Capacitance diaphragm gauge temperature correction method

Abstract

This application relates to the field of vacuum measurement technology, specifically to a temperature correction method for a capacitive thin-film vacuum gauge. By real-time detection of the external temperature, the method estimates the impact of temperature drift on the zero point and range of the vacuum gauge and implements dynamic compensation. This effectively overcomes the problem that vacuum gauges in the prior art are greatly affected by ambient temperature, and can significantly reduce the zero point and range temperature coefficient of the capacitive thin-film vacuum gauge. This enables the capacitive thin-film vacuum gauge to more accurately measure pressure in variable temperature environments, improving the accuracy and stability of the measurement.

Description

Technical Field

[0001] This application relates to the field of vacuum measurement technology, and more specifically, to a method for temperature correction of a capacitive thin-film vacuum gauge. Background Technology

[0002] A capacitive thin-film vacuum gauge is a type of instrument used for measuring rough and low vacuum. Typically, a vacuum gauge contains a measuring chamber and a reference chamber, separated by an elastic diaphragm. Based on the principle of capacitance change, it measures gas pressure by detecting the change in capacitance caused by the deformation of the elastic diaphragm under a pressure difference. Due to its advantages such as high measurement accuracy, good linearity, and independence from gas type, capacitive thin-film vacuum gauges are widely used in semiconductor manufacturing, space exploration, and military industries.

[0003] However, capacitive thin-film vacuum gauges are highly sensitive to changes in ambient temperature. Temperature fluctuations cause thermal expansion of the diaphragm material, changes in reference chamber pressure, and drift in electronic component characteristics, leading to measurement deviations. Manufacturers typically provide the zero-point temperature effect and full-scale temperature coefficient of the vacuum gauge separately, without incorporating them into the gauge's measurement accuracy. In scenarios with varying ambient temperatures, the measurement accuracy of the vacuum gauge will be significantly reduced.

[0004] Currently, the main way to reduce the influence of temperature is to install a constant temperature insulation device on the sensor. However, since the sensor must be connected to the system under test via an interface, it is impossible to completely isolate it from ambient temperature interference. The temperature gradient between the ambient temperature and the insulation device will still cause errors in the vacuum gauge measurement results. By establishing a real-time evaluation model of the external temperature and temperature drift error, the temperature coefficient of the capacitive thin-film vacuum gauge can be further reduced, thereby improving its measurement accuracy. Summary of the Invention

[0005] This application provides a temperature correction method for a capacitive thin-film vacuum gauge, which can detect the external temperature in real time and estimate the impact of temperature drift on the zero point and range of the vacuum gauge.

[0006] To achieve the above objectives, this application provides a temperature correction method for a capacitive thin-film vacuum gauge, comprising the following steps: Step 1: Install at least one temperature sensor at a key location of the capacitive thin-film vacuum gauge to collect ambient temperature data in real time; Step 2: Establish a zero-point temperature drift model and a range temperature drift model. The models are used to describe the effect of temperature changes on the zero-point reading drift and full-scale reading drift of the vacuum gauge. Step 3: Calibrate the capacitive thin-film vacuum gauge under different temperature conditions and obtain experimental data on the changes of zero-point reading and full-scale reading with temperature. Step 4: Based on experimental data, optimize and identify the parameters of the zero-point temperature drift model and the interval temperature drift model; Step 5: During the operation of the vacuum gauge, based on the real-time collected ambient temperature, calculate the zero-point drift compensation and interval drift compensation at the current temperature using the zero-point temperature drift model and the interval temperature drift model, respectively. Step 6: Correct the original pressure reading of the vacuum gauge according to the compensation amount, and output the corrected pressure value; Step 7: Periodically evaluate the compensation effect of the temperature drift model. When the evaluation results do not meet the preset accuracy requirements, automatically trigger the re-identification and update of the model parameters.

[0007] Furthermore, in step 2, the zero-point temperature drift model and the interval temperature drift model are polynomial models, with the following forms: ,in, For zero-point temperature drift model, This is a temperature drift model for a given range, where T represents ambient temperature data, and a i b i (i=0, 1, 2, ..., n) are model parameters.

[0008] Furthermore, in step 4, the least squares method or artificial intelligence algorithm is used to optimize the model parameters in order to minimize the error between the model prediction and the experimental data.

[0009] Furthermore, in step 6, the corrected pressure value is calculated using the following formula: ,in, This is the corrected pressure value. This is the original pressure reading.

[0010] Furthermore, this method is implemented through a real-time ambient temperature correction system for a capacitive thin-film vacuum gauge. The system includes: a temperature detection module, comprising one or more temperature sensors deployed at key locations of the capacitive thin-film vacuum gauge for real-time acquisition of ambient temperature data; a signal processing module, connected to the temperature detection module and the vacuum gauge signal output terminal, for receiving and processing temperature signals and raw vacuum gauge readings; a temperature drift estimation module, connected to the signal processing module, internally storing zero-point temperature drift models and interval temperature drift models for calculating temperature drift compensation based on real-time temperature data; and a dynamic compensation module, connected to the signal processing module and the temperature drift estimation module, for receiving raw pressure readings and temperature drift compensation, and performing calculations to output the corrected pressure value.

[0011] Furthermore, the temperature sensor is positioned at least at one location, including the pressure-sensing diaphragm of the capacitive thin-film vacuum gauge, around the reference cavity, and in the area where the signal processing circuit board is located.

[0012] Furthermore, the real-time ambient temperature correction system of the capacitive thin-film vacuum gauge is integrated into the internal control unit of the capacitive thin-film vacuum gauge, or exists independently as an external compensation device.

[0013] The temperature correction method for a capacitive thin-film vacuum gauge provided in this application has the following beneficial effects: (1) This application reduces the zero-point temperature coefficient and the range temperature coefficient of the vacuum gauge by an order of magnitude, and maintains the measurement error within 1.5% in a wide temperature range of -30℃ to 50℃, which significantly reduces the temperature coefficient. (2) This application can track rapid changes in ambient temperature and achieve real-time compensation, overcoming the limitations of traditional static compensation methods. It also achieves temperature compensation without significantly increasing hardware costs and system complexity, which is conducive to its widespread application. (3) This application has good compatibility and can be used in conjunction with existing constant temperature control systems to form multiple temperature protections and further improve the stability of vacuum gauge temperature. Attached Figure Description

[0014] The accompanying drawings, which form part of this application, are used to provide a further understanding of the application and to make other features, objects, and advantages of the application more apparent. The illustrative embodiments and descriptions of this application are used to explain the application and do not constitute an undue limitation of the application. In the drawings: Figure 1 This is a flowchart of the steps of the temperature correction method for a capacitor thin-film vacuum gauge provided in the embodiments of this application. Detailed Implementation

[0015] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0016] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0017] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0018] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0019] In addition, the term "multiple" should mean two or more.

[0020] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0021] like Figure 1 As shown, this application provides a temperature correction method for a capacitive thin-film vacuum gauge. Temperature sensors are installed at key locations on the vacuum gauge to collect ambient temperature data; a mathematical model describing the relationship between zero-point drift, range drift, and temperature is established; model parameters are identified using historical data or a self-learning algorithm; finally, during vacuum gauge operation, the compensation amount is calculated based on real-time temperature data using the model, and the original reading is dynamically corrected. Specifically, the method includes the following steps: Step 1: Install at least one temperature sensor at key locations on the capacitive thin-film vacuum gauge to collect ambient temperature data T in real time. Key locations include the vicinity of the pressure-sensing diaphragm, directly reflecting its operating temperature; the outer wall of the reference cavity, monitoring its temperature status; and the signal processing circuit area, reflecting the operating temperature of electronic components. The temperature sensor is preferably a PT100 platinum resistance thermometer, a thermocouple, or an integrated digital temperature sensor, with a sampling frequency of at least 10Hz to ensure real-time performance. The temperature detection module transmits the collected analog temperature signal to the signal processing module, which performs filtering, amplification, and analog-to-digital conversion to output a digital temperature signal.

[0022] Step 2: Establish a zero-point temperature drift model and a range temperature drift model. The models are used to describe the effect of temperature changes on the zero-point reading drift and full-scale reading drift of the vacuum gauge. Specifically, based on thermodynamic principles and experimental data, zero-point temperature drift models are established in the temperature drift estimation module. and range (full scale) temperature drift model This is used to describe the effect of temperature T on the output system error of the vacuum gauge. The model can be in polynomial form: , where a i b i (i=0, 1, 2, ..., n) are model parameters.

[0023] Step 3: Calibrate the capacitive thin-film vacuum gauge under different temperature conditions and obtain experimental data on the changes of zero-point reading and full-scale reading with temperature. Step 4: Based on experimental data, optimize and identify the parameters of the zero-point temperature drift model and the interval temperature drift model; Specifically, within a wide temperature range (e.g., -30℃ to 50℃), a multi-temperature-point calibration experiment is conducted on the capacitive thin-film vacuum gauge. The signal processing module collects zero-point and full-scale readings at different temperatures, and the temperature drift estimation module optimizes the model parameters using the least squares method, ridge regression, or artificial intelligence algorithms (e.g., neural networks) to minimize the mean square error between the model's predicted values ​​and the measured values.

[0024] Step 5: During the operation of the vacuum gauge, based on the real-time collected ambient temperature, calculate the zero-point drift compensation and interval drift compensation at the current temperature using the zero-point temperature drift model and the interval temperature drift model, respectively. Step 6: Correct the original pressure reading of the vacuum gauge according to the compensation amount, and output the corrected pressure value; Specifically, during normal operation of the vacuum gauge, the temperature drift estimation module calculates the current zero-point drift and interval drift based on the real-time detected temperature value using the established temperature drift estimation model, and dynamically compensates for the measurement results. The compensation amount is then output to the dynamic compensation module, which receives the original pressure signal and performs real-time correction according to the following formula: ,in, This is the corrected pressure value. This is the original pressure reading.

[0025] Step 7: Periodically evaluate the compensation effect of the temperature drift model. When the evaluation results do not meet the preset accuracy requirements, the model parameters will be automatically re-identified and updated. The system will periodically (e.g., monthly or every thousand hours) evaluate the compensation effect. If the compensation residual is detected to exceed the set threshold, the recalibration process will be automatically triggered to update the model parameters to adapt to long-term sensor aging or environmental changes.

[0026] Specifically, the real-time ambient temperature correction system for the capacitive thin-film vacuum gauge provided in this application embodiment can be integrated in the following two forms: embedded integration, which integrates the temperature detection module, signal processing module, temperature drift estimation module, and dynamic compensation module into the main control board of the vacuum gauge to achieve integrated correction; and external compensator, which exists in the form of an independent box and connects the vacuum gauge output terminal and the temperature sensor through a cable, and is suitable for upgrading and retrofitting existing equipment.

[0027] More specifically, this application effectively overcomes the problem of vacuum gauges being greatly affected by ambient temperature in the prior art by real-time detection of the external temperature, estimating the impact of temperature drift on the zero point and range of the vacuum gauge, and implementing dynamic compensation. It can significantly reduce the zero point and range temperature coefficient of the capacitive thin film vacuum gauge, enabling the capacitive thin film vacuum gauge to achieve more accurate pressure measurement in variable temperature environments, thereby improving the accuracy and stability of the measurement.

[0028] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for temperature correction of a capacitive thin-film vacuum gauge, characterized in that, Includes the following steps: Step 1: Install at least one temperature sensor at a key location of the capacitive thin-film vacuum gauge to collect ambient temperature data in real time; Step 2: Establish a zero-point temperature drift model and a range temperature drift model. The models are used to describe the effect of temperature changes on the zero-point reading drift and full-scale reading drift of the vacuum gauge. Step 3: Calibrate the capacitive thin-film vacuum gauge under different temperature conditions and obtain experimental data on the changes of zero-point reading and full-scale reading with temperature. Step 4: Based on experimental data, optimize and identify the parameters of the zero-point temperature drift model and the interval temperature drift model; Step 5: During the operation of the vacuum gauge, based on the real-time collected ambient temperature, calculate the zero-point drift compensation and interval drift compensation at the current temperature using the zero-point temperature drift model and the interval temperature drift model, respectively. Step 6: Correct the original pressure reading of the vacuum gauge according to the compensation amount, and output the corrected pressure value; Step 7: Periodically evaluate the compensation effect of the temperature drift model. When the evaluation results do not meet the preset accuracy requirements, automatically trigger the re-identification and update of the model parameters.

2. The temperature correction method for a capacitive thin-film vacuum gauge according to claim 1, characterized in that, In step 2, the zero-point temperature drift model and the interval temperature drift model are polynomial models, with the following forms: ,in, For zero-point temperature drift model, This is a temperature drift model for a given range, where T represents ambient temperature data, and a i b i (i=0, 1, 2, ..., n) are model parameters.

3. The temperature correction method for a capacitive thin-film vacuum gauge according to claim 2, characterized in that, In step 4, the least squares method or artificial intelligence algorithm is used to optimize the model parameters in order to minimize the error between the model prediction and the experimental data.

4. The temperature correction method for a capacitive thin-film vacuum gauge according to claim 3, characterized in that, In step 6, the corrected pressure value is calculated using the following formula: ,in, This is the corrected pressure value. This is the original pressure reading.

5. The temperature correction method for a capacitive thin-film vacuum gauge according to claim 4, characterized in that, This method is implemented through a real-time ambient temperature correction system for a capacitive thin-film vacuum gauge, the system comprising: The temperature detection module includes one or more temperature sensors installed in key parts of the capacitive thin-film vacuum gauge for real-time acquisition of ambient temperature data. The signal processing module is connected to the temperature detection module and the vacuum gauge signal output terminal, and is used to receive and process the temperature signal and the original reading signal of the vacuum gauge. The temperature drift estimation module is connected to the signal processing module and internally stores a zero-point temperature drift model and an interval temperature drift model, which are used to calculate the temperature drift compensation amount based on real-time temperature data. The dynamic compensation module, connected to the signal processing module and the temperature drift estimation module, is used to receive the original pressure reading and the temperature drift compensation amount, and to perform calculations to output the corrected pressure value.

6. The temperature correction method for a capacitive thin-film vacuum gauge according to claim 5, characterized in that, The temperature sensor is located at least at one of the following locations: the pressure-sensing diaphragm of the capacitive thin-film vacuum gauge, around the reference cavity, and in the area where the signal processing circuit board is located.

7. The temperature correction method for a capacitive thin-film vacuum gauge according to claim 6, characterized in that, The real-time ambient temperature correction system of the capacitive thin-film vacuum gauge is integrated into the internal control unit of the capacitive thin-film vacuum gauge, or it exists independently as an external compensation device.

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