Fabrication process of a silicon-based microchannel throttling device

Abstract

This invention discloses a fabrication process for a silicon-based microchannel throttling device, comprising the following steps: S1, etching a silicon-based channel layer on a wafer; S2, fabricating through-holes corresponding to the inlet and outlet of the silicon-based channel on a glass cover plate; S3, positioning and aligning the etched silicon wafer with the perforated glass cover plate, and bonding the silicon wafer-glass stack; S4, depositing Ti / Au on the upper surface of the bonded glass, and then dividing the wafer into individual throttling chip pieces; S5, fabricating a metal casing with interfaces, and fabricating cavities inside the metal casing to house the throttling chip; S6, soldering and fixing the throttling chip inside the metal casing, and placing a heating film with a temperature sensor on the lower surface of the throttling chip. This invention features high reliability, high consistency, and high precision, solving the problem of coexistence of three materials with vastly different properties—silicon, glass, and metal—in the same device.

Description

Technical Field

[0001] This invention relates to the field of flow regulator technology, and more specifically to a fabrication process for a silicon-based microchannel flow regulator. Background Technology

[0002] Due to the urgent need for precise, stable, and miniaturized fluid control systems in modern industry, and based on the engineering application of classical fluid mechanics at the microscale, and with the maturity of MEMS micromachining technology, microchannel throttles have developed rapidly. Essentially, they are passive components that utilize tiny flow channels to generate significant and controllable fluid resistance (flow resistance). This represents an important trend in fluid control technology, moving from macroscopic mechanical regulation to microscopic, integrated, and intelligent approaches. The core technological challenge has shifted from "manufacturing capability" to achieving perfect fidelity and batch consistency of flow channel geometry under demanding environments (such as high pressure and high temperature). This is precisely the key problem that next-generation manufacturing processes (such as silicon-based MEMS) need to solve.

[0003] Based on these advantages, microchannel throttling devices have become irreplaceable key components in many high-precision fields:

[0004] Aerospace: Providing extremely stable and precise flow control of working fluids (such as xenon) for micro-thrusters in satellite propulsion systems. Analytical Instruments: Serving as a split / splitless injection controller for chromatographic columns in gas chromatographs (GC) to ensure analytical accuracy. Medical Devices: Achieving precise and quiet gas delivery in portable ventilators and anesthesia machines. Semiconductor Equipment: Delivering precise flow rates of specialty gases (such as krypton and argon) to process chambers in etching, deposition, and other equipment.

[0005] Currently, in the pursuit of higher precision and reliability, microchannel throttling devices mainly face technical challenges at multiple levels, including manufacturing processes and material selection.

[0006] Channel deformation and dimensional consistency: In the fabrication of metal microchannels, subsequent packaging processes such as diffusion bonding need to be carried out under high temperature and pressure, which can easily lead to the collapse or deformation of micron-sized channels. Because the channel size itself is very small, the absolute amount of deformation may not be large, but the relative amount of deformation is large. This will directly lead to significant differences in flow resistance performance between different devices, making it difficult to guarantee consistency.

[0007] Manufacturing defects and stress concentration: During microchannel fabrication, minute defects or abrupt changes in geometry within the equipment can become sources of stress concentration. This stress concentration accelerates material damage and affects the long-term reliability of the flow regulator.

[0008] Material Corrosion and Long-Term Stability: Microchannel throttling devices may face highly corrosive operating environments when handling various media. This poses a serious challenge to the long-term stability of the materials. For example, special attention needs to be paid to stress corrosion caused by highly toxic substances such as chlorination and fluorination.

[0009] Heterogeneous Material Encapsulation and Leakage Prevention: To achieve specific functions (such as protection, heat dissipation, or interface), microchannel throttling devices often employ multiple materials for encapsulation and integration. However, preventing leakage when bonding heterogeneous materials is a key technical challenge, especially under long-term operation, where the reliability of the interface faces severe tests.

[0010] Structural-functional integration of materials: In some designs, materials not only need to form flow channels, but may also bear the mechanical function of preventing warping and deformation of chips or internal structures. This requires materials to possess sufficient structural strength in addition to meeting properties such as corrosion resistance and ease of processing. Summary of the Invention

[0011] The technical problem to be solved by this invention is to address the shortcomings of existing microchannel throttling device manufacturing technologies, such as poor channel geometry accuracy and consistency, large process thermal stress and residual stress, extremely difficult inspection and maintenance, limitations in material selection and functional integration, long design iteration cycle and high cost. The invention provides a manufacturing process for silicon-based microchannel throttling devices that can be mass-produced, has no channel deformation, and exhibits high consistency and high precision.

[0012] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0013] A fabrication process for a silicon-based microchannel throttling device includes the following steps:

[0014] Step S1: Etch and fabricate a silicon-based flow channel layer on the wafer;

[0015] Step S2: Process through holes on the glass cover plate that correspond to the inlet and outlet of the silicon-based flow channel;

[0016] Step S3: Position and align the etched silicon wafer obtained in step S1 with the perforated glass cover plate obtained in step S2, and bond the silicon wafer-glass stack.

[0017] Step S4: Ti / Au are deposited on the upper surface of the bonded glass cover, and then the wafer is divided into individual throttle chips;

[0018] Step S5: Process and manufacture a metal substrate with a connector, and process a cavity inside the metal substrate to place the throttle chip;

[0019] Step S6: Weld the upper surface of the throttle chip to the inside of the metal substrate, and set a heating film with a temperature sensor on the lower surface of the throttle chip; thus, the fabrication of the silicon-based microchannel throttle is completed.

[0020] As a further improvement of the present invention, step S1 further includes:

[0021] Step S11: Clean the wafer surface thoroughly;

[0022] Step S12: Spin-coat photoresist onto the silicon wafer, use a mask with spiral / serpentine flow channels for ultraviolet exposure, use the photoresist as a mask to transfer the flow channel pattern onto the photoresist;

[0023] Step S13: Using the Bosch process, microchannels are formed by inductively coupled plasma etching, and high aspect ratio silicon etching is achieved through alternating passivation and etching cycles.

[0024] Step S14: Remove residual photoresist and clean the flow channels.

[0025] As a further improvement of the present invention, in step S13, a flow channel with a depth of 30 to 100 μm and a sidewall inclination angle of 88° to 90° is etched.

[0026] As a further improvement of the present invention, in step S2, borosilicate glass that matches the thermal expansion coefficient of silicon is selected as the glass cover.

[0027] As a further improvement of the present invention, in step S3, the silicon wafer-glass stack is placed in a bonding machine and heated to 350-400°C, and a DC voltage of 200-1000V is applied between the silicon wafer and the glass to achieve anodic bonding between the silicon wafer and the glass.

[0028] As a further improvement of the present invention, in step S5, gold is plated on the upper surface of the cavity inside the metal substrate.

[0029] As a further improvement of the present invention, in step S6, high-temperature solder is used as solder. The solder is applied to the bonding glass surface of the throttle chip through an automatic printing system, and then aligned with the metal substrate and soldered at high temperature.

[0030] As a further improvement of the present invention, after the glass is welded and fixed to the metal substrate, a sealant is applied to the outer layer of the metal substrate and the silicon wafer.

[0031] As a further improvement of the present invention, in step S6, the heating film is made of polyimide, and the heating film contains a heating film resistor and a platinum resistance temperature sensor.

[0032] As a further improvement of the present invention, the shape of the heating film resistor is consistent with the flow channel, and voltage is applied to both ends of the heating film through positive and negative terminals.

[0033] Compared with the prior art, the advantages of the present invention are as follows:

[0034] The fabrication process of the silicon-based microchannel throttling device of this invention combines MEMS technology from the semiconductor industry, throttling technology from the microfluidics field, and the reliability of metal packaging from the mechanical field. This enables the etching of ultra-long, small-section flow channels on a silicon wafer, generating significant flow resistance to the passing gas, thereby achieving precise pressure drop from a high-pressure inlet to a low-pressure outlet. Furthermore, by using a heating film and temperature sensor attached to the lower surface of the silicon wafer, the entire flow channel is heated. By changing the gas temperature, its viscosity can be adjusted, thereby dynamically fine-tuning the flow resistance and achieving precise control of the flow rate or outlet pressure. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the fabrication process of the silicon-based microchannel throttling device in a specific embodiment of the present invention;

[0036] Figure 2 This is a front view of the silicon wafer flow channel in a specific embodiment of the present invention;

[0037] Figure 3 This is a schematic diagram of the bonding process between the silicon wafer and the glass cover plate in a specific embodiment of the present invention;

[0038] Figure 4 This is a schematic diagram of wafer dicing in a specific embodiment of the present invention;

[0039] Figure 5 This is a schematic diagram of the overall structure of the microchannel throttling device in a specific embodiment of the present invention.

[0040] Legend: 1. Silicon wafer; 101. Flow channel; 102. Inlet; 103. Outlet; 2. Glass cover plate; 3. Metal substrate; 4. Heating film; 5. Heating film resistor; 6. Connector; 7. Sealant. Detailed Implementation

[0041] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention.

[0042] In the description of this invention, it should be understood that the terms "side", "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0043] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more unless otherwise explicitly specified.

[0044] The emergence of microchannel flow regulators stems from the growing demand for precise fluid control. The basic principle of flow regulators is Poiseuille flow, that is, in laminar flow, when a fluid passes through a channel with a constant cross-section, its pressure drop (ΔP) is proportional to the flow rate (Q), fluid viscosity (μ), and channel length (L), and is also proportional to the fourth power of the channel's hydraulic diameter (D). h 4 It is inversely proportional to . Its simplified relationship is:

[0045]

[0046] The above formula reveals the core technical logic of the microchannel throttling device: (1) The pressure drop is inversely proportional to the fourth power of the channel diameter. This means that by reducing the channel size from millimeters to micrometers, even if the channel is very short, it can generate extremely large flow resistance, thereby achieving a small outlet pressure from high pressure to near vacuum; (2) To obtain high flow resistance, one can increase the length (make it into a spiral or serpentine shape) or reduce the cross-section.

[0047] Example

[0048] like Figure 1 As shown, the fabrication process of the silicon-based microchannel throttling device of the present invention includes the following steps:

[0049] Step S1: Etch and fabricate the silicon-based flow channel layer on the wafer, such as... Figure 2 As shown.

[0050] Step S2: Select borosilicate glass (such as Pyrex 7740) with a coefficient of thermal expansion matching that of silicon as the glass cover plate to ensure that the interface between the silicon wafer and the glass will not crack due to excessive thermal stress during the anodic bonding process and subsequent -160°C thermal cycling. Then, process through holes on the glass cover plate corresponding to the inlet 102 and outlet 103 of the flow channel 101.

[0051] Step S3: Precisely position and align the etched silicon wafer obtained in step S1 with the perforated glass cover plate obtained in step S2, and perform anodic bonding of the silicon wafer-glass stack, such as... Figure 3 As shown. In this embodiment, before bonding, a confocal microscope or white light interferometer is used to measure the three-dimensional morphology of the etched flow channel 101; after the device is manufactured, non-destructive three-dimensional imaging and dimensional measurement of the internal structure of the sealed flow channel can be achieved by any X-ray micro-CT (micro-CT) inspection method; thus realizing full-process quality monitoring and early detection of problems.

[0052] Anodic bonding is a wafer-level parallel manufacturing process that bonds an entire silicon wafer to a glass sheet in a single operation under the same conditions. Provided the photolithography and etching precision is consistent, all flow channels fabricated on the same wafer will have highly uniform geometry and dimensions. Using photolithography-based MEMS (DRIE) processes for flow channel fabrication inherently offers extremely high repeatability. Therefore, this embodiment achieves unparalleled device-to-device performance consistency and high yield, making it particularly suitable for mass production.

[0053] Step S4: Using ion beam deposition, Ti / Au is deposited on the upper surface of the bonded glass cover plate. The wafer is then divided into individual throttling chips, such as... Figure 4 As shown. A single throttle chip is used for further soldering and sealing to a metal substrate with a connector.

[0054] Step S5: Fabricate a stainless steel metal substrate 3 with connector 6, and machine a cavity inside the metal substrate 3 to place the throttle chip. Gold is plated onto the upper surface of the cavity. The connector 6 of the metal substrate 3 is welded to the inlet 102 and outlet 103 of the throttle chip. The connector 6 can be further connected to a miniature piezoelectric pump / valve by welding.

[0055] In practical applications, microfluidic throttling devices require thermal throttling control over a wide temperature range (e.g., 0°C to 160°C). Therefore, a mechanical structure is needed that is both thermally conductive and allows for easy heater installation, while also being able to withstand high temperatures. In this embodiment, a metal substrate is used as a protective layer and integrated with the silicon-glass chip via welding. Silicon is a good thermal conductor and an ideal substrate for heat spreaders and heaters. The metal provides robust mechanical protection for the brittle silicon-glass chip, and it is also easy to fabricate standard fluid interfaces. Therefore, the microfluidic throttling device in this embodiment achieves robust mechanical protection, efficient thermal management, and convenient system integration, providing an ideal platform for intelligent thermal throttling control.

[0056] Step S6: The upper surface of the throttle chip is soldered and fixed inside the metal substrate 3, and a heating film with a temperature sensor is placed on the lower surface of the throttle chip; thus, the fabrication of the silicon-based microchannel throttle is completed, and the obtained product is as follows. Figure 5 As shown.

[0057] This embodiment of the silicon-based microchannel throttling device employs a silicon-glass-metal composite structure. The core functional area is handled by a silicon / glass MEMS chip, ensuring precision. The outer metal substrate provides mechanical protection and integrates interfaces, while the heater is attached to the bottom of the silicon wafer. This composite structure combines the precision of MEMS with the robustness of metal. The purpose of this invention is to advance microchannel throttling device technology towards "MEMSization," "intelligentization," and "integration," utilizing the precision manufacturing concepts of the semiconductor industry and employing silicon-based MEMS processes to address the pain points of existing technologies and achieve a leap in performance.

[0058] Step S1 in this embodiment further includes:

[0059] Step S11, Silicon Wafer Cleaning: Prepare the wafer and use the standard RCA cleaning process to ensure that the wafer surface is free of contamination.

[0060] Step S12, Photolithography: Spin-coat photoresist onto the silicon wafer, use a mask with spiral / serpentine flow channels for ultraviolet exposure, use the photoresist as a mask to transfer the flow channel pattern onto the photoresist.

[0061] Step S13, Deep Reactive Ion Etching (DRIE): Using Bosch technology, microchannels are formed through inductively coupled plasma (ICP) etching. High aspect ratio silicon etching is achieved through alternating passivation (introducing gases such as C4F8) and etching (introducing gases such as SF6) cycles. For example... Figure 1As shown, flow channels 101 with a depth of 10–300 μm and vertical sidewalls are etched on silicon wafer 1, along with inlet 102 and outlet 103. To prevent damage to the front side of the chip, a fixture is used for protection. After etching, the flow channel 101 is approximately rectangular in shape, with sidewall angles ranging from 88° to 90° and a slight curvature at the bottom. The lateral dimensional accuracy of the flow channel 101 is controlled within ±0.1 µm. After optimization of the process parameters, the depth dimensional accuracy of the flow channel 101 is controlled within ±1 µm. The bottom of the flow channel 101 exhibits approximately a 3% thickness deviation depending on the etching depth (more etching in the middle and less on the sides). The surface roughness of the flow channel is approximately 50 nm, which can be further polished to <20 nm.

[0062] Step S14, Resin Removal and Cleaning: Remove residual photoresist and clean the flow channels.

[0063] In step S3 of this embodiment, the silicon wafer-glass laminate is placed in a bonding machine and heated to 350–400°C. A DC voltage of 200–1000V is applied between the silicon wafer and the glass. Under the influence of the electric field and temperature, sodium ions in the glass migrate, forming a very strong electrostatic force at the glass-silicon interface, forming permanent, hermetically sealed chemical bonds (Si-O-Si), thereby forming closed microchannels. The through-holes in the glass cover plate become the inlet and outlet of the fluid, such as… Figure 3 As shown, the bonding temperature is much lower than the softening point of silicon and the diffusion bonding temperature of metals. Moreover, the process does not require the application of macroscopic mechanical pressure, which fundamentally eliminates channel deformation and achieves extremely high geometrical fidelity.

[0064] In this embodiment, the flow channel is processed using deep reactive ion etching (DRIE) technology on a silicon wafer, and then sealed with a glass cover plate by anodic bonding. This has the following advantages: (1) The DRIE process can achieve submicron-level size control, perfectly maintaining the flow channel geometry; (2) Anodic bonding is performed at a lower temperature (<450℃) and voltage, so the silicon wafer and flow channel structure will not undergo plastic deformation or collapse due to thermal softening or thermal stress, preserving the original geometry after etching; (3) Based on photolithography, the device performance is highly consistent; (4) The bonding interface between the silicon wafer and the glass cover plate is transparent, allowing for direct optical inspection after bonding. Choosing glass as the cover plate material enables visualization of the manufacturing process, allows for non-destructive flow channel quality inspection, solves the "black box" problem, and greatly improves the speed of process development and quality control capabilities.

[0065] In step S6 of this embodiment, high-temperature solder is used as the solder. The solder is applied to the bonding glass surface of the throttling chip using an automatic printing system, or the solder pad is placed on the surface of the throttling chip, and then aligned with the metal substrate for high-temperature soldering. The soldering temperature is controlled at around 300°C. Stress is absorbed by using a solder / flexible adhesive (such as epoxy resin with a certain degree of elasticity), and the adhesive layer thickness is optimized to both transfer heat and buffer stress. After soldering, the solder seal is checked. Once the seal performance meets the requirements, a layer of high-temperature resistant sealant 7 is applied to the outer layer of the metal substrate 3 and the silicon wafer 1, such as... Figure 5 As shown. High-temperature resistant epoxy resin can be used as the sealant for mechanical protection and to enhance sealing, ensuring that the "silicon-glass" and "glass-metal / interface" interfaces remain absolutely sealed under high-pressure gas and temperature changes.

[0066] In this embodiment, methods such as gold-tin bonding, silicon-silicon bonding, and anodic bonding are used instead of traditional high-temperature diffusion bonding to reduce the process temperature and minimize the thermal impact. While retaining the overall structural advantages of the metal substrate 3, deformation of the flow channel 101 is minimized. In addition, high-temperature sealant is uniformly applied around the metal substrate 3 and the silicon wafer 1 to enhance the structure's shock absorption and sealing performance.

[0067] In step S6 of this embodiment, silicon has a high thermal conductivity, approximately ten times that of stainless steel. Considering the rate of heat transfer, it is more suitable to mount the heating film 4 onto the lower surface of the silicon wafer 1. A layer of thermally conductive adhesive is coated on the lower surface of the silicon wafer 1, and then the heating film 4 is aligned and mounted onto the lower surface of the silicon wafer 1. The heating film 4 is made of polyimide, and a heating film resistor 5 and a platinum resistance temperature sensor (not shown in the figure) are encapsulated inside the heating film 4. Furthermore, the shape of the heating film resistor is consistent with the flow channel, and voltage is applied to both ends of the heating film through positive and negative terminals. After the temperature controller at the back end obtains the temperature, it adjusts the heating power by adjusting the voltage / current to achieve temperature control.

[0068] In this embodiment, the layout of the heating film 4 and the temperature sensor must be optimized through thermal simulation to ensure uniform temperature throughout the flow channel area and avoid local overheating or undercooling points. The heating film 4 is tightly attached to the back or side of the silicon wafer 1, and the highly thermally conductive silicon layer is used as a "heat spreader" to uniformly transfer heat to the entire MEMS chip.

[0069] In this embodiment, a well-tuned PID control algorithm is required. The algorithm is responsible for responding quickly to temperature changes and precisely adjusting the heating power to counteract the thermal disturbances caused by fluctuations in ambient temperature and changes in working gas flow rate, thereby stabilizing the flow channel temperature (i.e., gas viscosity) at the set value and achieving precise dynamic control of flow resistance.

[0070] Thermal throttling control is a back-end closed-loop feedback system, and its core components are as follows:

[0071] The temperature sensor embedded in the heating diaphragm 4 is a Pt100 platinum resistance thermometer, whose resistance value has a precise and linear relationship with temperature change.

[0072] Signal conditioning circuit: Converts the minute resistance changes of the Pt100 platinum resistance into a voltage signal, and then amplifies and filters it.

[0073] Microprocessor (such as ARM Cortex-M or ESP32): Reads the conditioned temperature and voltage values; runs the PID control algorithm to calculate the control quantity.

[0074] Power drive circuit: Using MOSFETs, the current / voltage through the heating diaphragm 4 is controlled according to the PID output, thereby precisely controlling the heating power.

[0075] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A fabrication process for a silicon-based microchannel throttling device, characterized in that, Includes the following steps: Step S1: Etch and fabricate a silicon-based flow channel layer on the wafer; Step S2: Process through holes on the glass cover plate that correspond to the inlet and outlet of the silicon-based flow channel; Step S3: Position and align the etched silicon wafer obtained in step S1 with the perforated glass cover plate obtained in step S2, and bond the silicon wafer-glass stack. Step S4: Ti / Au are deposited on the upper surface of the bonded glass cover, and then the wafer is divided into individual throttle chips; Step S5: Process and manufacture a metal substrate with a connector, and process a cavity inside the metal substrate to place the throttle chip; Step S6: Weld the upper surface of the throttle chip to the inside of the metal substrate, and set a heating film with a temperature sensor on the lower surface of the throttle chip. This completes the fabrication of the silicon-based microchannel throttling device.

2. The fabrication process of the silicon-based microchannel throttling device according to claim 1, characterized in that, Step S1 further includes: Step S11: Clean the wafer surface thoroughly; Step S12: Spin-coat photoresist onto the silicon wafer, use a mask with spiral / serpentine flow channels for ultraviolet exposure, use the photoresist as a mask to transfer the flow channel pattern onto the photoresist; Step S13: Using the Bosch process, microchannels are formed by inductively coupled plasma etching, and high aspect ratio silicon etching is achieved through alternating passivation and etching cycles. Step S14: Remove residual photoresist and clean the flow channels.

3. The fabrication process of the silicon-based microchannel throttling device according to claim 2, characterized in that, In step S13, a flow channel with a depth of 30-100 μm and a sidewall inclination angle of 88°-90° is etched.

4. The fabrication process of the silicon-based microchannel throttling device according to any one of claims 1 to 3, characterized in that, In step S2, borosilicate glass with a coefficient of thermal expansion matching that of silicon is selected as the glass cover.

5. The fabrication process of the silicon-based microchannel throttling device according to any one of claims 1 to 3, characterized in that, In step S3, the silicon wafer-glass stack is placed in a bonding machine and heated to 350-400°C. A DC voltage of 200-1000V is applied between the silicon wafer and the glass to achieve anodic bonding between the silicon wafer and the glass.

6. The fabrication process of the silicon-based microchannel throttling device according to any one of claims 1 to 3, characterized in that, In step S5, gold is plated on the upper surface of the cavity inside the metal substrate.

7. The fabrication process of the silicon-based microchannel throttling device according to any one of claims 1 to 3, characterized in that, In step S6, high-temperature solder is used as the solder. The solder is applied to the bonding glass surface of the throttle chip through an automatic printing system, and then aligned with the metal substrate and soldered at high temperature.

8. The fabrication process of the silicon-based microchannel throttling device according to claim 7, characterized in that, After the glass is welded and fixed to the metal substrate, sealant is applied to the outer layer of the metal substrate and the silicon wafer.

9. The fabrication process of the silicon-based microchannel throttling device according to claim 6, characterized in that, In step S6, the heating film is made of polyimide, and a heating film resistor and a platinum resistance temperature sensor are encapsulated inside the heating film.

10. The fabrication process of the silicon-based microchannel throttling device according to claim 9, characterized in that, The shape of the heating film resistor is consistent with the flow channel, and voltage is applied to both ends of the heating film through positive and negative terminals.

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