Nanoimprint master template, nanoimprint negative template, preparation method of nanoimprint master template and nanoimprint negative template, and nanoimprint alignment system
By preparing nanoimprint master templates and master negative templates, and combining them with optical microscope-assisted alignment, the problem of low alignment accuracy in nanoimprint technology was solved, achieving high-precision nanoimprint alignment and improving the precision of chip manufacturing.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-23
- Publication Date
- 2026-03-24
AI Technical Summary
Current nanoimprint technology has low alignment accuracy, making it difficult to achieve high-precision chip manufacturing.
By employing a nanoimprint master template and a master negative template preparation method, combined with an optical microscope-assisted alignment device, alignment patterns are formed on the master template and the master negative template using photolithography, achieving high-precision alignment imprinting.
Without increasing additional costs, high-precision nanoimprint alignment was achieved, which multiplied the existing photolithography overlay accuracy, reaching an alignment accuracy of 200nm.
Smart Images
Figure CN121721900A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of nanoimprint alignment technology, and specifically relates to a nanoimprint master template, a master negative template, their preparation method, and a nanoimprint alignment system. Background Technology
[0002] Nanoimprint lithography (NIL) is a novel micro-nano fabrication technology that transfers intricate patterns onto a substrate through physical imprinting. Compared to traditional photolithography, nanoimprint lithography offers significant advantages, particularly in fabricating extremely small patterns. This technology is not limited by light diffraction and can achieve patterns smaller than 10 nm, far exceeding the resolution limits of traditional photolithography. This makes nanoimprint lithography a technology with enormous application potential in chip manufacturing.
[0003] Nanoimprint lithography can fabricate smaller, more intricate chip structures with resolutions below 10 nm, far surpassing traditional photolithography. Because it eliminates the need for light sources and lenses, nanoimprint lithography offers significant advantages in equipment and maintenance costs. In contrast, traditional photolithography requires expensive equipment and complex processes to expose chip patterns, while nanoimprint lithography only requires simple template and imprinting operations. Furthermore, nanoimprint lithography excels at fabricating simple three-dimensional micro / nano structures, such as blazed gratings, Fresnel lenses, and honeycomb structures, which have important applications in optics and electronics. Additionally, nanoimprint lithography overcomes the challenges of processing curved or flexible substrates with traditional photolithography, opening up new possibilities for the application of these special substrates.
[0004] The second-generation nanoimprint semiconductor manufacturing equipment, FPA-5510iZ2, employs ultraviolet light curing imprinting technology, boasting advantages such as high precision, high stability, and high production efficiency. This marks the transition of nanoimprint technology from the laboratory to industrialization, and it may pose a competition and challenge to existing EUV lithography systems. Several companies are also actively promoting the research and application of nanoimprint technology, aiming to improve the efficiency and cost of chip manufacturing. Technological innovation in the chip manufacturing field will continue to drive industry development, and nanoimprint technology, as an emerging micro-nano fabrication technology, possesses enormous potential and prospects.
[0005] The principle of nanoimprint alignment refers to the process of transferring circuit patterns from the chip to a UV imprinting adhesive during chip fabrication. These patterns are then transferred to a silicon wafer through chemical etching and other processes. This process utilizes nanoimprint alignment overlay technology to transfer the circuit patterns from the chip to the UV imprinting adhesive. Nanoimprint alignment technology is a highly precise technique requiring equipment and materials such as an imprinter, an imprinting template, and UV imprinting adhesive. During the overlay process, the imprinting template is first placed on the imprinter, and then the UV imprinting adhesive is spin-coated onto the silicon wafer. Next, the silicon wafer is placed on the imprinter, and through exposure and development processes, the circuit patterns on the imprinting template are transferred to the photoresist. Alignment is a crucial step in the alignment and overlay process; it refers to the process of transferring the circuit patterns from the imprinting template to the UV imprinting adhesive, requiring an alignment system. Currently, the nanoimprint alignment accuracy achievable in China is 3–5 micrometers. With continuous technological evolution and improvement, nanoimprint technology is expected to play a significant role in chip manufacturing, providing strong support for the development of the digital age.
[0006] Therefore, an alignment imprinting method based on nanoimprinting is provided. Summary of the Invention
[0007] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a nanoimprint master template, a master negative template, a method for preparing the same, and a nanoimprint alignment system to solve the problem of low nanoimprint alignment accuracy in the prior art.
[0008] To achieve the above and other related objectives, the present invention provides a method for preparing a nanoimprint master template, the method comprising the following steps:
[0009] S11. Provide a silicon wafer as a substrate, and spin-coat photoresist onto the silicon wafer;
[0010] S12. Place the photomask on top of the silicon wafer coated with photoresist, ensuring that the overlay marks on the photomask are aligned with the reference marks on the silicon wafer. Use photolithography to expose and develop the photomask to reveal the first main pattern and the first alignment pattern area on the photoresist. Then bake the hard film and transfer the pattern formed on the photoresist to the silicon wafer by dry etching.
[0011] S13. Remove residual photoresist to form a master template.
[0012] Preferably, in step S11, before spin-coating photoresist onto the silicon wafer, the silicon wafer needs to undergo pretreatment, which specifically includes:
[0013] The silicon wafer is cleaned by immersing it in a cleaning solution at 70°C to 80°C, and then the surface of the silicon wafer is treated with hexamethyldisilazane. The cleaning solution includes hydrochloric acid with a mass concentration of 73%, hydrogen peroxide with a mass concentration of 73%, and water, and the mass ratio of the three is 1:1:6.
[0014] Preferably, in step S12, the minimum linewidth of the first main pattern is 2 μm; the first alignment pattern area includes multiple sets of moiré gratings and annular moiré stripes with different linewidth combinations; the double period of the moiré grating is P1 = 10 μm, P2 = 15 μm or P1 = 10 μm, P2 = 12 μm or P1 = 10 μm, P2 = 20 μm, and the linewidth of the annular moiré stripes is 5 μm to 10 μm.
[0015] Preferably, the master template formed in step S13 requires further post-processing, specifically:
[0016] The master template is placed in an ozone or oxygen atmosphere and subjected to plasma bombardment treatment, and then treated with perfluorodecyltrichlorosilane for anti-sticking, resulting in a master template with a surface contact angle greater than 100°.
[0017] Preferably, the thickness of the photoresist in step S11 is h, and the thickness of the master template formed in step S13 is H, and the relationship between the two is as follows:
[0018] In the same etching atmosphere, v1 is the etching rate of the photoresist, and v2 is the etching rate of elemental silicon.
[0019] The present invention also provides a nanoimprint master template, characterized in that: the master template is prepared by the preparation method of the nanoimprint master template according to any one of claims 1 to 5.
[0020] This invention also provides a method for preparing a nanoimprint master negative template, wherein the master negative template is prepared based on the above-mentioned nanoimprint master template, and the preparation method includes the following steps:
[0021] S21. Provide a transparent dielectric silicon dioxide or quartz as a substrate, and spin-coat photoresist on the substrate;
[0022] S22. Using the master template as a mask, after exposure and development, the main pattern and alignment pattern on the master template are displayed on the photoresist.
[0023] S23. A metal film layer is formed by depositing a coating on the developed pattern.
[0024] S24. After removing the photoresist, the substrate is etched using the metal film as a mask to transfer the pattern structure on the metal film onto the substrate, forming a master negative template.
[0025] Preferably, the coating method in step S23 includes one or a combination of resistance thermal evaporation, electron beam evaporation, and magnetron sputtering; the material of the formed metal film is one of Al, Cr, Ag, and Au.
[0026] Preferably, the parent negative template formed in step S24 needs to be post-processed, specifically: the parent negative template is placed in an atmosphere filled with ozone or oxygen and subjected to plasma bombardment treatment, and then perfluorodecyltrichlorosilane is used to perform an anti-sticking treatment on the parent negative template.
[0027] Preferably, the thickness of the metal film layer formed in step S23 is h1, and the height of the mother negative template formed in step S24 is H1, and the relationship between the two is as follows:
[0028] In the same etching atmosphere, v3 is the etching rate of the metal film, and v4 is the etching rate of the substrate.
[0029] Preferably, the pattern structure on the mother negative template includes a second main pattern and a second alignment pattern area. The second main pattern is consistent with the first main pattern in terms of overprinting. The moiré grating in the second alignment pattern area is mirror-symmetrical with the moiré grating in the first alignment pattern area. The annular moiré stripes in the second alignment pattern area are consistent with the annular moiré stripes in the first alignment pattern area.
[0030] The present invention also provides a nanoimprint master negative template, which is prepared by the above-described method for preparing a nanoimprint master negative template.
[0031] In addition, the present invention also provides a nanoimprint alignment system, the nanoimprint system comprising a master template, a master negative template and an alignment module; wherein, the master template is a master template prepared by the above-described method for preparing a nanoimprint master template, and the master negative template is a master negative template prepared by the above-described method for preparing a nanoimprint master negative template.
[0032] Preferably, the alignment module includes an optical microscope, on which the negative template is covered and coated with nanoimprint adhesive. The position of the negative template is adjusted under the optical microscope through the negative template so that the moiré grating and the annular grating are aligned between the negative template and the negative template.
[0033] As described above, the alignment imprinting method based on nanoimprinting of the present invention has the following beneficial effects:
[0034] The nanoimprint-based alignment and imprinting method in this invention uses existing ordinary photolithography equipment combined with an optical structure-assisted alignment device to achieve high-precision alignment and imprinting without increasing additional costs. It achieves a precision many times higher than the original photolithography overlay precision, filling the gap in the domestic nanoimprint alignment technology field (currently, the nanoimprint alignment precision that can be achieved domestically is 3-5 micrometers). The overlay marks transferred from the photolithography process include multiple cross marks and moiré stripes, and the nanoimprint can be manually aligned with a precision of 200nm using an optical microscope. Attached Figure Description
[0035] Figure 1 The image shown is a light microscope image of the alignment mark on the side of the parent negative template adjacent to the parent template after alignment imprinting, in the alignment imprinting method based on nanoimprinting of the present invention.
[0036] Figure 2 The image shown is a light microscope image of the alignment mark on the side of the master template adjacent to the master negative template after alignment imprinting, in the alignment imprinting method based on nanoimprinting of the present invention.
[0037] Figure 3 The image shown is a moiré fringe grating characterization diagram under an optical microscope in the alignment imprinting method based on nanoimprinting of this invention.
[0038] Figure 4 The image shown is a characterization diagram of an annular moiré grating under an optical microscope in the alignment imprinting method based on nanoimprinting of this invention.
[0039] Figure 5 The image shows the alignment and imprinting accuracy measurement results under an optical microscope in the alignment and imprinting method based on nanoimprinting of this invention.
[0040] Figure 6 The image shows the alignment and imprinting accuracy measurement results under SEM in the alignment and imprinting method based on nanoimprinting of this invention. Detailed Implementation
[0041] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.
[0042] Please see Figures 1-6It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.
[0043] This invention provides a method for preparing a nanoimprint master template, characterized in that the method for preparing the master template includes the following steps:
[0044] S11. Provide a silicon wafer as a substrate, and spin-coat photoresist onto the silicon wafer;
[0045] S12. Place the photomask on top of the silicon wafer coated with photoresist, ensuring that the overlay marks on the photomask are aligned with the reference marks on the silicon wafer. Use photolithography to expose and develop the photomask to reveal the first main pattern and the first alignment pattern area on the photoresist. Then bake the hard film and transfer the pattern formed on the photoresist to the silicon wafer by dry etching.
[0046] S13. Remove residual photoresist to form a master template.
[0047] Specifically, in step S12, the platform on which the silicon wafer is located is moved, and microscopic observation is used to ensure that the overlay marks on the photomask are aligned with the reference marks on the silicon wafer. Preferably, the silicon wafer is moved by a lead screw, which provides high precision and a relatively balanced overall platform cost. The pre-designed pattern on the photomask includes a first main pattern and a first alignment pattern area, which is the overlay mark. A hardened film is then baked to improve the thermal stability and adhesion of the photoresist, preparing it for subsequent etching processes. Preferably, dry etching techniques include RIE etching or ICP RIE etching. In step S13, removing residual photoresist involves immersing the silicon wafer in photoresist solvent and then ultrasonically treating it to completely remove the residual photoresist, resulting in a silicon grating master template with only the pattern structure.
[0048] In addition, conventional photolithography is used to prepare the nanoimprint master template, and the alignment pattern is used to ensure precise alignment in the subsequent nanoimprinting process.
[0049] As an example, in step S11, before spin-coating photoresist onto the silicon wafer, the silicon wafer needs to be pre-treated. The pre-treatment specifically includes: immersing the silicon wafer in a cleaning solution at 70℃~80℃ (e.g., 70℃, 72℃, 74℃, 76℃, 78℃, 80℃, etc.) to clean it, and then treating the surface of the silicon wafer with hexamethyldisilazane (HDMS); the cleaning solution includes hydrochloric acid with a mass concentration of 73%, hydrogen peroxide with a mass concentration of 73%, and water, and the mass ratio of the three is 1:1:6.
[0050] Specifically, during the immersion of silicon wafers in the cleaning solution, the pH value of the cleaning solution needs to be maintained within the range of 2 to 5. This pretreatment of the silicon wafers is used to remove alkali metal ions and Al2O3 adhering to their surface. +3 Fe +3 Mg +2 To prevent the formation of NH4OH insoluble hydroxide cations in the alkaline solution, thus further improving the integrity of subsequent pattern transfer; after cleaning, the surface of the silicon wafer is treated with HDMS. HDMS reacts with the silicon dioxide on the surface of the silicon wafer, helping the photoresist to adhere better to the surface of the silicon wafer and preventing the photoresist from falling off.
[0051] As an example, in step S12, the minimum linewidth of the first main pattern is 2μm; the first alignment pattern area includes multiple sets of moiré gratings and annular moiré stripes with different linewidth combinations; the double period of the moiré grating is P1 = 10μm, P2 = 15μm or P1 = 10μm, P2 = 12μm or P1 = 10μm, P2 = 20μm; the linewidth of the annular moiré stripes is 5μm to 10μm.
[0052] Specifically, the template has two types of patterns: one is the main pattern, such as logic circuits and optical waveguides, and the other is the alignment pattern, such as crosshair verniers, moiré gratings, and annular moiré stripes; the line width of the annular moiré stripes can include 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, etc.
[0053] As an example, the master template formed in step S13 still requires post-processing steps, specifically:
[0054] The master template is placed in an ozone or oxygen atmosphere and subjected to plasma bombardment treatment, and then treated with perfluorodecyltrichlorosilane for anti-sticking, resulting in a master template with a surface contact angle greater than 100°.
[0055] Specifically, the master template is placed in an atmosphere filled with ozone or oxygen. Plasma ionization generates oxygen plasma inside the device. At this time, the gas atmosphere is in a high-energy state and highly active, which is suitable for chemical bonding. When the high-energy oxygen plasma comes into contact with the silicon wafer, the silicon layer on the surface will react chemically with it to become silicon dioxide.
[0056] As an example, the thickness of the photoresist in step S11 is h, and the thickness of the master template formed in step S13 is H. The relationship between the two is as follows:
[0057] In the same etching atmosphere, v1 is the etching rate of the photoresist, and v2 is the etching rate of elemental silicon.
[0058] The present invention also provides a nanoimprint master template, which is prepared by the above-described method for preparing a nanoimprint master template.
[0059] This invention also provides a method for preparing a nanoimprint master negative template, wherein the master negative template is prepared based on the above-mentioned nanoimprint master template, and the preparation method includes the following steps:
[0060] S21. Provide a transparent dielectric silicon dioxide or quartz as a substrate, and spin-coat photoresist on the substrate;
[0061] S22. Using the master template as a mask, after exposure and development, the main pattern and alignment pattern on the master template are displayed on the photoresist.
[0062] S23. A metal film layer is formed by depositing a coating on the developed pattern.
[0063] S24. After removing the photoresist, the substrate is etched using a metal film as a mask to transfer the pattern structure on the metal film onto the substrate, forming a master negative template.
[0064] Specifically, a highly transparent and flat silicon dioxide or quartz substrate is provided. A layer of photoresist is uniformly spin-coated onto the substrate. A master template is placed on the photoresist-coated substrate as a mask. The substrate is exposed using ultraviolet light, causing the photoresist to undergo a photochemical reaction under the mask pattern. After exposure, the substrate is developed to reveal the desired pattern on the photoresist. A metal film is then deposited on the developed pattern using a deposition technique. This metal film serves as a mask in the next etching process, allowing for wet etching of the substrate. After etching, the metal film is removed, and the structure on the metal film is transferred to the substrate, ultimately forming the desired master negative template structure on a transparent medium.
[0065] As an example, the coating method in step S23 includes one or a combination of resistance thermal evaporation, electron beam evaporation, and magnetron sputtering; the material of the formed metal film is one of Al, Cr, Ag, and Au.
[0066] As an example, the parent negative template formed in step S24 needs to be post-processed, specifically: the parent negative template is placed in an atmosphere filled with ozone or oxygen and subjected to plasma bombardment treatment, and then perfluorodecyltrichlorosilane is used to perform anti-sticking treatment on the parent negative template.
[0067] As an example, the thickness of the metal film layer formed in step S23 is h1, and the height of the parent negative template formed in step S24 is H1. The relationship between the two is as follows:
[0068] In the same etching atmosphere, v3 is the etching rate of the metal film, and v4 is the etching rate of the substrate.
[0069] As an example, the pattern structure on the mother negative template includes a second main pattern and a second alignment pattern area. The second main pattern is consistent with the first main pattern in overprinting. The moiré grating in the second alignment pattern area is mirror-symmetrical with the moiré grating in the first alignment pattern area. The annular moiré stripes in the second alignment pattern area are consistent with the annular moiré stripes in the first alignment pattern area.
[0070] The present invention also provides a nanoimprint master negative template, which is prepared by the above-described method for preparing a nanoimprint master negative template.
[0071] In addition, the present invention also provides a nanoimprint alignment system, which includes a master template, a master negative template and an alignment module; wherein, the master template is a master template prepared by the above-mentioned method for preparing a nanoimprint master template, and the master negative template is a master negative template prepared by the above-mentioned method for preparing a nanoimprint master negative template.
[0072] As an example, the alignment module includes an optical microscope, which covers a master negative template coated with nanoimprint adhesive. Through the master negative template, the position of the master negative template is adjusted under the optical microscope to align the moiré fringe grating and the annular grating between the master template and the master negative template.
[0073] Specifically, moiré gratings and annular moiré stripes are used as alignment marks to provide visual feedback, aligning moiré gratings with each other and annular gratings with each other. Only after the gratings are aligned can a clear, periodic grating be observed, rather than a distorted pattern. During alignment, an optical calibration module is also used, which includes crosshairs of various line widths. The alignment is further achieved by observing whether the crosshairs are aligned one by one through a microscope.
[0074] Preferably, the optical microscope has a maximum magnification of 200x.
[0075] In a specific embodiment of the present invention, existing ordinary photolithography equipment is used in combination with an optical structure-assisted alignment device to achieve high-precision alignment and imprinting without increasing additional costs. The accuracy is several times higher than the original photolithography overlay accuracy. With the original optical mirror alignment accuracy of 1μm, imprinting alignment of about 200nm can be achieved.
[0076] See Figure 1 and Figure 2The images show optical microscopic representations of the alignment marks on the side of the negative template adjacent to the mother template after imprinting, and the alignment marks on the side of the mother template adjacent to the negative template. During the imprinting process, the upper mother template is on the top surface, and the lower mother negative template is on the bottom surface. Although the two are in direct contact during imprinting, there is still imprinting adhesive in between, with a thickness of approximately 1 μm. Under an optical microscope, a height of 1 μm requires refocusing, and it is unlikely that the focus of the optical microscope can be focused on both the upper and lower surfaces simultaneously. Therefore... Figure 1 It is a structure focused on a transparent dielectric substrate (the main part is black). Figure 2 It is a structure focused on the silicon substrate (the main part is white).
[0077] See Figure 3 This is a characterization image of a moiré fringe grating under an optical microscope. The image shows the characterization result after the moiré fringes on the parent template and the parent negative template are overlapped. Some alternating bright and dark stripes can be seen, which are moiré fringes.
[0078] See Figure 4 This is a characterization image of an annular moiré fringe grating under an optical microscope, which can more conveniently display rotational alignment deviations in the plane.
[0079] See Figure 5 The alignment and imprinting accuracy measurement results under an optical microscope show the alignment error of the main pattern on the transparent substrate after moiré fringe alignment. The bottom image shows the pattern on the transparent substrate, and the top image shows the pattern on the master template. The alignment error under the optical microscope is within 1.5 μm, but this also includes measurement and etching errors.
[0080] See Figure 6 The alignment error accuracy is measured by calibrating the distance of the cross-section of the alignment pattern to obtain the alignment imprint accuracy measurement results under SEM.
[0081] In summary, the nanoimprint-based alignment method of this invention utilizes existing conventional photolithography equipment combined with an optical structure-assisted alignment device to achieve high-precision alignment without increasing additional costs. It achieves a precision several times higher than the original photolithography overlay accuracy, filling a gap in the domestic nanoimprint alignment technology field (currently, the achievable nanoimprint alignment accuracy in China is 3-5 micrometers). The overlay marks transferred from the photolithography process include multiple cross marks and moiré patterns, which can be manually aligned with a nanoimprint precision of 200nm using an optical microscope. Therefore, this invention effectively overcomes the various shortcomings of existing technologies and has high industrial application value.
[0082] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can 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 those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.
Claims
1. A method for preparing a nanoimprint master template, characterized in that: The method for preparing the master template includes the following steps: S11. Provide a silicon wafer as a substrate, and spin-coat photoresist onto the silicon wafer; S12. Place the photomask on top of the silicon wafer coated with photoresist, ensuring that the overlay marks on the photomask are aligned with the reference marks on the silicon wafer. Use photolithography to expose and develop the photomask to reveal the first main pattern and the first alignment pattern area on the photoresist. Then bake the hard film and transfer the pattern formed on the photoresist to the silicon wafer by dry etching. S13. Remove residual photoresist to form a master template.
2. The method for preparing the nanoimprint master template according to claim 1, characterized in that: In step S11, before spin-coating photoresist onto the silicon wafer, the silicon wafer needs to undergo pretreatment, which specifically includes: The silicon wafer is cleaned by immersing it in a cleaning solution at 70°C to 80°C, and then the surface of the silicon wafer is treated with hexamethyldisilazane. The cleaning solution includes hydrochloric acid with a mass concentration of 73%, hydrogen peroxide with a mass concentration of 73%, and water, and the mass ratio of the three is 1:1:
6.
3. The method for preparing the nanoimprint master template according to claim 1, characterized in that: In step S12, the minimum linewidth of the first main pattern is 2μm; the first alignment pattern area includes multiple sets of moiré gratings and annular moiré stripes with different linewidth combinations; the double period of the moiré grating is P1 = 10μm, P2 = 15μm or P1 = 10μm, P2 = 12μm or P1 = 10μm, P2 = 20μm, and the linewidth of the annular moiré stripes is 5μm to 10μm.
4. The method for preparing the nanoimprint master template according to claim 1, characterized in that: The master template formed in step S13 still requires post-processing steps, specifically: The master template is placed in an ozone or oxygen atmosphere and subjected to plasma bombardment treatment, and then treated with perfluorodecyltrichlorosilane for anti-sticking, resulting in a master template with a surface contact angle greater than 100°.
5. The method for preparing the nanoimprint master template according to claim 1, characterized in that: The thickness of the photoresist in step S11 is h, and the thickness of the master template formed in step S13 is H. The relationship between the two is as follows: In the same etching atmosphere, v1 is the etching rate of the photoresist, and v2 is the etching rate of elemental silicon.
6. A nanoimprint master template, characterized in that: The master template is prepared by the method of preparing the nanoimprint master template according to any one of claims 1 to 5.
7. A method for preparing a nanoimprint master negative template, characterized in that: The negative template is prepared based on the nanoimprint template described in claim 6, and the preparation method includes the following steps: S21. Provide a transparent dielectric silicon dioxide or quartz as a substrate, and spin-coat photoresist on the substrate; S22. Using the master template as a mask, after exposure and development, the main pattern and alignment pattern on the master template are displayed on the photoresist. S23. A metal film layer is formed by depositing a coating on the developed pattern. S24. After removing the photoresist, the substrate is etched using the metal film as a mask to transfer the pattern structure on the metal film onto the substrate, forming a master negative template.
8. The method for preparing the nanoimprint master negative template according to claim 7, characterized in that: The coating method described in step S23 includes one or a combination of resistance thermal evaporation, electron beam evaporation, and magnetron sputtering; the material of the formed metal film is one of Al, Cr, Ag, and Au.
9. The method for preparing the nanoimprint master negative template according to claim 7, characterized in that: The parent negative template formed in step S24 needs to be post-processed, specifically: the parent negative template is placed in an atmosphere filled with ozone or oxygen and subjected to plasma bombardment treatment, and then perfluorodecyltrichlorosilane is used to perform anti-sticking treatment on the parent negative template.
10. The method for preparing the nanoimprint master negative template according to claim 7, characterized in that: The thickness of the metal film layer formed in step S23 is h1, and the height of the mother negative template formed in step S24 is H1. The relationship between the two is as follows: In the same etching atmosphere, v3 is the etching rate of the metal film, and v4 is the etching rate of the substrate.
11. The method for preparing the nanoimprint master negative template according to claim 7, characterized in that: The pattern structure on the mother negative template includes a second main pattern and a second alignment pattern area. The second main pattern is consistent with the first main pattern in terms of overprinting. The moiré grating in the second alignment pattern area is mirror-symmetrical with the moiré grating in the first alignment pattern area. The annular moiré stripes in the second alignment pattern area are consistent with the annular moiré stripes in the first alignment pattern area.
12. A nanoimprint master negative template, characterized in that: The master negative template is prepared by the method of preparing the nanoimprint master negative template according to any one of claims 7 to 11.
13. A nanoimprint alignment system, characterized in that: The nanoimprinting system includes a master template, a master negative template, and an alignment module; wherein the master template is a master template prepared by the preparation method of the nanoimprinting master template according to any one of claims 1 to 5, and the master negative template is a master negative template prepared by the preparation method of the nanoimprinting master negative template according to any one of claims 7 to 11.
14. The nanoimprint alignment system according to claim 13, characterized in that: The alignment module includes an optical microscope. The master negative template is covered on the master template coated with nanoimprint adhesive. Through the master negative template, the position of the master negative template is adjusted under the optical microscope so that the moiré fringe grating and the annular grating are aligned between the master template and the master negative template.