Surface acoustic wave integrated sensor and preparation method thereof

Abstract

The present application discloses a surface acoustic wave integrated sensor and a preparation method thereof, belonging to the field of semiconductor technology. The surface acoustic wave integrated sensor includes a plurality of sensing units. Each sensing unit includes a channel layer, a barrier layer, a first electrode and a second electrode, the barrier layer includes a first interdigitated electrode and a second interdigitated electrode, the first interdigitated electrode and the second interdigitated electrode are cross-arranged, the first electrode is electrically connected to the first interdigitated electrode, and the second electrode is electrically connected to the second interdigitated electrode. The surface acoustic wave propagates on the material surface of the first interdigitated electrode and the second interdigitated electrode, and its propagation characteristics (such as speed, phase and amplitude) are affected by changes in the surrounding environment. By calibrating the magnitude of the frequency displacement of the electrical signal on the first electrode and the second electrode, the detection of changes in the external environment is achieved.

Description

Technical Field

[0001] The present application belongs to the field of semiconductor technology, and in particular relates to a surface acoustic wave integrated sensor and a preparation method thereof. Background Art

[0002] At present, surface acoustic wave sensor is a sensor widely used in various environmental monitoring and detection systems. Its basic working principle is based on the piezoelectric effect. Commonly used piezoelectric materials include quartz, lithium niobate and lead zirconate titanate. These materials have some significant disadvantages and limitations, such as poor performance in high temperature or strong ultraviolet environments, poor sensitivity and accuracy, difficulty in integration and high energy consumption.

[0003] How to overcome the above-mentioned material limitations has become an urgent problem to be solved in this field. Summary of the invention

[0004] The present application provides a surface acoustic wave integrated sensor and a preparation method thereof, aiming to improve its accuracy and enhance its anti-interference capability.

[0005] In a first aspect, the present application provides a surface acoustic wave integrated sensor, comprising a substrate and a plurality of sensing units arranged on the substrate. Each sensing unit comprises a channel layer, a barrier layer, a first electrode, and a second electrode, wherein the channel layer is arranged on the substrate, the barrier layer is arranged on a side of the channel layer away from the substrate, the barrier layer comprises a first interdigitated electrode and a second interdigitated electrode, the first interdigitated electrode and the second interdigitated electrode are arranged crosswise, the first electrode and the second electrode are both arranged on a side of the barrier layer away from the substrate, the first electrode is electrically connected to the first interdigitated electrode, and the second electrode is electrically connected to the second interdigitated electrode.

[0006] In some embodiments, the plurality of sensing units include at least a first sensing unit, and the first sensing unit is used to detect pressure.

[0007] In some embodiments, the plurality of sensing units include at least a second sensing unit, and the second sensing unit is used to detect temperature. In addition, the surface acoustic wave integrated sensor also includes a first hollow portion that at least penetrates the channel layer and the barrier layer, and the orthographic projection of the first hollow portion on the substrate is located around the orthographic projection of the second sensing unit on the substrate.

[0008] In some embodiments, the multiple sensing units include at least a third sensing unit, and the third sensing unit is used to detect ultraviolet rays. In addition, the barrier layer of the third sensing unit also includes a heating unit, and the heating unit is arranged between the first interdigitated electrode and the second interdigitated electrode of the third sensing unit. The third sensing unit also includes a third electrode and a fourth electrode, and the third electrode and the fourth electrode are electrically connected to the heating unit respectively. The surface acoustic wave integrated sensor also includes a second hollow portion that at least penetrates the channel layer and the barrier layer, and the orthographic projection of the second hollow portion on the substrate is located around the orthographic projection of the third sensing unit on the substrate.

[0009] In some embodiments, first electrodes of the various sensing units are electrically connected to each other, and second electrodes of the various sensing units are electrically connected to each other.

[0010] In some embodiments, the material of the channel layer includes at least one of gallium nitride, gallium arsenide, or indium gallium arsenide, and the material of the barrier layer includes at least one of indium gallium nitride, aluminum gallium nitride, indium phosphide, aluminum gallium arsenide, or indium aluminum arsenide.

[0011] In some embodiments, the sensing unit further includes a buffer layer disposed between the substrate and the channel layer.

[0012] In some embodiments, the substrate includes a plurality of cavities extending therethrough, and the orthographic projection of each sensing unit on the substrate is located within the region where a cavity is located.

[0013] In some embodiments, the surface acoustic wave integrated sensor further comprises a bonding layer, which is disposed on a side of the substrate away from the plurality of sensing units. The sensing unit further comprises a first ohmic contact layer and a second ohmic contact layer, the first ohmic contact layer being disposed between the first interdigitated electrode and the first electrode, and the second ohmic contact layer being disposed between the second interdigitated electrode and the second electrode.

[0014] In a second aspect, the present application further provides a method for preparing a surface acoustic wave integrated sensor, comprising the following steps S10 to S30:

[0015] Step S10: forming a channel layer on the substrate.

[0016] Step S20: forming a barrier layer on a side of the channel layer away from the substrate, wherein the barrier layer includes first interdigitating electrodes and second interdigitating electrodes of a plurality of sensing units, wherein the first interdigitating electrodes and the second interdigitating electrodes are arranged crosswise.

[0017] Step S30: forming a first electrode and a second electrode on a side of the barrier layer away from the substrate, wherein the first electrode is electrically connected to the first interdigitating electrode, and the second electrode is electrically connected to the second interdigitating electrode.

[0018] The surface acoustic wave integrated sensor provided in the embodiment of the present application includes a substrate and a plurality of sensing units arranged on the substrate, and different sensing units can be used to detect different environmental factors. Each sensing unit includes a channel layer, a barrier layer, a first electrode, and a second electrode, wherein the channel layer is arranged on the substrate, the barrier layer is arranged on a side of the channel layer away from the substrate, the barrier layer includes a first interdigitated electrode and a second interdigitated electrode, the first interdigitated electrode and the second interdigitated electrode are arranged crosswise, the first electrode and the second electrode are both arranged on a side of the barrier layer away from the substrate, the first electrode is electrically connected to the first interdigitated electrode, and the second electrode is electrically connected to the second interdigitated electrode.

[0019] For each sensing unit, the first electrode and the second electrode are respectively connected to related equipment such as an interdigital transducer to excite and receive surface acoustic waves. The surface acoustic waves propagate on the material surface of the first interdigital electrode and the second interdigital electrode, and their propagation characteristics (such as speed, phase and amplitude) are affected by changes in the surrounding environment. For example, by inputting a high-frequency signal at a resonant frequency into one of the two interdigital electrodes, the interdigital electrode will produce mechanical deformation and vibrate due to the piezoelectric effect. The vibration will propagate along the surface of the material and be received by the other interdigital electrode, converting the mechanical signal generated by the sound wave into an electrical signal. When the external environment (such as pressure, temperature, ultraviolet intensity, etc.) changes, the transmission of the sound wave will be affected, causing the frequency to shift. By calibrating the magnitude of the frequency shift, the detection of changes in the external environment is achieved.

[0020] In addition, the surface acoustic wave integrated sensor provided in the embodiment of the present application integrates multiple sensing units, each sensing unit detects different environmental changes respectively, and multiple environmental factors can be analyzed simultaneously, which is beneficial to eliminating the influence of other environmental factors on the detection results of a certain detected object. It has strong anti-interference ability, is beneficial to improve the accuracy of the detection results, improves the system integration, is beneficial to reduce costs and power consumption, and significantly improves sensor performance.

[0021] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0023] Figure 1 A top view of a surface acoustic wave integrated sensor provided in an embodiment of the present application;

[0024] Figure 2 for Figure 1 A cross-sectional view of the SAW integrated sensor along the section line AA';

[0025] Figure 3 A flow chart of a method for preparing a surface acoustic wave integrated sensor provided in an embodiment of the present application;

[0026] Figure 4 to Figure 12 A diagram of the steps for preparing a surface acoustic wave integrated sensor provided in an embodiment of the present application. DETAILED DESCRIPTION

[0027] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in some embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments provided by the present application, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present application.

[0028] Unless the context requires otherwise, throughout the specification and claims, the term "comprising" is to be construed in an open, inclusive sense, ie, meaning "including, but not limited to."

[0029] In the following, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present application, unless otherwise specified, "plurality" means two or more.

[0030] When describing some embodiments, the term "connection" and its derivative expressions may be used. The term "connection" should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For example, when describing some embodiments, the term "connection" may be used to indicate that two or more components are in direct physical or electrical contact with each other.

[0031] Additionally, the use of “based on” is meant to be open and inclusive, as a process, step, calculation, or other action “based on” one or more stated conditions or values ​​may, in practice, be based on additional conditions or values ​​beyond those stated.

[0032] It will be understood that when a layer or an element is referred to as being on another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may be present between the layer or element and the other layer or substrate.

[0033] Exemplary embodiments are described herein with reference to cross-sectional views that are idealized exemplary drawings. In the drawings, the thickness of layers and the area of ​​regions are exaggerated for clarity. Therefore, variations in shape relative to the drawings due to, for example, manufacturing techniques and / or tolerances are conceivable. Therefore, the exemplary embodiments should not be interpreted as being limited to the shapes of the regions shown herein, but include deviations in shape due to, for example, manufacturing. Therefore, the regions shown in the drawings are schematic in nature, and their shapes are not intended to illustrate the actual shape of regions of the device, and are not intended to limit the scope of the exemplary embodiments.

[0034] Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0035] At present, the piezoelectric materials commonly used in surface acoustic wave integrated sensors include quartz, lithium niobate and lead zirconate titanate, etc. These materials have some significant disadvantages and limitations, such as poor performance in high temperature environment or strong ultraviolet environment, poor sensitivity and temperature resistance, difficult integration and high energy consumption. In addition, the sensor application environment is usually more complex. At present, surface acoustic wave integrated sensors usually detect a single environmental parameter, cannot eliminate the influence of other environmental factors, and have poor anti-interference ability.

[0036] To solve the above problems, the present application provides a surface acoustic wave integrated sensor, such as Figure 1~Figure 2 As shown, Figure 1 A top view of a surface acoustic wave integrated sensor provided in an embodiment of the present application, Figure 2 for Figure 1 A cross-sectional view of the SAW integrated sensor along section line AA'.

[0037] The surface acoustic wave integrated sensor 10 includes a substrate 11 and a plurality of sensing units 100 disposed on the substrate 11. Each sensing unit 100 includes a channel layer 12, a barrier layer 13, a first electrode 141 and a second electrode 142, wherein the channel layer 12 is disposed on the substrate 11, the barrier layer 13 is disposed on a side of the channel layer 12 away from the substrate 11, the barrier layer 13 includes a first interdigitated electrode 131 and a second interdigitated electrode 132, the first interdigitated electrode 131 and the second interdigitated electrode 132 are disposed crosswise, the first electrode 141 and the second electrode 142 are both disposed on a side of the barrier layer 13 away from the substrate 11, the first electrode 141 is electrically connected to the first interdigitated electrode 131, and the second electrode 142 is electrically connected to the second interdigitated electrode 132.

[0038] The surface acoustic wave integrated sensor 10 provided in the embodiment of the present application includes a plurality of sensing units 100, and different sensing units 100 can be used to detect different environmental factors. For each sensing unit 100, the first electrode 141 and the second electrode 142 can be respectively connected to relevant equipment (such as an interdigital transducer) to excite and receive surface acoustic waves. The surface acoustic waves propagate on the material surface of the first interdigital electrode 131 and the second interdigital electrode 132, and their propagation characteristics (such as speed, phase and amplitude) are affected by changes in the surrounding environment.

[0039] Exemplarily, a high-frequency signal at a certain resonant frequency is input to the first interdigitated electrode 131 through the first electrode 141. Due to the piezoelectric effect, the first interdigitated electrode 131 will produce mechanical deformation and vibration, and the vibration will propagate along the surface of the material and be received by the second interdigitated electrode 132. The second electrode 142 converts the mechanical signal generated by the sound wave into an electrical signal and transmits it to the relevant equipment. Since each sensing unit 100 includes a channel layer 12 and a barrier layer 13, the channel layer 12 and the barrier layer 13 form a heterostructure, and its self-polarization effect will generate polarized surface charges on the surface. When the external environment (such as pressure, temperature, ultraviolet intensity, humidity, gas type, etc.) changes, the self-polarization effect will be affected, and then the transmission of the surface acoustic wave on the first interdigitated electrode 131 and the second interdigitated electrode 132 will be affected, thereby causing the frequency to shift. By calibrating the magnitude of the frequency displacement of the electrical signal received by the second electrode 142 relative to the electrical signal input by the first electrode 141, the detection of changes in the external environment can be achieved.

[0040] In addition, the surface acoustic wave integrated sensor 10 provided in the embodiment of the present application integrates multiple sensing units 100, each sensing unit 100 detects different environmental changes, such as pressure, temperature, ultraviolet intensity, etc., and multiple environmental factors can be analyzed simultaneously, which is beneficial to eliminating the influence of other environmental factors on the detection results of a certain detected object. It has strong anti-interference ability, is beneficial to improve the accuracy of the detection results, improves the system integration, is beneficial to reduce costs and power consumption, and significantly improves sensor performance.

[0041] For example, in some embodiments, Figure 1 As shown, the various sensing units 100 include at least a first sensing unit 101, and the first sensing unit 101 is used to detect pressure.

[0042] The pressure here includes air pressure. When the external pressure changes, the channel layer 12 and the barrier layer 13 will deform, affecting the self-polarization of the heterostructure, and then affecting the transmission of the surface acoustic wave, causing the frequency of the electrical signal on the first electrode 141 and the second electrode 142 to shift. By calibrating the frequency displacement, the magnitude of the external pressure can be reflected.

[0043] For example, in some embodiments, Figure 1 As shown, the various sensing units 100 at least include a second sensing unit 102, and the second sensing unit 102 is used to detect temperature. In addition, the surface acoustic wave integrated sensor 10 also includes a first hollow portion L1 that at least penetrates the channel layer 12 and the barrier layer 13, and the orthographic projection of the first hollow portion L1 on the substrate 11 is located around the orthographic projection of the second sensing unit 102 on the substrate 11.

[0044] That is, the first hollow portion L1 surrounds the outside of the second sensor unit 102. When the external temperature changes, the first hollow portion L1 can reduce the heat loss through conduction of the solid, which is beneficial to ensure the heat exchange between the second sensor unit 102 and the external temperature and ensure that the temperature of the second sensor unit 102 is closer to the external temperature.

[0045] Based on this, when the external temperature changes, the solid material will undergo slight deformation under the action of thermal stress, affecting the self-polarization of the heterostructure, and then affecting the transmission of the surface acoustic wave, causing the frequency of the electrical signals on the first electrode 141 and the second electrode 142 to shift. By calibrating the frequency shift, the external temperature can be reflected.

[0046] For example, Figure 1 As shown, the first sensing unit 101 on the surface acoustic wave integrated sensor 10 provided in the embodiment of the present application is used to detect pressure, and the second sensing unit 102 is used to detect temperature. The above two environmental factors are analyzed simultaneously. For example, according to the temperature detection result of the second sensing unit 102, the pressure detection result of the first sensing unit 101 is temperature compensated, which is beneficial to eliminate the influence of temperature factors on the pressure detection result. It has strong anti-interference ability, is beneficial to improve the accuracy of the detection result, improves the system integration, is beneficial to reduce the cost and power consumption, and significantly improves the sensor performance.

[0047] In some embodiments, Figure 1 As shown, the various sensing units 100 include at least a third sensing unit 103, and the third sensing unit 103 is used to detect ultraviolet rays. In addition, the barrier layer 13 of the third sensing unit 103 also includes a heating portion 133, and the heating portion 133 is arranged between the first interdigitating electrode 131 and the second interdigitating electrode 132 of the third sensing unit 103. The third sensing unit 103 also includes a third electrode 143 and a fourth electrode 144, and the third electrode 143 and the fourth electrode 144 are electrically connected to the heating portion 133 respectively. The surface acoustic wave integrated sensor 10 also includes a second hollow portion L2 that at least penetrates the channel layer 12 and the barrier layer 13, and the orthographic projection of the second hollow portion L2 on the substrate 11 is located around the orthographic projection of the third sensing unit 103 on the substrate 11.

[0048] The third electrode 143 and the fourth electrode 144 are used to connect an external fixed voltage as a heating power source for the heating portion 133. The heating portion 133 and the channel layer 12 here can be regarded as a heating resistor. When the intensity of external ultraviolet rays changes, the concentration of the two-dimensional electron gas in the heterostructure formed by the heating portion 133 and the channel layer 12 will also change, which can be regarded as a change in the resistance value of the heating resistor, thereby changing its power consumption, that is, changing the heating power of the heating portion 133, and then changing the temperature of the sensing unit 103. The second hollow portion L2 surrounds the outside of the third sensing unit 103, which can reduce the heat loss through solid conduction and keep the temperature change brought by the heating portion 133 in the third sensing unit 103 as much as possible.

[0049] Based on this, changes in ultraviolet intensity will affect the heating power of the heating part 133 and thus cause the temperature of the third sensing unit 103 to change. When the temperature of the third sensing unit 103 changes, the self-polarization effect of the heterostructure will be affected, thereby affecting the transmission of the surface acoustic wave, causing the frequency of the electrical signal on the first electrode 141 and the second electrode 142 to shift. By calibrating the frequency displacement of the electrical signal on the first electrode 141 and the second electrode 142, the external ultraviolet intensity can be reflected.

[0050] In some embodiments, Figure 1 As shown, the first electrodes 141 of the various sensing units 100 are electrically connected to each other, and the second electrodes 142 of the various sensing units 100 are electrically connected to each other.

[0051] Through the above connection relationship, multiple sensor units 100 can be connected to the same set of external devices (such as interdigital transducers), which is conducive to eliminating interference from external factors, and has a high degree of integration, which is conducive to reducing costs and power consumption.

[0052] In some embodiments, the material of the channel layer 12 includes at least one of gallium nitride, gallium arsenide, or indium gallium arsenide, and the material of the barrier layer 13 includes at least one of indium gallium nitride, aluminum gallium nitride, indium phosphide, aluminum gallium arsenide, or indium aluminum arsenide.

[0053] The channel layer 12 and the barrier layer 13 are used to form a heterostructure, so that when the external environment changes, the propagation of the surface acoustic wave is affected by the self-polarization effect. The above materials provided in the embodiments of the present application all have good piezoelectric effect, show good performance in high temperature environment or strong ultraviolet environment, and have high sensitivity and reliability. Based on this, the surface acoustic wave integrated sensor 10 is suitable for the fields of industry, medical treatment and environmental detection.

[0054] In some embodiments, Figure 2As shown, in order to improve the lattice mismatch problem and reduce the dislocation density, the sensor unit 100 further includes a buffer layer 15 , and the buffer layer 15 is disposed between the substrate 11 and the channel layer 12 .

[0055] In some embodiments, Figure 2 As shown, the substrate 11 includes a plurality of cavities K0 penetrating therethrough, and the orthographic projection of each sensing unit 100 on the substrate 11 is located within the region where a cavity K0 is located.

[0056] Exemplarily, for the first sensing unit 101, the cavity K0 is conducive to the formation of a suspended membrane structure of the first sensing unit 101. Under the action of pressure, the deformation of the channel layer 12 and the barrier layer 13 is more obvious, the self-polarization effect of the heterostructure is also more obvious, the influence on the transmission of the surface acoustic wave is also more obvious, and the frequency displacement is easier to detect, that is, the sensitivity of the first sensing unit 101 is improved.

[0057] The same is true for other sensing units 100, and for the second sensor 102 and the third sensor 103, the setting of the cavity K0 is also beneficial to reduce the conduction loss of heat in the solid and improve the sensitivity. In addition, the multiple sensing units 100 are all provided with corresponding cavities K0, which is beneficial to serve as control groups and eliminate the influence of other environmental factors on the detection results of a certain detected object.

[0058] In some embodiments, Figure 2 As shown, the surface acoustic wave integrated sensor 10 further includes a bonding layer 16, which is disposed on a side of the substrate 11 away from the various sensing units 100. The sensing unit 100 further includes a first ohmic contact layer 171 and a second ohmic contact layer 172, wherein the first ohmic contact layer 171 is disposed between the first interdigitated electrode 131 and the first electrode 141, and the second ohmic contact layer 172 is disposed between the second interdigitated electrode 132 and the second electrode 142.

[0059] The bonding layer 16 can be used to provide a flat surface for the surface acoustic wave integrated sensor 10 , the first ohmic contact layer 171 is used to ensure good electrical connection between the first finger electrode 131 and the first electrode 141 , and the second ohmic contact layer 172 is used to ensure good electrical connection between the second finger electrode 132 and the second electrode 142 .

[0060] In a second aspect, the present application also provides a method for preparing a surface acoustic wave integrated sensor, such as Figure 3 As shown, Figure 3 A flow chart of a method for preparing a surface acoustic wave integrated sensor provided in an embodiment of the present application, Figure 4 to Figure 12 A diagram of the steps for preparing a surface acoustic wave integrated sensor provided in an embodiment of the present application.

[0061] The preparation method comprises the following steps S10 to S30:

[0062] Step S10: Figure 4 As shown, a channel layer 12 is formed on a substrate 11 .

[0063] Illustratively, in some embodiments, a buffer layer 15 is further disposed between the substrate 11 and the channel layer 12 to improve the lattice mismatch problem and reduce the dislocation density.

[0064] Step S20: Figure 5 As shown, a barrier layer 13 is formed on a side of the channel layer 12 away from the substrate 11 , and the barrier layer 13 includes first interdigital electrodes 131 and second interdigital electrodes 132 of various sensing units 100 , and the first interdigital electrodes 131 and the second interdigital electrodes 132 are arranged crosswise.

[0065] Exemplarily, in some embodiments, the multiple sensing units 100 include a first sensing unit 101, a second sensing unit 102, and a third sensing unit 103, wherein the barrier layer 13 of the third sensing unit 103 further includes a heating unit 133, and the heating unit 133 is disposed between the first interdigitating electrode 131 and the second interdigitating electrode 132 of the third sensing unit 103. The first sensing unit 101 is used to detect pressure, the second sensing unit 102 is used to detect temperature, and the third sensing unit 103 is used to detect ultraviolet intensity.

[0066] Exemplarily, an inductively coupled plasma etching process may be used to form the morphology of the first finger electrodes 131 and the morphology of the second finger electrodes 132 of various sensor units 100, so that the first finger electrodes 131 and the second finger electrodes 132 of each sensor unit 100 are arranged crosswise.

[0067] Step S30: Figure 6~Figure 8 As shown, a first electrode 141 and a second electrode 142 are formed on a side of the barrier layer 13 away from the substrate 11 . The first electrode 141 is electrically connected to the first interdigitating electrode 131 , and the second electrode 142 is electrically connected to the second interdigitating electrode 132 .

[0068] For example, Figure 6As shown, to ensure good electrical connection, after the barrier layer 13 is formed, a first ohmic contact layer 171 is formed on the side of the first interdigital electrode 131 away from the substrate 11, and a second ohmic contact layer 172 is formed on the side of the second interdigital electrode 132 away from the substrate 11. The materials of the first ohmic contact layer 171 and the second ohmic contact layer 172 include but are not limited to at least one of gold, aluminum, platinum, molybdenum, etc., and the thickness ranges from 50nm to 1000nm, and the first ohmic contact layer 171 and the second ohmic contact layer 172 can be prepared by the same process. In some embodiments, to ensure the subsequent electrical connection of the heating part 133 of the third sensor unit 103, an ohmic contact layer is also formed simultaneously on the side of both ends of the heating part 133 away from the substrate 11.

[0069] Then, if Figure 7 As shown, a first passivation layer 21 is formed, and the first passivation layer 21 exposes the first ohmic contact layer 171 and the second ohmic contact layer 172 of the various sensing units 100. The material of the first passivation layer 21 includes but is not limited to silicon nitride, silicon dioxide, aluminum oxide, etc., and the thickness ranges from 100nm to 500nm. In some embodiments, the first passivation layer 21 also exposes the ohmic contact layers at both ends of the heating portion 133.

[0070] Afterwards, if Figure 8 As shown, electron beam evaporation or magnetron sputtering is used to form a first electrode 141 on a side of the first ohmic contact layer 171 away from the substrate 11, and a second electrode 142 is formed on a side of the second ohmic contact layer 172 away from the substrate 11. The materials of the first electrode 141 and the second electrode 142 include but are not limited to at least one of gold, silver, aluminum, copper, platinum, palladium, titanium, etc. In some embodiments, in the process of forming the first electrode 141 and the second electrode 142, a third electrode 143 and a fourth electrode 144 are also formed simultaneously, and the third electrode 143 and the fourth electrode 144 are electrically connected to the two ends of the heating part 133, respectively. The third electrode 143 and the fourth electrode 144 are both located on the side of the ohmic contact layer at both ends of the heating part 133 away from the substrate 11. Limited by the viewing angle of the cross-sectional view, Figure 8 In the figure, only the fourth electrode 144 is used as an example to illustrate the film structure. The third electrode 143 is located at the other end of the heating portion 133 away from the fourth electrode 144, and its film structure is the same as the film structure of the fourth electrode 144. The third electrode 143 is not illustrated in this figure. The relative position relationship between the third electrode 143 and the fourth electrode 144 and the heating portion 133 can be combined with Figure 1 Shown to be understood.

[0071] Next, in order to improve the performance of the surface acoustic wave integrated sensor 10, as Fig. 9As shown, the second passivation layer 22 is formed by plasma enhanced chemical vapor deposition process. The material of the second passivation layer 22 includes but is not limited to silicon nitride, silicon dioxide, aluminum oxide, etc., and the thickness ranges from 100nm to 500nm.

[0072] Then, in some embodiments, to form Figure 1 The surface acoustic wave integrated sensor 10 shown in FIG. Fig.10 As shown, an inductively coupled plasma etching process is used to etch a first hollow portion L1 outside the second sensing unit 102, and a second hollow portion L2 is etched outside the third sensing unit 103. Both the first hollow portion L1 and the second hollow portion L2 expose the substrate 11.

[0073] Then, if Fig.11 As shown, the substrate 11 is thinned and deep silicon etching is performed from the back side of the substrate 11, and the etching depth is the thickness of the substrate 11 to form a plurality of cavities K0. The orthographic projection of each sensing unit 100 on the substrate 11 is located within the region where a cavity K0 is located.

[0074] Finally, if Fig.12 As shown, a bonding layer 16 is formed on a side of the substrate 11 away from the various sensing units 100 by gold-gold bonding, anode bonding or silicon-silicon bonding.

[0075] So far, we can form Figure 1 An integrated surface acoustic wave sensor 10 is shown.

[0076] The preparation method has a relatively simple preparation process, and the prepared surface acoustic wave integrated sensor 10 includes a variety of sensing units 100, and different sensing units 100 can be used to detect different environmental factors. Since each sensing unit 100 includes a channel layer 12 and a barrier layer 13, the channel layer 12 and the barrier layer 13 form a heterostructure, and their self-polarization effect will generate polarized surface charges on the surface. When the external environment (such as pressure, temperature, ultraviolet intensity, etc.) changes, the self-polarization effect will be affected, and then the transmission of the surface acoustic wave on the first interdigitated electrode 131 and the second interdigitated electrode 132 will be affected, thereby causing the frequency to shift. By calibrating the magnitude of the frequency displacement of the electrical signal received by the second electrode 142 relative to the electrical signal input by the first electrode 141, the detection of changes in the external environment can be achieved.

[0077] In addition, the surface acoustic wave integrated sensor 10 provided in the embodiment of the present application integrates multiple sensing units 100, each sensing unit 100 detects different environmental changes, such as pressure, temperature, ultraviolet intensity, etc., and multiple environmental factors can be analyzed simultaneously, which is beneficial to eliminating the influence of other environmental factors on the detection results of a certain detected object. It has strong anti-interference ability, is beneficial to improve the accuracy of the detection results, improves the system integration, is beneficial to reduce costs and power consumption, and significantly improves sensor performance.

[0078] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that a person skilled in the art can think of within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A surface acoustic wave integrated sensor, characterized in that: It includes a substrate, and a plurality of sensing units arranged on the substrate; Each sensor unit includes: A channel layer is disposed on the substrate; A barrier layer is arranged on a side of the channel layer away from the substrate, the barrier layer comprises a first interdigitating electrode and a second interdigitating electrode, and the first interdigitating electrode and the second interdigitating electrode are arranged crosswise; A first electrode and a second electrode are both arranged on a side of the barrier layer away from the substrate; the first electrode is electrically connected to the first interdigitated electrode, and the second electrode is electrically connected to the second interdigitated electrode; The plurality of sensing units include at least a third sensing unit, and the third sensing unit is used to detect ultraviolet rays; The barrier layer of the third sensing unit further includes a heating portion, which is disposed between the first interdigitating electrode and the second interdigitating electrode of the third sensing unit; the third sensing unit further includes a third electrode and a fourth electrode, which are electrically connected to the heating portion respectively; The surface acoustic wave integrated sensor further includes a second hollow portion at least penetrating the channel layer and the barrier layer, and the orthographic projection of the second hollow portion on the substrate is located around the orthographic projection of the third sensing unit on the substrate.

2. The surface acoustic wave integrated sensor according to claim 1, characterized in that: The plurality of sensing units include at least a first sensing unit, and the first sensing unit is used to detect pressure.

3. The surface acoustic wave integrated sensor according to claim 1, characterized in that: The plurality of sensing units include at least a second sensing unit, wherein the second sensing unit is used to detect temperature; The surface acoustic wave integrated sensor further includes a first hollow portion at least penetrating the channel layer and the barrier layer, wherein the orthographic projection of the first hollow portion on the substrate is located around the orthographic projection of the second sensing unit on the substrate.

4. The surface acoustic wave integrated sensor according to claim 1, characterized in that: The first electrodes of the plurality of sensing units are electrically connected to each other, and the second electrodes of the plurality of sensing units are electrically connected to each other.

5. The surface acoustic wave integrated sensor according to claim 1, characterized in that: The material of the channel layer includes at least one of gallium nitride, gallium arsenide or indium gallium arsenide, and the material of the barrier layer includes at least one of indium gallium nitride, aluminum gallium nitride, indium phosphide, aluminum gallium arsenide or indium aluminum arsenide.

6. The surface acoustic wave integrated sensor according to claim 1, characterized in that: The sensing unit further includes a buffer layer, and the buffer layer is arranged between the substrate and the channel layer.

7. The surface acoustic wave integrated sensor according to claim 1, characterized in that: The substrate includes a plurality of cavities penetrating therethrough, and the orthographic projection of each sensing unit on the substrate is located within the region where a cavity is located.

8. The surface acoustic wave integrated sensor according to claim 1, characterized in that: The surface acoustic wave integrated sensor further comprises a bonding layer, wherein the bonding layer is arranged on a side of the substrate away from the plurality of sensing units; The sensing unit further includes a first ohmic contact layer and a second ohmic contact layer, wherein the first ohmic contact layer is disposed between the first interdigitated electrode and the first electrode, and the second ohmic contact layer is disposed between the second interdigitated electrode and the second electrode.

9. A method for preparing a surface acoustic wave integrated sensor, characterized in that: include: forming a channel layer on a substrate; Forming a barrier layer on a side of the channel layer away from the substrate, the barrier layer comprising first interdigitating electrodes and second interdigitating electrodes of a plurality of sensing units, wherein the first interdigitating electrodes and the second interdigitating electrodes are arranged crosswise; forming a first electrode and a second electrode on a side of the barrier layer away from the substrate, wherein the first electrode is electrically connected to the first interdigitated electrode, and the second electrode is electrically connected to the second interdigitated electrode; The plurality of sensing units include at least a third sensing unit, and the third sensing unit is used to detect ultraviolet rays; The barrier layer of the third sensing unit further includes a heating portion, which is disposed between the first interdigitating electrode and the second interdigitating electrode of the third sensing unit; the third sensing unit further includes a third electrode and a fourth electrode, which are electrically connected to the heating portion respectively; The surface acoustic wave integrated sensor further includes a second hollow portion at least penetrating the channel layer and the barrier layer, and the orthographic projection of the second hollow portion on the substrate is located around the orthographic projection of the third sensing unit on the substrate.

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