MEMS device, manufacturing method thereof and electronic device

Abstract

The invention discloses an MEMS device and a manufacturing method thereof, and an electronic device, the MEMS device comprises a substrate, a signal reference layer, a first signal acquisition layer, a second signal acquisition layer, a third signal acquisition layer and a signal output layer, the signal reference layer is connected to the substrate so as to move synchronously with the substrate, and a gap is formed between the signal reference layer and the substrate; the first signal acquisition layer and the signal reference layer form a first capacitor which is used for acquiring a gaseous medium environment noise signal and a solid medium environment noise signal; the second signal acquisition layer and the signal reference layer form a second capacitor, and the second capacitor is used for acquiring a solid-state medium environment noise signal; the third signal acquisition layer and the signal output layer form a third capacitor and are used for acquiring the gaseous medium environment noise signal, the solid medium environment noise signal and the effective sound signal; the signal output layer is used for outputting effective sound signals.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and more particularly to a MEMS device, a manufacturing method thereof, and an electronic device. Background Art

[0002] Micro-Electro-Mechanical System (MEMS) technology is a high-tech that has developed rapidly in recent years. It uses advanced semiconductor manufacturing processes to achieve mass production of devices such as sensors and actuators. Compared with corresponding traditional devices, MEMS devices have obvious advantages in terms of volume, power consumption, weight, and price. In the market, the main application examples of MEMS devices include accelerometers, pressure sensors, acoustic sensors, and silicon microphones.

[0003] An acoustic sensor emits noise by itself during operation. The noise value is extremely low. In the case of no non-effective sound signal pickup, it will have slight vibrations due to environmental noise. When an effective sound signal is input, the acoustic sensor captures the signal. Obviously, the captured sound signal is superimposed with an environmental noise, which is completely unhelpful for the pickup and recognition of the effective signal. Even when the environmental noise increases to a certain extent, it will affect the pickup of the effective signal. This is called the masking effect of the sound signal, that is, in a noisy environmental noise, the noise signal will affect the pickup of the effective sound signal. We can equivalently think that under the condition of being affected by the environmental noise, the pickup sensitivity of the acoustic sensor to the effective sound signal becomes weaker. Therefore, in order to ensure the quality and clarity of the effective sound signal, it is very necessary to filter out the environmental noise and non-effective sound signals. Summary of the Invention

[0004] A series of simplified concepts are introduced in the Summary of the Invention section, which will be further detailed in the Detailed Description section. The Summary of the Invention section of the present invention does not mean to attempt to define the key features and essential technical features of the claimed technical solution, nor does it mean to attempt to determine the protection scope of the claimed technical solution.

[0005] The present invention provides a MEMS device, including a substrate, a signal reference layer, a first signal acquisition layer, a second signal acquisition layer, a third signal acquisition layer, and a signal output layer, wherein,

[0006] The signal reference layer is connected to the substrate to move synchronously with the substrate, and there is a spacing between the signal reference layer and the substrate;

[0007] The first signal acquisition layer and the signal reference layer form a first capacitor for acquiring gaseous medium environmental noise signals and solid medium environmental noise signals;

[0008] The second signal acquisition layer and the signal reference layer form a second capacitor, and the second capacitor is used to acquire the ambient noise signal of the solid medium;

[0009] The third signal acquisition layer and the signal output layer form a third capacitor, which is used to acquire the ambient noise signal of the gaseous medium, the ambient noise signal of the solid medium, and the effective sound signal;

[0010] The signal output layer is used to output the effective sound signal.

[0011] Exemplarily, the first signal acquisition layer and the second signal acquisition layer are respectively located above or below the signal reference layer.

[0012] Exemplarily, the first signal acquisition layer and the third signal acquisition layer are flexible structure layers, the second signal acquisition layer and the signal output layer are rigid structure layers, the flexible structure layer is affected by the ambient noise signal of the gaseous medium, the rigid structure layer is not affected by the ambient noise signal of the gaseous medium, and the signal reference layer is not affected by the ambient noise signal of the gaseous medium and the ambient noise signal of the solid medium.

[0013] Exemplarily, the rigid structure layer includes a polysilicon layer and a passivation layer formed on the upper surface and / or the lower surface of the polysilicon layer, and the passivation layer includes a silicon nitride layer.

[0014] Exemplarily, the thickness of the flexible structure layer is less than the thickness of the rigid structure layer, the thickness range of the flexible structure layer includes 5000 Å to 8000 Å, the thickness range of the rigid structure layer includes 1 μm to 2 μm, and the thickness of the signal reference layer is greater than 5 μm.

[0015] Exemplarily, a plurality of sound holes are formed in the first signal acquisition layer, and the ratio of the total area of the plurality of sound holes to the total area of the first signal acquisition layer is greater than 30%; one or more air vent holes are formed in the third signal acquisition layer, and the ratio of the area of the air vent hole to the total area of the third signal acquisition layer is less than 5%; the signal reference layer does not include sound holes.

[0016] Exemplarily, the third signal acquisition layer, the signal output layer, the second signal acquisition layer, the signal reference layer, and the first signal acquisition layer are sequentially formed from bottom to top above the substrate.

[0017] Exemplarily, the distances between the first capacitor, the second capacitor, and the third capacitor are all less than 0.5 mm, and the distance range between the second signal acquisition layer and the signal output layer includes 1.5 μm to 2.5 μm.

[0018] The present invention also provides a manufacturing method of a MEMS device, including:

[0019] Forming a first device structure:

[0020] Providing a first substrate;

[0021] Sequentially forming a first sacrificial layer, a third signal acquisition layer, a second sacrificial layer, a signal output layer, a third sacrificial layer, a second signal acquisition layer, and a fourth sacrificial layer on the first substrate, and one or more through-holes are formed in the third signal acquisition layer, the signal output layer, and the second signal acquisition layer;

[0022] Removing the first sacrificial layer, the second sacrificial layer, the third sacrificial layer, and the fourth sacrificial layer to form a first cavity and a first support portion between the third signal acquisition layer and the signal output layer, a second cavity and a second support portion between the signal output layer and the second signal acquisition layer, and a groove and a third support portion above the second signal acquisition layer;

[0023] Forming a second device structure:

[0024] Providing a second substrate;

[0025] Sequentially forming a fourth sacrificial layer and a first signal acquisition layer on the second substrate, and a plurality of through-holes are formed in the first signal acquisition layer;

[0026] Removing the fourth sacrificial layer to form a fourth cavity and a fourth support portion between the second substrate and the first signal acquisition layer;

[0027] Bonding the first device structure and the second device structure:

[0028] Bonding the second substrate and the third support portion, using the second substrate as a signal reference layer, and the groove forms a third cavity between the signal reference layer and the second signal acquisition layer.

[0029] The present invention also provides an electronic device, including:

[0030] A packaging substrate, on which the MEMS device and the application-specific integrated circuit chip described in any one of the above are fixed.

[0031] According to the MEMS device, its manufacturing method, and the electronic device provided by the present invention, by providing multiple signal acquisition layers on the acoustic sensor to respectively acquire effective sound signals, gaseous medium ambient noise signals, and solid medium ambient noise signals, through the pickup, superposition, and filtering processing of different types of sound signals, the influence of ambient noise is finally eliminated, so as to improve the sound quality and reduce or eliminate the interference of ambient noise. Description of the Drawings

[0032] The following drawings of the present invention are hereby incorporated as part of the present invention for understanding the present invention. Embodiments of the present invention and their descriptions are shown in the drawings to explain the principles of the present invention.

[0033] In the drawings:

[0034] Figure 1 is a schematic structural diagram of a MEMS device according to an embodiment of the present invention;

[0035] Figure 2 is a signal processing flowchart of a MEMS device according to an embodiment of the present invention;

[0036] Figure 3 is a flowchart of a manufacturing method of a MEMS device according to an embodiment of the present invention;

[0037] Figures 4A - 4E is a schematic cross-sectional view of the structure obtained by sequentially implementing the manufacturing method of a MEMS device according to an embodiment of the present invention;

[0038] Figure 5 is a schematic structural diagram of an electronic device including a MEMS device according to an embodiment of the present invention;

[0039] Figure 6 is a signal processing flowchart of a MEMS device according to an embodiment of the present invention. Detailed Embodiments

[0040] In the following description, numerous specific details are given to provide a more thorough understanding of the present invention. However, it will be apparent to one of ordinary skill in the art that the present invention may be practiced without one or more of these details. In other instances, well-known technical features have not been described to avoid obscuring the present invention.

[0041] It should be understood that the present invention can be implemented in different forms and should not be construed as limited to the embodiments set forth herein. On the contrary, these embodiments are provided to make the disclosure thorough and complete, and to fully convey the scope of the present invention to those skilled in the art. In the drawings, the dimensions and relative dimensions of layers and regions may be exaggerated for clarity. Like reference numerals refer to like elements throughout.

[0042] It should be understood that when an element or layer is referred to as being "on", "adjacent to", "connected to" or "coupled to" another element or layer, it can be directly on, adjacent to, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on", "directly adjacent to", "directly connected to" or "directly coupled to" another element or layer, 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, regions, layers and / or portions, these elements, components, regions, layers and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or portion from another element, component, region, layer or portion. Thus, a first element, component, region, layer or portion discussed below may be denoted as a second element, component, region, layer or portion without departing from the teachings of the present invention.

[0043] Spatial relationship terms such as "under", "below", "beneath", "underneath", "above", "over", etc. are used herein for convenience in describing the relationship of one element or feature shown in the figures to other elements or features. It should be understood that, in addition to the orientation shown in the figures, spatial relationship terms are intended to include different orientations of the device in use and operation. For example, if the device in the figures is flipped, then an element or feature described as "under" or "beneath" or "underneath" another element or feature will be oriented "over" the other element or feature. Thus, the exemplary terms "under" and "beneath" can include both an upper and a lower orientation. The device may be otherwise oriented (rotated 90 degrees or other orientation) and the spatial descriptors used herein are to be interpreted accordingly.

[0044] The purpose of the terms used herein is only to describe specific embodiments and is not a limitation of the present invention. As used herein, the singular forms "a", "an" and "the" are also intended to include the plural forms unless the context clearly dictates otherwise. It should also be understood that the terms "comprising" and / or "including", when used in this specification, specify the presence of the stated features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups. As used herein, the term "and / or" includes any and all combinations of the associated listed items.

[0045] To fully understand the present invention, detailed steps and detailed structures will be presented in the following description to illustrate the technical solutions proposed by the present invention. The preferred embodiments of the present invention are described in detail below. However, in addition to these detailed descriptions, the present invention may have other embodiments.

[0046] The present invention provides a MEMS device, as Figure 1 shown, comprising a substrate 100, a signal reference layer 102, a first signal acquisition layer 101, a second signal acquisition layer 103, a third signal acquisition layer 105 and a signal output layer 104. Among them, the signal reference layer 102 is connected to the substrate 100 to move synchronously with the substrate 100, and there is a spacing between the signal reference layer 102 and the substrate 100; the first signal acquisition layer 101 and the signal reference layer 102 form a first capacitor, and the first capacitor is used to acquire gaseous medium ambient noise signals and solid medium ambient noise signals; the second signal acquisition layer 103 and the signal reference layer 102 form a second capacitor, and the second capacitor is used to acquire the solid medium ambient noise signals; the third signal acquisition layer 105 and the signal output layer 104 form a third capacitor, which is used to acquire the gaseous medium ambient noise signals, the solid medium ambient noise signals and effective sound signals; the signal output layer 104 is used to output the effective sound signals.

[0047] Main application examples of MEMS devices include, but are not limited to, accelerometers, pressure sensors, acoustic sensors, silicon microphones, etc. In the embodiments of the present application, the MEMS device includes an acoustic sensor.

[0048] In one embodiment, the substrate 100 can be any suitable semiconductor substrate, such as a silicon substrate, and it can also be at least one of the materials mentioned below: Si, Ge, SiGe, SiC, SiGeC, InAs, GaAs, InP or other III / V compound semiconductors, and also includes multi-layer structures composed of these semiconductor materials, etc., or is silicon on insulator (SOI), stacked silicon on insulator (SSOI), stacked silicon germanide on insulator (S-SiGeOI), silicon germanide on insulator (SiGeOI) and germanium on insulator (GeOI), or can also be double-sided polished wafers (DSP), and can also be a ceramic substrate such as alumina, a quartz or glass substrate, etc.

[0049] In one embodiment, the first signal acquisition layer 101 includes a polysilicon layer. Optionally, one or both sides (i.e., the upper surface and / or the lower surface) of the polysilicon layer have a passivation layer (e.g., a silicon nitride layer). The thickness range of the first signal acquisition layer 101 includes 5000 Å to 8000 Å, and the thickness range of the silicon nitride layer includes 2000 Å to 5000 Å. The silicon nitride layer has electrical insulation properties and can prevent the first signal acquisition layer 101 from experiencing structural failure due to contact with an external conductive layer. However, the thickness of the nitride layer affects the pickup of sound signals, and an increase in thickness will attenuate its signal gain. In addition, a plurality of sound holes are formed in the first signal acquisition layer 101, and the ratio of the total area of the plurality of sound holes to the total area of the first signal acquisition layer 101 is greater than 30% (e.g., 40%, 50%, etc.). The total area of the sound holes, the thickness of the first signal acquisition layer 101, and the structural gain all have a negative correlation.

[0050] In one embodiment, the first signal acquisition layer 101 is a film layer structure sensitive to sound signals, and the signals it picks up are sound signals passing through solid and gaseous media in ambient noise, i.e., the solid medium ambient noise signal N1 S and the gaseous medium ambient noise signal N1 G .

[0051] In one embodiment, the signal reference layer 102 includes a DC bias layer. The DC bias layer includes a single-crystalline silicon layer or a polysilicon layer. Optionally, one or both sides (i.e., the upper surface and / or the lower surface) of the DC bias layer have a passivation layer (e.g., a silicon nitride layer) to provide insulation protection for the DC bias layer. The thickness of the signal reference layer 102 is greater than 5 μm (e.g., 8 μm, 10 μm, etc.). It should be noted that the signal reference layer 102 is connected to the substrate 100 by bonding or other means and is regarded as an integral part of the substrate 100 and moves synchronously with the substrate. In addition, the signal reference layer 102 is a sealed structure, and no sound holes are provided in the signal reference layer 102.

[0052] In one embodiment, the signal reference layer 102 is not affected by any signals (gaseous medium ambient noise signal, solid medium ambient noise signal, effective sound signal), i.e., N2 S = 0, N2 G = 0.

[0053] In one embodiment, the second signal acquisition layer 103 includes a polysilicon layer. Optionally, one or both sides (i.e., the upper surface and / or the lower surface) of the polysilicon layer have a passivation layer (e.g., a silicon nitride layer). The thickness range of the second signal acquisition layer 103 includes 1 μm to 2 μm. In addition, a plurality of sound holes are formed in the second signal acquisition layer 103.

[0054] In one embodiment, the second signal acquisition layer 103 only receives the sound signals from the solid medium in the ambient noise, that is, the ambient noise directly acts on the acoustic sensor through solid contact. The second signal acquisition layer 103 is characterized in that it is not easily affected by the sound signals, does not deform under the action of the sound signals, and deforms under the action of the vibration signals, so that it can be used to characterize the signal component conducted by the solid state of the sound signal, that is, the solid medium ambient noise signal N3 S . The reason why the second signal acquisition layer 103 is not affected by the sound signals can be mainly attributed to the fact that the porous structure can allow air to pass through. When the sound takes air as the carrier, it will pass through the structure with the air and has no response to the gaseous medium sound signals, that is, N3 G = 0.

[0055] In one embodiment, the first signal acquisition layer 101 is a flexible structure layer, the second signal acquisition layer 103 is a rigid structure layer, the thickness of the first signal acquisition layer 101 is less than that of the second signal acquisition layer 103, the stiffness of the second signal acquisition layer 103 is less than the yield strength of the first signal acquisition layer 101, and the yield strength of the second signal acquisition layer 103 has a clear corresponding relationship with the yield strength of the first signal acquisition layer 101, which is beneficial to the subsequent processing by the digital signal processor (DSP).

[0056] In one embodiment, the first signal acquisition layer 101 is located above the signal reference layer 102 and forms a first capacitor with the signal reference layer 102, and the distance between the first signal acquisition layer 101 and the signal reference layer 102 is less than 0.5 mm; the second signal acquisition layer 103 is located below the signal reference layer 102 and forms a second capacitor with the signal reference layer 102, and the distance between the second signal acquisition layer 103 and the signal reference layer 102 is less than 0.5 mm. It should be noted that the first signal acquisition layer 101 and the second signal acquisition layer 103 need to be located on both sides of the signal reference layer 102 respectively and cannot be located on the same side of the signal reference layer 102. The positions of the first signal acquisition layer 101 and the second signal acquisition layer 103 can be interchanged, that is, the first signal acquisition layer 101 can be located above the second signal acquisition layer 103 or below the second signal acquisition layer 103.

[0057] In one embodiment, the signal output layer 104 includes a polysilicon layer. Optionally, one side or both sides (i.e., the upper surface and / or the lower surface) of the polysilicon layer have a passivation layer (for example, a silicon nitride layer). The thickness range of the signal output layer 104 includes 1 μm to 2 μm. In addition, a plurality of sound holes are formed in the signal output layer 104.

[0058] In one embodiment, the signal output layer 104 has the same structure as the second signal acquisition layer 103. It is a rigid structure layer with a porous structure, and it only receives the sound signals from the solid medium in the ambient noise, that is, the solid medium ambient noise signal N4 S , and is not responsive to the gaseous medium sound signals, that is, N4 G = 0. In addition, the signal output layer 104 is used to detect the change of the capacitance signal, so as to convert the sound signal into a corresponding electrical signal for output, that is, to output the effective sound signal S4 A .

[0059] In one embodiment, the third signal acquisition layer 105 includes a polysilicon layer. Optionally, one or both sides (i.e., the upper surface and / or the lower surface) of the polysilicon layer have a passivation layer (e.g., a silicon nitride layer). The thickness range of the third signal acquisition layer 105 includes 5000 Å to 8000 Å, and the thickness range of the silicon nitride layer includes 2000 Å to 5000 Å. The silicon nitride layer has electrical insulation properties, which can prevent the third signal acquisition layer 105 from structural failure due to contact with the external conductive layer. In addition, one or more vent holes are formed in the third signal acquisition layer 105, and the ratio of the total area of the one or more vent holes to the total area of the third signal acquisition layer 105 is less than 5%.

[0060] In one embodiment, the third signal acquisition layer 105 is a film layer structure with a relatively large yield strength, and the signals it picks up include the solid medium ambient noise signal N5 S , the gaseous medium ambient noise signal N5 G and the effective sound signal.

[0061] In one embodiment, the third signal acquisition layer 105 is a flexible structure layer, the signal output layer 104 is a rigid structure layer, the thickness of the third signal acquisition layer 105 is less than that of the signal output layer 104, and the third signal acquisition layer 105 and the first signal acquisition layer 101 have the same yield strength consideration.

[0062] In one embodiment, the third signal acquisition layer 105 and the signal output layer 104 form a third capacitor, and the distance between the third signal acquisition layer 105 and the signal output layer 104 is less than 0.5 mm. It should be noted that the third capacitor can be located on the side close to the first signal acquisition layer 101 or on the side close to the second signal acquisition layer 103, and this application does not limit this. The positions of the third signal acquisition layer 105 and the signal output layer 104 that form the third capacitor can be interchanged, that is, the third signal acquisition layer 105 can be located above the signal output layer 104 or below the signal output layer 104.

[0063] In one embodiment, the third signal acquisition layer 105, the signal output layer 104, the second signal acquisition layer 103, the signal reference layer 102, and the first signal acquisition layer 101 are sequentially formed from bottom to top above the substrate 100. Among them, the spacing range between the signal output layer 104 and the second signal acquisition layer 103 includes 1.5 μm to 2.5 μm, which is greater than the spacings of the first capacitor, the second capacitor, and the third capacitor. It should be noted that the arrangement manners of the above-mentioned third signal acquisition layer 105, signal output layer 104, second signal acquisition layer 103, signal reference layer 102, and first signal acquisition layer 101 are only exemplary, and the present application does not limit this.

[0064] In one embodiment, the MEMS device includes a five-layer structure, and the picked-up signals include one or more of solid-state noise, gaseous noise, and sound signals. Each layer has different signal-picking capabilities. Therefore, the spacing (GAP), the film thickness, and the effective area jointly determine the gain for different signals. The considerations for the gain and attenuation of different signals are different. Here, the effective area of the diaphragm is attenuated between the first signal acquisition layer 101 and the signal reference layer 102. At the same time, the attenuation effect can also be adjusted by the GAP value between it and the signal reference layer 102. Since the signal reference layer 102 serves as a DC bias layer, the signals generated by the first signal acquisition layer 101 and the second signal acquisition layer 103 are related to their initial relative distances. The first signal acquisition layer 101 and the second signal acquisition layer 103 complete the collection of noise signals, and their signal output layer 104 and the third signal acquisition layer 105 complete the collection of mixed signals. Therefore, a larger GAP is set between the second signal acquisition layer 103 and the signal output layer 104 to distinguish two different units. The GAP value is preferably designed to be 0.30 mm, and its value can also be designed to be 0.2 mm, 0.25 mm. This GAP difference can increase the gain by increasing the size of the film layer. The remaining GAP values are basically set to 1.5 μm to 2.5 μm, and the preferred GAP value is 1.8 μm.

[0065] In one embodiment, the response of the MEMS device to the conduction of external sound signals is characterized by capacitance changes, and the capacitance change represents the dynamic response of the signal or mixed signal in this layer structure. We apply a fixed voltage to certain structures and form capacitors between the corresponding layers. Due to different structural yield strengths, the degree of deformation is different. Here, we clearly state that the first signal acquisition layer 101 and the third signal acquisition layer 105 are film layer structures, and the other layers are rigid. Here, we choose to apply a bias voltage to the signal reference layer 102 and the third signal acquisition layer 105. The selection of this bias voltage can be the same or different amplitude voltages characterized by the yield strength. Due to the application of the bias voltage, three parallel plate capacitors are formed in the MEMS device. The first capacitor formed by the first signal acquisition layer 101 and the signal reference layer 102 is used to detect the environmental noise signal of the ambient gaseous medium, but it is inevitably affected by the solid medium. Therefore, it collects N1 S +N1 G , the second capacitor formed by the second signal acquisition layer 103 and the signal reference layer 102 is used to collect the noise signal conducted by the solid medium. Therefore, it collects N3 S . It should be noted that due to the yield strength difference, N3 S is different from N1 S in terms of value. Therefore, we set a solid medium gain parameter G1s according to its yield strength difference, that is, the signal captured by N3 S reaches an amplitude close to that of N1 S under the gain boost, that is, N3 S × G1s = N1 S . For the third capacitor formed by the third signal acquisition layer 105 and the signal output layer 104, a solid medium gain parameter G2s is also set, N3 S × G2s = N4 S . At the same time, we also need to set a gaseous medium gain parameter G1 G . The reference value for the setting of this parameter is based on the first signal acquisition layer 101. The first signal acquisition layer 101 can provide the environmental noise from the ambient noise gaseous medium, and its response has a clear corresponding relationship with the third signal acquisition layer 105. Here, we consider that the first signal acquisition layer 101 and the third signal acquisition layer 105 have the same yield strength (of course, their designs can also be different). Since this structure can receive ambient noise, the signal amplitude of the received noise is related to its surface area. Here, we define the gaseous medium gain parameter G1 G in terms of the film layer area, N1 G × G1 G = N4 G .

[0066] Refer toFigure 2 As shown, the gaseous medium environmental noise signal N1 is obtained through the first signal acquisition layer 101 and the second signal acquisition layer 103. G , solid-state medium environmental noise signal N1 S , solid-state media environmental noise signal N3 S After that, the first signal acquisition layer 101 extracts the gaseous medium environmental noise, and the solid medium environmental noise gain matches N3 S ×G1s=N1 S , the first signal acquisition layer 101 solid medium environmental noise elimination, output signal N1 G Next, the signal output layer 104 extracts the gaseous medium environment noise, and the gaseous medium environment noise gain matches N1 G ×G1 G =N4 G . Perform solid media environment noise extraction at the signal output layer 104, and solid media environment noise gain matching N3 S ×G2s=N4 S , Solid-state media environmental noise inversion processing-N4 S By obtaining the gaseous medium environmental noise signal N4 from the first signal acquisition layer 105 G , solid-state medium environmental noise signal N4 S and effective sound signal S4 A Matching the above gaseous medium ambient noise gain N4 G , solid-state media environmental noise gain matching N4 S By performing signal mixing, filtering and signal amplification processing, high-quality speech signals can be obtained.

[0067] According to the MEMS device provided by the present invention, a plurality of signal acquisition layers are arranged on the sound sensor to respectively acquire effective sound signals and solid medium environmental noise signals and gaseous medium environmental noise signals, and different types of sound signals are picked up, superimposed, and filtered to finally eliminate the influence of environmental noise, thereby improving sound quality and reducing or eliminating the interference of environmental noise.

[0068] The present invention also provides a method for manufacturing a MEMS device, such as Figure 3 As shown, including:

[0069] Step S310: Form a first device structure: Provide a first substrate; sequentially form a first sacrificial layer, a third signal acquisition layer, a second sacrificial layer, a signal output layer, a third sacrificial layer, a second signal acquisition layer, and a fourth sacrificial layer on the first substrate. One or more through holes are formed in each of the third signal acquisition layer, the signal output layer, and the second signal acquisition layer; Remove the first sacrificial layer, the second sacrificial layer, the third sacrificial layer, and the fourth sacrificial layer to form a first cavity and a first support portion between the third signal acquisition layer and the signal output layer, a second cavity and a second support portion between the signal output layer and the second signal acquisition layer, and a groove and a third support portion above the second signal acquisition layer;

[0070] Step S320: Form a second device structure: Provide a second substrate; sequentially form a fourth sacrificial layer and a first signal acquisition layer on the second substrate. A plurality of through holes are formed in the first signal acquisition layer; Remove the fourth sacrificial layer to form a fourth cavity and a fourth support portion between the second substrate and the first signal acquisition layer;

[0071] Step S320: Bond the first device structure and the second device structure: Bond the second substrate and the third support portion, with the second substrate as the signal reference layer, and the groove forms a third cavity between the signal reference layer and the second signal acquisition layer.

[0072] First, perform Step S310. As Figures 4A - 4B shown, form a first device structure 410.

[0073] In one embodiment, as Figure 4A shown, provide a first substrate 400. The first substrate 400 can be any suitable semiconductor substrate, such as a silicon substrate, and it can also be at least one of the materials mentioned below: Si, Ge, SiGe, SiC, SiGeC, InAs, GaAs, InP, or other III / V compound semiconductors, and also includes multilayer structures composed of these semiconductor materials, etc., or is silicon-on-insulator (SOI), stacked silicon-on-insulator (SSOI), stacked silicon-germanium-on-insulator (S-SiGeOI), silicon-germanium-on-insulator (SiGeOI), and germanium-on-insulator (GeOI), or can also be a double-sided polished wafer (DSP), and can also be a ceramic substrate such as alumina, a quartz or glass substrate, etc.

[0074] Next, as Figure 4AAs shown, a first sacrificial layer 406 and a third signal acquisition layer 405 are sequentially formed on the first substrate 400. The third signal acquisition layer 405 is patterned to form one or more vent holes therein, and the ratio of the area of the vent holes to the total area of the third signal acquisition layer is less than 5%. Then, a second sacrificial layer 407 and a signal output layer 404 are sequentially formed on the third signal acquisition layer 405. The signal output layer 404 is patterned to form a plurality of acoustic holes therein. Then, a third sacrificial layer 408 and a second signal acquisition layer 403 are sequentially formed on the signal output layer 404. The second signal acquisition layer 403 is patterned to form a plurality of acoustic holes therein. Optionally, a fourth sacrificial layer 409 is formed on the second signal acquisition layer 403.

[0075] Among them, the materials of the first sacrificial layer 406, the second sacrificial layer 407, the third sacrificial layer 408, and the fourth sacrificial layer 409 include but are not limited to silicon dioxide. The thicknesses of the second sacrificial layer 407 and the fourth sacrificial layer 409 are less than 0.5 mm, and the thickness range of the third sacrificial layer 408 includes 1.5 μm to 2.5 μm. The third signal acquisition layer 405, the signal output layer 404, and the second signal acquisition layer 403 at least include a polysilicon layer. Optionally, one or both sides (i.e., the upper surface and / or the lower surface) of the polysilicon layer have a passivation layer (e.g., a silicon nitride layer). The thickness range of the third signal acquisition layer 405 includes 5000 Å to 8000 Å, and the thickness ranges of the signal output layer 404 and the second signal acquisition layer 403 include 1 μm to 2 μm. The formation processes of the above-mentioned first sacrificial layer 406, third signal acquisition layer 405, second sacrificial layer 407, signal output layer 404, third sacrificial layer 408, second signal acquisition layer 403, and fourth sacrificial layer 409 can adopt any existing technologies well-known to those skilled in the art, preferably chemical vapor deposition (CVD), such as low-temperature chemical vapor deposition (LTCVD), low-pressure chemical vapor deposition (LPCVD), metal-organic chemical vapor deposition (MOCVD), rapid thermal chemical vapor deposition (RTCVD), and plasma-enhanced chemical vapor deposition (PECVD).

[0076] Next, as Figure 4BAs shown, to etch and remove the first sacrificial layer 406, the second sacrificial layer 407, the third sacrificial layer 408, and the fourth sacrificial layer 409, any existing technology well-known to those skilled in the art can be used. Wet etching is preferred. The solution of the wet etching method has selectivity. For the case where silicon dioxide is selected for the first sacrificial layer 406, the second sacrificial layer 407, the third sacrificial layer 408, and the fourth sacrificial layer 409 in the present invention, and polysilicon is selected for the third signal acquisition layer 405, the signal output layer 404, and the second signal acquisition layer 403, the solution of the wet etching can be selected as the BOE solution, and the BOE solution is prepared from HF, NH4F, and deionized water.

[0077] In one embodiment, as Figure 4B shown, the remaining portions of the etched first sacrificial layer 406, second sacrificial layer 407, third sacrificial layer 408, and fourth sacrificial layer 409 are used to form the support portions of the third signal acquisition layer 405, the signal output layer 404, and the second signal acquisition layer 403, and the removed portions of the first sacrificial layer 406, second sacrificial layer 407, third sacrificial layer 408, and fourth sacrificial layer 409 form the cavities between the third signal acquisition layer 405, the signal output layer 404, and the second signal acquisition layer 403.

[0078] Next, perform step S320, as Figures 4C - 4D shown, to form the second device structure 420.

[0079] In one embodiment, as Figure 4C shown, provide a second substrate 402. The second substrate 402 can be any suitable semiconductor substrate, which will not be elaborated herein in this application. In one embodiment, the second substrate 402 is single-crystalline silicon or polycrystalline silicon. Form a fifth sacrificial layer 411 and a first signal acquisition layer 401 on the second substrate 402 in sequence. The thickness of the fifth sacrificial layer 411 is less than 0.5 mm, and the thickness range of the first signal acquisition layer 401 includes 5000 Å to 8000 Å. Pattern the first signal acquisition layer 401 to form one or more acoustic holes in the first signal acquisition layer 401, and the ratio of the total area of the plurality of acoustic holes to the total area of the first signal acquisition layer is greater than 30%. The formation processes of the fifth sacrificial layer 411 and the first signal acquisition layer 401 can adopt any existing technology well-known to those skilled in the art, which will not be elaborated herein.

[0080] In one embodiment, as Figure 4DAs shown, the fifth sacrificial layer 411 is etched away. The remaining portion of the fifth sacrificial layer 411 is used to form the support portion of the second substrate 402 and the first signal acquisition layer 401, and the removed portion of the fifth sacrificial layer 411 forms a cavity between the second substrate 402 and the first signal acquisition layer 401. The etching of the fifth sacrificial layer 411 can adopt any existing technology well-known to those skilled in the art. Wet etching is preferably used and will not be elaborated here.

[0081] In one embodiment, it further includes the step of thinning the second substrate 402 until the thickness of the second substrate 402 reaches 5 μm to 20 μm.

[0082] Next, step S330 is executed, as Figure 4E shown, bonding the first device structure 410 and the second device structure 420: bonding the second substrate 402 and the third support portion, with the second substrate serving as the signal reference layer 402, and the groove forming a third cavity between the signal reference layer and the second signal acquisition layer.

[0083] Thus, the introduction of the key steps of the manufacturing method of the MEMS device of the present invention is completed. For the complete device preparation, there may be other multiple process procedures, which will not be elaborated one by one here.

[0084] It is worth mentioning that the order of the above steps is only an example. On the premise of no conflict, the order of the above steps can also be adjusted or alternately performed, etc.

[0085] The present invention also provides an electronic device, as Figure 5 shown, including a package substrate 500, the MEMS device 510 as described above, and an application-specific integrated circuit (ASIC) chip 520 fixed on the package substrate 500.

[0086] In one embodiment, the MEMS device 510 is fixed on a packaging substrate 500, which can be made of materials such as ceramics, glass, PCB, metal, etc. Generally, materials with less deformation are selected to transfer as little pressure signal as possible to the MEMS device 510 under external pressure. At the same time, for the fixing method of the MEMS device 510, silicone with stress buffering effect is generally selected here, which can reduce the transferred pressure from the substrate. At the same time, an ASIC chip 520 is also placed on the packaging substrate 500. The function of the ASIC chip 520 is to process the signals collected from the MEMS device 510. The signal processing circuit has multiple interface settings, and its main functions are to receive and process mixed signals and provide an effective bias voltage for the operation of the MEMS device 510. The MEMS device 510, the ASIC chip 520, and the packaging substrate 500 are electrically connected through the wirebond process. Similarly, other types of electrical connection methods can be selected here. The packaging substrate and the metal shell together form a receiving cavity to ensure the working state of the MEMS device. Here, we set two openings (ports). Among them, we define the bottom opening as the first sound hole and the top opening as the second sound hole. These sound holes can collect environmental noise signals from both the upper and lower sides. However, similarly, under the action of the effective sound signal, it will act on the upper and lower vibrating diaphragms through the upper and lower sound holes respectively. Since the sound response generated by the upper layer is very small, it can be ignored here. Its signal processing method is carried out according to Signal Processing Method 1 to obtain a high-quality sound signal. At the same time, here we propose a more accurate signal processing method. Its main improvement methods are: first, eliminate the sound signal response entering from the upper sound hole; second, consider the influence of all subtle vibration signals of the structure: the signal finally output by the device is the output signal of the signal output layer 104, which is a mixed multi-media signal. There are effective sound signals and environmental noise signals in the gas medium, and environmental noise signals in the solid medium. We extract all sound signals except those in the gaseous medium to accurately eliminate them. Here, in particular, a certain proportion of effective sound signal components are mixed in the environmental noise of the gaseous medium. The reason is that the effective sound signal acts on the first signal acquisition layer 101 and the third signal acquisition layer 105 through the two sound holes respectively, but its response to this signal is different. Here we use G A to represent its different response gains. This value is related to the effective area and yield of the first signal acquisition layer 101 and the second signal acquisition layer 103, as described above. The effective sound signal S4 A =S1 A *G A .

[0087] In one embodiment, as Figure 6As shown, we set a reference value of S1 A which is dynamically affected by the change of S4 A , and this also ensures the reliability of signal cancellation. We perform precise input calculations on gaseous medium noise and solid medium noise respectively. For solid medium noise: Since the output signal of the signal output layer 104 is derived from the signal capture of the third signal acquisition layer 105, its solid medium noise comes from two parts. The first is the solid medium noise of the third signal acquisition layer 105, and the noise value is N4 S = N3 S ×G2 S ; Additionally, the signal output layer 104 has the same solid noise conduction characteristics as the second signal acquisition layer 103, and it will move synchronously under the influence of solid medium noise. Here, we denote the yield displacements of the solid medium noise of the signal output layer 104 and the third signal acquisition layer 105 as ▲x1 and ▲x2 respectively, then ▲x1 < ▲x2. Therefore, the actual value of the solid medium noise signal generated on the signal output layer 104 is N4 S - N3 S , that is, N3 S (G2 S - 1). The processing of gaseous medium noise is relatively complex because the first signal acquisition layer 101 contains low-amplitude effective sound signals, that is, S4 A / G A , so this gaseous medium noise signal needs to cancel two parts, S1 A and N1 G . The method we mentioned here is to remove the gaseous medium mixed signal from the first signal acquisition layer 101 from the gaseous medium mixed signal of the signal output layer 104. During this process, the effective signal from the first signal acquisition layer 101 is not extracted, so it is eliminated from the output signal of the signal output layer 104 during signal processing. Here, we set a reference S1 A to compensate for this signal loss.

[0088] According to the MEMS device, its manufacturing method, and the electronic device provided by the present invention, by setting multiple signal acquisition layers on the acoustic sensor to respectively acquire effective sound signals, solid medium environmental noise signals, and gaseous medium environmental noise signals, through the pickup, superposition, and filtering processing of different types of sound signals, the influence of environmental noise is finally eliminated to improve the sound quality and reduce or eliminate the interference of environmental noise.

[0089] The present invention has been described by the above embodiments. However, it should be understood that the above embodiments are only for illustrative and explanatory purposes, and are not intended to limit the present invention to the scope of the described embodiments. In addition, those skilled in the art can understand that the present invention is not limited to the above embodiments, and more variations and modifications can be made according to the teachings of the present invention, and these variations and modifications all fall within the scope of protection required by the present invention. The scope of protection of the present invention is defined by the appended claims and their equivalent scope.

Claims

1. A MEMS device, characterized in that, it includes a substrate, a signal reference layer, a first signal acquisition layer, a second signal acquisition layer, a third signal acquisition layer and a signal output layer, wherein, the signal reference layer is connected to the substrate to move synchronously with the substrate, and there is a spacing between the signal reference layer and the substrate; the first signal acquisition layer and the signal reference layer form a first capacitor for acquiring gaseous medium ambient noise signals and solid medium ambient noise signals; the second signal acquisition layer and the signal reference layer form a second capacitor, and the second capacitor is used for acquiring the solid medium ambient noise signal; the third signal acquisition layer and the signal output layer form a third capacitor for acquiring the gaseous medium ambient noise signal, the solid medium ambient noise signal and the effective sound signal; the signal output layer is used for outputting the effective sound signal.

2. The MEMS device according to claim 1, characterized in that, the first signal acquisition layer and the second signal acquisition layer are respectively located above or below the signal reference layer.

3. The MEMS device according to claim 1, characterized in that, the first signal acquisition layer and the third signal acquisition layer are flexible structure layers, the second signal acquisition layer and the signal output layer are rigid structure layers, the flexible structure layers are affected by the gaseous medium ambient noise signals, the rigid structure layers are not affected by the gaseous medium ambient noise signals, and the signal reference layer is not affected by the gaseous medium ambient noise signals and the solid medium ambient noise signals.

4. The MEMS device according to claim 3, characterized in that, the rigid structure layer includes a polysilicon layer and a passivation layer formed on the upper surface and / or the lower surface of the polysilicon layer, and the passivation layer includes a silicon nitride layer.

5. The MEMS device according to claim 3, characterized in that, the thickness of the flexible structure layer is less than the thickness of the rigid structure layer, the thickness range of the flexible structure layer includes 5000A - 8000A, the thickness range of the rigid structure layer includes 1μm - 2μm, and the thickness of the signal reference layer is greater than 5μm.

6. The MEMS device according to claim 1, characterized in that, a plurality of sound holes are formed in the first signal acquisition layer, and the ratio of the total area of the plurality of sound holes to the total area of the first signal acquisition layer is greater than 30%; one or more vent holes are formed in the third signal acquisition layer, and the ratio of the area of the vent hole to the total area of the third signal acquisition layer is less than 5%; the signal reference layer does not include sound holes.

7. The MEMS device according to claim 1, characterized in that, the third signal acquisition layer, the signal output layer, the second signal acquisition layer, the signal reference layer and the first signal acquisition layer are sequentially formed above the substrate from bottom to top.

8. The MEMS device according to claim 8, characterized in that, The spacing between the first capacitor, the second capacitor, and the third capacitor is less than 0.5 mm, and the spacing range between the second signal acquisition layer and the signal output layer is 1.5 μm to 2.5 μm.

9. A manufacturing method of a MEMS device, characterized in that, it includes: Forming a first device structure: Providing a first substrate; Sequentially forming a first sacrificial layer, a third signal acquisition layer, a second sacrificial layer, a signal output layer, a third sacrificial layer, a second signal acquisition layer, and a fourth sacrificial layer on the first substrate, and one or more through holes are formed in each of the third signal acquisition layer, the signal output layer, and the second signal acquisition layer; Removing the first sacrificial layer, the second sacrificial layer, the third sacrificial layer, and the fourth sacrificial layer to form a first cavity and a first support portion between the third signal acquisition layer and the signal output layer, a second cavity and a second support portion between the signal output layer and the second signal acquisition layer, and a groove and a third support portion above the second signal acquisition layer; Forming a second device structure: Providing a second substrate; Sequentially forming a fourth sacrificial layer and a first signal acquisition layer on the second substrate, and a plurality of through holes are formed in the first signal acquisition layer; Removing the fourth sacrificial layer to form a fourth cavity and a fourth support portion between the second substrate and the first signal acquisition layer; Bonding the first device structure and the second device structure: Bonding the second substrate and the third support portion, using the second substrate as a signal reference layer, and the groove forms a third cavity between the signal reference layer and the second signal acquisition layer.

10. An electronic device, characterized in that, it includes: A packaging substrate, the MEMS device according to any one of claims 1 to 8, and an application specific integrated circuit chip are fixed on the packaging substrate.

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