CN119618429A - Pressure sensing chip, pressure sensor and calibration method of pressure sensor - Google Patents
Pressure sensing chip, pressure sensor and calibration method of pressure sensor Download PDFInfo
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Abstract
本公开提供了一种压力传感芯片、压力传感器及压力传感器的校准方法，涉及压力传感器技术领域。压力传感芯片包括上基板、下基板以压敏电阻；所述上基板和所述下基板相对设置，所述上基板和所述下基板由导电材料制成，且所述上基板和所述下基板之间绝缘；所述上基板包括感压膜，所述感压膜和所述下基板之间设有密闭的感压腔；所述压敏电阻连接在所述感压膜，且所述压敏电阻与所述感压膜绝缘，所述感压膜发生形变时所述压敏电阻的电阻值改变。
The present disclosure provides a pressure sensing chip, a pressure sensor and a pressure sensor calibration method, which relate to the technical field of pressure sensors. The pressure sensing chip includes an upper substrate, a lower substrate and a piezoresistor; the upper substrate and the lower substrate are arranged opposite to each other, the upper substrate and the lower substrate are made of conductive materials, and the upper substrate and the lower substrate are insulated; the upper substrate includes a pressure-sensitive film, and a closed pressure-sensitive cavity is provided between the pressure-sensitive film and the lower substrate; the piezoresistor is connected to the pressure-sensitive film, and the piezoresistor is insulated from the pressure-sensitive film, and the resistance value of the piezoresistor changes when the pressure-sensitive film is deformed.
Description
Technical Field
The disclosure relates to the technical field of pressure sensing, in particular to a pressure sensing chip, a pressure sensor and a calibration method of the pressure sensor.
Background
The pressure sensor is a device capable of converting pressure into an electrical signal, and may be classified into a piezoresistive type, a capacitive type, a resonant type, a piezoelectric type, and the like. The piezoresistive pressure sensor has the characteristics of good stability, low manufacturing cost, compatibility with COMS technology and the like, is widely applied to the fields of automobiles, industrial control, consumer electronics, construction and medical treatment, and is the most widely applied MEMS pressure sensor at present.
However, the pressure sensor is easy to have the problem of reduced precision after a period of use, the pressure sensor needs to be detached for calibration, and the operation is inconvenient.
Disclosure of Invention
The embodiment of the disclosure provides a pressure sensing chip, a pressure sensor and a pressure sensor calibration method, and the pressure sensor is more convenient to calibrate.
In order to achieve the above object, the embodiments of the present disclosure adopt the following technical solutions:
in one aspect, a pressure sensing chip is provided, including an upper substrate, a lower substrate, and a varistor;
The upper substrate and the lower substrate are arranged oppositely, the upper substrate and the lower substrate are made of conductive materials, and the upper substrate and the lower substrate are insulated;
the upper substrate comprises a pressure sensing film, and a closed pressure sensing cavity is arranged between the pressure sensing film and the lower substrate;
The piezoresistor is connected with the pressure sensing film, the piezoresistor is insulated from the pressure sensing film, and the resistance value of the piezoresistor is changed when the pressure sensing film deforms.
In some embodiments, the pressure sensing chip further includes an upper electrode electrically connected to the upper substrate and a lower electrode electrically connected to the lower substrate, the upper electrode and the lower electrode being located at a side of the upper substrate away from the lower substrate.
In some embodiments, a second lap joint structure is disposed in the upper substrate, the second lap joint structure penetrates through the upper substrate along a direction perpendicular to the upper substrate, one end of the second lap joint structure is electrically connected with the lower electrode, the opposite end of the second lap joint structure is electrically connected with the lower substrate, and the lap joint structure is insulated from the upper substrate.
In some embodiments, the upper substrate is provided with a second via hole, the second via hole penetrates through the upper substrate along a direction perpendicular to the upper substrate, the second overlap structure is disposed in the second via hole, and a first insulating layer is disposed between the second overlap structure and an inner wall of the second via hole.
In some embodiments, a second insulating layer is disposed on a side of the upper substrate away from the lower substrate, and the upper electrode, the lower electrode, and the varistor are connected to a side of the second insulating layer away from the lower substrate.
In some embodiments, the pressure sensing die includes a plurality of the piezoresistors connected to form a wheatstone bridge.
In some embodiments, the third insulating layer is formed by oxidizing the lower substrate toward one side of the upper substrate, the upper substrate and the third insulating layer are bonded, or the third insulating layer is formed by oxidizing the upper substrate toward one side of the lower substrate, the lower substrate and the third insulating layer are bonded.
In another aspect, a pressure sensor is provided, comprising a control chip and a pressure sensing chip according to any one of claims 1 to 7, wherein the piezo-resistor, the upper substrate and the lower substrate of the pressure sensing chip are all electrically connected to the control chip.
In yet another aspect, a method for calibrating a pressure sensor is provided, where the method includes:
the method comprises the steps of obtaining a test output value of the pressure sensor, wherein the test output value is the output value of the pressure sensor when a test deformation occurs to a pressure sensing film;
The theoretical output value is an output value corresponding to the test deformation in a mapping relation preset by the pressure sensor;
and compensating the output value of the pressure sensor according to the test output value and the theoretical output value.
In some embodiments, the obtaining the test output value of the pressure sensor includes:
applying test voltage to the upper substrate and the lower substrate, wherein the pressure sensing film generates the test deformation under the action of the test voltage;
and obtaining the output value of the pressure sensor as a test output value.
In some embodiments, the pressure sensitive film is not subjected to external forces when the test output value is obtained.
In some embodiments, the obtaining a theoretical output value of the pressure sensor includes:
The test capacitance value is the capacitance value between the upper substrate and the lower substrate when the pressure sensing film generates the test deformation;
and determining a theoretical output value corresponding to the test capacitance value according to the mapping relation.
According to the pressure sensing chip, the pressure sensor and the calibration method of the pressure sensor, which are provided by the embodiment of the disclosure, the upper substrate and the lower substrate are opposite and are arranged in an insulating way, namely the pressure sensing film and the lower substrate are opposite and are arranged in an insulating way, and the pressure sensing film and the lower substrate are made of conductive materials, so that an equivalent capacitor is formed by the pressure sensing film and the lower substrate. When the pressure sensing film deforms under the action of the force, the electric parameters of the equivalent capacitor change, and the electric parameters of the equivalent capacitor change continuously along with the continuous change of the deformation quantity, namely the deformation quantity of the pressure sensing film and the electric parameters of the equivalent capacitor have a corresponding relation. And because the deformation amount of the pressure sensing film and the magnitude of the acting force have a corresponding relation, the magnitude of the acting force and the electrical parameter of the equivalent capacitance have a corresponding relation. When the pressure sensing chip is calibrated, the acting force can be obtained through the electric parameter calculation of the equivalent capacitor, so that the output value of the sensing chip is calibrated, and the calibration of the sensing chip is more convenient.
Drawings
In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present disclosure, and other drawings may be obtained according to these drawings without inventive effort to a person of ordinary skill in the art.
FIG. 1 schematically illustrates an electronic device;
FIG. 2 schematically illustrates a block diagram of an electronic device;
FIG. 3 schematically illustrates a cross-sectional view of a pressure sensor;
FIG. 4 is a cross-sectional view of a related art pressure sensor chip in an initial state;
FIG. 5 is a cross-sectional view of a related art pressure sensor chip under external pressure;
FIG. 6 schematically illustrates a cross-sectional view of a pressure sensing die;
FIG. 7 is a diagram schematically illustrating the connection of a plurality of varistors;
Fig. 8 to 13 exemplarily show a process diagram of manufacturing a pressure sensor chip;
fig. 14 schematically shows a block diagram of the steps of a method for calibrating a pressure sensor.
Detailed Description
The following description of the technical solutions in the embodiments of the present disclosure will be made clearly and completely with reference to the accompanying drawings in the embodiments of the present disclosure, and it is apparent that the described embodiments are only some embodiments of the present disclosure, not all embodiments. Based on the embodiments in this disclosure, all other embodiments that a person of ordinary skill in the art would obtain without making any inventive effort are within the scope of protection of this disclosure.
In the embodiments of the present disclosure, the words "first," "second," "third," "fourth," etc. are used to distinguish between the same item or similar items that have substantially the same function and function, but merely for clarity of description of the technical solutions of the embodiments of the present disclosure, and are not to be construed as indicating or implying a relative importance or implying an indication of the number of technical features indicated.
In the embodiments of the present disclosure, the meaning of "a plurality" means two or more, and the meaning of "at least one" means one or more, unless specifically defined otherwise.
In the embodiments of the present disclosure, the azimuth or positional relationship indicated by the terms "upper", "lower", etc., are based on the azimuth or positional relationship shown in the drawings, and are merely for convenience of description and simplification of the description, and do not indicate or imply that the apparatus or element referred to must have a specific azimuth, be configured and operated in a specific azimuth, and thus should not be construed as limiting the present disclosure.
The disclosed embodiments provide an electronic device that may be a terminal consumer product (e.g., unmanned aerial vehicle, unmanned ship, robot, etc.) or a 3C electronic product (e.g., a cell phone, portable, tablet, electronic reader, notebook, digital camera, wearable device, headset, watch, etc.). Fig. 1 schematically illustrates an electronic device, and the embodiment shown in fig. 1 is an example of an electronic device 1000 that is a mobile phone.
Fig. 2 exemplarily shows a block diagram of a structure of an electronic device. As shown in fig. 2, the electronic device 1000 includes a processor 100 and a pressure sensor 200 electrically connected to the processor 100. In operation, the pressure sensor 200 collects external pressure information and sends the pressure value of the external pressure to the processor 200 for processing by the processor 100.
Illustratively, the electronic device 1000 may include a housing and a motherboard disposed inside the housing, on which both the processor 100 and the pressure sensor 200 are connected, and through which electrical connection of the processor 100 and the pressure sensor 200 is achieved.
The pressure sensor 200 can be a Micro-Electro-MECHANICAL SYSTEM (MEMS for short), which is a novel sensor with multiple cross disciplines developed on the basis of the microelectronic technology, and has the characteristics of small volume, light weight, low power consumption, easy integration and the like. Pressure sensor 200 may be of the piezoresistive, capacitive, resonant, piezoelectric, etc. type. The piezoresistive pressure sensor has the characteristics of good stability, low manufacturing cost, compatibility with COMS technology and the like, and is widely applied to the fields of automobiles, industrial control, consumer electronics, construction and medical treatment.
The pressure sensor 200 may be used to measure gas pressure, liquid pressure, and contact pressure. The embodiments of the present disclosure are exemplified only with the pressure sensor 200 for measuring the pressure of gas.
Fig. 3 shows an exemplary cross-sectional view of a pressure sensor. As shown in fig. 3, the pressure sensor 200 includes a pressure sensing chip 240 and a control chip 230, the pressure sensing chip 240 being configured to receive an external pressure and generate an electrical signal corresponding to the external pressure, the control chip 230 being configured to determine a pressure value of the external pressure from the electrical signal of the pressure sensing chip 240 and output the determined pressure value as an output value.
With continued reference to fig. 3, the pressure sensor 200 may further include a circuit board 210, a protective cover 220, a first connection line 250, and a second connection line 260.
The circuit board 210 is used to support and connect other components of the pressure sensor 200. Illustratively, the control chip 230 is coupled to a side of the circuit board 210, and the pressure sensing chip 240 is coupled to a side of the control chip 230 remote from the circuit board 210. In practice, the circuit board 210 may be a printed circuit board 210 (Printed Circuit Board, abbreviated as PCB), and the pressure sensor 200 may be electrically connected to an external circuit through the circuit board 210. Illustratively, the pressure sensing chip 240 is electrically connected with the control chip 230 through the first connection line 250, the control chip 230 is electrically connected with the circuit board 210 through the second connection line 260, the circuit board 210 is provided with a metal pad structure, and the metal pad structure is soldered to the motherboard or the test system by reflow soldering to realize the electrical connection of the pressure sensor 200 with the motherboard or the test system.
The protective cover 220 serves to protect the pressure sensing chip 240, the control chip 230, the first connection line 250, the second connection line 260 from an external force collision, etc. Illustratively, the protective cover 220 is fastened to one side of the circuit board 210, so that the protective cover 220 and the circuit board 210 enclose a receiving cavity, and the pressure sensing chip 240, the control chip 230, the first connection wire 250 and the second connection wire 260 are located in the receiving cavity. Illustratively, the protective cover 220 is a metal cover.
The protection cover 220 is provided with a through hole 221, and the receiving chamber is communicated with the external environment through the through hole 221, so that the pressure inside and outside the receiving chamber is equalized. The pressure sensing chip 240 can estimate the pressure outside the accommodating chamber by collecting the pressure inside the accommodating chamber.
Fig. 4 is a sectional view of a related art pressure sensor chip in an initial state, and fig. 5 is a sectional view of the related art pressure sensor chip in a state of being subjected to external pressure. As shown in fig. 4 and fig. 5, the pressure sensing chip in the related art includes a lower plate 101 and an upper plate 102 which are oppositely arranged, a cavity is defined between the lower plate 101 and the upper plate 102, a piezoresistor 103 is arranged on the upper wall of the cavity, when the pressure sensing chip is subjected to external pressure, the upper wall of the cavity deforms to drive the piezoresistor 103 to deform, the resistance value of the piezoresistor 103 changes after deformation, namely, the voltage u at two ends of the piezoresistor 103 changes, so that the pressure value p of the external pressure can be calculated according to the voltage. For example, a functional relation p=f (u) between the voltage u and the pressure value p is obtained (typically, F is a primary function, a secondary function, or a tertiary function).
In the use process of the pressure sensing chip, due to the influence of performances such as use environment, material internal stress, material creep and the like, the curve of the functional relation shifts, and the output result of the pressure sensing chip is inaccurate, so that the pressure sensing chip needs to be calibrated. However, since the pressure sensing chip is already assembled to form a complete machine product, the pressure sensing chip needs to be detached from the complete machine during calibration, and the operation is inconvenient.
In view of this, the embodiments of the present disclosure provide a pressure sensing chip, so that calibration of the pressure sensing chip is more convenient.
Fig. 6 shows an exemplary cross-sectional view of a pressure sensor chip. As shown in fig. 6, the pressure sensing chip 240 includes an upper substrate 30, a lower substrate 10, and a varistor 51. The upper and lower substrates 30 and 10 are disposed opposite to each other, the upper and lower substrates 30 and 10 are made of a conductive material, and the upper and lower substrates 30 and 10 are insulated from each other. The upper substrate 30 includes a pressure-sensitive film, and a closed pressure-sensitive cavity 1 is provided between the pressure-sensitive film and the lower substrate 10. The varistor 51 is connected to the pressure sensitive film, and the varistor 51 is insulated from the pressure sensitive film, and the resistance value of the varistor 51 changes when the pressure sensitive film is deformed.
The pressure sensing film is used for generating deformation when the pressure sensing chip 240 receives external pressure, so as to drive the piezoresistor 51 connected to the pressure sensing film to deform. In order to make the pressure sensing film more easily deformed and thus to improve the sensitivity of the pressure sensing chip 240, the thickness of the pressure sensing film may be set to be thinner than that of other portions of the upper substrate 30.
The pressure sensing film may be integrated with other structures of the upper substrate 30, and may be connected with other structures of the upper substrate 30 through a connection process. Illustratively, a side of the upper substrate 30 facing the lower substrate 10 is provided with a groove 31, and a bottom wall of the groove 31 serves as a pressure-sensitive film. Illustratively, the upper substrate 30 includes a frame and a pressure-sensitive film, which is a thin film or sheet structure and is connected to the frame through an adhesive or bonding process, and the material of the pressure-sensitive film may be the same as or different from the frame.
The upper substrate 30 may include a pressure sensitive film and a connection portion disposed around the pressure sensitive film, and the connection portion is fixedly disposed, for example, the connection portion is fixedly connected with the lower substrate 10. Because the pressure sensing film is of a peripheral solid supporting structure, when the pressure sensing film is subjected to pressure, the middle deformation amount of the pressure sensing film is large, the peripheral deformation amount is small, but the maximum deformation amount of the pressure sensing film is in direct proportion to the average deformation amount of the pressure sensing film, namely the larger the maximum deformation amount is, the larger the average deformation amount is. Here, only the maximum deformation amount of the pressure sensitive film at a fixed pressure was evaluated for simplifying the model. The square pressure-sensitive film is exemplified, and its maximum deformation is shown in the following formula (1).
Where P is the full scale pressure of the pressure sensor 200, a is the side length of the pressure sensing film of the pressure sensor 200, μ is the poisson ratio of the material used for the pressure sensor 200, E is the elastic modulus of the material used for the pressure sensor 200, and h is the thickness of the pressure sensing film of the pressure sensor 200.
The pressure sensing cavity 1 can be a vacuum cavity, and the pressure sensing cavity 1 can be filled with gas. When the pressure sensing cavity 1 is filled with gas, the pressure born by the pressure sensing film is equal to the pressure difference between the inside and the outside of the pressure sensing cavity 1.
The materials of the upper substrate 30 and the lower substrate 10 may be the same or different. Illustratively, the upper and lower substrates 30 and 10 are both silicon substrates.
The varistor 51 is connected to the pressure sensitive film so as to follow the deformation of the pressure sensitive film. Because the deformation occurring near the central area of the pressure sensing film is larger, the piezoresistor 51 can be arranged in the central area of the pressure sensing film or near the central area, so that the deformation amount of the piezoresistor 51 is increased, and the sensitivity of the pressure sensing chip 240 is further improved. Of course, the piezo-resistor 51 may also be disposed near the edge of the pressure sensing film, which is not limited by the embodiments of the present disclosure.
The varistor 51 may be connected to and insulated from the pressure sensitive film by various connection means. For example, the varistor 51 may be bonded to the pressure sensitive film by an adhesive, and the adhesive is located between the varistor 51 and the pressure sensitive film, so that the varistor 51 and the pressure sensitive film are connected and insulated.
The number of the piezoresistors 51 may be one or a plurality. Fig. 7 exemplarily shows a connection relationship diagram of the plurality of piezoresistors 51. For example, as shown in fig. 7, when the varistor 51 is plural, the plural piezoresistors 51 may be connected to form a wheatstone bridge.
Input voltage of wheatstone bridge:
Vin＝Vin+-Vin-
Output voltage of wheatstone bridge:
Vout＝Vout+-Vout-
r1, R2, R3, R4 represent four leg resistances of the Wheatstone bridge, and Vout can be represented by equation (2). In the preparation process of the sensitive chip, r1=r2=r3=r4=r, when external pressure acts on the sensitive chip, the resistances R1 and R3 are reduced by Δr, that is, the resistance values of the two become R- Δr, and the resistances R2 and R4 are increased by Δr, that is, the resistance values of the two become r+Δr, so that Vout is changed, the change amount of Vout is in direct proportion to the pressure value received by the piezoresistive chip, as shown in formula (3), and the pressure signal is converted into a voltage signal.
The upper substrate 30 and the lower substrate 10 are disposed opposite to each other and insulated from each other, i.e., the pressure sensitive film and the lower substrate 10 are disposed opposite to each other and insulated from each other, and the pressure sensitive film and the lower substrate 10 form an equivalent capacitance due to the fact that the pressure sensitive film and the lower substrate 10 are made of conductive materials. When the pressure sensing film deforms under the action of the force, the electric parameters of the equivalent capacitor change, and the electric parameters of the equivalent capacitor change continuously along with the continuous change of the deformation quantity, namely the deformation quantity of the pressure sensing film and the electric parameters of the equivalent capacitor have a corresponding relation. And because the deformation amount of the pressure sensing film and the magnitude of the acting force have a corresponding relation, the magnitude of the acting force and the electrical parameter of the equivalent capacitance have a corresponding relation. When the pressure sensing chip 240 is calibrated, the magnitude of the acting force can be obtained through the electrical parameter calculation of the equivalent capacitor, so that the output value of the sensing chip is calibrated, and the calibration of the sensing chip is more convenient.
The electrical parameters of the equivalent capacitor may include a voltage across the equivalent capacitor, a capacitance value of the equivalent capacitor, and the like.
The pressure sensing chip 240 may further include an upper electrode 61 and a lower electrode 62, the upper electrode 61 being electrically connected to the upper substrate 30, the lower electrode 62 being electrically connected to the lower substrate 10, so that an electrical connection of an equivalent capacitance to an external circuit is achieved through the upper electrode 61 and the lower electrode 62. The upper electrode 61 and the lower electrode 62 may be located on the same side of the pressure sensing die 240, thereby facilitating electrical connection of the pressure sensor 200 to external circuitry. For example, the upper electrode 61 and the lower electrode 62 may be located at a side of the upper substrate 30 remote from the lower substrate 10. Of course, the upper electrode 61 and the lower electrode 62 may be located at a side of the lower substrate 10 away from the upper substrate 30.
An overlap structure may be disposed in the upper substrate 30, penetrating through the upper substrate 30 in a direction perpendicular to the upper substrate 30, one end of the overlap structure is electrically connected with the lower electrode 62, the opposite end of the overlap structure is electrically connected with the lower substrate 10, and the overlap structure is insulated from the upper substrate 30. The lower electrode 62 is electrically connected to the lower substrate 10 through a bonding structure, and the bonding structure is disposed inside the upper substrate 30, thereby making the structure of the pressure sensing chip 240 more compact.
The upper substrate 30 may be provided with a via hole penetrating the upper substrate 30 in a direction perpendicular to the upper substrate 30, the landing structure is disposed in the via hole, and a first insulating layer is disposed between the landing structure and an inner wall of the via hole. The first insulating layer may prevent the landing structure from contacting the upper substrate 30, thereby achieving insulation of the landing structure from the upper substrate 30.
The side of the upper substrate 30 away from the lower substrate 10 may be provided with a second insulating layer 40, and the upper electrode 61, the lower electrode 62 and the pressure sensitive circuit are connected to the side of the second insulating layer 40 away from the lower substrate 10, so as to insulate the lower electrode 62, the piezoresistor 51 and the upper substrate 30.
The lower substrate 10 is oxidized toward one side of the upper substrate 30 to form the third insulating layer 20, and the upper substrate 30 and the third insulating layer 20 are bonded. Or the side of the upper substrate 30 toward the lower substrate 10 is oxidized to form the third insulating layer 20, and the lower substrate 10 and the third insulating layer 20 are bonded.
Illustratively, the upper substrate 30 and the lower substrate 10 are both silicon substrates, and the side of the lower substrate 10 facing the upper substrate 30 is oxidized to form a silicon oxide film, and the upper substrate 30 is bonded to the silicon oxide film to connect the upper substrate 30 and the lower substrate 10. Or the upper substrate 30 is oxidized towards one side of the lower substrate 10 to form a silicon oxide film, and the lower substrate 10 is bonded with the silicon oxide film to realize the connection of the upper substrate 30 and the lower substrate 10.
Fig. 8 to 13 exemplarily show a process diagram of manufacturing the pressure sensor chip 240. As shown in fig. 8 to 13, a process for manufacturing the pressure sensing chip 240 includes the following steps.
A. a first substrate is provided.
The first substrate includes an upper substrate 30, a second insulating layer 40, and a semiconductor layer 50, which are stacked in this order. Illustratively, the first substrate is an SOI material. Wherein the resistivity of the upper substrate 30 is 0.001 Ω or less.
B. a varistor 51 is formed on the first substrate.
For example, the semiconductor layer 50 may be subjected to photolithography, etching, to form the varistor 51.
C. a groove 31 is formed on the first substrate.
For example, the upper substrate 30 is subjected to photolithography and etching to form a groove 31 on the upper substrate 30, and a bottom wall of the groove 31 is a pressure-sensitive film.
D. A second substrate is provided.
The second substrate may be a silicon substrate, and a surface of one side of the silicon substrate is provided with a third insulating layer 20. For example, the surface of a silicon substrate is oxidized to form a silicon oxide film.
E. the first substrate and the second substrate are connected.
The first substrate and the second substrate may be bonded or bonded. For example, the upper substrate 30 is a silicon substrate, the third insulating layer 20 is a silicon oxide film, and the upper substrate 30 and the third insulating layer 20 may be connected to each other by bonding.
After the first substrate and the second substrate are connected, the groove 31 and the second substrate enclose the pressure sensing cavity 1.
F. Etching to form a first via hole 2 and a second via hole 3.
The first via hole 2 penetrates through the second insulating layer 40, so that a part of the structure of the upper substrate 30 is exposed through the first via hole 2. The second via hole 3 penetrates the second insulating layer 40, the upper substrate 30, and the third insulating layer 20, so that a part of the structure of the lower substrate 10 is exposed through the second via hole 3.
G. Forming a lap joint structure.
The first via hole 2 and the second via hole 3 are filled with a metal material, for example, by PVD, CVD or plating, thereby forming a first landing structure 71 and a second landing structure 72.
H. An upper electrode 61 and a lower electrode 62 are formed.
For example, the upper electrode 61 is formed at a position corresponding to the first overlap structure 71 and the lower electrode 62 is formed at a position corresponding to the second overlap structure 72 using a lift-off process. In practical applications, the resistive electrode 63 electrically connected to the varistor 51 may be formed at a position corresponding to the pressure-sensitive electrode.
The embodiment of the disclosure also provides a calibration method of the pressure sensor, which is used for calibrating the pressure sensor. Fig. 14 schematically shows a block diagram of the steps of a method for calibrating a pressure sensor. As shown in fig. 14, the method of calibrating the pressure sensor includes the following steps.
And step 100, obtaining a test output value of the pressure sensor.
When a pressure sensing chip in the pressure sensor receives acting force, the pressure sensing film deforms, so that the resistance value of the piezoresistor is changed. After the resistance value of the varistor changes, the electrical signal of the varistor changes (e.g., the voltage across the varistor, the current flowing through the varistor changes). The control chip can calculate the pressure value of the external acting force according to the electric signal of the piezoresistor and output the pressure value as an output value.
When the calibration is performed, the pressure sensing film can be deformed by applying acting force to the pressure sensing film, the deformation of the pressure sensing film is changed into test deformation, and the output value of the pressure sensor is a test output value when the pressure sensing film is subjected to test deformation.
For example, the pressure sensor is electrically connected to a test system, through which the test output value of the pressure sensor is read.
The acting force applied to the pressure sensing film can be an acting force in the pressure sensing chip, for example, a voltage is applied to the upper substrate and the lower substrate, and charges accumulated in the upper substrate and the lower substrate are opposite in electrical property, so that the pressure sensing film deforms towards the lower substrate under the action of electrostatic force. Of course, the force may also be an external force to the pressure sensing chip, such as increasing the air pressure of the environment in which the pressure sensing chip is located, or directly applying contact pressure on the pressure sensing film.
And step 200, acquiring a theoretical output value of the pressure sensor.
The pressure sensor is preset with a mapping relation, for example, a memory is arranged in the control chip, and the mapping relation is stored in the memory.
The mapping relation comprises the mapping relation between the deformation quantity of the pressure sensing membrane and the theoretical output value of the pressure sensor. For example, after the preparation of the pressure sensor is completed, different acting forces are respectively applied to the pressure sensor chip by using standard high-precision pressure calibration equipment, the output values of the pressure sensor are respectively read, so that the mapping relation between the acting forces and the theoretical output values is generated, different voltages are respectively applied to the upper substrate and the lower substrate, and the output values of the pressure sensor are respectively read, so that the mapping relation between the voltages and the theoretical output values is generated. And the mapping relation between the deformation and the acting force can be calculated through the formula (1), so that the mapping relation between the deformation and the theoretical output value of the pressure sensor can be obtained.
And obtaining a theoretical output value corresponding to the test deformation according to the mapping relation. The mapping relationship may be a table or a functional relationship, which is not limited in the embodiment of the present disclosure.
And step 300, compensating the output value of the pressure sensor according to the test output value and the theoretical output value.
When the difference between the test output value and the theoretical output value is small, the error of the pressure sensor is small, and the output value does not need to be compensated. When the difference between the test output value and the theoretical output value is large, the output value of the pressure sensor needs to be compensated.
The compensation mode can be various, and the difference between the test output value and the theoretical output value can be added to the output value of the pressure sensor, or the theoretical output value can be used as the output value of the pressure sensor.
According to the calibration method for the pressure sensor, the upper substrate and the lower substrate are opposite and are arranged in an insulating mode, namely the pressure sensing film and the lower substrate are opposite and are arranged in an insulating mode, and the pressure sensing film and the lower substrate are made of conducting materials, so that an equivalent capacitor is formed by the pressure sensing film and the lower substrate. When the pressure sensing film deforms under the action of the force, the electric parameters of the equivalent capacitor change, and the electric parameters of the equivalent capacitor change continuously along with the continuous change of the deformation quantity, namely the deformation quantity of the pressure sensing film and the electric parameters of the equivalent capacitor have a corresponding relation. And because the deformation amount of the pressure sensing film and the magnitude of the acting force have a corresponding relation, the magnitude of the acting force and the electrical parameter of the equivalent capacitance have a corresponding relation. When the pressure sensing chip is calibrated, the acting force can be obtained through the electric parameter calculation of the equivalent capacitor, so that the output value of the sensing chip is calibrated, and the calibration of the sensing chip is more convenient.
Optionally, acquiring the test output value of the pressure sensor in step S100 may include:
And S110, applying test voltages to the upper substrate and the lower substrate.
The deformation of the pressure sensing film under the action of the test voltage is changed into test deformation.
And S120, acquiring an output value of the pressure sensor as a test output value.
For example, the output value of the pressure sensor when the test voltage is applied to the upper and lower substrates is read by the test system.
For example, the preset mapping relationship may include a mapping relationship between the voltage between the upper substrate and the lower substrate and the theoretical output value. And determining a theoretical output value corresponding to the test voltage according to the mapping relation, and compensating the output value of the pressure sensor according to the test output value and the theoretical output value.
When a voltage is applied to the upper and lower substrates, the pressure sensitive film is not subjected to an external force, thereby preventing the external force from being applied to the pressure sensitive film, affecting the accuracy of calibration.
Optionally, obtaining the theoretical output value of the pressure sensor in step S200 includes:
step S210, obtaining a test capacitance value.
The upper substrate and the lower substrate are opposite and are arranged in an insulating way, so that the upper substrate and the lower substrate form an equivalent capacitor. When the pressure sensing film is deformed, the distance between the pressure sensing film and the lower substrate is changed, so that the capacitance value of the equivalent capacitor is changed. When the calibration is performed, the deformation of the pressure sensing film is changed into test deformation, and the capacitance value of the equivalent capacitor is the test capacitance value when the pressure sensing film is subjected to test deformation.
And S220, determining a theoretical output value corresponding to the test capacitance value according to the mapping relation.
The mapping may include a mapping between the capacitance value and the theoretical output value. For example, after the preparation of the pressure sensor is completed, different acting forces are respectively applied to the pressure sensor chip by using standard high-precision pressure calibration equipment, and the output value of the pressure sensor and the capacitance value of the equivalent capacitor are respectively read, so that a mapping relation between the capacitance value and the theoretical output value is generated.
And obtaining a theoretical output value corresponding to the test capacitance value according to the mapping relation. The mapping relationship may be a table or a functional relationship, which is not limited in the embodiment of the present disclosure.
When the calibration of the pressure sensor is realized through the capacitance value, the pressure sensing film of the pressure sensing chip can be subjected to external acting force, and can not be subjected to external acting force, so that the environment requirement on the calibration is lower, and the calibration is more convenient.
The foregoing is merely specific embodiments of the disclosure, but the protection scope of the disclosure is not limited thereto, and any person skilled in the art can easily think about changes or substitutions within the technical scope of the disclosure, and it is intended to cover the scope of the disclosure. Therefore, the protection scope of the present disclosure shall be subject to the protection scope of the claims.
Claims (12)
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| CN202311182823.6A CN119618429A (en) | 2023-09-13 | 2023-09-13 | Pressure sensing chip, pressure sensor and calibration method of pressure sensor |
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| CN202311182823.6A CN119618429A (en) | 2023-09-13 | 2023-09-13 | Pressure sensing chip, pressure sensor and calibration method of pressure sensor |
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