat surface 31 was set to 20 nm, 40 nm, 80 nm, 120 nm, 160 nm, 200 nm, and 240 nm, in the order of samples B1 to B7. Note that FIG. 13 shows the positions of the top flat surface 31, inclined surface 32, and stepped surface 33 when the mold substrate 200 is matched to the imprint mold 30.

[0106] (Samples C1 to C7) In the test examples, molds having both a bottom flat surface 51 and a top flat surface 52, like the imprint mold 50 of the third embodiment, were fabricated as samples C1 to C7. For samples C1 to C7, a mold substrate 200 having an electron beam resist layer 300 formed thereon was prepared, similar to samples A1 to A7 (see FIG. 10).

[0107] Next, a resist pattern was formed on the electron beam resist layer 300 by gradation drawing and spray development. For samples C1 to C7, similar to samples A1 to A7, the spray development treatment time was set to 180 seconds so that part of the surface of the mold substrate 200 was exposed between the lower end of the inclined surface 301 and the lower end of the stepped surface 302 (see FIG. 11).

[0108] As shown in Fig. 14, the mold substrate 200 was then dry-etched using an ICP dry etching apparatus, thereby transferring the blazed pattern of the electron beam resist layer 300 to the underlying mold substrate 200. The etching conditions for the mold substrate 200 were the same as those in Example 1. The dry etching time was set so that the electron beam resist layer 300 was not completely removed, but rather a partial residual image was left. Thereafter, the remaining electron beam resist layer 300 was peeled off from the mold substrate 200 by wet cleaning.

[0109] Using the above procedure, molds having both a bottom flat surface 51 and a top flat surface 52 as shown in FIG. 6 were fabricated for samples C1 to C7. In samples C1 to C7, the pitch P5 of the blazed shape was 400 nm, and the height H5 of the blazed shape was 200 nm. In samples C1 to C7, the design dimensions (target values) were changed so that the width W5 of the bottom flat surface 51 was different from one another. The width W5 of the bottom flat surface 51 was set to 10 nm, 20 nm, 40 nm, 60 nm, 80 nm, 100 nm, and 120 nm, in the order of samples C1 to C7. Similarly, the design dimensions were changed so that the width W6 of the top flat surface 52 was different from one another from sample C1 to C7. The width W6 of the top flat surface 52 was set to 10 nm, 20 nm, 40 nm, 60 nm, 80 nm, 100 nm, and 120 nm in the order of samples C1 to C7. Note that Fig. 14 shows the positions of the bottom flat surface 51, the top flat surface 52, the inclined surface 53, and the step surface 54 when the mold substrate 200 corresponds to the imprint mold 50.

[0110] (Sample X1) For sample X1, a mold was fabricated in which the bottom and top of the blazed shape had steep vertices rather than flat surfaces. For sample X1, similar to samples A1 to A7, a mold substrate 200 on which an electron beam resist layer 300 was formed was prepared (see FIG. 10). Next, a resist pattern was formed on the electron beam resist layer 300 by gradation drawing and spray development. At this time, similar to samples A1 to A7, the spray development treatment time was set to 120 seconds so that the surface of the mold substrate 200 would not be exposed between the lower end of the inclined surface 301 and the lower end of the stepped surface 302 (see FIG. 12).

[0111] Next, the mold substrate 200 was dry-etched using an ICP dry etching device, thereby transferring the blazed pattern of the electron beam resist layer 300 to the underlying mold substrate 200. At this time, the same etching conditions for the mold substrate 200 as those for samples A1 to A7 were adopted. The dry etching time was set to be until the electron beam resist layer 300 was completely removed. Thereafter, the remaining electron beam resist layer 300 was peeled off from the mold substrate 200 by wet cleaning.

[0112] By the above procedure, a mold was produced having a blazed shape with inclined surfaces 201 and step surfaces 202 as shown in Fig. 15. In sample X1, the pitch of the blazed shape was 400 nm, and the height of the blazed shape was 200 nm.

[0113] (evaluation) Each mold was evaluated for three items: mold shape accuracy, mold durability, and transferability of the imprint pattern.

[0114] The mold shape accuracy was evaluated by measuring the pitch, height, and tilt angle of the blazed shape at 10 locations per mold, as these dimensions are likely to affect the function of the blazed diffraction grating. If all measured dimensions were within ±5% of the design value, the mold was deemed to have passed. If any dimension exceeded ±5%, the mold was deemed to have failed. An accuracy of ±5% of the design value means that the measured dimension was between 0.95 and 1.05 times the design value.

[0115] The pitch was measured using a CD-SEM (critical dimension SEM, manufactured by Hitachi High-Tech Corporation) in a top view from a viewpoint opposite to the plane along which the blazed shape extends. The height and tilt angle were measured using a scanning probe microscope (manufactured by Hitachi High-Tech Corporation) in a cross-sectional view of the mold cut along a plane including the first direction D1 and the third direction D3. The design value of the tilt angle is uniquely determined by the design value of the pitch, the design value of the height, and the design values ​​of the flat surfaces at the bottom and top.

[0116] To evaluate the durability of the mold, the fabricated mold was used as a master mold and photoimprinted 50 times onto a UV-curable resin. The photoimprinting method involved first pre-coating the blazed surface of the mold with a fluorine-based surface treatment agent EGC-1720 (manufactured by 3M Japan Ltd.) as a mold release agent. Then, the silicon substrate to be imprinted was coated with a 300 nm thick photocurable resin PAK-01 (manufactured by Toyo Gosei Co., Ltd.). Next, the photocurable resin was cured by irradiating UV light from the backside of the mold while applying pressure with the blazed pattern surface of the mold facing the surface of the photocurable resin. The photoimprinting conditions were: no pre-bake (room temperature), press pressure of 2 MPa, UV wavelength of 365 nm, and UV exposure of 40 mJ / cm. 2 It was decided.

[0117] Next, each mold after imprinting was observed for the presence or absence of pattern damage. An optical microscope (Nikon Corporation) and a scanning probe microscope (Hitachi High-Tech Corporation) were used for the observations. A 50 μm square area was observed with the optical microscope. A 10 μm square area was observed with the scanning probe microscope. Observations for the presence or absence of pattern damage were made at 10 locations on each mold. If no pattern damage or cracks were found in any of the observed images, the mold was deemed to have passed, and if damage or cracks were found in even one of the observed images, the mold was deemed to have failed.

[0118] The mold transferability was evaluated by measuring the pitch, height, and tilt angle of the blazed shape in the pattern transferred by photoimprinting at 10 points on the transferee. The measurement method and evaluation criteria were the same as those for evaluating the mold shape accuracy.

[0119] The table in Figure 16 shows the design values ​​and evaluation results for each mold fabricated in the test examples. In evaluating the mold shape accuracy, the dimensional measurement results for samples A2 to A7, B2 to B7, and C3 to C7 were within ±5% of the design values. These results confirmed that providing a flat surface on at least one of the bottom and top of the blazed shape and ensuring that the area ratio of the flat surface in the unit shape is 10% or more can suppress shape variation. Among the molds whose dimensions were confirmed to be more than 5% of the design values, sample X1 had particularly large dimensional variation from the design values ​​compared to the other samples.

[0120] In evaluating the durability of the mold, no damage or cracks were observed in the patterns of samples B2 to B7 and C3 to C7 in any of the observation images. These results confirmed that the durability of the mold can be improved by providing a flat top surface on the blazed shape and ensuring that the ratio of the area of ​​the flat top surface to the unit shape is 10% or more.

[0121] In evaluating the mold transferability, the dimensional measurement results of the transferred objects transferred using samples A2 to A7 and C3 to C7 were within ±5% of the design value. These results confirmed that the accuracy of the transferred object's shape can be improved by providing a flat bottom surface on the blazed shape and ensuring that the ratio of the area of ​​the flat bottom surface to the unit shape is 10% or more. Among the transferred objects whose dimensions were confirmed to be more than 5% of the design value, the transferred object to which the pattern of sample X1 was transferred had particularly large dimensional variation from the design value compared to the other samples. [Explanation of symbols]

[0122] θ1~θ6…Inclination angle H1~H6...Height P1~P6...Pitch U1~U3...Unit shape W1~W8…width 10, 30, 50...Imprint mold 10P~60P...Pattern 10S~60S...Patterned surface 11,41,51,62…Bottom flat surface 12,22,32,42,53,63,201,301…Slope 13,23,33,43,54,64,202,302…Step surface 15, 35, 55, 56...Etching stopper layer 20, 40, 60... Diffractive optical elements 21,31,52,61…Top flat surface

Claims

1. A pattern surface on which a pattern is formed, the pattern has a plurality of unit shapes arranged in a first direction, The unit shape has a concave-convex shape extending in a second direction intersecting the first direction, the concave-convex shape includes a bottom flat surface located at the bottom of the concave-convex shape, and a convex portion including an inclined surface and a stepped surface; When viewed from a viewpoint opposite to a plane including the first direction and the second direction, the ratio of the area of ​​the bottom flat surface to the entire area of ​​the unit shape is 10% or more and 50% or less. Imprint mold.

2. A pattern surface on which a pattern is formed, the pattern has a plurality of unit shapes arranged in a first direction, The unit shape has a concave-convex shape extending in a second direction intersecting the first direction, The uneven shape has a convex portion including a flat top surface, an inclined surface, and a stepped surface, the top flat surface is located at the top of the uneven shape, When viewed from a viewpoint opposite to a plane including the first direction and the second direction, the ratio of the area of ​​the top flat surface to the entire area of ​​the unit shape is 10% or more and 50% or less. Imprint mold.

3. A pattern surface on which a pattern is formed, the pattern has a plurality of unit shapes arranged in a first direction, The unit shape has a concave-convex shape extending in a second direction intersecting the first direction, the concave-convex shape includes a bottom flat surface located at the bottom of the concave-convex shape, and a convex portion including a top flat surface, an inclined surface, and a stepped surface; the top flat surface is located at the top of the uneven shape, When viewed from a top view point opposite to a plane including the first direction and the second direction, the ratio of the area of ​​the bottom flat surface to the entire area of ​​the unit shape is 10% or more, the ratio of the area of ​​the top flat surface to the entire area of ​​the unit shape is 10% or more, and the ratio of the sum of the area of ​​the bottom flat surface and the area of ​​the top flat surface to the entire area of ​​the unit shape is 50% or less. Imprint mold.

4. The material constituting the pattern surface includes at least one of silicon, silicon compounds, diamond, metals, metal compounds, ceramics, and resins. The imprint mold according to claim 1 .

5. the pattern surface includes a first portion made of a first material and a second portion made of a second material that is less susceptible to etching than the first material under specific etching conditions; The second portion includes the bottom flat surface. The imprint mold according to claim 1 or 3.

6. the pattern surface includes a first portion made of a first material and a second portion made of a second material that is less susceptible to etching than the first material under specific etching conditions; The second portion includes the top flat surface. The imprint mold according to claim 2 or 3.

7. the pattern surface includes a first portion made of a first material and a second portion made of a second material that is less susceptible to etching than the first material under specific etching conditions; The second portion includes the bottom planar surface and the top planar surface. The imprint mold of claim 3 .

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