Nanoimprint method and nanoimprint mold

Abstract

The present invention provides a nanoimprinting method, which includes placing a working mold and a substrate formed with an imprinting adhesive layer in a sealed chamber, introducing a working gas into the sealed chamber to displace the ambient gas, and the introduced working gas has a greater solubility in the imprinting adhesive layer than the original ambient gas; subsequently, with the working mold in a state where its micro-nano structure is in contact with the imprinting adhesive layer, applying pressure to at least one of the working mold and the substrate, causing the imprinting adhesive layer to deform and fill the pores between the micro-nano structures, and transferring the micro-nano structures into the imprinting adhesive layer. The present invention uses the method of replacing the atmosphere composition, so that the gas captured by the imprinting adhesive layer when pressed into the working mold can be dissolved during the pore filling process of the working mold, greatly reducing the probability of generating bubbles, suppressing the pattern loss caused by bubbles, improving the pattern processing accuracy, enhancing the product yield, and not significantly increasing the cost and time of the imprinting process.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a nanoimprint method and a nanoimprint mold. Background Art

[0002] Nanoimprint technology is a graphic transfer technology completed by contact imprinting. Unlike traditional optical lithography technology that requires expensive process equipment, nanoimprint technology can produce patterns with nanoscale resolution at low cost. It has been widely used in the production and manufacturing of microfluidic chips, biochips, diffraction optical devices, various types of gratings, augmented reality products, and virtual reality products. In recent years, it has gradually expanded to the field of integrated circuit manufacturing.

[0003] Currently, defect rate is one of the bottlenecks limiting the application of nanoimprint technology in integrated circuit production. Figure 1 A typical nanoimprinting process flow chart is shown as Figure 1 As shown, the nanoimprint process generally includes the following steps: 1) coating, coating an imprint glue including an anti-etching agent on a substrate; 2) filling, providing a working mold with a relief pattern, and squeezing the imprint glue into the relief pattern on the working mold under the action of an external force; 3) curing, after the imprint glue filling is completed, the imprint glue is cured; 4) demoulding, using an external force to separate the working mold from the substrate, that is, leaving the imprint glue with a pattern on the substrate.

[0004] The most common defects in the nanoimprint process are attributed to the large number of graphic defects in the imprint glue after demolding, which are mainly manifested as graphic missing, that is, the graphics replicated by nanoimprinting are partially damaged, missing, and incomplete: For most applications, Figure 2 The defects shown will make the product quality unacceptable and produce defective products, especially in the metal interconnection structure of integrated circuits, where the pattern loss of metal interconnection lines will lead to circuit disconnection. One of the conventional methods for improving the bubble defects in the nanoimprint process is to construct a sealed chamber in the imprinting device, and keep the sealed chamber under vacuum conditions to perform the nanoimprint process to reduce the probability of bubble generation, which will increase the cost and time of the imprinting process.

[0005] It should be noted that the above introduction to the technical background is only for the convenience of providing a clear and complete description of the technical solutions of this application and for the convenience of understanding by those skilled in the art. It cannot be considered that the above technical solutions are well known to those skilled in the art simply because they are described in the background technology section. Summary of the invention

[0006] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a nanoimprint method and a nanoimprint mold, which are used to solve the problem of pattern defects caused by bubble defects in the patterns replicated by the existing nanoimprint process.

[0007] To achieve the above object and other related objects, the present invention provides a nanoimprinting method, comprising the following steps:

[0008] Providing a substrate, forming an embossed adhesive layer on the substrate, wherein the embossed adhesive layer includes a photoresist layer;

[0009] Placing a working mold and the substrate formed with an embossed adhesive layer in a sealed chamber, wherein the working mold includes a pattern transfer layer having a micro-nano structure, introducing a working gas into the sealed chamber to replace the original ambient gas, wherein the solubility of the introduced working gas in the embossed adhesive layer is greater than the solubility of the ambient gas in the embossed adhesive layer;

[0010] Applying pressure to at least one of the working mold and the substrate while the micro-nano structure of the working mold is in contact with the embossed adhesive layer, so that the embossed adhesive layer is deformed to fill the pores between the micro-nano structures, and the micro-nano structures in the pattern transfer layer are transferred to the embossed adhesive layer;

[0011] Under the condition of maintaining an atmosphere containing a working gas, the transferred embossed adhesive layer is solidified to form a pad printing pattern complementary to the micro-nano structure;

[0012] The working mold is demoulded from the pad printing pattern.

[0013] Optionally, the ambient gas is replaced by introducing the working gas toward the gap between the working mold and the substrate, wherein the working gas includes CO 2 , He, H 2 One or a combination of .

[0014] Optionally, before or after the step of forming the embossed adhesive layer, the working mold and the substrate are placed in the sealed chamber, wherein the pad printing pattern is formed by one or a combination of a plate-to-plate embossing method, a roller-to-roll embossing method, a roller-to-plate embossing method and a step-by-step embossing method.

[0015] Optionally, after the step of filling the pores between the micro-nano structures, the following steps are included:

[0016] In the sealed chamber, the photoresist layer is exposed by using an ultraviolet light source to solidify the transferred imprinted adhesive layer, wherein the photoresist layer is selected to be an ultraviolet photoresist.

[0017] Optionally, the embossed adhesive layer includes a photoresist layer and an optical functional material layer, and the step of filling the pores between the micro-nano structures includes:

[0018] One or a combination of an air bag, a pressure plate and an embossing roller is used to apply pressure to at least one of the working mold and the substrate, and the embossed adhesive layer and the working mold are cooled by introducing cooled working gas.

[0019] Furthermore, the step of curing the transferred embossed adhesive layer further includes:

[0020] The substrate is placed on the imprinting mechanism by using a suction cup, and the substrate, the imprinting adhesive layer and the working mold are subjected to temperature reduction treatment by means of electrocooling.

[0021] Optionally, the embossed adhesive layer is deformed in the replaced sealed chamber to fill the pores between the micro-nano structures, and at the same time, a working gas is captured to form bubbles, wherein the working gas is selected so that the bubbles formed in the embossed adhesive layer have a size smaller than a critical size l. c′ The dimensions are dissolved, and the critical size l c′ It is expressed by the following formula:

[0022]

[0023] Among them, C a is the solubility of the working gas at standard atmospheric pressure, P a is the standard atmospheric pressure, σ is the solubility of the working gas in the imprinting glue, P w It is the gas pressure in the working environment.

[0024] Furthermore, the working gas is selected so that the critical size of the bubbles formed during the filling process of the pores between the micro-nano structures is l c′ Larger than the characteristic size of the micro-nano structure on the working mold.

[0025] Optionally, the material of the working mold includes Si, SiO 2 , Ni, transparent glass, perfluoropolyether PFPE, polydimethylsiloxane PDMS or a combination thereof.

[0026] Optionally, the method of maintaining the atmosphere containing the working gas includes: monitoring the pressure and atmosphere composition in the sealed chamber, and adjusting the replacement rate of the working gas.

[0027] Optionally, the nanoimprint method is used to prepare a nanoimprint mold, a pattern transfer layer, an optical functional layer and a release film having a nanoscale microstructure.

[0028] The present invention also provides a nanoimprint mold, which includes a pad printing pattern, and the pad printing pattern is prepared by the nanoimprint method of the above item.

[0029] As described above, the present invention provides a nanoimprinting method having the following beneficial effects:

[0030] The nanoimprint method provided by the present invention increases the solubility of the working gas in the imprinted rubber layer by replacing the atmosphere composition before performing the step of filling the pores of the working mold in the sealed chamber, so that the gas captured by the imprinted rubber layer when pressed into the working mold can be dissolved in the process of filling the pores of the working mold, greatly reducing the probability of generating bubbles, suppressing the pattern loss caused by bubbles, thereby improving the pattern processing accuracy, improving the product yield, and achieving the pattern accuracy required for application in the field of integrated circuit manufacturing. The above process can be performed in existing process equipment, will not significantly increase the cost and time of the imprinting process, and the entire preparation process is simple and easy to implement, suitable for large-scale application. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Shown is a process flow diagram of a typical nanoimprinting method.

[0032] Figure 2 Scanning electron microscope (SEM) image showing pattern-missing defects during the nanoimprint process.

[0033] Figure 3A Schematic diagram showing the formation of bubbles in the imprint glue during the filling step of the nanoimprint process.

[0034] Figure 3B Schematic diagram showing an imprint paste with pattern defects formed during the curing step of the nanoimprint process.

[0035] Figure 4 FIG. 4 is a process flow chart showing the nanoimprinting method in an embodiment of the present invention.

[0036] FIG. 5A to FIG. 5E Schematic diagram showing the structures obtained at each stage of the nanoimprint method in an embodiment of the present invention.

[0037] Fig. 6A and Figure 6B This is a schematic diagram of bubbles formed by capillary force in micro-grooves of a working mold during the filling process of the nanoimprint method according to an embodiment of the present invention; wherein, Fig. 6A A partial schematic diagram showing gas trapped in micro-grooves of a working mold at the initial stage of the filling process. Figure 6B A partial schematic diagram showing the process of filling in which the printed adhesive layer is adsorbed into the micro-grooves of the working mold by capillary force.

[0038] Figure 7 FIG. 5 is a scanning electron microscope (SEM) image of a pad-printed pattern obtained by the nanoimprint process according to the present invention.

[0039] Component number description

[0040] 10 substrate

[0041] 11 Working mold

[0042] 20 substrate

[0043] 21 Working mold

[0044] 220 embossed adhesive layer

[0045] 210b, 210b' Bubble

[0046] 220b Pattern loss defect

[0047] 21p Micro-nanostructure

[0048] 21t Micro Groove

[0049] 22p Pad printing pattern

[0050] P e pressure

[0051] F Direction of introduction of working gas

[0052] UV ultraviolet light DETAILED DESCRIPTION

[0053] The following is a description of the implementation of the present invention by means of specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0054] Please refer to Figures 3 to Figure 7 . It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no substantial technical significance. Any modification of the structure, change in the proportional relationship, or adjustment of the size, without affecting the effects and purposes that can be achieved by the present invention, should still fall within the scope of the technical content disclosed by the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of the implementation of the present invention without changes in the substantial technical content.

[0055] Generally, nanoimprinting processes include hot embossing, ultraviolet nanoimprinting and microcontact printing. During hot embossing, the process environment needs to be kept close to a vacuum environment to avoid distortion of the imprinted pattern caused by the presence of air bubbles. However, during the imprinting process in a non-vacuum environment, the gas originally present in the pores between the working mold and the substrate cannot be discharged in time and gathers into bubbles in the imprinted adhesive layer. FIG. 3A to FIG. 3B The schematic diagram of the bubble defect generated in the nanoimprint process of the comparative example of the present invention is shown as follows: Figure 3A As shown, at pressure P e Under the action of the working mold 11 and the substrate 10, the embossed adhesive is deformed to fill the pores in the working mold. The gas in the pores is not discharged in time, and bubbles 210b are formed in the embossed adhesive. The occupancy of the bubbles will cause the embossed adhesive to be unable to completely fill the relief pattern on the working mold; Figure 3B As shown, the bubble occupancy retained in the imprinted adhesive will cause reflection at the bubble interface (such as Figure 3B This will reduce the exposure dose actually received by the embossed adhesive near the interface, making the actual exposure dose received by the entire surface of the embossed adhesive inconsistent, causing some areas of the embossed adhesive to be not fully cured, and its strength is much lower than that of the cured embossed adhesive. As a result, the uncured embossed adhesive breaks during subsequent demolding, resulting in a graphic missing defect 220b in the pad print pattern 22p.

[0056] To this end, the inventors have proposed an improved nanoimprinting method after long-term research. After forming an imprinting adhesive layer on a substrate, the working mold and the substrate are squeezed toward each other so that the imprinting adhesive layer on the substrate fills the pores in the working mold. Then, the ambient gas is replaced by a working gas to increase the solubility of the working gas in the imprinting adhesive layer and the working mold, reduce the probability of bubbles generated during the imprinting process, and suppress pattern defects caused by bubbles.

[0057] Hereinafter, the nanoimprinting method provided by the present invention will be described in detail in conjunction with the attached drawings, which includes the following steps:

[0058] First, step S110 is performed to provide a substrate and form an embossing adhesive layer on the substrate.

[0059] Specifically, see Figure 5A The liquid imprint material is applied as a transfer medium to the substrate 20 by spin coating or spraying to form an imprint adhesive layer 220. The imprint adhesive layer may include a photoresist layer, including but not limited to a visible photoresist layer and an ultraviolet photoresist layer, such as polymethyl methacrylate (PMMA).

[0060] The term "substrate" as used herein refers to a substrate and a material layer to be patterned or a substrate surface to be patterned. As used herein, the term "substrate" includes a semiconductor substrate, such as a silicon substrate; a metal substrate, such as Au, Al, Ni; or an insulator substrate, such as SiO 2 , glass, quartz, polyethylene terephthalate PET, polyethylene naphthalate PEN, polycarbonate PC, sapphire.

[0061] As an example, the embossed adhesive layer also includes an optical functional material layer. Depending on the situation, the embossed adhesive layer includes one selected from the following optical functional material layers: an optical anti-reflection film located on the upper surface of the embossed adhesive layer to increase the energy utilization rate of the incident light entering the photoresist layer from the imprint template; an optical anti-reflection film located on the lower surface of the embossed adhesive layer to reduce the standing wave effect inside the photoresist during optical exposure, or the above two optical functional material layers are configured at the same time.

[0062] Next, step S120 is performed to place the working mold and the substrate with the embossed adhesive layer formed thereon in a sealed chamber, and introduce working gas into the sealed chamber to replace the original ambient gas.

[0063] Specifically, see Figure 5B Before applying pressure to at least one of the working mold 21 and the substrate 20, the working mold 21 and the substrate 20 formed with the embossed adhesive layer are placed in a sealed chamber, wherein the working mold 21 includes a pattern transfer layer having a micro-nano structure 21p, and a working gas is introduced into the sealed chamber to replace the original ambient gas, wherein the solubility of the introduced working gas in the embossed adhesive layer is greater than the solubility of the ambient gas in the embossed adhesive layer, wherein the micro-nano structure 21p includes a characteristic structure having a micrometer-level size or a nanometer-level size, such as a depression or a protrusion.

[0064] At least one of the working mold and the substrate is transparent to the radiation causing the photoresist to cure, and the material of the working mold includes Si, SiO 2 , Ni, transparent glass, perfluoropolyether PFPE, and polydimethylsiloxane PDMS.

[0065] Before or after the step of forming the embossed adhesive layer, the working mold and the substrate are placed in a sealed chamber, and the micro-nano structure in the pattern transfer layer is transferred to the embossed adhesive layer by using one or a combination of plate-to-plate embossing, roller-to-roller embossing, roller-to-plate embossing and step-by-step embossing. As an example, the working mold and the substrate are delivered to a step-by-step embossing device, and the embossed adhesive layer is applied to the transparent substrate by spraying using a coating mechanism, wherein the embossed adhesive layer includes an ultraviolet photoresist layer; then, a working gas is introduced into the gap between the working mold and the substrate, such as Figure 5B The working gas is shown introduced in direction F to displace the ambient gas.

[0066] Considering that when the embossed rubber layer is pressed into the pores between the working molds, the gas between the working molds and the embossed rubber layer will be captured and gathered into bubbles, where the smaller bubbles will tend to shrink in volume until they dissolve under the action of surface tension. However, due to the solubility of the ambient gas in the embossed rubber layer, when the gathered bubbles have an external dimension exceeding the critical size, the captured gas exceeds the gas solubility in the embossed rubber layer, resulting in bubble residue. The "external dimension" mentioned here refers to the length used to characterize the bubble or the maximum dimension in three-dimensional space, such as the bubble diameter.

[0067] The solubility under standard conditions (101 kPa, 20 ° C) is recorded as C a According to the definition of gas solubility, the maximum amount of C that can be dissolved in a unit volume of solvent is a unit volume of gas. According to Henry's law, the solubility of a gas in a solvent is usually proportional to the pressure of the gas. Therefore, when the gas pressure is P g The gas solubility at is:

[0068]

[0069] Among them, P a It is standard atmospheric pressure (101kPa).

[0070] According to the definition of gas solubility: the volume of gas when the gas pressure is saturated in 1 volume of solvent under standard atmospheric pressure conditions (101kPa) and at a certain temperature. It can be seen that gas solubility is not only related to the properties of the gas and solvent, but also to temperature and pressure: solubility generally decreases with increasing temperature, that is, it is nonlinear, and increases linearly with increasing pressure (Henry's law). Preferably, the type of working gas used to replace the ambient gas can be selected according to the following principle: by making the working gas have a greater gas solubility in the imprinted adhesive layer relative to the ambient gas.

[0071] As an example, the working gas includes CO 2 , He, H 2 The working gas may be introduced along the side of the working mold, or introduced in two directions or multiple directions from the periphery of the working mold toward the gap between the working mold and the substrate.

[0072] In this embodiment, the working gas introduced into the sealed chamber is selected from He, CO 2 One or a mixture of both.

[0073] Next, step S130 is performed, in which a working mold is placed in a sealed chamber with its pattern transfer layer in contact with the embossed adhesive layer, and pressure is applied to at least one of the working mold and the substrate, causing the embossed adhesive layer to deform and fill the pores between the micro-nano structures, thereby transferring the micro-nano structures in the pattern transfer layer to the embossed adhesive layer.

[0074] Figure 5C Schematic diagram of bubbles formed by the embossing adhesive and the gas captured in the working mold during step S140 of the nanoimprinting method according to an embodiment of the present invention. Specifically, the working gas is introduced into the sealed chamber, and the working mold 21 is simultaneously or successively attached to the embossing adhesive layer 220 with its pattern transfer layer, and the pressure P applied to the working mold and / or the substrate is used. e , so that the working mold 21 is pressed into the embossed adhesive layer 220, so that the embossed adhesive layer is deformed to fill the pores between the micro-nano structures, and the micro-nano structures 21p in the pattern transfer layer are transferred to the embossed adhesive layer. Figure 5C As shown, the bubbles 210b' gathered in the embossed adhesive layer after transfer tend to dissolve.

[0075] Fig. 6A and Figure 6B The schematic diagram is a schematic diagram of bubbles formed by capillary force in the micro-grooves of the working mold during the filling process of the nanoimprint method according to an embodiment of the present invention. Hereinafter, the filling process of the working mold with micro-nanoscale micro-grooves will be described in detail with reference to the diagram.

[0076] In the initial stage of the filling process, the working mold 21 is fitted with the embossed adhesive layer 220 by its micro-grooves, and the volume Vg of the gas trapped in the micro-grooves of the working mold is approximately equal to the volume V liq .

[0077] During the filling process, with the application of the embossing force, the embossed adhesive layer 220 is adsorbed into the micro-grooves of the working mold by the capillary force. Accordingly, the embossed adhesive layer is deformed to fill the micro-grooves 21t and capture the trapped gas in the micro-grooves to form bubbles 210b'.

[0078] Pressure e When the embossed rubber layer fills the pores (i.e., micro-grooves) between the micro-nano structures on the working mold under the action of, it can be regarded as a capillary phenomenon. According to the Young-Laplace equation, the additional gas pressure is:

[0079]

[0080] Among them, P g is the pressure inside the bubble, P wis the pressure inside the embossed rubber layer (equal to the working pressure of the working mold during the filling process), σ is the surface tension of the embossed rubber, θ is the tangent angle between the curved liquid surface of the embossed rubber and the side wall of the template, and R is the curvature radius of the curved liquid surface.

[0081] According to the surface tension theory, the theoretical maximum value of θ is 0°, and the minimum value of the bending radius of the embossed adhesive liquid surface is half of the micro-groove width l, that is, the minimum width inside the micro-groove of the working mold. Therefore, the additional pressure of the gas captured in the embossed adhesive layer during the filling process can have an equivalent relationship:

[0082] Combining the variants of equation 1 and equation 2, it can be seen that the maximum solubility of the gas in the imprinted adhesive layer is expressed as:

[0083]

[0084] According to the definition of solubility, the maximum volume of gas that can be dissolved under specific conditions is:

[0085] v g,max =v w ·C g Formula 4

[0086] When the embossed adhesive layer has sufficient solubility for the working gas used, as the micro-groove filling step proceeds, the gas captured by the embossed adhesive layer will gather and tend to dissolve, so that no bubbles remain in the embossed adhesive layer. It can be seen that the premise of no bubbles is:

[0087] C g ≥1

[0088] Combining formula 3, we can get:

[0089]

[0090] By rearranging formula 5, we can get:

[0091] Therefore, the necessary condition for no bubbles after the filling step is that the length of the micro groove of the working mold satisfies the relation 5. It can be further known from the equation that the length variable l of the micro groove has a maximum value l c , the value of which is uniquely determined by surface tension and gas solubility.

[0092]

[0093] When the size l of the micro groove is larger than l c When , the premise of the relationship 5 will not exist, that is, the necessary condition that there is no bubble in the imprinted glue layer after the filling step does not exist. c Defined as the critical size at which no bubbles appear after the filling step.

[0094] On this basis, it is assumed that the step of filling the pores in the working mold is performed in the original working environment. Limited by the solubility of the ambient gas in the imprinted adhesive layer, the bubbles formed in the imprinted adhesive layer when the working mold is pressed into the imprinted adhesive layer have a size greater than the critical size l c When the outer dimensions are , the bubbles containing the ambient gas are retained; accordingly, by introducing the working gas into the sealed chamber to replace the ambient gas, the bubbles formed in the working environment after the replacement also have a critical size l c′ .

[0095] In a preferred embodiment, the working gas used to replace the ambient gas is selected so that the bubbles formed in the embossed adhesive layer when the working mold is pressed into the embossed adhesive layer have a size smaller than the critical size l. c′ The dimensions are dissolved, and the critical dimension l c′ It can be expressed by formula 7:

[0096]

[0097] Among them, C a is the solubility of the working gas at standard atmospheric pressure, P a is the standard atmospheric pressure, σ is the solubility of the working gas in the imprinting glue, P w It is the gas pressure in the working environment.

[0098] Furthermore, in the working environment after replacement, the pores formed in the embossed adhesive layer during the filling process of the pores between the micro-nano structures have a critical size l c′ In the original working environment, the pores formed by the embossed adhesive layer capturing the ambient gas have a critical size l c1 , where the critical size l c1 It can be expressed by formula 8:

[0099]

[0100] Among them, C a1 is the solubility of the original ambient gas under standard atmospheric pressure, P a is the standard atmospheric pressure, σ 1 is the solubility of the original ambient gas in the imprinting glue, P w1 is the gas pressure in the original working environment;

[0101] The working gas is selected so that the solubility of the working gas in the imprinted adhesive layer is greater than the solubility of the original ambient gas in the imprinted adhesive layer, thereby satisfying l c′ > c1 .

[0102] As a preferred implementation, the working gas is selected so that the bubbles formed by capturing the working gas in the imprinted adhesive layer in the replaced working environment have a critical size l c′ , critical size l c′ The characteristic size of the pores between the micro-nano structures on the working mold is larger than that of the pores between the micro-nano structures on the working mold, so that the gas captured by the imprinted glue layer can be completely dissolved in the working environment after replacement, further reducing the probability of bubble defects.

[0103] As an example, one or a combination of airbags, pressure plates, and embossing rollers are used to apply pressure to the working mold and / or the substrate, and the working mold can move relative to the substrate; or, the working mold and the substrate can be set to be relatively stationary. In this embodiment, the step-by-step embossing device performs step S130, applies pressure to the substrate using an embossing roller, and / or applies pressure to the working mold using an airbag, so that the embossed adhesive layer 220 is pressed into the working mold 21, thereby improving the uniformity of the applied stress. When the embossed adhesive layer includes an ultraviolet photoresist layer, the pores between the micro-nano structures 21p are mainly filled with the ultraviolet photoresist.

[0104] Furthermore, in the process of filling the pores between the micro-nano structures with the embossed adhesive layer, the embossed adhesive layer and the working mold are cooled by introducing a cooled working gas. Since the gas solubility decreases with the increase in ambient temperature, the cooled working gas is used to reduce the influence of heat generated by the curing reaction, thereby keeping the gas solubility σ basically unchanged during the curing process.

[0105] Next, step S140 is performed to solidify the transferred imprinted adhesive layer under the condition of maintaining the atmosphere containing the working gas to form a pad printing pattern complementary to the micro-nano structure.

[0106] Specifically, the transferred embossed adhesive layer is exposed, wherein the embossed adhesive layer includes a photoresist layer, so as to cause the photoresist layer to be cross-linked and cured.

[0107] As an example, the photoresist layer is selected to be an ultraviolet photoresist, and an ultraviolet light source is used to expose the photoresist layer to solidify the ultraviolet photoresist to form a pad printing pattern complementary to the micro-nano structure.

[0108] In this embodiment, the step-by-step imprinting device includes an unwinding mechanism, a rewinding mechanism, and a guide roller, and the substrate is intermittently transported forward by the unwinding mechanism and the guide roller.

[0109] Furthermore, during the curing process of the embossed adhesive layer, the substrate 20 , the embossed adhesive layer 220 and the working mold 21 are subjected to a cooling treatment, and the cooling treatment can be achieved by introducing a cooled working gas into the gap between the working mold and the substrate.

[0110] As an example, the atmosphere containing the working gas is maintained by monitoring the pressure in the sealed chamber and the composition of the atmosphere, and adjusting the replacement rate of the working gas.

[0111] Next, step S150 is performed to release the working mold from the pad printing pattern.

[0112] In this embodiment, the working mold 21 is released from the pad printing pattern 22p by curling. Figure 5E ; Then, stop introducing the working gases He and CO 2 One or a mixture of both, thereby completing the nanoimprint method.

[0113] Based on the above technical solution, before performing the step of filling the pores between the transfer patterns, the ambient gas is replaced by the working gas, and the solubility of the working gas in the transfer material and the working mold is increased relative to the original ambient gas, which is greater than the probability of reducing bubble defects.

[0114] Embodiment 2

[0115] The present embodiment provides a nanoimprinting method, which includes the following steps S210 to S240. Steps S210 to S250 in the nanoimprinting method of the present embodiment can be performed using steps similar to the nanoimprinting method described in the previous embodiment. The main difference is that steps S220 to S240 are preferably performed in a plate-to-plate nanoimprinting device, and in step S230, an electro-cooling method is used to synchronously cool the substrate, the imprinting glue layer and the working mold.

[0116] S210: providing a substrate, and forming an embossed adhesive layer on the substrate;

[0117] S220: placing a working mold and a substrate formed with an embossed adhesive layer in a sealed chamber, wherein the working mold includes a pattern transfer layer having a micro-nano structure, introducing a working gas into the sealed chamber to replace the original ambient gas, wherein the solubility of the introduced working gas in the embossed adhesive layer is greater than the solubility of the ambient gas in the embossed adhesive layer;

[0118] S230: in a sealed chamber, with the working mold having its pattern transfer layer attached to the embossed adhesive layer, applying pressure to at least one of the working mold and the substrate, so that the embossed adhesive layer is deformed to fill the pores between the micro-nano structures, and the micro-nano structures in the pattern transfer layer are transferred to the embossed adhesive layer;

[0119] S240: curing the transferred imprinted adhesive layer under the condition of maintaining an atmosphere containing a working gas to form a pad printing pattern complementary to the micro-nano structure;

[0120] S250: demoulding the working mold from the pad printing pattern.

[0121] After step S210, step S220 is performed, which includes: delivering the working mold and the substrate with the imprinted adhesive layer formed thereon to a plate-to-plate imprinting device, the plate-to-plate imprinting device including a sealed chamber, an imprinting mechanism and a suction cup, and placing the substrate on the imprinting mechanism using the suction cup.

[0122] At step S230, the stamping mechanism includes a pressure plate for applying an extrusion force to the substrate, and applying pressure to at least one of the working mold and the substrate through the pressure plate to press the stamped adhesive layer into the pores between the micro-nano structures, wherein the stamped adhesive layer includes an ultraviolet-sensitive stamped adhesive layer, and the pores between the micro-nano structures are mainly filled with ultraviolet-sensitive stamped adhesive.

[0123] In step S240, the ultraviolet photoresist layer is exposed by using an ultraviolet light source, and the substrate, the imprinting adhesive layer and the working mold are simultaneously cooled by electrocooling.

[0124] In this embodiment, the suction cup is equipped with a cooling component. After the operation of filling the pores between the micro-nano structures is performed, step S240 is performed in the following manner: the cooling component is powered on to start the cooling operation, and the substrate, the imprinted adhesive layer, and the working mold are synchronously cooled by the cooling component to ensure that the working gas has sufficient solubility σ in the imprinted adhesive layer to maintain the critical size l of the bubbles in the imprinted adhesive layer. c′ The temperature is larger than the characteristic size of the micro-nano structure in the working mold, thereby reducing the influence of heat generated by the curing reaction, for example, the substrate, the imprinted adhesive layer, and the working mold are maintained at a constant temperature for a period of time until the filling process is completed.

[0125] As an additional or alternative method, the step of cooling the working mold, the embossed adhesive layer and the substrate can be performed before the demoulding step of the pad printed pattern; after removing the working mold, the cooling function of the cooling component is turned off.

[0126] The nanoimprint method is used to make an anti-etching pattern layer, a pattern transfer layer, an optical functional layer and a release film with a micro-nano structure, wherein the optical functional layer includes but is not limited to an optical super-surface film and an anti-reflection film. The nanoimprint method of the present invention is used to perform pattern transfer, which can improve the replication accuracy of the pad printing pattern and avoid pattern missing defects.

[0127] This embodiment further provides a nanoimprint mold, wherein the nanoimprint mold comprises a pad printing pattern produced by the aforementioned nanoimprint method, wherein the nanoimprint mold comprises one of the soft template and the hard template.

[0128] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A nanoimprinting method, characterized in that: The following steps are involved: Providing a substrate, forming an embossed adhesive layer on the substrate, wherein the embossed adhesive layer includes a photoresist layer; Placing a working mold and the substrate formed with an embossed adhesive layer in a sealed chamber, wherein the working mold includes a pattern transfer layer having a micro-nano structure, introducing a working gas into the sealed chamber to replace the original ambient gas, wherein the solubility of the introduced working gas in the embossed adhesive layer is greater than the solubility of the ambient gas in the embossed adhesive layer and the working mold; The working mold is placed in a state where its micro-nano structure is attached to the embossed adhesive layer, and pressure is applied to at least one of the working mold and the substrate, so that the embossed adhesive layer is deformed in the replaced sealed chamber to fill the pores between the micro-nano structures, and the micro-nano structures in the pattern transfer layer are transferred to the embossed adhesive layer, and at the same time, the working gas in the pores is captured to form bubbles, and the working gas is selected so that the critical size of the bubbles formed in the process of filling the pores between the micro-nano structures is l c′ The size of the bubbles formed in the embossed adhesive layer is smaller than the critical size l c′ The dimensions are dissolved, and the critical size l c′ It is expressed by the following formula: Among them, C a is the solubility of the working gas at standard atmospheric pressure, P a is the standard atmospheric pressure, σ is the solubility of the working gas in the imprinting glue, P w is the gas pressure in the working environment; Under the condition of maintaining an atmosphere containing a working gas, the transferred embossed adhesive layer is solidified to form a pad printing pattern complementary to the micro-nano structure; The working mold is demoulded from the pad printing pattern.

2. The nanoimprint method according to claim 1, characterized in that: The ambient gas is replaced by introducing the working gas toward the gap between the working mold and the substrate, wherein the working gas includes one or a combination of CO 2 , He, and H 2 .

3. The nanoimprint method according to claim 2, characterized in that: Before or after the step of forming the embossed adhesive layer, the working mold and the substrate are placed in the sealed chamber, wherein the pad printing pattern is formed by one or a combination of a plate-to-plate embossing method, a roller-to-roll embossing method, a roller-to-plate embossing method and a step-by-step embossing method.

4. The nanoimprint method according to claim 1, characterized in that: After the step of filling the pores between the micro-nano structures, the method further comprises: In the sealed chamber, the photoresist layer is exposed by using an ultraviolet light source to solidify the transferred imprinted adhesive layer, wherein the photoresist layer is selected to be an ultraviolet photoresist.

5. The nanoimprint method according to claim 1, characterized in that: The embossed adhesive layer includes a photoresist layer and an optical functional material layer, and the step of filling the pores between the micro-nano structures includes: One or a combination of an air bag, a pressure plate and an embossing roller is used to apply pressure to at least one of the working mold and the substrate, and the embossed adhesive layer and the working mold are cooled by introducing cooled working gas.

6. The nanoimprint method according to claim 1, characterized in that: The step of curing the transferred embossed adhesive layer further includes: The substrate is placed on the imprinting mechanism by using a suction cup, and the substrate, the imprinting adhesive layer and the working mold are subjected to temperature reduction treatment by means of electrocooling.

7. The nanoimprint method according to claim 1, characterized in that: The material of the working mold includes one or a combination of Si, SiO2, Ni, transparent glass, perfluoropolyether PFPE, and polydimethylsiloxane PDMS.

8. The nanoimprint method according to any one of claims 1 to 7, characterized in that: The method of maintaining the atmosphere containing the working gas includes: monitoring the pressure and atmosphere composition in the sealed chamber, and adjusting the replacement rate of the working gas.

9. The nanoimprint method according to any one of claims 1 to 8, characterized in that: Used to make anti-etching pattern layers, pattern transfer layers, optical functional layers and release films with micro-nano structures.

10. A nanoimprint mold, characterized in that: The nanoimprint mold comprises a transfer pattern layer, and the transfer pattern layer is prepared by the nanoimprint method according to any one of claims 1 to 8.

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