Support substrate, pressure sensor and pressure transmitter

Abstract

The embodiment of the utility model provides a supporting substrate, a pressure sensor and a pressure transmitter, which are used for solving the defect that zero drift often occurs in the use process of the existing pressure sensor. According to the supporting substrate, a supporting substrate body is manufactured by adopting a glass substrate of which the thermal expansion coefficient is matched with that of the monocrystalline silicon diaphragm, and a high-pressure drainage channel is formed in the center of the supporting substrate body; the supporting substrate can be fixedly connected with the monocrystalline silicon diaphragm through a bonding process, and seals the cup-shaped cavity of the monocrystalline silicon diaphragm to form a high-pressure cavity. The thermal expansion coefficient of the glass-based support substrate body is matched with that of the monocrystalline silicon diaphragm, so that the thermal expansion or shrinkage deformation of the glass-based support substrate body and the monocrystalline silicon diaphragm is basically consistent in the bonding and packaging process or the use process of working temperature change, and the generation and accumulation of internal stress are reduced. And furthermore, the technical problem that zero drift often occurs due to internal stress generated by temperature change in the packaging process and the using process of the existing pressure sensor is effectively solved.

Description

Technical Field

[0001] The embodiments of the utility model relate to the technical field of pressure sensor devices, and in particular to a supporting substrate, a pressure sensor and a pressure transmitter. Background Art

[0002] The piezoresistive pressure sensor consists of a single crystal silicon diaphragm, a supporting substrate, and a signal conditioning circuit. Four strain resistors are deposited on the measuring surface of the single crystal silicon diaphragm by micro-electromechanical system (MEMS) micromachining technology, and these four strain resistors form a measuring circuit in a Wheatstone bridge configuration. The measuring surface of the single crystal silicon diaphragm is in contact with the low-pressure cavity, while the high-pressure bearing surface has a cup-shaped high-pressure cavity, which is closed by the supporting substrate. The pressure source to be measured is introduced into the high-pressure cavity through the high-pressure drainage channel on the supporting substrate.

[0003] When the pressure source to be measured is introduced into the high-pressure cavity, there is a pressure difference between the high-pressure cavity and the low-pressure cavity set on both sides of the single-crystal silicon diaphragm. The single-crystal silicon diaphragm is subjected to pressure, and its lattice is deformed, resulting in a change in carrier mobility, thereby causing the resistance value of the strain resistor to change. The measurement circuit outputs the corresponding electrical signal by detecting the change in the resistance value. By analyzing the change in the output electrical signal, the magnitude of the pressure can be inferred, thereby realizing the pressure measurement.

[0004] The sensitivity of piezoresistive pressure sensors is 50 to 100 times that of traditional metal strain gauges, and they have the advantages of fast response speed, small size, and light weight. Therefore, they are widely used in various scenarios that require pressure measurement. In existing designs, the support substrate used to support and fix the single-crystal silicon diaphragm is usually made of silicon, ceramic or metal materials.

[0005] However, in the process of implementing the technical solution in the embodiment of the utility model, the inventors found that the existing pressure sensor has at least the following technical problems:

[0006] During use, pressure sensors often experience zero drift, which has a negative impact on the sensitivity, temperature coefficient and overall stability of the sensor. Utility Model Content

[0007] In view of this, the purpose of the embodiments of the utility model is to provide a supporting substrate, a pressure sensor and a pressure transmitter. The supporting substrate is made of a glass substrate whose thermal expansion coefficient matches that of a single crystal silicon diaphragm, so as to solve the technical problem of zero drift that often occurs in existing pressure sensors during use.

[0008] In order to achieve the above purpose, the technical solutions adopted in the embodiments of the present invention are as follows:

[0009] In a first aspect, the utility model provides a support substrate in an embodiment for supporting and fixing a single crystal silicon diaphragm of a pressure sensor; the support substrate can be fixedly connected to the single crystal silicon diaphragm through a bonding process to seal the cup-shaped chamber of the single crystal silicon diaphragm to form a high-pressure chamber; the support substrate comprises:

[0010] The supporting substrate body is made of a glass substrate having a thermal expansion coefficient matching that of the single crystal silicon diaphragm;

[0011] The high-pressure drainage channel is a through hole opened in the center of the support substrate body, which is used to connect the high-pressure chamber and the measured pressure source, introduce the measured pressure medium into the high-pressure chamber, and form a pressure environment in the high-pressure chamber that is the same as the measured pressure source.

[0012] Optionally, the glass substrate having a thermal expansion coefficient matching that of the single crystal silicon diaphragm is one of a high borosilicate glass substrate and a soda-lime glass substrate.

[0013] Optionally, the support substrate has a thickness of 1 to 10 mm, a warpage of no more than 50 μm, a parallelism of no more than 0.1 mm, and a surface roughness Ra value of no more than 15 nm.

[0014] Optionally, the support substrate has a thickness of 2 to 3 mm, a warpage of no more than 15 μm, a parallelism of no more than 0.1 mm, and a surface roughness Ra value of no more than 5 nm.

[0015] Optionally, the through hole serving as the high-pressure drainage channel is a waist-shaped through hole or a cylindrical through hole.

[0016] Optionally, the through hole serving as the high-pressure drainage channel is a through hole obtained by a laser induced etching process.

[0017] Optionally, the through hole serving as the high-pressure drainage channel has a diameter of not less than 400 μm, a collapse rate of not more than 0.1%, a coaxiality of not more than 10 μm, a roundness of not more than 10 μm, and an inner wall roughness of not more than 3 μm.

[0018] Optionally, the through hole serving as the high-pressure drainage channel has a diameter of not less than 500 μm, a collapse rate of not more than 0.1%, a coaxiality of not more than 3 μm, a roundness of not more than 2 μm, and an inner wall roughness of not more than 1 μm.

[0019] In a second aspect, an embodiment of the utility model further provides a pressure sensor, comprising:

[0020] A single crystal silicon diaphragm; the central portion of the lower portion of the single crystal silicon diaphragm has a concave cup-shaped chamber; four strain resistors are deposited on the upper portion of the single crystal silicon diaphragm by a semiconductor diffusion process, and the four strain resistors are configured into a measurement circuit in the form of a Wheatstone bridge; an electrode contact electrically connected to each strain resistor is arranged on the outer side;

[0021] The aforementioned supporting substrate; the supporting substrate body of the supporting substrate is fixedly connected to the single crystal silicon diaphragm through a bonding process, sealing the cup-shaped chamber of the single crystal silicon diaphragm to form a high-pressure cavity; a high-pressure drainage channel is opened in the central part of the supporting substrate body, which is used to connect the high-pressure cavity and the measured pressure source, introduce the measured pressure medium into the high-pressure cavity, and form a pressure environment in the high-pressure cavity that is the same as that of the measured pressure source.

[0022] In a third aspect, the present invention also provides a pressure transmitter in an embodiment, including:

[0023] The aforementioned pressure sensor is used to convert the detected pressure change into an electrical signal;

[0024] A sensor mounting structure, used for nesting and mounting the pressure sensor;

[0025] The lower housing; the pressure sensor is embedded in the lower housing through the sensor mounting structure and the annular sealing ring; the lower portion of the lower housing has a drainage interface connected to the inner cavity of the lower housing, which is used to introduce the measured pressure medium of the measured pressure source into the inner cavity of the lower housing;

[0026] An upper shell, a sealing sleeve is arranged on the lower shell, and has an ambient atmosphere inlet for introducing ambient atmosphere into the inner cavity of the upper shell;

[0027] A control circuit is arranged in the inner cavity of the upper shell, electrically connected to the four electrode contacts of the pressure sensor, and is used to process the electrical signal collected by the pressure sensor; the control circuit is communicated with an external device or system through an interface terminal, and sends the processed signal to the external device or system.

[0028] Based on the above technical solution, the supporting substrate, pressure sensor and pressure transmitter in the embodiment of the utility model adopt a glass substrate whose thermal expansion coefficient matches that of the single crystal silicon diaphragm to manufacture the supporting substrate body of the supporting substrate; a high-pressure drainage channel is opened in the central part of the supporting substrate body; the supporting substrate can be fixedly connected with the single crystal silicon diaphragm through a bonding process, and the cup-shaped chamber of the single crystal silicon diaphragm is sealed to form a high-pressure cavity. The high-pressure drainage channel is used to connect the high-pressure cavity and the measured pressure source, introduce the measured pressure medium into the high-pressure cavity, and form a pressure environment in the high-pressure cavity that is the same as that of the measured pressure source.

[0029] Since the thermal expansion coefficient of the glass-based supporting substrate body matches the thermal expansion coefficient of the single-crystal silicon diaphragm, the thermal expansion or contraction deformation of the two is basically the same regardless of whether in the bonding packaging process or in the use process when the operating temperature changes, thereby reducing the generation and accumulation of internal stress.

[0030] Compared with silicon-based, ceramic-based or metal-based supporting substrates, the supporting substrate, pressure sensor and pressure transmitter in the embodiments of the utility model greatly reduce the probability of the sensing structure generating and accumulating internal stress, effectively suppress the zero drift phenomenon, and significantly improve the stability and accuracy of the pressure sensor in long-term use.

[0031] Therefore, the supporting substrate, pressure sensor and pressure transmitter in the embodiments of the utility model effectively solve the technical problem that the existing pressure sensors often experience zero drift due to internal stress generated by temperature changes during the packaging process and use, and significantly improve the stability and accuracy of the pressure sensor in the long term, making it suitable for various high-precision pressure measurement scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0033] Figure 1 A schematic structural diagram of a support substrate in an embodiment of the utility model is shown;

[0034] Figure 2 A schematic structural diagram of a pressure sensor in an embodiment of the utility model is shown;

[0035] Figure 3 A schematic circuit element layout diagram of the upper portion of the single crystal silicon diaphragm of the pressure sensor in the embodiment of the utility model is shown;

[0036] Figure 4 A schematic structural diagram of a pressure transmitter in an embodiment of the utility model is shown.

[0037] The corresponding relationship between the reference numerals and component names in the figures is as follows:

[0038] Pressure sensor 100, supporting substrate 110, supporting substrate body 111, high-pressure drainage channel 112, single crystal silicon diaphragm 120, high-pressure cavity 121, strain resistor 122, electrode contact 123, lower shell 200, upper shell 300, sensor mounting structure 400, annular sealing ring 500, control circuit 600. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the embodiment of the utility model clearer, the technical solution in the embodiment of the utility model will be clearly and completely described below in combination with actual application and with reference to the drawings of the embodiment of the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model, not all the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0040] The supporting substrate in the embodiment of the utility model is applied to a pressure sensor, which can be applied to an instrument or device for accurately measuring liquid or high-pressure gas, such as a pressure transmitter.

[0041] Existing pressure sensors often experience zero-point drift during use, which seriously affects the stability and accuracy of the sensors in long-term use.

[0042] After in-depth research, the inventors found that the reason why existing pressure sensors often experience zero-point drift during use is not entirely due to zero-point temperature drift caused by changes in the physical properties of the single-crystal silicon diaphragm due to changes in the operating temperature. Temperature drift can be eliminated by adding a temperature compensation circuit, but zero-point drift will still occur after adding a temperature compensation circuit.

[0043] The inventors further discovered that the reasons for the zero drift phenomenon also include: In the prior art, the supporting substrate is usually made of silicon, ceramic or metal materials. There is a significant difference in the thermal expansion coefficient of these materials and the single crystal silicon diaphragm. The pressure sensor composed of the supporting substrate and the single crystal silicon diaphragm will generate internal stress at the joint, whether in the bonding packaging process or in the use process when the working temperature changes. This internal stress causes the single crystal silicon diaphragm to produce non-pressure deformation, the measurement shape is destroyed, and thus causes the zero drift of the pressure sensor.

[0044] In order to solve this technical problem, the inventor found in the process of realizing the technical solution in the embodiment of the utility model that if a material matching the thermal expansion coefficient of the single crystal silicon diaphragm can be selected to make the supporting substrate, then whether in the bonding packaging process or in the use process of the working temperature change, the thermal expansion or contraction deformation of the two is basically the same, the probability of internal stress generation and accumulation is very low, and the single crystal silicon diaphragm can always maintain a good measurement shape, thereby effectively suppressing the zero drift phenomenon. After many comparisons and analyses of material properties, the inventor found that the thermal expansion coefficient of glass material is very close to that of single crystal silicon; and after many engineering experiments, it was verified that the supporting substrate made of high borosilicate glass and soda-lime glass selected from the glass material and the pressure sensor composed of the single crystal silicon diaphragm have a very low probability of zero drift.

[0045] Based on the above understanding, the inventor provides a new type of support substrate, pressure sensor and pressure transmitter. The support substrate is made of a glass substrate with a thermal expansion coefficient matching that of a single crystal silicon diaphragm, and a high-pressure drainage channel corresponding to the cup-shaped cavity of the single crystal silicon diaphragm is opened in the center of the support substrate body.

[0046] The technical solution of the utility model will be described below in conjunction with the accompanying drawings and embodiments.

[0047] Figure 1 A schematic structural diagram of a support substrate in an embodiment of the utility model is shown.

[0048] Now refer to Figure 1 As shown, in the embodiment of the utility model, a support substrate is provided for supporting and fixing the single crystal silicon diaphragm of the pressure sensor; the support substrate 110 can be fixedly connected with the single crystal silicon diaphragm through a bonding process, and the cup-shaped chamber of the single crystal silicon diaphragm is sealed to form a high pressure chamber; the support substrate 110 includes:

[0049] The supporting substrate body 111 is made of a glass substrate having a thermal expansion coefficient matching that of the single crystal silicon diaphragm;

[0050] The high-pressure drainage channel 112 is a through hole opened in the center of the support substrate body 111, which is used to connect the high-pressure chamber and the measured pressure source, introduce the measured pressure medium into the high-pressure chamber, and form the same pressure environment as the measured pressure source in the high-pressure chamber.

[0051] In the embodiment of the utility model, the support substrate body 111 is used to support and fix the single crystal silicon diaphragm of the pressure sensor, ensuring that the deformation of the single crystal silicon diaphragm can accurately reflect the pressure. The shape and size of the support substrate body 111 are adapted to the single crystal silicon diaphragm. The support substrate 110 includes a support substrate body 111 and a through hole opened in the center of the support substrate body 111. The through hole is used as a high-pressure drainage channel 112.

[0052] The supporting substrate body 111 is made of a glass substrate whose thermal expansion coefficient matches that of the single crystal silicon diaphragm. In a possible implementation, the glass substrate whose thermal expansion coefficient matches that of the single crystal silicon diaphragm is a high borosilicate glass substrate or a soda-lime glass substrate.

[0053] The thermal expansion coefficient of the single crystal silicon diaphragm is 2.62-8.4×10-6 / °C, the thermal expansion coefficient of the high borosilicate glass substrate is 2.60-4.0×10-6 / °C, and the thermal expansion coefficient of the soda-lime glass substrate is 8.6-9×10-6 / °C. The thermal expansion coefficients of the three are in the same order of magnitude. That is, the high borosilicate glass substrate and the soda-lime glass substrate match the thermal expansion coefficient of the single crystal silicon diaphragm. Therefore, if the support substrate 110 is made of a high borosilicate glass substrate or a soda-lime glass substrate, and the support substrate 110 and the single crystal silicon diaphragm are used to form a pressure sensor, then the pressure sensor is formed. During the bonding packaging and use process, no matter how the working temperature changes, the thermal expansion or contraction deformation of the single crystal silicon diaphragm and the support substrate 110 is basically the same, which effectively reduces the generation and accumulation of internal stress. The single crystal silicon diaphragm can maintain a good measurement shape for a long time, and the zero drift phenomenon is greatly reduced, which significantly improves the stability and reliability of the pressure sensor in long-term use.

[0054] Among the high borosilicate glass substrate and the soda-lime glass substrate, the high borosilicate glass substrate is the glass substrate whose thermal expansion coefficient is closest to that of the single crystal silicon diaphragm. Therefore, the glass substrate whose thermal expansion coefficient matches that of the single crystal silicon diaphragm is preferably the high borosilicate glass substrate.

[0055] In order to ensure that the supporting substrate matches the single crystal silicon diaphragm in structural morphology, in a possible implementation, the supporting substrate 110 has a thickness of 1 to 10 mm, a warpage of no more than 50 μm, a parallelism of no more than 0.1 mm, and a surface roughness Ra value of no more than 15 nm.

[0056] Specifically, in the process of using a glass substrate with a thermal expansion coefficient matching that of the single crystal silicon diaphragm to manufacture the support substrate 110, precision grinding and polishing can be used to control the thickness of the support substrate 110 to 1-10 mm, the warpage to no more than 50 μm, the parallelism to no more than 0.1 mm, and the surface roughness Ra value to no more than 15 nm. Laser interferometry can be used to inspect the processing quality.

[0057] Controlling the thickness of the support substrate 110 to 1 to 10 mm can reduce the heat capacity of the material and improve the response speed of the pressure sensor. Controlling the warpage of the support substrate 110 to no more than 50 μm and the parallelism to no more than 0.1 mm can ensure the flatness of the support substrate 110, match the flatness of the support substrate 110 with the flatness of the single crystal silicon diaphragm, reduce the probability of generating and accumulating internal stress during the bonding and packaging process, and reduce the probability of structural defects in the pressure sensor formed by the bonding and packaging. In the structure of the pressure sensor, the support substrate 110 and the single crystal silicon diaphragm are also in an aligned state. The surface roughness Ra value of the support substrate 110 is controlled to be no more than 15 nm to optimize the contact surface between the support substrate 110 and the single crystal silicon diaphragm and improve the bonding strength and airtightness.

[0058] In the embodiment of the utility model, by controlling the thickness, warpage, parallelism, and surface roughness Ra value of the support substrate 110, the bonding interface with the single crystal silicon diaphragm can be matched and flush as much as possible. On the one hand, during the bonding and packaging process of the support substrate 110 and the single crystal silicon diaphragm, the probability of structural defects can be reduced, the bonding quality can be improved, and the generation and accumulation of internal stress can be reduced. On the other hand, in the pressure sensor formed by bonding and packaging, the support substrate 110 and the single crystal silicon diaphragm are also in an aligned state, that is, when the operating temperature of the pressure sensor changes during use, the thermal expansion or contraction deformation of the support substrate 110 and the single crystal silicon diaphragm is basically the same, thereby avoiding the generation and accumulation of internal stress caused by temperature changes. This will further reduce the possibility of zero drift due to internal stress and significantly improve the stability and reliability of the pressure sensor in long-term use.

[0059] It has been verified by practical application that if process conditions permit, the thickness of the supporting substrate 110 is controlled within 2 to 3 mm, the warpage is controlled within 15 μm, the parallelism is controlled within 0.01 mm, and the surface roughness Ra value is controlled within 5 nm. This can make the pressure sensor composed of the supporting substrate 110 have better stability and reliability and can be applied to higher-precision pressure measurement scenarios.

[0060] In the embodiment of the utility model, the through hole provided in the center of the support substrate body 111 is used as the high-pressure drainage channel 112, which is used to connect the high-pressure chamber and the pressure source to be measured, introduce the pressure medium to be measured into the high-pressure chamber, and form the same pressure environment as the pressure source to be measured in the high-pressure chamber. The design and production of the high-pressure drainage channel 112 need to take into account the principles of fluid dynamics to ensure that the pressure medium can quickly and evenly enter the high-pressure chamber, and form the same pressure environment as the pressure source to be measured in the high-pressure chamber.

[0061] In order to ensure that the high-pressure drainage channel 112 has good drainage quality and efficiency, in a possible implementation manner, the through hole serving as the high-pressure drainage channel 112 is one of a waist-shaped through hole and a cylindrical through hole.

[0062] Among the waist-shaped through holes and cylindrical through holes, the cylindrical through holes have lower drainage resistance and unlimited flow characteristics, which are beneficial to quickly introduce the measured pressure medium into the high-pressure chamber, and quickly form a pressure environment with the same pressure source as the measured pressure source in the high-pressure chamber, which is beneficial to improving the response speed and measurement accuracy of the pressure sensor.

[0063] In order to ensure that the through hole serving as the high-pressure drainage channel 112 has the shape and size required for efficient drainage, in a possible implementation manner, the through hole serving as the high-pressure drainage channel 112 is a through hole obtained by a laser induced etching process.

[0064] Specifically, firstly, a laser device is used to irradiate the hole-forming area of ​​the glass substrate from top to bottom to form a modified area of ​​the through-hole pattern on the glass substrate;

[0065] The glass substrate with the modified through-hole region is placed in an etching tank of an etching device, and is etched for a predetermined time using an etching solution to form a through-hole that passes through the glass substrate from top to bottom, thereby obtaining the support substrate 110 .

[0066] After the laser induced etching is completed, the support substrate 110 is usually cleaned to remove impurities or residual etching liquid attached to the surface.

[0067] In the embodiment of the utility model, the through-holes made by non-contact laser-induced etching process are used as the high-pressure drainage channel 112. On the one hand, micron-level processing accuracy can be achieved to ensure that the made through-holes meet the design requirements, so that the pressure environment with the same pressure source as the measured pressure source can be quickly formed in the high-pressure cavity through the high-pressure drainage channel 112, ensuring that the pressure sensor composed of the support substrate 110 has good measurement accuracy and response speed. On the other hand, the internal stress formed in the support substrate 110 during the processing can be reduced, and the deviation of the single crystal silicon diaphragm from the measurement shape caused by the deformation of the support substrate 110 can be reduced, and the probability of zero drift can be reduced.

[0068] In order to ensure that the shape of the through hole serving as the high-pressure drainage channel 112 can meet the needs of efficient drainage, in a possible implementation manner, the through hole diameter of the through hole serving as the high-pressure drainage channel 112 is not less than 400 μm, the edge collapse rate is not greater than 0.1%, the coaxiality is not greater than 10 μm, the roundness is not greater than 10 μm, and the inner wall roughness is not greater than 3 μm.

[0069] Specifically, in the process of forming the modified area by laser scanning irradiation of the laser induced etching process and in the process of forming the through-holes by chemical etching, the process parameters are precisely controlled to control the diameter of the through-holes to be no less than 400 μm, the edge collapse rate to be no more than 0.1%, the coaxiality to be no more than 10 μm, the roundness to be no more than 10 μm, and the inner wall roughness to be no more than 3 μm.

[0070] The diameter of the through hole is controlled to be no less than 400 μm, so that the high-pressure drainage channel 112 can provide sufficient flow space and improve the flow efficiency of the measured pressure medium; the edge collapse rate of the through hole is controlled to be no more than 0.1% to ensure the integrity and consistency of the through hole and avoid irregularities in the flow of the measured pressure medium. The axiality of the through hole is controlled to be no more than 10 μm to ensure the straightness between the high-pressure drainage channel 112 and the high-pressure chamber and improve the efficiency of pressure transmission between the measured pressure source and the high-pressure chamber. The roundness of the through hole is controlled to be no more than 10 μm to ensure that the flow of the measured pressure medium in the through hole is more uniform; the inner wall roughness of the through hole is controlled to be no more than 3 μm to reduce the friction between the measured pressure medium and the inner wall and improve the smoothness of the flow of the measured pressure medium.

[0071] In the embodiment of the utility model, by controlling the diameter, edge collapse rate, coaxiality, roundness and inner wall roughness of the through hole serving as the high-pressure drainage channel 112, it is ensured that the high-pressure drainage channel 112 has a larger flow space and smaller fluid resistance, which is beneficial to quickly form a pressure environment in the high-pressure chamber that is the same as the pressure source being measured, thereby significantly improving the response speed and measurement accuracy of the pressure sensor.

[0072] It has been verified by practical application that if process conditions permit, the diameter of the through hole serving as the high-pressure drainage channel 112 is controlled to be no less than 500 μm, the through hole edge collapse rate is controlled to be no more than 0.1%, the through hole coaxiality is controlled to be no more than 3 μm, the through hole roundness is controlled to be no more than 2 μm, and the through hole inner wall roughness is controlled to be no more than 1 μm. The drainage channel can be used to more quickly form a pressure environment identical to that of the pressure source being measured in the high-pressure chamber.

[0073] In the embodiment of the utility model, the support substrate 110 can be fixedly connected to the single crystal silicon diaphragm through a bonding process, ensuring good connection strength between the support substrate 110 and the single crystal silicon diaphragm, and ensuring that the formed high-pressure cavity has good airtightness.

[0074] The supporting substrate 110 in the embodiment of the utility model is made of a glass substrate whose thermal expansion coefficient matches that of the single crystal silicon diaphragm to form the supporting substrate body 111, so that the pressure sensor composed of the single crystal silicon diaphragm and the supporting substrate 110 has basically the same thermal expansion or contraction deformation as that of the single crystal silicon diaphragm and the supporting substrate 110, regardless of whether in the bonding and packaging process or in the use process with changing working temperature, thereby significantly reducing the generation and accumulation of internal stress and allowing the single crystal silicon diaphragm to maintain a good measurement shape for a long time.

[0075] Before the pressure measuring medium is introduced into the high pressure cavity, there is no pressure difference between the high pressure cavity and the low pressure cavity arranged on both sides of the single crystal silicon diaphragm, and the sensor is in a zero point state due to the absence of internal stress.

[0076] When the pressure sensor is working, the pressure measuring medium is introduced into the high-pressure chamber in the form of medium flow through the high-pressure drainage channel 112, and a pressure environment identical to that of the pressure source to be measured is formed in the high-pressure chamber. There is a pressure difference between the high-pressure chamber and the low-pressure chamber arranged on both sides of the single-crystal silicon diaphragm, and the single-crystal silicon diaphragm is subjected to pressure and slightly deformed. The deformation of the single-crystal silicon diaphragm causes the resistance value of the strain resistor deposited thereon to change, and the output electrical signal of the Wheatstone bridge composed of the strain resistor changes. The magnitude of the pressure can be inferred by measuring the change in the output electrical signal.

[0077] During the operation of the pressure sensor, the thermal expansion or contraction deformation of the supporting substrate 110 and the single crystal silicon diaphragm caused by temperature changes is basically the same, no internal stress is generated and accumulated, and the single crystal silicon diaphragm maintains a good measurement shape for a long time, and then the size of the pressure is calculated to accurately reflect the actual force size, thereby achieving accurate measurement of pressure.

[0078] Through this working mechanism, the supporting substrate 110 in the embodiment of the utility model can not only provide effective support and fixation for the single crystal silicon diaphragm, but also basically maintain consistency with the thermal expansion or contraction deformation of the single crystal silicon diaphragm, thereby reducing the probability of internal stress generation and accumulation. Furthermore, the pressure sensor composed of the supporting substrate 110 and the single crystal silicon diaphragm will basically not have zero point drift caused by internal stress during use, thereby improving the stability and reliability of the pressure sensor in long-term use.

[0079] Compared with silicon-based, ceramic-based or metal-based supporting substrates, the supporting substrate, pressure sensor and pressure transmitter in the embodiments of the utility model greatly reduce the probability of the sensing structure generating and accumulating internal stress, effectively suppress the zero drift phenomenon, and significantly improve the stability and accuracy of the pressure sensor in long-term use.

[0080] Therefore, the supporting substrate, pressure sensor and pressure transmitter in the embodiments of the utility model effectively solve the technical problem that the existing pressure sensors often experience zero drift due to internal stress generated by temperature changes during the packaging process and use, and significantly improve the stability and accuracy of the pressure sensor in the long term, making it suitable for various high-precision pressure measurement scenarios.

[0081] Figure 2 A schematic structural diagram of a pressure sensor in an embodiment of the utility model is shown.

[0082] Figure 3 A schematic circuit element layout diagram of the upper portion of the single crystal silicon diaphragm of the pressure sensor in the embodiment of the utility model is shown.

[0083] Now refer to Figure 2 , while combining Figure 3 As shown, the embodiment of the utility model further provides a pressure sensor, including:

[0084] A single crystal silicon diaphragm 120; the central portion of the lower portion of the single crystal silicon diaphragm 120 has a concave cup-shaped chamber; four strain resistors 122 are deposited on the upper portion of the single crystal silicon diaphragm 120 by a semiconductor diffusion process, and the four strain resistors 122 are configured into a measurement circuit in the form of a Wheatstone bridge; an electrode contact 123 electrically connected to each strain resistor 122 is provided on the outer side of each strain resistor 122;

[0085] The aforementioned supporting substrate 110; the supporting substrate body 111 of the supporting substrate is fixedly connected to the single crystal silicon diaphragm 120 through a bonding process, sealing the cup-shaped chamber of the single crystal silicon diaphragm 120 to form a high-pressure chamber 121; a high-pressure drainage channel 112 is opened at the center of the supporting substrate body 111, which is used to connect the high-pressure chamber 121 and the measured pressure source, introduce the measured pressure medium into the high-pressure chamber 121, and form a pressure environment in the high-pressure chamber 121 that is the same as that of the measured pressure source.

[0086] The pressure sensor in the embodiment of the utility model can be applied to instruments or devices for precise measurement of liquids and high-pressure gases, such as pressure transmitters.

[0087] It should be understood that the support substrate in the folding screen embodiment of the utility model is the support substrate in the aforementioned support substrate embodiment of the utility model. For the convenience and simplicity of description, the description of the support substrate in the pressure sensor embodiment of the utility model can refer to the relevant description in the support substrate embodiment, and will not be repeated here.

[0088] Figure 4 A schematic structural diagram of a pressure transmitter in an embodiment of the utility model is shown.

[0089] Now refer to Figure 4 As shown, the embodiment of the utility model also provides a pressure transmitter, including:

[0090] The aforementioned pressure sensor 100 is used to convert the detected pressure change into an electrical signal;

[0091] A sensor mounting structure 400, used for nesting and mounting the pressure sensor 100;

[0092] The lower housing 200; the pressure sensor 100 is embedded in the lower housing 200 through the sensor mounting structure 400 and the annular sealing ring 500; the lower part of the lower housing 200 has a drainage interface connected to the inner cavity of the lower housing, which is used to introduce the measured pressure medium of the measured pressure source into the inner cavity of the lower housing;

[0093] The upper shell 300, the sealing sleeve is arranged on the lower shell 200, and has an ambient atmosphere inlet for introducing the ambient atmosphere into the inner cavity of the upper shell;

[0094] The control circuit 600 is arranged in the inner cavity of the upper shell and is electrically connected to the four electrode contacts of the pressure sensor 100, and is used to process the electrical signal collected by the pressure sensor 100; the control circuit 600 is communicated with the external device or system through the interface terminal, and sends the processed signal to the external device or system.

[0095] The pressure transmitter in the embodiment of the utility model is used for precise measurement of liquid and high-pressure gas.

[0096] It should be understood that the pressure sensor in the folding screen embodiment of the utility model is the pressure sensor in the aforementioned pressure sensor embodiment of the utility model. For the convenience and simplicity of description, the description of the pressure sensor in the pressure transmitter embodiment of the utility model can refer to the relevant description in the pressure sensor embodiment, and will not be repeated here.

Claims

1. A support substrate, used for supporting and fixing a single crystal silicon diaphragm of a pressure sensor; the support substrate (110) can be fixedly connected to the single crystal silicon diaphragm through a bonding process, sealing the cup-shaped chamber of the single crystal silicon diaphragm to form a high-pressure chamber; characterized in that: The support substrate (110) comprises: A supporting substrate body (111) is made of a glass substrate having a thermal expansion coefficient matching that of the single crystal silicon diaphragm; The high-pressure drainage channel (112) is a through hole provided in the center of the support substrate body (111), and is used to connect the high-pressure chamber and the pressure source to be measured, and to introduce the pressure medium to be measured into the high-pressure chamber, thereby forming a pressure environment in the high-pressure chamber that is the same as that of the pressure source to be measured.

2. The support substrate according to claim 1, characterized in that: The glass substrate whose thermal expansion coefficient matches that of the single crystal silicon diaphragm is one of a high borosilicate glass substrate and a soda-lime glass substrate.

3. The support substrate according to claim 1, characterized in that: The support substrate (110) has a thickness of 1 to 10 mm, a warpage of no more than 50 μm, a parallelism of no more than 0.1 mm, and a surface roughness Ra value of no more than 15 nm.

4. The support substrate according to claim 3, characterized in that: The support substrate (110) has a thickness of 2 to 3 mm, a warpage of no more than 15 μm, a parallelism of no more than 0.1 mm, and a surface roughness Ra value of no more than 5 nm.

5. The support substrate according to any one of claims 1 to 4, characterized in that: The through hole serving as the high-pressure drainage channel (112) is one of a waist-shaped through hole and a cylindrical through hole.

6. The support substrate according to any one of claims 1 to 4, characterized in that: The through hole serving as the high-pressure drainage channel (112) is a through hole obtained by a laser induced etching process.

7. The support substrate according to claim 6, characterized in that: Optionally, the through hole serving as the high-pressure drainage channel (112) has a diameter of not less than 400 μm, a collapse rate of not more than 0.1%, a coaxiality of not more than 10 μm, a roundness of not more than 10 μm, and an inner wall roughness of not more than 3 μm.

8. The support substrate according to claim 7, characterized in that: The through hole serving as the high-pressure drainage channel (112) has a diameter of not less than 500 μm, a collapse rate of not more than 0.1%, a coaxiality of not more than 3 μm, a roundness of not more than 2 μm, and an inner wall roughness of not more than 1 μm.

9. A pressure sensor, characterized in that include; A single crystal silicon diaphragm (120); the central portion of the lower portion of the single crystal silicon diaphragm (120) has a concave cup-shaped chamber; four strain resistors (122) are deposited on the upper portion of the single crystal silicon diaphragm (120) by a semiconductor diffusion process, and the four strain resistors (122) are configured into a measurement circuit in the form of a Wheatstone bridge; an electrode contact (123) electrically connected to each strain resistor (122) is arranged on the outer side of each strain resistor (122); The support substrate (110) as described in any one of claims 1 to 8; the support substrate body (111) of the support substrate is fixedly connected to the single crystal silicon diaphragm (120) through a bonding process, sealing the cup-shaped chamber of the single crystal silicon diaphragm (120) to form a high-pressure chamber (121); a high-pressure drainage channel (112) is opened in the central part of the support substrate body (111), which is used to connect the high-pressure chamber (121) and the measured pressure source, introduce the measured pressure medium into the high-pressure chamber (121), and form a pressure environment in the high-pressure chamber (121) that is the same as that of the measured pressure source.

10. A pressure transmitter, characterized in that: include: The pressure sensor (100) of claim 9, configured to convert a detected pressure change into an electrical signal; A sensor mounting structure (400) for nested mounting of the pressure sensor (100); A lower shell (200); the pressure sensor (100) is embedded in the lower shell (200) through the sensor mounting structure (400) and the annular sealing ring (500); the lower part of the lower shell (200) has a drainage interface connected to the inner cavity of the lower shell, which is used to introduce the measured pressure medium of the measured pressure source into the inner cavity of the lower shell; An upper shell (300), a sealing sleeve arranged on the lower shell (200), having an ambient atmosphere inlet for introducing ambient atmosphere into the inner cavity of the upper shell; A control circuit (600) is arranged in the inner cavity of the upper shell, electrically connected to the four electrode contacts of the pressure sensor (100), and is used to process the electrical signal collected by the pressure sensor (100); the control circuit (600) is communicatively connected with an external device or system through an interface terminal, and sends the processed signal to the external device or system.

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