N+1 beam laser interferometric lithography system

Abstract

The application provides an N+1 laser interference lithography system, comprising: a light source module, which controls the exposure dose of a laser beam emitted by a laser by using an electrically controlled clock valve device, and controls the laser beam to be incident to a rotating light splitting module at 45°; the rotating light splitting module splits the amplitude of the laser beam to obtain N+1 coherent beams with similar energy, and modulates the spatial position of N edge coherent beams; a beam arm, which is used for controlling a 1 center coherent beam to be directly incident to a sample table capable of rotating by 360° and moving in three dimensions, and respectively controlling N edge coherent beams to be incident to the sample table from the same side or different sides at a specified incident angle with the 1 center coherent beam; and the sample table, which is placed with a substrate material, and a double-sided periodic or three-dimensional periodic micro-nano structure is prepared by converging the N+1 coherent beams. The system can flexibly control the light splitting ratio, the beam polarization state, the interference angle and the number of participating beams to obtain periodic structures with more parameters and pattern changes.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of three-dimensional micro-nano processing, and particularly relates to an N+1 beam laser interference lithography system. BACKGROUND

[0002] Three-dimensional micro-nano structures have unlimited prospects in various fields at present, including medical devices, energy batteries, biological detection, photodetectors, sensors, and the like. At present, the preparation methods of three-dimensional micro-nano structures include two-photon polymerization lithography technology, electron beam lithography technology, and projection 3D printing. On the one hand, these methods have high processing difficulty, complex operation, high equipment cost, and low processing efficiency. On the other hand, these methods also have problems such as low manufacturing precision.

[0003] Laser interference lithography technology can form a periodic light field distribution through multi-beam coherent light interference, and can prepare large-area and high-resolution three-dimensional micro-nano structures through single exposure. Compared with traditional lithography technology, laser interference lithography technology has obvious competitiveness in processing efficiency and cost control. Unlike two-beam interference which can only realize one-dimensional periodic structure, multi-beam interference can construct two-dimensional light intensity distribution through vector superposition. At present, one-dimensional structure preparation based on two-beam interference and two-dimensional structure processing technology based on four-beam interference have become mature. Dr. Zhang Ziang of Changchun University of Science and Technology and others have established a multi-beam interference system and conducted in-depth research on the mechanism of four-beam laser interference for preparing two-dimensional periodic structures and multi-periodic structures. However, this interference technology cannot realize the preparation of three-dimensional structures. To realize the preparation of three-dimensional structures by using interference light field, coherent light at a special spatial position is needed, i.e., a central beam. Due to the limitation of spatial distribution of coherent light beams, the preparation of three-dimensional structures at present mainly relies on the interference control method of spatial light modulators (SLMs). For example, Saraswati Behera and others proposed a method of generating six phase-modulated plane beams by using a phase-type SLM to realize interference, thereby realizing sub-micron axial and lateral period spiral photonic structures and woodpile-shaped photonic crystal structures. Saurabh Pandey and others designed a racemic spiral metamaterial through a double-exposure phase control SLM method. However, this kind of wavefront separation interference method using SLM for light separation and interference can only control the phase of the light beam, and cannot control the polarization state and spatial angle of the coherent light beam. The formed interference light field pattern is limited, and the control is difficult. In addition, this kind of method highly depends on SLM, has high equipment cost and high operation difficulty, and at present, there is no SLM for less than 400 nm wavelength ultraviolet light, which limits the limit size of the structure prepared by the interference light field. In addition, the working threshold of the SLM device is relatively low, and it is not suitable for high-power laser systems.

[0004] David Lowell et al. studied a reflective optical device, a circularly polarized light beam was irradiated to the device, the device reflected part of the light at a certain angle, thereby generating multiple side beams with s polarization. These side beams interfere with the central beam to prepare a three-dimensional photonic crystal or quasi-crystal template with four-fold, five-fold or six-fold rotational symmetry. Although this method is flexible and reduces the number of optical devices, it inevitably raises a fundamental problem, i.e. the system has low degrees of freedom, limiting the incident angle of the coherent light beam, the spatial angle, and the control of the polarization state of a single coherent light beam, which limits the patterned structure that can be formed and is also difficult to control the period parameter of the structure. In addition, this method is only suitable for the visible light range, and it is difficult to obtain higher precision structures. In addition, this method ignores a key problem, i.e. the low light field contrast obtained by this method leads to low efficiency of structure preparation. SUMMARY

[0005] Therefore, the purpose of the present application is to provide an N+1 beam laser interference lithography system, which uses a split-amplitude interference method to establish a three-dimensional lithography system to realize advanced manufacturing of double-sided structures and three-dimensional structures, and significantly improve the flexibility and efficiency of three-dimensional micro-nano structure preparation. By flexibly setting the spatial angle, incident angle, polarization direction and spot diameter of the coherent light beam, a large-area three-dimensional spatial light field is formed, and the preparation of large-area high-precision double-sided and three-dimensional periodic micro-nano structures is realized at one time, which has the advantages of compact optical structure, low cost and high flexibility.

[0006] The present application provides an N+1 beam laser interference lithography system, comprising:

[0007] A light source module 1 controls the exposure dose of the laser beam emitted by the laser using an electrically controlled clock valve device, and controls the laser beam to be incident to a rotating light splitting module 2 at 45° using a mirror group;

[0008] The rotating light splitting module 2 is used to split the laser beam by amplitude splitting to obtain N+1 coherent light beams with similar energy, and to modulate the spatial positions of N edge coherent light beams respectively;

[0009] A first beam arm 3 is arranged on the main optical axis and is used to control 1 central coherent light beam located on the main optical axis to be directly incident to a sample stage 5 capable of 360° rotation and three-dimensional movement;

[0010] A second beam arm 4 is arranged on the transmission path of each edge coherent light beam and is used to control N edge coherent light beams to be incident to the sample stage 5 from the same side or different sides with a specified incident angle and 1 central coherent light beam;

[0011] The sample table 5, which is placed with the substrate material of the spin-coated photosensitive material, forms a three-dimensional interference light field on the substrate material by converging N+1 coherent light beams incident from the same side or different sides, thereby preparing a double-sided periodic or three-dimensional periodic micro-nano structure.

[0012] Further, the rotating beam splitting module 2 comprises N cubic cage mirror frames 21, N beam splitters, N 1 / 2 wave plates and N-1 rotating assemblies 22.

[0013] The cubic cage mirror frame 21 is a cubic structure with a hollow mounting cavity, used for embedding the beam splitter and the 1 / 2 wave plate, and the 1 / 2 wave plate is placed behind the beam splitter for adjusting the phase delay of each coherent light beam.

[0014] The thickness of the N beam splitters is not more than 1 mm, and the beam splitting ratios are N:1, (N-1):1, (N-2):1, (N-3):1 in turn, and N is at least 2.

[0015] The inner wall of each cubic cage mirror frame 21 is provided with a positioning structure for accurately limiting the installation angle of the beam splitter to 45°; wherein the installation angle refers to the included angle between the beam splitting interface and the laser incidence direction.

[0016] Further, the rotating assembly 22 is used to connect two adjacent cubic cage mirror frames 21, and through the rotating scale and fixed screws, the edge coherent light beam is rotated around the main optical axis by 360°, thereby controlling the spatial position of the edge coherent light beam.

[0017] Further, the first beam arm 3 comprises:

[0018] The first energy control unit 32 uses the 1 / 2 wave plate and the polarizer to jointly control the energy and linear polarization direction of the center coherent light beam.

[0019] The first beam collimation unit 33 uses two lenses and a small hole to expand, filter and collimate the center coherent light beam to control the spot diameter, thereby converting the Gaussian light into flat-top light.

[0020] Further, when N edge coherent light beams and 1 center coherent light beam are incident from the same side to the sample table 5, the second beam arm 4 comprises:

[0021] The first direction control unit 41 uses a 2D control right-angle mirror frame installed with a mirror to control the transmission path of the edge coherent light beam parallel to the center coherent light beam, and uses a diaphragm to control the flux of the edge coherent light beam and determine whether it participates in exposure.

[0022] The second energy control unit 42 uses a 1 / 2 wave plate and a polarizer to jointly control the energy and linear polarization direction of the edge coherent light beam;

[0023] The second beam collimation unit 43 uses two lenses and a pinhole to expand, filter and collimate the edge coherent light beam while controlling the spot diameter size;

[0024] The second direction control unit 44 uses an electrically driven rotatable mirror and a high reflector to jointly control the edge coherent light beam to be incident on the sample stage 5 at a specified incident angle.

[0025] Further, when N edge coherent light beams and 1 central coherent light beam are incident on the sample stage 5 from different sides, the second beam arm 4 comprises:

[0026] The second energy control unit 42 uses a diaphragm to determine whether the edge coherent light beam participates in exposure, and uses a 1 / 2 wave plate and a polarizer to jointly control the energy and linear polarization direction of the edge coherent light beam;

[0027] The second beam collimation unit 43 uses two lenses and a pinhole to expand, filter and collimate the edge coherent light beam while controlling the spot diameter size;

[0028] The second direction control unit 44 uses an electrically driven rotatable mirror and a high reflector to jointly control the edge coherent light beam to be incident on the sample stage 5 at a specified incident angle.

[0029] Further, the second direction control unit 44 and the second beam collimation unit 43 are connected by a telescopic support rod, and the telescopic length is not less than l· cot θ The specified incident angle is obtained by driving the mirror of the second direction control unit 44 to rotate; wherein, l is the horizontal distance between the edge coherent light beam and the central coherent light beam.

[0030] Further, when N edge coherent light beams and 1 central coherent light beam are incident on the sample stage 5 from different sides, the sample stage 5 is set to a center hollow structure, and the substrate material is set to be light-transmitting.

[0031] Further, when N edge coherent light beams and 1 central coherent light beam are incident on the sample stage 5 from the same side, the sample stage 5 is set to a center hollow or solid planar structure, and the substrate material is set to be any planar material.

[0032] Further, the spin-coating thickness of the photosensitive material covers 0.5-1 times the period of the Z-axis of the three-dimensional interference light field, so as to prepare a double-sided period micro-nano three-dimensional structure;

[0033] Alternatively, the spin coating thickness of the photosensitive material is set to cover more than 1 period of the Z-axis of the three-dimensional interference light field to prepare a three-dimensional periodic micro-nano structure.

[0034] The N+1 beam laser interference lithography system provided by the present application can manufacture three-dimensional periodic micro-nano structures with high precision. The high degree of freedom of the system can flexibly control the splitting ratio, the polarization state of the light beam, the interference angle, and the number of light beams involved in the interference in real time, and further quickly and low-costly obtain more parameters and more pattern changes of the periodic structure, thereby providing an ideal solution with lower cost, higher flexibility, and stronger scalability for preparing complex and variable three-dimensional periodic micro-nano structures. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 An example structural diagram of a 4+1 beam laser interference lithography system with different side incidence provided by an embodiment of the present application is shown;

[0036] Figure 2 An optical path schematic diagram of a 4+1 beam laser interference lithography system with different side incidence provided by an embodiment of the present application is shown;

[0037] Figure 3 An example structural diagram of a 4+1 beam laser interference lithography system with same side incidence provided by an embodiment of the present application is shown;

[0038] Figure 4 An optical path schematic diagram of a 4+1 beam laser interference lithography system with same side incidence provided by an embodiment of the present application is shown;

[0039] Figure 5 An example structural diagram of a rotating splitting module in a 4+1 beam laser interference lithography system provided by an embodiment of the present application is shown;

[0040] Figure 6 An example structural diagram of a beam arm of an edge coherent light beam provided by an embodiment of the present application is shown;

[0041] Figure 7 A spatial angle control schematic diagram of a 4+1 beam laser interference lithography system with same side incidence provided by an embodiment of the present application is shown;

[0042] Figure 8 An example structural diagram of a 4+1 beam laser interference lithography system with different side incidence provided by an embodiment of the present application is shown;

[0043] Figure 9 An example structural diagram of a 4+1 beam laser interference lithography system with different side incidence provided by an embodiment of the present application is shown;

[0044] Figure 10An experimental result diagram of the double-sided periodic micro-nano three-dimensional structure prepared by the 3+1 beam laser interference system with same side incidence is shown.

[0045] Figure 11 A cross-sectional SEM diagram of the double-sided periodic micro-nano three-dimensional structure prepared by the 3+1 beam laser interference system with same side incidence is shown. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical scheme and advantages of the present technical solution clearer and more comprehensible, the present technical solution will be further described in detail below in combination with specific embodiments. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present technical solution.

[0047] Embodiment one

[0048] Please refer to the structural example diagram and optical path schematic diagram of the 4+1 beam laser interference lithography system with different side incidence as shown in Figure 1 and 2 The structural example diagram and optical path schematic diagram of the 4+1 beam laser interference lithography system with same side incidence as shown in Figure 3 and 4 The system comprises:

[0049] The light source module 1 controls the exposure dose of the laser beam emitted by the laser by using an electrically controlled clock valve device, and controls the laser beam to be incident to the rotating light splitting module 2 at 45° by using a mirror group.

[0050] The rotating light splitting module 2 is used to split the laser beam by amplitude, to obtain N+1 coherent beams with similar energy, and to modulate the spatial positions of the N edge coherent beams respectively.

[0051] The first beam arm 3 is arranged on the main optical axis and is used to control the 1 central coherent beam located on the main optical axis to be directly incident to the sample stage 5 which can rotate 360° and move three-dimensionally.

[0052] The second beam arm 4 is arranged on the transmission path of each edge coherent beam and is used to control the N edge coherent beams to be incident to the sample stage 5 from the same side or different sides with the 1 central coherent beam at a specified incident angle respectively.

[0053] The sample stage 5 is placed with a substrate material on which a certain thickness of photosensitive material is spin-coated, and a three-dimensional interference light field is formed on the substrate material by converging the N+1 coherent beams incident from the same side or different sides, so as to prepare a double-sided periodic or three-dimensional periodic micro-nano three-dimensional structure.

[0054] Based on the N+1 beam laser interference lithography system with the above structure, a three-dimensional light field is formed by the following way: a laser beam is emitted by a laser, after the exposure dose is regulated by an electrically controlled clock valve device, the laser beam is controlled by a mirror group to be incident to a rotating light splitting module 2 at 45°, wherein a single-wavelength or multi-wavelength laser can be used, and pulse or continuous output can be selected, and the present application does not make any limitation here, in addition, in order to meet different preparation requirements, the output power of the laser can be freely regulated. The rotating light splitting module 2 divides the laser beam into N edge coherent beams and 1 center coherent beam, and modulates the spatial position of each edge coherent beam. The center coherent beam is incident to a sample stage 5 after being expanded, filtered and collimated by a first beam arm 3, and each edge coherent beam is incident to the sample stage 5 from different spatial positions at a specified incident angle after being expanded, filtered and collimated by a second beam arm 4, here, by controlling the incident angle, phase difference and polarization state of each edge coherent beam, high-resolution three-dimensional structure information is obtained to ensure the formation of an interference light field.

[0055] The substrate material is installed on the sample stage 5 which can rotate 360° and move precisely in X, Y and Z directions to realize micro-nano structure preparation and large-area splicing. The sample stage 5 is placed in the interference light field, and high-precision double-sided periodic micro-nano structures or three-dimensional periodic micro-nano structures can be obtained at one time through exposure, development and other steps.

[0056] Next, please refer to the structure example diagram of the rotating light splitting module in the 4+1 beam laser interference lithography system as shown in Figure 5

[0057] The rotating light splitting module 2 comprises N cubic cage mirror frames 21, N light splitting mirrors, N 1 / 2 wave plates and N-1 rotating components 22.

[0058] The cubic cage mirror frame 21 is a cubic structure with a hollow mounting cavity, used for embedding the light splitting mirror and the 1 / 2 wave plate, and the 1 / 2 wave plate is placed behind the light splitting mirror for adjusting the phase delay of each coherent beam. The thickness of the N light splitting mirrors is not more than 1 mm, and the splitting ratios are N:1, (N-1):1, (N-2):1, (N-3):1 in turn, and N is at least 2. The inner wall of each cubic cage mirror frame 21 is provided with a positioning structure for accurately limiting the installation angle of the light splitting mirror to 45°. Wherein, the installation angle refers to the included angle between the light splitting interface and the laser incident direction.

[0059] The rotating component 22 is used for connecting two adjacent cubic cage mirror frames 21, and by setting the rotating scale and the fixing screw, the edge coherent beam is rotated 360° around the main optical axis, so as to control the spatial position of the edge coherent beam. ​

[0060] Specifically, the configuration and function of the beam splitter group are as follows: four beam splitters are arranged in sequence along the transmission direction of the laser beam incidence, and the internal integrated beam splitting interface is used for laser transmission and reflection; the transmission and reflection ratio is specifically designed as follows: the ratio of the transmittance and reflectance of the four beam splitters is 4:1, 3:1, 2:1, and 1:1 in sequence. Through the gradient distribution of the transmission and reflection ratio, the incident laser is gradually split into multiple branch lasers when passing through each beam splitter in sequence, and the power can be uniformly distributed.

[0061] The installation angle control of the beam splitter group: each beam splitter is installed in the special installation cavity inside the corresponding cubic cage mirror frame 21 at an inclination angle of 45° between the beam splitting interface and the laser incidence direction. The spatial angle and size of the installation cavity are accurately matched with the installation requirements of the beam splitter shape to ensure that the laser can strictly complete the beam splitting according to the preset transmission and reflection ratio when it is incident on the beam splitting interface.

[0062] The configuration and connection relationship of the cubic cage mirror frame group: it contains four cubic cage mirror frames 21, each of which is a hollow installation cavity cubic structure, and the size of the installation cavity is accurately matched with the outer dimension of the beam splitter to realize the stable embedding of the beam splitter; and the inner wall of the installation cavity is provided with a positioning structure (such as a positioning groove, a positioning boss, etc.) for accurately limiting the 45° installation inclination angle of the beam splitter, so as to ensure the consistency of the beam splitting angle. Four 1 / 2 wave plates capable of manual rotation are placed at the nearest position after beam splitting, which are used to adjust the phase delay and reduce the change of optical path difference caused by device thickness, error, etc.

[0063] The configuration and connection method of the rotating assembly: the adjacent two cubic cage mirror frames 21 are connected through the rotating assembly 22. The rotating assembly 22 specifically includes: a rotating fitting part and a connection fixing part; the rotating fitting part adopts a bearing type rotating structure to enable the adjacent cubic cage mirror frames 21 to rotate relative to each other by 360° around the rotating axis, and to determine the specified spatial position of the edge coherent light beam; the connection fixing part is fixed with the end of the adjacent cubic cage mirror frame 21 through a stable connection method such as threaded connection or buckle connection, to ensure the connection reliability of the rotating assembly 22 and the cubic cage mirror frame 21.

[0064] By operating the rotating assembly 22, the corresponding cubic cage mirror frame 21 can be driven to rotate within a range of 360°; since the beam splitter is fixed in the installation cavity of the cubic cage mirror frame 21, its spatial angle will change synchronously with the rotation of the cubic cage mirror frame 21, and the 1 / 2 wave plate is placed at the nearest position after the beam splitting, so that the spatial propagation angle of the reflected light beam obtained by the beam splitting of the beam splitter can be freely adjusted, and the 1 / 2 wave plate plays a role in adjusting the delay phase, to meet the diversified demand for the spatial pointing of the beam after beam splitting in different application scenarios.

[0065] In summary, the N+1 beam laser interference lithography system can be compatible with multi-beam laser interference lithography by rotating the light splitting module 2. In this embodiment, N is 4. In addition, the rotating assembly 22 can realize 360° rotation of the edge coherent light beam around the main optical axis by the built-in one-way electric control driver (with both electric control and manual control), that is, the angle control range of the spatial position is 0-360°, and in this embodiment, the angles of the spatial positions of the edge coherent light beams are 0°, 90°, 180° and 270°, respectively.

[0066] The first beam arm 3 of the center light beam comprises: a first energy control unit 32 for controlling the energy and linear polarization direction of the center coherent light beam by using a 1 / 2 wave plate and a polarizer; and a first beam collimation unit 33 for expanding, filtering and collimating the center coherent light beam by using two lenses and a small hole to control the spot diameter, thereby converting the Gaussian light into flat-top light.

[0067] Specifically, the energy control unit 32 is used to continuously and adjustably control the output power and linear polarization direction of the light beam. By combining the 1 / 2 wave plate and the polarizer, the linearly polarized light is converted into circularly polarized light, realizing full freedom control of the polarization state. In the first beam arm 3 of the center light beam, the 1 / 2 wave plate in the energy control unit 32 can be replaced by a 1 / 4 wave plate, and the polarizer can be removed, so that the center coherent light beam is circularly polarized light, so as to obtain more interference patterns.

[0068] In addition, the beam collimation unit 33 is used to perform expansion and filtering operations on the laser spot, so as to achieve the conversion of the laser spot from Gaussian light to flat-top light, thereby improving the quality of the structure prepared by lithography. The unit is composed of a pair of optical lenses and a small hole: the pair of optical lenses are arranged opposite to each other along the laser transmission direction, the optical axes of the two lenses are strictly collinear, and their optical parameters such as focal length and aperture are carefully designed and matched, which can meet the requirements of expanding and collimating the laser spot; the small hole is a through-hole structure opened on a flat optical element carrier, the carrier is arranged on the optical path between the two opposite lenses, the center of the small hole is accurately collinear with the optical axes of the two lenses, thereby realizing the filtering function of the laser.

[0069] In the working process, the laser spot first enters the lens located upstream of the optical path, and under the optical action of the lens, the laser spot is expanded; the expanded laser spot is transmitted to the small hole at the middle position, the small hole filters the laser spot to effectively filter out the interference components such as stray light; then, the filtered laser spot is incident on the other lens located upstream of the optical path, and under the collimation action of the lens, the propagation direction of the laser spot is regularized, finally the laser spot is expanded, which provides a strong guarantee for the subsequent lithography process to prepare high-quality structures.

[0070] Next, please refer to the edge coherent light beam arm structure example diagram as shown in Figure 6 , wherein, Figure 6 (a) is the edge coherent light beam arm structure example diagram in N+1 beam laser interference lithography system with same side incidence, Figure 6 (b) is the edge coherent light beam arm structure example diagram in N+1 beam laser interference lithography system with different side incidence.

[0071] As shown in Figure 6 (a), when N edge coherent light beams and 1 central coherent light beam are incident to the sample table 5 from the same side, the second beam arm 4 includes: a first direction control unit 41, which controls the transmission path of the edge coherent light beam parallel to the central coherent light beam using a 2D adjustable right-angle mirror frame installed with a mirror, and controls the flux of the edge coherent light beam using a diaphragm to determine whether it participates in exposure; a second energy control unit 42, which controls the energy and linear polarization direction of the edge coherent light beam using a 1 / 2 wave plate and a polarizer together; a second beam collimation unit 43, which expands, filters and collimates the edge coherent light beam using two lenses and a pinhole, while controlling the spot diameter size; and a second direction control unit 44, which controls the edge coherent light beam to be incident to the sample table 5 at a specified incidence angle using a rotatable mirror and a high reflector.

[0072] As shown in Figure 6 (b), when N edge coherent light beams and 1 central coherent light beam are incident to the sample table 5 from different sides, the second beam arm 4 includes: a second energy control unit 42, which determines whether the edge coherent light beam participates in exposure using a diaphragm, and controls the energy and linear polarization direction of the edge coherent light beam using a 1 / 2 wave plate and a polarizer together; a second beam collimation unit 43, which expands, filters and collimates the edge coherent light beam using two lenses and a pinhole, while controlling the spot diameter size; and a second direction control unit 44, which controls the edge coherent light beam to be incident to the sample table 5 at a specified incidence angle using a rotatable mirror and a high reflector.

[0073] Wherein, the second direction control unit 44 and the second beam collimation unit 43 are connected by a telescopic support rod, and the telescopic length is not less than l· cot θ , and the specified incidence angle is obtained by rotating the mirror of the second direction control unit 44; wherein, l is the horizontal distance between the edge coherent light beam and the central coherent light beam, and the control range of the incidence angle is 0.1°-89°.

[0074] In summary, no matter whether the N beams of edge coherent light and the 1 beam of center coherent light are incident to the sample table 5 from the same side or from different sides, the spatial position angle of the edge coherent light can be modulated (modulation range 0-360°) by cooperating the second beam arm 4 with the rotating light splitting module 2. Please refer to the spatial angle modulation diagram of the 4+1 beam laser interference lithography system with the same side incidence as shown in Figure 7

[0075] The sample table 5 can realize three-axis (X / Y / Z) high-precision linear displacement, with a resolution of 1 µm and a repeat positioning accuracy of better than ±0.5 µm. The sample table 5 can also be rotated at any angle, with a rotation accuracy of 0.1°, and can realize fast switching of multi-period and multi-direction patterns by cooperating with beam adjustment. It supports automatic load leveling to ensure the consistency of the focal plane during large-area exposure. The center of the sample table 5 is located at the center of the main optical axis. In addition, the position of the Z direction where the sample table 5 is located is not arbitrary, and needs to be determined according to the actual use of the incidence angle, which is controlled by the second direction control unit 44. Therefore, a linkage control module is designed, that is, an independent driver is matched for each second direction control unit 44. Its role has two aspects, one is to control the direction of light, and the other is to correct the deviation of the mechanical part error to the light path direction.

[0076] When the N beams of edge coherent light and the 1 beam of center coherent light are incident to the sample table 5 from different sides, the sample table 5 is set to a center hollow structure, and the substrate material is set to be light-transmitting.

[0077] Here, the substrate material is the manufacturing object, and the light-transmitting substrate material includes glass, quartz, sapphire, etc.

[0078] When the N beams of edge coherent light and the 1 beam of center coherent light are incident to the sample table 5 from the same side, the sample table 5 is set to a center hollow or solid plane structure, and the substrate material is set to be any plane material. The spin-coating thickness of the photosensitive material is set to cover 0.5-1 times the period of the Z axis of the three-dimensional interference light field, so as to prepare a double-sided period micro-nano three-dimensional structure; or the spin-coating thickness of the photosensitive material is set to cover more than 1 times the period of the Z axis of the three-dimensional interference light field, so as to prepare a three-dimensional period micro-nano three-dimensional structure.

[0079] Here, the substrate material can be a light-transmitting material or a non-light-transmitting material, such as various metal sheets and metal films, silicon wafers and other non-transparent semiconductor materials, etc.

[0080] Embodiment two:

[0081] With Figure 1 and 2 ​The structure example diagram and optical path schematic diagram of the different side incidence 4+1 beam laser interference lithography system are taken as examples. For a three-dimensional light field composed of 4+1 coherent light beams, the laser light source of the light source module 1 is a 355 nm wavelength narrow linewidth laser. The laser light passes through the rotating light splitting module 2 in the direction of the main optical axis to complete the light splitting of the 4+1 coherent light beams. Among them, the center coherent light beam B0 passes through the rotating light splitting module 2 and enters the first light beam arm 3 to directly reach the sample table 5. The edge coherent light beams B1, B2, B3 and B4 are emitted from different light outlets of the rotating light splitting module 2 and enter the corresponding second light beam arms 4. The rotating light splitting module 2 cooperates with the four second light beam arms 4 to realize that the spatial position angle distributions of the edge coherent light beams B1, B2, B3 and B4 are 0°, 90°, 180° and 270°, and the spatial angle interval of each edge coherent light beam is 90°. The edge coherent light beams B1 and B2 are located in the XOZ plane, and the edge coherent light beams B3 and B4 are located in the YOZ plane. In addition, the second light beam arms 4 set the same incident angle θ of 55° for these edge coherent light beams, the same polarization angle of 90°, and the same energy of 1 mW / cm 2 . The sample table 5 is hollow in the center.

[0082] The energy control unit 32 of the first light beam arm 3 of the center coherent light beam only uses a 1 / 4 wave plate, so that the center coherent light beam can be a left-handed circularly polarized light. In this embodiment, no matter how the polarization state combination of the four edge coherent light beams is selected, the periods in the x and y directions are equal, but the period in the z direction changes because the center light beam is changed to be incident from the back, and the period in the z direction is always less than the wavelength When the incident angles of the coherent light beams are the same, the periods of the interference light field in the x, y and z directions are: (1)

[0083] The substrate material is quartz glass with a thickness of 1 mm, and the photosensitive material has a thickness of 800 nm.

[0084] Please refer to the simulation and experimental result diagram of the three-dimensional periodic micro-nano structure prepared by the different side incidence 4+1 beam laser interference lithography system as shown in Figure 8

[0085] The left graph is a simulated three-dimensional periodic micro-nano structure diagram, which presents a periodic lattice structure similar to an opal structure. Each unit cell presents a bright region in the center, surrounded by a relatively dark region, forming a regular light intensity distribution. This three-dimensional structure shows obvious periodic changes in the x, y and z directions, and the center-to-center distance of each unit is about 500 nm, and also has good symmetry and periodicity in the vertical direction (z axis).

[0086] Figure 8 ​(a) and (c) are respectively the plan view and cross-sectional view of the simulated three-dimensional periodic micro-nano structure. The plan view shows the periodic distribution of the light field in the x-o-y plane, with higher light intensity at the center of each unit cell and lower light intensity around it; the cross-sectional view shows the variation of the light field in the x-o-z plane, showing the distribution characteristics of the light intensity in the vertical direction, indicating that the light field has similar periodic structure at different depths.

[0087] The right side is the three-dimensional periodic micro-nano structure obtained by experiment, Figure 8 (b) and (d) are respectively the SEM plan view and cross-sectional view of the three-dimensional periodic micro-nano structure obtained by experiment. The SEM image shows the periodic nanostructure formed on the surface of the material, and its morphology is highly consistent with the simulated light field image. The experimental results verify that the 4+1 beam laser interference lithography system with different side incidence can obtain three-dimensional periodic nanostructure, which is consistent with the simulation results.

[0088] In the plan Figure 8 (b), a regularly arranged lattice structure can be observed, each dot corresponds to a bright area in the simulated light field, surrounded by lower areas, forming a pattern similar to hexagonal close packing. In the cross-sectional Figure 8 (d), the extension of the structure in the vertical direction can be seen, showing similar symmetry and periodicity to the simulation image, indicating that the structure has good uniformity and repeatability in three-dimensional space. The white scale in the figure is 500nm long, used to indicate the size of the structure.

[0089] Example Three:

[0090] As shown in the structure example diagram of the 4+1 beam laser interference lithography system with same side incidence as Figure 3 and the structure example diagram of the 3+1 beam laser interference lithography system with same side incidence as Figure 9 The N+1 beam laser interference lithography system can realize downward compatible multi-beam laser interference lithography. The key is to use the 4+1 beam laser interference lithography system with same side incidence to realize the 3+1 beam laser interference lithography to prepare double-sided periodic micro-nano three-dimensional structure. The specific operation mode is as follows:

[0091] As shown in Figure 3 , the first direction control unit 31 in the second beam arm 4 of any edge coherent beam is blocked by the diaphragm to obtain 3 edge coherent beams, thereby realizing 3+1 beam laser interference lithography, please refer to Figure 9The schematic diagram of 3+1 beam laser interference lithography with same side incidence is shown. The central coherent beam B0 is set to be incident from the front, the spatial angular distribution of the edge coherent beams B1, B2 and B3 is 0°, 90° and 180° respectively, the spatial angular interval of each edge coherent beam is 90°, the incidence angle of the edge coherent beams is equal to θ, and the edge coherent beams B1 and B2 are located in the XOZ plane, and the edge coherent beam B3 is located in the YOZ plane.

[0092] The experimental result diagram and the cross-sectional SEM diagram of the double-sided periodic micro-nano three-dimensional structure prepared by using the 3+1 beam laser interference system with same side incidence are shown in Figure 10 and 11 The experimental result diagram and the cross-sectional SEM diagram of the double-sided periodic micro-nano three-dimensional structure prepared by using the 3+1 beam laser interference system with same side incidence are shown in Figure 10 (a)-(c) are experimental result diagrams of the double-sided periodic structure obtained when the incidence angle θ is 20°, Figure 10 (d)-(f) are experimental result diagrams of the double-sided periodic structure obtained when the incidence angle θ is 50°. The two structures are similar in morphology to the microstructure in the butterfly wing, and have the same period in the x and y directions.

[0093] When θ is 20°, the period of the micro-nano structure is 1 micrometer, and when θ is 50°, the period of the micro-nano structure is 500 nanometers. Therefore, increasing the incidence angle of the edge beams can reduce the period to below 500 nanometers, thereby approaching the resolution limit of the photoresist.

[0094] In addition, by extracting a part of the simulated intensity distribution in the spatial light field, the structure formation process is further analyzed, and the result is shown in Figure 10 (c). The distribution presents a regular undulating structure composed of alternating peaks and valleys, thereby forming an obvious periodic interference pattern. As shown in Figure 10 (b), the structure has a period of 1 micrometer in the x and y directions, and higher main ridges and lower beams appear alternately, forming a complex 3D geometry, which exhibits a highly ordered periodicity in the XOY plane, which is completely consistent with the simulation result.

[0095] Further, by adjusting the exposure time, the evolution of the layered morphology in each layer of the three-dimensional periodic micro-nano structure can be observed and recorded. In the spatial light field, the cross-linking reaction of the photoresist proceeds from the top to the bottom. Therefore, by precisely controlling the exposure time, the surface topography at different positions in the z-axis direction can be captured.

[0096] The above is only a preferred embodiment of the present application, and those skilled in the art can make many changes in specific implementation and application range according to the technical content of the present application, as long as these changes do not deviate from the concept of the present application, and all belong to the protection scope of the present application.

Claims

1. An N+1 beam laser interferometric lithography system, characterized in that, The system comprises: A light source module (1) controls the exposure dose of the laser beam emitted by the laser using an electrically controlled clock valve device, and controls the laser beam to be incident at 45° to a rotating light splitting module (2) using a mirror group; The rotating light splitting module (2) is used for splitting the laser beam in amplitude to obtain N+1 coherent light beams with similar energy, and modulating the spatial positions of the N edge coherent light beams respectively; A first beam arm (3) is arranged on the main optical axis and is used for controlling 1 central coherent light beam located on the main optical axis to be directly incident to a sample stage (5) capable of rotating by 360° and moving in three dimensions; A second beam arm (4) is arranged on the transmission path of each edge coherent light beam and is used for respectively controlling N edge coherent light beams to be incident to the sample stage (5) from the same side or different sides at a specified incident angle together with 1 central coherent light beam; The sample stage (5) places a substrate material coated with spin-on photosensitive material, and forms a three-dimensional interference light field on the substrate material by converging N+1 coherent light beams incident from the same side or different sides, thereby preparing a double-sided periodic or three-dimensional periodic micro-nano structure; The rotating light splitting module (2) comprises N cubic cage mirror frames (21), N light splitting mirrors, N 1 / 2 wave plates and N-1 rotating assemblies (22); The cubic cage mirror frame (21) is a cubic structure with a hollow mounting cavity, used for embedding the light splitting mirror and the 1 / 2 wave plate, and the 1 / 2 wave plate is arranged behind the light splitting mirror and used for adjusting the phase delay of each coherent light beam; The thickness of each light splitting mirror is not more than 1 mm, and the splitting ratios are N:1, (N-1):1, (N-2):1, (N-3):1 in sequence, and N is minimum 2 and maximum 4; The inner wall of each cubic cage mirror frame (21) is provided with a positioning structure for accurately limiting the installation inclination angle of the light splitting mirror to 45°; wherein the installation inclination angle refers to the included angle between the light splitting interface and the laser incident direction.

2. The N+1 beam laser interferometric lithography system of claim 1, wherein, The rotating assembly (22) is used for connecting two adjacent cubic cage mirror frames (21), and through the rotating scale and the fixing screw, the edge coherent light beam is rotated by 360° around the main optical axis, thereby controlling the spatial position of the edge coherent light beam.

3. The N+1 beam laser interferometric lithography system of claim 1, wherein, The first beam arm (3) comprises: A first energy control unit (32) uses a 1 / 2 wave plate and a polarizer to jointly control the energy and linear polarization direction of the central coherent light beam; A first beam collimation unit (33) uses two lenses and a small hole to expand, filter and collimate the central coherent light beam to control the spot diameter, thereby converting the Gaussian light into flat-top light.

4. The N+1 beam laser interferometric lithography system of claim 1, wherein, When N edge coherent light beams and 1 central coherent light beam are incident to the sample stage (5) from the same side, the second beam arm (4) comprises: A first direction control unit (41) uses a 2D control right-angle mirror frame installed with a mirror to control the transmission path of the edge coherent light beam to be parallel to the central coherent light beam, and uses a diaphragm to control the flux of the edge coherent light beam and determine whether it participates in exposure; The second energy control unit (42) uses a 1 / 2 wave plate and a polarizer to jointly control the energy and linear polarization direction of the edge coherent light beam; The second beam collimation unit (43) uses two lenses and a pinhole to expand, filter and collimate the edge coherent light beam while controlling the spot diameter size; The second direction control unit (44) uses an electrically driven rotatable mirror and a high reflector to jointly control the edge coherent light beam to be incident on the sample table (5) at a specified incident angle.

5. The N+1 beam laser interferometric lithography system of claim 1, wherein, When N edge coherent light beams and 1 central coherent light beam are incident on the sample table (5) from different sides, the second beam arm (4) comprises: The second energy control unit (42) uses a diaphragm to determine whether the edge coherent light beam participates in exposure, and uses a 1 / 2 wave plate and a polarizer to jointly control the energy and linear polarization direction of the edge coherent light beam; The second beam collimation unit (43) uses two lenses and a pinhole to expand, filter and collimate the edge coherent light beam while controlling the spot diameter size; The second direction control unit (44) uses an electrically driven rotatable mirror and a high reflector to jointly control the edge coherent light beam to be incident on the sample table (5) at a specified incident angle.

6. The N+1 beam laser interferometric lithography system of claim 4 or 5, wherein, The second direction control unit (44) and the second light beam collimation unit (43) are connected by a telescopic support rod, and the telescopic length is not less than l· cot θ The specified incident angle is obtained by rotating the mirror of the second direction control unit (44); wherein, l The horizontal distance between the edge coherent light beam and the center coherent light beam.

7. The N+1 beam laser interferometric lithography system of claim 1, wherein, When N edge coherent light beams and 1 central coherent light beam are incident on the sample table (5) from different sides, the sample table (5) is arranged as a center hollow structure, and the substrate material is arranged to be light-transmitting.

8. The N+1 beam laser interferometric lithography system of claim 1, wherein, When N edge coherent light beams and 1 central coherent light beam are incident on the sample table (5) from the same side, the sample table (5) is arranged as a center hollow or solid plane structure, and the substrate material is arranged as any plane material.

9. The N+1 beam laser interferometric lithography system of claim 8, wherein, The spin-coating thickness of the photosensitive material is arranged to cover 0.5-1 times the period of the Z-axis of the three-dimensional interference light field, so as to prepare a double-sided period micro-nano three-dimensional structure. Alternatively, the spin-coating thickness of the photosensitive material is arranged to cover more than 1 times the period of the Z-axis of the three-dimensional interference light field, so as to prepare a three-dimensional period micro-nano three-dimensional structure.

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