CN117130230A - Interference lithography method based on deep ultraviolet radiation source - Google Patents
Interference lithography method based on deep ultraviolet radiation source Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 65
- 230000005855 radiation Effects 0.000 title claims abstract description 27
- 238000000025 interference lithography Methods 0.000 title claims abstract description 19
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Classifications
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/20—Exposure; Apparatus therefor
- G03F7/2002—Exposure; Apparatus therefor with visible light or UV light, through an original having an opaque pattern on a transparent support, e.g. film printing, projection printing; by reflection of visible or UV light from an original such as a printed image
- G03F7/2004—Exposure; Apparatus therefor with visible light or UV light, through an original having an opaque pattern on a transparent support, e.g. film printing, projection printing; by reflection of visible or UV light from an original such as a printed image characterised by the use of a particular light source, e.g. fluorescent lamps or deep UV light
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/70—Microphotolithographic exposure; Apparatus therefor
- G03F7/70008—Production of exposure light, i.e. light sources
- G03F7/70033—Production of exposure light, i.e. light sources by plasma extreme ultraviolet [EUV] sources
Abstract
The present disclosure provides an interference lithography method based on deep ultraviolet radiation source, which can be applied to the technical field of micro-nano structure processing, and the method includes: providing a substrate; preparing a multilayer structure on the substrate, wherein the multilayer structure comprises: a second metal layer disposed on the substrate; the photoresist layer is arranged on one side of the second metal layer away from the substrate; the first metal layer is arranged on one side of the photoresist layer, which is far away from the substrate; the first metal layer has a nano periodic structure; irradiating the first metal layer of the multilayer structure with deep ultraviolet light emitted by the deep ultraviolet radiation source, and converting the deep ultraviolet light into surface plasmons under the action of the multilayer structure; and photoetching the photoresist layer by utilizing the surface plasmon so as to form a photoresist pattern, wherein the nano periodic structure has a first period, the photoresist pattern has a second period, and the second period is smaller than the first period.
Description
Technical Field
The present disclosure relates to the technical field of micro-nanostructure processing, and more particularly, to an interference lithography method based on deep ultraviolet radiation sources.
Background
Photolithography is one of the common techniques for processing micro-nanostructures. The photoetching process has the advantages of low cost, high efficiency and the like, and has been widely applied to the fields of processing electronic chips, integrated optical devices and the like.
In implementing the concepts of the present disclosure, the inventors found that at least the following problems exist in the prior art: conventional photolithography processes are limited by the diffraction limit of light, and it is difficult to continue to increase the resolution of the photolithography process, which limits the use of the photolithography process in many fields.
Disclosure of Invention
In view of the foregoing, embodiments of the present disclosure provide an interference lithography method based on an euv radiation source, which can improve the resolution of a lithography process using surface plasmons.
According to an aspect of the present disclosure, there is provided an interference lithography method based on an euv radiation source, comprising the steps of: providing a substrate; preparing a multilayer structure on the substrate, wherein the multilayer structure comprises: a second metal layer disposed on the substrate; the photoresist layer is arranged on one side of the second metal layer away from the substrate; the first metal layer is arranged on one side of the photoresist layer, which is far away from the substrate; the first metal layer has a nano periodic structure; irradiating the first metal layer of the multilayer structure with deep ultraviolet light emitted by the deep ultraviolet radiation source, and converting the deep ultraviolet light into surface plasmons under the action of the multilayer structure; and photoetching the photoresist layer by utilizing the surface plasmon so as to form a photoresist pattern, wherein the nano periodic structure has a first period, the photoresist pattern has a second period, and the second period is smaller than the first period.
According to embodiments of the present disclosure, the wavelength range of deep ultraviolet light includes 157-365 nanometers.
According to an embodiment of the present disclosure, the wavelength of the deep ultraviolet light is 266 nm.
According to an embodiment of the present disclosure, the first period is 40-150 nanometers.
According to an embodiment of the present disclosure, the nano periodic structure includes a protrusion portion protruding in a direction away from the photoresist layer along a propagation direction of the deep ultraviolet light and a flattening portion extending in a plane perpendicular to the propagation direction of the deep ultraviolet light, the protrusion portion and the flattening portion forming a grating.
According to the embodiment of the disclosure, the thickness of the protruding portion in the propagation direction of the deep ultraviolet light is 30-50 nanometers, and the thickness of the flat portion in the propagation direction of the deep ultraviolet light is 10-20 nanometers.
According to an embodiment of the present disclosure, the orthographic projection of the convex portion in a plane perpendicular to the propagation direction of the deep ultraviolet light includes a one-dimensional pattern or a two-dimensional pattern.
According to an embodiment of the present disclosure, the thickness of the second metal layer in the propagation direction of the deep ultraviolet light is not less than 25 nm.
According to an embodiment of the disclosure, the photoresist layer has a thickness of 10-20 nanometers in a propagation direction of the deep ultraviolet light.
According to an embodiment of the present disclosure, the material of the first metal layer comprises at least one of silver, aluminum and magnesium, and/or the material of the second metal layer comprises at least one of silver, aluminum and magnesium.
According to an embodiment of the present disclosure, the multilayer structure further comprises an immersion layer disposed on a side of the first metal layer remote from the substrate.
According to an embodiment of the present disclosure, the material of the immersing layer includes one of water, air, oil, and silicon dioxide.
According to the technical scheme, the interference lithography method based on the deep ultraviolet radiation source provided by the embodiment of the disclosure utilizes the surface plasmon to carry out lithography on the photoresist layer, so that the resolution of the lithography process is improved, the period of a pattern generated in the photoresist is far smaller than that of a nano periodic structure of a first metal layer, and the processing of line width below 10 nanometers can be realized by single exposure. The method adopts multi-mode synergistic effect, and the device is simple to prepare. Meanwhile, the interference lithography method based on the deep ultraviolet radiation source provided by the embodiment of the disclosure has the potential of manufacturing a large-area periodic nano structure, and can be widely used for electromagnetic polarization control, strong field emission, wavelength selective photocurrent enhancement, surface enhanced Raman scattering and the like.
Drawings
The above and other objects, features and advantages of the present disclosure will become more apparent from the following description of the embodiments of the present disclosure with reference to the accompanying drawings. It will be apparent to those of ordinary skill in the art that the drawings in the following description are of some embodiments of the present disclosure and that other drawings may be derived from these drawings without undue effort. In the drawings:
FIG. 1 schematically depicts a flow chart of an interferometric lithography method based on an EUV radiation source according to an embodiment of the present disclosure;
FIG. 2 schematically depicts a front view of a multilayer structure of an interference lithography method based on a deep ultraviolet radiation source according to an embodiment of the present disclosure;
FIG. 3 schematically illustrates a top view of a raised portion employing a one-dimensional grating structure in accordance with an embodiment of the present disclosure;
FIG. 4 schematically illustrates a top view of a raised portion employing a two-dimensional grating structure in accordance with an embodiment of the present disclosure;
FIG. 5 (a) schematically shows an electric field intensity distribution in the photoresist layer of example 1;
FIG. 5 (b) schematically shows a transverse electric field intensity distribution in the photoresist layer of example 1;
FIG. 5 (c) schematically shows a longitudinal electric field intensity distribution in the photoresist layer of example 1;
fig. 5 (d) schematically shows a line scan of the electric field intensity at the center of the photoresist layer of example 1.
Reference numerals: 1-a substrate; 2-a second metal layer; 3-a photoresist layer; 4-a first metal layer; 5-a boss; 6-flattening; 7-immersing the layer; 8-incident light.
Detailed Description
Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be understood that the description is only exemplary and is not intended to limit the scope of the present disclosure. In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the present disclosure. It may be evident, however, that one or more embodiments may be practiced without these specific details. In addition, in the following description, descriptions of well-known structures and techniques are omitted so as not to unnecessarily obscure the concepts of the present disclosure.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The terms "comprises," "comprising," and/or the like, as used herein, specify the presence of stated features, steps, operations, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, or components.
All terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art unless otherwise defined. It should be noted that the terms used herein should be construed to have meanings consistent with the context of the present specification and should not be construed in an idealized or overly formal manner.
Where a formulation similar to at least one of "A, B or C, etc." is used, in general such a formulation should be interpreted in accordance with the ordinary understanding of one skilled in the art (e.g. "a system with at least one of A, B or C" would include but not be limited to systems with a alone, B alone, C alone, a and B together, a and C together, B and C together, and/or A, B, C together, etc.). The terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more of the described features.
Since the conventional photolithography process is limited by the diffraction limit of light, it is difficult to continue to improve the resolution of photolithography. This limits the application of conventional lithographic processes in many fields. A surface plasmon is a surface electromagnetic wave that exists at the interface of a metal and a medium. Since its wavelength is far smaller than that of the illumination light, its application to lithography can improve the resolution of lithography. At present, the surface plasmon lithography process mainly has two implementation schemes: 1. focused plasma beam lithography. It is a maskless plasma beam lithography process that uses a focused plasma beam generated by a plasma lens to generate a pattern. However, since the focused spot size of the plasmon lens increases with an increase in the depth of focus, and the attenuation of the surface plasmon increases with a decrease in wavelength, it is difficult to further improve the resolution of the technique; 2. surface plasmon interference lithography. The method is a photoetching process for exposing by utilizing the surface plasmon interference effect, the resolution can reach one quarter of the wavelength of the surface plasmon, and the method is used for manufacturing a periodic structure with a large area and ultra-small feature size. However, the existing photolithography process based on interference effect still has the problems that the image contrast of the high-resolution pattern is lower than the minimum requirement of the photoresist, and the resolution cannot be further improved.
Based on this, embodiments of the present disclosure provide an interference lithography method based on a deep ultraviolet radiation source.
FIG. 1 schematically depicts a flow chart of an interferometric lithography method based on an EUV radiation source according to an embodiment of the present disclosure.
As shown in fig. 1, the euv radiation source-based interference lithography method of this embodiment includes operations S101 to S104.
In operation S101, a substrate is provided.
In operation S102, a multi-layered structure is prepared on the substrate, wherein the multi-layered structure includes: a second metal layer disposed on the substrate; the photoresist layer is arranged on one side of the second metal layer away from the substrate; the first metal layer is arranged on one side of the photoresist layer, which is far away from the substrate; the first metal layer has a nano-periodic structure.
In operation S103, the first metal layer of the multilayer structure is irradiated with deep ultraviolet light emitted from the deep ultraviolet radiation source, and the deep ultraviolet light is converted into surface plasmons under the action of the multilayer structure.
According to the embodiment of the disclosure, the wavelength range of the deep ultraviolet light comprises 157-365 nanometers, and has the characteristics of short wavelength, large energy, narrow pulse width, high power, small thermal effect and the like. The wavelength range of the incident light in the deep ultraviolet band may include 157-365 nm, for example, 193 nm, 266 nm, and the like.
Preferably, the wavelength of the deep ultraviolet light is 266 nm. The 266 nm deep ultraviolet light has the characteristics of short wavelength, large energy, narrow pulse width, high power, small thermal effect and the like. Compared with laser with larger wavelength, the 266 nm deep ultraviolet wavelength is short, so that under the same optical aperture condition, the diffraction limit angle is smaller, and the resolution ratio is higher. Compared with extreme ultraviolet light with smaller wavelength, the 266 nm deep ultraviolet light has high power, the matched photoetching technology is more mature, the cost is lower, and the stable production can be realized. Thus, in embodiments of the present disclosure, lithography using 266 nm deep ultraviolet light may be preferred.
In operation S104, the photoresist layer is subjected to photolithography using the surface plasmon to form a photoresist pattern, wherein the nano periodic structure has a first period, and the photoresist pattern has a second period, which is smaller than the first period, thereby improving the resolution of the photolithography process.
According to the interference lithography method based on the deep ultraviolet radiation source, the first metal layer with the nano periodic structure is used as a mask, an incident light field is absorbed, the incident light field is converted into the antisymmetric coupling surface plasmons with the ultra-short wavelength under the combined action of the second metal layer, and then the surface plasmons are used for carrying out lithography on the photoresist layer, so that patterns with ultra-high resolution are generated in the photoresist layer, and the resolution of a lithography process is improved.
Surface plasmons are a mode of electromagnetic waves caused by the free electron interaction of light and a metal surface. In an embodiment of the present disclosure, the photoresist layer and the second metal layer constitute a surface plasmon waveguide by introducing a first metal layer. Wherein the first metal layer and the photoresist layer have opposite dielectric constants, and the photoresist layer and the second metal layer also have opposite dielectric constants. When deep ultraviolet light enters the surface plasmon waveguide, surface plasmons can be excited at the interface of the first metal layer and the photoresist layer and at the interface of the photoresist layer and the second metal layer. The first metal layer and the second metal layer form the surface plasmon resonance cavity, so that the wave vector of the surface plasmon can be obviously changed and regulated, the surface plasmon propagating in opposite directions is further formed, and interference fringes are formed in the photoresist layer by the surface plasmon. The effective wavelength of the surface plasmon is equal to 2 pi divided by the propagation constant of the surface plasmon, and the wavelength of the surface plasmon is far smaller than the wavelength of incident deep ultraviolet light, so that the method can improve the resolution of a photoetching process, obtain interference fringe resolution of super diffraction limit, and further obtain a photoresist pattern with ultra-narrow linewidth.
According to an embodiment of the present disclosure, the first period of the nano-periodic structure is 40 to 150 nanometers, and the second period of the photoresist pattern is in the range of 20 to 50 nanometers, and preferably, the ratio of the second period to the first period is less than 0.25. Since the second period of the photoresist pattern is much smaller than the first period, a single exposure can achieve processing of line widths below 10 nanometers.
Fig. 2 schematically illustrates a front view of a multilayer structure of an interference lithography method based on a deep ultraviolet radiation source according to an embodiment of the present disclosure.
As shown in fig. 2, the multilayer structure includes a substrate 1, a second metal layer 2, a photoresist layer 3, and a first metal layer 4. The substrate 1 may be a substrate known in the art, including but not limited to a monocrystalline silicon substrate sheet, silicon nitride, a metal substrate, a silicon oxide substrate, a glass substrate, sapphire, a group III-V substrate, etc., and a preferred substrate is a silicon substrate. In the embodiment of the present disclosure, when a multilayer structure is prepared, a metal thin film, for example, a film plating by an electron beam evaporation process, may be prepared on the substrate 1 using a vacuum plating method. Wherein the underlying metal film may be prepared as the second metal layer 2 by an electron beam evaporation process. Further, the photoresist layer 3 may be prepared on the surface of the second metal layer 2 by a spin coating method. The metal film is again prepared by an electron beam evaporation process to obtain a first metal layer 4 adjacent to the photoresist layer 3.
As shown in fig. 2, the first metal layer 4 has a nano periodic structure, according to an embodiment of the present disclosure, the nano periodic structure includes a protrusion 5 and a flattening portion 6, wherein the protrusion 5 protrudes in a direction away from the photoresist layer 3 along a propagation direction of the deep ultraviolet light, the flattening portion 6 extends in a plane perpendicular to the propagation direction of the deep ultraviolet light, the protrusion 5 and the flattening portion 6 form a grating, and when the grating is irradiated with incident light 8 of the deep ultraviolet light, the grating diffracts incident light of the deep ultraviolet light band and generates diffraction waves of different orders, that is, diffraction emitters, for generating surface plasmons.
According to embodiments of the present disclosure, the generation process of surface plasmons may be optimized by optimizing grating parameters to reduce the effective wavelength of the generated surface plasmons. Preferably, the thickness of the protruding portion 5 in the propagation direction of the deep ultraviolet light is 30-50 nanometers, and the thickness of the flat portion 6 in the propagation direction of the deep ultraviolet light is 10-20 nanometers, so that the generated plasmons can realize processing with line width below 10 nanometers.
Fig. 3 schematically illustrates a top view of a raised portion employing a one-dimensional grating structure in accordance with an embodiment of the present disclosure. Fig. 4 schematically illustrates a top view of a raised portion employing a two-dimensional grating structure in accordance with an embodiment of the present disclosure.
As shown in fig. 3, the front projection of the protruding portion 5 in the plane perpendicular to the propagation direction of the deep ultraviolet light is a one-dimensional graph, and the protruding portion 5 adopts a one-dimensional grating structure. As shown in fig. 4, the front projection of the convex portion 5 in the plane perpendicular to the propagation direction of the deep ultraviolet light is a two-dimensional graph, and the convex portion 5 adopts a two-dimensional grating structure. The specific shape of the boss 5 may be selected according to actual circumstances, and embodiments of the present disclosure are not limited.
According to the embodiment of the disclosure, the thickness of the second metal layer 2 in the propagation direction of the deep ultraviolet light is not less than 25 nanometers, so that it is ensured that the surface plasmon generated by the surface plasmon resonance cavity can realize processing of line widths below 10 nanometers.
According to the embodiment of the disclosure, the thickness of the photoresist layer 3 in the propagation direction of the deep ultraviolet light is 10-20 nanometers, and the deep ultraviolet photoresist with the refractive index between 1.7 and 2 is selected. Since the fringe period is very sensitive to the thickness of the photoresist, changing the thickness of the photoresist changes the period of the fringes formed in the photoresist, and thus, in order to improve the resolution of the photolithography process, to achieve processing of line widths below 10 nanometers, the thickness of the photoresist must be tightly controlled.
According to an embodiment of the present disclosure, the material of the first metal layer 4 includes at least one of silver, aluminum and magnesium, and may be a single metal layer formed of any one of silver, aluminum and magnesium or an alloy layer formed of any two or more thereof, and/or the material of the second metal layer 2 includes at least one of silver, aluminum and magnesium, and may be a single metal layer formed of any one of silver, aluminum and magnesium or an alloy layer formed of any two or more thereof. The materials of the first metal layer and the second metal layer may be the same or different, and any metal material that supports the surface plasmon effect in the deep ultraviolet light band may be used, which is not limited in the embodiments of the present disclosure.
According to an embodiment of the present disclosure, the multilayer structure further comprises an immersion layer 7, the immersion layer 7 being arranged on a side of the first metal layer 4 remote from the substrate 1. The immersing layer 7 is mainly formed of a material that absorbs less light field from the incident light.
According to an embodiment of the present disclosure, the material of the immersing layer 7 includes one of water, air, oil and silicon dioxide.
The interference lithography method based on the deep ultraviolet radiation source according to the embodiments of the present disclosure will be described in detail below with reference to the embodiments. It is to be understood that the following description is exemplary only and is not intended to be a specific limitation on the present disclosure.
Example 1
The embodiment provides an interference lithography method based on a deep ultraviolet radiation source, which specifically comprises the following steps:
in operation S101, a substrate is provided. Wherein the substrate is a monocrystalline silicon substrate piece.
In operation S102, a multi-layered structure is prepared on the substrate, wherein the multi-layered structure includes: the second metal layer is arranged on the substrate, the second metal layer is made of aluminum, and the thickness of the second metal layer is 25 nanometers; the photoresist layer is arranged on one side of the second metal layer far away from the substrate, the thickness is 10 nanometers, and the refractive index is 1.9; the first metal layer is arranged on one side of the photoresist layer, far away from the substrate, and is made of aluminum; the first metal layer is provided with a nano periodic structure, the thickness of a protruding part of the nano periodic structure is 30 nanometers, the thickness of a flattening part is 10 nanometers, the first period is 101 nanometers, and the duty ratio is 0.4, wherein the protruding part adopts a one-dimensional grating structure; an immersion layer is arranged on one side of the first metal layer far away from the substrate, and the immersion layer is water
In operation S103, the first metal layer of the multilayer structure is irradiated with 266 nm deep ultraviolet light emitted from the deep ultraviolet radiation source, the deep ultraviolet light is converted into surface plasmons under the action of the multilayer structure, and the polarization direction of the 266 nm deep ultraviolet light adopts a transverse magnetic (Transverse Magnetic, abbreviated as TM) mode because the nano periodic structure of the first metal layer has no symmetry.
In operation S104, the photoresist layer is subjected to photolithography using the surface plasmon to form a photoresist pattern.
Fig. 5 (a) schematically shows an electric field intensity distribution diagram in the photoresist layer of example 1. Fig. 5 (b) schematically shows a lateral electric field intensity distribution in the photoresist layer of example 1. Fig. 5 (c) schematically shows a longitudinal electric field intensity distribution in the photoresist layer of example 1. The ordinate in fig. 5 (a), 5 (b) and 5 (c) is the thickness direction of the multilayer structure, and the abscissa is the horizontal direction of the front view of the multilayer structure.
As shown in fig. 5 (a) -5 (c), in the local field in the photoresist layer of the present embodiment, the longitudinal electric field occupies the dominant component and has good periodic characteristics.
Fig. 5 (d) schematically shows a line scan of the electric field intensity at the center of the photoresist layer of example 1. Wherein, the ordinate is the electric field intensity, and the abscissa is the horizontal direction of the front view of the multilayer structure.
As shown in fig. 5 (d), the normalized period of the interference fringes in the photoresist layer obtained in this embodiment is 23.6 nm, and the normalized contrast ratio can reach 10.8, which indicates that the resolution of the photolithography process is improved.
Example 2
The embodiment provides an interference lithography method based on a deep ultraviolet radiation source, which specifically comprises the following steps:
in operation S101, a substrate is provided. Wherein the substrate is a monocrystalline silicon substrate piece.
In operation S102, a multi-layered structure is prepared on the substrate, wherein the multi-layered structure includes: the second metal layer is arranged on the substrate, the second metal layer is made of aluminum, and the thickness of the second metal layer is 25 nanometers; the photoresist layer is arranged on one side of the second metal layer far away from the substrate, the thickness is 15 nanometers, and the refractive index is 2; the first metal layer is arranged on one side of the photoresist layer, far away from the substrate, and is made of aluminum; the first metal layer is provided with a nano periodic structure, the thickness of a protruding part of the nano periodic structure is 35 nanometers, the thickness of a flat part is 15 nanometers, the first period is 40 nanometers, and the duty ratio is 0.9, wherein the protruding part adopts a one-dimensional grating structure; an immersion layer is arranged on one side, far away from the substrate, of the first metal layer, and the immersion layer is air.
In operation S103, the first metal layer of the multilayer structure is irradiated with 266 nm deep ultraviolet light emitted by the deep ultraviolet radiation source, the deep ultraviolet light is converted into surface plasmons under the action of the multilayer structure, and the polarization direction of the 266 nm deep ultraviolet light adopts a transverse magnetic mode because the nano periodic structure of the first metal layer has no symmetry.
In operation S104, the photoresist layer is subjected to photolithography using the surface plasmon to form a photoresist pattern.
The normalized period of the interference fringes in the photoresist layer obtained in the embodiment is 21.9 nanometers, and the normalized contrast ratio can reach 7.1, which indicates that the resolution of the photolithography process is improved.
Example 3
The embodiment provides an interference lithography method based on a deep ultraviolet radiation source, which specifically comprises the following steps:
in operation S101, a substrate is provided. Wherein the substrate is a monocrystalline silicon substrate piece.
In operation S102, a multi-layered structure is prepared on the substrate, wherein the multi-layered structure includes: the second metal layer is arranged on the substrate, the second metal layer is made of aluminum, and the thickness of the second metal layer is 50 nanometers; the photoresist layer is arranged on one side of the second metal layer far away from the substrate, the thickness is 20 nanometers, and the refractive index is 1.7; the first metal layer is arranged on one side of the photoresist layer, far away from the substrate, and is made of aluminum; the first metal layer is provided with a nano periodic structure, the thickness of a protruding part of the nano periodic structure is 50 nanometers, the thickness of a flattening part is 20 nanometers, the first period is 150 nanometers, and the duty ratio is 0.8, wherein the protruding part adopts a one-dimensional grating structure; an immersion layer is arranged on one side, far away from the substrate, of the first metal layer, and the immersion layer is water.
In operation S103, the first metal layer of the multilayer structure is irradiated with 266 nm deep ultraviolet light emitted by the deep ultraviolet radiation source, the deep ultraviolet light is converted into surface plasmons under the action of the multilayer structure, and the polarization direction of the 266 nm deep ultraviolet light adopts a transverse magnetic mode because the nano periodic structure of the first metal layer has no symmetry.
In operation S104, the photoresist layer is subjected to photolithography using the surface plasmon to form a photoresist pattern.
The normalized period of the interference fringes in the photoresist layer obtained in the embodiment is 49.7 nanometers, and the normalized contrast ratio can reach 597.4, which indicates that the resolution of the photolithography process is improved.
The embodiment of the disclosure utilizes the first metal layer with the nano periodic structure as the absorption incident deep ultraviolet light, converts the deep ultraviolet light into surface plasmons with ultra-short wavelength under the combined action of the second metal layer, then uses the surface plasmons to carry out photoetching on the photoresist layer, and generates patterns with ultra-high resolution in the photoresist layer, thereby improving the resolution of the photoetching process. The embodiment of the disclosure not only can realize processing below 10 nanometers, but also has strong expansibility, and the resolution is expected to be improved to 5-7 nanometers by optimizing a material system so as to meet the requirements of the current micro-nano structure processing.
Unless specifically indicated otherwise, the numerical parameters in this specification and the attached claims are approximations that can vary depending upon the desired properties sought to be obtained by the present disclosure. In particular, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term "about". In general, the meaning of expression is meant to include a variation of + -10% in some embodiments, a variation of + -5% in some embodiments, a variation of + -1% in some embodiments, and a variation of + -0.5% in some embodiments by a particular amount.
Those skilled in the art will appreciate that the features recited in the various embodiments of the disclosure and/or in the claims may be provided in a variety of combinations and/or combinations, even if such combinations or combinations are not explicitly recited in the disclosure. In particular, the features recited in the various embodiments of the present disclosure and/or the claims may be variously combined and/or combined without departing from the spirit and teachings of the present disclosure. All such combinations and/or combinations fall within the scope of the present disclosure.
The embodiments of the present disclosure are described above. However, these examples are for illustrative purposes only and are not intended to limit the scope of the present disclosure. Although the embodiments are described above separately, this does not mean that the measures in the embodiments cannot be used advantageously in combination. The scope of the disclosure is defined by the appended claims and equivalents thereof. Various alternatives and modifications can be made by those skilled in the art without departing from the scope of the disclosure, and such alternatives and modifications are intended to fall within the scope of the disclosure.
Claims (12)
1. An interference lithography method based on a deep ultraviolet radiation source, comprising the steps of:
providing a substrate;
preparing a multilayer structure on the substrate, wherein the multilayer structure comprises: a second metal layer disposed on the substrate; the photoresist layer is arranged on one side of the second metal layer away from the substrate; the first metal layer is arranged on one side of the photoresist layer, which is far away from the substrate; the first metal layer has a nano periodic structure;
irradiating the first metal layer of the multilayer structure with deep ultraviolet light emitted by the deep ultraviolet radiation source, and converting the deep ultraviolet light into surface plasmons under the action of the multilayer structure; and
photoetching the photoresist layer by utilizing the surface plasmons to form a photoresist pattern,
the nano periodic structure has a first period, and the photoresist pattern has a second period, which is smaller than the first period.
2. The method of claim 1, wherein the wavelength range of deep ultraviolet light comprises 157-365 nanometers.
3. The method of claim 2, wherein the deep ultraviolet light has a wavelength of 266 nm.
4. The method of claim 1, wherein the first period is 40-150 nanometers.
5. The method of claim 1, wherein the nano-periodic structure comprises a raised portion and a flattened portion, wherein the raised portion is raised away from the photoresist layer along a direction of propagation of the deep ultraviolet light, the flattened portion extends in a plane perpendicular to the direction of propagation of the deep ultraviolet light, and the raised portion and flattened portion form a grating.
6. The method of claim 5, wherein the thickness of the raised portion in the direction of propagation of the deep ultraviolet light is 30-50 nanometers and the thickness of the flattened portion in the direction of propagation of the deep ultraviolet light is 10-20 nanometers.
7. The method of claim 5, wherein the orthographic projection of the boss in a plane perpendicular to the direction of propagation of the deep ultraviolet light comprises a one-dimensional pattern or a two-dimensional pattern.
8. The method of claim 6, wherein the thickness of the second metal layer in the direction of propagation of the deep ultraviolet light is not less than 25 nanometers.
9. The method of claim 8, wherein the photoresist layer has a thickness of 10-20 nanometers in the direction of propagation of the deep ultraviolet light.
10. The method of claim 1, wherein the material of the first metal layer comprises at least one of silver, aluminum, and magnesium, and/or the material of the second metal layer comprises at least one of silver, aluminum, and magnesium.
11. The method of claim 1, wherein the multi-layered structure further comprises an immersing layer disposed on a side of the first metal layer remote from the substrate.
12. The method of claim 11, wherein the material of the immersing layer comprises one of water, air, oil, and silicon dioxide.
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