A microcavity magnetic sensing device and its fabrication method

Abstract

This invention provides a microcavity magnetic sensing device and its fabrication method. The fabrication method of the microcavity magnetic sensing device includes: step S10, providing a substrate, fabricating a first insulating layer on the substrate, and fabricating a groove at the middle position of the first insulating layer corresponding to the substrate; step S20, depositing a super magnetostrictive thin film in the groove; step S30, fabricating a second insulating layer covering the super magnetostrictive thin film on the first insulating layer; step S40, using an overlay process, fabricating a disk pattern covered with photoresist on the substrate, using the disk pattern covered with photoresist as a barrier layer, and etching the side surface of the insulating layer to obtain a microcavity structure encapsulating the super magnetostrictive thin film. This invention adopts a scheme in which the insulating layer completely encapsulates the super magnetostrictive thin film, which can effectively prevent acidic solutions from damaging the super magnetostrictive thin film without reducing the quality of the microcavity structure. It has the advantages of low cost, simple etching equipment, easy maintenance, and no damage to the magnetic film performance.

Description

Technical Field

[0001] This invention relates to the field of magnetic field measurement technology, and more specifically, to a microcavity magnetic sensing device and its fabrication method. Background Technology

[0002] With the development and progress of modern science and technology, magnetic sensing technology, as an indispensable technological means, has been widely applied in various fields such as biomedicine, geophysics, space exploration, and military defense. It holds significant importance from the perspectives of human health, social development, technological progress, and national defense. Optical microcavities can simultaneously constrain light fields in both spatial and temporal dimensions, thereby enhancing the interaction between light and matter. They are widely used in research fields such as optical frequency combs, microlasers, high-sensitivity sensors, nonlinear optics, optical information processing, cavity optomechanics, and quantum information. Among these, whispering-gallery mode microcavities possess ultra-high quality factors and small mode volumes, offering unique advantages in enhancing light-matter interactions. Furthermore, their small size, ease of fabrication, and suitability for large-scale integration make them a current academic frontier in microcavity research.

[0003] Microcavity-based magnetic sensing devices are fabricated as a single unit using micro-nano fabrication processes. Under the influence of an external magnetic field, the supermagnetic-strict film deforms, leading to deformation of the whispering-gallery mode optical microcavity, which in turn causes a change in the optical signal within the microcavity. This electrical signal contains information about the magnetic field being measured. The microcavity-based magnetic sensing device exhibits ultra-high sensitivity due to the combined enhancement of optical and mechanical resonances. Its advantages, including high precision, low power consumption, wide bandwidth, mass production capability, good repeatability, and resistance to electromagnetic interference, coupled with excellent scalability, make it a cutting-edge field in high-precision magnetic field measurement technology with immense development potential, becoming a research hotspot in recent years. However, its practical application is still significantly limited by the bulky measurement equipment. Furthermore, existing cavity-based optical-magnetic sensors suffer from numerous shortcomings in their probe components, such as complex fabrication processes, high manufacturing costs, low yield, and poor reliability, making it difficult to meet military and civilian needs.

[0004] Therefore, a novel microcavity magnetic sensing device and its fabrication method are needed to address the current limitations of using dry (XeF2, RIE, ICP) and wet (hydrofluoric acid / nitric acid mixed solution) methods for isotropic silicon etching to fabricate ultra-high-quality microcavities. However, these methods have significant drawbacks: dry isotropic silicon etching requires large-scale etching equipment, which is expensive, and the etching gases are toxic, making maintenance relatively difficult and costly; wet isotropic silicon etching solutions are highly corrosive to magnetic films, damaging them. Therefore, a low-cost, easy-to-maintain method that does not damage magnetic films for fabricating microcavity magnetic sensing devices has a very broad application prospect. Summary of the Invention

[0005] This invention provides a microcavity magnetic sensor and its fabrication method, which solves the current problem of widely using dry (XeF2, RIE, ICP) and wet (hydrofluoric acid / nitric acid mixed solution) methods for isotropic silicon etching to prepare ultra-high-quality microcavities. However, these methods also have significant drawbacks: dry isotropic silicon etching requires large-scale etching equipment, which is expensive, and the etching gases are toxic, making maintenance relatively difficult and costly; wet isotropic silicon etching solutions are highly corrosive to magnetic films, damaging them. Therefore, a low-cost, easy-to-maintain method that does not damage magnetic films for the fabrication of microcavity magnetic sensors has a very broad application prospect.

[0006] To solve the above problems, the technical solution provided by the present invention is as follows:

[0007] This invention provides a method for fabricating a microcavity magnetic sensing device, the method comprising:

[0008] Step S10: Provide a substrate, prepare a first insulating layer on the substrate, and prepare a groove in the first insulating layer at the middle position corresponding to the substrate;

[0009] Step S20: Deposit a super magnetostrictive thin film in the groove;

[0010] Step S30: A second insulating layer is prepared on the first insulating layer, and the second insulating layer is covered with a super magnetostrictive film;

[0011] Step S40: Using an overlay etching process, a disk pattern covered with photoresist is prepared on the substrate, and the disk pattern covers the groove; using the disk pattern covered with photoresist as a barrier layer, the sides of the first insulating layer and the second insulating layer are etched to obtain a microcavity structure encapsulating a super magnetostrictive film.

[0012] According to an optional embodiment of the present invention, the substrate is a single-crystal silicon wafer, and the first insulating layer is a first silicon dioxide oxide layer;

[0013] Step S10 specifically includes: providing a single-crystal silicon wafer, preparing a first silicon dioxide oxide layer on the single-crystal silicon wafer, and using photolithography and buffered hydrofluoric acid etching to obtain a circular groove on the surface of the first silicon dioxide oxide layer, wherein the depth of the circular groove is less than the thickness of the first silicon dioxide oxide layer.

[0014] According to an optional embodiment of the present invention, the second insulating layer is a second silicon dioxide oxide layer;

[0015] Step S30 specifically includes: depositing a second silicon dioxide oxide layer on the first silicon dioxide oxide layer using plasma-enhanced vapor deposition, so that the super magnetostrictive film is completely encapsulated in the silicon dioxide oxide layer to prevent oxidation and damage to the super magnetostrictive film.

[0016] According to an optional embodiment of the present invention, step S40 specifically includes:

[0017] Step S41: Using an overlay process, a disk pattern covered with photoresist is prepared above the surface of the second silicon dioxide oxide layer, and the size of the disk pattern is larger than the size of the circular groove.

[0018] Step S42: Using the disk pattern covered with photoresist as a barrier layer, the first silicon dioxide oxide layer and the second silicon dioxide oxide layer are etched using a buffered hydrofluoric acid etching method, so that the silicon dioxide oxide layer encapsulating the super magnetostrictive film forms a disk structure with a preset tilt angle and a preset thickness.

[0019] Step S43: A mixed solution of hydrofluoric acid, nitric acid and acetic acid is used as an etching solution to perform wet etching on the silicon substrate to remove the disk pattern covered with photoresist, thereby obtaining a microcavity structure wrapped with a super magnetostrictive film.

[0020] According to an optional embodiment of the present invention, the method of photolithography and buffered hydrofluoric acid etching in step S10 includes the following steps:

[0021] S11, Monocrystalline silicon wafer cleaning: Use acetone, isopropanol, anhydrous ethanol and deionized water to ultrasonically clean the monocrystalline silicon wafer to remove organic contaminants, and then use a plasma desmearer to clean the monocrystalline silicon wafer for 5 minutes at 500W power.

[0022] S12, Surface modification: The cleaned monocrystalline silicon wafer from step S11 is placed on the spin coater turntable and rotated. Hexamethyldisilane is dropped onto the first silicon dioxide oxide layer on the surface of the monocrystalline silicon wafer.

[0023] S13, Spin photoresist: A negative photoresist is coated onto the first silicon dioxide oxide layer on the surface of the modified single-crystal silicon wafer in step S12. The photoresist is then uniformly coated onto the oxide layer on the surface of the modified single-crystal silicon wafer by rotating a spin coater. After completion, a soft baking treatment is performed at 110°C for 90s. The spin coater parameters are: 5s@500rpm, 30s@2000rpm.

[0024] S14, a photomask is placed over the single-crystal silicon wafer coated with negative photoresist obtained in step S13, and then exposed under ultraviolet light with an exposure energy of 186 mJ / cm2. After exposure, the single-crystal silicon wafer is post-baked at 110°C for 90 s. The photomask is circular. The photomask is a common circular shape with a diameter generally between 70 and 200 μm. The photomask is arranged in an array of multiple circles.

[0025] S15, the single crystal silicon wafer obtained in step S14 is immersed in a developing solution, the developing solution being AZ300MIF, and the developing time being 120s; finally, it is baked again on a hot plate for 2min@100℃ and 10min@110℃ to solve the problem of photoresist bleaching in a buffered hydrofluoric acid solution.

[0026] S16, the single-crystal silicon wafer obtained in step S15 is immersed in a buffered hydrofluoric acid solution, wherein the buffered hydrofluoric acid solution is prepared by mixing hydrofluoric acid (49 wt.%) and ammonium fluoride (40 wt.%) in a volume ratio of (1:6); the negative photoresist is used as an etching mask to etch away a certain thickness of the oxide layer not covered by the negative photoresist, forming a silicon dioxide circular groove on the single-crystal silicon wafer.

[0027] According to an optional embodiment of the present invention, the buffered hydrofluoric acid solution in step S42 is prepared by mixing hydrofluoric acid (49 wt.%) and ammonium fluoride (40 wt.%) in a volume ratio of (1:6); in step S43, the volume ratio of hydrofluoric acid, nitric acid, and acetic acid in the etching solution is 1:89:10; the concentration of hydrofluoric acid used in the etching solution is 49 wt.%, the concentration of nitric acid used in the etching solution is 69.3 wt.%, and the concentration of acetic acid used in the etching solution is 99.9 wt.%.

[0028] According to an optional embodiment of the present invention, the thickness of the first insulating layer and the second insulating layer is 2μm-4μm.

[0029] According to an optional embodiment of the present invention, the super magnetostrictive film is prepared using a super magnetostrictive material, wherein the super magnetostrictive material is Terfenol-D (terbium-dysprosium-iron TbDyFe) or Galfenol (FeGa); wherein the cross-sectional shape of the microcavity structure encapsulating the super magnetostrictive film is an isosceles trapezoid.

[0030] Based on the fabrication method of the microcavity magnetic sensing device in the above embodiments, the present invention also provides a microcavity magnetic sensing device, the microcavity magnetic sensing device comprising a substrate, an insulating layer located on the substrate, and a super magnetostrictive thin film located within the insulating layer; the insulating layer forms a microcavity structure, the super magnetostrictive thin film is disposed within the microcavity structure, and the cross-sectional shape of the microcavity structure is an isosceles trapezoid;

[0031] The super magnetostrictive film is made of a super magnetostrictive material, which is Terfenol-D (terbium-dysprosium-iron TbDyFe) or Galfenol (FeGa); the insulating layer is made of silicon dioxide oxide; and the substrate is a single-crystal silicon wafer.

[0032] The beneficial effects of this invention: This invention provides a microcavity magnetic sensing device and its fabrication method. The fabrication method of the microcavity magnetic sensing device includes: step S10, providing a substrate, fabricating a first insulating layer on the substrate, and fabricating a groove at the middle position of the first insulating layer corresponding to the substrate; step S20, fabricating a super magnetostrictive thin film in the groove; step S30, fabricating a second insulating layer on the first insulating layer, and the second insulating layer covering the super magnetostrictive thin film; step S40, using an overlay process, fabricating a disk pattern covered with photoresist on the substrate, and the disk pattern covering the groove; using the disk pattern covered with photoresist as a barrier layer, etching the sides of the first insulating layer and the second insulating layer to obtain a microcavity structure encapsulating the super magnetostrictive thin film. This invention adopts a scheme in which the first insulating layer and the second insulating layer completely encapsulate the super magnetostrictive thin film, which can effectively prevent film oxidation and damage to the super magnetostrictive thin film by wet silicon etching solution without reducing the quality (deformation and sensitivity) of the microcavity structure. It has the advantages of low cost, simple etching equipment, easy maintenance, and no damage to the performance of the magnetic thin film. This invention is not limited to the preparation of magnetic thin films, but can also be used to prepare functional thin film devices such as PZT that are easily soluble in strong acid or strong alkaline solutions. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments or prior art, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figures 1 to 6 This application provides a schematic diagram of the fabrication process of a microcavity magnetic sensing device. Detailed Implementation

[0035] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0036] This invention addresses the current widespread use of dry (XeF2, RIE, ICP) and wet (hydrofluoric acid / nitric acid mixed solution) methods for isotropic silicon etching to prepare ultra-high-quality microcavities, which also have significant drawbacks: dry isotropic silicon etching requires large-scale etching equipment, which is expensive, and the etching gases are toxic, making maintenance relatively difficult and costly; wet isotropic silicon etching solutions are highly corrosive to magnetic films, damaging them. This embodiment solves these defects.

[0037] This invention provides a method for fabricating a microcavity magnetic sensor, the method comprising:

[0038] Step S10: Provide a substrate, prepare a first insulating layer on the substrate, and prepare a groove in the first insulating layer at the middle position corresponding to the substrate;

[0039] Step S20: Deposit a super magnetostrictive thin film in the groove;

[0040] Step S30: A second insulating layer is prepared on the first insulating layer, and the second insulating layer is covered with a super magnetostrictive film;

[0041] Step S40: Using an overlay etching process, a disk pattern covered with photoresist is prepared on the substrate, and the disk pattern covers the groove; using the disk pattern covered with photoresist as a barrier layer, the sides of the first insulating layer and the second insulating layer are etched to obtain a microcavity structure encapsulating a super magnetostrictive film.

[0042] This embodiment employs a scheme where the first and second insulating layers completely encapsulate the magnetostrictive thin film. This effectively prevents film oxidation and damage from wet silicon etching solutions without compromising the quality (deformation and sensitivity) of the microcavity structure. It offers advantages such as low cost, simple etching equipment, easy maintenance, and no damage to the magnetic film's performance. This invention is not limited to the fabrication of magnetic thin films; it can also be used to prepare functional thin-film devices such as PZT, which are easily soluble in strong acid or alkaline solutions. In this embodiment, the magnetostrictive thin film within the microcavity structure elongates or shortens in the magnetization direction, allowing the detector to collect the corresponding deformation signal, thus forming an ultra-high-quality microcavity.

[0043] Specifically, Figures 1 to 6 This application provides a schematic diagram of the fabrication process of a microcavity magnetic sensing device.

[0044] like Figure 1 As shown, the substrate in step S10 is a single-crystal silicon wafer 11, and a first insulating layer is prepared on the single-crystal silicon wafer 11. The first insulating layer is a first silicon dioxide oxide layer 12.

[0045] like Figure 1 and Figure 2 As shown, step S10 specifically includes: providing a single-crystal silicon wafer 11, preparing a first silicon dioxide oxide layer 12 on the single-crystal silicon wafer 11, and using photolithography and buffered hydrofluoric acid etching to obtain a circular groove 121 on the surface of the first silicon dioxide oxide layer 12, wherein the depth of the circular groove 121 is less than the thickness of the first silicon dioxide oxide layer 12.

[0046] The method of photolithography and buffered hydrofluoric acid etching in step S10 includes the following steps:

[0047] S11, monocrystalline silicon wafer 11 cleaning, uses acetone, isopropanol, anhydrous ethanol and deionized water to ultrasonically clean the monocrystalline silicon wafer to remove organic contaminants, and then uses a plasma desmearing machine to clean the monocrystalline silicon wafer for 5 minutes at 500W power.

[0048] S12, Surface modification: The single crystal silicon wafer 11, which was cleaned in step S11, is placed on the spin coater turntable and rotated. Hexamethyldisilane is dropped onto the first silicon dioxide oxide layer 12 on the surface of the single crystal silicon wafer 11.

[0049] S13, Spin photoresist: A negative photoresist is applied to the first silicon dioxide oxide layer 12 on the surface of the modified single-crystal silicon wafer 11 in step S12. The photoresist is then evenly coated on the oxide layer on the surface of the modified single-crystal silicon wafer 11 by rotating a spin coater. After completion, a soft baking treatment is performed on it at 110°C for 90s. The spin coater parameters are: 5s@500rpm, 30s@2000rpm.

[0050] S14, a photomask is placed over the single-crystal silicon wafer 11 covered with negative photoresist obtained in step S13, and then exposed under ultraviolet light with an exposure energy of 186 mJ / cm2. After exposure, the single-crystal silicon wafer 11 is post-baked at 110°C for 90 s. The photomask is circular. The photomask is a common circular shape with a diameter generally between 70 and 200 μm. The photomask is arranged in an array of multiple circular shapes.

[0051] S15, the single crystal silicon wafer 11 obtained in step S14 is immersed in a developing solution, the developing solution being AZ300MIF, and the developing time being 120s; finally, it is baked again on a hot plate for 2min@100℃ and 10min@110℃, which can solve the problem of photoresist bleaching in buffered hydrofluoric acid solution.

[0052] S16, the single-crystal silicon wafer 11 obtained in step S15 is immersed in a buffered hydrofluoric acid solution, wherein the buffered hydrofluoric acid solution is prepared by mixing hydrofluoric acid (49 wt.%) and ammonium fluoride (40 wt.%) in a volume ratio of (1:6); the negative photoresist is used as an etching mask to etch away a certain thickness of the oxide layer not covered by the negative photoresist, forming a silicon dioxide circular groove 121 on the single-crystal silicon wafer 11.

[0053] like Figure 3 As shown, the super magnetostrictive film 13 in step S20 is prepared using a super magnetostrictive material, namely Terfenol-D (terbium-dysprosium-iron TbDyFe) or Galfenol (FeGa), and a layer of super magnetostrictive film 13 is prepared in the circular groove 121. In this embodiment, the super magnetostrictive film is preferably obtained by magnetron sputtering, and the film is preferably a terbium-dysprosium-iron alloy (Terfenol-D) with a composition of Tb x Dy 1-x Fe 1.98-2 , where x = 0.27 - 0.3.

[0054] like Figure 4 As shown, the second insulating layer in step S30 is a second silicon dioxide oxide layer 14. Step S30 specifically includes: depositing a second silicon dioxide oxide layer 14 on the first silicon dioxide oxide layer 12 using physical vapor deposition, so that the supermagnetic-strict film 13 is completely encapsulated in the silicon dioxide oxide layer, which can effectively prevent the oxidation and damage of the supermagnetic-strict film. In this embodiment, the first silicon dioxide oxide layer 12 and the second silicon dioxide oxide layer 14 are an integral structure. The thickness of the first insulating layer and the second insulating layer is 2μm-4μm, that is, the thickness of the first silicon dioxide oxide layer 12 and the second silicon dioxide oxide layer 14 is 2μm-4μm, and both are preferably 3μm thick.

[0055] like Figure 5 As shown, step S40 specifically includes:

[0056] Step S41: Using an overlay process, a disk pattern 15 covered with photoresist is prepared above the surface of the second silicon dioxide oxide layer 14, and the size of the disk pattern 15 is larger than the size of the circular groove 121.

[0057] Step S42: Using the disk pattern 15 covered with photoresist as a barrier layer, the first silicon dioxide oxide layer 12 and the second silicon dioxide oxide layer 14 are etched using a buffered hydrofluoric acid etching method, so that the silicon dioxide oxide layer encapsulating the super magnetostrictive film 13 forms a disk structure with a preset tilt angle and a preset thickness.

[0058] Step S43: A mixed solution of hydrofluoric acid, nitric acid and acetic acid is used as an etching solution to perform wet etching on the disk pattern 15 covered with photoresist to remove the disk pattern 15 covered with photoresist, thereby obtaining a microcavity structure wrapped with a super magnetostrictive film. The cross-sectional shape of the microcavity structure is preferably an isosceles trapezoid. The wedge angle of the cross-section of the microcavity structure can be adjusted and controlled by the type and thickness of the photoresist. The cross-sectional shape of the microcavity structure can also be other shapes, which are not limited here.

[0059] Preferably, the buffered hydrofluoric acid solution in step S42 is prepared by mixing hydrofluoric acid (49 wt.%) and ammonium fluoride (40 wt.%) in a volume ratio of (1:6); the volume ratio of hydrofluoric acid, nitric acid, and acetic acid in the etching solution preparation in step S43 is 1:89:10; the concentration of hydrofluoric acid used in the etching solution preparation is 49 wt.%, the concentration of nitric acid used in the etching solution preparation is 69.3 wt.%, and the concentration of acetic acid used in the etching solution preparation is 99.9 wt.%.

[0060] In this embodiment, a mixed solution of hydrofluoric acid, nitric acid, and acetic acid is used for etching instead of dry etching in the preparation process, which improves isotropy and makes the etching method suitable for the preparation of ultra-high quality microcavities. In addition, the scheme of completely encapsulating the super magnetostrictive film with silicon oxide can effectively prevent film oxidation and damage to the film by wet silicon etching solution.

[0061] like Figure 6 As shown, the fabrication method of the microcavity magnetic sensing device further includes: etching the side surface of the single crystal silicon wafer 11 with a mixed solution of hydrofluoric acid, nitric acid and acetic acid to form a hole 111 on the right side and a hole 112 on the left side of the single crystal silicon wafer 11. The holes 111 and 112 are used to release the microcavity magnetic sensing device so that it can move freely.

[0062] Based on the fabrication method of the microcavity magnetic sensing device in the above embodiments, the present invention also provides a microcavity magnetic sensing device, such as... Figure 6 As shown, the microcavity magnetic sensing device 10 includes a substrate 11, an insulating layer 18 located on the substrate 11, and a super magnetostrictive thin film 13 located within the insulating layer 18; the insulating layer 18 forms a microcavity structure, and the super magnetostrictive thin film 13 is disposed within the microcavity structure. The cross-sectional shape of the microcavity structure is an isosceles trapezoid, for example, the right inclined surface 17 and the left inclined surface 16 of the microcavity structure are symmetrical about the longitudinal centerline of the microcavity structure.

[0063] The super magnetostrictive film 13 is prepared using a super magnetostrictive material, which is Terfenol-D (terbium-dysprosium-iron TbDyFe) or Galfenol (FeGa). In this embodiment, the super magnetostrictive film is preferably obtained by magnetron sputtering, and the film is preferably a terbium-dysprosium-iron alloy (Terfenol-D) with a composition of Tb x Dy 1-x Fe 1.98-2 , where x = 0.27 - 0.3.

[0064] The insulating layer 18 is made of silicon dioxide oxide, and the substrate 11 is a single crystal silicon wafer. A hole 111 is formed on the right side of the single crystal silicon wafer, and a hole 112 is formed on the left side. The holes 111 and 112 are used to release the microcavity magnetic sensing device, allowing it to move freely.

[0065] In summary, although the present invention has been disclosed above with reference to preferred embodiments, the above preferred embodiments are not intended to limit the present invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the scope defined in the claims.

Claims

1. A method for fabricating a microcavity magnetic sensing device, characterized in that, include: Step S10: Provide a substrate, prepare a first insulating layer on the substrate, and prepare a groove in the first insulating layer at the middle position corresponding to the substrate; Step S20: Deposit a super magnetostrictive thin film in the groove; Step S30: Prepare a second insulating layer on the first insulating layer, and the second insulating layer covers the super magnetostrictive thin film; Step S40: Use an overlay process to prepare a disk pattern covered with photoresist on the substrate, and the disk pattern covers the groove. Using a photoresist-coated disk pattern as a barrier layer, the sides of the first insulating layer and the second insulating layer are etched to obtain a microcavity structure encapsulating a supermagnetic-strictive film; the substrate is a single-crystal silicon wafer, and the first insulating layer is a first silicon dioxide oxide layer; step S10 specifically includes: providing a single-crystal silicon wafer, preparing a first silicon dioxide oxide layer on the single-crystal silicon wafer, and using photolithography and buffered hydrofluoric acid etching to obtain a circular groove on the surface of the first silicon dioxide oxide layer, the depth of the circular groove being less than the thickness of the first silicon dioxide oxide layer; the second insulating layer is a second silicon dioxide oxide layer; step S30 specifically includes: depositing a second silicon dioxide oxide layer on the first silicon dioxide oxide layer using plasma-enhanced vapor deposition, so that the supermagnetic-strictive film is completely encapsulated in the silicon dioxide oxide layer to prevent oxidation and damage to the supermagnetic-strictive film; step S40 specifically includes: step S41, using an overlay process, preparing a photoresist-coated disk pattern above the surface of the second silicon dioxide oxide layer, and the size of the disk pattern being larger than the size of the circular groove; Step S42: Using the disk pattern covered with photoresist as a barrier layer, the first silicon dioxide oxide layer and the second silicon dioxide oxide layer are etched using a buffered hydrofluoric acid etching method to form a disk structure with a preset tilt angle and a preset thickness in the silicon dioxide oxide layer encapsulating the super magnetostrictive film; Step S43: A mixed solution of hydrofluoric acid, nitric acid and acetic acid is used as an etching solution to perform wet etching on the silicon substrate to remove the disk pattern covered with photoresist, thereby obtaining a microcavity structure encapsulating the super magnetostrictive film.

2. The method for fabricating the microcavity magnetic sensing device as described in claim 1, characterized in that, The method of photolithography and buffered hydrofluoric acid etching in step S10 includes the following steps: S11, cleaning the single-crystal silicon wafer: ultrasonically cleaning the single-crystal silicon wafer with acetone, isopropanol, anhydrous ethanol and deionized water to remove organic contaminants, and then cleaning the single-crystal silicon wafer for 5 minutes at 500W power using a plasma stripper; S12, surface modification: rotating the single-crystal silicon wafer after cleaning in step S11 on a spin coater turntable, and dropping hexamethyldisilane onto the first silicon dioxide oxide layer on the surface of the single-crystal silicon wafer; S13, photoresist spin coating: covering the first silicon dioxide oxide layer on the surface of the single-crystal silicon wafer modified in step S12 with negative photoresist, and spinning the photoresist by rotating the spin coater to make the photoresist evenly cover the oxide layer on the surface of the modified single-crystal silicon wafer, and then performing a soft baking treatment at 110℃ for 90s. The parameters of the spin coater are: 5s@500rpm, 30s@2000rpm. S14, a photomask is placed over the single-crystal silicon wafer coated with negative photoresist obtained in step S13, and then exposed to ultraviolet light with an exposure energy of 186 mJ / cm². 2 After completion, the single-crystal silicon wafer is post-baked at 110°C for 90s; the mask is circular; the mask is a common circle with a diameter between 70 and 200 μm; the mask is arranged in an array of multiple circles; S15, the single-crystal silicon wafer obtained in step S14 is immersed in a developing solution, the developing solution is AZ300MIF, and the developing time is 120s; finally, it is baked again on a hot plate for 2min@100°C and 10min@110°C; S16, the single-crystal silicon wafer obtained in step S15 is immersed in a buffered hydrofluoric acid solution, the buffered hydrofluoric acid solution is prepared by mixing 49wt.% hydrofluoric acid and 40wt.% ammonium fluoride in a volume ratio of 1:6; the negative photoresist is used as an etching mask to etch away a certain thickness of the oxide layer not covered by the negative photoresist, forming a silicon dioxide circular groove on the single-crystal silicon wafer.

3. The method for fabricating the microcavity magnetic sensing device as described in claim 1, characterized in that, The buffered hydrofluoric acid etching solution in step S42 is prepared by mixing 49 wt.% hydrofluoric acid and 40 wt.% ammonium fluoride in a volume ratio of 1:6; in step S43, the volume ratio of hydrofluoric acid, nitric acid, and acetic acid in the etching solution is 1:89:10; the concentration of hydrofluoric acid used in the etching solution is 49 wt.%, the concentration of nitric acid used in the etching solution is 69.3 wt.%, and the concentration of acetic acid used in the etching solution is 99.9 wt.%.

4. The method for fabricating the microcavity magnetic sensing device as described in claim 1, characterized in that, The thickness of the first insulating layer and the second insulating layer is 2μm-4μm.

5. The method for fabricating the microcavity magnetic sensing device as described in claim 1, characterized in that, The super magnetostrictive film is made of a super magnetostrictive material, namely Terfenol-D (TbDyFe) or Galfenol (FeGa); wherein the cross-sectional shape of the microcavity structure encapsulating the super magnetostrictive film is an isosceles trapezoid.

6. A microcavity magnetic sensing device fabricated using the method described in claim 1, characterized in that, The device includes a substrate, an insulating layer situated on the substrate, and a super magnetostrictive thin film situated within the insulating layer. The insulating layer forms a microcavity structure, and the super magnetostrictive thin film is disposed within the microcavity structure, the cross-sectional shape of which is an isosceles trapezoid. The super magnetostrictive thin film is prepared using a super magnetostrictive material, such as Terfenol-D (TbDyFe) or Galfenol (FeGa). The insulating layer is made of silicon dioxide oxide, and the substrate is a single-crystal silicon wafer.

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