Sensor system and preparation method thereof

Abstract

The invention provides a sensor system and a preparation method thereof, relates to the technical field of semiconductors, and aims to improve the reliability of the system. The sensor system comprises a wireless passive sensor, an inquiry antenna, a response antenna and a reading circuit, the inquiry antenna is used for transmitting inquiry signals, the wireless passive sensor is used for receiving the inquiry signals and reflecting response signals, the response antenna is used for receiving the response signals, and the reading circuit is used for reading detection results according to the response signals. The wireless passive sensor comprises a substrate, a shielding layer, a high-electron-mobility transistor and a resonant part, the substrate comprises a first surface and a second surface which are opposite, the shielding layer is arranged on the first surface, and the high-electron-mobility transistor is arranged on the second surface. The high electron mobility transistor comprises a sensitive material electrode, a source electrode and a drain electrode, and the sensitive material electrode is located between the source electrode and the drain electrode. The resonance part is arranged on the second surface and electrically connected with the source electrode and the drain electrode. A sensor system may be used to detect environmental parameters.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor technology, and in particular to a sensor system and a preparation method thereof. BACKGROUND

[0002] In harsh environments such as high temperature, high pressure, high electric field, or passive scenes, active sensors and their backend processing circuits will be disturbed by the environment, causing errors in sensor detection results or direct damage and other problems. Secondly, due to the influence of harsh environments, the power supply, wiring and backend processing circuit of the sensor will also face severe challenges. SUMMARY

[0003] The present application provides a sensor system and a preparation method thereof, aiming to improve the reliability of the sensor system.

[0004] In a first aspect, the present application provides a sensor system, which comprises a wireless passive sensor, an interrogation antenna, a response antenna and a reading circuit, the interrogation antenna is used for transmitting an interrogation signal, the wireless passive sensor is used for receiving the interrogation signal and reflecting a response signal, the response antenna is used for receiving the response signal, and the reading circuit is electrically connected with the response antenna, and the reading circuit is used for reading a detection result according to the response signal.

[0005] The wireless passive sensor comprises a substrate, a shielding layer, a high electron mobility transistor and a resonator, the substrate comprises opposite first and second surfaces, the shielding layer is arranged on the first surface, and the high electron mobility transistor is arranged on the second surface. The high electron mobility transistor comprises a sensitive material electrode, a source electrode and a drain electrode, the sensitive material electrode is located between the source electrode and the drain electrode, and the sensitive material electrode is floating. The resonator is arranged on the second surface, the resonator is electrically connected with the source electrode and the drain electrode, and the resonator is floating.

[0006] The sensor system provided by the above-mentioned embodiments of the present application, in the wireless passive sensor, the source electrode and the drain electrode of the high electron mobility transistor are electrically connected with the resonator, the source electrode and the drain electrode of the high electron mobility transistor can be conducted through the two-dimensional electron gas to form a line of the resonator.

[0007] The sensitive material electrode acts as a false gate of the high electron mobility transistor, when the measured environmental parameter changes, the sensitive material electrode will sense the change of the environmental parameter and change the potential, the change of the potential of the sensitive material electrode will cause the change of the concentration of the two-dimensional electron gas in the heterojunction, thereby changing the resistance value of the conduction channel between the source electrode and the drain electrode, and further changing the resonant frequency of the resonator.

[0008] Based on this, the interrogation antenna and the response antenna are used to collect the change of the resonant frequency of the resonator, and the reading circuit can obtain the measured environmental parameter according to the corresponding relationship between the offset value of the resonant frequency and the measured environmental parameter.

[0009] The sensitive material electrode, the source electrode and the drain electrode do not need to receive a voltage signal, the sensitive material electrode is floating, and the sensitive material electrode is not connected to a signal line. The source electrode and the drain electrode are electrically connected to the resonant component, and are floating through the resonant component, so that the source electrode and the drain electrode are floating, that is, the wireless passive sensor can work without an external power supply. Moreover, by using the antenna integrated sensing technology, the reading circuit does not need to be integrated on the wireless passive sensor. Therefore, compared with an active sensor, the wireless passive sensor has higher detection precision and stability in a harsh environment such as high temperature, high pressure and high electric field or a passive scene, and is beneficial to improving the reliability of a sensor system.

[0010] In addition, the resonator adopts a high electron mobility transistor, and the high electron mobility transistor can realize the characteristic of always being on by using a two-dimensional electron gas, so that the wireless passive sensor has advantages of high sensitivity, non-contact measurement, wide test range, high precision, fast response, wide current test frequency, strong anti-interference ability, wide working temperature span and the like.

[0011] According to an embodiment of the present application, the high electron mobility transistor is a normally-on high electron mobility transistor, that is, the source electrode and the drain electrode can be conductive without receiving an excitation voltage.

[0012] According to an embodiment of the present application, the material of the sensitive material electrode includes a semiconductor gas sensitive material, and the semiconductor gas sensitive material can be used for detecting gas components and concentrations.

[0013] According to an embodiment of the present application, the high electron mobility transistor further includes a substrate and a heterojunction arranged on the substrate, the sensitive material electrode, the source electrode and the drain electrode are arranged on a side of the heterojunction away from the substrate, and the material of the heterojunction includes group IIIA-VIA elements.

[0014] The material formed by the group IIIA-VIA elements is a wide bandgap semiconductor material, and the material characteristics make the high electron mobility transistor have high electron mobility, saturation electron velocity and breakdown electric field, and the on-off characteristic of the high electron mobility transistor is good, so that the adjustable ability of the resonant frequency of the wireless passive sensor can be improved, and the sensitivity of adjustment can be improved.

[0015] According to an embodiment of the present application, the heterojunction includes a channel layer and a barrier layer which are arranged in layers on the substrate, 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.

[0016] According to an embodiment of the present application, the high electron mobility transistor further includes a buffer layer, the buffer layer is arranged between the substrate and the heterojunction, and the material of the buffer layer includes aluminum nitride.

[0017] The buffer layer is formed on the substrate first, and then the channel layer is formed on the buffer layer. Since the material of the buffer layer is aluminum nitride and the materials of the channel layer and the buffer layer both include group ⅢA-group ⅤA elements, the lattices of the two are well matched, which is conducive to improving the film layer quality of the channel layer, thereby improving the electrical performance of the high electron mobility transistor.

[0018] According to an embodiment of the present application, the high electron mobility transistor further includes a source contact layer and a drain contact layer disposed on the substrate, the resonant element is electrically connected to the source through the source contact layer, and the resonant element is electrically connected to the drain through the drain contact layer.

[0019] According to an embodiment of the present application, the sensitive material electrode, the source and the drain are disposed on the side of the substrate away from the base, that is, the sensitive material electrode, the source and the drain are all disposed above the substrate, so that the sensitive material electrode is in contact with the external environment to detect the environmental parameters.

[0020] According to an embodiment of the present application, the high electron mobility transistor further includes a packaging substrate disposed on the side of the substrate away from the heterojunction, the source contact layer is electrically connected to the resonant element through the packaging substrate, and the source contact layer is electrically connected to the resonant element through the packaging substrate.

[0021] In the second aspect, the present application further provides a preparation method of a sensor system, which includes: forming a shielding layer and a resonant element on a base, the shielding layer is disposed on a first surface, and the resonant element is disposed on a second surface; disposing a high electron mobility transistor on the second surface, the high electron mobility transistor includes a sensitive material electrode, a source and a drain, the sensitive material electrode is located between the source and the drain, and the resonant element is electrically connected to the source and the drain.

[0022] The preparation method provided by the above embodiments of the present application first forms a shielding layer and a resonant element on a base, and then forms a high electron mobility transistor on the base. The source and the drain of the high electron mobility transistor are electrically connected to the resonant element, and the source and the drain of the high electron mobility transistor can be conducted through the two-dimensional electron gas to form the circuit of the resonator.

[0023] The sensitive material electrode, the source and the drain all do not need to receive a voltage signal, the sensitive material electrode is floating, and the sensitive material electrode is not connected to a signal line. The source and the drain are electrically connected to the resonant element, and the source and the drain are floating through the resonant element, that is, the wireless passive sensor can work without an external power supply. Moreover, by using the antenna integrated sensing technology, the reading circuit does not need to be integrated on the wireless passive sensor. Therefore, compared with the active sensor, the wireless passive sensor has higher detection accuracy and stability in harsh environments such as high temperature, high pressure and high electric field or passive scenes, which is conducive to improving the reliability of the sensor system.

[0024] In addition, the resonator adopts a high electron mobility transistor, and the high electron mobility transistor can realize the always-on characteristic by using a two-dimensional electron gas, so that the wireless passive sensor has the advantages of high sensitivity, non-contact measurement, wide test range, high precision, fast response, wide current test frequency, strong anti-interference ability, wide working temperature span, and the like. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the present application, the drawings needed to be used in some embodiments of the present application will be briefly introduced as follows. Obviously, the drawings in the following description are only some drawings of the embodiments of the present application, and other drawings can also be obtained by those skilled in the art according to these drawings. In addition, the drawings in the following description can be regarded as schematic diagrams, and are not actual sizes of the products involved in the embodiments of the present application or actual processes of the methods.

[0026] Figure 1 A structural diagram of the sensor system provided by the embodiments of the present application is shown in FIG. 1.

[0027] Figure 2 Another structural diagram of the sensor system provided by the embodiments of the present application is shown in FIG. 2.

[0028] Figure 3 For Figure 1 A partial cross-sectional view of the wireless passive sensor of the sensor system in the embodiments of the present application along the cross-sectional line A-A' is shown in FIG. 3.

[0029] Figures 4A-4J The diagrams of the steps for preparing the sensor system provided by the embodiments of the present application are shown in FIG. 4. DETAILED DESCRIPTION

[0030] The technical solutions in some embodiments of the present application will be described clearly and completely in the following with reference to the drawings. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments provided by the present application, all other embodiments obtained by those skilled in the art belong to the scope of protection of the present application.

[0031] Unless otherwise required by the context, throughout the specification and claims, the term "comprising" is to be interpreted as open, inclusive, meaning "including, but not limited to".

[0032] Hereinafter, the terms "first" and "second" are only used for description purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first" and "second" can explicitly or implicitly include one or more of the features. In the description of the embodiments of the present application, unless otherwise specified, the meaning of "multiple" is two or more.

[0033] In describing some embodiments, use is made of the term "connected" and its derivatives. The term "connected" is used broadly and essentially means connected directly or indirectly. For example, when used in the context of two or more components being connected together, "connected" can be used to indicate that the two or more components are in direct physical or electrical contact with each other, or that there exists an intervening medium between the two or more components.

[0034] "A, B, or C, at least one of" includes the following combinations of A, B, and C: only A, only B, only C, A and B, A and C, B and C, and A and B and C.

[0035] Additionally, use of "based on" means that the process, step, calculation or other action is based on at least the identified condition or value, but can also be based on additional conditions or values.

[0036] It will be understood that when a layer or element is referred to as being "on" another layer or substrate, it can be directly on the other layer or substrate or intervening layers can also be present.

[0037] Exemplary embodiments are described herein with reference to cross-sectional illustrations that are idealized illustrations. In the drawings, the thickness of layers and regions are exaggerated for illustrative clarity. Accordingly, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and / or tolerances, are to be expected. Thus, the exemplary embodiments should not be construed as limited to the particular shapes of regions as illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, an etched region illustrated as a rectangle will typically have rounded or curved features. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the precise shape of a region of a device and are not intended to limit the scope of the exemplary embodiments.

[0038] Embodiments of the present application provide a sensor system, Figure 1 A structural diagram of a sensor system provided by embodiments of the present application; Figure 2 Another structural diagram of a sensor system provided by embodiments of the present application; Figure 3 For Figure 1 A partial cross-sectional view of a wireless passive sensor of the sensor system along section line A-A'.

[0039] Referring to Figure 1 The sensor system 100 includes a wireless passive sensor 1, an interrogation antenna 2, a response antenna 3, and a reading circuit 4.

[0040] The sensor system 100 adopts an antenna integrated sensing technology, which is a wireless passive parameter acquisition technology integrating an antenna and a wireless passive sensor. Based on the principle of microwave scattering measurement, the sensor system 100 transmits an interrogation signal (a wide-band and high-gain sweep signal) by using the interrogation antenna 2, and the wireless passive sensor 1 can receive the interrogation signal. When the specific frequency of the interrogation signal is consistent with the resonant frequency of the wireless passive sensor 1, the wireless passive sensor 1 resonates to lose the interrogation signal at the specific frequency, and the lost interrogation signal is reflected by the wireless passive sensor 1 in the form of a response signal.

[0041] The reading circuit 4 is electrically connected with the response antenna 3, the response antenna 3 receives the response signal, the reading circuit 4 can acquire the response signal through the response antenna 3, and the reading circuit 4 can read the detection result according to the response signal, for example, reading the peak value of the resonant frequency loss, and obtaining the measured physical quantity according to the corresponding relationship between the pre-measured resonant frequency offset value and the measured physical quantity (for example, an environmental parameter).

[0042] Exemplarily, referring to Figure 1 , the interrogation antenna 2 and the response antenna 3 can be separately arranged, in which case the reading circuit 4 can be electrically connected with the response antenna 3, for example, the reading circuit 4 and the response antenna 3 are integrated on the same circuit board.

[0043] The sensor system 100 can be a temperature sensor, a pressure sensor, a gas sensor, a flow sensor, a vibration sensor, an ultraviolet detector, etc. The sensor system 100 can be applied to harsh environments or passive scenes such as high temperature, high pressure, high electric field, etc. by carrying the wireless passive sensor 1, for example, applied to the detection of temperature, pressure, gas, flow, vibration, ultraviolet, crack, etc. in the fields of military, industry, etc.

[0044] Referring to Figure 2 , the interrogation antenna 2 and the response antenna 3 can also be integrated together, in which case the reading circuit 4 can be electrically connected with the response antenna 3, for example, the interrogation antenna 2, the response antenna 3 and the reading circuit 4 are integrated on the same circuit board, which can simplify the structural design of the antenna.

[0045] Referring to Figure 1 and Figure 3The wireless passive sensor 1 includes a substrate 10 and a shielding layer 11 disposed on the substrate 10. The substrate 10 includes a first surface P1 and a second surface P2 facing each other, and the shielding layer 11 is disposed on the first surface P1 of the substrate 10. The shielding layer 11 can reflect the attenuated interrogation signal (electromagnetic wave) as an response signal (electromagnetic wave) so that the response antenna 3 can receive the response signal and prevent electromagnetic waves from being transmitted out of the wireless passive sensor 1. In addition, the shielding layer 11 can also be used for grounding the device.

[0046] The wireless passive sensor 1 also includes a High Electron Mobility Transistor (HEMT) 12 and a resonator 13, both of which are disposed on the second surface P2 of the substrate 10. The HEMT 12 includes a sensitive material electrode G, a source electrode S, and a drain electrode D, with the sensitive material electrode G located between the source electrode S and the drain electrode D. The resonator 13 is electrically connected to the source electrode S and the drain electrode D of the HEMT 12, forming the circuitry of the resonator.

[0047] For example, see Figure 3 The high electron mobility transistor 12 also includes a substrate 100 and a heterojunction 101 disposed on the substrate 100. For example, the heterojunction 101 includes a channel layer 102 and a barrier layer 103 stacked on the substrate 100, and the sensitive material electrode G, the source electrode S and the drain electrode D are disposed on the side of the heterojunction 101 away from the substrate 100.

[0048] For example, the high electron mobility transistor 12 can be normally open, that is, even when the source S and drain D do not receive an excitation voltage, a two-dimensional electron gas (2DEG) can still be generated in the heterojunction 101. The two-dimensional electron gas forms a conductive channel in the channel layer 102 to realize the conduction between the source S and the drain D, thereby realizing the conduction of the resonator circuit.

[0049] For example, the high electron mobility transistor 12 further includes a source contact layer 104 and a drain contact layer 105 disposed on the substrate 100, wherein the source contact layer 104 is electrically connected to the source (S) and the drain contact layer 105 is electrically connected to the drain (D). The resonator 13 can be electrically connected to the source (S) through the source contact layer 104 and to the drain (D) through the drain contact layer 105.

[0050] Exemplarily, the high electron mobility transistor 12 further comprises a packaging substrate 106, which is arranged on the side of the substrate 100 away from the heterojunction 101, i.e., the packaging substrate 100 is located below the substrate 100. The source contact layer 104 can be electrically connected to the packaging substrate 106 through a bonding wire 108, and the packaging substrate 106 is electrically connected to the resonant piece 13 through a first connecting structure 109 (solder ball), so as to realize the electrical connection between the source contact layer 104 and the resonant piece 13.

[0051] Further, the drain contact layer 105 can be electrically connected to the packaging substrate 106 through a bonding wire 110, and the packaging substrate 106 is electrically connected to the resonant piece 13 through a second connecting structure 111 (solder ball), so as to realize the electrical connection between the drain contact layer 105 and the resonant piece 13, thereby realizing the electrical connection between the resonant piece 13 and the source S and the drain D of the high electron mobility transistor 12, and forming the line of the resonator.

[0052] The sensor system 100 provided by the above-mentioned embodiments of the present application, in the wireless passive sensor 1, the source S and the drain D of the high electron mobility transistor 12 are electrically connected to the resonant piece 13, and the source S and the drain D of the high electron mobility transistor 12 can be conducted through the two-dimensional electron gas to form the line of the resonator.

[0053] The sensitive material electrode G serves as a dummy gate of the high electron mobility transistor 12. When the measured environmental parameter changes, the sensitive material electrode G senses the change of the environmental parameter and changes in potential, and the change in potential of the sensitive material electrode G causes the concentration of the two-dimensional electron gas in the heterojunction 101 to change, thereby changing the resistance value of the conductive channel between the source S and the drain D, and further causing the resonant frequency of the resonator to change.

[0054] Based on this, the change in the resonant frequency of the resonator is collected by using the interrogation antenna 2 and the response antenna 3, and the readout circuit 4 can obtain the measured environmental parameter according to the correspondence between the shift value of the resonant frequency and the measured environmental parameter.

[0055] Among them, the sensitive material electrode G, the source S and the drain D all do not need to receive a voltage signal, the sensitive material electrode G is floating, and the sensitive material electrode G does not connect a signal line. The source S and the drain D are electrically connected to the resonant piece 13, and are floating through the resonant piece 13, so that the source S and the drain D are floating, i.e., the wireless passive sensor 1 can work without external power supply. Further, by using the antenna integrated sensing technology, the readout circuit 4 does not need to be integrated on the wireless passive sensor 1. Therefore, compared with the active sensor, the wireless passive sensor 1 has higher detection accuracy and stability in harsh environments such as high temperature, high pressure and high electric field or passive scenes, and is conducive to improving the reliability of the sensor system 100.

[0056] In addition, compared with a diode, the resonator adopts the high electron mobility transistor 12, and the high electron mobility transistor 12 can realize the always-on characteristic by using the two-dimensional electron gas, so that the wireless passive sensor 1 has the advantages of high sensitivity, non-contact measurement, wide test range, high precision, fast response, wide current test frequency, strong anti-interference ability, wide working temperature span, and the like.

[0057] In some embodiments, referring to Figure 3 , the sensitive material electrode G, the source electrode S, and the drain electrode D are arranged on the side of the substrate 100 away from the base 10, that is, the sensitive material electrode G, the source electrode S, and the drain electrode D are all arranged above the substrate 100, so that the sensitive material electrode G is in contact with the external environment to detect the environmental parameters.

[0058] In some embodiments, referring to Figure 3 , the material of the sensitive material electrode G includes a semiconductor gas-sensitive material, which can be used to detect the composition and concentration of a gas.

[0059] It can be understood that the detection gas can be adsorbed and desorbed on the surface of the semiconductor gas-sensitive material, and in the case that the composition or concentration of the gas in the environment changes, the electrical properties (for example, resistivity or potential) of the semiconductor gas-sensitive material will change, thereby causing the concentration of the two-dimensional electron gas in the heterojunction 101 to change.

[0060] In the embodiments of the present application, the material of the sensitive material electrode G is not limited to the semiconductor gas-sensitive material, and can also include other types of sensitive materials for detecting other types of environmental parameters, such as temperature, pressure, gas, flow, vibration, and the like.

[0061] In some embodiments, referring to Figure 3 , the material of the heterojunction 101 of the high electron mobility transistor 12 can include group ⅢA-group ⅤA elements.

[0062] For example, the material of the heterojunction 101 can include at least one of gallium nitride (chemical formula: GaN), gallium arsenide (chemical formula: GaAs), or indium gallium arsenide (chemical formula: InGaAs), and in the case that the material of the heterojunction 101 includes gallium nitride, the high electron mobility transistor 12 is also called “gallium nitride high electron mobility transistor (abbreviation: GaN HEMT)”.

[0063] For example, in the heterojunction 101, the material of the channel layer 102 includes at least one of gallium nitride, gallium arsenide, or indium gallium arsenide, and the material of the barrier layer 103 can include at least one of indium gallium nitride (chemical formula: InGaN), aluminum gallium nitride (chemical formula: AlGaN), indium phosphide (chemical formula: InP), aluminum gallium arsenide (AlGaAs), or indium aluminum arsenide (InAlAs).

[0064] The material formed by the group IIIA-VIA elements is a wide band gap semiconductor material, and the material characteristics make the high electron mobility transistor 12 have higher electron mobility, saturated electron velocity and breakdown field, and the high electron mobility transistor 12 has better conduction characteristics, which can improve the adjustable ability of the resonant frequency of the wireless passive sensor 1 and improve the sensitivity of the adjustment.

[0065] In some embodiments, referring to Figure 3 The high electron mobility transistor 12 further includes a buffer layer 107, which is arranged between the substrate 100 and the heterojunction 101, and the material of the buffer layer 107 can include aluminum nitride (chemical formula: AlN).

[0066] Generally, the substrate 100 adopts a silicon-based material, for example, a silicon wafer or silicon carbide. In the preparation process, if the channel layer 102 is directly formed on the substrate 100, the channel layer 102 formed by the group IIIA-VIA elements has a large lattice mismatch with the substrate 100, which can cause poor film quality of the channel layer 102, and further cause poor electrical performance of the high electron mobility transistor 12.

[0067] Therefore, the buffer layer 107 is first formed on the substrate 100, and then the channel layer 102 is formed on the buffer layer 107. Since the material of the buffer layer 107 is aluminum nitride and the materials of the channel layer 102 and the buffer layer 107 both include group IIIA-VIA elements, the lattices of the two are well matched, which is beneficial to improve the film quality of the channel layer 102, and thus the electrical performance of the high electron mobility transistor 12 can be improved.

[0068] The embodiments of the present application also provide a preparation method of the sensor system, Figures 4A-4J The preparation method of the sensor system provided by the embodiments of the present application is shown in the following steps.

[0069] Referring to Figure 4A The shielding layer 11 is formed on the first surface P1 of the substrate 10, and the resonant element 13 is formed on the second surface P2 of the substrate 10.

[0070] Exemplarily, the sputtering process can be used to form the shielding layer 11 on the first surface P1 of the substrate 10.

[0071] Exemplarily, the screen printing process can be used to form the resonant element 13 on the second surface P2 of the substrate 10.

[0072] In the embodiments of the present application, the shielding layer 11 can be first formed on the substrate 10, and then the resonant element 13 is formed, or the resonant element 13 can be first formed on the substrate 10, and then the shielding layer 11 is formed.

[0073] Referring to Figure 4BA high electron mobility transistor 12 is arranged on the second surface P2 of the substrate 10, and the resonator 13 is electrically connected to the source S and the drain D of the high electron mobility transistor 12 to form a resonator circuit.

[0074] The high electron mobility transistor 12 is formed by the following steps.

[0075] Referring to Figure 4C , a substrate 100 is provided, a buffer layer 107 is formed on the substrate 100, then a channel layer 102 is formed on the buffer layer 107, and finally a barrier layer 103 is formed on the channel layer 102 to form the buffer layer 107, the channel layer 102 and the barrier layer 103 arranged in layers.

[0076] Referring to Figure 4D , the barrier layer 103 is etched to form a step surface between the barrier layer 103 and the channel layer 102, and the remaining part of the barrier layer 103 and the channel layer 102 form a heterojunction 101 of the high electron mobility transistor 12.

[0077] The barrier layer 103 is etched by an inductively coupled plasma (ICP) etching process.

[0078] Referring to Figure 4E , a metal evaporation and rapid annealing process is used to form the source S and the drain D on the heterojunction 101, and the source S and the drain D form an ohmic contact with the barrier layer 103.

[0079] Then, referring to Figure 4F , a first passivation layer 112 is formed by a plasma enhanced chemical vapor deposition process, and the first passivation layer 112 is etched by an inductively coupled plasma etching process to form two first vias H1 and one second via H2, wherein one first via H1 exposes the source S, the other first via H1 exposes the drain D, and the second via H2 is located between the two first vias H1 and is used to form a sensitive material electrode G subsequently.

[0080] Referring to Figure 4F and Figure 4G , a source contact layer 104 and a drain contact layer 105 are formed, the source contact layer 104 is electrically connected to the source S, and the drain contact layer 105 is electrically connected to the drain D.

[0081] Referring to Figure 4H , a second passivation layer 113 is formed by a plasma enhanced chemical vapor deposition process, and the second passivation layer 113 is etched by an inductively coupled plasma etching process to form a third via H3, the third via H3 partially overlaps the second via H2 of the first passivation layer 112 to expose at least part of the second via H2.

[0082] See Figure 4I A sensitive material electrode G is formed within the third via H3.

[0083] See Figure 4J ,Will Figure 4I The structure is disposed on the packaging substrate 106. The source contact layer 104 can be electrically connected to the packaging substrate 106 through the bonding wire 108, and the drain contact layer 105 can be electrically connected to the packaging substrate 106 through the bonding wire 110.

[0084] Based on this, during the process of setting the high electron mobility transistor 12 on the second surface P2 of the substrate 10, the packaging substrate 106 is electrically connected to the resonator 13 through the first connection structure 109, thereby realizing the electrical connection between the source contact layer 104 and the resonator 13. Furthermore, the packaging substrate 106 is electrically connected to the resonator 13 through the second connection structure 111, thereby realizing the electrical connection between the drain contact layer 105 and the resonator 13.

[0085] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A sensor system, characterized in that, The sensor system includes a wireless passive sensor, an interrogation antenna, an answering antenna, and a readout circuit; The wireless passive sensor includes: The substrate includes opposing first and second surfaces; A shielding layer is disposed on the first surface; A high electron mobility transistor is disposed on the second surface; the high electron mobility transistor includes a sensitive material electrode, a source electrode and a drain electrode, the sensitive material electrode is located between the source electrode and the drain electrode, and the sensitive material electrode is floating; A resonant element is disposed on the second surface, the resonant element is electrically connected to the source and the drain, and the resonant element is floating; The interrogation antenna is used to transmit an interrogation signal, the wireless passive sensor is used to receive the interrogation signal and reflect a response signal, and the response antenna is used to receive the response signal. The reading circuit is electrically connected to the response antenna, and the reading circuit is used to read the detection result based on the response signal.

2. The sensor system according to claim 1, characterized in that, The high electron mobility transistor is a normally open high electron mobility transistor.

3. The sensor system according to claim 1, characterized in that, The material of the sensitive material electrode includes a semiconductor gas-sensitive material.

4. The sensor system according to claim 1, characterized in that, The high electron mobility transistor further includes a substrate and a heterojunction disposed on the substrate, wherein the sensitive material electrode, the source electrode and the drain electrode are disposed on the side of the heterojunction away from the substrate; The material of the heterojunction includes elements from groups IIIA to VA.

5. The sensor system according to claim 4, characterized in that, The heterojunction includes a channel layer and a barrier layer stacked on the substrate; The channel layer is made of at least one of gallium nitride, gallium arsenide, or indium gallium arsenide, and the barrier layer is made of at least one of indium gallium nitride, aluminum gallium nitride, indium phosphide, aluminum gallium arsenide, or indium aluminum arsenide.

6. The sensor system according to claim 4, characterized in that, The high electron mobility transistor further includes a buffer layer disposed between the substrate and the heterojunction; The material of the buffer layer includes aluminum nitride.

7. The sensor system according to claim 4, characterized in that, The high electron mobility transistor further includes a source contact layer and a drain contact layer disposed on the substrate; The resonator is electrically connected to the source electrode through the source contact layer, and the resonator is electrically connected to the drain electrode through the drain contact layer.

8. The sensor system according to claim 7, characterized in that, The sensitive material electrode, the source electrode, and the drain electrode are disposed on the side of the substrate away from the substrate.

9. The sensor system according to claim 8, characterized in that, The high electron mobility transistor further includes a packaging substrate disposed on the side of the substrate away from the heterojunction; The source contact layer is electrically connected to the resonator through the packaging substrate.

10. A method for fabricating a sensor system, characterized in that, The sensor system includes a wireless passive sensor, an interrogation antenna, an answering antenna, and a readout circuit; The preparation method includes: A shielding layer and a resonator are formed on a substrate, the substrate including a first surface and a second surface opposite to each other, the shielding layer being disposed on the first surface and the resonator being disposed on the second surface; A high electron mobility transistor is disposed on the second surface. The high electron mobility transistor includes a sensitive material electrode, a source electrode, and a drain electrode. The sensitive material electrode is located between the source electrode and the drain electrode. The resonator is electrically connected to the source electrode and the drain electrode.

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