Silicon deep etching method of high aspect ratio structure

Abstract

The invention discloses a silicon deep etching method of a high aspect ratio structure. The silicon deep etching method comprises the following steps of: 1, exposing a required structure plane pattern on a silicon wafer; 2, depositing a metal catalyst with a set thickness above the silicon substrate partially covered with the photoresist; 3, preparing the porous morphology of the metal catalyst on the basis of the metal catalyst prepared in the step 2; and 4, the silicon wafer is immersed in an etching solution prepared by mixing an oxidizing agent and hydrofluoric acid in a set proportion for etching, a silicon hole with a high aspect ratio is obtained, the silicon hole comprises a channel and a hole, and deep silicon etching is achieved. According to the method, the micro-nano scale morphology of the metal catalyst is accurately regulated and controlled, and the corresponding etching solution is reasonably used, so that a smooth, flat and uniform high aspect ratio structure is prepared on a large scale.

Description

Technical Field

[0001] The invention relates to a silicon deep etching method for a high aspect ratio structure, belonging to the technical field of integrated circuit three-dimensional packaging and MEMS manufacturing. Background Art

[0002] Deep silicon etching is a micro-nano processing method that can process structures with a depth much greater than their width by etching inside the silicon substrate. Such structures are called high aspect ratio structures, including deep grooves, deep holes, etc. Such structures are widely used in the manufacture of integrated circuit three-dimensional packaging and micro-electromechanical systems (MEMS).

[0003] Currently, deep silicon etching is mainly achieved using deep reactive ion etching (DRIE) technology. DRIE technology requires the use of a high vacuum chamber, precision plasma control circuits, precision gas supply control systems, and special gases, and has the limitations of high equipment complexity and high production costs. At the same time, this technology can only etch a single wafer in the same process chamber, which has the limitation of low production throughput.

[0004] Metal-assisted chemical etching (MACE) is a wet etching technology that only requires processing metal catalysts on silicon substrates and then achieving etching by immersion in a solution. However, traditional MaCE technology is generally used to process regularly arranged nanowires and nanosheet arrays on the surface of silicon wafers. When MaCE is used to process deep grooves, deep holes and other structures with large depths, it faces problems such as catalyst deformation and strong randomness in etching direction, resulting in poor controllability of the etched structure and many defects. Therefore, MaCE cannot be directly applied to deep silicon etching for three-dimensional packaging and MEMS manufacturing. Summary of the invention

[0005] The technical problem to be solved by the present invention is: how to broaden the process window of the catalyst film and improve the stability of the catalyst by changing the process steps, so as to manufacture a microstructure with a high aspect ratio.

[0006] In order to solve the above technical problems, the present invention provides a method for deep etching of silicon of a high aspect ratio structure, comprising the following steps: Step 1, exposing the required structural plane on the silicon wafer; Step 2, depositing a metal catalyst of a set thickness on the silicon substrate partially covered with the photoresist; Step 3, based on the metal catalyst prepared in step 2, preparing a porous morphology of a metal catalyst; Step 4: immerse the silicon wafer in an etching solution for etching to obtain silicon holes with a high aspect ratio, wherein the silicon holes include channels and holes to achieve deep silicon etching; the etching solution is prepared by mixing an oxidant and hydrofluoric acid with a set proportion of components.

[0007] The aforementioned silicon etching method for a high aspect ratio structure comprises, in step 1, the following steps: 11) Cleaning the silicon substrate using a cleaning agent; 12) Use deionized water to clean the bare silicon wafer, and then use nitrogen to blow dry the bare silicon wafer; 13) Depositing photoresist on the surface of the silicon substrate by spin coating or spray coating, the thickness of the photoresist is 10 nm-2 μm; the photoresist completely covers the surface of the silicon substrate, and after exposure, baking, and development in sequence, a specific pattern with micro-nanoscale precision is formed, wherein the specific pattern is formed by mask exposure, and masks with different patterns are customized, the photoresist inside the pattern is removed by the developer, the surface of the silicon substrate is exposed, and the photoresist outside the pattern still covers the surface of the silicon substrate. After the pattern is formed, the area of ​​the silicon substrate surface covered by the photoresist is not etched, and the area not covered by the photoresist is etched, forming the horizontal shape of the structure to be etched; 14) Rinse the developed silicon wafer again with deionized water and blow dry with nitrogen.

[0008] In the aforementioned silicon etching method for a high aspect ratio structure, in step 11), the cleaning agent includes an organic cleaning agent and an inorganic cleaning agent; The organic cleaning agent contains one or more of acetone, ethanol, isopropanol and the like; The inorganic cleaning agent contains one or more components such as sulfuric acid, hydrochloric acid, and hydrogen peroxide.

[0009] In the aforementioned method for etching silicon with a high aspect ratio, in step 11), the cleaning agent is a strong acid cleaning solution, and the bare silicon wafer is placed in the strong acid cleaning solution and boiled to 100-200 o C, cleaning for 10-40 minutes according to the cleanliness of the silicon wafer, the strong acid cleaning solution is composed of H2SO4 and H2O2, and the volume ratio of H2SO4:H2O2 is 1:10 to 10:1; In the aforementioned silicon etching method for a high aspect ratio structure, in step 2, the material of the metal catalyst is one or more of gold, silver, ruthenium, rhodium, palladium, osmium, iridium, and platinum.

[0010] In the aforementioned silicon etching method for a high aspect ratio structure, in step 2, the substrate silicon wafer obtained in step 1 is cleaned again using a plasma cleaning machine; A layer of metal catalyst is deposited on a silicon substrate using magnetron sputtering equipment, thermal evaporation equipment, electron beam evaporation equipment, chemical deposition or electrochemical deposition equipment. The thickness of the metal catalyst is 1-1000 nm. The thickness of the metal catalyst is controlled by controlling the sputtering, evaporation, electron beam evaporation, chemical reaction time or electrochemical deposition time.

[0011] The aforementioned silicon etching method for a high aspect ratio structure, when a plasma sputtering metal catalyst is selected in step 2, comprises the following steps: 1) Use the vacuum system to evacuate the sputtering chamber to 10 -7 After the vacuum reaches 1×10 Torr, argon gas is filled in to reduce the vacuum to 1×10 - 3 Torr, the hot cathode is heated by electricity, the heating voltage is 50-240V, the cathode emits electrons, and the electrons collide with argon molecules and ionize in the process of moving toward the anode with positive voltage, forming plasma; 2) Under the action of the focusing magnetic field, the plasma is focused into a columnar shape, forming a high-density plasma. The positive ions bombard the target surface under the acceleration of the negative voltage applied to the target, and atoms are sputtered from the target surface; 3) The atoms move in a straight line and deposit on the substrate opposite the target to form a sputtered film. The sputtering time is controlled between 2 and 120 minutes. After the metal catalyst reaches the preset thickness, the heating voltage is turned off. 4) After the metal catalyst deposition is completed, the thickness of the metal catalyst is measured using an ellipsometer and the thickness of the metal catalyst is adjusted to a set range.

[0012] In the aforementioned silicon etching method for a high aspect ratio structure, in step three, the method for preparing the pores of the catalyst includes: plasma etching, chemical etching, heat treatment or surface modification.

[0013] In the aforementioned silicon etching method for a high aspect ratio structure, in step three, after completing the preparation of the porous morphology, the shape, number, diameter, and spacing distribution of the holes are measured and counted by a scanning electron microscope, a transmission electron microscope, or an atomic force microscope for use in the subsequent etching process and the regulation of the structure shape.

[0014] In the aforementioned silicon etching method for a high aspect ratio structure, in step three, the hole density is 0-50%, the minimum width of the hole is 0-100 nm, and the shape of the hole is regular hole, linear array hole or irregular curve hole.

[0015] In the aforementioned silicon etching method for a high aspect ratio structure, in step 4, the oxidant is one of potassium permanganate, hydrogen peroxide, peroxide, nitric acid, nitrate, nitrite, and nitrite.

[0016] The beneficial effects achieved by the present invention are as follows: a method for deep silicon etching of a high aspect ratio structure of the present invention uses a metal film with a porous morphology as a catalyst to ensure the uniformity, stability and controllability of metal-assisted deep silicon etching, and the etching results are Figure 7 , 8 9 It can be seen that the method of the present invention overcomes the problem of catalyst deformation and the randomness of catalyst etching direction, has strong processing capability, high aspect ratio, and smooth sidewalls.

[0017] The equipment used in the method of the present invention is simple, easy to maintain, and low in cost. All patterns on a silicon wafer can be etched simultaneously, and multiple silicon wafers can be processed simultaneously in all steps, resulting in a large production throughput. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the structure of deep silicon etching results in Example 1 of the method for deep silicon etching of a structure with a high aspect ratio of the present invention; Figure 2 This is an atomic force microscope scan of a porous catalyst; Figure 3 is a flow chart of the preparation method of the present invention; Figure 4 This is the uneven etching morphology after etching of the non-porous catalyst; Figure 5 Schematic diagram of the interface state of non-porous catalyst and porous catalyst before and after etching; Figure 6 This is the bifurcated etching morphology after etching the porous catalyst; Figure 7 This is the side wall tilted etching morphology after the porous catalyst is etched; Figure 8 This is the vertical etching morphology of the side wall after etching the porous catalyst; Fig. 9 This is the high aspect ratio uniform etching morphology after porous catalyst etching.

[0019] Figure numerals: 1. non-porous catalyst, 2. etchant, 3. void region, 4. silicon wafer, 5. porous catalyst, 6. pores, 7. substrate. DETAILED DESCRIPTION

[0020] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0021] Example 1 This embodiment provides a silicon etching method for a high aspect ratio structure, comprising the following steps: Step 1, exposing the required structural plane on the silicon wafer; In step one, include: 11) Cleaning the silicon substrate 7 using a cleaning agent; The cleaning agent includes an organic cleaning agent and an inorganic cleaning agent; The organic cleaning agent contains one or more of acetone, ethanol, isopropanol and the like; The inorganic cleaning agent contains one or more of sulfuric acid, hydrochloric acid, hydrogen peroxide and the like; In this embodiment, the cleaning agent is a strong acid cleaning solution. The bare silicon wafer is placed in the strong acid cleaning solution and boiled to 100-200 o C, cleaning for 10-40 minutes according to the cleanliness of the silicon wafer, the strong acid cleaning solution is composed of H2SO4 and H2O2, and the volume ratio of H2SO4:H2O2 is 1:10 to 10:1; 12) Use deionized water to clean the bare silicon wafer, and then use nitrogen to blow dry the bare silicon wafer; 13) Depositing photoresist on the surface of the silicon substrate by spin coating or spray coating, the thickness of the photoresist is 10 nm-2 μm, and it may have different degrees of sensitivity to ultraviolet-visible light, deep ultraviolet light, extreme ultraviolet light, and electron beam; the photoresist completely covers the surface of the silicon substrate, and after exposure, baking, and development, a specific pattern with micro-nanoscale precision is formed. The specific pattern is formed by mask exposure, and masks with different patterns are customized according to needs. The photoresist inside the pattern is removed by the developer, and the surface of the silicon substrate is exposed. The photoresist outside the pattern still covers the surface of the silicon substrate. After the pattern is formed, the area of ​​the silicon substrate surface covered by the photoresist is not etched, and the area not covered by the photoresist is etched, thereby forming the horizontal shape of the structure to be etched.

[0022] 14) Rinse the developed silicon wafer again with deionized water and blow dry with nitrogen.

[0023] Step 2, depositing a metal catalyst of a set thickness on the silicon substrate partially covered with the photoresist; In step 2, the material of the metal catalyst is one or more of gold, silver, ruthenium, rhodium, palladium, osmium, iridium, and platinum.

[0024] The substrate silicon wafer obtained in step 1 is cleaned again using a plasma cleaning machine; the silicon wafer is placed in the plasma cleaning machine, the power is adjusted to 100-300W, the cleaning gas is one or more of hydrogen, oxygen, nitrogen, and argon, the flow rate is 10-100sccm, and the plasma cleaning time is 1-15min; Depositing a layer of metal catalyst on a silicon substrate using a magnetron sputtering device, a thermal evaporation device, an electron beam evaporation device, a chemical deposition device or an electrochemical deposition device, wherein the thickness of the metal catalyst is 1-1000 nm, and the thickness uniformity of the metal catalyst is controlled within 3%, and the thickness of the metal catalyst is controlled by controlling the sputtering, evaporation, electron beam evaporation, chemical reaction time or electrochemical deposition time; When using a plasma sputtering metal catalyst, the following steps are included: 1) Use the vacuum system to evacuate the sputtering chamber to 10 -7 After the vacuum degree is 1000 Torr (unit of pressure), argon gas is filled in to reduce the vacuum degree to 1×10 -3 Torr, the hot cathode is heated by electricity, the heating voltage is 50-240V, the cathode emits electrons, and the electrons collide with argon molecules and ionize in the process of moving toward the anode with positive voltage, forming plasma; 2) Under the action of the focusing magnetic field, the plasma is focused into a columnar shape, forming a high-density plasma. The positive ions bombard the target surface under the acceleration of the negative voltage applied to the target (the material to be sputtered), and atoms are sputtered from the target surface; 3) The atoms move in a straight line and deposit on the substrate opposite the target to form a sputtered film. The sputtering time is controlled between 2 and 120 minutes. After the metal catalyst reaches the preset thickness, the heating voltage is turned off. Different targets can be heated simultaneously according to the different compositions of the metal catalyst. 4) After the metal catalyst is deposited, the thickness of the metal catalyst is measured using an ellipsometer, and the thickness of the metal catalyst is adjusted to the set range. The appropriate metal catalyst thickness can ensure a high etching rate, the etching direction is perpendicular to the surface of the silicon substrate, and the etching shape is uniform and repeatable.

[0025] Step 3, based on the metal catalyst prepared in step 2, a porous morphology of a metal catalyst is prepared, and after the preparation is completed, an atomic force microscope (AFM) is used to measure and count the shape, number, diameter, and spacing distribution of the pores 6; As shown in Figure 5, Figure 5 (a) is a schematic diagram of the interface state of a non-porous catalyst before etching, (c) is a schematic diagram of the interface state of a non-porous catalyst after etching, (b) is a schematic diagram of the interface state of a porous catalyst before etching, and (d) is a schematic diagram of the interface state of a porous catalyst after etching; in the process of etching using a traditional non-porous catalyst, the corrosive agent can only be transported to the edge of the cavity area through the side of the catalyst, resulting in the etching rate at the edge of the cavity area being much lower than that in the central area; the present invention creates through pores inside the catalyst, so that the corrosive agent can be transported through the upper surface of the catalyst to the cavity area of ​​the silicon directly below it, therefore, the use of a porous catalyst can significantly improve the uniformity of etching below the catalyst.

[0026] The pores of the catalyst are prepared by the following methods, which can achieve the regulation of pore density, size and distribution, including: Plasma etching method: Use gas phase plasma treatment to create pores on the catalyst. After the catalyst is deposited, add a micro-nano mask with a set pattern to control the shape and distribution of the pores. Gases used in gas phase plasma treatment include argon, nitrogen, chlorine, etc. Micro-nano masks include standard micro-nano patterning methods such as photolithography, electron beam exposure, and micro-nano particle self-assembly.

[0027] After the porous morphology is prepared, the shape, number, diameter, and spacing distribution of the holes are measured and counted by scanning electron microscopy, projection electron microscopy, or atomic force microscopy for the subsequent etching process and structural shape regulation.

[0028] By preparing the porous morphology of the catalyst, the pore density can be controlled from 0 to 50%, where the minimum width of the pore is 0 to 100 nm, and the shape of the pore is regular pores, linear array pores or irregular curve pores, as shown in Figure 2.

[0029] By regulating the shape and distribution of the catalyst pores, uneven etching of the micro-nano structure can be achieved, in which the catalyst curls and deforms after etching, as shown in Figure 4.

[0030] By regulating the shape and distribution of catalyst pores, high aspect ratio etching of micro-nano structures can be achieved, in which the catalyst splits and bifurcates after etching, as shown in Figure 6.

[0031] By regulating the shape and distribution of catalyst pores, high aspect ratio etching of micro-nano structures can be achieved, in which the catalyst remains intact after etching and is located at the bottom of the etched structure. The sidewall of the etched structure has a certain angle with the surface of the silicon substrate, which is inclined or vertical, with an angle range of 50-90 o , as shown in Figure 7.

[0032] By regulating the shape and distribution of catalyst pores, high aspect ratio etching of micro-nano structures can be achieved, in which the catalyst remains intact after etching and is located at the bottom of the etched structure. The sidewall of the etched structure has a certain angle with the surface of the silicon substrate, which is vertical and ranges from 85-90 degrees. o , as shown in Figure 8.

[0033] By regulating the shape and distribution of catalyst pores, high aspect ratio etching of micro-nano structures can be achieved, in which the catalyst remains intact after etching and is located at the bottom of the etched structure. The sidewall of the etched structure has a certain angle with the surface of the silicon substrate, which is vertical and ranges from 85-90 degrees. o , as shown in Figure 9.

[0034] Step 4: Immerse the silicon wafer in an etching solution made of a mixture of oxidant and hydrofluoric acid with different set ratios for etching. The volume of the solution is set according to the size of the substrate area. The etching can be carried out at room temperature to 100o C temperature to obtain silicon holes with high aspect ratio, wherein the silicon holes include channels and holes, and deep silicon etching is realized; the oxidant-hydrofluoric acid mixed molar ratio is 1:1000 to 1000:1.

[0035] The oxidant includes a soluble chemical substance with oxidizing properties, including any of the following: potassium permanganate; Hydrogen peroxide or peroxide; Nitric acid or nitrates; Nitrite or nitrite.

[0036] In the etching solution, the oxidant, hydrofluoric acid and the metal-silicon substrate undergo coupled electrochemical interactions, resulting in chemical dissolution of silicon atoms, thereby etching the silicon substrate.

[0037] The method of this embodiment can ensure the uniformity of etching, and the minimum etching depth variation within a single etching structure is less than 1% of the etching width; 2*2 cm 2 The minimum standard deviation of the depth variation of different etched structures within the etching range can be less than 2%; the etched sidewall can be highly perpendicular to the silicon substrate surface, with an angle of 89-90 o The minimum roughness of the sidewall is less than 20 nm, and the maximum etching speed exceeds 1 μm / minute. The method of the present invention can achieve deep silicon etching of different geometric shapes with a minimum width of less than 1 nm and a maximum width of more than 1000 μm, a maximum depth of more than 500 μm, and a maximum aspect ratio of more than 10:1.

[0038] Example 2 In step 3, the pores of the catalyst are prepared by the following method, which can achieve the regulation of pore density, size and distribution, including: Chemical etching method: Use chemical reagents that corrode the catalyst to make pores on the catalyst. Soak the sample prepared in step 2 in the prepared chemical corrosion reagent for 1 second to 1 hour. Take out the sample, wash it with deionized water, and then dry it with nitrogen. Since there are defects, grain boundaries, and voids in the metal catalyst film, micropores can be formed under the action of a specific proportion of the corrosive agent. The chemical reagent is prepared from one or more of H2SO4, HF, HCl, HNO3, HNO2, KI, and I2 according to a set volume ratio.

[0039] Other technical features are the same as those of Example 1.

[0040] Example 3 In step 3, the pores of the catalyst are prepared by the following method, which can achieve the regulation of pore density, size and distribution, including: Heat treatment method: The catalyst is subjected to high-temperature treatment in a specific atmosphere to generate pores inside the catalyst. The sample prepared in step 2 is placed in a high-temperature furnace, and nitrogen is used as the heating atmosphere to heat the sample to 100-1200 °C. The temperature change curve is observed, and the heating rate and protective gas flow parameters are adjusted to achieve the best experimental effect. The heating time, heating and cooling rate, and protective gas flow parameters are adjusted to avoid excessive cooling or oxidation of the sample. When the temperature drops to room temperature, the sample is taken out.

[0041] Other technical features are the same as those of Example 1.

[0042] Example 4 In step 3, the pores of the catalyst are prepared by the following method, which can achieve the regulation of pore density, size and distribution, including: Surface modification method: Before the catalyst is deposited, the surface of the silicon substrate is physically or chemically treated to give the silicon substrate certain chemical functional groups and different surface energies, thereby inducing spontaneous arrangement of metal atoms during the catalyst deposition process to form a porous structure. The physical treatment includes heating, freezing, laser irradiation, and light irradiation; the chemical treatment includes plasma treatment, acid treatment, alkali treatment, and organic treatment.

[0043] Other technical features are the same as those of Example 1.

[0044] The above is only a preferred example of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various changes and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for deep etching of silicon of a high aspect ratio structure, characterized in that: The following steps are involved: Step 1, exposing the required structural plane on the silicon wafer; Step 2, depositing a metal catalyst of a set thickness on the silicon substrate partially covered with the photoresist; Step 3, based on the metal catalyst prepared in step 2, preparing a porous morphology of a metal catalyst; Step 4, immersing the silicon wafer in an etching solution for etching to obtain silicon holes with a high aspect ratio, wherein the silicon holes include channels and holes, thereby achieving deep silicon etching; The etching solution is prepared by mixing an oxidant and hydrofluoric acid with a set ratio of components.

2. The silicon etching method of a high aspect ratio structure according to claim 1, characterized in that: In step one, include: 11) Cleaning the silicon substrate using a cleaning agent; 12) Use deionized water to clean the bare silicon wafer, and then use nitrogen to blow dry the bare silicon wafer; 13) Depositing photoresist on the surface of the silicon substrate by spin coating or spray coating, the thickness of the photoresist is 10 nm-2 μm; the photoresist completely covers the surface of the silicon substrate, and after exposure, baking, and development in sequence, a specific pattern with micro-nanoscale precision is formed, the specific pattern is formed by mask exposure, and masks with different patterns are customized. The photoresist inside the pattern is removed by the developer, and the surface of the silicon substrate is exposed. The photoresist outside the pattern still covers the surface of the silicon substrate. After the pattern is formed, the area of ​​the silicon substrate surface covered by the photoresist is not etched, and the area not covered by the photoresist is etched, forming the horizontal shape of the structure to be etched; 14) Rinse the developed silicon wafer again with deionized water and blow dry with nitrogen.

3. The silicon etching method of a high aspect ratio structure according to claim 2, characterized in that: In step 11), the cleaning agent includes an organic cleaning agent and an inorganic cleaning agent; The organic cleaning agent contains one or more of acetone, ethanol, and isopropanol; The inorganic cleaning agent contains one or more of sulfuric acid, hydrochloric acid and hydrogen peroxide.

4. The silicon etching method of a high aspect ratio structure according to claim 3, characterized in that: In step 11), the cleaning agent is a strong acid cleaning solution, and the bare silicon wafer is placed in the strong acid cleaning solution and boiled to 100-200 o C. Clean for 10-40 minutes depending on the cleanliness of the silicon wafer. The strong acid cleaning solution is composed of H2SO4 and H2O2, and the volume ratio of H2SO4:H2O2 is 1:10 to 10:

1.

5. The silicon etching method of a high aspect ratio structure according to claim 1, characterized in that: In step 2, the material of the metal catalyst is one or more of gold, silver, ruthenium, rhodium, palladium, osmium, iridium, and platinum.

6. The silicon etching method of a high aspect ratio structure according to claim 5, characterized in that: In step 2, the substrate silicon wafer obtained in step 1 is cleaned again using a plasma cleaning machine; A layer of metal catalyst is deposited on a silicon substrate using magnetron sputtering equipment, thermal evaporation equipment, electron beam evaporation equipment, chemical deposition or electrochemical deposition equipment. The thickness of the metal catalyst is 1-1000 nm. The thickness of the metal catalyst is controlled by controlling the sputtering, evaporation, electron beam evaporation, chemical reaction time or electrochemical deposition time.

7. The silicon etching method of a high aspect ratio structure according to claim 6, characterized in that: In step 2, when a plasma sputtering metal catalyst is selected, the following steps are included: 1) Use the vacuum system to evacuate the sputtering chamber to 10 -7 After the vacuum reaches 1×10 Torr, argon gas is filled in to reduce the vacuum to 1×10 -3 Torr, the hot cathode is heated by electricity, the heating voltage is 50-240V, the cathode emits electrons, and the electrons collide with argon molecules and ionize in the process of moving toward the anode with positive voltage, forming plasma; 2) Under the action of the focusing magnetic field, the plasma is focused into a columnar shape, forming a high-density plasma. The positive ions bombard the target surface under the acceleration of the negative voltage applied to the target, and atoms are sputtered from the target surface; 3) The atoms move in a straight line and deposit on the substrate opposite the target to form a sputtered film. The sputtering time is controlled between 2 and 120 minutes. After the metal catalyst reaches the preset thickness, the heating voltage is turned off. 4) After the metal catalyst deposition is completed, the thickness of the metal catalyst is measured using an ellipsometer and the thickness of the metal catalyst is adjusted to a set range.

8. The silicon etching method of a high aspect ratio structure according to claim 1, characterized in that: In step three, the pore preparation method of the catalyst includes: plasma etching method, chemical etching method, heat treatment method or surface modification method.

9. The silicon etching method of a high aspect ratio structure according to claim 8, characterized in that: In step three, after the porous morphology preparation is completed, the shape, number, diameter, and spacing distribution of the holes are measured and counted by scanning electron microscopy, transmission electron microscopy, or atomic force microscopy for subsequent etching process and structural shape regulation.

10. The silicon etching method of a high aspect ratio structure according to claim 9, characterized in that: In step three, the hole density is 0-99%, the minimum width of the hole is 0-1 micrometer, and the shape of the hole is regular hole, linear array hole or irregular curve hole.

11. The silicon etching method of a high aspect ratio structure according to claim 1, characterized in that: In step 4, the oxidant is one of potassium permanganate, hydrogen peroxide, peroxide, nitric acid, nitrate, nitrite, and nitrite.

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