Nano-lithography method and device based on a hybrid surface plasmon waveguide exposure structure

Abstract

The present application discloses a nano-lithography method and apparatus based on a hybrid surface plasmon waveguide exposure structure, which relates to the field of integrated circuit manufacturing processes. The method includes: determining a theoretical analytical formula for the exposure pattern depth of the surface plasmon lithography exposure structure based on the field strength distribution data of the surface plasmon lithography exposure structure in combination with a hyperbola fitting method; determining relevant data on the focusing spot symmetry and increased exposure depth based on the first resolution and the second resolution; quantitatively analyzing the depth of field data in the relevant data on the focusing spot symmetry and increased exposure depth corresponding to the surface plasmon lithography exposure structure to determine the corresponding relationship between the depth of field data and the surface plasmon lithography exposure structure; and performing a modeling analysis on the dispersion relation data corresponding to the surface plasmon lithography exposure structure to determine the key process parameters that affect the surface plasmon lithography exposure structure to reach a high-frequency mode.

Description

Technical Field

[0001] The present application relates to the field of integrated circuit manufacturing processes, and particularly to a nano-lithography method and apparatus based on a hybrid surface plasmon waveguide exposure structure. Background Art

[0002] With the continuous development of the integrated circuit manufacturing industry, the requirements for micro-nano processing technologies are constantly increasing. Among them, lithography technology, due to its good technical compatibility and precision, has become the core technology for fabricating integrated circuits and has been widely applied to the fields of microelectronics and other micro-nano manufacturing.

[0003] So far, various lithography technologies have been widely used in the manufacturing of various micro-nano devices, such as electron beam lithography (EBL), extreme ultraviolet (EUV) lithography, and nanoimprint lithography. However, the manufacturing costs of these lithography technologies are relatively high, and further improvements are needed in terms of controlling exposure pattern defects, accuracy, and yield.

[0004] Optical lithography technology is a micro-nano processing technology that uses the principle of photochemical reaction to transfer the pattern on the mask to the silicon wafer. It has always been the driving force for the development of the semiconductor industry and an important reason for the integrated circuit to follow Moore's law. However, the resolution of optical lithography technology is limited by the phenomenon of light wave diffraction. This is because the diffraction limit of lithography comes from the fact that high-frequency information can only be carried by evanescent waves, and evanescent waves cannot reach the imaging plane because their amplitude decays exponentially during propagation and only exist in the near-field region. This results in high-frequency information not being able to participate in imaging, thereby limiting the resolution of the lithography system.

[0005] If it is possible to break through the diffraction limit bottleneck existing in traditional optical lithography technology and improve the lithography resolution without greatly shortening the wavelength of the incident light source, and establish an efficient, low-cost, and large-area optical lithography system, it is of great significance for meeting the urgent need of micro-nano processing technology to reduce the feature size of nano-devices.

[0006] After years of development, although experimental results have verified that surface plasmon lithography technology can achieve a lithography resolution of less than 22 nm on the resist and has important application prospects in the preparation of micro-nano structure devices, its practical applicability is still restricted by various factors. Mainly because as the feature size of the lithography pattern continues to shrink, the exposure depth of surface plasmon lithography is relatively shallow, resulting in a relatively small aspect ratio (Aspect ratio = Depth / Width) of the exposure pattern in the photoresist, and further causing the nano-devices or structures fabricated to be unable to achieve their own functions. Summary of the Invention

[0007] The purpose of this application is to provide a nano - lithography method and device based on a hybrid surface plasmon waveguide exposure structure, so as to solve the problem in the existing surface plasmon lithography technology that the exposure depth is relatively shallow, resulting in a relatively small aspect ratio of the exposed pattern in the photoresist, and further causing the nano - devices or structures processed to be unable to achieve their own functions.

[0008] In a first aspect, this application provides a nano - lithography method based on a hybrid surface plasmon waveguide exposure structure, and the method includes:

[0009] Obtain a single - layer photoresist exposure structure in surface plasmon lithography and a surface plasmon lithography exposure structure based on a hybrid surface plasmon waveguide exposure structure;

[0010] Use the finite - difference time - domain method to quantitatively analyze the field - strength distribution in the photoresist in the surface plasmon lithography exposure structure and the single - layer photoresist exposure structure respectively to determine the field - strength distribution data;

[0011] Based on the field - strength distribution data of the surface plasmon lithography exposure structure, combine with the hyperbola fitting method to determine the theoretical analytical formula of the exposure pattern depth of the surface plasmon lithography exposure structure;

[0012] Determine the first resolution of the surface plasmon lithography exposure structure and the second resolution of the single - layer photoresist exposure structure;

[0013] Based on the first resolution and the second resolution, determine the relevant data of the focusing spot symmetry and increasing the exposure depth;

[0014] Quantitatively analyze the depth - of - field data in the relevant data of the focusing spot symmetry and increasing the exposure depth corresponding to the surface plasmon lithography exposure structure to determine the corresponding relationship between the depth - of - field data and the surface plasmon lithography exposure structure;

[0015] Conduct a modeling analysis on the dispersion - relation data corresponding to the surface plasmon lithography exposure structure to determine the key process parameters affecting the surface plasmon lithography exposure structure to reach the high - frequency mode.

[0016] In the case of adopting the above technical solution, the nano-lithography method based on the hybrid surface plasmon waveguide exposure structure provided by the embodiment of the present application can obtain the single-layer photoresist exposure structure in surface plasmon lithography and the surface plasmon lithography exposure structure based on the hybrid surface plasmon waveguide exposure structure; the finite-difference time-domain method is used to quantitatively analyze the field strength distribution in the photoresist in the surface plasmon lithography exposure structure and the single-layer photoresist exposure structure respectively to determine the field strength distribution data; based on the field strength distribution data of the surface plasmon lithography exposure structure, the theoretical analytical formula of the exposure pattern depth of the surface plasmon lithography exposure structure is determined by combining the hyperbola fitting method. Based on the fact that the field strength distribution in the surface plasmon lithography exposure structure based on the hybrid surface plasmon waveguide exposure structure has hyperbolic characteristics, after fitting analysis, it is found that this characteristic can greatly improve the uniformity of the field strength distribution in the photoresist, and thus can effectively improve the depth of focus and increase the exposure depth of the pattern; determine the first resolution of the surface plasmon lithography exposure structure and the second resolution of the single-layer photoresist exposure structure; based on the first resolution and the second resolution, determine the relevant data of the focusing spot symmetry and increasing the exposure depth; quantitatively analyze the depth of focus data in the relevant data of the focusing spot symmetry and increasing the exposure depth corresponding to the surface plasmon lithography exposure structure to determine the corresponding relationship between the depth of focus data and the surface plasmon lithography exposure structure; perform a modeling analysis on the dispersion relation data corresponding to the surface plasmon lithography exposure structure to determine the key process parameters affecting the surface plasmon lithography exposure structure to reach the high-frequency mode. Through the theoretical derivation of the dispersion relation of the HPW exposure structure, the process parameters that can regulate its frequency selection characteristics are obtained, which can provide a theoretical basis for improving the aspect ratio of the surface plasmon lithography exposure pattern.

[0017] In a possible implementation manner, the using the finite-difference time-domain method to quantitatively analyze the field strength distribution in the photoresist in the surface plasmon lithography exposure structure and the single-layer photoresist exposure structure respectively to determine the field strength distribution data includes:

[0018] Using the finite-difference time-domain method to quantitatively analyze the field strength distribution in the photoresist in the single-layer photoresist exposure structure to determine the corresponding field strength distribution data. The field strength distribution data in the photoresist in the single-layer photoresist exposure structure decays rapidly in the form of an exponential and cannot participate in imaging, and the exposure depth is less than the preset exposure depth threshold;

[0019] Using the finite-difference time-domain method to quantitatively analyze the field strength distribution in the photoresist of the surface plasmon lithography exposure structure to determine the corresponding field strength distribution data. The field strength distribution data in the photoresist of the surface plasmon lithography exposure structure is data based on the hybrid waveguide mode formed in the photoresist of the surface plasmon lithography exposure structure, which amplifies and enhances the evanescent wave component and participates in imaging, corresponding to an increased exposure depth.

[0020] In a possible implementation, based on the field strength distribution data of the surface plasmon lithography exposure structure, combining the hyperbolic fitting method to determine the theoretical analytical formula for the exposure pattern depth of the surface plasmon lithography exposure structure, including:

[0021] Determine the field strength attenuation characteristic data based on the field strength distribution data in the photoresist of the surface plasmon lithography exposure structure;

[0022] Perform modeling analysis on the field strength attenuation characteristic data, and combine the hyperbolic fitting method to determine the theoretical analytical formula for the exposure pattern depth:

[0023]

[0024] Among them, the I HPW (z) represents the exposure pattern depth, the I i represents the exposure pattern depth base value, the a and the b represent diffusion function coefficients, the d represents the exposure structure diameter, and the z represents the scene attenuation characteristic data.

[0025] In a possible implementation, the hybrid surface plasmon waveguide exposure structure is a sandwich structure composed of metal-dielectric-metal, including a bowtie nano-aperture structure, the photoresist, and a nano-silver thin film reflection layer arranged in sequence.

[0026] In a possible implementation, the relevant data for determining the focusing spot symmetry and increasing the exposure depth based on the first resolution and the second resolution, including:

[0027] Compare and analyze the first resolution and the second resolution. The first resolution has asymmetry and large field divergence, and the second resolution has symmetry and uniform field strength distribution, to determine the relevant data for the focusing spot symmetry and increasing the exposure depth.

[0028] In a possible implementation, quantitatively analyze the depth of field data in the relevant data for the focusing spot symmetry and increasing the exposure depth corresponding to the surface plasmon lithography exposure structure to determine the corresponding relationship between the depth of field data and the surface plasmon lithography exposure structure, including:

[0029] Obtain the corresponding relationship between the exposure depth and exposure contrast in the photoresist of the surface plasmon lithography exposure structure;

[0030] Based on the corresponding relationship between the exposure depth and exposure contrast, and in combination with the overall contrast and the depth of field data, determine the corresponding relationship between the depth of field data and the surface plasmon lithography exposure structure.

[0031] In a possible implementation, perform modeling analysis on the dispersion relation data corresponding to the surface plasmon lithography exposure structure to determine the key process parameters that affect the surface plasmon lithography exposure structure to reach the high-frequency mode, including:

[0032] Perform modeling analysis on the dispersion relation data corresponding to the surface plasmon lithography exposure structure to determine that the transverse wave vector of the surface plasmon surface wave is greater than the vacuum wave vector, and the surface plasmon surface wave is much smaller than the incident light wave. Under the condition of satisfying phase matching, determine the key process parameters.

[0033] In a possible implementation, the key process parameters include: the aperture characteristic size of the bowtie nanoaperture structure, the thickness of the photoresist, and the thickness of the nano silver film reflective layer.

[0034] In a second aspect, the present application also provides a nano-lithography device based on a hybrid surface plasmon waveguide exposure structure. The device is used to implement the nano-lithography method based on the hybrid surface plasmon waveguide exposure structure according to any one of the first aspects. The device includes:

[0035] An acquisition module, configured to acquire a single-layer photoresist exposure structure in surface plasmon lithography and a surface plasmon lithography exposure structure based on a hybrid surface plasmon waveguide exposure structure;

[0036] A first determination module, configured to respectively perform quantitative analysis on the field strength distribution in the photoresist of the surface plasmon lithography exposure structure and the single-layer photoresist exposure structure by using the finite-difference time-domain method to determine the field strength distribution data;

[0037] A second determination module, configured to determine the theoretical analytical formula of the exposure pattern depth of the surface plasmon lithography exposure structure by combining the hyperbola fitting method based on the field strength distribution data of the surface plasmon lithography exposure structure;

[0038] A third determination module, configured to determine the first resolution of the surface plasmon lithography exposure structure and the second resolution of the single-layer photoresist exposure structure;

[0039] A fourth determination module, configured to determine the relevant data of the focusing spot symmetry and increasing the exposure depth based on the first resolution and the second resolution;

[0040] A fifth determination module, configured to quantitatively analyze the depth-of-field data in the data related to the symmetry of the focused spot corresponding to the surface plasmon lithography exposure structure and increasing the exposure depth, and determine the corresponding relationship between the depth-of-field data and the surface plasmon lithography exposure structure;

[0041] A sixth determination module, configured to perform a modeling analysis on the dispersion relation data corresponding to the surface plasmon lithography exposure structure, and determine the key process parameters that affect the surface plasmon lithography exposure structure to reach a high-frequency mode.

[0042] In a possible implementation manner, the first determination module includes:

[0043] A first determination sub-module, configured to quantitatively analyze the field strength distribution in the photoresist in the single-layer photoresist exposure structure by using the finite-difference time-domain method to determine the corresponding field strength distribution data. The field strength distribution data in the photoresist in the single-layer photoresist exposure structure rapidly decays in an exponential form and cannot participate in imaging, and the exposure depth is less than a preset exposure depth threshold;

[0044] A second determination sub-module, configured to quantitatively analyze the field strength distribution in the photoresist in the surface plasmon lithography exposure structure by using the finite-difference time-domain method to determine the corresponding field strength distribution data. The field strength distribution data in the photoresist in the surface plasmon lithography exposure structure is an amplification and enhancement of the evanescent wave component formed based on the hybrid waveguide mode formed in the photoresist in the surface plasmon lithography exposure structure, participates in imaging, and is data with an increased corresponding exposure depth.

[0045] In a possible implementation manner, the second determination module includes:

[0046] A third determination sub-module, configured to determine the field strength attenuation characteristic data based on the field strength distribution data in the photoresist in the surface plasmon lithography exposure structure;

[0047] A fourth determination sub-module, configured to perform a modeling analysis on the field strength attenuation characteristic data, and determine the theoretical analytical formula of the exposure pattern depth in combination with the hyperbola fitting method:

[0048]

[0049] Wherein, the I HPW (z) represents the exposure pattern depth, the I i represents the exposure pattern depth base value, the a and the b represent diffusion function coefficients, the d represents the exposure structure diameter, and the z represents the scene attenuation characteristic data.

[0050] In a possible implementation, the hybrid surface plasmon waveguide exposure structure is a sandwich structure composed of metal-dielectric-metal, including a bowtie nano-aperture structure, the photoresist, and a nano-silver film reflective layer arranged in sequence.

[0051] In a possible implementation, the fourth determination module includes:

[0052] A fifth determination sub-module, configured to perform comparative analysis on the first resolution and the second resolution, where the first resolution has asymmetry and large field divergence, and the second resolution has symmetry and uniform field strength distribution, to determine relevant data on the symmetry of the focused spot and the increase in exposure depth.

[0053] In a possible implementation, the fifth determination module includes:

[0054] An acquisition sub-module, configured to acquire the corresponding relationship between the exposure depth and the exposure contrast in the photoresist of the surface plasmon lithography exposure structure;

[0055] A sixth determination sub-module, configured to determine the corresponding relationship between the depth of field data and the surface plasmon lithography exposure structure based on the corresponding relationship between the exposure depth and the exposure contrast, in combination with the overall contrast and the depth of field data.

[0056] In a possible implementation, the sixth determination module includes:

[0057] A seventh determination sub-module, configured to perform modeling analysis on the dispersion relation data corresponding to the surface plasmon lithography exposure structure, determine that the transverse wave vector of the surface plasmon surface wave is greater than the vacuum wave vector, and the surface plasmon surface wave is much smaller than the incident light wave. When phase matching is satisfied, determine the key process parameters.

[0058] In a possible implementation, the key process parameters include: the aperture characteristic size of the bowtie nano-aperture structure, the thickness of the photoresist, and the thickness of the nano-silver film reflective layer.

[0059] The beneficial effects of the nano-lithography device based on the hybrid surface plasmon waveguide exposure structure provided in the second aspect are the same as those of the nano-lithography method based on the hybrid surface plasmon waveguide exposure structure described in the first aspect or any possible implementation of the first aspect, and will not be elaborated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] The drawings described herein are used to provide a further understanding of the present application, and constitute a part of the present application. The schematic embodiments of the present application and their descriptions are used to explain the present application, and do not constitute an improper limitation to the present application. In the drawings:

[0061] Figure 1 Shows a schematic flow chart of a nano - lithography method based on a hybrid surface plasmon waveguide exposure structure provided by an embodiment of the present application;

[0062] Figure 2 Shows a schematic flow chart of another nano - lithography method based on a hybrid surface plasmon waveguide exposure structure provided by an embodiment of the present application;

[0063] Figure 3 Shows a schematic structural diagram of a surface plasmon lithography system under two different exposure structures provided by an embodiment of the present application;

[0064] Figure 4 Shows a schematic diagram of the in - field - strength distribution in a photoresist. For the in - field - strength distribution in a single - layer photoresist;

[0065] Figure 5 Shows a curve graph of the attenuation characteristics provided by an embodiment of the present application;

[0066] Figure 6 Shows a schematic diagram of the resolution of an exposure structure provided by an embodiment of the present application, as well as the coupling mode and transmittance change in an HPW exposure structure;

[0067] Figure 7 Shows a schematic diagram of the in - field - strength distribution of a linear pattern under single - layer photoresist exposure provided by an embodiment of the present application;

[0068] Figure 8 Shows a schematic diagram of the in - field - strength distribution of a linear pattern under an HPW exposure structure provided by an embodiment of the present application;

[0069] Figure 9 Shows a schematic diagram of the change of the in - field - strength with the increase of the exposure depth after normalizing the in - field - strength in the photoresist provided by an embodiment of the present application;

[0070] Figure 10 Shows a schematic diagram of the change of the in - field - strength with the increase of the exposure depth after normalizing the in - field - strength in the photoresist provided by an embodiment of the present application;

[0071] Figure 11 Shows a schematic structural diagram of a nano - lithography device based on a hybrid surface plasmon waveguide exposure structure provided by an embodiment of the present application. Detailed implementation manners

[0072] For the convenience of clearly describing the technical solutions of the embodiments of the present application, in the embodiments of the present application, terms such as "first" and "second" are used to distinguish identical or similar items with basically the same functions and roles. For example, the first threshold and the second threshold are only used to distinguish different thresholds, and do not limit their sequence. Those skilled in the art can understand that terms such as "first" and "second" do not limit the quantity and execution order, and the terms "first" and "second" do not necessarily mean different.

[0073] It should be noted that in the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or explanations. Any embodiment or design solution described as "exemplary" or "for example" in the present application should not be construed as being more preferred or having more advantages than other embodiments or design solutions. Rather, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific manner.

[0074] In the present application, "at least one" means one or more, and "a plurality" means two or more. "And / or" describes the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone, where A and B can be singular or plural. The character " / " generally indicates that the associated objects before and after are an "or" relationship. "At least one (item)" or its similar expression refers to any combination of these items, including any combination of single item (item) or plural items (items). For example, at least one (item) of a, b or c can mean: a, b, c, the combination of a and b, the combination of a and c, the combination of b and c, or the combination of a, b and c, where a, b and c can be single or multiple.

[0075] If it is possible to break through the diffraction limit bottleneck existing in traditional optical lithography technology, and improve the lithography resolution without greatly shortening the wavelength of the incident light source, and establish an optical lithography system that is efficient, low-cost and can achieve large-area generation, it is of great significance for meeting the urgent need of micro-nano processing technology to reduce the feature size of nano-devices.

[0076] In recent years, by studying and utilizing the super-diffraction optical properties of surface plasmons (SPs), researchers have proposed and established a series of lithography techniques based on surface plasmons, such as surface plasmon interference lithography, prism-excited SP interference, SP super-resolution imaging lithography, superlens imaging lithography, reflective SP imaging lithography, SP resonant cavity structure imaging lithography, SP direct writing lithography, etc. Surface plasmons are a phenomenon of collective oscillation of electrons excited by the interaction between incident electromagnetic waves and metal surface electrons, and are free density waves confined to the metal-dielectric interface. On the one hand, since the wave vector of surface plasmons is greater than that of electromagnetic waves with the same frequency in vacuum, it has sub-wavelength characteristics and can break through the diffraction limit for transmission. On the other hand, because it is localized on the surface of the metal-dielectric, it has a near-field field strength enhancement effect, which can greatly increase the effect of the light field intensity in the near-field range. Therefore, based on the regulation of high-frequency evanescent waves, realizing sub-wavelength characteristics and local enhancement of the near-field field strength lays a theoretical basis for surface plasmon lithography technology to achieve super-resolution.

[0077] After years of development, although experimental results have verified that surface plasmon lithography technology can obtain a lithography resolution of less than 22 nm on the resist and has important application prospects in the preparation of micro-nano structure devices, its practical applicability is still restricted by many factors. This is mainly because as the feature size of the lithography pattern continues to shrink, the exposure depth of surface plasmon lithography is relatively shallow, resulting in a relatively small aspect ratio (Aspect ratio = Depth / Width) of the exposed pattern in the photoresist, and then the processed nano-devices or structures cannot realize their own functions. Generally speaking, various micro-nano structure devices, including integrated circuits, have relatively high requirements for the aspect ratio of the lithography pattern. For example, only when the aspect ratio of the pattern in the photoresist reaches more than 1 can it be ensured that when the lithography pattern is used as an etching mask, it can be etched into the substrate, enabling DRAM, α-Si devices, or other nano-structure devices in some integrated circuits to achieve a relatively large capacitance ratio, improving the electromechanical sensitivity and energy density of some nano-composite materials, and enabling the nano-jet channel to have a relatively large sample injection volume. Therefore, while enhancing the lithography resolution, conducting research on improving the aspect ratio of the pattern in the photoresist is of great significance for improving the practical applicability of surface plasmon lithography technology.

[0078] Currently, by combining a nano-bowtie antenna with a resonant imaging lithography (metal / dielectric / metal (MIM)) structure (BMIM) and applying it to a surface plasmon lithography system, a focal spot pattern with a full width at half maximum (FWHM) of approximately 28 nm and an exposure depth of 20 nm can be obtained in experiments, resulting in an aspect ratio of the exposure pattern reaching 0.71. However, when applying the BMIM structure to surface plasmon lithography technology, although it can greatly increase the depth of the focal spot pattern, it still fails to meet the requirement of micro-nano devices for an aspect ratio exceeding 1. Moreover, due to the influence of the asymmetric bowtie geometry, after the incident light passes through the bowtie, the field strength distribution is also severely asymmetric, causing the focused spot obtained on the photoresist surface to be elliptical and reducing the quality of the exposure pattern.

[0079] Currently, by combining a double-bowtie structure with a resonant imaging lithography (metal / dielectric / metal (MIM)) structure (DBMIM) and applying it to a surface plasmon lithography system, a circularly symmetric focal spot with a FWHM of 45 nm can be obtained in experiments under the excitation light source of linearly polarized light with an incident wavelength of 365 nm. However, when using the DBMIM structure as the exposure structure for surface plasmon lithography, although a circularly symmetric focal spot can be obtained using the double-bowtie structure, and a local enhanced field strength 22 times that of the incident plane electric field strength can be obtained at its opening, due to the bowtie structure being an asymmetric nano-ridge aperture structure, the near-field field strength converging at its opening has strong field divergence and asymmetry. Although the proposed double-bowtie structure can solve the field strength asymmetry, it further increases the field divergence and reduces its resolution.

[0080] To solve the problem of improving the aspect ratio of the pattern in the photoresist while enhancing the lithography resolution, which is of great significance for improving the practical applicability of surface plasmon lithography technology, this application proposes a surface plasmon nano-lithography technology based on a hybrid surface plasmon waveguide structure. Through the strong coupling resonance effect between two transverse and longitudinal surface plasmon waveguide structures and the SP surface wave, a high resolution can be obtained on the photoresist surface and the aspect ratio of the exposure pattern can be greatly increased.

[0081] Figure 1 The flowchart of a nano-lithography method based on a hybrid surface plasmon waveguide exposure structure provided by an embodiment of this application is shown, as Figure 1 shown, the nano-lithography method based on the hybrid surface plasmon waveguide exposure structure includes:

[0082] Step 101: Obtain the single-layer photoresist exposure structure in surface plasmon lithography and the surface plasmon lithography exposure structure based on the hybrid surface plasmon waveguide exposure structure.

[0083] In this application, the hybrid surface plasmon waveguide exposure structure is a sandwich structure composed of metal-dielectric-metal, including a bowtie nanoaperture structure, the photoresist, and a nano silver film reflection layer arranged in sequence.

[0084] Step 102: Use the finite-difference time-domain method to quantitatively analyze the field strength distribution in the photoresist of the surface plasmon lithography exposure structure and the single-layer photoresist exposure structure respectively to determine the field strength distribution data.

[0085] In this application, the finite-difference time-domain method can be used to quantitatively analyze the field strength distribution in the photoresist of the single-layer photoresist exposure structure to determine the corresponding field strength distribution data. The field strength distribution data in the photoresist of the single-layer photoresist exposure structure decays rapidly in an exponential form and cannot participate in imaging. The exposure depth is less than the preset exposure depth threshold;

[0086] Use the finite-difference time-domain method to quantitatively analyze the field strength distribution in the photoresist of the surface plasmon lithography exposure structure to determine the corresponding field strength distribution data. The field strength distribution data in the photoresist of the surface plasmon lithography exposure structure is an amplified and enhanced evanescent wave component formed based on the hybrid waveguide mode formed in the photoresist of the surface plasmon lithography exposure structure, participates in imaging, and the corresponding exposure depth increases.

[0087] Step 103: Based on the field strength distribution data of the surface plasmon lithography exposure structure, combine the hyperbola fitting method to determine the theoretical analytical formula of the exposure pattern depth of the surface plasmon lithography exposure structure.

[0088] In this application, the field strength attenuation characteristic data can be determined based on the field strength distribution data in the photoresist of the surface plasmon lithography exposure structure;

[0089] Perform modeling analysis on the field strength attenuation characteristic data, and combine the hyperbola fitting method to determine the theoretical analytical formula of the exposure pattern depth:

[0090]

[0091] where, the I HPW (z) represents the exposure pattern depth, the I i represents the exposure pattern depth base value, the a and the b represent diffusion function coefficients, the d represents the exposure structure diameter, and the z represents the scene attenuation characteristic data.

[0092] Step 104: Determine a first resolution of the surface plasmon lithography exposure structure and a second resolution of the single-layer photoresist exposure structure.

[0093] Step 105: Determine relevant data on the focusing spot symmetry and increased exposure depth based on the first resolution and the second resolution.

[0094] Perform a comparative analysis on the first resolution and the second resolution. The first resolution has asymmetry and large field divergence, and the second resolution has symmetry and a uniform field strength distribution, and determine the relevant data on the focusing spot symmetry and increased exposure depth.

[0095] Step 106: Perform a quantitative analysis on the depth-of-field data in the relevant data on the focusing spot symmetry and increased exposure depth corresponding to the surface plasmon lithography exposure structure, and determine the corresponding relationship between the depth-of-field data and the surface plasmon lithography exposure structure.

[0096] In the present application, the corresponding relationship between the exposure depth and the exposure contrast in the photoresist of the surface plasmon lithography exposure structure can be obtained;

[0097] Based on the corresponding relationship between the exposure depth and the exposure contrast, and in combination with the overall contrast and the depth-of-field data, determine the corresponding relationship between the depth-of-field data and the surface plasmon lithography exposure structure.

[0098] Step 107: Perform a modeling analysis on the dispersion relation data corresponding to the surface plasmon lithography exposure structure, and determine the key process parameters that affect the surface plasmon lithography exposure structure to reach the high-frequency mode.

[0099] In the present application, the dispersion relation data corresponding to the surface plasmon lithography exposure structure can be modeled and analyzed to determine that the transverse wave vector of the surface plasmon surface wave is greater than the vacuum wave vector, and the surface plasmon surface wave is much smaller than the incident light wave. Under the condition of satisfying phase matching, determine the key process parameters.

[0100] The key process parameters include: the aperture characteristic size of the bowtie nano-aperture structure, the thickness of the photoresist, and the thickness of the nano-silver thin film reflective layer.

[0101] The purpose of the present application is to propose a nano-lithography system that can solve the problem of shallow exposure depth caused by the near-field attenuation characteristic in surface plasmon lithography technology. Combine the bowtie structure with a reflective imaging (photoresist / metal thin film reflective layer) structure to form a new type of hybrid surface plasmon waveguide structure (hybrid plasmonic waveguide, HPW).

[0102] As an exposure structure for surface plasmon lithography, the HPW structure can not only well solve the problem of asymmetric focused spots, but also, due to the unique transverse MIM surface plasmon waveguide structure (Al / air / Al) of the bowtie structure, strongly couple and resonate with the longitudinal MIM surface plasmon waveguide structure (bowtie / resist / metal film reflector) of the HPW structure on the upper and lower surfaces of the resist layer to form SP surface waves. When the evanescent wave and the transverse propagation wave vector of the SP surface wave reach matching, the former can be coupled into the latter mode, amplifying and enhancing the evanescent wave component in the resist and participating in imaging. While ensuring the uniformity of the field strength distribution within the entire resist film layer, it also greatly increases the depth of the exposed pattern.

[0103] In addition, the application of the HPW structure endows the surface plasmon lithography system with strong spatial frequency selection characteristics. By adjusting the bowtie aperture gap size, the resist film thickness, and the metal reflector film thickness, the high-k mode can be achieved, enabling surface plasmon lithography to have high imaging contrast and exposure quality, which is of great significance for further improving the practical applicability of surface plasmon lithography technology.

[0104] In summary, the nano - lithography method based on the hybrid surface plasmon waveguide exposure structure provided by the embodiments of the present application can obtain the single - layer photoresist exposure structure in surface plasmon lithography and the surface plasmon lithography exposure structure based on the hybrid surface plasmon waveguide exposure structure. The finite - difference time - domain method is used to quantitatively analyze the field - strength distribution in the photoresist of the surface plasmon lithography exposure structure and the single - layer photoresist exposure structure respectively to determine the field - strength distribution data. Based on the field - strength distribution data of the surface plasmon lithography exposure structure, the theoretical analytical formula of the exposure pattern depth of the surface plasmon lithography exposure structure is determined by combining the hyperbolic fitting method. Since the field - strength distribution in the surface plasmon lithography exposure structure based on the hybrid surface plasmon waveguide exposure structure has hyperbolic characteristics, after fitting analysis, it is found that this characteristic can greatly improve the uniformity of the field - strength distribution in the photoresist, and then can effectively improve the depth of field and increase the exposure depth of the pattern. Determine the first resolution of the surface plasmon lithography exposure structure and the second resolution of the single - layer photoresist exposure structure. Based on the first resolution and the second resolution, determine the relevant data of the focusing spot symmetry and increasing the exposure depth. Quantitatively analyze the depth - of - field data in the relevant data of the focusing spot symmetry and increasing the exposure depth corresponding to the surface plasmon lithography exposure structure to determine the corresponding relationship between the depth - of - field data and the surface plasmon lithography exposure structure. Model and analyze the dispersion relation data corresponding to the surface plasmon lithography exposure structure to determine the key process parameters affecting the surface plasmon lithography exposure structure to reach the high - frequency mode. Through the theoretical derivation of the dispersion relation of the HPW exposure structure, the process parameters that can regulate its frequency - selection characteristics are obtained, which can provide a theoretical basis for improving the aspect ratio of the surface plasmon lithography exposure pattern.

[0105] Figure 2 FIG. shows a schematic flow chart of another nano - lithography method based on the hybrid surface plasmon waveguide exposure structure provided by the embodiments of the present application. As Figure 2 shown, the nano - lithography method based on the hybrid surface plasmon waveguide exposure structure includes:

[0106] Step 201: Obtain the single - layer photoresist exposure structure in surface plasmon lithography and the surface plasmon lithography exposure structure based on the hybrid surface plasmon waveguide exposure structure.

[0107] Figure 3 FIG. shows a schematic structural diagram of a surface plasmon lithography system under two different exposure structures provided by the embodiments of the present application. Figure 3 (a) is a traditional single - layer photoresist exposure structure. The traditional single - layer photoresist exposure structure includes: a nano - bowtie aperture structure Bowtie, a photoresist Photoresist, and a silicon substrate Si. Figure 3(b) is a surface plasmon lithography exposure structure based on a hybrid surface plasmon waveguide exposure structure. Among them, the hybrid surface plasmon waveguide exposure structure is a sandwich structure composed of metal-dielectric-metal, including a bowtie nano-aperture structure Bowtie, the photoresist Photoresist, a nano-silver film reflector layer Metal reflector film, and a silicon substrate Si arranged in sequence. The wavelength of the incident light Incident light is 365 nanometers (nm), and the bowtie nano-aperture structure 01 has a gap size.

[0108] Step 202: Use the finite-difference time-domain method to quantitatively analyze the field strength distribution in the photoresist in the surface plasmon lithography exposure structure and the single-layer photoresist exposure structure respectively to determine the field strength distribution data.

[0109] In this application, the finite-difference time-domain method (FDTD) can be used to quantitatively analyze the field strength distribution in the photoresist in the single-layer photoresist exposure structure to determine the corresponding field strength distribution data. The field strength distribution data in the photoresist in the single-layer photoresist exposure structure decays rapidly in an exponential form, cannot participate in imaging, and the exposure depth is less than the preset exposure depth threshold.

[0110] Specifically, Figure 4 shows a schematic diagram of the field strength distribution in the photoresist provided by the embodiment of the present application. For the field strength distribution in the single-layer photoresist, as Figure 4 (a) shows, in the exposure structure with only a single-layer photoresist, the exposure amount in the photoresist decays rapidly in an exponential form, so it cannot propagate to the far field and cannot participate in imaging, resulting in a shallower exposure depth.

[0111] Furthermore, the finite-difference time-domain method can be used to quantitatively analyze the field strength distribution in the photoresist in the surface plasmon lithography exposure structure to determine the corresponding field strength distribution data. The field strength distribution data in the photoresist in the surface plasmon lithography exposure structure is data with an increased exposure depth corresponding to the amplification and enhancement of the evanescent wave component based on the hybrid waveguide mode formed in the photoresist in the surface plasmon lithography exposure structure and participating in imaging.

[0112] Specifically, for the field strength distribution of the HPW exposure structure, as Figure 4As shown in (b), in the HPW exposure structure, the lateral fluctuation mode formed by the bowtie nano-aperture structure can not only achieve the field strength transmission of the incident wave, but also generate a strong SP surface wave on the upper surface of the photoresist film layer. Due to the presence of the nano-silver film reflection layer, an SP surface wave will be generated again at the interface between the photoresist and it. The longitudinal waveguide mode in the HPW exposure structure will be coupled with the SP surface waves generated at the upper and lower interfaces of the photoresist to form a hybrid waveguide mode confined in the photoresist. Compared with the pure SP surface wave mode, this hybrid surface plasmon waveguide mode has the advantages of achieving a near-field enhancement effect, having good field confinement ability, and being able to maintain a relatively long propagation distance, enabling the evanescent wave component in the photoresist to be amplified and enhanced and participate in imaging, thereby promoting the increase of the exposure depth.

[0113] Step 203: Determine the field strength attenuation characteristic data based on the field strength distribution data in the photoresist in the surface plasmon lithography exposure structure.

[0114] In this application, the point spread function (PSF) can be used to quantitatively analyze the field strength distribution in the photoresist. Figure 5 The attenuation characteristic curve diagram provided by the embodiment of the present application is shown. The horizontal axis represents the depth of field (Depth), FDTD simulation represents the simulation divergence simulation data, Theory represents the theoretical data, and the vertical axis represents the PSF, with the unit of a.u., representing a dimensionless unit. For the PSF in the single-layer photoresist exposure structure, it shows an exponential decay, as Figure 5 As shown in (a), the PSF in the single-layer photoresist exposure structure shows an exponential decay, and its attenuation characteristic can be quantitatively analyzed by β = a + bz.

[0115] Figure 5 (b) shows that the PST in the HPW exposure structure shows a hyperbolic decay characteristic, as Figure 5 As shown in (b), the field strength distribution in the HPW exposure structure shows a hyperbolic decay characteristic. Therefore, in this application, a fitting calculation is proposed to be carried out on it based on the formula (1).

[0116]

[0117] Step 204: Perform a modeling analysis on the field strength attenuation characteristic data, and determine the theoretical analytical formula of the exposure pattern depth in combination with the hyperbolic fitting method.

[0118] As shown in Formula 2:

[0119]

[0120] Among them, the I HPW(z) represents the depth of the exposed pattern, and the I i represents the base value of the depth of the exposed pattern, the a and the b represent the diffusion function coefficients, the d represents the diameter of the exposure structure, and the z represents the scene attenuation characteristic data.

[0121] According to the imaging conditions in the surface plasmon lithography process, that is, the dose modulation function (DMF) required for the exposed pattern should be greater than or equal to the critical modulation transfer function (CMTF) of the pattern structure, DMF≥CMTF, the theoretical maximum value of the exposure depth of the pattern at a specific size can be deduced.

[0122] Step 205: Determine the first resolution of the surface plasmon lithography exposure structure and the second resolution of the single-layer photoresist exposure structure.

[0123] In this application, the resolutions of two surface plasmon lithography systems can be compared and analyzed, and the physical origin of the HPW structure can improve the symmetry of the focused spot and increase the exposure depth can be revealed.

[0124] Step 206: Determine the relevant data of the focused spot symmetry and increased exposure depth based on the first resolution and the second resolution.

[0125] In this application, the first resolution and the second resolution can be compared and analyzed. The first resolution has asymmetry and large field divergence, and the second resolution has symmetry and uniform field strength distribution, and the relevant data of the focused spot symmetry and increased exposure depth are determined.

[0126] Specifically, for an optical lithography system, the field strength distribution of the focused spot is one of the important parameters that determine the system resolution and exposure result, directly affecting the length of the exposure time and the quality of the exposed pattern. Figure 6 shows a schematic diagram of the resolution of an exposure structure provided by an embodiment of this application, as well as the coupling mode and transmittance change in the HPW exposure structure. Figure 6 (a) is the resolution that can be achieved under two surface plasmon lithography exposure structures, such as Figure 6As shown in (a), for a traditional single-layer photoresist surface plasmon lithography system (Single), due to the severe asymmetry and large field divergence of its focused spot, the achievable resolution in the photoresist has asymmetry and increases with the increase of distance. The HPW exposure structure proposed in this application is a sandwich structure composed of metal-dielectric-metal (MIM), mainly including a bowtie nanoaperture (BNA), a photoresist (PR), and a nano silver film reflector (Ag reflector). This HPW exposure model includes a transverse MIM plasmonic waveguide structure composed of Al-air-Al, and a longitudinal MIM plasmonic waveguide structure composed of Al-PR-Ag. The transverse MIM plasmonic waveguide can further excite the generation of surface plasmons on the upper surface of the photoresist layer, and the longitudinal MIM plasmonic waveguide can further excite the generation of surface plasmons on the lower surface of the photoresist layer, and then form a complex resonance coupling mode with the SP surface wave in the photoresist layer. Figure 5 (b) shows the coupling mode and transmittance change in the HPW exposure structure under different incident light wavelengths provided by the embodiment of this application, as Figure 5 (b) shows, where the horizontal axis Wavelength represents the wavelength, the vertical axis Transmission represents the transmittance, and F-P like resonances represents the resonance cavity resonance. It can be seen that the field strength distribution in the entire photoresist thin film layer has uniformity, which can not only improve the achievable resolution in the photoresist, but also further enhance the exposure depth of the pattern.

[0127] Step 207: Obtain the corresponding relationship between the exposure depth and exposure contrast in the photoresist of the surface plasmon lithography exposure structure.

[0128] In this application, a quantitative analysis can be carried out on the role that the HPW structure can play in improving the depth-of-field in surface plasmon lithography technology.

[0129] Specifically, in surface plasmon lithography, the local contrast existing with the increase of exposure depth in the photoresist can be defined as γ(z)≡I1(z) / I0(z), that is, the corresponding relationship between the exposure depth and exposure contrast in the photoresist is: γ(z)≡I1(z) / I0(z).

[0130] Step 208: Based on the correspondence between the exposure depth and the exposure contrast, and in combination with the overall contrast and the depth-of-field data, determine the correspondence between the depth-of-field data and the surface plasmon lithography exposure structure.

[0131] The correspondence between the exposure depth and the exposure contrast in the photoresist is: γ(z)≡I1(z) / I0(z). Throughout the exposure range, the overall contrast can be defined as Γ = min(I1) / max(I0), and the depth of field is determined by V = (Γ - 1) / (Γ + 1) ≥ 0. Therefore, by quantitatively analyzing the variation of the field strength of the linear pattern with the increase of the exposure depth under the single-layer photoresist exposure structure and different HPW exposure structures, the depth of field under the two exposure structures can be calculated respectively, as Figures 7 - 10 shown. After quantitative calculation, it can be found that the HPW structure has a significant effect on changing the depth of field in surface plasmon lithography.

[0132] Figure 7 FIG. shows a schematic diagram of the field strength distribution of a linear pattern under a single-layer photoresist exposure provided by an embodiment of the present application. The vertical axis Pattern depth represents the pattern depth, Figure 8 FIG. shows a schematic diagram of the field strength distribution of a linear pattern under the HPW exposure structure provided by an embodiment of the present application. Figure 9 FIG. shows a schematic diagram of the variation of the field strength with the increase of the exposure depth after normalizing the field strength in the photoresist provided by an embodiment of the present application, as Figure 9 shown. The horizontal axis Pattern depth represents the pattern depth, and the vertical axis Normalized intensity represents the normalized intensity. When using the single-layer photoresist exposure structure for linear pattern exposure, it can be seen from the variation of the field strength with the increase of the exposure depth that its depth of field is relatively shallow. Figure 10 FIG. shows a schematic diagram of the variation of the field strength with the increase of the exposure depth after normalizing the field strength in the photoresist provided by an embodiment of the present application, as Figure 10 shown. The horizontal axis Pattern depth represents the pattern depth, and the vertical axis Normalized intensity represents the normalized intensity. When using the HPW exposure structure for linear pattern exposure, it can be seen from the variation of the field strength with the increase of the exposure depth that there is no depth-of-field limitation.

[0133] Step 209: Perform modeling analysis on the dispersion relation data corresponding to the surface plasmon lithography exposure structure to determine the key process parameters that affect the surface plasmon lithography exposure structure to reach the high-frequency mode.

[0134] In this application, modeling analysis can be performed on the dispersion relation data corresponding to the surface plasmon lithography exposure structure to determine that the transverse wave vector of the surface plasmon surface wave is greater than the vacuum wave vector, and the surface plasmon surface wave is much smaller than the incident light wave. When phase matching is satisfied, the key process parameters are determined.

[0135] Among them, the key process parameters include: the aperture characteristic size of the bowtie nano-aperture structure, the thickness of the photoresist, and the thickness of the nano-silver film reflective layer.

[0136] Specifically, modeling analysis is performed on the dispersion relation of the surface plasmon lithography system based on the HPW structure to obtain the key process parameters that can affect its reaching the high-k mode. Compared with the traditional single-layer photoresist exposure structure, the HPW exposure structure is composed of the mutual coupling of the surface plasmon waveguide mode and the SP surface wave mode. By analyzing its dispersion relation, it can be found that the transverse wave vector kx of the SP surface wave in the HPW exposure structure is much larger than the vacuum wave vector k0, that is, the SP surface wave is much smaller than the incident light wavelength. This characteristic can not only achieve the confinement of the sub-wavelength mode in the surface plasmon lithography process, that is, high resolution, but also achieve the near-field enhancement effect. Therefore, through the analysis of the dispersion characteristics of the HPW exposure structure, under the condition of satisfying phase matching, how to optimize the characteristic size of the bowtie nano-aperture, the photoresist, and the thickness of the nano-silver film reflective layer, change the transverse wave vector kx of the SP surface wave, and then achieve the characteristic of high-frequency spatial frequency selection.

[0137] This application proposes a surface plasmon lithography method based on the hybrid surface plasmon waveguide mode, and conducts theoretical analysis and simulation verification on its imaging characteristics. (1) The HPW exposure structure and its application in the surface plasmon lithography system. By combining the bowtie structure with the reflective imaging (photoresist / metal thin film reflective layer) structure and applying it to the surface plasmon lithography process, it has been verified through theoretical analysis and simulation results in this application that the complex and strong coupling resonance effect generated between the unique hybrid surface plasmon waveguide mode of this structure and the SP surface wave can effectively improve the resolution and aspect ratio of the exposure pattern of its system. (2) Quantitative modeling analysis of the field strength attenuation characteristics of the HPW exposure structure. Different from the traditional surface plasmon lithography exposure system where the field strength decays exponentially in the photoresist, the field strength distribution in the HPW exposure structure has hyperbolic characteristics. After fitting and analyzing it, we found that this characteristic can greatly improve the uniformity of the field strength distribution in the photoresist, and thus can effectively improve the depth of field and increase the exposure depth of the pattern. (3) The spatial frequency selection characteristics of the HPW exposure structure and the determination of its regulation parameters. In the surface plasmon lithography exposure system, being able to achieve a higher spatial frequency mode (high-k mode) with a higher propagation wave vector is one of the necessary physical conditions for it to break through the diffraction limit, improve the resolution of its system, imaging resolution, and pattern quality. Therefore, by theoretically deriving the dispersion relationship of the HPW exposure structure and then obtaining the process parameters that can regulate its spatial frequency selection characteristics, it can provide a theoretical basis for improving the aspect ratio of the surface plasmon lithography exposure pattern.

[0138] The HPW exposure structure proposed in this application can not only effectively improve the problem of the asymmetric focusing spot caused by the geometric asymmetry of the focusing element bowtie in the surface plasmon lithography system, but also reduce the divergence of the field strength at the bowtie opening through the complex and strong coupling resonance effect between the surface plasmon waveguide and the SP surface wave, making the evanescent wave in the photoresist have stronger field confinement and can be amplified and enhanced, ensuring the uniformity of the field strength distribution in the entire photoresist thin film layer and increasing the exposure depth of the pattern. In addition, due to the strong spatial frequency selection and filtering characteristics of the HPW exposure structure, the gap size of the bowtie nano-aperture structure, the thin film thickness of the photoresist, and the thickness of the metal thin film reflective layer can be regulated to reach the high-frequency mode and obtain a higher transverse propagation wave vector, which can greatly improve the imaging contrast of the surface plasmon lithography while also improving the aspect ratio of the exposure pattern. This is of great practical significance for meeting the requirement that the aspect ratio of the lithography pattern must be greater than 1 in the micro-nano device processing technology and then realizing the practical application of the surface plasmon lithography process.

[0139] In summary, the nano-lithography method based on the hybrid surface plasmon waveguide exposure structure provided by the embodiments of the present application can obtain a single-layer photoresist exposure structure in surface plasmon lithography and a surface plasmon lithography exposure structure based on the hybrid surface plasmon waveguide exposure structure; use the finite-difference time-domain method to quantitatively analyze the field strength distribution in the photoresist in the surface plasmon lithography exposure structure and the single-layer photoresist exposure structure respectively to determine the field strength distribution data; based on the field strength distribution data of the surface plasmon lithography exposure structure, combine the hyperbolic fitting method to determine the theoretical analytical formula of the exposure pattern depth of the surface plasmon lithography exposure structure. Based on the hyperbolic characteristics of the field strength distribution in the surface plasmon lithography exposure structure based on the hybrid surface plasmon waveguide exposure structure, after fitting and analyzing it, we find that this characteristic can greatly improve the uniformity of the field strength distribution in the photoresist, and thus can effectively improve the depth of field and increase the exposure depth of the pattern; determine the first resolution of the surface plasmon lithography exposure structure and the second resolution of the single-layer photoresist exposure structure; determine the relevant data of the focusing spot symmetry and increasing the exposure depth based on the first resolution and the second resolution; quantitatively analyze the depth-of-field data in the relevant data of the focusing spot symmetry and increasing the exposure depth corresponding to the surface plasmon lithography exposure structure to determine the corresponding relationship between the depth-of-field data and the surface plasmon lithography exposure structure; perform a modeling analysis on the dispersion relation data corresponding to the surface plasmon lithography exposure structure to determine the key process parameters that affect the surface plasmon lithography exposure structure to reach the high-frequency mode. Through the theoretical derivation of the dispersion relation of the HPW exposure structure, the process parameters that can regulate its frequency selection characteristics are obtained, which can provide a theoretical basis for improving the aspect ratio of the surface plasmon lithography exposure pattern.

[0140] Figure 11 FIG. shows a schematic structural diagram of a nano-lithography apparatus based on a hybrid surface plasmon waveguide exposure structure provided by an embodiment of the present application, which is used to implement any of the nano-lithography methods based on the hybrid surface plasmon waveguide exposure structure of the present application, as Figure 11 shown, the nano-lithography apparatus 300 based on the hybrid surface plasmon waveguide exposure structure includes:

[0141] An acquisition module 301, configured to acquire a single-layer photoresist exposure structure in surface plasmon lithography and a surface plasmon lithography exposure structure based on a hybrid surface plasmon waveguide exposure structure;

[0142] A first determination module 302, configured to quantitatively analyze the field strength distribution in the photoresist in the surface plasmon lithography exposure structure and the single-layer photoresist exposure structure respectively by using the finite-difference time-domain method to determine the field strength distribution data;

[0143] The second determination module 303 is configured to determine a theoretical analytical formula for the exposure pattern depth of the surface plasmon lithography exposure structure based on the field strength distribution data of the surface plasmon lithography exposure structure and in combination with a hyperbolic fitting method;

[0144] The third determination module 304 is configured to determine a first resolution of the surface plasmon lithography exposure structure and a second resolution of the single-layer photoresist exposure structure;

[0145] The fourth determination module 305 is configured to determine relevant data on the focusing spot symmetry and the increased exposure depth based on the first resolution and the second resolution;

[0146] The fifth determination module 306 is configured to quantitatively analyze the depth of field data in the relevant data on the focusing spot symmetry and the increased exposure depth corresponding to the surface plasmon lithography exposure structure, and determine the corresponding relationship between the depth of field data and the surface plasmon lithography exposure structure;

[0147] The sixth determination module 307 is configured to perform a modeling analysis on the dispersion relation data corresponding to the surface plasmon lithography exposure structure, and determine the key process parameters that affect the surface plasmon lithography exposure structure to reach the high-frequency mode.

[0148] In a possible implementation manner, the first determination module includes:

[0149] The first determination sub-module is configured to quantitatively analyze the field strength distribution in the photoresist of the single-layer photoresist exposure structure by using the finite-difference time-domain method to determine the corresponding field strength distribution data. The field strength distribution data in the photoresist of the single-layer photoresist exposure structure decays rapidly in an exponential form and cannot participate in imaging, and the exposure depth is less than a preset exposure depth threshold;

[0150] The second determination sub-module is configured to quantitatively analyze the field strength distribution in the photoresist of the surface plasmon lithography exposure structure by using the finite-difference time-domain method to determine the corresponding field strength distribution data. The field strength distribution data in the photoresist of the surface plasmon lithography exposure structure is an amplified and enhanced evanescent wave component formed based on the hybrid waveguide mode formed in the photoresist of the surface plasmon lithography exposure structure, participates in imaging, and is data with an increased corresponding exposure depth.

[0151] In a possible implementation manner, the second determination module includes:

[0152] The third determination sub-module is configured to determine field strength attenuation characteristic data based on the field strength distribution data in the photoresist of the surface plasmon lithography exposure structure;

[0153] The fourth determination sub-module is configured to perform modeling analysis on the field strength attenuation characteristic data, and determine the theoretical analytical formula of the exposure pattern depth in combination with the hyperbola fitting method:

[0154]

[0155] Among them, the I HPW (z) represents the exposure pattern depth, the I i represents the base value of the exposure pattern depth, the a and the b represent diffusion function coefficients, the d represents the exposure structure diameter, and the z represents the scene attenuation characteristic data.

[0156] In a possible implementation manner, the hybrid surface plasmon waveguide exposure structure is a sandwich structure composed of metal-dielectric-metal, and includes a bowtie nano-aperture structure, the photoresist, and a nano-silver thin film reflection layer arranged in sequence.

[0157] In a possible implementation manner, the fourth determination module includes:

[0158] The fifth determination sub-module is configured to perform comparative analysis on the first resolution and the second resolution. The first resolution has asymmetry and large field divergence, and the second resolution has symmetry and uniform field strength distribution, and determine the relevant data of the focusing spot symmetry and increased exposure depth.

[0159] In a possible implementation manner, the fifth determination module includes:

[0160] An acquisition sub-module is configured to acquire the correspondence between the exposure depth and the exposure contrast in the photoresist of the surface plasmon lithography exposure structure;

[0161] The sixth determination sub-module is configured to determine the correspondence between the depth of field data and the surface plasmon lithography exposure structure based on the correspondence between the exposure depth and the exposure contrast, in combination with the overall contrast and the depth of field data.

[0162] In a possible implementation manner, the sixth determination module includes:

[0163] The seventh determination sub-module is configured to perform modeling analysis on the dispersion relation data corresponding to the surface plasmon lithography exposure structure, determine that the transverse wave vector of the surface plasmon surface wave is greater than the vacuum wave vector, and the surface plasmon surface wave is much smaller than the incident light wave. Under the condition of satisfying phase matching, determine the key process parameters.

[0164] In a possible implementation, the key process parameters include: the aperture characteristic size of the bow-tie nano-aperture structure, the thickness of the photoresist, and the thickness of the nano-silver thin film reflective layer. The nano-lithography apparatus based on the hybrid surface plasmon waveguide exposure structure provided by the embodiments of the present application can obtain a single-layer photoresist exposure structure in surface plasmon lithography and a surface plasmon lithography exposure structure based on the hybrid surface plasmon waveguide exposure structure; use the finite-difference time-domain method to quantitatively analyze the field strength distribution in the photoresist in the surface plasmon lithography exposure structure and the single-layer photoresist exposure structure to determine the field strength distribution data; based on the field strength distribution data of the surface plasmon lithography exposure structure, combine the hyperbolic fitting method to determine the theoretical analytical formula of the exposure pattern depth of the surface plasmon lithography exposure structure. Based on the fact that the field strength distribution in the surface plasmon lithography exposure structure based on the hybrid surface plasmon waveguide exposure structure has hyperbolic characteristics, after fitting and analyzing it, we find that this characteristic can greatly improve the uniformity of the field strength distribution in the photoresist, and thus can effectively improve the depth of focus and increase the exposure depth of the pattern; determine the first resolution of the surface plasmon lithography exposure structure and the second resolution of the single-layer photoresist exposure structure; based on the first resolution and the second resolution, determine the relevant data of the focusing spot symmetry and the increased exposure depth; quantitatively analyze the depth-of-focus data in the relevant data of the focusing spot symmetry and the increased exposure depth corresponding to the surface plasmon lithography exposure structure to determine the corresponding relationship between the depth-of-focus data and the surface plasmon lithography exposure structure; perform a modeling analysis on the dispersion relation data corresponding to the surface plasmon lithography exposure structure to determine the key process parameters that affect the surface plasmon lithography exposure structure to reach the high-frequency mode. By theoretically deriving the dispersion relation of the HPW exposure structure, the process parameters that can regulate its frequency selection characteristics can be obtained, which can provide a theoretical basis for improving the aspect ratio of the surface plasmon lithography exposure pattern.

[0165] The nano-lithography apparatus based on the hybrid surface plasmon waveguide exposure structure provided by the present application can implement the nano-lithography method based on the hybrid surface plasmon waveguide exposure structure as shown in Figures 1 to 10 any one. To avoid repetition, it will not be elaborated here.

[0166] Although the present application has been described in connection with the embodiments, however, in the process of implementing the claimed present application, those skilled in the art can understand and realize other variations of the disclosed embodiments by viewing the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude a plurality. A single processor or other unit may implement several functions recited in the claims. Certain measures are recited in mutually different dependent claims, but this does not mean that these measures cannot be combined to produce good results.

[0167] Although the present application has been described in connection with specific features and their embodiments, it is obvious that various modifications and combinations can be made without departing from the spirit and scope of the present application. Accordingly, the present specification and the drawings are merely exemplary illustrations of the present application defined by the appended claims, and are considered to have covered any and all modifications, variations, combinations, or equivalents within the scope of the present application. Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application is also intended to include these changes and modifications.

Claims

1. A nano-lithography method based on a hybrid surface plasmon waveguide exposure structure, characterized in that, The method includes: obtaining a single-layer photoresist exposure structure in surface plasmon lithography and a surface plasmon lithography exposure structure based on a hybrid surface plasmon waveguide exposure structure; using the finite-difference time-domain method to quantitatively analyze the field intensity distribution in the photoresist in the surface plasmon lithography exposure structure and the single-layer photoresist exposure structure respectively to determine the field intensity distribution data; based on the field intensity distribution data of the surface plasmon lithography exposure structure, combining the hyperbola fitting method to determine the theoretical analytical formula of the exposure pattern depth of the surface plasmon lithography exposure structure; determining a first resolution of the surface plasmon lithography exposure structure and a second resolution of the single-layer photoresist exposure structure; based on the first resolution and the second resolution, determining the relevant data of the focusing spot symmetry and increasing the exposure depth; quantitatively analyzing the depth of field data in the relevant data of the focusing spot symmetry and increasing the exposure depth corresponding to the surface plasmon lithography exposure structure to determine the corresponding relationship between the depth of field data and the surface plasmon lithography exposure structure; modeling and analyzing the dispersion relation data corresponding to the surface plasmon lithography exposure structure to determine the key process parameters affecting the surface plasmon lithography exposure structure to reach the high-frequency mode.

2. The method according to claim 1, wherein The using the finite-difference time-domain method to quantitatively analyze the field intensity distribution in the photoresist in the surface plasmon lithography exposure structure and the single-layer photoresist exposure structure respectively to determine the field intensity distribution data includes: using the finite-difference time-domain method to quantitatively analyze the field intensity distribution in the photoresist in the single-layer photoresist exposure structure to determine the corresponding field intensity distribution data. The field intensity distribution data in the photoresist in the single-layer photoresist exposure structure decays rapidly in an exponential form and cannot participate in imaging, and the exposure depth is less than the preset exposure depth threshold; using the finite-difference time-domain method to quantitatively analyze the field intensity distribution in the photoresist in the surface plasmon lithography exposure structure to determine the corresponding field intensity distribution data. The field intensity distribution data in the photoresist in the surface plasmon lithography exposure structure is the data of amplifying and enhancing the evanescent wave component based on the hybrid waveguide mode formed in the photoresist in the surface plasmon lithography exposure structure, participating in imaging, and the corresponding exposure depth increases.

3. The method according to claim 1, characterized in that, The based on the field intensity distribution data of the surface plasmon lithography exposure structure, combining the hyperbola fitting method to determine the theoretical analytical formula of the exposure pattern depth of the surface plasmon lithography exposure structure includes: determining the field intensity attenuation characteristic data based on the field intensity distribution data in the photoresist in the surface plasmon lithography exposure structure; modeling and analyzing the field intensity attenuation characteristic data, and combining the hyperbola fitting method to determine the theoretical analytical formula of the exposure pattern depth; ； Among them, the represents the exposure pattern depth, the represents the base value of the exposure pattern depth, the and the represent the diffusion function coefficient, the represents the exposure structure diameter, the represents the field strength attenuation characteristic data.

4. The method according to claim 1, characterized in that, The hybrid surface plasmon waveguide exposure structure is a sandwich structure composed of metal-dielectric-metal, including a bowtie nano-aperture structure, the photoresist, and a nano-silver film reflective layer arranged in sequence.

5. The method according to claim 4, characterized in that, The based on the first resolution and the second resolution, determining the relevant data of the focusing spot symmetry and increasing the exposure depth includes: Compare and analyze the first resolution and the second resolution. The first resolution has asymmetry and large field divergence, while the second resolution has symmetry and a uniform field strength distribution. Determine the relevant data for the symmetry of the focused spot and the increase in exposure depth.

6. The method according to claim 1, wherein Quantitatively analyze the depth-of-field data in the relevant data for the symmetry of the focused spot and the increase in exposure depth corresponding to the surface plasmon lithography exposure structure, and determine the corresponding relationship between the depth-of-field data and the surface plasmon lithography exposure structure, including: Obtain the corresponding relationship between the exposure depth and the exposure contrast in the photoresist of the surface plasmon lithography exposure structure; Based on the corresponding relationship between the exposure depth and the exposure contrast, and in combination with the overall contrast and the depth-of-field data, determine the corresponding relationship between the depth-of-field data and the surface plasmon lithography exposure structure.

7. The method according to claim 4, wherein Perform a modeling analysis on the dispersion relation data corresponding to the surface plasmon lithography exposure structure to determine the key process parameters that affect the surface plasmon lithography exposure structure to reach the high-frequency mode, including: Perform a modeling analysis on the dispersion relation data corresponding to the surface plasmon lithography exposure structure to determine that the transverse wave vector of the surface plasmon surface wave is greater than the vacuum wave vector, and the surface plasmon surface wave is much smaller than the incident light wave. Under the condition of satisfying phase matching, determine the key process parameters.

8. The method according to claim 7, characterized in that The key process parameters include: the aperture characteristic size of the bowtie nano-aperture structure, the thickness of the photoresist, and the thickness of the nano-silver film reflective layer.

9. A nano-lithography device based on a hybrid surface plasmon waveguide exposure structure, characterized in that, A device for implementing the nano-lithography method based on the hybrid surface plasmon waveguide exposure structure according to any one of claims 1-8, the device includes: An acquisition module for acquiring a single-layer photoresist exposure structure in surface plasmon lithography and a surface plasmon lithography exposure structure based on the hybrid surface plasmon waveguide exposure structure; A first determination module for quantitatively analyzing the field strength distribution in the photoresist of the surface plasmon lithography exposure structure and the single-layer photoresist exposure structure respectively by using the finite-difference time-domain method to determine the field strength distribution data; A second determination module for determining the theoretical analytical formula of the exposure pattern depth of the surface plasmon lithography exposure structure in combination with the hyperbola fitting method based on the field strength distribution data of the surface plasmon lithography exposure structure; A third determination module for determining the first resolution of the surface plasmon lithography exposure structure and the second resolution of the single-layer photoresist exposure structure; A fourth determination module for determining the relevant data for the symmetry of the focused spot and the increase in exposure depth based on the first resolution and the second resolution; A fifth determination module for quantitatively analyzing the depth-of-field data in the relevant data for the symmetry of the focused spot and the increase in exposure depth corresponding to the surface plasmon lithography exposure structure to determine the corresponding relationship between the depth-of-field data and the surface plasmon lithography exposure structure; A sixth determination module, configured to perform modeling analysis on the dispersion relation data corresponding to the surface plasmon lithography exposure structure, and determine key process parameters that affect the surface plasmon lithography exposure structure to reach a high-frequency mode.

10. The device according to claim 9, characterized in that, The first determination module includes: A first determination sub-module, configured to quantitatively analyze the field strength distribution in the photoresist of the single-layer photoresist exposure structure by using the finite-difference time-domain method to determine the corresponding field strength distribution data. The field strength distribution data in the photoresist of the single-layer photoresist exposure structure rapidly decays in an exponential form and cannot participate in imaging, and the exposure depth is less than a preset exposure depth threshold; A second determination sub-module, configured to quantitatively analyze the field strength distribution in the photoresist of the surface plasmon lithography exposure structure by using the finite-difference time-domain method to determine the corresponding field strength distribution data. The field strength distribution data in the photoresist of the surface plasmon lithography exposure structure is data with an increased exposure depth that is formed by amplifying and enhancing the evanescent wave component based on the hybrid waveguide mode formed in the photoresist of the surface plasmon lithography exposure structure and participates in imaging.

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