CN-120991924-B - Surface acoustic wave sensor and packaging structure thereof

CN120991924BCN 120991924 BCN120991924 BCN 120991924BCN-120991924-B

Abstract

The invention provides a surface acoustic wave sensor and a packaging structure thereof, which are based on the layout of a POI piezoelectric substrate and a multifunctional reflecting grating, integrate temperature, pressure and acceleration sensitive units into a single chip to realize decoupling of multiple sensing quantities, respectively design two reference gratings positioned at two sides of a uniform interdigital transducer and a group of acceleration measuring reflecting grating, a temperature measuring reflecting grating and a pressure measuring reflecting grating, wherein the two reference gratings are used for differential time delay measurement of the sensing quantities, the temperature measuring reflecting grating is arranged close to the reference grating, the temperature measurement is effectively ensured not to be influenced by other sensing quantities, the interference of environmental noise is effectively inhibited, the efficient separation and synchronous detection of temperature, pressure and acceleration multi-parameter signals are realized, the electromagnetic coupling problem of the traditional interdigital transducer structure is avoided, the packaging structure of the surface acoustic wave sensor adopts the packaging structure, the whole structure of the device is compact, and the installation difficulty and the system maintenance cost under the complex environment are greatly reduced.

Inventors

SHI RUCHUAN
HAN WENHAO
HAN TAO
GUO DAPENG

Assignees

上海交通大学

Dates

Publication Date: 20260512
Application Date: 20250825

Claims (14)

1. A surface acoustic wave sensor is characterized by comprising a piezoelectric substrate, a surface acoustic wave uniform interdigital transducer, a temperature measurement reflection grating, a pressure measurement reflection grating, an acceleration measurement reflection grating and two reference gratings, wherein the surface acoustic wave uniform interdigital transducer, the temperature measurement reflection grating, the pressure measurement reflection grating, the acceleration measurement reflection grating and the two reference gratings are arranged on the piezoelectric substrate and are bonded to a substrate below the piezoelectric substrate, The uniform interdigital transducer is used for exciting and receiving the surface acoustic wave; the piezoelectric substrate is a POI piezoelectric substrate formed by a high-resistance substrate layer, an insulating layer and a piezoelectric monocrystalline layer; the two reference grids are respectively arranged at two sides close to the uniform interdigital transducer; the pressure measurement reflecting grating and the acceleration measurement reflecting grating are respectively arranged at two sides far away from the uniform interdigital transducer; the temperature measurement reflection grating is arranged between the reference grating and the pressure measurement reflection grating, which are positioned on the same side of the uniform interdigital transducer as the pressure measurement reflection grating; The substrate at least exposes the piezoelectric base below the acceleration measurement reflective grating to form a cantilever beam; And a pressure measuring cavity penetrating through the high-resistance substrate layer and the insulating layer is formed in the piezoelectric substrate between the temperature measuring reflecting grating and the pressure measuring reflecting grating.
2. The surface acoustic wave sensor of claim 1, wherein the piezoelectric single crystal layer in the piezoelectric substrate is made of lithium niobate, lithium tantalate, quartz, lead zirconate titanate or aluminum nitride, the insulating layer is a silicon dioxide layer or a silicon nitride layer or an aluminum oxide layer, and the high-resistance substrate layer is a high-resistance silicon layer or a high-resistance silicon carbide layer or a high-resistance gallium arsenide layer.
3. The surface acoustic wave sensor of claim 1, wherein the high-resistance substrate layer is a high-resistance silicon layer, the substrate is a glass substrate, and the high-resistance substrate layer and the substrate are pre-formed with an alumina transition layer on a bonding interface and bonded based on a low-temperature anodic bonding process.
4. The surface acoustic wave sensor according to claim 1, wherein a mass is fixed under the piezoelectric substrate under the acceleration-measuring reflecting grating.
5. The surface acoustic wave sensor according to claim 1 or 4, wherein the cantilever beam extends at least to the reference grid near the side where the cantilever beam is located, and the cantilever beam is provided with a micro-slit sensitization structure in an acceleration sensitive area, wherein the micro-slit sensitization structure is a plurality of micro-holes and/or micro-slits extending inwards from the lower surface of the high-resistance substrate layer towards the piezoelectric single crystal layer, and the extending depth of the micro-holes and/or micro-slits is not more than the thickness of the high-resistance substrate layer.
6. The surface acoustic wave sensor of claim 1, wherein the metal electrode of the uniform interdigital transducer is an aluminum film electrode, the line width is 0.5-1.0 μm, the interval is 0.5-1.0 μm, the interdigital pair number is 20-50 pairs, the length is 50-200 μm, the propagation direction of the surface acoustic wave is kept consistent, the surface acoustic wave is excited towards two sides, and the working frequency is in a frequency band range between 10 MHz-10 GHz.
7. A surface acoustic wave sensor packaging structure is characterized by comprising the surface acoustic wave sensor, a cover plate and a containing base according to any one of claims 1-6, The surface acoustic wave sensor is accommodated in the accommodating base; The cover plate is buckled on the accommodating base to form an SMD packaging structure; An antenna is fixed below the accommodating base.
8. The surface acoustic wave sensor package structure of claim 7, wherein the cover plate is a glass cover plate and the receiving base is a ceramic base.
9. The surface acoustic wave sensor package structure of claim 7, further comprising a solder bond wire electrically connected to the uniform interdigital transducer.
10. The surface acoustic wave sensor package structure of claim 9, wherein the bonding wire is gold wire, silicon aluminum wire, or platinum wire.
11. The surface acoustic wave sensor package structure of claim 7, further comprising a vent hole disposed on the cover plate or the bottom wall of the accommodating base, wherein the vent hole penetrates through the cover plate and is located above the pressure measuring cavity when the vent hole is disposed on the cover plate, and penetrates through the bottom wall of the accommodating base and the substrate of the surface acoustic wave sensor to communicate with the pressure measuring cavity when the vent hole is disposed on the bottom wall of the accommodating base.
12. The surface acoustic wave sensor package structure of claim 11, wherein the pressure measuring cavity forms a sealed space and introduces inert gas when the vent holes are arranged on the cover plate, and forms a sealed space and introduces inert gas between the cover plate and the piezoelectric substrate when the vent holes are arranged on the bottom wall of the accommodating base.
13. The surface acoustic wave sensor package structure of claim 7, further comprising an overload damping block disposed on an inner wall of the cover plate and/or an inner side of a bottom wall of the accommodating base and corresponding to an acceleration measuring reflective grating region of the surface acoustic wave sensor.
14. The surface acoustic wave sensor package structure of claim 13, wherein the overload damping block is made of a silicone rubber material.

Description

Surface acoustic wave sensor and packaging structure thereof Technical Field The invention belongs to the technical field of sensors, and particularly relates to a surface acoustic wave sensor and a packaging structure thereof. Background The surface acoustic wave (Surface Acoustic Wave, SAW) sensor is a passive wireless sensor based on the piezoelectric effect and the acoustic wave propagation characteristics, and the working principle is that an interdigital transducer (IDT) on the surface of a piezoelectric substrate is used for exciting and receiving the acoustic surface wave, and the sensing is realized by utilizing the modulation effect of external physical quantities (such as temperature, pressure, acceleration and the like) on the acoustic wave propagation characteristics. Compared with the traditional wired sensor, the SAW sensor has the remarkable advantages of small volume, high sensitivity, electromagnetic interference resistance, no need of external power supply and the like, and has been widely applied to the fields of aerospace, industrial monitoring, medical equipment and the like. However, the existing SAW sensor is limited to single parameter detection, and lacks an integrated design, for example, other parameters such as pressure, strain and the like cannot be monitored simultaneously when temperature parameters are monitored. This single parameter detection mode results in multiple independent sensors being deployed to cover the multi-parameter requirements of temperature, pressure, acceleration, etc. in complex application scenarios (e.g., aircraft condition monitoring, engine health diagnostics). This not only greatly increases system complexity and wiring costs, but also reduces overall reliability due to space competition and signal interference between sensors. In recent years, there have been attempts to integrate multi-parameter sensing functions into a single SAW sensor, but significant drawbacks remain. Few sensors capable of realizing multi-parameter detection adopt a multi-group interdigital transducer (IDT) and reflective grating stacking design, and adopt discrete reflective grating to realize differential measurement, but the sensors have limitations in the aspects of integration level, signal separation efficiency and the like. The structure not only increases signal transmission loss, but also causes cross interference due to multi-physical field coupling, and the size of a device is difficult to miniaturize due to excessive reflecting grids, so that the application requirement of a narrow space is difficult to meet. In addition, the increase in the number of reflective gates can further exacerbate process complexity, affecting device yield and uniformity. In summary, the existing SAW sensor has significant shortcomings in multi-parameter integration, miniaturization and anti-interference capability. The novel integrated SAW sensor which has a compact structure and can synchronously detect temperature, pressure and acceleration with high precision is developed, and the novel integrated SAW sensor becomes a key requirement for breaking through the bottleneck of real-time monitoring of multiple physical quantities under complex working conditions. Disclosure of Invention In view of the above drawbacks of the prior art, an object of the present invention is to provide a surface acoustic wave sensor and a packaging structure thereof, which are used for solving the problems of single function, large size and low anti-interference capability of the surface acoustic wave sensor in the prior art. To achieve the above and other related objects, the present invention provides a surface acoustic wave sensor comprising a piezoelectric substrate, a surface acoustic wave uniform interdigital transducer, a temperature measurement reflection grating, a pressure measurement reflection grating, an acceleration measurement reflection grating, and two reference gratings, which are disposed on the piezoelectric substrate, bonded to a substrate under the piezoelectric substrate, The uniform interdigital transducer is used for exciting and receiving the surface acoustic wave; the piezoelectric substrate is a POI piezoelectric substrate formed by a high-resistance substrate layer, an insulating layer and a piezoelectric monocrystalline layer; the two reference grids are respectively arranged at two sides close to the uniform interdigital transducer; the pressure measurement reflecting grating and the acceleration measurement reflecting grating are respectively arranged at two sides far away from the uniform interdigital transducer; the temperature measurement reflection grating is arranged between the reference grating and the pressure measurement reflection grating, which are positioned on the same side of the uniform interdigital transducer as the pressure measurement reflection grating; The substrate at least exposes the piezoelectric base below the acceleration measurement reflective grating