Pressure sensor and method for manufacturing the same

Abstract

The present invention provides a pressure sensor and a method for manufacturing the pressure sensor. The pressure sensor includes a substrate and a first pad and a second pad arranged on the substrate. A capacitor is arranged on the substrate. The capacitor includes a fixed plate and a sensing plate arranged relatively to each other. The fixed plate and the first pad, the sensing plate and the second pad are connected by metal leads. The fixed plate and the sensing plate are both arranged vertically. The pressure sensor innovatively adopts a vertically arranged fixed plate and sensing plate structure, and breaks through by arranging the capacitor on both sides of the second substrate. Environmental pollutants cannot adhere to the vertical sensitive membrane surface, which greatly improves the long-term use reliability of the capacitive pressure sensor. The pressure sensor has the advantages of being able to avoid the accumulation of particle dust, not easy to fail, and having high long-term use reliability. In addition, by using a support column to suspend the second substrate in a receiving groove, it also has the advantage of small temperature drift.

Description

Technical Field

[0001] The present invention relates to the field of microelectronic technology, and in particular to a pressure sensor and a method for manufacturing the pressure sensor. Background Art

[0002] As a widely used sensing and measurement module, pressure sensors have also experienced explosive growth in the fields of wearables, home appliances, new energy vehicles, and smart environments with the development of the Internet of Things. Mainstream capacitive pressure sensors mostly adopt the design principle of flat-plate capacitors, forming sensitive capacitors through upper and lower plates. The upper and lower plates are horizontally laid and set at a certain distance to form a capacitor. When the test pressure acts on the surface of the upper plate, the upper plate deforms, triggering a linear change in capacitance. With the increase in the use cycle, dust and particulate matter accumulate and increase on the surface of the sensitive membrane, especially when there is contamination by larger particles. Since the sensitive membrane itself is thin, the performance of the capacitive pressure sensor is greatly affected, and even damaged, which seriously reduces the long-term reliability of the sensor.

[0003] In addition, in order to ensure that the pressure measurement of the capacitive pressure sensor has sufficient sensitivity, the sensitive membrane of the electrode plate is usually designed to be thinner. In order to ensure the measurement sensitivity, protective glue is usually not used to protect the surface of the sensitive membrane. Even if there is protective glue on the surface, particles will fall on the protective glue, affecting the performance of the pressure sensor.

[0004] In view of this, it is necessary to provide a new pressure sensor and a method for manufacturing the pressure sensor to solve or at least alleviate the above technical defects. Summary of the invention

[0005] The main purpose of the present invention is to provide a pressure sensor and a method for manufacturing the pressure sensor, aiming to solve the technical problems in the prior art that the pressure sensor is easily damaged and has low reliability.

[0006] To achieve the above-mentioned purpose, according to one aspect of the present invention, the present invention provides a pressure sensor, including a MEMS chip, the MEMS chip including a substrate and a first pad and a second pad arranged on the substrate, a capacitor is arranged on the substrate, the capacitor includes a fixed electrode plate and a sensing electrode plate arranged opposite to each other, the fixed electrode plate and the first pad, the sensing electrode plate and the second pad are connected through metal leads, and the fixed electrode plate and the sensing electrode plate are both arranged vertically.

[0007] In one embodiment, the pressure sensor further includes an ASIC chip, the substrate includes a first substrate and a second substrate, the first substrate is bonded to the ASIC chip, the capacitor is arranged on the second substrate, the first substrate is formed with a receiving groove, the second substrate is suspended in the receiving groove and forms a gap with the first substrate.

[0008] In one embodiment, the pressure sensor further includes a support column, the bottom end of the support column is connected to the bottom surface of the accommodating groove, the top end of the support column is connected to the second substrate, the capacitor is arranged on the outer wall of the second substrate, the sensing electrode is arranged on the side of the fixed electrode away from the second substrate, and the sensing electrode is spaced apart from the side wall of the first substrate.

[0009] In one embodiment, the top surface of the first substrate, the top surface of the second substrate, and the top surface of the support column are arranged flush with each other.

[0010] In one embodiment, the number of the capacitors is two, and the two capacitors are respectively disposed on two opposite sides of the second substrate.

[0011] In one embodiment, a plurality of release holes are formed on the second substrate and vertically penetrate the second substrate.

[0012] In one embodiment, a sealing layer is further disposed on the second substrate, and the sealing layer is respectively connected to one side of the fixed electrode plate and the sensing electrode plate, so that a vacuum cavity is formed between the sensing electrode plate and the fixed electrode plate.

[0013] In one embodiment, the sealing layer is a silicon oxide layer.

[0014] According to another aspect of the present invention, the present invention further provides a method for manufacturing a pressure sensor, the method for manufacturing the sensor comprising:

[0015] Providing a first substrate, etching a receiving groove on the first substrate, and manufacturing a sacrificial layer, a supporting column, and a second substrate in the receiving groove;

[0016] Etching the second substrate to form release holes, isolation cavities and cavities;

[0017] Growing a plate material in the cavity and the isolation cavity to form a plate material layer;

[0018] Etching the electrode material layer to form a fixed electrode and a sensing electrode that are vertically and relatively spaced apart;

[0019] Making a first pad, a second pad and a metal lead, connecting the first pad and the fixed electrode, the second pad and the sensing electrode through the metal lead; and making a sealing layer to connect the fixed electrode and the upward side of the sensing electrode;

[0020] The etching solution is injected into the sacrificial layer through the release hole to remove the sacrificial layer, so that the bottom surface of the receiving groove is spaced apart from the bottom surface of the second substrate.

[0021] In one embodiment, the step of etching the second substrate to form the release hole, the isolation cavity and the cavity comprises:

[0022] The isolation cavity and the cavity are respectively formed by etching on two opposite sides of the second substrate, and the isolation cavity separates the side wall of the second substrate from the side wall of the first substrate.

[0023] In one embodiment, the step of growing the plate material in the cavity and the isolation cavity to form a plate material layer includes:

[0024] Doped polysilicon is deposited in the cavity and the isolation cavity by deposition to form the plate material layer.

[0025] In one embodiment, the step of etching the electrode material layer to form a fixed electrode and a sensing electrode comprises:

[0026] The substrate material layer in the cavity is etched to form the fixed electrode, and the electrode material layer in the isolation cavity is etched to form the sensing electrode. A gap is formed between the sensing electrode and the side wall of the first substrate.

[0027] In one embodiment, the steps of manufacturing the first pad, the second pad and the metal lead include:

[0028] A first soldering pad and a second soldering pad are fabricated on the top surface of the first substrate, and metal leads are fabricated on the first substrate, the second substrate and the supporting pillar.

[0029] In the above scheme, the pressure sensor includes a MEMS chip, the MEMS chip includes a substrate and a first pad and a second pad arranged on the substrate, a capacitor is arranged on the substrate, the capacitor includes a fixed plate and a sensing plate arranged relatively, the fixed plate and the first pad, the sensing plate and the second pad are connected by metal leads, and the fixed plate and the sensing plate are arranged vertically. The fixed plate is fixedly connected to the substrate, the fixed plate and the sensing plate form a capacitor, the test pressure acts on the surface of the sensing plate, causing the sensing plate to deform, triggering a linear change in capacitance. The sensing plate includes a sensitive film or the sensing plate is made of a sensitive film. The invention innovatively adopts a vertically arranged sensing plate structure, so that the sensitive film is arranged vertically, replacing the placement structure of the horizontally arranged sensitive film in the prior art. During use, since the sensitive film is a vertical structure, environmental pollutants cannot adhere to the vertical surface of the sensitive film, avoiding the problem of particles and dust accumulating on the sensitive film; it solves the problem that the performance of the traditional capacitive pressure sensor gradually decreases or even fails with the increase of particulate matter during long-term use, and greatly improves the long-term use reliability of the capacitive pressure sensor. The invention has the advantages of being able to avoid the accumulation of particle dust, not being prone to failure and having high reliability in long-term use. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0031] Figure 1 It is a schematic cross-sectional structure diagram of a MEMS chip of a pressure sensor according to an embodiment of the present invention;

[0032] Figure 2 A top view of a MEMS chip of a pressure sensor according to an embodiment of the present invention;

[0033] Figure 3 Schematic diagram of the cross-sectional structure of a pressure sensor according to an embodiment of the present invention;

[0034] Figures 4 to 9 It is a schematic diagram of the structural changes of the method for manufacturing a pressure sensor according to an embodiment of the present invention; wherein,

[0035] Figure 4 A schematic diagram of the structure of a first substrate, a second substrate, a support column and a sacrificial layer in a method for manufacturing a pressure sensor according to an embodiment of the present invention;

[0036] Figure 5 For Figure 4A schematic diagram of a structure in which a separation cavity, a cavity and a release hole are arranged on the structure;

[0037] Figure 6 For Figure 5 A schematic diagram of a structure in which a plate material layer is arranged on a structure;

[0038] Figure 7 For Figure 6 A schematic diagram of a structure in which a fixed electrode plate and a sensing electrode plate are formed by etching on a structure;

[0039] Figure 8 For Figure 7 A schematic diagram of a structure in which a metal lead, a sealing layer, a first pad and a second pad are arranged on the structure;

[0040] Fig. 9 same Figure 1 , for Figure 8 Schematic diagram of removing the sacrificial layer structure from the structure;

[0041] Fig.10 It is a flow chart of a first embodiment of a method for manufacturing a pressure sensor according to an embodiment of the present invention;

[0042] Fig.11 It is a flow chart of a second embodiment of a method for manufacturing a pressure sensor according to an embodiment of the present invention;

[0043] Fig.12 It is a flow chart of a third embodiment of a method for manufacturing a pressure sensor according to an embodiment of the present invention;

[0044] Fig.13 1 is a flow chart of a fourth embodiment of a method for manufacturing a pressure sensor according to an embodiment of the present invention.

[0045] Description of labels:

[0046] 100, MEMS chip; 200, ASIC chip; 1, first substrate; 2, second substrate; 3, capacitor; 31, fixed plate; 32, induction plate; 4, first pad; 5, second pad; 6, metal lead; 7, gap; 8, support column; 9, receiving groove; 91, inner wall; 10, release hole; 11, sealing layer; 12, partition; 13, plate material layer; 14, partition cavity; 15, cavity; 16, sacrificial layer.

[0047] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with the implementation methods and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] It should be noted that all directional indications (such as up, down, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0050] In addition, in the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0051] Furthermore, the technical solutions between the various embodiments of the present invention may be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in the field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0052] See also Figure 1 and Figure 2 According to one aspect of the present invention, a pressure sensor is provided, including a MEMS chip 100, the MEMS chip 100 includes a substrate and a first pad 4 and a second pad 5 arranged on the substrate, a capacitor 3 is arranged on the substrate, the capacitor 3 includes a fixed electrode 31 and a sensing electrode 32 arranged opposite to each other, the fixed electrode 31 and the first pad 4, the sensing electrode 32 and the second pad 5 are connected through a metal lead 6, and the fixed electrode 31 and the sensing electrode 32 are both arranged vertically.

[0053] In the above embodiment, the fixed electrode 31 is fixedly connected to the substrate, and the fixed electrode 31 and the sensing electrode 32 form a capacitor 3. The test pressure acts on the surface of the sensing electrode 32, causing the sensing electrode 32 to deform, triggering the linear change of the capacitor 3. The sensing electrode 32 includes a sensitive film or the sensing electrode 32 is made of a sensitive film, and is a movable electrode. This embodiment innovatively adopts a vertically arranged sensing electrode 32 structure, so that the sensitive film is arranged vertically, replacing the structure of the horizontally arranged sensitive film in the prior art. During use, since the sensitive film is a vertical structure, environmental pollutants cannot adhere to the vertical surface of the sensitive film, avoiding the problem of particles and dust accumulating on the sensitive film; it solves the problem that the performance of the traditional pressure sensor gradually decreases or even fails with the increase of particulate matter during long-term use, and greatly improves the long-term use reliability of the pressure sensor. This embodiment has the advantages of being able to avoid the accumulation of particles and dust, not easy to fail, and having high long-term use reliability.

[0054] See also Figure 3In one embodiment, the pressure sensor further includes an ASIC chip 200, the substrate includes a first substrate 1 and a second substrate 2, the first substrate 1 is bonded to the ASIC chip 200, a capacitor 3 is arranged on the second substrate 2, the first substrate 1 is formed with a receiving groove 9, the second substrate 2 is suspended in the receiving groove 9 and forms a gap 7 with the first substrate 1. Specifically, the first substrate 1 and the ASIC chip 20 can be bonded by glue, and the glue can be silica gel. The pressure sensor can include a MEMS chip 100 and an ASIC chip 200 stacked up and down, and with the development of science and technology, miniaturization, intelligence, and integration are required for smart sensors. In order to improve the overall space utilization of the product, the pressure sensor MEMS chip 100 is usually superimposed on the ASIC chip 200 for integrated packaging. Since the ASIC will emit heat during operation, the MEMS pressure sensor is not only affected by the ambient temperature, but also by the heat of the ASIC. The heat is transferred from the bottom of the MEMS chip 100 to the inside of the chip, resulting in the occurrence of temperature drift, which greatly reduces the various performances of the MEMS chip 100, and the temperature drift characteristics are obvious. This embodiment sets the substrate as a first substrate 1 and a second substrate 2, a receiving groove 9 is formed on the first substrate 1, and the second substrate 2 is suspended in the receiving groove 9 and there is a gap 7 between the first substrate 1 and the second substrate 2. The gap 7 is the spacing between the first substrate 1 and the second substrate 2, which plays a role in blocking heat transfer. The ASIC chip 200 is connected to the first substrate 1, specifically, it can be connected to the bottom surface of the first substrate 1. In this way, due to the existence of the gap, the bottom surface space of the first substrate and the second substrate is separated, and the heat emitted by the ASIC chip 200 will be blocked after being transferred to the first substrate 1 and cannot be transferred to the second substrate 2, and it is even less likely to be transferred to the capacitor 3 set on the second substrate 2, and will not affect the MEMS chip 100. In particular, the pressure capacitor 3 is generally vacuum packaged, and the gap 7 can play a better role in heat insulation. This embodiment provides a lateral sensitive capacitive MEMS pressure sensor structure with high reliability and low temperature drift.

[0055] See also Figure 1 and Figure 2 In one embodiment, the pressure sensor further includes a support column 8, the bottom end of the support column 8 is connected to the bottom surface of the receiving groove 9, the top end of the support column 8 is connected to the second substrate 2, the capacitor 3 is arranged on the outer wall of the second substrate 2, the sensing plate 32 is arranged on the side of the fixed plate 31 away from the second substrate 2, and the sensing plate 32 is spaced apart from the side wall of the first substrate 1, that is, there is a gap 7 between the sensing plate 32 and the inner wall 91 of the receiving groove 9. Specifically, the second substrate 2 can be suspended in the receiving groove 9 by providing a support column 8, so that the second substrate 2, the fixed plate 31 and the sensing plate 32 of the capacitor 3 are spatially isolated from the bottom of the first substrate 1. It should be noted here that, with reference to Figure 2, the support rod has two opposite sides connected to the side walls of the first substrate 1, but these two sides are not the side directions of the second substrate 2 where the capacitor 3 is set, so as to facilitate the metal lead 6. During use, the heat emitted by the bottom ASIC is difficult to be transferred to the sensitive structural unit of the capacitor 3, forming a physical heat isolation system structure, reducing the temperature drift characteristics of the pressure sensor, thereby improving the overall test performance of the pressure sensor. This embodiment is significantly better than the traditional horizontally placed sensitive film pressure sensor structure. Specifically, the support column 8, the first substrate 1 and the second substrate 2 can all be made of single crystal silicon. In addition, since the substrate of the capacitor 3 is connected to the first pad 4 and the second pad 5 through the metal lead 6, the top surface of the first substrate 1, the top surface of the second substrate 2 and the top surface of the support column 8 are arranged flush, so that the metal lead 6 is conveniently arranged.

[0056] See also Figure 1 and Figure 2 In one embodiment, the number of capacitors 3 is two, and the two capacitors 3 are respectively arranged on the opposite sides of the second substrate 2. Of course, the number of first pads 4 and second pads 5 is also two, and each first pad 4 and second pad 5 is arranged corresponding to a capacitor 3, which is used to connect the two plates of the capacitor 3 respectively. This embodiment adopts a dual capacitor 3 structure, which can greatly improve the sensitivity and linearity of the pressure sensor and other indicators, thereby greatly improving the overall test accuracy of the pressure sensor. Of course, it is easy for those skilled in the art to understand that multiple capacitors 3 can also be set according to actual needs.

[0057] See also Figure 1 and Figure 2 In one embodiment, a plurality of release holes 10 are formed on the second substrate 2 and vertically penetrate the second substrate 2. The release holes 10 are mainly used to inject etching solution to remove the sacrificial layer 16 generated in the intermediate process during the manufacturing process of the pressure sensor, which will be discussed in detail in the manufacturing method of the pressure sensor later.

[0058] See also Figure 1 In one embodiment, a sealing layer 11 is further provided on the second substrate 2, and the sealing layer 11 is respectively connected to one side of the fixed electrode 31 and the sensing electrode 32, so that a vacuum cavity is formed between the sensing electrode 32 and the fixed electrode 31. The sealing layer 11 is a silicon oxide layer. The bottom ends of the fixed electrode 31 and the sensing electrode 32 are sealed by the first substrate 1, and the top ends are formed by providing a sealing layer 11 between the sensing electrode 32 and the fixed electrode 31 to form a vacuum cavity, which serves as a reference cavity during pressure measurement. The sealing layer 11 can be made of silicon oxide, and is processed into a hat-like shape after silicon oxide is deposited on the sensing electrode 32 and the fixed electrode 31.

[0059] Reference Fig.10According to the first embodiment of the present invention, the present invention further provides a method for manufacturing a pressure sensor, the method for manufacturing the sensor comprising:

[0060] S10, providing a first substrate 1, etching to form a receiving groove 9 on the first substrate 1, and manufacturing a sacrificial layer 16, a supporting column 8 and a second substrate 2 in the receiving groove 9;

[0061] Reference Figure 4 , the first substrate 1 can be single crystal silicon, and the first substrate 1 is etched on the first substrate 1 by plasma etching to form a receiving groove 9, and then a sacrificial layer 16 is deposited and grown on the bottom surface of the receiving groove 9, and the sacrificial layer 16 can be made of silicon oxide, and then the support column 8 and the second substrate 2 are made, and the bottom surface of the second substrate 2 and the bottom surface of the receiving groove 9 are separated by the sacrificial layer 16, so that when the sacrificial layer 16 is removed later, the bottom surfaces of the first substrate 1 and the second substrate 2 are spaced apart to form a physical isolation structure. At the same time, the bottom end of the support column 8 passes through the sacrificial layer 16 and is connected to the bottom surface of the receiving groove 9, and the top surface of the support column 8, the first substrate 1 and the top surface of the second substrate 2 are flush, and the first substrate 1 and the support column 8 can be made of single crystal silicon, and the side surface of the grown first substrate 1 and the inner side wall 91 of the receiving groove 9 are arranged in a fit;

[0062] S20, etching the second substrate 2 to form a release hole 10, an isolation cavity 14 and a cavity 15;

[0063] Reference Figure 5 Specifically, the release hole 10, the isolation cavity 14 and the cavity 15 can be formed by etching in a plasma etching manner. The release hole 10 is used for subsequently injecting an etching solution to remove the sacrificial layer 16. The release hole 10 vertically penetrates the second substrate 2 and is connected to the sacrificial layer 16. The isolation cavity 14 forms a gap between the outer wall of the second substrate 2 and the inner wall 91 of the receiving groove 9. The cavity 15 and the isolation cavity 14 are separated by a partition 12 of the second electrode plate.

[0064] S30, growing a plate material in the cavity 15 and the isolation cavity 14 to form a plate material layer 13;

[0065] Reference Figure 6 , a substrate material layer may be grown in the cavity 15 and the isolation cavity 14 by deposition to fill the cavity 15 and the isolation cavity 14;

[0066] S40, etching the electrode material layer 13 to form a fixed electrode 31 and a sensing electrode 32 that are vertically and relatively spaced apart;

[0067] Reference Figure 7Here, plasma etching can also be used to dig grooves in the vertical direction of the electrode material layer 13, leaving a fixed electrode 31 fixed on the electrode and a sensing electrode 32 attached to the isolation plate. The sensing electrode can be a sensitive film for sensing external pressure signals and is a movable electrode. The fixed electrode 31 and the sensing electrode 32 form two substrates of the capacitor 3. A gap 7 is formed between the sensing electrode 32 and the inner side wall 91 of the accommodating groove 9 to form a spatial isolation, and the sensing electrode 32 and the fixed electrode 31 are respectively arranged on opposite sides of the isolation plate;

[0068] S50, manufacturing a first pad 4, a second pad 5 and a metal lead 6, connecting the first pad 4 and the fixed electrode 31, the second pad 5 and the sensing electrode 32 through the metal lead 6; and manufacturing a sealing layer 11 to connect the fixed electrode 31 and the upward side of the sensing electrode 32;

[0069] Reference Figure 8 The electrical signal generated by the capacitor 3 after sensing external pressure can be transmitted through the first pad 4, the second pad 5 and the metal lead 6, such as to the ASIC chip 200. The first pad 4, the second pad 5 and the metal lead 6 can be made of copper or gold.

[0070] S60 , injecting etching solution into the sacrificial layer 16 through the release hole 10 to remove the sacrificial layer 16 , so that the bottom surface of the receiving groove 9 is spaced apart from the bottom surface of the second substrate 2 .

[0071] Reference Fig. 9 The etching solution may be hydrofluoric acid, and the sacrificial layer 16 made of silicon oxide will dissolve under the action of hydrofluoric acid, so that the bottom surface of the receiving groove 9 and the bottom surface of the second substrate 2 are spaced apart to achieve physical isolation. The heat generated by the ASIC chip 200 cannot be transferred from the bottom surface of the receiving groove 9 to the first substrate and the capacitor, thereby blocking the heat conduction path.

[0072] In the above embodiment of the present invention, the fixed electrode 31 is fixedly connected to the substrate, and the fixed electrode 31 and the sensing electrode 32 form a capacitor 3. The test pressure acts on the surface of the sensing electrode 32, causing the sensing electrode 32 to deform, triggering the linear change of the capacitor 3. The sensing electrode 32 includes a sensitive film or the sensing electrode 32 is made of a sensitive film. This embodiment innovatively adopts a vertically arranged sensing electrode 32 structure, so that the sensitive film is arranged vertically, replacing the placement structure of the horizontally arranged sensitive film in the prior art. During use, since the sensitive film is a vertical structure, environmental pollutants cannot adhere to the vertical surface of the sensitive film, avoiding the problem of particles and dust accumulating on the sensitive film; it solves the problem that the performance of the traditional pressure sensor gradually decreases or even fails with the increase of particulate matter during long-term use, and greatly improves the long-term use reliability of the pressure sensor. The pressure sensor made by this embodiment has the advantages of being able to avoid the accumulation of particles and dust, not easy to fail, and having high long-term use reliability.

[0073] Reference Fig.11 In one embodiment, step S20 includes:

[0074] S201 , etching to form an isolation cavity 14 and a cavity 15 on opposite sides of the second substrate 2 , respectively. The isolation cavity 14 separates the side wall of the second substrate 2 from the side wall of the first substrate 1 .

[0075] The number of capacitors 3 can be two, and in this case, an isolation cavity 14 and a cavity 15 need to be respectively provided on both sides of the second substrate 2, and the two capacitors 3 are respectively provided on opposite sides of the second substrate 2. Of course, the number of first pads 4 and second pads 5 is also two, and each first pad 4 and second pad 5 is provided corresponding to one capacitor 3.

[0076] In the above embodiment of the present invention, by etching the isolation cavity 14 and the cavity 15 on the opposite sides of the second substrate 2, the isolation cavity 14 separates the side wall of the second substrate 2 and the side wall of the first substrate 1, and a dual capacitor 3 structure can be made, which can greatly improve the sensitivity and linearity of the pressure sensor and other indicators, thereby greatly improving the overall test accuracy of the pressure sensor. Of course, it is easy for those skilled in the art to understand that multiple capacitors 3 can also be set according to actual needs.

[0077] Reference Fig.12 In one embodiment, the step of S30 includes:

[0078] S301, doped polysilicon is deposited in the cavity 15 and the isolation cavity 14 by deposition to form a plate material layer 13. The plate material fills the cavity 15 and the isolation cavity 14 to form the plate material layer 13, in preparation for the subsequent removal of a portion by etching to form a vertically arranged fixed plate 31 and a sensing plate 32.

[0079] Reference Fig.13 In one embodiment, the step of S40 includes:

[0080] S401, etching the substrate material layer in the cavity 15 to form a fixed electrode 31, etching the electrode material layer 13 in the isolation cavity 14 to form a sensing electrode 32, and a gap 7 is formed between the sensing electrode 32 and the side wall of the first substrate 1. The electrode material layer 13 in the cavity 15 is etched by an etching liquid to form a fixed electrode 31, and the fixed electrode 31 is spaced apart from the isolation plate, and the electrode material layer 13 in the isolation cavity 14 is etched by an etching liquid to form a sensing electrode 32, and the sensing electrode 32 is attached to the isolation plate, and a gap 7 is formed between the sensing electrode 32 and the inner side wall 91 of the accommodating groove 9, forming a spatial isolation, and the sensing electrode 32 and the fixed electrode 31 are respectively on the opposite sides of the isolation plate.

[0081] In one embodiment, the step of S50 includes:

[0082] S501, a first pad 4 and a second pad 5 are formed on the top surface of the first substrate 1, and metal leads 6 are formed on the first substrate 1, the second substrate 2 and the support column 8. There are at least two metal leads 6, one metal lead 6 connects the first pad 4 and the fixed electrode 31, and the other metal lead 6 connects the second pad 5 and the sensing electrode 32.

[0083] The above are only optional embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention's specification and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A pressure sensor, characterized in that: The device comprises a MEMS chip and a support column, wherein the MEMS chip comprises a substrate and a first pad and a second pad arranged on the substrate, wherein a capacitor is arranged on the substrate, wherein the capacitor comprises a fixed plate and a sensing plate arranged opposite to each other, wherein the fixed plate and the first pad, and the sensing plate and the second pad are connected via metal leads, and the fixed plate and the sensing plate are arranged vertically; The substrate comprises a first substrate and a second substrate, the capacitor is arranged on the second substrate, a receiving groove is formed on the first substrate, and the second substrate is suspended from the receiving groove and forms a gap with the first substrate; The bottom end of the support column is connected to the bottom surface of the accommodating groove, the top end of the support column is connected to the second substrate, the capacitor is arranged on the outer side wall of the second substrate, the induction plate is arranged on the side of the fixed plate away from the second substrate, and the induction plate is spaced apart from the side wall of the first substrate; The support column has two opposite side surfaces connected to the side walls of the first substrate, and the two side surfaces are not located in the direction of the side surface of the second substrate where the capacitor is disposed.

2. The pressure sensor according to claim 1, characterized in that: The pressure sensor further comprises an ASIC chip, and the first substrate is bonded to the ASIC chip.

3. The pressure sensor according to claim 1, characterized in that: The top surface of the first base, the top surface of the second base and the top surface of the support column are arranged flush with each other.

4. The pressure sensor according to claim 2 or 3, characterized in that: The number of the capacitors is two, and the two capacitors are respectively arranged on two opposite sides of the second substrate.

5. The pressure sensor according to claim 2 or 3, characterized in that: A plurality of release holes are formed on the second substrate and vertically penetrate the second substrate.

6. The pressure sensor according to claim 2 or 3, characterized in that: A sealing layer is further disposed on the second substrate, and the sealing layer is respectively connected to one side of the fixed electrode plate and the sensing electrode plate, so that a vacuum cavity is formed between the sensing electrode plate and the fixed electrode plate.

7. The pressure sensor according to claim 6, characterized in that: The sealing layer is a silicon oxide layer.

8. A method for manufacturing a pressure sensor, applied to manufacturing the pressure sensor according to any one of claims 1 to 7, characterized in that: The manufacturing method of the pressure sensor comprises: Providing a first substrate, etching a receiving groove on the first substrate, and manufacturing a sacrificial layer, a supporting column, and a second substrate in the receiving groove; Etching the second substrate to form release holes, isolation cavities and cavities; Growing a plate material in the cavity and the isolation cavity to form a plate material layer; Etching the electrode material layer to form a fixed electrode and a sensing electrode that are vertically and relatively spaced apart; Making a first pad, a second pad and a metal lead, connecting the first pad and the fixed electrode, the second pad and the sensing electrode through the metal lead; and making a sealing layer to connect the fixed electrode and the upward side of the sensing electrode; The etching solution is injected into the sacrificial layer through the release hole to remove the sacrificial layer, so that the bottom surface of the receiving groove is spaced apart from the bottom surface of the second substrate.

9. The method for manufacturing a pressure sensor according to claim 8, characterized in that: The step of etching the second substrate to form a release hole, an isolation cavity and a cavity comprises: The isolation cavity and the cavity are respectively formed by etching on two opposite sides of the second substrate, and the isolation cavity separates the side wall of the second substrate from the side wall of the first substrate.

10. The method for manufacturing a pressure sensor according to claim 8, characterized in that: The step of growing the plate material in the cavity and the isolation cavity to form a plate material layer comprises: Doped polysilicon is deposited in the cavity and the isolation cavity by deposition to form the plate material layer.

11. The method for manufacturing a pressure sensor according to claim 8, characterized in that: The step of etching the electrode material layer to form a fixed electrode and a sensing electrode comprises: The substrate material layer in the cavity is etched to form the fixed electrode, and the electrode material layer in the isolation cavity is etched to form the sensing electrode. A gap is formed between the sensing electrode and the side wall of the first substrate.

12. The method for manufacturing a pressure sensor according to claim 8, characterized in that: The steps of making the first pad, the second pad and the metal lead include: A first pad and a second pad are formed on the top surface of the first substrate, and metal leads are formed on the first substrate, the second substrate and the support pillar.

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