A sub-wavelength metal grating polarization device structure and wafer-level manufacturing method thereof

Abstract

The present invention provides a sub-wavelength metal grating polarization device structure and a wafer-level manufacturing method thereof, comprising: a substrate; a first dielectric layer, deposited on the top of the substrate; a second dielectric layer, deposited on the top of the first dielectric layer; a plurality of dielectric grating layers, deposited on the top of the second dielectric layer and spaced along the length direction of the second dielectric layer, a groove is formed between each adjacent two dielectric grating layers, the material of each dielectric grating layer and the second dielectric layer has the same refractive index, and the grating period of each dielectric grating layer is less than the incident wavelength of the incident light; a plurality of first metal layers, respectively deposited in each groove; a plurality of second metal layers, respectively deposited on the top of each dielectric grating layer, and the material of each second metal layer and each first metal layer has the same dielectric constant. The beneficial effect is that the present invention can reduce the difficulty of micro-nano processing technology while obtaining excellent polarization performance, and realize large-area, high-fidelity, and high-efficiency manufacturing of sub-wavelength metal grating polarization device structure.

Description

Technical Field

[0001] The present invention relates to the technical field of optical device manufacturing, and in particular to a sub-wavelength metal grating polarization device structure and a wafer-level manufacturing method thereof. Background Art

[0002] Polarization imaging technology can achieve functions such as background suppression, detail highlighting and target detection by combining the target's spatial image information with the polarization information that characterizes its interface properties. It provides a solution for improving the perception of complex environments and has broad application prospects in military and civilian fields such as military reconnaissance, industrial inspection, and medical diagnosis.

[0003] Traditional polarization imaging systems have problems such as large size, difficult processing and high cost. In particular, the complex splitter components limit the current system development in the direction of miniaturization, lightweight and low cost. The sub-wavelength metal grating polarization device structure based on micro-nano manufacturing technology has the characteristics of free and flexible control of light field, as well as easy integration, customization, planarization and excellent performance. It has become a key component for building micro-sized or even chip-level polarization imaging systems.

[0004] In recent years, thanks to the development of micro-nano processing technologies such as electron beam lithography and nanoimprinting, sub-wavelength metal grating polarization devices for polarization imaging applications have been extensively studied by many researchers and gradually replaced traditional polarization devices. For example, in 2008, YB Chen et al. from Georgia Institute of Technology in the United States [Journal of Heat Transfer, 2008, 130(8): 1255-1264.] used electron beam lithography to design and prepare a metal grating array structure with a structural period of 800~1000nm and a line width of 285~296nm on a silicon substrate. The experimentally measured TM transmittance was better than 40% in the 8~10μm band, and the extinction ratio was about 20dB. In 2010, Itsunari Yamada et al. from Shiga University in Japan [Optics Letters, 2010, 35(18): 3111-3113.] used double-beam interference lithography and dry etching to achieve sub-wavelength metal grating polarization devices with a period of 800~1000nm and a line width of 285~296nm. A tungsten silicide metal grating array with ceramic as the substrate was prepared, with a structural period of 350nm and a line width of 175nm. The experimentally measured TM transmittance exceeded 70% in the 8~10μm band, and the transmission performance was greatly improved.

[0005] Although the above two single-layer sub-wavelength metal gratings have simple structures, due to the limited number of adjustable parameters, they can only meet the requirements of high polarization performance by reducing the structural period and increasing the height of the metal grating, which will increase the difficulty of processing. In 2019, Jie Xia et al. from Soochow University [OSA Continuum, 2019, 2(5): 1683-1692.] used extreme ultraviolet lithography and thin film deposition technology to deposit barium fluoride ( ), zinc sulfide (ZnS) dielectric layer and aluminum (Al) metal layer, and developed a multilayer metal-dielectric grating structure with a structural period of 250nm and a line width of 130nm. The experimentally measured TM transmittance is over 80% in the 8~12μm band, and the extinction ratio is over 35dB. Compared with the single-layer subwavelength metal grating, the subwavelength metal-dielectric composite grating has expanded the optimization space and customization range of the optical performance of the polarization device by increasing the optimization parameters, but the selected substrate and coating materials have the disadvantages of being hygroscopic, easily susceptible to moisture, highly toxic and soft, which makes it difficult to meet the usage requirements of certain scenarios.

[0006] In addition, the above-mentioned sub-wavelength metal grating polarization devices all exhibit sub-micron or even nanometer line width structures. In the process of electron beam lithography, there are disadvantages of complex preparation procedures, high manufacturing costs and low efficiency, which limits the low-cost, large-area and batch manufacturing of sub-wavelength metal grating structures, and it is difficult to meet the actual application requirements of polarization imaging. Therefore, the present invention aims to obtain excellent polarization performance while reducing the difficulty of micro-nano processing technology, so as to realize large-area, high-fidelity and high-efficiency manufacturing of sub-wavelength metal grating polarization device structures. Summary of the invention

[0007] The technical problem to be solved by the present invention is how to reduce the difficulty of micro-nano processing while obtaining excellent polarization performance, and how to achieve large-area, high-fidelity and high-efficiency manufacturing of sub-wavelength metal grating polarization device structures. In order to overcome the defects of the above-mentioned prior art (or related technology), the present invention provides a sub-wavelength metal grating polarization device structure and a wafer-level manufacturing method thereof.

[0008] The present invention provides a sub-wavelength metal grating polarization device structure, comprising:

[0009] a base;

[0010] a first dielectric layer, deposited on the top of the substrate;

[0011] a second dielectric layer, deposited on top of the first dielectric layer;

[0012] A plurality of dielectric grating layers are deposited on the top of the second dielectric layer and are spaced apart along the length direction of the second dielectric layer, a groove is formed between each two adjacent dielectric grating layers, the material of each dielectric grating layer and the second dielectric layer has the same refractive index, and the grating period of each dielectric grating layer is smaller than the incident wavelength of the incident light;

[0013] A plurality of first metal layers are deposited in each of the grooves respectively;

[0014] A plurality of second metal layers are respectively deposited on the top of each of the dielectric grating layers, and the material of each of the second metal layers and each of the first metal layers has the same dielectric constant.

[0015] Compared with the prior art, the sub-wavelength metal grating polarization device structure of the present invention has the following advantages:

[0016] In the present invention, a first dielectric layer, a second dielectric layer, a dielectric grating layer and a second metal layer are sequentially deposited on a substrate from bottom to top, and the first metal layer is deposited in the grooves between the dielectric grating layers, wherein the first dielectric layer is used to realize transmission enhancement of a working band of a sub-wavelength metal grating polarization device structure, the second dielectric layer is used to improve the TM transmittance and extinction ratio of the sub-wavelength metal grating polarization device structure, the first metal layer is used to improve the polarization performance of the sub-wavelength metal grating polarization device structure, the second metal layer is used to realize polarization modulation of incident light, and the materials of the dielectric grating layer and the second dielectric layer have the same refractive index, the grating period of the dielectric grating layer is smaller than the incident wavelength of the incident light, and then based on the stacking deposition method of the first dielectric layer, the second dielectric layer, the dielectric grating layer and the second metal layer, micro-nano processing is conveniently performed, thereby achieving excellent polarization performance while reducing the difficulty of micro-nano processing technology.

[0017] In a possible implementation manner, the thickness of the first dielectric layer satisfies the following expression:

[0018] ;

[0019] in,

[0020] represents the thickness of the first dielectric layer;

[0021] Indicates the wavelength of the incident light anti-reflection band;

[0022] represents the refractive index of the first dielectric layer.

[0023] In a possible implementation, another technical solution of the present invention is to provide a wafer-level manufacturing method of a sub-wavelength metal grating polarization device structure, which is applied to the above-mentioned sub-wavelength metal grating polarization device structure, comprising the following steps:

[0024] Step S1, selecting a substrate with high flatness, soaking the substrate in an acetone solution and anhydrous ethanol in sequence, then spraying it with deionized water and blowing it dry with nitrogen;

[0025] Step S2, placing the substrate in a material deposition device, and depositing a first dielectric layer on the top of the substrate;

[0026] Step S3, depositing a second dielectric layer on top of the first dielectric layer in the material deposition equipment;

[0027] Step S4, transferring the substrate obtained in step S3 to a spin coater, performing spin coating of photoresist at a preset speed within a preset spin coating time, and then placing the substrate on a hot plate to heat bake the film to cure the photoresist;

[0028] Step S5, transferring the substrate obtained in step S4 to a photolithography device, exposing it according to a pre-configured layout pattern, placing the exposed substrate in a developer for development, and cleaning the developed substrate with isopropanol and then drying it with nitrogen to obtain a periodic sub-wavelength grating array structure;

[0029] Step S6, placing the periodic sub-wavelength grating array structure obtained in step S5 in a material deposition device or an etching device to obtain a dielectric grating layer;

[0030] Step S7, immersing the substrate obtained in step S6 in an acetone solution, and transferring it to a water bath sonicator for sonication, taking it out and soaking it in anhydrous ethanol, and spraying it with deionized water to remove residual photoresist, and then drying it with nitrogen gas;

[0031] Step S8, placing the substrate obtained in step S7 in the material deposition equipment, and continuously depositing metal material to obtain the first metal layer and the second metal layer to form the sub-wavelength metal grating polarization device structure.

[0032] Compared with the prior art, the wafer-level manufacturing method of a sub-wavelength metal grating polarization device structure of the present invention has the following advantages:

[0033] In the present invention, a substrate is selected and processed through step S1, a first dielectric layer is deposited through step S2, a second dielectric layer is deposited through step S3, a photoresist is spin-coated and solidified through step S4, an exposure and development process is performed through step S5, a dielectric grating layer is deposited through steps S6 and S7, and a first metal layer and a second metal layer are deposited through step S8, thereby increasing the minimum line width of a sub-wavelength metal grating polarization device structure, reducing the difficulty of processing, meeting the use requirements of polarization imaging, and realizing large-area, high-fidelity, and high-efficiency manufacturing of a sub-wavelength metal grating polarization device structure.

[0034] In a possible implementation, in step S1, the material of the substrate selected is one of glass, quartz, silicon, zinc sulfide, barium fluoride, and germanium.

[0035] Compared with the existing technology, the above technical solution can provide the substrate with material options of visible light band materials and infrared band materials. The visible light band materials are glass and quartz, and the infrared band materials are silicon, zinc sulfide, barium fluoride, and germanium, so as to meet the transmission within the target working band range.

[0036] In a possible implementation, in step S2 and step S7, the material deposition equipment used is an electron beam evaporation coating machine, a magnetron sputtering apparatus, or an atomic layer deposition equipment.

[0037] In a possible implementation, in step S5, the photolithography equipment used is an ultraviolet photolithography machine, a stepper photolithography machine, an electron beam photolithography machine, or a laser direct writing photolithography machine.

[0038] In a possible implementation, step S6 includes:

[0039] Step S61, determining whether the thickness of the second dielectric layer is greater than a preset threshold:

[0040] If yes, go to step S62;

[0041] If not, go to step S63;

[0042] Step S62, placing the periodic sub-wavelength grating array structure obtained in step S5 in the etching device, and etching the second dielectric layer through a pre-configured mask to obtain the dielectric grating layer;

[0043] Step S63, placing the periodic sub-wavelength grating array structure obtained in step S5 in the material deposition device, and continuously depositing high refractive index material to obtain the dielectric grating layer.

[0044] Compared with the prior art, the above technical solution can use the thickness of the second dielectric layer as a reference, and select different dielectric grating layer preparation steps by comparing with a preset threshold, thereby providing diverse selectivity.

[0045] In a possible implementation, in step S62, the etching equipment used is a RIE etcher or an ICP etcher. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention;

[0047] Figure 2 It is a two-dimensional cross-sectional schematic diagram of the present invention;

[0048] Figure 3 is a flow chart of the method steps of the present invention;

[0049] Figure 4 This is a first manufacturing process flow chart of the present invention;

[0050] Figure 5 This is a second manufacturing process flow chart of the present invention;

[0051] Figure 6 It is a TM transmittance curve and extinction ratio curve of the sub-wavelength metal grating polarization device structure of the present invention;

[0052] Explanation of the reference numerals: 1. substrate; 2. first dielectric layer; 3. second dielectric layer; 4. dielectric grating layer; 5. first metal layer; 6. second metal layer; 7. photoresist. DETAILED DESCRIPTION

[0053] First, those skilled in the art should understand that these implementations are only used to explain the technical principles of the embodiments of the present invention, and are not intended to limit the protection scope of the embodiments of the present invention. Those skilled in the art can make adjustments to them as needed to adapt to specific application scenarios.

[0054] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0055] See also Figure 1 and Figure 2The embodiment of the present invention discloses a sub-wavelength metal grating polarization device structure, which mainly includes a substrate 1, a first dielectric layer 2, a second dielectric layer 3, a dielectric grating layer 4, a first metal layer 5, and a second metal layer 6 from bottom to top, wherein the substrate 1 is located at the bottom of the structure, and is used to support the first dielectric layer 2, the second dielectric layer 3, the dielectric grating layer 4, the first metal layer 5, and the second metal layer 6; the first dielectric layer 2 is on the top of the substrate 1, and is used to achieve transmission enhancement in the working band of the sub-wavelength metal grating polarization device structure; the second dielectric layer 3 is on the top of the first dielectric layer 2, and is used to improve the TM transmittance and extinction ratio of the polarization device; the dielectric light The grating layer 4 is on top of the second dielectric layer 3 and has the same refractive index as the material of the second dielectric layer 3. It is arranged at periodic intervals to form ridges and grooves with a fixed period and a fixed duty cycle with the spatial medium in which it is located, and the grating period is smaller than the incident wavelength. The first metal layer 5 is in the groove of the dielectric grating layer 4 and has the same groove width as the dielectric grating layer 4, so as to improve the polarization performance of the sub-wavelength metal grating polarization device structure. The second metal layer 6 is on the ridge of the dielectric grating layer 4 and has the same dielectric constant as the material of the first metal layer 5 and the same ridge width as the dielectric grating layer 4, so as to realize polarization modulation of the incident light field.

[0056] Continue to see Figure 2 In this embodiment, the substrate 1 is a six-inch double-polished zone-melted high-resistance silicon wafer with a thickness of 500 μm.

[0057] Continue to see Figure 2 The substrate 1 can be glass, quartz and other materials for visible light band, or silicon (Si), zinc sulfide (ZnS), barium fluoride ( ), germanium (Ge), etc., which are infrared-band materials, are used to meet the transmission within the target working band.

[0058] Continue to see Figure 2 The material of the first dielectric layer 2 can be silicon oxide (SiO), silicon nitride ( ) and other visible light band materials, or zinc selenide (ZnSe), barium fluoride ( )、Calcium Fluoride( )、Magnesium fluoride( ) and zinc sulfide (ZnS) and other low refractive index materials in the infrared light band; the thickness of the first dielectric layer 2 The selection is related to the central wavelength position of the polarization device. According to the refractive index n of the selected first dielectric layer 2 and the requirements of the anti-reflection band λ, the thickness of the first dielectric layer 2 satisfy: =λ / 4n.

[0059] Continue to see Figure 2In this embodiment, the material of the first dielectric layer 2 is zinc sulfide (ZnS) according to the use scenario requirements and the selection of the substrate 1; the thickness of the first dielectric layer 2 is According to the selected refractive index n=2.2 of the first dielectric layer 2 and the anti-reflection band λ=10μm, the thickness of the first dielectric layer 2 is Set to =1.14μm.

[0060] Continue to see Figure 2 The second dielectric layer 3 is made of a high refractive index material, mainly including titanium oxide ( )、Tantalum pentoxide( ), silicon (Si), germanium (Ge), etc.; the thickness of the second dielectric layer 3 The choice of thickness is related to the central wavelength position, polarization performance, modulation function, etc. of the polarization device. Different thicknesses can be set to correspond to different band ranges and performance requirements. .

[0061] Continue to see Figure 2 In this embodiment, the second dielectric layer 3 is made of a high refractive index material, which is germanium (Ge). The thickness of the second dielectric layer 3 is The choice of is related to the central wavelength position, polarization performance, modulation function, etc. of the polarization device. =500nm.

[0062] Continue to see Figure 2 The dielectric grating layer 4 is made of the same material as the second dielectric layer 3; the period Λ and height of the dielectric grating layer 4 The choice of is related to the working wavelength, polarization performance, modulation function and processing difficulty of the polarization device. Different periods Λ and heights can be set to correspond to different band ranges and performance requirements. The width of the dielectric grating layer 4 can be defined by the duty cycle f, which determines the optical field coupling distance between adjacent ridges of the dielectric grating layer 4 and directly determines the minimum line width in the micro-nano processing process. Different widths Λ*f can be set to correspond to different performance requirements and processing capabilities.

[0063] Continue to see Figure 2 In this embodiment, the period Λ=2.6μm and the height =500nm; the width of the dielectric grating layer 4 can be defined by the duty cycle f, and the duty cycle f is set to 0.5.

[0064] Continue to see Figure 2The first metal layer 5 and the second metal layer 6 are made of the same material, which is mainly one of conductive metal materials such as gold (Au), silver (Ag), aluminum (Al) and copper (Cu). The TM transmittance is increased and the TE wave transmittance is greatly reduced under the action of metal surface plasmons excited at the air / metal interface and the metal / medium interface, thereby realizing polarization characteristic modulation; the resonance peak corresponding to the Fabry-Perot resonant cavity mode in the TM transmission spectrum increases with the thickness of the first metal layer 5 and the second metal layer 6. As the thickness increases, the red shift is linear, and the extinction ratio gradually increases. However, this will cause the depth-to-width ratio of the structure to be too large, increasing the difficulty of device manufacturing. Different thicknesses can be set by comprehensively considering processing feasibility and performance requirements. .

[0065] Continue to see Figure 2 In this embodiment, the material of the first metal layer 5 and the second metal layer 6 is selected as a gold (Au) conductive metal material, and the thickness is set by comprehensively considering the processing feasibility and performance requirements. =100nm.

[0066] Continue to see Figure 3 In step S6, comparing the thickness of the second dielectric layer 3 with the preset threshold value can point to two different dielectric grating layer preparation processes, or placing the periodic sub-wavelength grating array structure obtained in step S5 in an etching device, and etching the second dielectric layer 3 through a pre-configured mask to obtain a dielectric grating layer 4; or placing the periodic sub-wavelength grating array structure obtained in step S5 in a material deposition device, and continuously depositing a high refractive index material to obtain a dielectric grating layer 4; and the specific value of the preset threshold value is .

[0067] See also Figure 3 and Figure 4 In order to achieve high-quality processing and manufacturing of the proposed sub-wavelength metal grating polarization device structure, the second object of the present invention is to provide a wafer-level manufacturing method for the sub-wavelength metal grating polarization device structure, which specifically includes the following steps:

[0068] Step S1, substrate 1 treatment: see Figure 4 In (a), a substrate 1 with high flatness is selected, and it is immersed in an acetone solution and anhydrous ethanol respectively, then sprayed with deionized water, and finally dried with nitrogen gas;

[0069] Step S2, depositing a first dielectric layer 2: see Figure 4 In (b), the treated substrate 1 is placed in a material deposition equipment chamber, and the deposition thickness is A low refractive index material is used to make the first dielectric layer 2;

[0070] Step S3, depositing the second dielectric layer 3: see Figure 4 (c) in the above, placing the substrate in a material deposition equipment chamber, and depositing a thickness of The second dielectric layer 3 is made of a high refractive index material;

[0071] Step S4, spin coating photoresist 7: see Figure 4 In (d), the substrate is placed on a spin coater, the rotation speed and the spin coating time are set, the photoresist 7 is spin coated, and then the substrate is placed on a hot plate for heat baking to cure the photoresist 7;

[0072] Among them, photoresist 7 can choose EPI680 positive photoresist, S1813 positive photoresist, HTIN160 negative photoresist, etc.

[0073] Step S5, exposure and development: see Figure 4 In (e), the substrate is placed in a photolithography equipment chamber, and the exposure parameters such as exposure dose are set, and the exposure is completed according to the pre-designed layout pattern; then the substrate is placed in a developer for development, and is cleaned with isopropanol, and finally the sample is blown dry with nitrogen to obtain a periodic sub-wavelength grating array structure;

[0074] Step S6, depositing dielectric grating layer 4: see Figure 4 In (f), the above substrate is placed in the chamber of the material deposition equipment, and the deposition thickness is A high refractive index material is used to make a dielectric grating layer 4;

[0075] Step S7, stripping process: see Figure 4 In (g), the substrate is immersed in an acetone solution, placed in a water bath ultrasonicator for ultrasonic treatment, taken out and soaked in anhydrous ethanol, then sprayed with deionized water to remove the residual photoresist 7, and finally dried with nitrogen to produce a dielectric grating layer 4;

[0076] Step S8, depositing the first metal layer 5 and the second metal layer 6: see Figure 4 (h) in the figure, the above substrate is placed in the chamber of the material deposition equipment, and the deposition thickness is The metal material is used to produce and deposit the first metal layer 5 and the second metal layer 6.

[0077] See also Figure 3 and Figure 5 The present invention provides a second wafer-level manufacturing method for a sub-wavelength metal grating polarization device structure, which specifically comprises the following steps:

[0078] Step S1, substrate 1 treatment: see Figure 5 In (a), a substrate 1 with high flatness is selected, and it is immersed in an acetone solution and anhydrous ethanol respectively, then sprayed with deionized water, and finally dried with nitrogen gas;

[0079] Step S2, depositing a first dielectric layer 2: see Figure 5 In (b), the treated substrate 1 is placed in a material deposition equipment chamber, and the deposition thickness is A low refractive index material is used to make the first dielectric layer 2;

[0080] Step S3, depositing the second dielectric layer 3: see Figure 5 (c) in the above, placing the substrate in a material deposition equipment chamber, and depositing a thickness of + The second dielectric layer 3 is made of a high refractive index material;

[0081] Step S4, spin coating photoresist 7: see Figure 5 In (d), the substrate is placed on a spin coater, the rotation speed and the spin coating time are set, the photoresist 7 is spin coated, and then the substrate is placed on a hot plate for heat baking to cure the photoresist 7;

[0082] Step S5, exposure and development: see Figure 5 In (e), the substrate is placed in a photolithography equipment chamber, and the exposure parameters such as exposure dose are set, and the exposure is completed according to the pre-designed layout pattern; then the substrate is placed in a developer for development, and is cleaned with isopropanol, and finally the sample is blown dry with nitrogen to obtain a periodic sub-wavelength grating array structure;

[0083] Step S6, etching: see Figure 5 In (f), the substrate is placed in the chamber of the etching equipment, and the second dielectric layer 3 is etched with a mask to a depth of ;

[0084] Step S7, glue removal: see Figure 5 In (g), the substrate is immersed in an acetone solution, placed in a water bath ultrasonicator for ultrasonic treatment, taken out and soaked in anhydrous ethanol, then sprayed with deionized water to remove the residual photoresist 7, and finally dried with nitrogen to produce a dielectric grating layer 4;

[0085] Step S8, depositing the first metal layer 5 and the second metal layer 6: see Figure 5 (h) in the figure, the above substrate is placed in the chamber of the material deposition equipment, and the deposition thickness is The metal material is used to produce and deposit the first metal layer 5 and the second metal layer 6.

[0086] See also Figure 6 , the period of production is Λ=2.6μm, =1.14μm, =500nm, =500nm, =100nm sub-wavelength metal grating infrared polarization device has a TM peak transmittance of more than 80% in the 8-12μm band, a spectral line half-width of about 1.3μm, and an extinction ratio in the band corresponding to the bandwidth better than 20dB, which meets the needs of polarization imaging. In addition, compared with the prior art, the structure and processing method proposed in this embodiment not only greatly improve the TM transmission performance, but also increase the minimum line width of the polarization device structure and reduce the difficulty of processing; it can meet the needs of polarization imaging, and at the same time, the structural line width is increased by 10 times, which can realize large-area, high-fidelity and high-efficiency manufacturing of polarization devices.

[0087] Embodiment 1

[0088] A first wafer-level manufacturing method for a sub-wavelength metal grating polarization device structure is provided, which specifically comprises the following steps:

[0089] Step S1, substrate 1 treatment: see Figure 4 In (a), a high-flatness substrate 1 of a six-inch double-polished zone-melted high-resistance silicon wafer (Si) with a thickness of 500 μm is selected, ultrasonically cleaned in an acetone solution for 5 minutes, then ultrasonically cleaned in anhydrous ethanol for 5 minutes, then rinsed with deionized water, and finally dried with nitrogen gas;

[0090] Step S2, depositing a first dielectric layer 2: see Figure 4 In (b), the treated substrate 1 is placed in the chamber of the electron beam evaporation coating equipment, the material is selected as zinc sulfide (ZnS), and the vacuum degree of the chamber is maintained at The deposition rate is set to 1 nm / s, the deposition thickness is 1.14 μm, and the production thickness is =1.14μm first dielectric layer 2;

[0091] Step S3, depositing the second dielectric layer 3: see Figure 4 In (c), the substrate is placed in the chamber of an electron beam evaporation coating device, the material is germanium (Ge), and the vacuum degree of the chamber is maintained at The deposition rate is set to 0.5nm / s, the deposition thickness is 500nm, and the thickness is = 500nm second dielectric layer 3;

[0092] Step S4, spin coating photoresist 7: see Figure 4 In (d), the substrate is placed on a spin coater, a negative photoresist of model HTIN160 is selected, the rotation speed is set to 5000 rpm and the spin coating time is set to 30 seconds, the photoresist 7 is spin-coated, and then the substrate is placed on a hot plate at 110° C. for 2 minutes to heat the film and cure the photoresist 7;

[0093] Step S5, exposure and development: see Figure 4In (e), the substrate is placed in the chamber of a SUSS UV lithography machine model MA8 / BA8 and the exposure dose is set. The parameters are set and the exposure is completed according to the pre-designed layout pattern; the substrate is then placed in a developer for 90 to 92 seconds, and is cleaned with isopropanol. Finally, the sample is blown dry with nitrogen to obtain a periodic sub-wavelength grating array structure;

[0094] Step S6, depositing dielectric grating layer 4: see Figure 4 In (f), the substrate is placed in the chamber of an electron beam evaporation coating device, the material is germanium (Ge), and the vacuum degree of the chamber is maintained at The deposition rate is set to 0.5nm / s, the deposition thickness is 500nm, and the thickness is =500nm dielectric grating layer 4;

[0095] Step S7, stripping process: see Figure 4 In (g), the substrate is immersed in an acetone solution, placed in a water bath sonicator for 10 minutes of sonication, taken out and soaked in anhydrous ethanol, then sprayed with deionized water to remove the residual photoresist 7, and finally dried with nitrogen to produce a dielectric grating layer 4;

[0096] Step S8, depositing the first metal layer 5 and the second metal layer 6: see Figure 4 In (h), the substrate is placed in the chamber of an electron beam evaporation coating device, the material is gold (Au), and the vacuum degree of the chamber is maintained at The deposition rate is set to 0.1nm / s, the deposition thickness is 100nm, and the thickness is =100nm of the first metal layer 5 and the second metal layer 6.

[0097] Embodiment 2

[0098] A second wafer-level manufacturing method for a sub-wavelength metal grating polarization device structure is provided, which specifically comprises the following steps:

[0099] Step S1, substrate 1 treatment: see Figure 5 In (a), a high-flatness substrate 1 of a six-inch double-polished zone-melted high-resistance silicon wafer (Si) with a thickness of 500 μm is selected, ultrasonically cleaned in an acetone solution for 5 minutes, then ultrasonically cleaned in anhydrous ethanol for 5 minutes, then rinsed with deionized water, and finally dried with nitrogen gas;

[0100] Step S2, depositing a first dielectric layer 2: see Figure 5 In (b), the treated substrate 1 is placed in the chamber of the electron beam evaporation coating equipment, the material is selected as zinc sulfide (ZnS), and the vacuum degree of the chamber is maintained at The deposition rate is set to 1 nm / s, the deposition thickness is 1.14 μm, and the production thickness is =1.14μm first dielectric layer 2;

[0101] Step S3, depositing the second dielectric layer 3: see Figure 5 In (c), the substrate is placed in the chamber of an electron beam evaporation coating device, the material is germanium (Ge), and the vacuum degree of the chamber is maintained at The deposition rate is set to 0.5 nm / s, the deposition thickness is 1 μm, and the thickness is + =1μm second dielectric layer 3 and dielectric grating layer 4;

[0102] Step S4, spin coating photoresist 7: see Figure 5 In (d), the substrate is placed on a spin coater, and a positive photoresist of model EPI680 is selected. The rotation speed is set to 5000 rpm and the spin coating time is set to 30 s. The photoresist 7 is spin-coated, and then the substrate is placed on a hot plate at 110° C. for 2 min to cure the photoresist 7.

[0103] Step S5, exposure and development: see Figure 5 In (e), the substrate is placed in the chamber of a SUSS UV lithography machine model MA8 / BA8 and the exposure dose is set. The parameters are set and the exposure is completed according to the pre-designed layout pattern; the substrate is then placed in a developer for 90 to 92 seconds, and is cleaned with isopropanol. Finally, the sample is blown dry with nitrogen to obtain a periodic sub-wavelength grating array structure;

[0104] Step S6, etching: see Figure 5 In (f), the substrate is placed in a chamber of an RIE etcher, and the second dielectric layer 3 is etched using a periodic sub-wavelength grating array structure as a mask, with an etching depth of 500 nm;

[0105] Step S7, glue removal: see Figure 5 In (g), the substrate is immersed in an acetone solution, placed in a water bath sonicator for 10 minutes of sonication, taken out and soaked in anhydrous ethanol, then sprayed with deionized water to remove the residual photoresist 7, and finally dried with nitrogen to produce a dielectric grating layer 4;

[0106] Step S8, depositing the first metal layer 5 and the second metal layer 6: see Figure 5 In (h), the substrate is placed in the chamber of an electron beam evaporation coating device, the material is gold (Au), and the vacuum degree of the chamber is maintained at The deposition rate is set to 0.1nm / s, the deposition thickness is 100nm, and the thickness is =100nm of the first metal layer 5 and the second metal layer 6.

[0107] In the description of the present invention, the description with reference to the terms "one embodiment", "some embodiments", "in the present embodiment", "specific example", or "some examples" etc. means that the specific features, mechanisms, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, mechanisms, materials or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0108] It should be pointed out that the above embodiments are intended to provide further explanation of the present invention in conjunction with the accompanying drawings. The technical solution proposed in the present invention is not only applicable to long-wave polarization devices, but can also be extended to polarization devices in working bands such as visible light, near-infrared and medium-wave infrared. On this basis, any improvements and equivalent substitutions made are within the protection scope of the present invention.

[0109] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A sub-wavelength metal grating polarization device structure, characterized in that: include: a base (1); a first dielectric layer (2) deposited on the top of the substrate (1), the first dielectric layer (2) being made of a low refractive index material, and the first dielectric layer (2) being used to enhance the transmission of the working band of the sub-wavelength metal grating polarization device structure; a second dielectric layer (3) deposited on the top of the first dielectric layer (2), the second dielectric layer (3) being made of a high refractive index material, and the second dielectric layer (3) being used to improve the TM transmittance and extinction ratio of the sub-wavelength metal grating polarization device structure; A plurality of dielectric grating layers (4) are deposited on the top of the second dielectric layer (3) and are spaced apart along the length direction of the second dielectric layer (3), a groove is formed between each two adjacent dielectric grating layers (4), the top of each dielectric grating layer (4) is a ridge, the material of each dielectric grating layer (4) and the second dielectric layer (3) has the same refractive index, and the grating period of each dielectric grating layer (4) is smaller than the incident wavelength of the incident light; A plurality of first metal layers (5), respectively deposited in each of the grooves and having the same width as the grooves, for improving the polarization performance of the sub-wavelength metal grating polarization device structure; A plurality of second metal layers (6), respectively deposited on the ridges of each of the dielectric grating layers (4) and having the same width as the ridges, wherein the materials of each of the second metal layers (6) and each of the first metal layers (5) have the same dielectric constant and are used for polarization modulation of an incident light field; The thickness of the first dielectric layer (2) satisfies the following expression: ； in, Indicates the thickness of the first dielectric layer (2); Indicates the wavelength of the incident light anti-reflection band; represents the refractive index of the first medium layer (2).

2. A wafer-level manufacturing method for a sub-wavelength metal grating polarization device structure, characterized in that: The sub-wavelength metal grating polarization device structure applied to claim 1 comprises the following steps: Step S1, selecting a substrate (1) with high flatness, soaking the substrate (1) in an acetone solution and anhydrous ethanol in sequence, then spraying with deionized water and drying with nitrogen; Step S2, placing the substrate (1) in a material deposition device, and depositing a first dielectric layer (2) on the top of the substrate (1); Step S3, depositing a second dielectric layer (3) on top of the first dielectric layer (2) in the material deposition device; Step S4, transferring the substrate obtained in step S3 to a spin coater, spin coating the photoresist (7) at a preset rotation speed within a preset spin coating time, and then placing the substrate on a hot plate to heat bake the film to cure the photoresist (7); Step S5, transferring the substrate obtained in step S4 to a photolithography device, exposing it according to a pre-configured layout pattern, placing the exposed substrate in a developer for development, and cleaning the developed substrate with isopropanol and then drying it with nitrogen to obtain a periodic sub-wavelength grating array structure; Step S6, placing the periodic sub-wavelength grating array structure obtained in step S5 in a material deposition device or an etching device to produce a dielectric grating layer (4); Step S7, immersing the substrate obtained in step S6 in an acetone solution, and transferring it to a water bath sonicator for sonication, taking it out and soaking it in anhydrous ethanol, and spraying it with deionized water to remove the residual photoresist (7), and then drying it with nitrogen gas; Step S8, placing the substrate obtained in step S7 in the material deposition device, and continuously depositing metal material to obtain the first metal layer (5) and the second metal layer (6), so as to form the sub-wavelength metal grating polarization device structure.

3. The wafer-level manufacturing method of the sub-wavelength metal grating polarization device structure according to claim 2, characterized in that: In the step S1, the material of the substrate (1) is selected to be one of glass, silicon, zinc sulfide, barium fluoride and germanium.

4. The wafer-level manufacturing method of the sub-wavelength metal grating polarization device structure according to claim 2, characterized in that: In the step S2 and the step S6, the material deposition equipment used is an electron beam evaporation coating machine, a magnetron sputtering apparatus, or an atomic layer deposition equipment.

5. The wafer-level manufacturing method of the sub-wavelength metal grating polarization device structure according to claim 2, characterized in that: In the step S5, the photolithography equipment used is an ultraviolet photolithography machine, a stepper photolithography machine, an electron beam photolithography machine, or a laser direct writing photolithography machine.

6. The wafer-level manufacturing method of the sub-wavelength metal grating polarization device structure according to claim 2, characterized in that: The step S6 comprises: Step S61, determining whether the thickness of the second dielectric layer (3) is greater than a preset threshold: If yes, go to step S62; If not, go to step S63; Step S62, placing the periodic sub-wavelength grating array structure obtained in step S5 in the etching device, and etching the second dielectric layer (3) through a pre-configured mask to obtain the dielectric grating layer (4); Step S63, placing the periodic sub-wavelength grating array structure obtained in step S5 in the material deposition device, and continuously depositing high refractive index material to obtain the dielectric grating layer (4).

7. The wafer-level manufacturing method of the sub-wavelength metal grating polarization device structure according to claim 6, characterized in that: In the step S62, the etching equipment used is a RIE etcher or an ICP etcher.

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