Cross-scale micro-nano structure manufacturing method

Abstract

The invention discloses a method for manufacturing a cross-scale micro-nano structure, which relates to the technical field of micro-nano structure processing, and comprises the following steps of: removing pollutants and an oxide layer on the surface of a substrate, forming a negative photoresist mask on the surface of the substrate, converting the negative photoresist from a high-elastic state to a glassy state, and forming a cross-scale micro-nano structure on the surface of the substrate. The manufacturing method comprises the following steps: coating a photoresist on the surface of a micron-sized indentation structure layer, carrying out imprinting to obtain the micron-sized indentation structure layer, carrying out exposure and curing, coating a negative photoresist on the surface of the micron-sized indentation structure layer, carrying out imprinting, obtaining a nano-sized indentation on the basis of the micron-sized indentation structure layer, and forming the cross-scale micro-nano structure. The micron-sized indentation structure layer is obtained through the imprinting technology, the nano-sized indentation structure layer can be obtained through secondary imprinting in the micron-sized indentation structure layer, and the nano-sized indentation structure layer is directly formed in the gully of the micron-sized indentation structure, so that the cross-scale micro-nano structure can be obtained through twice imprinting. The technical problems that the cross-scale micro-nano structure on the surface of the photoresist is large in manufacturing difficulty, high in cost, poor in flexibility and the like are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of micro-nano structure processing, and in particular to a micro-nano structure manufacturing method. Background Art

[0002] Cross-scale micro-nano structures refer to hierarchical composite structures that combine micrometers, nanometers and other scales. They have multiple functions such as hydrophilic and hydrophobic regulation, light field regulation, friction regulation, etc., and are widely used in aerospace, microelectronics, biomaterials, automobiles, energy and other technical fields. For example, a curved compound eye array with a micro-nano structure can obtain a larger field of view and is used in light detectors. The macroscopic composite structure of nanoarrays on free-form surfaces gives aircraft good aerodynamic performance. At the same time, nanoarray structures have the effect of enhancing transmittance and are widely used in aviation conformal optical windows, while curved gratings with micro-nano structures are widely used in polychromators. At present, the commonly used technologies for manufacturing cross-scale micro-nano structures include ultra-precision machining, photolithography, femtosecond lasers and self-assembly.

[0003] The secondary structure of the micro-nano secondary structure produced by ultra-precision machining is generally caused by tool vibration, and its texture form is single and the processing time is long; the micro-nano secondary structure produced by femtosecond laser processing has high processing efficiency, but it has not been possible to achieve a variety of secondary structure processing on thermoplastic polymers so far, and the surface chemical composition changes due to surface modification; the self-assembly process assembles SiO 2 (Silicon dioxide) nanospheres or PS (Polystyrene, polystyrene) nanospheres, and then use them as masks to transfer them to the substrate by dry etching. The nanostructures are mostly micro-column and micro-cone structures, and the available texture shapes are relatively few; while the photolithography method first classifies the masks according to the size, with small size as the first level and large size as the second level, and then exposes the first level structure 1-3 times, and then exposes the large size mold 7-9 times. Since UV lithography technology is top-down, it can only be used to manufacture cross-scale micro-nano structures with simple two-dimensional structures, and cannot achieve cross-scale structure manufacturing with complex three-dimensional morphology.

[0004] Therefore, a micro-nano structure manufacturing method that overcomes the above technical problems is needed. Summary of the invention

[0005] The purpose of the present invention is to provide a method for manufacturing a cross-scale micro-nano structure to solve the problems existing in the above-mentioned prior art. In the present invention, a negative photoresist mask serving as the basis of a micron-level indentation structure layer is heat-baked to obtain a glassy negative photoresist mask, and a firm micron-level indentation structure layer is obtained by combining the imprinting technology. The nano-level indentation structure layer can be obtained by imprinting again in the micron-level indentation structure layer. The nano-level indentation structure layer is directly formed in the grooves of the micron-level indentation structure. Therefore, a cross-scale micro-nano structure can be obtained by imprinting twice, which solves the technical difficulties of difficulty, high cost and poor flexibility in manufacturing cross-scale micro-nano structures on the photoresist surface. The method has the advantages of simple and convenient operation and high flexibility, and can transfer planar nanostructures to the surface of macroscopic structures to realize cross-scale structure manufacturing with complex three-dimensional morphology.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] The present invention provides a method for manufacturing a cross-scale micro-nano structure, comprising the following steps:

[0008] S1. Remove pollutants and oxide layers on the surface of the substrate;

[0009] S2, applying negative photoresist on the surface of the substrate to form a negative photoresist mask;

[0010] S3, thermally baking the negative photoresist mask obtained in step S2 until the negative photoresist changes from a highly elastic state to a glassy state, and imprinting the negative photoresist mask so that a micrometer-level indentation structure layer is formed on the surface of the negative photoresist mask;

[0011] S4, exposing the negative photoresist mask obtained in step S3 to solidify the micron-scale indentation structure layer;

[0012] S5, applying negative photoresist on the surface of the solidified micron-scale indentation structure layer obtained in step S4, allowing the negative photoresist to fill the micron-scale indentation structure, and forming a negative photoresist mask on the surface of the micron-scale indentation structure layer;

[0013] S6. Imprinting the negative photoresist mask obtained in step S5 to obtain nanometer-scale indentations on the basis of the micrometer-scale indentation structure layer, thereby forming a cross-scale micro-nano structure.

[0014] Preferably, in step S1, the substrate is treated by soaking, showering, and air blowing for drying the substrate after showering.

[0015] Preferably, the immersion solution is acetone, the immersion time is 10 minutes, the solution for rinsing the substrate is deionized water, the rinsing time is 3 minutes, and the blowing gas is nitrogen.

[0016] Preferably, in step S2, the substrate is baked before applying the negative photoresist, the baking temperature is 180 degrees Celsius, and the baking time is 5 minutes.

[0017] Preferably, in step S2, the coating method is a rotary coating method, the coating time is 40 seconds, the initial coating speed is 0, the coating speed increases by 100 revolutions per second, and the acceleration time is 4 seconds.

[0018] Preferably, in step S3, the temperature of the thermal drying is 50 degrees Celsius.

[0019] Preferably, in step S3, the material of the imprinting mold with the micron-scale pattern is nickel, and a micron-scale structural layer is provided on the surface of the imprinting mold with the micron-scale pattern in contact with the negative electrode photoresist mask.

[0020] Preferably, in step S4, the light used for exposure is ultraviolet light, and the wavelength of the ultraviolet light is 350 nanometers to 400 nanometers.

[0021] Preferably, in step S5, the coating method is a rotary coating method, the coating time is 40 seconds, the initial coating speed is 0, the coating speed increases by 100 revolutions per second, and the acceleration time is 4 seconds.

[0022] Preferably, in step S6, the material of the imprinting mold of the nanoscale pattern is polydimethylsiloxane, and a nanoscale structural layer is provided on the surface of the imprinting mold of the nanoscale pattern in contact with the negative electrode photoresist mask.

[0023] Compared with the prior art, the present invention has achieved the following technical effects:

[0024] The present invention provides a method for manufacturing a cross-scale micro-nano structure. A negative photoresist mask serving as the basis of a micron-level indentation structure layer is thermally baked to obtain a glassy negative photoresist mask. The imprinting technology is combined to obtain a firm micron-level indentation structure layer. The nano-level indentation structure layer can be obtained by imprinting again in the micron-level indentation structure layer. The nano-level indentation structure layer is directly formed in the grooves of the micron-level indentation structure. Therefore, the cross-scale micro-nano structure can be obtained by imprinting twice, thereby solving the technical problems of difficulty, high cost and poor flexibility in manufacturing the cross-scale micro-nano structure on the photoresist surface.

[0025] Compared with the prior art, the present invention also achieves the following technical effects:

[0026] 1. In the present invention, a spin coating method is used to apply negative photoresist, and the spin coating method can accurately control the thickness and surface flatness of the negative photoresist mask to form a high-precision negative photoresist mask that meets the processing standards;

[0027] 2. The mold for imprinting the nano-scale indentation structure in the present invention is polydimethylsiloxane, which is soft in texture and easily deformed after being compressed. It can better fit the micron-scale indentation structure layer and penetrate into the micron-scale indentation structure, allowing the negative photoresist filled in the micron-scale indentation structure to present micron-scale indentations. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 It is a schematic diagram of the manufacturing method of the present invention;

[0030] Figure 2 It is a functional relationship image of the spin coating thickness, exposure dose and spin coating speed in the present invention. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] The purpose of the present invention is to provide a method for manufacturing a cross-scale micro-nano structure to solve the problems existing in the above-mentioned prior art. In the present invention, a negative photoresist mask serving as the basis of a micron-level indentation structure layer is heat-baked to obtain a glassy negative photoresist mask, and a firm micron-level indentation structure layer is obtained by combining the imprinting technology. A nano-level indentation structure layer can be obtained by imprinting again on the basis of the micron-level indentation structure layer, and the obtained nano-level indentation structure layer can be directly embedded in the micron-level indentation structure. A cross-scale micro-nano structure can be obtained by only two imprintings, thereby solving the technical problems of difficulty, high cost and poor flexibility in manufacturing cross-scale micro-nano structures on the photoresist surface.

[0033] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] like Figure 1 As shown, the present invention provides a method for manufacturing a cross-scale micro-nano structure, comprising the following steps:

[0035] S1. Remove pollutants and oxide layers on the substrate surface to ensure that the subsequently applied photoresist can fully adhere to the substrate surface.

[0036] S2. Negative photoresist is applied to the surface of the substrate to form a negative photoresist mask. Before applying the negative photoresist, the substrate is heated first. The purpose of heating the substrate is to remove volatile resins or solvent compounds in the negative photoresist and eliminate bubbles that may affect the performance and quality of the photoresist. It also helps to remove water vapor on the surface of the wafer, which helps to improve the adhesion of the photoresist to the wafer and ensure the smooth progress of the coating process.

[0037] S3, the negative photoresist mask obtained in step S2 is heat-baked until the negative photoresist changes from a highly elastic state to a glassy state. The temperature at this time is called the Tg point (the transition temperature of the negative photoresist from a highly elastic state to a glassy state). The negative photoresist mask is imprinted so that a micrometer-level indentation structure layer is formed on the surface of the negative photoresist mask. The viscosity of the glassy negative photoresist at room temperature increases exponentially compared with that of the highly elastic state, and it exhibits solid properties macroscopically. The imprinting method in this step is hot imprinting, that is, the negative photoresist is in contact with a template having a predefined topological pattern, and they are pressed together under a certain pressure. When the negative photoresist is heated to above the glass transition temperature, the pattern on the template is pressed into the softened polymer film. After cooling, the template is separated from the sample, and the pattern resist is left on the substrate. After the negative photoresist mask is cooled, the imprinting mold is removed to ensure the integrity of the indentation.

[0038] S4, exposing the negative photoresist mask obtained in step S3 to solidify the micron-scale indentation structure layer. The exposure can make the negative photoresist present solid properties on the microscopic side.

[0039] S5. Apply negative photoresist on the surface of the solidified micron-scale indentation structure layer obtained in step S4, allow the negative photoresist to fill the micron-scale indentation structure, and form a negative photoresist mask on the surface of the micron-scale indentation structure layer.

[0040] S6. Imprinting the negative photoresist mask obtained in step S5 to obtain nanoscale indentations on the basis of the micron-scale indentation structure layer to form a cross-scale micro-nano structure. The nanoscale indentations can be directly generated in a relatively wide micron-scale indentation to form a composite cross-scale structure. In this step, the negative photoresist mask can also be heat-baked first to convert the negative photoresist into a glassy state before imprinting, and the obtained nanoscale indentations are exposed and cured. The Tg point of the exposed micron-scale indentation structure layer increases, so heating the nanoscale indentation will not cause the micron-scale indentation structure layer to undergo morphological changes, and the existing micron-scale indentation structure will not be damaged during imprinting.

[0041] In step S1, the method of processing the substrate includes soaking, rinsing and air blowing for drying the substrate after rinsing, wherein the function of soaking is to remove organic matter and oxides on the surface of the substrate, and the function of rinsing is to remove other types of pollutants on the surface of the substrate. The soaking time is 8 minutes to 12 minutes, and the rinsing time is 2 to 4 minutes. In a preferred embodiment, the soaking solution is acetone, the soaking time is 10 minutes, the solution for rinsing the substrate is deionized water, the rinsing time is 3 minutes, and the air blowing gas is nitrogen.

[0042] In step S2, the baking temperature is 180 degrees Celsius, the baking time is 5 minutes, in a preferred embodiment, the coating method is a rotary coating method, the coating time is 40 seconds, the coating initial speed is 0, the coating speed increases by 100 revolutions per second, and the acceleration time is 4 seconds. Figure 2 The functional relationship between the spin coating thickness (Polymerised Thickness), exposure dose (Exsopure Dose) and spin coating speed (Spin Speed) is shown. By adjusting the spin coating speed, a negative polarity photoresist mask of a specified thickness can be obtained.

[0043] The negative photoresist selected in the present invention is SU-8 photoresist. When not exposed, the Tg point of SU-8 photoresist is about 50 degrees Celsius. Therefore, in step S3, the thermal baking temperature is 50 degrees Celsius, and the Tg point of the exposed SU-8 photoresist is about 200 degrees Celsius. When other types of negative photoresists are used, the thermal baking temperature is consistent with the unexposed Tg point of the selected negative photoresist.

[0044] In step S3, the material of the imprint mold of the micron-scale pattern is nickel, and a micron-scale structural layer is arranged on the surface of the imprint mold of the micron-scale pattern that contacts the negative electrode photoresist mask. The pattern of the micron-scale structural layer is designed according to needs. In a preferred embodiment, the imprint mold of the micron-scale pattern is made by a laser etching process. The laser etching process has high processing precision and fast processing speed, and is convenient for mass production. The imprint mold of the micron-scale pattern can also be made by machining, 3D printing, electrospark etching technology, etc.

[0045] In step S4, the light used for exposing and curing the negative polarity photoresist mask of the present invention is ultraviolet light, and the wavelength of the ultraviolet light is 350 nanometers to 400 nanometers. When the negative polarity photoresist mask needs to be cured in step S6, ultraviolet light with a wavelength of 350 nanometers to 400 nanometers can also be used.

[0046] In a preferred embodiment of step S5, the method of applying the negative photoresist is a spin coating method, the coating time is 40 seconds, the initial coating speed is 0, the coating speed increases by 100 revolutions per second, and the acceleration time is 4 seconds.

[0047] In step S6, the material of the imprint mold of the nanoscale pattern is polydimethylsiloxane, and a nanoscale structural layer is arranged on the surface of the imprint mold of the nanoscale pattern in contact with the negative electrode photoresist mask. Polydimethylsiloxane is easily deformed by force and can fit well with the micron-scale indentation structural layer, so that a nano-indentation with a complete morphology appears inside the micron-indentation. In a preferred embodiment, the imprint mold of the micron-scale pattern and the imprint mold of the nanoscale pattern can be used in combination. Specifically, the imprint mold of the nanoscale pattern is placed under the imprint mold of the micron-scale pattern, and the nanoscale structural layer is ensured to face the negative electrode photoresist mask. The imprint of the micron-scale pattern can be completed by compacting the imprint; the imprint mold of the nanoscale pattern can also be made of other soft materials that do not react with the negative electrode photoresist.

[0048] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for manufacturing a cross-scale micro-nano structure, characterized in that: The following steps are included: S1. Remove pollutants and oxide layers on the surface of the substrate; S2, applying negative photoresist on the surface of the substrate to form a negative photoresist mask; S3, thermally baking the negative photoresist mask obtained in step S2 until the negative photoresist changes from a highly elastic state to a glassy state, and imprinting the negative photoresist mask so that a micrometer-level indentation structure layer is formed on the surface of the negative photoresist mask; S4, exposing the negative photoresist mask obtained in step S3 to solidify the micron-scale indentation structure layer; S5, applying negative photoresist on the surface of the solidified micron-scale indentation structure layer obtained in step S4, allowing the negative photoresist to fill the micron-scale indentation structure, and forming a negative photoresist mask on the surface of the micron-scale indentation structure layer; S6. Imprinting the negative photoresist mask obtained in step S5 to obtain nanoscale indentations in the grooves of the microscale indentation structure layer. The microscale indentations and nanoscale indentations are interlaced to form a cross-scale micro-nano structure.

2. The cross-scale micro-nano structure manufacturing method according to claim 1, characterized in that: In step S1 , the substrate is treated by soaking, showering, and air blowing for drying the substrate after showering.

3. The cross-scale micro-nano structure manufacturing method according to claim 2, characterized in that: The immersion solution is acetone, and the immersion time is 10 minutes; The solution used to rinse the substrate was deionized water, and the rinsing time was 3 minutes; The blowing gas is nitrogen.

4. The cross-scale micro-nano structure manufacturing method according to claim 1, characterized in that: In step S2, the substrate is baked before applying the negative photoresist, the baking temperature is 180 degrees Celsius, and the baking time is 5 minutes.

5. The cross-scale micro-nano structure manufacturing method according to claim 1, characterized in that: In step S2, the coating method is the rotary coating method, the coating time is 40 seconds, the initial coating speed is 0, the coating speed increases by 100 revolutions per second, and the acceleration time is 4 seconds.

6. The cross-scale micro-nano structure manufacturing method according to claim 1, characterized in that: In step S3, the temperature of the heat baking is 50 degrees Celsius.

7. The method for manufacturing a cross-scale micro-nano structure according to claim 1, characterized in that: In step S3, the material of the imprinting mold of the micron-scale pattern is nickel, and a micron-scale structural layer is provided on the surface of the imprinting mold of the micron-scale pattern that contacts the negative electrode photoresist mask.

8. The cross-scale micro-nano structure manufacturing method according to claim 1, characterized in that: In step S4, the light used for exposure is ultraviolet light, and the wavelength of the ultraviolet light is 350 nanometers to 400 nanometers.

9. The cross-scale micro-nano structure manufacturing method according to claim 1, characterized in that: In step S5, the coating method is the rotary coating method, the coating time is 40 seconds, the initial coating speed is 0, the coating speed increases by 100 revolutions per second, and the acceleration time is 4 seconds.

10. The cross-scale micro-nano structure manufacturing method according to claim 1, characterized in that: In step S6 , the material of the imprinting mold of the nanoscale pattern is polydimethylsiloxane, and a nanoscale structure layer is provided on the surface of the imprinting mold of the nanoscale pattern that contacts the negative electrode photoresist mask.

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