Nanoimprinting method

Abstract

This invention discloses a nanoimprinting method, comprising: providing a substrate and forming an imprinting adhesive layer on the surface of the substrate; providing a template with a nanoimprinting pattern; applying pressure to the template at a first temperature to nanoimprint the imprinting adhesive layer, wherein the first temperature is lower than room temperature, and the fluidity of the imprinting adhesive layer at the first temperature is less than that at room temperature; and after curing the imprinting adhesive layer, peeling off the template to obtain a micro / nano structure with uniform residual adhesive thickness. This invention reduces the fluidity of the imprinting adhesive layer by performing imprinting at a low temperature, thus solving the problem of uneven residual adhesive layer thickness. Especially when the nanoimprinting pattern has a non-uniform duty cycle or non-uniform height structure, this invention avoids the impact of uneven residual adhesive layer thickness on subsequent structure transfer processes.

Description

Technical Field

[0001] The present invention belongs to the technical field of nanoimprinting, and particularly relates to a nanoimprinting method. Background Art

[0002] Refer Figure 1 As shown, the process of fabricating nanostructures based on nanoimprinting technology generally includes: spin-coating a thin film of imprinting resin with a uniform thickness on a target substrate 11, placing a template 13 on the imprinting resin thin film, and applying pressure to fill the imprinting resin into the cavities 131 of the template 13. After curing the imprinting resin and demolding, an imprinting resin nanostructure replicated 1:1 with the template is obtained. After removing the residual resin layer, using the imprinting resin structure as a mask, the template pattern is transferred to the target substrate 11 by means of a dry etching process or a wet etching process, and a nanostructure of the substrate material is obtained.

[0003] Due to the inherent characteristics of nanoimprinting, when the nanostructures in the template 13 have different duty cycles or heights, the thickness of the residual resin at each location after imprinting is different. For example Figure 1 in, the thickness of the residual resin layer at the first residual resin region 121 and the second residual resin region 122 is inconsistent. The non-uniformity of the residual resin layer thickness will affect the subsequent structure transfer process. If the residual resin is removed based on the thinner region, the region with thicker residual resin cannot be completely removed. If the residual resin is removed based on the thicker region, the target substrate 11 in the thinner region will lose height.

[0004] Therefore, in view of the above technical problems, it is necessary to provide a nanoimprinting method. Summary of the Invention

[0005] The purpose of the present invention is to provide a nanoimprinting method, which can reduce the fluidity of the imprinting resin layer by performing imprinting in a low-temperature environment, and solve the problem of non-uniform thickness of the residual resin layer.

[0006] To achieve the above object, a specific embodiment of the present invention provides a nanoimprinting method, including: providing a substrate and forming an imprinting resin layer on the surface of the substrate; providing a template with a nanoimprinting pattern, and applying pressure to the template at a first temperature to perform nanoimprinting on the imprinting resin layer, wherein the first temperature is lower than room temperature, and the fluidity of the imprinting resin layer at the first temperature is less than the fluidity of the imprinting resin layer at room temperature; curing the imprinting resin layer and then peeling off the template to obtain a micro-nano structure with a uniform residual resin thickness.

[0007] In one or more embodiments of the present invention, the first temperature ranges from 0 to 10 °C.

[0008] In one or more embodiments of the present invention, the pressure applied to the template at the first temperature is greater than or equal to 40 bar.

[0009] In one or more embodiments of the present invention, the nanoimprinting method further includes: after forming an imprinting adhesive layer on the surface of the substrate, baking the substrate at a second temperature to reduce the solvent in the imprinting adhesive layer and reduce the fluidity of the imprinting adhesive layer, wherein the second temperature is higher than room temperature.

[0010] In one or more embodiments of the present invention, the second temperature range is greater than or equal to 120°C. The baking time is greater than or equal to 20 minutes.

[0011] In one or more embodiments of the present invention, the nanoimprinting method further includes: performing an anti-adhesion treatment on the surface of the template before performing nanoimprinting.

[0012] In one or more embodiments of the present invention, the surface of the template is subjected to an anti-adhesion treatment, specifically including: depositing a fluorocarbon compound on the surface of the template.

[0013] In one or more embodiments of the present invention, depositing a fluorocarbon compound on the surface of the template specifically includes: using reactive ion etching technology, under conditions of 8-10mt vacuum and 40-100W radio frequency power, plasma bombarding the template with a reactive gas source to deposit a fluorocarbon compound on the surface of the template, wherein the reactive gas source is one of C4F8, CHF3, and C2F6.

[0014] In one or more embodiments of the present invention, the nanoimprinting method further includes: providing a master template, covering the surface of the master template with a resin film and performing hot imprinting to prepare the template.

[0015] In one or more embodiments of the present invention, the substrate is made of silicon. The template is made of resin.

[0016] Compared with the prior art, the nanoimprinting method of the present invention reduces the fluidity of the imprinted adhesive layer by performing nanoimprinting in a low-temperature environment, thereby ensuring a consistent thickness of the residual adhesive layer. In particular, when the nanoimprinted pattern has a non-uniform duty cycle or non-uniform height structure, it avoids the impact of uneven residual adhesive layer thickness on subsequent structure transfer processes. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1This is a schematic diagram of the residual adhesive layer in the nanoimprinting process of existing technology;

[0019] Figure 2 This is a process flow diagram of the nanoimprinting method in one embodiment of the present invention;

[0020] Figure 3 This is a top view of the micro / nano structure in Embodiment 1 of the present invention;

[0021] Figure 4 for Figure 3 A partially enlarged schematic diagram of the micro / nano structure shown;

[0022] Figure 5 This is a side view of the micro / nano structure in Example 1;

[0023] Figure 6 for Figure 5 A partially enlarged schematic diagram of the micro / nano structure shown;

[0024] Figure 7 for Figure 5 Another enlarged schematic diagram of the micro / nano structure shown. Detailed Implementation

[0025] To enable those skilled in the art to better understand the technical solutions in this disclosure, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this disclosure.

[0026] In the detailed description of this specification, reference is made to the accompanying drawings, which form a part thereof, wherein like reference numerals always denote like parts, and wherein exemplary embodiments are shown by way of example that may be implemented. It should be understood that other embodiments may be utilized, and structural or logical changes may be made, without departing from the scope of this application. Therefore, the following detailed description should not be considered limiting.

[0027] As mentioned in the background section, when the nanoimprinted patterns in the template have different structural dimensions or heights, the thickness of the residual adhesive layer may vary after imprinting. Uneven residual adhesive layer thickness will affect subsequent structure transfer processes. If the residual adhesive is removed based on the thinner areas, the thicker areas will not be completely removed; conversely, if the residual adhesive is removed based on the thicker areas, the substrate in the thinner areas will lose height.

[0028] To address the aforementioned technical issues, existing technologies employ spot spraying, which precisely positions and sprays photoresist onto designated areas of the substrate as needed, replacing traditional full-surface coating. The drawback of spot spraying is that when the target micro / nano structure is too small, the volume of a single drop of photoresist is much larger than the space occupied by the nanoimprinted pattern, still resulting in residual photoresist.

[0029] Based on this, the present invention provides a nanoimprinting method, which reduces the fluidity of the imprinted adhesive layer by performing nanoimprinting in a low-temperature environment, thereby achieving uniformity control of the residual adhesive layer.

[0030] like Figure 1 As shown, the nanoimprinting method in one embodiment of the present invention specifically includes the following steps S101~S103:

[0031] S101 provides a substrate and forms an imprinting adhesive layer on the substrate surface.

[0032] S102, a template with a nanoimprint pattern is provided, and pressure is applied to the template at a first temperature to nanoimprint the imprinting adhesive layer, wherein the first temperature is lower than room temperature, and the fluidity of the imprinting adhesive layer at the first temperature is less than the fluidity of the imprinting adhesive layer at room temperature.

[0033] S103, after curing the imprinting adhesive layer, the template is peeled off to obtain a micro-nano structure with uniform residual adhesive thickness.

[0034] Furthermore, the substrate is preferably a silicon wafer. In one embodiment, an imprinting adhesive layer is prepared on the substrate surface by spin-coating epoxy resin adhesive, and the thickness of the imprinting adhesive layer is ensured to be the same at all locations.

[0035] In step S102, the first temperature range is 0~10℃. Within this temperature range, the thermal mobility of epoxy resin molecular chains and intermolecular forces decrease, the molecular chain movement in the imprinted adhesive layer is restricted, the flow resistance increases significantly, and the imprinted adhesive layer exhibits high viscosity and low fluidity.

[0036] In this invention, the template is a soft template made of resin, and the template material includes, but is not limited to, PC (polycarbonate), PMMA (polymethyl methacrylate), and PET (polyethylene terephthalate). The template includes a first surface and a second surface disposed opposite to each other, and the template has an imprinting cavity extending from the first surface to the second surface, the imprinting cavity not penetrating the first surface and the second surface.

[0037] It is understood that a number of imprint cavities arranged at intervals constitute the nanoimprint pattern of the template. The structural dimensions and height of the imprint cavities may be inconsistent (i.e., the depth to which the imprint cavities extend from the first surface to the second surface may be inconsistent, and the cross-sectional dimensions of the imprint cavities may be inconsistent). In other alternative embodiments, the imprint cavities of the template may also have the same depth and the same duty cycle, and be arranged at uniform intervals.

[0038] Understandably, during the imprinting process, the amount of imprinting adhesive in the imprinting layer exceeds the amount required for the nanoimprinted pattern on the template. Due to the inherent high fluidity of the imprinting adhesive layer, excess adhesive overflows to the side of the imprinting cavity, forming a residual adhesive layer. When the nanoimprinted pattern in the template has different structural dimensions or heights, the smaller imprinting cavity requires less imprinting adhesive than the larger one, resulting in a thicker residual adhesive layer on the side of the smaller imprinting cavity compared to the larger one. This invention reduces the fluidity of the imprinting adhesive layer by performing the imprinting in a low-temperature environment, preventing excess adhesive from overflowing to the side of the imprinting cavity during the imprinting process, thereby ensuring a consistent residual adhesive layer thickness.

[0039] To further ensure the embossing effect and improve the pattern filling efficiency, in step S102, the present invention compensates for insufficient fluidity of the embossing adhesive layer by applying high pressure, ensuring that the embossing adhesive completely fills the nano-embossing pattern of the template. Specifically, the pressure applied to the template at the first temperature is greater than or equal to 40 bar.

[0040] To further reduce the fluidity of the imprinting adhesive layer and improve the uniformity of the residual adhesive layer thickness, the nanoimprinting method of the present invention further includes: after forming the imprinting adhesive layer on the substrate surface, baking the substrate at a second temperature to reduce the solvent in the imprinting adhesive layer and reduce the fluidity of the imprinting adhesive layer, wherein the second temperature is higher than room temperature.

[0041] Specifically, the second temperature range in this invention is greater than or equal to 120°C, and the baking time is greater than or equal to 20 minutes.

[0042] Taking epoxy resin adhesive as an example, epoxy resin adhesive contains a certain amount of solvent to reduce the viscosity of the epoxy resin matrix. The main components of the solvent include acetone, toluene, and other components that are easily volatile at high temperatures. Therefore, under the second temperature condition, at least part of the solvent in the imprinting adhesive layer will evaporate, further reducing the fluidity of the imprinting adhesive layer. It is understood that this is only an example using epoxy resin adhesive; other types of nanoimprinting adhesives will also experience reduced fluidity after high-temperature baking.

[0043] In other alternative embodiments, those skilled in the art can directly use a high-viscosity, low-flow nanoimprint adhesive instead of the step provided in this invention of baking the substrate at the second temperature to reduce the flowability of the imprint adhesive layer, or combine the two.

[0044] To further improve the uniformity of the residual adhesive layer thickness, the nanoimprinting method of this invention further includes: performing an anti-adhesion treatment on the surface of the template before nanoimprinting, thereby reducing the surface energy of the template. It is understood that reducing the surface energy of the template reduces the capillary force between the template and the imprinting adhesive layer, thereby reducing the flow of the imprinting adhesive layer caused by capillary forces.

[0045] Specifically, the anti-adhesion treatment of the template surface includes: depositing a fluorocarbon compound on the template surface, wherein the fluorocarbon compound in this invention includes one of C4F8, CHF3, and C2F6.

[0046] For example, reactive ion etching technology is used to bombard the template with plasma under vacuum conditions of 8~10mt and RF power of 40~100W to deposit fluorocarbons on the surface of the template. The reactive gas source is one of C4F8, CHF3 and C2F6.

[0047] Furthermore, the present invention also provides a method for preparing a template, specifically comprising: providing a master template, wherein the nanoimprint pattern of the master template is complementary to the nanoimprint pattern of the template; covering the surface of the master template with a resin film and performing hot imprinting to prepare the template.

[0048] It is understood that the micro-nano structure prepared based on the method provided by the present invention includes a residual adhesive layer and micro-nano units protruding from the surface of the residual adhesive layer, wherein the thickness of the residual adhesive layer is the same everywhere, and the shape and size of the micro-nano units can be the same or different.

[0049] A specific embodiment of the present invention also provides a nanoimprinting method, which specifically includes: removing the residual adhesive layer between adjacent micro / nano units to obtain a mask structure; etching the substrate based on the mask structure using a dry etching process or a wet etching process; and then transferring the nanoimprinted pattern of the template to the substrate to obtain the nanostructure of the substrate material.

[0050] Another specific embodiment of the present invention provides the application of the above-mentioned micro / nano structures in new energy devices, biomedical detection devices, microfluidic devices, electronic devices, optical components, or nanoimprinting. Specifically, the prepared micro / nano structures can be used as templates to create sub-templates, or to create production templates for large-scale imprinting. Furthermore, in the creation of anti-counterfeiting patterns, the micro / nano structure preparation method of the present invention can be used to create anti-counterfeiting patterns, or the micro / nano structures can be used as templates for anti-counterfeiting pattern imprinting.

[0051] It should be noted that "consistent thickness" refers to approximately consistent thickness within a reasonable error range achievable by the process, not an absolutely uniform state without deviation. Due to objective factors such as substrate flatness, the characteristics of the imprinting adhesive itself, and fluctuations in imprinting conditions, minor deviations in residual adhesive thickness, as is common in the art, are permissible. These deviations do not affect the integrity of the micro / nano structure morphology or the subsequent pattern transfer effect, and should all be considered as meeting the "consistent residual adhesive thickness" requirement of this invention. The invention will be further described below with reference to specific embodiments.

[0052] An epoxy resin-based nanoimprinting adhesive was spin-coated onto the surface of a 4-inch circular silicon wafer. The substrate was then heated to 120°C and baked at that temperature for 20 minutes.

[0053] A resin template is prepared by using a silicon nanoimprint master template, covering the template surface with a resin film, and performing hot imprinting at 160°C and 20 bar.

[0054] Reactive ion etching (RIE) was used to bombard the template with plasma under a vacuum of 8 mt and a radio frequency power of 40 W, using C4F8 as the reactive gas source, in order to deposit fluorocarbons on the surface of the template and reduce the surface energy of the template.

[0055] Using a surface-treated template, nanoimprinting adhesive was imprinted at 4°C and 50 bar to prepare nanopillar structures with diameters ranging from 100 nm to 500 nm and heights ranging from 50 nm to 400 nm on the same substrate surface.

[0056] Combination Figure 3 and Figure 4 As shown, the diameters of the nanopillar structures range from 100 to 500 nm. (Combined with...) Figures 5-7 As shown, the height of the nanopillar structure varies from 50nm to 400nm, and the thickness of the residual adhesive layer is consistent at all locations, around 72.9nm.

[0057] As can be seen from the above technical solutions, the present invention has the following beneficial effects:

[0058] This invention achieves uniform control of the residual adhesive layer by performing nanoimprinting at low temperatures, reducing the fluidity of the imprinting adhesive layer. This is particularly effective when the nanoimprinted pattern has a non-uniform duty cycle or non-uniform height structure, solving the problem of uneven residual adhesive layer thickness and preventing interference with subsequent structure transfer processes. To ensure imprinting effect and improve pattern filling efficiency, this invention compensates for insufficient fluidity of the imprinting adhesive layer with high pressure, ensuring complete filling of the nanoimprinted pattern on the template. Furthermore, this invention bakes the substrate at a second temperature to reduce the solvent in the imprinting adhesive layer and decrease its fluidity, further reducing the fluidity of the imprinting adhesive layer and improving the uniformity of the residual adhesive layer thickness. In addition, this invention applies an anti-adhesion treatment to the template surface to reduce the surface energy of the template, thereby reducing the capillary force between the template and the imprinting adhesive layer, further improving the uniformity of the residual adhesive layer thickness.

[0059] It will be apparent to those skilled in the art that this disclosure is not limited to the details of the exemplary embodiments described above, and that this disclosure can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of this disclosure is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this disclosure. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0060] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A nanoimprinting method, characterized in that, The nanoimprinting method includes: A substrate is provided, and an imprinting adhesive layer is formed on the surface of the substrate; A template with a nanoimprint pattern is provided, and pressure is applied to the template at a first temperature to nanoimprint the imprint adhesive layer, wherein the first temperature is lower than room temperature, and the fluidity of the imprint adhesive layer at the first temperature is less than the fluidity of the imprint adhesive layer at room temperature; After the imprinting adhesive layer is cured, the template is peeled off to obtain a micro-nano structure with uniform residual adhesive thickness.

2. The nanoimprinting method according to claim 1, characterized in that, The first temperature range is 0~10℃.

3. The nanoimprinting method according to claim 1, characterized in that, The pressure applied to the template at the first temperature is greater than or equal to 40 bar.

4. The nanoimprinting method according to claim 1, characterized in that, The nanoimprinting method further includes: after forming an imprinting adhesive layer on the substrate surface, baking the substrate at a second temperature to reduce the solvent in the imprinting adhesive layer and reduce the fluidity of the imprinting adhesive layer, wherein the second temperature is higher than room temperature.

5. The nanoimprinting method according to claim 4, characterized in that, The second temperature range is greater than or equal to 120°C; and / or, Baking time is greater than or equal to 20 minutes.

6. The nanoimprinting method according to claim 1, characterized in that, The nanoimprinting method further includes: performing an anti-adhesion treatment on the surface of the template before performing nanoimprinting.

7. The nanoimprinting method according to claim 6, characterized in that, The surface of the template is subjected to an anti-adhesion treatment, specifically including: depositing a fluorocarbon compound on the surface of the template.

8. The nanoimprinting method according to claim 7, characterized in that, Depositing fluorocarbons on the surface of the template specifically includes: using reactive ion etching technology, under conditions of 8-10mt vacuum and 40-100W radio frequency power, plasma bombarding the template with a reactive gas source to deposit fluorocarbons on the surface of the template, wherein the reactive gas source is one of C4F8, CHF3, and C2F6.

9. The nanoimprinting method according to claim 1, characterized in that, The nanoimprinting method further includes: providing a master template, covering the surface of the master template with a resin film and performing hot imprinting to prepare the template.

10. The nanoimprinting method according to claim 1, characterized in that, The substrate is made of silicon; and / or, The template is made of resin.

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