MEMS device and manufacturing method therefor, and method for reading output signal of MEMS device

Abstract

The present application provides a MEMS device and a manufacturing method therefor, and a method for reading an output signal of the MEMS device. The MEMS device comprises: a first substrate, wherein a back cavity is formed in the first substrate; a first movable film layer, a first isolation layer, a first fixed electrode layer, a second isolation layer, a third movable film layer, a fifth isolation layer, a fourth movable film layer, a fourth isolation layer, a second fixed electrode layer, a third isolation layer, and a second movable film layer located on the first substrate; a first cavity located between the first movable film layer and the third movable film layer; a second cavity located between the second movable film layer and the fourth movable film layer; a first connecting column located in the first cavity and connecting the third movable film layer and the first movable film layer; a second connecting column located in the second cavity and connecting the second movable film layer and the fourth movable film layer; and release holes passing through the third movable film layer, the fifth isolation layer and the fourth movable film layer.

Description

MEMS devices and their manufacturing methods, and methods for reading the output signals of MEMS devices. Cross-references to related applications

[0001] This patent application claims priority to Chinese Patent Application No. 202411564197.1, filed on November 4, 2024, entitled "MEMS Device and Manufacturing Method Thereof, Method for Reading Output Signal of MEMS Device", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of semiconductor technology, and more specifically to a MEMS device and its manufacturing method, and a method for reading the output signal of a MEMS device. Background Technology

[0003] With the continuous development of semiconductor technology, MEMS microphones, which are fabricated based on micro-electro-mechanical systems (MEMS) technology, are widely used in the sensor product market due to their advantages such as small size, low cost and stable performance compared with traditional microphones.

[0004] A typical condenser MEMS microphone consists of a single-layer diaphragm and a single-layer backplate. The single-layer diaphragm and the single-layer backplate constitute a capacitor structure. When an external sound signal acts on the diaphragm, the diaphragm vibrates, causing a change in capacitance. The change in capacitance is used for calculation and operation to complete the conversion between sound signals and electrical signals. Summary of the Invention

[0005] The summary section introduces a series of simplified concepts, which will be further explained in detail in the detailed description section. This summary section is not intended to limit the key and essential technical features of the claimed technical solution, nor is it intended to determine the scope of protection of the claimed technical solution.

[0006] This application provides a MEMS device, including:

[0007] A first substrate, wherein a back cavity is formed therethrough the first substrate;

[0008] A first movable film layer is located on the first substrate, and the back cavity exposes a portion of the surface of the first movable film layer;

[0009] A first isolation layer is located on a portion of the first movable membrane layer;

[0010] The first fixed electrode layer is located on the first isolation layer;

[0011] A second isolation layer is located on a portion of the first fixed electrode layer;

[0012] The third movable membrane layer is located on the second isolation layer;

[0013] The fifth isolation layer is located on the third movable membrane layer;

[0014] The fourth movable membrane layer is located on the fifth isolation layer;

[0015] The fourth isolation layer is located on a portion of the fourth movable membrane layer;

[0016] The second fixed electrode layer is located on the fourth isolation layer;

[0017] A third isolation layer is located on a portion of the second fixed electrode layer;

[0018] The second movable membrane layer is located on the third isolation layer;

[0019] The first cavity is located between the first movable membrane layer and the third movable membrane layer;

[0020] The second cavity is located between the second movable membrane layer and the fourth movable membrane layer;

[0021] Multiple first connecting posts are located in the first cavity, and the upper and lower ends of the first connecting posts are respectively connected to the third movable membrane layer and the first movable membrane layer;

[0022] Multiple second connecting posts are located in the second cavity, and the upper and lower ends of the second connecting posts are respectively connected to the second movable membrane layer and the fourth movable membrane layer;

[0023] Multiple release holes penetrate the third movable membrane layer, the fifth isolation layer, and the fourth movable membrane layer. The first cavity and the second cavity are interconnected through the release holes to form a cavity.

[0024] For example, the first movable film layer and the first fixed electrode layer constitute a first variable capacitor structure, the second movable film layer and the second fixed electrode layer constitute a second variable capacitor structure, the third movable film layer and the first fixed electrode layer constitute a third variable capacitor structure, and the fourth movable film layer and the second fixed electrode layer constitute a fourth variable capacitor structure, wherein the phase difference of the output signals of adjacent variable capacitor structures is 180°.

[0025] For example, the structure of the third movable film layer, the fifth isolation layer and the fourth movable film layer includes any one of the following: Poly / A-Si / poly, Poly / SiN / Poly, Poly / SiO2 / Poly, Poly / SiN / A-si / SiN / Poly, Poly / A-si / SiN / A-si / Poly, Poly / SiO2 / A-si / SiO2 / Poly, Poly / A-si / SiO2 / A-si / / Poly, Poly / SiN / SiO2 / SiN / Poly and Poly / SiO2 / SiN / SiO2 / Poly;

[0026] The fifth isolation layer is made of TiO2 or TaO2, and the third and fourth movable film layers are made of silicon, germanium, metal, second-generation semiconductor or third-generation semiconductor.

[0027] For example, the first connecting post and the second connecting post are cylindrical, and the diameter of the first connecting post and the second connecting post ranges from 1um to 3um.

[0028] For example, the materials of the first connecting post and the second connecting post include SiN, SiO2 wrapped with SiN, or Poly wrapped with SiN.

[0029] For example, the spacing between the first movable film layer and the first fixed electrode layer, between the third movable film layer and the first fixed electrode layer, between the second movable film layer and the second fixed electrode layer, and between the fourth movable film layer and the second fixed electrode layer ranges from 1µm to 3µm.

[0030] For example, the thicknesses of the first movable film layer, the second movable film layer, the third movable film layer, and the fourth movable film layer range from 0.1µm to 1.5µm.

[0031] For example, the thickness of the MEMS device, excluding the substrate, ranges from 8µm to 15µm.

[0032] Exemplarily, it further includes: a first metal wiring layer, a second metal wiring layer, a third metal wiring layer, a fourth metal wiring layer, a fifth metal wiring layer, and a sixth metal wiring layer, wherein the first metal wiring layer is electrically connected to the first movable film layer, the second metal wiring layer is electrically connected to the second movable film layer, the third metal wiring layer is electrically connected to the third movable film layer, the fourth metal wiring layer is electrically connected to the fourth movable film layer, the fifth metal wiring layer is electrically connected to the first fixed electrode layer, and the sixth metal wiring layer is electrically connected to the second fixed electrode layer.

[0033] Exemplarily, it also includes a first pad located on the first movable film layer, a second pad located on the second movable film layer, a third pad located on the third movable film layer, a fourth pad located on the fourth movable film layer, a fifth pad located on the first fixed electrode layer, and a sixth pad located on the second fixed electrode layer.

[0034] For example, it further includes: a first support layer located between the first fixed electrode layer and the first isolation layer, a second support layer located between the first fixed electrode layer and the second isolation layer, a third support layer located between the second fixed electrode layer and the third isolation layer, and a fourth support layer located between the second fixed electrode layer and the fourth isolation layer.

[0035] Another aspect of this application provides a method for manufacturing a MEMS device, comprising:

[0036] A first substrate is provided, on the first surface of which a first movable film layer, a first isolation layer, a first fixed electrode layer, a second isolation layer and a first bonding layer are sequentially formed. A first cavity is formed between the first bonding layer and the first substrate. A plurality of first connecting pillars are formed in the first cavity. The upper and lower ends of the first connecting pillars are respectively connected to the first bonding layer and the first movable film layer. A plurality of first release holes are formed in the first bonding layer that expose the first cavity.

[0037] A second substrate is provided, on the first surface of which a second movable film layer, a third isolation layer, a second fixed electrode layer, a fourth isolation layer and a second bonding layer are sequentially formed. A second cavity is formed between the second bonding layer and the second substrate. A plurality of second connecting pillars are formed in the second cavity. The upper and lower ends of the second connecting pillars are respectively connected to the second bonding layer and the second movable film layer. A plurality of second release holes are formed in the second bonding layer that expose the second cavity.

[0038] The first bonding layer and the second bonding layer are bonded together so that the first bonding layer and the second bonding layer constitute a third movable film layer, a fifth isolation layer and a fourth movable film layer connected to the first connecting post, which are stacked and connected to the first connecting post. The first cavity and the second cavity are interconnected through the first release hole and the second release hole to form a cavity.

[0039] Remove the second substrate to expose the second movable film layer;

[0040] The portion of the first substrate corresponding to the cavity is removed from the second surface of the first substrate to form a back cavity that exposes a portion of the first movable film layer.

[0041] For example, the first bonding layer includes a first sub-movable film layer, and the second bonding layer includes the fourth movable film layer, the fifth isolation layer located on the fourth movable film layer, and a second sub-movable film layer located on the fifth isolation layer. In the bonding step, the first sub-movable film layer and the second sub-movable film layer are bonded together, and the first sub-movable film layer and the second sub-movable film layer constitute the third movable film layer; or,

[0042] The first bonding layer includes the third movable film layer, and the second bonding layer includes the fourth movable film layer and the fifth isolation layer located on the fourth movable film layer. In the bonding step, the fifth isolation layer and the third movable film layer are bonded together; or...

[0043] The first bonding layer includes the third movable film layer and a first sub-isolation layer located on the third movable film layer; the second bonding layer includes the fourth movable film layer and a second sub-isolation layer located on the fourth movable film layer; in the bonding step, the first sub-isolation layer and the second sub-isolation layer are bonded together, and the first sub-isolation layer and the second sub-isolation layer constitute the fifth isolation layer; or...

[0044] The first bonding layer includes the third movable film layer and the fifth isolation layer located on the third movable film layer; the second bonding layer includes the fourth movable film layer; and in the bonding step, the fifth isolation layer and the fourth movable film layer are bonded together; or,

[0045] The first bonding layer includes the third movable film layer, the fifth isolation layer located on the third movable film layer, and the third sub-movable film layer located on the fifth isolation layer. The second bonding layer includes the fourth sub-movable film layer. In the bonding step, the third sub-movable film layer and the fourth sub-movable film layer are bonded together, and the third sub-movable film layer and the fourth sub-movable film layer constitute the fourth movable film layer.

[0046] For example, a low-temperature bonding process is used to perform the bonding step.

[0047] This application further provides a method for reading the output signal of a MEMS device, including:

[0048] Provide the aforementioned MEMS device or provide a MEMS device manufactured using the aforementioned manufacturing method;

[0049] Read the output signal of the MEMS device;

[0050] The process of reading the output signals of MEMS devices includes:

[0051] A first bias voltage is applied to the first fixed electrode layer of the MEMS device, and a second bias voltage is applied to the second fixed electrode layer of the MEMS device;

[0052] Connect the first movable diaphragm layer and the fourth movable diaphragm layer to the non-inverting input terminal of the first amplifier, and connect the second movable diaphragm layer and the third movable diaphragm layer to the inverting input terminal of the first amplifier; or connect the first movable diaphragm layer and the fourth movable diaphragm layer to the inverting input terminal of the first amplifier, and connect the second movable diaphragm layer and the third movable diaphragm layer to the non-inverting input terminal of the first amplifier.

[0053] Read the signal at the output of the first amplifier;

[0054] Alternatively, read the output signals of the MEMS device, including:

[0055] A first bias voltage is applied to the first movable film layer and the fourth movable film layer, and a second bias voltage is applied to the second movable film layer and the third movable film layer;

[0056] The first fixed electrode layer and the second fixed electrode layer are respectively connected to the non-inverting input terminal and the inverting input terminal of the first amplifier;

[0057] Read the signal at the output of the first amplifier;

[0058] Alternatively, read the output signals of the MEMS device, including:

[0059] A first bias voltage is applied to the first fixed electrode layer, and a second bias voltage is applied to the second fixed electrode layer;

[0060] The second movable diaphragm layer and the fourth movable diaphragm layer are respectively connected to the non-inverting input terminal and the inverting input terminal of the first amplifier, and the first movable diaphragm layer or the third movable diaphragm layer is connected to the input terminal of the second amplifier; or, the first movable diaphragm layer and the third movable diaphragm layer are respectively connected to the non-inverting input terminal and the inverting input terminal of the first amplifier, and the second movable diaphragm layer or the fourth movable diaphragm layer is connected to the input terminal of the second amplifier.

[0061] Read the signals from the output terminals of the first amplifier and the second amplifier.

[0062] The MEMS device and its manufacturing method, and the method for reading the output signal of the MEMS device according to the embodiments of this application, form four movable film layers and two fixed electrode layers. The four movable film layers and two fixed electrode layers form multiple variable capacitor structures. The multiple variable capacitor structures can output higher capacitance values, thereby improving the sensitivity and signal-to-noise ratio of the device. Attached Figure Description

[0063] The following drawings, which are incorporated herein by reference and are used to understand this application, illustrate embodiments of the invention and their descriptions to explain the principles of the invention.

[0064] In the attached image:

[0065] Figure 1 shows a flowchart of a method for manufacturing a MEMS device according to an exemplary embodiment of this application;

[0066] Figures 2A-2C show schematic cross-sectional views of the MEMS device obtained by sequentially implementing a manufacturing method of a MEMS device according to an exemplary embodiment of this application;

[0067] Figures 3A-3C show schematic cross-sectional views of the MEMS device obtained by sequentially implementing a method for manufacturing a MEMS device according to another exemplary embodiment of this application;

[0068] Figures 4A-4C show schematic cross-sectional views of the MEMS device obtained by sequentially implementing a method for manufacturing a MEMS device according to another exemplary embodiment of this application.

[0069] Figures 5A-5C show schematic cross-sectional views of the MEMS device obtained by sequentially implementing a method for manufacturing a MEMS device according to another exemplary embodiment of this application.

[0070] Figures 6A-6C show schematic cross-sectional views of the MEMS device obtained by sequentially implementing a method for manufacturing a MEMS device according to another exemplary embodiment of this application.

[0071] Figures 7A-7D show schematic cross-sectional views of the MEMS device obtained by sequentially implementing a manufacturing method of a MEMS device according to another exemplary embodiment of this application;

[0072] Figure 8 shows a cross-sectional schematic diagram of a MEMS device obtained by sequentially implementing a manufacturing method of a MEMS device according to an exemplary embodiment of this application.

[0073] Figure 9 shows a cross-sectional schematic diagram of a MEMS device obtained by sequentially implementing a manufacturing method of a MEMS device according to another exemplary embodiment of this application;

[0074] Figure 10 shows a schematic diagram of the circuit connection for reading the output signal of a MEMS device according to an exemplary embodiment of this application;

[0075] Figure 11 shows a schematic diagram of the circuit connection for reading the output signal of a MEMS device according to another exemplary embodiment of this application;

[0076] Figure 12 shows a schematic diagram of the circuit connection for reading the output signal of a MEMS device in another exemplary embodiment of this application;

[0077] Figure 13 shows a schematic diagram of the circuit connection for reading the output signal of a MEMS device in another exemplary embodiment of this application.

[0078] Explanation of reference numerals in the attached figures:

[0079] 210-First substrate, 211-First movable film layer, 212-First fixed electrode layer, 213-First cavity, 214-First connecting post, 215-First release hole, 216-Third movable film layer, 2161-First sub-movable film layer, 2162-Second sub-movable film layer, 217-First support layer, 218-Second support layer, 219-Back cavity, 220-Second substrate, 221-Second movable film layer, 222-Second fixed electrode layer, 223-Second cavity, 224-Second connecting post, 225-Second release hole, 226-Fourth movable film layer, 2261-Third sub-movable film layer, 2262-Fourth sub-movable film layer, 227-Third support layer, 228-Fourth support layer, 230-First isolation layer 240 - Second isolation layer, 250 - Third isolation layer, 260 - Fourth isolation layer, 270 - Fifth isolation layer, 2701 - First sub-isolation layer, 27011 - First SiN layer, 27012 - First A-Si layer, 27021 - Second SiN layer, 27022 - Second A-Si layer, 2702 - Second sub-isolation layer, 280 - Sixth isolation layer, 281 - First metal wiring layer, 282 - Second metal wiring layer, 283 - Third metal wiring layer, 284 - Fourth metal wiring layer, 285 - Fifth metal wiring layer, 286 - Sixth metal wiring layer, 291 - First pad, 292 - Second pad, 293 - Third pad, 294 - Fourth pad, 295 - Fifth pad, 296 - Sixth pad. Detailed Implementation

[0080] The present application will now be described more fully with reference to the accompanying drawings, in which embodiments of the present application are illustrated. However, the present application can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, providing these embodiments will make the disclosure thorough and complete, and will fully convey the scope of the present application to those skilled in the art. In the drawings, for clarity, the dimensions and relative dimensions of layers and regions may be exaggerated. The same reference numerals denote the same elements throughout.

[0081] It should be understood that when an element or layer is referred to as "on," "adjacent to," "connected to," or "coupled to" other elements or layers, it may be directly on, adjacent to, connected to, or coupled to other elements or layers, or there may be intervening elements or layers. Conversely, when an element is referred to as "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc., may be used to describe various elements, components, areas, layers, and / or portions, these elements, components, areas, layers, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component, area, layer, or portion from another element, component, area, layer, or portion. Therefore, without departing from the teachings of this application, the first element, component, area, layer, or portion discussed below may be referred to as the second element, component, area, layer, or portion.

[0082] Spatial relation terms such as “below,” “under,” “below,” “under,” “above,” “above,” etc., are used herein for convenience of description to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relation terms are intended to also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, then the element or feature described as “below” or “under” the other element or feature will be oriented “above” the other element or feature. Therefore, the exemplary terms “below” and “under” can include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or otherwise) and the spatial descriptive terms used herein will be interpreted accordingly.

[0083] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. When used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprise” and / or “comprising,” when used in this specification, identify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. When used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0084] Embodiments of the application are described herein with reference to cross-sectional views illustrating ideal embodiments (and intermediate structures). Thus, variations from the shapes shown can be anticipated due to, for example, manufacturing techniques and / or tolerances. Therefore, embodiments of the application should not be limited to the specific shapes of the regions shown herein, but include shape deviations due to, for example, manufacturing processes. For example, implantation regions shown as rectangular typically have rounded or curved features at their edges and / or implantation concentration gradients, rather than a binary change from implantation regions to non-implantation regions. Similarly, buried regions formed by implantation can result in some implantation in the region between the buried region and the surface traversed during implantation. Therefore, the regions shown in the figures are substantially schematic, and their shapes are not intended to show the actual shapes of the regions of the device and are not intended to limit the scope of the application.

[0085] Unless otherwise defined, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art. It will also be understood that terms as defined in commonly used dictionaries shall be interpreted as having a meaning consistent with their meaning in the relevant field and / or the context of this specification, and not as in an ideal or overly formal sense, unless expressly defined herein.

[0086] To fully understand this application, detailed steps and structures will be presented in the following description to illustrate the technical solutions proposed in this application. Preferred embodiments of this application are described in detail below; however, in addition to these detailed descriptions, this application may have other implementation methods.

[0087] In view of the aforementioned technical problems, this application proposes a MEMS device, comprising:

[0088] A first substrate, wherein a back cavity is formed therethrough the first substrate;

[0089] A first movable film layer is located on the first substrate, and the back cavity exposes a portion of the surface of the first movable film layer;

[0090] A first isolation layer is located on a portion of the first movable membrane layer;

[0091] The first fixed electrode layer is located on the first isolation layer;

[0092] A second isolation layer is located on a portion of the first fixed electrode layer;

[0093] The third movable membrane layer is located on the second isolation layer;

[0094] The fifth isolation layer is located on the third movable membrane layer;

[0095] The fourth movable membrane layer is located on the fifth isolation layer;

[0096] The fourth isolation layer is located on a portion of the fourth movable membrane layer;

[0097] The second fixed electrode layer is located on the fourth isolation layer;

[0098] A third isolation layer is located on a portion of the second fixed electrode layer;

[0099] The second movable membrane layer is located on the third isolation layer;

[0100] The first cavity is located between the first movable membrane layer and the third movable membrane layer;

[0101] The second cavity is located between the second movable membrane layer and the fourth movable membrane layer;

[0102] Multiple first connecting posts are located in the first cavity, and the upper and lower ends of the first connecting posts are respectively connected to the third movable membrane layer and the first movable membrane layer;

[0103] Multiple second connecting posts are located in the second cavity, and the upper and lower ends of the second connecting posts are respectively connected to the second movable membrane layer and the fourth movable membrane layer;

[0104] Multiple release holes penetrate the third movable membrane layer, the fifth isolation layer, and the fourth movable membrane layer. The first cavity and the second cavity are interconnected through the release holes to form a cavity.

[0105] The MEMS device of this application has four movable film layers and two fixed electrode layers. The four movable film layers and two fixed electrode layers form multiple variable capacitor structures. The multiple variable capacitor structures can output higher capacitance values, thereby improving the sensitivity and signal-to-noise ratio of the device.

[0106] Example 1

[0107] The manufacturing method of the MEMS device of this application will now be described in detail with reference to Figures 1 to 9. Figure 1 shows a flowchart of a manufacturing method of a MEMS device according to an exemplary embodiment of this application; Figures 2A-2C show cross-sectional schematic diagrams of MEMS devices obtained by sequentially implementing the manufacturing method of a MEMS device according to an exemplary embodiment of this application; Figures 3A-3C show cross-sectional schematic diagrams of MEMS devices obtained by sequentially implementing the manufacturing method of another exemplary embodiment of this application; Figures 4A-4C show cross-sectional schematic diagrams of MEMS devices obtained by sequentially implementing the manufacturing method of another exemplary embodiment of this application; Figures 5A-5C show the manufacturing method of a MEMS device according to another exemplary embodiment of this application... Figure 6A-6C show cross-sectional schematic diagrams of MEMS devices obtained by sequentially implementing the manufacturing method of another exemplary embodiment of the present application; Figure 7A-7D show cross-sectional schematic diagrams of MEMS devices obtained by sequentially implementing the manufacturing method of another exemplary embodiment of the present application; Figure 8 shows cross-sectional schematic diagrams of MEMS devices obtained by sequentially implementing the manufacturing method of an exemplary embodiment of the present application; Figure 9 shows cross-sectional schematic diagrams of MEMS devices obtained by sequentially implementing the manufacturing method of another exemplary embodiment of the present application.

[0108] MEMS devices can be any suitable devices known to those skilled in the art, such as MEMS microphones or MEMS pressure sensors. In this embodiment, the technical solution of this application is explained and illustrated mainly by taking the case of a MEMS microphone as the MEMS device.

[0109] For example, the method for manufacturing the MEMS device of this application includes the following steps:

[0110] First, step S1 is performed to provide a first substrate. A first movable film layer, a first isolation layer, a first fixed electrode layer, a second isolation layer, and a first bonding layer are sequentially formed on the first surface of the first substrate. A first cavity is formed between the first bonding layer and the first substrate. A plurality of first connecting pillars are formed in the first cavity. The upper and lower ends of the first connecting pillars are respectively connected to the first bonding layer and the first movable film layer. A plurality of first release holes exposing the first cavity are formed in the first bonding layer.

[0111] In one example, as shown in Figures 2A, 3A, 4A, 5A, and 6A, the first substrate 210 is a bulk silicon substrate, which may include at least one of the following materials: Si, Ge, SiGe, SiC, SiGeC, InAs, GaAs, InP, InGaAs, or other III / V compound semiconductors. Alternatively, the first substrate 210 may also include silicon-on-insulator (SOI), silicon-on-insulator stacked (SSOI), silicon-on-insulator stacked germanium (S-SiGeOI), silicon-on-insulator germanium (SiGeOI), or germanium-on-insulator (GeOI), etc. Although several examples of materials that can form the first substrate 210 have been described herein, any material that can serve as a semiconductor substrate falls within the spirit and scope of this application.

[0112] In one example, as shown in Figures 2A, 3A, 4A, 5A and 6A, a first movable film layer 211, a first isolation layer 230, a first fixed electrode layer 212, a second isolation layer 240 and a first bonding layer are sequentially formed on the first surface of the first substrate 210.

[0113] In one example, as shown in Figures 2A, 3A, 4A, 5A, and 6A, a first cavity 213 is formed between the first bonding layer and the first substrate 210. A plurality of first connecting pillars 214 are formed within the first cavity 213. The upper and lower ends of each first connecting pillar 214 are connected to the first bonding layer and the first movable film layer 211, respectively. A plurality of first release holes 215 are formed in the first bonding layer, exposing the first cavity 213. Exemplarily, the material of the first connecting pillars 214 includes, but is not limited to, materials such as SiCN, SiN, SiC, SiON, SiO2 encapsulated by SiN, Poly encapsulated by SiN, etc., or may be other insulating materials; this application does not impose any limitations on this.

[0114] Next, step S2 is performed to provide a second substrate. A second movable film layer, a third isolation layer, a second fixed electrode layer, a fourth isolation layer, and a second bonding layer are sequentially formed on the first surface of the second substrate. A second cavity is formed between the second bonding layer and the second substrate. A plurality of second connecting pillars are formed in the second cavity. The upper and lower ends of the second connecting pillars are respectively connected to the second bonding layer and the second movable film layer. A plurality of second release holes exposing the second cavity are formed in the second bonding layer.

[0115] In one example, as shown in Figures 2B, 3B, 4B, 5B, and 6B, the second substrate 220 is a bulk silicon substrate, which may include at least one of the following materials: Si, Ge, SiGe, SiC, SiGeC, InAs, GaAs, InP, InGaAs, or other III / V compound semiconductors. Alternatively, the second substrate 220 may also include silicon-on-insulator (SOI), silicon-on-insulator stacked (SSOI), silicon-on-insulator stacked germanium (S-SiGeOI), silicon-on-insulator germanium (SiGeOI), or germanium-on-insulator (GeOI), etc. Although several examples of materials that can form the second substrate 220 have been described herein, any material that can serve as a semiconductor substrate falls within the spirit and scope of this application.

[0116] In one example, as shown in Figures 2B, 3B, 4B, 5B, and 6B, a second movable film layer 221, a third isolation layer 250, a second fixed electrode layer 222, a fourth isolation layer 260, and a second bonding layer are sequentially formed on the first surface of the second substrate 220. Exemplarily, the materials of the first isolation layer 230, the second isolation layer 240, the third isolation layer 250, and the fourth isolation layer 260 may include, but are not limited to, one or more of amorphous silicon, silicon nitride, and silicon oxide, such as a composite material of silicon nitride / amorphous silicon / silicon nitride or a composite material of silicon oxide / amorphous silicon / silicon oxide, or any other suitable insulating material, such as TiO2, TaO2, etc., which are not limited in this application. For example, the materials of the first movable film layer 211, the first fixed electrode layer 212, the second movable film layer 221 and the second fixed electrode layer 222 include, but are not limited to, materials such as polycrystalline silicon, silicon, germanium, metal, second-generation semiconductor, third-generation semiconductor, etc., and can also be any other suitable conductive material. This application does not limit this.

[0117] In one example, as shown in Figures 2B, 3B, 4B, 5B and 6B, a second cavity 223 is formed between the second bonding layer and the second substrate 220. A plurality of second connecting pillars 224 are formed in the second cavity 223. The upper and lower ends of the second connecting pillars 224 are respectively connected to the second bonding layer and the second movable film layer 221. A plurality of second release holes 225 are formed in the second bonding layer that expose the second cavity 223.

[0118] In one example, as shown in Figures 2A to 6C, the system further includes a first support layer 217 located between the first fixed electrode layer 212 and the first isolation layer 230, a second support layer 218 located between the first fixed electrode layer 212 and the second isolation layer 240, a third support layer 227 located between the second fixed electrode layer 222 and the third isolation layer 250, and a fourth support layer 228 located between the second fixed electrode layer 222 and the fourth isolation layer 260. Exemplarily, the first support layer 217 and the second support layer 218 are used to improve the rigidity of the first fixed electrode layer 212, and the third support layer 227 and the fourth support layer 228 are used to improve the rigidity of the second fixed electrode layer 222. Exemplarily, the materials of the first support layer 217, the second support layer 218, the third support layer 227, and the fourth support layer 228 include, but are not limited to, materials such as SiCN, SiN, SiC, and SiON.

[0119] Next, step S3 is executed, as shown in Figures 2C, 3C, 4C, 5C, and 6C, where the first bonding layer and the second bonding layer are bonded together to form a stacked third movable film layer 216 connected to the first connecting post 214, a fifth isolation layer 270, and a fourth movable film layer 226 connected to the second connecting post 224. The first cavity 213 and the second cavity 223 are interconnected through the first release hole 215 and the second release hole 225 to form a cavity. Exemplarily, the first cavity 213 and the second cavity 223 are correspondingly arranged.

[0120] In one example, a low-temperature bonding process is used to perform the above bonding steps. Specifically, the first bonding layer and the second bonding layer can be cryogenically bonded in a vacuum environment at a first temperature below 400°C; alternatively, the above-mentioned low-temperature bonding can also be performed in other environments, which is not limited in this application. In other embodiments, other bonding processes can also be used to perform the above-mentioned bonding steps.

[0121] In one example, multiple first release holes 215 and multiple second release holes 225 are arranged in a one-to-one correspondence, and multiple first connecting posts 214 and multiple second connecting posts 224 are arranged in a one-to-one correspondence, so that the deformation of multiple movable membrane layers is more consistent when subjected to external sound signals.

[0122] In one example, as shown in Figures 2A to 2C, the first bonding layer includes a first sub-movable film layer 2161, and the second bonding layer includes a fourth movable film layer 226, a fifth isolation layer 270 located on the fourth movable film layer, and a second sub-movable film layer 2162 located on the fifth isolation layer. The first sub-movable film layer 2161 is connected to one end of the first connecting post 214, and the fourth movable film layer 226 is connected to one end of the second connecting post 224. In the bonding step, the first sub-movable film layer 2161 and the second sub-movable film layer 2162 are bonded together, and the first sub-movable film layer 2161 and the second movable film layer 2162 constitute a third movable film layer 216.

[0123] In another example, as shown in Figures 3A to 3C, the first bonding layer includes a third movable film layer 216, the second bonding layer includes a fourth movable film layer 226 and a fifth isolation layer 270 located on the fourth movable film layer 226, the third movable film layer 216 is connected to one end of the first connecting post 214, and the fourth movable film layer 226 is connected to one end of the second connecting post 224. In the bonding step, the fifth isolation layer 270 and the third movable film layer 216 are bonded together.

[0124] In another example, as shown in Figures 4A to 4C, the first bonding layer includes a third movable film layer 216 and a first sub-isolation layer 2701 located on the third movable film layer 216, and the second bonding layer includes a fourth movable film layer 226 and a second sub-isolation layer 2702 located on the fourth movable film layer 226. The third movable film layer 216 is connected to one end of the first connecting post 214, and the fourth movable film layer 226 is connected to one end of the second connecting post 224. In the bonding step, the first sub-isolation layer 2701 and the second sub-isolation layer 2702 are bonded together, and the first sub-isolation layer 2701 and the second sub-isolation layer 2702 constitute the fifth isolation layer 270.

[0125] In another example, as shown in Figures 5A to 5C, the first bonding layer includes a third movable film layer 216 and a fifth isolation layer 270 located on the third movable film layer 216, and the second bonding layer includes a fourth movable film layer 226. The third movable film layer 216 is connected to one end of the first connecting post 214, and the fourth movable film layer 226 is connected to one end of the second connecting post 224. In the bonding step, the fifth isolation layer 270 and the fourth movable film layer 226 are bonded together.

[0126] In another example, as shown in Figures 6A to 6C, the first bonding layer includes a third movable film layer 216, a fifth isolation layer 270 located on the third movable film layer 216, and a third sub-movable film layer 2261 located on the fifth isolation layer 270. The second bonding layer includes a fourth sub-movable film layer 2262. The third movable film layer 216 is connected to one end of the first connecting post 214, and the fourth sub-movable film layer 2262 is connected to one end of the second connecting post 224. In the bonding step, the third sub-movable film layer 2261 and the fourth sub-movable film layer 2262 are bonded together, and the third sub-movable film layer 2261 and the fourth sub-movable film layer 2262 constitute the fourth movable film layer 226.

[0127] In one example, the structures of the third movable film layer 216, the fifth isolation layer 270, and the fourth movable film layer 226 include any of the following: Poly / A-Si / poly, Poly / SiN / Poly, Poly / SiO2 / Poly, Poly / SiN / A-si / SiN / Poly, Poly / A-si / SiN / A-si / Poly, Poly / SiO2 / A-si / SiO2 / Poly, Poly / A-si / SiO2 / A-si / / Poly, Poly / SiN / SiO2 / SiN / Poly, and Poly / SiO2 / SiN / SiO2 / Poly; wherein, the material of the fifth isolation layer 270 may also include other insulating materials such as TiO2 or TaO2, and the materials of the third movable film layer 216 and the fourth movable film layer 226 may also include metal, SiGe silicon, metal, second-generation semiconductor, or third-generation semiconductor, etc., and this application does not impose any restrictions on them. For example, taking the fifth isolation layer 270 as a composite material of SiN / A-si / SiN, the fifth isolation layer 270 is a composite film layer composed of an A-si layer and A-si layers located on the upper and lower sides of the amorphous silicon layer. When the first sub-isolation layer 2701 and the second sub-isolation layer 2702 are bonded in the bonding step, the material of the first sub-isolation layer 2701 and the second sub-isolation layer 2702 on the bonding surface is A-si. Specifically, referring to Figures 7A-7D, the steps of bonding the first sub-isolation layer 2701 and the second sub-isolation layer 2702 when the material of the fifth isolation layer 270 is SiN / A-si / SiN are described: The first sub-isolation layer 2701 includes a first SiN layer 27011 and a first A-si layer 27012, and the second sub-isolation layer 2702 includes a second SiN layer 27021 and a second A-si layer 27022. In the bonding step, the first A-si layer 27012 and the second A-si layer 27022 are bonded to obtain the fifth isolation layer 270 of SiN / A-si / SiN composite material.

[0128] In one example, the device structure shown in FIG4A can be obtained by the following steps: providing a first substrate 210; sequentially forming a first movable film layer 211, a first isolation layer 230, a first support layer 217, a first fixed electrode layer 212, and a second support layer 218 on a first surface of the first substrate 210; etching the first support layer 217, the first fixed electrode layer 212, and the second support layer 218 to form a plurality of first vias exposing a portion of the surface of the first isolation layer 230, and forming an insulating material filling the plurality of first vias; forming a second isolation layer 240 on the second support layer 218; etching away a portion of the second isolation layer 240 and a portion of the insulating material. A first insulating layer 230 is partially formed to create a plurality of second through-holes exposing a portion of the surface of the first movable film layer 211, and a plurality of first connecting posts 214 are formed in the plurality of second through-holes; a first bonding layer is formed on the second insulating layer 240 and the first connecting posts 214; a portion of the first bonding layer is etched away to form a plurality of first release holes 215 exposing a portion of the surface of the second insulating layer 240; the remaining insulating material, a portion of the first insulating layer 230, and a portion of the second insulating layer 240 are removed through the first release holes 215 to form a first cavity 213 between the first bonding layer and the first movable film layer 211, and the plurality of first connecting posts 214 are located in the first cavity 213. Exemplarily, the above-mentioned film layer can be formed by a deposition process, such as epitaxial growth, chemical vapor deposition (CVD), physical vapor deposition (PVD), or atomic layer deposition (ALD), etc., and this application does not limit this. Exemplarily, the above-described etching steps can be performed using an etching process, such as a dry etching process or a wet etching process. For example, a buffer oxide etchant can be used, or gaseous hydrogen fluoride (VHF) can be used to remove the remaining insulating material, a portion of the first isolation layer 230, and a portion of the second isolation layer 240 to form the first cavity 213. Exemplarily, the formation process of the second substrate 220 and the structure on the second substrate 220 can refer to the above-described process steps, and will not be repeated here.

[0129] In one example, the first bonding layer, as shown in FIG4A, including a third movable film layer 216 and a first sub-isolation layer 2701, can be formed as follows: a portion of the third movable film layer 216 is formed on the second isolation layer 240, and a first sub-isolation layer 2701 and a portion of the third movable film layer 216 located on the first sub-isolation layer 2701 are provided. The third movable film layer 216 on the second isolation layer 240 and the portion of the third movable film layer 216 located on the first sub-isolation layer 2701 are bonded together to obtain the first bonding layer shown in FIG4A.

[0130] Next, step S4 is performed, as shown in Figures 7D, 8, and 9, to remove the second substrate 220 to expose the second movable film layer 221. Exemplarily, an etching process, such as a dry etching process or a wet etching process, can be used to etch and remove the second substrate 220.

[0131] Finally, step S5 is performed, as shown in Figures 8 and 9, to remove the portion of the first substrate 210 corresponding to the cavity from the second surface of the first substrate 210, thereby forming a back cavity 219 exposing a portion of the first movable film layer 211. Exemplarily, an etching process can be used to etch and remove the portion of the first substrate 210 corresponding to the cavity, such as a dry etching process or a wet etching process.

[0132] In one example, as shown in FIG8, after removing the portion of the first substrate 210 corresponding to the cavity from the second surface of the first substrate 210 to form a back cavity 219 exposing a portion of the first movable film layer 211, the method of this application further includes: forming, respectively, a first metal wiring layer 281 electrically connected to the first movable film layer 211, a second metal wiring layer 282 electrically connected to the second movable film layer 221, a third metal wiring layer 283 electrically connected to the third movable film layer 216, a fourth metal wiring layer 284 electrically connected to the fourth movable film layer 226, a fifth metal wiring layer 285 electrically connected to the first fixed electrode layer 212, and a sixth metal wiring layer 286 electrically connected to the second fixed electrode layer 222 using a metal wiring process. For example, as shown in FIG8, before performing the metal wiring process, a step of forming a sixth isolation layer 280 on a portion of the surface of the second movable film layer 221 is included. At least a portion of the first metal wiring layer 281, the third metal wiring layer 283, the fourth metal wiring layer 284, the fifth metal wiring layer 285, and the sixth metal wiring layer 286 are located on the sixth isolation layer 280, so that the first metal wiring layer 281, the third metal wiring layer 283, the fourth metal wiring layer 284, the fifth metal wiring layer 285, and the sixth metal wiring layer 286 are electrically isolated from the second movable film layer 221. The second metal wiring layer 282 is located on the surface of the second movable film layer 221 not covered by the sixth isolation layer 280. For example, the metal wiring layer is used to lead out the movable film layer and the fixed electrode layer so that the movable film layer and the fixed electrode layer are connected to an external circuit to complete the output of the capacitor signal. For example, a single metal wiring layer can be formed in a single metal wiring process after the bonding step, or a single metal wiring layer can be formed in two metal wiring processes: before the bonding step, a partial structure of the single metal wiring layer is formed in a single metal wiring process, and after the bonding step, the remaining structure of the single metal wiring layer is formed in a second metal wiring process. This reduces the difficulty and simplifies the process control when forming multiple metal wiring layers after the bonding step. For example, electrical isolation between the metal wiring layer and the movable film layer and / or fixed electrode layer requiring electrical isolation is achieved through an insulating material.

[0133] In one example, as shown in FIG9, after removing the portion of the first substrate 210 corresponding to the cavity from the second surface of the first substrate 210 to form a back cavity 219 exposing a portion of the first movable film layer 211, the method of this application further includes: forming a first pad 291 on the first movable film layer 211, a second pad 292 on the second movable film layer 221, a third pad 293 on the third movable film layer 216, a fourth pad 294 on the fourth movable film layer 226, a fifth pad 295 on the first fixed electrode layer 212, and a sixth pad 296 on the second fixed electrode layer 222 using a wire bonding process. Exemplarily, the pads are used to lead out the movable film layer and the fixed electrode layer so that the movable film layer and the fixed electrode layer are connected to an external circuit to complete the output of a capacitance signal.

[0134] In one example, the first movable film layer 211 and the first fixed electrode layer 212 constitute a first variable capacitor structure; the second movable film layer 221 and the second fixed electrode layer 222 constitute a second variable capacitor structure; the third movable film layer 216 and the first fixed electrode layer 212 constitute a third variable capacitor structure; and the fourth movable film layer 226 and the second fixed electrode layer 222 constitute a fourth variable capacitor structure. The phase difference between the output signals of adjacent variable capacitor structures is 180°. Specifically, the phase difference between the output signals of the first and third variable capacitor structures is 180°, the phase difference between the output signals of the third and fourth variable capacitor structures is 180°, and the phase difference between the output signals of the fourth and second variable capacitor structures is 180°; in other words, the output signals of the first and fourth variable capacitor structures are in phase, and the output signals of the second and third variable capacitor structures are in phase.

[0135] In one example, by using appropriate electrical connections, the capacitance signals of multiple variable capacitor structures can be output, thereby enabling a higher capacitance value than that of a single capacitor structure in related technologies, which in turn improves the device's sensitivity and signal-to-noise ratio.

[0136] In one example, the following describes one method of reading the output signal of the MEMS device of this application by applying a first bias voltage to the first fixed electrode layer 212, applying a second bias voltage to the second fixed electrode layer 222, connecting the first movable film layer 211 and the fourth movable film layer 226 to the inverting input terminal of the first amplifier, and connecting the second movable film layer 221 and the third movable film layer 216 to the non-inverting input terminal of the first amplifier:

[0137] The first fixed electrode layer 212 can be electrically connected to a first voltage source via a fifth metal wiring layer 285 or a fifth pad 295. The first voltage source is used to apply a first bias voltage to the first fixed electrode layer 212. The second fixed electrode layer can be electrically connected to a second voltage source via a sixth metal wiring layer 286 or a sixth pad 296. The second voltage source is used to apply a second bias voltage to the first fixed electrode layer 212. For example, the voltage range of the first bias voltage and the second bias voltage is 3V-20V, such as 3V, 6V, 8V, 16V, or 20V.

[0138] Under the polarization effect, the first capacitor structure and the third capacitor structure are in opposite phase and there is no space charge interference. The phase difference between the output signals of the first movable film layer 211 and the third movable film layer 216 is 180°. The second capacitor structure and the fourth capacitor structure are in opposite phase and there is no space charge interference. The phase difference between the output signals of the second movable film layer 221 and the fourth movable film layer 226 is 180°.

[0139] The first movable film layer 211 and the fourth movable film layer 226 are electrically connected by electrically connecting the first metal wiring layer 281 and the fourth metal wiring layer 284, and the first metal wiring layer 281 and the fourth metal wiring layer 284 are connected to the inverting input terminal of the first amplifier; or, the first movable film layer 211 and the fourth movable film layer 226 are electrically connected by electrically connecting the first pad 291 and the fourth pad 294 through leads, and the first pad 291 and the fourth pad 294 are connected to the inverting input terminal of the first amplifier.

[0140] The second movable film layer 221 and the third movable film layer 216 are electrically connected by electrically connecting the second metal wiring layer 282 and the third metal wiring layer 283, and the second metal wiring layer 282 and the third metal wiring layer 283 are connected to the non-inverting input terminal of the first amplifier; or, the second movable film layer 221 and the third movable film layer 216 are electrically connected by electrically connecting the second pad 292 and the third pad 293 with leads, and the second pad 292 and the third pad 293 are connected to the non-inverting input terminal of the first amplifier.

[0141] In one example, since the phase difference between the output signals of adjacent variable capacitor structures is 180°, the phase difference between the capacitor signals output by the first movable membrane layer 211 and the third movable membrane layer 216 and the capacitor signals output by the first movable membrane layer 211 and the fourth movable membrane layer 226 is 180°. Due to the presence of the first connecting post 214 and the second connecting post 224, when an external sound signal is received, the first movable membrane layer 211, the second movable membrane layer 221, the third movable membrane layer 216 and the fourth movable membrane layer 226 undergo the same deformation. At this time, the capacitance of the first capacitor structure, the second capacitor structure, the third capacitor structure and the fourth capacitor structure changes. More specifically, taking the downward deformation of the movable film layer as an example, the capacitance of the first and fourth capacitor structures decreases, while the capacitance of the second and third capacitor structures increases. The output signals of the electrically connected first movable film layer 211 and third movable film layer 216 are designated as positive output signals (Out_P), and the output signals of the electrically connected second movable film layer 221 and fourth movable film layer 226 are designated as negative output signals (Out_N). The positive and negative output signals are then differentially output (for example, the positive output signal is input to the non-inverting input of the first amplifier, and the negative output signal...). The signal is input to the inverting input terminal of the first amplifier, and the output capacitance signal can be read at the output terminal of the first amplifier to complete the conversion between sound signal and electrical signal. The sensitivity and signal-to-noise ratio of the device can be significantly improved. For example, the output capacitance value of this embodiment is four times that of a single-diaphragm, single-backplane MEMS microphone. The sensitivity of the MEMS device in this application is four times that of a single-diaphragm, single-backplane MEMS microphone, and the signal-to-noise ratio of the MEMS device in this application is at least 6dB higher than that of a single-diaphragm, single-backplane MEMS microphone. It is worth noting that other reading methods can also be used to read the output signal of the MEMS device manufactured by the manufacturing method of this application. Specifically, refer to the various methods for reading the output signal of the MEMS device manufactured by the manufacturing method of this application described in Embodiment 3 below. Alternatively, any other suitable method that can obtain a higher capacitance value for reading the output signal can be used; this application does not limit this method.

[0142] This concludes the description of the key steps in the manufacturing method of the MEMS device of this application. The manufacturing of a complete MEMS device may include other steps, which will not be elaborated here. It is worth mentioning that the order of the above steps can be adjusted without conflict.

[0143] In summary, the MEMS device manufacturing method of this application embodiment forms four movable film layers and two fixed electrode layers. The four movable film layers and two fixed electrode layers form multiple variable capacitor structures. The multiple variable capacitor structures can output higher capacitance values, thereby improving the sensitivity and signal-to-noise ratio of the device.

[0144] Example 2

[0145] This application also provides a MEMS device, which is manufactured by the method described in the first embodiment above.

[0146] The MEMS device of this application will now be described in detail with reference to Figures 8 and 9. Exemplarily, the MEMS device of this application includes:

[0147] A first substrate 210, wherein a back cavity 219 is formed through the first substrate 210;

[0148] The first movable film layer 211 is located on the first substrate 210, and the back cavity 219 exposes a portion of the surface of the first movable film layer 211;

[0149] The first isolation layer 230 is located on a portion of the first movable membrane layer 211;

[0150] The first fixed electrode layer 212 is located on the first isolation layer 230;

[0151] The second isolation layer 240 is located on a portion of the first fixed electrode layer 212;

[0152] The third movable membrane layer 216 is located on the second isolation layer 240;

[0153] The fifth isolation layer 270 is located on the third movable membrane layer 216;

[0154] The fourth movable membrane layer 226 is located on the fifth isolation layer 270;

[0155] The fourth isolation layer 260 is located on a portion of the fourth movable membrane layer 226;

[0156] The second fixed electrode layer 222 is located on the fourth isolation layer 260;

[0157] The third isolation layer 250 is located on a portion of the second fixed electrode layer 222;

[0158] The second movable membrane layer 221 is located on the third isolation layer 250;

[0159] The first cavity 213 is located between the first movable membrane layer 211 and the third movable membrane layer 216;

[0160] The second cavity 223 is located between the second movable membrane layer 221 and the fourth movable membrane layer 226;

[0161] Multiple first connecting posts 214 are located in the first cavity 213, and the upper and lower ends of the first connecting posts 214 are respectively connected to the third movable membrane layer 216 and the first movable membrane layer 211.

[0162] Multiple second connecting posts 224 are located in the second cavity 223, and the upper and lower ends of the second connecting posts 224 are respectively connected to the second movable membrane layer 221 and the fourth movable membrane layer 226.

[0163] Multiple release holes penetrate the third movable membrane layer 216, the fifth isolation layer 270 and the fourth movable membrane layer 226. The first cavity 213 and the second cavity 223 are interconnected through the release holes to form a cavity. The release holes are composed of the first release hole 215 and the second release hole 225.

[0164] The first movable membrane layer 211 and the fourth movable membrane layer 226 are electrically connected, as are the second movable membrane layer 221 and the third movable membrane layer 216. For example, the release hole is composed of a first release hole 215 and a second release hole 225.

[0165] In one example, the first substrate 210 and the second substrate 220 are bulk silicon substrates, which may include at least one of the following materials: Si, Ge, SiGe, SiC, SiGeC, InAs, GaAs, InP, InGaAs, or other III / V compound semiconductors. Alternatively, the first substrate 210 and the second substrate 220 may also include silicon-on-insulator (SOI), silicon-on-insulator stacked (SSOI), silicon-on-insulator stacked germanium (S-SiGeOI), silicon-on-insulator (SiGeOI), or germanium-on-insulator (GeOI), etc. Although several examples of materials that can form the first substrate 210 and the second substrate 220 have been described herein, any material that can serve as a semiconductor substrate falls within the spirit and scope of this application.

[0166] In one example, the materials of the first movable film layer 211, the second movable film layer 221, the third movable film layer 216, the fourth movable film layer 226, the first fixed electrode layer 212, and the second fixed electrode layer 222 include, but are not limited to, materials such as polycrystalline silicon, SiGe silicon, metal, etc., and can also be any other suitable conductive material. This application does not impose any restrictions on this.

[0167] In one example, the materials of the first isolation layer 230, the second isolation layer 240, the third isolation layer 250 and the fourth isolation layer 260 include, but are not limited to, one or more of amorphous silicon, silicon nitride, and silicon oxide, such as a composite material of silicon nitride / amorphous silicon / silicon nitride or a composite material of silicon oxide / amorphous silicon / silicon oxide, or any other suitable insulating material, which is not limited in this application.

[0168] In one example, the structures of the third movable film layer 216, the fifth isolation layer 270, and the fourth movable film layer 226 include any of the following: Poly / A-Si / poly, Poly / SiN / Poly, Poly / SiO2 / Poly, Poly / SiN / A-si / SiN / Poly, Poly / A-si / SiN / A-si / Poly, Poly / SiO2 / A-si / SiO2 / Poly, Poly / A-si / SiO2 / A-si / / Poly, Poly / SiN / SiO2 / SiN / Poly, and Poly / SiO2 / SiN / SiO2 / Poly; wherein, the material of the fifth isolation layer 270 may also include other insulating materials such as TiO2 or TaO2, and the materials of the third movable film layer 216 and the fourth movable film layer 226 may also include metal, SiGe silicon, metal, second-generation semiconductor, or third-generation semiconductor, etc., and this application does not impose any restrictions on them. For example, the third movable film layer 216, the fifth isolation layer 270 and the fourth movable film layer 226 are structured as Poly / SiN / A-si / SiN / Poly. The fifth isolation layer 270 is made of a composite material of SiN / A-si / SiN. The fifth isolation layer 270 is a composite film layer composed of an A-si layer and A-si layers located on the upper and lower sides of the amorphous silicon layer.

[0169] In one example, the materials of the first support layer 217, the second support layer 218, the third support layer 227, the fourth support layer 228, the first connecting post 214, and the second connecting post 224 include, but are not limited to, SiCN, SiN, SiC, SiON, SiO2 encapsulated by SiN, and Poly encapsulated by SiN.

[0170] In one example, as shown in Figure 8, the system further includes a first metal wiring layer 281, a second metal wiring layer 282, a third metal wiring layer 283, a fourth metal wiring layer 284, a fifth metal wiring layer 285, and a sixth metal wiring layer 286. The first metal wiring layer 281 is electrically connected to the first movable film layer 211, the second metal wiring layer 282 is electrically connected to the second movable film layer 221, the third metal wiring layer 283 is electrically connected to the third movable film layer 216, the fourth metal wiring layer 284 is electrically connected to the fourth movable film layer 226, the fifth metal wiring layer 285 is electrically connected to the first fixed electrode layer 212, and the sixth metal wiring layer is electrically connected to the second fixed electrode layer 222. Exemplarily, as shown in FIG8, a sixth isolation layer 280 is further included, covering a portion of the surface of the second movable film layer 221. At least a portion of the first metal wiring layer 281, the third metal wiring layer 283, the fourth metal wiring layer 284, the fifth metal wiring layer 285, and the sixth metal wiring layer 286 are located on the sixth isolation layer 280, such that the first metal wiring layer 281, the third metal wiring layer 283, the fourth metal wiring layer 284, the fifth metal wiring layer 285, and the sixth metal wiring layer 286 are electrically isolated from the second movable film layer 221. The second metal wiring layer 282 is located on the surface of the second movable film layer 221 not covered by the sixth isolation layer 280. Exemplarily, the metal wiring layer is electrically isolated from the movable film layer and / or the fixed electrode layer that require electrical isolation by means of an insulating material. Exemplarily, the metal wiring layer is used to lead out the movable film layer and the fixed electrode layer so that the movable film layer and the fixed electrode layer are connected to an external circuit to complete the output of the capacitor signal.

[0171] In another example, as shown in FIG9, it also includes a first pad 291 on the first movable film layer 211, a second pad 292 on the second movable film layer 221, a third pad 293 on the third movable film layer 216, a fourth pad 294 on the fourth movable film layer 226, a fifth pad 295 on the first fixed electrode layer 212, and a sixth pad 296 on the second fixed electrode layer 222. Exemplarily, the pads are used to lead out the movable film layer and the fixed electrode layer so that the movable film layer and the fixed electrode layer are connected to an external circuit to complete the output of the capacitance signal.

[0172] In one example, the first connecting post 214 and the second connecting post 224 are cylindrical, and the diameter of the first connecting post 214 and the second connecting post 224 is in the range of 1um-3um, for example, 1um, 1.5um, 2um, 2.2um or 3um, or any other suitable diameter range; and / or, the material of the first connecting post 214 and the second connecting post 224 includes SiN, SiO2 wrapped by SiN or Poly wrapped by SiN, or any other suitable material.

[0173] In one example, the spacing between the first movable film layer 211 and the first fixed electrode layer 212, between the third movable film layer 216 and the first fixed electrode layer 212, between the second movable film layer 221 and the second fixed electrode layer 222, and between the fourth movable film layer 226 and the second fixed electrode layer 222 ranges from 1µm to 3µm, for example, 1µm, 1.5µm, 2µm, 2.2µm, or 3µm; and / or, the thickness of the first movable film layer 211, the second movable film layer 221, the third movable film layer 216, and the fourth movable film layer 226 ranges from 0.1µm to 1.5µm, for example, 1µm, 1.1µm, 1.3µm, 1.4µm, or 1.5µm; and / or, the thickness of the MEMS device excluding the substrate 200 ranges from 8µm to 15µm, for example, 8µm, 8.5µm, 9µm, 10.2µm, or 15µm.

[0174] In one example, the first movable film layer 211 and the first fixed electrode layer 212 constitute a first variable capacitor structure; the second movable film layer 221 and the second fixed electrode layer 222 constitute a second variable capacitor structure; the third movable film layer 216 and the first fixed electrode layer 212 constitute a third variable capacitor structure; and the fourth movable film layer 226 and the second fixed electrode layer 222 constitute a fourth variable capacitor structure. The phase difference between the output signals of adjacent variable capacitor structures is 180°. Specifically, the phase difference between the output signals of the first and third variable capacitor structures is 180°, the phase difference between the output signals of the third and fourth variable capacitor structures is 180°, and the phase difference between the output signals of the fourth and second variable capacitor structures is 180°; in other words, the output signals of the first and fourth variable capacitor structures are in phase, and the output signals of the second and third variable capacitor structures are in phase.

[0175] In one example, by using a suitable electrical connection method, the capacitance signals of multiple variable capacitor structures can be output (specifically, refer to the various methods for reading the output signals of MEMS devices manufactured by the manufacturing method of this application described in Embodiment 3, or any other suitable method for reading output signals that can obtain higher capacitance values, which is not limited in this application), thereby enabling the output of higher capacitance values ​​than a single capacitor structure in the related art, thereby improving the sensitivity and signal-to-noise ratio of the device.

[0176] This concludes the introduction to the structure of the MEMS device of this application. The complete device may also include other components, which will not be described in detail here.

[0177] In summary, the MEMS device of this application embodiment has four movable film layers and two fixed electrode layers. The four movable film layers and two fixed electrode layers form multiple variable capacitor structures. The multiple variable capacitor structures can output higher capacitance values, thereby improving the sensitivity and signal-to-noise ratio of the device.

[0178] Example 3

[0179] Another embodiment of this application provides a method for reading the output signal of a MEMS device. The method for reading the output signal of a MEMS device is described below with reference to Figures 10, 11, 12, and 13. The method for reading the output signal of a MEMS device according to this application includes:

[0180] Provide the MEMS device described in Embodiment 2 or provide a MEMS device manufactured using the manufacturing method described in Embodiment 1;

[0181] Read the output signals of MEMS devices.

[0182] In one example, reading the output signal of a MEMS device includes: applying a first bias voltage to the first fixed electrode layer 212 of the MEMS device and applying a second bias voltage to the second fixed electrode layer 222 of the MEMS device;

[0183] Connect the first movable diaphragm layer 211 and the fourth movable diaphragm layer 226 to the non-inverting input terminal of the first amplifier 310, and connect the second movable diaphragm layer 221 and the third movable diaphragm layer 216 to the inverting input terminal of the first amplifier 310; or connect the first movable diaphragm layer 211 and the fourth movable diaphragm layer 226 to the inverting input terminal of the first amplifier 310, and connect the second movable diaphragm layer 221 and the third movable diaphragm layer 216 to the non-inverting input terminal of the first amplifier 310.

[0184] Read the signal at the output of the first amplifier 310.

[0185] In one example, as shown in Figure 10, the same voltage source can be used to provide the first bias voltage and the second bias voltage, in which case the first bias voltage and the second bias voltage are equal voltages in phase. Alternatively, as shown in Figure 11, two voltage sources can be used to provide the first bias voltage and the second bias voltage respectively, in which case the first bias voltage and the second bias voltage can be equal voltages in phase, unequal voltages in phase, equal voltages with different phases, or unequal voltages with different phases, etc.

[0186] The first movable film layer 211 and the first fixed electrode layer 212 constitute a first variable capacitor structure; the second movable film layer 221 and the second fixed electrode layer 222 constitute a second variable capacitor structure; the third movable film layer 216 and the first fixed electrode layer 212 constitute a third variable capacitor structure; and the fourth movable film layer 226 and the second fixed electrode layer 222 constitute a fourth variable capacitor structure. The phase difference between the output signals of adjacent variable capacitor structures is 180°. Specifically, the phase difference between the output signals of the first and third variable capacitor structures is 180°, the phase difference between the output signals of the third and fourth variable capacitor structures is 180°, and the phase difference between the output signals of the fourth and second variable capacitor structures is 180°; in other words, the output signals of the first and fourth variable capacitor structures are in phase, and the output signals of the second and third variable capacitor structures are in phase.

[0187] In one example, due to the presence of the first connecting post 214 and the second connecting post 224, when an external sound signal is received, the first movable diaphragm layer 211, the second movable diaphragm layer 221, the third movable diaphragm layer 216, and the fourth movable diaphragm layer 226 undergo the same deformation. At this time, the capacitance of the first capacitor structure, the second capacitor structure, the third capacitor structure, and the fourth capacitor structure changes. More specifically, taking the overall downward deformation of the movable diaphragm layers as an example, the capacitance of the first capacitor structure and the fourth capacitor structure decreases, while the capacitance of the second capacitor structure and the third capacitor structure increases. The output signals of the electrically connected first movable diaphragm layer 211 and the third movable diaphragm layer 216 are set as positive output signals (Out_P), and the electrically connected second movable diaphragm layer 221 and the fourth movable diaphragm layer 226 are set as negative output signals (Out_N). The positive and negative output signals are differentially output (for example, the positive output signal is input to the non-inverting input of the first amplifier, and the negative output signal is input to the inverting input of the first amplifier).

[0188] By using the above-described method for reading the output signal of a MEMS device, the output capacitance signal can be read at the output terminal of the first amplifier, thus completing the conversion between sound and electrical signals. Furthermore, the sensitivity and signal-to-noise ratio of the device can be significantly improved. Specifically, the output capacitance value read by the above method is four times that of a single-diaphragm, single-backplane MEMS microphone, thereby making the sensitivity of the MEMS device four times that of a single-diaphragm, single-backplane MEMS microphone. The signal-to-noise ratio of the MEMS device of this application can also be improved by at least 6dB compared to a single-diaphragm, single-backplane MEMS microphone.

[0189] In another example, as shown in Figure 12, reading the output signal of the MEMS device includes: applying a first bias voltage to the first movable film layer 211 and the fourth movable film layer 226, and applying a second bias voltage to the second movable film layer 221 and the third movable film layer 216.

[0190] The first fixed electrode layer 212 and the second fixed electrode layer 222 are respectively connected to the non-inverting input terminal and the inverting input terminal of the first amplifier;

[0191] Read the output signal of the first amplifier 310.

[0192] By using the above method to read the output signal of the MEMS device, the output capacitance value read is 4 times that of the output capacitance value of a MEMS microphone with a single diaphragm and a single backplane. As a result, the sensitivity of the MEMS device is 4 times that of the MEMS microphone with a single diaphragm and a single backplane. The signal-to-noise ratio of the MEMS device of this application can also be improved by at least 6dB compared with the MEMS microphone with a single diaphragm and a single backplane.

[0193] In another example, reading the output signal of the MEMS device includes: applying a first bias voltage to the first fixed electrode layer 212 and applying a second bias voltage to the second fixed electrode layer 222;

[0194] The second movable film layer and the fourth movable film layer are respectively connected to the non-inverting input terminal and the inverting input terminal of the first amplifier, and the first movable film layer or the third movable film layer is connected to the input terminal of the second amplifier; or, the first movable film layer and the third movable film layer are respectively connected to the non-inverting input terminal and the inverting input terminal of the first amplifier, and the second movable film layer or the fourth movable film layer is connected to the input terminal of the second amplifier.

[0195] Read the signals at the output terminals of the first amplifier and the second amplifier.

[0196] Specifically, as shown in Figure 13, Figure 13 illustrates one specific embodiment of the above-described method for reading the output signal of a MEMS device: the second movable film layer 221 and the fourth movable film layer 226 are connected to the non-inverting input terminal and the inverting input terminal of the first amplifier 310, respectively, and the first movable film layer is connected to the input terminal of the second amplifier 320.

[0197] By using the above method to read the output signal of the MEMS device, the output capacitance value read is three times that of the output capacitance value of a MEMS microphone with a single diaphragm and a single backplane. As a result, the sensitivity of the MEMS device is three times that of the MEMS microphone with a single diaphragm and a single backplane. The signal-to-noise ratio of the MEMS device of this application can also be improved compared with the MEMS microphone with a single diaphragm and a single backplane.

[0198] In other embodiments, the output signal of the MEMS device of this application can also be read by any other suitable reading method that can obtain a higher capacitance value (a capacitance value higher than the output capacitance value of a MEMS microphone with a single diaphragm and a single backplane).

[0199] In one example, the movable film layer and the fixed electrode layer can be brought out in any suitable way and structure (e.g., metal wiring layer, pads, etc.) to connect the movable film layer and the fixed electrode layer to the external circuit.

[0200] In one example, the voltage range of the first bias voltage and the second bias voltage is 3V-20V.

[0201] In summary, the method for reading the output signal of a MEMS device in this application can read a higher output capacitance value, thereby improving the device's sensitivity and signal-to-noise ratio.

[0202] Although several embodiments have been described herein, it should be understood that many other modifications and embodiments will arise in the mind of those skilled in the art, all of which will fall within the spirit and scope of the concept disclosed herein. More specifically, various modifications and changes may be made in terms of the arrangement and / or components of the subject matter within the scope of this disclosure, the drawings, and the appended claims. In addition to modifications and changes in the components and / or arrangement, the use of alternative methods will also be obvious to those skilled in the art.

Claims

1. A MEMS device, characterized in that, include: A first substrate, wherein a back cavity is formed therethrough the first substrate; A first movable film layer is located on the first substrate, and the back cavity exposes a portion of the surface of the first movable film layer; A first isolation layer is located on a portion of the first movable membrane layer; The first fixed electrode layer is located on the first isolation layer; A second isolation layer is located on a portion of the first fixed electrode layer; The third movable membrane layer is located on the second isolation layer; The fifth isolation layer is located on the third movable membrane layer; The fourth movable membrane layer is located on the fifth isolation layer; The fourth isolation layer is located on a portion of the fourth movable membrane layer; The second fixed electrode layer is located on the fourth isolation layer; A third isolation layer is located on a portion of the second fixed electrode layer; The second movable membrane layer is located on the third isolation layer; The first cavity is located between the first movable membrane layer and the third movable membrane layer; The second cavity is located between the second movable membrane layer and the fourth movable membrane layer; Multiple first connecting posts are located in the first cavity, and the upper and lower ends of the first connecting posts are respectively connected to the third movable membrane layer and the first movable membrane layer; Multiple second connecting posts are located in the second cavity, and the upper and lower ends of the second connecting posts are respectively connected to the second movable membrane layer and the fourth movable membrane layer; Multiple release holes penetrate the third movable membrane layer, the fifth isolation layer, and the fourth movable membrane layer. The first cavity and the second cavity are interconnected through the release holes to form a cavity.

2. The MEMS device according to claim 1, characterized in that, The first movable film layer and the first fixed electrode layer constitute a first variable capacitor structure, the second movable film layer and the second fixed electrode layer constitute a second variable capacitor structure, the third movable film layer and the first fixed electrode layer constitute a third variable capacitor structure, and the fourth movable film layer and the second fixed electrode layer constitute a fourth variable capacitor structure, wherein the phase difference of the output signals of adjacent variable capacitor structures is 180°.

3. The MEMS device according to claim 1, characterized in that, The structure of the third movable film layer, the fifth isolation layer, and the fourth movable film layer includes any one of the following: Poly / A-Si / poly, Poly / SiN / Poly, Poly / SiO2 / Poly, Poly / SiN / A-si / SiN / Poly, Poly / A-si / SiN / A-si / Poly, Poly / SiO2 / A-si / SiO2 / Poly, Poly / A-si / SiO2 / A-si / / Poly, Poly / SiN / SiO2 / SiN / Poly, and Poly / SiO2 / SiN / SiO2 / Poly. The fifth isolation layer is made of TiO2 or TaO2, and the third and fourth movable film layers are made of silicon, germanium, metal, second-generation semiconductor or third-generation semiconductor.

4. The MEMS device according to claim 1, characterized in that, The first connecting post and the second connecting post are cylindrical, and the diameter of the first connecting post and the second connecting post ranges from 1um to 3um.

5. The MEMS device according to claim 1, characterized in that, The materials of the first connecting post and the second connecting post include SiN, SiO2 encapsulated by SiN, or Poly encapsulated by SiN.

6. The MEMS device according to claim 1, characterized in that, The spacing between the first movable film layer and the first fixed electrode layer, between the third movable film layer and the first fixed electrode layer, between the second movable film layer and the second fixed electrode layer, and between the fourth movable film layer and the second fixed electrode layer ranges from 1µm to 3µm.

7. The MEMS device according to claim 1, characterized in that, The thickness range of the first movable film layer, the second movable film layer, the third movable film layer and the fourth movable film layer is 0.1um-1.5um.

8. The MEMS device according to claim 1, characterized in that, The sum of the thicknesses of the MEMS devices, excluding the substrate, ranges from 8µm to 15µm.

9. The MEMS device according to claim 1, characterized in that, Also includes: The system comprises a first metal wiring layer, a second metal wiring layer, a third metal wiring layer, a fourth metal wiring layer, a fifth metal wiring layer, and a sixth metal wiring layer, wherein the first metal wiring layer is electrically connected to the first movable film layer, the second metal wiring layer is electrically connected to the second movable film layer, the third metal wiring layer is electrically connected to the third movable film layer, the fourth metal wiring layer is electrically connected to the fourth movable film layer, the fifth metal wiring layer is electrically connected to the first fixed electrode layer, and the sixth metal wiring layer is electrically connected to the second fixed electrode layer.

10. The MEMS device according to claim 1, characterized in that, Also includes: The first pad is located on the first movable film layer, the second pad is located on the second movable film layer, the third pad is located on the third movable film layer, the fourth pad is located on the fourth movable film layer, the fifth pad is located on the first fixed electrode layer, and the sixth pad is located on the second fixed electrode layer.

11. The MEMS device according to claim 1, characterized in that, Also includes: A first support layer located between the first fixed electrode layer and the first isolation layer, a second support layer located between the first fixed electrode layer and the second isolation layer, a third support layer located between the second fixed electrode layer and the third isolation layer, and a fourth support layer located between the second fixed electrode layer and the fourth isolation layer.

12. A method for manufacturing a MEMS device, characterized in that, The method includes: A first substrate is provided, on the first surface of which a first movable film layer, a first isolation layer, a first fixed electrode layer, a second isolation layer and a first bonding layer are sequentially formed. A first cavity is formed between the first bonding layer and the first substrate. A plurality of first connecting pillars are formed in the first cavity. The upper and lower ends of the first connecting pillars are respectively connected to the first bonding layer and the first movable film layer. A plurality of first release holes are formed in the first bonding layer that expose the first cavity. A second substrate is provided, on the first surface of which a second movable film layer, a third isolation layer, a second fixed electrode layer, a fourth isolation layer and a second bonding layer are sequentially formed. A second cavity is formed between the second bonding layer and the second substrate. A plurality of second connecting pillars are formed in the second cavity. The upper and lower ends of the second connecting pillars are respectively connected to the second bonding layer and the second movable film layer. A plurality of second release holes are formed in the second bonding layer that expose the second cavity. The first bonding layer and the second bonding layer are bonded together so that the first bonding layer and the second bonding layer constitute a third movable film layer, a fifth isolation layer and a fourth movable film layer connected to the first connecting post, which are stacked and connected to the first connecting post. The first cavity and the second cavity are interconnected through the first release hole and the second release hole to form a cavity. Remove the second substrate to expose the second movable film layer; The portion of the first substrate corresponding to the cavity is removed from the second surface of the first substrate to form a back cavity that exposes a portion of the first movable film layer.

13. The manufacturing method according to claim 12, characterized in that, The first bonding layer includes a first sub-movable film layer, and the second bonding layer includes the fourth movable film layer, the fifth isolation layer located on the fourth movable film layer, and a second sub-movable film layer located on the fifth isolation layer. In the bonding step, the first sub-movable film layer and the second sub-movable film layer are bonded together, and the first sub-movable film layer and the second sub-movable film layer constitute the third movable film layer; or... The first bonding layer includes the third movable film layer, and the second bonding layer includes the fourth movable film layer and the fifth isolation layer located on the fourth movable film layer. In the bonding step, the fifth isolation layer and the third movable film layer are bonded together; or... The first bonding layer includes the third movable film layer and a first sub-isolation layer located on the third movable film layer; the second bonding layer includes the fourth movable film layer and a second sub-isolation layer located on the fourth movable film layer; in the bonding step, the first sub-isolation layer and the second sub-isolation layer are bonded together, and the first sub-isolation layer and the second sub-isolation layer constitute the fifth isolation layer; or... The first bonding layer includes the third movable film layer and the fifth isolation layer located on the third movable film layer; the second bonding layer includes the fourth movable film layer; and in the bonding step, the fifth isolation layer and the fourth movable film layer are bonded together; or, The first bonding layer includes the third movable film layer, the fifth isolation layer located on the third movable film layer, and the third sub-movable film layer located on the fifth isolation layer. The second bonding layer includes the fourth sub-movable film layer. In the bonding step, the third sub-movable film layer and the fourth sub-movable film layer are bonded together, and the third sub-movable film layer and the fourth sub-movable film layer constitute the fourth movable film layer.

14. The manufacturing method according to claim 12, characterized in that, The bonding step is performed using a low-temperature bonding process.

15. A method for reading the output signal of a MEMS device, characterized in that, include: Provide a MEMS device as described in any one of claims 1-11 or a MEMS device manufactured using the manufacturing method as described in any one of claims 12-14; Read the output signal of the MEMS device; The process of reading the output signals of MEMS devices includes: A first bias voltage is applied to the first fixed electrode layer of the MEMS device, and a second bias voltage is applied to the second fixed electrode layer of the MEMS device; Connect the first movable diaphragm layer and the fourth movable diaphragm layer to the non-inverting input terminal of the first amplifier, and connect the second movable diaphragm layer and the third movable diaphragm layer to the inverting input terminal of the first amplifier; or connect the first movable diaphragm layer and the fourth movable diaphragm layer to the inverting input terminal of the first amplifier, and connect the second movable diaphragm layer and the third movable diaphragm layer to the non-inverting input terminal of the first amplifier. Read the signal at the output of the first amplifier; Alternatively, read the output signals of the MEMS device, including: A first bias voltage is applied to the first movable film layer and the fourth movable film layer, and a second bias voltage is applied to the second movable film layer and the third movable film layer; The first fixed electrode layer and the second fixed electrode layer are respectively connected to the non-inverting input terminal and the inverting input terminal of the first amplifier; Read the signal at the output of the first amplifier; Alternatively, read the output signals of the MEMS device, including: A first bias voltage is applied to the first fixed electrode layer, and a second bias voltage is applied to the second fixed electrode layer; The second movable diaphragm layer and the fourth movable diaphragm layer are respectively connected to the non-inverting input terminal and the inverting input terminal of the first amplifier, and the first movable diaphragm layer or the third movable diaphragm layer is connected to the input terminal of the second amplifier; or, the first movable diaphragm layer and the third movable diaphragm layer are respectively connected to the non-inverting input terminal and the inverting input terminal of the first amplifier, and the second movable diaphragm layer or the fourth movable diaphragm layer is connected to the input terminal of the second amplifier. Read the signals from the output terminals of the first amplifier and the second amplifier.

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