A MEMS device and its low-frequency response adjustment method

Abstract

This application provides a MEMS device and a method for adjusting its low-frequency response. In the MEMS device, a sensing structure and a capacitor structure are connected in parallel. Based on this, the resistance and capacitance of each of the sensing and capacitor structures are designed such that the capacitance of the capacitor structure is greater than the capacitance of the sensing structure, and the insulation resistance of the capacitor structure is greater than the insulation resistance of the sensing structure. A positive correlation is established between the time constant of the MEMS device and the insulation resistance of the sensing structure and the capacitance of the capacitor structure. Thus, by adjusting the insulation resistance of the sensing structure and / or the capacitance of the capacitor structure, the time constant of the MEMS device can be adjusted, thereby optimizing the low-frequency response performance of the MEMS device.

Description

Technical Field

[0001] This application relates to the field of microelectromechanical technology, and more specifically, to a MEMS device and a method for adjusting its low-frequency response. Background Technology

[0002] Micro-Electro-Mechanical Systems (MEMS) technology enables high-precision sensing and measurement of various physical and chemical quantities, leading to the widespread application of MEMS sensors. Low-frequency response (lowest response frequency) is a key indicator of a MEMS sensor's ability to detect quasi-static signals. Because piezoelectric principles cannot respond to DC signals, sensors constantly strive for even lower frequency response limits.

[0003] When low-frequency force attenuation is ignored, the lowest response frequency is affected by the time constant, which is only related to the resistivity and relative permittivity of the material and is independent of the sensor's geometry, film thickness, and the combination of multiple sensors. Unlike traditional piezoelectric ceramics, piezoelectric MEMS use extremely thin piezoelectric films. Due to defects generated during the fabrication process, the time constant can easily decrease, thus deteriorating low-frequency response performance.

[0004] Therefore, the low-frequency response of the device is entirely determined by the intrinsic properties of the material and cannot be effectively designed and improved by changing the structural size, film thickness or sensor combination, which has become the main technical bottleneck for the application of piezoelectric MEMS sensors in the field of ultra-low frequency and quasi-static detection. Summary of the Invention

[0005] The purpose of this application is to provide a MEMS device and a method for adjusting its low-frequency response, addressing the shortcomings of the prior art.

[0006] To achieve the above objectives, the technical solutions adopted in the embodiments of this application are as follows: One aspect of this application provides a MEMS device, including: The sensing structure includes a substrate and a piezoelectric diaphragm disposed on the substrate, wherein the piezoelectric diaphragm is connected between a first signal terminal and a second signal terminal of the sensing structure. A capacitor structure is connected to the first signal terminal and the second signal terminal respectively to be connected in parallel with the sensing structure; The capacitance of the capacitor structure is greater than that of the sensing structure, and the insulation resistance of the capacitor structure is greater than that of the sensing structure. The time constant of the MEMS device is positively correlated with the insulation resistance of the sensing structure and the capacitance of the capacitor structure.

[0007] Optionally, the number of piezoelectric diaphragms is at least two, and the at least two independent piezoelectric diaphragms are connected in series and then connected between the first signal terminal and the second signal terminal.

[0008] Optionally, the piezoelectric diaphragm is divided into several independent piezoelectric units by a partition slit, and the several piezoelectric units are connected in series to form a series branch, which is connected between the first signal terminal and the second signal terminal. Optionally, the bandgap of the dielectric film in the capacitor structure is greater than or equal to 5 eV.

[0009] Optionally, the dielectric film of the capacitor structure is a paraelectric material. Optionally, the dielectric film of the capacitor structure is made of at least one of all-carbon, a binary compound comprising group IV, a binary compound comprising group V, and a binary compound comprising group VI.

[0010] Optionally, the capacitance value of the capacitor structure is greater than 10 times the capacitance value of the sensing structure.

[0011] Optionally, the insulation resistance of the capacitor structure is greater than 10 times the insulation resistance of the sensing structure.

[0012] Another aspect of this application provides a method for adjusting the low-frequency response of a MEMS device, applied to a MEMS device including a parallel sensing structure and a capacitor structure, the method comprising: Obtain the target time constant corresponding to the low-frequency response of the MEMS device; The time constant of the MEMS device is adjusted to the target time constant based on the low-frequency response model. The low-frequency response model is used to characterize the relationship between the time constant of the MEMS device and the insulation resistance value of the sensing structure and the capacitance value of the capacitor structure.

[0013] Optionally, the method further includes: Based on MEMS devices, constraints are created: the insulation resistance of the capacitor structure is much greater than the insulation resistance of the sensing structure, and the capacitance of the capacitor structure is much greater than the capacitance of the sensing structure. Based on the constraints, the insulation resistance parameters of the sensing structure, and the capacitance parameters of the capacitor structure, a low-frequency response model is generated. In the low-frequency response model, the time constant of the MEMS device is positively correlated with the insulation resistance parameters of the sensing structure and the capacitance parameters of the capacitor structure.

[0014] The beneficial effects of this application include: This application provides a MEMS device and a method for adjusting its low-frequency response. In the MEMS device, a sensing structure and a capacitor structure are connected in parallel. Based on this, the resistance and capacitance of each of the sensing and capacitor structures are designed such that the capacitance of the capacitor structure is greater than the capacitance of the sensing structure, and the insulation resistance of the capacitor structure is greater than the insulation resistance of the sensing structure. A positive correlation is established between the time constant of the MEMS device and the insulation resistance of the sensing structure and the capacitance of the capacitor structure. Thus, by adjusting the insulation resistance of the sensing structure and / or the capacitance of the capacitor structure, the time constant of the MEMS device can be adjusted, thereby optimizing the low-frequency response performance of the MEMS device. Attached Figure Description To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 One of the equivalent circuit diagrams of a MEMS device provided in the embodiments of this application; Figure 2 This is one of the structural schematic diagrams of a sensing structure provided in an embodiment of this application; Figure 3 A second equivalent circuit diagram of a MEMS device provided in an embodiment of this application; Figure 4 This is a second schematic diagram of a sensing structure provided in an embodiment of this application; Figure 5 A third equivalent circuit diagram of a MEMS device provided for embodiments of this application; Figure 6 This is the third schematic diagram of a sensing structure provided in an embodiment of this application; Figure 7 This is a schematic diagram of a capacitor structure provided in an embodiment of this application.

[0016] Icons: 10-MEMS device; 100-sensing structure; 101-first signal terminal; 102-second signal terminal; 110-substrate; 111-back cavity; 120-piezoelectric diaphragm; 120a-piezoelectric unit; 121-lower electrode; 122-piezoelectric thin film; 123-upper electrode; 200-capacitor structure; 210-substrate; 220-lower electrode; 230-dielectric thin film; 240-upper electrode. Detailed Implementation

[0017] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0018] Piezoelectric sensors based on MEMS technology are a type of microelectromechanical system (MEMS) device that uses a piezoelectric thin film as the core transducer. They typically consist of a single or double-layer piezoelectric thin film, a support layer, and electrodes, forming a movable structure such as a diaphragm or cantilever beam. These sensors have broad application prospects in the detection of dynamic signals such as acceleration, pressure, and sound waves. Low-frequency response is a key performance indicator of piezoelectric sensors, determining the lowest frequency signal (i.e., the slowest changing signal) that the sensor can detect. Due to the limitations of the piezoelectric principle, piezoelectric sensors cannot respond to static signals (DC, frequency 0). Therefore, in practical applications, piezoelectric sensors constantly strive for even lower frequency response limits to achieve near-static signal detection capabilities.

[0019] The low-frequency response performance of a piezoelectric sensor is largely determined by its time constant. Ignoring factors such as force attenuation at low frequencies, the sensor's lowest response frequency is influenced by its resistance and capacitance. Analysis shows that the geometric parameters upon which resistance and capacitance depend (such as electrode area and conductive length) cancel each other out in their product. Therefore, the time constant can be simplified to be related only to the intrinsic properties of the material (i.e., resistivity and relative permittivity, also known as material parameters). This means that without changing the material, the sensor's size, the thickness of the piezoelectric film, or even the series-parallel combination of multiple sensors cannot alter the time constant, and thus cannot fundamentally adjust its upper limit of low-frequency response.

[0020] In view of this, one aspect of the embodiments of this application provides a MEMS device. In the MEMS device, a sensing structure and a capacitor structure are connected in parallel. Based on this, the resistance and capacitance of the sensing structure and the capacitor structure are designed such that the capacitance value of the capacitor structure is greater than the capacitance value of the sensing structure, and the insulation resistance value of the capacitor structure is greater than the insulation resistance value of the sensing structure, establishing a positive correlation between the time constant of the MEMS device and the insulation resistance value of the sensing structure and the capacitance value of the capacitor structure. Thus, by adjusting the insulation resistance value of the sensing structure and / or the capacitance value of the capacitor structure, the time constant of the MEMS device can be adjusted, thereby optimizing the low-frequency response performance of the MEMS device.

[0021] Figure 1 This is one of the equivalent circuit diagrams of a MEMS device provided in an embodiment of this application. The figure shows that the MEMS device 10 includes a sensing structure 100 and a capacitor structure 200.

[0022] Please refer to the reference. Figure 1 and Figure 2 The MEMS device 10 senses external signals through the sensing structure 100. The sensing structure 100 can be fabricated based on MEMS technology. The sensing structure 100 mainly senses signals based on the piezoelectric effect. Therefore, the core transducer material of the sensing structure 100 is a piezoelectric thin film 122. The piezoelectric thin film 122, together with the electrodes, forms a piezoelectric diaphragm 120 to achieve electromechanical conversion.

[0023] A piezoelectric diaphragm 120 is disposed on a substrate 110, which supports it. A back cavity 111 can be formed on the substrate 110, thereby allowing the piezoelectric diaphragm 120 to be suspended to form a diaphragm (i.e., a complete and seamless membrane layer) or a cantilever beam (usually formed by dividing the diaphragm with slits), or other movable structures. Figure 2 As shown, the piezoelectric diaphragm 120 disposed on the substrate 110 is a diaphragm.

[0024] It should be understood that the piezoelectric diaphragm 120 may include at least one piezoelectric thin film 122 and several layers of electrodes, such as Figure 2 The diagram shows that the piezoelectric diaphragm 120 is a single piezoelectric structure, which includes a lower electrode 121, a piezoelectric thin film 122, and an upper electrode 123 stacked sequentially. In addition, the piezoelectric diaphragm 120 can also be a double piezoelectric structure (two piezoelectric thin films 122 and three electrodes), a triple piezoelectric structure (three piezoelectric thin films 122 and four electrodes), etc.

[0025] The sensing structure 100 has a first signal terminal 101 and a second signal terminal 102. A piezoelectric diaphragm 120 is connected between the first signal terminal 101 and the second signal terminal 102 of the sensing structure 100. In this way, the charge generated by the piezoelectric diaphragm 120 through electromechanical conversion can be output to the outside through the first signal terminal 101 and the second signal terminal 102. Therefore, the first signal terminal 101 and the second signal terminal 102 can also be regarded as the signal terminals for the signals output to the outside of the MEMS device 10.

[0026] The capacitor structure 200, as part of the MEMS device 10, is connected to the first signal terminal 101 and the second signal terminal 102, thus being connected in parallel with the sensing structure 100. It should be understood that, due to limitations in the fabrication process, the piezoelectric thin film 122 in the sensing structure 100 and the dielectric thin film 230 in the capacitor structure 200 inevitably have some leakage paths. Therefore, both the sensing structure 100 and the capacitor structure 200 possess capacitance and resistance. In this application, the overall insulation resistance value of the sensing structure 100 is represented by R1, and the capacitance value by C1; the overall insulation resistance value of the capacitor structure 200 is represented by R2, and the capacitance value by C2.

[0027] time constant It is one of the determining parameters of the low-frequency response of MEMS devices, and its expression is: ,in, This is the lowest frequency signal. Ignoring the attenuation caused by force at low frequencies, the lowest response frequency of the MEMS device 10 is entirely determined by the time constant. Therefore, adjusting the time constant of the MEMS device 10 can change its low-frequency response performance.

[0028] Based on the relationship between time constant and capacitance and resistance, a positive correlation is established between the time constant of MEMS device 10 and the insulation resistance value R1 of sensing structure 100 and the capacitance value C2 of capacitor structure 200. By designing the resistance and capacitance of sensing structure 100 and capacitor structure 200 respectively: the capacitance value C2 of capacitor structure 200 is greater than the capacitance value C1 of sensing structure 100, and the insulation resistance value R2 of capacitor structure 200 is greater than the insulation resistance value R1 of sensing structure 100. In this way, the time constant of MEMS device 10 is more influenced by the insulation resistance value R1 of sensing structure 100 and the capacitance value C2 of capacitor structure 200, achieving parameter separation. The main parameters affecting the time constant of MEMS device 10 are separated into the insulation resistance value R1 inside sensing structure 100 and the capacitance value C2 of capacitor structure 200 outside sensing structure 100.

[0029] After parameter separation, the time constant of the MEMS device 10 can be adjusted by changing the insulation resistance value R1 of the sensing structure 100 and / or the capacitance value C2 of the capacitor structure 200, thereby making the low-frequency response performance of the MEMS device 10 designable. Compared with existing solutions that can only adjust the low-frequency response capability of the device by changing the material of the piezoelectric film 122, this application provides more ways to design the low-frequency response capability of the MEMS device 10, no longer limited by the range of materials of the piezoelectric film 122.

[0030] Based on the relationship between time constant and capacitance and resistance, the following can be established: .

[0031] In some possible implementations, when the capacitance value C2 of the capacitor structure 200 is much larger than the capacitance value C1 of the sensing structure 100, the total capacitance of the MEMS device 10 is... Therefore, the time constant of MEMS device 10 is: That is, the capacitance value C2 of capacitor structure 200 has a more significant impact on the time constant of MEMS device 10. In other words, by adjusting the capacitance value C2 of capacitor structure 200, the time constant of MEMS device 10 can be significantly changed, which is beneficial to increasing the adjustment range of the time constant of MEMS device 10.

[0032] In some possible implementations, when the insulation resistance R2 of the capacitor structure 200 is much greater than the insulation resistance R1 of the sensing structure 100, the total resistance of the MEMS device 10 is... Therefore, the time constant of MEMS device 10 is: That is, the insulation resistance value R1 of the sensing structure 100 has a more significant impact on the time constant of the MEMS device 10. In other words, by adjusting the insulation resistance value R1 of the sensing structure 100, the time constant of the MEMS device 10 can be significantly changed, which is beneficial to increasing the adjustment range of the time constant of the MEMS device 10.

[0033] In some possible implementations, when the capacitance value C2 of the capacitor structure 200 is much larger than the capacitance value C1 of the sensing structure 100, the total capacitance of the MEMS device 10 is... Similarly, when the insulation resistance R2 of the capacitor structure 200 is much greater than the insulation resistance R1 of the sensing structure 100, the total resistance of the MEMS device 10 will be... Therefore, the time constant of MEMS device 10 is: That is, the insulation resistance value R1 of the sensing structure 100 and the capacitance value C2 of the capacitor structure 200 basically determine the time constant of the MEMS device 10. In other words, the changes in the insulation resistance value R1 of the sensing structure 100 and the capacitance value C2 of the capacitor structure 200 can be significantly reflected in the time constant of the MEMS device 10, which is beneficial to further increase the adjustment range of the time constant of the MEMS device 10.

[0034] In some possible implementations, when the capacitance value C2 of the capacitor structure 200 is much greater than the capacitance value C1 of the sensing structure 100, it can be understood that the capacitance value of the capacitor structure 200 is greater than 10 times the capacitance value of the sensing structure 100.

[0035] In some possible implementations, when the insulation resistance value R2 of the capacitor structure 200 is much greater than the insulation resistance value R1 of the sensing structure 100, it can be understood that the insulation resistance value of the capacitor structure 200 is greater than 10 times the insulation resistance value of the sensing structure 100.

[0036] As described above, the insulation resistance and capacitance of capacitor structure 200 must both be greater than those of sensing structure 100. However, if the capacitance value is increased by increasing the size of capacitor structure 200, it will result in a lower insulation resistance (i.e., the larger the size of capacitor structure 200, the lower its resistance). Therefore, simply designing the size of capacitor structure 200 is insufficient to meet the requirements of both capacitor structure 200 and sensing structure 100.

[0037] Furthermore, from the perspective of dielectric materials, conventional capacitors have relatively large leakage currents, making it difficult to meet the requirements for high insulation resistance. For example, to obtain higher capacitance values, ceramic chip capacitors typically use ferroelectric materials such as barium titanate to construct internal spontaneous polarization, thereby increasing the dielectric constant of the material. Additionally, some doping is performed on the material for performance tuning. However, all of these factors lead to increased leakage current, resulting in a lower insulation resistance value. Moreover, conventional electrolytic capacitors, film capacitors, and chip capacitors all have relatively large leakage currents, failing to adequately meet the aforementioned requirements. Therefore, this application designs the capacitor structure 200 to easily meet these requirements.

[0038] It should be understood that in the MEMS devices of this application, the capacitor structure and the sensing structure can be integrated or discretely configured, and the appropriate choice can be made according to actual needs. For example, the capacitor structure can be directly integrated into the sensing structure. Specifically, the capacitor structure can be stacked on the device structure of the sensing structure. If further integration is required, some layers of the two can be shared or fabricated in the same step. Alternatively, the capacitor structure and the sensing structure can each be discrete devices, and the two are connected by leads or the like.

[0039] In some possible implementations, please refer to Figure 7 The capacitor structure 200 includes a substrate 210, a lower electrode 220, a dielectric thin film 230, and an upper electrode 240. Optionally, the substrate 210 of the capacitor structure 200 can be at the same level as the substrate 110 of the sensing structure 100, that is, the capacitor structure 200 and the sensing structure 100 are integrated on the same substrate 110, such as a silicon substrate 110. After the two are integrated, other functional layers, such as a piezoelectric thin film 122, can be provided between the lower electrode 220 and the substrate 210, and other functional layers, such as a passivation layer, can be provided above the upper electrode 240. Of course, the substrate 210 of the capacitor structure 200 can also be independently provided from the substrate 110 of the sensing structure 100, that is, the two are separated from each other.

[0040] In some possible implementations, the bandgap of the dielectric film 230 of the capacitor structure 200 is greater than or equal to 5 eV, thus keeping its intrinsic carrier concentration at a low level, thereby increasing the resistance of the dielectric film 230 and ensuring its low leakage current. At the same time, a larger bandgap also makes it less likely for hot carriers to be excited in the dielectric film 230, and its leakage current will not increase significantly at high temperatures, thus improving stability.

[0041] In some possible implementations, the dielectric film 230 of the capacitor structure 200 is a paraelectric material. This avoids spontaneous polarization of the ferroelectric material and improves stability.

[0042] Multi-component compounds are prone to generating different phases, which can easily lead to defects during growth and ultimately increase leakage current. Therefore, the material of the dielectric film 230 must be strictly controlled to be either an element or a binary compound. In some possible embodiments, the material of the dielectric film 230 of the capacitor structure 200 includes one or more combinations of elemental carbon, binary compounds containing group IV, binary compounds containing group V, and binary compounds containing group VI, such as silicon oxynitride. In this way, the material of the dielectric film 230 is relatively pure, avoiding the possibility that impurities introduced by multi-component compounds may generate energy levels within the band gap. These energy levels (especially at high temperatures) can generate additional charge carriers, causing a sharp increase in leakage current.

[0043] For example, when the dielectric film 230 is made of elemental carbon, it can be diamond. As another example, when the dielectric film 230 is made of binary compounds comprising group IV, group V, or group VI, it can be a carbide (such as silicon carbide), a nitride (such as boron nitride, aluminum nitride, or silicon nitride), or an oxide (such as magnesium oxide, aluminum oxide, gallium oxide, or silicon oxide). It should be noted that the dielectric film 230 in this application is allowed to contain small amounts of impurities or other elements or chemical bonds. The impact of these impurities, elements, or chemical bonds on the overall leakage current is insignificant and controllable. Especially for binary compounds, absolutely pure or ideal binary compounds may be difficult to obtain due to limitations in processing methods. Therefore, small amounts of other elements may be present within them. For example, silicon nitride materials typically contain hydrogen (H) elements, which subsequently form hydrogen bonds. However, it should be understood that binary compounds containing small amounts of impurities or other elements or chemical bonds are not multi-component compounds. They are significantly different from multi-component compounds. For example, barium titanate (BaTiO3) is a ternary compound with a large overall leakage current, which cannot meet the requirements. Barium titanate (BaTiO3) is not a binary compound containing some impurities as mentioned above.

[0044] In some possible implementations, the dielectric film 230 can be a composite structure, for example, the dielectric film 230 can be a double layer or a multilayer layer, wherein at least one layer is the aforementioned elemental or binary compound, and the remaining layers are any dielectric material.

[0045] In some possible implementations, the capacitor structure 200 may not be based on microelectronic processes or silicon substrates, but may be a ceramic capacitor composed of the aforementioned elemental or binary compounds, such as an alumina capacitor.

[0046] In some possible implementations, the dielectric thin film 230 can be deposited by processes such as chemical vapor deposition, physical vapor deposition, atomic layer deposition, and pulsed laser deposition.

[0047] Based on parameter separation, the time constant of the MEMS device 10 can be adjusted by the insulation resistance value R1 of the sensing structure 100 and / or the capacitance value C2 of the capacitor structure 200. The insulation resistance value R1 of the sensing structure 100 can be increased or decreased by designing the internal structure of the sensing structure 100 to form at least two interconnected structures. This will be explained below with reference to the accompanying drawings.

[0048] In some examples, please refer to the reference. Figure 1 and Figure 2 The sensing structure 100 includes a single piezoelectric diaphragm 120, which is not segmented. If the insulation resistance of the piezoelectric diaphragm 120 is R0 and the capacitance is C0, then R1=R0 and C1=C0 for the sensing structure 100.

[0049] In some examples, please refer to the reference. Figure 3 and Figure 4 The sensing structure 100 includes a single piezoelectric diaphragm 120, but the difference lies in that the piezoelectric diaphragm 120 is divided into N independent piezoelectric units 120a. These N piezoelectric units 120a are connected in series (which can be implemented using through-hole interconnect technology) to form a series branch, which is connected between the first signal terminal 101 and the second signal terminal 102. If the insulation resistance of the piezoelectric diaphragm 120 before it is divided is R0 and the capacitance is C0, then the insulation resistance of each piezoelectric unit 120a after division (equal division, or unequal division in other examples) is NR0 and the capacitance is C0 / N. Therefore, the insulation resistance value R1 of the sensing structure 100 is N. 2 ×R0, capacitance value C1=C0 / N 2 The time constant of MEMS device 10 is The time constant of the MEMS device 10 can be adjusted by increasing or decreasing the number of piezoelectric units 120a. .

[0050] It should be understood that when the piezoelectric diaphragm 120 on the substrate 110 is divided into N independent piezoelectric units 120a, it can be as follows: Figure 4 The electrical segmentation shown refers to the lower electrode 121 and upper electrode 123 of the piezoelectric diaphragm 120 being divided by partition slits. In this case, several partition slits are located within the lower electrode 121 and upper electrode 123, so that adjacent small electrode pieces are electrically isolated through the partition slits, but the piezoelectric film 122 is not segmented. Of course, electrical and structural segmentation can also be used, for example in… Figure 4 In the structure shown, the dividing slit extends into the piezoelectric film 122 (forming a slit) so that the piezoelectric diaphragm 120 is completely divided in the thickness direction.

[0051] In some examples, please refer to the reference. Figure 5 andFigure 6 The sensing structure 100 includes N piezoelectric diaphragms 120, but each piezoelectric diaphragm 120 is not segmented (in other examples, it may be segmented to further increase the insulation resistance value R1, referring to the previous example). Different piezoelectric diaphragms 120 are disposed on different substrates 110 (in other examples, different piezoelectric diaphragms 120 may share the same substrate 110), thus, the different piezoelectric diaphragms 120 are independently separated from each other. The N piezoelectric diaphragms 120 are connected in series (which can be implemented based on through-hole interconnect technology) between the first signal terminal 101 and the second signal terminal 102. If the insulation resistance value of each piezoelectric diaphragm 120 is R0 and the capacitance value is C0, then the insulation resistance value R1 of the sensing structure 100 is R1 = N × R0, the capacitance value C1 is C0 / N, and the time constant of the MEMS device 10 is... The time constant of the MEMS device 10 can be adjusted by increasing or decreasing the number of piezoelectric units 120a. .

[0052] In another aspect of this application, a low-frequency response adjustment method for a MEMS device 10 is provided, which is applied to the MEMS device 10. The MEMS device 10 includes a sensing structure 100 and a capacitor structure 200 connected in parallel, such as the aforementioned MEMS device 10.

[0053] The methods include: S10: Obtain the target time constant corresponding to the low-frequency response of MEMS device 10.

[0054] S20: The time constant of MEMS device 10 is adjusted to the target time constant based on the low-frequency response model. The low-frequency response model is used to characterize the relationship between the time constant of MEMS device 10 and the insulation resistance value of sensing structure 100 and the capacitance value of capacitor structure 200.

[0055] First, the desired low-frequency response performance of the MEMS device 10 is determined based on its application requirements. For example, for sensors that need to detect quasi-static signals (such as low-frequency vibrations, slow pressure changes, etc.), the minimum response frequency is required to be as low as possible. Therefore, if the desired minimum response frequency is... The relationship between the time constant and the minimum response frequency can then be expressed as: The corresponding target time constant can then be calculated. This target time constant can also be obtained through simulation or experimental calibration and used as a benchmark for subsequent adjustments.

[0056] Then, based on the relationship between the time constant of the MEMS device 10 and the insulation resistance value of the sensing structure 100 and the capacitance value of the capacitor structure 200, as characterized by the low-frequency response model, parameter separation is achieved. This allows the time constant of the MEMS device 10 to be adjusted by changing the insulation resistance value R1 of the sensing structure 100 and / or the capacitance value C2 of the capacitor structure 200, thereby making the low-frequency response performance of the MEMS device 10 designable. Compared to existing solutions that only allow adjustment of the device's low-frequency response capability by changing the piezoelectric film 122 material, this application provides more avenues for designing the low-frequency response capability of the MEMS device 10, no longer limited by the range of materials available for the piezoelectric film 122.

[0057] Optionally, the method further includes: S30: Based on MEMS device 10, create the following constraints: the insulation resistance of capacitor structure 200 is much greater than the insulation resistance of sensing structure 100, and the capacitance of capacitor structure 200 is much greater than the capacitance of sensing structure 100.

[0058] S40: Based on the constraints, the insulation resistance parameters of the sensing structure 100, and the capacitance parameters of the capacitor structure 200, a low-frequency response model is generated. In the low-frequency response model, the time constant of the MEMS device 10 is positively correlated with the insulation resistance parameters of the sensing structure 100 and the capacitance parameters of the capacitor structure 200.

[0059] In the process of generating the low-frequency response model, it is necessary to introduce constraints based on the capacitor structure 200: the capacitance value C2 of the capacitor structure 200 is much greater than the capacitance value C1 of the sensing structure 100, and the insulation resistance value R2 of the capacitor structure 200 is much greater than the insulation resistance value R1 of the sensing structure 100.

[0060] When generating a low-frequency response model based on the relationship between the time constant of MEMS device 10 and its capacitance and resistance, the capacitance value C1 of sensing structure 100 can be ignored, thus obtaining the total capacitance of MEMS device 10. Similarly, the total resistance of MEMS device 10 Therefore, a low-frequency response model is generated: That is, the insulation resistance value R1 of the sensing structure 100 and the capacitance value C2 of the capacitor structure 200 basically determine the time constant of the MEMS device 10. In other words, the changes in the insulation resistance value R1 of the sensing structure 100 and the capacitance value C2 of the capacitor structure 200 can be significantly reflected in the time constant of the MEMS device 10, which is beneficial to further increase the adjustment range of the time constant of the MEMS device 10.

[0061] The basic principles of this application have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this application are merely examples and not limitations, and should not be considered as essential features of each embodiment of this application. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the application to the necessity of employing the aforementioned specific details for implementation.

[0062] The block diagrams of devices, apparatuses, devices, and systems involved in this application are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, devices, and systems can be connected, arranged, and configured in any manner. Words such as “comprising,” “including,” “having,” etc., are open-ended terms meaning “including but not limited to,” and are used interchangeably with them. The terms “or” and “and” as used herein refer to the terms “and / or,” and are used interchangeably with them unless the context clearly indicates otherwise. The term “such as” as used herein refers to the phrase “such as but not limited to,” and is used interchangeably with it.

[0063] It should also be noted that in the apparatus, equipment, and methods of this application, the components or steps can be disassembled and / or recombined. These disassemblies and / or recombinations should be considered as equivalent solutions of this application.

[0064] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use this application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of this application. Therefore, this application is not intended to be limited to the aspects shown herein, but rather to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0065] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this application to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. A MEMS device, characterized in that, include: A sensing structure includes a substrate and a piezoelectric diaphragm disposed on the substrate, wherein the piezoelectric diaphragm is connected between a first signal terminal and a second signal terminal of the sensing structure. A capacitor structure is connected to the first signal terminal and the second signal terminal respectively to be connected in parallel with the sensing structure; The capacitance value of the capacitor structure is greater than the capacitance value of the sensing structure, the insulation resistance value of the capacitor structure is greater than the insulation resistance value of the sensing structure, and the time constant of the MEMS device is positively correlated with the insulation resistance value of the sensing structure and the capacitance value of the capacitor structure.

2. The MEMS device as described in claim 1, characterized in that, The number of piezoelectric diaphragms is at least two, and the at least two independent piezoelectric diaphragms are connected in series and then connected between the first signal terminal and the second signal terminal.

3. The MEMS device as described in claim 1, characterized in that, The piezoelectric diaphragm is divided into several independent piezoelectric units by a partition slit. Several piezoelectric units are connected in series to form a series branch, which is connected between the first signal terminal and the second signal terminal.

4. The MEMS device according to any one of claims 1 to 3, characterized in that, The dielectric film of the capacitor structure has a bandgap greater than or equal to 5 eV.

5. The MEMS device as described in claim 4, characterized in that, The dielectric film of the capacitor structure is a paraelectric material.

6. The MEMS device as described in claim 5, characterized in that, The dielectric film of the capacitor structure is made of at least one of the following: carbon, a binary compound comprising group IV, a binary compound comprising group V, and a binary compound comprising group VI.

7. The MEMS device according to any one of claims 1 to 3, characterized in that, The capacitance value of the capacitor structure is greater than 10 times the capacitance value of the sensing structure.

8. The MEMS device according to any one of claims 1 to 3, characterized in that, The insulation resistance value of the capacitor structure is greater than 10 times the insulation resistance value of the sensing structure.

9. A method for adjusting the low-frequency response of a MEMS device, characterized in that, Applied to MEMS devices, wherein the MEMS devices include parallel sensing structures and capacitor structures, the method includes: Obtain the target time constant corresponding to the low-frequency response of the MEMS device; The time constant of the MEMS device is adjusted to the target time constant based on the low-frequency response model. The low-frequency response model is used to characterize the relationship between the time constant of the MEMS device and the insulation resistance value of the sensing structure and the capacitance value of the capacitor structure.

10. The method for adjusting the low-frequency response of a MEMS device as described in claim 9, characterized in that, The method further includes: Based on the MEMS device, the following constraints are created: the insulation resistance value of the capacitor structure is much greater than the insulation resistance value of the sensing structure, and the capacitance value of the capacitor structure is much greater than the capacitance value of the sensing structure. Based on the constraints, the insulation resistance parameter of the sensing structure, and the capacitance parameter of the capacitor structure, the low-frequency response model is generated, wherein the time constant of the MEMS device in the low-frequency response model is positively correlated with the insulation resistance parameter of the sensing structure and the capacitance parameter of the capacitor structure.

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