Method for manufacturing a structure and structure

Abstract

The present invention provides a method for manufacturing a structure and a structure thereof. On a substrate having a micro-uneven structure with an average period of less than 1 μm, a mask with an opening pattern is formed. The surface of the substrate is etched from the mask side to form a recess corresponding to the opening pattern of the mask, having an opening with an opening period greater than the average period of the micro-uneven structure and a depth of more than twice the unevenness of the micro-uneven structure. The structure is then manufactured by removing the mask.

Description

Technical Field

[0001] This invention relates to a method for manufacturing a structure and the structure itself. Background Technology

[0002] Previously, various methods for forming micro-uneven structures on the surface of a substrate have been studied.

[0003] For example, Japanese Patent No. 5797133 discloses a method for forming a micro-uneven structure on the surface of a substrate by providing a boehm layer with micro-uneven textures on the surface of a substrate and etching the boehm layer as a mask.

[0004] Furthermore, Japanese Patent Application Publication No. 2019-40039 discloses a method for forming a micro-uneven structure on the surface of a substrate by irregularly attaching chromium (Cr) particles to the surface of a substrate and using the irregularly attached Cr particles as a mask for etching.

[0005] On the other hand, an imprinting method is known to form a fine textured structure based on a resin layer on the surface of a substrate by transferring the textured pattern of a mold with a surface having an uneven pattern onto the surface of a substrate. Japanese Patent Application Publication No. 2019-153704 discloses a method for manufacturing an imprinting mold with stepped recesses, which involves repeatedly performing photolithography and etching to produce an imprinting mold with an uneven surface structure.

[0006] In addition, Japanese Patent Application Publication No. 2009-128538 discloses a method for forming micro-scale irregularities on the surface of a substrate after forming micron-scale irregularities on the surface of the substrate, and forming micro-scale irregularities with a period of less than micron-scale on the surface of the irregularities. Summary of the Invention

[0007] The technical problem to be solved by the invention

[0008] Using the methods described in Japanese Patent No. 5797133, Japanese Unexamined Patent Application Publication No. 2019-40039, and Japanese Unexamined Patent Application Publication No. 2019-153704, it is possible to form micro-uneven structures smaller than the micrometer scale on the surface of each substrate. Furthermore, using the method described in Japanese Unexamined Patent Application Publication No. 2009-128538, it is possible to fabricate structures with two different periods of uneven structures.

[0009] The inventors are currently researching the fabrication of a structure in which, when a recess is formed on the surface of a substrate, at least a portion of the substrate surface remaining around the recess has a fine, irregularly shaped texture smaller than the recess itself. However, methods for manufacturing such a structure have been disclosed in Japanese Patent No. 5797133, Japanese Unexamined Patent Application Publication No. 2019-40039, and Japanese Unexamined Patent Application Publication No. 2019-153704. Furthermore, using the method described in Japanese Unexamined Patent Application Publication No. 2009-128538, the same fine irregularly shaped texture is formed not only on the surface of the substrate remaining around the recess, but also on the bottom surface of the recess when it has a bottom.

[0010] The present invention was made in view of the above circumstances, and its object is to provide a method for manufacturing a structure having a micro-unravel structure that is relatively smaller than the recess in at least a portion of the surface of the substrate surrounding the recess when a recess is formed on the surface of the substrate.

[0011] means for solving technical problems

[0012] The manufacturing method of the structure of the present invention includes: a mask forming process, wherein a mask having an opening pattern is formed on the micro-uneven structure of a substrate having a micro-uneven structure with an average period of less than 1 μm on the surface;

[0013] A dry etching process etches the surface of the substrate from the mask side to form a recess that corresponds to the opening pattern of the mask, has an opening with a period greater than the average period of the micro-uneven structure, and has a depth more than twice the unevenness of the micro-uneven structure; and

[0014] The mask removal process removes the mask after the dry etching process.

[0015] In the manufacturing method of the structure of the present invention, the micro-uneven structure is preferably an irregular structure.

[0016] In the manufacturing method of the structure of the present invention, the recess formed in the dry etching process can be a through hole that penetrates the substrate.

[0017] In the manufacturing method of the structure of the present invention, in the dry etching process, a stripe-like groove along the depth direction of the recess can be formed on at least a portion of the inner wall surface of the recess.

[0018] In the manufacturing method of the structure of the present invention, the etching gas used in the dry etching process may contain fluorine-based gas or chlorine-based gas.

[0019] In the manufacturing method of the structure of the present invention, etching gas and etching protective gas can be used alternately in the dry etching process.

[0020] In the manufacturing method of the structure of the present invention, the mask forming process may include a photoresist coating process, a photoresist exposure process, and a development process.

[0021] In the manufacturing method of the structure of the present invention, the mask forming process may include a resin layer coating process and a pattern transfer process to the resin layer.

[0022] In the manufacturing method of the structure of the present invention, the mask removal process may include a dry etching process or a cleaning process using a sulfuric acid-hydrogen peroxide mixture.

[0023] In the manufacturing method of the structure of the present invention, the method includes a micro-uneven structure forming step of forming a micro-uneven structure on the surface of a substrate. The micro-uneven structure forming step includes: forming a thin film containing aluminum on the surface of the substrate; changing the thin film containing aluminum into a micro-uneven layer containing alumina hydrate by hot water treatment; etching the surface of the substrate from the micro-uneven layer side; and removing the micro-uneven layer.

[0024] In the manufacturing method of the structure of the present invention, the substrate is preferably a silicon substrate or a silicon compound substrate.

[0025] The structure of the present invention comprises: a substrate; and a micro-unraveling structure, wherein a recess on the surface of the substrate and at least the periphery of the recess on the surface of the substrate have an average period of less than 1 μm, and the opening of the recess is greater than the average period of the micro-unraveling structure.

[0026] In the structure of the present invention, the micro-uneven structure is preferably an irregular structure.

[0027] Invention Effects

[0028] According to the manufacturing method of the structure of the present invention, it is possible to obtain a structure in which, when a recess is formed on the surface of a substrate, at least a portion of the surface of the substrate surrounding the recess has a fine uneven structure that is relatively smaller than the recess, rather than in the recess itself. Attached Figure Description

[0029] Figure 1 This is a three-dimensional view of the structure of one embodiment.

[0030] Figure 2 yes Figure 1 The cut-off end face of the structure shown is along line II-II.

[0031] Figure 3 It is a three-dimensional drawing of the structure of a design change example.

[0032] Figure 4This is a diagram illustrating the steps of a manufacturing method according to one embodiment.

[0033] Figure 5 This is a diagram illustrating an example of the mask forming process.

[0034] Figure 6 This is another example of the mask forming process.

[0035] Figure 7 This is a diagram showing the inner wall surface of the concave section.

[0036] Figure 8 This is a diagram used to illustrate the etching process.

[0037] Figure 9 This is a diagram used to illustrate the etching process.

[0038] Figure 10 This is a diagram showing the inner wall surface of the concave section.

[0039] Figure 11 This diagram illustrates the manufacturing process of a substrate with a fine, uneven structure.

[0040] Figure 12 This diagram illustrates the process of penetrating a finely textured layer containing alumina hydrate.

[0041] Figure 13 This is a scanning microscope photograph showing a portion of the structure in the embodiment.

[0042] Figure 14 It is magnification Figure 13 A scanning microscope image of a portion of the structure shown.

[0043] Figure 15 It is a further amplification Figure 14 A scanning microscope image of a portion of the structure shown. Detailed Implementation

[0044] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Furthermore, for ease of visual identification, the film thicknesses and their ratios of each layer are appropriately modified in the description, and may not necessarily reflect the actual film thicknesses and ratios. In this specification, the numerical range indicated by “~” refers to the range encompassed by the values ​​recorded before and after “~” as the lower and upper limits.

[0045] The manufacturing method of the structure of the present invention includes: a mask forming step, forming a mask with an opening pattern on a substrate having a fine uneven structure with an average period of less than 1 μm on its surface; a dry etching step, etching the surface of the substrate from the mask side to form an opening corresponding to the opening pattern of the mask, having an opening with a period greater than the average period of the fine uneven structure and a depth more than twice the unevenness of the fine uneven structure; and a mask removal step, removing the mask after the dry etching step.

[0046] First, an example of a structure of the present invention obtained by one embodiment of the manufacturing method of the structure according to the present invention will be described. Figure 1 This is a perspective view of an example of the structure of the present invention obtained by one embodiment of the manufacturing method of the present invention. Figure 2 It means Figure 1 The diagram shows a cut-off end face of a portion of the structure 1. The structure 1 includes a substrate 10 and a recess 21 formed on the surface 10a of the substrate 10. In the structure 1, since the recess 21 is formed on the surface 10a of the substrate 10, the surface 10a of the substrate 10 remains on the protrusion 22 surrounding the recess 21. The structure 1 has a micro-uneven structure 30 on the surface 10a of the substrate 10 remaining as the protrusion 22, which is smaller than the recess 21. The micro-uneven structure is an uneven structure with an average period of less than 1 μm. In the structure 1, the opening of the recess 21 is larger than the average period of the micro-uneven structure 30, and the depth d of the recess 21 is more than twice as deep as the unevenness e of the micro-uneven structure 30. The depth d of the recess 21 is the distance from the top of the protruding part of the micro-uneven structure 30 formed on the protrusion 22 to the bottom surface 21a of the recess 21 when the recess 21 has a bottom. Furthermore, when the recess 21 is a through hole, the depth d of the recess 21 is equal to the thickness of the substrate 10. Thus, when the recess 21 is formed on the surface 10a of the substrate 10, the structure 1 has a fine uneven structure 30 that is relatively smaller than the recess 21 only on the surface 10a of the substrate 10 surrounding the recess 21, and not on the recess 21 itself.

[0047] The micro-convex-concave structure 30 in structure 1 includes multiple concave portions 31 and multiple convex portions 32, and the concave portions and convex portions are arranged in a continuous repeating pattern. The micro-convex-concave structure 30 can be a regularly arranged structure, or it can be like... Figure 2The irregular structure is shown. Here, "irregular structure" means, for example, that at least one of the size, shape, and spacing of the protrusions 32 is irregular, such as being different in size or shape, or having uneven spacing between adjacent protrusions 32. The average period of the micro-protrusion structure 30 is less than 1 μm. Here, the average period of the micro-protrusion structure 30 is the average of the distances between multiple protrusions 32. The distance between protrusions 32 refers to the distance between a single protrusion 32 and the protrusion closest to it, i.e., the distance between the vertices of its two protrusions. Specifically, in a scanning electron microscope (SEM) image of the structure surface, the distances between any 10 protrusions 32 are measured, and the average value of the measured distances is taken as the average period of the micro-protrusion structure 30. The average period of the micro-uneven structure 30 is, for example, several nm to 1 μm, but preferably 10 nm to 800 nm, more preferably 10 nm to 400 nm, and even more preferably 10 nm to 200 nm. Furthermore, the unevenness e of the micro-uneven structure 30 is, for example, several nm to 1 μm, but preferably 10 nm to 800 nm, more preferably 100 nm to 500 nm.

[0048] The size of the recess 21 in structure 1 is larger than the average period of the fine uneven structure 30. For example, the size of the recess 21 can be set to several μm to several tens of μm, and the average period of the fine uneven structure 30 can be set to several nm to several hundred nm. In this way, the size of the recess 21 and the average period of the fine uneven structure 30 can differ by more than one decimal place. Of course, the sizes can also be different within the same decimal place range, such as setting the size of the recess 21 to 500 nm and the average period of the fine uneven structure 30 to 100 nm, or setting the size of the recess 21 to 5 μm and the average period of the fine uneven structure 30 to 1 μm. Here, the size of the recess 21 is defined by the equivalent circle diameter of the opening. Here, the equivalent circle diameter refers to the diameter of a circle with an area equal to the area of ​​the opening.

[0049] On the other hand, the depth d of the recess 21 can be more than twice the unevenness e of the micro-uneven structure 30, but preferably more than five times the unevenness e, and more preferably more than ten times. The depth d of the recess 21 is, for example, 1 μm to several mm.

[0050] In addition, such as Figure 1 The structure 1 shown has multiple recesses 21, but as a structure of the present invention, such as Figure 3 The structure 2 shown can have only one recess 21. Furthermore, it is not necessary to... Figure 1The structure 1 shown has a fine uneven structure 30 covering the entire area of ​​the surface 10a of the substrate 10 surrounding the recess 21, such as... Figure 3 As shown, it is sufficient to have a fine uneven structure 30 on a portion of the surface 10a of the substrate 10 remaining around the recess 21. Figure 3 In the example shown, more specifically, the fine uneven structure is formed only on the periphery of the recess 21. Furthermore, the periphery of the recess 21, as referred to here, is a region having a width of 20% of the size of the recess 21 in the direction surrounding the opening of the recess 21 and away from the edge of the opening.

[0051] In this example, structure 1 can be used as a microplate for use in biochemical analysis or clinical examinations, where the recesses 21 serve as test wells. Alternatively, structure 1 can also be used as a mold when fabricating a structure consisting of multiple protruding structures arranged in a two-dimensional pattern. A curable composition is filled into the recesses 21, and the curable composition is brought into contact with the surface of a separately prepared transfer substrate. The curable composition is then cured in this state. Afterward, a structure consisting of multiple protruding structures can be fabricated by peeling structure 1 from the transfer substrate.

[0052] The micro-unravel structure 30 with an average period of less than 1 μm can have hydrophobic properties. As mentioned above, when a liquid such as a test fluid or a curing composition is injected into the recess 21, the liquid is bounced off the substrate surface adjacent to the recess opening, so it is easy to inject the liquid into the recess 21.

[0053] Next, refer to Figure 4 An embodiment of the manufacturing method of the present invention for manufacturing the above-described structure 1 will be described. Figure 4 This diagram schematically illustrates the manufacturing process. In the manufacturing method of the structure in this embodiment, a mask forming process, a dry etching process, and a mask removal process are sequentially performed on a substrate 10 having a fine uneven structure 30 with an average period of less than 1 μm on its surface 10a.

[0054] First, such as Figure 4 As shown in ST1, a substrate 10 is prepared having a fine uneven structure 30 with an average period of less than 1 μm on its surface 10a. The process for preparing the substrate 10 having the fine uneven structure 30 will be described later.

[0055] Next, as Figure 4 As shown in ST2, in the mask forming process, a mask 42 with an opening pattern 41 is formed on the micro-convex and concave structure 30.

[0056] After that, as Figure 4As shown in ST3, in the dry etching process, a mask 42 formed in the mask forming process is used to perform dry etching on the surface 10a of the substrate 10 using etching gas G1. This dry etching forms a recess 21 on the surface 10a of the substrate 10 corresponding to the opening pattern of the mask 42. When etching from the surface side of the substrate 10 having the micro-uneven structure 30 to form the recess 21, the etching is initially performed in a manner where the uneven shape of the surface of the micro-uneven structure 30 on the substrate surface gradually recedes. Subsequently, as etching proceeds, the unevenness gradually decreases, and the original micro-uneven structure 30 is etched away. Consequently, when a recess with a depth twice the unevenness e of the micro-uneven structure is formed, almost no uneven structure remains on the bottom surface of the recess, thus obtaining a recess without micro-uneven structure on the bottom surface. By setting the depth of the recess to 5 times or more, more preferably 10 times or more, a recess with further improved flatness of the bottom surface is obtained. In addition, "no micro-protrusion structure 30" here means that there is no micro-protrusion structure in which the concave and convex parts are repeatedly arranged at the same period as the micro-protrusion structure 30 formed on the surface 10a, which allows one or more independent micro-protrusions to be formed on the bottom surface 21a in the dry etching process.

[0057] Finally, as Figure 4 As shown in ST4, in the mask removal process, the mask 42 remaining after the dry etching process is removed by spraying stripping liquid 60 onto the substrate 10.

[0058] After the above procedures, it is possible to obtain Figure 4 Structure 1 is shown in ST5.

[0059] As described above, in the manufacturing method of the structure in this embodiment, the above-described mask formation process, dry etching process, and mask removal process are performed on a substrate 10 having a fine uneven structure 30 with an average period of less than 1 μm on its surface 10a. With this manufacturing method, when a recess 21 is formed on the surface 10a of the substrate 10, a structure 1 can be obtained where at least a portion of the surface 10a of the substrate 10 surrounding the recess 21 has a fine uneven structure 30 that is relatively smaller than the recess 21, rather than being located on the recess 21 itself.

[0060] The following is a detailed explanation of each process.

[0061] There are no particular limitations on the material of the substrate 10; for example, silicon or silicon compounds can be used. Silicon or silicon compounds are preferred because the etch selectivity is easy to control. Examples of silicon compounds include silicon oxide and silicon nitride. Specifically, silicon wafers and quartz glass can be used as the substrate 10.

[0062] <Mask Forming Process>

[0063] The method for forming the mask 42 and the mask material in the mask forming process are not particularly limited, but it is preferable that the mask 42 is made of an organic material. If an organic material is used, a mask 42 with the desired opening pattern can be formed in a simple way. Hereinafter, the method for forming the mask 42 with an organic material will be briefly described.

[0064] In one example, the mask forming process includes a photoresist coating process, a photoresist exposure process, and a photoresist development process. For example... Figure 5 As shown in ST21, a positive photoresist 40 is coated on the surface 10a of the substrate 10. Figure 5 As shown in ST22, an exposure mask 47 is disposed on the photoresist 40, and light (e.g., laser L) is irradiated onto the portion 40a forming the opening of the photoresist 40 to expose it. Subsequently, by developing the photoresist 40, only the exposed portion 40a of the photoresist 40 can be dissolved to form an opening, thereby forming a mask 42 with an opening pattern 41 (ST2).

[0065] Alternatively, in another example of the mask forming process, a resin layer coating process and a process of transferring the resin layer to the raised / undone pattern may also be included. For example... Figure 6 As shown in ST23, a resin layer 46, for example, composed of a photocurable resin composition, is coated on the surface 10a of the substrate 10. Then, as... Figure 6 As shown in ST24, an embossing mold 48 with an embossed pattern corresponding to the opening pattern 41 of the mask 42 to be formed is used to press the embossed pattern surface onto the resin layer 46 to transfer the embossed pattern onto the resin layer 46. Then, as... Figure 6 As shown in ST25, after the resin layer 46 is cured by irradiating the resin layer 46 with ultraviolet light 49, a mask 42 with an opening pattern 41 on the substrate 10 can be obtained by peeling off the imprinting mold 48.

[0066] <Dry Etching Process>

[0067] In the dry etching process, reactive ion etching is preferred. To ensure that the etching rate relative to the substrate 10 is greater than the etching rate relative to the mask 42, an etching gas G1 with good etching efficiency relative to the substrate 10 is preferably used. Specifically, when silicon is used as the substrate, fluorine-based or chlorine-based gases can be used, for example. As a fluorine-based gas, trifluoromethane (CFH3) or sulfur hexafluoride (SF6) can be used, for example, and as a chlorine-based gas, chlorine (Cl2) can be used, for example.

[0068] When forming the recess 21 using dry etching on a substrate 10 having a fine uneven structure 30 on surface 10a, such as Figure 7As shown, a striped groove 24 corresponding to the concavity and convexity of the micro-convex and concave structure 30 is formed on the inner wall surface 21b of the recess 21. Figure 7 It is a cross-sectional view of a portion including a recess 21 of the structure 1. A groove 24 is formed on the inner wall surface 21b of the recess 21, having a width that approximately corresponds to the width of the protrusions 32 of the micro-convex structure 30 or the spacing of the protrusions 32, and is striped along the depth direction of the recess 21. Figure 7 The portion indicated by the gray shading line is the groove 24, which is recessed relative to the portion indicated by white. The width of the striped groove 24 is approximately corresponding to the width of the protrusion 32 or the spacing of the protrusion 32 on the surface side in the depth direction, but the width gradually narrows on the deep side.

[0069] In short, forming as Figure 7 The striped grooves 24 are due to the interaction between the multiple protrusions 32 of the micro-convex structure 30 and the mask 42. (See reference) Figure 8 and Figure 9 For the formation of Figure 7 The principle of the striped groove 24 will be explained. Figure 8 and Figure 9 In the middle, the left figure shows the state where the mask 42 is formed on the micro-uneven structure 30 on the surface of the substrate before the dry etching process, and the right figure shows the state after the dry etching process when the mask is removed. In each figure, the upper figure is a plan view of the structure viewed from above the protrusion 32, and the lower figure is a side view.

[0070] first, Figure 8 An example illustrates a situation where, when a mask 42 is formed on the substrate 10, near the boundary B corresponding to the inner wall surface 42a of the opening portion of the mask 42, the plurality of protrusions 32 of the micro-unraveling structure 30 are not entirely covered by the mask 42. That is, in Figure 8 In the left figure, the inner wall surface 42a of the opening portion of the mask 42 is formed in a way that the hem portion of the protrusion 32 is formed in a roundabout manner.

[0071] like Figure 8 As shown in the upper left figure, in the inner wall surface 42a of the mask 42, the portion of the meandering protrusion 32 is recessed further into the inner side of the mask 42 than the portion between adjacent protrusions 32. If etching is performed in this state to form the recess 21, near boundary B, the portion of the protrusion 32 not covered by the mask 42 is removed by etching along the depth direction. On the other hand, the portion protected by the mask 42 is not removed. Therefore, near boundary B, the portions corresponding to the plurality of protrusions 32 are etched in the depth direction, forming a stripe-like groove 24 on the inner wall surface 21b of the recess 21 with a width approximately corresponding to the width of the protrusion 32 and along the depth direction. Thus, in Figure 8In the example, the inner wall surface 42a of the mask 42 is formed by a series of protrusions 32, so that the groove 24 is formed on the inner wall surface 21b of the recess 21 by the difference in erosion rate between the part covered by the mask 42 and the part with protrusions 32 not covered by the mask 42.

[0072] Figure 9 An example illustrates a situation where, when a mask 42 is formed on a substrate 10, near the boundary B corresponding to the inner wall surface 42a of the opening portion of the mask 42, half of the plurality of protrusions 32 of the micro-unraveling structure 30 are covered by the mask 42. That is, as... Figure 9 As shown at boundary B in the left figure, the inner wall surface 42a of the opening portion of the mask 42 appears straight when viewed from above. In this case, a portion of the conical protrusion 32, or half of the protrusion 32 in this example, is covered by the mask 42. On the other hand, the remaining portion of the protrusion 32 becomes the exposed portion not covered by the mask 42. In this state, if etching is performed to form the recess 21, near boundary B, the portion corresponding to the exposed portion of the protrusion 32 not covered by the mask 42 is etched first from the protrusion 32. After the protrusion 32 is etched, etching in the depth direction, which helps to form the recess 21, begins. On the other hand, the portion without the protrusion 32 begins etching in the depth direction, which helps to form the recess 21, after etching begins. Thus, near boundary B, the etch-based etching proceeds faster in the portion without the protrusion 32 compared to the portion with the protrusion 32. Therefore, the parts with a fast erosion rate form grooves 24 on the inner wall surface 21b of the recess 21, with a width approximately corresponding to the spacing of the protrusions 32, and running along the depth direction. Thus, in Figure 9 In the example, near the boundary B corresponding to the inner wall surface 42a of the mask 42, a groove 24 is formed on the inner wall surface 21b of the recess 21 by the difference in erosion rate between the portion with the protrusion 32 and the portion without the protrusion 32.

[0073] As shown above, a shape is formed on the inner wall surface 21b of the recess 21. Figure 7 The reason for the striped grooves 24 is the interaction between the multiple protrusions 32 of the micro-convex structure 30 and the mask 42.

[0074] Considering the boundary B corresponding to the inner wall surface 42a of the actual mask 42, the mixture exists as follows: Figure 8 The state shown is where no mask 42 is formed on the protrusion 32 of the micro-uneven structure 30, and as shown in the figure. Figure 9 A portion of the protrusion 32 is covered by the mask 42. Figure 8 Examples and Figure 9In any of the examples, based on the interaction between the plurality of protrusions 32 of the micro-convex-concave structure 30 and the mask 42, a plurality of striped grooves 24 along the depth direction are formed on the inner wall surface 21b of the recess 21. Therefore, in this manufacturing process, as described above, the width of the striped grooves 24 formed on the inner wall surface 21b and the formation interval of the grooves 24 are changed according to the width of the protrusions 32 of the micro-convex-concave structure 30 and the interval of the protrusions 32.

[0075] Furthermore, as a method for forming high aspect ratio recesses, etching can be performed using the so-called Bosh process, which typically alternates between etching gas and etching shielding gas. The Bosh process can effectively form high aspect ratio recesses. Additionally, it is known that when etching recesses using the Bosh process, a structure called scallops is formed on the inner wall surface of the recess, consisting of repeating stripe-like grooves extending in a direction approximately perpendicular to the depth direction.

[0076] By utilizing Bosch technology, in addition to Figure 7 In addition to the striped groove 24 (hereinafter referred to as the first groove 24) shown in the depth direction, striped grooves 26 (hereinafter referred to as the second groove 26) that intersect the depth direction approximately perpendicularly can also be formed. That is, as shown... Figure 10 As shown, a grid-like interlocking surface is formed on the inner wall surface 21b of the recess 21, consisting of the first groove 24 (represented by a gray shading line) and the second groove 26 (represented by a stripe-like shading line at the lower right). In this case, Figure 10 In the middle, in the part where the gray shading line overlaps with the lower right slanted shading line, the first groove 24 and the second groove 26 overlap, forming a deeper groove by adding the depths of their respective grooves, thus forming a complex shape of concavity and convexity.

[0077] <Mask Removal Process>

[0078] Mask removal preferably includes a dry etching process, or a cleaning process using a mixture of sulfuric acid (H2SO4) and hydrogen peroxide (H2O2), i.e., a sulfuric acid-hydrogen peroxide solution, such as the SH-303 manufactured by Kanto Chemical Co., Inc.

[0079] The dry etching process for mask removal is, for example, a process that switches to an etching gas with high etchability relative to the mask after the aforementioned dry etching process for recess formation. Regarding mask removal based on dry etching, it is possible to switch from a process that etches the substrate simply by changing the gas to a mask removal process, resulting in high work efficiency.

[0080] Furthermore, if a cleaning process using a sulfuric acid-hydrogen peroxide mixture is employed, the mask 42 remaining after the dry etching process used to form the aforementioned recesses can be effectively removed with high cleaning power.

[0081] <Process for preparing a substrate with a fine textured surface>

[0082] In the above manufacturing method, the step of preparing a substrate having the micro-uneven structure 30 may also include a micro-uneven structure forming step of forming the micro-uneven structure 30 on the surface of a flat substrate 9. As an example, the micro-uneven structure forming step includes: forming a thin film containing aluminum on the surface of the substrate; transforming the aluminum-containing thin film into a micro-uneven layer containing aluminum oxide hydrate by hot water treatment; etching the surface of the substrate from the micro-uneven layer side; and removing the micro-uneven layer. References are provided below. Figure 11 The steps in this example will be explained.

[0083] like Figure 11 As shown in ST12, firstly, an aluminum-containing thin film 50 (hereinafter referred to as Al-containing thin film 50) is formed on the surface of the substrate 9 to be processed.

[0084] The Al-containing thin film 50 is, for example, a film composed of any one of aluminum, aluminum oxide, aluminum nitride, and aluminum alloys, but any material that can be transformed into a fine, uneven layer containing alumina hydrates such as boehmite through a subsequent warm water treatment process is acceptable. Furthermore, "aluminum alloy" refers to a compound or solid solution containing at least one of the elements silicon (Si), iron (Fe), copper (Cu), manganese (Mn), magnesium (Mg), zinc (Zn), chromium (Cr), titanium (Ti), and nickel (Ni), with aluminum as the main component. From the viewpoint of forming an uneven structure, the composition ratio of aluminum to all metallic elements in the Al-containing thin film 50 is preferably 80 mol% or more.

[0085] The thickness of the Al-containing thin film 50 can be set according to the desired thickness of the fine uneven layer obtained in the subsequent process. For example, the thickness of the Al-containing thin film 50 is 0.5 to 60 nm, preferably 2 to 40 nm, and particularly preferably 5 to 20 nm.

[0086] There are no particular limitations on the method for forming the Al-containing thin film 50. For example, conventional film formation methods such as resistance heating evaporation, electron beam evaporation, and sputtering can be used. Furthermore, as a method for forming the Al-containing thin film 50 on the recess 21, an electrodeposition bath can be used.

[0087] Next, as Figure 11 As shown in ST13, in the warm water treatment process, the Al-containing thin film 50 is subjected to warm water treatment. For example, as... Figure 11As shown in ST13, pure water 56 in container 55 is heated to warm water using hot plate 58, and the substrate 9 to be processed, on which an Al thin film 50 is formed, is then immersed entirely in it. Through warm water treatment, as... Figure 11 As shown in ST14, the Al-containing thin film 50 can be transformed into a finely textured layer 52 containing alumina hydrate. This finely textured layer 52 has multiple protrusions and multiple recesses formed in an irregular shape and configuration. The size of the protrusions and the average distance between the protrusions (i.e., the average period of the protrusions) of the textured layer can be controlled by the material of the Al-containing thin film 50, the formation thickness, and the warm water treatment conditions, but its average period is approximately less than 1 μm.

[0088] The "warm water treatment" in the warm water treatment process refers to the treatment of applying warm water to an aluminum-containing thin film. Examples of warm water treatment include immersing a laminate containing an aluminum-containing thin film 50 in room temperature water and then boiling the water, immersing the laminate in warm water maintained at a high temperature, or exposing it to high-temperature steam. As described, in this embodiment, pure water 56 in container 55 is heated to warm water using a hot plate 58, and the substrate 10 is immersed in it. The immersion time and the temperature of the warm water are appropriately set according to the desired uneven structure. A standard time is 1 minute or more, and more preferably 3 minutes or more and 15 minutes or less. The temperature of the warm water is preferably 60°C or higher, and more preferably higher than 90°C. There is a tendency that the higher the temperature, the shorter the treatment time. For example, when a 10 nm thick aluminum-containing film is boiled in warm water at 100 °C for 3 minutes, a randomly configured uneven structure with a distance of 50–300 nm between the protrusions and a height of 50–100 nm between the protrusions can be obtained.

[0089] In addition, such as Figure 11 As shown in ST15, by etching the surface 10a of the substrate 9, on which the micro-uneven layer 52 containing alumina hydrate is formed, using etching gas G2, as shown in ST1, a micro-uneven structure 30 can be formed on the surface 10a of the substrate 10. When etching is performed from the surface of the micro-uneven layer 52, the uneven shape of the surface of the micro-uneven layer 52 gradually recedes through etching-based dissolution erosion. The dissolution erosion acts on the surface 10a of the substrate 10 to reflect the uneven shape of the micro-uneven layer 52. Thus, a micro-uneven structure 30 reflecting the shape of the micro-uneven layer 52 is formed on the surface 10a of the substrate. In addition, the uneven shape of the micro-uneven layer 52 being "reflected" means that the positional accuracy of the uneven part or the concave part corresponding to the uneven shape is similar to a certain undulation, without the need for so-called transfer.

[0090] In this etching process, reactive ion etching or reactive ion beam etching is preferably used, for example. Etching is preferably performed under conditions where the etching rate of the substrate 10 is greater than the etching rate of the micro-uneven layer 52. For example, fluorine-based or chlorine-based gases, which are the same as etching gas G1, can be used as the etching gas G2, which has good etching efficiency relative to the substrate 10.

[0091] Furthermore, it is preferable to perform a penetration treatment of the micro-unraveling layer 52 before the etching process on the substrate surface 10a, until at least a portion of the surface of the substrate 9 being processed is exposed. Specifically, as... Figure 12 As shown, after the micro-uneven layer 52 is formed (ST14), the micro-uneven layer 52 is etched (ST40) to expose the bottom surface 21a of the recess 21 in at least a portion of the recess of the micro-uneven layer 52 (ST41). In this penetration process, an etching gas G3 with good etching efficiency relative to alumina hydrate is used to effectively etch the micro-uneven layer 52. For example, a gas containing argon (Ar) and trifluoromethane (CHF3) is used as the etching gas G3. Subsequently, in order to form the micro-uneven structure 30 on the surface of the substrate 9 being processed, as... Figure 12 As shown in ST42, a substrate 10 (ST1) having a micro-uneven structure 30 on surface 10a is obtained by etching relative to the surface of the substrate 9 using etching gas G2 from the micro-uneven layer 52 side. By performing a through-through process, the etching time of the substrate can be significantly shortened, thus improving the manufacturing efficiency of the entire manufacturing process.

[0092] The mask removal process preferably includes a cleaning process using a sulfuric acid-hydrogen peroxide mixture. Using the sulfuric acid-hydrogen peroxide mixture effectively removes the fine uneven layer 52 remaining after the etching process.

[0093] Furthermore, the method for fabricating a substrate with a micro-uneven surface is not limited to the above. A substrate with a micro-uneven surface can also be fabricated by irregularly attaching particles such as Cr to a flat substrate and using the particles as a mask to etch the substrate surface. Alternatively, a resin layer can be formed on the surface of the substrate, and a molded pattern with an uneven pattern can be pressed onto the resin layer to transfer the pattern, thereby forming a resin-layer-based mask on the substrate surface. This resin layer can then be used as a mask to etch the surface of the substrate, thus fabricating a substrate with a micro-uneven surface. However, as described above, the method for forming a micro-uneven structure containing alumina hydrate allows for the simple fabrication of irregular micro-uneven surfaces smaller than 1 μm, thus enabling the efficient fabrication of substrates with micro-uneven structures.

[0094] The above are as follows Figure 1In the structure 1 shown, the recess 21 is a bottomed recess, but in the structure of the present invention, the recess can be a through hole. That is, in the manufacturing method of the present invention, during the dry etching process that forms the recess, etching can be performed until the recess is through. A structure with a substrate having multiple through holes and a surface having a fine uneven structure can be used, for example, as an optical component that emits incident light as parallel light. When used as such an optical component, the anti-reflection function based on the surface's fine uneven structure can prevent the reflection of light incident on parts other than the through holes. Furthermore, by providing a grid-like groove on the inner wall surface of the through hole, which is a combination of striped grooves along the depth direction, striped grooves along a direction intersecting the depth direction, or striped grooves along the depth direction and striped grooves along a direction intersecting the depth direction, the reflection of the oblique light component incident on the inner wall surface in the light incident on the through hole can be suppressed, thereby improving the accuracy of parallel light conversion.

[0095] Furthermore, in a structure with through-holes, by fixing a trapping substance within the through-holes and circulating the test fluid containing the test substance from one opening to another, it can be used as a biochemical chip for binding the test substance with the trapping substance and detecting biochemical reactions. By fixing different trapping substances in multiple through-holes, it can also be used as a biochemical chip for simultaneously detecting multiple substances. Additionally, in this case, such as... Figure 7 or Figure 10 As shown, if the inner wall of the concave part has multiple grooves, the adhesion of the captured substance can be improved, thereby increasing the detection sensitivity.

[0096] Example

[0097] A structural component was fabricated using an embodiment of the manufacturing method for the structure described above. The specific manufacturing method is as follows.

[0098] Using a silicon wafer as the substrate, a substrate with a finely textured surface was first fabricated. Specifically, an aluminum thin film was first formed on the surface of the substrate by sputtering. The thickness of the aluminum thin film was set to 10 nm. Then, as a warm water treatment, the substrate was immersed in boiling pure water for 3 minutes, transforming the aluminum thin film into a finely textured layer containing aluminum oxide hydrate. Next, a penetration treatment was performed on the surface of the finely textured layer using a mixture of Ar and CHF3 gases, followed by reactive ion etching using a mixture of SF6 and CHF3 gases, to form a finely textured surface on the substrate. Thus, a substrate with a finely textured surface was obtained.

[0099] Next, a photoresist is coated onto the micro-uneven structure of a substrate with a fine surface texture. An exposure mask with predetermined openings is then placed on the photoresist for laser exposure. Further, a mask with an opening pattern is formed through a development process. Then, using this mask, reactive ion etching is performed using a mixture of SF6 and CHF3 gases as the etching gas, forming recesses on the substrate surface.

[0100] Finally, a mixture of sulfuric acid and hydrogen peroxide was used for cleaning to remove the mask.

[0101] Figure 12 This is an SEM image representing a portion of the structure created above. For example... Figure 12 As shown, the structure has multiple recesses on the surface of the substrate. The opening of each recess is a square with a side of 20 μm, and the depth of the recess is 10 μm.

[0102] Figure 13 It's enlarged. Figure 12 SEM image of the inner wall of one of the concave parts. Figure 14 It has been further amplified. Figure 13 SEM image of the upper part of the inner wall surface. From Figure 13 and 14 It can be seen that a fine uneven structure is formed on the surface of the substrate. Furthermore, Figure 13 The dark-colored portion observed is the bottom surface of the recess, on which no fine uneven structure as formed on the surface of the substrate is formed. Furthermore, it is known that striped grooves formed according to the fine uneven structure of the surface are formed on the wall surface of the recess.

[0103] Thus, according to one embodiment of the above-described method for manufacturing a structure, a structure can be manufactured that has a fine uneven structure with an average period of less than 1 μm formed only on the surface of a substrate having a relatively large recess, and at least on the periphery of the recess, while the bottom surface of the recess does not have a fine uneven structure.

[0104] All disclosures of Japanese Patent Application No. 2020-055019, filed on March 25, 2020, are incorporated herein by reference.

[0105] All documents, patent applications and technical standards described herein are incorporated herein by reference to the same extent that each individual document, patent application or technical standard is specifically and individually described by reference.

Claims

1. A method for manufacturing a structure having a recess, comprising: The mask forming process forms a mask with an opening pattern on the micro-uneven structure of a substrate having a micro-uneven structure on its surface, wherein the micro-uneven structure has an average period of less than 1 μm. A dry etching process etches the surface of the substrate from the mask side to form a recess corresponding to the opening pattern of the mask. This recess has an opening with a period greater than the average period of the micro-unravel structure and a depth more than twice the unevenness of the micro-unravel structure. The mask removal process involves removing the mask after the dry etching process. The micro-uneven structure is an irregular structure, and is formed at least around the periphery of the recess. The periphery refers to a region with a width of 20% of the size of the recess in a direction surrounding the opening of the recess and away from the edge of the opening. In the dry etching process, a stripe-like groove is formed along the depth direction of the recess on the inner wall surface of the recess, corresponding to the concavity and convexity of the irregular micro-concavity structure.

2. The method for manufacturing a structure with a recess according to claim 1, wherein, The recess formed in the dry etching process is a through hole that penetrates the substrate.

3. The method for manufacturing a structure with a recess according to claim 1 or 2, wherein, The etching gas used in the dry etching process contains fluorine-based or chlorine-based gases.

4. The method for manufacturing a structure with a recess according to claim 1 or 2, wherein, In the dry etching process, etching gas and etching protective gas are used alternately.

5. The method for manufacturing a structure with a recess according to claim 1 or 2, wherein, The mask forming process includes: a photoresist coating process, an exposure process for the photoresist, and a development process.

6. The method for manufacturing a structure having a recess according to claim 1 or 2, wherein, The mask forming process includes: a resin layer coating process and a pattern transfer process for transferring a pattern onto the resin layer.

7. The method for manufacturing a structure having a recess according to claim 1 or 2, wherein, The mask removal process includes either a dry etching process or a cleaning process using a sulfuric acid-hydrogen peroxide mixture.

8. The method for producing a structure having a recess according to claim 1 or 2, comprising: The process of forming the micro-uneven structure on the surface of the substrate. The process for forming the micro-uneven structure includes: The process of forming a thin film containing aluminum on the surface of the substrate; The process of transforming the aluminum-containing film into a fine, uneven layer containing aluminum oxide hydrate through warm water treatment. The process of etching the surface of the substrate from the side of the micro-uneven layer; and The process of removing the micro-uneven layer.

9. The method for manufacturing a structure having a recess according to claim 1 or 2, wherein, The substrate is a silicon substrate or a silicon compound substrate.

10. A structure having a recess, comprising: substrate; A recess is formed on the surface of the substrate; and A fine uneven structure with an average period of less than 1 μm is provided, wherein the fine uneven structure is formed only on the surface of the substrate and at least at the periphery of the recesses in the surface, the periphery being a region having a width of 20% of the size of the recess in a direction surrounding the opening of the recess and away from the edge of the opening. The opening of the recess is larger than the average period of the micro-convex and concave structure. The micro-uneven structure is an irregular structure. The recess has striped grooves on its inner wall surface that correspond to the irregular structure of the micro-convex and concave structure and run along the depth direction.

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