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Magnetic-acoustic surface wave magnetic field sensor and preparation method thereof

A magnetic field sensor and surface wave technology, applied in the direction of the size/direction of the magnetic field, can solve the problems of difficult miniaturization and low magnetic field sensitivity, and achieve the effects of easy integration, high sensitivity, and consistent number

Inactive Publication Date: 2012-05-02
UNIV OF ELECTRONICS SCI & TECH OF CHINA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] In order to overcome the shortcomings of low magnetic field sensitivity and difficulty in miniaturization in the existing magnetoacoustic surface wave magnetic field sensor technology, the present invention provides a magnetoacoustic surface wave magnetic field sensor with a composite multilayer film structure, which has the advantages of miniaturization, easy integration, and high sensitivity , consistency number, stable and reliable features

Method used

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  • Magnetic-acoustic surface wave magnetic field sensor and preparation method thereof

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preparation example Construction

[0021] A method for preparing a magnetoacoustic surface wave magnetic field sensor, comprising the following steps:

[0022] Step 1: On clean Pt / Ti / SiO 2 / Si substrate Pt surface sputtering deposition of piezoelectric film and high temperature annealing of the piezoelectric film. Highly oriented ZnO, PZT, AlN or LiNbO should be used for piezoelectric film 3 Piezoelectric film with a thickness of 1-2 microns.

[0023]Step 2: Deposit a metal chromium buffer layer on the surface of the piezoelectric thin film obtained in step 1 by sputtering. The thickness of the metal chromium buffer layer is controlled at about 20 nanometers. The role of the metal chromium buffer layer is to increase the adhesion between the piezoelectric film and the magnetostrictive film. If the magnetostrictive film is directly sputtered on the surface of the piezoelectric film, it will cause damage to the quality of the piezoelectric film on the one hand, and on the other hand It is also difficult to ob...

specific Embodiment approach 1

[0029] A specific surface wave magnetic field sensor obtained through the above preparation process, the substrate substrate is a quartz substrate, the size is 20 × 10 mm, and the parameters of each component are as follows:

[0030] The piezoelectric film is a C-axis oriented ZnO film with a thickness of 1 micron, the rocking curve FWHM (half width height) of its (002) diffraction peak is 2.8 deg, and the resistivity is >10 9 Ω / cm, surface roughness less than 4nm, piezoelectric coefficient d 33 for

[0031] The magnetostrictive film is 5 μm thick Fe 81 Si 13.5 B 3.5 C 2 Thin film, the magnetostriction coefficient is 35ppm, the coercive force along the direction of easy magnetization is 2Oe, and the remanence ratio> 75%;

[0032] The interdigital transducer is a double-ended interdigital transducer with reflection grids on both sides, with a thickness of 0.8 microns and made of metal aluminum. The finger width and finger spacing of IDs and reflection grids are both 2 μm...

specific Embodiment approach 2

[0035] A specific surface wave magnetic field sensor obtained through the above preparation process, the substrate substrate is a quartz substrate, the substrate size is 20 × 10 mm, and the parameters of each component are as follows:

[0036] The piezoelectric film is PZT (Pb 1.1 (Zr 0.58 Ti 0.42 )O 3 ) film with a thickness of 1 micron, the rocking curve FWHM (half width height) of its (001) diffraction peak is 5.8deg, and the resistivity>10 10 Ω / cm, surface roughness less than 6.5nm, piezoelectric coefficient d 33 for

[0037] The magnetostrictive film is Fe after 5 microns 78 Si 9 B 13 The film has a magnetostriction coefficient of 30ppm, a coercive force of 2.4Oe along the direction of easy magnetization, and a remanence ratio>50%; two layers of 20nm metal copper layers are inserted into the magnetostrictive film;

[0038] The interdigital transducer is a double-ended interdigital transducer with reflection grids on both sides, with a thickness of 0.8 microns ...

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Abstract

The invention relates to a magnetic-acoustic surface wave magnetic field sensor and a preparation method thereof, and belongs to the technical field of electronic functional materials and devices. The sensor comprises a piezoelectric thin film, a magnetostrictive thin film and a substrate, wherein the magnetostrictive thin film is positioned between the piezoelectric thin film and the substrate; the thickness of the magnetostrictive thin film is 2-5 times the thickness of the piezoelectric thin film; and an interdigital transducer is arranged on the surface of the piezoelectric thin film, and the interdigital transducer and the piezoelectric thin film constitute an acoustic surface wave device. A layer of SiO2 is covered on the surface of the piezoelectric thin film and the interdigital transducer. When the sensor is in resonant state, if an external magnetic field changes, the Young's modulus of a magnetostrictive layer changes, the propagation speed of acoustic surface waves in a piezoelectric layer can be further affected and then the changes of the external magnetic field can be known by detecting the changes in resonance center frequency. The SiO2 covering layer can compensate for a frequency temperature coefficient of the piezoelectric thin film and realize the frequency temperature coefficient which is close to zero. The sensor has the characteristics of miniaturization, easiness in integration, high sensitivity, good consistency, stability and reliability.

Description

technical field [0001] The invention belongs to the technical field of electronic functional materials and devices, and relates to a magnetic field sensor structure and a preparation method, in particular to a magnetoacoustic surface wave sensor for weak magnetic field measurement based on piezoelectric materials and magnetostrictive materials. Background technique [0002] Magnetic field detection plays an important role in the fields of production, life and national defense security. The magnetic field has strong anti-interference ability, is not affected by external conditions such as temperature and humidity, has no radiation characteristics, and has strong penetrability, so it can be widely used in early warning investigation, automatic tracking and positioning, geomagnetic navigation, mine clearance, magnetic wave Many military fields such as communications; in addition, magnetic field sensors can also be used as flow meters, tachometers, etc. [0003] Traditional mag...

Claims

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Application Information

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IPC IPC(8): G01R33/02
Inventor 白飞明代丽红文丹丹钟智勇张怀武
Owner UNIV OF ELECTRONICS SCI & TECH OF CHINA
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