CN104215917B - Boundary wave resonance type magnetic sensor - Google Patents
Boundary wave resonance type magnetic sensor Download PDFInfo
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- CN104215917B CN104215917B CN201410467102.4A CN201410467102A CN104215917B CN 104215917 B CN104215917 B CN 104215917B CN 201410467102 A CN201410467102 A CN 201410467102A CN 104215917 B CN104215917 B CN 104215917B
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- boundary wave
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Abstract
The invention provides a boundary wave resonance type magnetic sensor. The boundary wave resonance type magnetic sensor comprises a piezoelectric substrate, a dielectric layer formed on one surface of the piezoelectric substrate, and an inter-digital electrode arranged between the piezoelectric substrate and the dielectric layer and used to generate boundary waves, wherein the dielectric layer covers the inter-digital electrode. The boundary wave resonance type magnetic sensor further comprises a magnetostriction film which is formed on the upper surface of the dielectric layer, and used to sense an external magnetic field and change own Young modulus based on the external magnetic field. Changes of resonant frequency of the boundary waves are caused by changes of the own Young modulus of the magnetostriction film, and the boundary wave resonance type magnetic sensor detects changes of the external magnetic field by detecting the changes of the resonant frequency of the boundary waves. Not only does the boundary wave resonance type magnetic sensor have the advantages of being high in sensitivity, small in size, convenient to encapsulate and simple to manufacture, but also due to the fact that the magnetostriction film is located on the upper surface of the dielectric layer, the formed magnetostriction film is small in residual stress, and formation of the magnetostriction film high in quality is facilitated.
Description
【Technical field】
The present invention relates to the Magnetic Sensor field based on boundary wave, more particularly to a kind of boundary wave resonant mode Magnetic Sensor.
【Background technology】
In recent years, it is wide using acoustic surface wave devices such as surface acoustic wave resonance of surface acoustic wave, surface acoustic wave filters
Apply generally.
Acoustic surface wave device has piezoelectric substrate and the interdigital electrode formed on piezoelectric substrate, in acoustic surface wave device
The elastic wave that interdigital electrode is excited is propagated on piezoelectric substrate surface as surface acoustic wave.
Vibration mode of the acoustic surface wave device using surface acoustic wave, its resonant frequency depend on piezoelectric substrate and dielectric layer
Young's moduluss and density of material, therefore can by change the Young's moduluss or density of material of piezoelectric substrate or dielectric layer come
Change the resonant frequency.
【The content of the invention】
It is an object of the invention to provide a kind of sensitivity height, small volume, convenient encapsulation, and making simple boundary wave
Resonant mode Magnetic Sensor.
In order to reach foregoing invention purpose, the invention provides a kind of boundary wave resonant mode Magnetic Sensor, which includes：One pressure
Electric substrate；One dielectric layer, is formed on a surface of the piezoelectric substrate, and which includes the following table combined with the piezoelectric substrate
Face and the upper surface being oppositely arranged with the lower surface；One interdigital electrode, is arranged between piezoelectric substrate and dielectric layer and by this
Dielectric layer is covered, and which is used to produce boundary wave；One magnetostrictive thin film, is formed at the upper surface of the dielectric layer, and which is used for
Sensing external magnetic field is simultaneously based on the external magnetic field and changes itself Young's modulus；Wherein, itself Young of the magnetostrictive thin film
The change of modulus causes the resonant frequency of above-mentioned boundary wave to change, and the boundary wave resonant mode Magnetic Sensor is by detecting the border
The change that the resonant frequency of ripple changes to detect external magnetic field.
Preferably, the piezoelectric substrate is monocrystalline piezoelectric substrate or piezoelectric membrane.
Preferably, the interdigital electrode includes interdigital transducer and the reflector positioned at interdigital transducer two ends.
Preferably, the velocity of sound of the velocity of sound of the dielectric layer less than piezoelectric substrate.
Preferably, the dielectric layer is made up of silicon dioxide.
Preferably, the magnetostrictive thin film be the FeSiB with uniaxial anisotropy and huge Young's moduluss effect,
FeSiBC or FeCoSiB magnetostrictive thin films.
Preferably, the boundary wave resonant mode Magnetic Sensor is additionally included in magnetostrictive thin film away from the dielectric layer
The protective layer formed on surface.
Preferably, the protective layer is made up of resin material, and which is used to absorb clutter and the protection magnetostrictive thin film.
Preferably, the protective layer is made up of high-sound-velocity material, and which is used to isolate magnetostrictive thin film surface from environment
The impact of factor.
Preferably, the protective layer is made up of silicon dioxide, and which is used for the frequency for improving the boundary wave resonant mode Magnetic Sensor
Rate temperature characterisitic.
The boundary wave resonant mode Magnetic Sensor that the present invention is provided, its not only sensitivity height, small volume, convenient encapsulation, making
Simply, and as the magnetostrictive thin film is located at the upper surface of dielectric layer, therefore the magnetostrictive thin film remnants for being formed should
Power is little, beneficial to forming high-quality magnetostrictive thin film.
【Description of the drawings】
Fig. 1 is the positive cross-sectional schematic of boundary wave resonant mode Magnetic Sensor of the present invention.
【Specific embodiment】
Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is carried out clear, complete
Site preparation is described.Based on the embodiment in the present invention, those of ordinary skill in the art institute under the premise of creative work is not made
The every other embodiment for obtaining, belongs to the scope of protection of the invention.
As shown in figure 1, the invention provides a kind of boundary wave resonant mode Magnetic Sensor 1, which includes a piezoelectric substrate 10, shape
Into the dielectric layer 11 on a surface of the piezoelectric substrate 10, it is placed between piezoelectric substrate 10 and dielectric layer 11 and by this
Interdigital electrode 12 that dielectric layer 11 is covered, the magnetostrictive thin film 13 being formed on the dielectric layer 11, and stretch in mangneto
The protective layer 14 that contracting thin film 11 is formed on the surface away from the dielectric layer 11.
The piezoelectric substrate 10 can be monocrystalline piezoelectric substrate, and for example quartz, LiNbO3 or LiTaO3 etc. make, it is also possible to
It is piezoelectric membrane, the piezoelectric membrane such as such as AIN, ZnO.
The interdigital electrode 12 is made out of a piezoelectric material, and which is traditional single-ended or both-end interdigitated electrode structure, for producing
Raw boundary wave, the boundary wave is SH shearing waves, and which includes interdigital transducer and the reflector positioned at interdigital transducer two ends.The fork
Refer to difference of the electrode 12 according to piezoelectric substrate 10, the material that its electrode material can adopt the big velocity of sound of AI, Cu, Ag, Au isodensity low
Material.As the thickness of electrode of interdigital electrode 12 has adjustment effect to the speed of boundary wave, therefore could be arranged to trapezoidal or square
Shape electrode, concrete thickness and formation can go to be adjusted according to actual needs, and in the present invention, the interdigital electrode 12 is preferred
Using rectangular electrode.
The dielectric layer 11 is included the lower surface combined with the piezoelectric substrate 10 and is oppositely arranged with the lower surface
Upper surface, which covers 12 1 preset thickness of interdigital electrode, and its thickness is typically in 0.01-0.25 wavelength thickness scope of boundary wave
It is interior, it is preferably big using density and the relatively low insulant of the velocity of sound is made, so that the velocity of sound for ensureing the dielectric layer 11 is less than
The velocity of sound of piezoelectric substrate 10, its object is to be formed the ducting layer of aggregation, and the characteristic of mechanical wave sound wave in other words is that energy is easy
Toward fast strata collection in a low voice.SiO2 is selected in the present invention preferentially, because can also have temperature compensation characteristic concurrently using SiO2, certainly
Dielectric layer 11 can also adopt that other density are big, the velocity of sound is low, and the little material of Young's moduluss make.The dielectric layer 11
On the premise of ensureing that magnetostrictive thin film 13 has enough electric isolations with interdigital electrode 12, thickness is unsuitable blocked up, so, magnetic
Cause self-adhering film 13 be more nearly the boundary at the place of interdigital electrode 12, so that magnetostrictive thin film 13 is to resonance frequency
The impact of rate is bigger, and then causes the boundary wave resonant mode Magnetic Sensor 1 that the present invention is provided to have higher sensitivity.
The magnetostrictive thin film 13 is formed at the upper surface of the dielectric layer 11, and which is used to sense external magnetic field and be based on
The external magnetic field and change itself Young's modulus.Magnetostrictive thin film 13 is non-crystaline amorphous metal, possesses magnetic anisotropy and huge Young
Modulus effect, which can be FeCoSiB, and the material such as FeGaB, FeSiB is made.
Existing some boundary wave mangneto sensors are again provided with piezoelectric substrate, and piezoelectric substrate upper surface is formed with interdigital electrode
And dielectric layer, but, magnetostrictive thin film is but arranged on the lower surface of piezoelectric substrate, this kind of Magnetic Sensor institute relatively of the present invention
For the boundary wave resonant mode Magnetic Sensor 1 of offer, due to magnetostrictive thin film be sandwiched in piezoelectric substrate and bonding protective layer or
Between other substrates, so, using successively succession can not then obtain high-quality magnetostrictive thin film and take from the bottom up
To the high piezoelectric substrate of growth or piezoelectric membrane, then sacrifice layer work can only be adopted in order to obtain high-quality magnetostrictive thin film
Skill, but this sacrifice layer process is relatively complicated, directly contributes production cost height, low production efficiency.And the present invention is different, this
Bright magnetostrictive thin film 13, can directly using pressure due in the superiors, adopting succession from the bottom up successively
Electric substrate or growth piezoelectric membrane, then interdigital electrode is made, after grown dielectric layer covers the interdigital electrode, regrowth is thicker
Magnetostrictive thin film 13, as magnetostrictive thin film 13 is located at the upper surface of dielectric layer 11, what is can not only grown is thicker, and
And the internal stress of magnetostrictive thin film 13 can be caused fully to be discharged, and can be obtained by magnetic anneal possess magnetic respectively to
The magnetostrictive thin film 13 of the opposite sex.
Boundary wave resonant mode Magnetic Sensor 1 provided by the present invention, which is most important to be characterised by that the magnetostriction is thin
Film 13 is arranged on the upper surface of dielectric layer 11, under magnetostrictive thin film 13 is arranged at piezoelectric substrate or piezoelectric membrane
For side, the magnetostrictive thin film 13 is with a distance from boundary wave closer to so so that magnetostrictive thin film 13 is to resonant frequency
Impact it is bigger, can take up bigger proportion in equivalent Young's modulus, or even can realize that highly sensitive detection is extremely weak
Steady magnetic field.Further, since magnetostrictive thin film 13 itself is soft, the thickness of dielectric layer 11 can be reduced, by setting
The ducting layer that boundary wave is formed can be limited in magnetostrictive thin film 13, so, the boundary wave mangneto that the present invention is provided by meter
The sensitivity of sensor 1 will be greatly improved, while and the characteristics of had the low-loss of boundary wave, high electromechanical coupling factor concurrently.
And when magnetostrictive thin film 13 is located at below piezoelectric substrate or piezoelectric membrane, not only Young's moduluss of magnetostrictive thin film 13
Accounting is reduced, also farther from interdigital electrode 12, and boundary wave cannot form the ducting layer of aggregation, sensitivity as in the present invention
Also it is difficult to be lifted.
Present invention additionally comprises the protective layer 14 formed on surface of the magnetostrictive thin film 13 away from the dielectric layer 11.
When the protective layer 14 is made up of resin material, which can be used for absorbing clutter and protects the magnetostrictive thin film 13；It is described
When protective layer 14 is made up of high-sound-velocity material, which can be used for isolating shadow of 13 surface of magnetostrictive thin film from environmental factorss
Ring；When the protective layer 14 is made up of silicon dioxide, which can be used for the frequency temperature for improving the boundary wave resonant mode Magnetic Sensor 1
Degree characteristic
In the present invention, the boundary wave resonant mode Magnetic Sensor 1 is the vibration mode based on boundary wave, and its resonant frequency takes
Certainly in piezoelectric substrate 10 and the Young's moduluss and density of material of dielectric layer 11, and the magnetostrictive thin film 13 itself Young mould
The change of amount can cause the resonant frequency of boundary wave to change again, and based on this, the boundary wave resonant mode Magnetic Sensor 1 can pass through
Detect the change that the resonant frequency of the boundary wave changes to detect external magnetic field.
The boundary wave resonant mode Magnetic Sensor 1 that the present invention is provided, its not only sensitivity height, small volume, convenient encapsulation, making
Simply, and as the magnetostrictive thin film 13 is located at the upper surface of dielectric layer 11, therefore the magnetostrictive thin film 13 for being formed
Residual stress is little, beneficial to forming high-quality magnetostrictive thin film 13, or even can realize the extremely weak steady of highly sensitive detection
Magnetic field.
Above-described is only the better embodiment of the present invention, it should be noted here that for the ordinary skill of this area
For personnel, without departing from the concept of the premise of the invention, improvement can also be made, but these belongs to the guarantor of the present invention
Shield scope.
Claims (10)
1. a kind of boundary wave resonant mode Magnetic Sensor, it is characterised in which includes：
One piezoelectric substrate；
One dielectric layer, is formed on a surface of the piezoelectric substrate, and which includes the lower surface combined with the piezoelectric substrate
And the upper surface being oppositely arranged with the lower surface；
One interdigital electrode, is arranged between piezoelectric substrate and dielectric layer and is covered by the dielectric layer, and which is used to produce border
Ripple；
One magnetostrictive thin film, is formed at the upper surface of the dielectric layer, and covers the interdigital electrode, for sensing extraneous magnetic
Field is simultaneously based on the external magnetic field and changes itself Young's modulus；
Wherein, the change of itself Young's modulus of the magnetostrictive thin film causes the resonant frequency of above-mentioned boundary wave to change, described
The change that boundary wave resonant mode Magnetic Sensor changes to detect external magnetic field by the resonant frequency for detecting the boundary wave.
2. boundary wave resonant mode Magnetic Sensor as claimed in claim 1, it is characterised in that：The piezoelectric substrate is monocrystalline piezoelectric
Substrate or piezoelectric membrane.
3. boundary wave resonant mode Magnetic Sensor as claimed in claim 1, it is characterised in that：The interdigital electrode includes interdigital changing
Can device and the reflector positioned at interdigital transducer two ends.
4. boundary wave resonant mode Magnetic Sensor as claimed in claim 1, it is characterised in that the velocity of sound of the dielectric layer is less than
The velocity of sound of piezoelectric substrate.
5. boundary wave resonant mode Magnetic Sensor as claimed in claim 1, it is characterised in that the dielectric layer is by silicon dioxide
Make.
6. boundary wave resonant mode Magnetic Sensor as claimed in claim 1, it is characterised in that the magnetostrictive thin film be with
FeSiB, FeSiBC or FeCoSiB magnetostrictive thin film of uniaxial anisotropy and huge Young's moduluss effect.
7. boundary wave resonant mode Magnetic Sensor as claimed in claim 1, it is characterised in that the boundary wave resonant mode magnetic sensing
Device is additionally included in the protective layer formed on surface of the magnetostrictive thin film away from the dielectric layer.
8. boundary wave resonant mode Magnetic Sensor as claimed in claim 7, it is characterised in that the protective layer is by resin material system
Into which is used to absorb clutter and the protection magnetostrictive thin film.
9. boundary wave resonant mode Magnetic Sensor as claimed in claim 7, it is characterised in that the protective layer is by high-sound-velocity material
Make, which is used to isolate impact of the magnetostrictive thin film surface from environmental factorss.
10. boundary wave resonant mode Magnetic Sensor as claimed in claim 7, it is characterised in that the protective layer is by silicon dioxide
Make, which is used for the frequency-temperature characteristic for improving the boundary wave resonant mode Magnetic Sensor.
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| CN201410467102.4A CN104215917B (en) | 2014-09-12 | 2014-09-12 | Boundary wave resonance type magnetic sensor |
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| CN201410467102.4A CN104215917B (en) | 2014-09-12 | 2014-09-12 | Boundary wave resonance type magnetic sensor |
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| CN104215917B true CN104215917B (en) | 2017-05-10 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN105158711B (en) * | 2015-07-31 | 2018-05-11 | 瑞声光电科技(常州)有限公司 | A kind of Z axis magnetic field loading device |
| CN106154186B (en) * | 2016-06-20 | 2020-01-17 | 瑞声声学科技(常州)有限公司 | Surface acoustic wave magnetic sensor and preparation method thereof |
| CN108205118B (en) * | 2016-12-19 | 2020-12-25 | 南京理工大学 | Resonant magnetic sensor sensitive unit and digital frequency output magnetic sensor |
| CN110118947B (en) * | 2019-04-19 | 2021-01-05 | 华中科技大学 | Magnetic sensing device |
| CN110118946B (en) * | 2019-04-19 | 2020-12-29 | 华中科技大学 | Resonant magnetic sensor |
| JP2020202429A (en) * | 2019-06-06 | 2020-12-17 | 株式会社村田製作所 | Elastic wave device |
| CN110611492A (en) * | 2019-09-09 | 2019-12-24 | 电子科技大学 | Magnetoelectric surface acoustic wave resonator based on magnetostrictive multilayer film |
| CN114609554B (en) * | 2022-05-11 | 2022-07-29 | 电子科技大学 | Length-telescopic resonant magnetic sensor |
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| US4078186A (en) * | 1976-10-21 | 1978-03-07 | The United States Of America As Represented By The Secretary Of The Navy | Magnetically tuned, surface acoustic wave device |
| US5959388A (en) * | 1997-10-27 | 1999-09-28 | Lucent Technologies Inc. | Magnetically tunable surface acoustic wave devices |
| CN101504446B (en) * | 2009-03-06 | 2011-04-20 | 华南理工大学 | Thin film type structural magnetofluid-sonic surface wave integrated magnetic transducer |
| CN102435959A (en) * | 2011-10-11 | 2012-05-02 | 电子科技大学 | Magnetic-acoustic surface wave magnetic field sensor and preparation method thereof |
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