Manufacturing method of an imprint mold, imprint mold, mold blank, and manufacturing method of an optical element

Abstract

The present invention provides an imprint mold (1) and related technologies. The imprint mold (1) has a plurality of concave portions (1c) constituting a given mold pattern. Among them, a laminate including a plurality of mold base layers (4) and etching stop layers (3) interposed between the mold base layers (4) is provided on a substrate (2). The laminate has a plurality of concave portions (1c) with different depths. The mold base layer (4) and the etching stop layer (3) are formed of materials having etching selectivity with respect to each other. Each of the plurality of concave portions (1c) has a bottom surface where the etching stop layer (3) is exposed.

Description

Technical Field

[0001] The present invention relates to an imprint mold for forming a fine pattern such as an optical element by imprinting. In particular, the present invention relates to an imprint mold suitable for transferring a fine three-dimensional transfer pattern to a material such as resin by optical imprinting, a method for manufacturing the same, and a mold blank. Background Art

[0002] The imprinting technique is a method that is highly anticipated in various fields such as semiconductors, biology, and medicine as a superfine processing technique.

[0003] Patent Document 1 discloses a molding die for manufacturing a blazed grating, which has a substrate and a plurality of double-layer films laminated on the surface of the substrate. Each double-layer film is composed of a first thin film and a second thin film. The first thin film has high reactivity to one of two etching gases and low reactivity to the other etching gas, and the second thin film has low reactivity to the one etching gas and high reactivity to the other etching gas.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Patent Laid-Open No. 6-258510 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] For example, a structure formed by forming a desired three-dimensional pattern on the surface of a substrate such as glass, metal, or Si can be used as an optical element such as a diffraction grating. When forming a fine pattern on these products, an imprinting die method using a mold (also referred to as a template, stamper, metal mold, casting mold, or master) having the above pattern is sometimes employed. Hereinafter, the imprinting die method will also be simply referred to as the imprinting method or imprinting.

[0009] In the imprinting method, for example, while pressing a three-dimensional pattern of a mold against a layer formed of a photocurable or thermosetting resin coated on a substrate, the resin is irradiated with light (optical imprinting) or heated (thermal imprinting) to cure the resin. Thereby, the shape of the mold is transferred to the resin layer to form a pattern.

[0010] As described above, the imprinting method is a method of directly pressing a mold against a resin or the like coated on a substrate or the like to transfer a pattern. Therefore, the size and depth of the pattern possessed by the mold directly affect the shape of the produced fine pattern.

[0011] As the demand for higher precision optical elements continues to increase, the precision of the imprint mold is expected to be higher. In particular, the mold pattern of the imprint mold (hereinafter also referred to as the transfer pattern) is transferred at the same magnification, which is different from the photomask for semiconductors using reduced exposure. Therefore, the pattern accuracy required for the imprint mold will be directly reflected in the accuracy required for the pattern of the optical element as the final product. Therefore, it is expected that the fine transfer pattern of the imprint mold is formed with very high precision. However, it is not easy to precisely form a three-dimensional shape with a transfer pattern with a width and depth of less than 1μm.

[0012] As described above, Patent Document 1 describes a molding die for producing a diffraction grating for cheaply producing a blazed grating by a replication method. The molding die has a stepped mold shape formed by a bottom surface and two steps, so it is considered that the stepped shape forms a portion corresponding to the inclined surface of the blazed grating in the desired replica. Among them, Patent Document 1 describes that the depth accuracy and uniformity of the concave bottom surface and the step used for transferring the diffraction grating can be improved.

[0013] On the other hand, in a mold having a transfer pattern with a plurality of recesses (digging portions), not only the depth accuracy but also the position accuracy of each recess is required to be maintained at a high level. That is, in order to improve the performance of the final product, the inventors of the present invention focus on the importance of improving the accuracy of the three-dimensional shape of the mold.

[0014] An object of the present invention is to provide an imprint mold having a plurality of recessed portions (debossed portions) and having a high formation accuracy for a three-dimensional transfer pattern, and a method for manufacturing the same.

[0015] Solutions to the problem

[0016] A first aspect of the present invention is a method for manufacturing an imprint mold having a plurality of recessed portions forming a given mold pattern.

[0017] The manufacturing method comprises:

[0018] A step of preparing a mold blank, wherein the mold blank has a stacked body including a plurality of mold base material layers and an etching stop layer interposed between the mold base material layers formed on a substrate, and a hard mask layer formed on the stacked body;

[0019] A hard mask patterning step, etching the hard mask layer based on the design of the mold pattern to form a hard mask pattern;

[0020] A recess forming step of performing, N times (where N is an integer of 2 or more), a die digging etching for etching the die base material layer or the etching stop layer and the die base material layer, using a given resist pattern and the hard mask pattern formed on the laminate provided with the hard mask pattern as masks, thereby forming the plurality of recesses having different depths; and

[0021] A step of removing the hard mask pattern,

[0022] The die base material layer and the etching stop layer are formed of materials having etching selectivity with respect to each other,

[0023] Each of the plurality of formed recesses has a bottom surface where the etching stop layer is exposed.

[0024] A second aspect of the present invention is in the method for manufacturing an imprint mold according to the first aspect,

[0025] The number of times N of the die digging etching is set to 2 ≤ N ≤ 5.

[0026] A third aspect of the present invention is in the method for manufacturing an imprint mold according to any one of the first or second aspects,

[0027] The laminate includes the plurality of die base material layers having different thicknesses.

[0028] A fourth aspect of the present invention is in the method for manufacturing an imprint mold according to any one of the first to third aspects,

[0029] Each of the plurality of recesses having different depths is a recess vertically dug independently from the die surface.

[0030] A fifth aspect of the present invention is in the method for manufacturing an imprint mold according to any one of the first to fourth aspects,

[0031] An etching stop layer is disposed between the die base material layer closest to the substrate and the substrate.

[0032] A sixth aspect of the present invention is an imprint mold having a plurality of recesses constituting a given die pattern,

[0033] wherein the imprint mold has a laminate including a plurality of die base material layers and an etching stop layer interposed between the die base material layers on a substrate,

[0034] The laminate has the plurality of recesses having different depths,

[0035] The die base material layer and the etching stop layer are formed of materials having etching selectivity with respect to each other,

[0036] Each of the plurality of concave portions has a bottom surface formed by exposing the etching stop layer.

[0037] A seventh aspect of the present invention is the imprinting mold according to the sixth aspect,

[0038] Each of the plurality of concave portions having different depths is a concave portion vertically dug independently from the mold surface.

[0039] An eighth aspect of the present invention is the imprinting mold according to the sixth or seventh aspect,

[0040] The laminate includes the plurality of mold substrate layers having different thicknesses.

[0041] A ninth aspect of the present invention is the imprinting mold according to any one of the sixth to eighth aspects,

[0042] When the mold substrate layer and the etching stop layer are formed to have the same thickness, the transmittance of ultraviolet light is 1:0.8 to 1:0.95.

[0043] A tenth aspect of the present invention is the imprinting mold according to any one of the sixth to ninth aspects,

[0044] The thickness of the mold substrate layer is 3 times or more and 25 times or less with respect to the thickness of the etching stop layer.

[0045] An eleventh aspect of the present invention is the imprinting mold according to any one of the sixth to tenth aspects,

[0046] The plurality of concave portions are formed by etching and removing mold substrate layers having different numbers and each in the range of 2 or more and 5 or less layers.

[0047] A twelfth aspect of the present invention is the imprinting mold according to any one of the sixth to eleventh aspects,

[0048] An etching stop layer is disposed between the mold substrate layer closest to the substrate and the substrate.

[0049] A thirteenth aspect of the present invention is the imprinting mold according to any one of the sixth to twelfth aspects applied to photoimprinting using ultraviolet light.

[0050] A fourteenth aspect of the present invention is a mold blank for manufacturing an imprinting mold having a mold pattern including a plurality of concave portions with different depths,

[0051] wherein the mold blank is used to obtain the imprinting mold having concave portions with depths of D1 and D2 (where D1≠D2) from the mold surface,

[0052] In this mold blank, a plurality of mold base material layers are laminated on the substrate surface, and a hard mask layer is further formed on the surface side thereof.

[0053] Moreover, an etching stop layer with a thickness W formed of a material having etching selectivity with respect to the above-mentioned mold base material layers is interposed between each of the plurality of mold base material layers.

[0054] When the thickness of the mold base material layer farthest from the substrate in the above lamination is set as K1 and the thickness of the second mold base material layer from the top is set as K2, the thicknesses of the plurality of mold base material layers are set such that:

[0055] K1 = D1,

[0056] K2 = D2 - (D1 + W).

[0057] A 15th aspect of the present invention relates to a mold blank for obtaining an imprint mold having recesses with depths from the mold surface of D1, D2, ··· Dn (where n is an integer of 3 or more, and D1, D2 ··· Dn are different from each other).

[0058] In this mold blank, a plurality of mold base material layers are laminated on the substrate surface, and a hard mask layer is further formed on the surface side thereof.

[0059] Moreover, an etching stop layer with a thickness W formed of a material having etching selectivity with respect to the above-mentioned mold base material layers is interposed between each of the plurality of mold base material layers.

[0060] When the thickness of the mold base material layer farthest from the substrate in the above lamination is set as K1, the thickness of the second mold base material layer from the top is set as K2, and the thickness of the nth mold base material layer from the top is set as Kn, the thicknesses of the plurality of mold base material layers are set such that:

[0061] K1 = D1,

[0062] K2 = D2 - (D1 + W), :

[0064] Kn = Dn - (D1 + D2 + ··· (n - 1)W).

[0065] A 16th aspect of the present invention is the mold blank according to the 14th or 15th aspect,

[0066] wherein the above-mentioned mold base material layer contains silicon and oxygen, and the above-mentioned etching stop layer contains silicon, aluminum and oxygen.

[0067] A 17th aspect of the present invention is the mold blank according to any one of the 14th to 16th aspects,

[0068] The refractive index n of the above-described etch stop layer with respect to light having a wavelength of 365 nm is 2.2 or less.

[0069] The 18th aspect of the present invention is the mold blank according to any one of the 14th to 17th aspects,

[0070] The extinction coefficient k of the above-described etch stop layer with respect to light having a wavelength of 365 nm is 0.01 or less.

[0071] The 19th aspect of the present invention is a method for manufacturing an optical element, the method including:

[0072] a step of preparing an imprint mold according to any one of the 6th to 13th aspects; and

[0073] a step of directly or indirectly pressing the mold surface of the above-described imprint mold against a transfer body including a resin material to transfer the above-described mold pattern to the transfer body.

[0074] Effects of the Invention

[0075] According to the present invention, it is possible to provide an imprint mold having high formation accuracy of a transfer pattern in a three-dimensional shape with a plurality of concave portions and a method for manufacturing the same. BRIEF DESCRIPTION OF THE DRAWINGS

[0076] Figure 1 is a cross-sectional schematic view showing an example of the structure of the imprint mold of the present embodiment.

[0077] Figure 2A is a cross-sectional schematic view showing an example of the method for manufacturing the imprint mold of the present embodiment (Part 1).

[0078] Figure 2B is a cross-sectional schematic view showing an example of the method for manufacturing the imprint mold of the present embodiment (Part 2).

[0079] Figure 3 is a cross-sectional schematic view showing an outline of pattern transfer by photoimprint using the imprint mold of the present embodiment.

[0080] REFERENCE SIGNS

[0081] 1 (Imprint) Mold

[0082] 1c Concave Portion

[0083] 1s Mold Surface

[0084] 2 Substrate

[0085] 3 Etch Stop Layer

[0086] 4 Mold Substrate Layer

[0087] 5 Hard Mask Layer

[0088] 5p hard mask pattern

[0089] 61 First resist film

[0090] 61p First resist pattern

[0091] 62 Second resist film

[0092] 62p Second resist pattern

[0093] 63 Third resist film

[0094] 63p Third resist pattern

[0095] 7 Photo-curable resin

[0096] 8 Working replica

[0097] 10 Mold blank Detailed implementation manners

[0098] The implementation manners of the present invention will be described with reference to the accompanying drawings. The accompanying drawings are examples for explanation and are not limited thereto. In addition, the accompanying drawings are schematic, and the ratio of the dimensions of each part, the arrangement order of each part, and the number of each part are not limited to be consistent with the actual situation.

[0099] <Imprint mold 1>

[0100] The imprint mold 1 of the present implementation manner can be suitably used as a mold used in the imprint method. Hereinafter, the imprint mold 1 will also be simply referred to as mold 1. Specifically, the mold pattern of the mold 1 of the present implementation manner can be transferred to a transfer body such as resin, and the obtained formation such as an optical element (or the formation obtained by further transferring the formation as a replica to a separately prepared material) can be used for various purposes.

[0101] For example, the mold 1 of the present implementation manner can be advantageously used as a mold for semiconductors, MEMS components, bio-related components, medical-related components, and optical elements (such as diffraction gratings). As an optical element, it can be used for display device applications, etc.

[0102] Figure 1 It is a cross-sectional schematic view showing an example of the structure of the mold 1 of the present implementation manner.

[0103] As Figure 1As shown, the mold 1 of the present embodiment has a laminate on the substrate 2, and the laminate is configured as follows: having a plurality of mold base layers 4, and an etching stop layer 3 is interposed between the plurality of mold base layers 4. In addition, in the present embodiment, an etching stop layer 3 is also provided between the lowermost mold base layer 4 (the layer closest to the substrate 2) and the substrate 2.

[0104] It should be noted that in this specification, the surface of the substrate 2 on the side where the mold pattern is formed in the imprint mold 1 having the substrate 2 is defined as the substrate main surface (or simply referred to as the substrate surface), with the main surface side being upward and the back side of the main surface being downward.

[0105] The mold 1 has a plurality of concave portions 1c for forming a given mold pattern.

[0106] The mold 1 of the present embodiment includes a mold pattern having concave portions 1c (digging portions) formed by vertically digging independently from each mold surface 1s and having N different depths (here, 3 depths). The respective depths are D1, D2, and D3 from the mold surface 1s. Figure 1 The case where D1 < D2 < D3 is exemplified. In this way, the mold 1 of the present embodiment has a plurality of concave portions 1c with different depths. Of course, for any one depth, a plurality of concave portions 1c with the same depth can be included (in Figure 1 there are 2 concave portions 1c for each depth, a total of 6). The three-dimensional shape of such a mold pattern is transferred to a transfer body formed of a resin material or the like, and a reversed pattern is formed on the transfer body. That is, after reversing the three-dimensional shape to be formed on the transfer body, it is the mold pattern of the mold 1 of the present embodiment.

[0107] The depth of the concave portion 1c (digging portion) can be determined according to the use. For example, if it is an optical element, it can be set to 10 to 500 nm according to the light used. More specifically, about 10 to 300 nm can be exemplified. In addition, when the depth of the concave portion 1c is in such a range, the effects of the invention are significant. This is because the fine depth of the concave portion 1c in the fine pattern can be precisely controlled by the manufacturing method described later.

[0108] The mold pattern of the mold 1 of the present embodiment can be designed according to the use. For example, according to the present invention, it can have concave portions 1c with N depths (for example, 2 ≤ N ≤ 5).

[0109] The depth control of the concave portion 1c can be accurately performed by the design of the mold blank 10 prepared to obtain the mold 1 of the present embodiment. This will be further described later.

[0110] The mold surface 1s is the uppermost plane of the mold 1 (the plane located farthest from the substrate 2). When transferring a mold pattern to a transfer body formed of resin or the like using the mold 1 of the present embodiment, the mold surface 1s directly or indirectly contacts and presses against the pattern formation surface of the transfer body. As a case of indirect pressing, there is a case where a functional layer such as a release material or an additional layer is formed on or interposed between the surfaces of the mold surface 1s.

[0111] In the present embodiment, the recesses 1c are each independently dug from below the mold surface 1s. Therefore, with respect to the shape of the mold pattern as viewed from the mold surface 1s side (top view of the mold pattern), the respective recesses 1c are sandwiched by the mold surface 1s or arranged so as to be surrounded. This is advantageous when accurately adjusting the angle and positioning during the transfer of the mold pattern to the transfer body.

[0112] In addition, in such a designed mold pattern, the effects of the present invention that can precisely control the width, position, and depth of the recesses 1c are significantly produced, and by applying this effect, a wide range of applications to products such as optical elements can be carried out.

[0113] For example, the mold pattern (top view) may be a linear pattern in which the mold surface 1s remaining in a linear shape is regularly arranged via linear recesses 1c, or may be a hole arrangement pattern in which a plurality of recesses 1c having a given diameter are formed in the mold surface 1s, and in addition, other designs are also possible.

[0114] When the mold pattern is the above-described linear arrangement pattern, the pitch (period) thereof may be in the range of 50 to 1000 nm, or more specifically, may be 70 to 500 nm. Of course, for any dimension of the width (also referred to as CD) and pitch of the pattern of each recess 1c (the dug-in portion), in addition to the case where patterns of the same size are repeatedly arranged, it may also be a pattern in which the size changes depending on the position.

[0115] The same applies to the case where the mold pattern is a hole pattern. The shape of each hole is not particularly limited, and designs such as a square, a rectangle, or a circle are possible. The diameter thereof (the diameter of the inscribed circle of the hole shape) may be set to 50 to 1000 nm, and further may be set to the range of 70 to 500 nm.

[0116] In addition, the aspect ratio of the pattern of the recesses 1c (that is, (the depth of the recesses 1c) / (the bottom width of the recesses 1c)) may be set to, for example, 0.1 to 5.

[0117] The mold 1 of the present embodiment does not have a stepped portion in each recess 1c. That is, each recess 1c has a single depth. The side walls of each recess 1c are as Figure 1As shown, the exposed structure is formed by alternately laminating the mold base material layer 4 and the etch stop layer 3. As will be described later, each recess 1c is formed by patterning the mold base material layer 4 and the etch stop layer 3 using different etchants. Therefore, it is difficult to avoid generating small steps between the mold base material layer 4 and the etch stop layer 3 on the sidewalls. However, such steps are like the part of the etch stop layer 3 on the sidewall slightly protruding relative to the part of the mold base material layer 4 on the sidewall, or the part of the etch stop layer 3 on the sidewall slightly recessed relative to the part of the mold base material layer 4 on the sidewall. Such steps on the sidewalls are all on the order of several nm and are generally not regarded as stepped steps.

[0118] As will be described later, the etch stop layer 3 is exposed on the bottom surface of each recess 1c. That is, the formation of each recess 1c starts from the mold surface 1s and is dug down to a depth up to the surface position of any one of the multiple etch stop layers 3. Among them, the etch stop layer 3 remains without being removed. Each recess 1c is composed of a sidewall and a bottom surface. The sidewall is formed by the mold base material layer 4 and the etch stop layer 3, and the bottom surface is formed by the etch stop layer 3.

[0119] "The multiple recesses 1c constituting the mold pattern" means that there are multiple portions recessed from the mold surface 1s. The number of recesses 1c is not particularly limited. For example, it can be 100 to 2000 parts in a rectangular area with a side length of 100 mm. As described above, the depths of the multiple recesses 1c can be different from each other, but some of the recesses 1c can have the same depth.

[0120] Regarding the CD of each recess 1c (the dug-in part), it can also be determined according to the use. For example, a dug-in part with a width of 50 to 1000 nm, preferably about 70 to 500 nm, can be vertically dug down to form. The shape of the sidewall of each recess 1c is preferably vertical. Specifically, the sidewall of the recess 1c is preferably within the range of ±10 degrees (within the range of 80 degrees or more and 100 degrees or less relative to the bottom surface), more preferably within the range of ±5 degrees (within the range of 85 degrees or more and 95 degrees or less relative to the bottom surface) with respect to the imaginary plane perpendicular to its bottom surface.

[0121] In other words, it is possible to provide such a mold that precisely controls the fine depth / CD as the mold 1 of the present embodiment.

[0122] (Substrate 2)

[0123] The substrate 2 supports the above-described laminate formed with the dug-in pattern.

[0124] The material of the substrate 2 is not particularly limited. However, it is preferably translucent. In this case, it is advantageous for use in photolithography. For example, when irradiating the resin while pressing the mold surface 1s of the above-mentioned mold 1 against the transfer body having a photocurable resin layer formed on the substrate 2, the light can be irradiated from the back side of the substrate 2. That is, the above-mentioned "translucency" means that light is transmitted to such an extent that the photocurable resin can be cured by the light irradiated through the substrate 2. The property of having translucency is also referred to as "transparent".

[0125] It should be noted that in photolithography, it is preferable to cure the resin using ultraviolet rays. For example, the transmittance of ultraviolet rays in the thickness direction of the substrate 2 is preferably 70% or more, more preferably 90% or more. The ultraviolet rays here are light in the wavelength range of 10 to 400 nm, preferably 200 to 380 nm. For example, the transmittance of the above-mentioned ultraviolet rays can be set with 365 nm as the reference wavelength. The same setting is adopted for the ultraviolet rays cited below.

[0126] The shape of the substrate 2 is not particularly limited. For example, it can be disk-shaped or rectangular plate-shaped. As the size of the substrate 2, for example, in the case of the imprint mold 1 for optical elements, the length of one side can be set to 10 to 300 mm. The thickness of the substrate 2 is not particularly limited. Considering the transmittance of the ultraviolet rays cited above, for example, in the case of the imprint mold 1 for optical elements, it can be about 5 to 15 mm.

[0127] As specific materials constituting the substrate 2, examples include: materials containing silicon and oxygen (quartz glass, aluminosilicate glass, soda-lime glass, etc.), materials containing silicon, oxygen, and titanium (SiO2-TiO2 low-thermal-expansion glass, etc.), and materials containing aluminum and oxygen (sapphire, etc.). In the present embodiment, an example of using a quartz substrate as the substrate 2 will be described. The quartz substrate can achieve transparency to the irradiation light in photolithography and can be processed to be flat and smooth. Therefore, for example, it can be used as an imprint mold for high-precision transfer.

[0128] (Laminate)

[0129] According to Figure 1 It can be understood that the mold 1 of the present embodiment has a plurality of mold base layers 4 and an etching stop layer 3 interposed therebetween. That is, the mold of the present embodiment has a laminate including a plurality of mold layers with different thicknesses.

[0130] The mold base material layer 4 is the main base material constituting the mold 1. The mold base material layer 4 is preferably formed of a material transparent to the irradiation light for photolithography. The mold base material layer 4 can be, for example, a silicon-containing material such as silica. In addition, the mold base material layer 4 more preferably uses a material containing one or more elements selected from oxygen and nitrogen in silicon, and further preferably uses a material containing silicon and oxygen. Specifically, in addition to silicon dioxide (SiO2), it can also contain Si3N4, SiON, etc. On the other hand, a hafnium-containing material such as hafnium oxide can be selected.

[0131] The refractive index n of the etching stop layer 3 for ultraviolet light with a reference wavelength (wavelength 365 nm) is preferably 1.7 or less, more preferably 1.6 or less, and further preferably 1.5 or less. The extinction coefficient k of the etching stop layer 3 for ultraviolet light with a reference wavelength (wavelength 365 nm) is preferably 0.003 or less, more preferably 0.001 or less. It should be noted that the materials of the plurality of mold base material layers 4 do not necessarily have to be the same, and one or more materials having the following characteristics can be used.

[0132] The material of each mold base material layer 4 is preferably a material transparent to the light (the above-mentioned ultraviolet light) used. For example, the transmittance of ultraviolet light in the thickness direction of each mold base material layer 4 is preferably 70% or more, more preferably 90% or more.

[0133] The thickness (layer thickness) of each mold base material layer 4 can be determined based on the shape of the mold pattern to be obtained. That is, it can be determined according to the set depth of each concave portion 1c (each dug-in portion) of the mold pattern. For example, the thickness of the mold base material layer 4 can be set in the range of 10 to 500 nm, or can also be set in the range of 30 to 200 nm. When in this range, stable film-forming conditions for obtaining a uniform film thickness can be selected.

[0134] Figures 1 to 3 The case where the thicknesses of the respective mold base material layers 4 are substantially the same is shown, but the mold 1 of the present invention is not limited thereto, and can also include mutually different thicknesses. When forming the mold pattern of the present embodiment, by determining up to which depth of the mold base material layer 4 (or the etching stop layer 3 and the mold base material layer 4) that is removed (dug in) by etching, a concave portion 1c having a desired depth can be obtained. In other words, the thicknesses and lamination orders of the respective mold base material layers 4 are determined in advance according to the types of depths of the concave portions 1c to be obtained. At this time, the thickness of the etching stop layer 3 interposed between the mold base material layers 4 is considered. This will be further described later.

[0135] In addition, as described later in <Manufacturing Method of Imprinting Die 1>, an etching stop layer 3 is interposed between the respective die substrate layers 4. When etching away the die substrate layer 4, the etching depth is independently controlled for each die substrate layer 4, so as to accurately obtain the depth of the recess 1c that conforms to the design.

[0136] By disposing the etching stop layer 3 as described above, the depth of the recess 1c (etched-in portion) can be easily set according to the sum of the layer thicknesses of the die substrate layer 4 preset to a given thickness in the predetermined portion etched in from the die surface 1s and the etching stop layer 3 also preset to a given thickness.

[0137] The above-described etching stop layer 3 has the function of accurately stopping the etching when forming each etched-in portion. The over-etching time can be appropriately set, and the shape of the bottom of the recess 1c can be formed in accordance with the design.

[0138] In the die 1 of the present embodiment, the plurality of recesses 1c each have a bottom surface where the etching stop layer 3 is exposed.

[0139] In the present embodiment, since the etching stop layer 3 is exposed on the bottom surface of any recess 1c, it can be considered that it can also be used for the inspection of die products (optical inspection / guarantee of the depth of the recess 1c).

[0140] The number of stacked die substrate layers 4 in the laminate can be determined according to the use of the die 1 and is not particularly limited. For example, it can be set to 2 to 5 layers according to the types of depths of the recesses 1c to be formed, and more preferably 3 to 4 layers. That is, at least any one of the recesses 1c in the recess 1c is preferably formed by etching away N layers (where 2 ≤ N ≤ 5, preferably 3 ≤ N ≤ 4) of the die substrate layer 4 (including the etching stop layer 3 interposed between the die substrate layers 4 to be removed).

[0141] At this time, in the case of using optical imprinting, the transfer body is uniformly cured without being affected by the reflection or scattering of light occurring at the interface between the die substrate layer 4 and the etching stop layer 3.

[0142] The etching stop layer 3 is formed of a material having etching resistance with respect to the etchant (e.g., etching gas) of the die substrate layer 4. In addition, the die substrate layer 4 has etching resistance with respect to the etchant of the etching stop layer 3. The die substrate layer 4 and the etching stop layer 3 are formed of materials having etching selectivity with respect to each other.

[0143] As a specific example of the material of the etching stop layer 3, the following can be cited: a material containing silicon dioxide (SiO2) and aluminum (Al) (for example, aluminum oxide (Al2O3)), a material containing hafnium (Hf) (for example, hafnium oxide (HfO2)), a material containing chromium (Cr) (for example, chromium oxide (CrO), chromium nitride (CrN), chromium oxynitride (CrON), at least any one of the materials containing carbon in these materials), etc.

[0144] It should be noted that since the material of the etching stop layer 3 is a material having etching selectivity with respect to the material of the mold substrate layer 4, when a Si-containing material such as SiO2 is used for the mold substrate layer 4, it is preferable to use a material containing aluminum or chromium for the etching stop layer 3. The etching stop layer 3 is more preferably formed of a material containing silicon, aluminum, and oxygen. Such an etching stop layer 3 has high etching selectivity with respect to the mold substrate layer 4, has high cleaning resistance, and has high light transmittance for ultraviolet rays used in photolithography. In addition, when both the substrate 2 and the mold substrate layer 4 are formed of a Si-containing material, the adhesion between the substrate 2 and the etching stop layer 3 and the adhesion between the mold substrate layer 4 and the etching stop layer 3 are both improved.

[0145] The refractive index n of the etching stop layer 3 for light (ultraviolet rays) with a reference wavelength (wavelength 365 nm) is preferably 2.2 or less, more preferably 1.9 or less, and further preferably 1.6 or less. The extinction coefficient k of the etching stop layer 3 for light (ultraviolet rays) with a reference wavelength (wavelength 365 nm) is preferably 0.01 or less, more preferably 0.005 or less.

[0146] The etching selectivity of the etching stop layer 3 with respect to the mold substrate layer 4 in this specification can be defined by the formula (etching rate of the etching stop layer 3) / (etching rate of the mold substrate layer 4) when the same etching agent is used. The etching selectivity defined by this formula is also called the etching selectivity ratio.

[0147] "High etching selectivity between the mold substrate layer 4 and the etching stop layer 3" means that when a given etching agent is used, the value of the above-defined formula is significantly large or significantly close to zero. For example, the etching selectivity ratio of the etching stop layer 3 with respect to the mold substrate layer 4 during etching, that is, (etching rate of the etching stop layer 3) / (etching rate of the mold substrate layer 4) is preferably 1 / 2 to 1 / 1000.

[0148] As an example, it can be cited that the mold substrate layer 4 is formed of SiO2, the etching agent for the mold substrate layer 4 is carbon tetrafluoride (CF4), the etching stop layer 3 is formed of a material containing Al2O3 and SiO2, and the etching agent for the etching stop layer 3 is carbon tetrachloride (CCl4).

[0149] In the above example, when the etchant CF4 is used, the etching rate of the etch stop layer 3 containing Al2O3 is very low. Therefore, the value of (etching rate of etch stop layer 3) / (etching rate of mold substrate layer 4) approaches zero. On the other hand, when the etchant CCl4 is used, the etching rate of the mold substrate layer 4 containing SiO2 is very low. Therefore, the value of (etching rate of etch stop layer 3) / (etching rate of mold substrate layer 4) is 10 or more.

[0150] The plurality of etch stop layers 3 can be set to have the same thickness as each other, or can include cases where the thicknesses are different from each other.

[0151] It should be noted that the material of each etch stop layer 3 can be one kind or a plurality of kinds. Considering the transmittance of ultraviolet rays and the stability of etching conditions described later, it is preferable that all the etch stop layers 3 are formed of the same material, and in addition, their thicknesses are also preferably the same.

[0152] In order to adopt the mold 1 of the present embodiment in photolithography, it is preferable that the material of each etch stop layer 3 is a material with high transparency to light (especially ultraviolet light) used in photolithography. For example, the transmittance of ultraviolet rays in the thickness direction of each etch stop layer 3 is preferably 70% or more, more preferably 90% or more.

[0153] In addition, regarding the transmittance of the materials used for the mold substrate layer 4 and the etch stop layer 3 respectively, when comparing specimens with the same thickness, it is preferable that T1 > T2 (where T1: specimen of the material of the mold substrate layer 4, T2: specimen of the etch stop material), and the relative ratio can be set to T1:T2 = 1:0.8 to 1:0.95.

[0154] The thickness of the etch stop layer 3 is preferably a smaller value within the range where the function of stopping etching can be sufficiently exerted. When it is too large, not only does the etching time increase, but also a problem of decreased light transmittance of the mold 1 occurs. The thickness of the etch stop layer 3 can be set to, for example, 3 to 30 nm, preferably 5 to 20 nm, and more preferably 8 to 20 nm.

[0155] The thickness of the above-mentioned mold substrate layer 4 is preferably 3 to 25 times, more preferably 3 to 20 times, the thickness of the above-mentioned etch stop layer 3.

[0156] It should be noted that the raw materials of the mold substrate layer 4 and the material of the etch stop layer 3 are selected to be materials with sufficient transparency to the irradiation light used in photolithography. Among them, the materials listed above can be preferably used. In particular, since the mold substrate layer 4 has a relatively larger thickness compared to the etch stop layer 3, a material with higher transparency is desired.

[0157] On the other hand, the following situation may occur: the etching rate Rs at which the etching stop layer 3 is etched by the etchant of the mold substrate layer 4 is less than the etching rate Rb at which the mold substrate layer 4 is etched by the etchant of the etching stop layer 3, that is, Rb > Rs. That is, it has been found that the following situation may occur: the damage suffered by the etching stop layer 3 from the etchant of the mold substrate layer 4 is relatively lower than the damage suffered by the mold substrate layer 4 from the etchant of the etching stop layer 3. Therefore, it has been ascertained that leaving the bottom surface of the recess 1c with the etching stop layer 3 remaining when controlling the depth of the recess 1c in the mold pattern is advantageous for the control of the precise digging amount of ±5 nm, and further ±2 nm with respect to the target value.

[0158] (Other layers)

[0159] The mold 1 of the present embodiment may also have a bottom coating for improving adhesiveness and impact resistance, a conductive layer for suppressing charging during electron beam lithography, etc. as needed. When each mold substrate layer 4, each etching stop layer 3, and / or the hard mask layer 5 described later has conductivity, an effect of suppressing charging can sometimes be obtained.

[0160] <Method for manufacturing the imprint mold 1>

[0161] According to the present embodiment, the above-described imprint mold 1 can be manufactured by the following method. It should be noted that the content not specifically described below is the same as that described in <Imprint mold 1>.

[0162] The method for manufacturing the imprint mold 1 of the present embodiment is as described below.

[0163] (Mold blank 10)

[0164] The mold 1 manufactured in the present embodiment is an imprint mold 1 having a mold pattern including a plurality of recesses 1c with different depths, and as Figure 1 exemplified in, is a mold 1 having recesses 1c with depths of D1 and D2 (where D1 ≠ D2) from the mold surface 1s at least.

[0165] The above mold is manufactured using a mold blank 10 prepared in advance based on the design of the desired mold 1.

[0166] For the mold blank 10, the number of stacked layers, the stacking order, and the thickness of each of the mold base layer 4 and the etch stop layer 3 are pre-adjusted based on the desired dug-in depth of the mold 1. Using the mold blank 10, recesses 1c are formed at different positions with different N depths (recess forming process). In other words, it is formed by performing at least N times (i.e., at N positions) of mold dug-in etching with different desired depths. Of course, recesses 1c with the same or different depths can also be additionally formed.

[0167] It should be noted that the mold base layer 4 and the etch stop layer 3 can be formed by a known film forming method such as sputtering.

[0168] The outline of the cross-section of the mold blank 10 used in this embodiment is as Figure 2A (a) shows.

[0169] In the mold blank 10 of this embodiment, a plurality of mold base layers 4 are stacked on the surface of the substrate 2, a hard mask layer 5 is formed on the surface side thereof, and a resist layer is further provided thereon.

[0170] An etch stop layer 3 with a thickness W is interposed between each of the plurality of mold base layers 4. Here, all the etch stop layers 3 have the same thickness.

[0171] When the thickness of the uppermost mold base layer 4 in the above stack is set as K1 and the thickness of the second mold base layer 4 from the top is set as K2,

[0172] K1 = D1,

[0173] K2 = D2 - (D1 + W).

[0174] The above mold base layer 4 and the above etch stop layer 3 are formed of materials having etching selectivity with respect to each other.

[0175] The above expressions of K1 and K2 are defined expressions for two recesses 1c starting from the shallower one among the recesses 1c to be formed in the mold blank 10.

[0176] In addition, when further forming a recess 1c with a depth D3 different from both D1 and D2, the mold blank 10 further has a stack of a mold base layer 4 with a thickness K3 (refer to Fig. 2(A)),

[0177] K3 = D3 - (D1 + D2 + 2W).

[0178] That is, in the case of the recess 1c having n kinds of depths, the lamination that the mold blank 10 should have, K1, K2, K3, ··· Kn (with an etching stop layer 3 intervening between them) has the following relationship.

[0179] Kn = Dn - (D1 + D2 + ··· (n - 1)W)

[0180] That is to say, considering the mold 1 that further has deeper recesses 1c in addition to the above two recesses 1c,

[0181] In the mold blank 10 of the above imprint mold 1 for obtaining recesses 1c having depths D1, D2, ··· Dn (where n is an integer of 3 or more and D1, D2 ··· Dn are different from each other) starting from the mold surface 1s,

[0182] A plurality of mold base layers 4 are laminated on the surface of the substrate 2, and a hard mask layer 5 is further formed on the surface side thereof.

[0183] And, an etching stop layer 3 with a thickness W intervenes between each of the plurality of mold base layers 4.

[0184] When the thickness of the uppermost mold base layer 4 in the above lamination is set as K1, the thickness of the second mold base layer 4 from the top is set as K2, and the thickness of the nth mold base layer 4 from the top is set as Kn, it can be expressed as:

[0185] K1 = D1,

[0186] K2 = D2 - (D1 + W), :

[0188] Kn = Dn - (D1 + D2 + ··· (n - 1)W).

[0189] It should be noted that in the present embodiment, at least one K among K1, K2, ··· Kn can be set to a value different from other Ks, or all Ks can be different from each other.

[0190] (Hard mask layer 5)

[0191] The hard mask layer 5 has a function of pre - defining the digging position before etching the plurality of mold base layers 4, that is, the position of the recess 1c to be formed. The top - view shape of all the formed digging positions and their patterns is determined according to the hard mask pattern 5p.

[0192] As the material of the hard mask layer 5, it is a material that has etching resistance to the etching agent of any layer among the mold base layer 4 and the etching stop layer 3.

[0193] That is, preferably, the hard mask layer 5 has an etching selectivity with respect to the mold substrate layer 4 and also has an etching selectivity with respect to the etching stop layer 3.

[0194] It should be noted that after all the desired dug-in portions are formed, the hard mask layer 5 can be removed.

[0195] Examples of the material of the hard mask layer 5 include: a material containing chromium (Cr) (such as chromium oxide (CrO), chromium nitride (CrN), chromium oxynitride (CrON), and at least any one of the materials containing carbon among these).

[0196] The hard mask layer 5 ensures patterning accuracy by exerting a mask function for etching the mold substrate layer 4 and the etching stop layer 3 with a small film thickness. This effect is significant when dry etching is employed. Therefore, its layer thickness is preferably set to, for example, 3 to 30 nm.

[0197] (Resist film)

[0198] As the resist film, a known photoresist can be used. As the resist, a positive-type photoresist or a negative-type photoresist can be used. It should be noted that in the case of exposure for forming a resist pattern by electron beam lithography, a chemically amplified resist for electron beam can be used. In addition, the resist can be coated on the hard mask layer 5 by a known coating device such as a slit coater and a spin coater.

[0199] The film thickness of the resist film is not particularly limited. Considering the aspect of withstanding the etching time of the hard mask layer 5 for forming the hard mask pattern 5p, if it is too large, the pattern accuracy formed will be reduced. Therefore, it is preferably 50 to 300 nm, for example.

[0200] Figs. 2(a) to (p) (that is, Figure 2A (a) to (i) in Figure 2B and (j) to (p) in

[0201] are cross-sectional schematic views showing an example of the manufacturing method of the mold 1 of the present embodiment of the present invention.

[0202] The mold blank 10 of the present embodiment further includes a hard mask layer 5 formed on the stacked mold base material layer 4 and a first resist film 61. It should be noted that the mold blank 10 here may also be a mold intermediate in which a part of the mold base material layer 4 has been patterned.

[0203] As shown in Fig. 2(b), the first resist film 61 on the prepared mold blank 10 is drawn (first drawing) and developed to form a first resist pattern 61p. The first resist pattern 61p has an opening corresponding to the recess to be formed.

[0204] Even when drawing is performed by an electron beam, when the hard mask layer 5 has conductivity, the occurrence of charging can be suppressed, which is suitable.

[0205] As shown in Fig. 2(c), the hard mask layer 5 is etched using the first resist pattern 61p as a mask to form a hard mask pattern 5p (hard mask patterning process). Thereby, the width and position of the recess can be determined.

[0206] In the etching of the hard mask layer 5, dry etching or wet etching can be employed. In the present embodiment, dry etching is used. When the material of the hard mask layer 5 is CrO, as the etching gas used as an etchant, a well-known gas such as a gas containing chlorine (Cl2) can be used.

[0207] As shown in Fig. 2(d), the first resist pattern 61p is peeled off. The peeling can be performed by a well-known method. For example, a resist stripper containing a mixed solution of sulfuric acid and hydrogen peroxide water can be used. Hereinafter, the peeling of the resist pattern is set in the same manner.

[0208] As shown in Fig. 2(e), the uppermost mold base material layer 4 is etched using the hard mask pattern 5p as a mask. Thereby, a first recess pattern is formed. The etching depth of the recess 1c in the first recess pattern is D1 (=K1).

[0209] In the etching of the uppermost mold base material layer 4, dry etching or wet etching can be employed. In the present embodiment, dry etching is used. As the etching gas, a well-known gas can be used (for example, a fluorine-containing gas, preferably CF4 when SiO2 is used as the material of the mold base material layer 4). The same applies to the etching of the mold base material layer 4 described later.

[0210] As shown in Fig. 2(f), a resist is coated on the surface of the mold blank 10 including the hard mask pattern 5p to form a new second resist film 62. The raw material of the second resist film 62 can use the same material as the above-mentioned resist.

[0211] As shown in FIG. 2(g), the second resist film 62 is drawn (second drawing) and developed to form a second resist pattern 62p. The second resist pattern 62p covers a part of the formed first dug-in pattern, and the other parts are exposed. This is to protect the part with a dug-in depth of D1 to be finally obtained from being damaged by etching. As the drawing device, the same device as the drawing device used to form the first resist pattern 61p can be used.

[0212] It should be noted that since a positional shift may occur between the first drawing and the second drawing, in the drawing data of the second drawing, only the alignment margin determined based on the predicted positional shift amount is added to the drawing size (performing sizing). That is, as shown in the figure, a part of the hard mask pattern 5p can be made to expose into the opening of the second resist pattern 62p. The exposure width (the width of sizing) can be set to 5 to 200 nm.

[0213] As shown in FIG. 2(h), using the second resist pattern 62p and the hard mask pattern 5p as masks, the uppermost etching stop layer 3 is etched.

[0214] Dry etching or wet etching can be used for the etching of the uppermost etching stop layer 3. In this embodiment, dry etching is used. As the etching gas, a known gas (for example, CCl4 when using Al2O3 as the material of the etching stop layer 3) can be used. The same applies to the etching of the intermediate etching stop layer 3 described later.

[0215] As shown in FIG. 2(i), using the second resist pattern 62p and the hard mask pattern 5p as masks, the second mold substrate layer 4 from the top is etched. Thereby, a second dug-in pattern can be formed. The dug-in depth of the concave portion 1c of the second dug-in pattern is D2 (=K1 + K2 + W) from the mold surface 1s.

[0216] As shown in FIG. 2(j), the second resist pattern 62p is peeled off.

[0217] As shown in FIG. 2(k), a resist is coated on the surface of the mold blank 10 including the hard mask pattern 5p. The raw material of the third resist film 63 can use the same raw material as the above-mentioned resist.

[0218] As shown in FIG. 2(l), the third resist film 63 is drawn (third drawing) and developed to form a third resist pattern 63p. The third resist pattern 63p covers not only the formed first dug-in pattern but also a part of the second dug-in pattern, and the other parts are exposed. As the drawing device, the same device as the drawing device used to form the first resist pattern 61p can be used.

[0219] Note that positional deviation may occur between the first drawing, the second drawing, and the third drawing. Therefore, the same scaling as that in the second drawing described above can be applied to the drawing data of the third drawing.

[0220] As shown in FIG. 2(m), the third resist pattern 63p and the hard mask pattern 5p exposed in the opening of the third resist pattern 63p are used as masks, and the second etching stop layer 3 from the top is etched.

[0221] As shown in FIG. 2(n), the mold substrate layer 4 at the third position from the top is etched. Thus, a third dug-in pattern is formed. The dug-in depth of the recess 1c of the third dug-in pattern is D3 (=K1 + K2 + K3 + 2W) from the mold surface 1s.

[0222] As shown in FIG. 2(o), the third resist pattern 63p is peeled off.

[0223] Note that in the case where the number of stacked layers of the mold substrate layer 4 is more than three, the Nth dug-in pattern can be formed by repeating the same process as described above. The dug-in depth of the recess 1c of the Nth dug-in pattern is Dn (=K1 + K2 + ··· + Kn + (n - 1)W) from the mold surface 1s.

[0224] In the formation of each recess 1c, the etching is terminated when the etching stop layer 3 is exposed to form the bottom surface. The depths of the plurality of recesses 1c are respectively the sum of the thicknesses of the mold substrate layers 4 with different amounts removed by digging and the thicknesses of the etching stop layers 3 interposed between the removed mold substrate layers 4. In other words, the desired depth of the recess 1c is determined in advance at the design stage of the mold blank 10, and the configurations of the mold substrate layers 4 and the etching stop layers 3 are determined such that the etching stop layer 3 is located at the bottom of the recess 1c.

[0225] After the etching of the necessary mold substrate layer 4 is completed, as shown in FIG. 2(p), the hard mask pattern 5p is peeled off.

[0226] Thus, the mold 1 of the present embodiment is completed. The present embodiment can exhibit the following effects.

[0227] The mold 1 of the present embodiment has a plurality of dug-in portions, and for each dug-in portion, the etching stop layer 3 is exposed at the bottom surface. That is, the end point of the above-mentioned dug-in etching is set to the moment when the etching stop layer 3 is exposed, and the etching stop layer 3 is left intact. Thereby, the etching end point can be easily determined, and the shape of the bottom of the formed dug-in portion is made consistent with the design, so that the depth of the recess 1c can be more precisely controlled.

[0228] That is, it is of great significance to manage the depth of the recess 1c within a range of ±5 nm, and further ±2 nm with respect to the target depth.

[0229] Furthermore, it naturally has the cost advantage of being able to reduce the process of etching the etching stop layer 3.

[0230] In addition, in the manufacturing method of the mold 1 of the present embodiment, the positions and sizes of the respective dug-in portions are determined at the time when the hard mask pattern 5p is formed. In subsequent processes, even if the drawing is repeated, the device positions of the respective recesses 1c will not deviate from the design values. Thus, in the mold 1 of the present embodiment, the pattern formation position and size thereof coincide with the target values with high precision.

[0231] That is to say, the manufacturing method of the present invention can obtain patterning accuracy, particularly excellent control of the dug-in depth, by adopting an optimal laminated structure and manufacturing process for the materials of the mold substrate layer 4 and the etching stop layer 3 respectively.

[0232] Furthermore, the dug-in depths of the dug-in portions with multiple depths can be determined according to the thicknesses of the mold substrate layer 4 and the etching stop layer 3. Therefore, the film formation conditions can be determined according to the dug-in depth to be obtained at the stage of designing the mold blank 10.

[0233] It should be noted that, although not shown in the manufacturing method of FIG. 2, depending on the manufacturing method, the mold substrate layers 4 with different thicknesses may be etched simultaneously. In this case, at the moment when the etching of the mold substrate layer 4 with a relatively small thickness ends, the etching of the mold substrate layer 4 with a larger thickness has not ended. Therefore, if the etching of the mold substrate layer 4 with a larger thickness continues, there is a risk that the exposed edge portion of the mold substrate layer 4 with a relatively small thickness will be damaged by the etching, resulting in a change in the pattern width. On the other hand, according to the manufacturing method of the mold 1 of the present embodiment, by independently controlling the etching processes of the respective mold substrate layers 4 with different thicknesses for each mold substrate layer 4, such risks can be further reduced.

[0234] In addition, according to the present embodiment, the substrate 2, the etching stop layer 3, and the mold substrate layer 4 can be set to be transparent. Thus, when using the mold 1 of the present embodiment and manufacturing an optical element or the like by imprinting, light can be irradiated to the resin through the mold 1 in a state where the pattern surface of the mold 1 is pressed against the transfer body (such as a photocurable resin). Thus, products such as optical elements or replicas for further transfer can be manufactured.

[0235] As a result of the above, according to the present embodiment, it is possible to provide an imprint mold 1 for an optical element and a manufacturing method thereof, in which the shape and depth of the recess 1c of the mold pattern have extremely high precision.

[0236] <Manufacturing method of working replica and / or optical element>

[0237] The method for manufacturing an optical element using the mold 1 of the present embodiment is described below.

[0238] That is, a manufacturing method including the following steps is provided:

[0239] A step of preparing the imprint mold 1 of the present embodiment; and

[0240] A step of directly or indirectly pressing the mold surface 1s of the imprint mold 1 against a transfer body containing a resin material and transferring the mold pattern to the transfer body.

[0241] Here, the procedure for pattern transfer by photoimprinting on the transfer body is described. In the case of photoimprinting using ultraviolet light, an imprinting process at room temperature (e.g., 10 to 30 °C) can be achieved. The preferred wavelength of the ultraviolet light at this time is the same as the preferred wavelength described in <Imprint Mold 1>. However, the mold 1 of the present embodiment can also be applied to thermal imprinting.

[0242] Figure 3 It is a cross-sectional schematic view showing an outline of pattern transfer by photoimprinting using the imprint mold 1 of the present embodiment.

[0243] In the case of pattern transfer by photoimprinting, first, a transfer body is prepared. The transfer body can be a photocurable resin coated on the main surface of a substrate 2 (not shown).

[0244] This photocurable resin can be in a liquid state before curing. In the liquid state, the photocurable resin quickly enters the concave portion 1c of the mold 1 turned upside down, so that the shape of the concave portion 1c can be easily and accurately transferred. Therefore, it is preferred that the viscosity of the photocurable resin before curing is low, preferably about 10 to 1000 mPa·s (25 °C).

[0245] It should be noted that as the photocurable resin, a resin solution obtained by mixing a photopolymerization initiator, a radical initiator, etc. in a matrix resin such as an epoxy resin or a urethane resin can be exemplified. In addition, a resin material that cures by light other than ultraviolet light can also be used.

[0246] Next, Figure 1 The mold 1 of the present embodiment exemplified in is turned upside down so that the photocurable resin 7 faces the mold surface 1s, and the mold 1 is arranged ( Figure 3 (a)).

[0247] Then, by directly pressing the mold 1 against the photocurable resin 7, the mold 1 is brought into contact with the photocurable resin 7. Then, the photocurable resin 7 is cured by ultraviolet exposure to form a resin pattern ( Figure 3(b)). Ultraviolet rays can be irradiated onto the photocurable resin 7 from the back side of the mold surface 1s through the mold 1, for example.

[0248] The form of exposure is not particularly limited.

[0249] Next, the mold 1 is demolded, whereby the mold pattern is transferred to the photocurable resin 7 ( Figure 3 (c)). Further processing such as etching can be performed on the cured resin based on the transferred pattern to manufacture an optical element. Alternatively, instead of using the cured resin with the transferred pattern as an optical element, it can be used as a working replica 8, i.e., a replica of the imprint mold 1, and an optical element can be manufactured using this replica. It should be noted that the working replica 8 is used to manufacture an optical element, and in a broad sense, the working replica 8 can also be interpreted as an optical element.

[0250] Summarizing the above content, according to this embodiment, the mold 1, the substrate 2, the etching stop layer 3, and the mold base layer 4 are transparent as described above. When using the mold 1 of this embodiment and manufacturing an optical element or the like by imprinting, by irradiating light on the resin through the mold 1 in a state where the pattern surface of the mold 1 is pressed from above against the photocurable resin as a resin material, products such as optical elements or replicas can be manufactured.

[0251] It should be noted that in order to easily demold the mold 1, a release layer can be formed on the outermost surface of the mold 1 (i.e., the surface in contact with the gas atmosphere, including not only the mold surface 1s but also the bottom and side portions of the recess 1c). In this case, the mold surface 1s of the mold 1 is indirectly pressed against the transfer body containing the resin material.

[0252] As a release agent, a known release agent can be used. For example, it can be exemplified: a surface modifier containing a silicone compound having a linear perfluoropolyether structure, or an unmodified or modified silicone oil, a polysiloxane containing trimethylsilyloxy silicic acid, a silicone-based acrylic resin, etc. In addition, as described in Japanese Unexamined Patent Application Publication No. 2012-048772, a compound having one or more (C m F 2m O) n [m is an integer and 1 ≤ m ≤ 7, n is an integer such that the molecular weight of (C m F 2m O) n is 500 or more and 6000 or less], having at least 2 hydroxyl groups as adsorption functional groups capable of adsorbing to the mold 1, and hydroxyl groups provided at both ends in the molecular chain can be used as a release agent.

Claims

1. A manufacturing method of an imprint mold, the imprint mold having a plurality of concave portions constituting a given mold pattern, The manufacturing method includes: A step of preparing a mold blank, the mold blank having a laminate formed on a substrate, the laminate including a plurality of mold base layers and an etching stop layer interposed between the mold base layers, and a hard mask layer formed on the laminate; A hard mask patterning step of etching the hard mask layer based on the design of the mold pattern to form a hard mask pattern; A concave portion forming step of using a given resist pattern and the hard mask pattern formed on the laminate provided with the hard mask pattern as a mask, and performing N times of mold digging etching for etching the mold base layer or the etching stop layer and the mold base layer, thereby forming the plurality of concave portions having different depths, where N is an integer of 2 or more; and A step of removing the hard mask pattern, The mold base layer and the etching stop layer are formed of materials having etching selectivity with respect to each other, The plurality of formed concave portions respectively have bottom surfaces where the etching stop layer is exposed, The mold pattern is transferred to a transfer body.

2. The manufacturing method of an imprint mold according to claim 1, wherein The number of times N of the mold digging etching is set to 2 ≤ N ≤ 5.

3. The manufacturing method of an imprint mold according to claim 1 or 2, wherein The laminate includes the plurality of mold base layers having different thicknesses.

4. The manufacturing method of an imprint mold according to claim 1 or 2, wherein The plurality of concave portions having different depths are respectively concave portions vertically dug independently from the mold surface.

5. The manufacturing method of an imprint mold according to claim 1 or 2, wherein An etching stop layer is disposed between the mold base layer closest to the substrate and the substrate.

6. An imprint mold having a plurality of concave portions constituting a given mold pattern, Among them, The imprint mold has a laminate including a plurality of mold base layers and an etching stop layer interposed between the mold base layers on a substrate, The laminate has the plurality of concave portions having different depths, The mold base layer and the etching stop layer are formed of materials having etching selectivity with respect to each other, The plurality of concave portions respectively have bottom surfaces where the etching stop layer is exposed, The mold pattern is transferred to a transfer body.

7. The imprint mold according to claim 6, wherein The plurality of concave portions having different depths are respectively concave portions vertically dug independently from the mold surface.

8. The imprint mold according to claim 6 or 7, wherein The laminate includes the plurality of mold base layers having different thicknesses.

9. The imprint mold according to claim 6 or 7, wherein When the mold base layer and the etching stop layer are formed to have the same thickness, the transmittance of ultraviolet rays is 1:0.8 to 1:0.

95.

10. The imprint mold according to claim 6 or 7, wherein The thickness of the mold base layer is 3 to 25 times the thickness of the etching stop layer.

11. The imprint mold according to claim 6 or 7, wherein The plurality of recesses are formed by etching and removing mold substrate layers having different numbers and ranging from 2 to 5 layers respectively.

12. The imprint mold according to claim 6 or 7, wherein An etching stop layer is disposed between the mold substrate layer closest to the substrate and the substrate.

13. The imprint mold according to claim 6 or 7, which is applied to ultraviolet light imprinting.

14. A mold blank for manufacturing an imprint mold having a mold pattern including a plurality of recesses with different depths, Among them, The mold blank is for obtaining the imprint mold having recesses with depths D1 and D2 from the mold surface respectively, where D1≠D2. In this mold blank, a plurality of mold substrate layers are stacked on the substrate surface, and a hard mask layer is further formed on the surface side thereof. Moreover, an etching stop layer with a thickness W formed of a material having etching selectivity for the mold substrate layer is interposed between each of the plurality of mold substrate layers. When the thickness of the mold substrate layer farthest from the substrate in the stacking is set as K1 and the thickness of the mold substrate layer in the second position from the top is set as K2, the thicknesses of the plurality of mold substrate layers are set such that: K1 = D1, K2 = D2 - (D1 + W) An etching stop layer is disposed between the mold substrate layer closest to the substrate and the substrate. The thickness of each layer of the mold substrate layer is 10 to 500 nm and is 3 to 25 times the thickness W of the etching stop layer.

15. A mold blank is used to obtain an embossing mold having recesses with depths D1, D2, ··· Dn from the mold surface, where, n is an integer of 3 or more, and D1, D2 ··· Dn are different from each other. In this mold blank, a plurality of mold substrate layers are stacked on the substrate surface, and a hard mask layer is further formed on the surface side thereof. Moreover, an etching stop layer with a thickness W formed of a material having etching selectivity for the mold substrate layer is interposed between each of the plurality of mold substrate layers. When the thickness of the mold substrate layer farthest from the substrate in the stacking is set as K1, the thickness of the mold substrate layer in the second position from the top is set as K2, and the thickness of the mold substrate layer in the nth position from the top is set as Kn, the thicknesses of the plurality of mold substrate layers are set such that: K1 = D1, K2 = D2 - (D1 + W), ： Kn = Dn - (D1 + D2 + ··· (n - 1)W) An etching stop layer is disposed between the mold substrate layer closest to the substrate and the substrate. The thickness of each layer of the mold substrate layer is 10 to 500 nm and is 3 to 25 times the thickness W of the etching stop layer.

16. The mold blank according to claim 14 or 15, wherein The mold substrate layer contains silicon and oxygen, and the etching stop layer contains silicon, aluminum and oxygen.

17. The mold blank according to claim 14 or 15, wherein The refractive index n of the etching stop layer for light with a wavelength of 365 nm is 2.2 or less.

18. The mold blank according to claim 14 or 15, wherein The extinction coefficient k of the etching stop layer for light with a wavelength of 365 nm is 0.01 or less.

19. A method for manufacturing an optical element, the method comprising: a step of preparing an imprint mold according to any one of claims 6 to 13; and a step of directly or indirectly pressing a mold surface of the imprint mold against a transfer body containing a resin material to transfer the mold pattern to the transfer body.

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