Z-axis sensitive magnetoelectric film sensor and self-assembly preparation method thereof

Abstract

The invention provides a z-axis sensitive magnetoelectric film sensor and a self-assembly preparation method thereof. The self-assembly preparation method comprises the following steps: sequentially epitaxially depositing a sacrificial layer, a bottom electrode layer, a ferroelectric layer, a patterned strip-shaped ferromagnetic layer and a Si3N4 insulating layer on a substrate; etching the ferroelectric layer to the sacrificial layer, and reserving the ferroelectric layer around the ferromagnetic layer to obtain a patterned planar film to be self-assembled with fulcrums on the periphery; coating a fixing layer on one edge of the ferroelectric layer; depositing an electrode pin; wet etching is carried out on the sacrificial layer, and due to residual tensile stress in the Si3N4 insulating layer, the to-be-self-assembled planar film is spontaneously curled into a multi-layer roll structure; and dumping the multi-layer roll structure to enable the sensitive shaft of the multi-layer roll structure to point to the out-of-plane direction, and carrying out polarization processing to obtain the z-axis sensitive magnetoelectric film sensor. The magnetoelectric film sensor is prepared based on a magnetoelectric composite material, has the advantages of low power consumption and high sensitivity, and can realize integrated preparation of a z-axis sensitive magnetoelectric sensor.

Description

Technical Field

[0001] The invention belongs to the technical field of sensors, and in particular relates to a z-axis sensitive magnetoelectric thin film sensor and a self-assembly preparation method thereof. Background Art

[0002] With the rapid development of modern industry and technology, the demand for highly sensitive micro magnetic sensors is growing, especially in the fields of precision manufacturing, aerospace, geophysical exploration, biomedicine, and national 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 the magnetic field is a vector containing magnitude and direction information, the accurate measurement of the magnetic field requires the use of highly sensitive vector magnetic sensors. The key to building a vector magnetic sensor is to develop z A magnetic sensor that is sensitive to the axis. In view of this, a method is provided to achieve z Axis-sensitive and high-precision micro-nano magnetic sensors have become a problem that needs to be solved urgently.

[0003] at present z Axis magnetic field measurement is mainly achieved through the following methods: (1) Install the planar magnetoresistive sensor with the sensitive axis in the plane vertically so that the sensitive axis points to the z-axis direction. Both the Chinese utility model patent CN206930767U and the Chinese invention patent CN102426344B are based on placing the magnetoresistive sensor vertically on the plane. z Axis magnetic field measurement. This assembled magnetoresistive sensor z Axis sensitivity depends on assembly accuracy, and its consistency is difficult to guarantee. x , y , z The three-axis magnetoresistive sensors are respectively installed vertically, which makes it difficult to realize the integrated manufacturing of the three-axis magnetoresistive sensors, thereby increasing the complexity of the manufacturing process.

[0004] (2) Using the anomalous Hall effect of ferromagnetic films with perpendicular magnetic anisotropy and other physical effects to measure the sensitivity of 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) used this principle to develop a new device prototype based on a planar structure to detect vector magnetic field. Chinese invention patent CN101813479B discloses a TMR electronic compass that uses the giant Hall effect to measure zHowever, the driving current of the Hall-type magnetic sensor is large, and the accompanying Joule heat causes thermal noise, which limits its sensitivity limit to further improve.

[0005] (3) Use magnetic rings etc. z The axial magnetic field is transformed into x , y For example, Chinese invention patent CN108303660B uses a flux guide to direct the vertical magnetic field component. z The axial magnetic field is converted into a leakage magnetic field component in the horizontal plane, and then the in-plane sensitive magnetic sensor is used to realize the z Measurement of axial magnetic field strength; Chinese invention patents CN117075007B, CN203894395U, CN103901363B, etc. all use similar technologies to gather and turn the magnetic lines of force in the vertical plane into the plane for measurement. However, components such as magnetic rings increase the volume of the sensor, making it difficult to meet the needs of device miniaturization.

[0006] In addition, the above three magnetic sensors are all based on magnetoresistance or Hall effect. Their driving current is large, and the accompanying Joule heat will cause thermal noise, which limits their sensitivity. Magnetoelectric sensors made of magnetoelectric composite materials do not require current drive, and the detection limit of micro-nano magnetoelectric sensors can reach the pT level, which is a new generation of highly sensitive magnetic sensors. However, existing micro-nano magnetoelectric sensors involve multiple micro-nano processing steps, complex processes, and their planar structure leads to low angular resolution.

[0007] As a low-cost and high-efficiency manufacturing method, self-assembly technology provides new possibilities for the preparation of high-performance vector magnetoelectric sensors. For example, Chinese patent applications with application numbers CN116106798A and CN115893308A both use micro-rolls formed by thin films with magnetoresistance effect to detect magnetic fields, but they can only detect the magnitude of the magnetic field and cannot obtain information on the direction of the magnetic field. Moreover, the axial direction of these rolls is x or y Direction, cannot be achieved z Therefore, it is urgent to propose a new z Axis-sensitive magnetoelectric sensor and self-assembly manufacturing method thereof. Summary of the invention

[0008] In view of the defects and shortcomings of the above-mentioned prior art, the present invention proposes a z-axis sensitive magnetoelectric thin film sensor and a self-assembly preparation method thereof. The magnetoelectric thin film sensor is prepared based on a magnetoelectric composite material, has the advantages of low power consumption and high sensitivity, and can realize the integrated preparation of a z-axis sensitive magnetoelectric sensor.

[0009] The present invention is achieved through the following technical solutions: In a first aspect, the present invention provides a self-assembly preparation method of a z-axis sensitive magnetoelectric thin film sensor, comprising: S1, epitaxially depositing a sacrificial layer on a substrate; S2, epitaxially depositing a bottom electrode layer on the sacrificial layer; S3, epitaxially depositing a ferroelectric layer on the bottom electrode layer; S4, depositing a patterned long strip ferromagnetic layer on the ferroelectric layer by combining photolithography and magnetron sputtering technology; S5, using a method combining photolithography and magnetron sputtering technology, deposit Si on the ferromagnetic layer except for the part connected to the electrode pins. 3 N 4 Insulating layer, wherein the sputtering rate of magnetron sputtering is 500 W to 900 W; S6, using a method combining photolithography and dry etching to etch the ferroelectric layer to the sacrificial layer, retaining the ferroelectric layer around the ferromagnetic layer, and obtaining a patterned planar thin film to be self-assembled with a support point around the periphery; S7, coating a fixed layer on an edge of the ferroelectric layer that is perpendicular to the long strip ferromagnetic layer, and fixing the edge of the ferroelectric layer on the substrate; S8, depositing electrode pins by combining photolithography with magnetron sputtering to lead out the bottom electrode layer and the ferromagnetic layer; S9, wet etching the sacrificial layer. 3 N 4 The residual tensile stress in the insulating layer causes the self-assembled planar film to spontaneously curl into a multi-layer roll structure; S10, the multilayer roll structure is cleaned and freeze-dried, and the multilayer roll structure is tilted by a micromanipulator and a micromanipulation needle so that the sensitive axis of the multilayer roll structure points to the out-of-plane direction, and a z-axis sensitive magnetoelectric thin film sensor is obtained after polarization treatment.

[0010] Preferably, the substrate is DyScO 3 .

[0011] Preferably, the sacrificial layer is Sr 3 Al 2 O 6 .

[0012] Preferably, the bottom electrode layer is BaMoO 3 .

[0013] Preferably, the ferroelectric layer is PMN-PT, and the ferromagnetic layer is FeGaB.

[0014] Preferably, the ferroelectric layer is Pb(Zr,Ti)O 3 , the ferromagnetic layer is CoFeSiB.

[0015] Preferably, the fixed layer is a negative photoresist.

[0016] Preferably, the aspect ratio of the elongated ferromagnetic layer is greater than 10:1.

[0017] Preferably, in S1 to S3, pulsed laser deposition is used for deposition.

[0018] In a second aspect, the present invention provides a z-axis sensitive magnetoelectric thin film sensor obtained by the self-assembly preparation method.

[0019] Compared with the prior art, the present invention has the following beneficial effects: The present invention can make Si 3 N 4 The insulating layer has residual tensile stress, which provides a curling driving force for the film, so that the self-assembled planar film spontaneously curls into a multi-layer scroll structure. Since the patterned long strip ferromagnetic layer has shape anisotropy, its magnetic easy axis is along the length direction of the long strip, and the sensitive axis is perpendicular to the magnetic easy axis and in the in-plane direction. The sensitive axis of the multi-layer scroll structure obtained by spontaneous curling is still parallel to the in-plane. The multi-layer scroll structure is tilted by a micromanipulator and a micromanipulation needle, and the sensitive axis of the multi-layer scroll structure points to the out-of-plane direction (i.e. z axis), after polarization, the magnetic field can be realized based on the magnetoelectric coupling effect z Compared with the traditional method of vertically installing a planar sensor, the z-axis sensitive magnetoelectric thin film sensor obtained by the present invention can be formed in one step by removing the sacrificial layer, and the process is simple; compared with the traditional method of using an external magnetic field conversion element to z The axial magnetic field is transformed into x , y The z-axis sensitive magnetoelectric film sensor of the present invention can detect the z-axis magnetic field component by itself. z The z-axis sensitive magnetoelectric film sensor of the present invention does not require current drive, and the angular sensitivity can reach ±0.1°, which has the advantages of low power consumption and high sensitivity. Compared with the micro-rolled film with magnetoresistance effect, the z-axis sensitive magnetoelectric film sensor of the present invention can measure the direction information of the magnetic field, and can realize the magnetic field. z Axis component detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 For a z Flow chart of axis-sensitive magnetoelectric thin film sensor and its self-assembly preparation method.

[0022] Figure 2 For Example 1 z The magnetoelectric voltage under resonant conditions of an axis-sensitive magnetoelectric thin film sensor when it rotates in a 2 Oe out-of-plane AC magnetic field from 0° to 360°. DETAILED DESCRIPTION

[0023] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0024] It should be noted that the process equipment or devices not specifically specified in the following embodiments are all conventional equipment or devices in the art.

[0025] It should be noted that the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or to define the scope of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of the present invention without substantially changing the technical content.

[0026] like Figure 1 As shown, the self-assembly preparation method of the z-axis sensitive magnetoelectric thin film sensor of the present invention comprises: S1, epitaxially depositing a sacrificial layer on a substrate; S2, epitaxially depositing a bottom electrode layer on the sacrificial layer; S3, epitaxially depositing a ferroelectric layer on the bottom electrode layer; S4, using a method combining photolithography and magnetron sputtering technology to deposit a patterned long strip ferromagnetic layer on the ferroelectric layer; the ferromagnetic layer also serves as a top electrode layer; S5, using a method combining photolithography and magnetron sputtering technology, deposit Si on the ferromagnetic layer except for the part connected to the electrode pins. 3 N 4Insulating layer, wherein the sputtering rate of magnetron sputtering is 500 W to 900 W; S6, using a method combining photolithography and dry etching to etch the ferroelectric layer to the sacrificial layer, retaining the ferroelectric layer around the ferromagnetic layer, and obtaining a patterned planar thin film to be self-assembled with a support point around the periphery; S7, coating a fixed layer on an edge of the ferroelectric layer that is perpendicular to the long strip ferromagnetic layer, and fixing the edge of the ferroelectric layer on the substrate; S8, depositing electrode pins by combining photolithography with magnetron sputtering to lead out the bottom electrode layer and the ferromagnetic layer; S9, wet etching the sacrificial layer. 3 N 4 The residual tensile stress in the insulating layer causes the self-assembled planar film to spontaneously curl into a multi-layer roll structure; S10, the multilayer roll structure is cleaned and freeze-dried, and the multilayer roll structure is tilted by a micromanipulator and a micromanipulation needle so that the sensitive axis of the multilayer roll structure points to the out-of-plane direction, and a z-axis sensitive magnetoelectric thin film sensor is obtained after polarization treatment.

[0027] The present invention can make Si 3 N 4 The insulating layer has residual tensile stress, which prevents the multi-layer roll structure from short-circuiting on the one hand, and provides a curling driving force for the film on the other hand, so that the self-assembled planar film can spontaneously curl into a multi-layer roll structure. At the same time, the film curling diameter can also be controlled by changing the sputtering rate.

[0028] Since the patterned long strip ferromagnetic layer of the present invention has shape anisotropy, its magnetic easy axis is along the length direction of the long strip, and the sensitive axis is perpendicular to the magnetic easy axis and in the in-plane direction. The sensitive axis of the multilayer roll structure obtained by spontaneous curling is still parallel to the in-plane. The multilayer roll structure is tilted by a micromanipulator and a micromanipulation needle, and the sensitive axis of the multilayer roll structure points to the out-of-plane direction. After the device is polarized by the electrode pin, the magnetic field can be realized based on the magnetoelectric coupling effect. z Axis component detection.

[0029] In the present invention, the substrate is an oxide single crystal substrate, such as DyScO 3 The sacrificial layer is a thin film layer that can be completely removed by wet etching, such as Sr 3 Al 2 O 6 ; The bottom electrode layer may be BaMoO 3 .

[0030] In the present invention, the ferroelectric layer may be lead zirconate titanate (Pb(Zr,Ti)O 3), lead magnesium niobate-lead titanate (PMN-PT), etc., and the ferromagnetic layer can be FeGaB, CoFeSiB, etc. In order to better couple the ferromagnetic layer and the piezoelectric layer and make the magnetoelectric coupling response larger, 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 long strip ferromagnetic layer is greater than 10:1.

[0031] The electrode pins described in the present invention may be Au, Pt, etc.

[0032] The multilayer scroll structure of the present invention is rinsed in deionized water for 2-3 times, the deionized water is removed by freeze drying technology, and then the multilayer scroll structure is poured into the plane by a micromanipulator and a micromanipulation needle so that its sensitive axis points to the out-of-plane direction.

[0033] Example 1: Based on lead magnesium niobate-lead titanate (Pb(Mg 1 / 3 Nb 2 / 3 ) 3 –PbTiO 3 , PMN-PT) / FeGaB z-axis sensitive magnetoelectric thin film sensor.

[0034] The PMN-PT / FeGaB-based z Axis-sensitive magnetoelectric thin film sensors, including DyScO 3 Substrate and rectangular thin films, the thin films are BaMoO 3 Bottom electrode layer, PMN-PT ferroelectric layer, FeGaB ferromagnetic layer, Si 3 N 4 The FeGaB ferromagnetic layer is located at one end of the PMN-PT ferroelectric layer. The other end of the PMN-PT ferroelectric layer is fixed on the substrate through the SU8 fixing layer. The Au pin layer connects the BaMoO 3 The bottom electrode layer and the FeGaB ferromagnetic layer are led out from the other end of the PMN-PT ferroelectric layer. One end of the film having the FeGaB ferromagnetic layer is in a multi-layer roll structure, and the axis of the multi-layer roll structure is perpendicular to the substrate.

[0035] The implementation steps of this embodiment are as follows: Step 1: Pulsed laser deposition on DyScO 3 Epitaxial deposition of Sr on substrate 3 Al 2 O 6 Sacrificial layer.

[0036] (1-1) Pretreatment of substrate: DyScO oriented (001) 3 The substrate was placed in acetone, alcohol, and deionized water in turn, ultrasonically cleaned for 10 minutes in turn, and blown dry with dry nitrogen. The substrate was then placed in an ultraviolet ozone cleaning machine for 15 minutes to ensure that the substrate surface was clean and dust-free.

[0037] (1-2) Pulsed laser deposition on DyScO 3 Sr is deposited on the substrate 3 Al 2 O 6 Sacrificial layer film, deposition conditions include: DyScO 3 The substrate heating temperature was 800 °C, the laser energy was 0.8 W, the laser frequency was 3 Hz, and the working gas was O 2 The oxygen pressure was 20 Pa and the deposition time was 5 min. The Sr layer with a thickness of about 20 nm was obtained. 3 Al 2 O 6 Sacrificial layer film. Cubic phase Sr 3 Al 2 O 6 The lattice constant of DyScO is a=15.844 Å. 3 The pseudo cubic lattice constant of Sr is a = 3.946 Å. Since 15.844 Å / 4 = 3.96 Å is slightly larger than 3.946 Å, 3 Al 2 O 6 The sacrificial layer can be in DyScO 3 Epitaxial growth on substrate; Sr 3 Al 2 O 6 As a sacrificial layer, it can be completely dissolved by deionized water at room temperature, thereby completely releasing the upper functional film.

[0038] Step 2: pulsed laser deposition on Sr 3 Al 2 O 6 BaMoO epitaxially deposited on the sacrificial layer 3 Bottom electrode layer.

[0039] The specific process is: pulse laser deposition method is used to deposit Sr 3 Al 2 O 6 BaMoO is deposited on the sacrificial layer 3 The deposition conditions of the bottom electrode layer film include: substrate heating temperature 650 °C, laser energy 0.8 W, laser frequency 3 Hz, high vacuum environment 3 × 10 − 7 Torr, deposition time 15 min, the thickness of BaMoO was about 50 nm. 3 Bottom electrode layer thin film.

[0040] Because the cubic phase of BaMoO 3 The lattice constant of Sr is a = 4.04 Å, and the cubic phase 3 Al 2 O6 The lattice constant of BaMoO is a=15.844 Å. Since 4.04 Å is slightly larger than 15.844 Å / 4=3.96 Å, 3 The layer can be in Sr 3 Al 2 O 6 Epitaxial growth on the layer.

[0041] Step 3: pulsed laser deposition on BaMoO 3 A PMN-PT ferroelectric film is epitaxially deposited on the bottom electrode layer.

[0042] The specific process is: pulse laser deposition method is used to deposit BaMoO 3 The PMN-PT ferroelectric film was deposited on the bottom electrode layer. The deposition conditions included: substrate heating temperature 600 °C, laser energy 0.8 W, laser frequency 5 Hz, working gas O 2 The oxygen pressure was 25 Pa and the deposition time was 60 min, and a PMN-PT ferroelectric layer film with a thickness of about 200 nm was obtained.

[0043] The PMN-PT ferroelectric layer has a tetragonal structure with a lattice constant of a=b=4.024 Å and a cubic BaMoO 3 The lattice constant of PMN-PT is a=4.04 Å. Since their lattice constants are not much different, the PMN-PT ferroelectric layer can be formed on the surface of BaMoO 3 The bottom electrode layer is epitaxially grown.

[0044] Step 4: deposit a rectangular (aspect ratio = 10:1) FeGaB ferromagnetic layer film having an in-plane magnetic sensitive axis on the surface of the PMN-PT ferroelectric layer by combining photolithography and magnetron sputtering to form a PMN-PT / FeGaB magnetoelectric composite film.

[0045] (4-1) Spin-coat AR-P 3510T positive photoresist. Drop the positive photoresist on the sample surface and spin-coat at 500 rpm for 10 s and 4000 rpm for 50 s. Dry the sample on a heating table at 120 °C for 5 min, expose it to UV light for 8 s, and develop it in a developer for 60 s to pattern the positive photoresist.

[0046] (4-2) A FeGaB ferromagnetic film was deposited on the PMN-PT ferroelectric layer by magnetron sputtering. The deposition conditions included: working gas Ar gas, working gas pressure 3 mTorr, DC sputtering power 100 W deposition 2500 s, and a 200 nm thick FeGaB ferromagnetic film was obtained. The positive photoresist was then removed in acetone. Due to the anisotropy of the shape of the FeGaB ferromagnetic film, its magnetic easy axis is along the length direction of the long strip, and the magnetic sensitive axis is perpendicular to the magnetic easy axis and in the in-plane direction. Thus, a rectangular FeGaB ferromagnetic layer with an in-plane magnetic sensitive axis is obtained, and the FeGaB ferromagnetic film also serves as the top electrode layer.

[0047] Step 5: Deposit patterned Si on the surface of the FeGaB ferromagnetic layer by combining photolithography and magnetron sputtering technology. 3 N 4 The insulating layer is made of Si by using a high sputtering rate 3 N 4 The insulating layer has residual tensile stress, which prevents short circuit of the multi-layer roll structure on the one hand and provides a curling driving force for the film on the other hand.

[0048] (5-1) Spin-coat AR-P 3510T positive photoresist. Drop the positive photoresist on the sample surface and spin-coat at 500 rpm for 10 s and 4000 rpm for 50 s. Dry the sample on a heating table at 120°C for 5 min, expose it to UV light for 8 s, and develop it in a developer for 60 s to pattern the positive photoresist.

[0049] (5-2) Deposition of Si on the FeGaB ferromagnetic layer by magnetron sputtering 3 N 4 Insulating layer film, deposition conditions include: working gas Ar: N 2 =1:1, working pressure 3 mTorr, RF sputtering power 500 W, deposition 1000 s, to obtain 100 nm thick Si 3 N 4 The positive photoresist is then removed in acetone. This operation leaves most of the FeGaB ferromagnetic layer covered by Si 3 N 4 Cover, thereby preventing the multi-layer roll structure from short-circuiting, exposing a small portion of the FeGaB ferromagnetic layer for lead-out electrode pins. Due to the high sputtering rate, Si 3 N 4 The insulating layer has residual tensile stress, which provides a driving force for the self-curling / self-assembly of the film.

[0050] Step 6: Spin-coat a thicker photoresist protective layer and pattern it by ultraviolet exposure. Etch the film to the sacrificial layer by ion beam etching, and completely expose the end face of the bottom electrode layer, remove the photoresist, and form a rectangular self-assembled planar film with a fulcrum around it. The fulcrum provides support for the z-axis sensitive magnetoelectric sensor, enabling it to operate in the frequency range from DC to several hundred kHz.

[0051] (6-1) Spin-coat AR-P 3220 positive photoresist. Drop the positive photoresist on the film surface and spin-coat at 500 rpm for 10 s and 4000 rpm for 50 s. Place the sample on a heating table at 100 °C and dry for 2 min. Repeat the operation three times to obtain a photoresist coating of about 30 μm thick. Expose to ultraviolet light to form a patterned protective layer.

[0052] (6-2) The ferroelectric layer is etched by ion beam etching technology until the sacrificial layer is completely etched away and the end surface of the bottom electrode layer is completely exposed, and the ferroelectric layer around the ferromagnetic layer is retained. The etching conditions are: vacuum degree 8×10 -4 Pa, the anode current was 1 A, and the etching was performed for 50 min. Then the photoresist protective layer was removed in acetone.

[0053] Step seven, forming a fixed layer on the surface of the ferromagnetic layer by photolithography of a negative photoresist (SU8), and fixing one edge of the ferroelectric layer on the substrate.

[0054] (7-1) Spin-coat SU8 2000.5 negative photoresist, drop the negative photoresist on the film surface, spin-coat at 500 rpm for 10 seconds, spin-coat at 4000 rpm for 50 seconds, place the sample on a 100°C heating table to dry for 5 minutes, obtain a negative photoresist coating of about 0.5 μm thick, expose to ultraviolet light for 10 seconds, place the sample on a 100°C heating table again for 5 minutes, and develop in a developer for 60 seconds to form a patterned fixed layer. This operation fixes one edge of the device on the substrate.

[0055] Step eight, deposit the Au pin layer by combining photolithography and magnetron sputtering to lead out the top / bottom electrode layer to facilitate subsequent testing.

[0056] (8-1) Spin-coat AR-P 3510T positive photoresist. Drop the positive photoresist on the sample surface and spin-coat at 500 rpm for 10 s and 4000 rpm for 50 s. Dry the sample on a heating table at 120°C for 5 min, expose it to UV light for 8 s, and develop it in a developer for 60 s to pattern the positive photoresist. (8-2) Deposition of precious metal electrode pins: A layer of precious metal electrode pins Au was deposited on the surface of the film by magnetron sputtering technology, with Ar gas as the working gas, working pressure of 3 mTorr, DC sputtering power of 70 W for 4000 s to obtain a 200 nm thick Au film. Then, the positive photoresist was removed in acetone to obtain a patterned Au pin layer.

[0057] Step nine, wet-etching the sacrificial layer to completely remove the sacrificial layer.

[0058] (9-1) The sample was immersed in deionized water and Sr 3 Al 2 O 6 The sacrificial layer is wet etched. 3 N 4 The residual tensile stress in the insulating layer causes the film to self-roll to form a multi-layer roll structure as the sacrificial layer dissolves. At this time, the sensitive axis of the multi-layer roll structure is still parallel to the plane.

[0059] Step 10: Use freeze drying technology to remove deionized water, and use a micromanipulator and a micromanipulator needle to pour the multilayer roll structure into the plane, so that its sensitive axis points out of the plane to achieve magnetic field. z Axis component detection. After polarization at 100℃ and 200 kV / cm DC electric field for 20 minutes, a highly sensitive z Axis-sensitive magnetoelectric thin film sensors, such as Figure 2 As shown, its angular sensitivity is ±0.1°.

[0060] Example 2: Based on lead zirconate titanate (Pb(Zr,Ti)O 3 ) / CoFeSiB z-axis sensitive magnetoelectric thin film sensor.

[0061] The present invention provides a method based on lead zirconate titanate (Pb(Zr,Ti)O 3 ) / CoFeSiB z Axis-sensitive magnetoelectric thin film sensors, including DyScO 3 Substrate and rectangular thin films, the thin films are BaMoO 3 Bottom electrode layer, Pb(Zr,Ti)O 3 Ferroelectric layer, CoFeSiB ferromagnetic layer, Si 3 N 4 The insulating layer, the CoFeSiB ferromagnetic layer is located on the Pb(Zr,Ti)O 3 One end of the ferroelectric layer, Pb(Zr,Ti)O 3 The other end of the ferroelectric layer is fixed to the substrate through the SU8 fixing layer, and the Au pin layer fixes the BaMoO 3 The bottom electrode layer and the CoFeSiB ferromagnetic layer are made of Pb(Zr,Ti)O3 The other end of the ferroelectric layer is led out, and one end of the film having the CoFeSiB ferromagnetic layer is in a multi-layer roll structure, and the axis of the multi-layer roll structure is perpendicular to the substrate.

[0062] The implementation steps of this embodiment are as follows: Step 1: Pulsed laser deposition on DyScO 3 Epitaxial deposition of Sr on substrate 3 Al 2 O 6 Sacrificial layer.

[0063] (1-1) Pretreatment of substrate: DyScO oriented (001) 3 The substrate was placed in acetone, alcohol, and deionized water in turn, ultrasonically cleaned for 10 minutes in turn, and blown dry with dry nitrogen. The substrate was then placed in an ultraviolet ozone cleaning machine for 15 minutes to ensure that the substrate surface was clean and dust-free.

[0064] (1-2) Pulsed laser deposition on DyScO 3 Sr is deposited on the substrate 3 Al 2 O 6 Sacrificial layer film, deposition conditions include: DyScO 3 The substrate heating temperature was 800 °C, the laser energy was 0.8 W, the laser frequency was 3 Hz, and the working gas was O 2 The oxygen pressure was 20 Pa and the deposition time was 5 min. The Sr layer with a thickness of about 20 nm was obtained. 3 Al 2 O 6 Sacrificial layer film. Cubic phase Sr 3 Al 2 O 6 The lattice constant of DyScO is a=15.844 Å. 3 The pseudo cubic lattice constant of Sr is a = 3.946 Å. Since 15.844 Å / 4 = 3.96 Å is slightly larger than 3.946 Å, 3 Al 2 O 6 Layers can be in DyScO 3 Epitaxial growth on substrate, Sr 3 Al 2 O 6 As a sacrificial layer, it can be completely dissolved by deionized water at room temperature, thereby completely releasing the upper functional film.

[0065] Step 2: pulsed laser deposition on Sr 3 Al 2 O 6 BaMoO epitaxially deposited on the sacrificial layer 3 Bottom electrode layer.

[0066] The specific process is: pulse laser deposition method is used to deposit Sr 3 Al 2 O 6 BaMoO is deposited on the sacrificial layer 3 The deposition conditions of the bottom electrode layer film include: substrate heating temperature 650 °C, laser energy 0.8 W, laser frequency 3 Hz, high vacuum environment 3 × 10 − 7 Torr, deposition time 15 min, the thickness of BaMoO was about 50 nm. 3 Bottom electrode layer thin film.

[0067] Cubic BaMoO 3 The lattice constant of Sr is a = 4.04 Å, and the cubic phase 3 Al 2 O 6 The lattice constant of BaMoO is a = 15.844 Å. Since 4.04 Å is slightly larger than 15.844 Å / 4 = 3.96 Å, 3 The layer can be in Sr 3 Al 2 O 6 Epitaxial growth on the layer.

[0068] Step 3: pulsed laser deposition on BaMoO 3 Epitaxial deposition of Pb(Zr,Ti)O on the bottom electrode layer 3 Ferroelectric single crystal thin film.

[0069] The specific process is: pulse laser deposition method is used to deposit BaMoO 3 Pb(Zr,Ti)O is deposited on the bottom electrode layer 3 The deposition conditions of the ferroelectric layer include: substrate heating temperature 650 °C, laser energy 0.8 W, laser frequency 5 Hz, working gas O 2 The oxygen pressure was 26 Pa and the deposition time was 60 min to obtain a Pb(Zr,Ti)O layer with a thickness of about 200 nm. 3 Ferroelectric thin film.

[0070] Pb(Zr,Ti)O 3 The ferroelectric layer has a tetragonal structure with a lattice constant of a=b=4.017 Å and a cubic BaMoO 3 The lattice constant of Pb(Zr,Ti)O is a=4.04 Å. Since their lattice constants are not much different, 3 The ferroelectric layer can be 3 The bottom electrode layer is epitaxially grown.

[0071] Step 4: In Pb(Zr,Ti)O 3 The surface of the ferroelectric layer is deposited with a rectangular (aspect ratio = 10:1) CoFeSiB ferromagnetic film layer with an in-plane magnetic sensitive axis by combining photolithography and magnetron sputtering to form a Pb(Zr,Ti)O 3 / CoFeSiB magnetoelectric composite film.

[0072] (4-1) Spin-coat AR-P 3510T positive photoresist. Drop the positive photoresist on the sample surface and spin-coat at 500 rpm for 10 s and 4000 rpm for 50 s. Dry the sample on a heating table at 120 °C for 5 min, expose it to UV light for 8 s, and develop it in a developer for 60 s to pattern the positive photoresist.

[0073] (4-2) Magnetron sputtering was used to deposit Pb(Zr,Ti)O 3 A CoFeSiB ferromagnetic layer was deposited on the ferroelectric layer. The deposition conditions included: working gas Ar gas, working gas pressure 3 mTorr, DC sputtering power 120 W deposition for about 2000 s, and a 200 nm thick CoFeSiB ferromagnetic film was obtained. Then the positive photoresist was removed in acetone. Due to the anisotropy of the shape of the CoFeSiB ferromagnetic film, its magnetic easy axis is along the length direction of the long strip, and the magnetic sensitive axis is perpendicular to the magnetic easy axis and in the in-plane direction. Thus, a rectangular CoFeSiB ferromagnetic layer with an in-plane magnetic sensitive axis was obtained.

[0074] Step 5: Deposit patterned Si on the surface of the CoFeSiB ferromagnetic layer by combining photolithography and magnetron sputtering technology. 3 N 4 The insulating layer is formed by sputtering the CoFeSiB ferromagnetic layer with residual tensile stress at a high sputtering rate; on the one hand, it prevents the multi-layer roll structure from short-circuiting, and on the other hand, it provides a curling driving force for the film.

[0075] (5-1) Spin-coat AR-P 3510T positive photoresist. Drop the positive photoresist on the sample surface and spin-coat at 500 rpm for 10 s and 4000 rpm for 50 s. Dry the sample on a heating table at 120°C for 5 min, expose it to UV light for 8 s, and develop it in a developer for 60 s to pattern the positive photoresist.

[0076] (5-2) Deposition of Si on the CoFeSiB ferromagnetic layer by magnetron sputtering 3 N 4 Insulating layer film, deposition conditions include: working gas Ar: N 2 =1:1, working pressure 3 mTorr, RF sputtering power 900 W deposition 600 s, to obtain 90 nm thick Si 3 N4 The positive photoresist was then removed in acetone. This operation left most of the CoFeSiB film covered with Si 3 N 4 Covering, thereby preventing the multi-layer roll structure from short-circuiting, exposing a small portion of the CoFeSiB film for lead-out electrode pins. Due to the high sputtering rate, Si 3 N 4 The insulating layer has residual tensile stress, which provides a driving force for the self-curling / self-assembly of the film.

[0077] Step 6: Spin-coat a thicker photoresist protective layer and pattern it by ultraviolet exposure. Etch the film to the sacrificial layer by ion beam etching, and completely expose the end face of the bottom electrode layer, remove the photoresist, and form a rectangular self-assembled planar film with a fulcrum around it. The fulcrum provides support for the z-axis sensitive magnetoelectric sensor, enabling it to work at a higher frequency.

[0078] (6-1) Spin-coat AR-P 3220 positive photoresist by dropping the positive photoresist on the film surface and spin-coating at 500 rpm for 10 s and 4000 rpm for 50 s. Place the sample on a heating table at 100 °C and dry for 2 min. Repeat the operation three times to obtain a positive photoresist coating of about 30 μm thick. Expose to ultraviolet light to form a patterned protective layer.

[0079] (6-2) The ferroelectric layer is etched by ion beam etching technology until the sacrificial layer is completely etched away and the end surface of the bottom electrode layer is completely exposed, and the ferroelectric layer around the ferromagnetic layer is retained. The etching conditions are: vacuum degree 8×10 -4 Pa, the anode current was 1 A, and the etching was carried out for 60 min. The photoresist was then removed in acetone.

[0080] Step seven, forming a fixed layer on the surface of the ferromagnetic layer by photolithography of a negative photoresist (SU8), and fixing one edge of the ferroelectric layer on the substrate.

[0081] (7-1) Spin-coat SU8 2000.5 negative photoresist, drop the negative photoresist on the film surface, spin-coat at 500 rpm for 10 seconds, spin-coat at 4000 rpm for 50 seconds, place the sample on a 100°C heating table to dry for 5 minutes, obtain a negative photoresist coating of about 0.5 μm thick, expose to ultraviolet light for 10 seconds, place the sample on a 100°C heating table again for 5 minutes, and develop in a developer for 60 seconds to form a patterned fixed layer. This operation fixes one edge of the device on the substrate.

[0082] Step eight, deposit the Au pin layer by combining photolithography and magnetron sputtering to lead out the top / bottom electrodes for subsequent testing.

[0083] (8-1) Spin-coat AR-P 3510T positive photoresist. Drop the positive photoresist on the sample surface and spin-coat at 500 rpm for 10 s and 4000 rpm for 50 s. Dry the sample on a heating table at 120°C for 5 min, expose it to UV light for 8 s, and develop it in a developer for 60 s to pattern the positive photoresist. (8-2) Deposition of precious metal electrode pins: A layer of precious metal electrode pins Au was deposited on the surface of the film by magnetron sputtering technology, with Ar gas as the working gas, working pressure of 3 mTorr, DC sputtering power of 70 W for 4000 s to obtain a 200 nm thick Au film. Then, the positive photoresist was removed in acetone to obtain a patterned Au pin layer.

[0084] Step nine, wet-etching the sacrificial layer to completely remove the sacrificial layer.

[0085] (9-1) The sample was immersed in deionized water and Sr 3 Al 2 O 6 The sacrificial layer is wet etched. 3 N 4 The residual tensile stress in the insulating layer causes the film to self-roll to form a multi-layer roll structure as the sacrificial layer dissolves. At this time, the sensitive axis of the multi-layer roll structure is still parallel to the plane.

[0086] Step 10: Use freeze drying technology to remove deionized water, and use a micromanipulator and a micromanipulator needle to pour the multilayer roll structure into the plane, so that its sensitive axis points out of the plane to achieve magnetic field. z Axis component detection. After polarization at 100℃ and 200 kV / cm DC electric field for 20 minutes, a highly sensitive z Axis-sensitive magnetoelectric thin film sensor with an angular sensitivity of ±0.2°.

Claims

1. A self-assembly preparation method of a z-axis sensitive magnetoelectric thin film sensor, characterized in that: include: S1, epitaxially depositing a sacrificial layer on a substrate; S2, epitaxially depositing a bottom electrode layer on the sacrificial layer; S3, epitaxially depositing a ferroelectric layer on the bottom electrode layer; S4, depositing a patterned long strip ferromagnetic layer on the ferroelectric layer by combining photolithography and magnetron sputtering technology; S5, using a method combining photolithography and magnetron sputtering technology to deposit a Si3N4 insulating layer on the ferromagnetic layer except for the portion connected to the electrode pins, wherein the sputtering rate of the magnetron sputtering is 500 W to 900 W; S6, using a method combining photolithography and dry etching to etch the ferroelectric layer to the sacrificial layer, retaining the ferroelectric layer around the ferromagnetic layer, and obtaining a patterned planar thin film to be self-assembled with a support point around the periphery; S7, coating a fixed layer on an edge of the ferroelectric layer that is perpendicular to the long strip ferromagnetic layer, and fixing the edge of the ferroelectric layer on the substrate; S8, depositing electrode pins by combining photolithography with magnetron sputtering to lead out the bottom electrode layer and the ferromagnetic layer; S9, wet etching the sacrificial layer, and due to the residual tensile stress in the Si3N4 insulating layer, the self-assembled planar film spontaneously curls into a multi-layer roll structure; S10, the multilayer roll structure is cleaned and freeze-dried, and the multilayer roll structure is tilted by a micromanipulator and a micromanipulation needle so that the sensitive axis of the multilayer roll structure points to the out-of-plane direction, and a z-axis sensitive magnetoelectric thin film sensor is obtained after polarization treatment.

2. The self-assembly preparation 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 preparation 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 preparation 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 preparation 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 preparation 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 preparation method of the z-axis sensitive magnetoelectric thin film sensor according to claim 1, characterized in that: The fixed layer is negative photoresist.

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

1.

9. The self-assembly preparation method of the z-axis sensitive magnetoelectric thin film sensor according to claim 1, characterized in that: In S1~S3, pulse laser deposition is 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.

Images