Resonant pressure sensor and preparation method thereof

Abstract

The invention relates to the technical field of MEMS microsensors, and discloses a resonant pressure sensor and a preparation method thereof, the resonant pressure sensor comprises a substrate layer and a resonant assembly, the substrate layer comprises a support substrate and a pressure sensitive film; the supporting substrate is located at the side part of the pressure sensitive film; the resonance assembly comprises a first resonance beam and a second resonance beam which are arranged in parallel, two ends of the first resonance beam are connected with the pressure sensitive film through a first anchor area and a second anchor area, and two ends of the second resonance beam are connected with the pressure sensitive film through a third anchor area and a fourth anchor area; the first resonant beam and the second resonant beam are coupled and connected together through the mass block and the spring; the resonance assembly further comprises a first driving electrode unit and a second driving electrode unit. The first driving electrode unit is positioned on one side of the first resonant beam; the second driving electrode unit is located on one side of the second resonant beam. Compared with the prior art, the detection sensitivity, precision and reliability of the sensor can be improved, the Q value is improved, and the measuring range of the sensor is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of MEMS microsensors, and in particular to a resonant pressure sensor and a preparation method thereof. Background Art

[0002] A resonant pressure sensor is a MEMS (micro-electromechanical system) device that indirectly measures pressure by detecting changes in the natural frequency of a resonator. It has the characteristics of high precision and good anti-interference performance. Its output frequency signal is a quasi-digital signal, which can be easily connected to digital interfaces such as computers and circuits to form a high-precision detection system. It is very suitable for complex environments such as aerospace, meteorological monitoring, and oil exploration that have higher requirements on sensor accuracy and other performance. It has broad development potential in both military and civilian fields.

[0003] According to the excitation method and detection method, MEMS resonant pressure sensors can be divided into several categories, including electrostatic excitation / capacitive detection, electrostatic excitation / piezoresistive detection, electromagnetic excitation / electromagnetic detection, piezoelectric excitation / piezoelectric detection, optical excitation / optical detection, etc. Among them, MEMS resonant pressure sensors with electrostatic excitation / capacitive detection have the advantages of simple structure, low cost, easy processing and miniaturization, but the capacitance of MEMS processed devices is often small, the signal extracted by the circuit is relatively weak, and detection is more difficult. At the same time, MEMS resonant pressure sensors often have a small range, and a large range usually requires a trade-off in sensitivity. In addition, resonant pressure sensors are easily affected by temperature, and external temperature sensors are prone to temperature errors, resulting in low compensation accuracy. Integrated temperature sensors can improve the errors of external temperature sensors, but due to the introduction of temperature-sensitive components, the complexity of sensor processing is increased. Summary of the invention

[0004] In view of this, the present invention provides a resonant pressure sensor and a preparation method thereof to solve the problems in the related art that the resonant pressure sensor of electrostatic excitation / capacitive detection has a small capacitance, resulting in a relatively weak signal extracted by the circuit and difficult detection, and an external temperature sensor has a large error, low compensation accuracy and a relatively complex process.

[0005] In a first aspect, the present invention provides a resonant pressure sensor, the resonant pressure sensor comprising:

[0006] A substrate layer, the substrate layer includes a supporting substrate and a pressure sensitive film; the supporting substrate is located on the side of the pressure sensitive film;

[0007] The resonant component is located on one side of the substrate layer; the resonant component includes a first resonant beam and a second resonant beam arranged in parallel, the two ends of the first resonant beam are connected to the pressure-sensitive membrane through a first anchor area and a second anchor area, and the two ends of the second resonant beam are connected to the pressure-sensitive membrane through a third anchor area and a fourth anchor area; the first resonant beam and the second resonant beam are connected together through a mass block and a spring coupling; the resonant component also includes a first driving electrode unit and a second driving electrode unit; the first driving electrode unit is located on the side of the first resonant beam that is away from the second resonant beam; the second driving electrode unit is located on the side of the second resonant beam that is away from the first resonant beam.

[0008] The resonant pressure sensor provided by the present invention, first, by setting the first resonant beam and the second resonant beam, the double resonant beam can be made to vibrate in the opposite direction, so that the detection electrode can simultaneously detect the vibration displacement of the double resonant beam to enhance the detection capacitance signal, thereby improving the detection sensitivity and accuracy of the sensor; second, by setting the spring and the mass block to couple the first resonant beam and the second resonant beam together to form an integral coupling beam, the tolerance of the sensor to process errors, uneven force, environmental interference and other problems can be improved, thereby improving the reliability of the sensor, and at the same time, the interference of different modes can be improved and the Q value can be improved; third, by setting the first anchor area, the second anchor area, the third anchor area and the fourth anchor area, four silicon island force transmission structures are formed, which can improve the pressure distribution, reduce the root stress of each silicon island, improve the bearing capacity of the sensor, enable the sensor to withstand greater stress, and then improve the range of the sensor. Therefore, the resonant pressure sensor provided by the present invention can improve the detection sensitivity, accuracy and reliability of the sensor, and can also improve the Q value and increase the range of the muscle sensor.

[0009] In an optional embodiment, the material of the substrate layer is silicon;

[0010] The material of the resonant component is silicon;

[0011] The resonant pressure sensor also includes a silicon dioxide layer located between the resonant component and the substrate layer;

[0012] The silicon dioxide layer is provided with a first groove and a second groove at positions corresponding to the first resonance beam and the second resonance beam, respectively. The first groove and the second groove penetrate the silicon dioxide layer and expose the surface of the pressure sensitive film. The first resonance beam and the second resonance beam are suspended on one side of the pressure sensitive film.

[0013] The resonant pressure sensor provided by the present invention can make the first resonant beam and the second resonant beam suspended on one side of the pressure sensitive film by respectively arranging the first groove and the second groove at the positions of the silicon dioxide layer corresponding to the first resonant beam and the second resonant beam, so that the first resonant beam and the second resonant beam can vibrate according to the pressure transmitted by the first anchor area, the second anchor area, the third anchor area and the fourth anchor area, thereby improving the detection sensitivity and accuracy of the sensor.

[0014] In an optional embodiment, the first anchor region, the second anchor region, the third anchor region and the fourth anchor region are connected to the pressure sensitive membrane through a silicon dioxide layer; the first anchor region, the second anchor region, the third anchor region and the fourth anchor region are suitable for transmitting the pressure exerted on the pressure sensitive membrane to the first resonant beam and the second resonant beam.

[0015] In an optional implementation, the first driving electrode unit includes a first driving electrode and a first transmission electrode that are perpendicular to each other; the second driving electrode unit includes a second driving electrode and a second transmission electrode that are perpendicular to each other;

[0016] The first driving electrode and the second driving electrode are parallel to the first resonant beam;

[0017] The first driving electrode unit and the second driving electrode unit are connected to the pressure sensitive film through the silicon dioxide layer.

[0018] The resonant pressure sensor provided by the present invention can drive the first resonant beam and the second resonant beam to vibrate in response to the pressure change of the pressure sensitive membrane by means of a first driving electrode and a second driving electrode which are arranged in parallel with the first resonant beam / the second resonant beam, and can enhance the detection capacitance signal by simultaneously detecting the vibration displacement of the dual resonant beams through the detection electrodes, thereby improving the detection sensitivity and accuracy of the sensor.

[0019] In an optional embodiment, the resonance component further includes a detection electrode, which is located between the first resonance beam and the second resonance beam and on the side of the mass block and the spring;

[0020] The detection electrode is connected to the pressure sensitive membrane through a silicon dioxide layer.

[0021] In an optional implementation, the mass block includes a first mass block and a second mass block, the first mass block is located on a side of the first resonant beam facing the second resonant beam, and the second mass block is located on a side of the second resonant beam facing the first resonant beam;

[0022] The first mass block and the second mass block are connected via a spring;

[0023] The resonant frequency of the first resonant beam is the same as the resonant frequency of the second resonant beam.

[0024] In the resonant pressure sensor provided by the present invention, the first mass block and the second mass block are connected by a spring, and then the first resonant beam and the second resonant beam are coupled together to form an integral coupling beam. The coupling beam includes the first resonant beam, the first mass block, the spring, the second mass block and the second resonant beam, which can improve the sensor's tolerance to process errors, uneven force, environmental interference and other problems, thereby improving the reliability of the sensor, and can also improve the interference of different modes and improve the Q value.

[0025] In an optional implementation, the resonant pressure sensor further includes:

[0026] A cover layer, located on a surface of the resonant component facing away from the substrate layer;

[0027] The temperature sensor is located on one side of the temperature sensor substrate and embedded in the third groove of the temperature sensor substrate; the temperature sensor substrate is arranged in the same layer as the resonance component and is located on the side of the resonance component; the temperature sensor includes a serpentine resistor and a third transmission electrode.

[0028] The resonant pressure sensor provided by the present invention embeds a temperature sensor on a temperature sensor substrate on the side of the resonant component and integrates the temperature sensor inside the frame of the resonant component, so that the temperature sensor resonant components are located at the same level and very close to each other, which can reduce temperature errors, improve the accuracy of temperature measurement, and thus improve the reliability and detection accuracy of the sensor.

[0029] In an optional embodiment, the cover layer includes a cavity, an air-absorbing agent and a plurality of through holes; the through holes are located at positions of the cover layer corresponding to the first transmission electrode, the second transmission electrode and the third transmission electrode, and are respectively filled with the first lead-out electrode, the second lead-out electrode and the third lead-out electrode, and are respectively connected to the first transmission electrode, the second transmission electrode and the third transmission electrode; the cavity corresponds to the pressure sensitive film; and the air-absorbing agent is arranged on the inner wall of the cavity.

[0030] In a second aspect, the present invention provides a method for preparing a resonant pressure sensor, which is used to prepare the resonant pressure sensor of the first aspect, and the preparation method comprises:

[0031] forming a substrate layer, the substrate layer comprising a supporting substrate and a pressure sensitive film; the supporting substrate is located on a side of the pressure sensitive film;

[0032] A resonance component is formed on one side of the substrate layer; the resonance component includes a first resonance beam and a second resonance beam arranged in parallel, two ends of the first resonance beam are connected to the pressure sensitive membrane through a first anchor area and a second anchor area, and two ends of the second resonance beam are connected to the pressure sensitive membrane through a third anchor area and a fourth anchor area; the first resonance beam and the second resonance beam are connected together through a mass block and a spring coupling; the resonance component also includes a first drive electrode unit and a second drive electrode unit; the first drive electrode unit is located on the side of the first resonance beam that is away from the second resonance beam; the second drive electrode unit is located on the side of the second resonance beam that is away from the first resonance beam.

[0033] The preparation method of the resonant pressure sensor provided by the present invention, first, by forming a first resonant beam and a second resonant beam, the double resonant beam can be made to vibrate in the opposite direction, so that the detection electrode can simultaneously detect the vibration displacement of the double resonant beam to enhance the detection capacitance signal, thereby improving the detection sensitivity and accuracy of the sensor; second, by forming a spring and a mass block to couple the first resonant beam and the second resonant beam together to form an integral coupling beam, the tolerance of the sensor to process errors, uneven force, environmental interference and other problems can be improved, thereby improving the reliability of the sensor, and at the same time, the interference of different modes can be improved and the Q value can be increased; third, by forming a first anchor area, a second anchor area, a third anchor area and a fourth anchor area, four silicon island force transmission structures are formed, which can improve the pressure distribution, reduce the root stress of each silicon island, improve the bearing capacity of the sensor, enable the sensor to withstand greater stress, and then increase the range of the sensor. Therefore, the resonant pressure sensor prepared by the preparation method of the resonant pressure sensor provided by the present invention can improve the detection sensitivity, accuracy and reliability of the sensor, and can also improve the Q value and increase the range of the sensor.

[0034] In an optional embodiment, the step of forming the substrate layer includes:

[0035] Providing an SOI substrate, the SOI substrate comprising a first silicon layer, a silicon dioxide layer, and a second silicon layer;

[0036] A fourth groove is formed on a side of the first silicon layer facing away from the silicon dioxide layer; the fourth groove penetrates a portion of the first silicon layer, and a portion of the first silicon layer that is not penetrated forms a pressure sensitive film; the first silicon layer on the side of the pressure sensitive film forms a supporting substrate; the pressure sensitive film and the supporting substrate constitute a substrate layer;

[0037] The step of forming a resonant component on one side of the substrate layer comprises:

[0038] A resonant component is formed in the second silicon layer.

[0039] The preparation method of the resonant pressure sensor provided by the present invention uses the first silicon layer of an SOI (silicon on insulating substrate) substrate to form a pressure sensitive film and a supporting substrate, and uses the second silicon layer to form a resonant component, which can simplify the preparation process of the sensor and improve the process efficiency.

[0040] In an optional embodiment, the second silicon layer includes a temperature sensor substrate located on a side of the resonant component;

[0041] Before the step of forming a resonant component in the second silicon layer, the method further includes:

[0042] forming a third recess in the temperature sensor substrate;

[0043] A metal or a conductive medium is deposited in the third groove to form a temperature sensor.

[0044] The resonant pressure sensor provided by the present invention, on the one hand, utilizes the second silicon layer of the SOI substrate to form a resonant component and a temperature sensor on its side, so that the temperature sensor can be integrated inside the device without introducing an additional bonding layer, does not affect the cover plate packaging process, and has a simple process flow; on the other hand, by embedding the temperature sensor on the temperature sensor substrate on the side of the resonant component and integrating the temperature sensor inside the frame of the resonant component, the temperature sensor resonant component is located at the same level and very close to each other, which can reduce temperature errors, improve the accuracy of temperature measurement, and thereby improve the reliability and detection accuracy of the sensor.

[0045] In an optional implementation manner, after the step of forming a resonant component in the second silicon layer, the method further includes:

[0046] A first groove and a second groove are formed at positions of the silicon dioxide layer corresponding to the first resonance beam and the second resonance beam respectively; the first groove and the second groove penetrate the silicon dioxide layer and expose the surface of the pressure sensitive film; the first resonance beam and the second resonance beam are suspended on one side of the pressure sensitive film. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the related technologies, the drawings required for use in the specific embodiments or the related technical descriptions will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0048] Figure 1 4 is a schematic top view of a resonant component in a resonant pressure sensor according to an embodiment of the present invention.

[0049] Figure 2 is a schematic structural diagram of a resonant pressure sensor according to an embodiment of the present invention.

[0050] Figure 3 Schematic diagram of the working principle of a resonant pressure sensor according to an embodiment of the present invention.

[0051] Figure 4 4 is a schematic structural diagram of a cover layer of a resonant pressure sensor according to an embodiment of the present invention.

[0052] Figure 5 It is a schematic flow chart of a method for preparing a resonant pressure sensor according to an embodiment of the present invention.

[0053] Figure 6 It is a schematic diagram of a specific process of a method for preparing a resonant pressure sensor according to an embodiment of the present invention.

[0054] Figure 7 It is a structural schematic diagram of forming a pressure sensitive film in a method for preparing a resonant pressure sensor according to an embodiment of the present invention.

[0055] Figure 8 In a method for preparing a resonant pressure sensor according to an embodiment of the present invention, Figure 7 A schematic structural diagram of a first patterned photoresist layer formed on the basis.

[0056] Fig. 9 In a method for preparing a resonant pressure sensor according to an embodiment of the present invention, Figure 8 Schematic diagram of the structure of forming a third groove on the basis.

[0057] Fig.10 In a method for preparing a resonant pressure sensor according to an embodiment of the present invention, Fig. 9 The structural schematic diagram of the temperature sensor is formed on this basis.

[0058] Fig.11 In a method for preparing a resonant pressure sensor according to an embodiment of the present invention, Fig.10 A schematic structural diagram of a second patterned photoresist layer formed on the basis.

[0059] Fig.12 In a method for preparing a resonant pressure sensor according to an embodiment of the present invention, Fig.11 A schematic diagram of the structure of a resonant component is formed on this basis.

[0060] Fig.13 In a method for preparing a resonant pressure sensor according to an embodiment of the present invention, Fig.12 A schematic diagram of a structure in which a first groove and a second groove are formed on the basis.

[0061] Fig.14 In a method for preparing a resonant pressure sensor according to an embodiment of the present invention, Fig.13 Schematic diagram of the structure of the cover layer formed on the foundation.

[0062] Fig.15 In a method for preparing a resonant pressure sensor according to an embodiment of the present invention, Fig.14 Schematic diagram of the structure of the lead-out electrode formed on the basis.

[0063] Reference numerals:

[0064] 10. substrate layer; 11. supporting substrate; 12. pressure sensitive film; 13. silicon dioxide layer; 14. second silicon layer; 20. resonant component; 211. first resonant beam; 212. second resonant beam; 221. first anchor area; 222. second anchor area; 223. third anchor area; 224. fourth anchor area; 231. first mass block; 232. second mass block; 24. spring; 25. first drive electrode unit; 251. first drive electrode; 26. second drive electrode unit; 261. second drive electrode; 27. detection electrode; 30. cover layer; 31. cavity; 32. getter; 33. through hole; 40. temperature sensor; 51. first patterned photoresist layer; 52. second patterned photoresist layer. DETAILED DESCRIPTION

[0065] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0066] In the following description, the description of known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention. Various structural schematic diagrams according to embodiments of the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified for the purpose of clear expression, and some details may be omitted. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships between them are only exemplary, and may be deviated due to manufacturing tolerances or technical limitations in practice, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs. In the context of the present invention, when a layer / element is referred to as being "on" another layer / element, the layer / element may be directly on the other layer / element, or there may be a middle layer / element between them. In addition, if a layer / element is "on" another layer / element in one orientation, then when the orientation is reversed, the layer / element may be "under" the other layer / element.

[0067] A resonant pressure sensor is a MEMS (micro-electromechanical system) device that indirectly measures pressure by detecting changes in the natural frequency of a resonator. It has the characteristics of high precision and good anti-interference performance. Its output frequency signal is a quasi-digital signal, which can be easily connected to digital interfaces such as computers and circuits to form a high-precision detection system. It is very suitable for complex environments such as aerospace, meteorological monitoring, and oil exploration that have higher requirements on sensor accuracy and other performance. It has broad development potential in both military and civilian fields.

[0068] According to the excitation method and detection method, MEMS resonant pressure sensors can be divided into several categories, including electrostatic excitation / capacitive detection, electrostatic excitation / piezoresistive detection, electromagnetic excitation / electromagnetic detection, piezoelectric excitation / piezoelectric detection, optical excitation / optical detection, etc. Among them, MEMS resonant pressure sensors with electrostatic excitation / capacitive detection have the advantages of simple structure, low cost, easy processing and miniaturization, but the capacitance of MEMS processed devices is often small, the signal extracted by the circuit is relatively weak, and detection is more difficult. At the same time, MEMS resonant pressure sensors often have a small range, and a large range usually requires a trade-off in sensitivity. In addition, resonant pressure sensors are easily affected by temperature, and external temperature sensors are prone to temperature errors, resulting in low compensation accuracy. Integrated temperature sensors can improve the errors of external temperature sensors, but due to the introduction of temperature-sensitive components, the complexity of sensor processing is increased.

[0069] like Figure 1 and Figure 2 As shown, this embodiment provides a resonant pressure sensor, and the resonant pressure sensor includes:

[0070] The substrate layer 10 includes a supporting substrate 11 and a pressure sensitive film 12; the supporting substrate 11 is located on the side of the pressure sensitive film 12;

[0071] The resonance component 20 is located on one side of the substrate layer 10; the resonance component 20 includes a first resonance beam 211 and a second resonance beam 212 arranged in parallel, both ends of the first resonance beam 211 are connected to the pressure sensitive film 12 through a first anchor area 221 and a second anchor area 222, and both ends of the second resonance beam 212 are connected to the pressure sensitive film 12 through a third anchor area 223 and a fourth anchor area 224; the first resonance beam 211 and the second resonance beam 212 are coupled and connected together through a mass block and a spring 24; the resonance component 20 also includes a first driving electrode unit 25 and a second driving electrode unit 26; the first driving electrode unit 25 is located on the side of the first resonance beam 211 facing away from the second resonance beam 212; the second driving electrode unit 26 is located on the side of the second resonance beam 212 facing away from the first resonance beam 211.

[0072] In a specific implementation, the first resonant beam 211 and the second resonant beam 212 are coupled together through the mass block and the spring 24 to form a coupling beam. The coupling beam includes the first resonant beam 211, the mass block, the spring 24 and the second resonant beam 212. Figure 1 shown.

[0073] The resonant pressure sensor is an electrostatic excitation / capacitive detection mode. The first anchor area, the second anchor area, the third anchor area and the fourth anchor area are used to transmit the pressure on the pressure sensitive film. The four anchor areas convert the pressure on the pressure sensitive film into a small displacement to force the resonant beam, thereby changing the resonant frequency of the two resonant beams, and then controlling the resonant frequency of the entire coupling beam. Figure 3 shown.

[0074] The resonant pressure sensor provided in this embodiment, first, by setting the first resonant beam and the second resonant beam, the dual resonant beam can be made to vibrate in the opposite direction, so that the detection electrode can simultaneously detect the vibration displacement of the dual resonant beam to enhance the detection capacitance signal, thereby improving the detection sensitivity and accuracy of the sensor; second, by setting the spring and the mass block to couple the first resonant beam and the second resonant beam together to form an integral coupling beam, the tolerance of the sensor to process errors, uneven force, environmental interference and other problems can be improved, thereby improving the reliability of the sensor, and at the same time, the interference of different modes can be improved and the Q value can be increased; third, by setting the first anchor area, the second anchor area, the third anchor area and the fourth anchor area, four silicon island force transmission structures are formed, which can improve the pressure distribution, reduce the root stress of each silicon island, improve the bearing capacity of the sensor, enable the sensor to withstand greater stress, and then increase the range of the sensor. Therefore, the resonant pressure sensor provided in this embodiment can improve the detection sensitivity, accuracy and reliability of the sensor, and can also improve the Q value and increase the range of the sensor.

[0075] In an optional embodiment, the material of the substrate layer 10 is silicon;

[0076] The material of the resonant component 20 is silicon;

[0077] The resonant pressure sensor further includes a silicon dioxide layer 13 located between the resonant component 20 and the substrate layer 10;

[0078] The silicon dioxide layer 13 is provided with a first groove and a second groove at positions corresponding to the first resonance beam 211 and the second resonance beam 212 , respectively. The first groove and the second groove penetrate the silicon dioxide layer 13 and expose the surface of the pressure sensitive film 12 ; the first resonance beam 211 and the second resonance beam 212 are suspended on one side of the pressure sensitive film 12 .

[0079] The resonant pressure sensor provided in this embodiment can make the first resonant beam and the second resonant beam suspended on one side of the pressure sensitive membrane by respectively setting the first groove and the second groove at the positions of the silicon dioxide layer corresponding to the first resonant beam and the second resonant beam, so that the first resonant beam and the second resonant beam can vibrate according to the pressure transmitted by the first anchor area, the second anchor area, the third anchor area and the fourth anchor area, thereby improving the detection sensitivity and accuracy of the sensor.

[0080] In an optional embodiment, the first anchor region 221, the second anchor region 222, the third anchor region 223 and the fourth anchor region 224 are connected to the pressure sensitive membrane 12 through the silicon dioxide layer 13; the first anchor region 221, the second anchor region 222, the third anchor region 223 and the fourth anchor region 224 are suitable for transmitting the pressure exerted on the pressure sensitive membrane 12 to the first resonant beam 211 and the second resonant beam 212.

[0081] In an optional embodiment, the first driving electrode unit 25 includes a first driving electrode 251 and a first transmission electrode that are perpendicular to each other; the second driving electrode unit 26 includes a second driving electrode 261 and a second transmission electrode that are perpendicular to each other;

[0082] The first driving electrode 251 and the second driving electrode 261 are parallel to the first resonance beam 211;

[0083] The first driving electrode unit 25 and the second driving electrode unit 26 are connected to the pressure sensitive film 12 through the silicon dioxide layer 13 .

[0084] The resonant pressure sensor provided in this embodiment is provided with a first driving electrode and a second driving electrode parallel to the first resonant beam / the second resonant beam, which can drive the first resonant beam and the second resonant beam to generate vibrations to respond to pressure changes of the pressure sensitive membrane, and enhance the detection capacitance signal by simultaneously detecting the vibration displacement of the dual resonant beams through the detection electrodes, thereby improving the detection sensitivity and accuracy of the sensor.

[0085] In an optional embodiment, the resonance component 20 further includes a detection electrode 27, which is located between the first resonance beam 211 and the second resonance beam 212 and on the side of the mass block and the spring 24;

[0086] The detection electrode 27 is connected to the pressure sensitive film 12 through the silicon dioxide layer 13 .

[0087] In an optional embodiment, the mass block includes a first mass block 231 and a second mass block 232, the first mass block 231 is located on the side of the first resonant beam 211 facing the second resonant beam 212, and the second mass block 232 is located on the side of the second resonant beam 212 facing the first resonant beam 211;

[0088] The first mass block 231 and the second mass block 232 are connected via a spring 24;

[0089] The resonance frequency of the first resonance beam 211 and the resonance frequency of the second resonance beam 212 are the same.

[0090] In the resonant pressure sensor provided in this embodiment, the first mass block and the second mass block are connected by a spring, and then the first resonant beam and the second resonant beam are coupled together to form an overall coupling beam. The coupling beam includes the first resonant beam, the first mass block, the spring, the second mass block and the second resonant beam, which can improve the sensor's tolerance to process errors, uneven force, environmental interference and other problems, thereby improving the reliability of the sensor, and can also improve the interference of different modes and improve the Q value.

[0091] In an optional implementation, the resonant pressure sensor further includes:

[0092] The cover layer 30 is located on a surface of the resonant component 20 facing away from the substrate layer 10;

[0093] The temperature sensor 40 is located on one side of the temperature sensor substrate and embedded in the third groove of the temperature sensor substrate; the temperature sensor substrate is arranged in the same layer as the resonance component 20 and is located on the side of the resonance component 20; the temperature sensor 40 includes a serpentine resistor and a third transmission electrode.

[0094] The resonant pressure sensor provided in this embodiment embeds a temperature sensor on the temperature sensor substrate on the side of the resonant component and integrates the temperature sensor inside the frame of the resonant component, so that the temperature sensor resonant components are located at the same level and very close to each other, which can reduce temperature errors and improve the accuracy of temperature measurement, thereby improving the reliability and detection accuracy of the sensor.

[0095] In an optional embodiment, if Figure 4 As shown, the cover layer 30 includes a cavity 31, a getter 32 and a plurality of through holes 33; the through holes 33 are located at positions of the cover layer corresponding to the first transmission electrode, the second transmission electrode and the third transmission electrode, and are respectively filled with the first lead-out electrode, the second lead-out electrode and the third lead-out electrode, and are respectively connected to the first transmission electrode, the second transmission electrode and the third transmission electrode; the cavity corresponds to the pressure sensitive film; the getter is arranged on the inner wall of the cavity.

[0096] like Figure 5 As shown, this embodiment provides a method for preparing a resonant pressure sensor, and the method includes but is not limited to steps S101 to S102.

[0097] Step S101, forming a substrate layer, the substrate layer comprising a supporting substrate and a pressure sensitive membrane; the supporting substrate is located on the side of the pressure sensitive membrane;

[0098] Step S102, forming a resonance component on one side of the substrate layer; the resonance component includes a first resonance beam and a second resonance beam arranged in parallel, two ends of the first resonance beam are connected to the pressure sensitive membrane through a first anchor area and a second anchor area, and two ends of the second resonance beam are connected to the pressure sensitive membrane through a third anchor area and a fourth anchor area; the first resonance beam and the second resonance beam are connected together through a mass block and a spring coupling; the resonance component also includes a first drive electrode unit and a second drive electrode unit; the first drive electrode unit is located on the side of the first resonance beam facing away from the second resonance beam; the second drive electrode unit is located on the side of the second resonance beam facing away from the first resonance beam.

[0099] In an optional embodiment, the step of forming the substrate layer includes:

[0100] Providing an SOI substrate, the SOI substrate comprising a first silicon layer, a silicon dioxide layer, and a second silicon layer;

[0101] A fourth groove is formed on a side of the first silicon layer facing away from the silicon dioxide layer; the fourth groove penetrates a portion of the first silicon layer, and a portion of the first silicon layer that is not penetrated forms a pressure sensitive film; the first silicon layer on the side of the pressure sensitive film forms a supporting substrate; the pressure sensitive film and the supporting substrate constitute a substrate layer;

[0102] The step of forming a resonant component on one side of the substrate layer comprises:

[0103] A resonant component is formed in the second silicon layer.

[0104] The preparation method of the resonant pressure sensor provided in this embodiment uses the first silicon layer of the SOI (silicon on insulating substrate) substrate to form a pressure sensitive film and a supporting substrate, and uses the second silicon layer to form a resonant component, which can simplify the preparation process of the sensor and improve the process efficiency.

[0105] In an optional embodiment, the second silicon layer includes a temperature sensor substrate located on a side of the resonant component;

[0106] Before the step of forming a resonant component in the second silicon layer, the method further includes:

[0107] forming a third recess in the temperature sensor substrate;

[0108] A metal or a conductive medium is deposited in the third groove to form a temperature sensor.

[0109] The resonant pressure sensor provided in this embodiment, on the one hand, utilizes the second silicon layer of the SOI substrate to form a resonant component and a temperature sensor on its side, so that the temperature sensor can be integrated inside the device without introducing an additional bonding layer, does not affect the cover packaging process, and has a simple process flow; on the other hand, by embedding the temperature sensor on the temperature sensor substrate on the side of the resonant component and integrating the temperature sensor inside the frame of the resonant component, the temperature sensor resonant component is located at the same level and very close to each other, which can reduce temperature errors, improve the accuracy of temperature measurement, and thereby improve the reliability and detection accuracy of the sensor.

[0110] In an optional implementation manner, after the step of forming a resonant component in the second silicon layer, the method further includes:

[0111] A first groove and a second groove are formed at positions of the silicon dioxide layer corresponding to the first resonance beam and the second resonance beam respectively; the first groove and the second groove penetrate the silicon dioxide layer and expose the surface of the pressure sensitive film; the first resonance beam and the second resonance beam are suspended on one side of the pressure sensitive film.

[0112] In an optional embodiment, the first driving electrode unit 25 includes a first driving electrode 251 and a first transmission electrode that are perpendicular to each other; the second driving electrode unit 26 includes a second driving electrode 261 and a second transmission electrode that are perpendicular to each other; the first driving electrode and the second driving electrode are parallel to the first resonant beam 211; the temperature sensor 40 includes a serpentine resistor and a third transmission electrode; and the detection electrode 27 also includes a fourth transmission electrode.

[0113] In an optional embodiment, after the step of forming the first groove and the second groove at the positions of the silicon dioxide layer corresponding to the first resonant beam and the second resonant beam respectively, the method further includes:

[0114] A cover layer 30 is formed on a surface of the resonant component 20 facing away from the substrate layer 10; the cover layer includes a cavity 31, a getter 32 and a plurality of through holes 33; the through holes 33 are located at positions of the cover layer corresponding to the first transmission electrode, the second transmission electrode, the third transmission electrode and the fourth transmission electrode;

[0115] A metal or conductor medium is filled in a plurality of through holes to form a first lead-out electrode, a second lead-out electrode, a third lead-out electrode and a fourth lead-out electrode, which are respectively connected to the first transmission electrode, the second transmission electrode, the third transmission electrode and the fourth transmission electrode; the cavity corresponds to the pressure sensitive film; and the getter is arranged on the inner wall of the cavity.

[0116] like Figure 6 As shown, the present invention also provides a specific flow diagram of a method for preparing a resonant pressure sensor, comprising the following steps:

[0117] Step S201 , providing an SOI substrate, wherein the SOI substrate includes a first silicon layer, a silicon dioxide layer 13 and a second silicon layer 14 .

[0118] Step S202, forming a fourth groove on the side of the first silicon layer facing away from the silicon dioxide layer 13; the fourth groove penetrates part of the first silicon layer, and the part of the first silicon layer that is not penetrated forms a pressure sensitive film 12; the first silicon layer on the side of the pressure sensitive film forms a supporting substrate 11; the pressure sensitive film 12 and the supporting substrate 11 constitute a substrate layer 10, such as Figure 7 shown.

[0119] Step S203, forming a third groove in the temperature sensor substrate on the side of the second silicon layer 14; depositing metal or conductor medium in the third groove to form a temperature sensor 40, the temperature sensor 40 includes a serpentine resistor and a third transmission electrode.

[0120] In a specific implementation, a first patterned photoresist layer 51 is first formed on the surface of the second silicon layer 14 facing away from the silicon dioxide layer 13. Figure 8 Then the temperature sensor substrate on the side of the second silicon layer 14 is etched to form a third groove, such as Fig. 9As shown, the third groove includes a serpentine groove and a third transmission electrode groove; finally, a metal or conductor medium is deposited in the third groove, and thinned to the height of the second silicon layer 14 by a CMP (chemical mechanical polishing) process; a temperature sensor 40 is formed, as shown in FIG. Fig.10 As shown, the temperature sensor 40 includes a serpentine resistor and a third transmission electrode.

[0121] Step S204, forming a resonance component 20 in the second silicon layer; the resonance component 20 includes a first resonance beam 211 and a second resonance beam 212 arranged in parallel, both ends of the first resonance beam 211 are connected to the pressure sensitive film 12 through a first anchor area 221 and a second anchor area 222, and both ends of the second resonance beam 212 are connected to the pressure sensitive film 12 through a third anchor area 223 and a fourth anchor area 224; the first resonance beam 211 and the second resonance beam 212 are coupled and connected together through a mass block and a spring 24; the resonance component 20 also includes a first driving electrode unit 25 and a second driving electrode unit 26; the first driving electrode unit 25 is located on the side of the first resonance beam 211 facing away from the second resonance beam 212; the second driving electrode unit 26 is located on the side of the second resonance beam 212 facing away from the first resonance beam 211; the resonance component 20 also includes a transmission electrode.

[0122] In a specific implementation, firstly, a second patterned photoresist layer 52 is formed on the surface of the second silicon layer 14 facing away from the silicon dioxide layer 13. Fig.11 Then, the silicon dioxide layer 13 is formed into a resonant component by deep reactive ion etching, as shown in FIG. Fig.12 shown.

[0123] The first driving electrode unit 25 includes a first driving electrode 251 and a first transmission electrode that are perpendicular to each other; the second driving electrode unit 26 includes a second driving electrode 261 and a second transmission electrode that are perpendicular to each other; the first driving electrode and the second driving electrode are parallel to the first resonant beam 211; the resonant component also includes a detection electrode 27; the detection electrode 27 also includes a fourth transmission electrode.

[0124] Step S205, forming a first groove and a second groove at positions of the silicon dioxide layer 13 corresponding to the first resonant beam 211 and the second resonant beam 212 respectively; the first groove and the second groove penetrate the silicon dioxide layer 13 and expose the surface of the pressure sensitive film 12; the first resonant beam 211 and the second resonant beam 212 are suspended on one side of the pressure sensitive film, such as Fig.13 shown.

[0125] In a specific implementation, the silicon dioxide layer 13 is etched by HF to release the resonance component, so that the first resonance beam 211 and the second resonance beam 212 are suspended on one side of the pressure sensitive film 12. Fig.13 shown.

[0126] Step S206, forming a cover layer 30 on the side surface of the resonant component 20 facing away from the substrate layer 10; the cover layer 30 includes a cavity 31, a getter 32 and a plurality of through holes 33; the cavity 31 corresponds to the pressure sensitive film 12; the getter 32 is arranged on the inner wall of the cavity 31; the plurality of through holes 33 are located at the transmission electrode position, such as Fig.14 shown.

[0127] In specific implementation, a cavity 31 is formed inside the cover layer 30 by etching and a getter 32 is deposited. The position of the cavity 31 corresponds to the pressure sensitive film 12. The second silicon layer 14 of the SOI substrate and the cover layer 30 are anodic bonded to realize vacuum packaging of the device. The through hole 33 is located at the position of the cover layer corresponding to the first transmission electrode, the second transmission electrode, the third transmission electrode and the fourth transmission electrode.

[0128] Step S207, depositing metal or conductor medium in the plurality of through holes 33 to form lead electrodes, such as Fig.15 shown.

[0129] In specific implementation, metal or conductor medium is filled in the plurality of through holes 33 to form the first extraction electrode, the second extraction electrode, the third extraction electrode and the fourth extraction electrode, which are respectively connected to the first transmission electrode, the second transmission electrode, the third transmission electrode and the fourth transmission electrode.

[0130] In one example, lead vias are made by TGV technology and metal is deposited to form electrodes.

[0131] In the description of this specification, the description with reference to the terms "this embodiment", "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples, unless otherwise clearly and specifically defined. In addition, the terms "first" and "second" are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" can explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0132] In the above description, the technical details of the patterning and etching of each layer are not described in detail. However, those skilled in the art should understand that various technical means can be used to form layers, regions, etc. of desired shapes. In addition, in order to form the same structure, those skilled in the art can also design methods that are not completely the same as the methods described above. In addition, although the various embodiments are described above separately, this does not mean that the measures in the various embodiments cannot be used in combination to advantage.

[0133] The above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described above, and that various obvious changes, readjustments, combinations and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention is described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may also include more other equivalent embodiments without departing from the concept of the present invention. The scope of protection of the present invention is determined by the scope of the attached claims.

Claims

1. A resonant pressure sensor, characterized in that: include: A substrate layer, the substrate layer comprising a supporting substrate and a pressure sensitive film; The support substrate is located on the side of the pressure sensitive film; A resonance component is located at one side of the substrate layer; the resonance component comprises a first resonance beam and a second resonance beam arranged in parallel, two ends of the first resonance beam are connected to the pressure sensitive film through a first anchor area and a second anchor area, and two ends of the second resonance beam are connected to the pressure sensitive film through a third anchor area and a fourth anchor area; the first resonance beam and the second resonance beam are connected together through a mass block and a spring coupling; the resonance component also comprises a first driving electrode unit and a second driving electrode unit; The first driving electrode unit is located at a side of the first resonance beam facing away from the second resonance beam; and the second driving electrode unit is located at a side of the second resonance beam facing away from the first resonance beam.

2. The resonant pressure sensor according to claim 1, characterized in that: The material of the substrate layer is silicon; The material of the resonant component is silicon; The resonant pressure sensor further includes a silicon dioxide layer located between the resonant component and the substrate layer; The silicon dioxide layer is provided with a first groove and a second groove at positions corresponding to the first resonance beam and the second resonance beam, respectively. The first groove and the second groove penetrate the silicon dioxide layer and expose the surface of the pressure sensitive film. The first resonance beam and the second resonance beam are suspended on one side of the pressure sensitive film.

3. The resonant pressure sensor according to claim 2, characterized in that: The first anchor region, the second anchor region, the third anchor region and the fourth anchor region are connected to the pressure sensitive film through the silicon dioxide layer; the first anchor region, the second anchor region, the third anchor region and the fourth anchor region are suitable for transmitting the pressure exerted on the pressure sensitive film to the first resonant beam and the second resonant beam.

4. The resonant pressure sensor according to claim 2, characterized in that: The first driving electrode unit includes a first driving electrode and a first transmission electrode that are perpendicular to each other; the second driving electrode unit includes a second driving electrode and a second transmission electrode that are perpendicular to each other; The first driving electrode and the second driving electrode are parallel to the first resonant beam; The first driving electrode unit and the second driving electrode unit are connected to the pressure sensitive film through the silicon dioxide layer.

5. The resonant pressure sensor according to claim 4, characterized in that: The resonant component further includes a detection electrode, the detection electrode being located between the first resonant beam and the second resonant beam and being located on the side of the mass block and the spring; The detection electrode is connected to the pressure sensitive film through the silicon dioxide layer.

6. The resonant pressure sensor according to claim 2, characterized in that: The mass block includes a first mass block and a second mass block, the first mass block is located on a side of the first resonance beam facing the second resonance beam, and the second mass block is located on a side of the second resonance beam facing the first resonance beam; The first mass block and the second mass block are connected via a spring; The resonance frequency of the first resonance beam is the same as the resonance frequency of the second resonance beam.

7. The resonant pressure sensor according to claim 4, characterized in that: The resonant pressure sensor further comprises: A cover layer, located on a surface of the resonant component facing away from the substrate layer; The temperature sensor is located on one side of the temperature sensor substrate and embedded in the third groove of the temperature sensor substrate; the temperature sensor substrate is arranged in the same layer as the resonance component and is located on the side of the resonance component; the temperature sensor includes a serpentine resistor and a third transmission electrode.

8. The resonant pressure sensor according to claim 7, characterized in that: The cover layer includes a cavity, a getter and a plurality of through holes; the through holes are located at positions of the cover layer corresponding to the first transmission electrode, the second transmission electrode and the third transmission electrode, are filled with the first lead-out electrode, the second lead-out electrode and the third lead-out electrode, respectively, and are connected to the first transmission electrode, the second transmission electrode and the third transmission electrode, respectively; the cavity corresponds to the pressure sensitive film; the getter is arranged on the inner wall of the cavity.

9. A method for preparing a resonant pressure sensor, used for preparing the resonant pressure sensor as claimed in claim 1, characterized in that: forming a substrate layer, the substrate layer comprising a supporting substrate and a pressure sensitive film; the supporting substrate is located at a side of the pressure sensitive film; A resonance component is formed on one side of the substrate layer; the resonance component comprises a first resonance beam and a second resonance beam arranged in parallel, two ends of the first resonance beam are connected to the pressure sensitive film through a first anchor region and a second anchor region, and two ends of the second resonance beam are connected to the pressure sensitive film through a third anchor region and a fourth anchor region; the first resonance beam and the second resonance beam are connected together through a mass block and a spring coupling; the resonance component also comprises a first driving electrode unit and a second driving electrode unit; The first driving electrode unit is located at a side of the first resonance beam facing away from the second resonance beam; and the second driving electrode unit is located at a side of the second resonance beam facing away from the first resonance beam.

10. The method for preparing a resonant pressure sensor according to claim 9, characterized in that: The step of forming the substrate layer comprises: Providing an SOI substrate, the SOI substrate comprising a first silicon layer, a silicon dioxide layer, and a second silicon layer; A fourth groove is formed on a side of the first silicon layer facing away from the silicon dioxide layer; the fourth groove penetrates a portion of the first silicon layer, and a portion of the first silicon layer that is not penetrated forms a pressure sensitive film; the first silicon layer on the side of the pressure sensitive film forms a supporting substrate; the pressure sensitive film and the supporting substrate constitute the substrate layer; The step of forming a resonant component on one side of the substrate layer comprises: The resonant component is formed in the second silicon layer.

11. The method for preparing a resonant pressure sensor according to claim 10, characterized in that: The second silicon layer includes a temperature sensor substrate located on a side of the resonant component; Before the step of forming the resonant component in the second silicon layer, the method further includes: forming a third groove in the temperature sensor substrate; A metal or a conductive medium is deposited in the third groove to form the temperature sensor.

12. The method for preparing a resonant pressure sensor according to claim 11, characterized in that: After the step of forming the resonant component in the second silicon layer, the method further includes: A first groove and a second groove are respectively formed at positions of the silicon dioxide layer corresponding to the first resonance beam and the second resonance beam; the first groove and the second groove penetrate the silicon dioxide layer and expose the surface of the pressure sensitive film; the first resonance beam and the second resonance beam are suspended on one side of the pressure sensitive film.

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