Electronic device and method for manufacturing sensor in the electronic device

Abstract

The present application provides an electronic device comprising: a plurality of sensor pixels, each of the sensor pixels comprising: an acoustic wave sensor; a demultiplexer electrically connected to the acoustic wave sensor; a drive line electrically connected to the acoustic wave sensor; a switch line electrically connected to the demultiplexer; and a readout line electrically connected to the demultiplexer. The drive line is used to transmit a drive signal to the acoustic wave sensor to emit an acoustic wave, and the switch line is used to activate the demultiplexer to output a sensing signal received by the acoustic wave sensor to the readout line.

Description

Technical Field

[0001] The present application relates to an electronic device, and more particularly to an acoustic wave sensor and a manufacturing method thereof. Background Art

[0002] The core components of acoustic wave sensing systems, such as micromachined ultrasonic transducers (MUTs), are currently a focus of active global development. Currently, MUTs are primarily passive matrix devices fabricated on wafers, making them incapable of achieving three-dimensional array imaging. Furthermore, integration of the MUT with external circuitry requires wafer bonding, which is costly and difficult to manufacture on a large scale. Therefore, the industry is eager to find ways to reduce costs and / or achieve large-scale fabrication. Summary of the Invention

[0003] According to one embodiment of the present application, an electronic device is provided, including: a plurality of sensor pixels, each of the sensor pixels including: an acoustic wave sensor; a demultiplexer electrically connected to the acoustic wave sensor; a drive line electrically connected to the acoustic wave sensor; a switch line electrically connected to the demultiplexer; and a readout line electrically connected to the demultiplexer, wherein the drive line is used to transmit a drive signal to the acoustic wave sensor to emit an acoustic wave, and the switch line is used to activate the demultiplexer to output a sensing signal received by the acoustic wave sensor to the readout line.

[0004] According to one embodiment of the present application, a method for manufacturing an acoustic wave sensor is provided, comprising: providing a substrate; forming a drive layer on the substrate; forming a sacrificial layer on the drive layer; forming a piezoelectric layer on the sacrificial layer; and etching the sacrificial layer, wherein the step of etching the sacrificial layer is performed before forming the piezoelectric layer.

[0005] According to one embodiment of the present application, a method for manufacturing an acoustic wave sensor is provided, comprising: providing a substrate; forming a driving layer on the substrate; forming a lower electrode on the driving layer; forming a sacrificial layer on the lower electrode; forming an upper electrode on the sacrificial layer; and removing the sacrificial layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] In order to make the above-mentioned objects, features and advantages of the present invention more clearly understood, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings, in which:

[0007] Figure 1 According to an embodiment of the present application, a circuit diagram of an electronic device;

[0008] Figure 2-1 According to an embodiment of the present application, a circuit diagram in an electronic device;

[0009] Figure 2-2 According to an embodiment of the present application, a circuit diagram in an electronic device;

[0010] Figure 3-1 According to one embodiment of the present application, a top view of an acoustic wave sensor;

[0011] Figure 3-2 According to one embodiment of the present application, Figure 3-1 Schematic cross-sectional view of the A-A' and B-B' sections;

[0012] Figure 3-3 According to one embodiment of the present application, a cross-sectional schematic diagram of a method for manufacturing an acoustic wave sensor;

[0013] Figure 4-1 According to one embodiment of the present application, a top view of an acoustic wave sensor;

[0014] Figure 4-2 According to one embodiment of the present application, Figure 4-1 Schematic cross-sectional view of the A-A' and B-B' sections;

[0015] Figure 4-3 According to one embodiment of the present application, a cross-sectional schematic diagram of a method for manufacturing an acoustic wave sensor; and

[0016] Figure 4-3-2 According to an embodiment of the present application, a cross-sectional schematic diagram of a method for manufacturing an acoustic wave sensor is provided.

[0017] Description of component numbers in the figure:

[0018] 10: Electronic devices

[0019] 10a: Sensing area

[0020] 10b: Non-sensing area

[0021] 12: Sensor pixels

[0022] 14: Drive Line

[0023] 16: Switch Line

[0024] 16a, 16b: Branch lines

[0025] 18: Read line

[0026] 20: Acoustic wave sensor circuit unit

[0027] 22, 30: Reference signal

[0028] 24: Demultiplexer

[0029] 26a, 26b, 26c, 26d: driving circuit

[0030] 28: Drive signal

[0031] 32: Acoustic sensor

[0032] 34: Demultiplexer

[0033] 36a, 36b: Demultiplexer transistors

[0034] 38a, 38b: Gates of the demultiplexer transistors

[0035] 40a, 40b: Demultiplexer transistors

[0036] 42a, 42b: Sources of the demultiplexer transistors

[0037] 44, 92: Upper electrode

[0038] 46, 88: Lower electrode

[0039] 50: Substrate

[0040] 51: Driver layer

[0041] 52, 54: Insulation layer

[0042] 56: Semiconductor layer

[0043] 58: Channel Area

[0044] 60, 66, 68: Insulation layer

[0045] 64, 72: conductive layer

[0046] 70, 76, 82, 84: through holes

[0047] 74: Insulation layer

[0048] 78, 89: conductive layer

[0049] 80: Insulation layer

[0050] 86: Cavity

[0051] 90: Piezoelectric layer

[0052] 94: Sacrificial layer

[0053] 96: Amorphous silicon layer

[0054] 98: Nickel layer

[0055] 100: Nickel silicide layer DETAILED DESCRIPTION

[0056] The following application content provides many different embodiments or examples to implement the different features of this case. The following application content describes specific examples of each component and its arrangement to simplify the description. Of course, these specific examples are not intended to be limiting. For example, if the embodiment of the present application describes a first characteristic component formed on or above a second characteristic component, it means that it may include an embodiment in which the above-mentioned first characteristic component and the above-mentioned second characteristic component are in direct contact, and may also include an embodiment in which an additional characteristic component is formed between the above-mentioned first characteristic component and the above-mentioned second characteristic component, so that the above-mentioned first characteristic component and the second characteristic component may not be in direct contact.

[0057] In addition, when the terms "including" and / or "having" are used in this specification, they specify the presence of the features, regions, steps, operations and / or elements, but do not exclude the presence or addition of one or more other features, regions, steps, operations, elements and / or combinations thereof. When an element such as a layer or region is referred to as being "on" or extending "on" another element (or variations thereof), it can be directly on or directly extended to the other element, or there can be intervening elements between the two.

[0058] It should be understood that additional operating steps may be implemented before, during, or after the method, and in other embodiments of the method, some operating steps may be replaced or omitted.

[0059] Additionally, spatially relative terms such as "below," "beneath," "lower," "above," "above," "upper," and the like may be used to describe the relationship of one element or feature to another element or feature in the drawings. These spatially relative terms encompass different orientations of the device in use or operation, as well as the orientations depicted in the drawings. When the device is rotated 45 degrees or at other orientations, the spatially relative adjectives used herein will be interpreted based on that orientation.

[0060] The electrical connection can be achieved directly or indirectly through other components.

[0061] It should be understood that although the terms "first," "second," "third," etc. are used herein to describe different elements, components, regions, layers, and / or sections, these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms may only be used to distinguish one element, component, region, layer, or section from another element, component, region, layer, or section. Thus, a first element, component, region, layer, or section discussed below may be referred to as a second element, component, region, layer, or section without departing from the technology of the present application.

[0062] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meanings as commonly understood by those skilled in the art. It is understood that these terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning consistent with the background or context of the relevant technology and this application, and should not be interpreted in an idealized or overly formal manner unless specifically defined in the examples of this application.

[0063] See also Figure 1 According to an embodiment of the present application, the circuit connection relationship between the components in the electronic device 10 is described. Here, a 3×3 matrix is used as an example for description, but the present application is not limited thereto.

[0064] like Figure 1 As shown, the electronic device 10 includes a sensing area 10a and a non-sensing area 10b, which are arranged adjacent to each other. The sensing area 10a includes a plurality of sensor pixels 12, a plurality of drive lines 14, a plurality of switching lines (16a, 16b), and a plurality of readout lines 18. In this embodiment, each sensor pixel 12 includes an acoustic wave sensor circuit unit 20, a drive line 14, a switching line (16a, 16b), and a readout line 18. For the detailed structure of the acoustic wave sensor circuit unit 20 and its circuit connection relationship, please refer to Figure 2-1 and Figure 2-2 . The non-sensing area 10b may have multiple driving circuits (26a, 26b, 26c, 26d), wherein the driving circuit 26a is electrically connected to the demultiplexer 24 to turn on the demultiplexer 24. Each demultiplexer 24 is electrically connected to the driving line 14, and receives a driving signal 28 and a reference signal 30. In this embodiment, the switching lines (16a, 16b) are electrically connected to the driving circuits (26c, 26d), respectively. In other embodiments, the switching lines (16a, 16b) may be electrically connected to the same driving circuit, but are not limited thereto. For the detailed structure of the demultiplexer 24 and its circuit connection relationship, please refer to Figure 2-1 and Figure 2-2 In this embodiment, the plurality of sensor pixels 12 may respectively correspond to pixel units (not shown) of the electronic device; in other embodiments, the plurality of pixel units may also correspond to and share one sensor pixel 12, without limitation thereto.

[0065] In the present application, sound waves may include infrasound waves (eg, with a frequency less than 20 Hz), acoustic waves (eg, with a frequency between 20 Hz and 20 kHz), and ultrasonic waves (eg, with a frequency higher than 20 kHz).

[0066] The electronic device may have a display function, wherein the electronic display device of the embodiment of the present application may include a display device, an antenna device, a sensing device, a splicing device or a transparent display device, but is not limited thereto. The electronic device may be a rollable, stretchable, bendable or flexible electronic device. The electronic device may, for example, include liquid crystal, light emitting diode (LED), quantum dot (QD), fluorescence, phosphorescence or other suitable materials and their materials may be arranged and combined in any manner or other suitable display media, or a combination of the foregoing; the light emitting diode may, for example, include an organic light emitting diode (OLED), a millimeter / sub-millimeter light emitting diode (mini LED), a micro light emitting diode (micro LED) or a quantum dot light emitting diode (QD, which may be, for example, QLED, QDLED), but is not limited thereto. The antenna device may, for example, be a liquid crystal antenna, but is not limited thereto. The splicing device may, for example, be a display splicing device or an antenna splicing device, but is not limited thereto. It should be noted that the electronic device may be any of the aforementioned arrangements and combinations, but is not limited thereto. Furthermore, the electronic device may have a rectangular, circular, polygonal shape, a shape with curved edges, or other suitable shapes. The electronic device may include peripheral systems such as a drive system, a control system, a light source system, a shelving system, etc. to support the display device, antenna device, or splicing device. The following description of this application will be based on an electronic display device with display functionality, but this application is not limited thereto.

[0067] See also Figure 2-1 and Figure 2-2 According to an embodiment of the present application, the circuit connection relationship between the components in a single sensor pixel 12 and how to transmit and receive signals are further described.

[0068] like Figure 2-1 As shown, in the sensing area 10a, the acoustic wave sensor circuit unit 20 includes an acoustic wave sensor 32 and a demultiplexer 34. In this embodiment, the demultiplexer 34 and the driving line 14 are electrically connected to the acoustic wave sensor 32, and the switching line (16a, 16b) and the reading line 18 are electrically connected to the demultiplexer 34. The acoustic wave sensor 32 may include a piezoelectric acoustic wave sensor (piezoelectric micromachined ultrasonic transducer, PMUT) or a capacitive acoustic wave sensor (capacitive micromachined ultrasonic transducer, CMUT), but is not limited thereto. Figure 2-1In the embodiment, the demultiplexer 34 is electrically connected to the acoustic wave sensor 32. The driving line 14 is electrically connected to the acoustic wave sensor 32, and the driving signal 28 is transmitted to the acoustic wave sensor 32 via the driving line 14, so that the acoustic wave sensor 32 emits an acoustic wave. The reading line 18 is electrically connected to the demultiplexer 34. The switching lines (16a, 16b) are electrically connected to the demultiplexer 34 to turn on the demultiplexer 34. In this embodiment, when the electronic device 10 performs different actions, such as transmitting a signal or receiving a signal, the switching lines (16a, 16b) can transmit different signals to enable the demultiplexer 34 to perform different actions, such as Figure 2-1 In the process, the demultiplexer 34 is turned on to transmit the reference signal 22 to the acoustic wave sensor 32, or Figure 2-2 In the embodiment, the demultiplexer 34 is turned on and the sensing signal received by the acoustic wave sensor 32 is output to the read line 18. The demultiplexer 34 may include at least two transistors (36a, 36b), but the present application is not limited thereto. In the present embodiment, the demultiplexer 34 includes two transistors (36a, 36b), and the switching line includes two branches (16a, 16b) electrically connected to the gates (38a, 38b) of the two transistors (36a, 36b) of the demultiplexer 34, respectively. The non-sensing area 10b includes the demultiplexer 24. The demultiplexer 24 includes at least two transistors (40a, 40b), but the present application is not limited thereto. In the present embodiment, the demultiplexer 24 includes two transistors (40a, 40b), and the sources (42a, 42b) of the transistors (40a, 40b) of the demultiplexer 24 receive the drive signal 28 and the reference signal 30, respectively. In this application, the source and the drain can be interchanged, but are not limited thereto.

[0069] according to Figure 2-1 , explaining how the electronic device 10 of the present application transmits a signal. When performing signal transmission, the driving circuit 26a first turns on the transistor 40a of the demultiplexer 24, and transmits the driving signal 28 to the upper electrode 44 of the acoustic wave sensor 32 via the driving line 14. At this time, the potential of the driving signal 28 is equal to the potential of the upper electrode 44, and the driving signal 28 is an alternating current (AC) signal. At the same time, the driving circuit 26c turns on the transistor 36a of the demultiplexer 34 via the switching line 16a, and transmits the reference signal 22 to the lower electrode 46 of the acoustic wave sensor 32. At this time, the potential of the reference signal 22 is equal to the potential of the lower electrode 46, and the reference signal 22 is a direct current (DC) signal. Due to the AC driving potential of the upper electrode 44 and the DC reference potential of the lower electrode 46, the acoustic wave sensing unit 20 sends a signal (e.g., an acoustic wave) to the object to be measured.

[0070] according to Figure 2-2, illustrating how the electronic device 10 of the present application receives signals. When receiving a signal, the transistor 40b of the demultiplexer 24 in the driving circuit 26b is first turned on, and the reference signal 30 is transmitted to the upper electrode 44 of the acoustic wave sensor 32 via the driving line 14. At this time, the potential of the reference signal 30 is equal to the potential of the upper electrode 44, and the reference signal 30 is a direct current (DC) signal, which maintains the upper electrode 44 at a fixed voltage. Simultaneously, the driving circuit 26d transmits the reference signal 22 via the switching line 16b to turn on the transistor 36b of the demultiplexer 34. At this time, the acoustic wave sensor 32 has converted the acoustic wave signal reflected back from the object under test into a corresponding electrical signal 29. The electrical signal 29 is output to the read line 18 for reading via the lower electrode 46 and the transistor 36b of the demultiplexer 34, allowing the electronic device 10 to receive the signal (e.g., the returned acoustic wave).

[0071] according to Figure 2-1 and Figure 2-2 The acoustic wave sensor unit 20 can transmit and receive signals to detect, for example, the distance or surface shape of the object to be detected.

[0072] according to Figure 1 Different modes may be used for signal transmission and reception. For example, the acoustic wave sensor circuit units 20 of the same sensor pixels or the same column of sensor pixels may be selected to simultaneously perform signal transmission and reception. Alternatively, the acoustic wave sensor circuit units 20 of sensor pixels in different columns may be selected to perform signal transmission and reception respectively. For example, the acoustic wave sensor circuit units 20 of the sensor pixels in the first column may be selected to perform signal transmission, and the acoustic wave sensor circuit units 20 of the sensor pixels in the second column may be selected to perform signal reception. However, the present application is not limited thereto, and any mode of selecting each sensor pixel to be matched with signal transmission and reception is applicable to the present application.

[0073] In addition, the driving circuit can also be used to adjust the actuation of signal transmission and reception, for example, using or not using a beam-forming mode. When the beam-forming mode is not used, all sensor pixels emit sound waves synchronously, enabling large-scale, comprehensive detection. If it is desired to detect an object to be detected at a specific position and distance, a beam-forming mode (i.e., signal transmission with a phase difference) can be used. For example, in the beam-forming mode, the driving circuit can be controlled to emit driving signals at different timings, so that, for example, each sensor pixel in the same row emits sound waves at different timings. The phase difference signal generated by the time difference produces a constructive interference superposition effect on the sound waves emitted by the object to be detected at a specific position and distance, effectively improving the signal strength.

[0074] See also Figure 3-1 and Figure 3-2According to an embodiment of the present application, the detailed structure of the acoustic wave sensor circuit unit 20 is further described. Here, a piezoelectric acoustic wave sensor (PMUT) is used as an example for description. Figure 3-1 FIG. 2 is a top view of the acoustic wave sensor circuit unit 20 . Figure 3-2 For the Figure 3-1 Schematic cross-sectional view of the AA' and BB' sections.

[0075] The acoustic wave sensor circuit unit 20 is mainly composed of an acoustic wave sensor 32 and a demultiplexer 34 (see Figure 2-1 ).like Figure 3-1 and Figure 3-2 As shown, the acoustic wave sensor circuit unit 20 includes a substrate 50, an insulating layer 52, an insulating layer 54, a semiconductor layer 56, an insulating layer 60, a conductive layer 64, an insulating layer 66, an insulating layer 68, a conductive layer 72, an insulating layer 74, a conductive layer 78, an insulating layer 80, a cavity 86, a lower electrode 88, a piezoelectric layer 90, and an upper electrode 92. In this embodiment, the substrate 50 may have a supporting function. The insulating layer 52 is formed on the substrate 50. The insulating layer 54 is formed on the insulating layer 52. The semiconductor layer 56 is formed on the insulating layer 54 and includes a channel region 58 corresponding to the conductive layer 64. In this embodiment, the insulating layers (52, 54) are located between the substrate 50 and the semiconductor layer 56 and may have a buffering function. The insulating layer 60 is formed on the insulating layer 54 and covers the semiconductor layer 56. The conductive layer 64 is formed on the insulating layer 60. The insulating layer 60 is located between the semiconductor layer 56 and the conductive layer 64 and may serve as a gate insulating layer, for example. An insulating layer 66 is formed on the insulating layer 60 and covers the conductive layer 64. An insulating layer 68 is formed on the insulating layer 66. A through hole 70 passes through the insulating layers (60, 66, 68) to expose the semiconductor layer 56. In this embodiment, the through hole 70 passes through the insulating layers (60, 66, 68), indicating that the insulating layers (60, 66, 68) have a through hole 70. Other related embodiments are applicable and will not be described in detail. In some embodiments, the insulating layers (66, 68) can be optionally provided. A conductive layer 72 is formed on the insulating layer 68, fills the through hole 70, and contacts the semiconductor layer 56. An insulating layer 74 is formed on the insulating layer 68, covers the conductive layer 72, and fills the through hole 70. In this embodiment, the insulating layer 74 has a flattening function, allowing subsequent process components to be provided on a relatively flat surface. A through hole 76 passes through the insulating layer 74 to expose the conductive layer 72. Conductive layer 78 is formed on insulating layer 74, fills through hole 76, and contacts conductive layer 72. The above forms the active transistor structure in demultiplexer 34. The above transistor structure is any transistor in demultiplexer 34, such as transistor 36a or transistor 36b (e.g. Figure 2-1 shown).

[0076] Insulating layer 80 is formed on insulating layer 74, covering conductive layer 78 and filling through hole 76. Through hole 82 passes through insulating layer 80, exposing insulating layer 74. Through hole 84 passes through insulating layer 80, exposing conductive layer 78. Cavity 86 is formed in insulating layer 80, located between insulating layer 74 and insulating layer 80. For the formation of cavity 86, please refer to the subsequent Figure 3-3 The lower electrode 88 is formed on the insulating layer 80, fills the through hole 84, and contacts the conductive layer 78. The piezoelectric layer 90 is formed on the insulating layer 80, covers the lower electrode 88, and fills the through hole 84. The upper electrode 92 is formed on the piezoelectric layer 90. The above forms the piezoelectric acoustic wave sensor (PMUT) 32 (such as Figure 2-1 shown).

[0077] In this embodiment, the thickness of the piezoelectric layer 90 may be 1 to 1.5 μm, for example, 1.2 μm; the height of the cavity 86 may be 0.3 to 1 μm, for example, 0.5 μm; the thickness of the insulating layer 80 may be 1.5 to 3 μm, for example, 2 μm; the thickness of the upper electrode 92 may be For example The thickness of the insulating layer 74 can be 2-3 μm, for example, 2.9 μm; the thickness of the insulating layer 66 and the insulating layer 68 can be respectively For example and The thickness of the insulating layer 60 can be For example and The thickness of the insulating layer 52 and the insulating layer 54 can be between For example and But it is not limited to this.

[0078] In some embodiments, the piezoelectric layer 90 may include aluminum nitride, zinc oxide, or ceramic material, or other appropriate materials or combinations thereof, but is not limited thereto.

[0079] In some embodiments, the insulating layer 80 may be a single layer or multiple layers.

[0080] The material of the insulating layer may include, but is not limited to, inorganic materials such as silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide, or hafnium oxide. It may also include, but is not limited to, acrylic resin, or other suitable materials or combinations thereof. The insulating layer may be a single-layer structure or a multi-layer structure, but this does not limit the scope of this application. In some embodiments, the insulating layer (52, 54, 60, 66, 68) may include silicon oxide, silicon nitride, or silicon oxynitride.

[0081] The substrate 50 can be a rigid substrate or a flexible substrate. The substrate 50 can include a single-layer material structure or a multi-layer material structure. The substrate 50 can be made of polyimide (PI), polyethylene terephthalate (PET), polycarbonate (PC), polyethersulfone (PES), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polyarylate (PAR), or other suitable materials or combinations thereof, but is not limited thereto.

[0082] The material of semiconductor layer 56 may include, but is not limited to, amorphous silicon, polycrystalline silicon, germanium, a compound semiconductor (e.g., gallium nitride, silicon carbide, gallium arsenide, gallium phosphide, indium phosphide, indium arsenide, and / or indium antimonide), an alloy semiconductor (e.g., SiGe alloy, GaAsP alloy, AlInAs alloy, AlGaAs alloy, GaInAs alloy, GaInP alloy, GaInAsP alloy), or a combination thereof. The material of semiconductor layer 56 may also include, but is not limited to, a metal oxide such as indium gallium zinc oxide (IGZO), indium zinc oxide (IZO), indium gallium zinc oxide (IGZTO), an organic semiconductor including a polycyclic aromatic compound, or a combination thereof. In some embodiments, semiconductor layer 56 may be doped with a p-type or n-type dopant.

[0083] In some embodiments, the bottom electrode 88 may include a conductive layer of a non-transparent material. In some embodiments, the top electrode 92 may include a conductive layer of a non-transparent material, and the material selected may be adjusted based on the conductivity and adhesion to the piezoelectric layer 90 .

[0084] The material of the conductive layer (64, 72, 78) may include, but is not limited to, an opaque conductive material, such as a single layer or multilayer composite structure composed of a metal, metal oxide, or other suitable conductive material. For example, it may include at least one of aluminum, copper, silver, chromium, titanium, and molybdenum, a composite layer of the above materials, or an alloy of the above materials. It may include, but is not limited to, a transparent conductive material, such as a transparent conductive oxide (TCO), indium tin oxide (ITO), or indium zinc oxide (IZO). It may include, but is not limited to, a semi-transparent metal film material, such as a magnesium-silver alloy film, a gold film, a platinum film, or an aluminum film, or other suitable materials or a combination of the above materials, but is not limited thereto.

[0085] The material compositions of the aforementioned components are applicable to the relevant components of this application and will not be described in detail hereafter.

[0086] See also Figure 3-2, explaining the operation of the piezoelectric acoustic wave sensor (PMUT). The piezoelectric acoustic wave sensor (PMUT) mainly transmits and receives signals by virtue of the piezoelectric properties of the piezoelectric layer. When the driving signal AC is transmitted to the upper electrode 92 of the acoustic wave sensor, a reference signal DC is also transmitted to the lower electrode 88 of the acoustic wave sensor. At this time, a vertical electric field is formed between the upper electrode 92 and the lower electrode 88. As the AC signal switches between positive and negative voltages, the direction of the electric field continues to change, and the piezoelectric layer 90 deforms due to the piezoelectric properties of the material itself, releasing mechanical force. At this time, the insulating layer 80 vibrates due to the mechanical force, thereby emitting an acoustic wave signal to the object under test.

[0087] See also Figure 3-3 According to one embodiment of the present application, a method for manufacturing an acoustic wave sensor circuit unit is provided. Here, a piezoelectric acoustic wave sensor (PMUT) is used as an example for illustration. Figure 3-3 A cross-sectional schematic diagram of a method for manufacturing an acoustic wave sensor circuit unit.

[0088] First, a substrate 50 is provided, and a driving layer 51 is formed on the substrate. The driving layer 51 includes a stack of insulating layers 52 to conductive layers 78. Next, a sacrificial layer 94 is formed on the driving layer 51. In this embodiment, the sacrificial layer 94 is formed on the insulating layer 74. Next, an insulating layer 80 is formed on the insulating layer 74, covering the conductive layer 78 and the sacrificial layer 94, and filling the through hole 76. Next, the insulating layer 80 is etched to form a through hole 82 corresponding to the sacrificial layer 94 and a through hole 84 corresponding to the conductive layer 78. The through hole 82 passes through the insulating layer 80, exposing the sacrificial layer 94. The through hole 84 passes through the insulating layer 80, exposing the conductive layer 78. Next, a lower electrode 88 is formed on the insulating layer 80, filling the through hole 84, and contacting the conductive layer 78. Next, the sacrificial layer 94 is removed to form a cavity 86. In some embodiments, the sacrificial layer 94 can be removed by an etching process. For example, an etching solution is provided to the through-hole 82 to etch away the sacrificial layer 94. In some embodiments, the sacrificial layer 94 can also be removed by introducing an etching gas, but is not limited thereto. Next, a piezoelectric layer 90 is formed on the insulating layer 80, covering the lower electrode 88 and filling the through-holes (82, 84). In some embodiments, the piezoelectric layer 90 can be formed on the insulating layer 80 by a sputtering process. Next, an upper electrode 92 is formed on the piezoelectric layer 90, so that the piezoelectric layer 90 is located between the upper electrode 92 and the lower electrode 80. At this point, the fabrication of the acoustic wave sensor circuit unit 20 is completed.

[0089] In the embodiment of the present application, the driving layer 51 is completed before the cavity 86 is formed. More specifically, the driving layer 51 includes the stacked layers before the sacrificial layer 94 is formed.

[0090] See also Figure 4-1 and Figure 4-2According to an embodiment of the present application, the detailed structure of the acoustic wave sensor circuit unit 20 is further described. Here, a capacitive acoustic wave sensor (CMUT) is taken as an example for description. Figure 4-1 FIG. 2 is a top view of the acoustic wave sensor circuit unit 20 . Figure 4-2 For the Figure 4-1 Schematic cross-sectional view of the AA' and BB' sections.

[0091] The acoustic wave sensor circuit unit 20 is mainly composed of an acoustic wave sensor 32 and a demultiplexer 34 (see Figure 2-1 ).like Figure 4-1 and Figure 4-2 As shown, the acoustic wave sensor circuit unit 20 includes a substrate 50, an insulating layer 52, an insulating layer 54, a semiconductor layer 56, a channel region 58, an insulating layer 60, a conductive layer 64, an insulating layer 66, an insulating layer 68, a through-hole 70, a conductive layer 72, an insulating layer 74, a through-hole 76, a lower electrode 88, an insulating layer 80, a through-hole 82, a cavity 86, and an upper electrode 92. In this embodiment, the substrate 50 may have a supporting function. The insulating layer 52 is formed on the substrate 50. The insulating layer 54 is formed on the insulating layer 52. In this embodiment, the insulating layers (52, 54) are located between the substrate 50 and the semiconductor layer 56 and may have a buffering function. The semiconductor layer 56 is formed on the insulating layer 54 and includes the channel region 58. The insulating layer 60 is formed on the insulating layer 54 and covers the semiconductor layer 56. The insulating layer 60 is located between the semiconductor layers 56 and may serve as a gate insulating layer, for example. The conductive layer 64 is formed on the insulating layer 60. An insulating layer 66 is formed on the insulating layer 60 and covers the conductive layer 64. An insulating layer 68 is formed on the insulating layer 66. A through hole 70 passes through the insulating layers (60, 66, 68) to expose the semiconductor layer 56. A conductive layer 72 is formed on the insulating layer 68, fills the through hole 70, and contacts the semiconductor layer 56. An insulating layer 74 is formed on the insulating layer 68, covers the conductive layer 72, and fills the through hole 70. The insulating layer 74 has a flat function, which allows the components of the subsequent process to be set on a relatively flat surface. The through hole 76 passes through the insulating layer 74 to expose the conductive layer 72. The lower electrode 88 is formed on the insulating layer 74, fills the through hole 76, and contacts the conductive layer 72. In some embodiments, the lower electrode 88 may include a conductive layer of a non-transparent material. The above forms the transistor structure in the demultiplexer 34. The above transistor structure is any one of the transistors in the demultiplexer 34, such as the transistor 36a or the transistor 36b (such as Figure 2-1 shown).

[0092] An insulating layer 80 is formed on the lower electrode 88 and fills the through hole 76. A through hole 82 passes through the insulating layer 80, exposing the lower electrode 88. An upper electrode 92 is formed on the insulating layer 80. A cavity 86 is formed in the insulating layer 80, located between the lower electrode 88 and the upper electrode 92. The above forms a capacitive acoustic wave sensor (CMUT) 32 (such as Figure 2-1 In the embodiments of this application, a piezoelectric acoustic wave sensor (PMUT) can transmit and receive signals by utilizing the piezoelectric properties of the piezoelectric layer. As the electric field continuously changes, the piezoelectric layer deforms due to the piezoelectric properties of the material itself, releasing a mechanical force that causes the insulating layer to vibrate under the action of the mechanical force, thereby emitting an acoustic wave signal to the object under test. A capacitive acoustic wave sensor (CMUT) can transmit and receive signals by utilizing the principle of attraction between positive and negative charges between upper and lower electrodes. As the upper and lower electrodes undergo displacement changes due to electrostatic attraction, the insulating layer vibrates under the force, thereby emitting an acoustic wave signal to the object under test.

[0093] See also Figure 4-2 , explaining the operation of a capacitive acoustic wave sensor (CMUT). A capacitive acoustic wave sensor (CMUT) primarily transmits and receives signals based on the principle of attraction between positive and negative charges between upper and lower electrodes. When a drive signal AC is transmitted to the upper electrode 92 of the acoustic wave sensor, a reference signal DC is simultaneously transmitted to the lower electrode 88 of the acoustic wave sensor. As the AC signal switches between positive and negative voltages, the upper electrode moves toward the lower electrode due to the electrostatic attraction between the upper electrode and the lower electrode. As the upper electrode's displacement changes, the insulating layer 80 vibrates due to the force, thereby emitting an acoustic wave signal to the object under test.

[0094] See also Figure 4-3 According to one embodiment of the present application, a method for manufacturing an acoustic wave sensor circuit unit is provided. Here, a capacitive acoustic wave sensor (CMUT) is used as an example for illustration. Figure 4-3 A cross-sectional schematic diagram of a method for manufacturing an acoustic wave sensor circuit unit.

[0095] First, a substrate 50 is provided, and a driving layer 51 is formed on the substrate. The driving layer 51 includes a stack of layers from an insulating layer 52 to a lower electrode 88 and a conductive layer 8. Next, a sacrificial layer 94 is formed on the driving layer 51. In this embodiment, the sacrificial layer 94 is formed on the lower electrode 88. Next, an insulating layer 80 is formed on the insulating layer 74, covering the lower electrode 88, the sacrificial layer 94, and the conductive layer 89, and filling the through hole 76. In this embodiment, the lower electrode 88 and the conductive layer 89 can be formed in a single process, or they can be formed separately, without limitation. Next, the insulating layer 80 is etched to form a through hole 82 corresponding to the sacrificial layer 94 and a through hole 84 corresponding to the conductive layer 89. The through hole 82 passes through the insulating layer 80, exposing the sacrificial layer 94. The through hole 84 passes through the insulating layer 80, exposing the conductive layer 89. Next, a top electrode 92 is formed on the insulating layer 80, filling the through hole 84, and contacting the conductive layer 89. Next, the sacrificial layer 94 is removed to form the cavity 86, which is located between the upper electrode 92 and the lower electrode 88. In some embodiments, the sacrificial layer 94 can be removed by an etching process. For example, an etching solution is introduced into the through-hole 82 to etch away the sacrificial layer 94. In some embodiments, the sacrificial layer 94 can also be removed by introducing an etching gas, but this is not limited to this. At this point, the fabrication of the acoustic wave sensor circuit unit 20 is complete.

[0096] See also Figure 4-3-2 According to one embodiment of the present application, a method for manufacturing an acoustic wave sensor circuit unit is provided. Here, a capacitive acoustic wave sensor (CMUT) is used as an example for illustration. Figure 4-3-2 A cross-sectional schematic diagram of a method for manufacturing an acoustic wave sensor circuit unit.

[0097] First, a substrate 50 is provided, and a driving layer 51 is formed on the substrate. Next, a sacrificial layer 94 is formed on the lower electrode 88. The sacrificial layer 94 may include a double-layer structure formed by stacking an amorphous silicon layer 96 and a nickel layer 98, but the present application is not limited thereto. Other specific material combinations are also suitable for the present application, for example, a double-layer structure formed by stacking an amorphous silicon layer and an aluminum layer. Next, an insulating layer 80 is formed on the insulating layer 74, covering the lower electrode 88, the sacrificial layer 94, and the conductive layer 89, and filling the through hole 76. Next, the insulating layer 80 is etched to form a through hole 82 corresponding to the sacrificial layer 94 and a through hole 84 corresponding to the conductive layer 89. The through hole 82 passes through the insulating layer 80, exposing the sacrificial layer 94. The through hole 84 passes through the insulating layer 80, exposing the conductive layer 89. Next, an upper electrode 92 is formed on the insulating layer 80, filling the through hole 84, and contacting the conductive layer 89. Next, an annealing process is performed to form the cavity 86. During the annealing process, a eutectic reaction occurs between the amorphous silicon layer 96 and the nickel layer 98. Nickel atoms dissolve and diffuse into the amorphous silicon layer, forming a new nickel silicide layer 100 on the bottom electrode 88. The volume change of the amorphous silicon layer 96 and the nickel layer 98 during the eutectic process forms a cavity 86. This completes the fabrication of the acoustic wave sensor circuit unit 20.

[0098] The present application fabricates an acoustic wave sensor (MUT) element directly on a substrate containing a transistor structure and implements the MUT using an active matrix. This system includes a pixel array, which is composed of a single pixel, and a single pixel is composed of two transistors and a MUT element. The present application can control the pixel to receive / transmit signals by means of a driving circuit. The MUT may include a PMUT or a CMUT. The PMUT element includes a piezoelectric layer, a cavity, and upper and lower electrodes disposed above and below the piezoelectric layer, respectively; the CMUT element includes a cavity and upper and lower electrodes disposed above and below the cavity, respectively. The cavity in the MUT element can also be formed by a volume change caused by a eutectic reaction between conductive layers. In addition, the present application fabricates the MUT element on a substrate containing a transistor structure, which facilitates large-area fabrication and significantly reduces costs. The present application can be widely used in applications such as distance detection, fingerprint biometric sensors, gesture detection, ultrasound imaging, or biochemical sensors.

[0099] The above summarizes the components of several embodiments so that those skilled in the art can better understand the viewpoints of the embodiments of the present application. Those skilled in the art should understand that they can design or modify other processes and structures based on the embodiments of the present application to achieve the same purposes and / or advantages as the embodiments introduced herein. Those skilled in the art should also understand that such equivalent structures do not deviate from the spirit and scope of the present application, and they can make various changes, substitutions and replacements without violating the spirit and scope of the present application. Therefore, the scope of protection of the present application shall be determined by the definition of the appended claims. In addition, although the present application has been disclosed as above with several preferred embodiments, it is not intended to limit the present application.

[0100] References throughout this specification to features, advantages, or similar language do not imply that all features and advantages that may be realized with this application should or may be realized in any single embodiment of this application. Rather, language referring to features and advantages is understood to mean that a particular feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of this application. Thus, discussions of features and advantages, and similar language, throughout this specification may, but do not necessarily, refer to the same embodiment.

[0101] Furthermore, in one or more embodiments, the described features, advantages, and characteristics of the present application may be combined in any suitable manner. Based on the description herein, one skilled in the relevant art will appreciate that the present application may be practiced without one or more of the specific features or advantages of a particular embodiment. In other cases, additional features and advantages may be identified in certain embodiments that may not be present in all embodiments of the present application.

[0102] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make some modifications and improvements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be based on the definition of the claims.

Claims

1. An electronic device having a signal transmission mode and a signal reception mode, comprising: A plurality of sensor pixels, each of the sensor pixels comprising: an acoustic wave sensor; a first driving circuit; a first demultiplexer electrically connected between the first driving circuit and the acoustic wave sensor; a driving line electrically connected to the acoustic wave sensor, wherein in the signal transmission mode, the driving line is used to transmit a driving signal to the acoustic wave sensor to emit an acoustic wave, and in the signal receiving mode, the driving line is used to transmit a first reference signal to the acoustic wave sensor; a switch line electrically connected to the first demultiplexer; a read line electrically connected to the first demultiplexer; a second driving circuit; and a second demultiplexer electrically connected between the second driving circuit and the acoustic wave sensor, wherein the second demultiplexer comprises at least two transistors, and sources of the at least two transistors are used to receive the driving signal and the first reference signal respectively; The switch line is used to turn on the first demultiplexer to output the sensing signal received by the acoustic wave sensor to the read line.

2. The electronic device according to claim 1, wherein The first demultiplexer includes at least two transistors, and the switching line includes a first switching line and a second switching line, which are electrically connected to the gates of the at least two transistors. In the signal transmission mode, the first driving circuit activates one of the at least two transistors of the first demultiplexer via the first switching line to transmit a second reference signal to the acoustic wave sensor. In the signal reception mode, another first driving circuit transmits the second reference signal to activate the other of the at least two transistors of the first demultiplexer via the second switching line to output an electrical signal to the read line.

Images