A plate offset compensation method for a MEMS capacitive pressure sensor

Abstract

The present invention discloses a plate offset compensation method for a MEMS capacitive pressure sensor, comprising: in response to the MEMS capacitive pressure sensor being turned on and being in an unloaded state, obtaining a first pressure indication; in response to the first pressure indication being zero, determining that the plate of the sensing capacitor is offset, obtaining a first capacitance according to the first pressure indication, and collecting a first temperature of the sensing capacitor; obtaining a first dielectric constant according to the first temperature; controlling a heating resistor to heat the sensing capacitor, collecting a second temperature of the sensing capacitor, and obtaining a second pressure indication; obtaining a second dielectric constant according to the second temperature; obtaining a second capacitance according to the second pressure indication; obtaining an actual plate facing area and an actual distance between plates of the sensing capacitor according to the first capacitance, the first dielectric constant, the second capacitance, and the second dielectric constant to compensate the MEMS capacitive pressure sensor. The present invention can compensate for the plate offset, making the measurement result more accurate.

Description

Technical Field

[0001] The invention relates to the field of pressure sensors, and in particular to a plate offset compensation method for a MEMS capacitive pressure sensor. Background Art

[0002] MEMS, the full name of which is Micro-Electro-Mechanical Systems, is a micro system that integrates components such as micro-mechanical structures, sensors, actuators, and electronic control circuits. The size of these components is usually in the micron or millimeter level, so the MEMS system has the characteristics of small size, light weight, low power consumption, and high performance. The MEMS pressure sensor is a pressure measurement device manufactured based on MEMS technology, which has the characteristics of small size, low power consumption, and fast response. MEMS pressure sensors are mainly divided into resistive sensors and capacitive sensors. Among them, capacitive sensors detect pressure by measuring the change in capacitance between two electrodes. When pressure acts on the movable plate of the sensor, the distance or area between the plates changes, resulting in a change in the capacitance value.

[0003] However, the MEMS capacitive pressure sensor may cause the movable plate of the capacitor to deviate due to process reasons or long-term use, and the deviation of the movable plate of the capacitor may make the pressure measurement inaccurate. Summary of the invention

[0004] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is to provide a plate offset compensation method for a MEMS capacitive pressure sensor, aiming to automatically compensate for the plate offset so as to make the pressure measurement result accurate.

[0005] To achieve the above object, the present invention discloses a plate offset compensation method for a MEMS capacitive pressure sensor, the method comprising:

[0006] Step S1, in response to the MEMS capacitive pressure sensor being turned on and being in an unloaded state, obtaining a first pressure indication of the MEMS capacitive pressure sensor; wherein the MEMS capacitive pressure sensor comprises a sensing capacitor, a temperature-rising resistor and a temperature sensor are arranged next to the sensing capacitor, and the sensing capacitor comprises a movable plate and a fixed plate;

[0007] Step S2, judging whether the first pressure indication is zero, if so, determining that the MEMS capacitive pressure sensor is in a normal working state; if not, judging that the plate of the sensing capacitor is offset, obtaining the first capacitance of the sensing capacitor according to the first pressure indication, and proceeding to step S3;

[0008] Step S3, collecting a first temperature of the sensing capacitor by means of the temperature sensor; and obtaining a first dielectric constant of the sensing capacitor according to the first temperature;

[0009] Step S4, controlling the temperature-raising resistor to heat up the sensing capacitor, collecting a second temperature of the sensing capacitor through the temperature sensor, and obtaining a second pressure indication of the MEMS capacitive pressure sensor;

[0010] Step S5, obtaining a second dielectric constant of the sensing capacitor according to the second temperature; and obtaining a second capacitance of the sensing capacitor according to the second pressure indication;

[0011] Step S6, obtaining an actual plate-facing area and an actual distance between the plates of the induction capacitor according to the first capacitance, the first dielectric constant, the second capacitance, and the second dielectric constant;

[0012] Step S7: compensating the MEMS capacitive pressure sensor according to the actual electrode plate facing area and the actual distance between the electrode plates.

[0013] Optionally, the movable electrode plate and the temperature-increasing resistor of the inductive capacitor are formed by photolithography at the same level, and the movable electrode plate and the temperature-increasing resistor are independent of each other.

[0014] Optionally, step S6 includes:

[0015] according to and , solve to obtain the actual plate facing area and the actual distance between the plates of the inductive capacitor; wherein, is the first capacitance, is the first dielectric constant, is the second capacitance, is the second dielectric constant, is the actual plate facing area, is the actual distance between the plates.

[0016] Optionally, the method further includes:

[0017] A first relationship diagram of the dielectric constant of the inductive capacitor changing with temperature is obtained according to the dielectric material of the inductive capacitor.

[0018] Optionally, obtaining a first dielectric constant of the sensing capacitor according to the first temperature in step S3 includes:

[0019] Substitute the first temperature into the first relationship diagram to obtain the first dielectric constant corresponding to the first temperature.

[0020] Optionally, obtaining a second dielectric constant of the sensing capacitor according to the second temperature in step S5 includes:

[0021] Substitute the second temperature into the first relationship diagram to obtain the second dielectric constant corresponding to the second temperature.

[0022] Optionally, the step S7 includes:

[0023] The original plate facing area in the induction capacitance formula is replaced by the actual plate facing area; the distance between the plates in the induction capacitance formula corresponding to a pressure indication of zero is replaced by the actual distance between the plates; and the pressure indication is set to zero.

[0024] Optionally, the method further includes:

[0025] The ambient temperature of the sensing capacitor is collected by the temperature sensor; and temperature compensation is performed on the MEMS capacitive pressure sensor according to the ambient temperature.

[0026] The beneficial effects of the present invention are as follows: 1. The present invention changes the dielectric constant of the inductive capacitor under no-load state by heating through the setting of the temperature-rising resistor and the temperature sensor, and collects the corresponding output pressure indication at the same time, and then obtains the capacitance of the inductive capacitor at different temperatures according to the pressure indication. Finally, the actual plate facing area and the actual distance between the plates are solved by the capacitance and the dielectric constant at different temperatures to perform plate offset compensation on the MEMS capacitive pressure sensor. The present invention can automatically compensate for the plate offset compensation, so that the measurement result is more accurate. 2. The mobile plate and the temperature-rising resistor of the inductive capacitor are formed by photolithography at the same level, and the mobile plate and the temperature-rising resistor are independent of each other. The mobile plate and the temperature-rising resistor are prepared together, which can reduce the additional steps of preparing the temperature-rising resistor, thereby improving the preparation efficiency. 3. Because the present invention is provided with a temperature sensor, the MEMS capacitive pressure sensor can be temperature compensated by collecting the temperature to avoid the influence of the ambient temperature on the measurement result.

[0027] In summary, the present invention can automatically compensate for the plate offset, making the pressure measurement result more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a flow chart of a plate offset compensation method of a MEMS capacitive pressure sensor provided by a specific embodiment of the present invention;

[0029] Figure 2 It is a structural schematic diagram of a MEMS capacitive pressure sensor provided by a specific embodiment of the present invention;

[0030] Figure 3It is a schematic diagram of a process in which an inductive capacitor is offset according to a specific embodiment of the present invention. DETAILED DESCRIPTION

[0031] The present invention discloses a plate offset compensation method for a MEMS capacitive pressure sensor. Those skilled in the art can refer to the content of this article and appropriately improve the technical details to achieve it. It should be particularly noted that all similar replacements and modifications are obvious to those skilled in the art, and they are all considered to be included in the present invention. The method and application of the present invention have been described through preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention.

[0032] The applicant has found through research that the movable plate of the capacitor of the MEMS capacitive pressure sensor may deviate due to process reasons or long-term use. The deviation of the movable plate of the capacitor may make the pressure measurement inaccurate. The existing technology compensates by manually adding standard weights, which is not only time-consuming and labor-intensive, but also prone to compensation errors due to improper operation.

[0033] Therefore, an embodiment of the present invention provides a plate offset compensation method for a MEMS capacitive pressure sensor, such as Figure 1 As shown, the method includes:

[0034] Step S1: in response to the MEMS capacitive pressure sensor being powered on and being in a no-load state, obtaining a first pressure indication of the MEMS capacitive pressure sensor.

[0035] The MEMS capacitive pressure sensor includes a sensing capacitor, a temperature-increasing resistor and a temperature sensor are arranged next to the sensing capacitor, and the sensing capacitor includes a moving electrode plate and a fixed electrode plate.

[0036] It should be noted that the MEMS capacitive pressure sensor is turned on and in a no-load state, which means that the MEMS capacitive pressure sensor is not subjected to any external pressure. At this time, the normal reading should be zero.

[0037] In this specific embodiment, the structure of the MEMS capacitive pressure sensor can be as follows: Figure 2 As shown, Figure 2 middle, Figure 2 In the figure, 201 is a fixed plate, 202 is a movable plate, 203 is a temperature-raising resistor, 204 is a substrate, 205 is a base plate, and 206 is a buried oxide layer of the base plate 205. The base plate 205 is a silicon-based semiconductor process material with a three-layer structure of silicon / insulating layer / silicon prepared by SOI (Silicon-On-Insulator) technology.

[0038] Furthermore, Figure 2 In the embodiment, the moving plate 202 and the temperature-increasing resistor 203 of the inductive capacitor are formed by photolithography at the same level, and the moving plate 202 and the temperature-increasing resistor 203 are independent of each other.

[0039] It should be noted that the moving plate and the temperature-raising resistor are not in the same circuit, and the temperature-raising resistor only plays a heating role.

[0040] Step S2, determine whether the first pressure indication is zero, if so, determine that the MEMS capacitive pressure sensor is in a normal working state; if not, determine that the plate of the sensing capacitor is offset, obtain the first capacitance of the sensing capacitor according to the first pressure indication, and enter step S3.

[0041] It should be noted that when the plate of the sensing capacitor is offset, the first pressure indication will also change and will no longer be zero. Therefore, it can be judged whether the plate of the sensing capacitor is offset.

[0042] In this specific embodiment, the plate offset of the sensing capacitor can be as follows: Figure 3 As shown, Figure 3 In the figure, 301 is a fixed plate, and 302 is a movable plate.

[0043] Step S3: collecting a first temperature of the sensing capacitor by using a temperature sensor; and obtaining a first dielectric constant of the sensing capacitor according to the first temperature.

[0044] It should be noted that the dielectric constant of a capacitor is not only related to the material, but also to the temperature. Changes in temperature will also affect the dielectric constant of the medium. Within a certain temperature range, as the temperature increases, the thermal motion of the molecules intensifies, the polarization and ionization of the molecules decrease, and the dielectric constant decreases. Therefore, in the embodiments of the present invention, the dielectric constant can be changed by changing the temperature, and the dielectric constant of the dielectric material can also be obtained by the temperature.

[0045] Step S4, controlling the heating resistor to heat up the sensing capacitor, collecting a second temperature of the sensing capacitor through the temperature sensor, and obtaining a second pressure indication of the MEMS capacitive pressure sensor.

[0046] It should be noted that as the dielectric constant changes, the capacitance of the inductive capacitor changes, and the corresponding reading also changes.

[0047] Step S5: obtaining a second dielectric constant of the sensing capacitor according to the second temperature; and obtaining a second capacitance of the sensing capacitor according to the second pressure indication.

[0048] In this specific embodiment, the method further includes:

[0049] According to the dielectric material of the sensing capacitor, a first relationship diagram of the dielectric constant of the sensing capacitor changing with temperature is obtained.

[0050] Further, in step S3, obtaining a first dielectric constant of the sensing capacitor according to the first temperature includes:

[0051] Substitute the first temperature into the first relationship diagram to obtain a first dielectric constant corresponding to the first temperature.

[0052] Further, in step S5, obtaining a second dielectric constant of the sensing capacitor according to the second temperature includes:

[0053] The second temperature is substituted into the first relationship diagram to obtain a second dielectric constant corresponding to the second temperature.

[0054] Step S6: Obtaining an actual plate facing area and an actual distance between the plates of the inductive capacitor according to the first capacitance, the first dielectric constant, the second capacitance, and the second dielectric constant.

[0055] In this specific embodiment, step S6 includes:

[0056] according to and , solve to obtain the actual plate facing area and actual plate distance of the inductive capacitor; where, is the first capacitance, is the first dielectric constant, is the second capacitance, is the second dielectric constant, is the actual plate facing area, is the actual distance between the plates.

[0057] It should be noted that the actual plate facing area and the actual distance between the plates can be solved by two sets of known capacitance and dielectric constant. The embodiment of the present invention can automatically perform compensation, reduce compensation operations, and facilitate use.

[0058] Step S7: Compensate the MEMS capacitive pressure sensor according to the actual plate facing area and the actual distance between the plates.

[0059] In this specific embodiment, step S7 includes:

[0060] The original plate facing area in the induction capacitance formula is replaced by the actual plate facing area; the distance between the plates in the induction capacitance formula corresponding to the pressure indication of zero is replaced by the actual distance between the plates; and the pressure indication is set to zero.

[0061] In this specific embodiment, the ambient temperature of the sensing capacitor is collected by a temperature sensor; and temperature compensation is performed on the MEMS capacitive pressure sensor according to the ambient temperature.

[0062] It should be noted that the measurement of MEMS capacitive pressure sensors is also affected by temperature. Therefore, if the temperature is known, temperature compensation can be performed more effectively based on this to increase the accuracy of the measurement results.

[0063] The embodiment of the present invention changes the dielectric constant of the sensing capacitor in the no-load state by setting a heating resistor and a temperature sensor, and collects the corresponding output pressure indication at the same time, and then obtains the capacitance of the sensing capacitor at different temperatures according to the pressure indication. Finally, the actual plate facing area and the actual distance between the plates are solved by the capacitance and dielectric constant at different temperatures to compensate for the plate offset of the MEMS capacitive pressure sensor. The embodiment of the present invention can realize automatic compensation for the plate offset, so that the measurement result is more accurate.

[0064] The moving plate and the temperature-increasing resistor of the inductive capacitor are formed by photolithography at the same level, and the moving plate and the temperature-increasing resistor are independent of each other. The moving plate and the temperature-increasing resistor are prepared together, which can reduce the steps of preparing the temperature-increasing resistor, thereby improving the preparation efficiency.

[0065] Because the temperature sensor is provided in the embodiment of the present invention, the temperature compensation can be performed on the MEMS capacitive pressure sensor by collecting the temperature, thereby avoiding the influence of the ambient temperature on the measurement result.

[0066] In summary, the embodiments of the present invention can automatically compensate for the plate offset, making the pressure measurement result more accurate.

[0067] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0068] Each embodiment in this specification is described in a related manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0069] The above are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A plate offset compensation method for a MEMS capacitive pressure sensor, characterized in that: The method comprises: Step S1, in response to the MEMS capacitive pressure sensor being turned on and being in an unloaded state, obtaining a first pressure indication of the MEMS capacitive pressure sensor; wherein the MEMS capacitive pressure sensor comprises a sensing capacitor, a temperature-rising resistor and a temperature sensor are arranged next to the sensing capacitor, and the sensing capacitor comprises a movable plate and a fixed plate; Step S2, judging whether the first pressure indication is zero, if so, determining that the MEMS capacitive pressure sensor is in a normal working state; if not, judging that the plate of the sensing capacitor is offset, obtaining the first capacitance of the sensing capacitor according to the first pressure indication, and proceeding to step S3; Step S3, collecting a first temperature of the sensing capacitor by means of the temperature sensor; and obtaining a first dielectric constant of the sensing capacitor according to the first temperature; Step S4, controlling the temperature-raising resistor to heat up the sensing capacitor, collecting a second temperature of the sensing capacitor through the temperature sensor, and obtaining a second pressure indication of the MEMS capacitive pressure sensor; Step S5, obtaining a second dielectric constant of the sensing capacitor according to the second temperature; and obtaining a second capacitance of the sensing capacitor according to the second pressure indication; Step S6, obtaining an actual plate-facing area and an actual distance between the plates of the induction capacitor according to the first capacitance, the first dielectric constant, the second capacitance, and the second dielectric constant; Step S7: compensating the MEMS capacitive pressure sensor according to the actual electrode plate facing area and the actual distance between the electrode plates.

2. The plate offset compensation method of the MEMS capacitive pressure sensor according to claim 1, characterized in that: The moving electrode plate and the temperature-increasing resistor of the inductive capacitor are formed by photolithography at the same level, and the moving electrode plate and the temperature-increasing resistor are independent of each other.

3. The plate offset compensation method of the MEMS capacitive pressure sensor according to claim 1, characterized in that: The step S6 comprises: according to and , solve to obtain the actual plate facing area and the actual distance between the plates of the inductive capacitor; wherein, is the first capacitance, is the first dielectric constant, is the second capacitance, is the second dielectric constant, is the actual plate facing area, is the actual distance between the plates.

4. The plate offset compensation method of the MEMS capacitive pressure sensor according to claim 1, characterized in that: The method further comprises: A first relationship diagram of the dielectric constant of the inductive capacitor changing with temperature is obtained according to the dielectric material of the inductive capacitor.

5. The plate offset compensation method of the MEMS capacitive pressure sensor according to claim 4, characterized in that: The step S3 of obtaining a first dielectric constant of the sensing capacitor according to the first temperature includes: Substitute the first temperature into the first relationship diagram to obtain the first dielectric constant corresponding to the first temperature.

6. The plate offset compensation method of the MEMS capacitive pressure sensor according to claim 4, characterized in that: The step S5 of obtaining a second dielectric constant of the sensing capacitor according to the second temperature includes: Substitute the second temperature into the first relationship diagram to obtain the second dielectric constant corresponding to the second temperature.

7. The plate offset compensation method of a MEMS capacitive pressure sensor according to claim 1, characterized in that: The step S7 comprises: The original plate facing area in the induction capacitance formula is replaced by the actual plate facing area; the distance between the plates in the induction capacitance formula corresponding to a pressure indication of zero is replaced by the actual distance between the plates; and the pressure indication is set to zero.

8. The plate offset compensation method of a MEMS capacitive pressure sensor according to claim 1, characterized in that: The method further comprises: The ambient temperature of the sensing capacitor is collected by the temperature sensor; and temperature compensation is performed on the MEMS capacitive pressure sensor according to the ambient temperature.

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