Metal auxiliary chemical etching method and equipment based on three-dimensional magnetic field guidance

Abstract

The invention discloses a metal-assisted chemical etching method and equipment based on three-dimensional magnetic field guidance. The etching method comprises the steps of pre-cleaning, adding a metal catalytic material, soaking in an erosion liquid, placing in a magnetic field guidance erosion device, performing three-dimensional magnetic field guidance erosion, performing post-treatment and the like. According to the metal-assisted chemical etching method, the controllable magnetic field is generated through the three-dimensional Helmholtz coil, so that the motion trail of the metal catalytic material in the metal-assisted chemical etching process is accurately restrained and controlled, the controllability and accuracy of the etching process can be remarkably improved, and manufacturing of a complex micro-nano structure becomes more efficient. In addition, by adjusting the direction and strength of the magnetic field, the processing rate of the metal catalytic material is effectively increased. Through the magnetic guiding effect, the metal catalytic material can be etched in the preset direction, the consistency and directivity of an etching track are ensured, and a microscopic three-dimensional structure with a specific shape and size is manufactured.

Description

Technical Field

[0001] The present invention relates to the field of chemical etching, and in particular to a metal-assisted chemical etching method and equipment based on three-dimensional magnetic field guidance. Background Art

[0002] Metal assisted chemical etching (MACE) is a key technology for preparing micro-nano structures. Its principle is to deposit micrometer or nanometer-scale metal catalytic particles or films, such as gold, silver and other metals, on the surface of the substrate, and use these metal catalysts to induce local chemical reactions in the corrosive solution, thereby selectively etching the substrate material.

[0003] In the process of metal-assisted chemical etching, the movement path of the metal catalyst is crucial to ensure the accuracy, rate and directionality of etching. However, the existing technology lacks effective control means to manage the movement trajectory of the metal catalyst. If the path of the metal catalyst cannot be precisely controlled, it may lead to poor etching directionality, low rate and unevenness, making the manufacture of complex structures difficult. Summary of the invention

[0004] The purpose of the present invention is to provide a metal-assisted chemical etching method and equipment based on three-dimensional magnetic field guidance to solve the above-mentioned problems of poor etching directionality, low rate and unevenness.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] The present invention provides a metal-assisted chemical etching method based on three-dimensional magnetic field guidance, comprising the following steps:

[0007] Pre-cleaning: Use organic solvent to clean the base material and dry it;

[0008] Adding metal catalytic material: adding metal catalytic material to the surface of the base material to obtain the material to be etched;

[0009] Soak in etching solution: put the material to be etched into a container filled with etching solution;

[0010] Placing in a magnetic field guided etching device: placing a container containing a material to be etched and an etching liquid in an etching area of ​​a three-dimensional Helmholtz coil frame, wherein the three-dimensional Helmholtz coil frame comprises an X-axis coil, a Y-axis coil and a Z-axis coil, wherein the X-axis coil is used to generate a magnetic field in an X-axis direction, the Y-axis coil is used to generate a magnetic field in a Y-axis direction, and the Z-axis coil is used to generate a magnetic field in a Z-axis direction;

[0011] Three-dimensional magnetic field guided erosion: after waiting for a preset time, current is passed through one or two of the X-axis coil, Y-axis coil and Z-axis coil according to process requirements. Under the synergistic effect of the X-axis coil, Y-axis coil and Z-axis coil, a magnetic field in the corresponding direction is generated to control the metal catalytic material to move in the corresponding direction, so as to electrochemically corrode the material to be etched and obtain the etched material;

[0012] Post-processing: The etched material is taken out, rinsed with deionized water, and then dried to obtain a base material with a three-dimensional etched structure.

[0013] In the metal-assisted chemical etching method based on three-dimensional magnetic field guidance, in the step of three-dimensional magnetic field guidance etching, the etching time is 15 to 25 minutes and the etching temperature is 22 to 27°C.

[0014] In the metal-assisted chemical etching method based on three-dimensional magnetic field guidance, in the three-dimensional magnetic field guided erosion step, the current passed through one or two of the X-axis coil, Y-axis coil and Z-axis coil is 1 to 30A; the magnetic induction intensity of the X-axis coil is 6.8 to 200Gs; the magnetic induction intensity of the Y-axis coil is 7.3 to 200Gs; and the magnetic induction intensity of the Z-axis coil is 50.6 to 200Gs.

[0015] In the metal-assisted chemical etching method guided by a three-dimensional magnetic field, the etching solution comprises, by weight percentage, 40-48% HF, 9-12% H2O2 and 42-50% deionized water.

[0016] In the metal-assisted chemical etching method based on three-dimensional magnetic field guidance, in the pre-cleaning step, the following steps are included:

[0017] The substrate material is immersed in toluene and ultrasonically cleaned for 28 to 32 minutes, then the substrate material is taken out and rinsed with deionized water;

[0018] The substrate material is immersed in acetone and ultrasonically cleaned for 28 to 32 minutes, then the substrate material is taken out and rinsed with deionized water;

[0019] The substrate material is immersed in anhydrous ethanol and ultrasonically cleaned for 28 to 32 minutes, then the substrate material is taken out and rinsed with deionized water;

[0020] Dry the base material in an environment of 98-100°C.

[0021] In the metal-assisted chemical etching method based on three-dimensional magnetic field guidance, in the step of adding metal catalytic material, the following steps are included:

[0022] Prepare Ni@SiO2 with a concentration of 0.5 mg / ml or NiSi@SiO2 solution with a concentration of 0.5 mg / ml;

[0023] Coating Ni@SiO2 or NiSi@SiO2 solution on the surface of the substrate material;

[0024] The Ni@SiO2 or NiSi@SiO2 solution on the surface of the base material is dried to make the Ni@SiO2 or NiSi@SiO2 attached to the surface of the base material.

[0025] In the metal-assisted chemical etching method based on three-dimensional magnetic field guidance, in the pre-cleaning step, the following steps are included:

[0026] Soak the substrate material in acetone for 5 to 15 minutes, then take out the substrate material and rinse it with deionized water;

[0027] Soak the substrate material in anhydrous ethanol for 5 to 15 minutes, then take out the substrate material and rinse it with deionized water;

[0028] Dry the base material in an environment of 98-100°C.

[0029] In the metal-assisted chemical etching method based on three-dimensional magnetic field guidance, in the step of adding metal catalytic material, the following steps are included:

[0030] Coating a photoresist on the surface of the base material to form a PR layer on the surface of the base material;

[0031] Etching the PR layer on the PR layer by photolithography to form a PR groove on the PR layer;

[0032] Depositing Au on the PR layer and the PR groove to form a first catalytic deposition layer;

[0033] Depositing magnetic material on the first catalytic deposition layer to form a magnetic guide layer; the width of the magnetic guide layer is smaller than the width of the first catalytic deposition layer;

[0034] Depositing Au again to fill the gap between the magnetic guide layer and the PR groove and form a second catalytic deposition layer; the width of the first catalytic deposition layer is the same as the width of the second catalytic deposition layer, so that the first catalytic deposition layer and the second catalytic deposition layer wrap the magnetic guide layer to form a metal catalytic material;

[0035] The PR layer is removed, so that the surface of the base material is attached with a metal catalyst material.

[0036] In the metal-assisted chemical etching method based on three-dimensional magnetic field guidance, the deposition thickness of the first catalytic deposition layer, the magnetic guidance layer and the second catalytic deposition layer is 18-25 nm.

[0037] The present invention also provides a metal-assisted chemical etching device based on three-dimensional magnetic field guidance, which is used to implement the above-mentioned metal-assisted chemical etching method based on three-dimensional magnetic field guidance, comprising an X-axis coil, a Y-axis coil and a Z-axis coil, wherein the Y-axis coil is sleeved on the outer periphery of the Z-axis coil, and the X-axis coil is sleeved on the outer periphery of the Y-axis coil; the X-axis coil, the Y-axis coil and the Z-axis coil are respectively provided with connecting posts, and the X-axis coil, the Y-axis coil and the Z-axis coil are respectively connected to an external power supply through the connecting posts;

[0038] The axis of the Z-axis coil is perpendicular to the horizontal line, and the Z-axis coil is provided with a placement platform, and the placement platform is used to place a container containing the material to be etched and the etching liquid.

[0039] A technical solution in the present invention can have the following beneficial effects:

[0040] The metal-assisted chemical etching method generates a controllable magnetic field through a three-dimensional Helmholtz coil to accurately constrain and control the movement trajectory of the metal catalytic material during the metal-assisted chemical etching process, which can significantly improve the controllability and accuracy of the etching process and make the manufacture of complex micro-nano structures more efficient.

[0041] Moreover, the processing rate of metal catalytic materials can be effectively increased by adjusting the direction and intensity of the magnetic field. In the experiment, the processing rate was successfully increased to 3 times the original rate by adjusting the Z-axis current, showing the potential of this method in improving production efficiency.

[0042] In addition, through magnetic guidance, the metal catalytic material can be etched along a predetermined direction, ensuring the consistency and directionality of the etching track and manufacturing a microscopic three-dimensional structure with a specific shape and size. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 is a schematic structural diagram of a metal-assisted chemical etching device in one embodiment of the present invention;

[0044] Figure 2 is a preparation flow chart of one embodiment of the present invention;

[0045] Figure 3 is a preparation flow chart of one embodiment of the present invention;

[0046] In the drawings: X-axis coil 1, Y-axis coil 2, Z-axis coil 3, container 4;

[0047] A placement platform 31 ; Ni particles 50 , a base material 51 , a PR layer 52 , a PR groove 53 , a first catalytic deposition layer 54 , a magnetic guide layer 55 , and a second catalytic deposition layer 56 . DETAILED DESCRIPTION

[0048] The technical scheme of the present invention is further illustrated by specific embodiments below. In order to facilitate understanding of the present invention, the present invention is described more comprehensively below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0049] If no specific techniques or conditions are specified in the examples, the techniques or conditions described in the literature in the field or the product instructions are used. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0050] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0051] The present invention provides a metal-assisted chemical etching method based on three-dimensional magnetic field guidance, comprising the following steps:

[0052] Pre-cleaning: Use organic solvent to clean the base material and dry it;

[0053] Adding metal catalytic material: adding metal catalytic material to the surface of the base material to obtain the material to be etched;

[0054] Soaking in etching liquid: placing the material to be etched into a container 4 filled with etching liquid;

[0055] Placed in a magnetic field guided etching device: placing a container 4 containing a material to be etched and an etching liquid in an etching area of ​​a three-dimensional Helmholtz coil frame, wherein the three-dimensional Helmholtz coil frame comprises an X-axis coil 1, a Y-axis coil 2 and a Z-axis coil 3, wherein the X-axis coil 1 is used to generate a magnetic field in the X-axis direction, the Y-axis coil 2 is used to generate a magnetic field in the Y-axis direction, and the Z-axis coil 3 is used to generate a magnetic field in the Z-axis direction;

[0056] Three-dimensional magnetic field guided erosion: after waiting for a preset time, current is passed through one or two of the X-axis coil 1, Y-axis coil 2 and Z-axis coil 3 according to process requirements. Under the synergistic effect of the X-axis coil 1, Y-axis coil 2 and Z-axis coil 3, a magnetic field in a corresponding direction is generated to control the metal catalytic material to move in the corresponding direction, so as to electrochemically corrode the material to be etched to obtain the etched material;

[0057] Post-processing: The etched material is taken out, rinsed with deionized water, and then dried to obtain a base material with a three-dimensional etched structure.

[0058] The metal-assisted chemical etching method generates a controllable magnetic field through a three-dimensional Helmholtz coil to accurately constrain and control the movement trajectory of the metal catalytic material during the metal-assisted chemical etching process, which can significantly improve the controllability and accuracy of the etching process and make the manufacture of complex micro-nano structures more efficient.

[0059] Moreover, the processing rate of metal catalytic materials can be effectively increased by adjusting the direction and intensity of the magnetic field. In the experiment, the processing rate was successfully increased to 3 times the original rate by adjusting the Z-axis current, showing the potential of this method in improving production efficiency.

[0060] In addition, through magnetic guidance, the metal catalytic material can be etched along a predetermined direction, ensuring the consistency and directionality of the etching track and manufacturing a microscopic three-dimensional structure with a specific shape and size.

[0061] In a specific embodiment of the present invention, the substrate material is a silicon wafer. However, the metal-assisted chemical etching method is not only applicable to silicon-based materials, but also can adjust the type of metal catalyst according to needs, such as using Ni or Fe, and can be extended to different materials.

[0062] In the metal-assisted chemical etching method, the pre-cleaning step can remove the surface grease of the substrate material to avoid the problem that the grease affects the addition process of the metal catalytic material, thereby affecting the effect of subsequent etching. The type and shape of the metal catalytic material can be selected according to the actual situation in the step of adding the metal catalytic material, so as to etch a structure of a special-shaped hole or an etching groove. The steps of soaking in the etching liquid and placing in the magnetic field guided etching device are both pre-treatment steps of three-dimensional magnetic field guided etching, so that the material to be etched is in contact with the etching liquid and placed in the magnetic field guided etching device so that the three-dimensional magnetic field guided etching step can be performed.

[0063] In the three-dimensional magnetic field guided erosion step, a controllable magnetic field is generated using a three-dimensional Helmholtz coil, which can focus the direction of the magnetic field, thereby generating magnetic attraction in any direction on the metal particles; during erosion, current can be simultaneously passed through two of the X-axis coil 1, Y-axis coil 2, and Z-axis coil 3, and when the magnetic fields in two corresponding directions are superimposed, the size of the magnetic field can be increased or reduced, and the direction of the magnetic field can be changed, thereby etching a microscopic three-dimensional structure of a specific shape and size. If a single coil is selected, etching can be performed in a single direction.

[0064] In a specific embodiment of the present invention, the preset time is 5s, and the magnetic field is provided after waiting for 5s, so that the metal catalyst material can be embedded in the base material first, avoiding the problem of the placed metal catalyst material being offset due to the influence of the magnetic field, and ensuring that the metal catalyst material under the action of the magnetic field can perform the next step of magnetic guided etching according to the arrangement state attached to the base material.

[0065] In the post-processing step, the etched material is taken out, rinsed with deionized water, and dried, and the process is repeated three times to obtain a base material with a three-dimensional etched structure. The metal catalytic material can be removed by ultrasonic vibration.

[0066] Specifically, in the step of three-dimensional magnetic field guided etching, the etching time is 15 to 25 minutes, and the etching temperature is 22 to 27°C.

[0067] The etching time is selected according to the specific etching shape. During the etching process, the etching temperature needs to be maintained at 22-27°C to avoid temperature changes affecting the etching effect.

[0068] Specifically, in the step of three-dimensional magnetic field guided erosion, the current passed through one or two coils of the X-axis coil 1, the Y-axis coil 2 and the Z-axis coil 3 is 1 to 30A; the magnetic induction intensity of the X-axis coil 1 is 6.8 to 200Gs; the magnetic induction intensity of the Y-axis coil 2 is 7.3 to 200Gs; and the magnetic induction intensity of the Z-axis coil 3 is 50.6 to 200Gs.

[0069] The corresponding relationship between the magnetic field magnitude and the current of the X-axis coil 1, the Y-axis coil 2 and the Z-axis coil 3 is shown in Table 1.

[0070] Table 1- Correspondence between magnetic field and current

[0071] Magnetic field direction 1A 2A 3A 3.96A 10A 15A 20A 27.4A 29.4A Z 50.6Gs 101.2Gs 151.9Gs 200Gs / / / / / Y 7.3Gs 14.6Gs 21.9Gs / 73.3Gs 111Gs 147.1Gs 200Gs / X 6.8Gs 13.7Gs 20.7Gs / 68.2Gs 102.2Gs 136.5Gs / 200Gs

[0072] Since the magnetic field of some current magnitudes is unstable, it is represented by " / " in Table 1. By controlling the magnitude and direction of the current passed through the X-axis coil 1, the Y-axis coil 2 and the Z-axis coil 3, the magnitude and direction of the magnetic field can be controlled, thereby controlling the metal catalyst material to etch along a predetermined direction.

[0073] Specifically, the etching solution includes 40-48% HF, 9-12% H2O2 and 42-50% deionized water in terms of weight percentage.

[0074] The etching solution is obtained by mixing hydrofluoric acid and hydrogen peroxide. The etching solution can etch the substrate material through the catalysis of the metal catalytic material.

[0075] Furthermore, in the pre-cleaning step, the following steps are included:

[0076] The substrate material is immersed in toluene and ultrasonically cleaned for 28 to 32 minutes, then the substrate material is taken out and rinsed with deionized water;

[0077] The substrate material is immersed in acetone and ultrasonically cleaned for 28 to 32 minutes, then the substrate material is taken out and rinsed with deionized water;

[0078] The substrate material is immersed in anhydrous ethanol and ultrasonically cleaned for 28 to 32 minutes, then the substrate material is taken out and rinsed with deionized water;

[0079] Dry the base material in an environment of 98-100°C.

[0080] In practical applications, the volume concentration of toluene is ≥99.5%, the volume concentration of acetone is ≥99.5%, and the volume concentration of anhydrous ethanol is ≥99.7%. The specific steps of drying are: placing the substrate material in a tube furnace at 100°C for 3 hours to ensure that the residual solution on the surface of the substrate material is completely evaporated. The above pre-cleaning steps can completely remove the oil stains on the surface of the substrate material to prevent the oil stains from affecting the subsequent steps.

[0081] Furthermore, the step of adding the metal catalytic material includes the following steps:

[0082] Prepare Ni@SiO2 with a concentration of 0.5 mg / ml or NiSi@SiO2 solution with a concentration of 0.5 mg / ml;

[0083] Coating Ni@SiO2 or NiSi@SiO2 solution on the surface of the substrate material;

[0084] The Ni@SiO2 or NiSi@SiO2 solution on the surface of the base material is dried to make the Ni@SiO2 or NiSi@SiO2 attached to the surface of the base material.

[0085] In a specific embodiment of the present invention, Ni@SiO2 includes Ni metal particles with a particle size of 8 to 11 μm and a SiO2 wrapping layer with a thickness of 95 to 110 μm, and the SiO2 wrapping layer wraps the outer periphery of the Ni metal particles.

[0086] In another specific embodiment of the present invention, NiSi@SiO2 includes NiSi particles with a particle size of 8 to 11 μm and a SiO2 encapsulating layer with a thickness of 95 to 110 μm, wherein the SiO2 encapsulating layer is encapsulated around the NiSi particles.

[0087] Ni and NiSi are both catalysts. Ni and NiSi are paramagnetic and can change their motion trajectory under the influence of magnetic field. The periphery of Ni or NiSi is wrapped with SiO2, which acts as a spacer. During spin coating, the spacing between adjacent NiSi or adjacent Ni can be at least the thickness of the SiO2 wrapping layer; when the material to be etched is immersed in the etching solution, the SiO2 wrapping layer will be dissolved by hydrofluoric acid, exposing Ni or NiSi, achieving the catalytic effect.

[0088] In actual operation, Ni@SiO2 or NiSi@SiO2 solution is spin-coated by a sizing machine. The working process of the sizing machine includes three stages, including a particle spreading stage lasting 5 seconds, a particle arrangement stage lasting 5 seconds, and a stage of removing excess particles lasting 10 seconds. The rotation speeds of the three stages are 500rpm, 2000rpm, and 5000rpm, respectively. Using the above steps, holes with an aperture of 8 to 11μm can be etched through Ni or NiSi particles. By controlling the magnetic field, the motion trajectory of the Ni or NiSi particles can be changed, and a special-shaped hole structure can be etched on the surface of the material to be etched.

[0089] Furthermore, in the pre-cleaning step, the following steps are included:

[0090] Soak the substrate material in acetone for 5 to 15 minutes, then take out the substrate material and rinse it with deionized water;

[0091] Soak the substrate material in anhydrous ethanol for 5 to 15 minutes, then take out the substrate material and rinse it with deionized water;

[0092] Dry the base material in an environment of 98-100°C.

[0093] The volume concentration of acetone is ≥99.5%, and the volume concentration of anhydrous ethanol is ≥99.7%. The specific steps of drying are: placing the substrate material in a tube furnace at 100°C for 3 hours to ensure that the residual solution on the surface of the substrate material is completely evaporated. The above pre-cleaning steps can completely remove the oil stains on the surface of the substrate material to prevent the oil stains from affecting the subsequent steps.

[0094] Furthermore, the step of adding the metal catalytic material includes the following steps:

[0095] A photoresist is coated on the surface of the base material 51 to form a PR layer 52 on the surface of the base material 51;

[0096] Etching the PR layer 52 by photolithography to form a PR groove 53 on the PR layer 52 ;

[0097] Depositing Au on the PR layer 52 and the PR groove 53 to form a first catalytic deposition layer 54;

[0098] Depositing magnetic material on the first catalytic deposition layer 54 to form a magnetic guide layer 55; the width of the magnetic guide layer 55 is smaller than the width of the first catalytic deposition layer 54;

[0099] Au is deposited again to fill the gap between the magnetic guide layer 55 and the PR groove 53, and to form a second catalytic deposition layer 56; the width of the first catalytic deposition layer 54 is the same as the width of the second catalytic deposition layer 56, so that the first catalytic deposition layer 54 and the second catalytic deposition layer 56 wrap the magnetic guide layer 55 to form a metal catalytic material;

[0100] The PR layer 52 is removed, leaving the surface of the base material with the metal catalyst material.

[0101] The magnetic material is Ni or Fe. The catalytic performance of Au is higher than that of Ni and Fe, but Au does not have paramagnetism and cannot change its motion trajectory according to the change of magnetic field. By adopting the above steps, a long strip of metal catalytic material can be prepared. Since the metal catalytic material is wrapped with magnetic material, the magnetic field can be controlled to change the motion trajectory of the metal catalytic material, thereby etching a complex etching groove.

[0102] Specifically, the deposition thickness of the first catalytic deposition layer 54 , the magnetic guide layer 55 and the second catalytic deposition layer 56 is 18-25 nm.

[0103] By adopting the above deposition thickness, the magnetic guide layer 55 is wrapped between the first catalytic deposition layer 54 and the second catalytic deposition layer 56, so as to prevent the magnetic guide layer 55 from being affected by the etching solution. At the same time, it is ensured that there is enough Au for catalysis so that Au can participate in the etching process.

[0104] Please refer to Figure 1 The present invention also provides a metal-assisted chemical etching device based on three-dimensional magnetic field guidance, which is used to implement the above-mentioned metal-assisted chemical etching method based on three-dimensional magnetic field guidance, including an X-axis coil 1, a Y-axis coil 2 and a Z-axis coil 3, wherein the Y-axis coil 2 is sleeved on the outer periphery of the Z-axis coil 3, and the X-axis coil 1 is sleeved on the outer periphery of the Y-axis coil 2; the X-axis coil 1, the Y-axis coil 2 and the Z-axis coil 3 are respectively provided with terminals, and the X-axis coil 1, the Y-axis coil 2 and the Z-axis coil 3 are respectively connected to an external power supply through the terminals;

[0105] The axis of the Z-axis coil 3 is perpendicular to the horizontal line, and the Z-axis coil 3 is provided with a placement platform 31, and the placement platform 31 is used to place the container 4 containing the material to be etched and the etching liquid.

[0106] The material of the container 4 is polytetrafluoroethylene. In a specific embodiment of the present invention, the winding wire diameter of the Z-axis coil 3 is 1.1-1.3 mm, the inner diameter of the coil is 93-96 mm, the outer diameter of the coil is 175-177 mm, the number of coil turns is 840, the total coil resistance (16°C) is 7.0-7.4, and the inductance is 82-85 mH; the winding wire diameter of the Y-axis coil 2 is 2.6-2.9 mm, the inner diameter of the coil is 181-186 mm, and the outer diameter of the coil is 270 ~274mm, the number of coil turns is 200, the total coil resistance (16℃) is 0.45~0.50, and the inductance is 8.06~8.09mH; the winding wire diameter of the X-axis coil 1 is 2.8~3.1mm, the inner diameter of the coil is 273~278mm, the outer diameter of the coil is 374~378mm, the number of coil turns is 264, the total coil resistance (16℃) is 0.80~0.84, and the inductance is 21.2~21.5mH.

[0107] The magnetic field uniformity area range of 0.1% magnetic field error is 28mm×28mm×28mm, the magnetic field uniformity area range of 1% magnetic field error is 36mm×36mm×36mm, and the magnetic field uniformity area range of 2% magnetic field error is 80mm×56mm×40mm.

[0108] The metal-assisted chemical etching device can refer to the existing three-dimensional Helmholtz coil. When in use, the positive and negative outputs of the power supply are selected according to the direction of the magnetic field, and magnetic fields in different directions can be obtained. The metal-assisted chemical etching device generates a controllable magnetic field through the X-axis coil 1, the Y-axis coil 2 and the Z-axis coil 3 to constrain and control the movement trajectory of the metal catalyst in the metal-assisted chemical etching process, thereby achieving the purpose of improving the controllability, accuracy and processing rate of the etching process.

[0109] Example 1

[0110] Please refer to Figure 2 , a metal-assisted chemical etching method based on three-dimensional magnetic field guidance, comprising the following steps:

[0111] Pre-cleaning: Use a silicon wafer with a size of 1 cm × 1 cm and a thickness of 300 μm as the substrate material, soak the substrate material in toluene, and ultrasonically clean it for 28 to 32 minutes. Then take out the substrate material and rinse it with deionized water for 10 times;

[0112] The substrate material was immersed in acetone and ultrasonically cleaned for 28 to 32 minutes, then the substrate material was taken out and rinsed with deionized water 10 times;

[0113] The substrate material was immersed in anhydrous ethanol and ultrasonically cleaned for 28 to 32 minutes, then the substrate material was taken out and rinsed with deionized water for 10 times;

[0114] The base material was placed in a tube furnace at 98-100°C and dried for 3 hours;

[0115] Additional metal catalyst material: prepare Ni@SiO2 solution with a concentration of 0.5 mg / ml;

[0116] The substrate material was placed on the table of the coating machine, 3 mL of Ni@SiO2 solution was dropped on the surface of the substrate material, and the parameters of the coating machine were set so that the working process of the coating machine included three stages, including a particle spreading stage lasting 5 seconds, a particle arrangement stage lasting 5 seconds, and a stage of removing excess particles lasting 10 seconds. The rotation speeds of the three stages were 500 rpm, 2000 rpm, and 5000 rpm, respectively. The coating machine was started for spin coating;

[0117] After the spin coating, the substrate material was placed in a tube furnace at 100 °C for 3 h to ensure that the solution was completely evaporated and Ni@SiO2 was attached to the surface of the substrate material;

[0118] Soaking in etching solution: placing the material to be etched into a container 4 filled with etching solution; the etching solution contains 40wt% HF, 10wt% H2O2 and 50wt% deionized water;

[0119] Place in a magnetic field guided etching device: place a container 4 containing the material to be etched and the etching liquid in the etching area of ​​the three-dimensional Helmholtz coil frame;

[0120] Three-dimensional magnetic field guided erosion: After waiting for 5 seconds, a current of 2A is passed through the Z-axis coil 3 to generate a Z-axis magnetic field of 101.2Gs, which produces a vertical downward magnetic attraction to Ni; after processing for 10 minutes, the current of the Z-axis coil 3 is set to 0, and the current of the X-axis coil 1 is set to 2A, which generates an X-axis magnetic field of 111Gs, which produces a magnetic attraction to Ni in the X-axis direction. After processing for 10 minutes, the power is turned off; the etching time is a total of 20 minutes, and the etching temperature is constant at 25°C;

[0121] Post-processing: The etched material is taken out, and the operation of rinsing with deionized water and drying is repeated three times to obtain a base material with a three-dimensional etched structure.

[0122] By using the above etching method, when etching in the Z-axis direction, the processing rate is increased to 9 μm / min, which is three times the existing processing rate, and a special-shaped hole with a hole diameter of 8 to 11 μm is formed.

[0123] Example 2

[0124] Please refer to Figure 3 , a metal-assisted chemical etching method based on three-dimensional magnetic field guidance, comprising the following steps:

[0125] Pre-cleaning: Use a p-type Si100 wafer with a size of 1 cm×1 cm and a thickness of 300 μm as the substrate material, soak the substrate material in acetone for 10 minutes, then take out the substrate material and rinse it with deionized water 10 times;

[0126] The substrate material was soaked in anhydrous ethanol for 10 minutes, then the substrate material was taken out and rinsed with deionized water for 10 times;

[0127] The base material was placed in a tube furnace at 98-100°C and dried for 3 hours;

[0128] Adding metal catalyst material: coating a photoresist on the surface of the base material to form a PR layer 52 on the surface of the base material;

[0129] Etching the PR layer 52 by photolithography to form a PR groove 53 on the PR layer 52 ;

[0130] Au is deposited on the PR layer 52 and the PR groove 53 by electron beam evaporation, with a deposition thickness of 30 nm, to form a first catalytic deposition layer 54;

[0131] Ni is deposited on the first catalytic deposition layer 54 by electron beam evaporation, with a deposition thickness of 20 nm, to form a magnetic guide layer 55; the width of the magnetic guide layer 55 is smaller than the width of the first catalytic deposition layer 54;

[0132] Au is deposited again by electron beam evaporation to fill the gap between the magnetic guide layer 55 and the PR groove 53, with a deposition thickness of 20 nm to form a second catalytic deposition layer 56; the width of the first catalytic deposition layer 54 is the same as that of the second catalytic deposition layer 56, forming a metal catalytic material;

[0133] The PR layer 52 is removed, so that the surface of the base material is attached with a metal catalyst material;

[0134] Soaking in etching solution: placing the material to be etched into a container 4 filled with etching solution; the HF content in the etching solution is 48wt%, the H2O2 content is 10wt%, and the deionized water content is 42wt%;

[0135] Place in a magnetic field guided etching device: place a container 4 containing the material to be etched and the etching liquid in the etching area of ​​the three-dimensional Helmholtz coil frame;

[0136] Three-dimensional magnetic field guided erosion: After waiting for 5 seconds, 3A current is passed through the Z-axis coil 3 to generate a Z-axis magnetic field of 151.9GsGs, which produces a vertical downward magnetic attraction to Ni; after 10 minutes of processing, while maintaining the current of the Z-axis coil 3, the current of the Y-axis coil 2 is set to 10A, generating a Y-axis magnetic field of 73.3Gs; at this time, due to the combined effect of the Z-axis magnetic field and the Y-axis magnetic field, an offset magnetic field is generated; after 5 minutes of processing, the current of the Z-axis coil 3 is set to 0, leaving only the Y-axis coil to generate a magnetic field, guiding the metal catalyst material to move in the Y-axis direction, generating a Y-axis magnetic attraction to the metal catalyst material, and after 10 minutes of processing, the power is turned off; the total etching time is 25 minutes, and the etching temperature is constant at 25°C;

[0137] Post-processing: The etched material is taken out, and the operation of rinsing with deionized water and drying is repeated three times to obtain a base material with a three-dimensional etched structure.

[0138] By means of the above etching method, a curved silicon structure is etched on the substrate material.

[0139] The technical principle of the present invention is described above in conjunction with specific embodiments. These descriptions are only for explaining the principle of the present invention and cannot be interpreted as limiting the scope of protection of the present invention in any way. Based on the explanations herein, those skilled in the art can associate other specific embodiments of the present invention without creative work, and these equivalent variations or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A metal-assisted chemical etching method based on three-dimensional magnetic field guidance, characterized in that: The following steps are involved: Pre-cleaning: Use organic solvent to clean the base material and dry it; Adding metal catalytic material: adding metal catalytic material to the surface of the base material to obtain the material to be etched; Soak in etching solution: put the material to be etched into a container filled with etching solution; Placing in a magnetic field guided etching device: placing a container containing a material to be etched and an etching liquid in an etching area of ​​a three-dimensional Helmholtz coil frame, wherein the three-dimensional Helmholtz coil frame comprises an X-axis coil, a Y-axis coil and a Z-axis coil, wherein the X-axis coil is used to generate a magnetic field in an X-axis direction, the Y-axis coil is used to generate a magnetic field in a Y-axis direction, and the Z-axis coil is used to generate a magnetic field in a Z-axis direction; Three-dimensional magnetic field guided erosion: after waiting for a preset time, current is passed through one or two of the X-axis coil, Y-axis coil and Z-axis coil according to process requirements. Under the synergistic effect of the X-axis coil, Y-axis coil and Z-axis coil, a magnetic field in the corresponding direction is generated to control the metal catalytic material to move in the corresponding direction, so as to electrochemically corrode the material to be etched and obtain the etched material; Post-processing: The etched material is taken out, rinsed with deionized water, and then dried to obtain a base material with a three-dimensional etched structure.

2. The metal-assisted chemical etching method based on three-dimensional magnetic field guidance according to claim 1, characterized in that: In the step of three-dimensional magnetic field guided etching, the etching time is 15 to 25 minutes and the etching temperature is 22 to 27°C.

3. The metal-assisted chemical etching method based on three-dimensional magnetic field guidance according to claim 1, characterized in that: In the step of three-dimensional magnetic field guided erosion, the current passed through one or two of the X-axis coil, Y-axis coil and Z-axis coil is 1 to 30A; the magnetic induction intensity of the X-axis coil is 6.8 to 200Gs; the magnetic induction intensity of the Y-axis coil is 7.3 to 200Gs; and the magnetic induction intensity of the Z-axis coil is 50.6 to 200Gs.

4. The metal-assisted chemical etching method based on three-dimensional magnetic field guidance according to claim 1, characterized in that: The etching solution comprises 40-48% HF, 9-12% H2O2 and 42-50% deionized water according to weight percentage.

5. The metal-assisted chemical etching method based on three-dimensional magnetic field guidance according to claim 1, characterized in that: In the pre-cleaning step, the following steps are included: The substrate material is immersed in toluene and ultrasonically cleaned for 28 to 32 minutes, then the substrate material is taken out and rinsed with deionized water; The substrate material is immersed in acetone and ultrasonically cleaned for 28 to 32 minutes, then the substrate material is taken out and rinsed with deionized water; The substrate material is immersed in anhydrous ethanol and ultrasonically cleaned for 28 to 32 minutes, then the substrate material is taken out and rinsed with deionized water; Dry the base material in an environment of 98-100°C.

6. The metal-assisted chemical etching method based on three-dimensional magnetic field guidance according to claim 5, characterized in that: The step of adding the metal catalytic material comprises the following steps: Prepare Ni@SiO2 with a concentration of 0.5 mg / ml or NiSi@SiO2 solution with a concentration of 0.5 mg / ml; Coating Ni@SiO2 or NiSi@SiO2 solution on the surface of the substrate material; The Ni@SiO2 or NiSi@SiO2 solution on the surface of the base material is dried to make the Ni@SiO2 or NiSi@SiO2 attached to the surface of the base material.

7. The metal-assisted chemical etching method based on three-dimensional magnetic field guidance according to claim 1, characterized in that: In the pre-cleaning step, the following steps are included: Soak the substrate material in acetone for 5 to 15 minutes, then take out the substrate material and rinse it with deionized water; Soak the substrate material in anhydrous ethanol for 5 to 15 minutes, then take out the substrate material and rinse it with deionized water; Dry the base material in an environment of 98-100°C.

8. The metal-assisted chemical etching method based on three-dimensional magnetic field guidance according to claim 7, characterized in that: The step of adding the metal catalytic material comprises the following steps: Coating a photoresist on the surface of the base material to form a PR layer on the surface of the base material; Etching the PR layer on the PR layer by photolithography to form a PR groove on the PR layer; Depositing Au on the PR layer and the PR groove to form a first catalytic deposition layer; Depositing magnetic material on the first catalytic deposition layer to form a magnetic guide layer; the width of the magnetic guide layer is smaller than the width of the first catalytic deposition layer; Depositing Au again to fill the gap between the magnetic guide layer and the PR groove and form a second catalytic deposition layer; the width of the first catalytic deposition layer is the same as the width of the second catalytic deposition layer, so that the first catalytic deposition layer and the second catalytic deposition layer wrap the magnetic guide layer to form a metal catalytic material; The PR layer is removed, so that the surface of the base material is attached with a metal catalyst material.

9. The metal-assisted chemical etching method based on three-dimensional magnetic field guidance according to claim 8, characterized in that: The deposition thickness of the first catalytic deposition layer, the magnetic guide layer and the second catalytic deposition layer is 18-25 nm.

10. A metal-assisted chemical etching device based on three-dimensional magnetic field guidance, used to implement the metal-assisted chemical etching method based on three-dimensional magnetic field guidance according to any one of claims 1 to 9, characterized in that: It includes an X-axis coil, a Y-axis coil and a Z-axis coil, wherein the Y-axis coil is sleeved on the outer periphery of the Z-axis coil, and the X-axis coil is sleeved on the outer periphery of the Y-axis coil; the X-axis coil, the Y-axis coil and the Z-axis coil are respectively provided with a terminal, and the X-axis coil, the Y-axis coil and the Z-axis coil are respectively connected to an external power supply through the terminal; The axis of the Z-axis coil is perpendicular to the horizontal line, and the Z-axis coil is provided with a placement platform, and the placement platform is used to place a container containing the material to be etched and the etching liquid.

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