Method for processing gas mass flow sensor

Abstract

The invention discloses a gas mass flow sensor processing method. The method comprises the following steps: providing a bottom plate; manufacturing a detection chip on the top surface of the bottom plate; grooves are machined in the bottom face of the bottom plate and the surface of the cover plate and oppositely installed to form a first heat insulation cavity, and a first heat insulation structure is formed after sealing. A gas flow channel and a second heat insulation cavity are formed in the cover body; a cover body is installed on the top face of the bottom plate, and sealing plates are installed at the two ends of the second heat insulation cavity and sealed to construct a second heat insulation structure; when the cover body is mounted, the airflow channel is ensured to cover the detection chip to construct a detection unit; and manufacturing a cleaning chip to construct the sensor autonomous cleaning system. The process replaces a traditional silicon nitride heat insulation process and a titanium / platinum mixed transition film process, so that the components of the resistive film are changed into pure platinum elementary substances, and the problems of poor consistency and repeatability and the like of important physical parameters such as temperature coefficient and resistivity of the resistive film due to the existence of mixed components in a film layer material are solved; and the detection precision and stability of the sensor are improved.

Description

Technical Field

[0001] The invention relates to the utilization of gas flow detection technology, and in particular to a method for processing a gas mass flow sensor. Background Art

[0002] The advancement of the "smart energy network" project first requires the realization of intelligent metering of energy such as water, electricity and gas, and the establishment of a smart energy network. The intelligent metering of gas requires the development of smart gas flow metering sensors that are compatible with the Internet of Things.

[0003] The MEMS sensor based on the thermal temperature difference principle detects the gas flow rate by using the principle that the gas flow absorbs heat when passing through the heating resistor, thereby causing the thermal temperature difference. Since the amount of heat absorbed by the gas is directly causally related to its own specific heat capacity (CH4 content) and mass, it detects the mass flow of methane gas, and thus can more accurately reflect the amount of methane actually consumed by the user than the traditional volume flow detection method, and will not be affected by the volume expansion, pressure changes, different methane content in different gas fields and other factors that affect the accuracy of gas metering. Moreover, the gas mass flow sensor based on this principle can be compatible with MEMS technology, making it have the advantages of small size, light weight, low power consumption, compatibility with the Internet of Things, and easy integration. Therefore, once it was proposed, it was considered by the gas industry to be an ideal detection solution to solve the accurate measurement of gas and avoid measurement contradictions.

[0004] However, the development of a new type of sensor requires a set of corresponding processing and manufacturing methods. A reasonably designed manufacturing process is the basis for ensuring the detection function of the MEMS sensor. At the same time, the processing method also directly affects the processing cost and detection accuracy of the sensor. In order to reduce the heat transfer of the sensor substrate (reducing the heat transfer of the substrate has an important impact on the detection accuracy of the sensor), the traditional processing technology usually coats a layer of silicon nitride film with good thermal insulation on the surface of the substrate. However, after the introduction of the silicon nitride film layer, due to the poor bonding between the platinum resistor film (the detection element of the sensor) and the silicon nitride film, in order to solve the problem of weak bonding, a titanium film is usually plated between the silicon nitride film and the platinum resistor film. However, the introduction of the titanium film makes the originally pure platinum resistor actually become a platinum / titanium mixture. The mixture will cause the resistivity and temperature coefficient of the platinum resistor to become complicated, because the temperature coefficient and resistivity of the mixture will be different due to its different components, and even the different penetration positions of the two components when mixed will also lead to different temperature coefficients. For example, the temperature coefficient when the titanium layer and the platinum layer are clearly defined is different from the temperature coefficient when the two layers penetrate each other. It is difficult to ensure that the components and penetration positions of resistor films processed in different batches are the same each time, which leads to low repeatability and consistency of the temperature coefficient and resistivity of the resistor. The sensor uses the linear functional relationship between the resistance value and temperature of the temperature measuring element platinum resistor film to detect thermal temperature difference, and the functional relationship between the resistance value and temperature is determined by the temperature coefficient and resistivity of the platinum resistor film. Therefore, the repeatability and consistency of these two physical parameters are crucial to the performance of the sensor, especially the temperature coefficient has a greater impact. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides a processing method for a gas mass flow sensor, which replaces the traditional silicon nitride insulation process and the titanium / platinum mixed transition film layer process, so that the component of the resistor film is changed into a pure platinum single-element material, thereby solving the problems of poor consistency and repeatability of important physical parameters such as the temperature coefficient and resistivity of the chip resistor film due to the presence of mixed components in the film layer material, thereby improving the accuracy and stability of sensor detection.

[0006] In order to achieve the above object, the present invention is implemented by the following technical solution: a gas mass flow sensor processing method, comprising:

[0007] Provide a base plate;

[0008] Processing and manufacturing a detection element and a heating element on the top surface of the bottom plate to construct a detection chip, wherein the detection element is manufactured at the upstream and downstream of the heating element and at the gas inlet end;

[0009] Providing a cover plate, and processing a groove structure on the bottom surface of the base plate and one side surface of the cover plate, then installing the groove structure of the base plate and the groove structure of the cover plate relative to each other to form a first heat insulation cavity, and then sealing to construct a first heat isolation structure;

[0010] Providing a cover body blank, and processing and manufacturing a gas main flow channel and a gas auxiliary flow channel on the cover body blank to construct a gas flow channel, and manufacturing a second heat insulation cavity to complete the manufacture of the cover body;

[0011] The cover is installed on the top surface of the bottom plate, and then the sealing plates are installed on both ends of the second heat insulation cavity and sealed to construct a second heat isolation structure; when installing the cover, ensure that the gas flow channel covers the detection chip to construct a detection unit;

[0012] Providing a cleaning chip substrate, and processing and manufacturing a cleaning chip on the cleaning chip substrate; and

[0013] The cleaning chip is mounted on the surface of the cover plate facing away from the base plate to construct a sensor dirt autonomous cleaning system consisting of the cleaning chip, the main gas channel and the auxiliary gas channel.

[0014] Furthermore, the processing method of the detection chip and the first thermal insulation cavity is:

[0015] Provide and clean the baseboard for use;

[0016] Plating a polyimide film on the top surface of the bottom plate to form a first polyimide film layer;

[0017] uniformly coating a first photoresist film layer on the first polyimide film layer;

[0018] Manufacturing a detection chip resistance film layer on the base plate by exposure, development, sputtering, and stripping processes;

[0019] Processing and manufacturing a first electrical lead film and a first terminal on the surface of the first polyimide film layer;

[0020] Alloying the detection chip having the detection element resistance film, the heating element resistance film, the electric lead film and the terminal;

[0021] A second polyimide film layer is formed on the surface of the detection chip to cover the detection element resistance film, the heating element resistance film and the area where the first electric lead film is located;

[0022] Processing a groove structure on the bottom surface of the bottom plate;

[0023] Provide and clean the cover blank for use;

[0024] Processing a groove structure on the surface of the cover plate blank;

[0025] The groove structure of the bottom plate and the groove structure of the cover plate are relatively installed to form the first heat insulation cavity, and then sealed to form the first thermal isolation structure.

[0026] Furthermore, the gas mass flow sensor processing method provides a surface activation treatment process before coating the surface of the base plate; after completing the processing of the groove of the base plate and the groove of the cover plate, a finishing process is also provided for grinding and polishing the sealing parts in the groove structure of the base plate and the groove of the cover plate.

[0027] Furthermore, in the gas mass flow sensor processing method, when processing and manufacturing the detection chip on the top surface of the base plate, a process is set up to manufacture two groups of detection elements and heating elements spaced apart from each other on the detection chip, so that each group of the detection elements is manufactured upstream and downstream of each group of the heating elements and at the gas inlet end of each group of the gas flow channels.

[0028] Furthermore, the process for processing and manufacturing the gas flow channel and the second heat insulation cavity on the cover body is:

[0029] Provide cover blanks, clean and dry them;

[0030] Prepare wet etching solution for later use;

[0031] A protective layer is applied to the places where etching is not required, and the gas main flow channel, the gas auxiliary flow channel and the second insulation cavity are etched on the cover blank with a prepared wet etching liquid.

[0032] Furthermore, in the gas mass flow sensor processing method, when processing and manufacturing the gas flow channel on the cover body blank, a finishing process of grinding and polishing the flow channel wall surfaces of the gas main flow channel and the auxiliary flow channel is also provided.

[0033] Furthermore, in the gas mass flow sensor processing method, when processing and manufacturing the gas flow channel on the cover body blank, a processing technology for processing and manufacturing two groups of the gas flow channels on the cover body is set. When the cover body is installed, the two groups of the gas flow channels respectively cover two groups of detection elements and heating elements, so that two groups of detection units can be constructed, one group of the detection units can be used for small gas flow detection, and the other group of detection units can be used for large gas flow detection.

[0034] Furthermore, in the gas mass flow sensor processing method, when processing the cover body, a process for processing and manufacturing a second insulation cavity between the two groups of the gas flow channels is also provided. After the two groups of the gas flow channels and the second insulation cavity are processed and manufactured, the cover body including the second insulation cavity is installed on the top surface of the base plate, and the sealing plates are installed on both ends of the second insulation cavity and sealed to construct a second thermal isolation structure.

[0035] Furthermore, in the gas mass flow sensor processing method, when processing and manufacturing the second thermal insulation cavity on the cover body blank, a process of grinding and polishing the sealing part of the inner wall of the second thermal insulation cavity is also provided to ensure the sealing of the second thermal isolation structure and enhance the thermal insulation effect.

[0036] Furthermore, the processing method of the cleaning chip is:

[0037] Providing a cleaning chip substrate for making a cleaning chip, and performing activation treatment on the surface to be coated of the cleaning chip substrate;

[0038] Evenly coating a second photoresist film layer on the surface to be coated of the clean chip substrate;

[0039] The clean electrode is manufactured by combining exposure, development, magnetron sputtering and stripping processes;

[0040] forming a second electrical lead film and a second terminal on the clean chip substrate;

[0041] After the clean electrode, the second electrical lead film and the second terminal have been manufactured, alloying treatment is performed;

[0042] After the alloying treatment, a third polyimide insulating layer is formed on the clean chip substrate to cover the clean electrode and the second electrical lead film to complete the manufacture of the clean chip;

[0043] A cleaning chip is mounted on the surface of the cover plate facing away from the base plate to construct an autonomous sensor contamination cleaning system consisting of the cleaning chip, the main gas channel and the auxiliary gas channel.

[0044] Beneficial effects of the present invention:

[0045] Since the present invention discloses a "solid-vacuum / gas-solid" coupled insulation structure and its processing and manufacturing process, a new insulation method is formed, which replaces the traditional insulation process scheme for processing and manufacturing silicon nitride film, and achieves a better insulation effect; and since the present invention proposes a processing technology for manufacturing a polyimide film on the surface of a silicon substrate and manufacturing a chip resistor film after surface activation treatment, it replaces the traditional processing technology for manufacturing a titanium / platinum mixed film layer to solve the problem of weak adhesion between the platinum film and the silicon nitride film, so that the component of the resistor film is changed to pure platinum single material, and the consistency and repeatability problems of important physical parameters such as the temperature coefficient and resistivity of the chip resistor film material are solved, which not only improves the detection accuracy and stability of the sensor, but also because polyimide has excellent electrical insulation performance, shielding performance and anti-interference performance, this process can also enhance the safety, shielding and anti-interference of the sensor.

[0046] In addition, since the present invention provides a processing method for a sensor chip autonomous cleaning and protection system composed of a cleaning chip, a gas main channel and a gas auxiliary channel, the sensor chip autonomous cleaning and protection system can be manufactured using this method, so that the sensor has the advanced function of autonomous cleaning and protection, avoiding the deposition of microparticles in the gas on the surface of the sensor chip to cause chip contamination, and solving the problem that the sensor chip is easily affected by the adhesion of microparticles and affects the detection accuracy and service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the specific implementation of the present invention, the following will briefly introduce the drawings required for use in the specific implementation. In all the drawings, each element or part is not necessarily drawn according to the actual scale.

[0048] Figure 1 A schematic diagram of a method for processing a gas mass flow sensor provided by the present invention;

[0049] Figure 2 is a three-dimensional schematic diagram of a gas mass flow sensor in one embodiment;

[0050] Figure 3 for Figure 2 A schematic diagram of a cover body in a gas mass flow sensor shown;

[0051] Figure 4 for Figure 2 A schematic diagram of a base plate in a gas mass flow sensor shown;

[0052] Figure 5 for Figure 2 A schematic diagram of a cover plate in a gas mass flow sensor shown;

[0053] Figure 6 for Figure 2 A schematic diagram of a cleaning chip in a gas mass flow sensor is shown;

[0054] Figure 7 for Figure 1 A schematic diagram of the processing flow of a detection chip in a gas mass flow sensor processing method shown;

[0055] Figure 8 for Figure 1 The schematic diagram of the processing flow of the cleaning chip in the gas mass flow sensor processing method is shown.

[0056] Reference numerals:

[0057] 1. Bottom plate; 11. Cover plate; 12. First heat insulation cavity;

[0058] 2. Detection chip; 21. Detection element; 22. Heating element; 23. First polyimide film layer; 24. First photoresist film layer; 25. Detection chip resistance film; 26. First electrical lead film; 27. Second polyimide layer; 28. First terminal;

[0059] 3. Cover body; 31. Main gas flow channel; 32. Second heat insulation cavity; 33. Gas auxiliary flow channel;

[0060] 4. Clean chip; 41. Clean chip substrate; 42. Second photoresist film layer; 43. Clean electrode; 44. Second electrical lead film; 45. Third polyimide film layer; 46. Second terminal. DETAILED DESCRIPTION

[0061] The following embodiments of the technical solution of the present invention are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore only used as examples, and cannot be used to limit the protection scope of the present invention.

[0062] Research has found that in order to reduce the heat transfer of the sensor substrate (reducing the heat transfer of the substrate has an important impact on the detection accuracy of the sensor), the traditional processing technology usually coats a layer of silicon nitride film with good thermal insulation on the surface of the substrate. However, after the introduction of the silicon nitride film layer, due to the poor bonding between the platinum resistor film (the detection element of the sensor) and the silicon nitride film, in order to solve the problem of weak bonding, a titanium film is usually plated between the silicon nitride film and the platinum resistor film. However, the introduction of the titanium film actually turns the originally pure platinum resistor into a platinum / titanium mixture. The mixture will cause the resistivity and temperature coefficient of the platinum resistor to become complicated, because the temperature coefficient and resistivity of the mixture will vary depending on the components, and even the different penetration positions of the two components when mixed will also lead to different temperature coefficients. For example, the temperature coefficient when the titanium layer and the platinum layer are clearly demarcated is different from the temperature coefficient when the two layers penetrate each other. It is difficult to ensure that the components and penetration positions of resistor films processed in different batches are the same each time, which leads to poor repeatability and consistency of the temperature coefficient and resistivity of the resistor. The sensor uses the linear functional relationship between the resistance value and temperature of the temperature measuring element platinum resistor film to detect thermal temperature difference, and the functional relationship between the resistance value and temperature is determined by the temperature coefficient and resistivity of the platinum resistor film. Therefore, the repeatability and consistency of these two physical parameters are crucial to the performance of the sensor, especially the temperature coefficient, which has a greater impact.

[0063] In order to solve this important technical problem, the present invention discloses a "solid-vacuum / gas-solid" coupled insulation structure and its processing technology, which replaces the traditional process of making silicon nitride insulation film for insulation, not only can obtain better insulation effect, but also can avoid the problem of weak bonding between the two and affecting chip performance when making the detection chip resistance film on the silicon nitride surface in the traditional process. Specifically:

[0064] See also Figures 1 to 8 The present invention provides a method for processing a gas mass flow sensor, comprising:

[0065] S110, providing a base plate 1;

[0066] S120, processing and manufacturing a detection element 21 and a heating element 22 on the top surface of the bottom plate 1 to construct a detection chip 2, wherein the detection element 21 is manufactured at the upstream and downstream of the heating element 22 and at the inlet end of the gas;

[0067] S130, providing a cover plate 11, and processing a groove structure on the top surface of the bottom plate 1 and one side surface of the cover plate 11, then relatively installing the groove structure of the bottom plate 1 and the groove structure of the cover plate 11 to form a first heat insulation cavity 12, and then sealing to construct a first heat isolation structure with a "solid-vacuum / gas-solid" coupling structure;

[0068] S140, providing a cover body blank, and processing and manufacturing a gas main flow channel 31 and a gas auxiliary flow channel 33 on the cover body blank to construct a gas flow channel, and manufacturing a second heat insulation cavity 32 to complete the manufacturing of the cover body 3;

[0069] S150, installing the cover body 3 on the top surface of the bottom plate 1, and then installing the sealing plates on both ends of the second heat insulation cavity 32 and sealing to construct a second heat isolation structure; when installing the cover body 3, ensure that the gas flow channel covers the detection chip to construct a detection unit;

[0070] S160, providing a cleaning chip substrate 41, and processing and manufacturing a cleaning chip 4 on the cleaning chip substrate 41;

[0071] S170 , installing the cleaning chip 4 on the surface of the cover plate 11 facing away from the base plate 1 to construct a sensor dirt autonomous cleaning system consisting of the cleaning chip 4 , the gas main channel 31 and the gas auxiliary channel 33 .

[0072] In the specific implementation, the processing and manufacturing method of the detection chip 2 can preferably be surface plasma activation treatment + stripping process + etching process to solve the problems of accurate chip surface film pattern, uniform thickness, surface smoothness, weak stress, and excellent repeatability and consistency of the temperature coefficient and resistivity of the resistor film to ensure the excellent performance of the sensor. Of course, other processing techniques can also be selected according to actual conditions to achieve accurate chip surface film pattern, uniform thickness, surface smoothness, weak stress, and excellent repeatability and consistency of the temperature coefficient and resistivity of the resistor film to ensure the excellent performance of the sensor. For example: laser activation treatment or chemical activation treatment and their combination activation treatment methods are selected to replace surface plasma activation treatment; or activation treatment + etching process is selected; or activation treatment + stripping process is selected, etc.

[0073] In specific implementation, the processing methods of the grooves of the bottom plate 1 and the grooves of the cover plate 11 can preferably be a process combining wet etching + mechanical and chemical grinding, so as to achieve the requirement of smooth and flat groove sealing surfaces in a low-cost manner to improve the sealing performance. Of course, other processing techniques can also be selected according to actual conditions to achieve the requirement of smooth and flat groove sealing surfaces, such as laser etching process, etc.

[0074] In specific implementation, the processing method of the gas main flow channel 31, the gas auxiliary flow channel 33 and the second insulation cavity 32 may preferably be a process combining wet etching + laser etching process + mechanical and chemical grinding, so as to achieve smooth and flat inner surfaces of the gas main flow channel 31 and the gas auxiliary flow channel 33, so as to reduce the influence of the viscosity effect of the flow channel surface on the sensor detection accuracy, and the sealing surface of the second insulation cavity 32 is smooth and flat to improve the sealing performance. Of course, other processing techniques may also be selected according to actual conditions to achieve smooth and flat inner surfaces of the gas main flow channel 31 and the gas auxiliary flow channel 33, so as to reduce the influence of the viscosity effect of the flow channel surface on the sensor detection accuracy, and the sealing surface of the second insulation cavity 32 is smooth and flat to improve the sealing performance. For example: dry etching is selected to replace the wet etching process; or etching process + laser etching process is selected; or etching process + mechanical and chemical grinding combination process is selected, etc.

[0075] In the specific implementation, the processing and manufacturing method of the cleaning chip 4 can preferably be a surface mechanical activation treatment + stripping process + etching process to solve the problems of accurate chip surface film pattern, uniform thickness, surface smoothness, weak stress, and excellent repeatability and consistency of the temperature coefficient and resistivity of the resistor film to ensure the excellent performance of the sensor. Of course, other processing techniques can also be selected according to actual conditions to achieve accurate chip surface film pattern, uniform thickness, surface smoothness, weak stress, and excellent repeatability and consistency of the temperature coefficient and resistivity of the resistor film to ensure the excellent performance of the sensor. For example: select laser activation treatment or chemical activation treatment and their combination activation treatment methods to replace surface mechanical activation treatment; or select activation treatment + etching process; or select activation treatment + stripping process, etc.

[0076] The gas mass flow sensor manufactured by the above processing technology is as follows: Figure 2 As shown, when in use, Joule heat is generated by the heating element 22. After the gas enters the detection unit, the gas upstream of the heating element 22 brings the heat generated by the heating element 22 to the downstream of the heating element 22, forming an upstream and downstream thermal temperature difference. Since the detection element 21 is provided upstream and downstream of the heating element 22, the detection element 21 detects the corresponding temperature values ​​at the upstream and downstream. By calculating the temperature difference between the upstream and downstream and comparing the temperature difference-flow curve, the flow value of the measured airflow can be obtained, thereby obtaining the flow detection data.

[0077] Due to the above-mentioned gas mass flow sensor processing method, a first insulation cavity 12 composed of a base plate 1 and a cover plate 11 with a "solid-vacuum / gas-solid" coupling structure and its processing method are provided, and a first thermal isolation structure is processed and manufactured to isolate the heat generated by the heating element 22 in the detection unit from propagating to the bottom of the base plate 1, so as to avoid the heat in the detection unit from being lost to the bottom of the substrate and destroying the original real thermal temperature difference distribution in the detection unit, thereby ensuring and improving the accuracy of thermal temperature difference detection in the detection unit. It should be noted that in the specific implementation, the first insulation cavity 12 is evacuated to form a "solid-vacuum-solid" coupling insulation structure, which has a better insulation effect and is conducive to improving the detection accuracy and stability of the sensor. Of course, other gases with smaller specific heat capacity can also be injected into the insulation cavity according to actual conditions.

[0078] Due to the above-mentioned gas mass flow sensor processing method, a first insulation cavity 12 with a "solid-vacuum / gas-solid" coupling structure and its processing technology are disclosed, which replaces the traditional insulation process scheme for processing and manufacturing silicon nitride film layers. It can not only obtain better insulation effect, but also avoid the problem of weak bonding between the two affecting chip performance when manufacturing the detection chip resistance film on the silicon nitride surface in the traditional process.

[0079] Due to the above-mentioned gas mass flow sensor processing method, a processing method for a sensor chip self-cleaning and protection system composed of a cleaning chip 4, a gas main channel 31 and a gas auxiliary channel 33 is also provided. The sensor chip self-cleaning and protection system is manufactured by this method, so that the sensor has the advanced function of self-cleaning and protection, which avoids the deposition of microparticles in the gas on the surface of the sensor chip and causes chip contamination, and solves the problem that the sensor chip is easily affected by the adhesion of microparticles and affects the detection accuracy and service life.

[0080] Furthermore, the present invention also proposes a process for making a polyimide film on the surface of a silicon substrate, and making a detection chip resistor film on the surface after surface activation treatment, replacing the traditional processing technology of making a titanium / platinum mixed film layer to solve the problem of weak adhesion between the detection chip resistor film and the silicon nitride film, so that the composition of the resistor film becomes a pure platinum single material, solving the consistency and repeatability problems of important physical parameters such as the temperature coefficient and resistivity of the chip resistor film material, not only improving the accuracy and stability of sensor detection, but also, because polyimide has excellent electrical insulation performance, shielding performance and anti-interference performance, this process can also enhance the safety, shielding and anti-interference of the sensor. Specifically:

[0081] See also Figure 7 The present invention provides a processing method for manufacturing a detection chip 2 and a first heat insulation cavity 12 on a bottom plate 1:

[0082] S110, selecting a semiconductor chip substrate as the bottom plate 1, cleaning and drying it, and then performing surface activation treatment;

[0083] Specifically, the bottom plate 1 is first cleaned with deionized water, then cleaned with anhydrous ethanol and dried, and then the top surface of the bottom plate 1 is subjected to surface activation treatment, and then cleaned with acetone solution, and then cleaned with deionized water and anhydrous ethanol and dried.

[0084] S120, forming a first polyimide film layer 23 on the top surface of the bottom plate 1, and after the first polyimide film layer 23 is formed and stabilized, firstly cleaning and drying the first polyimide film layer 23 according to the cleaning step in S110, and then performing surface activation treatment;

[0085] S130, coating the first photoresist film layer 24 on the surface of the first polyimide film layer 23;

[0086] S140, processing and manufacturing the detection chip resistance film 25;

[0087] Specifically, the first photoresist film layer 24 is exposed and developed, and specific grooves having the same geometric shapes as the resistance films of the detection element 21 and the heating element 22 are formed on its surface. After cleaning and drying, a layer of platinum material is sputtered on the surface of the first photoresist film layer 24 having the specific grooves by magnetron sputtering to form a platinum film. After the film layer material is formed, the first photoresist film layer 24 is removed. In the process of removing the first photoresist film layer 24, the resistance film material film formed on the non-groove portion of the first photoresist film layer 24 is removed together with the photoresist film layer, and the remaining resistance film material located in the specific groove portion is deposited on the surface of the first polyimide film layer 23 to form the resistance film of the detection element 21 and the resistance film of the heating element 22.

[0088] S150, processing and manufacturing the first electrical lead film 26 and the first connection terminal 28 on the surface of the first polyimide film layer 23;

[0089] S160, performing alloying treatment after the resistance film of the detection element 21, the resistance film of the heating element 22, the first electric lead film 26 and the first terminal 28 have been manufactured;

[0090] Specifically: alloying treatment is performed while passing non-oxidizing and non-flammable gas to eliminate the film stress of the resistance film of the detection element 21, the resistance film of the heating element 22, the first electric lead film 26 and the first terminal 28, and at the same time, enhance the bonding force between the resistance film of the detection element 21, the resistance film of the heating element 22, the first electric lead film 26 and the first terminal 28 and the first polyimide film layer 23, and enhance the bonding tightness of the connection between the resistance film of the detection element 21, the resistance film of the heating element 22, the first electric lead 26 and the first terminal 28.

[0091] S170, after the alloying treatment is completed, a layer of polyimide material is deposited on the surface of the detection chip 2 to form a second polyimide film layer 27, and after the second polyimide film layer 27 is formed and stabilized, it is cleaned and dried using the cleaning method in step S110;

[0092] S180, after the processing of the detection chip 2 is completed, rough processing of the groove structure is performed on the bottom surface of the bottom plate 1;

[0093] Specifically, firstly, the surface that needs to be corroded is scribed, and then a protective layer with corrosion resistance is applied to all surfaces that do not need to be corroded (including the top surface of the bottom plate where the detection chip 2 has been made). Since the surface coated with the protective layer is higher than the other surfaces not coated with the protective layer by the thickness of the coating layer, a pit-shaped area is formed between the surface with the protective layer and the surface without the protective layer. Then, an appropriate amount of corrosive solution is slowly injected into the pit-shaped area, the corrosion processing is observed in real time, and the corrosive solution is added in time. It should be noted that a certain processing allowance should be reserved for wet etching processing to facilitate the next step of fine processing.

[0094] S190, selecting a rectangular solid material as a blank sheet of the cover plate 11, and washing and drying the blank sheet of the cover plate 11 by the same steps as in S110;

[0095] S200, rough-processing the groove of the cover plate 11 by the same steps as in S180;

[0096] S210, after the grooves of the bottom plate 1 and the grooves of the cover plate 11 are roughly processed, the protective layer is removed, and the grooves are cleaned and dried;

[0097] S220, finishing the sealing surfaces of the groove of the bottom plate 1 and the groove of the cover plate 11;

[0098] Specifically, the sealing surfaces of the grooves of the bottom plate 1 and the cover plate 11 are first ground and polished to make their sizes and inner surface smoothness meet the design requirements of the sensor insulation cavity, and then cleaned and dried according to the steps in S110.

[0099] S230 , installing the cover plate 11 and the base plate 1 to construct a first thermal isolation structure.

[0100] Specifically, the groove of the cover plate 11 is installed relative to the groove of the base plate 1 to construct a first insulation cavity 12, and then sealed to construct a first thermal isolation structure with a "solid-vacuum / gas-solid" coupling structure, which is used to isolate the heat generated by the heating element 22 from dissipating heat to the bottom of the base plate 1.

[0101] In this embodiment, the semiconductor chip base plate 1 may preferably be a single crystal silicon substrate, but other semiconductor substrates may also be used, such as a ceramic substrate, a glass substrate, etc.

[0102] In this embodiment, the surface activation treatment process of the top surface of the bottom plate 1 can preferably be a surface plasma activation treatment process. Of course, other activation treatment technologies can also be selected, such as mechanical activation, laser activation, etc.

[0103] In this embodiment, the first photoresist film layer 24 is evenly coated, preferably in a professional coating machine, and medium and high speed rotation coating is set to achieve a uniform thickness and a smooth surface of the first photoresist film layer 24. Of course, other methods can also be used for even coating according to actual conditions to achieve a uniform thickness and a smooth surface of the first photoresist film layer 24. The manufacturing thickness of the first photoresist film layer 24 can be preferably 2 to 20 μm. Of course, its thickness can also be appropriately increased or decreased according to actual needs.

[0104] In this embodiment, the method for making the first electrical lead 26 and the first terminal 28 may preferably be an etching method, such as dry etching, wet etching, etc. Of course, magnetron sputtering may also be used according to actual needs. The material for making the first electrical lead 26 and the first terminal 28 may preferably be a metal conductor material with a low resistivity, such as copper, silver, gold, platinum, aluminum and its alloys, etc. Considering the material cost, it is recommended to use aluminum or copper metal. Of course, non-metallic materials with conductivity, such as polysilicon, etc., may also be selected according to actual conditions. The thickness of the first electrical lead film 26 and the first terminal 28 is preferably 0.01-0.1 μm and 0.1-1 μm, respectively. Of course, the thickness may also be appropriately increased or decreased according to actual needs.

[0105] In this embodiment, the non-oxidizing and non-flammable gas introduced during the alloying treatment may preferably be nitrogen. Of course, other non-oxidizing and non-flammable gases, such as carbon dioxide gas, etc., may also be selected according to actual conditions. The alloying treatment temperature may preferably be 300 to 500° C. Of course, it may also be appropriately adjusted according to specific circumstances. The alloying treatment time may preferably be 20 to 40 minutes. Of course, it may also be appropriately adjusted according to specific circumstances.

[0106] In the present embodiment, the manufacturing method of the first polyimide film layer 23 and the second polyimide film layer 27 may preferably be a vapor deposition method to achieve uniform film layers and smooth surfaces. Of course, other methods may also be selected, such as magnetron sputtering, etc. In specific implementation, the manufacturing thickness of the first polyimide film layer 23 is generally greater than the manufacturing thickness of the second polyimide film layer 27. For example, the manufacturing thickness of the first polyimide film layer 23 may preferably be 10 to 20 μm; the manufacturing thickness of the second polyimide film layer 27 may preferably be 0.1 to 0.2 μm. Of course, the specific thickness size may be adjusted according to actual conditions. The surface activation treatment process of the first polyimide film layer 23 may preferably be a surface plasma activation treatment process.

[0107] It should be noted that, in specific implementation, the second polyimide film layer 27 needs to completely cover the resistance film of the detection element 21 , the resistance film of the heating element 22 , and the area where the first electrical lead film 26 is located, but does not cover the first terminal 28 .

[0108] In this embodiment, the material of the cover plate 11 may preferably be a material with a low thermal conductivity, such as quartz glass. Of course, other materials with a low thermal conductivity, such as organic resin materials, composite materials, etc., may also be used.

[0109] In this embodiment, the rough processing method of the groove of the bottom plate 1 and the groove of the cover plate 11 can preferably be a low-cost wet etching process. The preparation of the etching solution needs to be determined according to the materials of the bottom plate 1 and the cover plate 11, and the material of the protective layer needs to be selected according to the composition of the etching solution. For example, if the bottom plate 1 uses a single crystal silicon substrate, it is appropriate to prepare sodium hydroxide or potassium hydroxide or hydrofluoric acid solution as the etching solution; if the cover plate 11 uses a quartz glass material, it is appropriate to prepare a hydrofluoric acid solution as the etching solution; if a hydrofluoric acid solution is used as the etching solution, it is appropriate to use photoresist as the protective layer material. Of course, non-wet etching processing can also be selected according to actual conditions, such as mechanical processing or laser processing.

[0110] In this embodiment, the coating thickness of the protective layer may be preferably 1 to 20 mm, and the reserved processing allowance for the etching process may be preferably 0.05 to 0.08 mm. Of course, the thickness of the protective layer and the allowance for the etching process may be appropriately adjusted according to actual needs.

[0111] In this embodiment, the grinding method of the sealing surface of the groove of the bottom plate 1 and the groove of the cover plate 11 can preferably be a process combining mechanical grinding and chemical grinding, because mechanical grinding combined with appropriate chemical grinding can reduce the bonding force of the chemical bonds between the molecules of the surface material to be ground, which is conducive to obtaining a more delicate and smooth processing surface, which can enhance the thermal insulation effect of the thermal insulation structure and improve the detection accuracy of the sensor. Of course, other grinding processes can also be selected according to actual needs to meet the requirements of relevant surface smoothness, such as: mechanical grinding or electrolytic grinding or a combination of the two.

[0112] In this embodiment, the first heat-insulating cavity 12 is evacuated into a vacuum heat-insulating cavity, and the heat-insulating effect is better. Of course, a gas with a smaller specific heat capacity can also be injected into the first heat-insulating cavity 12.

[0113] Due to the above-mentioned processing method, a first thermal isolation structure with a "solid-vacuum / gas-solid" coupling structure and its processing technology are disclosed, which replaces the traditional process of making silicon nitride insulation film for thermal insulation, and proposes to make a polyimide film on the surface of a silicon substrate, and make a chip resistor film after surface activation treatment, replacing the traditional processing technology of making a titanium / platinum mixed film layer to solve the problem of weak adhesion between the platinum film and the silicon nitride film, so that the component of the resistor film is changed to pure platinum single material, and the consistency and repeatability of important physical parameters such as the temperature coefficient and resistivity of the chip resistor film material are solved, which not only improves the detection accuracy and stability of the sensor, but also, because polyimide has excellent electrical insulation performance, shielding performance and anti-interference performance, this process can also enhance the safety, shielding and anti-interference of the sensor.

[0114] Due to the above-mentioned processing method, a sealing surface finishing process suitable for a micro-sized groove structure is provided for a micro-structured MEMS sensor, so that the sealing surface of the first thermal insulation cavity 12 is smooth and flat, thereby ensuring the sealing of the first thermal isolation structure, enhancing the thermal insulation effect, and solving the technical problem that the heat in the detection chip 2 is dissipated to the bottom of the base plate 1, which will affect the detection accuracy of the detection chip.

[0115] Due to the above-mentioned processing method, a process for the production of micron-level chip resistor film is provided, which includes surface activation treatment before coating and alloying treatment after coating, thereby ensuring the close bonding of the chip film layer and the electrical leads to the surface of the substrate, and improving the reliability and service life of the chip film layer; and because a process combining exposure, development, magnetron sputtering and stripping processes is set up to process and produce the resistor film of the detection element 21 and the heating element 22, the problems of accurate graphics, uniform thickness, smooth surface, weak stress, and close bonding of the microstructure of the detection chip resistor film are solved, and it can ensure that the temperature coefficient and resistivity of the manufactured resistor film have excellent repeatability and consistency, so that the sensor performance is excellent.

[0116] Furthermore, the present invention also provides a processing method for processing and manufacturing the gas main channel 31, the gas auxiliary channel 33 and the second heat insulation cavity 32 on the cover body 3, specifically:

[0117] S110, providing a blank sheet of the cover body 3 for processing and manufacturing the cover body 3;

[0118] Specifically, a rectangular solid material with a small thermal conductivity is selected as the blank of the cover body 3. The blank piece of the cover body 3 is washed with deionized water, washed with anhydrous ethanol and dried. After the blank piece of the cover body is cut so that the overall length, width and thickness of the cover body meet the requirements, it is washed and dried again with deionized water and anhydrous ethanol.

[0119] S120, preparing a corrosion solution required for wet corrosion for corrosion processing of the cover body 3;

[0120] S130, performing rough processing on the main gas channel 31, the auxiliary gas channel 33 and the second heat insulation cavity 32 on the cover blank;

[0121] Specifically, firstly, the surface that needs to be corroded is scribed, and then a protective layer with corrosion resistance is applied to the surface that does not need to be corroded. Since the surface coated with the protective layer is higher than the other surfaces not coated with the protective layer by the thickness of the coating layer, a pit-shaped area is formed between the surface with the protective layer and the surface without the protective layer. Then, a proper amount of the corrosive solution prepared in S120 is slowly injected into the pit-shaped area, the corrosion processing status is observed in real time, and the corrosive solution is added in time. It should be noted that a certain processing allowance should be reserved for wet etching processing to facilitate the next step of fine processing. S140, fine processing is performed on the gas main channel 31, the gas auxiliary channel 33 and the second insulation cavity 32;

[0122] Specifically, first remove the protective layer applied during rough processing, clean and dry it, then grind and polish the sealing surface of the second insulation cavity 32 and the contact surface of the cover body 3 and the bottom plate 1, then grind and polish the inner surfaces of the main gas channel 31 and the gas auxiliary channel 33 so that their dimensions and the smoothness of the inner surfaces meet the design requirements of the sensor, then clean and dry it, and then use laser etching technology on the inner walls on both sides of the gas channel to deepen the depth of the gas auxiliary channel 33 so that its depth dimension meets the design requirements of the sensor.

[0123] S150, installing the cover 3 and the base plate 1;

[0124] Specifically, the cover body 3 with the processed gas main channel 31, the second insulation cavity 32 and the gas auxiliary channel 33 is installed on the top surface of the base plate 1 and fixed with a sealant; then, sealing plates are installed at both ends of the second insulation cavity 32 and fixed with a sealant to construct a second thermal isolation structure for isolating the temperature thermal crosstalk between the two detection units and improving the sensor detection accuracy.

[0125] In this embodiment, the material of the cover 3 may preferably be quartz glass. Of course, other materials with low thermal conductivity, such as organic resin materials, composite materials, etc., may also be used.

[0126] In this embodiment, the rough processing method of the gas main channel 31, the second heat insulation cavity 32 and the gas auxiliary channel 33 can preferably be a low-cost wet etching process. The preparation of the etching liquid needs to be determined according to the material of the cover body 3, and the material of the protective layer needs to be selected according to the composition of the etching liquid. For example, if the cover body 3 is made of quartz glass material, it is advisable to prepare a hydrofluoric acid solution as the etching liquid; if the hydrofluoric acid solution is selected as the etching liquid, it is advisable to use photoresist as the protective layer material. Of course, non-wet etching processing, such as mechanical processing or laser processing, can also be selected according to actual conditions.

[0127] In specific implementation, the coating thickness of the protective layer may be preferably 1 to 20 mm, and the reserved processing allowance for the etching process may be preferably 0.2 to 0.5 mm. Of course, the thickness of the protective layer and the allowance for the etching process may be appropriately adjusted according to actual needs.

[0128] In this embodiment, the grinding method of the inner surface of the gas main channel 31 and the gas auxiliary channel 33 can preferably be a process combining mechanical grinding and chemical grinding, because mechanical grinding combined with appropriate chemical grinding can reduce the bonding force of chemical bonds between molecules of the surface material to be ground, which is conducive to obtaining a more delicate and smooth processed surface. Of course, other grinding processes can also be selected according to actual needs to achieve the requirements of relevant surface smoothness, such as: mechanical grinding or electrolytic grinding or a combination of the two.

[0129] Due to the above-mentioned gas mass flow sensor processing method, a wet etching process is provided for rough processing of the cover body 3 and the gas main channel 31 and the gas auxiliary channel 33 therein, thereby reducing the processing cost; and a fine processing process suitable for the wall of the gas flow channel of micro-size is provided for the micro-structure MEMS sensor, thereby improving the surface smoothness of the inner wall of the flow channel, reducing the interference of the fluid viscosity effect of the flow channel wall on the gas flow, and improving the accuracy of flow detection.

[0130] Due to the above-mentioned gas mass flow sensor processing method, a processing method for simultaneously manufacturing two groups of mutually spaced detection elements 21 and heating elements 22 on the detection chip is provided, so that each group of detection elements 21 can be simultaneously manufactured at the upstream and downstream of each group of heating elements 22 and the gas inlet end of each group of gas flow channels; and a processing method for simultaneously manufacturing two groups of mutually spaced gas flow channels on the cover body 3 is provided, so that the two groups of gas flow channels respectively cover the two groups of detection elements and heating elements to construct two groups of detection units, so that one group of detection units is used for small gas flow detection, and the other group of detection units is used for large gas flow detection. In specific use, the data obtained by the detection of the two groups of detection units are merged to obtain a wide range of flow detection data, which can not only expand the detection range of the sensor, but also optimize the design parameters of the two groups of detection units according to actual needs, so that the sensor can realize different detection accuracy, different detection sensitivity and different detection range and other functions, and solve the problem that the sensor sensitivity and detection range are limited and difficult to meet the actual needs of gas detection. At the same time, since the sensor made by the above method has a wider range of functions and applicability, the market competitiveness of the sensor is enhanced.

[0131] Due to the above-mentioned gas mass flow sensor processing method, a process for fine-machining the sealing surface of the second insulation cavity 32 is provided for the sealing surface of the microstructure, thereby enhancing the sealing of the second insulation cavity 32, ensuring a good insulation effect, isolating the temperature field thermal crosstalk between the two groups of detection units, solving the adverse effects of temperature field thermal crosstalk on the sensor detection performance, and ensuring the detection accuracy of the sensor.

[0132] For further information, see Figure 8 The present invention also provides a process method for processing the cleaning chip 4, specifically:

[0133] S110, providing a cleaning chip substrate 41 for processing and manufacturing the cleaning chip, and performing activation treatment on the surface to be coated after cleaning;

[0134] Specifically, the chip substrate 41 is first cleaned with deionized water, then cleaned with anhydrous ethanol and dried, and then the surface to be coated is activated, then cleaned with acetone solution, and then cleaned with deionized water and anhydrous ethanol and dried.

[0135] S120, coating the second photoresist film layer 42 evenly on the surface to be coated of the clean chip substrate 41;

[0136] S130, processing and manufacturing a cleaning electrode 43;

[0137] Specifically, the second photoresist film layer 42 is exposed and developed, and a specific groove with the same geometric shape as the cleaning electrode 43 is formed on its surface. After cleaning and drying, a layer of conductive material film is sputtered on the surface of the second photoresist film layer 42 with the specific groove by magnetron sputtering. After the conductive material film is formed, the second photoresist film layer 42 is removed. In the process of removing the second photoresist film layer 42, the conductive material film formed in the non-groove part of the second photoresist film layer 42 is removed together with the photoresist film layer, and the remaining conductive material located in the specific groove part is deposited on the surface of the cleaning chip substrate 41 to form a cleaning electrode 43.

[0138] S140, manufacturing a second electric lead film 44 and a second terminal 46 on the clean chip substrate 41 on which the clean electrode 43 has been manufactured;

[0139] S150, alloying treatment is performed after the clean electrode 43, the second electrical lead film 44 and the second terminal 46 are manufactured;

[0140] Specifically: alloying treatment is performed while passing non-oxidizing and non-flammable gas to eliminate the film stress of the cleaning electrode 43, the second electric lead film 44 and the second terminal 46, and at the same time, enhance the bonding force between the cleaning electrode 43, the second electric lead film 44 and the second terminal 46 and the cleaning chip substrate 41, and enhance the bonding tightness of the connection between the cleaning electrode 43, the second electric lead film 44 and the second terminal 46.

[0141] S160, after the alloying treatment is completed, a layer of polyimide material is deposited on the surface of the cleaning chip 4 to form a third polyimide film layer 45, and after the third polyimide film layer 45 is formed and stabilized, it is cleaned and dried using the cleaning method in step S110;

[0142] S170, installing the manufactured cleaning chip 4 on the bottom surface of the base plate 1 and fixing it tightly.

[0143] In this embodiment, the cleaning chip substrate 41 may preferably be an insulating substrate, such as a quartz substrate, a ceramic substrate, etc. Of course, other non-insulating semiconductor substrates, such as a silicon-based substrate, may also be selected according to actual needs. It should be noted that if a non-insulating semiconductor substrate is selected, since there is a conductive phenomenon between the semiconductor substrate and the cleaning electrode and the first electrical lead, it is necessary to make a film layer of insulating material, such as a polyimide film, on the surface of the substrate after completing the above step S110 and before performing step S120 to ensure the electrical insulation safety of the cleaning chip, and then perform subsequent processing steps.

[0144] In this embodiment, the surface activation treatment of the clean chip substrate 41 to be coated may preferably be a mechanical activation treatment process to reduce process costs, such as grinding, polishing, shot blasting, sand blasting, etc. Of course, laser activation treatment or chemical activation treatment or a combination of mechanical activation, laser activation, chemical activation and other methods may also be used for activation treatment according to actual needs.

[0145] In this embodiment, the second photoresist film layer 42 is evenly coated, preferably in a professional coating machine, and medium and high speed rotation and coating are set to achieve uniform thickness and smooth surface of the second photoresist film layer 42. Of course, other methods can also be used for even coating according to actual conditions to achieve uniform thickness and smooth surface of the second photoresist film layer 42. In specific implementation, the manufacturing thickness of the second photoresist film layer 42 can be preferably 2 to 20 μm. Of course, its thickness can also be appropriately increased or decreased according to actual needs.

[0146] In this embodiment, the material of the cleaning electrode 43 can preferably be a metal conductor material with low resistivity, such as copper, silver, gold, platinum, aluminum and its alloys. Considering the cost of the material, copper is recommended. Of course, it can also be made of a non-metallic material with conductivity according to actual needs, such as polysilicon material. In specific implementation, the thickness of the cleaning electrode film 43 can preferably be 0.1 to 1 μm. Of course, its thickness can also be appropriately increased or decreased according to actual needs.

[0147] In this embodiment, the manufacturing method of the second electric lead film 44 and the second terminal 46 may preferably be an etching method, such as dry etching, wet etching, etc. Of course, magnetron sputtering may also be used according to actual needs. The manufacturing material of the second electric lead film 44 and the second terminal 46 may preferably be a metal conductor material with a low resistivity, such as copper, silver, gold, platinum, aluminum and its alloys, etc. Considering the material cost, it is recommended to use aluminum or copper metal. Of course, non-metallic materials with conductivity, such as polycrystalline silicon, etc., may also be selected according to actual needs. The manufacturing thickness of the second electric lead film 44 and the second terminal 46 may preferably be 0.01-0.1 μm and 0.1-1 μm, respectively. Of course, the thickness size may also be appropriately increased or decreased according to actual needs.

[0148] In the specific implementation, the cleaning electrode 43, the second electric lead film 44 and the second terminal 46 can be preferably made of the same material. If the cleaning electrode 43, the second electric lead film 44 and the second terminal 46 are made of the same material, the cleaning electrode 43, the second electric lead film 44 and the second terminal 46 can be simultaneously manufactured in the above-mentioned step S130. It is only necessary to make the geometric shape of the groove into the geometric shape when the cleaning electrode 43, the second electric lead film 44 and the second terminal 46 are combined when exposing and developing the second photoresist film layer 42 to produce a specific groove, and then the cleaning electrode 43, the second electric lead film 44 and the second terminal 46 can be simultaneously manufactured, thereby simplifying the processing process.

[0149] In this embodiment, the non-oxidizing and non-flammable gas introduced during the alloying treatment may preferably be nitrogen. Of course, other non-oxidizing and non-flammable gases, such as carbon dioxide gas, etc., may also be selected according to actual conditions. The temperature of the alloying treatment may preferably be 300 to 500° C. Of course, it may also be appropriately adjusted according to specific circumstances. The alloying treatment time may preferably be 20 to 40 minutes. Of course, it may also be appropriately adjusted according to specific circumstances.

[0150] In this embodiment, the manufacturing method of the third polyimide film layer 45 may preferably be a vapor deposition method. Of course, other manufacturing methods may also be selected according to actual needs, such as magnetron sputtering. The manufacturing thickness of the third polyimide film layer 45 may preferably be 0.5 to 2 μm. Of course, its thickness may also be increased or decreased according to actual needs.

[0151] In this embodiment, the third polyimide film layer 45 needs to completely cover the area where the cleaning electrode 43 and the second electrical lead film 44 are located, but does not cover the second wiring terminal 46 .

[0152] Due to the above-mentioned processing method, an insulating substrate is used to manufacture the cleaning chip 4, and in view of the electrical safety problem of the cleaning chip, a process is set up to manufacture a third polyimide film layer 45 with extremely strong insulation on the surface of the cleaning electrode and the electrical lead, thereby ensuring that the cleaning chip 4 has extremely high electrical safety; and because a process is provided for performing surface activation treatment before manufacturing the cleaning electrode and performing alloying treatment after the cleaning electrode is manufactured, the chip film layer and the electrical leads are tightly bonded to the surface of the cleaning chip substrate, thereby improving the reliability and service life of the cleaning chip 4.

[0153] Due to the processing technology of the cleaning chip 4 disclosed in the present invention, the cleaning electrode and the electrical lead can be preferably made of the same low-cost material, which can reduce the processing cost and simplify the process flow; and because the cleaning electrode 43 is manufactured by a process combining exposure, development, magnetron sputtering and stripping processes, the problems of accurate graphics, uniform thickness, smooth surface, weak stress, and tight bonding of the cleaning electrode are solved, ensuring that the resistivity of the cleaning electrode has excellent repeatability and consistency, thereby enhancing the cleaning performance of the cleaning chip 4.

[0154] Due to the above-mentioned gas mass flow sensor processing method, a process for fine processing of the flow channel wall is provided for the discharge of micro-particles, thereby reducing the interference of the fluid viscosity effect of the flow channel wall on the gas flow and the discharge of micro-particles; and because a laser etching process suitable for micro-size is provided for deepening the two sides of the auxiliary flow channel close to the flow channel wall, it is beneficial to the discharge of dirty particles and improves the autonomous cleaning effect of the cleaning chip 4.

[0155] The gas mass flow sensor processing method disclosed in the present invention has the following advantages:

[0156] 1. Since the present invention discloses a "solid-vacuum / gas-solid" coupled insulation structure and its processing and manufacturing process, a new insulation method is formed, which replaces the traditional insulation process scheme for processing and manufacturing silicon nitride film, and achieves a better insulation effect; and since the present invention proposes a processing technology for manufacturing a polyimide film on the surface of a silicon substrate and manufacturing a chip resistor film after surface activation treatment, it replaces the traditional processing technology for manufacturing a titanium / platinum mixed film layer to solve the problem of weak adhesion between the platinum film and the silicon nitride film, so that the component of the resistor film becomes a pure platinum single material, and solves the consistency and repeatability problems of important physical parameters such as the temperature coefficient and resistivity of the chip resistor film material, which not only improves the detection accuracy and stability of the sensor, but also because polyimide has excellent electrical insulation performance, shielding performance and anti-interference performance, this process can also enhance the safety, shielding and anti-interference of the sensor.

[0157] 2. The gas mass flow sensor processing method disclosed in the present invention provides a processing method that can simultaneously produce two sets of detection units spaced apart from each other. The two sets of detection units produced by this process can be used for detection in different situations, and can achieve functions such as different detection accuracy, different detection sensitivity, and different detection ranges, solving the problem that the sensitivity and detection range of the sensor are limited and difficult to meet actual needs. At the same time, since the sensor produced by the above method has a wider range of functions and applicability, the market competitiveness of the sensor is enhanced.

[0158] 3. Due to the gas mass flow sensor processing method disclosed in the present invention, a processing method for a sensor dirty self-cleaning and protection system composed of a cleaning chip 4, a gas main channel 31 and a gas auxiliary channel 33 is provided. The sensor chip dirty self-cleaning and protection system is processed and manufactured by this method, which can make the sensor have the advanced function of self-cleaning and protection, avoid the micro-particles in the gas from being deposited on the surface of the sensor chip to cause chip dirt, and solve the problem that the sensor chip is easily affected by the attachment of micro-particles and affects the detection accuracy and service life. At the same time, due to the use of the processing technology disclosed in the present invention, the cleaning electrode and the electrical lead can be preferably made of the same low-cost material, which can simplify the process flow and reduce the processing cost.

[0159] 4. Due to the gas mass flow sensor processing method disclosed in the present invention, a fine processing process suitable for the gas flow channel wall of micro-size is provided for the micro-structure MEMS sensor, which reduces the interference of the fluid viscosity effect of the flow channel wall on the gas flow and improves the flow detection accuracy; and because a laser etching process suitable for micro-size is provided for deepening the two side parts of the gas auxiliary flow channel 33 close to the flow channel wall, it is beneficial to the discharge of dirty particles and improves the self-cleaning effect of the cleaning chip 4.

[0160] 5. Due to the gas mass flow sensor processing method disclosed in the present invention, for the production of micron-level detection chip resistor film, a process of surface activation treatment before coating and alloying treatment after coating is provided, thereby ensuring the close bonding of the chip film layer and the electrical leads to the substrate surface, and improving the reliability and service life of the chip film layer; and because a process combining exposure, development, magnetron sputtering and stripping processes is set up to process and manufacture the resistor film of the detection element 21 and the heating element 22, the problems of accurate graphics, uniform thickness, smooth surface, weak stress, and close bonding of the microstructure of the detection chip resistor film are solved, and it can ensure that the temperature coefficient and resistivity of the manufactured resistor film have excellent repeatability and consistency, so that the sensor performance is excellent.

[0161] 6. Due to the gas mass flow sensor processing method disclosed in the present invention, a process for rough processing of the first insulation cavity 12 and the second insulation cavity 32 using wet etching is provided, and a sealing surface finishing process suitable for miniature size is provided, which not only ensures the sealing of the thermal isolation structure and enhances the thermal insulation effect, but also solves the technical problems of heat loss of the heating element and thermal crosstalk affecting the detection accuracy, and reduces the processing cost.

[0162] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. A method for processing a gas mass flow sensor, characterized in that: Provide a base plate; Processing and manufacturing a detection element and a heating element on the top surface of the bottom plate to construct a detection chip, wherein the detection element is manufactured at the upstream and downstream of the heating element and at the gas inlet end; Providing a cover plate, and processing a groove structure on the bottom surface of the base plate and one side surface of the cover plate, then installing the groove structure of the base plate and the groove structure of the cover plate relative to each other to form a first heat insulation cavity, and then sealing to construct a first heat isolation structure; Providing a cover body blank, and processing and manufacturing a gas main flow channel and a gas auxiliary flow channel on the cover body blank to construct a gas flow channel, and manufacturing a second heat insulation cavity to complete the manufacture of the cover body; The cover is installed on the top surface of the bottom plate, and then the sealing plates are installed on both ends of the second heat insulation cavity and sealed to construct a second heat isolation structure; when installing the cover, ensure that the gas flow channel covers the detection chip to construct a detection unit; Providing a cleaning chip substrate, and processing and manufacturing a cleaning chip on the cleaning chip substrate; and The cleaning chip is mounted on the surface of the cover plate facing away from the base plate to construct a sensor dirt autonomous cleaning system consisting of the cleaning chip, the main gas channel and the auxiliary gas channel.

2. The gas mass flow sensor processing method according to claim 1, characterized in that: The processing method of the detection chip and the first thermal insulation cavity is: Provide and clean the baseboard for use; Plating a polyimide film on the top surface of the bottom plate to form a first polyimide film layer; uniformly coating a first photoresist film layer on the first polyimide film layer; Manufacturing a detection chip resistance film layer on the base plate by exposure, development, sputtering, and stripping processes; Processing and manufacturing a first electrical lead film and a first terminal on the surface of the first polyimide film layer; Alloying the detection chip having the detection element resistance film, the heating element resistance film, the electric lead film and the terminal; A second polyimide film layer is formed on the surface of the detection chip to cover the detection element resistance film, the heating element resistance film and the area where the first electric lead film is located; Processing a groove structure on the bottom surface of the bottom plate; Provide and clean the cover blank for use; Processing a groove structure on the surface of the cover plate blank; The groove structure of the bottom plate and the groove structure of the cover plate are relatively installed to form the first heat insulation cavity, and then sealed to form the first thermal isolation structure.

3. The gas mass flow sensor processing method according to claim 2, characterized in that: The gas mass flow sensor processing method provides a surface activation treatment process before coating the bottom plate surface; after completing the processing of the groove of the bottom plate and the groove of the cover plate, a finishing process is also provided for grinding and polishing the sealing parts in the groove structure of the bottom plate and the groove of the cover plate.

4. The gas mass flow sensor processing method according to claim 2, characterized in that: The gas mass flow sensor processing method, when processing and manufacturing the detection chip on the top surface of the base plate, sets a process for manufacturing two groups of detection elements and heating elements spaced apart from each other on the detection chip, so that each group of the detection elements is manufactured upstream and downstream of each group of the heating elements and at the gas inlet end of each group of the gas flow channels.

5. The gas mass flow sensor processing method according to claim 1, characterized in that: The process for processing and manufacturing the gas flow channel and the second heat insulation cavity on the cover body is as follows: Provide cover blanks, clean and dry them; Prepare wet etching solution for use; A protective layer is applied to the places where etching is not required, and the gas main flow channel, the gas auxiliary flow channel and the second insulation cavity are etched on the cover blank with a prepared wet etching liquid.

6. The gas mass flow sensor processing method according to claim 5, characterized in that: The gas mass flow sensor processing method further provides a finishing process for grinding and polishing the channel wall surfaces of the gas main channel and the auxiliary channel when processing and manufacturing the gas channel on the cover blank.

7. The gas mass flow sensor processing method according to claim 5, characterized in that: The gas mass flow sensor processing method, when processing and manufacturing the gas flow channel on the cover body blank, is provided with a processing technology for processing and manufacturing two groups of the gas flow channels on the cover body. When installing the cover body, the two groups of the gas flow channels respectively cover two groups of detection elements and heating elements, so that two groups of detection units can be constructed, one group of the detection units can be used for small gas flow detection, and the other group of detection units can be used for large gas flow detection.

8. The gas mass flow sensor processing method according to claim 7, characterized in that: The gas mass flow sensor processing method, when processing the cover body, is also provided with a process for processing and manufacturing a second insulation cavity between the two groups of the gas flow channels. After the two groups of the gas flow channels and the second insulation cavity are processed and manufactured, the cover body including the second insulation cavity is installed on the top surface of the base plate, and the sealing plates are installed on both ends of the second insulation cavity and sealed to construct a second thermal isolation structure.

9. The gas mass flow sensor processing method according to claim 8, characterized in that: The gas mass flow sensor processing method, when processing and manufacturing the second thermal insulation cavity on the cover body blank, also provides a process for grinding and polishing the sealing part of the inner wall of the second thermal insulation cavity to ensure the sealing of the second thermal isolation structure and enhance the thermal insulation effect.

10. The gas mass flow sensor processing method according to claim 1, characterized in that: The processing method of the cleaning chip is as follows: Providing a cleaning chip substrate for making a cleaning chip, and performing activation treatment on the surface to be coated of the cleaning chip substrate; Evenly coating a second photoresist film layer on the surface to be coated of the clean chip substrate; The clean electrode is manufactured by combining exposure, development, magnetron sputtering and stripping processes; forming a second electrical lead film and a second terminal on the clean chip substrate; After the clean electrode, the second electrical lead film and the second terminal have been manufactured, alloying treatment is performed; After the alloying treatment, a third polyimide insulating layer is formed on the clean chip substrate to cover the clean electrode and the second electrical lead film to complete the manufacture of the clean chip; A cleaning chip is mounted on the surface of the cover plate facing away from the base plate to construct an autonomous sensor contamination cleaning system consisting of the cleaning chip, the main gas channel and the auxiliary gas channel.

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