A method of transferring a nanoforest structure

Abstract

The present application relates to a kind of methods for transferring nanoforest structure, which utilizes the controllable adhesion of releasable adhesive tape and the principle of magnetic field adsorption, successfully transfers nanoforest structure from original substrate to target substrate, as the variety of target substrate, thus expands the application scenario of nanoforest structure, and at the same time improves the reliability of nanoforest structure when applied.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of functional nanomaterials, and particularly to a method for transferring a nano-forest structure. BACKGROUND

[0002] Existing nano-forest structures are generally formed by relatively complex growth processes or etching processes, and thus have high requirements for substrates. At present, they can only be prepared on a limited number of substrates, and cannot meet the demand for preparing nano-forest structures on some substrates (such as metal material substrates) in actual applications, greatly limiting the application scenarios of nano-forest structures. In addition, in the process of preparing nano-forest structures, the substrates will be damaged to some extent, which will in turn bring the risk of reduced reliability for the subsequent application of nano-forest structures.

[0003] Therefore, it is necessary to develop a method for transferring a nano-forest structure from an original substrate to a new substrate, so as to achieve the purpose of forming a nano-forest structure on the new substrate, and improve the reliability of the nano-forest structure in application. SUMMARY

[0004] The purpose of the present application is to overcome the shortcomings of the prior art and provide a method for transferring a nano-forest structure. The method successfully transfers a nano-forest structure from an original substrate to a target substrate by using the controllable adhesion of a releasable adhesive tape and the principle of magnetic field adsorption. Since the target substrate is diversified, the method expands the application scenarios of the nano-forest structure and improves the reliability of the nano-forest structure in application.

[0005] In order to achieve the above purpose, the present application provides the following technical solutions.

[0006] A method for transferring a nano-forest structure, comprising the following steps:

[0007] Providing an original substrate, the upper surface of the original substrate being provided with a nano-forest structure formed by photoresist;

[0008] Forming a magnetic metal layer on the upper surface of the nano-forest structure;

[0009] Attaching a releasable adhesive tape to the upper surface of the magnetic metal layer, and separating the nano-forest structure from the original substrate, so as to obtain a nano-forest structure attached to the releasable adhesive tape;

[0010] Processing the releasable adhesive tape, so as to release the nano-forest structure with the magnetic metal layer on the upper surface;

[0011] Providing a target substrate; and

[0012] applying a magnetic field to a first surface of the target substrate, thereby adsorbing the nano-forest structure having the magnetic metal layer on the upper surface to a second surface of the target substrate to complete the transfer.

[0013] Compared with the prior art, the present application has the following advantages:

[0014] 1. The present application provides a method for transferring nano-forest structure, which uses the controllable adhesion of releasable adhesive tape and the principle of magnetic adsorption to successfully transfer the nano-forest structure from the original substrate to the target substrate. Since the target substrate is diverse, the application scenario of the nano-forest structure is expanded, and the reliability of the nano-forest structure in application is improved.

[0015] 2. The adsorption process of the present application is carried out in a liquid such as water. By adjusting the included angle a between the target substrate and the horizontal plane, and under the action of magnetic force, gravity and the resistance and torque of water, the nano-forest structure can be arranged at a specific angle on the target substrate, greatly expanding the application field of the nano-forest structure. The nano-forest structure prepared by etching method or chemical synthesis growth method in the prior art is usually perpendicular to the substrate, and the inclination angle between the nano-forest structure and the substrate cannot be adjusted. BRIEF DESCRIPTION OF DRAWINGS

[0016] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The accompanying drawings are included to provide a description of the preferred embodiments and are not intended to limit the scope of the present application. Moreover, the same reference numerals are used throughout the same figures. In the drawings:

[0017] Figures 1-10 Structure schematic diagram obtained in each step of the transfer method provided by the embodiments of the present application.

[0018] REFERENCE NUMERALS

[0019] 100 is the original substrate, 200 is the nano-forest structure, 201 is the nanocolumn, 300 is the magnetic metal layer, 400 is the heat-releasing adhesive tape, 500 is water, 600 is the target substrate, 700 is the magnetic substrate, and 800 is the flexible adhesive tape. DETAILED DESCRIPTION

[0020] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present disclosure. In addition, in the following description, descriptions of well-known structures and techniques are omitted to avoid unnecessary confusion of the concept of the present disclosure.

[0021] Various structural diagrams according to embodiments of the present disclosure are shown in the accompanying drawings. These diagrams are not drawn to scale, in which certain details are shown in a somewhat exaggerated manner for purposes of clarity and understanding, and certain other details are omitted. The shapes of various regions, layers, and the relative sizes and positional relationships among them shown in the drawings are merely exemplary, and in actuality can be deviated due to manufacturing tolerances or technical limitations, and regions / layers with different shapes, sizes, and relative positions can be additionally designed according to actual needs by those skilled in the art.

[0022] In the context of the present disclosure, when a layer / element is referred to as being located "on" another layer / element, the layer / element can be directly located on the other layer / element, or there can be an intervening layer / element therebetween. In addition, if a layer / element is located "on" another layer / element in one orientation, it can be located "under" the other layer / element when the orientation is reversed.

[0023] Since existing nano-forest structures are generally formed by relatively complex growth or etching processes, the substrates have relatively high requirements, and currently only a limited number of substrates can be used. In order to be able to form nano-forest structures on more types of substrates, the present application proposes a method for transferring a nano-forest structure, which comprises the following steps.

[0024] First, an original substrate is provided, and the upper surface of the original substrate is provided with a nano-forest structure formed by photoresist.

[0025] The original substrate of the present application can be a silicon-based original substrate, such as single crystal silicon, polycrystalline silicon, or amorphous silicon; glass; quartz or sapphire. The present application does not have special restrictions on the original substrate, and conventional original substrates suitable for microfabrication processes can be used.

[0026] Preferably, the nano-forest structure comprises a plurality of nanocolumns. The height of the nanocolumns can be 1-5 μm, preferably 1.5-3.5 μm; the diameter can be 50-300 nm, preferably 100-200 nm; and the pitch can be 50-300 nm, preferably 100-200 nm.

[0027] The method for preparing the original substrate with the nano-forest structure on the upper surface comprises the following steps: providing an original substrate; forming a photoresist layer on the upper surface of the original substrate; etching the photoresist layer to obtain a nano-forest structure. The etching is preferably plasma etching. Preferably, the thickness of the photoresist layer is 4-6 μm.

[0028] Then, a magnetic metal layer is formed on the upper surface of the nano-forest structure.

[0029] Preferably, the magnetic metal layer is formed by sputtering. Preferably, the magnetic metal layer is a magnetic material, such as nickel, iron, cobalt, or manganese, etc. The material of the magnetic metal layer is not particularly limited in the present application, and any metal having magnetism can be used in the present application.

[0030] Preferably, the thickness of the magnetic metal layer can be 20-50 nm. A too thin metal layer is difficult to provide sufficient magnetic adsorption force, and a too thick metal layer is easy to form a continuous film on the top of the nano forest.

[0031] Then, a releasable adhesive tape is adhered to the upper surface of the magnetic metal layer, and the nano forest structure is separated from the original substrate, thereby obtaining the nano forest structure adhered to the releasable adhesive tape.

[0032] The releasable adhesive tape of the present application can lose adhesion under certain conditions or can be degraded under certain conditions. Preferably, the releasable adhesive tape is a heat-releasing adhesive tape. The heat-releasing adhesive tape is made of a temperature-sensitive material and can lose adhesion at a certain temperature. The nano forest structure is in a dense and collapsed state on the releasable adhesive tape.

[0033] Next, the releasable adhesive tape is treated, thereby releasing the nano forest structure having the magnetic metal layer on the upper surface.

[0034] In some embodiments, the releasable adhesive tape is a heat-releasing adhesive tape, and the heat-releasing adhesive tape is treated by heating. The heating temperature is determined by the characteristic temperature of the heat-releasing adhesive tape. Preferably, the heating is performed in a liquid. Preferably, the liquid is water. The nano forest structure detached from the original substrate is dispersed in a liquid such as water. In some specific embodiments, the nano forest structure adhered to the heat-releasing adhesive tape can be put into a liquid and the liquid is heated, so that the heat-releasing adhesive tape is heated and loses adhesion, thereby releasing the nano forest structure having the magnetic metal layer on the upper surface.

[0035] In other specific embodiments, the nano forest structure adhered to the heat-releasing adhesive tape can be put into a heated liquid, so that the heat-releasing adhesive tape is heated and loses adhesion, thereby releasing the nano forest structure having the magnetic metal layer on the upper surface.

[0036] Then, a target substrate is provided.

[0037] The target substrate of the present application can be any substrate, for example, can be a silicon substrate, an organic polymer substrate or a metal material substrate. In the present application, the first surface and the second surface of the target substrate refer to the two opposite surfaces with the largest area in the target substrate, i.e. the surfaces commonly processed in the art, and the first surface of the target substrate refers to the surface directly contacting the magnetic field, and the second surface of the target substrate refers to the surface opposite to the first surface. In some embodiments, the first surface of the target substrate refers to the upper surface thereof, and the second surface of the target substrate refers to the lower surface thereof.

[0038] Preferably, the second surface of the target substrate is provided with a flexible tape. The thickness of the flexible tape is in microns. Both the upper and lower surfaces of the flexible tape have adhesion. When the second surface of the target substrate is provided with a flexible tape, the method further comprises: after the transfer is completed, the magnetic field is removed. This embodiment is suitable for application scenarios that require further process preparation on the first surface of the target substrate. Since the nano-forest structure is adhered to the target substrate by the flexible tape, even if the magnetic field is removed, the nano-forest structure is still fixed on the target substrate.

[0039] In the case where the second surface of the target substrate is not provided with a flexible tape, after the transfer is completed, the magnetic field will always act on the first surface of the target substrate, so that the nano-forest structure is continuously adsorbed on the second surface of the target substrate. This embodiment is suitable for application scenarios that do not require further process preparation on the first surface of the target substrate.

[0040] In some specific embodiments, the releasable tape is a thermal release tape; the thermal release tape is treated by heating; the released nano-forest structure with the magnetic metal layer on the upper surface is placed in a liquid, and the target substrate is placed in the liquid with its second surface parallel to the horizontal plane, thereby providing the target substrate. Preferably, the target substrate is placed on top of the liquid.

[0041] In other embodiments, the second surface of the target substrate is provided with a flexible tape, and the releasable tape is a thermal release tape; the thermal release tape is treated by heating; the released nano-forest structure with the magnetic metal layer on the upper surface is placed in a liquid, and the target substrate is placed in the liquid with its second surface inclined at an angle α to the horizontal plane, thereby providing the target substrate. Preferably, the target substrate is placed on top of the liquid. Preferably, the angle α can be in the range of 0°-45°.

[0042] Finally, a magnetic field is applied to the first surface of the target substrate, thereby adsorbing the nano-forest structure with the magnetic metal layer on the upper surface to the second surface of the target substrate to complete the transfer.

[0043] In some embodiments, the second surface of the target substrate is provided with a flexible tape, and after the magnetic field is applied, the nano-forest structure of the magnetic metal layer on the upper surface is adsorbed onto the flexible tape, thereby completing the transfer.

[0044] Preferably, the adsorption is performed in a liquid. The liquid can be water. Preferably, the magnetic field can be applied by providing a magnetic substrate on the first surface of the target substrate. Preferably, the magnetic substrate is a magnet. When a magnetic substrate is used to adsorb the nano-forest structure in water, due to the resistance and torque of water, and only the magnetic metal layer on the top of the nano-forest structure is adsorbed by the magnetic field, the nano-forest structure will tend to be adsorbed vertically upward on the second surface of the target substrate.

[0045] Preferably, the upper surface area of the original substrate, the second surface area of the target substrate, and the lower surface area of the magnetic substrate are all the same.

[0046] In theory, when the heat-releasing tape is heated in a liquid and the target substrate is placed in the liquid with its second surface parallel to the horizontal plane, after the nano-forest structure is transferred to the target substrate, the arrangement interval of the nanorods on the target substrate is close to or the same as that on the original substrate, because from a macroscopic point of view, due to the same upper surface area of the original substrate, the same second surface area of the target substrate, and the same lower surface area of the magnetic substrate, the total number of nanorods in the nano-forest structure is also the same, and the magnetic field is uniformly distributed on the first surface of the target substrate, therefore, under the action of these factors, the nanorods can be uniformly distributed on the second surface of the target substrate, so that the interval of the nanorods before and after the transfer is the same.

[0047] In theory, when the adsorption process is performed in a liquid and the target substrate is placed in the liquid with its second surface inclined at an angle of α to the horizontal plane, due to the combined action of magnetic force, gravity, and the resistance and torque of water, after the nano-forest structure is transferred to the target substrate, the nano-forest structure can be arranged at a certain angle θ on the target substrate, and the nanorods are uniformly distributed on the second surface of the target substrate. In the present application, the sum of angle θ and angle α is 90°. The present application effectively solves the problem that the nano-forest structure cannot form a certain inclination angle, greatly expanding the application field of the nano-forest structure.

[0048] The present application will be further described below in conjunction with specific embodiments and drawings.

[0049] Example 1

[0050] First, a raw substrate 100, which is a single-crystal silicon raw substrate, is provided. Then, a photoresist layer is formed on the upper surface of the raw substrate 100. Subsequently, the photoresist layer is plasma-etched, thereby obtaining a nano-forest structure 200 in which the height of the nano-pillars 201 is 3 μm, the diameter of a single nano-pillar 201 is 100 nm, and the pitch of the nano-pillars 201 is 100 nm. The obtained structure is shown in FIG. 1. Figure 1

[0051] Then, a magnetic metal layer 300 having a thickness of 30 nm is formed on the upper surface of the nano-forest structure 200 by sputtering, in which the magnetic metal layer 300 is nickel. The obtained structure is shown in FIG. 2. Figure 2

[0052] Subsequently, a heat-releasable adhesive tape 400 (purchased from Shanghai Junna Technology Co., Ltd.) is adhered to the upper surface of the magnetic metal layer 300, and a pulling force is applied to separate the nano-forest structure 200 from the raw substrate 100, thereby obtaining a nano-forest structure adhered to the heat-releasable adhesive tape. The obtained structure is shown in FIG. 3. Figure 3

[0053] Next, the nano-forest structure 200 adhered to the heat-releasable adhesive tape 400 is heated to 90-100°C, so that the heat-releasable adhesive tape 400 is heated and loses adhesion, and the released nano-forest structure 200 having the upper surface with the magnetic metal layer 300 falls into water 500. The obtained structure is shown in FIG. 4. Figure 4

[0054] Then, a target substrate 600 (a silicon substrate) is placed on top of the water 500 with its lower surface parallel to the horizontal plane, in which the lower surface of the target substrate 600 has the same area as the upper surface of the raw substrate 100.

[0055] Subsequently, a magnetic substrate 700 is arranged on the upper surface of the target substrate 600 to apply a magnetic field, thereby adsorbing the nano-forest structure 200 having the upper surface with the magnetic metal layer 300 to the lower surface of the target substrate 600, to complete the transfer, in which the lower surface of the magnetic substrate 700 has the same area as the lower surface of the target substrate 600. The obtained structure is shown in FIG. 5. Figure 5

[0056] Finally, the magnetic substrate 700 is kept arranged on the target substrate 600, and the target substrate 600 having the nano-forest structure 200 adsorbed thereto and the magnetic substrate 700 are taken out of the water 500. The obtained structure is shown in FIG. 6. Figure 6

[0057] Example 2

[0058] ​​​​​​Example 2 is carried out according to the method described in Example 1, except that a flexible tape 800 is arranged on the lower surface of the target substrate 600 before the target substrate 600 is put into the water 500; after the magnetic field is applied by the magnetic substrate 700, the nano forest structure 200 with the magnetic metal layer 300 on the upper surface is adsorbed to the flexible tape 800, and the obtained structure is as shown in Figure 7 After the transfer is completed, the target substrate 600 with the adsorbed nano forest structure 200 is taken out of the water 500, and the magnetic substrate 700 is removed, and the obtained structure is as shown in Figure 8 .

[0059] Example 3

[0060] Example 3 is carried out according to the method described in Example 2, except that the target substrate 600 with the flexible tape 800 arranged on the lower surface is put into the top of the water 500 in a way that the lower surface is inclined at an angle of 45° with the horizontal surface. After the transfer is completed in the water, the obtained structure is as shown in Figure 9 . The target substrate 600 with the adsorbed nano forest structure 200 is taken out of the water 500, and the obtained structure is as shown in Figure 10 .

[0061] The above merely describes preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for transferring nanoforest structures, characterized in that, Includes the following steps: A raw substrate is provided, wherein a nanoforest structure is disposed on the upper surface of the raw substrate, the nanoforest structure being formed by photoresist; A magnetic metal layer is formed on the upper surface of the nanoforest structure; A releasable tape is adhered to the upper surface of the magnetic metal layer, and the nanoforest structure is separated from the original substrate, thereby obtaining a nanoforest structure adhered to the releasable tape. The releasable tape is processed to release the nanoforest structure having the magnetic metal layer on its upper surface, the nanoforest structure being dispersed in the liquid; Provide target base; as well as A magnetic field is applied to the first surface of the target substrate, thereby adsorbing the nanoforest structure with the magnetic metal layer on its upper surface to the second surface of the target substrate to complete the transfer; wherein the adsorption takes place in a liquid.

2. The method according to claim 1, characterized in that, A flexible adhesive tape is provided on the second surface of the target substrate; after the magnetic field is applied, the nanoforest structure with the magnetic metal layer on the upper surface is adsorbed onto the flexible adhesive tape.

3. The method according to claim 2, characterized in that, Also includes: After the transfer is complete, the magnetic field is removed.

4. The method according to claim 1 or 2, characterized in that, The releasable tape is a heat-release tape; The heat-release tape is treated by heating; The nanoforest structure with the magnetic metal layer on its upper surface is placed in a liquid, and the target substrate is placed in the liquid with its second surface parallel to the horizontal plane, thereby providing the target substrate.

5. The method according to claim 2, characterized in that, The releasable tape is a heat-release tape; The heat-release tape is treated by heating; The nanoforest structure with the magnetic metal layer on its upper surface is placed in a liquid, and the target substrate is placed in the liquid at an angle α between its second surface and the horizontal plane, thereby providing the target substrate.

6. The method according to claim 1 or 2, characterized in that, A magnetic field is applied by placing a magnetic substrate on the first surface of the target substrate.

7. The method according to claim 6, characterized in that, The upper surface area of ​​the original substrate, the second surface area of ​​the target substrate, and the lower surface area of ​​the magnetic substrate are all the same.

8. The method according to claim 1, characterized in that, The liquid is water.

9. The method according to claim 1 or 2, characterized in that, The magnetic metal layer is formed by sputtering; the magnetic metal layer is a magnetic material.

10. The method according to claim 1 or 2, characterized in that, The nanoforest structure comprises multiple nanopillars, each with a height of 1-5 μm, a diameter of 50-300 nm, and a spacing of 50-300 nm.

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