A gas mass flow feedback control system and method

Abstract

This application provides a gas mass flow feedback control system and method, applied to a gas mass flow controller. The system includes: a pipeline signal acquisition module for acquiring the actual pressure and temperature signals of the pipeline under test; a calibration module including a calibration tank of known volume, for acquiring the calibration pressure and calibration temperature signals of the calibration pipeline; and a control module connected to the pipeline signal acquisition module and the calibration module, for calculating the gas mass flow measurement value based on the actual pressure, actual temperature, calibration pressure, and calibration temperature signals, and generating a flow mapping relationship based on the gas mass flow measurement value and the target value of the pipeline under test, which is then fed back to the gas mass flow controller to ensure gas flow consistency.

Description

Technical Field

[0001] This application relates to the field of gas mass flow control technology, specifically to a gas mass flow feedback control system and method. Background Technology

[0002] In semiconductor manufacturing, precise gas supply to the gas reaction chamber is a crucial step in achieving high-precision control of related processes. Therefore, the accuracy of gas flow control is paramount—flow control errors will affect the quality of the final wafer. Typically, this is controlled by a mass flow controller (MFC), a high-precision instrument used to accurately measure and control the mass flow rate of gas (or liquid). It can automatically, quickly, and accurately adjust and stabilize the flow rate at the user-defined target value.

[0003] However, different MFCs may come from different suppliers, such as gas sources He, H2, and O2. The gas flow rate controlled by the corresponding MFCs may have different degrees of error (i.e., there are individual differences between MFCs supplied with different gas sources, resulting in significant deviations between the actual flow rate and the set value, and the deviations vary). This leads to differences in the consistency of gas mass flow rate across different machines, different gas reaction chambers, and different gas paths. In semiconductor processes, the accumulation of errors at different stages can be further amplified in the back-end stages, thus significantly affecting the final wafer quality.

[0004] Therefore, there is an urgent need for a gas mass flow feedback control mechanism that can be uniformly calibrated across gas sources and equipment to ensure the consistency of gas flow between different gas sources and different MFCs, thereby ensuring process stability. Summary of the Invention

[0005] This application provides a gas mass flow feedback control system and method, which aims to solve the problem of poor gas mass flow consistency caused by different equipment in the prior art.

[0006] A gas mass flow feedback control system is applied to an external mass flow controller for the gas to be controlled, the system comprising: The pipeline signal acquisition module is used to acquire the actual pressure signal and actual temperature signal of the pipeline under test; The calibration module includes a calibration vessel of known volume, and the calibration module is used to acquire calibration pressure signals and calibration temperature signals of the calibration pipeline; The control module is connected to the pipeline signal acquisition module and the calibration module respectively. It is used to calculate the gas mass flow rate measurement value based on the volume of the calibration tank, the actual pressure signal, the actual temperature signal, the calibration pressure signal, and the calibration temperature signal. It also generates a flow rate mapping relationship based on the gas mass flow rate measurement value and the target value of the pipeline to be tested and feeds it back to the gas mass flow rate controller to be controlled. The generation of the flow mapping relationship specifically includes: within a preset mass flow range, dividing the preset mass flow range into multiple continuous segments according to characteristic flow points, and determining the scale value of each segment as the target value of that segment; acquiring multiple signal data groups for each segment, wherein each signal data group includes an actual pressure signal, an actual temperature signal, a calibration pressure signal, and a calibration temperature signal; determining the measured value of each signal data group based on the volume of the calibration tank, the actual pressure signal, the actual temperature signal, the calibration pressure signal, and the calibration temperature signal; and constructing the flow mapping relationship based on the measured values ​​and the target value of each continuous segment.

[0007] In some possible embodiments, the gas mass flow feedback control system further includes a host computer module; The host computer module is used to generate gas mass flow control commands based on the gas mass flow measurement value and the flow mapping relationship.

[0008] In some possible embodiments, the control module further includes a back-end valve control component, which is used to generate a back-end valve flow mapping relationship corresponding to a valve based on the gas mass flow measurement value in the pipeline corresponding to the different valves.

[0009] In some possible embodiments, the back-end valve control component includes a back-end valve control submodule and a gated valve control submodule; The back-end valve control submodule is used to generate corresponding pipeline opening and closing adjustment commands based on the flow mapping relationship of back-end valves in different pipelines. The gate valve control submodule is used to generate corresponding gas path switching commands according to the gas path switching requirements.

[0010] In some possible embodiments, the gas mass flow feedback control system further includes a gas source valve sub-control module, which is linked with the pipeline signal acquisition module through a switch linkage control structure to form a switch linkage control loop; The gas source valve secondary control module is used to trigger the switch linkage control loop to perform a shutdown action when the pressure signal of the pipeline under test is greater than the preset pressure threshold, so as to shut down the mass flow controller of the gas to be controlled.

[0011] In some possible embodiments, both the pipeline signal acquisition module and the calibration module include a resistance temperature detector and a pressure gauge.

[0012] A gas mass flow rate feedback control method, applied to a gas mass flow rate controller, includes: Collect the actual pressure and temperature signals of the pipeline under test; Collect calibration pressure and temperature signals from the calibration pipeline in a calibration vessel of known volume; The gas mass flow rate measurement value is calculated based on the volume of the calibration tank, the actual pressure signal, the actual temperature signal, the calibration pressure signal, and the calibration temperature signal. A flow rate mapping relationship is generated based on the gas mass flow rate measurement value and the target value of the pipeline under test and fed back to the gas mass flow rate controller to be controlled. The generation of the flow mapping relationship specifically includes: within a preset mass flow range, dividing the preset mass flow range into multiple continuous segments according to characteristic flow points, and determining the scale value of each segment as the target value of that segment; acquiring multiple signal data groups for each segment, wherein each signal data group includes an actual pressure signal, an actual temperature signal, a calibration pressure signal, and a calibration temperature signal; determining the measured value of each signal data group based on the volume of the calibration tank, the actual pressure signal, the actual temperature signal, the calibration pressure signal, and the calibration temperature signal; and constructing the flow mapping relationship based on the measured values ​​and the target value of each continuous segment.

[0013] In some possible embodiments, determining the measured value of each signal data group based on the volume of the calibration vessel, the actual pressure signal, the actual temperature signal, the calibration pressure signal, and the calibration temperature signal includes: Based on the ideal gas law, the volume of the calibration vessel, the actual pressure signal, the actual temperature signal, the calibration pressure signal, and the calibration temperature signal are converted into data to obtain the measured value of each signal data group.

[0014] In some possible embodiments, constructing the traffic mapping relationship based on the measured value and the target value for each consecutive segment includes: A flow mapping relationship is established between the measured value and the target value for each segment; The traffic mapping relationship is a piecewise function.

[0015] In some possible embodiments, establishing a traffic mapping relationship between the measured value and the target value for each segment includes: Based on the measured values ​​and the target values, a scatter plot is constructed and a linear mapping function is fitted. The linear mapping function is determined to be the flow mapping relationship.

[0016] This application provides a gas mass flow feedback control system and method. The system acquires the actual pressure and temperature signals in the pipeline in real time through a pipeline signal acquisition module, and then uses a calibration module with a calibration tank of known volume to acquire the calibration pressure and temperature signals of the calibration pipeline. Finally, the control module determines the measured gas mass flow rate in the pipeline in real time based on the actual pressure signal, actual temperature signal, calibration pressure signal, calibration temperature signal, and the volume of the calibration tank. Mapping the measured gas mass flow rate with the target value of the pipeline under test determines the flow rate mapping relationship. Finally, during the flow control process of the gas mass flow controller based on the flow rate mapping relationship, since the calibration tank is an independent calibration unit uniformly set by the gas mass flow feedback control system, this flow rate mapping relationship ensures that the gas mass flow controller obtains consistent reference flow rate response characteristics under the same calibration conditions. This ensures that the gas mass flow rate of different devices is synchronously and stably maintained at their respective set values, thus ensuring the consistency of gas flow rate between different gas sources and different gas mass flow controllers under test. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is an architectural diagram of an embodiment of the gas mass flow feedback control system provided in this application; Figure 2a A schematic diagram of a structure of an embodiment of the gas mass flow feedback control system provided in this application; Figure 2b A schematic diagram of the piping space and component connections in the gas mass flow feedback control system provided in this application; Figure 3 A schematic flowchart of an embodiment of the gas mass flow rate feedback control method provided in this application; Figure 4 A schematic diagram showing the result of an embodiment of the mapping relationship provided in this application. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0020] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not 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 application. 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 indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0021] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0022] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0023] The following disclosure provides many different embodiments or examples for implementing different structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. Of course, these are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or reference letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, various specific examples of processes and materials are provided in this application, but those skilled in the art will recognize the application of other processes and / or the use of other materials. This application provides a gas mass flow feedback control system and method, which will be described in detail below with reference to the accompanying drawings: Please refer to Figure 1 , Figure 1 This is a schematic diagram of an embodiment of the gas mass flow feedback control system provided in this application. The gas mass flow feedback control system provided in this application is applied to the mass flow controller of the gas to be controlled. The gas mass flow feedback control system 100 specifically includes: The pipeline signal acquisition module 101 is used to acquire the actual pressure signal and actual temperature signal of the pipeline under test. The calibration module 102 includes a calibration vessel of known volume. The calibration module 102 is used to acquire the calibration pressure signal and calibration temperature signal of the calibration pipeline. The control module 103 is connected to the pipeline signal acquisition module 101 and the calibration module 102 respectively. It is used to calculate the gas mass flow rate measurement value based on the volume of the calibration tank, the actual pressure signal, the actual temperature signal, the calibration pressure signal, and the calibration temperature signal. It also generates a flow rate mapping relationship based on the gas mass flow rate measurement value and the target value of the pipeline to be measured and feeds it back to the gas mass flow rate controller to be controlled. The generation of the flow mapping relationship specifically includes: within a preset mass flow range, dividing the preset mass flow range into multiple continuous segments according to characteristic flow points, and determining the scale value of each segment as the target value for that segment; acquiring multiple signal data groups for each segment, wherein each signal data group includes an actual pressure signal, an actual temperature signal, a calibration pressure signal, and a calibration temperature signal; determining the measured value of each signal data group based on the volume of the calibration tank, the actual pressure signal, the actual temperature signal, the calibration pressure signal, and the calibration temperature signal; and constructing a flow mapping relationship based on the measured values ​​and the target value of each continuous segment.

[0024] It should be noted that the gas mass flow controller to be controlled is any industrial device that requires precise control of gas mass flow. It is an external device that exists independently of the gas mass flow feedback control system. It can be a gas mass flow controller, such as a gas source distribution system in semiconductor manufacturing, a gas supply unit in a biopharmaceutical reactor, or a protective gas regulating valve in precision welding equipment, etc. There are no restrictions here.

[0025] Furthermore, in this embodiment, the gas mass flow controller is used in the gas flow delivery system of semiconductor process equipment such as etching machines, ion implantation equipment, and thin film deposition equipment to regulate the output gas mass flow rate.

[0026] The pipeline signal acquisition module 101 is a device used to measure the dynamic pressure and temperature parameters of the gas in the pipeline that needs to be controlled in the mass flow controller of the gas to be controlled in real time. Only by obtaining the pressure and temperature data under the actual working conditions of the mass flow controller of the gas to be controlled can a reliable basis be provided for the accurate calculation of the mass flow rate.

[0027] The calibration module 102 is a core auxiliary component for achieving accurate flow measurement and serves as a standard comparison benchmark for flow calculation. Specifically, by acquiring the calibration pressure and temperature signals of the calibration pipeline, the calibration module 102 includes a calibration tank of known volume. Therefore, based on the ideal gas law and the principle of mass conservation, the standard value of gas mass flow rate in the calibration pipeline can be determined.

[0028] The gas mass flow rate measurement value is a key parameter that reflects the actual mass flow rate of gas in the pipeline under test.

[0029] The control module 103 is the core data processing unit of the system. It is responsible for performing data fusion calculations on the actual pressure and temperature signals and calibration pressure and temperature signals collected by combining the volume of the calibration tank. Based on the ideal gas law, it derives the gas mass flow rate measurement value of the pipeline under test, and then determines the flow mapping relationship between the gas mass flow rate measurement value and the target value of the pipeline under test. Finally, in order to facilitate the automatic control of the external gas mass flow controller, it also feeds back the flow mapping relationship to the gas mass flow controller.

[0030] The gas mass flow controller is a self-regulating intelligent actuator that automatically adjusts its internal control parameters based on the received flow mapping relationship, thereby dynamically correcting the output gas mass flow rate and ensuring that the deviation between the actual measured value and the target value is always controlled within ±0.5%FS. Specifically, since there is a one-to-one correspondence between the measured value and the target value for a given pipeline under test, the target value can be directly determined based on the pre-generated flow mapping relationship after obtaining the gas mass flow rate measurement value.

[0031] The preset mass flow rate range refers to the gas mass flow rate measurement range preset by the gas mass flow rate feedback control system, such as 0-100 Sccm. The purpose of the mass flow rate range is to provide a clear range for the system's flow rate measurement and control. Within this range, the system will obtain the gas mass flow rate values ​​corresponding to multiple characteristic flow points based on the pipeline pressure and temperature signals, and divide the range into multiple continuous segments according to the characteristic flow points to achieve precise and refined control of the flow rate.

[0032] Characteristic flow points are multiple key flow values ​​selected within a preset mass flow range. These values ​​divide the range into several continuous segments. By acquiring the gas mass flow measurement values ​​corresponding to these characteristic flow points, a mapping relationship between the measured value and the target value is established for each segment, thereby achieving precise control of the gas mass flow rate. For example, in a range of 0-100 Sccm, multiple characteristic flow points such as 0, 5, 10, 15, or 0, 1, 2, 3...99, 100 can be selected. That is, characteristic flow points can be equally spaced reference values, or they can be set as non-linearly distributed key thresholds based on gas characteristics or process requirements; no restrictions are placed here.

[0033] The signal data set is a pre-acquired data packet for a specific pipeline under test, used to obtain flow mapping relationships. Since the volume of the calibration tank is known and relatively fixed, the signal data set only contains four signal parameters: actual pressure signal, actual temperature signal, calibration pressure signal, and calibration temperature signal. Combined with the ideal gas law, the gas mass flow rate measurement value of the pipeline under test can be directly derived, thereby supporting the establishment and verification of the mapping relationship of each characteristic flow point.

[0034] The ideal gas law is: PV = nRT P is the gas pressure, V is the gas volume, n is the amount of substance of the gas (number of moles), T is the thermodynamic temperature (Kelvin), and R is the ideal gas constant.

[0035] Therefore, within the enclosed space, the amount of substance nR remains constant, which leads to the following: P1V1 / T1=P2V2 / T2 Wherein, P1 is the calibration pressure signal, V1 is the volume of the calibration tank, T1 is the calibration temperature signal, P2 is the actual pressure signal, T2 is the actual temperature signal, and V2 is the measured gas mass flow rate.

[0036] The flow mapping relationship is a mapping function obtained by fitting and analyzing multiple signal data sets. This mapping function can accurately characterize the dynamic relationship between the target value and the actual measured value.

[0037] The scale value of each segment refers to the standard reference flow rate value within that segment, which can accurately reflect the flow rate accuracy of that segment and thus serve as a reference benchmark for flow control within that segment.

[0038] It should be noted that in this embodiment, the actual pressure and temperature signals in the pipeline are acquired in real time by the pipeline signal acquisition module 101, and the calibration pressure and temperature signals of the calibration pipeline are acquired by the calibration module 102 with a calibration tank of known volume. Finally, the control module 103 determines the gas mass flow rate measurement value in the pipeline in real time based on the actual pressure signal, actual temperature signal, calibration pressure signal, calibration temperature signal, and the volume of the calibration tank, combined with the ideal gas state equation. Thus, by acquiring multiple sets of signal data for each segment and calculating the corresponding gas mass flow rate measurement value, a precise flow rate mapping relationship between the measured value and the target value is finally constructed and fed back to the external gas mass flow rate controller to be controlled, realizing segmented dynamic calibration and closed-loop control within the full range. Furthermore, since the calibration tank is an independent calibration unit set by the gas mass flow feedback control system and is different from the gas mass flow rate controller to be controlled, each gas mass flow rate controller to be controlled obtains consistent reference flow rate response characteristics under the same calibration conditions, thereby ensuring that the gas mass flow rate of different devices is synchronously and stably stable at their respective set values, ensuring the consistency of gas flow rate between different gas sources and different gas mass flow rate controllers to be controlled.

[0039] In one specific embodiment, when it is necessary to regulate the gas mass flow rate of a device's pipeline, the gas mass flow rate feedback control system first establishes a communication connection with the device. Based on the characteristic flow rate points reflected by the historical data of the device's pipeline, the mass flow rate range is divided into multiple continuous segments, and data is collected for each continuous segment. Specifically, this includes: acquiring the actual pressure signal and actual temperature signal in the device's pipeline; simultaneously, the gas in the device's pipeline is introduced into a calibration tank of known volume, and the calibration pressure signal and calibration temperature signal of the calibration pipeline are acquired; then, the control module 103 calculates the gas mass flow rate measurement value of the gas in the device's pipeline in real time based on the ideal gas law, combined with the calibration tank volume and the two sets of pressure and temperature signals; finally, the gas mass flow rate measurement value is mapped one-to-one with the scale value of each continuous segment to generate a flow rate mapping relationship, which is then fed back to the gas mass flow rate controller to be controlled.

[0040] Correspondingly, when the mass flow controller of the gas to be controlled performs self-regulation, it first determines the true mass flow rate corresponding to the current set value based on the flow mapping relationship. That is, it determines the offset of the mass flow controller of the gas to be controlled within the range of the current set value based on the flow mapping relationship. When the true mass flow rate is greater than the current set value, it indicates that the gas flow rate in the equipment pipeline is too high. In this case, it is necessary to reduce the gas output flow rate of the equipment so that its actual mass flow rate gradually approaches the current set value until it is completely consistent. When the true mass flow rate is less than the set value, it indicates that the gas flow rate in the equipment pipeline is too low. In this case, it is necessary to increase the gas output flow rate until the actual mass flow rate precisely matches the set value.

[0041] Specifically, when the current setting value is 1, that is, the target value is 1, the measured value A corresponding to the target value 1 can be directly determined according to the flow mapping relationship. When A is greater than 1, it means that the gas flow rate of the equipment pipeline is too high. In this case, it is necessary to reduce the gas output flow rate of the equipment so that its actual mass flow rate gradually approaches the current setting value until it is completely consistent. When A is less than 1, it means that the gas flow rate of the equipment pipeline is too low. In this case, it is necessary to increase the gas output flow rate until the actual mass flow rate accurately matches the setting value.

[0042] It should be noted that the type of mass flow controller for the gas to be controlled is not limited. It can be any actuator with flow regulation capability, such as a mass flow controller, proportional valve, electric regulating valve, or integrated gas distribution module. It can also be an old device with missing scale or blurred markings that requires external calibration. The piping can be any piping within the mass flow controller for the gas to be controlled, or it can be a branch piping connecting multiple gas sources or a mixing chamber inlet piping. There are no limitations on this.

[0043] Therefore, in this embodiment, by using the calibration tank as a unified benchmark, the limitations of relying on the accuracy of the device's own sensors are overcome, and the consistency of flow across devices and operating conditions is guaranteed. This enables high-precision gas flow collaborative control to be achieved even in semiconductor process production lines where multiple devices, especially those produced by devices from multiple suppliers, are still in operation.

[0044] It should be noted that, since the flow mapping relationship reflects the nonlinear response characteristics of the equipment under different operating conditions, and the measured value and the target value have a one-to-one correspondence, once the flow mapping relationship of the pipeline is determined, the mapping relationship between the target value and the compensation target value can be increased according to actual needs. For example, when the actual measured value corresponding to the target value of 5 is 4.8, then a compensation target value of 5.25 can be established to make the actual measured value approach 5. The setting of this compensation target value is not a nonlinear extrapolation, but is obtained by nonlinear fitting based on the historical response curve of the equipment in this operating condition range. It can be completed through the adaptive compensation algorithm built into the gas mass flow feedback control system, supporting online updates and dynamic corrections. Therefore, based on the mapping relationship between the target value and the compensation target value, once the target value is determined, the value that the mass flow controller of the gas to be controlled should be set can be directly determined, effectively improving the equipment's response efficiency.

[0045] To further meet the needs of automated flow control under different operating conditions, the gas mass flow feedback control system also includes a host computer module; the host computer module is used to generate gas mass flow control commands based on the gas mass flow measurement value and the flow mapping relationship.

[0046] The host computer module can also receive externally input process parameter commands and dynamically adjust the update frequency and calibration weight of the flow mapping relationship, so that the system can automatically adapt the calibration sensitivity and response speed in different process stages (such as etching, deposition, and cleaning), ensuring that the flow control is both accurate and efficient.

[0047] In this embodiment, by adding a host computer module, it is possible to intelligently generate precise gas mass flow control commands based on the gas mass flow measurement value and the pre-acquired flow mapping relationship, thereby realizing automated and refined regulation of gas mass flow, improving the control accuracy and response speed of the system, ensuring that the gas flow is stable within the target range, and meeting the flow control requirements under different working conditions.

[0048] When the mass flow controller of the gas to be controlled includes multiple pipelines, multiple valves need to be controlled simultaneously. In order to achieve multi-valve coordinated control, the control module 103 also includes a back-end valve control component. The back-end valve control component is used to generate the back-end valve flow mapping relationship corresponding to the valve based on the gas mass flow measurement value in the pipeline corresponding to the different valves.

[0049] When the mass flow controller of the gas to be controlled is applied to a vacuum system, and the vacuum system includes multiple gas source pipelines (H2, O2, etc.), each gas source pipeline is connected to the corresponding gas mass flow controller, and each pipeline is relatively independent, but needs to operate simultaneously. Therefore, in order to ensure the accuracy and synchronization of flow distribution between pipelines, the control module 103 performs flow mapping modeling and closed-loop control on each pipeline as an independent operating entity, thereby obtaining the flow data of each pipeline and generating the corresponding independent back-end valve flow mapping relationship.

[0050] In this embodiment, by adding a back-end valve control component, the flow mapping relationship of each pipeline's back-end valve is generated specifically based on the measured gas mass flow rate in the pipeline corresponding to different valves. Therefore, the gas mass flow controller containing multiple pipelines can independently and precisely regulate each pipeline according to the corresponding back-end valve flow mapping relationship. It can flexibly adjust the valve state according to the actual flow rate of each pipeline, thereby more effectively optimizing the gas distribution in each pipeline and improving the control accuracy, response speed, and operational stability of the entire gas mass flow feedback control system, meeting the needs for refined gas flow management under complex operating conditions.

[0051] Furthermore, when the mass flow controller for the gas to be controlled includes multiple parallel gas path channels, and at least two gas path channels are equipped with gas source valves and selector valves, the back-end valve control component includes a back-end valve control submodule and a selector valve control submodule; wherein, the back-end valve control submodule is used to generate corresponding pipeline opening and closing adjustment commands according to the back-end valve flow mapping relationship of different pipelines; the selector valve control submodule is used to generate corresponding gas path switching commands according to gas path switching requirements.

[0052] It should be noted that the back-end valve control submodule is responsible for generating precise and real-time pipeline opening and closing adjustment commands based on the flow mapping relationship of the back-end valves in each pipeline. Its control logic integrates dynamic feedback compensation and feedforward prediction mechanisms, completing command parsing and output within a millisecond response cycle. Specifically, when the back-end valve flow mapping relationship reflects a positive deviation between the target value and the compensation target value, the system activates the feedforward prediction mechanism to inject compensation in advance; when the deviation is reversed, dynamic feedback compensation is activated to correct the actuator output in real time. Thus, based on the pipeline opening and closing adjustment commands, the back-end actuator can be precisely driven to complete high-precision opening and closing adjustment actions, ensuring that the valve completes a millisecond-level response within a linearity range of ±0.15%FS.

[0053] On the other hand, the gate valve control submodule is responsible for generating accurate and real-time gas path switching commands based on gas path switching requirements. Its control logic adopts a dual-mode mechanism of state machine driving and event triggering. Under the premise of ensuring that the switching sequence strictly complies with the safety protocol, it supports millisecond-level disturbance-free switching. Specifically, when a gas path switching command is received, the gas mass flow controller to be controlled first locks the state parameters of the current operating channel, immediately enters the state machine switching process, and synchronously triggers the millisecond-level sampling of the corresponding pipeline signal acquisition module 101.

[0054] In this embodiment, by subdividing the back-end valve control component into a back-end valve control submodule and a gating valve control submodule, precise control of a gas mass flow controller containing multiple parallel gas path channels is achieved. The back-end valve control submodule generates pipeline opening and closing adjustment commands based on the flow mapping relationship of the back-end valves of different pipelines, ensuring precise adjustment of the flow of each gas path channel. The gating valve control submodule generates gas path switching commands according to the gas path switching requirements, realizing flexible switching between multiple gas path channels. This improves the control accuracy, response speed, and operational flexibility of the gas mass flow controller in complex gas path systems, meeting the comprehensive requirements of multiple gas path switching and precise flow control.

[0055] On the other hand, in order to ensure that the system can take protective measures in a timely manner under abnormal operating conditions and ensure the stable operation of the entire gas delivery and control process, the gas mass flow feedback control system also includes a gas source valve secondary control module. The gas source valve secondary control module and the pipeline signal acquisition module 101 are linked by a switch linkage control structure to form a switch linkage control loop. The gas source valve secondary control module is used to trigger the switch linkage control loop to perform a shut-off action when the pressure signal of the pipeline under test is greater than the preset pressure threshold, so as to shut down the gas mass flow controller under control.

[0056] The preset pressure threshold is set to 1.2 times the rated working pressure based on the system's safety redundancy design principle. It can also be set to other values ​​according to actual needs, which not only reserves reasonable buffer space but also avoids false triggering. The pressure signal is monitored and dynamically responded to in real time through the gas source valve sub-control module. It can cut off the gas source in milliseconds when the pressure rises abnormally, effectively preventing pipeline rupture or equipment damage.

[0057] In this embodiment, by adding a secondary control module for the gas source valve and constructing a switch-linked control loop with the pipeline signal acquisition module 101, a shutdown action can be quickly triggered to shut down the mass flow controller of the gas under control when the pressure signal of the pipeline under test exceeds the preset pressure threshold. This achieves real-time monitoring and rapid response to abnormal high pressure conditions in the pipeline, effectively avoiding safety risks such as equipment damage and gas leakage that may be caused by excessive pipeline pressure. It further improves the safety, reliability, and emergency response capabilities of the gas mass flow feedback control system, ensuring that the system can take timely protective measures under abnormal operating conditions and guaranteeing the stable operation of the entire gas delivery and control process.

[0058] Both the pipeline signal acquisition module 101 and the calibration module 102 include a resistance temperature detector and a pressure gauge.

[0059] In some embodiments, the temperature sensor in a resistance temperature detector can be a resistance temperature detector (RTD). The resistance of an RTD increases with increasing temperature and decreases with decreasing temperature. When the resistance of an RTD changes, it changes the voltage, thus the temperature change can be determined by detecting the change in voltage. More specifically, a PT100 RTD can be used for temperature detection. In PT100, "PT" stands for Platinum, and "100" indicates that the resistance of the RTD is 100 ohms at 0 degrees Celsius. The PT100 has a relatively fast thermal response time, accurately and quickly reflecting temperature changes in a short time. Furthermore, the temperature coefficient of the PT100 is very stable, meaning that the rate of change of its resistance value is relatively constant across different temperature ranges. This stability allows the PT100 to provide accurate measurement results within a temperature range of -200°C to +850°C. In addition, the PT100 RTD has excellent long-term stability; even during prolonged use, the change in its resistance value is very small.

[0060] Pressure gauges include diaphragm gauges.

[0061] Finally, to clearly understand the collaborative working mechanism of the various modules in the gas mass flow feedback control system and to ensure that the modules can operate in coordination, please refer to [link to relevant documentation]. Figure 2a and Figure 2b The first pipeline space is composed of the second, third, and fourth pipeline spaces. The target pipeline space is composed of the third and second pipeline spaces. The second pipeline space is the pipeline space formed between the second valve VAL2, the third valve VAL3, and the fourth valve VAL4. The second volume of the second pipeline space is as follows: Figure 2a and Figure 2bThe pipeline space volume V2 is shown. The third pipeline space is the pipeline space formed between the first valve VAL1 and the second valve VAL2. The third volume of the third pipeline space is as follows: Figure 2a and Figure 2b The pipeline space volume V3 is shown. The fourth pipeline space is the pipeline space formed between the output end of the gas output module and the first valve VAL1, and the fourth volume of the fourth pipeline space is shown below. Figure 2a and Figure 2b The pipeline space shown is volume V4. The reference pipeline space is the pipeline space formed between the fourth valve and the calibration vessel. The standard pipeline space is composed of the first pipeline space and the reference pipeline space. The fifth pipeline space is composed of the third pipeline space and the fourth pipeline space. The sixth pipeline space is composed of the target pipeline space and the reference pipeline space. The volume of the calibration vessel is the known first volume V1, which can be any suitable volume, such as 326 ml, 286 ml, etc.

[0062] Next, close VAL3 and start the dry pump to evacuate the system to remove residual gas from the pipeline. With the dry pump and VAL3 closed, open VAL4 to connect the calibration tank (volume V1) to the target pipeline space (V2+V3) and record the initial pressure P1. Open VAL1 and the gas control valve VALSec to allow the gas to enter the fourth pipeline space (V4) from the mass flow controller and flow through the third pipeline space (V3), and start timing at the same time. After the system pressure stabilizes, record the final pressure P2 and time t. According to the ideal gas law, calculate the flow rate using the known volumes V1, V2, V3, V4, pressure change (P2-P1), and time t.

[0063] In another embodiment, the gas flow rate after the gas source is regulated by the MFC (mass flow controller) is measured. According to the ideal gas law PV=nRT, the volume of the calibration tank is a known quantity (i.e. it has been accurately measured before use). However, due to the complexity of the semiconductor process site, such as process environment fluctuations and equipment installation wiring and gas path reversal, the gas mass flow feedback control system needs to measure its pipeline volume.

[0064] Based on PV=nRT, since the amount of substance nR remains constant in a closed space, and P1V1 / T1=P2V2 / T2, the unknown quantity can be calculated through the gas filling and uniform gas mixing operations.

[0065] Based on the known volume of the calibration tank, and by measuring the P and T values ​​through the calibration module 102 and the pipeline signal acquisition module 101, the pipeline volume of the measurement section (V3 and V2) is obtained, and the pipeline volume of the front end (V4) is further obtained.

[0066] Finally, by measuring the flow rate nR=PV / T, the output flow rate after MFC regulation is calculated. Based on the measured flow rate, a mapping relationship is obtained, and then the upper computer feeds back to MFC for further regulation of MFC.

[0067] Furthermore, this application also provides a gas mass flow feedback control method, applied to a gas mass flow controller, please refer to [reference needed]. Figure 3 , Figure 3 This is a flowchart illustrating an embodiment of the gas mass flow rate feedback control method provided in this application. The method includes: S301: Collect the actual pressure and temperature signals of the pipeline under test; S302: Collect calibration pressure and calibration temperature signals of the calibration pipeline in a calibration vessel of known volume; S303: Calculates the gas mass flow rate measurement value based on the volume of the calibration tank, the actual pressure signal, the actual temperature signal, the calibration pressure signal, and the calibration temperature signal, and generates a flow mapping relationship based on the gas mass flow rate measurement value and the target value of the pipeline under test, which is then fed back to the gas mass flow rate controller to be controlled. The generation of the flow mapping relationship specifically includes: within a preset mass flow range, dividing the preset mass flow range into multiple continuous segments according to characteristic flow points, and determining the scale value of each segment as the target value for that segment; acquiring multiple signal data groups for each segment, wherein each signal data group includes an actual pressure signal, an actual temperature signal, a calibration pressure signal, and a calibration temperature signal; determining the measured value of each signal data group based on the volume of the calibration tank, the actual pressure signal, the actual temperature signal, the calibration pressure signal, and the calibration temperature signal; and constructing a flow mapping relationship based on the measured values ​​and the target value of each continuous segment.

[0068] In this embodiment, the measured gas mass flow rate in the pipeline is determined in real time based on the actual pressure signal, actual temperature signal, calibration pressure signal, calibration temperature signal, and the volume of the calibration tank. Then, by collecting multiple sets of signal data for each segment and calculating the corresponding measured gas mass flow rate, a precise flow mapping relationship between the measured value and the target value is finally constructed and fed back to the external gas mass flow controller to be controlled. This achieves segmented dynamic calibration and closed-loop control within the entire range. Furthermore, since different gas mass flow controllers to be controlled obtain the flow mapping relationship through the same calibration method or even the same calibration tank, each gas mass flow controller to be controlled after calibration has highly consistent flow response characteristics, which can ensure that the gas mass flow rate is synchronously and stably maintained at its respective set value, thus ensuring the consistency of gas flow rate between different gas sources and different gas mass flow controllers to be controlled.

[0069] In one specific embodiment, please refer to Figure 4 ,Figure 4 This is a schematic diagram of the result of an embodiment of the mapping relationship provided in this application. In this diagram, the target value represents the target output flow rate of a specific pipeline, and the measured value represents the flow rate calculated by actual testing. The mapping relationship between the target value and the measured value is not exactly the same in different intervals. For example, the fitted straight lines of the interval from 15 Sccm to 20 Sccm and the interval from 15 Sccm to 20 Sccm have different slopes. That is, when the output flow rate of a specific pipeline is in different ranges, the flow mapping relationship in the control command received by the mass flow controller is not consistent. The mass flow controller can internally regulate the output gas flow rate according to the corresponding flow mapping relationship.

[0070] Furthermore, there is a one-to-one correspondence between the target value and the measured value, and the overall trend of the mapping relationship is consistent, that is, the measured value increases approximately linearly with the increase of the target value. This indicates that the system has good linear response characteristics in each segment. However, the specific mapping slope and offset will vary in different intervals. Therefore, when higher precision control commands are required, the mapping parameters of the corresponding segment need to be dynamically called according to the current working interval to ensure that the control commands always accurately match the physical response characteristics under the current working conditions. In addition, when the number of intervals is increased, the resolution of the mapping parameters of each segment is improved synchronously, and the system's ability to identify and respond to small flow changes is enhanced, thereby significantly improving the control sensitivity and repeatability in the low flow range.

[0071] In this embodiment, by acquiring multiple signal data sets within a preset mass flow range and dividing the range into multiple continuous segments according to characteristic flow points, a precise flow mapping relationship is established based on the signal data sets of each segment and the corresponding target value. This achieves dynamic closed-loop matching between the target value and the actual flow, effectively eliminating the interference of different pressure and temperature conditions on gas mass flow measurement. Furthermore, based on the current pressure signal, temperature signal, and the established flow mapping relationship, a flow mapping relationship is quickly and accurately generated, achieving high-precision, dynamic feedback control of gas mass flow. This ensures that the gas mass flow of the pipeline under test remains stable at the target value, improving the accuracy, stability, and adaptability of flow control.

[0072] The process of establishing a flow mapping relationship based on the signal data group and the corresponding target value for each segment includes: determining the measured value of each signal data group based on the ideal gas law; establishing a flow mapping relationship between the measured value and the target value for each segment; wherein the flow mapping relationship is a piecewise function.

[0073] In this embodiment, by determining the measured value of each signal data group based on the ideal gas law, and establishing a piecewise function-based flow mapping relationship between the measured values ​​of each segment and the target value, more accurate and realistic feedback control of gas mass flow rate can be achieved. Since the flow mapping relationship is constructed based on actual measurement data, it can truly reflect the dynamic response characteristics of the gas under different pressure and temperature combinations, avoiding systematic deviations caused by the simplification of assumptions in theoretical models.

[0074] In particular, more feature flow points can be obtained as needed to improve the resolution and robustness of flow mapping, such as increasing the sampling density within critical process windows or adding feature points for regions of abrupt changes in gas properties.

[0075] In another embodiment, establishing a flow mapping relationship based on each segment of signal data group and the corresponding target value includes: determining the measured value of each signal data group based on the ideal gas law; constructing a scatter plot and fitting a linear mapping function based on the measured value and the target value; and determining the linear mapping function as the flow mapping relationship.

[0076] In this embodiment, by constructing a scatter plot and fitting a linear mapping function to determine the flow mapping relationship, a mathematical correlation model between the measured value and the target value can be established more accurately. Since the linear mapping function can more objectively reflect the overall trend and inherent law of flow change, it can reduce the local error that may be caused by segmentation, improve the continuity and accuracy of flow feedback control, make the control process respond more smoothly to flow fluctuations and adjust more precisely, thereby further optimizing the dynamic control effect of gas mass flow.

[0077] In particular, when the pressure and temperature changes are relatively small in actual operating conditions, a calibration compensation model can be directly constructed based on the actual pressure signal, actual temperature signal, calibration pressure signal, calibration temperature signal, and target value. This model can then correct flow deviations in real time. In other words, the calibration compensation model directly correlates the pressure signal, temperature signal, and target value to generate a flow mapping relationship to control the flow rate of the gas passing through the mass flow controller. This method overcomes the limitations of traditional lookup table methods and fixed coefficient compensation, making the calibration compensation model both physically interpretable and engineering-practical.

[0078] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0079] The above provides a detailed description of a gas mass flow feedback control system and method provided in the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the technical solutions and core ideas of this application. Those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A gas mass flow feedback control system, characterized in that, An external mass flow controller for a controlled gas, the system comprising: The pipeline signal acquisition module is used to acquire the actual pressure signal and actual temperature signal of the pipeline under test; The calibration module includes a calibration vessel of known volume, and the calibration module is used to acquire calibration pressure signals and calibration temperature signals of the calibration pipeline; The control module is connected to the pipeline signal acquisition module and the calibration module respectively. It is used to calculate the gas mass flow rate measurement value based on the volume of the calibration tank, the actual pressure signal, the actual temperature signal, the calibration pressure signal, and the calibration temperature signal. It also generates a flow rate mapping relationship based on the gas mass flow rate measurement value and the target value of the pipeline to be tested and feeds it back to the gas mass flow rate controller to be controlled. The generation of the flow mapping relationship specifically includes: within a preset mass flow range, dividing the preset mass flow range into multiple continuous segments according to characteristic flow points, and determining the scale value of each segment as the target value of that segment; acquiring multiple signal data groups for each segment, wherein each signal data group includes an actual pressure signal, an actual temperature signal, a calibration pressure signal, and a calibration temperature signal; determining the measured value of each signal data group based on the volume of the calibration tank, the actual pressure signal, the actual temperature signal, the calibration pressure signal, and the calibration temperature signal; and constructing the flow mapping relationship based on the measured values ​​and the target value of each continuous segment.

2. The gas mass flow feedback control system according to claim 1, characterized in that, The gas mass flow feedback control system also includes a host computer module; The host computer module is used to generate gas mass flow control commands based on the gas mass flow measurement value and the flow mapping relationship.

3. The gas mass flow feedback control system according to claim 2, characterized in that, The control module also includes a back-end valve control component, which is used to generate a back-end valve flow mapping relationship for each valve based on the gas mass flow measurement value in the pipeline corresponding to that valve.

4. The gas mass flow feedback control system according to claim 3, characterized in that, The back-end valve control component includes a back-end valve control submodule and a gated valve control submodule; The back-end valve control submodule is used to generate corresponding pipeline opening and closing adjustment commands based on the flow mapping relationship of back-end valves in different pipelines. The gate valve control submodule is used to generate corresponding gas path switching commands according to the gas path switching requirements.

5. The gas mass flow feedback control system according to claim 3, characterized in that, The gas mass flow feedback control system also includes a gas source valve sub-control module, which is linked with the pipeline signal acquisition module through a switch linkage control structure to form a switch linkage control loop. The gas source valve secondary control module is used to trigger the switch linkage control loop to perform a shutdown action when the pressure signal of the pipeline under test is greater than the preset pressure threshold, so as to shut down the mass flow controller of the gas to be controlled.

6. The gas mass flow feedback control system according to claim 1, characterized in that, Both the pipeline signal acquisition module and the calibration module include a resistance temperature detector and a pressure gauge.

7. A gas mass flow rate feedback control method, characterized in that, Applications include: Mass flow controllers for the gas to be controlled, including: Collect the actual pressure and temperature signals of the pipeline under test; Collect calibration pressure and temperature signals from the calibration pipeline in a calibration vessel of known volume; The gas mass flow rate measurement value is calculated based on the volume of the calibration tank, the actual pressure signal, the actual temperature signal, the calibration pressure signal, and the calibration temperature signal. A flow rate mapping relationship is generated based on the gas mass flow rate measurement value and the target value of the pipeline under test and fed back to the gas mass flow rate controller to be controlled. The generation of the flow mapping relationship specifically includes: within a preset mass flow range, dividing the preset mass flow range into multiple continuous segments according to characteristic flow points, and determining the scale value of each segment as the target value of that segment; acquiring multiple signal data groups for each segment, wherein each signal data group includes an actual pressure signal, an actual temperature signal, a calibration pressure signal, and a calibration temperature signal; determining the measured value of each signal data group based on the volume of the calibration tank, the actual pressure signal, the actual temperature signal, the calibration pressure signal, and the calibration temperature signal; and constructing the flow mapping relationship based on the measured values ​​and the target value of each continuous segment.

8. The gas mass flow rate feedback control method according to claim 7, characterized in that, The step of determining the measured value of each signal data group based on the volume of the calibration vessel, the actual pressure signal, the actual temperature signal, the calibration pressure signal, and the calibration temperature signal includes: Based on the ideal gas law, the volume of the calibration vessel, the actual pressure signal, the actual temperature signal, the calibration pressure signal, and the calibration temperature signal are converted into data to obtain the measured value of each signal data group.

9. The gas mass flow rate feedback control method according to claim 8, characterized in that, The step of constructing the traffic mapping relationship based on the measured value and the target value of each consecutive segment includes: A flow mapping relationship is established between the measured value and the target value for each segment; The traffic mapping relationship is a piecewise function.

10. The gas mass flow rate feedback control method according to claim 9, characterized in that, The step of establishing a traffic mapping relationship between the measured value and the target value for each segment includes: Based on the measured values ​​and the target values, a scatter plot is constructed and a linear mapping function is fitted. The linear mapping function is determined to be the flow mapping relationship.

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