A pressure sensor and a method of forming the same, electronic device

Abstract

The application discloses a pressure sensor and a forming method thereof and an electronic device, and belongs to the technical field of MEMS sensors. The pressure sensor comprises a first substrate, a second substrate, a medium layer, a first pressure-sensitive element and a second pressure-sensitive element. The first substrate has a first surface and a first groove. The second substrate has a second surface and a third surface, and the second surface is fixedly bonded to the first surface. The medium layer has a fourth surface and a fifth surface, and the fourth surface is connected to the third surface. The first pressure-sensitive element is located between the fourth surface and the third surface. The first groove has a first projection on the second surface, the first pressure-sensitive element has a second projection on the second surface, and the second projection is within the range of the first projection. The second pressure-sensitive element is located on the fifth surface, the piezoresistivity coefficient of the second pressure-sensitive element is smaller than that of the first pressure-sensitive element, the second pressure-sensitive element has a third projection on the second surface, and the third projection is within the range of the first projection. The above scheme can realize double-range pressure measurement, and meanwhile, the volume of the pressure sensor is reduced.

Description

Technical Field

[0001] This application relates to the field of MEMS sensor technology, and in particular to a pressure sensor and its forming method, and an electronic device. Background Technology

[0002] Pressure sensors are used for pressure measurement and monitoring. A piezoresistive resistor is the core component of a pressure sensor. The resistance of a piezoresistive resistor changes with the applied pressure; this characteristic (piezoresistive effect) allows it to convert mechanical pressure signals into electrical signals. Specifically, when a piezoresistive resistor is subjected to external force (pressure), the crystal lattice structure inside the material deforms, causing a change in the mobility of charge carriers (electrons or holes), thus resulting in a change in the resistance value. Consequently, the voltage signal of the piezoresistive resistor changes. This voltage signal is then output to a control module, which converts the voltage signal into a pressure value, thereby enabling pressure measurement and monitoring.

[0003] Among related technologies, MEMS (micro-electro-mechanical systems) piezoresistive pressure sensors are widely used in consumer electronics, medical, and automotive fields due to their high sensitivity and good linearity. In wearable devices (such as smartwatches), these pressure sensors can be used to monitor parameters such as blood pressure and altitude. These pressure sensors typically employ a multi-chip design (such as a dual-chamber absolute pressure chip or a combination of two chips with different pressure ranges), but this increases size, making it difficult to meet the compact size requirements of wearable devices. Summary of the Invention

[0004] This application provides a pressure sensor and its forming method, as well as an electronic device, to at least partially solve the above-mentioned technical problems.

[0005] To achieve the above objectives, according to a first aspect of this application, a pressure sensor is provided, comprising: A first substrate has a first surface and a first groove recessed relative to the first surface; The second substrate has a second surface and a third surface opposite to each other, and the second surface is bonded and fixed to the first surface; A dielectric layer having opposing fourth and fifth surfaces, the fourth surface being connected to the third surface; A first pressure-sensitive element is located between the fourth surface and the third surface; the first groove has a first projection on the second surface, the first pressure-sensitive element has a second projection on the second surface, and the second projection is within the range of the first projection; A second pressure-sensitive element is located on the fifth surface, the piezoresistive coefficient of the second pressure-sensitive element is less than that of the first pressure-sensitive element; the second pressure-sensitive element has a third projection on the second surface, the third projection being within the range of the first projection.

[0006] In some embodiments, the first projection is a rectangle having a center; the distance from the second projection to the center is greater than the distance from the third projection to the center.

[0007] In some embodiments, the material of the first pressure-sensitive element includes monocrystalline silicon; the material of the second pressure-sensitive element includes polycrystalline silicon.

[0008] In some embodiments, the pressure sensor further includes: The first conductive structure includes a first wire and a first pad located between the fourth surface and the third surface, the first wire and the first pad being coupled together, and the first wire also being coupled to the first pressure-sensitive element. The second conductive structure includes a second conductor and a second pad located on the fifth surface, the second conductor and the second pad being coupled together, and the second conductor also being coupled to the second pressure-sensitive element.

[0009] In some embodiments, the first conductive structure further includes: a via structure, a third conductor, and a third connection portion; the via structure penetrates the dielectric layer and is coupled to the first pad; the third conductor is located on the fifth surface and is coupled to the via structure; the third connection portion is located on the fifth surface and is coupled to the third conductor. The second conductive structure further includes: a fourth conductor and a fourth connection portion; the fourth conductor is located on the fifth surface and coupled to the second pad; the fourth connection portion is located on the fifth surface and coupled to the fourth conductor.

[0010] In some embodiments, the third connection portion includes: a third pad, a fourth pad, a fifth pad, and a sixth pad; The third pad is used for grounding, the fourth pad is used for outputting a first positive voltage signal, the fifth pad is used for acquiring a first excitation signal, and the sixth pad is used for outputting a first negative voltage signal. The fourth connection portion includes: a seventh pad, an eighth pad, a ninth pad, and a tenth pad; The seventh pad is used to acquire the second excitation signal, the eighth pad is used to output the second negative voltage signal, the ninth pad is used to ground, and the tenth pad is used to output the second positive voltage signal.

[0011] In some embodiments, the pressure sensor further includes an eleventh pad and a twelfth pad located on the fifth surface; The eleventh pad is coupled to the third and fourth conductors, and the eleventh pad is used for grounding; The twelfth pad is coupled to the third conductor and the fourth conductor, and the twelfth pad is used to acquire the third excitation signal; The third connection portion includes a thirteenth pad and a fourteenth pad; the thirteenth pad is used to output a first positive voltage signal, and the fourteenth pad is used to output a first negative voltage signal. The fourth connection portion includes a fifteenth pad and a sixteenth pad; the fifteenth pad is used to output a second positive voltage signal, and the sixteenth pad is used to output a second negative voltage signal.

[0012] In some embodiments, both the first pressure-sensitive element and the second pressure-sensitive element are coupled to the eleventh pad; and / or, both the first pressure-sensitive element and the second pressure-sensitive element are coupled to the twelfth pad.

[0013] According to a second aspect of this application, an electronic device is provided, including a pressure sensor as described in any of the above embodiments.

[0014] According to a third aspect of this application, a method for forming a pressure sensor as described in any of the foregoing embodiments is provided, comprising: Forming a first substrate and a second substrate; The second surface of the second substrate is bonded and fixed to the first surface of the first substrate; A first pressure-sensitive element is formed on the third surface of the second substrate; A dielectric layer is formed on the third surface of the second substrate; A second pressure-sensitive element is formed on the fifth surface of the dielectric layer.

[0015] This application offers the following advantages: In the pressure sensor provided in this embodiment, the first pressure-sensitive element and the second pressure-sensitive element have different piezoresistive coefficients. The first pressure-sensitive element has a higher piezoresistive coefficient, resulting in a more significant resistance change and a stronger output voltage signal when the second substrate is subjected to a small-range pressure, making it suitable for small-range pressure measurement. The second pressure-sensitive element has a lower piezoresistive coefficient, resulting in a relatively smaller resistance change and a weaker output voltage signal, making it suitable for large-range pressure measurement. Therefore, dual-range pressure measurement can be achieved using the same sensor. Furthermore, by matching the positions of the two pressure-sensitive elements with the structure of the first groove, dual-range pressure detection can be achieved using only one groove, satisfying the dual-range measurement requirements while reducing the size of the pressure sensor.

[0016] Other features and advantages of this application will be described in detail in the following detailed description section. Attached Figure Description To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] To gain a more complete understanding of this application and its beneficial effects, the following description will be provided in conjunction with the accompanying drawings, wherein the same reference numerals in the following description denote the same parts.

[0018] Figure 1 This is a schematic diagram of the structure of the pressure sensor provided in an exemplary embodiment of this disclosure; Figure 2 This is a schematic diagram of the structure of the first substrate and the second substrate provided in an exemplary embodiment of this disclosure; Figure 3 This is a partial structural schematic diagram of the pressure sensor provided in an exemplary embodiment of this disclosure; Figure 4 yes Figure 3 The corresponding top view; Figure 5 This is a partial structural schematic diagram of a pressure sensor with a material layer introduced according to an exemplary embodiment of this disclosure; Figure 6 yes Figure 1 The corresponding top view; Figure 7 This is a schematic diagram of the structure of the pressure sensor after introducing a through hole according to an exemplary embodiment of this disclosure; Figure 8 yes Figure 7 The corresponding top view; Figure 9 This is a schematic diagram of the structure of the pressure sensor provided in an exemplary embodiment of this disclosure; Figure 10 yes Figure 9 The corresponding top view; Figure 11 This is a schematic diagram of the Wheatstone bridge structure corresponding to the first varistor provided in the exemplary embodiments of this disclosure; Figure 12 This is a schematic diagram of the Wheatstone bridge structure corresponding to the second varistor provided in the exemplary embodiments of this disclosure; Figure 13 This is a schematic diagram of the structure of another pressure sensor provided in an exemplary embodiment of this disclosure; Figure 14 This is a schematic diagram of the structure of another pressure sensor provided in an exemplary embodiment of this disclosure; Figure 15 yes Figure 14 The corresponding Wheatstone bridge structure diagram; Figure 16 This is a schematic flowchart illustrating a method for forming a pressure sensor provided in an exemplary embodiment of this disclosure.

[0019] Explanation of reference numerals in the attached figures: 1-First substrate; 11-First surface; 12-First groove; 2-Second substrate; 21-Second surface; 22-Third surface; 3-Dielectric layer; 31-Fourth surface; 32-Fifth surface; 4-First varistor; R1-First varistor; R2-Second varistor; R3-Third varistor; R4-Fourth varistor; 5-Second varistor; r1-Fifth varistor; r2-Sixth varistor; r3-Seventh varistor; r4-Eighth varistor; 6-First conductive structure; 61-First conductor; 62-First pad; 63-Via structure; 64-Third conductor; 65-Third connection; 651-Third pad; 652-Fourth pad; 653-Fifth pad; 654-Sixth pad; 655-Thirteenth pad; 656-Fourteenth pad; 7-Second conductive structure; 71-Second conductor; 72-Second pad; 73-Fourth conductor; 74-Fourth connection; 741-Seventh pad; 742-Eighth pad; 743-Ninth pad; 744-Tenth pad; 745-Fifteenth pad; 746-Sixteenth pad; 8-Material layer; 9-Through hole; 81-Eleventh pad; 82-Twelfth pad; O - Center; AA' - Central axis; Z - First direction. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the protection scope of this application.

[0021] This application provides a pressure sensor; please refer to [link / reference]. Figure 1 The pressure sensor includes: The first substrate 1 has a first surface 11 and a first groove 12 recessed relative to the first surface 11; The second substrate 2 has a second surface 21 and a third surface 22 opposite to each other, and the second surface 21 is bonded and fixed to the first surface 11; The dielectric layer 3 has a fourth surface 31 and a fifth surface 32 opposite to each other, the fourth surface 31 being connected to the third surface 22; A first pressure-sensitive element 4 is located between the fourth surface 31 and the third surface 22; a first groove 12 has a first projection on the second surface 21, and the first pressure-sensitive element 4 has a second projection on the second surface 21, the second projection being within the range of the first projection; The second pressure-sensitive element 5 is located on the fifth surface 32. The piezoresistive coefficient of the second pressure-sensitive element 5 is less than that of the first pressure-sensitive element 4. The second pressure-sensitive element 5 has a third projection on the second surface 21, and the third projection is within the range of the first projection.

[0022] In some embodiments, the pressure sensor has a first direction Z, which is perpendicular to the bottom surface of the first groove 12, the second surface 21, the third surface 22, the fourth surface 31, and the fifth surface 32. The second substrate 2 forms a sensitive membrane along the portion where it overlaps with the first groove 12 along the first direction Z.

[0023] In some embodiments, the pressure sensor is applied to a wearable device.

[0024] In the above embodiments, the first pressure-sensitive element 4 is disposed on the sensitive membrane. Due to the high piezoresistive coefficient of the first pressure-sensitive element 4, when the sensitive membrane is deformed by a small range of pressure, the resistance change of the first pressure-sensitive element 4 is large, and the output voltage signal is strong. Therefore, the first pressure-sensitive element 4 is used to sense the small range of pressure and output the corresponding voltage signal. The second pressure-sensitive element 5 has a lower piezoresistive coefficient, which is smaller than that of the first pressure-sensitive element 4. The piezoresistive effect of the second pressure-sensitive element 5 is weaker than that of the first pressure-sensitive element 4. When the sensitive membrane is deformed by pressure, the resistance change of the second pressure-sensitive element 5 is small, and the output voltage signal is weak. Therefore, the second pressure-sensitive element 5 is used to sense the large range of pressure and output the corresponding voltage signal, realizing that one sensor can measure two ranges of pressure simultaneously. Furthermore, in this embodiment, the positions of the two pressure-sensitive elements with different piezoresistive coefficients are matched with the first groove 12. Only one groove is needed to realize the measurement of dual-range pressure, which can simultaneously meet the dual-range pressure measurement requirements and reduce the size of the pressure sensor. It can simultaneously realize small-range (barometric pressure monitoring, altitude monitoring, where altitude monitoring includes weather forecasting and calorie calculation) and large-range (water pressure detection during diving) measurements, and can also meet the size compactness requirements of wearable devices.

[0025] The piezoresistive coefficient is a parameter describing the degree of resistivity change of a pressure-sensitive element under stress. It reflects the sensitivity of the element's resistivity to stress changes. If Δρ represents the change in resistivity, ρ0 represents the initial resistivity, and σ represents stress (pressure), then the piezoresistive coefficient (denoted by α) can be expressed as α = (Δρ / ρ0) / σ. A larger piezoresistive coefficient indicates a more significant change in resistivity under the same stress, thus making it more sensitive to pressure. It is suitable for sensing small pressure ranges, converting minute pressure changes into larger resistivity changes, and thus conveniently detecting pressure magnitude through resistivity changes (which are represented by voltage signals).

[0026] The pressure sensor and its manufacturing method will be described below with reference to the accompanying drawings.

[0027] In some embodiments, the material of the first substrate 1 includes silicon, the material of the second substrate 2 includes silicon, and the first substrate 1 and the second substrate 2 are arranged along a first direction Z. The second surface 21 of the second substrate 2 is bonded and fixed to the first surface 11 of the first substrate 1, and then thinned to a suitable thickness by chemical mechanical polishing to form… Figure 2 The structure is shown. The thickness of the second substrate 2 is determined by the pressure range. Due to the provision of the first groove 12, a cavity structure is formed between the first substrate 1 and the second substrate 2.

[0028] In some embodiments, see Figure 3 and Figure 4 As shown, a first pressure-sensitive element 4 and a first conductive line 61 are formed on the third surface 22 by diffusion or ion implantation, and a first pad 62 connected to the first conductive line 61 is further provided. The first conductive line 61 and the first pad 62 constitute a first conductive structure 6. The first pressure-sensitive element 4 includes a first pressure-sensitive resistor R1, a second pressure-sensitive resistor R2, a third pressure-sensitive resistor R3, and a fourth pressure-sensitive resistor R4. The material of the first pressure-sensitive element 4 includes monocrystalline silicon, and the first pressure-sensitive element 4 is located near the edge of the first groove 12. The first conductive line 61 interconnects the first pressure-sensitive resistor R1, the second pressure-sensitive resistor R2, the third pressure-sensitive resistor R3, and the fourth pressure-sensitive resistor R4 to form a Wheatstone bridge. Because the first pressure-sensitive element 4 has a high piezoresistive coefficient, when the sensitive film is deformed by a small range of pressure, the resistance change of the first pressure-sensitive element 4 is large, and the voltage signal output by the Wheatstone bridge is strong. Therefore, the first pressure-sensitive element 4 is used to sense small range of pressure.

[0029] In some embodiments, the width of the first wire 61 is set to be wider in order to reduce resistance.

[0030] In some embodiments, after obtaining the first pressure-sensitive element 4 and the first wire 61, refer to Figure 5As shown, a dielectric layer 3 is deposited on the third surface 22 by deposition. The dielectric layer 3 has a fourth surface 31 and a fifth surface 32 facing each other, with the fourth surface 31 in direct contact with the third surface 22. The dielectric layer 3 is made of silicon oxide and is used to isolate the first pressure-sensitive element 4 and the second pressure-sensitive element 5. After obtaining the dielectric layer 3, a material layer 8 is deposited on the fifth surface 32 of the dielectric layer 3. The material layer 8 includes a polycrystalline silicon layer.

[0031] In some embodiments, see Figure 1 and Figure 6 As shown, Figure 6 yes Figure 1 In the corresponding top view, the material layer 8 (polysilicon layer) is doped by diffusion or ion implantation, and the doped material layer 8 is patterned. Excess material layer 8 (polysilicon layer) is removed to form a coupled second varistor 5 and a second conductive line 71. The material of the second varistor 5 includes polysilicon. Further, a second pad 72 is provided to connect the second conductive line 71. The second conductive line 71 and the second pad 72 constitute a second conductive structure 7. The second varistor 5 includes a fifth varistor r1, a sixth varistor r2, a seventh varistor r3, and an eighth varistor r4. The fifth varistor r1, the sixth varistor r2, the seventh varistor r3, the eighth varistor r4, and the second conductive line 71 form a Wheatstone bridge. The first groove 12 has a first projection on the second surface 21. The first projection is rectangular, with a center O, which is the geometric center of the rectangle. The first pressure-sensitive element 4 has a second projection on the second surface 21, and the second pressure-sensitive element 5 has a third projection on the second surface 21. The distance from the second projection to the center O is greater than the distance from the third projection to the center O. The second pressure-sensitive element 5 is located near the edge of the first groove 12, or it can be positioned closer to the center O according to the range requirements. Because there are a large number of grain boundaries between the grains of polycrystalline silicon, the grain boundaries scatter charge carriers, significantly reducing mobility. At the same time, the randomly oriented grains average out the anisotropy of the piezoresistive effect, resulting in a smaller overall piezoresistive coefficient. Therefore, the piezoresistive effect of the second pressure-sensitive element 5 (polycrystalline silicon) is weaker than that of the first pressure-sensitive element 4 (monocrystalline silicon). When the sensitive film is deformed by pressure, the resistance change of the second pressure-sensitive element 5 is smaller, and the voltage signal output by the Wheatstone bridge is weaker. Therefore, the second pressure-sensitive element 5 is used to sense a large range of pressure. It should be noted that, for ease of demonstration, in Figure 6 The dielectric layer 3 is omitted in the middle.

[0032] In some embodiments, see Figure 7 and Figure 8 As shown, a through-hole 9 is provided on the dielectric layer 3, and the through-hole 9 penetrates the dielectric layer 3 along the first direction Z. Furthermore, the through-hole 9 and the first pad 62 are stacked along the first direction Z. It should be noted that, for ease of demonstration, in... Figure 8 The dielectric layer 3 is omitted in the middle.

[0033] In some embodiments, see Figure 9 and Figure 10 As shown, metal is deposited in the via 9 to form a via structure 63, which penetrates the dielectric layer 3 and is coupled to the first pad 62. Further, metal is deposited on the fifth surface 32 to form a third conductor 64, a fourth conductor 73, a third connection portion 65, and a fourth connection portion 74. The third conductor 64 is coupled to the via structure 63; the third connection portion 65 is coupled to the third conductor 64. The fourth conductor 73 is coupled to the second pad 72; the fourth connection portion 74 is coupled to the fourth conductor 73. The voltage signal output by the first varistor 4 is led out to the outside through the third conductor 64 and the third connection portion 65. The voltage signal output by the second varistor 5 is led out to the outside through the fourth conductor 73 and the fourth connection portion 74.

[0034] In some embodiments, the via structure 63 is made of aluminum. The third conductor 64 is made of aluminum. The fourth conductor 73 is made of aluminum.

[0035] In some embodiments, see Figure 10 As shown, the first projection has a central axis AA'; the third connecting part 65 and the fourth connecting part 74 can be disposed on opposite sides of the central axis AA'. Through this embodiment, mutual interference between the voltage signals output by the first pressure-sensitive element 4 and the voltage signals output by the second pressure-sensitive element 5 can be avoided, and it is easier for the subsequent electrical signal processing module (control module) to distinguish between these two different sets of electrical signals. In some embodiments, see Figure 10 As shown, the third connection portion 65 includes: a third pad 651, a fourth pad 652, a fifth pad 653, and a sixth pad 654; the third pad 651 is used for grounding, the fourth pad 652 is used for outputting a first positive voltage signal, the fifth pad 653 is used for acquiring a first excitation signal, and the sixth pad 654 is used for outputting a first negative voltage signal. The function of the first excitation signal is to provide a stable excitation voltage or current to the first pressure-sensitive element 4, enabling it to generate a measurable output signal (first negative voltage signal, first positive voltage signal) when the pressure changes. The fourth connection portion 74 includes: a seventh pad 741, an eighth pad 742, a ninth pad 743, and a tenth pad 744; the seventh pad 741 is used for acquiring a second excitation signal, the eighth pad 742 is used for outputting a second negative voltage signal, the ninth pad 743 is used for grounding, and the tenth pad 744 is used for outputting a second positive voltage signal. The function of the second excitation signal is to provide a stable excitation voltage or current to the second pressure-sensitive element 5, so that it can generate a measurable output signal (second negative voltage signal, second positive voltage signal) when the pressure changes.

[0036] In some embodiments, the pressure sensor is connected to an external control module via a fourth pad 652, a fifth pad 653, a sixth pad 654, a seventh pad 741, an eighth pad 742, and a tenth pad 744. The control module provides a first excitation signal and a second excitation signal, and includes an IC chip. The control module also receives and analyzes a first negative voltage signal and a first positive voltage signal to calculate a first pressure value. If the first pressure value meets a preset small-range pressure interval, it is used as the target pressure value acquired by the pressure sensor. If the first pressure value does not meet the preset small-range pressure interval, the control module receives and analyzes a second negative voltage signal and a second positive voltage signal to calculate a second pressure value, which is then used as the target pressure value acquired by the pressure sensor. In other embodiments, the control module may also preferentially calculate the second pressure value using the second negative voltage signal and the second positive voltage signal, and detect whether the second pressure value meets a preset large-range pressure interval. If the second pressure value meets the preset large-range pressure interval, it is used as the target pressure value acquired by the pressure sensor. If the second pressure value does not meet the preset large range pressure range, the first pressure value is calculated by the first negative voltage signal and the first positive voltage signal, and the first pressure value is used as the target pressure value collected by the pressure sensor.

[0037] In some embodiments, Figure 11 This indicates the Wheatstone bridge structure formed by the first varistor 4. Figure 11 The second pad 72 and the first pad 62 are omitted. The fourth pad 652 is coupled to the first varistor R1 and the second varistor R2 respectively; the fifth pad 653 is coupled to the first varistor R1 and the fourth varistor R4 respectively; the sixth pad 654 is coupled to the fourth varistor R4 and the third varistor R3 respectively; the third pad 651 is coupled to the third varistor R3 and the second varistor R2 respectively.

[0038] In some embodiments, Figure 12 This indicates the Wheatstone bridge structure formed by the second varistor 5. Figure 12 The second pad 72 and the first pad 62 are omitted. The tenth pad 744 is coupled to the fifth varistor r1 and the sixth varistor r2 respectively; the seventh pad 741 is coupled to the fifth varistor r1 and the eighth varistor r4 respectively; the eighth pad 742 is coupled to the eighth varistor r4 and the seventh varistor r3 respectively; and the ninth pad 743 is coupled to the seventh varistor r3 and the sixth varistor r2 respectively.

[0039] Specifically, during the deformation of the sensitive membrane under pressure, the resistance values ​​of the second varistor R2 and the fourth varistor R4 increase, while the resistance values ​​of the first varistor R1 and the third varistor R3 decrease. During the deformation of the sensitive membrane under pressure, the resistance values ​​of the sixth varistor r2 and the eighth varistor r4 increase, while the resistance values ​​of the fifth varistor r1 and the seventh varistor r3 decrease.

[0040] In other embodiments, see Figure 13 , Figure 14 and Figure 15 As shown, the pressure sensor further includes: an eleventh pad 81 and a twelfth pad 82 located on the fifth surface 32; the eleventh pad 81 is coupled to the third wire 64 and the fourth wire 73, and the eleventh pad 81 is used for grounding; the twelfth pad 82 is coupled to the third wire 64 and the fourth wire 73, and the twelfth pad 82 is used to acquire a third excitation signal; the third connection portion 65 includes: a thirteenth pad 655 and a fourteenth pad 656; the thirteenth pad 655 is used to output a first positive voltage signal, and the fourteenth pad 656 is used to output a first negative voltage signal; the fourth connection portion 74 includes: a fifteenth pad 745 and a sixteenth pad 746; the fifteenth pad 745 is used to output a second positive voltage signal, and the sixteenth pad 746 is used to output a second negative voltage signal.

[0041] Figure 13 and Figure 6 The difference is that, in Figure 13 In order to facilitate lead connection, the position of the first pad 62 coupled between the second varistor R2 and the third varistor R3 has been changed, and correspondingly, the positions of the through hole 9 (not shown) and the via structure 63 (not shown) have also been changed.

[0042] Figure 14 and Figure 10 The difference is that, in Figure 14 In this configuration, the first varistor 4 and the second varistor 5 share a twelfth pad 82. The twelfth pad 82 transmits a third excitation signal to both the first varistor 4 and the second varistor 5. The function of the third excitation signal is to simultaneously provide a stable excitation voltage or current to both the first varistor 4 and the second varistor 5. The first varistor 4 and the second varistor 5 share an eleventh pad 81, which is grounded. Therefore... Figure 10 The embodiment shown requires 8 pads on the fifth surface 32, while Figure 14 The embodiment shown only requires 6 pads on the fifth surface 32, eliminating one grounding pad and one pad for transmitting excitation signals. This reduces the number of pads, simplifies the structure, and also reduces redundant and repetitive power and ground lines, reduces the pressure sensor area, and simplifies the packaging process.

[0043] In some embodiments, Figure 15 express Figure 14 The corresponding Wheatstone bridge structure, in Figure 15 The second pad 72 and the first pad 62 are omitted. The thirteenth pad 655 is coupled to the first varistor R1 and the second varistor R2. The fourteenth pad 656 is coupled to the third varistor R3 and the fourth varistor R4. The fifteenth pad 745 is coupled to the fifth varistor R1 and the sixth varistor R2. The sixteenth pad 746 is coupled to the seventh varistor R3 and the eighth varistor R4. The eleventh pad 81 is coupled to the second varistor R2, the third varistor R3, the sixth varistor R2, and the seventh varistor R3. The twelfth pad 82 is coupled to the first varistor R1, the fourth varistor R4, the fifth varistor R1, and the eighth varistor R4.

[0044] This application provides an electronic device including a pressure sensor as described in any of the above embodiments.

[0045] This application provides a method for forming a pressure sensor as described in any of the embodiments, see below. Figure 16 As shown, it includes: S101: Form the first substrate 1 and the second substrate 2; S102: Bond and fix the second surface 21 of the second substrate 2 to the first surface 11 of the first substrate 1; S103: A first pressure-sensitive element 4 is formed on the third surface 22 of the second substrate 2; S104: A dielectric layer 3 is formed on the third surface 22 of the second substrate 2; S105: A second pressure-sensitive element 5 is formed on the fifth surface 32 of the dielectric layer 3.

[0046] In some embodiments, the first pressure-sensitive element 4 may be formed on the third surface 22 of the second substrate 2 by diffusion or ion implantation.

[0047] In some embodiments, after forming the dielectric layer 3, a material layer 8 (polysilicon layer) is deposited. The polysilicon layer can be doped by diffusion or ion implantation, and excess portions of the polysilicon layer can be removed to form a second pressure-sensitive element 5 on the fifth surface 32 of the dielectric layer 3.

[0048] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0049] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0050] The embodiments, implementation methods, and related technical features of this application can be combined and substituted for each other without conflict.

[0051] The above are merely preferred embodiments of this application and are not intended to limit this application in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of this application without departing from the scope of the technical solution of this application shall still fall within the scope of the technical solution of this application.

Claims

1. A pressure sensor, characterized in that, include: The first substrate (1) has a first surface (11) and a first groove (12) recessed relative to the first surface (11); The second substrate (2) has a second surface (21) and a third surface (22) opposite to each other, and the second surface (21) is bonded and fixed to the first surface (11); The dielectric layer (3) has a fourth surface (31) and a fifth surface (32) opposite to each other, the fourth surface (31) being connected to the third surface (22); A first pressure-sensitive element (4) is located between the fourth surface (31) and the third surface (22); the first groove (12) has a first projection on the second surface (21), and the first pressure-sensitive element (4) has a second projection on the second surface (21), the second projection being within the range of the first projection; The second pressure-sensitive element (5) located on the fifth surface (32) has a piezoresistive coefficient that is less than that of the first pressure-sensitive element (4); the second pressure-sensitive element (5) has a third projection on the second surface (21), which is within the range of the first projection.

2. The pressure sensor according to claim 1, characterized in that, The first projection is a rectangle, and the rectangle has a center (O); The distance of the second projection to the center (O) is greater than the distance of the third projection to the center (O).

3. The pressure sensor according to claim 1, characterized in that, The material of the first pressure-sensitive element (4) includes monocrystalline silicon; the material of the second pressure-sensitive element (5) includes polycrystalline silicon.

4. The pressure sensor according to claim 1, characterized in that, Also includes: The first conductive structure (6) includes a first wire (61) and a first pad (62) located between the fourth surface (31) and the third surface (22), the first wire (61) and the first pad (62) being coupled together, and the first wire (61) also being coupled to the first pressure-sensitive element (4). The second conductive structure (7) includes a second conductor (71) and a second pad (72) located on the fifth surface (32), the second conductor (71) and the second pad (72) being coupled together, and the second conductor (71) also being coupled to the second pressure-sensitive element (5).

5. The pressure sensor according to claim 4, characterized in that, The first conductive structure (6) further includes: a via structure (63), a third conductor (64), and a third connection portion (65); the via structure (63) penetrates the dielectric layer (3) and is coupled to the first pad (62); the third conductor (64) is located on the fifth surface (32) and is coupled to the via structure (63); the third connection portion (65) is located on the fifth surface (32) and is coupled to the third conductor (64); The second conductive structure (7) further includes: a fourth conductor (73) and a fourth connection portion (74); the fourth conductor (73) is located on the fifth surface (32) and coupled to the second pad (72); the fourth connection portion (74) is located on the fifth surface (32) and coupled to the fourth conductor (73).

6. The pressure sensor according to claim 5, characterized in that, The third connection portion (65) includes: a third pad (651), a fourth pad (652), a fifth pad (653), and a sixth pad (654); The third pad (651) is used for grounding, the fourth pad (652) is used for outputting a first positive voltage signal, the fifth pad (653) is used for acquiring a first excitation signal, and the sixth pad (654) is used for outputting a first negative voltage signal. The fourth connection portion (74) includes: a seventh pad (741), an eighth pad (742), a ninth pad (743), and a tenth pad (744); The seventh pad (741) is used to acquire the second excitation signal, the eighth pad (742) is used to output the second negative voltage signal, the ninth pad (743) is used to ground, and the tenth pad (744) is used to output the second positive voltage signal.

7. The pressure sensor according to claim 5, characterized in that, Also includes: The eleventh pad (81) and the twelfth pad (82) located on the fifth surface (32); The eleventh pad (81) is coupled to the third conductor (64) and the fourth conductor (73), and the eleventh pad (81) is used for grounding; The twelfth pad (82) is coupled to the third conductor (64) and the fourth conductor (73), and the twelfth pad (82) is used to acquire the third excitation signal; The third connection part (65) includes: a thirteenth pad (655) and a fourteenth pad (656); the thirteenth pad (655) is used to output a first positive voltage signal, and the fourteenth pad (656) is used to output a first negative voltage signal; The fourth connection part (74) includes a fifteenth pad (745) and a sixteenth pad (746); the fifteenth pad (745) is used to output a second positive voltage signal, and the sixteenth pad (746) is used to output a second negative voltage signal.

8. The pressure sensor according to claim 7, characterized in that, Both the first pressure-sensitive element (4) and the second pressure-sensitive element (5) are coupled to the eleventh pad (81); And / or, both the first pressure-sensitive element (4) and the second pressure-sensitive element (5) are connected to the twelfth pad (82).

9. An electronic device, characterized in that, Including the pressure sensor as described in any one of claims 1 to 8.

10. A method for forming a pressure sensor as described in any one of claims 1 to 8, characterized in that, include: Forming a first substrate (1) and a second substrate (2); The second surface (21) of the second substrate (2) is bonded and fixed to the first surface (11) of the first substrate (1); A first pressure-sensitive element (4) is formed on the third surface (22) of the second substrate (2); A dielectric layer (3) is formed on the third surface (22) of the second substrate (2); A second pressure-sensitive element (5) is formed on the fifth surface (32) of the dielectric layer (3).

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