Mems chip and sensor module

Abstract

The application provides a MEMS chip and a sensor module, wherein the MEMS chip comprises a support base, a diaphragm and a back plate arranged on the support base, and the diaphragm and the back plate form a capacitor structure; wherein a porous filter assembly is arranged on the side of the back plate away from the diaphragm; the porous filter assembly is used for screening a vibration signal entering the capacitor structure; and the diaphragm generates displacement according to the vibration signal entering the capacitor structure, so as to convert the vibration signal into an electric signal. The application can improve the accuracy of chip detection on a target signal.

Description

Technical Field

[0001] This invention relates to the field of sensor technology, and more specifically, to a MEMS chip and sensor module. Background Technology

[0002] With societal progress and technological advancements, the size of electronic products such as mobile phones, computers, and wearable devices has been continuously decreasing in recent years. People's performance requirements for these portable electronic products are also increasing, which in turn demands that the size, performance, and consistency of the supporting electronic components be continuously reduced. MEMS (Micro-Electro-Mechanical-System) integrated products have begun to be mass-produced and applied to such electronic products. Their package size is smaller than that of traditional electronic devices; for example, MEMS chips are favored by most manufacturers.

[0003] Currently, the main structural components of conventional acoustic MEMS include a diaphragm forming a capacitor and a backplate. Sound vibration signals are collected and analyzed by monitoring the electrical signals generated by the capacitance change due to diaphragm deformation under different sound pressure levels. When such MEMS devices are used in gas sensors based on acousto-optic theory, they receive the vibration signals generated after the target gas molecules are excited and convert these vibration signals into electrical signals, thereby detecting the concentration of the target gas molecules based on the analysis of these electrical signals. However, conventional MEMS designs lack the ability to distinguish vibration signals in different frequency bands, and vibration signals generated after the excitation of non-target gas molecules can interfere with the accuracy of target gas concentration detection.

[0004] Therefore, there is an urgent need for a MEMS chip that can filter vibration signals of different frequencies and improve the accuracy of detecting different target gas concentrations. Summary of the Invention

[0005] In view of the above problems, the purpose of this invention is to provide a MEMS chip and sensor module to solve the problem that existing MEMS products have no ability to distinguish vibration signals of different frequency bands, thereby affecting the accuracy of target gas concentration detection.

[0006] The MEMS chip provided by this invention includes a support base and a diaphragm and a back electrode plate disposed on the support base, wherein the diaphragm and the back electrode plate form a capacitor structure; wherein,

[0007] A porous filter assembly is provided on the side of the back electrode plate away from the diaphragm;

[0008] The porous filter assembly is used to filter vibration signals entering the capacitor structure;

[0009] The diaphragm is displaced according to the vibration signal entering the capacitor structure, so as to convert the vibration signal into an electrical signal.

[0010] In addition, an optional technical solution is that the porous filter assembly includes at least one porous membrane;

[0011] When the porous membrane is provided with at least two layers, the porous membrane layers are distributed at intervals through insulating layers.

[0012] In addition, an alternative technical solution is that the pores on the porous membrane are circular, elliptical, or polygonal.

[0013] In addition, an optional technical solution is that when the porous membrane is provided in at least two sets, the positions of the pores on the adjacent two layers of porous membrane are correspondingly distributed or staggered in the direction perpendicular to the porous membrane.

[0014] Alternatively, an optional technical solution is to provide through holes on the back electrode plate; and to provide an anti-adsorption protrusion structure on the side of the back electrode plate near the diaphragm to avoid the distribution of the through holes.

[0015] Alternatively, the porous filter assembly can cover all the through holes on the back electrode plate and be distributed at intervals with the back electrode plate.

[0016] Alternatively, an optional technical solution is to provide at least one vent hole on the diaphragm.

[0017] In addition, an optional technical solution includes a first pad and a second pad exposed from the back electrode plate; wherein the first pad is connected to the electrode layer of the back electrode plate and the second pad is connected to the diaphragm.

[0018] Alternatively, the porous filter assembly can be a monolithically formed silicon compound.

[0019] On the other hand, the present invention also provides a sensor module, including a substrate and a housing forming an encapsulation structure with the substrate; the aforementioned MEMS chip is disposed within the encapsulation structure.

[0020] Using the aforementioned MEMS chip and sensor module, a porous filter component is set on the side of the back electrode plate away from the diaphragm. The porous filter component can filter the vibration signal entering the capacitor structure. The diaphragm is displaced according to the vibration signal entering the capacitor structure to convert the vibration signal into an electrical signal. The porous filter component can enable the target frequency sound signal to be picked up by the capacitor structure, thereby improving the accuracy of the chip in detecting the concentration of target molecules and reducing the design difficulty of the back-end processing circuit.

[0021] To achieve the foregoing and related objectives, one or more aspects of the invention include the features that will be described in detail below. The following description and accompanying drawings illustrate certain exemplary aspects of the invention. However, these aspects indicate only a few of the various ways in which the principles of the invention can be used. Furthermore, the invention is intended to encompass all such aspects and their equivalents. Attached Figure Description

[0022] Other objects and results of the invention will become more apparent and readily understood with reference to the following description taken in conjunction with the accompanying drawings. In the drawings:

[0023] Figure 1 A top view of a MEMS chip according to an embodiment of the present invention;

[0024] Figure 2 for Figure 1 Cross-sectional view along line AB;

[0025] Figure 3 A cross-sectional view of a MEMS chip according to another embodiment of the present invention;

[0026] Figure 4 This is a schematic diagram of the structure of a porous membrane according to an embodiment of the present invention;

[0027] Figure 5 This is a schematic diagram of the structure of a porous membrane according to another embodiment of the present invention;

[0028] Figure 6 This is a partial schematic structure of a porous membrane according to an embodiment of the present invention.

[0029] The attached figures are labeled as follows: support base 1, diaphragm 2, vent hole 21, back electrode plate 3, anti-adsorption protrusion structure 4, first pad 51, second pad 52, porous filter assembly 6, pore 61, insulating layer 62, and support layer 7.

[0030] In all the accompanying drawings, the same reference numerals indicate similar or corresponding features or functions. Detailed Implementation

[0031] In the following description, numerous specific details are set forth for illustrative purposes and to provide a thorough understanding of one or more embodiments. However, it will be apparent that these embodiments may also be implemented without these specific details. In other instances, well-known structures and devices are shown in block diagram form for ease of description of one or more embodiments.

[0032] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0033] Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the term “comprising” as used in this specification means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It should be understood that the term “and / or” as used herein includes any and all combinations of one or more of the associated listed items.

[0034] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless defined as herein.

[0035] To provide a detailed description of the MEMS chip and sensor module of this invention, specific embodiments of the invention will be described in detail below with reference to the accompanying drawings.

[0036] Figure 1 and Figure 2 The schematic structures of the MEMS chip according to embodiments of the present invention are shown from different angles.

[0037] like Figure 1 and Figure 2As shown in the figure, the MEMS chip of this embodiment includes a support base 1 and a diaphragm 2 and a back electrode plate 3 disposed at intervals on the support base 1. The support base 1 includes a substrate and a support layer 7 located on the substrate. The edges of the diaphragm 2 and the back electrode plate 3 are confined within the support layer 7 to form a parallel plate capacitor structure. A porous filter component 6 is provided on the side of the back electrode plate 3 away from the diaphragm 2. The porous filter component 6 can filter the vibration signal entering the capacitor, so that the target signal enters the capacitor and is picked up by the diaphragm 2. The diaphragm 2 is displaced according to the vibration signal entering the capacitor structure. This displacement causes a change in the distance between the diaphragm 2 and the back electrode plate 3, thereby converting the vibration signal into an electrical signal for output, thus completing the detection of the target signal.

[0038] The target signal can be a variety of detection signals. For example, when a MEMS chip is used in a gas sensor based on acousto-optic theory, the target signal can be the target gas molecule. The gas molecule is excited by external light and its temperature rises after absorbing light energy, thereby generating a vibration signal. The vibration signal can be picked up by the capacitor structure, and the concentration of the target gas molecule can be detected by the corresponding electrical signal. The porous filter component 6 can distinguish vibration signals of different frequency bands, thereby achieving the screening of vibration signals of different frequencies and improving the accuracy of the detection of the target gas concentration.

[0039] Specifically, the porous filter assembly 6 includes at least one porous membrane. This porous membrane can be disposed on the upper side of the back electrode plate 3 via an insulating layer. When at least two porous membranes are provided, each porous membrane layer can be spaced apart by an insulating layer 62. In other words, the porous filter assembly 6 can include multiple porous membranes that are parallel to each other and spaced apart. Furthermore, the porous membranes near the back electrode plate 3 are also spaced apart from the back electrode plate 3 to avoid mutual adsorption and interference, which could affect detection accuracy. Figure 3 A schematic structure is shown according to an embodiment of the present invention, in which a porous membrane layer is disposed on the back electrode plate 3 by means of various methods such as pasting or welding after the porous membrane is formed.

[0040] Furthermore, the porous filter component 6 can be integrally molded using silicon compound materials, such as silicon nitride or other silicides. Silicon oxide can be deposited between the multiple porous membranes for support, and the silicon oxide can be removed later by etching to form a multi-layered three-dimensional structure. The spacing between the porous membranes can be adjusted according to the actual needs of the chip, and the pores 61 on the porous membranes can be circular, elliptical, or polygonal. The pores 61 can be regular or irregular in shape. Figure 4 and Figure 5Schematic structures of porous membranes according to embodiments of the present invention are shown, wherein the pores 61 can be configured as prototypical or regular hexagonal. Furthermore, depending on the stress differences at different locations of the multilayer membrane, pores 61 with different densities or shapes can be provided at different locations, thereby improving the signal filtering quality of the porous membrane.

[0041] It should be noted that the size, number, and arrangement of the pores 61 on the porous membrane can be adjusted according to actual needs. For example, the relevant parameters of the porous membrane pores 61 can be adjusted according to the frequency of the vibration signal emitted by the target gas molecules to be detected. In this way, the sound absorption effect of the porous membrane structure can be used to absorb the external non-target frequency sound signals, and only the vibration signal of the target frequency (the frequency of the target signal) can be retained to enter the capacitor structure to excite the diaphragm 2 to vibrate, thereby improving the accuracy of the target signal detection.

[0042] In the MEMS chip of this invention, the absorption of vibration signals of different frequency bands by the pores (micropores) on the porous membrane is mainly due to the radial velocity gradient generated by the vibration signal within the pores. The relative motion under different velocity gradients generates frictional resistance, causing viscous loss of the vibration signal. Combined with the attached... Figure 6 It can be seen that it is mainly affected by the following parameters:

[0043] 1. Aperture size d: Vibration signals encounter viscous resistance when propagating within a micropore. The smaller the aperture, the greater the viscous resistance. When the micropore size is close to the wavelength λ of the vibration signal, the scattering and refraction of the vibration signal within the aperture are most pronounced, resulting in greater energy loss and significant attenuation of the vibration signal intensity near that wavelength. Irregular aperture shapes complicate the propagation path of the vibration signal within the aperture, thereby enhancing its attenuation capability.

[0044] 2. Micropore depth t: The depth of the micropore affects the propagation path of the vibration signal in the micropore and the interaction time between the vibration signal and the sidewall of the pore. Increasing t can cause longer wavelength signals to generate effective energy loss in the micropore structure, that is, the effective absorption frequency is shifted forward, which increases the frequency bandwidth of the affected vibration signal.

[0045] 3. Cavity depth D: The air layer under the porous membrane on the surface is equivalent to increasing the effective thickness of the porous membrane-air composite structure. Vibration signals are reflected and interfered between the back electrode plate and the porous membrane, allowing some frequency band vibration signals to re-enter the porous structure on the surface, thus improving the absorption effect of frequency signals in that band.

[0046] When at least two sets of porous membranes are provided, the positions of the pores 61 on adjacent layers of porous membranes can be either one-to-one or staggered in the direction perpendicular to the porous membrane. The multiple sets of porous membranes are connected in series, and the absorption effect of different frequency bands can be adjusted more easily by adjusting the parameters, thereby increasing the bandwidth of the affected frequency. When the positions of the multiple layers of pores 61 are one-to-one, the filtering intensity of non-target signals can be enhanced, which can be used to effectively intercept non-target signals that play a major role in interference. When the positions of the multiple layers of pores 61 are staggered, non-target signals of multiple frequencies can be filtered. The specific setting method can be flexibly set according to the application scenario and detection requirements.

[0047] As a specific example, in the MEMS chip of this embodiment of the invention, when one set of porous membranes is provided, the pore parameters of the porous membranes can be set to d = 1 mm, t = 1 mm, and D = 30 mm. Under these parameters, the porous filter component can have a significant absorption effect on 800 Hz signals. When two sets of porous membranes are provided, the parameters of the upper porous membrane are d = 1 mm, t = 1 mm, and D = 30 mm, and the parameters of the lower porous membrane are d = 1 mm, t = 1 mm, and D = 20 mm. Under these parameters, the porous filter component can have a significant absorption effect on 500 Hz and 1280 Hz signals, and also has a large absorption effect on vibration signals in the middle frequency band.

[0048] In the MEMS chip of this embodiment, a number of through holes are also provided on the back electrode plate 3. During the assembly process of the porous filter component 6, it can cover all the through holes on the back electrode plate 3 and be distributed at intervals with the back electrode plate 3. In addition, an anti-adsorption protrusion structure 4 is provided on the side of the back electrode plate 3 near the diaphragm 2 to avoid the distribution of each through hole. The anti-adsorption protrusion structure 4 can prevent the diaphragm 2 from adsorbing together with the back electrode plate 3 during vibration. The density and size of the anti-adsorption protrusion structure 4 can be set according to the size of the chip.

[0049] Furthermore, the MEMS chip in this embodiment of the invention may also have at least one vent hole 21 on the diaphragm 2, which can prevent the diaphragm 2 from breaking during large-amplitude vibration; in addition, the MEMS chip may also include a first pad 51 and a second pad 52 exposed from the back electrode plate 3; wherein, the first pad 51 is connected to the electrode layer of the back electrode plate 3, and the second pad 52 is connected to the diaphragm 2, and the first pad 51 and the second pad 52 can realize the signal transmission between the MEMS chip and the outside world.

[0050] Corresponding to the above-mentioned MEMS chip, the present invention also provides a sensor module, which may include a substrate and a housing forming an encapsulation structure with the substrate, and the above-mentioned MEMS chip is disposed within the encapsulation structure.

[0051] It should be noted that the above-mentioned sensor module embodiments can refer to the MEMS chip embodiments, and will not be described in detail here.

[0052] According to the MEMS chip and sensor module of the present invention, a porous filter assembly is provided on the side of the back electrode plate away from the diaphragm. The vibration signal entering the capacitor structure is filtered by one or more porous membranes in the porous filter assembly, which can distinguish vibration signals of different frequency bands, thereby achieving the filtering of vibration signals of different frequencies, improving the accuracy of the chip in detecting the concentration of target molecules, and reducing the design difficulty of the back-end processing circuit.

[0053] The MEMS chip and sensor module according to the present invention have been described above by way of example with reference to the accompanying drawings. However, those skilled in the art should understand that various modifications can be made to the MEMS chip and sensor module proposed in the present invention without departing from the scope of the invention. Therefore, the scope of protection of the present invention should be determined by the contents of the appended claims.

Claims

1. A MEMS chip, characterized in that, It includes a support base and a diaphragm and a back electrode plate disposed on the support base, wherein the diaphragm and the back electrode plate form a capacitor structure; wherein, A porous filter assembly is provided on the side of the back electrode plate away from the diaphragm; The porous filter assembly is used to filter vibration signals entering the capacitor structure; The diaphragm is displaced according to the vibration signal entering the capacitor structure, so as to convert the vibration signal into an electrical signal; The porous filter assembly includes at least one porous membrane, and pores of different densities or shapes are provided at different locations of the porous membrane according to the stress differences at different locations of the porous membrane; The relevant parameters of the porous membrane pores can be adjusted according to the frequency of the vibration signal emitted by the target gas molecules to be detected. In this way, the sound absorption effect of the porous membrane structure can be used to absorb the external non-target frequency sound signals, and only the vibration signal of the target signal frequency can be retained to enter the capacitor structure to excite the diaphragm vibration. The porous membrane has micropores, which absorb vibration signals of different frequency bands.

2. The MEMS chip according to claim 1, characterized in that, When the porous membrane is provided with at least two layers, the porous membrane layers are distributed at intervals through insulating layers.

3. The MEMS chip according to claim 2, characterized in that, The pores on the porous membrane are circular, elliptical, or polygonal.

4. The MEMS chip according to claim 2, characterized in that, When at least two sets of porous membranes are provided, the positions of the pores on adjacent porous membrane layers are either correspondingly distributed or staggered in the direction perpendicular to the porous membrane.

5. The MEMS chip according to claim 1, characterized in that, A through hole is provided on the back electrode plate; and, An anti-adsorption protrusion structure is provided on the side of the back electrode plate near the diaphragm to avoid the distribution of through holes.

6. The MEMS chip according to claim 5, characterized in that, The porous filter assembly covers all the through holes on the back electrode plate and is distributed at intervals with the back electrode plate.

7. The MEMS chip according to claim 1, characterized in that, At least one vent hole is provided on the diaphragm.

8. The MEMS chip according to claim 1, characterized in that, It also includes a first pad and a second pad exposed from the back electrode plate; wherein... The first pad is connected to the electrode layer of the back electrode plate, and the second pad is connected to the diaphragm.

9. The MEMS chip according to claim 1, characterized in that, The porous filter assembly is a one-piece molded silicon compound.

10. A sensor module, comprising a substrate and a housing forming an encapsulation structure with the substrate; characterized in that, The package structure contains a MEMS chip as described in any one of claims 1 to 9.

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