Metal auxiliary chemical etching method based on ultrasonic standing wave sound field

Abstract

The invention discloses a metal auxiliary chemical etching method based on an ultrasonic standing wave sound field, and the method employs the ultrasonic standing wave sound field to enable suspended metal catalysis balls to be arranged on the surface of an etching substrate along sound pressure nodes, so as to induce the self-assembly of the metal catalysis balls, and form a regular particle array template. By means of the acoustic resonance mode in the fluid channel, accurate control and patterned arrangement of the metal catalysis balls are achieved, the distribution uniformity and arrangement orderliness of the metal catalysis balls can be remarkably improved, more accurate and quicker metal catalysis ball distribution is provided for the subsequent etching process, and therefore the etching accuracy and efficiency are improved. Besides, according to the scheme, the ultrasonic standing wave sound field particle self-assembly technology is combined with the MACE technology, the defects of the prior art in the aspects of large-scale manufacturing and structural precision are overcome, and the application potential of the MACE technology in large-scale manufacturing and high-precision nanostructures is remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of metal-assisted chemical etching, and in particular to a metal-assisted chemical etching method based on an ultrasonic standing wave sound field. Background Art

[0002] Metal assisted chemical etching (MACE) has become an important technology for preparing micro-nano structures. This method deposits micrometer- or nanometer-scale metal catalyst beads (such as gold, silver and other metals) on the surface of the substrate, and uses the above metal catalyst beads to catalyze local chemical reactions in the etching solution to selectively etch the substrate material (such as silicon, etc.).

[0003] However, the commonly used deposition methods of metal catalytic beads, such as magnetron sputtering and spin coating, have some limitations. The above methods are difficult to achieve precise positioning and arrangement of metal catalytic beads, resulting in insufficient structural accuracy and uniformity during the etching process; and the relative position of the metal catalytic beads cannot be adjusted during the etching reaction. In addition, in large-area patterning processing, traditional deposition methods are difficult to ensure the patterned arrangement of metal catalytic beads, which limits the application of MACE technology in large-scale manufacturing and high-precision nanostructures.

[0004] Therefore, it is urgent to develop new metal catalytic ball deposition and arrangement technology to assist chemical etching in order to improve the processing efficiency and etching accuracy of MACE. Summary of the invention

[0005] The purpose of the present invention is to propose a metal-assisted chemical etching method based on an ultrasonic standing wave sound field, wherein a standing wave sound field is applied to a suspension containing metal catalytic beads, so that the metal catalytic beads are self-assembled into a preset etching pattern on the surface of a substrate along the sound pressure nodes, which is beneficial to reducing the arrangement time of the metal catalytic beads on the substrate to improve the processing efficiency of MACE; and the etching area of ​​the above-mentioned substrate has a high degree of consistency, which is also beneficial to improving the etching accuracy of MACE.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] A metal assisted chemical etching method based on ultrasonic standing wave sound field comprises the following steps:

[0008] A. preparing an etching substrate, and placing the etching substrate at the bottom of an etching container;

[0009] B. preparing a suspension containing metal catalytic beads, and placing the suspension into the etching container;

[0010] C. driving a piezoelectric transducer through a signal generator so that the piezoelectric transducer acts on the etching container, so that a standing wave acoustic field is generated inside the etching container;

[0011] D. adjusting the frequency of the signal generator so that the metal catalytic beads in the suspension are arranged into a preset etching pattern on the surface of the etching substrate; wherein the arrangement time is 2 to 5 seconds;

[0012] E. Prepare an etching solution, and put the etching solution into the etching container to perform metal-assisted chemical etching. After the etching is completed, take out the etching substrate and wash and dry it.

[0013] Preferably, in step C, the frequency of the signal generator is 0.5-4 MHz.

[0014] Preferably, step E specifically further comprises:

[0015] E1. preparing an etching solution, and injecting the etching solution into the etching container to perform metal-assisted chemical etching;

[0016] E2. During the etching process, adjusting the frequency of the signal generator according to the desired etching effect;

[0017] E3. After etching is completed, take out the etched substrate and clean and dry it.

[0018] Preferably, the method further comprises step F, wherein step F is located after step E;

[0019] F. Repeat steps B to E.

[0020] Preferably, in step B, the suspension comprises metal catalytic beads and distilled water, and the particle size of the metal catalytic beads is 5 to 500000 nm;

[0021] In step E, the etching solution includes hydrofluoric acid, hydrogen peroxide and deionized water.

[0022] Preferably, in step C, the driving voltage of the piezoelectric transducer is 20 Vpp and the power is 10 to 50 W.

[0023] Preferably, in step B, the inner cavity shape of the etching container is any one of a cylinder and a cuboid.

[0024] Preferably, in step E, the etching temperature of the metal-assisted chemical etching is 70°C.

[0025] Preferably, in step A, the etching substrate has a length of 1 to 5 cm, a width of 1 to 5 cm, and a height of 50 to 500 μm.

[0026] Preferably, the etching container is made of polytetrafluoroethylene.

[0027] The technical solution provided by the present invention may include the following beneficial effects:

[0028] 1. An ultrasonic standing wave sound field is used to arrange the suspended metal catalytic spheres along the sound pressure nodes on the surface of the etching substrate to induce the self-assembly of the metal catalytic spheres to form a regular particle array template (i.e., etching pattern). Compared with the existing technologies of magnetron sputtering and spin coating of metal catalytic spheres, this scheme uses the acoustic resonance mode in the fluid channel to achieve precise control and patterned arrangement of the metal catalytic spheres, which can significantly improve the distribution uniformity and arrangement order of the metal catalytic spheres, and provide a more accurate and faster distribution of metal catalytic spheres for the subsequent etching process, thereby improving the etching accuracy and efficiency. In addition, compared with the traditional flat plate vibration method, this scheme can achieve more complex and diverse particle arrangements, with higher arrangement accuracy and higher etching uniformity. Moreover, by adjusting the frequency of the ultrasonic standing wave sound field, the pattern of the metal catalytic spheres on the surface of the etching substrate can be effectively controlled, thereby achieving precise control of the etching effect and improving the etching controllability.

[0029] 2. Combining the ultrasonic standing wave acoustic field particle self-assembly technology with the MACE process overcomes the shortcomings of existing technologies in large-scale manufacturing and structural accuracy, and significantly enhances the application potential of MACE technology in large-scale manufacturing and high-precision nanostructures. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of a device of a metal-assisted chemical etching method based on an ultrasonic standing wave field of the present invention.

[0031] Figure 2 The etching pattern is formed by arranging metal catalytic balls on an etching substrate at different frequencies.

[0032] Among them, there are an etching substrate 1, an etching container 2, a signal generator 3, and a piezoelectric transducer 4. DETAILED DESCRIPTION

[0033] A metal assisted chemical etching method based on ultrasonic standing wave sound field comprises the following steps:

[0034] A. Prepare an etching substrate 1, and place the etching substrate 1 at the bottom of an etching container 2;

[0035] B. preparing a suspension containing metal catalytic beads, and placing the suspension into the etching container 2;

[0036] C. driving the piezoelectric transducer 4 through the signal generator 3, so that the piezoelectric transducer 4 acts on the etching container 2, so that a standing wave acoustic field is generated inside the etching container 2;

[0037] D. adjusting the frequency of the signal generator 3 so that the metal catalytic beads in the suspension are arranged on the surface of the etching substrate 1 into a preset etching pattern; wherein the arrangement time is 2 to 5 seconds;

[0038] E. Prepare an etching solution, and put the etching solution into the etching container 2 to perform metal-assisted chemical etching. After the etching is completed, take out the etching substrate 1 and clean and dry it.

[0039] In order to improve the processing efficiency and etching accuracy of MACE, this technical solution proposes a metal-assisted chemical etching method based on ultrasonic standing wave sound field. The schematic diagram of the device is shown in Figure 1 As shown, a standing wave acoustic field is applied to a suspension containing metal catalytic beads, so that the metal catalytic beads self-assemble into a preset etching pattern on the surface of the substrate along the sound pressure nodes, which is beneficial to reducing the arrangement time of the metal catalytic beads on the substrate to improve the processing efficiency of MACE; and the etching area of ​​the above-mentioned substrate has a high degree of consistency, which is also beneficial to improving the etching accuracy of MACE.

[0040] Specifically, this solution first uses an ultrasonic standing wave sound field to arrange the suspended metal catalyst spheres along the sound pressure nodes on the surface of the etching substrate 1 to induce the self-assembly of the metal catalyst spheres to form a regular particle array template (i.e., etching pattern). Compared with the existing technologies of magnetron sputtering and spin coating of metal catalyst spheres, this solution uses the acoustic resonance mode in the fluid channel to achieve precise control and patterned arrangement of the metal catalyst spheres, which can significantly improve the distribution uniformity and arrangement order of the metal catalyst spheres, and provide a more accurate and faster distribution of metal catalyst spheres for the subsequent etching process, thereby improving the etching accuracy and efficiency. In addition, compared with the traditional plate vibration method, this solution can achieve more complex and diverse particle arrangements, and has higher arrangement accuracy and higher etching uniformity. Moreover, by adjusting the frequency of the ultrasonic standing wave sound field, the pattern of the metal catalyst spheres on the surface of the etching substrate 1 can be effectively controlled, thereby achieving precise control of the etching effect and improving the etching controllability.

[0041] Furthermore, this scheme also combines the ultrasonic standing wave acoustic field particle self-assembly technology with the MACE process, overcoming the shortcomings of the existing technology in large-scale manufacturing and structural accuracy, and significantly improving the application potential of MACE technology in large-scale manufacturing and high-precision nanostructures.

[0042] Preferably, the etching substrate 1 material of the present solution can be silicon, silicon carbide or zinc oxide, and the metal catalyst ball material can be gold or silver, which is not limited here. The etching method of the present solution can also be adapted to different chemical solution systems and has a wide range of applicability. In addition, the present solution can also achieve full control from the self-assembly of the metal catalyst balls to the etching reaction and then to the preparation of the nanostructure by optimizing the parameters and conditions of each step, so as to further improve the applicability and controllability of the solution.

[0043] To further explain, in step C, the frequency of the signal generator 3 is 0.5-4 MHz.

[0044] The piezoelectric transducer 4 of this solution can generate vibrations through electrical signals, thereby emitting sound waves. After voltage is applied, the rapid vibration of the piezoelectric material will generate sound wave signals, and the frequency of the standing wave sound field is set at 0.5-4MHz to facilitate the arrangement of the etching pattern on demand. The specific frequency depends on the acoustic resonance mode of the fluid channel.

[0045] To further illustrate, step E specifically includes:

[0046] E1. Prepare an etching solution, and put the etching solution into the etching container 2 to perform metal-assisted chemical etching;

[0047] E2. During the etching process, adjusting the frequency of the signal generator 3 according to the desired etching effect;

[0048] E3. After etching is completed, take out the etched substrate 1 and clean and dry it.

[0049] In a preferred embodiment of the present technical solution, the frequency of the signal generator 3 can be dynamically adjusted during the etching process to obtain the desired etching effect on the etching substrate 1.

[0050] In one embodiment, during the etching process, the relative position of the metal catalyst beads in the horizontal direction (X and Y directions) is kept fixed, and they only move along the processing depth direction (Z direction) without deviation, which plays a restraining role. During the etching process, the metal catalyst beads penetrate into the etching substrate 1, and the position of the metal catalyst particles is adjusted by increasing the frequency of ultrasound, which can effectively increase the processing depth.

[0051] Further, step F is included, and step F is located after step E;

[0052] F. Repeat steps B to E.

[0053] In another preferred embodiment of the present technical solution, the etching substrate 1 after the initial etching is completed can be etched twice or multiple times by repeating steps B to E to form a multi-layer patterned structure on the etching substrate 1, which is conducive to realizing its expanded application.

[0054] Further, in step B, the suspension includes metal catalytic beads and distilled water, and the particle size of the metal catalytic beads is 5 to 500000 nm;

[0055] In step E, the etching solution includes hydrofluoric acid, hydrogen peroxide and deionized water.

[0056] Specifically, the suspension of the present invention includes metal catalytic beads and distilled water, which ensures the stability of the acoustic field and the good arrangement of the particles. In addition, the distilled water in the suspension can be used as part of the solvent (i.e., deionized water) in the etching solution, which is conducive to simplifying the operation steps of the metal-assisted chemical etching method.

[0057] To further illustrate, in step C, the driving voltage of the piezoelectric transducer 4 is 20 Vpp and the power is 10 to 50 W.

[0058] The piezoelectric transducer 4 of the present solution is driven by the signal generator 3, and the driving voltage is 20 Vpp and the power is 10 to 50 W. The above power and voltage can generate sufficient acoustic radiation force to arrange the particles with high precision.

[0059] It should be noted that, in this solution, a power amplifier (not shown in the figure) may be added between the signal generator 3 and the piezoelectric transducer 4 to ensure the driving of the piezoelectric transducer 4 .

[0060] To further illustrate, in step B, the inner cavity shape of the etching container 2 is any one of a cylinder and a cuboid.

[0061] To further illustrate, in step E, the etching temperature of the metal-assisted chemical etching is 70°C.

[0062] It should be noted that the metal-assisted chemical etching process in step E of this scheme can be carried out in a water bath at a constant temperature of 70° C. to accelerate the rate of the etching reaction.

[0063] To further illustrate, in step A, the etching substrate 1 has a length of 1 to 5 cm, a width of 1 to 5 cm, and a height of 50 to 500 μm, so as to meet the actual application requirements of the etching substrate 1 .

[0064] Further, the etching container 2 is made of polytetrafluoroethylene to prevent the hydrofluoric acid in the etching solution from corroding the etching container 2 .

[0065] This proposal also proposes an application of a metal-assisted chemical etching method based on ultrasonic standing wave field in the micro-nanostructure processing of silicon-based materials.

[0066] In the manufacture of microelectronic devices, the etching accuracy of silicon-based materials is crucial. Through ultrasonic standing wave acoustic field technology, metal catalytic beads are precisely assembled into specific areas on the surface of silicon wafers. These metal beads act as catalysts to promote local chemical etching reactions.

[0067] Compared with traditional wet etching, this technology can achieve the following advantages:

[0068] High etching precision: Since the metal balls can self-assemble to the predetermined position, the etched area has a high consistency, which is suitable for micro-nanoscale fine processing.

[0069] The etching depth is controllable: By adjusting the frequency of ultrasound, the arrangement and density of the metal balls can be controlled, thereby adjusting the etching depth. This method can be used to manufacture high-precision micro-nano sensors, optical devices, and silicon-based nanostructures.

[0070] This proposal also proposes an application of a metal-assisted chemical etching method based on ultrasonic standing wave field in the preparation of heterostructures of optoelectronic devices.

[0071] In the field of optoelectronics, the precise preparation of heterostructures is crucial to improving device performance. Using ultrasonic standing wave fields, metal catalytic spheres are self-assembled at the interface of different materials to form a multi-layer heterostructure. Through metal-assisted chemical etching, materials in certain areas can be precisely removed to achieve complex three-dimensional structure design.

[0072] Using this technology can achieve the following advantages:

[0073] Heterostructure formation: By selecting metal catalytic beads of different sizes and combining them with chemical etching processes, selective removal of different materials can be achieved to form layered or multi-layer heterostructures.

[0074] Improve device performance: This precision etching technology enables optoelectronic devices to have higher photoelectric conversion efficiency, response speed and optical performance.

[0075] The technical solution of the present invention is further illustrated below through specific implementation methods.

[0076] Example 1: Processing of micro-nanostructures on silicon wafers

[0077] A. Prepare a silicon wafer with a size of 2cm*2cm*100μm, and place the silicon wafer at the bottom of the etching container 2;

[0078] B. Prepare a suspension containing silver balls, and put the suspension into the etching container 2; wherein the suspension includes silver balls with a particle size of 20000 nm and 20 ml of distilled water.

[0079] C. The piezoelectric transducer 4 is driven by the signal generator 3 with a driving voltage of 20 Vpp and a power of 10 to 50 W, so that the piezoelectric transducer 4 acts on the etching container 2 to generate a standing wave acoustic field inside the etching container 2;

[0080] D. Adjust the frequency of signal generator 3 to 0.595 MHz, so that the silver balls are arranged on the surface of the silicon wafer as follows. Figure 2 The (1,0) mode etching pattern (black area) is shown; the arrangement of the silver balls on the silicon wafer is completed within 2 to 5 seconds. It should be noted that the arrangement process of the particles can be observed and recorded in advance by a fluorescence microscope, so that the metal catalyst balls can be quickly arranged into the desired etching pattern during the actual etching process.

[0081] E. Prepare an etching solution and put it into the etching container 2 for metal-assisted chemical etching. After the etching is completed, take out the silicon wafer and wash and dry it. The etching solution includes 10 ml of hydrofluoric acid with a concentration of 48%, 1 ml of hydrogen peroxide with a concentration of 30%, and 20 ml of deionized water. The temperature of the etching reaction is 70°C and the time is 10 minutes. During the etching process, the silver ball plays a catalytic role. The silicon wafer in contact with the silver ball is more easily oxidized than the surface without contact with the silver ball. That is, hydrogen peroxide partially oxidizes the silicon surface into silicon dioxide, while hydrofluoric acid dissolves the above silicon dioxide and exposes a new silicon surface. This oxidation-etching cycle occurs at the location where the silver ball is deposited, thereby causing local dissolution and etching of the silicon wafer.

[0082] Example 2: Rapid processing of multi-layer patterned structures on a gallium nitride substrate

[0083] A. Prepare a gallium nitride substrate with a size of 2cm*2cm*0.1cm, and place the gallium nitride substrate at the bottom of the etching container 2;

[0084] B. Prepare a suspension containing gold balls, and put the suspension into the etching container 2; wherein the suspension includes gold balls with a particle size of 100 μm and 20 ml of distilled water.

[0085] C. The piezoelectric transducer 4 is driven by the signal generator 3 with a driving voltage of 20 Vpp and a power of 10 to 50 W, so that the piezoelectric transducer 4 acts on the etching container 2 to generate a standing wave acoustic field inside the etching container 2;

[0086] D. Adjust the frequency of signal generator 3 to 0.595 MHz, so that the gold balls are arranged on the surface of the GaN substrate as shown below. Figure 2The (1,0) mode etching pattern (black area) is shown; in which the arrangement of gold balls on the silicon wafer is completed within 2 to 5 seconds.

[0087] E. Prepare an etching solution and put it into the etching container 2 for metal-assisted chemical etching. After the etching is completed, take out the gallium nitride substrate and clean and dry it. The etching solution includes 15 ml of hydrofluoric acid with a concentration of 48%, 1 ml of hydrogen peroxide with a concentration of 30%, and 15 ml of deionized water. The temperature of the etching reaction is 70°C and the time is 10 minutes.

[0088] F. Repeat the above steps B to E for the GaN substrate that has been initially etched in step E, and adjust the frequency of the signal generator 3 in step D to 3.911 MHz, so that the gold balls are arranged on the surface of the GaN substrate as follows: Figure 2 The etching pattern (black area) of the (4,0) mode is shown. After two etching processes, a double-layer patterned structure with (1,0) mode and (4,0) mode superimposed is formed on the gallium nitride substrate.

[0089] 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 implementations of the present invention without paying creative labor, and these methods will fall within the scope of protection of the present invention.

Claims

1. A metal-assisted chemical etching method based on ultrasonic standing wave field, characterized in that: The following steps are involved: A. preparing an etching substrate, and placing the etching substrate at the bottom of an etching container; B. preparing a suspension containing metal catalytic beads, and placing the suspension into the etching container; C. driving a piezoelectric transducer through a signal generator so that the piezoelectric transducer acts on the etching container, so that a standing wave acoustic field is generated inside the etching container; D. adjusting the frequency of the signal generator so that the metal catalytic beads in the suspension are arranged into a preset etching pattern on the surface of the etching substrate; wherein the arrangement time is 2 to 5 seconds; E. Prepare an etching solution, and put the etching solution into the etching container to perform metal-assisted chemical etching. After the etching is completed, take out the etching substrate and wash and dry it.

2. The metal-assisted chemical etching method based on ultrasonic standing wave field according to claim 1, characterized in that: In step C, the frequency of the signal generator is 0.5-4 MHz.

3. The metal-assisted chemical etching method based on ultrasonic standing wave field according to claim 1, characterized in that: Step E specifically also includes: E1. preparing an etching solution, and injecting the etching solution into the etching container to perform metal-assisted chemical etching; E2. During the etching process, adjusting the frequency of the signal generator according to the desired etching effect; E3. After etching is completed, take out the etched substrate and clean and dry it.

4. The metal-assisted chemical etching method based on ultrasonic standing wave field according to claim 1, characterized in that: Also includes step F, said step F is located after said step E; F. Repeat steps B to E.

5. The metal-assisted chemical etching method based on ultrasonic standing wave field according to claim 1, characterized in that: In step B, the suspension includes metal catalytic beads and distilled water, and the particle size of the metal catalytic beads is 5 to 500000 nm; In step E, the etching solution includes hydrofluoric acid, hydrogen peroxide and deionized water.

6. The metal-assisted chemical etching method based on ultrasonic standing wave field according to claim 1, characterized in that: In step C, the driving voltage of the piezoelectric transducer is 20 Vpp and the power is 10 to 50 W.

7. The metal-assisted chemical etching method based on ultrasonic standing wave field according to claim 1, characterized in that: In step B, the inner cavity of the etching container is in the shape of a cylinder or a cuboid.

8. The metal-assisted chemical etching method based on ultrasonic standing wave field according to claim 1, characterized in that: In step E, the etching temperature of the metal-assisted chemical etching is 70°C.

9. The metal-assisted chemical etching method based on ultrasonic standing wave field according to claim 1, characterized in that: In step A, the etching substrate has a length of 1 to 5 cm, a width of 1 to 5 cm, and a height of 50 to 500 μm.

10. The metal-assisted chemical etching method based on ultrasonic standing wave field according to claim 1, characterized in that: The etching container is made of polytetrafluoroethylene.

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