A Polarization Interference Lithography Method and System for Three-Dimensional Micro-Nano Structures

Abstract

The present invention belongs to the technical field of micro-nano structure processing, and relates to a polarization interference lithography method and system for three-dimensional micro-nano structures. An amplitude spatial light modulation element is used to modulate the amplitude of the incident light field to obtain an amplitude-modulated light field; a crystal holographic optical element is used to modulate the amplitude-modulated light field to obtain a first transmitted light field; a holographic optical element is used to modulate the first transmitted light field to obtain a second transmitted light field on the Fourier spectrum plane; a first Fourier transform lens is used to perform Fourier transforms on the amplitude-modulated light field, the first transmitted light field, and the second transmitted light field to obtain a Fourier-transformed light field; a second Fourier transform lens is used to perform a Fourier transform on the Fourier-transformed light field to obtain an interference light field with adjustable light intensity and phase on the imaging plane; the light intensity and phase of the interference light field are adjusted so that the distribution of the interference light field matches a preset three-dimensional micro-nano structure, thereby preparing the preset three-dimensional micro-nano structure. This solution can prepare three-dimensional micro-nano structures with high precision and small line widths.

Description

Technical Field

[0001] The present invention relates to the technical field of micro-nano structure processing, and in particular to a polarization interference lithography method and system for three-dimensional micro-nano structures. Background Art

[0002] The metasurface is a two-dimensional planar structure that can regulate the characteristics of light such as amplitude, phase, and polarization. Preparing three-dimensional micro-nano structures of various shapes on the metasurface can regulate the light beam incident on the metasurface at different heights and spatial positions, improving the degree of freedom of the metasurface for light beam regulation.

[0003] The existing methods for preparing three-dimensional micro-nano structures on the metasurface mainly include nanosphere lithography and laser direct writing lithography. Among them, the nanosphere lithography technology immerses the substrate in a nanosphere solution, so that the nanospheres in the nanosphere solution self-assemble on the substrate surface to form a closely arranged monolayer or multilayer nanosphere array. A photoresist is coated on the surface of the nanosphere array, and the photoresist is etched using the nanosphere array as a hard mask to obtain a photoresist pattern. Then, the nanosphere array on the substrate is removed, and the substrate is etched based on the remaining photoresist pattern as a mask, so as to transfer the photoresist pattern to the substrate, obtaining a three-dimensional micro-nano structure related to the nanosphere array. The laser direct writing lithography technology means that after coating a photoresist on the substrate, the scanning path and exposure dose of the laser beam are controlled by a computer, and the photoresist is exposed point by point or line by line according to a preset three-dimensional micro-nano structure, so as to form a photoresist pattern on the substrate surface that is the same as the preset three-dimensional micro-nano structure. Finally, the photoresist pattern is transferred to the substrate to obtain a three-dimensional micro-nano structure.

[0004] When using the nanosphere lithography technology to prepare three-dimensional micro-nano structures, the nanospheres are arranged on the substrate surface by self-assembly. Due to the randomness of the self-assembly process, it is difficult to control the spacing and arrangement of the nanospheres, which will lead to the non-uniformity of the nanosphere array formed on the substrate surface. Furthermore, when etching the photoresist pattern using the nanosphere array as a hard mask, it is easy to over-etch the photoresist in the nanosphere-dispersed part and under-etch the photoresist in the nanosphere-dense part, resulting in differences in the depth, shape, etc. of the three-dimensional micro-nano structure at different positions, showing non-uniformity and affecting the accuracy of the three-dimensional micro-nano structure. Although the laser direct writing lithography technology can ensure the processing accuracy of the three-dimensional micro-nano structure, limited by the optical system and laser wavelength, the laser beam will form a spot of a certain size at the exposed part when exposing the photoresist. Since the size of the spot cannot be infinitely reduced, when using the laser direct writing lithography technology to prepare three-dimensional micro-nano structures, it is impossible to define lines with a line width less than 500 nm on the photoresist, that is, it is impossible to prepare three-dimensional micro-nano structures with a line width less than 500 nm.

[0005] In summary, the existing methods for fabricating three-dimensional micro-nano structures cannot fabricate three-dimensional micro-nano structures with high precision and small line widths. Summary of the Invention

[0006] For this reason, the technical problem to be solved by the present invention is to overcome the problem that the existing methods for fabricating three-dimensional micro-nano structures cannot fabricate three-dimensional micro-nano structures with high precision and small line widths.

[0007] To solve the above technical problem, the present invention provides a polarization interference lithography method for three-dimensional micro-nano structures, including:

[0008] Modulating the amplitude of the incident light field by using an amplitude spatial light modulation element to obtain an amplitude-modulated light field;

[0009] Modulating the polarization, amplitude, and phase of the amplitude-modulated light field by using a crystal holographic optical element to obtain a first transmitted light field;

[0010] Modulating the amplitude and phase of the first transmitted light field by using a holographic optical element to obtain a second transmitted light field on the Fourier spectrum plane;

[0011] Performing Fourier transforms on the amplitude-modulated light field, the first transmitted light field, and the second transmitted light field by using a first Fourier transform lens in a Fourier transform optical system to obtain a Fourier transform light field;

[0012] Performing a Fourier transform on the Fourier transform light field by using a second Fourier transform lens in the Fourier transform optical system, so as to obtain an interference light field with adjustable light intensity and phase on the imaging plane;

[0013] Changing the amplitude modulation parameter of the amplitude spatial light modulation element and / or the modulation region of the crystal holographic optical element and / or the distance between the holographic optical element and the Fourier spectrum plane to adjust the light intensity and phase of the interference light field, so that the distribution of the interference light field matches a preset three-dimensional micro-nano structure, thereby fabricating the preset three-dimensional micro-nano structure on the surface of a photosensitive material.

[0014] Preferably, changing the amplitude modulation parameter of the amplitude spatial light modulation element and / or the modulation region of the crystal holographic optical element and / or the distance between the holographic optical element and the Fourier spectrum plane to adjust the light intensity and phase of the interference light field, so that the distribution of the interference light field matches a preset three-dimensional micro-nano structure includes:

[0015] Based on the material parameters of the photosensitive material and the dimensional parameters of the preset three-dimensional micro-nano structure, obtaining the light field distribution function of the preset three-dimensional micro-nano structure;

[0016] Obtaining the light field distribution function of the interference light field, thereby calculating the error between the light field distribution function of the three-dimensional micro-nano structure and the light field distribution function of the interference light field, and determining the magnitude relationship between the error and a preset error threshold;

[0017] When the error is greater than or equal to a preset error threshold, change the amplitude modulation parameter of the amplitude spatial light modulation element and / or the modulation region of the crystal holographic optical element and / or the distance between the holographic optical element and the Fourier spectrum plane to adjust the light intensity and phase of the interference light field;

[0018] Re-obtain the light field distribution function of the interference light field until the error between the light field distribution function of the three-dimensional micro-nano structure and the light field distribution function of the interference light field is less than the preset error threshold.

[0019] Preferably, the Fourier transform light field is expressed as:

[0020] ,

[0021] where, represents the Fourier transform light field; represents the amplitude distribution function of the amplitude spatial light modulation element after being transformed by the first Fourier transform lens; represents the transmitted light field function of the crystal holographic optical element after being transformed by the first Fourier transform lens; represents the transmitted light field function of the holographic optical element after being transformed by the first Fourier transform lens; represents the spatial coordinate of the second transmitted light field on the Fourier spectrum plane; represents a constant factor.

[0022] Preferably, the light field distribution function of the interference light field is expressed as:

[0023] ,

[0024] where, represents the light field distribution function of the interference light field; represents the spatial coordinate of the interference light field on the imaging plane of the Fourier imaging system; represents the amplitude distribution function of the amplitude spatial light modulation element after being transformed by the second Fourier transform lens; represents the transmitted light field function of the crystal holographic optical element after being transformed by the second Fourier transform lens; represents the transmitted light field function of the holographic optical element after being transformed by the first Fourier transform lens; represents a constant factor; represents the focal length of the first Fourier transform lens; represents the focal length of the second Fourier transform lens; represents the distance between the holographic optical element and the Fourier spectrum plane.

[0025] Preferably, the amplitude spatial light modulation element includes a liquid crystal amplitude spatial light modulator, a digital micromirror array, an optical switch, a gray scale mask, an aperture stop; and / or,

[0026] The crystal holographic optical element includes a liquid crystal holographic optical element, a birefringent crystal holographic optical element, and a phase-type spatial light dynamic modulator based on Lcos; and / or,

[0027] The holographic optical element includes a phase-type holographic optical element, an amplitude-type holographic optical element, and a volume holographic optical element.

[0028] Preferably, when preparing a three-dimensional micro-nano structure with a rectangular structure, the amplitude spatial light modulation element is a gray-scale mask, the crystal holographic optical element is a liquid crystal element, and the holographic optical element is a variable spatial frequency one-dimensional grating combination;

[0029] When preparing a three-dimensional micro-nano structure with a pyramid shape, the amplitude spatial light modulation element is a digital micromirror array, the crystal holographic optical element is a birefringent crystal element, and the holographic optical element is a partitioned Fresnel ring.

[0030] The present invention also provides a polarization interference lithography system for a three-dimensional micro-nano structure, including:

[0031] An amplitude spatial light modulation element, configured to modulate the amplitude of an incident light field to obtain an amplitude-modulated light field;

[0032] A crystal holographic optical element, configured to modulate the polarization, amplitude, and phase of the amplitude-modulated light field to obtain a first transmitted light field;

[0033] A holographic optical element, configured to modulate the amplitude and phase of the first transmitted light field to obtain a second transmitted light field on the Fourier spectrum plane;

[0034] A first Fourier transform lens, disposed between the crystal holographic optical element and the holographic optical element, for performing Fourier transform on the amplitude-modulated light field, the first transmitted light field, and the second transmitted light field to obtain a Fourier transform light field;

[0035] A second Fourier transform lens, disposed on the side of the holographic optical element away from the first Fourier transform lens, for performing Fourier transform on the Fourier transform light field, so as to obtain an interference light field with adjustable light intensity and phase on the imaging plane;

[0036] A spatial light modulator, connected to the amplitude spatial light modulation element and the crystal holographic optical element;

[0037] A displacement stage, for placing the holographic optical element;

[0038] The host computer, connected to the spatial light modulator and the displacement stage, is used to control the spatial light modulator to change the amplitude modulation parameter of the amplitude spatial light modulation element and / or the modulation area of the crystal holographic optical element, and control the displacement stage to move to change the distance between the holographic optical element and the Fourier spectrum plane, so as to adjust the light intensity and phase of the interference light field, make the distribution of the interference light field match the preset three-dimensional micro-nano structure, and thus prepare the preset three-dimensional micro-nano structure on the surface of the photosensitive material;

[0039] Wherein, the first Fourier transform lens and the second Fourier transform lens form a coaxial interference system.

[0040] Preferably, the host computer specifically includes:

[0041] The first light field distribution function acquisition module is used to calculate the light field distribution function of the preset three-dimensional micro-nano structure based on the material parameters of the photosensitive material and the size parameters of the preset three-dimensional micro-nano structure;

[0042] The error calculation module is used to obtain the light field distribution function of the interference light field, so as to calculate the error between the light field distribution function of the three-dimensional micro-nano structure and the light field distribution function of the interference light field, and judge the size of the error and the preset error threshold;

[0043] The control module is used to control the spatial light modulator to change the amplitude modulation parameter of the amplitude spatial light modulation element and / or the modulation area of the crystal holographic optical element, and control the displacement stage to move to change the distance between the holographic optical element and the Fourier spectrum plane until the error is less than the preset error threshold when the error is greater than or equal to the preset error threshold.

[0044] Preferably, it further includes:

[0045] The charge coupled device is arranged on the side of the second Fourier transform lens away from the holographic optical element and is connected to the host computer, and is used to photograph the light intensity map of the interference light field and transmit the light intensity map to the host computer, so that the host computer can obtain the light field distribution function of the interference light field based on the light intensity map.

[0046] Preferably, it further includes:

[0047] The micro-reduced optical path is arranged on the side of the second Fourier transform lens away from the first Fourier transform lens, and includes a double telecentric lens and a micro-reduced objective lens arranged in sequence along the optical path propagation direction, and is used to prepare the preset three-dimensional micro-nano structure on the surface of the photosensitive material.

[0048] The polarization interference lithography method for the three-dimensional micro-nano structure provided by the present application has the following beneficial effects:

[0049] In this application, an amplitude modulation spatial light modulation element is first used to modulate the amplitude of an incident light field to obtain an amplitude-modulated light field. After the amplitude-modulated light field enters the crystal holographic optical element, due to the birefringence effect, optical path modulation, diffraction, and scattering effects of the crystal structure inside the crystal holographic optical element, the modulation of phase and polarization can be combined on the basis of the amplitude of the existing amplitude-modulated light field, further enriching the distribution characteristics of the amplitude-modulated light field, so that the distribution characteristics of the first transmitted light field output can meet the complex requirements of the three-dimensional micro-nano structure for the light field; further, a first Fourier transform lens is used to convert the spatial distributions of the amplitude-modulated light field, the first transmitted light field, and the second transmitted light field into the frequency domain. At the same time, the holographic optical element directly acts on the spectral information of the light field, and the amplitude and phase of the light field are finely adjusted in the frequency domain, so that the modulated light field also has richer distribution characteristics in the frequency domain, and thus can be used to prepare three-dimensional micro-nano structures of various shapes; finally, a second Fourier transform lens is used to perform a Fourier transform on the Fourier transform light field again to convert it back to the spatial domain to form an interference light field with adjustable light intensity and phase on the imaging plane; since the interference light field generated on the imaging plane is the result of multiplying the amplitude-modulated light field, the transmitted light field modulated by the crystal holographic optical element, and the transmitted light field modulated by the holographic optical element after two Fourier transforms respectively, its light intensity distribution and phase distribution are jointly determined by the three light fields, and the spatial frequency magnification factors of the amplitude-modulated light field, the first transmitted light field, and the second transmitted light field are independent of each other, indicating that adjusting one or more of the three parameters, namely the amplitude modulation parameter of the amplitude modulation spatial light modulation element, the modulation region of the crystal holographic optical element, or the distance between the holographic optical element and the Fourier spectral plane, can change the light intensity distribution and phase of the interference light field to achieve dynamic control of the interference light field, so that the distribution of the interference light field matches various complex three-dimensional micro-nano structures, and various complex three-dimensional micro-nano structures can be prepared on the photosensitive material.

[0050] This application uses a variety of optical elements to continuously modulate each parameter of the incident light field to generate an interference light field with adjustable phase and light intensity, and realizes multi-parameter dynamic control of the interference light field through single-parameter or multi-parameter combination control. Thus, an interference light field matching various three-dimensional micro-nano structures can be obtained. Only by placing the photosensitive material in this interference light field for exposure can the three-dimensional micro-nano structure be prepared. Since the light field can act uniformly on the surface of the photosensitive material, the uniformity and precision of the prepared three-dimensional micro-nano structure are ensured; at the same time, this multi-link light field modulation method no longer relies on direct laser beam exposure, but directly forms a more finely distributed and accurate interference light field on the surface of the photosensitive material through precise control of the amplitude and phase of the light field, breaking through the limitation of the diffraction limit during laser beam lithography and enabling the preparation of three-dimensional micro-nano structures with small line widths. Brief Description of the Drawings

[0051] To make the content of the present invention easier to be clearly understood, the following further describes the present invention in detail according to specific embodiments of the present invention in conjunction with the accompanying drawings, where

[0052] Figure 1 is a flowchart of a polarization interference lithography method for a three-dimensional micro-nano structure provided by this application;

[0053] Figure 2 is a schematic structural diagram of a polarization interference lithography system for a three-dimensional micro-nano structure provided by this application;

[0054] Figure 3 is a schematic diagram of the imaging principle of a polarization interference lithography system for a three-dimensional micro-nano structure provided in Embodiment 1 of this application; among them, Figure 3 in (a) is a schematic diagram of the transmission distribution of a gray-scale mask on one side of the optical axis of the system, Figure 3 in (b) is a schematic diagram of the transmission distribution of the gray-scale mask at the position symmetric to the optical axis of the system, Figure 3 in (c) is a schematic diagram of the orientation of a kind of liquid crystal molecules of the liquid crystal element, Figure 3 in (d) is a schematic diagram of the orientation of another kind of liquid crystal molecules of the liquid crystal element, Figure 3 in (e) is a schematic diagram of the amplitude distribution of the light field modulated by the modulation region of the liquid crystal element, Figure 3 in (f) is a schematic diagram of the amplitude distribution of the first transmitted light field, Figure 3 in (g) is a schematic diagram of the amplitude distribution of the first transmitted light field, Figure 3 in (h) is a schematic diagram of the amplitude distribution of the interference light field;

[0055] Figure 4 is a schematic diagram of the imaging principle of a polarization interference lithography system for a three-dimensional micro-nano structure provided in Embodiment 2 of this application; among them, Figure 4 in (a) is a schematic diagram of the transmission distribution of a digital micromirror array on one side of the optical axis of the system, Figure 4 in (b) is a schematic diagram of the transmission distribution of the digital micromirror array at the position symmetric to the optical axis of the system, Figure 4 in (c) is a schematic diagram of the second transmitted light field distribution, Figure 4 in (d) is a schematic diagram of the amplitude distribution of the interference light field;

[0056] Figure 5 is a schematic diagram of optical elements with different partition arrangements provided in the embodiments of this application;

[0057] Explanation of reference numerals in the accompanying drawings of the specification: 1. Amplitude spatial light modulation element; 2. Crystal holographic optical element; 3. Fourier transform optical system; 31. First Fourier transform lens; 32. Second Fourier transform lens; 33. Fourier spectrum plane; 4. Holographic optical element; U. Imaging plane; 5. Spatial light modulator; 6. Displacement stage; 7. Host computer; 8. Charge coupled device. Detailed implementation manners

[0058] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and be able to implement it, but the specific embodiments cited are not intended to limit the present invention.

[0059] Please refer to Figure 1 , Figure 1 which shows a flowchart of a polarization interference lithography method for a three-dimensional micro-nano structure provided by the present application. The method specifically includes:

[0060] S10: Modulate the amplitude of the incident light field by using an amplitude spatial light modulation element to obtain an amplitude-modulated light field.

[0061] S20: Modulate the polarization, amplitude, and phase of the amplitude-modulated light field by using a crystal holographic optical element to obtain a first transmitted light field.

[0062] S30: Modulate the amplitude and phase of the first transmitted light field by using a holographic optical element to obtain a second transmitted light field on the Fourier spectrum plane.

[0063] S40: Perform Fourier transform on the amplitude-modulated light field, the first transmitted light field, and the second transmitted light field by using a first Fourier transform lens in the Fourier transform optical system to obtain a Fourier transform light field.

[0064] S50: Perform Fourier transform on the Fourier transform light field by using a second Fourier transform lens in the Fourier transform optical system, so as to obtain an interference light field with adjustable light intensity and phase on the imaging plane.

[0065] S60: Change the amplitude modulation parameter of the amplitude spatial light modulation element and / or the modulation area of the crystal holographic optical element and / or the distance between the holographic optical element and the Fourier spectrum plane to adjust the light intensity and phase of the interference light field, so that the distribution of the interference light field matches the preset three-dimensional micro-nano structure, thereby preparing the preset three-dimensional micro-nano structure on the surface of the photosensitive material.

[0066] Specifically, the Fourier transform light field is expressed as:

[0067] ,

[0068] wherein, represents the Fourier transform light field; represents the amplitude distribution function of the amplitude spatial light modulation element after being transformed by the first Fourier transform lens; represents the transmitted light field function of the crystal holographic optical element after being transformed by the first Fourier transform lens; represents the transmitted light field function of the holographic optical element after being transformed by the first Fourier transform lens; represents the spatial coordinates of the second transmitted light field on the Fourier spectrum plane; represents a constant factor.

[0069] ,

[0070] ,

[0071]

[0072] Among them, represents the amplitude distribution function of the amplitude spatial light modulation element before transformation; represents the spatial coordinates of the incident light field; represents the transmitted light field function of the crystal holographic optical element before transformation; represents the spatial coordinates of the amplitude-modulated light field; represents the transmitted light field function of the holographic optical element before transformation; represents the spatial coordinates of the Fourier-transformed light field; represents the laser wavelength; represents the focal length of the first Fourier transform lens; represents the distance between the holographic optical element and the Fourier spectrum plane; is the Fourier transform scale of the amplitude distribution function of the amplitude spatial light modulation element and the transmitted light field function of the crystal holographic optical element; is the Fourier transform scale of the holographic optical element.

[0073] The light field distribution function of the interference light field is expressed as:

[0074] ,

[0075] Among them, represents the light field distribution function of the interference light field; represents the spatial coordinates of the interference light field on the imaging plane of the Fourier imaging system; represents the amplitude distribution function of the amplitude spatial light modulation element after being transformed by the second Fourier transform lens; represents the transmitted light field function of the crystal holographic optical element after being transformed by the second Fourier transform lens; represents the transmitted light field function of the holographic optical element after being transformed by the first Fourier transform lens; represents a constant factor; represents the focal length of the first Fourier transform lens; represents the focal length of the second Fourier transform lens; represents the distance between the holographic optical element and the Fourier spectrum plane.

[0076] Specifically, it can be seen from the expression of the interference light field that the interference light field is the result of multiplying the amplitude-modulated light field, the transmitted light field modulated by the crystal holographic optical element, and the transmitted light field modulated by the holographic optical element after two Fourier transforms respectively. Its light intensity distribution and phase distribution are jointly determined by the three light fields. Therefore, in this application, an amplitude spatial light modulation element, a crystal holographic optical element, and a holographic optical element are sequentially used to modulate different parameters of the light field to obtain three modulated light fields, and then combined with a Fourier transform optical system composed of two Fourier transform lenses to perform Fourier transforms on the modulated light fields respectively, so as to obtain an interference light field whose phase and light intensity can both be modulated. At the same time, since the spatial frequency magnification factors of the three modulated light fields are , and respectively, and their spatial frequency magnification factors are independent of each other. Therefore, separately regulating the amplitude modulation parameter of the amplitude spatial light modulation element, the modulation area of the crystal holographic optical element, or the distance between the holographic optical element and the Fourier spectrum plane can change the light intensity distribution and phase of the interference light field, so that the distribution of the interference light field can be matched with the distribution of various complex three-dimensional micro-nano structures through single-variable regulation or multi-variable combination regulation, so as to prepare various three-dimensional micro-nano structures on the photosensitive material.

[0077] In this application, different optical elements are used to independently modulate each parameter of the incident light field multiple times to achieve multi-parameter dynamic regulation of the interference light field, so as to prepare three-dimensional micro-nano structures. By single-parameter or multi-parameter combination regulation, an interference light field that is highly uniform and matches the three-dimensional micro-nano structure is generated, so that each part of the photosensitive material is evenly illuminated during exposure, avoiding the problem of insufficient accuracy of the three-dimensional micro-nano structure caused by uneven arrangement of the nanosphere array in the nanosphere lithography technology. At the same time, this multi-link light field modulation method no longer simply relies on direct laser beam exposure, but directly forms a more fine and precise interference light field on the surface of the photosensitive material through precise regulation of the light field amplitude and phase, breaking through the limitation of the diffraction limit during laser beam lithography, and enabling the preparation of three-dimensional micro-nano structures with small line widths.

[0078] Furthermore, since the light field modulated by the crystal holographic optical element already has rich distribution characteristics, in step S40, only the spectrum of the light field needs to be adjusted in the frequency domain, and there is no need to perform complex regulation on the light field. Therefore, only a holographic optical element is needed in step S40. Compared with the crystal holographic optical element, the structure and principle of the holographic optical element are relatively simple, and it is also easier to implement the specific modulation function of the frequency-domain light field.

[0079] Further, in step S50, adjusting the light intensity and phase of the interference light field by changing the amplitude modulation parameter of the amplitude spatial light modulation element and / or the modulation region of the crystal holographic optical element and / or the distance between the holographic optical element and the Fourier spectrum plane, so that the distribution of the interference light field matches the preset three-dimensional micro-nano structure includes:

[0080] Based on the material parameters of the photosensitive material and the size parameters of the preset three-dimensional micro-nano structure, obtain the light field distribution function of the preset three-dimensional micro-nano structure.

[0081] Specifically, after obtaining the material parameters of the photosensitive material and the size parameters of the three-dimensional micro-nano structure, methods such as the finite element method, the finite difference method, or the finite difference time domain method can be used to construct a three-dimensional micro-nano structure model. By setting the wavelength, polarization direction, and incident angle of the incident light to simulate the propagation process of light in the three-dimensional micro-nano structure, the light field distribution function of the three-dimensional micro-nano structure can be obtained based on the simulation results.

[0082] Obtain the light field distribution function of the interference light field, thereby calculating the error between the light field distribution function of the three-dimensional micro-nano structure and the light field distribution function of the interference light field, and judging the magnitude of the error and the preset error threshold.

[0083] When the error is greater than or equal to the preset error threshold, change the amplitude modulation parameter of the amplitude spatial light modulation element and / or the modulation region of the crystal holographic optical element and / or the distance between the holographic optical element and the Fourier spectrum plane to adjust the light intensity and phase of the interference light field.

[0084] Re-obtain the light field distribution function of the interference light field until the error between the light field distribution function of the three-dimensional micro-nano structure and the light field distribution function of the interference light field is less than the preset error threshold. [[ID=!7]]

[0085] Specifically, if the amplitude spatial light modulation element is centered on the optical axis, and its amplitudes are respectively 、 ,when only the ±1 order diffraction lights of the crystal holographic optical element and the holographic optical element participate in the light field interference of imaging, define the ±1 order diffraction lights of the crystal holographic optical element as:

[0086] ,

[0087] ,

[0088] The ±1 order diffraction lights of the holographic optical element are respectively:

[0089] ,

[0090] ,

[0091] Then the light field distribution function of the interference light field is:

[0092] ,

[0093] If the polarization angle of the ±1 order diffracted light of the crystal holographic optical element in the spatial coordinates is , and the phase difference is , and , , then:

[0094] ,

[0095] Among them, represents the intensity distribution of the interference light field; represents the amplitude term related to the modulation parameters of the amplitude spatial light modulator; represents the coherent light field related to the modulation region of the holographic optical element; represents the polarization interference light field related to the modulation region of the crystal holographic optical element; represents the amplitude term related to the polarization direction; represents the amplitude and phase of the +1 order diffracted beam of the crystal holographic optical element that are independent of the polarization direction; represents the amplitude and phase of the -1 order diffracted beam of the crystal holographic optical element that are independent of the polarization direction.

[0096] Furthermore, when the distribution of the interference light field matches the preset three-dimensional micro-nano structure, it is only necessary to place the substrate coated with the photosensitive material in the interference light field for exposure. The photosensitive material will undergo a chemical reaction according to the light intensity distribution of the interference light field to form a latent image corresponding to the light intensity distribution. Then, the substrate is placed in the developer for development, and a preset three-dimensional micro-nano structure can be formed on the surface of the photosensitive material. Among them, the photosensitive material can be photoresist, photopolymer, etc.

[0097] Furthermore, in some embodiments of the present application, the amplitude spatial light modulator includes a liquid crystal amplitude spatial light modulator, a digital micromirror array, an optical switch, a gray scale mask, an aperture stop, etc.

[0098] Furthermore, in some embodiments of the present application, the crystal holographic optical element includes a liquid crystal holographic optical element, a birefringent crystal holographic optical element, high refractive index materials such as silicon / titanium nitride / silicon nitride, a phase-type spatial light dynamic modulator based on Lcos, etc.

[0099] Furthermore, in some embodiments of the present application, the holographic optical element includes a phase-type holographic optical element, an amplitude-type holographic optical element, a volume holographic optical element, etc.

[0100] In a specific example of the present application, when fabricating a three-dimensional micro-nano structure with a rectangular structure, the amplitude spatial light modulation element is a gray-scale mask, the crystal holographic optical element is a liquid crystal element, and the holographic optical element is a variable spatial frequency one-dimensional grating combination.

[0101] In another specific example of the present application, when fabricating a three-dimensional micro-nano structure with a pyramid shape, the amplitude spatial light modulation element is a digital micromirror array, the crystal holographic optical element is a birefringent crystal element, and the holographic optical element is a partitioned Fresnel zone plate.

[0102] Based on the polarization interference lithography method for three-dimensional micro-nano structures provided in the above embodiments, the embodiments of the present application further provide a polarization interference lithography system for three-dimensional micro-nano structures. As Figure 2 shown, the system specifically includes an amplitude spatial light modulation element 1, a crystal holographic optical element 2, a Fourier transform optical system 3, a holographic optical element 4, a spatial light modulator 5, a displacement stage 6, and a host computer 7. Among them, the Fourier transform optical system 3 includes a first Fourier transform lens 31 and a second Fourier transform lens 32, and the first Fourier transform lens 31 and the second Fourier transform lens 32 form a coaxial interference system.

[0103] The amplitude spatial light modulation element 1 is used to modulate the amplitude of the incident light field to obtain an amplitude-modulated light field.

[0104] The crystal holographic optical element 2 is used to modulate the polarization, amplitude, and phase of the amplitude-modulated light field to obtain a first transmitted light field.

[0105] The holographic optical element 4 is used to modulate the amplitude and phase of the first transmitted light field to obtain a second transmitted light field on the Fourier spectrum plane 33.

[0106] The first Fourier transform lens 31 is disposed between the crystal holographic optical element 2 and the holographic optical element 4, and is used to perform Fourier transform on the amplitude-modulated light field, the first transmitted light field, and the second transmitted light field to obtain a Fourier transform light field.

[0107] Optionally, in some embodiments, the crystal holographic optical element 2 may be disposed on the side of the first Fourier transform lens 31 close to the amplitude spatial light modulation element 1, and the holographic optical element 4 is disposed on the side of the first Fourier transform lens 31 far from the crystal holographic optical element 2; in other embodiments, the holographic optical element 4 may be disposed on the side of the first Fourier transform lens 31 close to the amplitude spatial light modulation element 1, and the crystal holographic optical element 2 is disposed on the side of the first Fourier transform lens 31 far from the holographic optical element 4; that is, at least one of the crystal holographic optical element 2 and the holographic optical element 4 is disposed between the first Fourier transform lens 31 and the second Fourier transform lens 32.

[0108] The second Fourier transform lens 32 is disposed on the side of the holographic optical element 4 away from the first Fourier transform lens 31, and is used to perform Fourier transform on the Fourier transform light field, so as to obtain an interference light field with adjustable light intensity and phase on the imaging plane.

[0109] The spatial light modulator 5 is connected to the amplitude spatial light modulation element 1 and the crystal holographic optical element 2.

[0110] The displacement stage 6 is used to place the holographic optical element 4.

[0111] The host computer 7 is connected to the spatial light modulator 5 and the displacement stage 6, and is used to control the spatial light modulator 5 to change the amplitude modulation parameter of the amplitude spatial light modulation element 1 and / or the modulation area of the crystal holographic optical element 2, and control the displacement stage 6 to move to change the distance between the holographic optical element 4 and the Fourier spectrum plane 33, so as to adjust the light intensity and phase of the interference light field, so that the distribution of the interference light field matches the preset three-dimensional micro-nano structure, thereby preparing the preset three-dimensional micro-nano structure on the surface of the photosensitive material.

[0112] Specifically, by controlling the voltage and phase of the spatial light modulator 5, the amplitude modulation parameter of the amplitude spatial light modulation element 1 and the modulation area of the crystal holographic optical element 2 can be changed.

[0113] Furthermore, the host computer 7 specifically includes a first light field distribution function acquisition module, an error calculation module and a control module.

[0114] The first light field distribution function acquisition module is used to calculate the light field distribution function of the preset three-dimensional micro-nano structure based on the material parameters of the photosensitive material and the size parameters of the preset three-dimensional micro-nano structure.

[0115] The error calculation module is used to obtain the light field distribution function of the interference light field, so as to calculate the error between the light field distribution function of the three-dimensional micro-nano structure and the light field distribution function of the interference light field, and judge the magnitude of the error and the preset error threshold.

[0116] The control module is used to control the spatial light modulator to change the amplitude modulation parameter of the amplitude spatial light modulation element 1 and / or the modulation area of the crystal holographic optical element, and control the displacement stage to move to change the distance between the holographic optical element and the Fourier spectrum plane when the error is greater than or equal to the preset error threshold, until the error is less than the preset error threshold.

[0117] Furthermore, in some embodiments of the present application, the polarization interference lithography system for the three-dimensional micro-nano structure further includes a charge coupled device 8.

[0118] The charge-coupled device 8 is disposed on the side of the second Fourier transform lens 32 away from the holographic optical element 4 and is connected to the host computer 7. It is used to capture the intensity map of the interference light field on the imaging surface U and transmit the intensity map to the host computer 7 so that the host computer 7 can obtain the light field distribution function of the interference light field based on the intensity map.

[0119] Further, in some embodiments of the present application, the polarization interference lithography system for three-dimensional micro-nano structures further includes a reduced optical path.

[0120] The reduced optical path is disposed on the side of the second Fourier transform lens 32 away from the first Fourier transform lens 31 and includes a double telecentric lens and a reduction objective lens arranged in sequence along the optical path propagation direction. It is used to fabricate a preset three-dimensional micro-nano structure on the surface of the photosensitive material.

[0121] The technical solution of the present application will be described in more detail below with reference to two specific examples. However, it should be understood that the following embodiments are only for explaining and illustrating the technical solution and do not limit the scope of the present application.

[0122] Embodiment 1 of the present application provides a polarization interference lithography system for three-dimensional micro-nano structures, as Figure 3 shown in the schematic diagram of the imaging principle of the polarization interference lithography system for three-dimensional micro-nano structures provided in this embodiment. The system specifically includes an amplitude spatial light modulator, a crystal holographic optical element, a Fourier transform optical system, a holographic optical element, a spatial light modulator, and a host computer; among them, the Fourier transform optical system includes a first Fourier transform lens and a second Fourier transform lens.

[0123] The amplitude spatial light modulator is a gray-scale mask, which is used to modulate the amplitude of the incident light field to obtain an amplitude-modulated light field. As Figure 3 shown in (a) of Figure 3 is the schematic diagram of the transmission distribution of the gray-scale mask on one side of the optical axis of the system, and

[0124] shown in (b) of Figure 3 is the schematic diagram of the transmission distribution of the gray-scale mask at the position symmetric to the optical axis of the system. Figure 3 Figure 3 The crystal holographic optical element 2 is a liquid crystal element, which is used to modulate the polarization, amplitude, and phase of the amplitude-modulated light field to obtain a first transmitted light field. When the liquid crystal element is a combination of liquid crystal gratings with different spatial frequencies, relative to the position symmetric to the optical axis, if the liquid crystal molecule orientation of the liquid crystal element is as Figure 3 shown in (c) and (d) of Figure 3 shown in (e) of Figure 3 shown in (f) of

[0125] The first Fourier transform lens is disposed on the side of the liquid crystal element away from the gray-scale mask and is used to perform Fourier transform on the amplitude-modulated light field, the first transmitted light field, and the second transmitted light field to obtain a Fourier transform light field.

[0126] The holographic optical element adopts a variable spatial frequency one-dimensional grating combination and is arranged on the side of the first Fourier transform lens away from the liquid crystal element, and is used to modulate the amplitude and phase of the first transmitted light field so as to obtain a second transmitted light field on the Fourier spectrum plane. As shown in Figure 3 (g) in it is a schematic diagram of the amplitude distribution of the second transmitted light field.

[0127] The second Fourier transform lens is arranged on the side of the variable spatial frequency one-dimensional grating combination away from the first Fourier transform lens, and is used to perform Fourier transform on the Fourier transform light field, so as to obtain an interference light field with adjustable light intensity and phase on the imaging plane.

[0128] By adjusting the light intensity and phase of the interference light field, an interference light field amplitude distribution diagram as shown in Figure 3 (h) in it can be obtained. It can be seen that compared with the cosine structure prepared by traditional interference lithography, the system provided by the present application can prepare a rectangular three-dimensional micro-nano structure.

[0129] Embodiment 2 of the present application provides a polarization interference lithography system for three-dimensional micro-nano structures. As shown in Figure 4 It is a schematic diagram of the imaging principle of the polarization interference lithography system for three-dimensional micro-nano structures provided in this embodiment. The system specifically includes an amplitude spatial light modulation element, a crystal holographic optical element, a Fourier transform optical system, a holographic optical element, a spatial light modulator and a host computer; wherein, the Fourier transform optical system includes a first Fourier transform lens and a second Fourier transform lens.

[0130] The amplitude spatial light modulation element is a digital micromirror array and is used to modulate the amplitude of the incident light field to obtain an amplitude-modulated light field. As shown in Figure 4 (a) in it is a schematic diagram of the transmission distribution of the digital micromirror array on one side of the optical axis of the system, Figure 4 (b) in it is a schematic diagram of the transmission distribution of the digital micromirror array at the position symmetrical to the optical axis of the system.

[0131] The crystal holographic optical element is a birefringent crystal element and is used to modulate the polarization, amplitude and phase of the amplitude-modulated light field to obtain a first transmitted light field.

[0132] The first Fourier transform lens is arranged on the side of the birefringent crystal element away from the digital micromirror array, and is used to perform Fourier transform on the amplitude-modulated light field, the first transmitted light field and the second transmitted light field to obtain a Fourier transform light field.

[0133] The holographic optical element adopts a partitioned Fresnel ring and is arranged on the side of the first Fourier transform lens away from the birefringent crystal element, and is used to modulate the amplitude and phase of the first transmitted light field so as to obtain a second transmitted light field on the Fourier spectrum plane. As shown in Figure 4In (c), it is a schematic diagram of the amplitude distribution of the second transmitted light field. It can be seen that the second transmitted light field is a dot matrix distributed on different depth surfaces.

[0134] The second Fourier transform lens is arranged on the side of the Fresnel ring with partitioned distribution away from the first Fourier transform lens, and is used to perform Fourier transform on the Fourier transform light field, so as to obtain an interference light field with adjustable light intensity and phase on the imaging surface.

[0135] By adjusting the light intensity and phase of the interference light field, an interference light field amplitude distribution schematic diagram as shown in (d) of Figure 4 can be obtained. It can be seen that the system provided by the present application can also prepare three-dimensional micro-nano structures with fine structures.

[0136] Specifically, when the holographic optical element is translated along the optical axis, the spatial frequency of the interference light field and the distribution region along the optical axis direction will both change accordingly.

[0137] It should be noted that when the crystal holographic optical element adopts a Fresnel ring with partitioned distribution and the holographic optical element adopts a birefringent crystal, if the holographic optical element is translated along the optical axis, the spatial frequency of the interference light field and the amplitude modulation speed of the gray-scale light field will change accordingly. Moreover, if at least one of the crystal holographic optical element and the holographic optical element is composed of different structures arranged in different partitions, as shown in Figure 5 , where the structure distributions in the same digital regions are the same, then according to the light field distribution on the imaging surface, the coherence of the diffracted light beams under different numbers in the same digital region can be realized only through the modulation parameters of the amplitude spatial light modulation element, so as to form three-dimensional micro-nano structures with various different morphologies.

[0138] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0139] This application is described with reference to the flowcharts and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present application. It should be understood that each flow and / or block in the flowchart and / or block diagram, and the combination of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing device to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing device produce means for implementing the functions specified in one or more flows and / or one or more blocks in the flowcharts and / or block diagrams. Figure 1 in one or more flows and / or one or more blocks Figure 1 of the means for implementing the functions specified in the block or blocks.

[0140] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory produce a manufactured article including instruction means for implementing the functions specified in one or more flows and / or one or more blocks Figure 1 in one or more flows and / or one or more blocks Figure 1 of the block or blocks.

[0141] These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process, so that the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one or more flows and / or one or more blocks Figure 1 in one or more flows and / or one or more blocks Figure 1 of the block or blocks.

[0142] Obviously, the above embodiments are only examples for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A polarization interference lithography method for three-dimensional micro-nano structures, characterized in that, Including: Modulating the amplitude of the incident light field by using an amplitude spatial light modulation element to obtain an amplitude-modulated light field; Modulating the polarization, amplitude, and phase of the amplitude-modulated light field by using a crystal holographic optical element to obtain a first transmitted light field; Modulating the amplitude and phase of the first transmitted light field by using a holographic optical element to obtain a second transmitted light field on the Fourier spectrum plane; Performing Fourier transform on the amplitude-modulated light field, the first transmitted light field, and the second transmitted light field by using a first Fourier transform lens in the Fourier transform optical system to obtain a Fourier transform light field; Performing Fourier transform on the Fourier transform light field by using a second Fourier transform lens in the Fourier transform optical system, so as to obtain an interference light field with adjustable light intensity and phase on the imaging plane; Changing the amplitude modulation parameter of the amplitude spatial light modulation element and / or the modulation region of the crystal holographic optical element and / or the distance between the holographic optical element and the Fourier spectrum plane to adjust the light intensity and phase of the interference light field, so that the distribution of the interference light field matches a preset three-dimensional micro-nano structure, thereby preparing the preset three-dimensional micro-nano structure on the surface of the photosensitive material; Specifically including: Based on the material parameters of the photosensitive material and the size parameters of the preset three-dimensional micro-nano structure, obtaining the light field distribution function of the preset three-dimensional micro-nano structure; Obtaining the light field distribution function of the interference light field, thereby calculating the error between the light field distribution function of the three-dimensional micro-nano structure and the light field distribution function of the interference light field, and judging the magnitude of the error and a preset error threshold; When the error is greater than or equal to the preset error threshold, changing the amplitude modulation parameter of the amplitude spatial light modulation element and / or the modulation region of the crystal holographic optical element and / or the distance between the holographic optical element and the Fourier spectrum plane to adjust the light intensity and phase of the interference light field; Re-obtaining the light field distribution function of the interference light field until the error between the light field distribution function of the three-dimensional micro-nano structure and the light field distribution function of the interference light field is less than the preset error threshold.

2. The polarization interference lithography method for three-dimensional micro-nano structures according to claim 1, characterized in that The Fourier transform light field is expressed as: ， Among them, represents the Fourier-transformed optical field; represents the amplitude distribution function of the amplitude spatial light modulator after being transformed by the first Fourier-transform lens; represents the transmitted optical field function of the crystal holographic optical element after being transformed by the first Fourier-transform lens; represents the transmitted optical field function of the holographic optical element after being transformed by the first Fourier-transform lens; represents the spatial coordinates of the second transmitted optical field on the Fourier spectrum plane; represents a constant factor.

3. The polarization interference lithography method for three-dimensional micro-nano structures according to claim 1, characterized in that The light field distribution function of the interference light field is expressed as: ， Among them, represents the optical field distribution function of the interference optical field; represents the spatial coordinates on the imaging surface of the Fourier imaging system for the interference optical field; represents the amplitude distribution function of the amplitude spatial light modulation element after being transformed by the second Fourier transform lens; represents the transmitted optical field function of the crystal holographic optical element after being transformed by the second Fourier transform lens; represents the transmitted optical field function of the holographic optical element after being transformed by the first Fourier transform lens; represents a constant factor; represents the focal length of the first Fourier transform lens; represents the focal length of the second Fourier transform lens; represents the distance between the holographic optical element and the Fourier spectrum plane.

4. The polarization interference lithography method for three-dimensional micro-nano structures according to claim 1, characterized in that The amplitude spatial light modulation element is a liquid crystal amplitude spatial light modulator, a digital micromirror array, an optical switch, a gray scale mask, or an aperture diaphragm; and / or, The crystal holographic optical element is a liquid crystal holographic optical element, a birefringent crystal holographic optical element, or a phase-type spatial light dynamic modulator based on Lcos; and / or, The holographic optical element is a phase-type holographic optical element, an amplitude-type holographic optical element, or a volume holographic optical element.

5. The polarization interference lithography method for three-dimensional micro-nano structures according to claim 1, characterized in that When preparing a three-dimensional micro-nano structure with a rectangular structure, the amplitude spatial light modulation element is a gray scale mask, the crystal holographic optical element is a liquid crystal element, and the holographic optical element is a variable spatial frequency one-dimensional grating combination; When preparing a three-dimensional micro-nano structure with a pyramid shape, the amplitude spatial light modulation element is a digital micromirror array, the crystal holographic optical element is a birefringent crystal element, and the holographic optical element is a partitioned Fresnel ring.

6. A polarization interference lithography system for three-dimensional micro-nano structures, characterized in that, Including: An amplitude spatial light modulation element for modulating the amplitude of the incident light field to obtain an amplitude-modulated light field; A crystal holographic optical element for modulating the polarization, amplitude, and phase of the amplitude-modulated light field to obtain a first transmitted light field; A holographic optical element for modulating the amplitude and phase of a first transmitted light field to obtain a second transmitted light field on a Fourier spectrum plane; A first Fourier transform lens disposed between the crystal holographic optical element and the holographic optical element for performing Fourier transform on the amplitude-modulated light field, the first transmitted light field, and the second transmitted light field to obtain a Fourier transform light field; A second Fourier transform lens disposed on a side of the holographic optical element away from the first Fourier transform lens for performing Fourier transform on the Fourier transform light field, thereby obtaining an interference light field with adjustable light intensity and phase on an imaging plane; A spatial light modulator connected to the amplitude spatial light modulation element and the crystal holographic optical element; A displacement stage for placing the holographic optical element; A host computer connected to the spatial light modulator and the displacement stage for controlling the spatial light modulator to change the amplitude modulation parameter of the amplitude spatial light modulation element and / or the modulation region of the crystal holographic optical element, and controlling the displacement stage to move to change the distance between the holographic optical element and the Fourier spectrum plane, so as to adjust the light intensity and phase of the interference light field, such that the distribution of the interference light field matches a preset three-dimensional micro-nano structure, thereby preparing the preset three-dimensional micro-nano structure on the surface of a photosensitive material; Specifically, it includes: A first light field distribution function acquisition module for acquiring the light field distribution function of the preset three-dimensional micro-nano structure based on the material parameters of the photosensitive material and the size parameters of the preset three-dimensional micro-nano structure; An error calculation module for acquiring the light field distribution function of the interference light field, thereby calculating the error between the light field distribution function of the three-dimensional micro-nano structure and the light field distribution function of the interference light field, and judging the magnitude of the error and a preset error threshold; A control module for, when the error is greater than or equal to the preset error threshold, controlling the spatial light modulator to change the amplitude modulation parameter of the amplitude spatial light modulation element and / or the modulation region of the crystal holographic optical element, and controlling the displacement stage to move to change the distance between the holographic optical element and the Fourier spectrum plane until the error is less than the preset error threshold; Wherein, the first Fourier transform lens and the second Fourier transform lens form a coaxial interference system.

7. The polarization interference lithography system for three-dimensional micro-nano structures according to claim 6, characterized in that, It further includes: A charge coupled device disposed on a side of the second Fourier transform lens away from the holographic optical element and connected to the host computer for capturing an intensity map of the interference light field and transmitting the intensity map to the host computer, so that the host computer obtains the light field distribution function of the interference light field based on the intensity map.

8. The polarization interference lithography system for three-dimensional micro-nano structures according to claim 6, characterized in that It further includes: A micro-reduced optical path disposed on a side of the second Fourier transform lens away from the first Fourier transform lens, including a double telecentric lens and a micro-reduced objective lens arranged in sequence along the light path propagation direction, for preparing the preset three-dimensional micro-nano structure on the surface of the photosensitive material.

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