Polarization interference photoetching method and system of three-dimensional micro-nano structure

Abstract

The invention belongs to the technical field of micro-nano structure processing, and relates to a polarization interference photoetching method and system of a three-dimensional micro-nano structure, and the method comprises the following steps: modulating the amplitude of an incident light field by using an amplitude spatial light modulation element to obtain an amplitude modulation light field; modulating the amplitude modulation light field by using a crystal holographic optical element to obtain a first transmission light field; modulating the first transmission light field by using a holographic optical element to obtain a second transmission light field on the Fourier spectrum plane; performing Fourier transform on the amplitude modulation light field, the first transmission light field and the second transmission light field by using a first Fourier transform lens to obtain a Fourier transform light field; performing Fourier transform on the Fourier transform light field by using a second Fourier transform lens, and obtaining an interference light field with adjustable light intensity and phase on the imaging surface; and adjusting the light intensity and phase of the interference light field to enable the distribution of the interference light field to be matched with the preset three-dimensional micro-nano structure, thereby preparing the preset three-dimensional micro-nano structure. According to the scheme, the high-precision and small-line-width three-dimensional micro-nano structure can be prepared.

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, thereby transferring the photoresist pattern to the substrate to obtain 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 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 dispersed part of the nanospheres and under-etch the photoresist in the dense part of the nanospheres, 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: 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 a 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 fabricating the preset three-dimensional micro-nano structure on the surface of a photosensitive material.

[0008] 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: 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; 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-obtain the optical field distribution function of the interference optical field until the error between the optical field distribution function of the three-dimensional micro-nano structure and the optical field distribution function of the interference optical field is less than a preset error threshold.

[0009] Preferably, the Fourier-transformed optical field is expressed as: , where, 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.

[0010] Preferably, the optical field distribution function of the interference optical field is expressed as: , where, represents the optical field distribution function of the interference optical field; represents the spatial coordinates of the interference optical field on the imaging plane of the Fourier imaging system; represents the amplitude distribution function of the amplitude spatial light modulator 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.

[0011] Preferably, 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; and / or, the crystal holographic optical element includes a liquid crystal holographic optical element, a birefringent crystal holographic optical element, a phase-type spatial light dynamic modulator based on Lcos; and / or, the holographic optical element includes a phase-type holographic optical element, an amplitude-type holographic optical element, a volume holographic optical element.

[0012] 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; 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.

[0013] The present invention also provides a polarization interference lithography system for a three-dimensional micro-nano structure, comprising: An amplitude spatial light modulation element for modulating the amplitude of an 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 the first transmitted light field to obtain a second transmitted light field on the 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 the 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 the 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; An upper computer connected to the spatial light modulator and the displacement stage for controlling the spatial light modulator to change the amplitude modulation parameters 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 the preset three-dimensional micro-nano structure, thereby preparing the preset three-dimensional micro-nano structure on the surface of the photosensitive material; Wherein, the first Fourier transform lens and the second Fourier transform lens form a coaxial interference system.

[0014] Preferably, the upper computer specifically comprises: A first light field distribution function acquisition module for calculating 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, configured to control a spatial light modulator to change the amplitude modulation parameter of an amplitude spatial light modulation element and / or the modulation region of a crystal holographic optical element, and control a 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 a preset error threshold until the error is less than the preset error threshold.

[0015] Preferably, it further includes: A charge coupled device, arranged on the side of the second Fourier transform lens away from the holographic optical element and connected to a host computer, for photographing an intensity map of an interference light field and transmitting the 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 intensity map.

[0016] Preferably, it further includes: A microscale optical path, arranged on the side of the second Fourier transform lens away from the first Fourier transform lens, including a double telecentric lens and a microscale objective lens arranged in sequence along the optical path propagation direction, for preparing a preset three-dimensional micro-nano structure on the surface of a photosensitive material.

[0017] The polarization interference lithography method for a three-dimensional micro-nano structure provided by this application has the following beneficial effects: In this application, the amplitude of an incident light field is first modulated by an amplitude modulation spatial light modulation element 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, the 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 to finely adjust the amplitude and phase of the light field 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, the second Fourier transform lens performs 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 the multiplication of 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 spectrum plane, can change the light intensity distribution and phase of the interference light field to achieve the dynamic regulation 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.

[0018] 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 the multi-parameter dynamic regulation of the interference light field through single-parameter or multi-parameter combination regulation. 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 regulation 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. Description of the Drawings

[0019] To make the content of the present invention easier to be clearly understood, the following further details the present invention according to specific embodiments of the present invention and in combination with the accompanying drawings, where Figure 1 is a flowchart of a polarization interference lithography method for a three-dimensional micro-nano structure provided by this application; Figure 2 is a schematic structural diagram of a polarization interference lithography system for a three-dimensional micro-nano structure provided by this application; 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; where 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 symmetrical 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 a 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 light field amplitude distribution after modulation in the modulation region of the liquid crystal element, Figure 3 in (f) is a schematic diagram of the first transmitted light field amplitude distribution, Figure 3 in (g) is a schematic diagram of the first transmitted light field amplitude distribution, Figure 3 in (h) is a schematic diagram of the interference light field amplitude distribution; 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; where 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 symmetrical 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 interference light field amplitude distribution; Figure 5 is a schematic diagram of optical elements with different partition arrangements provided in the embodiments of this application; Explanation of reference numerals in the drawings of the specification: 1. Amplitude spatial light modulator; 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

[0020] 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 embodiments cited are not intended to limit the present invention.

[0021] Please refer to Figure 1 , Figure 1 which shows a flowchart of a polarization interference lithography method for three-dimensional micro-nano structures provided by the present application. The method specifically includes: S10: Modulate the amplitude of the incident light field by using an amplitude spatial light modulation element to obtain an amplitude-modulated light field.

[0022] 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.

[0023] 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.

[0024] S40: Perform 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 the Fourier transform optical system to obtain a Fourier transform light field.

[0025] S50: Perform 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.

[0026] 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.

[0027] Specifically, the Fourier transform light field is expressed as: , 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.

[0028] , ,

[0029] 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.

[0030] The light field distribution function of the interference light field is expressed as: , 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.

[0031] 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 used in sequence to modulate different parameters of the light field, obtaining 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; meanwhile, 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 adjusting the amplitude modulation parameter of the amplitude spatial light modulation element, the modulation region 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, in order to fabricate various three-dimensional micro-nano structures on the photosensitive material.

[0032] 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, thereby fabricating three-dimensional micro-nano structures. By regulating with a single parameter or a combination of multiple parameters, an interference light field that is highly uniform and matches the three-dimensional micro-nano structure is generated, making the photosensitive material receive light evenly 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 finely and precisely distributed interference light field on the surface of the photosensitive material through precise regulation of the amplitude and phase of the light field, breaking through the limitation of the diffraction limit during laser beam lithography and enabling the fabrication of three-dimensional micro-nano structures with small line widths.

[0033] 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, without complex regulation of 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 achieve the specific modulation function of the frequency-domain light field.

[0034] 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: Obtaining 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.

[0035] 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.

[0036] 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 of the error and the preset error threshold.

[0037] 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.

[0038] 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.

[0039] Specifically, if the amplitude spatial light modulation element is centered on the optical axis and its amplitudes are respectively 、 , when only the ±1st order diffracted lights of the crystal holographic optical element and the holographic optical element participate in the light field interference of imaging, the ±1st order diffracted lights of the crystal holographic optical element are respectively defined as: , , The ±1st order diffracted lights of the holographic optical element are respectively: , , Then the light field distribution function of the interference light field is: , If the polarization angle between the ±1st order diffracted lights of the crystal holographic optical element in the spatial coordinates is , the phase difference is , and , , then: , wherein, represents the intensity distribution of the interference light field; represents the amplitude term related to the modulation parameter 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 +1st order diffracted beam of the crystal holographic optical element that is independent of the polarization direction; represents the amplitude and phase of the -1st order diffracted beam of the crystal holographic optical element that is independent of the polarization direction.

[0040] 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 the 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.

[0041] 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 mask, an aperture stop, etc.

[0042] 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.

[0043] 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.

[0044] In a specific example of the present application, when preparing a three-dimensional micro-nano structure with a rectangular structure, the amplitude spatial light modulator is a gray 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.

[0045] In another specific example of the present application, when preparing a three-dimensional micro-nano structure with a pyramid shape, the amplitude spatial light modulator 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.

[0046] Based on the method for polarization interference lithography of 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 modulator 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.

[0047] The amplitude spatial light modulator 1 is used to modulate the amplitude of the incident light field to obtain an amplitude-modulated light field.

[0048] 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.

[0049] 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.

[0050] The first Fourier transform lens 31 is arranged 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.

[0051] Optionally, in some embodiments, the crystal holographic optical element 2 may be arranged on the side of the first Fourier transform lens 31 close to the amplitude spatial light modulator 1, and the holographic optical element 4 is arranged 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 arranged on the side of the first Fourier transform lens 31 close to the amplitude spatial light modulator 1, and the crystal holographic optical element 2 is arranged 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 arranged between the first Fourier transform lens 31 and the second Fourier transform lens 32.

[0052] The second Fourier transform lens 32 is arranged on the side of the holographic optical element 4 far 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.

[0053] The spatial light modulator 5 is connected to the amplitude spatial light modulator 1 and the crystal holographic optical element 2.

[0054] The displacement stage 6 is used to place the holographic optical element 4.

[0055] 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 region 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.

[0056] 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 region of the crystal holographic optical element 2 can be changed.

[0057] Furthermore, the host computer 7 specifically includes a first light field distribution function acquisition module, an error calculation module, and a control module.

[0058] 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.

[0059] The error calculation module is used to 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 size of the error and the preset error threshold.

[0060] 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 region 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.

[0061] 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.

[0062] The charge coupled device 8 is arranged 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, and is used to photograph the light intensity map of the interference light field on the imaging surface U and transmit the light 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 light intensity map.

[0063] Furthermore, in some embodiments of the present application, the polarization interference lithography system for the three-dimensional micro-nano structure further includes a reduced optical path.

[0064] The reduced optical path is arranged 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, and is used to prepare the preset three-dimensional micro-nano structure on the surface of the photosensitive material.

[0065] The technical solution of the present application is described in more detail below with reference to two specific examples. However, it should be understood that the following embodiments are only intended to explain and illustrate the technical solution and do not limit the scope of the present application.

[0066] Embodiment 1 of the present application provides a polarization interference lithography system for three-dimensional micro-nano structures, such as Figure 3 The figure shows the imaging principle schematic diagram of the polarization interference lithography system of the three-dimensional micro-nano structure 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.

[0067] The amplitude spatial light modulation element is a grayscale mask, which is used to modulate the amplitude of the incident light field to obtain an amplitude modulated light field, such as Figure 3 (a) is a schematic diagram of the transmission distribution of the grayscale mask on one side of the system optical axis. Figure 3 (b) is a schematic diagram of the transmission distribution of the grayscale mask at a symmetrical position along the system optical axis.

[0068] 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 the first transmitted light field. When the liquid crystal element is a combination of liquid crystal gratings with different spatial frequencies, relative to the symmetrical position of the optical axis, if the liquid crystal molecules of the liquid crystal element are oriented as follows Figure 3 When (c) and (d) are shown in FIG. 1 , the amplitude distribution of the light field after the modulation area of ​​the liquid crystal element is modulated is as follows: Figure 3 As shown in (e) in the figure, the amplitude distribution of the first transmitted light field is as follows: Figure 3 As shown in (f) in .

[0069] The first Fourier transform lens is arranged on the side of the liquid crystal element away from the grayscale 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 transformed light field.

[0070] The holographic optical element adopts a variable space-frequency one-dimensional grating combination, which 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 to obtain a second transmitted light field on the Fourier spectrum plane, such as Figure 3 (g) is a schematic diagram of the amplitude distribution of the second transmitted light field.

[0071] The second Fourier transform lens is arranged on the side of the variable space-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, thereby obtaining an interference light field with adjustable light intensity and phase on the imaging plane.

[0072] By adjusting the intensity and phase of the interference light field, we can obtainFigure 3 As can be seen from the schematic diagram of the interference light field amplitude distribution shown in (h) in

[0073] Embodiment 2 of the present application provides a polarization interference lithography system for three-dimensional micro-nano structures, as Figure 4 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; wherein, the Fourier transform optical system includes a first Fourier transform lens and a second Fourier transform lens.

[0074] The amplitude spatial light modulator is a digital micromirror array, which is used to modulate the amplitude of the incident light field to obtain an amplitude-modulated light field. As Figure 4 shown in (a) in Figure 4 is the schematic diagram of the transmission distribution of the digital micromirror array on one side of the optical axis of the system,

[0075] The crystal holographic optical element is a birefringent 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.

[0076] 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.

[0077] The holographic optical element adopts a Fresnel ring with a partitioned distribution, 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 to obtain a second transmitted light field on the Fourier spectrum plane. As Figure 4 shown in (c) in

[0078] is the 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.

[0079] By adjusting the light intensity and phase of the interference light field, an interference light field amplitude distribution schematic diagram as shown in (d) in Figure 4 is obtained. As can be seen, the system provided by the present application can also fabricate three-dimensional micro-nano structures with fine structures.

[0080] Specifically, when the holographic optical element is translated along the optical axis, both the spatial frequency of the interference light field and the distribution region along the optical axis direction will change accordingly.

[0081] It should be noted that when the crystal holographic optical element adopts a partitioned Fresnel ring and the holographic optical element uses 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 Figure 5 shown, where the structural distributions in the same digital regions are the same, then according to the light field distribution on the imaging plane, the coherent diffraction beams under different numbers in the same digital regions can be achieved only through the modulation parameters of the amplitude spatial light modulation element, thereby forming three-dimensional micro-nano structures with various different morphologies.

[0082] Those skilled in the art should understand that the embodiments of the present application can be provided as methods, systems, or computer program products. 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.

[0083] The present application is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each flow and / or block in the flowchart and / or block diagram, as well as 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, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing devices generate a device for realizing the functions specified in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0084] 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 generate a manufactured article including an instruction device that realizes the functions specified in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0085] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus, so that a series of operation steps are executed on the computer or other programmable apparatus to produce a computer-implemented process, thereby providing instructions for implementing the process Figure 1 in one process or a plurality of processes and / or boxes Figure 1 steps for the functions specified in one box or a plurality of boxes.

[0086] 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 enumerate all the 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.

2. The polarization interference lithography method for three-dimensional micro-nano structures according to claim 1, characterized in that, 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: 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.

3. 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 transform optical 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.

4. 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 plane 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.

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

6. 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 grayscale 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.

7. A polarization interference lithography system for three-dimensional micro-nano structures, characterized in that, Including: 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 polarization, amplitude, and phase of the amplitude-modulated light field to obtain a first transmitted light field; A holographic optical element 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; A first Fourier transform lens is arranged between the crystal holographic optical element and the holographic optical element 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-transformed light field; A second Fourier transform lens is arranged on the side of the holographic optical element away from the first Fourier transform lens and is used to perform Fourier transform on the Fourier-transformed light field, so as to obtain an interference light field with adjustable light intensity and phase on the imaging plane; A spatial light modulator is connected to the amplitude spatial light modulation element and the crystal holographic optical element; A displacement stage is used to place the holographic optical element; A host computer is connected to the spatial light modulator and the displacement stage and 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, so that the distribution of the interference light field matches the preset three-dimensional micro-nano structure, and thus a preset three-dimensional micro-nano structure is prepared on the surface of the photosensitive material; Among them, the first Fourier transform lens and the second Fourier transform lens form a coaxial interference system.

8. The polarization interference lithography system for three-dimensional micro-nano structures according to claim 7, characterized in that, Specifically, the host computer includes: A first light field distribution function acquisition module is used to acquire 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 is used to acquire 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 size of the error and the preset error threshold; A control module is used to, when the error is greater than or equal to the preset error threshold, 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.

9. The polarization interference lithography system for three-dimensional micro-nano structures according to claim 7, characterized in that, It further includes: A 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 capture 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.

10. The polarization interference lithography system for three-dimensional micro-nano structures according to claim 7, characterized in that, It further includes: A 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 a preset three-dimensional micro-nano structure on the surface of the photosensitive material.

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