A pressure sensor and a method of manufacturing the same

Abstract

The application provides a pressure sensor and a manufacturing method thereof, and relates to the field of semiconductor manufacturing. A first electrode is arranged on the side of an insulating medium layer close to a diaphragm, and the first electrode and the diaphragm form a first detection capacitor. Since the area of the first electrode is larger than the area of a second electrode and the area of a third electrode, the capacitance of the first detection capacitor is larger than the capacitance of the second detection capacitor and the capacitance of the third detection capacitor. When there is no signal interference caused by non-pressure factors, the product precision can be improved by calculating the pressure of the measured environment through the measurement data of the first detection capacitor. The second electrode and the third electrode are arranged in the same layer between the insulating medium layer and a fixed substrate, and the second electrode and the third electrode form a second detection capacitor and a third detection capacitor with the diaphragm respectively. According to the capacitance of the second detection capacitor and the third detection capacitor, the signal interference caused by non-pressure factors can be eliminated, and then the measurement result with higher precision can be obtained by combining the capacitance of the first detection capacitor, so that the product precision is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of semiconductor manufacturing, and in particular, to a pressure sensor. The present application also relates to a manufacturing method for manufacturing the pressure sensor. BACKGROUND

[0002] At present, a thin film capacitor pressure sensor is made according to the principle that the deformation of an elastic thin film caused by a pressure difference leads to a change in capacitance. The thin film capacitor pressure sensor is mainly used for measuring the vacuum degree in a sealed environment. High-performance vacuum measurement is a necessary guarantee for the production of all semiconductor and photovoltaic devices such as deposition, etching, and heat treatment. Vacuum measurement needs to face complex environments such as high heat, strong corrosion, and multiple gases, and the precision and stability of vacuum measurement directly restrict the level and consistency of process products.

[0003] There are many factors that affect the measurement precision of the thin film capacitor pressure sensor, such as non-pressure factors (temperature, vibration, etc.) interference of the detection environment, the relative effective area of the movable electrode and the fixed electrode, and the relative distance size, etc.

[0004] Therefore, how to improve the precision of the product is a technical problem that needs to be solved by those skilled in the art. SUMMARY

[0005] The present application aims to at least solve one of the technical problems existing in the prior art, and proposes a pressure sensor. Another object of the present application is to provide a manufacturing method for manufacturing the pressure sensor.

[0006] To achieve the object of the present application, a pressure sensor is provided, comprising a shell, a movable film, and a fixed electrode assembly, the shell has a mounting cavity inside, the movable film is sealingly connected to the inner side wall of the mounting cavity, the mounting cavity is divided into a detection cavity and a reference cavity, the fixed electrode assembly is arranged in the reference cavity, the fixed electrode assembly comprises a fixed substrate, an insulating medium layer, a first electrode, a second electrode, and a third electrode, wherein,

[0007] The insulating medium layer is arranged on the side of the fixed substrate close to the movable film;

[0008] The first electrode is arranged on the side of the insulating medium layer close to the movable film, and is used to cooperate with the movable film to obtain a first detection capacitance; the second electrode and the third electrode are arranged in the same layer and insulated from each other between the insulating medium layer and the fixed substrate, and are respectively used to cooperate with the movable film to obtain a second detection capacitance and a third detection capacitance; the area of the first electrode is greater than the area of the second electrode and the area of the third electrode.

[0009] In some embodiments, the pressure sensor further comprises an electrode lead-out structure arranged on the side of the fixed substrate away from the insulating medium layer, the electrode lead-out structure comprises a first electrode connecting part, a second electrode connecting part, and a third electrode connecting part, wherein,

[0010] The first via hole, the second via hole and the third via hole are arranged on the fixed substrate and have conductive layers on the walls of the holes, and the fourth via hole is arranged on the insulating medium layer and has a conductive layer on the wall of the hole, the fourth via hole is coaxially arranged with the first via hole, and the two are electrically connected through a connecting piece;

[0011] The first electrode connecting part is electrically connected with the first electrode through the conductive layers in the first via hole and the fourth via hole; the second electrode connecting part is electrically connected with the second electrode through the conductive layer in the second via hole; and the third electrode connecting part is electrically connected with the third electrode through the conductive layer in the third via hole.

[0012] In some embodiments, the first electrode is a first circular electrode, the second electrode is a second circular electrode, and the third electrode is a circular ring electrode, wherein the circular ring electrode is arranged to surround the second circular electrode at intervals.

[0013] In some embodiments, the axes of the first via hole and the fourth via hole are coincident with the center of the first circular electrode, and a clearance hole is arranged at the center position of the second circular electrode for the connecting piece to pass through, and the second circular electrode is insulated from the connecting piece through the clearance hole.

[0014] The orthographic projection of the second via hole on the insulating medium layer is located in the orthographic projection of the second circular electrode on the insulating medium layer and is spaced apart from the clearance hole; and the orthographic projection of the third via hole on the insulating medium layer is located in the orthographic projection of the circular ring electrode on the insulating medium layer.

[0015] In some embodiments, the dielectric constant of the insulating medium layer is set to be able to increase the capacitance of the second detection capacitor and the third detection capacitor.

[0016] In some embodiments, the dielectric constant of the insulating medium layer is greater than or equal to 10.

[0017] In some embodiments, the thickness of the insulating medium layer is greater than or equal to 5 mm.

[0018] In some embodiments, the thickness of the first electrode, the second electrode and the third electrode is greater than or equal to 1 μm and less than or equal to 20 μm.

[0019] The application also provides a manufacturing method of a pressure sensor, for manufacturing any one of the above pressure sensors, comprising:

[0020] Cleaning the fixed substrate and the insulating medium layer;

[0021] Processing the insulating medium layer and the fixed substrate to form the first electrode, the second electrode and the third electrode;

[0022] Bonding the fixed substrate and the insulating medium layer;

[0023] Sinter the fixed substrate and the insulating medium layer after being bonded and fixed;

[0024] Mounting the movable membrane in the mounting cavity, separating the mounting cavity to form a reference cavity and a detection cavity, and mounting the fixed electrode assembly in the reference cavity;

[0025] Extracting the gas in the reference cavity to form a vacuum chamber in the reference cavity;

[0026] After the extraction is completed, the reference cavity is closed.

[0027] In some embodiments, processing the insulating medium layer and the fixed substrate to form the first electrode, the second electrode and the third electrode comprises:

[0028] Processing the insulating medium layer and the fixed substrate to form the first electrode, the second electrode and the third electrode through a metallization process, the metallization process comprising a magnetron sputtering process, a vacuum evaporation process and a screen printing process.

[0029] The present application has the following beneficial effects:

[0030] In the technical solution provided by the present application, the first electrode is arranged on the side of the insulating medium layer close to the movable membrane, and the first electrode and the movable membrane form a first detection capacitor. Since the area of the first electrode is larger than the areas of the second electrode and the third electrode, the capacitance of the first detection capacitor is larger than the capacitances of the second detection capacitor and the third detection capacitor. When there is no non-pressure factor interference, the product precision can be improved by calculating the pressure of the measured environment through the capacitance of the first detection capacitor. The second electrode and the third electrode are arranged in the same layer between the insulating medium layer and the fixed substrate, and the second electrode and the third electrode form a second detection capacitor and a third detection capacitor with the movable membrane, respectively. According to the capacitances of the second detection capacitor and the third detection capacitor, the signal interference caused by the non-pressure factor can be eliminated, and then the measurement result with higher precision can be obtained by combining the capacitance of the first detection capacitor, thereby improving the product precision. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 A cross-sectional view of a specific embodiment of the pressure sensor provided by the present application;

[0032] Figure 2 A cross-sectional view of a specific embodiment of the pressure sensor provided by the present application; Figure 1 A cross-sectional view of a specific embodiment of the pressure sensor provided by the present application;

[0033] Figure 3 A cross-sectional view of a specific embodiment of the pressure sensor provided by the present application; Figure 2 A cross-sectional view of a specific embodiment of the pressure sensor provided by the present application;

[0034] Figure 4 A cross-sectional view of a specific embodiment of the pressure sensor provided by the present application; Figure 2 A cross-sectional view of a specific embodiment of the pressure sensor provided by the present application;

[0035] Figure 5 A cross-sectional view of a specific embodiment of the pressure sensor provided by the present application; Figure 2C-C cross-sectional view of the fixed electrode assembly.

[0036] Figure 6 For Figure 1 Structure diagram of the pressure sensor;

[0037] Wherein, Figures 1 to 6 The reference signs in the drawings are as follows:

[0038] Fixed electrode assembly 1, fixed substrate 101, insulating dielectric layer 102, first electrode 103, second electrode 104, third electrode 105, first electrode connecting part 106, second electrode connecting part 107, third electrode connecting part 108, first via hole 109, second via hole 110, third via hole 111, fourth via hole 112, diaphragm 2, shell 3, upper seat 301, lower seat 302, pressure lead pipe 303, top cover 4, lead pin 401, through hole 402, fixed block 403, air exhaust pipe 404. DETAILED DESCRIPTION

[0039] In order to enable those skilled in the art to better understand the technical solutions of the present application, the temperature control device provided by the present application and the reaction chamber using the same will be described in detail below with reference to the drawings.

[0040] The pressure sensor provided by the present application has a structure as shown in the figure, which comprises a shell 3 and a diaphragm 2 and a fixed electrode assembly 1 arranged in the shell 3. Figure 1 The diaphragm 2 is provided with a movable electrode, and the fixed electrode assembly 1 is provided with a fixed electrode. The shell 3 has a mounting cavity, and the diaphragm 2 is sealingly connected to the inner side wall of the mounting cavity, thereby separating the mounting cavity into a detection cavity and a reference cavity, and the fixed electrode assembly 1 is arranged in the reference cavity. The shell 3 has a detection hole for connecting the detection cavity with the outside of the shell 3, and the detection hole is provided with a pressure lead pipe 303 for connecting a measured environment. The reference cavity is sealed, and the pressure in the reference cavity is known and remains unchanged. When the pressure of the measured environment changes, the distance between the diaphragm 2 and the fixed electrode assembly 1 (i.e. the movable electrode and the fixed electrode) changes, and according to the calculation formula of the capacitance:

[0041]

[0042] Wherein, C is the capacitance, ε is the dielectric constant of the medium between the two capacitor plates, s is the relative effective area of the two capacitor plates, d is the distance between the two capacitor plates, k is the electrostatic force constant, and π is the circular constant. The two capacitor plates refer to the movable electrode on the diaphragm 2 and the fixed electrode on the fixed electrode assembly 1.

[0043] When the distance between the diaphragm 2 and the fixed electrode assembly 1 changes, the capacitance of the detection capacitor also changes. The value of the pressure of the measured environment can be determined according to the capacitance of the detection capacitor.

[0044] There are three factors affecting the accuracy of thin-film capacitive pressure sensors: resolution, the linearity of the capacitance-pressure function relationship, and interference immunity. Resolution is related to the capacitance of the sensing capacitor; the larger the capacitance, the higher the resolution and the higher the accuracy, and vice versa. A linear relationship between capacitance and pressure results in high accuracy, while a non-linear relationship reduces accuracy. Pressure sensors are frequently subjected to interference from non-pressure factors such as temperature or vibration; therefore, the product's interference immunity directly affects its accuracy.

[0045] Existing technologies typically employ a dual-electrode structure to eliminate interference in capacitance measurement caused by non-pressure factors. However, the dual-electrode structure also affects the resolution of the pressure sensor and the linearity of the capacitance-pressure function relationship. The dual-electrode structure replaces the original single capacitor plate with two mutually insulated capacitor plates (i.e., two fixed electrodes). Because a certain distance is required between them for insulation, the dual-electrode structure reduces the relative effective area between the moving electrode and either fixed electrode, thus decreasing the capacitance and lowering the product's resolution and accuracy. Furthermore, even with changes in the shape of the dual-electrode structure, the relative effective area of ​​its capacitor plates is always smaller than that of a single capacitor plate. While users can increase capacitance by reducing the distance between the electrodes, the distance between the capacitor plates and capacitance are inversely related; only when the distance between the electrodes exceeds a certain range can the relationship between the distance between the capacitor plates and capacitance be approximately linear. Reducing the distance between the electrodes may cause the relationship between the distance between the electrodes and capacitance to enter a non-linear range, where the capacitance-pressure relationship becomes non-linear, ultimately affecting the product's accuracy.

[0046] In some embodiments of this application, such as Figure 2 As shown, the fixed electrode assembly 1 includes a fixed substrate 101, an insulating dielectric layer 102, a first electrode 103, a second electrode 104, and a third electrode 105. The insulating dielectric layer 102 is disposed on the fixed substrate 101 near the moving membrane 2. The first electrode 103 is disposed on the insulating dielectric layer 102 near the moving membrane 2 and cooperates with the moving membrane 2 to obtain a first detection capacitance. The second electrode 104 and the third electrode 105 are disposed in the same layer between the insulating dielectric layer 102 and the fixed substrate 101, and cooperate with the moving membrane 2 respectively to obtain a second detection capacitance and a third detection capacitance. The pressure of the measured environment can be obtained from the capacitances of the first, second, and third detection capacitors.

[0047] In the embodiment, the area of the first electrode 103 is larger than the areas of the second electrode 104 and the third electrode 105. Since the first electrode 103, the second electrode 104 and the third electrode 105 are generally parallel to the diaphragm 2, and the projections of the three electrodes on the diaphragm 2 are all located in the diaphragm 2, the relative effective area of the capacitor plate of any detection capacitor is equal to the area of the fixed electrode in the detection capacitor. Therefore, the relative effective area of the capacitor plate of the first detection capacitor is larger than the relative effective areas of the capacitor plates of the second and third detection capacitors. Meanwhile, the distance between the first electrode 103 and the diaphragm 2 is smaller than the distances between the second electrode 104 and the third electrode 105 and the diaphragm 2. Therefore, the capacitance of the first detection capacitor is larger than the capacitances of the second and third detection capacitors, and the pressure of the measured environment can be measured by the first detection capacitor with higher precision. When the pressure sensor is not disturbed by non-pressure factors, the pressure of the measured environment can be measured by the pressure sensor through the capacitance of the first detection capacitor, so as to improve the product precision of the pressure sensor. The second electrode 104 and the third electrode 105 are arranged in the same layer, and the capacitances of the second and third detection capacitors are affected differently when the pressure sensor is disturbed by non-pressure factors such as temperature or vibration. The influence of non-pressure factors can be reduced or eliminated through the difference between the capacitance of the third detection capacitor and the capacitance of the second detection capacitor, so as to improve the product precision of the pressure sensor.

[0048] In some embodiments, the pressure sensor further comprises an electrode lead-out structure arranged on the side of the fixed substrate 101 away from the insulating medium layer 102. As shown in FIGS. 1B, 1C and 1D, the electrode lead-out structure comprises a first electrode connecting part 106, a second electrode connecting part 107 and a third electrode connecting part 108, which are electrically connected to the first electrode 103, the second electrode 104 and the third electrode 105 respectively. Figure 2 Figure 3 Figure 3 The first electrode connecting part 106, the second electrode connecting part 107 and the third electrode connecting part 108 shown in the figures are in the form of dots or strips, and the shapes of the three parts can also be set as required by the user, which are not limited herein.

[0049] The first via hole 109, the second via hole 110 and the third via hole 111 each having a conductive layer on the hole wall are arranged on the fixed substrate 101, and the fourth via hole 112 having a conductive layer on the hole wall is arranged on the insulating medium layer 102. The fourth via hole 112 is coaxially arranged with the first via hole 109, and the two are electrically connected through a connecting part.

[0050] ​​The first electrode connecting part 106 is electrically connected with the first electrode 103 through the conductive layer in the first via hole 109 and the fourth via hole 112; the second electrode connecting part 107 is electrically connected with the second electrode 104 through the conductive layer in the second via hole 110; and the third electrode connecting part 108 is electrically connected with the third electrode 105 through the conductive layer in the third via hole 111.

[0051] As shown in Figure 3 The first electrode connecting part 106, the second electrode connecting part 107 and the third electrode connecting part 108 are insulated from each other. In addition, the conductive layers in the first via hole 109 and the fourth via hole 112 are electrically connected through a connecting piece which can be inserted between the fixed substrate 101 and the insulating medium layer 102 for fixation. The conductive layers in the first via hole 109 and the fourth via hole 112 are connected with the connecting piece to realize electrical conduction. The second electrode 104 is also insulated from the connecting piece.

[0052] The user can form the conductive layer on the inner wall of the via hole by using a metallization process, which includes a magnetron sputtering process, a vacuum evaporation process and a screen printing process. Of course, the user can also use other processes in the prior art to form the conductive layer on the inner wall of the via hole, which is not limited herein.

[0053] The fixed electrode assembly 1 can be loaded into the mounting cavity at the top of the shell 3, and the mounting cavity is closed by the top cover 4 which is provided with three through holes 402 corresponding to the positions of the first electrode connecting part 106, the second electrode connecting part 107 and the third electrode connecting part 108 respectively, and each of the three through holes 402 is provided with a lead pin 401. The first electrode connecting part 106, the second electrode connecting part 107 and the third electrode connecting part 108 are electrically connected with the lead pin 401 in the through hole 402 corresponding to the position thereof respectively, and the lead pin 401 extends to the outside of the shell 3 for connecting a circuit board or other detection unit. The lead pins in the three via holes connect the first detection capacitor, the second detection capacitor and the third detection capacitor to the detection unit to measure the capacitance of the three, and then obtain the pressure of the measured environment.

[0054] In addition, the through hole 402 is also provided with a fixing block 403, and the lead pin 401 is inserted into the fixing block 403, and the fixing block 403 is used to seal the gap between the lead pin 401 and the through hole 402. Of course, the way of leading the electrode is not limited to this.

[0055] In this embodiment, the electrode is connected to the detection unit through the conductive layer, the electrode connecting part and the lead pin, and the capacitance is detected by the detection unit. The fixed substrate 101 and the insulating medium layer are provided with a via hole, and the conductive layer is arranged in the via hole, so that the conductive layer does not need to occupy additional space, and the volume of the fixed electrode assembly 1 is reduced. In addition, the conductive layer is made of a metallization process, which improves the processing efficiency of the fixed electrode assembly 1 and reduces the processing difficulty.

[0056] In some embodiments, such as Figures 3 to 5 As shown, the first electrode 103 is a first circular electrode, the second electrode 104 is a second circular electrode, and the third electrode 105 is a ring electrode. The ring electrode is arranged around the second circular electrode at intervals, and the ring electrode and the second circular electrode can be arranged concentrically. Of course, the shapes of the first electrode 103, the second electrode 104, and the third electrode 105 are not limited to this.

[0057] The housing 3 of the pressure sensor includes an upper seat 301 and a lower seat 302. The outer edge of the moving diaphragm 2 is located between the upper seat 301 and the lower seat 302 and is sealed to the side wall of the mounting cavity by welding or other methods. The middle part of the moving diaphragm 2 is suspended in the mounting cavity, and the position of the fixed electrode assembly 1 corresponds to that of the moving diaphragm 2. Non-pressure factors can affect the measurement accuracy of the pressure sensor. When affected by factors such as pressure, temperature, or vibration, the moving diaphragm 2 deforms, and the middle part of the moving diaphragm 2 moves towards or away from the fixed electrode assembly 1, thereby causing a change in the capacitance of the sensing capacitor. For example, an increase in temperature will cause the moving diaphragm 2 to expand. Since the outer edge of the moving diaphragm 2 is fixed, the deformation near the center of the moving diaphragm 2 is larger when it expands, and the deformation near the outer edge is smaller. The projection position of the second electrode 104 on the moving membrane 2 is closer to the center of the moving membrane 2 than that of the third electrode 105. Therefore, the change in distance between the second electrode 104 and the moving membrane 2 is greater than the change in distance between the third electrode 105 and the moving membrane 2. Correspondingly, the change in capacitance of the second detection capacitor is greater than the change in capacitance of the third detection capacitor. Based on the changes in capacitance of the second and third detection capacitors, the degree of interference from temperature rise can be determined, thereby eliminating the interference.

[0058] In one specific embodiment of this application, the user can eliminate interference from non-pressure factors by measuring the difference between the capacitance of the third detection capacitor and the capacitance of the second detection capacitor. During the difference calculation, the capacitance change of the second detection capacitor caused by interference will eliminate the capacitance change of the third detection capacitor caused by interference, thereby eliminating interference from non-pressure factors. Of course, the user can also use other methods in the prior art to eliminate interference from non-pressure factors, which are not limited here. Before the product leaves the factory, it is internally calibrated. During the calibration process, a set of experimental data is obtained, including the difference between the capacitance of the third detection capacitor and the capacitance of the second detection capacitor, the capacitance of the first detection capacitor, and the pressure of the measured environment. The correspondence between the difference between the capacitance of the third detection capacitor and the capacitance of the second detection capacitor and the pressure of the measured environment, and the correspondence between the capacitance of the first detection capacitor and the pressure of the measured environment, are obtained respectively. The user can obtain the pressure of the measured environment by measuring the difference between the capacitance of the third detection capacitor and the capacitance of the second detection capacitor or the capacitance of the first detection capacitor through the above two correspondences.

[0059] In some embodiments, the axes of the first via hole 109 and the fourth via hole 112 are both coincident with the center of the first circular electrode, and a clearance hole is arranged at the center position of the second circular electrode for the connection member to pass through; the connection member can adopt a T-shaped structure, the middle part of which has a plug-in block or the like structure, which can be inserted and fixed between the fixed substrate 101 and the insulating dielectric layer 102, and the upper and lower ends of the connection member are connected with the conductive layers in the first via hole 109 and the fourth via hole 112 respectively, so as to electrically conduct the two conductive layers. The clearance hole can avoid the contact between the second electrode 104 and the plug-in block. A plurality of connection members can be arranged between the first via hole 109 and the fourth via hole 112, and all the connection members can be uniformly distributed along the circumference of the first via hole 109, so as to increase the connection area between the first via hole 109 and the fourth via hole 112 and reduce the connection resistance.

[0060] The orthogonal projection of the second via hole 110 on the insulating dielectric layer 102 is located in the orthogonal projection of the second circular electrode on the insulating dielectric layer 102 and is spaced from the clearance hole, so as to avoid the contact between the conductive layer in the second via hole 110 and the connection member, while ensuring that the connection part between the conductive layer and the second circular electrode is relatively long and reducing the connection resistance between the conductive layer and the second circular electrode; the orthogonal projection of the third via hole 111 on the insulating dielectric layer 102 is located in the orthogonal projection of the annular electrode on the insulating dielectric layer 102, and the position of the third via hole 111 can also reduce the connection resistance between the conductive layer and the annular electrode. Of course, the positions of the first via hole 109, the second via hole 110, the third via hole 111 and the fourth via hole 112 are not limited to this.

[0061] In some embodiments, the dielectric constant of the insulating dielectric layer 102 is set to be able to increase the capacitance of the second detection capacitor and the third detection capacitor.

[0062] According to the calculation formula of the capacitor, it can be determined that the capacitance is proportional to the dielectric constant of the medium between the two capacitor electrodes, and the capacitance of the second detection capacitor and the third detection capacitor will increase with the increase of the dielectric constant of the insulating dielectric layer 102. In this embodiment, the insulating dielectric layer with a larger dielectric constant can increase the capacitance of the second detection capacitor and the third detection capacitor.

[0063] In some embodiments, the dielectric constant of the insulating dielectric layer 102 is greater than or equal to 10.

[0064] In some embodiments, the thickness of the insulating dielectric layer 102 is greater than or equal to 5 mm. The medium between the second electrode 104, the third electrode 105 and the moving membrane 2 includes the insulating dielectric layer 102 and the gap between the insulating dielectric layer 102 and the moving membrane 2, according to the Likhita formula: ε eff = v1ε1 + v2ε2, wherein, ε effThe effective dielectric constant of the composite medium is calculated by multiplying the volume percentage of the first medium v1, the dielectric constant of the first medium ε1, the volume percentage of the second medium v2, and the dielectric constant of the second medium ε2. The composite medium can include more than two kinds of medium, and the volume percentage and dielectric constant of each medium are multiplied and added to obtain the dielectric constant of the composite medium. The medium in the gap between the insulating medium layer 102 and the diaphragm 2 is air or vacuum, and the dielectric constant is 1. The dielectric constant of the insulating medium layer 102 is greater than or equal to 10, so the dielectric constant of the composite medium in the second detection capacitor and the third detection capacitor can be increased. According to the formula for calculating the capacitance:

[0065]

[0066] The capacitance and the dielectric constant are in a linear relationship. When the dielectric constant of the composite medium increases, the capacitance of the second detection capacitor and the third detection capacitor also increases accordingly.

[0067] In addition, increasing the volume percentage of the insulating medium layer 102 can further increase the dielectric constant of the composite medium, thereby increasing the capacitance of the second detection capacitor and the third detection capacitor. When the area of the second electrode 104 and the third electrode 105 is constant, the volume percentage of the insulating medium layer 102 can be increased by increasing the thickness of the insulating medium layer 102. When the thickness of the insulating medium layer 102 is greater than or equal to 5 mm, the capacitance of the second detection capacitor and the third detection capacitor can be significantly increased. In addition, when the thickness of the insulating medium layer 102 is greater than or equal to 5 mm, the distance between the second electrode 104 and the diaphragm 2 and the distance between the third electrode 105 and the diaphragm 2 are both greater than 5 mm, thereby ensuring that the capacitance of the second detection capacitor and the third detection capacitor and the pressure are in a linear relationship.

[0068] In summary, the pressure sensor provided by the application has the double-layer structure of the fixed substrate 101 and the insulating medium layer 102, the second electrode 104 and the third electrode 105 are arranged in the same layer between the fixed substrate 101 and the insulating medium layer 102, and the second detection capacitor and the third detection capacitor formed by the second electrode 104 and the third electrode 105 respectively and the dynamic membrane 2 eliminate the interference caused by non-pressure factors, thereby improving the anti-interference ability of the pressure sensor. Meanwhile, the dielectric constant of the composite medium in the second detection capacitor and the third detection capacitor is increased by the insulating medium layer 102, thereby increasing the capacitance of the second detection capacitor and the third detection capacitor, improving the anti-interference ability of the pressure sensor, ensuring that the pressure sensor has high resolution, and meeting the distance requirement between the second electrode 104, the third electrode 105 and the dynamic membrane 2, so that the capacitance and the pressure maintain a linear relationship. In addition, the first electrode 103 is arranged on the side of the insulating medium layer 102 close to the dynamic membrane 2, the area of the first electrode 103 is larger than that of the second electrode 104 and the third electrode 105, and the first detection capacitor has the highest capacitance. When there is no non-pressure factor interference, the pressure of the measured environment is measured by the first detection capacitor, which has higher resolution and further improves the accuracy of the pressure sensor.

[0069] In addition, the application also provides a manufacturing method of a pressure sensor, which is used for manufacturing the pressure sensor in any of the above embodiments, and includes the following steps.

[0070] S1, cleaning the fixed substrate 101 and the insulating medium layer 102;

[0071] The fixed substrate 101 and the insulating medium layer 102 are ultrasonically cleaned before being connected. During the cleaning process, the fixed substrate 101 and the insulating medium layer 102 can be sequentially cleaned by using cleaning liquid with a concentration of 100%, cleaning liquid with a concentration of 40% and pure water, so as to remove oil stains on the surfaces of the fixed substrate 101 and the insulating medium layer 102 and increase the adhesion during the connection. Of course, the cleaning method is not limited to ultrasonic cleaning, and the cleaning liquid concentration and the cleaning times are not limited to this.

[0072] S2, processing the insulating medium layer 102 and the fixed substrate 101 to form the first electrode 103, the second electrode 104 and the third electrode 105;

[0073] Optionally, before the connection, the first electrode 103, the second electrode 104, the third electrode 105, the first electrode connecting part 106, the second electrode connecting part 107 and the third electrode connecting part 108 are arranged on the fixed substrate 101 and the insulating medium layer 102. The fixed substrate 101 and the insulating medium layer 102 can be made into electrodes and electrode connecting parts by a metalization process such as a magnetron sputtering process, a vacuum evaporation process, a screen printing process and the like. The electrodes and the electrode connecting parts can be made of silver, palladium, gold, nickel, molybdenum, manganese and the like. The metalization process has the advantages of good forming effect and strong adhesion, but the arrangement of the electrodes and the electrode connecting parts is not limited to the metalization process.

[0074] Optionally, the upper and lower end faces of the fixed substrate 101 and the insulating medium layer 102 are metalized, and the metalization patterns are arranged according to the shapes of the corresponding electrodes or electrode connecting parts. After the metalization, metal layers corresponding to the patterns are formed. The upper end face of the insulating medium layer 102 and the lower end face of the fixed substrate 101 adopt the same pattern, which includes the patterns of the second electrode 104 and the third electrode 105. When the fixed substrate 101 and the insulating medium layer 102 are connected, the metal layers with the same pattern are overlapped and connected to form the second electrode 104 and the third electrode 105. Figure 4 The pattern of the second electrode 104 and the third electrode 105 shown is a specific embodiment of the pattern, and the pattern of the second electrode 104 and the third electrode 105 is not limited thereto.

[0075] Optionally, the thicknesses of the first electrode 103, the second electrode 104 and the third electrode 105 are greater than or equal to 1 μm and less than or equal to 20 μm.

[0076] S3, bonding and fixing the fixed substrate 101 and the insulating medium layer 102;

[0077] S4, sintering the fixed substrate 101 and the insulating medium layer 102 after the bonding and fixing;

[0078] After the metalization of the fixed substrate 101 and the insulating medium layer 102 is completed, the side of the insulating medium layer 102 away from the diaphragm 2 and the side of the fixed substrate 101 close to the diaphragm 2 can be bonded and fixed by a slurry. The thickness of the bonding slurry is greater than or equal to 2 μm and less than or equal to 7 μm. The fixed substrate 101 and the insulating medium layer 102 after the bonding are sintered together. The sintering temperature is greater than or equal to 250 and less than or equal to 500 ℃.

[0079] S5, installing the diaphragm 2 in the installation cavity, the diaphragm 2 divides the installation cavity to form a reference cavity, and the fixed electrode assembly is installed in the reference cavity;

[0080] S6, extracting the gas in the reference cavity to form a vacuum chamber in the reference cavity;

[0081] S7, after the pumping, the reference cavity is closed.

[0082] After the fixed electrode assembly 1 is manufactured, the moving membrane 2 and the fixed electrode assembly 1 are installed into the shell 3. Then the top cover 4 is welded with the upper seat 301. The top cover 4 is provided with a pumping pipe 404, which connects the reference cavity with the outside of the shell 3. Then a vacuum pump is connected with the pumping pipe 404 to pump the reference cavity, so that the reference cavity forms a vacuum chamber. At the same time, the pressure sensor is heated on the outside, so that the gas adsorbed on the surface of the fixed electrode assembly 1 in the reference cavity is accelerated to be discharged. After the pressure in the reference cavity is reduced to the required range, the pumping pipe 404 is cut off and sealed. The structure of the sealed pumping pipe 404 is shown in Figure 6 The required range of the pressure in the reference cavity can refer to the prior art, which is not described here. After the pumping pipe 404 is sealed, the reference cavity forms a complete and independent vacuum chamber, so that the pressure sensor can measure the absolute pressure.

[0083] In the embodiment, the first electrode 103, the second electrode 104 and the third electrode 105 are processed by a metallization process, which can make the electrodes have the advantages of stronger adhesion, more uniform thickness and better mechanical stress resistance. After the fixed substrate 101 and the insulating medium layer 102 are bonded and fixed, they are sintered to further improve the connection strength of the fixed substrate 101 and the insulating medium layer 102, and then improve the structural strength of the fixed electrode assembly. In addition, during the metallization process, the upper end surface of the insulating medium layer 102 and the lower end surface of the fixed substrate 101 are both metallized to form metal layers corresponding to the second electrode 104 and the third electrode 105. The metal layers of the fixed substrate 101 and the insulating medium layer 102 are correspondingly connected to form the second electrode 104 and the third electrode 105. The fixed substrate 101 and the insulating medium layer 102 are fixed by sintering, which can make the second electrode 104 and the third electrode 105 have lower resistivity and higher strength.

[0084] It can be understood that the above embodiments are only exemplary embodiments adopted to illustrate the principles of the present application, and the present application is not limited thereto. Various modifications and improvements can be made by those skilled in the art without departing from the spirit and essence of the present application, and these modifications and improvements are also regarded as the protection scope of the present application.

Claims

1. A pressure sensor, characterized by The pressure sensor comprises a shell, a diaphragm and a fixed electrode assembly, the shell has a mounting cavity inside, the diaphragm is in sealing connection with the inner side wall of the mounting cavity, the mounting cavity is divided into a detection cavity and a reference cavity, the diaphragm is provided with a movable electrode, the fixed electrode assembly is arranged in the reference cavity, and the fixed electrode assembly comprises a fixed substrate, an insulating medium layer, a first electrode, a second electrode and a third electrode. The insulating medium layer is arranged on the side of the fixed substrate close to the diaphragm. The first electrode is arranged on the side of the insulating medium layer close to the diaphragm and is used for cooperating with the diaphragm to obtain a first detection capacitance; the second electrode and the third electrode are arranged in the same layer and are insulated from each other between the insulating medium layer and the fixed substrate and are respectively used for cooperating with the diaphragm to obtain a second detection capacitance and a third detection capacitance; and the area of the first electrode is greater than the area of the second electrode and the area of the third electrode.

2. The pressure sensor of claim 1, wherein, The pressure sensor further comprises an electrode lead-out structure arranged on the side of the fixed substrate away from the insulating medium layer, the electrode lead-out structure comprises a first electrode connecting part, a second electrode connecting part and a third electrode connecting part. A first via hole, a second via hole and a third via hole each having a conductive layer on the hole wall are arranged on the fixed substrate, and a fourth via hole having a conductive layer on the hole wall is arranged on the insulating medium layer, the fourth via hole is coaxially arranged with the first via hole, and the two are electrically connected through a connecting piece. The first electrode connecting part is electrically connected with the first electrode through the conductive layer in the first via hole and the fourth via hole; the second electrode connecting part is electrically connected with the second electrode through the conductive layer in the second via hole; and the third electrode connecting part is electrically connected with the third electrode through the conductive layer in the third via hole.

3. The pressure sensor of claim 2, wherein, The first electrode is a first circular electrode, the second electrode is a second circular electrode, and the third electrode is a circular ring electrode, wherein the circular ring electrode is arranged to surround the second circular electrode at intervals.

4. The pressure sensor of claim 3, wherein, The axes of the first via hole and the fourth via hole are coincident with the center of the first circular electrode, and a relief hole is arranged at the center position of the second circular electrode for the connecting piece to pass through, and the second circular electrode is insulated from the connecting piece through the relief hole; The orthographic projection of the second via hole on the insulating medium layer is located in the orthographic projection of the second circular electrode on the insulating medium layer and is spaced apart from the relief hole; and the orthographic projection of the third via hole on the insulating medium layer is located in the orthographic projection of the circular ring electrode on the insulating medium layer.

5. The pressure sensor according to any one of claims 1 to 4, characterized in that The dielectric constant of the insulating medium layer is set to be able to increase the capacitance of the second detection capacitance and the third detection capacitance.

6. The pressure sensor of claim 5, wherein, The dielectric constant of the insulating medium layer is greater than or equal to 10.

7. The pressure sensor of claim 5, wherein, The thickness of the insulating medium layer is greater than or equal to 5 mm.

8. The pressure sensor of claim 1, wherein, The thickness of the first electrode, the second electrode and the third electrode is greater than or equal to 1 μm and less than or equal to 20 μm.

9. A method of manufacturing a pressure sensor for manufacturing the pressure sensor according to any one of claims 1 to 8, characterized by, The method comprises: cleaning the fixed substrate and the insulating medium layer; processing the insulating medium layer and the fixed substrate to form the first electrode, the second electrode and the third electrode; adhesively fixing the fixed substrate and the insulating medium layer; sintering the fixed substrate and the insulating medium layer after adhesively fixing; mounting the moving membrane in the mounting cavity, separating the mounting cavity to form the reference cavity and the detection cavity, and mounting the fixed electrode assembly in the reference cavity; extracting gas in the reference cavity to form a vacuum chamber in the reference cavity; after the extraction of gas is completed, sealing the reference cavity.

10. The manufacturing method according to claim 9, wherein The processing the insulating medium layer and the fixed substrate to form the first electrode, the second electrode and the third electrode, comprises: processing the insulating medium layer and the fixed substrate to form the first electrode, the second electrode and the third electrode through a metallization process, the metallization process comprising a magnetron sputtering process, a vacuum evaporation process and a screen printing process.

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