A z-axis sensitive magneto-electric thin film sensor and a self-assembly preparation method thereof

Abstract

This invention proposes a z-axis sensitive magnetoelectric thin-film sensor and its self-assembly fabrication method, comprising: sequentially epitaxially depositing a sacrificial layer, a bottom electrode layer, a ferroelectric layer, a patterned elongated ferromagnetic layer, and a Si3N4 insulating layer on a substrate; etching the ferroelectric layer down to the sacrificial layer, retaining the ferroelectric layer around the ferromagnetic layer, to obtain a patterned planar thin film to be self-assembled with peripheral supports; coating a fixing layer on one edge of the ferroelectric layer; depositing electrode leads; performing wet etching on the sacrificial layer, causing the planar thin film to be self-assembled to spontaneously curl into a multi-layer roll structure due to the residual tensile stress in the Si3N4 insulating layer; tilting the multi-layer roll structure so that the sensitive axis of the multi-layer roll structure points outward, and performing polarization treatment to obtain the z-axis sensitive magnetoelectric thin-film sensor. This magnetoelectric thin-film sensor is based on magnetoelectric composite materials and has the advantages of low power consumption and high sensitivity, and can realize the integrated fabrication of a z-axis sensitive magnetoelectric sensor.

Description

Technical Field

[0001] This invention belongs to the field of sensor technology, specifically relating to a z-axis sensitive magnetoelectric thin film sensor and its self-assembly preparation method. Background Technology

[0002] With the rapid development of modern industry and technology, the demand for highly sensitive miniature magnetic sensors is increasing, especially in fields such as precision manufacturing, aerospace, geophysical exploration, biomedicine, and defense technology. As a key device for detecting and measuring magnetic fields, the performance of magnetic sensors directly affects the accuracy and reliability of magnetic field measurements. Since magnetic fields are vectors containing both magnitude and direction information, accurate measurement of magnetic fields relies on highly sensitive vector magnetic sensors. The key to constructing vector magnetic sensors lies in developing… z Axis-sensitive magnetic sensor. Therefore, a method is provided that can realize... z The development of axis-sensitive and high-precision micro / nano magnetic sensors has become an urgent problem to be solved.

[0003] at present z Axial magnetic field measurements are mainly achieved through the following methods:

[0004] (1) The planar magnetoresistive sensor with its sensitive axis in the plane is installed vertically, so that the sensitive axis points in the z-axis direction. Chinese Utility Model Patent CN206930767U and Chinese Invention Patent CN102426344B both involve placing the magnetoresistive sensor perpendicular to the plane. z Axial magnetic field measurement. This type of assembled magnetoresistive sensor... z Shaft sensitivity depends on assembly precision, and its consistency is difficult to guarantee. Furthermore, x , y , z The triaxial magnetoresistive sensors are mounted vertically, making it difficult to integrate them into a single manufacturing process, which increases the complexity of the manufacturing process.

[0005] (2) Utilizing the physical effects of the anomalous Hall effect and other physical effects of ferromagnetic thin films with perpendicular magnetic anisotropy to measure the z-axis magnetic field. z Axial magnetic field. For example, Su et al. (Advanced Functional Materials, 2022, 33(10):2211752) and Li et al. (Nature Electronics, 2021, 4(3): 179-184) developed a novel device prototype for detecting vector magnetic fields based on a planar structure using this principle. Chinese invention patent CN101813479B discloses a TMR electronic compass, which uses the giant Hall effect to measure... zDirectional magnetic field. However, Hall-type magnetic sensors have a large driving current, and the accompanying Joule heating leads to thermal noise, which limits further improvement in their sensitivity limit.

[0006] (3) Using magnetic rings, etc. z The axial magnetic field transforms into x , y The magnetic field component in the axial direction. For example, Chinese invention patent CN108303660B uses a flux guide to direct the magnetic field in the vertical direction. z The axial magnetic field is converted into a leakage magnetic field component in the horizontal plane, and then the signal is detected by an in-plane sensitive magnetic sensor. z Measurement of axial magnetic field strength; Chinese invention patents CN117075007B, CN203894395U, CN103901363B, etc., all employ similar technologies, focusing and redirecting magnetic field lines in a vertical plane for measurement within the plane. However, components such as magnetic rings increase the sensor size, making it difficult to meet the requirements for device miniaturization.

[0007] Furthermore, the three types of magnetic sensors mentioned above are all based on magnetoresistive or Hall effects, and their driving currents are relatively large. The accompanying Joule heating leads to thermal noise, which limits further improvements in their sensitivity. In contrast, magnetoelectric sensors made from magnetoelectric composite materials do not require current driving, and the detection limit of micro / nano magnetoelectric sensors can reach the pT level, making them a new generation of highly sensitive magnetic sensors. However, existing micro / nano magnetoelectric sensors involve multiple micro / nano fabrication steps, are complex in process, and their planar structure results in low angular resolution.

[0008] Self-assembly technology, as a low-cost and high-efficiency manufacturing method, offers new possibilities for the fabrication of high-performance vector magnetoelectric sensors. For example, Chinese patent applications CN116106798A and CN115893308A both utilize microrolls formed from thin films with magnetoresistive effects to detect magnetic fields; however, they can only detect the magnitude of the magnetic field and cannot obtain information about its direction. Furthermore, the axial direction of these rolls... x or y The direction cannot be achieved. z It is sensitive to direction. Therefore, there is an urgent need to propose a new type of... z Axis-sensitive magnetoelectric sensor and its self-assembly manufacturing method. Summary of the Invention

[0009] To address the shortcomings and deficiencies of the existing technologies, this invention proposes a z-axis sensitive magnetoelectric thin-film sensor and its self-assembly preparation method. This magnetoelectric thin-film sensor is based on magnetoelectric composite materials and has the advantages of low power consumption and high sensitivity. Furthermore, it can achieve the integrated preparation of a z-axis sensitive magnetoelectric sensor.

[0010] This invention is achieved through the following technical solution:

[0011] In a first aspect, the present invention provides a self-assembly fabrication method for a z-axis sensitive magnetoelectric thin-film sensor, comprising:

[0012] S1, Epitaxially deposit a sacrificial layer on the substrate;

[0013] S2, Epitaxially depositing the bottom electrode layer on the sacrificial layer;

[0014] S3, an epitaxial ferroelectric layer is deposited on the bottom electrode layer;

[0015] S4 uses a combination of photolithography and magnetron sputtering techniques to deposit patterned elongated ferromagnetic layers on the ferroelectric layer;

[0016] S5 uses a combination of photolithography and magnetron sputtering to deposit a Si3N4 insulating layer in the ferromagnetic layer except for the part connected to the electrode pins. The sputtering power of the magnetron sputtering is 500 W to 900 W.

[0017] S6. A combination of photolithography and dry etching is used to etch the ferroelectric layer down to the sacrificial layer, while retaining the ferroelectric layer around the ferromagnetic layer, to obtain a patterned planar thin film with fulcrums around the periphery to be self-assembled.

[0018] S7, A fixing layer is coated on one edge of the ferroelectric layer perpendicular to the elongated ferromagnetic layer to fix the edge of the ferroelectric layer on the substrate;

[0019] S8 uses a combination of photolithography and magnetron sputtering to deposit electrode leads to bring out the bottom electrode layer and the ferromagnetic layer;

[0020] S9, wet etching is performed on the sacrificial layer. Due to the residual tensile stress in the Si3N4 insulating layer, the self-assembled planar thin film spontaneously curls into a multi-layer roll structure.

[0021] S10: After cleaning and freeze-drying the multi-layer roll structure, the multi-layer roll structure is tilted using a micro manipulator and a micro manipulator needle, so that the sensitive axis of the multi-layer roll structure points outward. After polarization treatment, a z-axis sensitive magnetoelectric thin film sensor is obtained.

[0022] Preferably, the substrate is DyScO3.

[0023] Preferably, the sacrificial layer is Sr3Al2O6.

[0024] Preferably, the bottom electrode layer is BaMoO3.

[0025] Preferably, the ferroelectric layer is PMN-PT and the ferromagnetic layer is FeGaB.

[0026] Preferably, the ferroelectric layer is Pb(Zr,Ti)O3 and the ferromagnetic layer is CoFeSiB.

[0027] Preferably, the fixing layer is a negative photoresist.

[0028] Preferably, the aspect ratio of the elongated ferromagnetic layer is greater than 10:1.

[0029] Preferably, pulsed laser deposition is used for deposition in S1 to S3.

[0030] Secondly, the present invention provides a z-axis sensitive magnetoelectric thin film sensor obtained by the self-assembly preparation method described above.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] This invention employs high sputtering power to induce residual tensile stress in the Si3N4 insulating layer, providing a curling driving force for the thin film. This causes the planar thin film to be self-assembled to spontaneously curl into a multilayer roll structure. Due to the anisotropic shape of the patterned elongated ferromagnetic layer, its magnetic easy axis is along the length of the elongated shape, and its sensitive axis is perpendicular to the magnetic easy axis and in-plane. The sensitive axis of the spontaneously curled multilayer roll structure remains parallel to the in-plane direction. By tilting the multilayer roll structure using a micromanipulator and a micromanipulation needle, the sensitive axis of the multilayer roll structure points outward (i.e., ...). z (Axis), after polarization, a magnetic field can be realized based on the magnetoelectric coupling effect. z Z-axis component detection. Compared to the traditional method of vertically mounting planar sensors, the z-axis sensitive magnetoelectric thin-film sensor obtained by this invention can be formed in one step after removing the sacrificial layer, which is simpler in process; compared to the traditional method of using an external magnetic field conversion element to... z The axial magnetic field transforms into x , y The method for detecting the z-axis magnetic field component can be achieved by the z-axis sensitive magnetoelectric thin-film sensor itself in this invention. z The z-axis sensitive magnetoelectric thin-film sensor of this invention requires no additional magnetic field conversion element, and its sensor size is on the micrometer scale, enabling device miniaturization. Compared to traditional Hall-type magnetic sensors, this z-axis sensitive magnetoelectric thin-film sensor requires no current drive, has an angular sensitivity of ±0.1°, and offers advantages such as low power consumption and high sensitivity. Compared to magnetoresistive micro-rolled thin films, this z-axis sensitive magnetoelectric thin-film sensor can measure magnetic field direction information and can achieve magnetic field... z Axis component detection. Attached Figure Description

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

[0034] Figure 1 As a kind z Flowchart of axis-sensitive magnetoelectric thin-film sensor and its self-assembly fabrication method.

[0035] Figure 2 In Example 1 z Magnetoelectric voltage under resonant conditions when an axis-sensitive magnetoelectric thin-film sensor rotates in an out-of-plane AC magnetic field of 2 Oe from 0° to 360°. Detailed Implementation

[0036] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0037] It should be noted that the process equipment or apparatus not specifically mentioned in the following embodiments are all conventional equipment or apparatus in the art.

[0038] It should be noted that the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or apparatuses. Furthermore, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not intended to limit the order of the method steps or define the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0039] like Figure 1 As shown, the self-assembly fabrication method of the z-axis sensitive magnetoelectric thin film sensor of the present invention includes:

[0040] S1, Epitaxially deposit a sacrificial layer on the substrate;

[0041] S2, Epitaxially depositing the bottom electrode layer on the sacrificial layer;

[0042] S3, an epitaxial ferroelectric layer is deposited on the bottom electrode layer;

[0043] S4 uses a combination of photolithography and magnetron sputtering techniques to deposit patterned elongated ferromagnetic layers on the ferroelectric layer; the ferromagnetic layer also serves as the top electrode layer.

[0044] S5 uses a combination of photolithography and magnetron sputtering to deposit a Si3N4 insulating layer in the ferromagnetic layer except for the part connected to the electrode pins. The sputtering power of the magnetron sputtering is 500 W to 900 W.

[0045] S6. A combination of photolithography and dry etching is used to etch the ferroelectric layer down to the sacrificial layer, while retaining the ferroelectric layer around the ferromagnetic layer, to obtain a patterned planar thin film with fulcrums around the periphery to be self-assembled.

[0046] S7, A fixing layer is coated on one edge of the ferroelectric layer perpendicular to the elongated ferromagnetic layer to fix the edge of the ferroelectric layer on the substrate;

[0047] S8 uses a combination of photolithography and magnetron sputtering to deposit electrode leads to bring out the bottom electrode layer and the ferromagnetic layer;

[0048] S9, wet etching is performed on the sacrificial layer. Due to the residual tensile stress in the Si3N4 insulating layer, the self-assembled planar thin film spontaneously curls into a multi-layer roll structure.

[0049] S10: After cleaning and freeze-drying the multi-layer roll structure, the multi-layer roll structure is tilted using a micro manipulator and a micro manipulator needle, so that the sensitive axis of the multi-layer roll structure points outward. After polarization treatment, a z-axis sensitive magnetoelectric thin film sensor is obtained.

[0050] This invention employs high sputtering power to impart residual tensile stress to the Si3N4 insulating layer. This prevents short circuits in the multilayer roll structure and provides a curling driving force for the thin film, enabling the planar thin film to be self-assembled to spontaneously curl into a multilayer roll structure. Furthermore, the curling diameter of the thin film can be controlled by varying the sputtering power.

[0051] Because the patterned elongated ferromagnetic layer of this invention has anisotropic shape, its magnetic easy axis is along the length of the elongated shape, and its sensitive axis is perpendicular to the magnetic easy axis and lies in the plane. The sensitive axis of the spontaneously rolled multilayer structure remains parallel to the plane. By tilting the multilayer rolled structure using a micromanipulator and a micromanipulation pin, the sensitive axis of the multilayer rolled structure points outward. After polarizing the device through electrode pins, a magnetic field can be realized based on the magnetoelectric coupling effect. z Axis component detection.

[0052] In this invention, the substrate is an oxide single crystal substrate, such as DyScO3; the sacrificial layer is a thin film layer that can be completely removed by wet etching, such as Sr3Al2O6; and the bottom electrode layer can be BaMoO3.

[0053] In this invention, the ferroelectric layer can be lead zirconate titanate (Pb(Zr,Ti)O3), lead magnesium niobate-lead titanate (PMN-PT), etc., and the ferromagnetic layer can be FeGaB, CoFeSiB, etc. To improve the coupling between the ferromagnetic layer and the piezoelectric layer and increase the magnetoelectric coupling response, the thickness of the ferromagnetic layer film is greater than or equal to the thickness of the piezoelectric layer film. The aspect ratio of the elongated ferromagnetic layer is greater than 10:1.

[0054] The electrode pins described in this invention can be Au, Pt, etc.

[0055] The multi-layer roll structure of this invention is rinsed 2-3 times in deionized water, and the deionized water is removed by freeze-drying technology. Then, the multi-layer roll structure is tilted inward by a micro manipulator and a micro manipulator needle, so that its sensitive axis points outward.

[0056] Example 1: Based on lead magnesium niobate-lead titanate (Pb(Mg) 1 / 3 Nb 2 / 3 z-axis sensitive magnetoelectric thin film sensor of (PbTiO3, PMN-PT) / FeGaB.

[0057] This embodiment provides a PMN-PT / FeGaB-based solution. z An axis-sensitive magnetoelectric thin-film sensor includes a DyScO3 substrate and a rectangular thin film. The thin film consists of, from bottom to top, a BaMoO3 bottom electrode layer, a PMN-PT ferroelectric layer, a FeGaB ferromagnetic layer, and a Si3N4 insulating layer. The FeGaB ferromagnetic layer is located at one end of the PMN-PT ferroelectric layer, and the other end of the PMN-PT ferroelectric layer is fixed to the substrate by an SU8 fixing layer. An Au lead layer leads the BaMoO3 bottom electrode layer and the FeGaB ferromagnetic layer out from the other end of the PMN-PT ferroelectric layer. The end of the thin film with the FeGaB ferromagnetic layer has a multi-layer roll structure, and the axis of the multi-layer roll structure is perpendicular to the substrate.

[0058] The implementation steps of this embodiment are as follows:

[0059] Step 1: An epitaxial Sr3Al2O6 sacrificial layer is deposited on a DyScO3 substrate using pulsed laser deposition.

[0060] (1-1) Pretreatment of substrate: The (001) oriented DyScO3 substrate was placed in acetone, alcohol and deionized water in sequence, ultrasonically cleaned for 10 minutes in sequence, and dried with dry nitrogen. Then the substrate was placed in an ultraviolet ozone cleaner for 15 minutes to ensure that the substrate surface was clean and dust-free.

[0061] (1-2) A Sr3Al2O6 sacrificial layer film was deposited on a DyScO3 substrate using pulsed laser deposition. The deposition conditions included: DyScO3 substrate heating temperature of 800 ℃, laser energy of 0.8 W, laser frequency of 3 Hz, working gas of O2 with an oxygen pressure of 20 Pa, and deposition time of 5 min, resulting in a Sr3Al2O6 sacrificial layer film with a thickness of approximately 20 nm. The lattice constant of cubic Sr3Al2O6 is a = 15.844 Å, and the pseudo-cubic lattice constant of DyScO3 is a = 3.946 Å. Since 15.844 Å / 4 = 3.96 Å is slightly larger than 3.946 Å, the Sr3Al2O6 sacrificial layer can be epitaxially grown on the DyScO3 substrate. Sr3Al2O6, as a sacrificial layer, can be completely dissolved by deionized water at room temperature, thereby completely releasing the upper functional film.

[0062] Step 2: A BaMoO3 bottom electrode layer is epitaxially deposited on the Sr3Al2O6 sacrificial layer using pulsed laser deposition.

[0063] The specific process is as follows: A BaMoO3 bottom electrode layer film is deposited on a Sr3Al2O6 sacrificial layer using pulsed laser deposition. The deposition conditions include: substrate heating temperature of 650 ℃, laser energy of 0.8 W, laser frequency of 3 Hz, and a high vacuum environment of 3 × 10⁻⁶. - 7 Torr, deposition time 15 min, to obtain a BaMoO3 bottom electrode layer film with a thickness of about 50 nm.

[0064] Because the lattice constant of cubic BaMoO3 is a = 4.04 Å, and the lattice constant of cubic Sr3Al2O6 is a = 15.844 Å, and since 4.04 Å is slightly larger than 15.844 Å / 4 = 3.96 Å, the BaMoO3 layer can be epitaxially grown on the Sr3Al2O6 layer.

[0065] Step 3: A PMN-PT ferroelectric layer thin film is epitaxially deposited on the BaMoO3 bottom electrode layer using pulsed laser deposition.

[0066] The specific process is as follows: a PMN-PT ferroelectric layer film is deposited on the BaMoO3 bottom electrode layer using pulsed laser deposition. The deposition conditions include: substrate heating temperature of 600 ℃, laser energy of 0.8 W, laser frequency of 5 Hz, working gas of O2 with oxygen pressure of 25 Pa, and deposition time of 60 min, resulting in a PMN-PT ferroelectric layer film with a thickness of about 200 nm.

[0067] The PMN-PT ferroelectric layer has a tetragonal phase structure with a lattice constant of a = b = 4.024 Å, while the cubic phase BaMoO3 has a lattice constant of a = 4.04 Å. Because their lattice constants are not significantly different, the PMN-PT ferroelectric layer can be epitaxially grown on the BaMoO3 bottom electrode layer.

[0068] Step 4: On the surface of the PMN-PT ferroelectric layer, a rectangular FeGaB ferromagnetic layer thin film with an in-plane magnetic sensitive axis is deposited by a combination of photolithography and magnetron sputtering to form a PMN-PT / FeGaB magnetoelectric composite thin film.

[0069] (4-1) Spin-coating AR-P 3510T positive photoresist: drop positive photoresist onto the sample surface, spin-coat at 500 rpm for 10 s, spin-coat at 4000 rpm for 50 s, place the sample on a heating stage at 120℃ to dry for 5 min, expose to ultraviolet light for 8 s, and develop in developer for 60 s to pattern the positive photoresist.

[0070] (4-2) A FeGaB ferromagnetic thin film was deposited on the PMN-PT ferroelectric layer using magnetron sputtering. The deposition conditions included: Ar working gas, working pressure 3 mTorr, DC sputtering power 100 W, and deposition time 2500 s, resulting in a 200 nm thick FeGaB ferromagnetic film. The positive photoresist was then removed in acetone. Due to the anisotropic shape of the FeGaB ferromagnetic film, its magnetic easy axis is along the length of the strip, and its magnetic sensitive axis is perpendicular to the magnetic easy axis and in-plane. This resulted in a rectangular FeGaB ferromagnetic layer with an in-plane magnetic sensitive axis, which also served as the top electrode layer.

[0071] Step 5: A patterned Si3N4 insulating layer is deposited on the surface of the FeGaB ferromagnetic layer using a combination of photolithography and magnetron sputtering. High sputtering power is used to give the Si3N4 insulating layer residual tensile stress, which on the one hand prevents short circuits in the multilayer roll structure, and on the other hand provides a rolling driving force for the thin film.

[0072] (5-1) Spin-coating AR-P 3510T positive photoresist: drop the positive photoresist onto the sample surface, spin-coat at 500 rpm for 10 s, spin-coat at 4000 rpm for 50 s, place the sample on a heating stage at 120℃ to dry for 5 min, expose to ultraviolet light for 8 s, and develop in developer for 60 s to pattern the positive photoresist.

[0073] (5-2) A Si3N4 insulating film was deposited on a FeGaB ferromagnetic layer using magnetron sputtering. The deposition conditions included: working gas Ar:N2 = 1:1, working gas pressure 3 mTorr, RF sputtering power 500 W, and deposition time 1000 s, resulting in a 100 nm thick Si3N4 film. The positive photoresist was then removed in acetone. This operation ensured that most of the FeGaB ferromagnetic layer was covered by Si3N4, thus preventing short circuits in the multilayer roll-up structure, while exposing a small portion of the FeGaB ferromagnetic layer for electrode leads. Due to the high sputtering power, the Si3N4 insulating layer exhibited residual tensile stress, which provided the driving force for the film's self-rolling / self-assembly.

[0074] Step six: Spin-coat a thicker protective photoresist layer and expose it with ultraviolet light to pattern it. Then, etch the film down to the sacrificial layer using ion beam etching, fully exposing the bottom electrode layer end face. Remove the photoresist to form a rectangular planar film with supporting points around its perimeter, ready for self-assembly. These supporting points provide support for the z-axis sensitive magnetoelectric sensor, enabling it to operate in a frequency range from DC to several hundred kHz.

[0075] (6-1) Spin-coating AR-P 3220 positive photoresist: drop positive photoresist onto the thin film surface, spin-coat at 500 rpm for 10 s, spin-coat at 4000 rpm for 50 s, place the sample on a heating stage at 100℃ and dry for 2 min. Repeat the operation 3 times to obtain a photoresist coating of about 30 μm thickness, expose to ultraviolet light to form a patterned protective layer.

[0076] (6-2) The ferroelectric layer was etched using ion beam etching until the sacrificial layer was completely removed, exposing the bottom electrode layer's end face completely while preserving the ferroelectric layer surrounding the ferromagnetic layer. The etching conditions were: vacuum level 8 × 10⁻⁶. -4 The etching process was carried out at Pa, with an anolyte current of 1 A for 50 min. The photoresist protective layer was then removed in acetone.

[0077] Step 7: A fixing layer is formed on the surface of the ferromagnetic layer using photolithography with negative photoresist (SU8) to fix one edge of the ferroelectric layer onto the substrate.

[0078] (7-1) Spin-coating SU8 2000.5 negative photoresist: The negative photoresist was dropped onto the thin film surface and spin-coated at 500 rpm for 10 s, then at 4000 rpm for 50 s. The sample was then dried on a heating stage at 100°C for 5 min to obtain a negative photoresist coating of approximately 0.5 μm thickness. After UV exposure for 10 s, the sample was baked again on a heating stage at 100°C for 5 min, and then developed in a developer for 60 s to form a patterned fixing layer. This operation fixes one edge of the device to the substrate.

[0079] Step 8: Deposit Au pin layers using a combination of photolithography and magnetron sputtering to bring out the top / bottom electrode layers for easy subsequent testing.

[0080] (8-1) Spin-coating AR-P 3510T positive photoresist: drop the positive photoresist onto the sample surface, spin-coat at 500 rpm for 10 s, spin-coat at 4000 rpm for 50 s, place the sample on a heating stage at 120℃ to dry for 5 min, expose to ultraviolet light for 8 s, and develop in developer for 60 s to pattern the positive photoresist.

[0081] (8-2) Deposition of noble metal electrode leads: A layer of noble metal electrode leads, Au, was deposited on the thin film surface by magnetron sputtering. The working gas was Ar, the working pressure was 3 mTorr, the DC sputtering power was 70 W, and the deposition time was 4000 s to obtain a 200 nm thick Au film. Then, the positive photoresist was removed in acetone to obtain a patterned Au lead layer.

[0082] Step nine: Perform wet etching on the sacrificial layer to completely remove it.

[0083] (9-1) The sample was immersed in deionized water, and the Sr3Al2O6 sacrificial layer was wet-etched. Due to the residual tensile stress in the Si3N4 insulating layer, the film self-curled to form a multilayer roll structure as the sacrificial layer dissolved. At this time, the sensitive axis of the multilayer roll structure was still parallel to the plane.

[0084] Step 10: Deionized water is removed using freeze-drying technology. Then, using a micromanipulator and micromanipulation needle, the multi-layered roll structure is tilted inwards, with its sensitive axis pointing outwards, thus achieving magnetic field... z Axis component detection. A highly sensitive method is established by polarizing the device at 100℃ and a 200 kV / cm DC electric field for 20 minutes. z Axis-sensitive magnetoelectric thin-film sensors, such as Figure 2 As shown, its angular sensitivity is ±0.1°.

[0085] Example 2: z-axis sensitive magnetoelectric thin film sensor based on lead zirconate titanate (Pb(Zr,Ti)O3) / CoFeSiB.

[0086] This embodiment provides a lead zirconate titanate (Pb(Zr,Ti)O3) / CoFeSiB-based solution. zAn axis-sensitive magnetoelectric thin-film sensor includes a DyScO3 substrate and a rectangular thin film. The thin film, from bottom to top, consists of a BaMoO3 bottom electrode layer, a Pb(Zr,Ti)O3 ferroelectric layer, a CoFeSiB ferromagnetic layer, and a Si3N4 insulating layer. The CoFeSiB ferromagnetic layer is located at one end of the Pb(Zr,Ti)O3 ferroelectric layer, and the other end of the Pb(Zr,Ti)O3 ferroelectric layer is fixed to the substrate by an SU8 fixing layer. An Au lead layer leads the BaMoO3 bottom electrode layer and the CoFeSiB ferromagnetic layer out from the other end of the Pb(Zr,Ti)O3 ferroelectric layer. The end of the thin film with the CoFeSiB ferromagnetic layer has a multi-layer roll structure, and the axis of the multi-layer roll structure is perpendicular to the substrate.

[0087] The implementation steps of this embodiment are as follows:

[0088] Step 1: An epitaxial Sr3Al2O6 sacrificial layer is deposited on a DyScO3 substrate using pulsed laser deposition.

[0089] (1-1) Pretreatment of substrate: The (001) oriented DyScO3 substrate was placed in acetone, alcohol and deionized water in sequence, ultrasonically cleaned for 10 minutes in sequence, and dried with dry nitrogen. Then the substrate was placed in an ultraviolet ozone cleaner for 15 minutes to ensure that the substrate surface was clean and dust-free.

[0090] (1-2) A Sr3Al2O6 sacrificial layer film was deposited on a DyScO3 substrate using pulsed laser deposition. The deposition conditions included: DyScO3 substrate heating temperature of 800 ℃, laser energy of 0.8 W, laser frequency of 3 Hz, working gas of O2 with an oxygen pressure of 20 Pa, and deposition time of 5 min, resulting in a Sr3Al2O6 sacrificial layer film with a thickness of approximately 20 nm. The lattice constant of cubic Sr3Al2O6 is a = 15.844 Å, and the pseudo-cubic lattice constant of DyScO3 is a = 3.946 Å. Since 15.844 Å / 4 = 3.96 Å is slightly larger than 3.946 Å, the Sr3Al2O6 layer can be epitaxially grown on the DyScO3 substrate. As a sacrificial layer, Sr3Al2O6 can be completely dissolved by deionized water at room temperature, thereby completely releasing the upper functional film.

[0091] Step 2: A BaMoO3 bottom electrode layer is epitaxially deposited on the Sr3Al2O6 sacrificial layer using pulsed laser deposition.

[0092] The specific process is as follows: A BaMoO3 bottom electrode layer film is deposited on a Sr3Al2O6 sacrificial layer using pulsed laser deposition. The deposition conditions include: substrate heating temperature of 650 ℃, laser energy of 0.8 W, laser frequency of 3 Hz, and a high vacuum environment of 3 × 10⁻⁶. - 7Torr, deposition time 15 min, to obtain a BaMoO3 bottom electrode layer film with a thickness of about 50 nm.

[0093] The lattice constant of cubic BaMoO3 is a = 4.04 Å, and the lattice constant of cubic Sr3Al2O6 is a = 15.844 Å. Since 4.04 Å is slightly larger than 15.844 Å / 4 = 3.96 Å, the BaMoO3 layer can be epitaxially grown on the Sr3Al2O6 layer.

[0094] Step 3: Pb(Zr,Ti)O3 ferroelectric single-crystal thin film is epitaxially deposited on the BaMoO3 bottom electrode layer using pulsed laser deposition.

[0095] The specific process is as follows: Pb(Zr,Ti)O3 ferroelectric layer film is deposited on BaMoO3 bottom electrode layer using pulsed laser deposition. The deposition conditions include: substrate heating temperature 650 ℃, laser energy 0.8 W, laser frequency 5 Hz, working gas O2 with oxygen pressure of 26 Pa, and deposition time 60 min, resulting in a Pb(Zr,Ti)O3 ferroelectric layer film with a thickness of about 200 nm.

[0096] The Pb(Zr,Ti)O3 ferroelectric layer has a tetragonal phase structure with a lattice constant of a = b = 4.017 Å, while the cubic phase BaMoO3 has a lattice constant of a = 4.04 Å. Because their lattice constants are not significantly different, the Pb(Zr,Ti)O3 ferroelectric layer can be epitaxially grown on the BaMoO3 bottom electrode layer.

[0097] Step 4: On the surface of the Pb(Zr,Ti)O3 ferroelectric layer, a rectangular (length-to-width ratio = 10:1) CoFeSiB ferromagnetic thin film layer with an in-plane magnetic sensitive axis is deposited by a combination of photolithography and magnetron sputtering to form a Pb(Zr,Ti)O3 / CoFeSiB magnetoelectric composite thin film.

[0098] (4-1) Spin-coating AR-P 3510T positive photoresist: drop positive photoresist onto the sample surface, spin-coat at 500 rpm for 10 s, spin-coat at 4000 rpm for 50 s, place the sample on a heating stage at 120℃ to dry for 5 min, expose to ultraviolet light for 8 s, and develop in developer for 60 s to pattern the positive photoresist.

[0099] (4-2) A CoFeSiB ferromagnetic film was deposited on a Pb(Zr,Ti)O3 ferroelectric layer using magnetron sputtering. The deposition conditions included: Ar gas as the working gas, a working pressure of 3 mTorr, a DC sputtering power of 120 W, and a deposition time of approximately 2000 s, resulting in a 200 nm thick CoFeSiB ferromagnetic film. The positive photoresist was then removed in acetone. Due to the anisotropic shape of the CoFeSiB ferromagnetic film, its magnetic easy axis is along the length of the strip, and its magnetic sensitive axis is perpendicular to the magnetic easy axis and lies in the plane. This resulted in a rectangular CoFeSiB ferromagnetic layer with an in-plane magnetic sensitive axis.

[0100] Step 5: A patterned Si3N4 insulating layer is deposited on the surface of the CoFeSiB ferromagnetic layer using a combination of photolithography and magnetron sputtering. High sputtering power is used to give the CoFeSiB ferromagnetic layer residual tensile stress, which on the one hand prevents short circuits in the multilayer roll structure, and on the other hand provides a rolling driving force for the thin film.

[0101] (5-1) Spin-coating AR-P 3510T positive photoresist: drop the positive photoresist onto the sample surface, spin-coat at 500 rpm for 10 s, spin-coat at 4000 rpm for 50 s, place the sample on a heating stage at 120℃ to dry for 5 min, expose to ultraviolet light for 8 s, and develop in developer for 60 s to pattern the positive photoresist.

[0102] (5-2) A Si3N4 insulating film was deposited on a CoFeSiB ferromagnetic layer using magnetron sputtering. The deposition conditions included: working gas Ar:N2 = 1:1, working gas pressure 3 mTorr, RF sputtering power 900 W, and deposition time 600 s, resulting in a 90 nm thick Si3N4 film. The positive photoresist was then removed in acetone. This operation ensured that most of the CoFeSiB film was covered by Si3N4, preventing short circuits in the multilayer roll-up structure, while exposing a small portion of the CoFeSiB film for electrode leads. Due to the high sputtering power, the Si3N4 insulating layer exhibited residual tensile stress, which provided the driving force for the film's self-rolling / self-assembly.

[0103] Step six: Spin-coat a thicker protective photoresist layer and expose it under ultraviolet light to pattern it. Then, etch the film down to the sacrificial layer using ion beam etching, fully exposing the bottom electrode layer end face. Remove the photoresist to form a rectangular planar film with supporting points around its perimeter, ready for self-assembly. These supporting points provide support for the z-axis sensitive magnetoelectric sensor, enabling it to operate at higher frequencies.

[0104] (6-1) Spin-coating AR-P 3220 positive photoresist: drop positive photoresist onto the thin film surface, spin-coat at 500 rpm for 10 s, spin-coat at 4000 rpm for 50 s, place the sample on a heating stage at 100℃ and dry for 2 min, repeat the operation 3 times to obtain a positive photoresist coating of about 30 μm thickness, expose to ultraviolet light to form a patterned protective layer.

[0105] (6-2) The ferroelectric layer was etched using ion beam etching until the sacrificial layer was completely removed, exposing the bottom electrode layer's end face completely while preserving the ferroelectric layer surrounding the ferromagnetic layer. The etching conditions were: vacuum level 8 × 10⁻⁶. -4 The etching process was carried out at Pa, with an anolyte current of 1 A for 60 min. The photoresist was then removed in acetone.

[0106] Step 7: A fixing layer is formed on the surface of the ferromagnetic layer using photolithography with negative photoresist (SU8) to fix one edge of the ferroelectric layer onto the substrate.

[0107] (7-1) Spin-coating SU8 2000.5 negative photoresist: The negative photoresist was dropped onto the thin film surface and spin-coated at 500 rpm for 10 s, then at 4000 rpm for 50 s. The sample was then dried on a heating stage at 100°C for 5 min to obtain a negative photoresist coating of approximately 0.5 μm thickness. After UV exposure for 10 s, the sample was baked again on a heating stage at 100°C for 5 min, and then developed in a developer for 60 s to form a patterned fixing layer. This operation fixes one edge of the device to the substrate.

[0108] Step 8: Deposit an Au pin layer using a combination of photolithography and magnetron sputtering to bring out the top / bottom electrodes for easy subsequent testing.

[0109] (8-1) Spin-coating AR-P 3510T positive photoresist: drop the positive photoresist onto the sample surface, spin-coat at 500 rpm for 10 s, spin-coat at 4000 rpm for 50 s, place the sample on a heating stage at 120℃ to dry for 5 min, expose to ultraviolet light for 8 s, and develop in developer for 60 s to pattern the positive photoresist.

[0110] (8-2) Deposition of noble metal electrode leads: A layer of noble metal electrode leads, Au, was deposited on the thin film surface by magnetron sputtering. The working gas was Ar, the working pressure was 3 mTorr, the DC sputtering power was 70 W, and the deposition time was 4000 s to obtain a 200 nm thick Au film. Then, the positive photoresist was removed in acetone to obtain a patterned Au lead layer.

[0111] Step nine: Perform wet etching on the sacrificial layer to completely remove it.

[0112] (9-1) The sample was immersed in deionized water, and the Sr3Al2O6 sacrificial layer was wet-etched. Due to the residual tensile stress in the Si3N4 insulating layer, the film self-curled to form a multilayer roll structure as the sacrificial layer dissolved. At this time, the sensitive axis of the multilayer roll structure was still parallel to the plane.

[0113] Step 10: Deionized water is removed using freeze-drying technology. Then, using a micromanipulator and micromanipulation needle, the multi-layered roll structure is tilted inwards, with its sensitive axis pointing outwards, thus achieving magnetic field... z Axis component detection. A highly sensitive method is established by polarizing the device at 100℃ and a 200 kV / cm DC electric field for 20 minutes. z The axis-sensitive magnetoelectric thin-film sensor has an angular sensitivity of ±0.2°.

Claims

1. A self-assembly fabrication method for a z-axis sensitive magnetoelectric thin-film sensor, characterized in that, include: S1, Epitaxially deposit a sacrificial layer on the substrate; S2, Epitaxially depositing the bottom electrode layer on the sacrificial layer; S3, an epitaxial ferroelectric layer is deposited on the bottom electrode layer; S4 uses a combination of photolithography and magnetron sputtering techniques to deposit patterned elongated ferromagnetic layers on the ferroelectric layer; S5 uses a combination of photolithography and magnetron sputtering to deposit a Si3N4 insulating layer in the ferromagnetic layer except for the part connected to the electrode pins. The sputtering power of the magnetron sputtering is 500 W to 900 W. S6. A combination of photolithography and dry etching is used to etch the ferroelectric layer down to the sacrificial layer, while retaining the ferroelectric layer around the ferromagnetic layer, to obtain a patterned planar thin film with fulcrums around the periphery to be self-assembled. S7, A fixing layer is coated on one edge of the ferroelectric layer perpendicular to the elongated ferromagnetic layer to fix the edge of the ferroelectric layer on the substrate; S8 uses a combination of photolithography and magnetron sputtering to deposit electrode leads to bring out the bottom electrode layer and the ferromagnetic layer; S9, wet etching is performed on the sacrificial layer. Due to the residual tensile stress in the Si3N4 insulating layer, the self-assembled planar thin film spontaneously curls into a multi-layer roll structure. S10: After cleaning and freeze-drying the multi-layer roll structure, the multi-layer roll structure is tilted using a micro manipulator and a micro manipulator needle, so that the sensitive axis of the multi-layer roll structure points outward. After polarization treatment, a z-axis sensitive magnetoelectric thin film sensor is obtained.

2. The self-assembly fabrication method of the z-axis sensitive magnetoelectric thin-film sensor according to claim 1, characterized in that, The substrate is DyScO3.

3. The self-assembly fabrication method of the z-axis sensitive magnetoelectric thin-film sensor according to claim 1, characterized in that, The sacrificial layer is Sr3Al2O6.

4. The self-assembly fabrication method of the z-axis sensitive magnetoelectric thin-film sensor according to claim 1, characterized in that, The bottom electrode layer is BaMoO3.

5. The self-assembly fabrication method of the z-axis sensitive magnetoelectric thin-film sensor according to claim 1, characterized in that, The ferroelectric layer is PMN-PT, and the ferromagnetic layer is FeGaB.

6. The self-assembly fabrication method of the z-axis sensitive magnetoelectric thin-film sensor according to claim 1, characterized in that, The ferroelectric layer is Pb(Zr,Ti)O3, and the ferromagnetic layer is CoFeSiB.

7. The self-assembly fabrication method of the z-axis sensitive magnetoelectric thin-film sensor according to claim 1, characterized in that, The fixing layer is a negative photoresist.

8. The self-assembly fabrication method of the z-axis sensitive magnetoelectric thin-film sensor according to claim 1, characterized in that, The aspect ratio of the elongated ferromagnetic layer is greater than 10:

1.

9. The self-assembly fabrication method of the z-axis sensitive magnetoelectric thin-film sensor according to claim 1, characterized in that, In S1 to S3, pulsed laser deposition was used for deposition.

10. A z-axis sensitive magnetoelectric thin film sensor obtained by the self-assembly preparation method according to any one of claims 1 to 9.

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