Pressure sensor, preparation method thereof and electronic equipment

Abstract

The invention provides a pressure sensor, a preparation method thereof and electronic equipment. The preparation method of the pressure sensor comprises the following steps: sequentially depositing a first sacrificial layer, a first movable electrode layer, a second sacrificial layer, a fixed electrode layer and a third sacrificial layer on a substrate; wherein the sensing area of the first movable electrode layer is provided with a first release hole, and the sensing area of the fixed electrode layer is provided with a second release hole; performing etching on the third sacrificial layer to form a first sinking hole extending to the surface of the induction region of the first mobile electrode layer, and depositing a connecting column in the first sinking hole; depositing a second moving electrode layer on the third sacrificial layer, wherein a sensing area of the second moving electrode layer is provided with a third release hole; removing the first sacrificial layer, the second sacrificial layer and the third sacrificial layer on the two sides of the induction region of the fixed electrode layer through the first release hole, the second release hole and the third release hole by adopting an erosion process; and blocking the third release hole to obtain the pressure sensor.

Description

Technical Field

[0001] The present application relates to the field of microelectronics technology, and more specifically, to a pressure sensor and a preparation method thereof and an electronic device. Background Art

[0002] Existing MEMS pressure sensors mainly include piezoresistive pressure sensors and capacitive pressure sensors. Capacitive pressure sensors are sensors that use changes in capacitance to measure pressure. Compared with piezoresistive pressure sensors, capacitive pressure sensors can generally achieve higher measurement accuracy. However, the existing capacitive pressure sensors are relatively complex in preparation and have low production efficiency. Summary of the invention

[0003] The present application provides a new technical solution for a method for preparing a pressure sensor, which can at least solve the technical problem of low production efficiency of existing pressure sensors.

[0004] The present application also provides a new technical solution for a pressure sensor.

[0005] The present application also provides a new technical solution for electronic equipment.

[0006] According to a first aspect of the present application, a method for preparing a pressure sensor is provided, comprising: depositing a first sacrificial layer, a first mobile electrode layer, a second sacrificial layer, a fixed electrode layer and a third sacrificial layer in sequence on a substrate; wherein a first release hole is provided in a sensing region of the first mobile electrode layer, and a second release hole is provided in a sensing region of the fixed electrode layer; a first sinking hole extending to the surface of the sensing region of the first mobile electrode layer is etched on the third sacrificial layer, and a connecting column is deposited in the first sinking hole; a second mobile electrode layer is deposited on the third sacrificial layer, and a third release hole is provided in the sensing region of the second mobile electrode layer; the first sacrificial layer, the second sacrificial layer and the third sacrificial layer located on both sides of the sensing region of the fixed electrode layer are removed through the first release hole, the second release hole and the third release hole by an etching process; and the third release hole is blocked to obtain a pressure sensor.

[0007] Optionally, a diameter of the first sinking hole is smaller than a diameter of the second release hole, and the first sinking hole is located inside the second release hole.

[0008] Optionally, the number of the deposited first mobile electrode layers, the fixed electrode layers, and the second mobile electrode layers are all two, and the positions of the two first mobile electrode layers, the two fixed electrode layers, and the two second mobile electrode layers correspond one to one.

[0009] Optionally, the preparation method also includes: before depositing the second sacrificial layer, patterning the first movable electrode layer to obtain a plurality of spaced-apart first sub-movable electrodes, before depositing the third sacrificial layer, patterning the fixed electrode layer to obtain a plurality of spaced-apart sub-fixed electrodes, and before adopting the etching process, patterning the second movable electrode layer to obtain a plurality of spaced-apart second sub-movable electrodes; wherein each of the first sub-movable electrodes, each of the sub-fixed electrodes and each of the second sub-movable electrodes has a sensing area, and the positions of the plurality of the first sub-movable electrodes, the plurality of the sub-fixed electrodes and the plurality of the second sub-movable electrodes correspond one-to-one.

[0010] Optionally, the step of depositing a connecting column in the first sinking hole includes: depositing a material layer on the upper side of the third sacrificial layer so that the material layer is deposited in each of the first sinking holes; and removing the material layer on the upper surface of the third sacrificial layer to obtain a connecting column.

[0011] Optionally, the step of depositing a material layer on the upper side of the third sacrificial layer includes: depositing a first material layer on the upper side of the third sacrificial layer so that the first material layer covers the inner wall surface of each of the first sinking holes; depositing a second material layer on the upper side of the third sacrificial layer so that the second material layer fills the first sinking holes; removing the first material layer and the second material layer on the upper surface of the third sacrificial layer; depositing a third material layer on the upper side of the third sacrificial layer so that the third material layer covers the upper end of each of the first sinking holes; wherein the first material layer and the third material layer are configured as a first insulating passivation layer.

[0012] Optionally, the preparation method also includes: etching a second sinker hole on the upper side of the third sacrificial layer; depositing a conductive interconnection line on the upper side of the third sacrificial layer to form a lead-out electrode; wherein the conductive interconnection line is connected to the first mobile electrode layer, the fixed electrode layer and / or the second mobile electrode layer in the second sinker hole and / or on the upper surface of the second mobile electrode layer.

[0013] Optionally, the variable capacitors formed by the two first movable electrode layers, the two fixed electrode layers and the two second movable electrode layers are connected through the conductive interconnection lines to form a Wheatstone bridge circuit.

[0014] Optionally, the etching working fluid used in the etching process is a selective gaseous working fluid or a selective liquid working fluid.

[0015] Optionally, the fixed electrode layer includes a second insulating passivation layer, an electrode layer and a third insulating passivation layer deposited in sequence.

[0016] According to a second aspect of the present application, a pressure sensor is provided, which is manufactured by any of the manufacturing methods described above.

[0017] According to a third aspect of the present application, a pressure sensor is provided, comprising: a substrate, a first mobile electrode layer, a fixed electrode layer, and a second mobile electrode layer, which are sequentially spaced apart along a first direction; an insulating layer, wherein the substrate, the first mobile electrode layer, the fixed electrode layer, and the second mobile electrode layer are connected as a whole through the insulating layer; wherein the first mobile electrode layer, the fixed electrode layer, and the second mobile electrode layer correspond to sensing regions, the sensing region of the first mobile electrode layer is provided with a first release hole, the sensing region of the fixed electrode layer is provided with a second release hole, and the sensing region of the second mobile electrode layer is provided with a third release hole, a connecting column is connected between the sensing region of the first mobile electrode layer and the sensing region of the second mobile electrode layer, the connecting column passes through the second release hole, and is spaced apart from the inner wall thereof; the insulating layer is provided with a through groove, the through groove corresponds to the sensing regions of the first mobile electrode layer, the fixed electrode layer, and the second mobile electrode layer, and the second mobile electrode layer is provided with a blocking portion for blocking the third release hole, so that the second mobile electrode layer can sense changes in air pressure.

[0018] Optionally, a material of at least an outer side of the connection pillar is different from a material of the insulation layer.

[0019] Optionally, the number of the first mobile electrode layers, the fixed electrode layers and the second mobile electrode layers are two, the positions of the two first mobile electrode layers, the two fixed electrode layers and the two second mobile electrode layers correspond one to one, and the variable capacitors formed by the two first mobile electrode layers, the two fixed electrode layers and the two second mobile electrode layers are connected through conductive interconnects to form a Wheatstone bridge circuit.

[0020] Optionally, the first movable electrode layer includes a plurality of spaced-apart first sub-movable electrodes, the fixed electrode layer includes a plurality of spaced-apart sub-fixed electrodes, and the second movable electrode layer includes a plurality of spaced-apart second sub-movable electrodes, wherein each of the first sub-movable electrodes, each of the sub-fixed electrodes and each of the second sub-movable electrodes has a sensing area, and the positions of the plurality of the first sub-movable electrodes, the plurality of the sub-fixed electrodes and the plurality of the second sub-movable electrodes correspond one to one, and optionally, the variable capacitors formed by the plurality of the first sub-movable electrodes and the plurality of the sub-fixed electrodes are connected in parallel through conductive interconnections, and the variable capacitors formed by the plurality of the second sub-movable electrodes and the plurality of the sub-fixed electrodes are connected in parallel through conductive interconnections.

[0021] According to a fourth aspect of the present application, an electronic device is provided, comprising the pressure sensor described in any one of the above items.

[0022] According to the preparation method of the pressure sensor of the present application, by setting the first release hole, the second release hole and the third release hole, the sacrificial layers at different positions are removed at one time in one process, which simplifies the entire preparation process flow, can effectively improve production efficiency and reduce production costs; and the first mobile electrode layer, the fixed electrode layer and the second mobile electrode layer form a differential capacitor structure, and the differential capacitor structure can effectively improve the temperature stability and reliability of the pressure sensor.

[0023] Other features and advantages of the present application will become apparent from the following detailed description of exemplary embodiments of the present application with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the application and, together with the description, serve to explain the principles of the application.

[0025] Figure 1 is a flow chart of a method for preparing a pressure sensor according to an embodiment of the present application;

[0026] Figure 2 is a schematic diagram of a method for preparing a pressure sensor according to an embodiment of the present application after depositing a first mobile electrode layer;

[0027] Figure 3 is a schematic diagram of a method for preparing a pressure sensor according to an embodiment of the present application after depositing a fixed electrode layer;

[0028] Figure 4 is a schematic diagram of step S100 of a method for preparing a pressure sensor according to an embodiment of the present application;

[0029] Figure 5 is a schematic diagram of a method for preparing a pressure sensor according to an embodiment of the present application after etching a first sink hole;

[0030] Figure 6 is a schematic diagram of step S211 of a method for preparing a pressure sensor according to an embodiment of the present application;

[0031] Figure 7 is a schematic diagram of step S212 of a method for preparing a pressure sensor according to an embodiment of the present application;

[0032] Figure 8 is a schematic diagram of step S213 of a method for preparing a pressure sensor according to an embodiment of the present application;

[0033] Fig. 9is a schematic diagram of step S214 of a method for preparing a pressure sensor according to an embodiment of the present application;

[0034] Fig.10 is a schematic diagram of step S220 of a method for preparing a pressure sensor according to an embodiment of the present application;

[0035] Fig.11 is a schematic diagram of step S300 of a method for preparing a pressure sensor according to an embodiment of the present application;

[0036] Fig.12 is a schematic diagram of step S400 of a method for preparing a pressure sensor according to an embodiment of the present application;

[0037] Fig.13 is a schematic diagram of step S500 of a method for preparing a pressure sensor according to an embodiment of the present application;

[0038] Fig.14 is a schematic structural diagram of a pressure sensor according to an embodiment provided by the present application;

[0039] Fig.15 is a cross-sectional view of a pressure sensor at a fixed electrode layer according to an embodiment provided by the present application;

[0040] Fig.16 is a cross-sectional view of a pressure sensor at a fixed electrode layer according to another embodiment provided by the present application;

[0041] Fig.17 is a schematic diagram of the structure of a Wheatstone bridge circuit of a pressure sensor provided in the present application.

[0042] Reference numerals

[0043] 100. Pressure sensor;

[0044] 10. substrate; 20. first sacrificial layer;

[0045] 30, first mobile electrode layer; 30a, first release hole; 30b, fourth insulating passivation layer; 30c, second bare electrode layer; 31, first sub-mobile electrode;

[0046] 40, fixed electrode layer; 40a, second release hole; 40b, second insulating passivation layer; 40c, first bare electrode layer; 40d, third insulating passivation layer; 41, sub-fixed electrode;

[0047] 50. Connecting column; 60. Second mobile electrode layer; 60a. Third release hole; 60b. Blocking portion; 61. Second sub-mobile electrode; 70. Lead-out electrode. DETAILED DESCRIPTION

[0048] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that unless otherwise specifically stated, the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application.

[0049] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present application, its application, or uses.

[0050] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered as part of the specification.

[0051] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0052] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0053] The following first describes in detail a method for preparing the pressure sensor 100 according to an embodiment of the present application with reference to the accompanying drawings.

[0054] like Figures 1 to 14 As shown, the method for preparing the pressure sensor 100 according to the embodiment of the present application includes: S100 to S500.

[0055] S100, depositing a first sacrificial layer 20, a first mobile electrode layer 30, a second sacrificial layer, a fixed electrode layer 40 and a third sacrificial layer on the substrate 10 in sequence; wherein the sensing region of the first mobile electrode layer 30 is provided with a first release hole 30a, and the sensing region of the fixed electrode layer 40 is provided with a second release hole 40a;

[0056] Specifically, the required substrate 10 can be first obtained, and then a first sacrificial layer 20 is deposited on the upper surface of the substrate 10, so that the first sacrificial layer 20 covers the upper surface of the substrate 10; then, a first mobile electrode layer 30 is deposited on the upper surface of the first sacrificial layer 20, and the first mobile electrode layer 30 is patterned by a photolithography process, so that a first release hole 30a is formed through its sensing area; next, a second sacrificial layer is deposited on the upper side of the first mobile electrode layer 30, the deposited second sacrificial layer covers the upper surface of the first mobile electrode layer 30, fills the first release hole 30a and is connected to the first sacrificial layer 20 as a whole; next, a fixed electrode layer 40 is deposited on the upper side of the second sacrificial layer, and the first mobile electrode layer 30 is patterned by a photolithography process, so that a second release hole 40a is formed through its sensing area; finally, a third sacrificial layer is deposited on the upper side of the fixed electrode layer 40, the deposited third sacrificial layer covers the upper surface of the fixed electrode layer 40, fills the second release hole 40a and is connected to the second sacrificial layer as a whole.

[0057] S200, etching on the third sacrificial layer to form a first sink hole extending to the surface of the sensing area of ​​the first mobile electrode layer 30, and depositing a connecting column 50 in the first sink hole;

[0058] In detail, after the third sacrificial layer is formed, a wet etching process can be used to etch a first sinker hole at a position of the third sacrificial layer relative to the sensing area of ​​the first mobile electrode layer 30, and the etched first sinker hole extends to the surface of the sensing area of ​​the first mobile electrode layer 30, and then a connecting column 50 can be deposited in the first sinker hole, so that the deposited connecting column 50 can be fixedly connected to the first mobile electrode layer 30.

[0059] S300, depositing a second mobile electrode layer 60 on the third sacrificial layer, wherein a third release hole 60a is provided in a sensing area of ​​the second mobile electrode layer 60;

[0060] Specifically, after the connecting column 50 is formed, the second mobile electrode layer 60 is deposited on the upper side of the third sacrificial layer, so that the second mobile electrode layer 60 is fixedly connected to the third sacrificial layer and the connecting column 50, and the second mobile electrode layer 60 can be patterned using a photolithography process so that a third release hole 60a is formed through its sensing area.

[0061] S400, removing the first sacrificial layer 20, the second sacrificial layer and the third sacrificial layer located on both sides of the sensing area of ​​the fixed electrode layer 40 through the first release hole 30a, the second release hole 40a and the third release hole 60a by an etching process;

[0062] That is to say, after the second mobile electrode layer 60 is formed, the first sacrificial layer 20, the second sacrificial layer and the third sacrificial layer can be selectively removed by an etching process. Specifically, the etching medium can flow from the third release hole 60a to the third sacrificial layer, and the third sacrificial layer on the upper side of the sensing area of ​​the fixed electrode layer 40 (that is, the third sacrificial layer between the sensing area of ​​the fixed electrode layer 40 and the sensing area of ​​the second mobile electrode layer 60) can be removed by the etching medium, so that the sensing area of ​​the second mobile electrode layer 60 is released.

[0063] The corrosive medium can also flow from the second release hole 40a to the second sacrificial layer to remove the second sacrificial layer on the lower side of the sensing area of ​​the fixed electrode layer 40 (i.e., the second sacrificial layer between the sensing area of ​​the fixed electrode layer 40 and the sensing area of ​​the first movable electrode layer 30); the corrosive medium can also flow from the first release hole 30a to the first sacrificial layer 20 to remove the first sacrificial layer 20 on the lower side of the sensing area of ​​the fixed electrode layer 40 (i.e., the first sacrificial layer 20 between the sensing area of ​​the first movable electrode layer 30 and the substrate 10), so that the sensing area of ​​the first movable electrode layer 30 is released, thereby forming a variable capacitor between the first movable electrode layer 30 and the fixed electrode layer 40, and a variable capacitor between the second movable electrode layer 60 and the fixed electrode layer 40.

[0064] S500 , blocking the third release hole 60 a to obtain the pressure sensor 100 .

[0065] Specifically, after the sacrificial layer is removed, the third release hole 60a may be blocked with one or more materials. In the present embodiment, the third release hole 60a is blocked with multiple materials, from bottom to top. For example, silicon oxide may be used to block the third release hole 60a initially, and then a silicon nitride layer may be deposited on the upper side of the third release hole 60a to block the third release hole 60a for a second time. Finally, an electrode material may be deposited on the upper side of the silicon nitride layer to form an electrode layer connected to the second movable electrode as a whole, so as to block the third release hole 60a. 0a for final sealing; or, first, silicon nitride can be used to perform preliminary sealing in the third release hole 60a, and then a silicon oxide layer can be deposited on the upper side of the third release hole 60a to perform secondary sealing on the third release hole 60a, and finally, an electrode material can be deposited on the upper side of the silicon oxide layer to form an electrode layer connected to the second movable electrode as a whole, so as to perform final sealing on the third release hole 60a, thereby ensuring the sealing effect and good reliability. After sealing, the pressure sensor 100 can be obtained, and a sealed cavity is formed in the pressure sensor 100 after sealing.

[0066] Therefore, according to the preparation method of the pressure sensor 100 provided in this embodiment, by setting the first release hole 30a, the second release hole 40a and the third release hole 60a, the sacrificial layers at different positions are removed at one time in one process, which simplifies the entire preparation process flow, can effectively improve production efficiency and reduce production costs; and the first mobile electrode layer 30, the fixed electrode layer 40 and the second mobile electrode layer 60 form a differential capacitor structure, and the differential capacitor structure can effectively improve the temperature stability and reliability of the pressure sensor 100.

[0067] In some optional examples of the present application, the first mobile electrode layer 30 , the fixed electrode layer 40 , and the second mobile electrode layer 60 are all polysilicon layers.

[0068] In some embodiments of the present application, the diameter of the first sinking hole is smaller than the diameter of the second release hole 40a, and the first sinking hole is located inside the second release hole 40a.

[0069] That is to say, Figure 5 As shown, the position of the first sinker hole corresponds to the position of the second release hole 40a, and the diameter of the first sinker hole is smaller than the diameter of the second release hole 40a, so that the structure of the fixed electrode layer 40 will not be encountered when etching the first sinker hole. Therefore, the same etching medium can be used to perform the etching process, which is beneficial to simplify the steps of the entire etching process.

[0070] According to an embodiment of the present application, the number of deposited first mobile electrode layers 30 , fixed electrode layers 40 and second mobile electrode layers 60 are all two, and the positions of the two first mobile electrode layers 30 , the two fixed electrode layers 40 and the two second mobile electrode layers 60 correspond one to one.

[0071] Specifically, Fig.15As shown, in step S100, two spaced-apart first mobile electrode layers 30 are deposited on the upper surface of the first sacrificial layer 20. For example, during preparation, a single mobile electrode layer is deposited on the upper surface of the first sacrificial layer 20, and the single electrode layer can be patterned into two spaced-apart first mobile electrode layers 30 by a photolithography process; a second sacrificial layer located on the upper side of the substrate 10 covers the two first mobile electrode layers 30, and two spaced-apart fixed electrode layers 40 are deposited on the upper surface of the second sacrificial layer. For example, during preparation, a single electrode layer is deposited on the upper surface of the second sacrificial layer, and the single electrode layer can be patterned into two spaced-apart fixed electrode layers 40 by a photolithography process, wherein the first fixed electrode The electrode layer 40 is located directly above the first first mobile electrode layer 30, the second fixed electrode layer 40 is located directly above the second first mobile electrode layer 30, the third sacrificial layer located on the upper side of the substrate 10 covers the two fixed electrode layers 40, and two second mobile electrode layers 60 are deposited on the upper surface of the third sacrificial layer. For example, during preparation, a single mobile electrode layer is deposited on the upper surface of the third sacrificial layer, and the single mobile electrode layer can be patterned into two spaced-apart second mobile electrode layers 60 through a photolithography process, wherein the first second mobile electrode layer 60 is located directly above the first fixed electrode layer 40, and the second second mobile electrode layer 60 is located directly above the second fixed electrode layer 40.

[0072] In this embodiment, the first second mobile electrode layer 60 and the first fixed electrode layer 40 form a variable capacitor C1, the first first mobile electrode layer 30 and the first fixed electrode layer 40 form a variable capacitor C2, the second second mobile electrode layer 60 and the second fixed electrode layer 40 form a variable capacitor C3, and the second first mobile electrode layer 30 and the second fixed electrode layer 40 form a variable capacitor C4. Fig.17 As shown, the variable capacitors C1, C2, C3 and C4 can be electrically connected to form a Wheatstone bridge circuit, which can effectively improve the nonlinearity of the capacitance sensor and enhance the temperature stability and reliability.

[0073] In some embodiments of the present application, before depositing the second sacrificial layer, the first mobile electrode layer 30 is patterned to obtain a plurality of spaced-apart first sub-mobile electrodes 31; before depositing the third sacrificial layer, the fixed electrode layer 40 is patterned to obtain a plurality of spaced-apart sub-fixed electrodes 41; before adopting the etching process, the second mobile electrode layer 60 is patterned to obtain a plurality of spaced-apart second sub-mobile electrodes 61; wherein each first sub-mobile electrode 31, each sub-fixed electrode 41 and each second sub-mobile electrode 61 has a sensing area, and the positions of the plurality of first sub-mobile electrodes 31, the plurality of sub-fixed electrodes 41 and the plurality of second sub-mobile electrodes 61 correspond one to one.

[0074] That is to say, Fig.16As shown, during preparation, a single first mobile electrode layer 30 can be patterned into a plurality of spaced-apart first sub-mobile electrodes 31 by a photolithography process, and the middle region of each first sub-mobile electrode 31 has one or more first release holes 30a; a single fixed electrode layer 40 can be patterned into a plurality of spaced-apart sub-fixed electrodes 41 by a photolithography process, and the middle region of each sub-fixed electrode 41 has one or more second release holes 40a; a single second mobile electrode layer 60 can be patterned into a plurality of spaced-apart second sub-mobile electrodes 61 by a photolithography process, and the middle region of each second sub-mobile electrode 61 has one or more third release holes 60a; the middle regions of each first sub-mobile electrode 31, each sub-fixed electrode 41 and each second sub-mobile electrode 61 are configured as sensing regions, and the positions of the plurality of first sub-mobile electrodes 31, the plurality of sub-fixed electrodes 41 and the plurality of second sub-mobile electrodes 61 correspond one to one, so that the plurality of second sub-mobile electrodes 61 and the plurality of sub-fixed electrodes 41 form a plurality of first sub-capacitors, and the plurality of second sub-mobile electrodes 61 and the plurality of sub-fixed electrodes 41 form a plurality of second sub-capacitors.

[0075] Specifically, the multiple first sub-capacitors formed by the first second mobile electrode layer 60 and the first fixed electrode layer 40 can be connected in parallel to form a variable capacitor C1, the multiple second sub-capacitors formed by the first first mobile electrode layer 30 and the first fixed electrode layer 40 can be connected in parallel to form a variable capacitor C2, the multiple first sub-capacitors formed by the second second mobile electrode layer 60 and the second fixed electrode layer 40 can be connected in parallel to form a variable capacitor C3, and the multiple second sub-capacitors formed by the second first mobile electrode layer 30 and the second fixed electrode layer 40 can be connected in parallel to form a variable capacitor C4.

[0076] In this embodiment, the variable capacitors C1, C2, C3 and C4 are all formed by connecting a plurality of sub-capacitors in parallel. When one of the sub-capacitors is damaged, the variable capacitors can still be used normally, thereby effectively improving the reliability of the pressure sensor 100.

[0077] In some optional examples of the present application, the sensing areas of the first sub-movable electrode 31 , the fixed electrode and the second sub-movable electrode 61 are respectively provided with a plurality of release holes.

[0078] According to one embodiment of the present application, the step of depositing the connecting pillar 50 in the first sink hole includes: S210 and S220.

[0079] S210, depositing a material layer on the upper side of the third sacrificial layer so that the material layer is deposited in each first sink hole;

[0080] S220 , removing the material layer on the upper surface of the third sacrificial layer to obtain the connecting column 50 .

[0081] That is, after the first sink hole is formed, a material layer is deposited on the upper side of the third sacrificial layer, so that the deposited material layer can be deposited not only on the upper surface of the third sacrificial layer, but also in each first sink hole, and then, the material layer on the upper surface of the third sacrificial layer can be removed by photolithography to obtain the required connecting column 50. The above method enables multiple connecting columns 50 to be formed at one time, effectively simplifies the manufacturing process, and thus significantly improves production efficiency.

[0082] In some embodiments of the present application, the step of depositing a material layer on the upper side of the third sacrificial layer includes: S211 to S214.

[0083] S211, depositing a first material layer on the upper side of the third sacrificial layer so that the first material layer covers the inner wall surface of each first sink hole;

[0084] S212, depositing a second material layer on the upper side of the third sacrificial layer so that the second material layer fills the first sink hole;

[0085] S213, removing the first material layer and the second material layer on the upper surface of the third sacrificial layer;

[0086] S214, depositing a third material layer on the upper side of the third sacrificial layer so that the third material layer covers the upper end of each first sink hole; wherein the first material layer and the third material layer are configured as a first insulating passivation layer.

[0087] That is to say, Figures 6 to 9 As shown, after the first sink hole is formed, a first material layer can be deposited on the upper side of the third sacrificial layer, so that the deposited first material layer can not only be deposited on the upper surface of the third sacrificial layer, but also be deposited on the inner wall surface of each first sink hole; next, a second material layer is deposited on the upper side of the third sacrificial layer, so that the deposited second material layer can not only be deposited on the upper surface of the first material layer, but also can fill each first sink hole; then, the first material layer and the second material layer on the upper surface of the third sacrificial layer are removed by chemical mechanical polishing, and the first material layer in the first sink hole is flush with the upper surfaces of the second material layer and the third sacrificial layer; next, a third material layer is deposited on the upper side of the third sacrificial layer, so that the deposited second material layer can not only be deposited on the upper surface of the first material layer, but also can cover the upper end of each first sink hole, so that the third material layer can be connected to the first material layer as a whole to form the outermost structure of the connecting column 50; finally, the third material layer on the upper surface of the third sacrificial layer can be removed by photolithography, and the desired connecting column 50 can be obtained.

[0088] In this embodiment, the first material layer and the third material layer outside the connection pillar 50 are a first insulating passivation layer (eg, a silicon nitride layer), which can prevent the connection pillar 50 from being damaged when the sacrificial layer is removed.

[0089] Furthermore, the density of the second material layer is configured to be smaller than the density of the first material layer and the third material layer, so as to avoid the connection column 50 being too heavy, thereby effectively reducing the weight of the pressure sensor 100 .

[0090] In some optional examples of the present application, the hardness of the first material layer and the third material layer is greater than the hardness of the second material layer.

[0091] Specifically, the material of the first material layer and the third material layer can be the same, for example, the first material layer and the third material layer are configured as silicon nitride layers, and the second material layer can be the same as the material of the first sacrificial layer 20, the second sacrificial layer and the third sacrificial layer, for example, the second material layer is configured as a silicon oxide layer.

[0092] In this example, the hardness of the silicon nitride layer is greater than that of the silicon oxide layer, so that the hardness of the connecting pillar 50 can be increased, so that the second moving electrode can reliably drive the first moving electrode to move synchronously through the connecting pillar 50 .

[0093] According to one embodiment of the present application, the preparation method further includes: S600 and S700.

[0094] S600, etching a second sink hole on the upper side of the third sacrificial layer;

[0095] S700, depositing conductive interconnects on the upper side of the third sacrificial layer to form lead-out electrodes 70; wherein the conductive interconnects are connected to the first mobile electrode layer 30, the fixed electrode layer 40 and / or the second mobile electrode layer 60 in the second sinker hole and / or on the upper surface of the second mobile electrode layer 60.

[0096] That is to say, Fig.13 and 14 As shown, part of the third sacrificial layer is not covered by the second movable electrode layer 60, part of the fixed electrode layer 40 is staggered with the second movable electrode layer 60, and part of the first movable electrode layer 30 is staggered with the fixed electrode layer 40 and the second movable electrode layer 60. After the third release hole 60a is blocked, multiple second sinker holes can be etched on the upper side of the third sacrificial layer according to actual needs. For example, part of the second sinker holes extends to the surface of the fixed electrode layer 40, and part of the second sinker holes extends to the surface of the first movable electrode layer 30.

[0097] Next, a conductive interconnection line can be deposited at a corresponding position on the upper side of the third sacrificial layer. The conductive interconnection line can be made of metal, for example, aluminum. The conductive interconnection line can be deposited at the corresponding positions of the second sinker hole, the second movable electrode layer 60 and the third sacrificial layer, so that the conductive interconnection line is connected to the first movable electrode layer 30 and the second movable electrode layer 60 in the second sinker hole and on the upper surface of the second movable electrode layer 60. Finally, an insulating covering layer (for example, a silicon nitride layer) is deposited to cover part of the conductive interconnection line, and the uncovered part of the conductive interconnection line is formed as the lead-out electrode 70.

[0098] Thus, the first movable electrode layer 30, the fixed electrode layer 40 and the second movable electrode layer 60 can be connected together through the conductive interconnection line to form a required circuit, and a corresponding extraction electrode 70 can be provided for easy use.

[0099] In some embodiments of the present application, the variable capacitors formed by the two first mobile electrode layers 30 , the two fixed electrode layers 40 , and the two second mobile electrode layers 60 are connected through conductive interconnects to form a Wheatstone bridge circuit.

[0100] Specifically, Fig.17 As shown, the deposited conductive interconnects can connect the variable capacitors (i.e., C1, C2, C3, and C4) formed by the two sets of first mobile electrode layers 30, the two sets of fixed electrode layers 40, and the two sets of second mobile electrode layers 60 to form a Wheatstone bridge circuit. When external pressure acts on the pressure sensor 100, the capacitance values ​​of C1 and C3 increase, while the capacitance values ​​of C2 and C4 decrease, so that the pressure sensor 100 can achieve low-noise detection, which can effectively improve the nonlinearity of the capacitance sensor, and improve the temperature stability and reliability.

[0101] In some embodiments of the present application, the etching fluid used in the etching process is a selective gaseous fluid or a selective liquid fluid.

[0102] That is, the erosion medium used to remove the first sacrificial layer 20, the second sacrificial layer and the third sacrificial layer located on both sides of the sensing area of ​​the fixed electrode layer 40 includes but is not limited to the following situations:

[0103] Case 1: The etching fluid is a selective gaseous fluid, for example, hydrofluoric acid. The product generated by the reaction of hydrofluoric acid and silicon oxide is still gaseous. The generated product will not be deposited inside the pressure sensor 100, and no subsequent cleaning is required, which simplifies the preparation process and can effectively improve production efficiency.

[0104] Case 2: The etching medium is a selective liquid medium, such as BOE solution (ie, buffered oxide etching solution). The BOE solution is used to accurately control the etching process while avoiding unnecessary damage to surrounding materials.

[0105] It should be noted that the etching time, erosion fluid flow rate, etc. required to remove the first sacrificial layer 20, the second sacrificial layer and the third sacrificial layer located on both sides of the sensing area of ​​the fixed electrode layer 40 can be adjusted by those skilled in the art according to actual conditions and will not be described in detail in this embodiment.

[0106] According to one embodiment of the present application, the fixed electrode layer 40 includes a second insulating passivation layer 40 b , a first bare electrode layer 40 c and a third insulating passivation layer 40 d which are deposited in sequence.

[0107] Specifically, the fixed electrode layer 40 is mainly composed of a second insulating passivation layer 40b, a first bare electrode layer 40c and a third insulating passivation layer 40d. When depositing the fixed electrode layer 40, the second insulating passivation layer 40b (for example, a silicon nitride layer) can be first deposited on the upper side of the second sacrificial layer, and then the first bare electrode layer 40c (for example, a polysilicon layer) is deposited on the upper side of the second sacrificial layer. Finally, the third insulating passivation layer 40d (for example, a silicon nitride layer) is deposited on the upper side of the second sacrificial layer to obtain the fixed electrode layer 40.

[0108] In this embodiment, the deposited second insulating passivation layer 40b and the third insulating passivation layer 40d can prevent the fixed electrode layer 40 from contacting the first mobile electrode layer 30 or the second mobile electrode layer 60 to cause a short circuit, thereby ensuring the reliability of the pressure sensor 100; and the deposited second insulating passivation layer 40b and the third insulating passivation layer 40d can effectively prevent the corrosive working fluid from corroding the fixed electrode layer 40, and at the same time can effectively improve the hardness of the fixed electrode layer 40, thereby effectively preventing the fixed electrode layer 40 from being deformed, and can prevent the fixed electrode layer 40 from being attracted to the first mobile electrode layer 30 and the second mobile electrode layer 60 when the pressure sensor 100 is working, thereby ensuring the reliability of the pressure sensor 100.

[0109] In some optional examples of the present application, the first mobile electrode layer 30 includes a fourth insulating passivation layer 30b (for example, a silicon nitride layer) and a second bare electrode layer 30c (for example, a polysilicon layer) deposited in sequence. The deposited fourth insulating passivation layer 30b can ensure the structural strength of the first mobile electrode layer 30, and at the same time, can effectively prevent the corrosive working fluid from corroding the first mobile electrode layer 30, and can prevent the first mobile electrode layer 30 and the substrate 10 from being attracted to each other when the pressure sensor 100 is working, thereby ensuring the reliability of the pressure sensor 100.

[0110] In summary, according to the preparation method of the pressure sensor 100 provided in this embodiment, by setting the first release hole 30a, the second release hole 40a and the third release hole 60a, the sacrificial layers at different positions are removed at one time in one process, which simplifies the entire preparation process flow, can effectively improve production efficiency and reduce production costs; and the first mobile electrode layer 30, the fixed electrode layer 40 and the second mobile electrode layer 60 form a differential capacitor structure, and the differential capacitor structure can effectively improve the temperature stability and reliability of the pressure sensor 100.

[0111] The embodiment of the present application further provides a pressure sensor 100, which is manufactured by the manufacturing method of the pressure sensor 100 described in any of the above embodiments. Since the manufacturing method of the pressure sensor 100 according to the embodiment of the present application has the above technical effects, the pressure sensor 100 according to the embodiment of the present application also has the corresponding technical effects, which will not be described in detail in this embodiment.

[0112] The embodiment of the present application also provides a pressure sensor 100, comprising: a substrate 10, a first mobile electrode layer 30, a fixed electrode layer 40, and a second mobile electrode layer 60, which are sequentially spaced and distributed along a first direction; an insulating layer, wherein the substrate 10, the first mobile electrode layer 30, the fixed electrode layer 40, and the second mobile electrode layer 60 are connected as a whole through the insulating layer; wherein the sensing areas of the first mobile electrode layer 30, the fixed electrode layer 40, and the second mobile electrode layer 60 correspond to each other, the sensing area of ​​the first mobile electrode layer 30 is provided with a first release hole 30a, and the sensing area of ​​the fixed electrode layer 40 is provided with a first release hole 30a. The second mobile electrode layer 60 has two release holes 40a, and the sensing area of ​​the second mobile electrode layer 60 is provided with a third release hole 60a. A connecting column 50 is connected between the sensing area of ​​the first mobile electrode layer 30 and the sensing area of ​​the second mobile electrode layer 60. The connecting column 50 passes through the second release hole 40a and is separated from the inner wall thereof. The insulating layer is provided with a through groove, which corresponds to the sensing area of ​​the first mobile electrode layer 30, the fixed electrode layer 40 and the second mobile electrode layer 60, and the second mobile electrode layer 60 is provided with a blocking portion 60b for blocking the third release hole 60a, so that the second mobile electrode layer 60 can sense changes in air pressure.

[0113] In other words, if Fig.14 As shown, the pressure sensor 100 according to the embodiment of the present application is mainly composed of a substrate 10, a first mobile electrode layer 30, a fixed electrode layer 40, a second mobile electrode layer 60 and an insulating layer. The substrate 10, the first mobile electrode layer 30, the fixed electrode layer 40, and the second mobile electrode layer 60 are spaced apart and distributed along a first direction, and the first direction is the same as the thickness direction of the substrate 10, the first mobile electrode layer 30, the fixed electrode layer 40, and the second mobile electrode layer 60.

[0114] The insulating layer is fixedly connected to a side of the substrate 10 close to the first movable electrode layer 30, the first movable electrode layer 30 and the fixed electrode layer 40 are sequentially embedded in the insulating layer, the second movable electrode layer 60 is embedded in the insulating layer, or the second movable electrode layer 60 is fixedly connected to a side of the insulating layer away from the substrate 10, so that the insulating layer connects the substrate 10, the first movable electrode layer 30, the fixed electrode layer 40 and the second movable electrode layer 60 which are sequentially spaced along the first direction into a whole.

[0115] Specifically, the first mobile electrode layer 30, the fixed electrode layer 40 and the second mobile electrode layer 60 all have sensing areas, and in the first direction, the sensing areas of the first mobile electrode layer 30, the fixed electrode layer 40 and the second mobile electrode layer 60 correspond. The insulating layer is provided with through grooves corresponding to the sensing areas of each first bare electrode layer 40c, that is, when the first mobile electrode layer 30, the fixed electrode layer 40 and the second mobile electrode layer 60 are provided with n sensing areas, the insulating layer is also provided with n through grooves, so that the sensing area of ​​the first mobile electrode layer 30 and the sensing area of ​​the second mobile electrode can be deformed and moved in the first direction, so that variable capacitance is formed between the first mobile electrode layer 30 and the fixed electrode layer 40, and between the second mobile electrode layer 60 and the fixed electrode layer 40.

[0116] In addition, the first movable electrode layer 30 is provided with one or more first release holes 30a extending through the thickness direction thereof, the fixed electrode layer 40 is provided with one or more second release holes 40a extending through the thickness direction thereof, and the second movable electrode layer 60 is provided with one or more third release holes 60a extending through the thickness direction thereof. The first release holes 30a, the second release holes 40a and the third release holes 60a can flow corrosive working fluids, so that the through grooves on the insulating layer can be formed at one time through an etching process, which is beneficial to simplifying the preparation process of the pressure sensor 100, thereby facilitating improving production efficiency.

[0117] like Fig.14 As shown, a connecting column 50 is provided between the sensing areas of the first mobile electrode layer 30 and the second mobile electrode layer 60, the first end of the connecting column 50 is fixedly connected to the first mobile electrode, and the second end of the connecting column 50 passes through the second release hole 40a and is connected to the second mobile electrode, so that the first mobile electrode and the second mobile electrode can move synchronously, so that the first mobile electrode layer 30, the fixed electrode layer 40 and the second mobile electrode layer 60 form a differential capacitor structure.

[0118] It should be noted that the outer peripheral surface of the connecting column 50 is spaced apart from the inner wall surface of the second release hole 40a to allow the corrosive working medium to flow therebetween, and at least the outer material of the connecting column 50 is different from that of the insulating layer. The materials of the connecting column 50 include but are not limited to the following:

[0119] Case 1: the material of the outer side of the connecting column 50 is different from the material of the insulating layer. The material of the outer side of the connecting column 50 is silicon nitride, and the material of the inner side of the connecting column 50 and the material of the insulating layer are silicon oxide.

[0120] Case 2: the whole material of the connection column 50 is different from the material of the insulating layer. For example, the material of the connection column 50 is silicon nitride, and the material of the insulating layer is silicon oxide.

[0121] The silicon nitride on the outside of the connecting column 50 can be used as a passivation layer, which will not react with the corrosive medium that corrodes the insulating layer. Therefore, when the groove is formed by the etching process, the corrosive medium will not damage the structure of the connecting column 50, and the connecting column 50 will not affect the flow of the corrosive medium to the side of the fixed electrode layer 40 close to the first movable electrode.

[0122] The third release hole 60a on the second mobile electrode layer 60 can be blocked by the blocking portion 60b, and after blocking, a sealed cavity can be formed between the sensing area of ​​the second mobile electrode layer 60 and the substrate 10, so that the second mobile electrode layer 60 can sense changes in air pressure and move with changes in air pressure.

[0123] Thus, according to the pressure sensor 100 of this embodiment, the through groove on the insulating layer can be formed once by an etching process through the first release hole 30a, the second release hole 40a and the third release hole 60a, and the arrangement is convenient for production and manufacturing, which is conducive to improving the production efficiency of the air sensor. Moreover, the first mobile electrode layer 30 is connected to the second mobile electrode layer 60 through the connection column 50, so that the first mobile electrode layer 30, the fixed electrode layer 40 and the second mobile electrode layer 60 form a differential capacitor structure, which can effectively improve the temperature stability and reliability of the pressure sensor 100.

[0124] In some optional examples of the present application, the blocking portion 60b includes a silicon nitride material layer, a silicon oxide material layer and an electrode material layer arranged in sequence from bottom to top; or, the blocking portion 60b includes a silicon oxide material layer, a silicon nitride material layer and an electrode material layer arranged in sequence from bottom to top.

[0125] According to one embodiment of the present application, the number of the first mobile electrode layer 30, the fixed electrode layer 40 and the second mobile electrode layer 60 are all two, the positions of the two first mobile electrode layers 30, the two fixed electrode layers 40 and the two second mobile electrode layers 60 correspond one to one, and the variable capacitors formed by the two first mobile electrode layers 30, the two fixed electrode layers 40 and the two second mobile electrode layers 60 are connected through conductive interconnects to form a Wheatstone bridge circuit.

[0126] like Fig.17As shown, in this embodiment, the first second mobile electrode layer 60 and the first fixed electrode layer 40 form a variable capacitor C1, the first first mobile electrode layer 30 and the first fixed electrode layer 40 form a variable capacitor C2, the second second mobile electrode layer 60 and the second fixed electrode layer 40 form a variable capacitor C3, and the second first mobile electrode layer 30 and the second fixed electrode layer 40 form a variable capacitor C4. The variable capacitor C1, the variable capacitor C2, the variable capacitor C3 and the variable capacitor C4 are electrically connected through conductive interconnects to form a Wheatstone bridge circuit, which can effectively improve the nonlinearity of the capacitive sensor and improve the temperature stability and reliability.

[0127] In some embodiments of the present application, the first movable electrode layer 30 includes a plurality of spaced-apart first sub-movable electrodes 31, the fixed electrode layer 40 includes a plurality of spaced-apart sub-fixed electrodes 41, and the second movable electrode layer 60 includes a plurality of spaced-apart second sub-movable electrodes 61, wherein each first sub-movable electrode 31, each sub-fixed electrode 41, and each second sub-movable electrode 61 has a sensing area, and the positions of the plurality of first sub-movable electrodes 31, the plurality of sub-fixed electrodes 41, and the plurality of second sub-movable electrodes 61 correspond one to one; the variable capacitors formed by the plurality of first sub-movable electrodes 31 and the plurality of sub-fixed electrodes 41 are connected in parallel through conductive interconnections, and the variable capacitors formed by the plurality of second sub-movable electrodes 61 and the plurality of sub-fixed electrodes 41 are connected in parallel through conductive interconnections.

[0128] Specifically, Fig.16 As shown, the first movable electrode layer 30 includes a plurality of first sub-movable electrodes 31, the fixed electrode layer 40 includes a plurality of sub-fixed electrodes 41, and the second movable electrode layer 60 includes a plurality of second sub-movable electrodes 61. The middle area of ​​each first sub-movable electrode 31, each sub-fixed electrode 41, and each second sub-movable electrode 61 is configured as a sensing area, and the positions of the plurality of first sub-movable electrodes 31, the plurality of sub-fixed electrodes 41, and the plurality of second sub-movable electrodes 61 correspond one to one, so that the plurality of second sub-movable electrodes 61 and the plurality of sub-fixed electrodes 41 form a plurality of first sub-variable capacitors, and the plurality of second sub-movable electrodes 61 and the plurality of sub-fixed electrodes 41 form a plurality of second sub-variable capacitors.

[0129] The multiple first sub-variable capacitors formed by the first second mobile electrode layer 60 and the first fixed electrode layer 40 can be connected in parallel through conductive interconnects to form a variable capacitor C1, the multiple second sub-variable capacitors formed by the first first mobile electrode layer 30 and the first fixed electrode layer 40 can be connected in parallel to form a variable capacitor C2, the multiple first sub-variable capacitors formed by the second second mobile electrode layer 60 and the second fixed electrode layer 40 can be connected in parallel to form a variable capacitor C3, and the multiple second sub-variable capacitors formed by the second first mobile electrode layer 30 and the second fixed electrode layer 40 can be connected in parallel to form a variable capacitor C4.

[0130] In this embodiment, the variable capacitors C1, C2, C3 and C4 are all formed by connecting a plurality of sub-variable capacitors in parallel. When one of the sub-variable capacitors is damaged, the variable capacitors can still be used normally, thereby effectively improving the reliability of the pressure sensor 100.

[0131] In addition, the pressure sensor 100 of this embodiment can be manufactured by the manufacturing method described in any of the above embodiments, and the first sacrificial layer 20, the second sacrificial layer and the third sacrificial layer form the insulating layer of this embodiment.

[0132] The embodiment of the present application also provides an electronic device, including the pressure sensor 100 described in any of the above embodiments. Since the method for preparing the pressure sensor 100 according to the embodiment of the present application has the above technical effects, the electronic device according to the embodiment of the present application also has the corresponding technical effects, which will not be described in detail in this embodiment.

[0133] Although some specific embodiments of the present application have been described in detail by way of example, it should be understood by those skilled in the art that the above examples are only for illustration, not for limiting the scope of the present application. It should be understood by those skilled in the art that the above embodiments may be modified without departing from the scope and spirit of the present application. The scope of the present application is defined by the appended claims.

Claims

1. A method for preparing a pressure sensor, characterized in that: include: Depositing a first sacrificial layer, a first movable electrode layer, a second sacrificial layer, a fixed electrode layer and a third sacrificial layer in sequence on the substrate; Wherein, the sensing area of ​​the first movable electrode layer is provided with a first release hole, and the sensing area of ​​the fixed electrode layer is provided with a second release hole; Etching a first sink hole extending to the surface of the sensing area of ​​the first mobile electrode layer on the third sacrificial layer, and depositing a connecting column in the first sink hole; Depositing a second mobile electrode layer on the third sacrificial layer, wherein a third release hole is provided in a sensing region of the second mobile electrode layer; Using an etching process to remove the first sacrificial layer, the second sacrificial layer and the third sacrificial layer located on both sides of the sensing area of ​​the fixed electrode layer through the first release hole, the second release hole and the third release hole; The third release hole is blocked to obtain a pressure sensor.

2. The preparation method according to claim 1, characterized in that: The diameter of the first sinking hole is smaller than the diameter of the second releasing hole, and the first sinking hole is located inside the second releasing hole.

3. The preparation method according to claim 1, characterized in that: The number of the deposited first mobile electrode layer, the fixed electrode layer and the second mobile electrode layer is two each. The positions of the two first movable electrode layers, the two fixed electrode layers and the two second movable electrode layers correspond one to one.

4. The preparation method according to claim 1 or 3, characterized in that: Also includes: Before depositing the second sacrificial layer, the first mobile electrode layer is patterned to obtain a plurality of first sub-mobile electrodes spaced apart from each other. Before depositing the third sacrificial layer, the fixed electrode layer is patterned to obtain a plurality of spaced-apart sub-fixed electrodes. Before the etching process is performed, the second mobile electrode layer is patterned to obtain a plurality of separated second sub-mobile electrodes; Each of the first sub-movable electrodes, each of the sub-fixed electrodes and each of the second sub-movable electrodes has a sensing area. The positions of the plurality of first movable sub-electrodes, the plurality of fixed sub-electrodes and the plurality of second movable sub-electrodes correspond one to one.

5. The preparation method according to claim 1, characterized in that: The step of depositing a connecting column in the first sink hole comprises: Depositing a material layer on the upper side of the third sacrificial layer so that the material layer is deposited in each of the first sink holes; The material layer on the upper surface of the third sacrificial layer is removed to obtain a connecting column.

6. The preparation method according to claim 5, characterized in that: The step of depositing a material layer on the upper side of the third sacrificial layer comprises: Depositing a first material layer on the upper side of the third sacrificial layer so that the first material layer covers the inner wall surface of each of the first sink holes; Depositing a second material layer on the upper side of the third sacrificial layer so that the second material layer fills the first sink hole; removing the first material layer and the second material layer on the upper surface of the third sacrificial layer; Depositing a third material layer on the upper side of the third sacrificial layer so that the third material layer covers the upper end of each of the first sink holes; Wherein, the first material layer and the third material layer are configured as a first insulating passivation layer.

7. The preparation method according to claim 4, characterized in that: Also includes: etching a second sink hole on the upper side of the third sacrificial layer; Depositing a conductive interconnection line on the upper side of the third sacrificial layer to form an extraction electrode; Wherein, the conductive interconnection line is connected to the first movable electrode layer, the fixed electrode layer and / or the second movable electrode layer in the second sink hole and / or on the upper surface of the second movable electrode layer.

8. The preparation method according to claim 7, characterized in that: The variable capacitors formed by the two first movable electrode layers, the two fixed electrode layers and the two second movable electrode layers are connected through the conductive interconnection lines to form a Wheatstone bridge circuit.

9. The preparation method according to claim 1, characterized in that: The etching medium used in the etching process is a selective gaseous medium or a selective liquid medium.

10. The preparation method according to claim 1, characterized in that: The fixed electrode layer includes a second insulating passivation layer, a first bare electrode layer and a third insulating passivation layer which are deposited in sequence.

11. A pressure sensor, characterized in that: The pressure sensor is manufactured by the manufacturing method according to any one of claims 1 to 10.

12. A pressure sensor, characterized in that: include: A substrate, a first movable electrode layer, a fixed electrode layer, and a second movable electrode layer are sequentially spaced apart along a first direction; an insulating layer, wherein the substrate, the first movable electrode layer, the fixed electrode layer and the second movable electrode layer are connected as a whole through the insulating layer; The first mobile electrode layer, the fixed electrode layer and the second mobile electrode layer have corresponding sensing areas. The sensing area of ​​the first movable electrode layer is provided with a first release hole, the sensing area of ​​the fixed electrode layer is provided with a second release hole, and the sensing area of ​​the second movable electrode layer is provided with a third release hole. A connecting column is connected between the sensing area of ​​the first mobile electrode layer and the sensing area of ​​the second mobile electrode layer, and the connecting column passes through the second release hole and is spaced apart from the inner wall thereof; The insulating layer is provided with a through groove, and the through groove corresponds to the sensing area of ​​the first movable electrode layer, the fixed electrode layer and the second movable electrode layer. The second movable electrode layer is provided with a blocking portion for blocking the third release hole, so that the second movable electrode layer can sense the change of air pressure.

13. The pressure sensor according to claim 12, characterized in that: The material of at least the outer side of the connection column is different from the material of the insulation layer.

14. The pressure sensor according to claim 12, characterized in that: The number of the first movable electrode layer, the number of the fixed electrode layer and the second movable electrode layer are all two, The positions of the two first movable electrode layers, the two fixed electrode layers and the two second movable electrode layers correspond one to one, The variable capacitors formed by the two first movable electrode layers, the two fixed electrode layers and the two second movable electrode layers are connected through conductive interconnection lines to form a Wheatstone bridge circuit.

15. The pressure sensor according to claim 12 or 14, characterized in that: The first mobile electrode layer includes a plurality of spaced-apart first sub-mobile electrodes, the fixed electrode layer includes a plurality of spaced-apart sub-fixed electrodes, and the second mobile electrode layer includes a plurality of spaced-apart second sub-mobile electrodes. Each of the first sub-movable electrodes, each of the sub-fixed electrodes and each of the second sub-movable electrodes has a sensing area. The positions of the plurality of the first movable sub-electrodes, the plurality of the sub-fixed electrodes and the plurality of the second movable sub-electrodes correspond one to one; The variable capacitors formed by the plurality of the first sub-movable electrodes and the plurality of the sub-fixed electrodes are connected in parallel through conductive interconnection lines. The variable capacitors formed by the plurality of the second sub-movable electrodes and the plurality of the sub-fixed electrodes are connected in parallel through conductive interconnection lines.

16. An electronic device, characterized in that: The pressure sensor comprises the pressure sensor according to claim 11, or the pressure sensor according to any one of claims 12 to 15.

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