Near-field photoetching nanometer pattern processing system based on interference type space phase imaging

Abstract

The invention discloses a near-field direct-writing nanometer pattern processing system based on interference type space phase imaging. The method comprises the following steps: firstly, preparing a photoetching head, depositing a hyperbolic dispersion cavity consisting of a plurality of groups of metals and dielectric films on a transparent substrate, then sputtering a layer of metal film on the hyperbolic dispersion cavity to serve as an excitation layer, and preparing a surface plasma lens for bunching incident light and a grating structure for interferometric space phase imaging on the surface of the excitation layer. And then spin-coating a tackifier and a photoresist photosensitive layer on the surface of the disc substrate. A gap between a photoetching head and a photoresist disc is detected by utilizing an interference type space phase imaging principle and is controlled to be about 20nm, the intensity and the working distance of a surface plasmon beaming light field are improved by utilizing a compensation effect of a hyperbolic dispersion cavity on the photoetching head, and energy attenuation of the surface plasmon in a photoetching direction is compensated; therefore, the depth-to-width ratio of a processing structure of the nano pattern processing system for direct-writing near-field photoetching based on interference type space phase imaging is improved, good steepness is achieved, and high-efficiency, high-resolution and low-cost direct-writing nano processing is achieved. The method can be applied to the field of nano photoetching.

Description

Technical Field

[0001] The present invention belongs to the field of nano-processing technology, and in particular relates to a near-field photolithography nano-patterning processing system based on interferometric spatial phase imaging. Background Art

[0002] Because of its ability to efficiently process nanoscale fine structures, photolithography technology is widely used in fields such as integrated circuits, micro-electromechanical systems, and data storage. With the advancement of nanomanufacturing technology, improving resolution has become the key to future development. Currently, the main technologies for precision below 10nm include optical immersion exposure, extreme ultraviolet exposure, multiple exposure, and interference exposure. However, high equipment costs and limited processing capabilities, especially in the processing of complex structures, have restricted the widespread application of these technologies, which in turn has affected the further development of my country's high-precision nanomanufacturing industry. Therefore, breaking through these technical bottlenecks and promoting the application of photolithography technology in more fields has become an important direction for the development of the industry.

[0003] Near-field lithography, an emerging lithography technology, boasts resolution capabilities exceeding the diffraction limit, enabling the processing of complex nanoscale patterns within the near-field region on a macroscopic scale. Its high efficiency, low cost, and high resolution give it broad application potential in nanofabrication. Lithography based on interferometric spatial phase imaging utilizes the principle of interferometric spatial phase imaging to control the distance between the photolithography head and the disk, thereby achieving a near-field processing environment and effectively maintaining a working distance below 20nm. When wave vector matching conditions are met, the plasma lens can excite evanescent surface plasmon waves, carrying subtle information. This allows the photoresist coated on the disk surface to be exposed, resulting in high-resolution nanostructures that exceed the diffraction limit. Summary of the Invention

[0004] The purpose of the present invention is to provide a near-field photolithography nano-patterning processing system based on interferometric spatial phase imaging, which has the ability to break through the diffraction limit for photolithography processing and solve the problems of low aspect ratio and low resolution of other nano-patterning processing technologies.

[0005] The technical solution to implement the present invention is: a near-field lithography nanopatterning system based on interferometric spatial phase imaging, which is specifically implemented according to the following steps:

[0006] (1) Select the disc substrate;

[0007] (2) preparing an organic photoresist film layer on the upper surface of the disk, with a film thickness of 30 nm to 50 nm;

[0008] (3) Selecting a transparent substrate for the photolithography head;

[0009] (4) A hyperbolic dispersion cavity composed of multiple sets of metal and dielectric films is fabricated at the center of a transparent substrate. The thickness of the metal and dielectric layers is 10 nm to 30 nm, and the length and width of the hyperbolic dispersion cavity are 1 mm × 1 mm.

[0010] (5) Processing a metal film on the hyperbolic dispersion cavity to serve as an excitation layer, with a film thickness of 30nm to 60nm;

[0011] (6) processing a bow-tie hole structure penetrating the metal excitation layer on the metal excitation layer;

[0012] (7) processing a plurality of symmetrical alternating semicircular periodic structures that are concentric with the bow-tie hole structure and penetrate the metal excitation layer on the metal excitation layer, and preparing a surface plasmon lens, wherein the characteristic size and period of each unit structure in the nanostructure in the excitation layer are smaller than the wavelength of the illumination light;

[0013] (8) Four sets of interferometric spatial phase imaging gratings are machined at the four corners of the transparent substrate. The gratings are composed of rectangles whose sizes vary according to a certain rule and form a chessboard-like structure.

[0014] (9) The incident light is focused by the surface plasmon lens obtained in step (7), and the distance between the photolithography head and the disk is detected by using the principle of interferometric spatial phase imaging to expose the photoresist disk obtained in step (2) in the near field;

[0015] (10) The exposed part is developed to obtain a nano-fabrication pattern.

[0016] The disc material in step (1) is silicon dioxide.

[0017] The photoresist film layer in step (2) is a photoresist film layer that is sensitive to ultraviolet light.

[0018] The method for preparing the ultraviolet light-sensitive photoresist film layer in step (2) is spin coating, and the spin coating speed is 2000-4000 rpm.

[0019] The transparent substrate material in step (3) is quartz.

[0020] In the step (4), the metal in the metal-dielectric multilayer hyperbolic dispersion cavity is a good conductor material, and the metal material can be Ag, Al, Cr, Au, etc., and the dielectric material can be SiO2, TiO2, etc., and the processing method is magnetron sputtering or electrochemical deposition.

[0021] The material of the metal excitation layer in step (5) is Ag, Al, Cr, Au, etc., and the processing method is evaporation or sputtering.

[0022] In the step (7), the initial radius r1 of the semicircular groove periodic structure on one side of the bow-tie structure is 100 nm to 200 nm, and preferably the initial radius r1 is 160 nm.

[0023] In step (7), the semicircular groove periodic structure has an initial radius r1 as the inner boundary and one or more periods extending along the radial edge of the disk as the outer boundary. The period distance is 150nm to 200nm, and preferably the period distance is 160nm.

[0024] In the step (7), the initial radius r2 of the semicircular groove periodic structure on the other side of the bow-tie structure is 80nm to 180nm, and the periodic distance is consistent with that on the opposite side. Preferably, the initial radius r2 is 140nm.

[0025] In step (7), the semicircular groove periodic structure has an initial radius r2 as the inner boundary and one or more periods extending along the radial edge of the disk as the outer boundary. The period distance is consistent on both sides and is 150nm to 200nm.

[0026] The width w of the semicircular grooves of the semicircular groove periodic structure in step (7) is 50 nm to 80 nm.

[0027] The number of periodic circular grooves in step (7) is 2 to 6.

[0028] The method for preparing the interferometric spatial phase imaging grating in step (8) is photolithographic pattern transfer.

[0029] In the step (9), the incident light is ultraviolet polarized light.

[0030] In step (9), the incident light excites surface plasmons at the interface between the metal excitation layer and the air through the surface plasmon lens, and the surface plasmons propagate on the surface of the metal excitation layer. Then, the surface plasmons are further amplified by the hyperbolic dispersion cavity and coupled to form a focused light spot at the center of the bow-tie structure. The focused light spot exposes the photoresist film layer on the surface of the disk.

[0031] The present invention also provides a processing system for implementing the above-mentioned nano-pattern processing method. The processing system includes a disk carrier, which is used to carry a disk, and a UV-sensitive photoresist film layer is prepared on the disk; a movable stage, which is used to adjust the position of the disk carrier; an optical component, which is used to generate ultraviolet polarized incident light suitable for exciting surface plasmons, and the optical component includes an ultraviolet laser generator, an ultraviolet reflector, and a pre-focusing lens; and an observation component, which is used to observe the interference pattern generated by the interferometric spatial phase imaging grating, and the observation component includes an infrared laser generator and a CCD camera.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. This direct-write near-field lithography nanopatterning system is based on the principle of interferometric spatial phase imaging. It can detect the working distance between the lithography head and the disk in real time, ensuring stable near-field processing height.

[0034] 2. A metal-dielectric multilayer hyperbolic dispersion cavity is processed on the lithography head. The distance between two adjacent metal-dielectric interfaces is smaller than the skin depth of the surface plasmon. The surface plasmons will interact with each other and cause mode coupling, allowing the surface plasmons to propagate from one interface to the next, achieving super-resolution transmission and compensating for the energy attenuation of the surface plasmons excited by the metal excitation layer on the transparent substrate in the etching direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of the three-dimensional structure of the surface plasmon lens of the embodiment.

[0036] Figure 2 Schematic diagram of the cross-sectional structure of the surface plasmon lens of the embodiment.

[0037] Figure 3 Schematic diagram of the interferometric spatial phase imaging grating structure of an embodiment.

[0038] Figure 4 The invention relates to a nanometer pattern processing system for direct-write near-field lithography based on interferometric spatial phase imaging.

[0039] The marks in the figure mean as follows: 1 is the illumination beam, 2 is the transparent substrate, 3 is the metal thin film excitation layer, 4 is the dielectric film layer, 5 is the metal film layer, 6 is the nanostructure on the excitation layer, 7 is the ultraviolet laser generator, 8 is the polarizer, 9 is the pre-focusing lens, 10 is the ultraviolet reflector, 11 is the integrated infrared laser generator and CCD camera, 12 is the photolithography head, 13 is the disk, and 14 is the disk carrier. DETAILED DESCRIPTION

[0040] The embodiments of the present invention are described in detail below. It will be appreciated by those skilled in the art that the following embodiments are intended to explain the present invention and should not be considered as limiting the present invention. Unless otherwise specified, specific techniques or conditions are not clearly described in the following examples. Those skilled in the art can proceed according to conventional techniques or conditions in this area or according to product specifications. Reagents or instruments used without manufacturer's indication are conventional products available on the market.

[0041] The present invention provides a near-field lithography nano-patterning system based on interferometric spatial phase imaging, which specifically includes the following steps:

[0042] (1) First, select the disk substrate material. In this embodiment, a silicon dioxide disk is selected as the substrate. Figure 2 As shown;

[0043] (2) Prepare an organic photoresist film layer that is sensitive to ultraviolet light on the upper surface of the disk. The thickness of the organic photoresist film layer is 30nm to 50nm. Figure 2 As shown;

[0044] (3) Selecting a transparent substrate for the photolithography head. In this embodiment, quartz is selected as the transparent substrate material, such as Figure 2 As shown;

[0045] (4) A hyperbolic dispersion cavity composed of multiple sets of metal and dielectric films is fabricated at the center of the transparent substrate. The thickness of the metal and dielectric layers is 10nm to 30nm, and the length and width of the hyperbolic dispersion cavity are 1mm×1mm. Figure 2 As shown;

[0046] (5) A metal film is processed on the hyperbolic dispersion cavity to serve as the excitation layer, with a film thickness of 30nm to 60nm, such as Figure 2 As shown;

[0047] (6) Processing a bow-tie hole structure penetrating the metal excitation layer on the metal excitation layer, such as Figure 2 As shown;

[0048] (7) A plurality of symmetrical alternating semicircular ring periodic structures that are concentric with the bow-tie hole structure and penetrate the metal excitation layer are processed on the metal excitation layer, and a surface plasmon lens is prepared, such as Figure 2 As shown;

[0049] (8) Four sets of interferometric spatial phase imaging gratings are processed at the four corners of the transparent substrate. The gratings are composed of rectangles whose sizes change according to a certain rule to form a chessboard-like structure, such as Figure 3 As shown;

[0050] (9) The incident light is focused by the surface plasmon lens obtained in step (7), and the distance between the photolithography head and the disk is detected by using the principle of interferometric spatial phase imaging, and the photoresist disk obtained in step (2) is exposed in the near field;

[0051] (10) The exposed part is developed to obtain a nano-fabrication pattern.

[0052] The disc material in step (1) is silicon dioxide.

[0053] The photoresist film layer in step (2) is a photoresist film layer that is sensitive to ultraviolet light.

[0054] The method for preparing the ultraviolet light-sensitive photoresist film layer in step (2) is spin coating, and the spin coating speed is 2000-4000 rpm.

[0055] The transparent substrate material in step (3) is quartz.

[0056] In the step (4), the metal in the metal-dielectric multilayer hyperbolic dispersion cavity is a good conductor material, and the metal material can be Ag, Al, Cr, Au, etc., and the dielectric material can be SiO2, TiO2, etc., and the processing method is magnetron sputtering or electrochemical deposition.

[0057] The material of the metal excitation layer in step (5) is Ag, Al, Cr, Au, etc., and the processing method is evaporation or sputtering.

[0058] In the step (7), the initial radius r1 of the semicircular groove periodic structure on one side of the bow-tie structure is 100 nm to 200 nm, and preferably the initial radius r1 is 160 nm.

[0059] In step (7), the semicircular groove periodic structure has an initial radius r1 as the inner boundary and one or more periods extending along the radial edge of the disk as the outer boundary. The period distance is 150nm to 200nm, and preferably the period distance is 160nm.

[0060] In the step (7), the initial radius r2 of the semicircular groove periodic structure on the other side of the bow-tie structure is 80nm to 180nm, and the periodic distance is consistent with that on the opposite side. Preferably, the initial radius r2 is 140nm.

[0061] In step (7), the semicircular groove periodic structure has an initial radius r2 as the inner boundary and one or more periods extending along the radial edge of the disk as the outer boundary. The period distance is consistent on both sides and is 150nm to 200nm.

[0062] The width w of the semicircular grooves of the semicircular groove periodic structure in step (7) is 50 nm to 80 nm.

[0063] The number of periodic circular grooves in step (7) is 2 to 6.

[0064] The method for preparing the interferometric spatial phase imaging grating in step (8) is photolithographic pattern transfer.

[0065] In the step (9), the incident light is ultraviolet polarized light.

[0066] In step (9), the incident light excites surface plasmons at the interface between the metal excitation layer and the air through the surface plasmon lens, and the surface plasmons propagate on the surface of the metal excitation layer. Then, the surface plasmons are further amplified by the hyperbolic dispersion cavity and coupled to form a focused light spot at the center of the bow-tie structure. The focused light spot exposes the photoresist film layer on the surface of the disk.

[0067] The present invention also provides a processing system for implementing the above-mentioned nano-pattern processing method. The processing system includes a disk carrier, which is used to carry a disk, and a UV-sensitive photoresist film layer is prepared on the disk; a movable stage, which is used to adjust the position of the disk carrier; an optical component, which is used to generate ultraviolet polarized incident light suitable for exciting surface plasmons, and the optical component includes an ultraviolet laser generator, an ultraviolet reflector, and a pre-focusing lens; and an observation component, which is used to observe the interference pattern generated by the interferometric spatial phase imaging grating, and the observation component includes an infrared laser generator and a CCD camera.

[0068] In this embodiment, if Figure 3 The figure shows an interferometric spatial phase imaging grating provided by an embodiment of the present invention. The X-direction grating has a fixed period of 2μm and a duty cycle of 1:1, while the Y-direction grating has a variable period. The principle of interferometric spatial phase imaging relies on the interference of light waves. It utilizes two laser beams emitted by a light source, one of which serves as a reference beam, while the other is reflected or scattered back to a detector after irradiating the surface of an object. When the surface undergoes slight fluctuations, the propagation path of the light waves changes, causing the phase of the reflected or scattered light to shift, which in turn causes changes in the interference fringes. By measuring the spatial distribution and morphology of these interference fringes, information about changes in the surface height of the object can be obtained. When the laser beam impinges on the interferometric spatial phase imaging grating, based on the principles of wave optics, a series of diffraction and interference phenomena occur between the photolithography head and the disk. A CCD detector captures the interference fringe information and calculates the spacing between the photolithography head and the disk. This data is then used for comparison. If the photolithography head and disk are not parallel, the spacing values ​​measured at different marking positions will differ. By comparing these values, the actual distance between the photolithography head and the platter is determined, and the height of the platter carrier is adjusted accordingly. The adjusted distance is then remeasured and compared with the previous distance data. This process is repeated until all measured distances are consistent, indicating that the photolithography head and platter are parallel.

[0069] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A near-field direct-writing nano-patterning system based on interferometric spatial phase imaging, characterized in that: The specific steps include: (1) First, select the disc substrate, the disc material is silicon dioxide; (2) preparing an organic photoresist film layer that is sensitive to ultraviolet light on the upper surface of the disk, wherein the thickness of the organic photoresist film layer is 30 nm to 50 nm, and the preparation method is spin coating at a spin coating speed of 2000 to 4000 rpm; (3) Selecting a transparent substrate for the photolithography head, the transparent substrate is quartz or sapphire; (4) A hyperbolic dispersion cavity composed of multiple sets of metal and dielectric films is fabricated at the center of a transparent substrate. The metal materials can be Ag, Al, Cr, Au, etc., and the dielectric materials can be SiO2, TiO2, etc. The fabrication method is magnetron sputtering or electrochemical deposition. The thickness of the metal and dielectric layers is 10nm to 30nm, and the length and width of the hyperbolic dispersion cavity are 1mm×1mm. (5) Processing a metal film on the hyperbolic dispersion cavity to serve as the excitation layer. The metal material is Ag, Al, Cr, Au, etc., and the processing method is evaporation or sputtering. The film thickness is 30nm to 60nm; (6) processing a bow-tie hole structure penetrating the metal excitation layer on the metal excitation layer; (7) processing a plurality of symmetrical alternating semicircular ring periodic structures that are concentric with the bow-tie hole structure and penetrate the metal excitation layer on the metal excitation layer, and preparing a surface plasmon lens; (8) Four sets of interferometric spatial phase imaging gratings are processed at the four corners of the transparent substrate. The gratings are composed of rectangles whose sizes change according to a certain rule to form a chessboard-like structure. The processing method is photolithographic pattern transfer; (9) The incident light is focused by the surface plasmon lens obtained in step (7), and the distance between the photolithography head and the disk is detected by using the principle of interferometric spatial phase imaging to expose the photoresist disk obtained in step (2) in the near field; (10) The exposed part is developed to obtain a nano-fabrication pattern.

2. The near-field direct-writing nano-patterning processing system based on interferometric spatial phase imaging according to claim 1, characterized in that: In step (7), the initial radius of the semicircular groove periodic structure on one side of the bow-tie hole structure is 100nm to 200nm, the semicircular groove periodic structure uses the initial radius as the inner boundary and extends one or more periods along the radial edge of the disk as the outer boundary, and the period distance is 150nm to 200nm. The initial radius of the semicircular groove periodic structure on the other side of the bow-tie structure is 80nm to 180nm, the semicircular groove periodic structure uses the initial radius as the inner boundary and extends one or more periods along the radial edge of the disk as the outer boundary, and the period distance is consistent on both sides, and the period distance is 150nm to 200nm. The characteristic size and period of each unit structure in the nanostructure in the excitation layer are both smaller than the wavelength of the illumination light.

3. The near-field direct-writing nano-patterning processing system based on interferometric spatial phase imaging according to claim 1, characterized in that: The width of the semicircular grooves of the semicircular groove periodic structure in step (7) is 50 nm to 80 nm.

4. The near-field direct-writing nano-patterning processing system based on interferometric spatial phase imaging according to claim 1, characterized in that: The exposure step in step (9) further includes exciting surface plasmons at the interface between the metal excitation layer and the air through the surface plasmon lens via incident light, the light source used for exposure being an ultraviolet light source, the surface plasmons propagating on the surface of the metal excitation layer, and then the surface plasmons are further amplified by the hyperbolic dispersion cavity, coupled at the center of the bow-tie structure to form a beam spot, and the beam spot exposes the photoresist film layer on the surface of the disk.

5. The near-field direct-writing nano-patterning processing system based on interferometric spatial phase imaging according to claim 1, characterized in that: include: a disc carrier, the disc carrier being used to carry a disc, the disc being provided with a UV-sensitive photoresist film layer; and a movable platform, the movable platform being used to adjust the position of the disc carrier; An optical component for generating ultraviolet polarized incident light suitable for exciting surface plasmons, the optical component comprising an ultraviolet laser generator, an ultraviolet reflector, and a pre-focusing lens; an observation component for observing interference patterns generated by an interferometric spatial phase imaging grating, the observation component comprising an infrared laser generator and a CCD camera.

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