Method for manufacturing pattern master, mold and substrate

Abstract

The present invention provides a method for manufacturing a pattern master, a mold, and a method for manufacturing a substrate, wherein the pattern master has a fine concave-convex pattern on its surface, the substrate has a concave-convex structure on its surface, the pattern master has a substrate and a concave-convex structure layer arranged on one surface of the substrate, at least one surface of the substrate is made of a material with an etching stop function, the substrate is exposed to the bottom of at least a portion of the concave portions of the concave-convex structure layer, and in the concave-convex pattern, the deviation of the bottom point position of each concave portion of the concave-convex pattern in a direction perpendicular to one surface is less than 20nm.

Description

[0001] This application is a divisional application of the Chinese invention patent application with the application date of May 17, 2019, the invention name of which is "Pattern master, method for manufacturing pattern master, method for manufacturing mold and method for manufacturing substrate", and the application number is 201980035676.5 (PCT / JP2019 / 019793). Technical Field

[0002] The present invention relates to a pattern master having a fine concavo-convex pattern on its surface, a method for manufacturing the pattern master, a method for manufacturing a mold using the pattern master, and a method for manufacturing a substrate having a concavo-convex structure on its surface. Background Art

[0003] In transparent substrates such as glass and plastic lenses and cover glasses, an anti-reflection structure or anti-reflection film is sometimes provided on the light-incident surface to reduce the loss of transmitted light due to surface reflection. For example, a so-called moth-eye structure, a fine concave-convex structure with a pitch shorter than the wavelength of visible light, is known as an anti-reflection structure for visible light.

[0004] As a method for forming a moth-eye structure, from the perspective of processing volume, pattern transfer technology based on nanoimprinting has attracted much attention (refer to Japanese Patent Publication No. 2015-029118 (hereinafter referred to as Patent Document 1)). Nanoimprinting is a technology in which a mold having a concave-convex pattern is pressed on a resist coated on a workpiece, and the resist is mechanically deformed or flowed to precisely transfer a fine pattern to the resist film. After the pattern is transferred, for example, by etching the workpiece using the resist with the transferred pattern as a mask, a concave-convex structure can be formed on the surface of the workpiece. In addition, a mold having a concave-convex pattern is also generally referred to as a mold, a stamper or a template. Hereinafter, a mold having a concave-convex pattern for imprinting will be referred to as a mold.

[0005] As a mold used in the nanoimprint method, for example, a structure having a concave-convex structure including an anodized porous aluminum oxide layer on a substrate is known (International Publication No. 2010 / 087139 (hereinafter referred to as Patent Document 2), Japanese Patent Gazette No. 2012-137534 (hereinafter referred to as Patent Document 3)).

[0006] Furthermore, Japanese Patent Application Publication No. 2007-268831 (hereinafter referred to as Patent Document 4) discloses a method for manufacturing a mold, wherein a resist layer is formed on a substrate, exposure and patterning are performed on the resist layer, and the patterned resist layer is used as a mask for etching to produce a mold having a concave-convex pattern formed on the surface of the substrate. Patent Document 4 discloses a method for manufacturing a mold, wherein a laminated body made of the same material with different stacking surface orientations is used as a substrate, and the etching rate varies depending on the surface orientation to produce a mold having a concave-convex pattern with a constant concave-convex depth.

[0007] In nanoimprint lithography, the same mold can be reused multiple times, but the mold deteriorates with each repetition. Therefore, in applications such as optical component manufacturing and surface processing, it is necessary to prepare multiple copies of the mold with the same pattern. To replicate this mold, a master mold (pattern master) is used, which has a concave-convex structure that is the inverse of the concave-convex structure of the mold.

[0008] Japanese Patent Application Publication No. 2013-185188 (hereinafter referred to as Patent Document 5) and Japanese Patent Application Publication No. 2015-059977 (hereinafter referred to as Patent Document 6) disclose a method of forming a fine concavo-convex structure layer made of gibbsite on a substrate surface and etching the substrate surface using the concavo-convex structure layer as a mask. In particular, Patent Document 5 describes a method of producing a pattern master used in mold production. Summary of the Invention

[0009] Technical issues to be solved by the invention

[0010] In the manufacture of the molds disclosed in Patent Documents 2 and 3, repeated anodization and etching are required to form the moth-eye structure, which is time-consuming. Furthermore, in the manufacture of the mold disclosed in Patent Document 4, the resist exposure and development steps are also time-consuming. In mold manufacturing, it is desirable to increase throughput.

[0011] On the other hand, as in Patent Document 5, if a pattern master is produced using a concavo-convex structure layer made of gibbsite as an etching mask and an imprint mold is produced using the pattern master, the mold can be produced with a higher throughput than before.

[0012] However, it is known that when imprinting is performed using a mold manufactured using a pattern master produced using the method described in Patent Document 5, problems may arise, such as the height of the concave-convex pattern formed on the surface of the workpiece being extremely small, or the desired concave-convex pattern not being formed. Furthermore, the inventors, through in-depth research, discovered that the cause of these problems is the large variation in the height position of the apex of the convex portions in the mold's concave-convex pattern, which results in large variations in the thickness of the residual resist film during imprinting. Furthermore, they discovered that the variation in the height position of the apex of the mold's convex portions corresponds to the variation in the height position of the bottom of the concave portions in the pattern master's concave-convex pattern.

[0013] The present invention has been made in view of the above circumstances. The purpose of the present invention is to provide a pattern master in which the height deviation of the bottom point of the concave portion of the concave-convex pattern is suppressed, a method for manufacturing the pattern master, a method for manufacturing a mold using the pattern master, and a method for manufacturing a substrate having a concave-convex structure on its surface.

[0014] Means for solving technical problems

[0015] Specific solutions for solving the above-mentioned problems include the following methods.

[0016] <1> A pattern master having a fine concave-convex pattern on its surface, the pattern master comprising a substrate and a concave-convex structure layer, the concave-convex structure layer being arranged on one surface of the substrate and comprising a plurality of convex portions and a plurality of concave portions along the concave-convex pattern, at least one surface of the substrate being made of a material having an etching stop function, the substrate being exposed to the bottoms of at least a portion of the concave portions of the concave-convex structure layer, and the deviation of the bottom point position of each concave portion of the concave-convex pattern in a direction perpendicular to the one surface in the concave-convex pattern being less than 20 nm.

[0017] <2> The pattern master according to <1>, wherein the concavo-convex pattern is uneven with an average period of 400 nm or less.

[0018] <3> The pattern master according to <1> or <2>, wherein in the concavo-convex pattern, a deviation in the position of the apex of each convex portion in a direction perpendicular to the one surface exceeds 5 nm.

[0019] <4> The pattern master as described in any one of <1> to <3>, wherein an interdiffusion layer in which a material constituting the concave-convex structure layer and a material constituting the one surface of the substrate are mixed is formed in the interface region between the concave-convex structure layer and the substrate.

[0020] <5> The pattern master according to any one of <1> to <4>, wherein the one surface of the base is made of silicon oxide.

[0021] <6> The pattern master according to any one of <1> to <4>, wherein the one surface of the base is made of metal.

[0022] <7> The pattern master according to any one of <1> to <6>, wherein the concavo-convex structure layer is a layer containing silicon as a main component.

[0023] <8> The pattern master according to any one of <1> to <4>, wherein the concavo-convex structure layer is a layer containing silicon as a main component, and the one surface of the base is a layer containing nickel as a main component.

[0024] <9> The pattern master according to <8>, wherein a nickel silicide layer is formed in an interface region between the concavo-convex structure layer and the substrate.

[0025] <10> The pattern master according to any one of <7> to <9>, wherein the concavo-convex structure layer is made of polycrystalline or amorphous silicon.

[0026] <11> The pattern master according to any one of <1> to <10>, wherein the base is composed of a laminate including: a first layer including the one surface; and a second layer made of a material different from that of the first layer.

[0027] <12> A method for manufacturing a pattern master, wherein a stacked body is prepared, the stacked body having a processed layer and a thin film containing aluminum in sequence on one surface of a substrate, and at least the above-mentioned one surface of the above-mentioned substrate is made of a material having an etching stop function, the thin film containing the above-mentioned aluminum is subjected to warm water treatment to form a first concave-convex structure layer made of aluminum oxide hydrate, the first concave-convex structure layer and the above-mentioned processed layer are etched from the side of the first concave-convex structure layer until the above-mentioned first concave-convex structure layer is removed, and the above-mentioned one surface of the above-mentioned substrate is exposed to at least a part of the concave portion formed on the above-mentioned processed layer, and the above-mentioned processed layer is processed into a second concave-convex structure layer comprising a plurality of convex portions and a plurality of concave portions.

[0028] <13> The method for manufacturing a pattern master according to <12>, wherein, in the etching step, when the etching rate of the first concavo-convex structure layer is set to Ra, the etching rate of the processed layer is set to Rw, and the etching rate of the substrate is set to Rs,

[0029] The etching after the layer to be processed is exposed to the recessed portion of the first concavo-convex structure layer is performed under the condition of Rw>Ra>Rs.

[0030] <14> The method for manufacturing a pattern master according to <12> or <13>, wherein at least the one surface of the base is made of silicon oxide or metal.

[0031] <15> The method for manufacturing a pattern master according to any one of <12> to <14>, wherein the layer to be processed is a layer containing silicon as a main component.

[0032] <16> The method for manufacturing a pattern master according to any one of <12> to <15>, wherein an etching gas containing halogen atoms is used in the etching.

[0033] <17> The method for producing a pattern master according to <16>, wherein the halogen atom is a fluorine atom.

[0034] <18> The method for manufacturing a pattern master according to any one of <12> to <17>, wherein the thin film containing aluminum has a film thickness of 2 nm to 20 nm.

[0035] <19> The method for manufacturing a pattern master according to any one of <12> to <18>, wherein heat treatment is performed after the etching step.

[0036] <20> A method for manufacturing a mold, comprising using the pattern master according to any one of <1> to <11>,

[0037] A mold having a surface thereof having a transferred concavo-convex pattern of the concavo-convex pattern of the pattern master is manufactured.

[0038] <21> A method for manufacturing a mold as described in <20>, wherein a resin composition layer is formed along the above-mentioned concave-convex pattern on the above-mentioned surface of the above-mentioned pattern master, the above-mentioned resin composition layer is cured to form a resin layer having a transferred concave-convex pattern of the above-mentioned concave-convex pattern, and the above-mentioned resin layer is peeled off from the above-mentioned pattern master to obtain a flexible mold having the above-mentioned transferred concave-convex pattern on the surface.

[0039] <22> A method for manufacturing a substrate having a concave-convex structure on its surface, wherein the pattern master described in any one of <1> to <11> is used to prepare a mold having a first transfer concave-convex pattern on its surface on which the concave-convex pattern of the pattern master is transferred, a resist is applied to one surface of the processed substrate, the first transfer concave-convex pattern of the mold is pressed onto the resist, thereby transferring the first transfer concave-convex pattern to the resist to form a second transfer concave-convex pattern, the resist formed with the second transfer concave-convex pattern is cured, thereby forming a second resin layer having the second transfer concave-convex pattern, the second resin layer having the second transfer concave-convex pattern is used as a mask, the second resin layer and the processed substrate are etched from the second resin layer side, and a concave-convex pattern is formed on the surface of the processed substrate.

[0040] Effects of the Invention

[0041] According to one embodiment of the present invention, it is possible to provide a pattern master in which the positional variation of the bottom of the concave portion of the concave-convex pattern is suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a diagram schematically showing a cross section of a pattern master according to the first embodiment of the present invention.

[0043] Figure 2 It will Figure 1 A diagram showing an enlarged portion of the pattern master shown in .

[0044] Figure 3 This is a scanning electron microscope image obtained by photographing the concavo-convex pattern of the pattern master according to one embodiment of the present invention from a direction perpendicular to one surface of the substrate.

[0045] Figure 4 This is a scanning electron microscope image of the concavo-convex pattern of the pattern master according to another embodiment of the present invention, taken from a direction perpendicular to one surface of the substrate.

[0046] Figure 5 This is a scanning electron microscope image obtained by photographing the concavo-convex pattern of the pattern master according to still another embodiment of the present invention from a direction perpendicular to one surface of the substrate.

[0047] Figure 6 This is a diagram schematically showing an interdiffusion layer formed between the concavo-convex structure layer and the base in a pattern master according to one embodiment.

[0048] Figure 7 It is a diagram schematically showing a cross section of a pattern master according to a second embodiment of the present invention.

[0049] Figure 8 It is a diagram showing the manufacturing process of the pattern master according to the second embodiment.

[0050] Figure 9 It is a figure which shows the manufacturing process of the flexible mold|die which concerns on one embodiment of this invention.

[0051] Figure 10 It is a diagram showing the manufacturing process of a base having a concavo-convex structure on its surface.

[0052] Figure 11 This is a scanning electron microscope image of the surface of the pattern master of the example.

[0053] Figure 12 This is a scanning electron microscope image of a cross section of a pattern master according to an example. DETAILED DESCRIPTION

[0054] Hereinafter, embodiments of the present invention will be described using the drawings. For easier visual recognition, the scales of the components in the drawings are appropriately different from the actual scales.

[0055] "Original Pattern"

[0056] A pattern master according to a first embodiment of the present invention will be described. Figure 1 It is a diagram schematically showing a cross section of the pattern master 1 according to the first embodiment.

[0057] The pattern master 1 has a fine concave-convex pattern 2 on its surface. The pattern master 1 has a substrate 10 and a concave-convex structure layer 20, which is provided on a surface 10a of the substrate 10 and includes a plurality of convex portions 22a and a plurality of concave portions 22b along the concave-convex pattern 2. At least one surface 10a of the substrate 10 is made of a material different from the concave-convex structure layer 20, and in particular, one surface 10a of the substrate 10 is made of a material having an etching stop function. Here, the material having an etching stop function refers to a material having an etching rate lower than that of the concave-convex structure layer 20 relative to the etching gas when the concave-convex structure layer 20 is formed by etching. In particular, it is preferred that the material have an etching rate lower than that of the concave-convex structure layer 20 relative to the etching gas containing at least one of a rare gas, oxygen, a fluorine-based gas and a chlorine-based gas.

[0058] The concavo-convex pattern 2 is mainly composed of a plurality of convex portions 22a and a plurality of concave portions 22b of the concavo-convex structure layer 20. That is, the concavo-convex structure layer 20 includes convex portions 22a and concave portions 22b along the concavo-convex pattern 2. Most of the convex portions 2a and concave portions 2b of the concavo-convex pattern 2 coincide with the convex portions 22a and concave portions 22b of the concavo-convex structure layer 20.

[0059] Figure 2 yes Figure 1 A partially enlarged view of the pattern master 1 shown in FIG. The base 10 is exposed to the bottom of at least a portion of the recess 22b of the recessed portion 22b of the recessed portion 22b of the recessed portion 20. In this case, the base 10 has a form in which one surface 10a of the base 10 is exposed to the bottom of the recessed portion 22b of the recessed portion 22b of the recessed portion 20, or the base 10 is exposed to the bottom of the recessed portion 22b of the recessed portion 20, and the recessed portion 10b is also formed on a portion of the base 10. In these cases, the recessed portion 2b of the recessed portion 2b of the recessed portion 20 and one surface 10a of the base 10 are composed of the recessed portion 22b of the recessed portion 20 and the base 10, or the recessed portion 22b of the recessed portion 20 and the recessed portion 10b provided on the base 10.

[0060] In the concavo-convex pattern 2 of the present pattern master 1, a deviation α in the position of the bottom point of each concave portion 2b in a direction perpendicular to the one surface 10a of the substrate 10 is 20 nm or less.

[0061] Here, the bottom point of the concave portion 2b refers to a point at the deepest position of each concave portion 2b in a direction perpendicular to one surface 10a of the base 10. Figure 2 As shown, the deviation α of the bottom point position of each recess 2b refers to the distance between the bottom point of the deepest recess and the bottom point of the shallowest recess among the plurality of recesses 2b. Hereinafter, the position of the bottom point of a recess (or bottom point position) refers to the position of the bottom point of the recess in a direction perpendicular to one surface 10a of the substrate 10.

[0062] On the other hand, in the concavo-convex pattern 2 of the pattern master 1, the smaller the deviation in the position of the apex of each convex portion 2a in the direction perpendicular to the one surface 10a of the base 10, the more preferably it is. However, it may exceed 5 nm.

[0063] Here, the vertex of the convex portion 2a refers to a point located at the highest position of each convex portion 2a in a direction perpendicular to one surface 10a of the base 10. Figure 2 As shown, the deviation β of the position of each protrusion 2a refers to the distance from the vertex of the highest protrusion to the vertex of the lowest protrusion among the multiple protrusions 2a. Hereinafter, the position of the vertex of the protrusion (or vertex position) refers to the position of the vertex of the protrusion in the direction perpendicular to one surface 10a of the substrate 10.

[0064] The positional deviation of the concave bottoms and convex apex was determined by measuring the pattern height using an atomic force microscope (AFM) and randomly selecting 10 concave bottoms and convex apex points. The positional deviation of the concave bottoms was calculated as the difference between the deepest and shallowest of the 10 extracted concave bottoms. Furthermore, the positional deviation of the convex apex was calculated as the difference between the highest and lowest of the 10 extracted convex apex points.

[0065] Furthermore, the degree of the variation in the bottom position and the apex position of the concave portions of the concavo-convex pattern can be observed by taking a scanning electron microscope (SEM) image of the cross section of the pattern master 1 .

[0066] The height difference of the concave and convex portions of the concave-convex pattern 2 is preferably 100 nm or greater, more preferably 200 nm or greater, and even more preferably 300 nm or greater. From the perspective of anti-reflection, a larger height difference is preferred. However, from the perspective of mechanical strength, it is preferably 1 μm or less, and more preferably 500 nm or less. The height difference referred to herein is the distance from the bottom point of a concave portion to the top point of a convex portion. The height difference of the concave and convex portions of the concave-convex pattern 2 can be considered to be the distance between the center of deviation of the top point of a convex portion 2a and the center of deviation of the bottom point of a concave portion 2b.

[0067] Regarding the concave-convex pattern 2, it is preferred that the average period be 400 nm or less and the concave-convex be uneven. The average period is preferably 300 nm or less, more preferably 200 nm or less. Here, the period refers to the arrangement period of the convex parts or the concave parts, such as Figure 1 As shown, the distance T1 between the closest convex portions across a concave portion in the concave-convex pattern 2, or the distance T2 between the closest concave portions across a convex portion, can be represented. In the concave-convex pattern 2, the arrangement period of the convex portions 2a and the concave portions 2b is not constant. Furthermore, the shapes of the convex portions and the concave portions are not uniform.

[0068] The average period can be determined by, for example, capturing a surface image of a fine concavo-convex structure with an SEM, performing image processing and binarization, and performing statistical processing.

[0069] The concavo-convex pattern 2 may be composed of a plurality of isolated convex portions and concave regions surrounding the convex portions, or may be composed of isolated concave portions and convex regions surrounding the concave portions. In the former case, the shape and arrangement of the convex portions, as well as the shape of the concave regions, may be non-uniform. Similarly, in the latter case, the shape and arrangement of the concave portions, as well as the shape of the convex regions, may be non-uniform. Furthermore, a concavo-convex pattern may be formed with uneven convex and concave regions.

[0070] Figures 3 to 5 These are SEM images of the concave-convex patterns of pattern masters from examples of the present invention, taken perpendicular to the substrate. In each figure, the white portions are convex, and the dark gray portions are concave. In all cases, the concave-convex pattern is unevenly arranged in a sea-island structure. In this specification, "uneven concave-convex" refers to a sea-island structure in which the shapes of the concave and convex portions vary, and the arrangement of the concave and convex portions is irregular. Figure 3 In the embodiment, a concave-convex pattern is formed which is composed of a plurality of isolated convex portions and concave regions surrounding the convex portions. Figure 4 In the embodiment, a concave-convex pattern is formed which is composed of a plurality of isolated concave portions and convex regions surrounding the concave portions. Figure 5 In the formation of Figure 3 and Figure 4 An intermediate concave-convex pattern is obtained by mixing continuous convex areas and continuous concave areas.

[0071] like Figure 6 As shown, an interdiffusion layer 15 in which the material constituting the concavo-convex structure layer 20 and the material constituting the one surface 10 a of the substrate 10 are mixed is preferably formed in the interface region between the concavo-convex structure layer 20 and the substrate 10 .

[0072] The interdiffusion layer 15 can improve the adhesion between the concavo-convex structure layer 20 and the base 10. Since the adhesion between the concavo-convex structure layer 20 and the base 10 is high, when the flexible mold described later is manufactured, it is possible to suppress the concavo-convex structure layer 20 and the base 10 from being peeled off when the flexible mold is peeled off from the concavo-convex structure layer.

[0073] As described above, one surface 10a of the substrate 10 may be composed of a material having an etching rate lower than that of the concave-convex structure layer 20 relative to the etching gas used when etching to form the concave-convex structure layer 20. For example, when the concave-convex structure layer 20 is silicon, fluorine-based gases such as sulfur hexafluoride (SF6) and trifluoromethane (CHF3) are suitable as gases for etching the concave-convex structure layer 20, and metals such as nickel (Ni) and chromium (Cr), silicon oxide (SiO2), sapphire, etc. can be cited as materials having an etching rate lower than that of the concave-convex structure layer 20 relative to the gases. Furthermore, when the concave-convex structure layer 20 is Cr, chlorine gas is suitable as a gas for etching the concave-convex structure layer 20, and sapphire can be cited as a material having an etching rate lower than that of the concave-convex structure layer 20 relative to the gases.

[0074] One surface 10a of the substrate 10 is preferably made of an oxide such as silicon oxide or sapphire, a nitride or carbide of a metal, or a metal. Examples of the metal include nickel and chromium. From these materials, one surface 10a of the substrate 10 can be selected so as to function as an etching stop layer in relation to the material of the concavo-convex structure layer 20 and the etching gas.

[0075] On the other hand, the concavo-convex structure layer 20 is preferably a layer containing silicon as a main component. A layer containing silicon as a main component means a layer containing 50 atomic % or more of silicon. As a layer containing silicon as a main component, a polycrystalline silicon layer or an amorphous silicon layer is particularly preferred.

[0076] In addition, when the concave-convex structure layer 20 is a layer containing silicon as a main component, one surface 10a of the substrate is preferably composed of a material containing nickel as a main component. In this case, a nickel silicide layer can be formed as an interdiffusion layer 15 in the interface region between the concave-convex structure layer 20 and the substrate 10. If a nickel silicide layer is formed at the interface, the adhesion between the concave-convex structure layer 20 and the substrate 10 is improved, and therefore it is preferred.

[0077] Regarding the substrate 10, at least one surface 10a is sufficient to be made of a material having an etch-stop function, but the entire substrate may be composed of the same material. Alternatively, the substrate 10 may be composed of a stack of two or more layers, including a first layer including one surface 10a and a second layer made of a material different from the first layer.

[0078] Figure 7It is a diagram schematically showing a cross section of a pattern master 3 according to the second embodiment.

[0079] The pattern master 3 includes all the structures of the pattern master 1 of the first embodiment. The pattern master 3 differs from the pattern master 1 of the first embodiment in that the substrate 10 is structured to include a first layer 11 having a single surface 10a and a second layer 12 laminated in contact with the first layer. The first layer 11 is an etching stopper layer that functions as an etching stopper when the concavo-convex structure layer 20 is formed by etching.

[0080] The material constituting the one surface 10a of the base 10 described in the first embodiment can be used as the first layer 11. That is, a metal layer such as silicon oxide or nickel can be used as the first layer 11. The first layer 11 can be formed on the second layer 12 by sputtering or the like.

[0081] As the second layer 12 , for example, a silicon wafer can be used.

[0082] Even in this configuration, the same effects as those of the pattern master 1 of the first embodiment can be obtained.

[0083] "Method for producing a pattern master"

[0084] A method for manufacturing a pattern master according to one embodiment of the present invention will be described. Figure 8 1 and 2 are diagrams showing the steps of a method for manufacturing a pattern master according to one embodiment of the present invention. As an example, this method is a method for manufacturing the pattern master 3 according to the second embodiment described above.

[0085] In the method for manufacturing a pattern master, a laminate 5 is first prepared, wherein the laminate 5 includes a workpiece layer 20a and a thin film 25 containing aluminum in this order on one surface 10a of a substrate 10, and at least one surface 10a of the substrate 10 is made of a material that functions as an etch stopper for the workpiece layer 20a (step 1). Here, a substrate 10 is used in which a first layer 11 serving as an etch stopper is formed on one surface of a second layer 12.

[0086] Next, the aluminum-containing thin film 25 is subjected to a warm water treatment (step 2). For example, each laminate 5 is immersed in pure water 6 contained in a container 7 and subjected to a warm water treatment. This warm water treatment forms a concavo-convex structure layer 26 made of aluminum oxide hydrate (step 3).

[0087] Then, the concave-convex structure layer 26 and the processed layer 20a are etched from the side of the concave-convex structure layer 26 made of aluminum oxide hydrate until the concave-convex structure layer 26 is removed and one surface 10a of the substrate 10 is exposed to the concave portion provided on the processed layer 20a (step 4), and the processed layer 20a is processed into a concave-convex structure layer 20 including a convex portion 22a and a concave portion 22b (step 5).

[0088] Through the above steps, the pattern master 3 having the fine concavo-convex pattern 2 on the surface can be obtained.

[0089] Alternatively, after etching, the laminate including the base 10 and the concavo-convex structure layer 20 provided on one surface 10 a thereof may be subjected to heat treatment, and the laminate after the heat treatment may be used as a pattern master.

[0090] It is known that when a thin film 25 containing aluminum is treated with warm water, a fine concavo-convex structure with aluminum oxide hydrate (Al2O3·H2O) as the main component is formed on its surface. Here, "aluminum oxide hydrate as the main component" means that the content of aluminum oxide hydrate in the concavo-convex structure layer is 50% by mass or more.

[0091] The film 25 containing aluminum is preferably made of any one of aluminum, aluminum oxide, aluminum nitride or aluminum oxynitride. Furthermore, the film 25 can be made of an aluminum alloy. "Aluminum alloy" refers to a compound or solid solution having aluminum as a main component and containing at least one of elements such as silicon (Si), iron (Fe), copper (Cu), manganese (Mn), magnesium (Mg), zinc (Zn), chromium (Cr), titanium (Ti) and nickel (Ni). With regard to the film 25, from the perspective of forming a concave-convex structure (hydraulic mineralization), the composition ratio of aluminum to all metal elements is preferably 80 mol% or more. This film having aluminum as the main component is modified into aluminum oxide hydrates such as hydraulic mineral by warm water treatment, and a concave-convex structure is formed on its surface.

[0092] The method for forming the thin film 25 containing aluminum on the processing layer 20a is not particularly limited. For example, a vapor phase method such as evaporation, sputtering, ion plating, or chemical vapor deposition, or a sol-gel method in which an aluminum precursor solution is applied by a liquid phase method such as spin coating, dip coating, or inkjet and then sintered can be used.

[0093] In this specification, "warm water treatment" refers to a treatment in which warm water is applied to a thin film containing aluminum. Warm water treatment is, for example, a method in which the laminate 5 formed with the thin film 25 containing aluminum is immersed in water at room temperature (especially, preferably pure water) and then the water is boiled, a method in which the laminate 5 is immersed in warm water maintained at a high temperature, or a method in which the laminate is exposed to high-temperature water vapor. For example, in the present embodiment, each laminate 5 is immersed in a state in which the pure water 6 in the container 7 is heated and boiled using a heating plate 8. The boiling and immersion time and the temperature of the warm water are appropriately set according to the desired concave-convex structure. The reference time is more than 1 minute, and more than 3 minutes and less than 15 minutes is more appropriate. From the viewpoint of gibbsite mineralization, the temperature of the warm water is preferably more than 60°C, and more preferably a temperature higher than 90°C. The higher the temperature, the shorter the treatment time tends to be. For example, boiling a 10nm-thick aluminum film in 100°C water for 3 minutes produces a randomly arranged concave-convex structure with convex-convex spacing of 50 to 300nm and convex heights of 50 to 100nm, i.e., an uneven concave-convex pattern. The depth of the concave and convex heights also vary widely, typically by 5nm or more, or 10nm or more.

[0094] The thickness of the concave-convex structure layer 26 (hereinafter referred to as the first concave-convex structure layer 26) made of aluminum oxide hydrate formed after the warm water treatment is defined as the height from the surface of the processed layer 20a to the apex of the convex portion. The thickness of the first concave-convex structure layer 26 is preferably 130 nm or more, and more preferably 200 nm or more. The conditions for obtaining a concave-convex structure layer of 130 nm or more vary depending on the material of the aluminum-containing thin film as its precursor, but are preferably set to a film thickness of approximately 2 nm or more and 20 nm or less. Under the same warm water treatment conditions, the thickness of the concave-convex structure layer increases as the film thickness of aluminum increases.

[0095] The thickness of the aluminum-containing film 25 and the thickness of the concavo-convex structure layer 26 obtained by treating the film 25 with warm water can be determined by taking a cross-sectional SEM image in each process. However, in actual manufacturing, it is impossible to expose the cross section. Therefore, the relationship between the film thickness of the film 25 and the film formation time, and the relationship between the film thickness of the film 25 and the thickness of the concavo-convex structure layer 26, etc., are determined in advance, and manufacturing can be performed based on the pre-determined relationships.

[0096] In the method for manufacturing a pattern master of this embodiment, etching is performed from the side of the fine concavo-convex structure made of aluminum oxide hydrate along the concavo-convex structure, causing the surface shape to recede. This results in a concavo-convex structure on the processed layer 20a that reflects the shape of the concavo-convex structure of the aluminum oxide hydrate. Furthermore, "reflecting" the concavo-convex structure of the aluminum-containing thin film means that the positional accuracy of the convex or concave portions of the concavo-convex structure need not be achieved at each position corresponding to each convex or concave portion (so-called transfer), but rather that some degree of similarity exists in the undulations.

[0097] The laminated body comprising the substrate 10 and the processed layer 20a is a component that becomes the pattern master 1 by processing the processed layer 20a. The shape of the substrate 10 is not particularly limited and can be appropriately determined based on the pattern master 1 to be manufactured. For example, a wafer-shaped or rectangular flat substrate can be used as the substrate 10. Furthermore, a three-dimensional component having a curved surface (e.g., a spherical surface) can also be used as the substrate.

[0098] The base 10 may be formed of a material having a lower etching rate than the target layer 20 a and functioning as an etching stopper when etching the target layer 20 a , at least one surface 10 a thereof.

[0099] The processed layer 20a is a layer that is processed by etching to form a concave-convex structure layer 20 having convex portions and concave portions along the concave-convex pattern of the pattern master 1. The processed layer 20a is preferably made of a material that has a higher etching rate than the first concave-convex structure layer 26 made of aluminum oxide and is easily etched. If the etching selectivity of the processed layer 20a relative to the first concave-convex structure layer 26 is high, after the processed layer 20a is exposed to the concave portion of the first concave-convex structure layer 26, the etching of the processed layer 20a proceeds faster than the etching of the first concave-convex structure layer 26. As a result, the processed layer 20a can be processed into a second concave-convex structure layer 20 having a concave-convex shape with a height difference greater than that of the first concave-convex structure layer 26.

[0100] In order to suppress shape degradation caused by side etching, the etching step is preferably performed by anisotropic etching in which an energy beam is irradiated from the surface side of the fine concavo-convex structure. Examples of such etching include reactive ion etching and reactive ion beam etching.

[0101] As the etching gas G, one or more selected from argon (Ar), oxygen (O2), nitrogen (N2), difluoromethane (CH2F2), trifluoromethane (CHF3), tetrafluoromethane (CF4), octafluorocyclobutane (C4H8), sulfur hexafluoride (SF6), carbon monoxide (CO), carbon dioxide (CO2), and chlorine (Cl2) can be used. In particular, the etching gas preferably contains halogen atoms such as fluorine, chlorine, bromine, iodine, and astatine, with fluorine atoms being particularly preferred. The pressure within the apparatus during etching is preferably 0.5 Pa or higher.

[0102] In the etching process, the etching after the processed layer 20a is exposed to the concave portion of the first concave-convex structure layer 26 made of aluminum oxide hydrate is preferably carried out under the condition of Rw>Ra>Rs, with the etching rate of the first concave-convex structure layer 26 being set to Ra, the etching rate of the processed layer being set to Rw, and the etching rate of one surface of the substrate being set to Rs.

[0103] If the etching rate Rw of the processed layer 20a is greater than the etching rate Ra of the first concave-convex structure layer 26, the etching of the processed layer 20a exposed to the concave portion of the first concave-convex structure layer 26 proceeds faster than the etching of the first concave-convex structure layer 26. As a result, the processed layer 20a can be processed into the second concave-convex structure layer 20 having concave-convex portions with a greater height difference than that of the first concave-convex structure layer 26.

[0104] The first concave-convex structure layer 26 made of aluminum oxide hydrate has uneven concavities and convexities, and the height of the convex parts and the depth of the concave parts are uneven and differ from one convex part to another. Therefore, the time from the start of etching to the exposure of the processed layer 20a to each concave part of the first concave-convex structure layer 26 is different. That is, the moment of starting etching depends on the shape of the first concave-convex structure layer 26 and varies according to the position of the surface of the processed layer 20a. Therefore, when one surface 10a of the substrate 10 is exposed to the bottom of the concave part at the position where etching starts early on the processed layer 20a, a situation occurs in which the bottom of the concave part formed at other positions of the processed layer 20a does not reach one surface 10a of the substrate 10.

[0105] However, since the etching rate Rs of the one surface 10a of the substrate 10 is lower than the etching rate Ra of the processed layer 20a, the progress of etching in the one surface 10a is slowed down when the one surface 10a of the substrate 10 is exposed from the recessed portion formed in the processed layer 20a by etching. Although the one surface 10a of the substrate 10 is also slightly etched, since the etching rate of the processed layer 20a is higher than the etching rate of the substrate 10, the etching of the recessed portion in the processed layer 20a that does not reach the one surface 10a of the substrate 10 progresses more rapidly.

[0106] In the absence of a surface that functions as an etching stop layer, if the first concave-convex structure layer having low uniformity of concave-convexity such as gibbsite is used as a mask for etching, the deviation of the position of the bottom point of the concave portion is as large as more than 20nm. However, according to the manufacturing method of the present embodiment, as described above, the first layer 11 constituting one surface 10a of the substrate 10 functions as an etching stop layer, so that the positions of the bottom points of each concave portion 2b of the concave-convex pattern 2 formed by etching can be aligned near one surface 10a of the substrate 10. Therefore, the deviation of the positions of the bottom points of the multiple concave portions 2b of the concave-convex pattern 2 can be set to less than 20nm. In addition, by adjusting the etching conditions, the deviation can also be set to less than 10nm, or less than 5nm. On the other hand, since the influence of the uneven concave-convexity of the first concave-convex structure layer remains on the vertex position of each convex portion of the concave-convex pattern 2, the deviation of the vertex position is generally greater than the deviation of the bottom point position.

[0107] As described above, according to the method for manufacturing a pattern master in the above embodiment, a thin film containing aluminum is formed on a processed layer provided on a substrate surface, and a pattern master having a concave-convex pattern with suppressed bottom height variations of the concave portions can be obtained through very simple steps such as warm water treatment and etching. Therefore, the pattern master can be manufactured with high throughput.

[0108] When heat treatment is performed after etching, it is preferably performed under conditions where the concavo-convex structure layer 20 and the surface 10a having an etch-stop function diffuse into each other. For example, when the concavo-convex structure layer 20 is made of silicon and the etch-stop layer is made of nickel, heat treatment is preferably performed at a temperature of 350°C or higher. This has the advantage of increasing the strength of the interface through interdiffusion between the concavo-convex layer and the etch-stop layer, and thus improving the durability when used as a pattern master.

[0109] "Mold Manufacturing Method"

[0110] A method for manufacturing a mold according to one embodiment of the present invention will now be described. This method uses the aforementioned pattern master to manufacture a mold having a transferred concave-convex pattern on its surface. The method will now be described for manufacturing a flexible mold. Figure 9 It is a diagram showing the steps of a method for manufacturing a flexible mold according to one embodiment.

[0111] First, a pattern master is prepared (step 11). Here, the pattern master 3 of the second embodiment is used. A resin composition layer 30, which serves as a raw material for a flexible mold, is formed on the concave-convex pattern 2 of the pattern master 3 (step 12). For example, a UV-curable resin composition is applied to the surface of the concave-convex pattern 2 to form the resin composition layer 30.

[0112] Then, the resin composition is cured to form the resin layer 31 (step 13). When the resin composition is an ultraviolet curing type, it is cured by irradiating ultraviolet rays (UV).

[0113] The resin layer is preferably made of, for example, dimethylpolysiloxane (PDMS). The resin composition is not limited to ultraviolet curing resins, and may be a thermosetting resin. In the case of a thermosetting resin, the resin composition can be cured by heating.

[0114] Next, the resin layer 31 obtained by curing the resin composition is peeled off from the pattern master 3 (step 14). The concave-convex pattern 2 of the pattern master 3 is transferred to one surface of the resin layer 31, forming a transferred concave-convex pattern 32. The resin layer 31 having the transferred concave-convex pattern 32 serves as a flexible mold (hereinafter referred to as the flexible mold 31).

[0115] The transfer convex-concave pattern 32 of the flexible mold 31 is a reverse pattern of the concave-convex pattern 2 of the pattern master 3. In the concave-convex pattern 2 of the pattern master 3, the deviation of the bottom point of the concave portion is suppressed, so the transfer concave-convex pattern 32 as a reverse pattern becomes a deviation α2 of the vertex position of the convex portion 32a is suppressed. Preferably, the deviation α2 of the vertex position is less than 20nm. The deviation α2 is preferably less than 10nm, more preferably less than 5nm. On the other hand, the smaller the deviation β2 of the bottom point position of the concave portion 32b of the transfer concave-convex pattern 32, the more preferred it is, but the deviation β of the vertex position of the convex portion 2a corresponding to the concave-convex pattern 2 of the pattern master 3 (reference Figure 1 . ), sometimes exceeding 5nm.

[0116] As described above, the flexible mold 31 suppresses variations in the apex positions of the convex portions 32a of the concavo-convex pattern 32, resulting in convex portions of uniform height. Therefore, when used as a mold for nanoimprinting, the residual resist film thickness can be made uniform, enabling a good concavo-convex pattern to be formed on the surface of a workpiece.

[0117] The flexible mold 31 can be used to form a concavo-convex structure on the surface of various substrates. For example, it can be used to form a concavo-convex pattern that functions as an anti-reflection structure on the surface of an optical element.

[0118] Furthermore, in the aforementioned method for manufacturing a mold using the pattern master, for example, nickel is electroformed onto the concave-convex pattern of the pattern master to form an electroformed object having a transferred concave-convex pattern of the pattern master, and the electroformed object is then peeled off. A mold made from the electroformed object can also be manufactured. In this case, a mold can be produced in which the positional deviation of the apexes of the transferred concave-convex pattern is small. Therefore, similar to the case of the flexible mold described above, the residual film thickness of the resist can be made uniform, and a good concave-convex pattern can be formed on the surface of the workpiece.

[0119] "Method for producing a substrate having a concavo-convex structure on its surface"

[0120] A method for producing a substrate having a concavo-convex structure on its surface according to one embodiment of the present invention will be described. Figure 10 It is a diagram showing the steps of a method for manufacturing a substrate according to one embodiment.

[0121] First, a flexible mold is produced using the above-mentioned pattern master. The production process of the flexible mold is the same as the production method of the flexible mold in the above-mentioned embodiment. Here, the flexible mold 31 obtained through the above-mentioned production process is used, but a mold produced by electroforming using the pattern master can also be used.

[0122] As the substrate to be processed, a sapphire substrate, various glass substrates, or an optical component such as a lens is preferable.

[0123] For example, an ultraviolet curable resist 50 is applied to one surface of the substrate 40 (step 21 ). The flexible mold 31 is pressed against the resist 50 to press the transferred concave-convex pattern 32 onto the resist 50 (step 22 ).

[0124] Ultraviolet rays are transmitted through the substrate 40 and irradiated onto the resist 50, thereby curing the resist 50 (step 23). The resist 50 is cured to form a resin layer 51 having a second transferred concave-convex pattern 52 on the surface of the first transferred concave-convex pattern 32 of the flexible mold 31.

[0125] The flexible mold 31 is peeled off from the surface of the resin layer 51 (step 24). Thus, a structure is obtained in which the resin layer 51 having the second transferred concavo-convex pattern 52 is provided on the sapphire substrate 40. At this time, since the heights of the convex apexes of the flexible mold 31 are uniform, the thickness of the remaining resist film becomes uniform.

[0126] The second transferred concave-convex pattern 52 of the resin layer 51 is the same concave-convex pattern as the concave-convex pattern 2 of the pattern master 3. Therefore, the variation α3 of the bottom position of the concave portion 52b is suppressed, while the variation β3 of the top position of the convex portion 52a is large. While the magnitude of the variation slightly changes with repeated transfer, the variation α3 of the bottom position is preferably 20 nm or less, more preferably 10 nm or less, and even less than 5 nm. On the other hand, the variation β3 of the top position of the convex portion 52a exceeds 5 nm. The small variation of the bottom position of the concave portion 52b means that the residual resist film thickness is uniform.

[0127] Next, etching is performed using the resin layer 51 as a mask (step 25 ).

[0128] As a pretreatment, the residual film of the resin layer 51 is removed. The resin layer 51 that remains on the substrate 40 from the concave portion 52b of the transferred concave-convex pattern 52 of the resin layer is a residual film. This residual film is removed by etching or ashing to expose the surface of the substrate 40. If there is a deviation in the residual film, it will take time to remove the thick residual film. The shape of the spit portion is flattened and the height is also reduced by the ashing process. As a result, the function as a mask when etching the substrate is reduced. However, in this embodiment, the above-mentioned flexible mold 31 is used, so the residual film thickness is uniform, and the residual film of each concave portion 52b can be well removed with a certain residual film processing time. In order to remove the residual film, oxygen, argon, fluorine-based gas, etc. can be used.

[0129] After the substrate 40 is exposed to the concave portions 52b of the second transferred concave-convex pattern of the resin layer 51, etching is performed using an etching gas having a large etching selectivity ratio for the substrate 40 to the resin layer 51. By this etching, a concave-convex pattern 42 corresponding to the second transferred concave-convex pattern 52 of the resin layer 51 can be formed on the surface of the substrate 40 (step 25).

[0130] In the above manner, the base 41 having a fine concavo-convex pattern on the surface can be produced.

[0131] Example

[0132] Hereinafter, a method for manufacturing a pattern master according to an embodiment of the present invention will be described.

[0133] A laminated body was prepared, comprising a substrate formed of a nickel layer laminated on a silicon wafer, and a silicon layer formed on the nickel layer. The nickel layer constituted the first layer, encompassing one surface of the substrate, and the silicon wafer served as the second layer. Furthermore, the silicon layer formed on the nickel layer served as the processed layer. The nickel layer had a thickness of 20 nm, and the silicon layer had a thickness of 300 nm.

[0134] Then, a 10 nm aluminum film was formed on the surface of the silicon layer by sputtering as a thin film containing aluminum. Next, the laminated body formed with the aluminum film was immersed in warm water at 100°C for 3 minutes and then subjected to warm water treatment to obtain a first concave-convex structure layer made of aluminum oxide hydrate. Then, a reactive ion etching device was used to etch the surface on which the first concave-convex structure layer was formed. Etching was performed until the first concave-convex structure layer was removed. In addition, a mixed gas of SF6 and CHF3 was used as an etching gas.

[0135] By the etching, the first concavo-convex structure layer is removed, and the processed layer is processed into a second concavo-convex structure layer including convex portions and concave portions, thereby obtaining a pattern master having a fine concavo-convex pattern on the surface.

[0136] Figure 11 and Figure 12The SEM images of the surface and cross section of the pattern master disk manufactured by the above manufacturing method are shown. Figure 11 In the surface image shown in , it was observed that the convex parts were white and the concave parts were black, and it was found that a non-uniform concave-convex pattern was formed. Figure 12 It is clear from the cross-sectional image shown in that etching stops in the nickel layer, the bottom point of the concave portion is located on the surface of the nickel layer, and a concave-convex pattern with very small deviation in the bottom point of the concave portion is formed. Figure 12 The image shown in FIG includes a cross section of the sloped sidewall of the concave portion (or convex portion). In this embodiment, a concave-convex pattern with a convex portion height (concave portion depth) of approximately 300 nm was obtained.

[0137] The disclosure of Japanese Patent Application No. 2018-103819 filed on May 30, 2018 is incorporated herein by reference in its entirety.

[0138] All documents, patent documents, and technical standards described in this specification are incorporated herein by reference to the same extent as if each document, patent document, or technical standard was specifically and individually described as being incorporated by reference.

Claims

1. A pattern master having a fine concave-convex pattern on its surface, The pattern master comprises a base and a concavo-convex structure layer, wherein the concavo-convex structure layer is provided on one surface of the base and comprises a plurality of convex portions and a plurality of concave portions along the concavo-convex pattern. At least one surface of the substrate is made of a material having an etching stop function, The base is exposed to the bottom of at least a portion of the concave portions of the concave-convex structure layer, In the concavo-convex pattern, the deviation of the bottom point position of each concave portion of the concavo-convex pattern in the direction perpendicular to the one surface is 20 nm or less, The concavo-convex structure layer is a layer containing 50 atomic % or more of silicon, and the one surface of the substrate is a layer containing nickel as a main component.

2. The pattern master according to claim 1, wherein: The concavo-convex pattern is uneven with an average period of 400 nm or less.

3. The pattern master according to claim 1 or 2, wherein: In the concavo-convex pattern, a deviation in the position of the apex of each convex portion of the concavo-convex pattern in a direction perpendicular to the one surface exceeds 5 nm.

4. The pattern master according to claim 1, wherein: A nickel silicide layer is formed in the interface region between the concavo-convex structure layer and the substrate.

5. The pattern master according to claim 1, wherein: The concavo-convex structure layer is made of polycrystalline or amorphous silicon.

6. The pattern master according to claim 1 or 2, wherein: The base body is composed of a laminated body including: a first layer including the one surface; and a second layer made of a material different from that of the first layer.

7. A method for manufacturing a mold, wherein: Using the pattern master disc according to any one of claims 1 to 6, A mold having a surface thereof having a transferred concavo-convex pattern of the concavo-convex pattern of the pattern master is manufactured.

8. The method for manufacturing a mold according to claim 7, wherein: forming a resin composition layer along the concavo-convex pattern on the surface of the pattern master, curing the resin composition layer to form a resin layer having a transferred concavo-convex pattern of the concavo-convex pattern, The resin layer is peeled off from the pattern master to obtain a flexible mold having the transferred concavo-convex pattern on its surface.

9. A method for manufacturing a substrate having a concavo-convex structure on its surface, wherein: Using the pattern master according to any one of claims 1 to 6, a mold having a first transferred concave-convex pattern on a surface of which the concave-convex pattern of the pattern master is transferred is produced; Apply the resist to one surface of the processed substrate. pressing the first transfer concavo-convex pattern of the mold onto the resist, thereby transferring the first transfer concavo-convex pattern onto the resist to form a second transfer concavo-convex pattern; curing the resist having the second transferred concavo-convex pattern formed thereon to form a second resin layer having the second transferred concavo-convex pattern; The second resin layer having the second transferred concavo-convex pattern is used as a mask, and the second resin layer and the substrate to be processed are etched from the second resin layer side to form a concavo-convex pattern on the surface of the substrate to be processed.

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