Piezoelectric driving resonant MEMS pressure sensor and manufacturing method thereof, and electrical product
By integrating the piezoelectric layer, bottom electrode and top electrode in the resonator of the MEMS pressure sensor, direct contact to avoid DC bias voltage and electrode gap, the existing MEMS pressure sensors in accuracy, cost and compatibility challenges are solved, achieving a piezoelectrically driven resonant MEMS pressure sensor with low energy consumption, low cost and high compatibility.
Patent Information
- Application Number
- CN202311779134.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-22
- Publication Date
- 2025-06-24
AI Technical Summary
Existing MEMS pressure sensors have challenges in accuracy and cost, capacitive sensors have high energy consumption and poor stability, while electromagnetic sensors have large volume and poor compatibility with CMOS circuits.
Using a piezoelectrically driven resonant MEMS pressure sensor, the piezoelectric layer, bottom electrode and top electrode are integrated into the resonator, and the direct contact is to avoid the demand for DC bias voltage and electrode gaps, reducing energy consumption and simplifying the process.
It effectively reduces the energy consumption of the sensor, simplifies the processing technology, reduces the volume, and improves compatibility with CMOS circuits. At the same time, the output frequency signal is strong and is not prone to distortion and drift.
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Figure CN120194830A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of semiconductor technology, and particularly relates to a piezoelectrically actuated resonant MEMS pressure sensor, a manufacturing method thereof, and an electrical product. Background Art
[0002] A MEMS pressure sensor is a thin film element that deforms when subjected to pressure and has wide applications in fields such as automotive, medical, and industrial. For example, it is applied to pressure detection in automotive drive systems, pressure detection of side airbags, control of heating, ventilation, and air conditioning, and engine detection of airplanes.
[0003] Currently, common MEMS pressure sensors include capacitive MEMS pressure sensors, electromagnetic MEMS pressure sensors, etc. Summary of the Invention
[0004] The inventors found that the gap between the resonator and the electrode of a high-precision capacitively actuated resonant MEMS pressure sensor is only a few hundred nanometers, which requires high processing accuracy, resulting in greater processing difficulty and higher cost of the sensor. Moreover, capacitive MEMS pressure sensors require a large DC bias voltage for driving, which leads to problems such as high energy consumption and poor stability of the sensor; while electromagnetic MEMS pressure sensors require a permanent magnet to be placed inside the sensor, which leads to problems such as large volume and poor compatibility with CMOS circuits of the sensor.
[0005] To solve at least one of the above problems existing in the prior art, embodiments of the present application provide a piezoelectrically actuated resonant MEMS pressure sensor, a manufacturing method thereof, and an electrical product.
[0006] According to a first aspect of embodiments of the present application, the present application provides a piezoelectrically actuated resonant MEMS pressure sensor, which includes a pressure sensing diaphragm and a resonator; the resonator includes a substrate, a bottom electrode, a piezoelectric layer, and a top electrode arranged in sequence along a first direction;
[0007] A first cavity is provided on a first surface of the substrate on a side close to the bottom electrode, and a second cavity is provided on a second surface opposite to the first surface. The substrate between the first cavity and the second cavity is the pressure sensing diaphragm;
[0008] At least a part of the bottom electrode, at least a part of the piezoelectric layer, at least a part of the top electrode, at least a part of the first cavity, and at least a part of the second cavity overlap in the first direction.
[0009] According to a second aspect of embodiments of the present application, the present application provides a manufacturing method of a piezoelectrically actuated resonant MEMS pressure sensor as described in the first aspect, and the method includes:
[0010] Form a substrate and form a first cavity on a first surface of the substrate;
[0011] Form a bottom electrode, and the bottom electrode is disposed on the first surface of the substrate;
[0012] Form a piezoelectric layer, and the piezoelectric layer is disposed on a surface of the bottom electrode facing away from the substrate;
[0013] Form a top electrode, and the top electrode is disposed on a surface of the piezoelectric layer facing away from the bottom electrode;
[0014] Form a second cavity on a second surface of the substrate opposite to the first surface to form a pressure sensing diaphragm between the first cavity and the second cavity.
[0015] According to a third aspect of the embodiments of the present application, the present application provides an electrical product, and the electrical product includes the piezoelectric drive resonant MEMS pressure sensor according to any embodiment of the present application.
[0016] One of the beneficial effects of the embodiments of the present application includes: the piezoelectric layer of the piezoelectric drive resonant MEMS pressure sensor of the present application is in direct contact with the top electrode and the bottom electrode, avoiding the application of the DC bias voltage and the electrode gap of the capacitive pressure sensor, effectively reducing the energy consumption of the sensor, and at the same time reducing the process processing difficulty. At the same time, since the sensing and driving electrodes of the pressure sensor are both integrated on the resonator, the pressure sensor has the advantage of small volume. In addition, the processing technology of the pressure sensor of the present application has good process compatibility with the COMS process. Furthermore, the frequency signal output by the pressure sensor has strong stability and is not easily distorted and drifted. Description of the Drawings
[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings. In the drawings:
[0018] Figure 1 is a schematic diagram of a pressure sensor according to an embodiment of the present application.
[0019] Figure 2 is another schematic diagram of a pressure sensor according to an embodiment of the present application.
[0020] Figure 3 is another schematic diagram of a pressure sensor according to an embodiment of the present application.
[0021] Figure 4Another schematic diagram of the pressure sensor according to the embodiment of the present application.
[0022] Figure 5A and Figure 5B Another schematic diagram of the pressure sensor according to the embodiment of the present application.
[0023] Figure 6 A schematic diagram of the silicon cap according to the embodiment of the present application.
[0024] Figure 7 is Figure 6 A schematic diagram of the bonding of the silicon cap shown in Figure 1 to the bottom electrode of the resonator shown in
[0025] Figure 8 is Figure 6 A schematic diagram of the bonding of the silicon cap shown in Figure 1 to the top electrode of the resonator shown in
[0026] Figure 9 is Figure 6 A schematic diagram of the bonding of the silicon cap shown in Figure 3 to the bottom electrode of the resonator shown in
[0027] Figure 10 is Figure 6 A schematic diagram of the bonding of the silicon cap shown in Figure 3 to the top electrode of the resonator shown in
[0028] Figure 11 is Figure 6 A schematic diagram of the bonding of the silicon cap shown in Figure 4 to the top electrode of the resonator shown in
[0029] Figure 12A A top view of the differential pressure type pressure sensor according to the embodiment of the present application.
[0030] Figure 12B is Figure 12A A cross-sectional view of the differential pressure type pressure sensor along the AA' direction.
[0031] Figure 12C Another top view of the pressure sensor according to the embodiment of the present application.
[0032] Figure 13 A schematic diagram of the manufacturing method of the pressure sensor according to the embodiment of the present application.
[0033] Figure 14 is Figure 7 A schematic diagram of the manufacturing method of the pressure sensor shown in
[0034] Figures 15A to 15I is Figure 7 A schematic diagram of the pressure sensor at different process stages shown in
[0035] Figure 16 Schematic diagram of a manufacturing method of the pressure sensor shown Figure 9 in FIG.
[0036] Figures 17A to 17H Schematic diagram of the pressure sensor shown Figure 9 at different process stages
[0037] Figure 18 Schematic diagram of a manufacturing method of a substrate of the pressure sensor shown Figure 5A in FIG.
[0038] Figures 19A to 19C Schematic diagram of the substrate of the pressure sensor shown Figure 5A at different process stages
[0039] Figure 20 Schematic diagram of bonding of a silicon cap shown Figure 6 to a top electrode of a resonator shown Figure 5A in FIG. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings. Herein, the illustrative embodiments of the present invention and their descriptions are used to explain the present invention, but not to limit the present invention
[0041] To solve at least one of the above problems existing in the prior art, in a first aspect, an embodiment of the present application provides a piezoelectrically driven resonant MEMS pressure sensor (hereinafter simply referred to as "pressure sensor") Figure 1 Schematic diagram of a pressure sensor according to an embodiment of the present application. As Figure 1 shown in FIG., the pressure sensor 1 includes a resonator 100 and a pressure sensing diaphragm 400. The resonator 100 is a sensitive element of the pressure sensor 1
[0042] The resonator 100 includes a substrate 101-1, a bottom electrode 102, a piezoelectric layer 103, and a top electrode 104 arranged in sequence along a first direction, i.e., Figure 1 the X1 direction shown in FIG., The substrate 101 is used to carry the bottom electrode 102, the piezoelectric layer 103, and the top electrode 104. The substrate 101 is, for example Figure 1The silicon substrate 101-1 shown has materials including but not limited to semiconductor materials such as single-crystalline silicon, polycrystalline silicon, silicon carbide, sapphire, quartz, etc. When the substrate 101-1 selects silicon carbide, it can be applicable to high-temperature environments. The materials of the bottom electrode 102 include but not limited to molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium, or composites of the above metals or their alloys. The materials of the piezoelectric layer 103 include but not limited to aluminum nitride, zinc oxide, PZT and other materials or rare-earth element doped materials with a certain atomic ratio containing the above materials. The materials of the top electrode 104 include but not limited to molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium, or composites of the above metals or their alloys, and can also be doped polysilicon. This application does not limit the materials of the components of the resonator 100.
[0043] The pressure-sensitive diaphragm 400 is formed in the substrate 101-1, or is a part of the substrate 101-1. As Figure 1 shown, the first surface of the substrate 101-1 on the side close to the bottom electrode 102 (i.e., Figure 1 the upper surface of the substrate 101-1 in ) is provided with a first cavity 301, and the second surface opposite to the first surface (i.e., Figure 1 the lower surface of the substrate 101-1 in ) is provided with a second cavity 302. The first cavity 301 and the second cavity 302 overlap in the first direction X1 and are separated by a part of the substrate 101-1. The part of the substrate 101-1 that separates the first cavity 301 and the second cavity 302 is the pressure-sensitive diaphragm 400. The shape of the pressure-sensitive diaphragm 400 includes but not limited to circular, square or other shapes, and this application does not limit this.
[0044] Viewed from the aforementioned first direction X1 (or the second direction X2 opposite to the first direction), at least part of the bottom electrode 102, at least part of the piezoelectric layer 103, at least part of the top electrode 104, at least part of the first cavity 301, and at least part of the second cavity 302 overlap.
[0045] Figure 1 In, the structure connecting the cavity 301 is the release channel 5. This release channel is designed to release the sacrificial layer filled in the cavity 301 to form the cavity 301 in the manufacturing process of the pressure sensor. The material of this sacrificial layer is, for example, phosphosilicate glass. The release channel 5 can be formed by etching the piezoelectric layer 103. The specific manufacturing process will be described in the subsequent embodiments.
[0046] In this embodiment, the piezoelectric layer of the pressure sensor is in direct contact with the bottom electrode and the top electrode, avoiding the application of the DC bias voltage and the electrode gap of the capacitive pressure sensor, effectively reducing the energy consumption of the sensor, and at the same time reducing the process processing difficulty. At the same time, since both the sensing and driving electrodes of the pressure sensor are integrated on the resonator, the pressure sensor has the advantage of small volume. Moreover, the processing technology of the pressure sensor of the present application has good process compatibility with the COMS process. In addition, the frequency signal output by the pressure sensor of the present application has strong stability and is not easily distorted and drifted.
[0047] In some embodiments, a support layer is provided between the substrate and the bottom electrode.
[0048] For example, as Figure 1 shown, a support layer 105 is provided between the substrate 101-1 and the bottom electrode 102. The material of the support layer 105 can be materials such as aluminum nitride, zinc oxide, PZT, etc. or rare earth element doped materials with a certain atomic ratio containing the above materials. At this time, in the manufacturing process, the support layer 105 can be formed by a deposition method. The material of the support layer 105 can also be single crystal silicon, silicon nitride, silicon oxide, polysilicon, etc. At this time, in the manufacturing process, the support layer 105 can be formed by a low-pressure chemical vapor deposition method.
[0049] When there is a support layer 105, the release channel 5 is formed by etching the piezoelectric layer 103 and the support layer 105.
[0050] In other embodiments, the bottom electrode 102 and the support layer 105 can also be set as the same layer, that is Figure 1 the shown pressure sensor may not include the support layer 105, or the support layer 105 and the bottom electrode 102 are jointly represented as a single structure of the bottom electrode 102.
[0051] Figure 2 Another schematic diagram of the pressure sensor according to the embodiment of the present application. As Figure 2 shown, the substrate 101 of the resonator 100 adopts a SOI silicon wafer 101-2. The SOI silicon wafer 101-2 includes a bottom silicon layer 1011, a buried oxide layer 1012, and a top silicon layer 1013 arranged in sequence along the first direction X1. On the top silicon layer 1013, a bottom electrode 102, a piezoelectric layer 103, and a top electrode 104 are arranged in sequence.
[0052] Among them, the first cavity 301 is arranged on the surface of the top silicon layer 1013 close to the bottom electrode 102 (that is Figure 2 the upper surface of the top silicon layer 1013 shown), and the second cavity 302 is arranged on the surface of the bottom silicon layer 1011 facing away from the top silicon layer 1013 (that is Figure 2 the lower surface of the bottom silicon layer 1011 shown). At Figure 2In the pressure sensor 1 shown, the pressure sensing diaphragm 400 is a partial top silicon layer 1013 between the first cavity 301 and the second cavity 302. The buried oxide layer 1012 is an etching stop layer.
[0053] Figure 2 For structures similar to those in Figure 1 please refer to the description in the relevant part, which will not be elaborated here.
[0054] Figure 2 Use the SOI wafer 101-2 to replace Figure 1 the silicon substrate 101-1 in. Thus, during the processing, when processing the pressure sensing diaphragm 400, only the bottom silicon layer 1011 at the corresponding position needs to be completely etched, and the thickness of the pressure sensing diaphragm 400 can be accurately controlled. For example, in an SOI wafer, the thickness of the top silicon layer is a μm, and the required thickness of the pressure sensing diaphragm is b μm. Then during processing, only the top silicon layer needs to be etched to form a first cavity 301 with a depth of (a - b) μm, and the bottom silicon layer at the corresponding position is completely etched to form a second cavity 302, so that the thickness of the pressure sensing diaphragm 400 can be accurately controlled to be the thickness of the top silicon layer 1013 between the first cavity 301 and the second cavity 302.
[0055] In some embodiments, a support layer is provided between the substrate and the bottom electrode.
[0056] For example, as Figure 2 shown, a support layer 105 is provided between the substrate 102-1 and the bottom electrode 102. The material, processing technology, and other related content of the support layer 105 are as described above and will not be repeated here.
[0057] When the support layer 105 exists, the release channel 5 is formed by etching the piezoelectric layer 103 and the support layer 105.
[0058] In other embodiments, the bottom electrode 102 and the support layer 105 can also be set as the same layer, that is Figure 2 the pressure sensor shown may not include the support layer 105, or the support layer 105 and the bottom electrode 102 are jointly represented as a single structure of the bottom electrode 102.
[0059] Figure 3 This is another schematic diagram of the pressure sensor according to the embodiment of the present application. As Figure 3 shown, the substrate 101 of the resonator 100 uses an SOI wafer 101-2, which includes a bottom silicon layer 1011, a buried oxide layer 1012, and a top silicon layer 1013 along the first direction X1. On the top silicon layer 1013, a bottom electrode 102, a piezoelectric layer 103, and a top electrode 104 are sequentially arranged along the first direction X1.
[0060] Among them, the first cavity 301 is surrounded by a top silicon layer 1013, a buried oxide layer 1012, and a bottom silicon layer 1011; the top silicon layer 1013 and the bottom silicon layer 1011 serve as the upper bottom surface and the lower bottom surface of the first cavity 301 respectively, and the buried oxide layer 1012 serves as the side wall of the first cavity 301. The second cavity 302 is disposed on the surface of the bottom silicon layer 1011 facing away from the top silicon layer 1013 (i.e., Figure 3 the lower surface of the bottom silicon layer 1011). In Figure 3 the pressure sensor 1 shown, the pressure sensing diaphragm 400 is a part of the bottom silicon layer 1011 between the first cavity 301 and the second cavity 302.
[0061] Figure 3 In
[0062] Figure 3 and Figure 1 and Figure 2 the similar structures, please refer to the descriptions of the relevant parts, and will not be elaborated here.
[0063] In some embodiments, an insulating layer is provided between the top silicon layer of the SOI wafer and the bottom electrode.
[0064] For example, as Figure 3 shown, between the top silicon layer 1013 of the SOI wafer 101-2 and the bottom electrode 102, an insulating layer 106 is provided. The material of the insulating layer 106 can be aluminum nitride.
[0065] When there is an insulating layer 106, the release channel 5 is formed by etching the piezoelectric layer 103, the insulating layer 106, and the top silicon layer 1013.
[0066] In Figure 3 the pressure sensor shown, the top silicon layer 1013 of the SOI wafer 101-2 is used to support other structures disposed on the SOI wafer 101-2.
[0067] Figure 4 is another schematic diagram of the pressure sensor according to the embodiment of the present application. As Figure 4 shown, the substrate 101 of the resonator 100 uses an SOI wafer 101-2, which includes a bottom silicon layer 1011, a buried oxide layer 1012, and a top silicon layer 1013 along the first direction X1. On the top silicon layer 1013, a piezoelectric layer 103 and a top electrode 104 are sequentially disposed along the first direction X1.
[0068] Figure 4 In [the above], taking advantage of the low resistivity characteristic of the top silicon layer 103, the top silicon layer 1013 is used as the bottom electrode 102, that is, the bottom electrode 102 is the top silicon layer 1013 of the SOI silicon wafer.
[0069] Figure 4 The pressure sensor of [the above] omits Figure 3 the structure and processing flow of the bottom electrode 102 and the insulating layer 106 in [the above]. Thus, the processing flow of the pressure sensor can be simplified, and the volume of the pressure sensor can be reduced.
[0070] Figure 4 In [the above] and Figures 1 to 3 similar structures, please refer to the description in the relevant part, which will not be elaborated here.
[0071] Figure 5A This is another schematic diagram of the pressure sensor according to the embodiment of the present application. As Figure 5A shown, the substrate 101 of the resonator 100 uses a CSOI silicon wafer 101-3. The CSOI silicon wafer 101-3 includes a bottom silicon layer 1011, a buried oxide layer 1012, a first top silicon layer 1013, and a second top silicon layer 1014 arranged in sequence along the first direction X1. On the second top silicon layer 1014, a bottom electrode 102, a piezoelectric layer 103, and a top electrode 104 are arranged in sequence. Between the first top silicon layer 1013 and the second top silicon layer 1014, a thermal oxidation bonding layer 1015 is provided. During the processing of the CSOI silicon wafer 101-3, the first top silicon layer 1013 and the second top silicon layer 1014 are bonded through the thermal oxidation bonding layer 1015, and the specific processing process will be described in the subsequent embodiments.
[0072] Among them, the first cavity 301 is arranged on the surface of the first top silicon layer 1013 close to the second top silicon layer 1014 (that is, Figure 5A the upper surface of the top silicon layer 1013 shown), and the second cavity 302 is arranged on the surface of the bottom silicon layer 1011 facing away from the first top silicon layer 1013 (that is, Figure 5A the lower surface of the bottom silicon layer 1011 shown). In Figure 5A the pressure sensor 1 shown, the pressure sensing diaphragm 400 is a part of the first top silicon layer 1013 and the buried oxide layer 1012 between the first cavity 301 and the second cavity 302. The buried oxide layer 1012 is an etching stop layer. The thermal oxidation bonding layer 1015 covers the bottom and side walls of the first cavity 301 and extends between the first top silicon layer 1013 and the second top silicon layer 1014.
[0073] In some embodiments, Figure 5A the pressure sensing diaphragm 400 in [the above] is a part of the first top silicon layer 1013 between the first cavity 301 and the second cavity 302, and the first top silicon layer 1013 is an etching stop layer, that is, Figure 5AIn this case, the buried oxide layer 1012 between the first cavity 301 and the second cavity 302 can be removed by etching, leaving only the first top silicon layer 1013 as the pressure sensing diaphragm 400.
[0074] It should be noted that although Figure 5A the first cavity 301 does not need to be obtained by etching the sacrificial layer, the piezoelectric layer 103, the insulating layer 106, and the second top silicon layer 1014 still need to be etched to form a release channel 5 communicating with the first cavity 301. However, at this time, the release channel 5 is no longer used to release the sacrificial layer, but only serves as part of the structure of the resonator. In Figures 1 to 4 the release channel 5 serves as the structure of the resonator and is reused as the release channel at the same time.
[0075] Figure 5A For the structures similar to those in Figures 1 to 4 please refer to the description of the relevant parts, and will not be elaborated here.
[0076] In some embodiments, the substrate 101 of the resonator 10 may also adopt a CSOI silicon wafer with other structures. For example, the Figure 5A bottom silicon layer 1011, the buried oxide layer 1012, and the first top silicon layer 1013 in are replaced with a silicon substrate. Figure 5B is another schematic diagram of the pressure sensor according to the embodiment of the present application. As Figure 5B shown, the substrate 101 of the resonator 100 adopts a CSOI silicon wafer 101-3'. The CSOI silicon wafer 101-3' includes a silicon substrate 101-1' and a second top silicon layer 1014 arranged in sequence along the first direction X1. On the second top silicon layer 1014, a bottom electrode 102, a piezoelectric layer 103, and a top electrode 104 are arranged in sequence. Between the silicon substrate 101-1' and the second top silicon layer 1014, a thermal oxidation bonding layer 1015 is arranged. During the processing of the CSOI silicon wafer 101-3', the silicon substrate 101-1' and the second top silicon layer 1014 are bonded through the thermal oxidation bonding layer 1015, and the specific processing process will be described in subsequent embodiments.
[0077] Among them, the first cavity 301 is arranged on the surface of the silicon substrate 101-1' close to the second top silicon layer 1014 (i.e., Figure 5B the upper surface of the silicon substrate 101-1' shown), and the second cavity 302 is arranged on the surface of the silicon substrate 101-1' facing away from the second top silicon layer 1014 (i.e., Figure 5B the lower surface of the silicon substrate 101-1' shown). In Figure 5B the pressure sensor 1 shown, the pressure sensing diaphragm 400 is a part of the silicon substrate 101-1' between the first cavity 301 and the second cavity 302. The thermal oxidation bonding layer 1015 covers the bottom and side walls of the first cavity 301 and extends between the silicon substrate 101-1' and the second top silicon layer 1014.
[0078] Figure 5B In Figures 1 to 4 For the similar structures in, please refer to the descriptions in the relevant parts, and will not be elaborated here.
[0079] In some embodiments, an insulating layer is provided between the second top silicon layer of the CSOI silicon wafer and the bottom electrode.
[0080] For example, as Figure 5A shown, between the second top silicon layer 1014 and the bottom electrode 102 of the CSOI silicon wafer 101-3, an insulating layer 106 is provided. The material of the insulating layer 106 can be aluminum nitride.
[0081] When the insulating layer 106 exists, the release channel 5 is formed by etching the piezoelectric layer 103, the insulating layer 106, and the top silicon layer 1013.
[0082] In Figure 5A the pressure sensor shown, the second top silicon layer 1014 of the CSOI silicon wafer 101-3 is used to support other structures disposed on the CSOI silicon wafer 101-3.
[0083] This application has described the pressure sensor through the above embodiments. It can be understood that the corresponding Figures 1 to 5B embodiments focus on describing the differences from other embodiments. The same or similar structures in the above embodiments can be implemented with reference to each other, so there is no repeated description.
[0084] Figures 1 to 5B In the corresponding embodiments, the pressure sensor is not vacuum packaged, and the resonator can be directly used as a gauge pressure sensor.
[0085] In some embodiments, the pressure sensor further includes a silicon cap, and the silicon cap is bonded to the resonator. Figure 6 This is a schematic diagram of the silicon cap of the embodiment of this application. As Figure 6 shown, the silicon cap 200 includes a substrate 201, a bonding layer 202, metal pins 203, and conductive vias 204. At least one protrusion 205 is provided on the first surface 2011 of the substrate 201 (i.e., Figure 6 the lower surface of the substrate 201 shown), and the bonding layer 202 is provided on the protrusion 205. The protrusion 205 is used to bond to the top electrode or the bottom electrode of the resonator. The metal pins 203 penetrate through the substrate 201 and its protrusion 205, and the conductive vias 204 are provided on the second surface 2012 of the substrate 201 opposite to the first surface 2011 (i.e., Figure 6(upper surface of the substrate 201 shown). The conductive vias 204 can be metal vias or conductive vias formed by highly doped polysilicon or single-crystalline silicon. One end of the metal pin 203 is connected to the bonding layer 202 disposed on the corresponding protrusion 205, and the other end is connected to the conductive via 204. The metal pin 203 and the conductive via 204 together serve as a conductive structure. This conductive structure can guide the signal of the resonator 100 above the silicon cap 200, that is, the side of the silicon cap 200 facing away from the resonator 100; and the conductive via 204 can also be connected to other electrical devices, thereby transmitting the signal of the resonator 100 to other devices.
[0086] In some embodiments, an insulating layer can also be provided between the conductive structure and the substrate 201 of the silicon cap 200. Thus, the conductive structure is isolated from the substrate 201 through the insulating layer, which is beneficial to improving the transmission performance of the signal of the resonator.
[0087] In some embodiments, the silicon cap is bonded to the resonator through a bonding layer, and the bonding layer is disposed on the bottom electrode. Figure 7 For Figure 6 the silicon cap 200 shown and Figure 1 a schematic diagram of the bonding of the bottom electrode of the resonator 100 shown. As Figure 7 shown, the silicon cap 200 is bonded to the bottom electrode 102 of the resonator 100 through the protrusion 205. At this time, in the resonator 100, a part of the bottom electrode 102 bonded to the protrusion 205 is exposed, and a bonding layer 107 is also provided on the exposed bottom electrode 102. The bonding layer 107 electrically connects the bottom electrode 102 and the top electrode 104. Thus, the resonator 100 and the silicon cap 200 are bonded together through the bonding layer 107 of the resonator 100 and the bonding layer 202 of the silicon cap 200.
[0088] Among them, the materials of the substrate 201 and its protrusion 205 include but are not limited to semiconductor materials such as single-crystalline silicon, polysilicon, silicon carbide, sapphire, quartz, etc. When the substrate 101-1 is selected as silicon carbide, it can be applied to high-temperature environments. The materials of the bonding layer 202 and the bonding layer 107 include but are not limited to gold, aluminum, germanium, copper, tin, titanium, or composite layers or alloys of the above metals, etc. Moreover, the materials of the bonding layer 202 and the bonding layer 107 need to be selected in cooperation to form gold-gold bonding, aluminum-germanium bonding, copper-copper bonding, copper-gold-copper bonding, copper-tin bonding, copper-tin-gold bonding, etc. The material of the metal pin 203 includes but is not limited to gold, aluminum, copper, titanium, iridium, osmium, chromium, or composites or alloys of the above metals, etc. The material of the conductive via 204 includes but is not limited to materials such as copper, gold, low-resistance polysilicon, aluminum, aluminum-silicon-copper alloy, or composite layers thereof.
[0089] In some embodiments, the silicon cap is bonded to the resonator through a bonding layer, and the bonding layer is disposed on the top electrode. Figure 8 For Figure 6 the schematic diagram of the bonding of the silicon cap shown Figure 1 to the top electrode of the resonator shown. As Figure 8 shown, the silicon cap 200 is bonded to the top electrode 104 of the resonator 100 through the protrusion 205. At this time, the shape of the top electrode 103 of the resonator 100 needs to cooperate with the position of the protrusion 205, and a bonding layer 107 is further disposed on the top electrode 102. The bonding layer 107 electrically connects the top electrode 104 and the partially exposed bottom electrode 102. Thus, the resonator 100 and the silicon cap 200 are bonded together through the bonding layer 107 of the resonator 100 and the bonding layer 202 of the silicon cap 200.
[0090] In some embodiments, a dielectric layer is further disposed between the bonding layer and the top electrode. The setting position of the bonding layer can be various, not limited to those shown in the specification, as long as it can meet the requirements of electrical connection of the resonator, resonator sealing, and electrical isolation of the non - electrically connected area between the resonator and the silicon cap.
[0091] In this application, the bonding layers (such as bonding layer 202 and bonding layer 107) used for bonding the silicon cap and the resonator are both metal layers.
[0092] For the materials of each structure, please refer to the foregoing embodiments and will not be repeated here.
[0093] In addition, the top electrode or the bottom electrode of any resonator in the embodiments of this application can be bonded to Figure 6 the silicon cap shown, for example Figure 9 for Figure 6 the schematic diagram of the bonding of the silicon cap shown Figure 3 to the bottom electrode of the resonator shown, Figure 10 for Figure 6 the schematic diagram of the bonding of the silicon cap shown Figure 3 to the top electrode of the resonator shown. Figure 11 For Figure 6 the schematic diagram of the bonding of the silicon cap shown Figure 4 to the top electrode of the resonator shown. The remaining combination methods will not be shown one by one here.
[0094] In some embodiments, the bonding layer 202 and the bonding layer 107 also serve as a sealing ring at the same time, so it can also be a bonding and sealing ring. At this time, after the silicon cap 200 is bonded to the resonator 100, a vacuum third cavity 303 is formed between the silicon cap and the resonator, as Figures 7 to 11 described, the third cavity 303 is disposed in the silicon cap 200. When the silicon cap 200 is bonded to the resonator 100, the third cavity 303 communicates with the first cavity 301 on the resonator (please refer toFigures 1 to 5B ) are connected, and the vacuum degree of the connected third cavity and the first cavity is lower than 50 Pa. In some other embodiments, the vacuum degree of the connected third cavity and the first cavity is lower than 10 Pa; in some other embodiments, the vacuum degree of the connected third cavity and the first cavity is lower than 1 Pa. In addition, at least at the bottom of the third cavity 303, a getter layer 206 is provided. For example, in addition to the bottom of the third cavity 303, the getter layer can also be provided on the side wall of the third cavity 303 and other positions in the space where the third cavity 303 is connected to the first cavity 301. The present application does not limit this.
[0095] Thus, the silicon cap 200 encapsulates the resonator 100 with a high vacuum degree, thereby forming an absolute pressure type pressure sensor. The higher the vacuum degree, the higher the Q value of the resonator, and the better the performance of the absolute pressure type pressure sensor.
[0096] In some embodiments, by adjusting the bonding surface position of the silicon cap 200 and the resonator 100 and the thickness of the silicon cap 200, a differential pressure type pressure sensor can be formed.
[0097] For example, one bonding method of the silicon cap and the resonator is: in the first direction, the silicon cap is only located in the resonant region of the resonator, the bonding layer is as narrow as possible and as close to the resonator as possible, and the region where the third cavity is located is covered by the region where the second cavity is located, and the region where the third cavity is located is greater than or equal to the region where the first cavity is located. Figure 12A This is a top view of the differential pressure type pressure sensor provided by the present application. Figure 12B is Figure 12A The cross-sectional view of the differential pressure type pressure sensor along the AA' direction. As Figure 12A and Figure 12B shown, in the first direction X1, the silicon cap 200 is only located in the resonant region of the resonator 100, and the bonding layer 202 and the bonding layer 107 are as narrow as possible and as close to the resonant region as possible. The resonant region is the region with a resonant structure in the first direction X1. The region where the third cavity 303 is located is covered by the region where the second cavity 302 is located, and the region where the third cavity 301 is located is greater than or equal to the region where the first cavity 301 is located.
[0098] Another example, another bonding method of the silicon cap and the resonator is: in the first direction, the silicon cap is located on the entire surface of the resonator, at least completely covering the region where the pressure sensing diaphragm of the resonator is located. The region where the third cavity is located is greater than or equal to the region where the second cavity is located, and the bonding surface includes the region above the entire pressure sensing diaphragm without the resonator, so as to ensure that the silicon cap and the pressure sensing diaphragm below form a complete diaphragm, so as to facilitate the transfer of the pressure difference above and below the diaphragm to the resonator. Figure 7For example, in the first direction X1, the silicon cap 200 covers the entire surface of the resonator 100. The silicon cap 200 at least completely covers the area where the pressure-sensitive diaphragm 400 is located. The area of the third cavity 303 is greater than or equal to the area of the second cavity 302, and the bonding surface includes the area above the entire pressure-sensitive diaphragm 400 where there is no resonator.
[0099] Thus, the silicon cap 200 and the pressure-sensitive diaphragm 400 form a complete diaphragm, facilitating the transfer of the pressure difference above and below the diaphragm to the resonator 100. When pressure is applied to the pressure sensor 1, the silicon cap 200 and the pressure-sensitive diaphragm 400 deform simultaneously, and then transfer the axial pressure to the resonator 100, causing a change in the resonance frequency. When the pressure sensor is working, the external circuit drives the resonator to work in the resonance state, and the magnitude of the pressure change can be measured by detecting the change in the frequency signal of the resonator. When pressure is applied to the silicon cap 200, this pressure forms a pressure difference with the pressure applied to the pressure-sensitive diaphragm 400, and then the resonator 100 detects this pressure difference as a differential pressure sensor.
[0100] In some embodiments, the working mode of the resonator in the pressure sensor is the flexural vibration mode.
[0101] The flexural vibration mode of the resonator includes in-plane vibration and out-of-plane vibration, specifically including in-plane co-directional vibration, in-plane counter-directional vibration, out-of-plane counter-directional vibration, out-of-plane co-directional vibration, etc. By etching the top electrode 104 of the resonator 100 into different structures during the processing flow, different vibration modes of the resonator can be excited. For example, the structures of the top electrode that can achieve the flexural vibration mode of the resonator include, but are not limited to, circular structures, fixed beam structures, etc. Figure 12A and Figure 12C is a top view of the pressure sensor according to an embodiment of the present application. As Figure 12C shown, the structure of the top electrode 104 of the resonator is a circular structure. At this time, the vibration mode of the resonator is out-of-plane vibration; as Figure 12A shown, the shape of the top electrode 104 of the resonator is a fixed beam structure. At this time, the vibration mode of the resonator is in-plane counter-directional vibration. In addition, the resonator can also work in other vibration modes other than the flexural vibration mode, and the present application does not limit this.
[0102] The piezoelectric layer of the piezoelectrically driven resonant MEMS pressure sensor of the present application is in direct contact with the top electrode and the bottom electrode, avoiding the application of the DC bias voltage and the electrode gap of the capacitive pressure sensor, effectively reducing the energy consumption of the sensor, and at the same time reducing the process processing difficulty. At the same time, since the sensing and driving electrodes of the pressure sensor are both integrated on the resonator, the pressure sensor has the advantage of small volume. In addition, the frequency signal output by the pressure sensor of the present application has strong stability and is not easily distorted and drifted.
[0103] According to a second aspect of the embodiments of the present application, the present application provides a manufacturing method for a piezoelectrically driven resonant MEMS pressure sensor. Figure 13 It is a schematic diagram of the manufacturing method of the pressure sensor according to the embodiments of the present application. As Figure 13 shown, the method includes:
[0104] 1301, forming a substrate and forming a first cavity on a first surface of the substrate;
[0105] 1302, forming a bottom electrode, the bottom electrode being disposed on the first surface of the substrate;
[0106] 1303, forming a piezoelectric layer, the piezoelectric layer being disposed on a surface of the bottom electrode facing away from the substrate;
[0107] 1304, forming a top electrode, the top electrode being disposed on a surface of the piezoelectric layer facing away from the bottom electrode;
[0108] 1305, forming a second cavity on a second surface of the substrate opposite to the first surface, so as to form a pressure sensing diaphragm between the first cavity and the second cavity.
[0109] In some embodiments, before 1305, the method further includes:
[0110] 1304-1, bonding a resonator to a silicon cap to create a vacuum environment for the resonator to operate.
[0111] The above manufacturing method is applicable to any pressure sensor in the present application. The formation positions, materials, structures, etc. of the substrate, bottom electrode, piezoelectric layer, top electrode, and pressure sensing diaphragm involved can be referred to Figures 1 to 11 the corresponding embodiments and will not be repeated here.
[0112] The following will specifically describe this manufacturing method in combination with some pressure sensors provided by the present application. Figure 14 For Figure 7 the schematic diagram of the manufacturing method of the pressure sensor shown, Figures 15A to 15I For Figure 7 the schematic diagram of the pressure sensor at different process stages shown. As Figures 14 to 15I shown, when the pressure sensor includes a silicon cap, the manufacturing method includes:
[0113] 1401, forming a substrate 101-1 and forming a first cavity 301 on a first surface of the substrate, refer to Figure 15A ;
[0114] 1402. Fill the sacrificial layer 301' in the first cavity 301, deposit the support layer 105 and the bottom electrode 102 on the first surface of the substrate 101 and the sacrificial layer 301', and etch the pattern of the bottom electrode. See Figure 15B ;
[0115] 1403. Deposit the piezoelectric layer 103 and the top electrode 104 on the bottom electrode 102 and the support layer 105, and etch the pattern of the top electrode 104. See Figure 15C ;
[0116] 1404. Etch the piezoelectric layer 103 to expose a part of the bottom electrode 102. See Figure 15D ;
[0117] 1405. Etch the piezoelectric layer 103 and the support layer 105 at one time to form the release channel 5. See Figure 15E ;
[0118] 1406. Sputter metal on the exposed part of the bottom electrode 102 to electrically connect the bottom electrode 102 and the top electrode 104, and form the bonding layer 107. See Figure 15F ;
[0119] 1407. Etch the sacrificial layer through the release channel 5 to release the resonator. See Figure 15G ;
[0120] 1408. Bond the resonator to the silicon cap to create a vacuum environment for the resonator to work, that is, form the third cavity 303. See Figure 15H ;
[0121] 1409. Etch the second cavity 302 from the back of the substrate 101 - 1 to form the pressure sensing diaphragm 400. See Figure 15I .
[0122] Figure 8 The manufacturing method of the pressure sensor shown can be referred to Figure 14 for implementation. The difference is only that in 1406, metal is sputtered on the top electrode 104 to form the bonding layer 107.
[0123] Figure 1 The manufacturing method of the pressure sensor shown can also be referred to Figure 14 for implementation. The difference is that steps 1404, 1406, and 1408 do not need to be executed.
[0124] Figure 2 The manufacturing method of the pressure sensor shown in Figure 1 is similar to the manufacturing method of the pressure sensor shown and can be referred to for implementation. The difference is only that the substrate 101 used is different.
[0125] Figure 16 ForFigure 9 Schematic diagram of a method for manufacturing the pressure sensor shown Figures 17A to 17H is Figure 9 Schematic diagrams of the pressure sensor shown at different process stages. As Figures 16 to 17H shown, when the pressure sensor includes a silicon cap, the manufacturing method includes:
[0126] 1601, deposit an insulating layer 106 and a bottom electrode 102 on the top silicon layer 1013 of the SOI wafer 101-2, and etch a pattern of the bottom electrode 102, see Figure 17A ;
[0127] 1602, deposit a piezoelectric layer 103 and a top electrode 104 on the insulating layer 106 and the bottom electrode 102, and etch a pattern of the top electrode 104, see Figure 17B ;
[0128] 1603, etch the piezoelectric layer 103 to expose the bottom electrode 102, see Figure 17C ;
[0129] 1604, etch the piezoelectric layer 103, the insulating layer 106 and the top silicon layer 1013 at one time to etch out the resonator shape and form a release channel 5, see Figure 17D ;
[0130] 1605, sputter metal on the exposed part of the bottom electrode 102 to electrically connect the bottom electrode 102 and the top electrode 104 and form a bonding layer 107, see Figure 17E ;
[0131] 1606, etch the buried oxide layer 1012 to release the resonator, see Figure 17F ;
[0132] 1607, bond the resonator 100 with the silicon cap 200 to create a vacuum environment for the resonator to work, that is, form a third cavity 303, see Figure 17G ;
[0133] 1608, etch the second cavity 302 from the back of the SOI wafer 101 (the surface of the bottom silicon layer 1011 facing away from the top silicon layer 1013) to form a pressure sensing diaphragm 400, see Figure 17H .
[0134] Figure 10 The manufacturing method of the pressure sensor shown can be referred to Figure 16 for implementation, the difference is only that in 1605, metal is sputtered on the top electrode 104 to form a bonding layer 107.
[0135] Figure 3 The manufacturing method of the pressure sensor shown can also be referred to Figure 16Implement, with the difference that steps 1603, 1605, and 1607 do not need to be executed.
[0136] Figure 11 The manufacturing method of the pressure sensor shown is similar to Figure 10 the manufacturing method of the pressure sensor shown, and can be referred to Figure 16 Implement. The difference is that step 1601 does not need to be executed, and instead, a piezoelectric layer 103 and a top electrode 104 are directly deposited on the top silicon layer 1013 of the SOI wafer 101, and the pattern of the top electrode 104 is etched.
[0137] Figure 4 The manufacturing method of the pressure sensor shown can also be referred to Figure 16 Implement, with the difference that steps 1601, 1603, 1605, and 1607 do not need to be executed.
[0138] Figure 5A and Figure 5B The manufacturing method of the pressure sensor described is similar to Figure 3 the manufacturing method of the pressure sensor shown, and can be referred to Figure 16 Implement similarly, with the difference that the structure of the substrate 101 is different, and when forming the second cavity 302, Figure 5A the second cavity of the pressure sensor can be formed by completely etching the bottom silicon layer 1011 of the CSOI wafer 101, and the thickness of the pressure sensing diaphragm 400 can be precisely controlled to be the thickness of the CSOI top silicon wafer 101.
[0139] Figure 18 is Figure 5A a schematic diagram of the manufacturing method of the CSOI substrate 101 of the pressure sensor shown, Figures 19A to 19C is Figure 5A a schematic diagram of the CSOI substrate 101 of the pressure sensor shown at different process stages.
[0140] As Figure 18 , Figures 19A to 19C shown, the manufacturing method of the CSOI substrate 101 includes:
[0141] 1801, etching a first cavity 301 on the top silicon layer 1013 of the first SOI wafer 101-2, and generating a thermal oxidation bonding layer 1015, see Figure 19A ;
[0142] 1802, bonding the top silicon layer 1014 of the second SOI wafer 101-2' to the top silicon layer 1013 of the first SOI wafer through the thermal oxidation bonding layer 1015, see Figure 19B ;
[0143] In 1803, the bottom silicon layer 1017 and the buried oxide layer 1016 of the second silicon wafer were removed through a chemical mechanical grinding process and an etching process to obtain a SOI wafer with a cavity, that is, a CSOI wafer 101-3. Refer to Figure 19C .
[0144] Figure 5B The manufacturing method of the CSOI substrate 101 of the pressure sensor shown is similar to Figure 5A , with the only difference being that Figure 19A and Figure 19B the SOI substrate 101-2 therein is replaced with a silicon substrate, and the first cavity 301 is etched and formed on the upper surface of 101-1' of the silicon substrate.
[0145] Figure 20 is Figure 6 a schematic diagram of the bonding of the silicon cap shown to the top electrode of the resonator shown. The method of bonding the pressure sensor shown in Figure 5A to the silicon cap is similar to the foregoing embodiments. For example, reference can be made to the implementations of Figure 5A 1603, 1605, and 1607, or reference can be made to the implementations of Figure 16 1404, 1406, and 1408. Only the differences will be described here, and the repeated parts will not be elaborated. Figure 14
[0146] The manufacturing method of the pressure sensor provided in this embodiment has good process compatibility with the COMS process. It can be understood that the above embodiments only give the Figure 1 , Figure 3 , Figure 7 , Figure 9 manufacturing methods of the pressure sensors shown, Figure 2 , Figure 4 , Figure 5A , Figure 5B , Figure 8 , Figure 10 , Figure 11 manufacturing methods of the pressure sensors shown can be referred to for implementation, which will not be elaborated here.
[0147] According to the third aspect of the embodiments of the present application, the present application provides an electrical product, which includes a longitudinal electric field excited single crystal piezoelectric resonator as described in any embodiment of the present application. For example, the electrical product includes: (1) radio frequency filters, duplexers, multiplexers, especially broadband radio frequency filters applied to the 5G communication band, such as N77, N78, N79, and WiFi filters applied to the frequency band of 3 GHz to 5 GHz; (2) radio frequency front-end modules, communication modules, and communication devices including the above filters, duplexers, and multiplexers; (3) oscillators, clock signal generators; (4) biological, chemical, and physical sensors using the resonator as a sensitive element; (5) Internet of Things sensing nodes including the above resonator, or filter, or oscillator, or sensor.
[0148] The specific embodiments described above further elaborate on the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.
Claims
1. A piezoelectrically actuated resonant MEMS pressure sensor, characterized in that, The pressure sensor includes a pressure sensing diaphragm and a resonator; The resonator includes a substrate, a bottom electrode, a piezoelectric layer, and a top electrode arranged in sequence along a first direction; On a first surface of the substrate near the bottom electrode side, a first cavity is provided, and on a second surface opposite to the first surface, a second cavity is provided. The substrate between the first cavity and the second cavity is the pressure sensing diaphragm; At least part of the bottom electrode, at least part of the piezoelectric layer, at least part of the top electrode, at least part of the first cavity, and at least part of the second cavity overlap in the first direction.
2. The pressure sensor according to claim 1, wherein, The substrate is made of a semiconductor material such as single crystal silicon, polycrystalline silicon, silicon carbide, sapphire, or quartz; Moreover, a support layer is provided between the substrate and the bottom electrode.
3. The pressure sensor according to claim 1, wherein The substrate is a SOI silicon wafer, and the SOI silicon wafer includes a bottom silicon layer, a buried oxide layer, and a top silicon layer arranged in sequence along the first direction.
4. The pressure sensor according to claim 3, characterized in that, The first cavity is provided on a surface of the top silicon layer near the bottom electrode; The second cavity is provided on a surface of the bottom silicon layer facing away from the top silicon layer; Moreover, a support layer is provided between the top silicon layer and the bottom electrode; The pressure sensing diaphragm is the top silicon layer between the first cavity and the second cavity, or is the top silicon layer and the buried oxide layer between the first cavity and the second cavity.
5. The pressure sensor according to claim 3, characterized in that, The first cavity is surrounded by the top silicon layer, the buried oxide layer, and the bottom silicon layer; The second cavity is provided on a surface of the bottom silicon layer facing away from the top silicon layer; The pressure sensing diaphragm is the bottom silicon layer between the first cavity and the second cavity.
6. The pressure sensor according to claim 5, characterized in that, An insulating layer is provided between the top silicon layer of the SOI silicon wafer and the bottom electrode.
7. The pressure sensor according to claim 5, characterized in that The bottom electrode is the top silicon layer of the SOI silicon wafer.
8. The pressure sensor according to claim 1, characterized in that, The substrate is a CSOI silicon wafer, and the CSOI silicon wafer includes a substrate, a thermal oxidation bonding layer, and a second top silicon layer arranged in sequence along the first direction; Wherein, the substrate is a SOI silicon wafer, and the SOI silicon wafer includes a bottom silicon layer, a buried oxide layer, and a first top silicon layer; or, the substrate is a silicon substrate.
9. The pressure sensor according to claim 8, wherein, When the substrate is a SOI silicon wafer, the first cavity is provided on a surface of the first top silicon layer near the second top silicon layer; the second cavity is provided on a surface of the bottom silicon layer facing away from the first top silicon layer; the pressure sensing diaphragm is the first top silicon layer between the first cavity and the second cavity; When the substrate is a silicon substrate, the first cavity is provided on a surface of the silicon substrate near the second top silicon layer; the second cavity is provided on a surface of the silicon substrate facing away from the second top silicon layer; the pressure sensing diaphragm is the silicon substrate between the first cavity and the second cavity.
10. The pressure sensor according to claim 9, characterized in that, An insulating layer is provided between the second top silicon layer of the CSOI silicon wafer and the bottom electrode.
11. The pressure sensor according to claim 1, wherein The working mode of the resonator is a bending vibration mode.
12. The pressure sensor according to any one of claims 1 to 11, characterized in that, The pressure sensor further includes a silicon cap, and the silicon cap is bonded to the resonator.
13. The pressure sensor according to claim 12, characterized in that, A vacuum third cavity is provided between the silicon cap and the resonator. The third cavity is provided in the silicon cap, and the third cavity is communicated with the first cavity and the vacuum degree is lower than 50 Pa.
14. The pressure sensor according to claim 13, characterized in that, At least an getter layer is provided at the bottom of the third cavity.
15. The pressure sensor according to claim 12, wherein The silicon cap includes a substrate and a conductive structure. The conductive structure penetrates through the substrate and is connected to the resonator to lead out the signal of the resonator to the side of the silicon cap facing away from the resonator.
16. The pressure sensor according to claim 15, wherein An insulating layer is provided between the conductive structure and the substrate.
17. The pressure sensor according to claim 13, wherein, In the first direction, the silicon cap covers the resonant region of the resonator, the region where the third cavity is located is covered by the region where the second cavity is located, and the region where the third cavity is located is greater than or equal to the region where the first cavity is located; Or In the first direction, the silicon cap covers the region where the pressure sensing diaphragm is located, and the region where the third cavity is located is greater than or equal to the region where the second cavity is located.
18. The pressure sensor according to claim 12, wherein, The silicon cap is bonded to the resonator through a bonding layer, and the bonding layer is a metal layer.
19. A manufacturing method of a piezoelectrically actuated resonant MEMS pressure sensor as claimed in claim 1, characterized in that, The method includes: Forming a substrate and forming a first cavity on a first surface of the substrate; Forming a bottom electrode, the bottom electrode being disposed on the first surface of the substrate; Forming a piezoelectric layer, the piezoelectric layer being disposed on a surface of the bottom electrode facing away from the substrate; Forming a top electrode, the top electrode being disposed on a surface of the piezoelectric layer facing away from the bottom electrode; Forming a second cavity on a second surface of the substrate opposite to the first surface to form a pressure sensing diaphragm between the first cavity and the second cavity.
20. An electrical product, characterized in that, The electrical product includes the piezoelectric drive resonant MEMS pressure sensor according to any one of claims 1 to 18.