Preparation method of micro-nano optical structural color film based on all-dielectric silicon

Abstract

The application provides a preparation method of a full-dielectric silicon-based micro-nano optical structural color thin film, which comprises the following steps: obtaining structural parameters of the optical structural color thin film by using a finite-difference time-domain method according to chromaticity and reflectivity of the optical structural color thin film to be prepared; performing ultrasonic cleaning on an SOI chip, plating a chromium adhesion layer with a thickness of 2 nm to obtain an SOI substrate, and uniformly coating photoresist with a thickness of 150 nm to obtain an SOI photoresist layer; adjusting parameters of a double-beam laser interference optical path to perform interference exposure on the SOI photoresist layer to obtain a micro-nano optical structure pattern; after evaporating a metal chromium film with a thickness of 30 nm on the micro-nano optical structure pattern, dissolving the photoresist with a developing solution to strip the metal chromium film, and forming a chromium mask with the micro-nano optical structure pattern; and etching the SOI chip by using an inductively coupled plasma etching technology to obtain a Si micro-nano optical structural color thin film. The Si micro-nano optical structural color thin film obtained by the method has high resolution and high brightness, and the color and processing area are adjustable.

Description

Technical Field

[0001] The present application belongs to the field of laser interference lithography technology, and in particular relates to a method for preparing a micro-nano optical structure color film based on all-dielectric silicon. Background Art

[0002] Micro-nano optics is characterized by its ability to precisely control light fields at extremely small spatial scales, making it of great significance in new physics and applications. The micro-nano structures (such as nanowires, nanopores, nanopillars, and nanoparticles) on micro-nano optical structured color surfaces can manipulate the light waves scattered by the surface by varying their periodic distribution and characteristic size. Therefore, they hold great promise in cutting-edge applications such as ultra-high-resolution backlight-free displays, optical information storage, and image encryption.

[0003] At present, the scale of preparation of micro-nano optical structural colors is mostly at the micron level, and common manufacturing technologies used for structural color preparation include: focused ion beam lithography, electron beam lithography, reactive ion beam etching, nanoimprinting and self-assembly technology. Although these methods can achieve the preparation of micro-nano optical metal / dielectric structural colors with controllable period, size, morphology and arrangement, they are limited by low processing efficiency and high cost and are not suitable for large-scale commercial production. Summary of the Invention

[0004] In view of this, the purpose of this application is to provide a method for preparing a micro-nano optical structure color film based on all-dielectric silicon. By adjusting the parameters of the dual-beam laser interference optical path, the grating period and characteristic size of the micro-nano optical structure can be adjusted, and the color of the micro-nano optical structure color film can be adjusted. At the same time, by controlling the exposure time of the ultraviolet laser beam and the movement of the sample stage, the processing area of ​​the micro-nano optical structure color film can be adjusted; in addition, due to the advantage of the high refractive index of the all-dielectric silicon material, the micro-nano optical structure color film based on all-dielectric silicon has the characteristics of high resolution and high brightness.

[0005] The present application provides a method for preparing a micro-nano optical structured color film based on all-dielectric silicon, the method comprising:

[0006] According to the chromaticity and reflectivity of the optical structural color film to be prepared, the structural parameters of the optical structural color film are obtained using the finite difference time domain method; the structural parameters include: grating period, characteristic size and height;

[0007] After ultrasonic cleaning of the high-height SOI chip, a 2 nm thick chromium adhesion layer is plated to obtain an SOI substrate, and a 150 nm thick photoresist is uniformly coated on the surface of the SOI substrate to obtain an SOI adhesive layer;

[0008] Adjust parameters of a dual-beam laser interference optical path based on the structural parameters to perform interference exposure on the SOI adhesive layer, so as to obtain a micro-nano optical structure pattern with the grating period and feature size;

[0009] After evaporating a 30-nm-thick metal chromium film on the micro-nano optical structure pattern, dissolve the photoresist on the micro-nano optical structure pattern with a developing solution to strip the metal chromium film, so as to form a chromium mask with the micro-nano optical structure pattern;

[0010] After etching the SOI chip according to the pattern of the chromium mask by using an inductively coupled plasma etching technology, remove the residual chromium mask layer on the surface, so as to obtain a Si micro-nano optical structure color film.

[0011] Further, the dual-beam laser interference optical path comprises a laser, a light splitting element, a reflecting element, a half-wave plate, a polarizer, and a micro-displacement sample stage;

[0012] The laser is configured to emit a 360-nm ultraviolet laser beam;

[0013] The light splitting element is configured to split the ultraviolet laser beam into two laser beams with the same power;

[0014] The reflecting element is configured to adjust the propagation path of the laser beam, so that the two laser beams have the same angle of incidence to the micro-displacement sample stage;

[0015] The half-wave plate and the polarizer are configured to adjust the polarization direction and laser power of the laser beam, so that the amplitudes of the two laser beams are the same and interference is generated, and the grating period and feature size of the micro-nano optical structure pattern are changed;

[0016] The micro-displacement sample stage is configured to fix the SOI adhesive layer.

[0017] Further, the dual-beam laser interference optical path further comprises an aperture stop, a convex lens, and a pinhole;

[0018] The aperture stop is arranged between the polarizer and the sample stage, and is configured to reshape the spot shape of the two laser beams into a square shape to adapt to the shape of the SOI chip;

[0019] The convex lens and the pinhole are arranged between the reflecting element and the aperture stop, and are configured to filter and amplify the laser beam.

[0020] Further, the dual-beam laser interference optical path further comprises a light shutter;

[0021] The light shutter is arranged between the laser and the light splitting element, and is configured to control the exposure time of the ultraviolet laser beam;

[0022] After the SOI adhesive layer is fixed on the micro-displacement sample stage, large-area interference exposure of the SOI adhesive layer is achieved by setting the moving speed and moving path of the micro-displacement sample stage and the exposure time of the optical shutter;

[0023] Wherein, the micro-displacement sample stage can perform micro-movement in a two-dimensional plane.

[0024] Furthermore, the micro-nano optical structure includes: a Si nanowire grid structure.

[0025] Furthermore, the grating period of the micro-nano optical structure is in the range of 200-300 nm;

[0026] The characteristic size of the micro-nano optical structure ranges from 50 to 200 nm.

[0027] Furthermore, the reflection wavelength range of the Si micro-nano optical structure color film is 400-700nm;

[0028] The thickness of the Si micro-nano optical structure color film ranges from 50 to 400 nm;

[0029] The area of ​​the Si micro-nano optical structure color film ranges from 1 to 100 cm 2 .

[0030] Furthermore, the etching parameters of the inductively coupled plasma etching technology are set as follows: CHF3 gas flow rate is 80 sccm, front RF voltage is 300 V, rear RF voltage is 20 V, and etching time is 360 s.

[0031] Furthermore, after obtaining the Si micro-nano optical structure color film, the method further includes:

[0032] A scanning electron microscope is used to obtain a scanning electron microscope image of the Si micro-nano optical structure color film to verify the structural characteristics of the Si micro-nano optical structure color film.

[0033] Furthermore, after obtaining the Si micro-nano optical structure color film, the method further includes:

[0034] A high-power halogen light was used as the light source, and a 100x objective lens was used to focus the incident light perpendicularly to the surface of the Si micro-nano optical structure color film. The full-angle illumination reflection mode of the micro-angle-resolved spectrometer was used for measurement to obtain the reflection spectrum of the Si micro-nano optical structure color film.

[0035] Based on the reflection spectrum, the reflection wavelength and reflectivity of the Si micro-nano optical structure color film are obtained to test the performance of the Si micro-nano optical structure color film.

[0036] The method for preparing a micro-nano optical structure color film based on all-dielectric silicon in the present application adjusts the parameters of the dual-beam laser interference optical path to make the grating period and characteristic size of the micro-nano optical structure adjustable, and the color of the micro-nano optical structure color film adjustable. At the same time, by controlling the exposure time of the ultraviolet laser beam and the movement of the sample stage, the processing area of ​​the micro-nano optical structure color film can be adjusted. In addition, due to the advantage of the high refractive index of the all-dielectric silicon material, the micro-nano optical structure color film based on all-dielectric silicon has the characteristics of high resolution and high brightness. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A flow chart of a method for preparing a micro-nano optical structured color film based on all-dielectric silicon provided in an embodiment of the present application is shown;

[0038] Figure 2 A schematic diagram of a dual-beam laser interference optical path provided in an embodiment of the present application is shown;

[0039] Figure 3 A sample image of a blue all-dielectric silicon micro-nano optical structure color film provided in an embodiment of the present application is shown;

[0040] Figure 4 The scanning electron microscopic image of the blue all-dielectric silicon micro-nano optical structure color film provided in the embodiment of the present application is shown;

[0041] Figure 5 The reflection spectrum of the blue all-dielectric silicon micro-nano optical structure color film provided in the embodiment of the present application is shown;

[0042] Figure 6 A sample image of a green all-dielectric silicon micro-nano optical structure color film provided in an embodiment of the present application is shown;

[0043] Figure 7 A scanning electron microscopic image of a green all-dielectric silicon micro-nano optical structure color film provided in an embodiment of the present application is shown;

[0044] Figure 8 The reflection spectrum of the green all-dielectric silicon micro-nano optical structure color film provided in the embodiment of the present application is shown;

[0045] Figure 9 A sample image of a red all-dielectric silicon micro-nano optical structure color film provided in an embodiment of the present application is shown;

[0046] Figure 10 A scanning electron microscopic image of a red all-dielectric silicon micro-nano optical structure color film provided in an embodiment of the present application is shown;

[0047] Figure 11 The reflection spectrum of the red all-dielectric silicon micro-nano optical structure color film provided in the embodiment of the present application is shown;

[0048] The reference numerals include: 1-laser, 2-optical gate, BS-spectrometric element, HR-reflective element, H-half-wave plate, P-polarizer, 3-convex lens, 4-pinhole, 5-aperture, 6-SOI adhesive layer, 7-micro-displacement sample stage, 8-computer. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solution and advantages of this technical solution more clear, the following technical solution is further described in detail in conjunction with specific implementation methods. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of this technical solution.

[0050] Silicon (Si) is frequently used in the fabrication of micro-nano optical structural color films due to its low cost, high refractive index, high reliability, and compatibility with optoelectronic devices. Subwavelength-sized Si structures exhibit strong electromagnetic resonance upon interaction with visible light. Nanofilters fabricated from Si in various shapes can achieve high-purity, wide-color gamut structural color in the visible light band. Furthermore, the higher refractive index of all-dielectric silicon compared to metals allows for greater brightness and vividness of the structural colors.

[0051] Laser interference lithography is a method for producing large-area periodic micro- and nanostructure patterns. The periodically distributed light intensity in the interference region is directly exposed to the photoresist surface, offering the advantages of maskless, low-cost, high-efficiency, and large-area fabrication.

[0052] In view of this, this application uses all-dielectric silicon materials and laser interference lithography technology to prepare Si micro-nano optical structure color films with high resolution and high brightness. By adjusting the laser interference lithography parameters, the grating period and characteristic size of the micro-nano optical structure can be changed to achieve the adjustment of the surface color and brightness of the Si micro-nano optical structure color film.

[0053] Next, the method for preparing the micro-nano optical structure color film based on all-dielectric silicon provided in this application and the structural characteristics of the obtained Si micro-nano optical structure color film will be explained with reference to specific examples.

[0054] Example 1

[0055] See also Figure 1 , Figure 1 This is a flow chart of the method for preparing a micro-nano optical structure color film based on all-dielectric silicon provided in the embodiment of this application. Figure 1 As shown, the method includes:

[0056] S101. According to the chromaticity and reflectivity of the optical structural color film to be prepared, the structural parameters of the optical structural color film are obtained using the finite difference time domain method; the structural parameters include: grating period, characteristic size and height.

[0057] In this step, the surface color of the optical structured color film is related to its surface structure. Specifically, the surface color can be changed by adjusting the grating period and characteristic size of the surface structure to adjust its reflection wavelength. In addition, the reflectivity of the optical structured color film is related to the grating depth: a larger grating depth leads to higher reflectivity, while a smaller grating depth enhances transmission. Therefore, based on the chromaticity and reflectivity of the optical structured color film, the surface structure of the optical structured color film can be designed using the finite-difference time-domain method to obtain the structural parameters of the optical structured color film, including the grating period, characteristic size, and height.

[0058] S102 , ultrasonically clean the SOI chip of the height, plate a 2 nm thick chromium adhesion layer to obtain an SOI substrate, and uniformly coat a 150 nm thick photoresist on the surface of the SOI substrate to obtain an SOI adhesive layer.

[0059] In this step, first, an SOI (Silicon On Insulator) chip with the same height as the structural parameters is selected as a sample. The SOI chip is ultrasonically cleaned in acetone solution, anhydrous ethanol, and deionized water solution for 5 minutes in sequence to remove surface contaminants. Secondly, since the SOI chip is hydrophobic, a 2nm thick chromium adhesion layer is plated on the cleaned SOI chip to obtain an SOI substrate to improve its coating quality. Thirdly, Allresist AR-P-3170 photoresist is spin-coated at a speed of 1200 rpm to evenly coat the surface of the SOI substrate with a thickness of 150nm to obtain an SOI adhesive layer.

[0060] S103 . Based on the structural parameters, adjust the parameters of the dual-beam laser interference optical path to perform interference exposure on the SOI adhesive layer to obtain a micro-nano optical structure pattern with the grating period and characteristic size.

[0061] The micro-nano optical structure includes: a Si nanowire grid structure; the grating period of the micro-nano optical structure ranges from 200 to 300 nm; and the characteristic size of the micro-nano optical structure ranges from 50 to 200 nm.

[0062] Here, see Figure 2 , Figure 2 Schematic diagram of the dual-beam laser interference optical path provided in the embodiment of the present application. Figure 2 As shown, the dual-beam laser interference optical path includes: a laser, a beam splitter, a reflective element, a half-wave plate, a polarizer, and a micro-displacement sample stage.

[0063] The laser is used to emit a 360nm ultraviolet laser beam; the beam splitter is used to split the ultraviolet laser beam into two laser beams with equal power; the reflective element is used to adjust the propagation path of the laser beam so that the two laser beams are incident on the micro-displacement sample stage at the same angle; the half-wave plate and polarizer are used to adjust the polarization direction and laser power of the laser beam so that the amplitudes of the two laser beams are the same and interference occurs, as well as to change the grating period and characteristic size of the micro-nano optical structure pattern; and the micro-displacement sample stage is used to fix the SOI adhesive layer.

[0064] Specifically, the light splitting element is a 1:1 ultraviolet light splitter, and the light reflecting element is a ultraviolet high reflective mirror.

[0065] In addition, the dual-beam laser interference optical path further includes: an aperture, a convex lens and a pinhole;

[0066] The aperture is arranged between the polarizer and the sample stage, and is used to shape the spot shape of the two laser beams into a square to adapt to the shape of the SOI chip; the convex lens and the small hole are arranged between the reflective element and the aperture, and are used to filter and amplify the laser beams.

[0067] The dual-beam laser interference optical path further includes: an optical gate;

[0068] The optical shutter is arranged between the laser and the beam splitter element, and is used to control the exposure time of the ultraviolet laser beam;

[0069] After the SOI adhesive layer is fixed on the micro-displacement sample stage, large-area interference exposure of the SOI adhesive layer is achieved by setting the moving speed and moving path of the micro-displacement sample stage and the exposure time of the optical shutter;

[0070] Wherein, the micro-displacement sample stage can perform micro-movement in a two-dimensional plane.

[0071] Here, the optical shutter and the micro-displacement sample stage are both controlled by a computer.

[0072] S104 , after evaporating a metal chromium film with a thickness of 30 nm on the micro-nano optical structure pattern, using a developer to dissolve the photoresist on the micro-nano optical structure pattern to peel off the metal chromium film, forming a chromium mask having the micro-nano optical structure pattern.

[0073] S105 , using inductively coupled plasma etching technology, after etching the SOI chip according to the pattern of the chromium mask, remove the chromium mask layer remaining on the surface to obtain a Si micro-nano optical structure color film.

[0074] The etching parameter of the inductively coupled plasma etching technology is set as follows: CHF3 gas flow is 80sccm, front radio frequency voltage is 300V, back radio frequency voltage is 20V, and etching time is 360s.

[0075] In this step, the etching time is determined by the thickness of the SOI chip, so as to etch through the surface Si film to the SiO2 layer, and finally form a Si micro-nano optical structure on the surface of the SiO2, so as to obtain a Si micro-nano optical structure color thin film.

[0076] The reflection wavelength range of the Si micro-nano optical structure color thin film is 400-700nm; the thickness of the Si micro-nano optical structure color thin film is 50-400nm; and the area of the Si micro-nano optical structure color thin film is 1-100cm 2 .

[0077] After obtaining the Si micro-nano optical structure color thin film, the method further comprises:

[0078] Step 106, using a scanning electron microscope, a scanning electron micrograph of the Si micro-nano optical structure color thin film is obtained to verify the structural characteristics of the Si micro-nano optical structure color thin film.

[0079] In this step, the structural characteristics of the Si micro-nano optical structure color thin film, such as etching depth, grating period, and average feature size, can be obtained by analyzing the scanning electron micrograph. By comparing with the structural parameters of the optical structure color thin film obtained by the finite difference time domain method, it is verified whether the structural characteristics of the Si micro-nano optical structure color thin film meet the requirements.

[0080] Step 107, using a 100x objective lens to focus high-power halogen light as a light source, so that the incident light is perpendicular to the surface of the Si micro-nano optical structure color thin film, and using a microscopic angle-resolved spectrometer in a full-angle illumination reflection mode to measure the reflection spectrum of the Si micro-nano optical structure color thin film.

[0081] In this step, the diffuse light of the high-power halogen light source is focused on the back focal plane of the 100x objective lens, wherein the numerical aperture NA of the objective lens is 0.7.

[0082] Step 108, based on the reflection spectrum, the reflection wavelength and reflectivity of the Si micro-nano optical structure color thin film are obtained to test the performance of the Si micro-nano optical structure color thin film.

[0083] Example two,

[0084] The preparation method of the blue full-dielectric silicon micro-nano optical structure color thin film comprises:

[0085] Step 201: According to the chromaticity and reflectivity of the blue light micro-nano optical structure color film, the structural parameters of the blue light micro-nano optical structure color film are obtained using the time-domain finite difference method: grating period 300nm, characteristic size 60nm and height 200nm.

[0086] Step 202 : After ultrasonic cleaning of a 200 nm thick SOI chip, a 2 nm thick chromium adhesion layer is plated to obtain an SOI substrate, and a 150 nm thick photoresist is evenly coated on the surface of the SOI substrate to obtain an SOI adhesive layer.

[0087] Step 203: Based on the above structural parameters, a 360nm ultraviolet laser (CNI MSL-FN-360-S) is selected and the parameters of the dual-beam laser interference optical path are adjusted: the incident angle of the two laser beams is 36.9°, and the laser power is set to 4mW / cm 2 The exposure time is set to 8s, and the SOI layer is subjected to interference exposure to obtain the micro-nano optical structure. At the same time, the moving speed and moving path of the micro-displacement sample stage, as well as the switching time of the optical gate, are coordinated to complete the area of ​​about 30cm 2 Processing of micro-nano optical structure patterns.

[0088] Step 204 : After evaporating a 30 nm thick metal chromium film on the micro-nano optical structure pattern, a developer is used to dissolve the photoresist on the micro-nano optical structure pattern to peel off the metal chromium film, thereby forming a chromium mask having the micro-nano optical structure pattern.

[0089] Step 205: Using ICP-RIE (Sentech SI 500), set the etching parameters as follows: CHF3 gas flow rate is 80 sccm, front RF voltage is 300 V, rear RF voltage is 20 V, etching time is 360 s, and after etching the SOI chip according to the pattern of the chromium mask, remove the residual chromium mask layer on the surface to obtain the following: Figure 3 The blue all-dielectric silicon micro-nano optical structural color film shown.

[0090] Step 206: Using a scanning electron microscope (FEI Helios NanoLab G4), obtain Figure 4 The scanning electron microscopy image of the blue all-dielectric silicon micro-nano optical structure color film shown in the figure shows that the blue all-dielectric silicon micro-nano optical structure color film has a Si nanowire grid structure, and its structural features are: etching depth of 200nm, grating period of 300nm, and average feature size of 54nm.

[0091] Step 207: Use high-power halogen light as the light source and focus it with a 100x objective lens so that the incident light is perpendicular to the surface of the blue all-dielectric silicon micro-nano optical structure color film. Use the full-angle illumination reflection mode of the micro-angle resolved spectrometer (ideaoptics ARMS) to measure and obtain the following: Figure 5 The reflection spectrum of the blue all-dielectric silicon micro-nano optical structural color film is shown.

[0092] Step 208: From the reflection spectrum, it can be seen that the reflection wavelength of the blue all-dielectric silicon micro-nano optical structure color film is 460nm, and the maximum reflectivity can reach 62%, which shows that the performance of the blue all-dielectric silicon micro-nano optical structure color film is good.

[0093] Example 3:

[0094] The preparation method of the green all-dielectric silicon micro-nano optical structure color film includes:

[0095] Step 301: According to the chromaticity and reflectivity of the green light micro-nano optical structure color film, the structural parameters of the green light micro-nano optical structure color film are obtained using the time-domain finite difference method: grating period 300nm, characteristic size 80nm and height 200nm.

[0096] Step 302 : After ultrasonic cleaning of a 200 nm thick SOI chip, a 2 nm thick chromium adhesion layer is plated to obtain an SOI substrate, and a 150 nm thick photoresist is evenly coated on the surface of the SOI substrate to obtain an SOI adhesive layer.

[0097] Step 303: Based on the above structural parameters, a 360nm ultraviolet laser (CNI MSL-FN-360-S) is selected and the parameters of the dual-beam laser interference optical path are adjusted: the incident angle of the two laser beams is 36.9°, and the laser power is set to 3mW / cm 2 The exposure time is set to 8s, and the SOI layer is subjected to interference exposure to obtain the micro-nano optical structure. At the same time, the moving speed and moving path of the micro-displacement sample stage, as well as the switching time of the optical gate, are coordinated to complete the area of ​​about 30cm 2 Processing of micro-nano optical structure patterns.

[0098] Step 304 : After evaporating a 30 nm thick metal chromium film on the micro-nano optical structure pattern, a developer is used to dissolve the photoresist on the micro-nano optical structure pattern to peel off the metal chromium film, thereby forming a chromium mask having the micro-nano optical structure pattern.

[0099] Step 305: Using ICP-RIE (Sentech SI 500), set the etching parameters: CHF3 gas flow rate is 80 sccm, front RF voltage is 300 V, rear RF voltage is 20 V, etching time is 360 s, and after etching the SOI chip according to the pattern of the chromium mask, remove the residual chromium mask layer on the surface to obtain the following: Figure 6 The green all-dielectric silicon micro-nano optical structural color film shown.

[0100] Step 306: Using a scanning electron microscope (FEI Helios NanoLab G4), obtain Figure 7 The scanning electron microscopy image of the green all-dielectric silicon micro-nano optical structure color film shown in the figure shows that the green all-dielectric silicon micro-nano optical structure color film has a Si nanowire grid structure, and its structural features are: etching depth of 200nm, grating period of 300nm, and average feature size of 74nm.

[0101] Step 307: Use high-power halogen light as the light source and focus it with a 100x objective lens so that the incident light is perpendicular to the surface of the green all-dielectric silicon micro-nano optical structure color film. Use the full-angle illumination reflection mode of the micro-angle resolved spectrometer (ideaoptics ARMS) to measure and obtain the following: Figure 8 The reflection spectrum of the green all-dielectric silicon micro-nano optical structural color film is shown.

[0102] Step 308: From the reflection spectrum, it can be seen that the reflection wavelength of the green all-dielectric silicon micro-nano optical structure color film is 560nm, and the maximum reflectivity can reach 73%, which shows that the performance of the green all-dielectric silicon micro-nano optical structure color film is good.

[0103] Example 4:

[0104] The preparation method of the red all-dielectric silicon micro-nano optical structure color film includes:

[0105] Step 401: According to the chromaticity and reflectivity of the red light micro-nano optical structure color film, the structural parameters of the red light micro-nano optical structure color film are obtained using the time-domain finite difference method: grating period 300nm, characteristic size 120nm and height 200nm.

[0106] Step 402 : After ultrasonic cleaning of a 200 nm thick SOI chip, a 2 nm thick chromium adhesion layer is plated to obtain an SOI substrate, and a 150 nm thick photoresist is evenly coated on the surface of the SOI substrate to obtain an SOI adhesive layer.

[0107] Step 403: Based on the above structural parameters, a 360nm ultraviolet laser (CNI MSL-FN-360-S) is selected and the parameters of the dual-beam laser interference optical path are adjusted: the incident angle of the two laser beams is 36.9°, and the laser power is set to 2mW / cm 2 The exposure time is set to 8s, and the SOI layer is subjected to interference exposure to obtain the micro-nano optical structure. At the same time, the moving speed and moving path of the micro-displacement sample stage, as well as the switching time of the optical gate, are coordinated to complete the area of ​​about 30cm 2 Processing of micro-nano optical structure patterns.

[0108] Step 404 : After evaporating a 30 nm thick metal chromium film on the micro-nano optical structure pattern, a developer is used to dissolve the photoresist on the micro-nano optical structure pattern to peel off the metal chromium film, thereby forming a chromium mask having the micro-nano optical structure pattern.

[0109] Step 405: Using ICP-RIE (Sentech SI 500), set the etching parameters: CHF3 gas flow rate is 80 sccm, front RF voltage is 300 V, rear RF voltage is 20 V, etching time is 360 s, and after etching the SOI chip according to the pattern of the chromium mask, remove the residual chromium mask layer on the surface to obtain the following: Figure 9 The red all-dielectric silicon micro-nano optical structural color film shown.

[0110] Step 406: Using a scanning electron microscope (FEI Helios NanoLab G4), obtain Figure 10 The scanning electron microscopy image of the red all-dielectric silicon micro-nano optical structure color film shown in the figure shows that the red all-dielectric silicon micro-nano optical structure color film has a Si nanowire grid structure, and its structural features are: etching depth of 200nm, grating period of 300nm, and average feature size of 106nm.

[0111] Step 407: Use high-power halogen light as the light source and focus it with a 100x objective lens so that the incident light is perpendicular to the surface of the red all-dielectric silicon micro-nano optical structure color film. Use the full-angle illumination reflection mode of the micro-angle resolved spectrometer (ideaoptics ARMS) to measure and obtain the following: Figure 11 The reflection spectrum of the red all-dielectric silicon micro-nano optical structural color film is shown.

[0112] Step 408: From the reflection spectrum, it can be seen that the reflection wavelength of the red all-dielectric silicon micro-nano optical structure color film is 670nm, and the maximum reflectivity can reach 91%, which shows that the performance of the red all-dielectric silicon micro-nano optical structure color film is good.

[0113] The above content is only a preferred embodiment of the present invention. For ordinary technicians in this field, many changes can be made in the specific implementation methods and application scope based on the ideas of the present technical content. As long as these changes do not deviate from the concept of the present invention, they all fall within the scope of protection of this patent.

Claims

1. A method for preparing a micro-nano optical structure color film based on all-dielectric silicon, characterized in that: The method comprises: According to the chromaticity and reflectivity of the optical structural color film to be prepared, the structural parameters of the optical structural color film are obtained using the finite difference time domain method; the structural parameters include: grating period, characteristic size and height; After ultrasonic cleaning of the high-height SOI chip, a 2 nm thick chromium adhesion layer is plated to obtain an SOI substrate, and a 150 nm thick photoresist is uniformly coated on the surface of the SOI substrate to obtain an SOI adhesive layer; Based on the structural parameters, adjusting the parameters of the dual-beam laser interference optical path to perform interference exposure on the SOI glue layer to obtain a micro-nano optical structure pattern with the grating period and characteristic size; After evaporating a metal chromium film with a thickness of 30 nm on the micro-nano optical structure pattern, dissolving the photoresist on the micro-nano optical structure pattern with a developer to peel off the metal chromium film to form a chromium mask having the micro-nano optical structure pattern; Using inductively coupled plasma etching technology, the SOI chip is etched according to the pattern of the chromium mask, and the chromium mask remaining on the surface is removed to obtain a Si micro-nano optical structure color film; The dual-beam laser interference optical path includes: a laser, a beam splitter, a reflective element, a half-wave plate, a polarizer, and a micro-displacement sample stage; The laser is used to emit a 360nm ultraviolet laser beam; The beam splitting element is used to split the ultraviolet laser beam into two laser beams with the same power; The reflective element is used to adjust the propagation path of the laser beam so that the two laser beams are incident on the micro-displacement sample stage at the same angle; The half-wave plate and polarizer are used to adjust the polarization direction and laser power of the laser beam so that the amplitudes of the two laser beams are the same and interference occurs, and to change the grating period and characteristic size of the micro-nano optical structure pattern; The micro-displacement sample stage is used to fix the SOI adhesive layer; The dual-beam laser interference optical path further includes: an aperture, a convex lens and a pinhole; The aperture is arranged between the polarizer and the micro-displacement sample stage, and is used to shape the spot shapes of the two laser beams into a square to adapt to the shape of the SOI chip; The convex lens and the small hole are arranged between the reflective element and the aperture, and are used to filter and amplify the laser beam; The dual-beam laser interference optical path further includes: an optical gate; The optical shutter is arranged between the laser and the beam splitter element, and is used to control the exposure time of the ultraviolet laser beam; After the SOI adhesive layer is fixed on the micro-displacement sample stage, large-area interference exposure of the SOI adhesive layer is achieved by setting the moving speed and moving path of the micro-displacement sample stage and the exposure time of the optical shutter; Wherein, the micro-displacement sample stage can perform micro-movement in a two-dimensional plane.

2. The method according to claim 1, wherein The micro-nano optical structure pattern includes: a Si nanowire grid structure.

3. The method according to claim 1, wherein The grating period of the micro-nano optical structure pattern is in the range of 200-300 nm; The characteristic size of the micro-nano optical structure pattern ranges from 50 to 200 nm.

4. The method according to claim 1, wherein The reflection wavelength range of the Si micro-nano optical structure color film is 400-700nm; The thickness of the Si micro-nano optical structure color film ranges from 50 to 400 nm; The area of ​​the Si micro-nano optical structure color film ranges from 1 to 100 cm2.

5. The method according to claim 1, wherein The etching parameters of the inductively coupled plasma etching technology are set as: CHF3 gas flow rate is 80 sccm, the front radio frequency voltage is 300 V, the rear radio frequency voltage is 20 V, and the etching time is 360 s.

6. The method according to claim 1, wherein After obtaining the Si micro-nano optical structure color film, the method further comprises: A scanning electron microscope is used to obtain a scanning electron microscope image of the Si micro-nano optical structure color film to verify the structural characteristics of the Si micro-nano optical structure color film.

7. The method according to claim 1, wherein After obtaining the Si micro-nano optical structure color film, the method further comprises: A high-power halogen light was used as the light source, and a 100x objective lens was used to focus the incident light perpendicularly to the surface of the Si micro-nano optical structure color film. The full-angle illumination reflection mode of the micro-angle-resolved spectrometer was used for measurement to obtain the reflection spectrum of the Si micro-nano optical structure color film. Based on the reflection spectrum, the reflection wavelength and reflectivity of the Si micro-nano optical structure color film are obtained to test the performance of the Si micro-nano optical structure color film.

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