Capacitive pressure sensor

Abstract

The utility model provides a capacitive pressure sensor which mainly comprises a shell and a detection electrode arranged in the shell, the detection electrode divides the shell into a reference cavity and a detection cavity, a fixed electrode and a fixed pole plate are arranged in the reference cavity, the fixed electrode is arranged on the first side of the fixed pole plate, and the fixed pole plate is arranged on the second side of the fixed pole plate. The fixed electrode and the detection electrode are oppositely and parallelly arranged, the detection electrode deforms when the air pressure in the detection cavity changes, the heating plate is arranged on the first side of the fixed electrode and surrounds the fixed electrode, the inner side of the heating plate is matched with the outer side of the fixed electrode, and the outer side of the heating plate is matched with the outer side of the fixed electrode. And the outer side of the heating plate is matched with the shell. According to the capacitive pressure sensor, the interior of the capacitive pressure sensor can be subjected to radiation heating through the heating plate, so that the electrothermal conversion efficiency is higher, the heating uniformity of the detection electrode can be improved, and the measurement precision of the capacitive pressure sensor is further improved.

Description

Technical Field

[0001] The present application relates to the field of sensor technology, and in particular to a capacitive pressure sensor. Background Art

[0002] Capacitive pressure sensor is a device that uses capacitive sensitive elements to sense pressure signals and converts pressure signals into electrical signals according to certain rules. Figure 1 As shown, the capacitive pressure sensor includes: a housing 11; an electrical connector 12 arranged on the housing 11; a fixed electrode 13 arranged in the housing 11; a fixed electrode 14 arranged on one side of the fixed electrode 13; a signal processing circuit 15 arranged on the other side of the fixed electrode 13, and the signal processing circuit 15 is electrically connected to the fixed electrode 14 and the electrical connector 12 respectively; a detection electrode 16, one side of the detection electrode 16 is arranged opposite to the fixed electrode 13, and the other side of the detection electrode 16 is arranged opposite to the detection port 17, and the detection electrode 16 divides the housing into a reference cavity 18 and a detection cavity 19. It should be noted that the detection cavity 19 is connected to the environment to be measured through the detection port 17, so as to obtain the pressure of the environment to be measured.

[0003] Capacitive pressure sensors can be used in semiconductor processes involving vacuum environments to reflect the vacuum level inside the process chamber of the semiconductor process. Since semiconductor processes mostly use a variety of highly corrosive plasma gases such as chlorine-based and fluorine-based gases, and the process is mostly carried out in a high-temperature environment, and the accuracy and full-scale calibration coefficient of capacitive pressure sensors are easily affected by changes in ambient temperature, how to maintain a constant temperature environment for capacitive pressure sensors to improve measurement accuracy is an urgent problem to be solved.

[0004] In the related art, a heating device can be provided on the outer wall of the reference cavity 18, and the heating device heats the capacitive pressure sensor by heat conduction. Figure 1 The chamber is in an ultra-high vacuum state, and it is difficult to achieve heat transfer using the principle of heat conduction. The sensor reference chamber environment cannot be directly heated by the heating device. The capacitive pressure sensor itself obtains relatively little energy, the heating speed is slow, and the reference chamber is heated unevenly, resulting in the capacitive pressure sensor being unable to quickly reach the preset temperature to measure the test environment, and also resulting in low measurement accuracy of the capacitive pressure sensor. Utility Model Content

[0005] The technical problem to be solved by the present application is that the existing capacitive pressure sensors have low measurement accuracy.

[0006] To solve the above technical problems, the present application provides a capacitive pressure sensor, comprising a shell, a detection electrode arranged in the shell, the detection electrode divides the shell into a reference cavity and a detection cavity, a fixed electrode and a fixed electrode plate are arranged in the reference cavity, the fixed electrode is arranged on the first side of the fixed electrode plate, the fixed electrode and the detection electrode are arranged opposite to and parallel to each other, when the air pressure in the detection cavity changes, the detection electrode is deformed, and the air pressure value in the detection cavity is determined based on the capacitance between the deformed detection electrode and the fixed electrode, and also includes: a heating plate arranged on the first side of the fixed electrode plate and surrounding the fixed electrode, the inner side of the heating plate is adapted to the outer side of the fixed electrode, and the outer side of the heating plate is adapted to the shell.

[0007] In some embodiments of the present application, the heating plate is a sheet-type heating plate, or the heating plate is a wire-type heating plate.

[0008] In some embodiments of the present application, the heating plate is fixedly connected to the fixed electrode, or the heating plate is detachably connected to the fixed electrode.

[0009] In some embodiments of the present application, the heating plate is fixedly connected to the fixed electrode by welding, or the heating plate is detachably connected to the fixed electrode by threads.

[0010] In some embodiments of the present application, the capacitive pressure sensor also includes: a temperature sensor arranged on the heating plate, the temperature sensor being used to obtain the real-time temperature of the heating plate; a signal processing circuit arranged on the second side of the fixed electrode plate, the signal processing circuit being electrically connected to the temperature sensor and the heating plate respectively, and the signal processing circuit controlling whether to supply power to the heating plate based on the real-time temperature.

[0011] In some embodiments of the present application, the capacitive pressure sensor further includes: a thermal insulation layer, wherein the thermal insulation layer is used to wrap the fixed plate, the fixed electrode, the heating plate and the detection electrode.

[0012] In some embodiments of the present application, the thermal insulation layer material is a porous material.

[0013] In some embodiments of the present application, the capacitive pressure sensor further includes: a getter, wherein the getter is disposed in the reference cavity.

[0014] In some embodiments of the present application, the heating plate is made of ceramic material or metal material.

[0015] In some embodiments of the present application, the material of the fixed electrode plate is a ceramic material.

[0016] Compared with the prior art, the technical solution of the present application uses the heating plate to radiate heat inside the capacitive pressure sensor, so that the electrothermal conversion efficiency is higher, and the heating uniformity of the detection electrode can be improved, thereby improving the measurement accuracy of the capacitive pressure sensor. Since the radiation heating method does not require contact with the detection electrode, the wavelength, shape, power output and other parameters of the heating plate can be set according to the detection electrode material, so as to achieve precise matching of the detection electrode to quickly convert the radiation energy into heat, increase the heating speed, and thereby improve the measurement accuracy of the capacitive pressure sensor. At the same time, the use of radiation heating can avoid the generation of smoke and surface damage to the shell surface, and can also improve the space utilization of the storage space inside the capacitive pressure sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The following figures describe in detail the exemplary embodiments disclosed in this application. The same reference numerals represent similar structures in several views of the drawings. Those skilled in the art will understand that these embodiments are non-limiting, exemplary embodiments, and the drawings are only for the purpose of illustration and description, and are not intended to limit the scope of this application. Other embodiments may also accomplish the inventive intent in this application. It should be understood that the drawings are not drawn to scale.

[0018] Figure 1 It is a structural schematic diagram of an existing capacitive pressure sensor;

[0019] Figure 2 is a structural schematic diagram of a capacitive pressure sensor according to some embodiments of the present application;

[0020] Figure 3 is a schematic diagram of the relative positions of the fixed electrode and the heating plate according to some embodiments of the present application;

[0021] Figure 4 is a schematic diagram of the relative positions of the heating plate and the detection electrode according to some embodiments of the present application;

[0022] Figure 5 is a schematic structural diagram of another capacitive pressure sensor according to some embodiments of the present application;

[0023] Explanation of the accompanying drawings: 11-shell, 12-electric connector, 13-fixed plate, 14-fixed electrode, 15-signal processing circuit, 16-detection electrode, 17-detection port, 18-reference cavity, 19-detection cavity, 21-heating plate, 22-temperature sensor, 51-insulation layer and 52-absorbent. DETAILED DESCRIPTION

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some examples or embodiments of the present application. For ordinary technicians in this field, the present application can also be applied to other similar scenarios based on these drawings without creative work. Unless it is obvious from the language environment or otherwise explained, the same reference numerals in the figures represent the same structure or operation. It should be clearly understood that the drawings are only for the purpose of illustration and description and are not intended to limit the scope of disclosure of this specification.

[0025] It should be understood that the "module" and "circuit" used herein are a method for distinguishing different components, elements, parts, portions or assemblies at different levels. However, if other words can achieve the same purpose, the words can be replaced by other expressions.

[0026] The terms used in this application are only for the purpose of describing specific example embodiments and are not restrictive. When used in this specification, the terms "include", "comprise" and / or "contain" mean the existence of the associated integers, steps, operations, elements and / or components, but do not exclude the existence of one or more other features, integers, steps, operations, elements, components and / or groups or the addition of other features, integers, steps, operations, elements, components and / or groups in the capacitive pressure sensor. When describing the association of different components in this specification, it can be a direct relationship or an indirect relationship. For example, "A and B are connected" can mean that A and B are directly connected, or A and B are indirectly connected through other components.

[0027] Capacitive pressure sensors can use a thin film (circular metal film or metal-plated film) as an electrode of a capacitor. When the film deforms due to pressure, the capacitance formed between the film and the fixed electrode changes, and an electrical signal with a certain relationship to the voltage can be output through the measuring circuit.

[0028] In the related art, a heating device can be provided on the outer wall of the reference cavity 18, and the heating device heats the capacitive pressure sensor by heat conduction. Figure 1 The chamber is in an ultra-high vacuum state, and it is difficult to achieve heat transfer using the principle of heat conduction. The sensor reference chamber environment cannot be directly heated by the heating device. The capacitive pressure sensor itself obtains relatively little energy and has a slow heating speed (it may take more than 40 minutes to reach the set temperature). In addition, the reference chamber is heated unevenly, resulting in the capacitive pressure sensor being unable to quickly reach the preset temperature to measure the test environment, and also resulting in low measurement accuracy of the capacitive pressure sensor.

[0029] On this basis, in order to improve the problem of long heating time and low efficiency of heating by a heating device, a heating device can also be added in the detection cavity 19, and the influence of temperature change on the stress of the detection electrode 16 is reduced by heating the test environment, so as to improve the measurement accuracy of the capacitive pressure sensor. However, adding a heating device in the detection cavity 19 occupies the volume of the detection cavity 19, and the heating device is easily contaminated by the process environment (strongly corrosive plasma gas and high temperature), resulting in a lower service life of the capacitive pressure sensor. In this way, on the one hand, the degree of improvement in the measurement accuracy of the capacitive pressure sensor is limited, and on the other hand, the risk of reducing the service life of the capacitive pressure sensor is increased.

[0030] Therefore, it is an urgent problem to realize rapid temperature rise and constant temperature control to improve the measurement accuracy of the capacitive pressure sensor without affecting the service life of the capacitive pressure sensor.

[0031] Based on the above analysis, if Figure 2 As shown, the capacitive pressure sensor provided in the embodiment of the present application may include: a housing 11, a detection electrode 16 arranged in the housing 11, the detection electrode 16 divides the housing 11 into a reference cavity 18 and a detection cavity 19, a fixed electrode 14 and a fixed electrode plate 12 are arranged in the reference cavity, the fixed electrode 14 is arranged on the first side of the fixed electrode plate 13, the fixed electrode 14 is arranged opposite to and parallel to the detection electrode 16, when the air pressure in the detection cavity 19 changes, the detection electrode 16 is deformed, and the air pressure value in the detection cavity 19 is determined based on the capacitance between the deformed detection electrode 16 and the fixed electrode 14. The capacitive pressure sensor also includes:

[0032] A heating plate 21 is disposed on the first side of the fixed electrode 13 and surrounds the fixed electrode 14 , wherein the inner side of the heating plate 21 matches the outer side of the fixed electrode 14 , and the outer side of the heating plate 21 matches the housing 11 .

[0033] In the embodiment of the present application, the fixed electrode 14 may be circular or polygonal, and correspondingly, the heating plate 21 may be circular or polygonal.

[0034] In the embodiment of the present application, the capacitive pressure sensor structure is a hollow cylindrical structure, and there is a certain accommodation space inside it. The detection electrode 16 can be connected to the housing 11 by welding, so that the housing 11 is divided into a reference cavity 18 and a detection cavity 19 by the detection electrode 16. The reference cavity 18 will maintain a high vacuum state for a long time when in use, and the vacuum degree is less than 10 -7 The detection chamber 19 is connected to the environment to be detected, and the pressure in the detection chamber 19 is the same as the pressure of the environment to be detected.

[0035] In the embodiment of the present application, the fixed electrode 13 is fixed in the reference cavity 18, the fixed electrode 14 and the heating electrode 21 are fixed on the fixed electrode 13 and are parallel to the detection electrode 16, and the fixed electrode 14 and the detection electrode 16 constitute the sensing component of the capacitive pressure sensor.

[0036] In the embodiments of the present application, Figure 3 As shown, the fixed electrode 14 is a circular sheet, the heating plate 21 is annular, the heating plate 21 is arranged around the periphery of the fixed electrode 14, and the periphery of the heating plate 21 is the shell 11. Figure 4 As shown, when the heating plate 21 is in a heating state, it radiates and heats the detection electrode 16 .

[0037] It should be noted that during the use of the capacitive pressure sensor, the use environment and the heating of the heating plate 21 may cause temperature changes, which may cause the fixed electrode 14, the heating plate 21 and the housing 11 to deform (expand or shrink). Therefore, according to the degree of deformation that may occur in the fixed electrode 14, the heating plate 21 and the housing 11, the distance between the fixed electrode 14 and the heating plate 21, and the distance between the heating plate 21 and the housing 11 can be set to ensure that the inner side of the heating plate 21 is compatible with the outer side of the fixed electrode 14, and the outer side of the heating plate 21 is compatible with the housing 11.

[0038] It should be noted that before using the capacitive pressure sensor, the heating plate 21 can be started to heat up so that the detection electrode 16 is directly heated inside the reference cavity 18 of the capacitive pressure sensor to avoid the deposition of process gases at different temperatures on the detection electrode 16 and the influence of the stress on the detection electrode, thereby ensuring the measurement accuracy of the capacitive pressure sensor.

[0039] In some embodiments of the present application, the heating plate 21 is a sheet-type heating plate, or the heating plate 21 is a wire-type heating plate.

[0040] In some embodiments of the present application, Figure 2 As shown, the capacitive pressure sensor further includes: a temperature sensor 22 disposed on the heating plate 21, the temperature sensor 22 being used to obtain the real-time temperature of the heating plate 21;

[0041] The signal processing circuit 15 is disposed on the second side of the fixed electrode 13 , and is electrically connected to the temperature sensor 22 and the heating plate 21 , respectively. The signal processing circuit 15 controls whether to supply power to the heating plate 21 based on the real-time temperature.

[0042] In the embodiment of the present application, the heating plate 21 is a radiation heating plate, which may be a sheet-type heating plate or a wire-type heating plate. The heating speed of the heating plate 21 is controlled by adjusting the heating power through the signal processing circuit 15 .

[0043] In the embodiment of the present application, the signal processing circuit 15 may be disposed on the second side of the fixed electrode 13 , and the signal processing circuit 15 and the fixed electrode 14 are respectively located on two sides of the fixed electrode 13 .

[0044] In the embodiment of the present application, the fixed electrode 14 is connected to the signal processing circuit 15 through a first wire, and the heating plate 21 is connected to the signal processing circuit 15 through a second wire. The capacitive pressure sensor controls the voltage applied to both ends of the heating plate 21 through the signal processing circuit 15, thereby controlling the temperature of the heating plate 21.

[0045] It is understandable that there is a gap between the fixed electrode plate 13 and the housing 11 , and the first wire and the second wire can bypass the fixed electrode plate 13 and connect to the signal processing circuit 15 .

[0046] In one example, the signal processing circuit 15 sets the heating power and applies a voltage corresponding to the heating power to both ends of the heating plate 21. The heating plate 21 gradually heats up, and the temperature sensor 22 monitors and obtains the real-time temperature of the heating plate 21. Thereafter, the signal processing circuit 15 controls whether to supply power to the heating plate 21 based on the real-time temperature.

[0047] In another example, the signal processing circuit 15 sets the heating power and applies a voltage corresponding to the heating power to both ends of the heating plate 21. The heating plate 21 gradually heats up, and the temperature sensor 22 monitors and obtains the real-time temperature of the heating plate 21. Thereafter, the signal processing circuit 15 controls whether to supply power to the heating plate 21 based on the real-time temperature, and re-determines the voltage applied to both ends of the heating plate 21. The signal processing circuit 15 implements temperature control of the heating plate 21 by a PID control system.

[0048] In some embodiments of the present application, the capacitive pressure sensor further includes: a temperature control switch disposed on the heating plate 21. When the temperature on the heating plate 21 reaches a first predetermined temperature, the temperature control switch opens to cut off the power supply circuit of the heating plate 21, and when the temperature of the reference cavity 18 cools to a second predetermined temperature, the temperature control switch closes to connect the power supply circuit, so that the heating plate 21 resumes the heating working state.

[0049] In this way, the internal temperature of the capacitive pressure sensor is jointly controlled by the signal processing circuit 15 and the temperature sensor 22 so that the interior of the capacitive pressure sensor can maintain a constant temperature, thereby ensuring that the interior of the capacitive pressure sensor maintains a constant temperature state and improving the measurement accuracy of the capacitive pressure sensor.

[0050] In some embodiments of the present application, the heating plate 21 is fixedly connected to the fixed electrode 14 , or the heating plate 21 is detachably connected to the fixed electrode 14 .

[0051] In some embodiments of the present application, the heating plate 21 is fixedly connected to the fixed electrode 14 by welding, or the heating plate 21 is detachably connected to the fixed electrode 14 by threads.

[0052] In this way, the heating plate 21 and the fixed electrode 14 are connected in a fixed connection or a detachable connection manner, so that the relative position between the heating plate 21 and the fixed electrode 14 can be made more stable. On the one hand, it can ensure the effectiveness of the radiant heating of the detection electrode 16. On the other hand, it can ensure that the heating plate 21 will not be mistakenly moved between the fixed electrode 14 and the detection electrode 16, avoiding affecting the capacitance of the capacitive pressure sensor and avoiding affecting the accuracy of the output pressure value.

[0053] In some embodiments of the present application, Figure 5 As shown, the capacitive pressure sensor further includes: a heat insulation layer 51 , and the heat insulation layer 51 is used to wrap the fixed electrode 13 , the fixed electrode 14 , the heating plate 21 and the detection electrode 16 .

[0054] In some embodiments of the present application, the thermal insulation layer 51 is made of porous material.

[0055] In the embodiment of the present application, the material of the thermal insulation layer 51 may also be traditional thermal insulation materials such as glass fiber and asbestos.

[0056] It is understandable that the shell 11 material may be an alloy material, such as Inconel X600, and the detection electrode 16 may also be an alloy material, such as Inconel X750. By enhancing the corrosion resistance of the shell 11 and the detection electrode 16 materials in contact with the semiconductor process environment, the service life of the capacitive pressure sensor in the semiconductor process environment (with strong corrosive gas and high temperature) is improved.

[0057] In the embodiment of the present application, the thermal insulation layer 51 is wrapped around the fixed plate 13, the fixed electrode 14, the heating plate 21 and the detection electrode 16, and the heat generated by the heating plate 21 is blocked from the outside world, so that the interior of the capacitive pressure sensor can maintain a constant temperature, which can not only increase the heating rate of the detection electrode 16, but also ensure that the internal temperature of the capacitive pressure sensor maintains the optimal working temperature, thereby improving the measurement accuracy of the capacitive pressure sensor.

[0058] In some embodiments of the present application, Figure 5 As shown, the capacitive pressure sensor further includes: a getter 52, and the getter 52 is arranged in the reference cavity.

[0059] In the embodiment of the present application, when the capacitive pressure sensor is in use, the detection port 17 is connected to the process chamber of the machine through a flange interface, and the vacuum degree of the process chamber of the machine is detected by direct measurement.

[0060] In the embodiment of the present application, the getter 52 can effectively absorb gas molecules, so that the reference cavity 18 can obtain a vacuum, and ensure that the reference cavity 18 can maintain a high vacuum environment stably for a long time.

[0061] In some embodiments of the present application, the heating plate 21 is made of ceramic material or metal material. The fixed electrode plate 13 is made of ceramic material.

[0062] It is understandable that the material of the heating plate 21 can be determined according to the material of the detection electrode 16, so that the detection electrode 16 can improve the efficiency of converting the radiant heat output by the heating plate 21 into heat.

[0063] The beneficial effects that may be brought about by the embodiments of the present application include but are not limited to: the internal radiation heating of the capacitive pressure sensor by the heating plate 21 makes the electrothermal conversion efficiency higher, and can improve the heating uniformity of the detection electrode 16, thereby improving the measurement accuracy of the capacitive pressure sensor. Since the radiation heating method does not require contact with the detection electrode 16, the wavelength, shape, power output and other parameters of the heating plate 21 can be set according to the material of the detection electrode 16, so as to achieve accurate matching of the detection electrode 16 and quickly convert the radiation energy into heat, thereby improving the heating speed and improving the measurement accuracy of the capacitive pressure sensor. At the same time, the use of radiation heating can avoid the generation of smoke and surface damage to the surface of the shell 11, and can also improve the space utilization rate of the storage space inside the capacitive pressure sensor.

[0064] It should be noted that different embodiments may produce different beneficial effects. In different embodiments, the beneficial effects that may be produced may be any one or a combination of the above, or any other beneficial effects that may be obtained.

[0065] In summary, after reading the contents of this application, those skilled in the art will appreciate that the aforementioned application contents may be presented only in an exemplary manner and may not be restrictive. Although not explicitly stated herein, those skilled in the art will appreciate that this application is intended to encompass various reasonable changes, improvements and modifications to the embodiments. These changes, improvements and modifications are within the spirit and scope of the exemplary embodiments of this application.

[0066] It should also be understood that although the terms first, second, third, etc. can be used to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. Therefore, without departing from the teachings of the present application, the first element in some embodiments can be referred to as the second element in other embodiments. The same reference numerals or the same reference signs represent the same elements throughout the specification.

Claims

1. A capacitive pressure sensor, comprising a shell, a detection electrode arranged in the shell, the detection electrode divides the shell into a reference cavity and a detection cavity, a fixed electrode and a fixed electrode plate are arranged in the reference cavity, the fixed electrode is arranged on a first side of the fixed electrode plate, the fixed electrode and the detection electrode are arranged opposite and parallel to each other, the detection electrode is deformed when the air pressure in the detection cavity changes, and the air pressure value in the detection cavity is determined based on the capacitance between the deformed detection electrode and the fixed electrode, characterized in that: The capacitive pressure sensor also includes: A heating plate is arranged on the first side of the fixed electrode and surrounds the fixed electrode, wherein the inner side of the heating plate is matched with the outer side of the fixed electrode, and the outer side of the heating plate is matched with the shell.

2. The capacitive pressure sensor according to claim 1, characterized in that: The heating plate is a sheet-type heating plate, or the heating plate is a wire-type heating plate.

3. The capacitive pressure sensor according to claim 1, characterized in that: The heating plate is fixedly connected to the fixed electrode, or the heating plate is detachably connected to the fixed electrode.

4. The capacitive pressure sensor according to claim 3, characterized in that: The heating plate is fixedly connected to the fixed electrode by welding, or the heating plate is detachably connected to the fixed electrode by threads.

5. The capacitive pressure sensor according to claim 1, characterized in that: Also includes: A temperature sensor is arranged on the heating plate, and the temperature sensor is used to obtain the real-time temperature of the heating plate; A signal processing circuit is arranged on the second side of the fixed electrode, the signal processing circuit is electrically connected to the temperature sensor and the heating plate respectively, and the signal processing circuit controls whether to supply power to the heating plate based on the real-time temperature.

6. The capacitive pressure sensor according to claim 1, characterized in that: Also includes: A heat insulating layer is used to wrap the fixed plate, the fixed electrode, the heating plate and the detection electrode.

7. The capacitive pressure sensor according to claim 6, characterized in that: The heat insulation layer material is a porous material.

8. The capacitive pressure sensor according to claim 1, characterized in that: Also includes: A getter is disposed in the reference cavity.

9. The capacitive pressure sensor according to claim 1, characterized in that: The heating plate is made of ceramic material or metal material.

10. The capacitive pressure sensor according to claim 1, characterized in that: The fixed electrode plate is made of ceramic material.

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