Pressure sensor

Abstract

The embodiment of the invention discloses a pressure sensor. The pressure sensor comprises a strain area; the supporting area is arranged on the periphery of the strain area; a substrate layer located in the strain region and the support region; the dielectric layer is located in the strain area and the supporting area and comprises a first surface close to the substrate layer and a second surface opposite to the first surface; the first metal layer is located in the supporting region and is arranged on the second surface of the dielectric layer; the variable-voltage resistance area is located in the strain area and arranged on the substrate layer, and the variable-voltage resistance area is configured to change the resistance value according to the pressure borne by the strain area; the capacitor region is located in the supporting region and arranged on the substrate layer or the dielectric layer, and the capacitor region is capacitively coupled with the first metal layer through the dielectric layer; wherein the varistor region is closer to the strain region than the capacitor region. By arranging the capacitance area surrounding the varistor, a filtering and noise reduction access of a circuit is formed, high-frequency noise of an external environment is filtered out, electromagnetic interference of equipment is reduced, and stability and output precision of the sensor are enhanced.

Description

Technical Field

[0001] The present application relates to the technical field of pressure sensors, and in particular to a pressure sensor. Background Art

[0002] MEMS pressure sensors are widely used in automotive electronics, consumer electronics, industrial electronics and other fields. They place four piezoresistors that sense pressure changes in parallel at the center of the edge of the strain film to form a Wheatstone bridge circuit. When pressure acts on the strain film, the strain film deforms and generates deformation, which in turn generates stress. The stress change at the center of the edge of the strain film is the largest. The four piezoresistors placed there sense the change in stress, and their resistance values ​​increase or decrease in pairs, causing the bridge to be unbalanced, and the output voltage difference Vout=V2-V1 that is proportional to the loading pressure.

[0003] In the prior art, MEMS pressure sensors are manufactured using semiconductor processes. Usually, a back cavity is set in a silicon substrate. The interlayer between the back cavity and the surface is a silicon strain film. Doped regions are set around the silicon strain film to form a varistor. The heavily doped region and the metal layer are connected to the surface metal and the pad as leads through the ohmic contact between the heavily doped region and the metal layer, thereby outputting a test voltage.

[0004] However, when this MEMS pressure sensor is used in harsh environments such as automobiles and industries, high-frequency noise, electromagnetic interference, etc. in the environment are coupled to the output end of the piezoresistor, which will cause the MEMS pressure sensor's anti-interference ability to deteriorate, the output signal to be unstable, and the voltage to jump greatly, which will lead to problems such as poor signal-to-noise ratio and reduced accuracy. Summary of the invention

[0005] The present application provides a pressure sensor, aiming to effectively solve the problems of poor anti-interference ability and low signal-to-noise ratio of MEMS pressure sensors in the prior art.

[0006] According to the first aspect of the present application, the present application provides a pressure sensor, comprising: a strain zone; a support zone, arranged around the strain zone; a substrate layer, located in the strain zone and the support zone; a dielectric layer, located in the strain zone and the support zone, arranged on the surface of the substrate layer, and comprising a first surface close to the substrate layer and a second surface opposite thereto; a first metal layer, located in the support zone, arranged on the second surface of the dielectric layer; a piezoresistive resistor zone, located in the strain zone, arranged on the substrate layer, the piezoresistive resistor zone being configured to change the size of the resistance value according to the pressure applied to the strain zone; a capacitance zone, located in the support zone, arranged on the substrate layer or the dielectric layer, the capacitance zone being capacitively coupled to the first metal layer through the dielectric layer.

[0007] Through one or more of the above embodiments in the present application, at least the following technical effects can be achieved:

[0008] By integrating filter capacitors and resistors on the pressure sensor using a bridge circuit, it is possible to filter out high-frequency noise and electromagnetic interference from the external environment, block their coupling to the output end, suppress common-mode noise, improve the sensor's signal-to-noise ratio and anti-interference ability, and make the sensor more stable and the output more accurate.

[0009] In addition, the capacitor area in the above-mentioned pressure sensor is formed by the same doping process as that of manufacturing a variable resistor, which is convenient for integration into a MEMS pressure sensor chip, does not require an additional process flow, is low-cost, and has a simple process. At the same time, because the capacitor used for filtering has been integrated into the MEMS pressure sensor chip in advance, there is no need to add external capacitors for filtering in the post-processing circuit or sensor conditioning chip, which reduces the use of large-area capacitors in components or integrated circuits and reduces system costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The technical solution and other beneficial effects of the present application will be made apparent by describing in detail the specific implementation methods of the present application in conjunction with the accompanying drawings.

[0011] Figure 1 is a schematic diagram of a pressure sensor;

[0012] Figure 2 A schematic diagram of a circuit structure of a pressure sensor;

[0013] Figure 3 It is a structural schematic diagram of a pressure sensor;

[0014] Figure 4 A schematic diagram of a circuit structure of a pressure sensor provided according to an embodiment of the present application;

[0015] Figure 5 A schematic diagram of the structure of a pressure sensor provided according to an embodiment of the present application;

[0016] Figure 6 A schematic diagram of the structure of another pressure sensor provided according to an embodiment of the present application;

[0017] Figure 7 A schematic diagram of the circuit structure of another pressure sensor provided according to an embodiment of the present application;

[0018] Figure 8 A schematic diagram of the structure of another pressure sensor provided according to an embodiment of the present application;

[0019] Fig. 9 A schematic diagram of the structure of another pressure sensor provided according to an embodiment of the present application;

[0020] Figure numerals: 10 - substrate layer; 20 - dielectric layer; 21 - through hole; 22 - blind hole; 30 - first metal layer; 31 - first sub-metal layer; 32 - second sub-metal layer; 33 - third sub-metal layer; 34 - fourth sub-metal layer; 40 - voltage-variable resistor area; 50 - capacitor area; 51 - external resistor area; 60 - lead area; 70 - back cavity; 80 - strain film; 90 - doped substrate area. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0022] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0023] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0024] In the present application, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0025] The disclosure below provides many different embodiments or examples to realize the different structures of the present application. In order to simplify the disclosure of the present application, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the various specific processes and material examples provided by the present application, but those of ordinary skill in the art can appreciate the application of other processes and / or the use of other materials.

[0026] MEMS pressure sensors are widely used in automotive electronics, consumer electronics, industrial electronics and other fields. Figure 1 This is a schematic diagram of a pressure sensor. The four piezoresistors that sense pressure changes are placed parallel to each other at the center of the edge of the strain film. Figure 2 Schematic diagram of the circuit structure of a pressure sensor. Figure 2 The resistors in the circuit are connected to form a Whistler bridge circuit. When pressure acts on the strain film, the strain film deforms and generates deformation, which in turn generates stress. The stress change at the center of the edge of the strain film is the largest. The four piezoresistors placed there sense the change in stress, and their resistance values ​​increase or decrease in pairs, causing the bridge to be unbalanced, and the output voltage difference Vout=V2-V1, which is proportional to the loading pressure.

[0027] Figure 3Schematic diagram of the structure of a pressure sensor, the pressure sensor includes a substrate layer 10', a back cavity 70' located in the substrate layer, a strain film 80' on the back cavity, a piezoresistive resistor area 40', a lead area 60', a dielectric layer 20', a doped substrate area 90' and a first metal layer 30', the piezoresistive resistor is electrically connected to a power supply voltage terminal VDD, a ground voltage terminal GND, a first voltage terminal V1 and a second voltage terminal V2 through the lead area and the first metal layer, the doped substrate area is connected to the substrate voltage terminal Vsub, the piezoresistive resistor is used as a boundary to divide the strain area A1' and the support area A2', when pressure acts on the strain area, a voltage proportional to the pressure change is output from the first voltage terminal V1 and the second voltage terminal V2.

[0028] However, when the pressure sensor using this circuit is used in harsh environments such as automobiles and industries, high-frequency noise, electromagnetic interference, etc. in the environment are coupled to the output end of the piezoresistor, which will cause the MEMS pressure sensor's anti-interference ability to deteriorate, the output signal to be unstable, and the voltage to jump greatly, which will lead to problems such as poor signal-to-noise ratio and reduced accuracy.

[0029] In order to solve the problems of poor anti-interference ability and low signal-to-noise ratio of pressure sensors in the prior art, an embodiment of the present application provides a pressure sensor. Figure 4 A circuit structure schematic diagram of a pressure sensor provided according to an embodiment of the present application is given, wherein the pressure sensor includes a first voltage terminal V1, a second voltage terminal V2, a ground voltage terminal GND and a power supply voltage terminal VDD, wherein the ground voltage terminal GND is coupled to a reference ground, the power supply voltage terminal VDD receives a power supply voltage, and the magnitude of the pressure applied to the pressure sensor is calculated based on a voltage difference between the first voltage terminal V1 and the second voltage terminal V2.

[0030] The pressure sensor also includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first capacitor C1, a second capacitor C2, a third capacitor C3 and a fourth capacitor C4. Among them, the first resistor R1 is electrically connected between the first voltage terminal V1 and the power supply voltage terminal VDD, the second resistor R2 is electrically connected between the power supply voltage terminal VDD and the second voltage terminal V2, the third resistor R3 is electrically connected between the second voltage terminal V2 and the ground voltage terminal GND, and the fourth resistor R4 is electrically connected between the ground voltage terminal GND and the first voltage terminal V1. When the pressure on the strain area of ​​the pressure sensor changes, the resistance values ​​of the first resistor R1 and the third resistor R3 increase or decrease synchronously, and the resistance values ​​of the second resistor R2 and the fourth resistor R4 decrease or increase synchronously. In some embodiments, the resistance value of the first resistor R1 is equal to the resistance value of the third resistor R3; the resistance value of the second resistor R2 is equal to the resistance value of the fourth resistor R4.

[0031] The first end of the first capacitor C1 is connected to the first voltage terminal V1, the first end of the second capacitor C2 is connected to the power supply voltage terminal VDD, the first end of the third capacitor C3 is connected to the second voltage terminal V2, the first end of the fourth capacitor C4 is connected to the ground voltage terminal GND, and the second ends of the first capacitor C1 to the fourth capacitor C4 are all connected to the substrate voltage terminal. The capacitors added between the voltage terminal and the substrate voltage terminal of the pressure sensor constitute multiple filtering and noise reduction paths, filtering out high-frequency noise from the external environment and blocking it from coupling to the output terminal. Common-mode noise is suppressed, electromagnetic interference of the equipment is reduced, the signal-to-noise ratio and anti-interference ability of the pressure sensor are improved, and the stability and output accuracy of the sensor are enhanced.

[0032] For the realization of the above circuit structure, the process of manufacturing the capacitor structure on the existing pressure sensor chip is difficult and the manufacturing cost is high. If it is added to the peripheral circuit outside the chip, the number of large-area capacitors in the integrated circuit will increase, which will increase the system cost and reduce the integration.

[0033] Embodiment 1

[0034] In response to the above technical issues, Figure 5 A schematic diagram of the structure of a pressure sensor provided according to an embodiment of the present application is given. The pressure sensor includes a strain area A1 and a support area A2. The support area A2 is arranged around the strain area A1. The scope of the strain area A1 and the support area A2 includes the substrate layer 10 and all structures in the direction perpendicular to the substrate layer 10. It should be noted that the boundary between the strain area A1 and the support area A2 is not limited. Figure 5 In the example shown, the edge of the varistor region 40 farthest from the center is used as the dividing line. In some other embodiments, the edge of the top of the back cavity 70 may also be used as the dividing line.

[0035] The pressure sensor also includes a substrate layer 10, a dielectric layer 20, a first metal layer 30, a piezoresistive resistor area 40 and a capacitance area 50. The substrate layer 10 is located in the strain area A1 and the support area A2. The dielectric layer 20 is located in the strain area A1 and the support area A2, is arranged on the surface of the substrate layer 10, and includes a first surface close to the substrate layer 10 and an opposite second surface. The first metal layer 30 is located in the support area A2 and is arranged on the second surface of the dielectric layer 20. The piezoresistive resistor area 40 is located in the strain area A1 and is arranged on the substrate layer 10, and the piezoresistive resistor area 40 is configured to change the size of the resistance value according to the pressure applied to the strain area A1. The capacitance area 50 is located in the support area A2 and is arranged on the substrate layer 10, and the capacitance area 50 is capacitively coupled with the first metal layer 30 through the dielectric layer 20.

[0036] In some embodiments, the dielectric layer 20 may include an electrically insulating material, and the dielectric layer 20 is continuously disposed on the surface of the substrate layer 10 , so that the substrate layer 10 is insulated from the first metal layer 30 .

[0037] In some embodiments, the pressure sensor also includes a first voltage terminal V1, a second voltage terminal V2, a ground voltage terminal GND and a power supply voltage terminal VDD electrically connected to the first metal layer 30, wherein the ground voltage terminal GND is coupled to a reference ground, and the power supply voltage terminal VDD receives a power supply voltage. When the resistance value of the voltage-variable resistor area 40 changes, the magnitude of the pressure applied to the strain area A1 is calculated based on the voltage difference between the first voltage terminal V1 and the second voltage terminal V2. The first metal layer 30 includes a plurality of first sub-metal layers 31 arranged at intervals, and the first sub-metal layer 31 is electrically connected to the first voltage terminal V1, the second voltage terminal V2, the ground voltage terminal GND or the power supply voltage terminal VDD. The first metal layer 30 can be configured in the form of a wire, a pad, etc., and the pad is used to connect to the voltage terminal of the pressure sensor to receive or output a voltage signal.

[0038] In some embodiments, the voltage-variable resistor area 40 is disposed in the substrate layer 10, connected to the first surface of the dielectric layer 20, and located on the inner side of the strain area A1 at the junction of the strain area A1 and the support area A2. The voltage-variable resistor area 40 includes a first resistor R1 electrically connected between the first voltage terminal V1 and the power supply voltage terminal VDD, a second resistor R2 electrically connected between the power supply voltage terminal VDD and the second voltage terminal V2, a third resistor R3 electrically connected between the second voltage terminal V2 and the ground voltage terminal GND, and a fourth resistor R4 electrically connected between the ground voltage terminal GND and the first voltage terminal V1. When the pressure on the strain area A1 changes, the resistance values ​​of the first resistor R1 and the third resistor R3 increase or decrease synchronously, and the resistance values ​​of the second resistor R2 and the fourth resistor R4 decrease or increase synchronously. The resistance value of the first resistor R1 is equal to the resistance value of the third resistor R3; the resistance value of the second resistor R2 is equal to the resistance value of the fourth resistor R4.

[0039] Please refer to Figure 1 , exemplarily, the first resistor R1 and the third resistor R3 are symmetrically arranged, the second resistor R2 and the fourth resistor R4 are symmetrically arranged, and the center of each resistor is located at a vertex of the rhombus on a cross section perpendicular to the thickness direction of the substrate layer 10. When the pressure on the strain area A1 changes, the resistance values ​​of the first resistor R1 and the third resistor R3 increase or decrease synchronously, and the resistance values ​​of the second resistor R2 and the fourth resistor R4 decrease or increase synchronously. Figure 5 FIG. 2 shows two resistors that change synchronously in the voltage-variable resistance region, for example, Figure 5 The two resistors shown in the figure may be a first resistor R1 and a third resistor R3, or a second resistor R2 and a fourth resistor R4. It should be noted that: Figure 5 The structural diagram shown in the figure is only a schematic illustration of the layered structure of the pressure sensor and is not limited to the display of a specific cross-section of the pressure sensor.

[0040] In some embodiments, the capacitor region 50 includes a plurality of sub-capacitor regions disposed at intervals, and the projection of the sub-capacitor region on the dielectric layer 20 at least partially overlaps with the projection of the corresponding first sub-metal layer 31 on the dielectric layer 20. The sub-capacitor region, the dielectric layer 20, and the corresponding first sub-metal layer 31 form a capacitor structure in a direction perpendicular to the substrate layer 10.

[0041] exist Figure 5 In the illustrated embodiment, the capacitor region 50 is disposed on the substrate layer 10 and is in contact with the first surface of the dielectric layer 20. The substrate layer 10 and the capacitor region 50 are made of single crystal silicon, and the capacitor region 50 and the substrate layer 10 are doped to exhibit the same conductivity type, and the doping concentration of the capacitor region 50 is greater than the doping concentration of the substrate layer 10. Exemplarily, the substrate layer 10 is N-type doped, and the capacitor region 50 is N-type heavily doped.

[0042] exist Figure 5 In the illustrated embodiment, the first metal layer 30 further includes a fourth sub-metal layer 34, and the pressure sensor further includes a doped substrate region 90. The doped substrate region 90 is located in the support region A2, is disposed in the substrate layer 10, and is in contact with the first surface of the dielectric layer 20. The doped substrate region 90 is connected to the fourth sub-metal layer 34 through a through hole 21 penetrating the dielectric layer 20, and the fourth sub-metal layer 34 is connected to the substrate voltage terminal. Exemplarily, the doped substrate region 90 can be N-type heavily doped, connected to the fourth sub-metal layer 34 through the through hole 21, and provides a substrate voltage terminal for the entire substrate layer 10.

[0043] In some embodiments, the pressure sensor further includes a lead area 60, which is located in the support area A2, disposed in the substrate layer 10, and connected to the first surface of the dielectric layer 20. One end of the lead area 60 is connected to the varistor area 40, and the other end is connected to the first metal layer 30 through a through hole 21 that penetrates the dielectric layer 20. The through hole 21 is filled with metal, and the through hole 21 is in metal contact with the first metal layer 30, and is in ohmic contact with the lead area 60.

[0044] The lead region 60 and the piezoresistive resistor region 40 are made of single crystal silicon, and are doped to exhibit the same conductivity type, the doping concentration of the lead region 60 is greater than the doping concentration of the piezoresistive resistor region 40, and the conductivity type of the lead region 60 and the piezoresistive resistor region 40 is opposite to that of the substrate layer 10. Exemplarily, the piezoresistive resistor region 40 is P-type doped, and the lead region 60 is P-type heavily doped.

[0045] In some embodiments, the pressure sensor further includes a back cavity 70. The back cavity 70 is disposed on the substrate layer 10 and is open in a direction away from the dielectric layer 20. A first cross section of the back cavity 70 at least partially overlaps with a projection of the strain region A1 in a thickness direction perpendicular to the substrate layer 10, wherein the first cross section is a cross section with the largest area among all cross sections of the back cavity 70 in a direction parallel to the surface of the substrate layer 10. The substrate layer 10 located in the strain region A1 between the back cavity 70 and the dielectric layer 20 forms a strain film 80, and when the strain film 80 is subjected to pressure, the resistance value of the pressure-variable resistor region 40 changes.

[0046] In some embodiments, the substrate layer 10 is a semiconductor N-type doped <crystal direction 100> silicon wafer with a doping concentration of 1x10 14 cm -3 ~1x10 17 cm -3 ; The doping concentration of the doped substrate region 90 is greater than 1x10 20 cm -3 The doping type of the varistor region 40 is P type, and its doping concentration is 1x10 17 cm -3 ~1x10 20 cm -3 The doping type of the lead region 60 is P type, and its doping concentration is greater than 1x10 20 cm -3 The dielectric layer 20 may include silicon oxide or a composite structure of silicon oxide and silicon nitride. The first metal layer 30 may include metal aluminum (Al), gold (Au), platinum (Pt), and alloy metal layers thereof.

[0047] Embodiment 2

[0048] The present application also provides a pressure sensor, Figure 6 This is a schematic diagram of the structure of the pressure sensor provided in Example 2 of the present application.

[0049] like Figure 6 As shown, the difference between this embodiment and the first embodiment is that the first metal layer 30 further includes a second sub-metal layer 32 and a third sub-metal layer 33. The pressure sensor further includes an external resistance region 51, which is located in the support region A2 and is closer to the strain region A1 than the capacitance region 50.

[0050] One end of the external resistance region 51 is electrically connected to the second sub-metal layer 32, and the other end is electrically connected to the third sub-metal layer 33 to form a resistor connected in series between the second sub-metal layer 32 and the third sub-metal layer 33, wherein the second sub-metal layer 32 is electrically connected to the first voltage terminal V1 or the second voltage terminal V2, and the third sub-metal layer 33 is electrically connected to the voltage-variable resistance region 40.

[0051] In some embodiments, the external resistor region 51 is disposed on the substrate layer 10 and is in contact with the first surface of the dielectric layer 20. The external resistor region 51 is electrically connected to the second sub-metal layer 32 and the third sub-metal layer 33 through the through hole 21 penetrating the dielectric layer 20. The material of the external resistor region 51 is single crystal silicon, and the external resistor region 51 and the substrate layer 10 are doped to exhibit opposite conductivity types, and the doping concentration of the external resistor region 51 is greater than the doping concentration of the substrate layer 10. Exemplarily, the external resistor region 51 is heavily doped with P type, and the substrate layer 10 is doped with N type.

[0052] Figure 7 A schematic diagram of the circuit structure of the pressure sensor provided in the second embodiment of the present application is given as an improvement. Figure 4 The difference between the circuit structure in FIG. 1 and FIG. 2 is that the pressure sensor further includes a fifth resistor R5 and a sixth resistor R6. The first end of the fifth resistor R5 is connected to the second end of the first resistor R1, and the second end of the fifth resistor R5 is connected to the first voltage terminal V1. The first end of the sixth resistor R6 is connected to the second end of the second resistor R2, and the second end of the sixth resistor R6 is connected to the second voltage terminal V2. Adding the fifth resistor R5 and the sixth resistor R6 can further improve the filtering and anti-interference capabilities of the circuit, wherein the fifth resistor R5 can be as shown in FIG. Figure 7 As shown in , it is arranged between the first end of the first capacitor C1 and the first voltage terminal V1, and can also be arranged between the first end of the first capacitor C1 and the second end of the first resistor R1. It is arranged between the first end of the first capacitor C1 and the first voltage terminal V1, which means that on the cross section perpendicular to the thickness direction of the pressure sensor, the fifth resistor R5 is farther away from the first resistor R1 than the first capacitor C1, and is arranged between the first end of the first capacitor C1 and the second end of the first resistor R1, which means that the fifth resistor R5 is closer to the first resistor R1 than the first capacitor C1. Similarly, the sixth resistor R6 can be as Figure 7 As shown in the figure, it is arranged between the first end of the third capacitor C3 and the second voltage end V2, and can also be arranged between the first end of the third capacitor C3 and the second end of the second resistor R2.

[0053] Embodiment 3

[0054] The present application also provides a pressure sensor, Figure 8 This is a schematic diagram of the structure of the pressure sensor provided in Example 3 of the present application.

[0055] like Figure 8 As shown, the difference between this embodiment and the first embodiment is that the capacitor region 50 is disposed in the dielectric layer 20 and is separated from the first metal layer 30. The material of the capacitor region 50 is polysilicon or metal.

[0056] The capacitor region 50 made of polysilicon or metal is capacitively coupled to the first metal layer 30 via the dielectric layer 20 to form a capacitor structure.

[0057] exist Figure 8 In the illustrated embodiment, the first metal layer 30 further includes a fourth sub-metal layer 34, and the pressure sensor further includes a doped substrate region 90. The doped substrate region 90 is located in the support region A2, is disposed in the substrate layer 10, and is in contact with the first surface of the dielectric layer 20. The doped substrate region 90 is connected to the fourth sub-metal layer 34 through a through hole 21 penetrating the dielectric layer 20, the fourth sub-metal layer 34 is connected to the substrate voltage terminal, and the capacitor region 50 is electrically connected to the fourth sub-metal layer 34 through a blind hole 22 partially penetrating the dielectric layer 20.

[0058] Embodiment 4

[0059] The present application also provides a pressure sensor, Fig. 9 This is a schematic diagram of the structure of the pressure sensor provided in Example 4 of the present application.

[0060] like Fig. 9 As shown, the difference between this embodiment and the third embodiment is that the first metal layer 30 further includes a second sub-metal layer 32 and a third sub-metal layer 33. The pressure sensor further includes an external resistance region 51, which is located in the support region A2 and is closer to the strain region A1 than the capacitor region 50.

[0061] One end of the external resistance region 51 is connected to the second sub-metal layer 32, and the other end is connected to the third sub-metal layer 33 to form a resistor connected in series between the second sub-metal layer 32 and the third sub-metal layer 33, wherein the second sub-metal layer 32 is electrically connected to the first voltage terminal V1 or the second voltage terminal V2, and the third sub-metal layer 33 is electrically connected to the voltage-variable resistance region 40.

[0062] exist Fig. 9 In the illustrated embodiment, the external resistor region 51 is disposed in the dielectric layer 20 and is spaced apart from the first metal layer 30. The external resistor region 51 is electrically connected to the second sub-metal layer 32 and the third sub-metal layer 33 through a blind hole 22 that partially penetrates the dielectric layer 20. The material of the external resistor region 51 is polysilicon or metal.

[0063] In this embodiment, since the capacitor region and the resistor region are arranged in the dielectric layer and their material is polysilicon or metal, the capacitance of the capacitor and the resistance of the resistor can be more accurately controlled compared with the capacitor and the resistor formed by doping in the substrate layer.

[0064] In some embodiments, the outer resistance region 51 made of metal material may also be embedded in the first metal layer 30 and formed as a whole during the manufacturing process, which is beneficial to simplify the process flow and reduce production costs.

[0065] In the structure shown in the above embodiment, the capacitor region, the voltage variable resistor region, the lead region, the external resistor region, etc. are doped regions arranged at intervals or continuously, and are formed by doping, deposition, etc. in semiconductor processes. The specific steps of doping, deposition, etc. of each region can be designed according to actual needs, and the embodiment of the present application does not specifically limit this. Among them, the number of doped regions and the doping concentration and doping ions of each doped region can be determined according to the performance design requirements of the device.

[0066] The present application integrates filter capacitors and resistors on a MEMS pressure sensor using a bridge circuit to filter out high-frequency noise and electromagnetic interference from the external environment, block their coupling to the output end, suppress common-mode noise, improve the signal-to-noise ratio and anti-interference ability of the sensor, and make the sensor more stable and the output more accurate.

[0067] In addition, the capacitor area with filtering function of the pressure sensor is formed by the same doping process as the pressure-variable resistor area, which is easy to integrate into the MEMS pressure sensor chip without additional process flow, low cost and simple process. At the same time, because the capacitor area has been integrated into the MEMS pressure sensor chip in advance, there is no need to couple additional filtering capacitors in the post-processing circuit or sensor conditioning chip, which reduces the use of large-area capacitors in components or integrated circuits and reduces system costs.

[0068] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0069] In summary, although the present application has been disclosed as above with preferred embodiments, the above preferred embodiments are not intended to limit the present application. Ordinary technicians in this field can make various changes and modifications without departing from the spirit and scope of the present application. Therefore, the scope of protection of the present application shall be based on the scope defined in the claims.

Claims

1. A pressure sensor, characterized in that: include: strain area; A support area, arranged around the strain area; A substrate layer, located in the strain region and the support region; a dielectric layer, located in the strain region and the support region, disposed on the surface of the substrate layer, and comprising a first surface close to the substrate layer and an opposite second surface; A first metal layer, located in the support area and disposed on the second surface of the dielectric layer; A pressure-variable resistance region, located in the strain region and disposed on the substrate layer, wherein the pressure-variable resistance region is configured to change the magnitude of the resistance value according to the pressure applied to the strain region; The capacitor region is located in the support region and is arranged on the substrate layer or the dielectric layer. The capacitor region is capacitively coupled with the first metal layer through the dielectric layer.

2. The pressure sensor according to claim 1, characterized in that: The pressure sensor further includes a first voltage terminal, a second voltage terminal, a ground voltage terminal and a power supply voltage terminal electrically connected to the first metal layer, the ground voltage terminal is coupled to a reference ground, and the power supply voltage terminal receives a power supply voltage; When the resistance value of the voltage-variable resistor area changes, the magnitude of the pressure applied to the strain area is calculated according to the voltage difference between the first voltage end and the second voltage end.

3. The pressure sensor according to claim 2, characterized in that: The first metal layer includes a plurality of first sub-metal layers arranged at intervals, and the first sub-metal layers are electrically connected to the first voltage terminal, the second voltage terminal, the ground voltage terminal or the power supply voltage terminal.

4. The pressure sensor according to claim 3, characterized in that: The capacitor region comprises a plurality of sub-capacitor regions arranged at intervals, and projections of the sub-capacitor regions on the dielectric layer at least partially overlap with projections of the corresponding first sub-metal layers on the dielectric layer; The sub-capacitor region, the dielectric layer and the corresponding first sub-metal layer form a capacitor structure in a direction perpendicular to the surface of the substrate layer.

5. The pressure sensor according to claim 1, characterized in that: The capacitor region is arranged on the substrate layer and is connected to the first surface of the dielectric layer.

6. The pressure sensor according to claim 5, characterized in that: The substrate layer and the capacitor region are made of single crystal silicon. The capacitor region and the substrate layer are doped to exhibit the same conductivity type. The doping concentration of the capacitor region is greater than the doping concentration of the substrate layer.

7. The pressure sensor according to claim 1, characterized in that: The capacitor region is disposed in the dielectric layer and is spaced apart from the first metal layer.

8. The pressure sensor according to claim 7, characterized in that: The material of the capacitor region is polysilicon or metal.

9. The pressure sensor according to claim 2, characterized in that: The voltage-variable resistor area includes a first resistor electrically connected between the first voltage terminal and the power supply voltage terminal, a second resistor electrically connected between the power supply voltage terminal and the second voltage terminal, a third resistor electrically connected between the second voltage terminal and the ground voltage terminal, and a fourth resistor electrically connected between the ground voltage terminal and the first voltage terminal; When the pressure on the strain area changes, the resistance values ​​of the first resistor and the third resistor increase or decrease synchronously, and the resistance values ​​of the second resistor and the fourth resistor decrease or increase synchronously.

10. The pressure sensor according to claim 9, characterized in that: The resistance value of the first resistor is equal to the resistance value of the third resistor; the resistance value of the second resistor is equal to the resistance value of the fourth resistor.

11. The pressure sensor according to claim 1, characterized in that: The pressure sensor further comprises a lead area, which is located in the support area, arranged in the substrate layer, and connected to the first surface of the dielectric layer; One end of the lead area is connected to the voltage-variable resistor area, and the other end is connected to the first metal layer through a through hole penetrating the dielectric layer.

12. The pressure sensor according to claim 11, characterized in that: The lead area and the varistor area are made of single crystal silicon, are doped to exhibit the same conductivity type, the doping concentration of the lead area is greater than the doping concentration of the varistor area, and the conductivity type of the lead area and the varistor area is opposite to that of the substrate layer.

13. The pressure sensor according to claim 1, wherein: The first metal layer further includes a second sub-metal layer and a third sub-metal layer; the pressure sensor further includes an external resistance region, the external resistance region is located in the support region and is closer to the strain region than the capacitance region; One end of the external resistance area is electrically connected to the second sub-metal layer, and the other end is electrically connected to the third sub-metal layer to form a resistor connected in series between the second sub-metal layer and the third sub-metal layer, wherein the second sub-metal layer is electrically connected to the first voltage terminal or the second voltage terminal, and the third sub-metal layer is electrically connected to the voltage-variable resistance area.

14. The pressure sensor according to claim 13, characterized in that: The external resistance region is disposed on the substrate layer and is in contact with the first surface of the dielectric layer; The outer resistance region is electrically connected to the second sub-metal layer and the third sub-metal layer through a through hole penetrating the dielectric layer.

15. The pressure sensor according to claim 14, characterized in that: The material of the outer resistor region is single crystal silicon, and the outer resistor region and the substrate layer are doped to exhibit opposite conductivity types.

16. The pressure sensor according to claim 13, characterized in that: The external resistance region is arranged in the dielectric layer and is spaced apart from the first metal layer; The outer resistance region is electrically connected to the second sub-metal layer and the third sub-metal layer through a blind hole that partially penetrates the dielectric layer.

17. The pressure sensor according to claim 16, characterized in that: The material of the outer resistance area is polysilicon or metal.

18. The pressure sensor according to claim 1, wherein: The pressure sensor also includes a back cavity; The back cavity is arranged on the substrate layer and is open in a direction away from the dielectric layer; The first cross section of the back cavity at least partially overlaps with the projection of the strain region in a thickness direction perpendicular to the substrate layer, wherein the first cross section is the cross section with the largest area among all cross sections of the back cavity in a surface direction parallel to the substrate layer; The substrate layer located in the strain region between the back cavity and the dielectric layer forms a strain film. When the strain film is subjected to pressure, the resistance value of the pressure-variable resistor region changes.

19. The pressure sensor according to claim 1, characterized in that: The first metal layer further includes a fourth sub-metal layer, and the pressure sensor further includes a doped substrate region; The doped substrate region is located in the support region, is disposed on the substrate layer, and is in contact with the first surface of the dielectric layer; The doped substrate region is connected to the fourth sub-metal layer through a through hole penetrating the dielectric layer, and the fourth sub-metal layer is connected to the substrate voltage terminal.

20. The pressure sensor according to claim 7, characterized in that: The first metal layer further includes a fourth sub-metal layer, and the pressure sensor further includes a doped substrate region; The doped substrate region is located in the support region, is disposed on the substrate layer, and is in contact with the first surface of the dielectric layer; The doped substrate region is connected to the fourth sub-metal layer through a through hole penetrating the dielectric layer, the fourth sub-metal layer is connected to the substrate voltage terminal, and the capacitor region is electrically connected to the fourth sub-metal layer through a blind hole partially penetrating the dielectric layer.

21. The pressure sensor according to claim 19 or 20, characterized in that: The doped substrate region is made of single crystal silicon. The doped substrate region and the substrate layer are doped to exhibit the same conductivity type. The doping concentration of the doped substrate region is greater than the doping concentration of the substrate layer.

22. The pressure sensor according to any one of claims 1 to 20, characterized in that: The substrate layer is of N-type conductivity, and the piezoresistive resistor region is of P-type conductivity.

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