A method for calibrating a gas flow meter

Abstract

The application provides a calibration method for a gas flow meter, comprising the following steps: obtaining the real volumes of a first gas tank and a second gas tank, calculating the real volume difference of the two as a first volume difference; selecting a gas supply flow from the range of the gas flow meter, supplying the first gas tank with the gas supply flow until the first gas tank is filled, and recording the first gas amount; supplying the second gas tank with the gas supply flow until the second gas tank is filled, and recording the second gas amount; the difference between the first gas amount and the second gas amount is a second volume difference; and calibrating the gas flow meter according to the deviation between the second volume difference and the first volume difference. The calibration method for the gas flow meter can realize the calibration of the gas flow meter without removing the gas flow meter from the gas source pipeline, and can eliminate the interference of the gas path volume in the gas source pipeline which cannot be measured on the measurement result.

Description

Technical Field

[0001] This invention relates to the field of gas flow meter calibration, and more particularly to a calibration method for a gas flow meter. Background Technology

[0002] In semiconductor process equipment, such as wafer etching or other processes, gas flow rate is one of the most important parameters, and gas flow meters in the gas path often need to be calibrated. In existing semiconductor process equipment, process chambers are often used to calibrate gas flow meters. However, due to the gaps between components within the process chamber and the influence of the physical and chemical adsorption of gases by organic polymers within the process chamber, high-precision gas calibration cannot be achieved based on the process chamber.

[0003] A new calibration method is needed for calibrating gas flow meters used in semiconductor process equipment. Summary of the Invention

[0004] The purpose of this invention is to provide a calibration method for gas flow meters, which has the advantage of enabling high-precision calibration of gas flow meters in the gas path.

[0005] To achieve the above objectives, the present invention provides a calibration method for a gas flow meter, comprising a calibration system connected to a gas source pipeline, the gas source pipeline including a gas source and a gas flow meter, the gas flow meter being located downstream of the gas source; the calibration system comprising: a first gas tank and a second gas tank of different volumes, the first gas tank and the second gas tank being connected in parallel and connected to the gas source pipeline, the volume of a first gas path between the first gas tank and the gas source being the same as the volume of a second gas path between the second gas tank and the gas source;

[0006] The calibration method includes:

[0007] S10. Obtain the true volumes of the first gas tank and the second gas tank, and assemble the calibration system to calculate the true volume difference between the first gas tank and the second gas tank, which is denoted as the first volume difference.

[0008] S20. Select a gas flow rate value from the range of the gas flow meter and set the gas flow rate value as the gas supply flow rate of the gas source;

[0009] S30. Gas is supplied to the first gas tank through the first gas path at the gas supply flow rate until the first gas tank is full, and the gas flow meter records the first gas volume when the first gas tank and the first gas path are full; gas is supplied to the second gas tank through the second gas path at the gas supply flow rate until the second gas tank is full, and the gas flow meter records the second gas volume when the second gas tank and the second gas path are full.

[0010] S40. Calculate the difference between the first gas quantity and the second gas quantity to obtain the second volume difference;

[0011] S50. Compare the second volume difference with the first volume difference to obtain the deviation;

[0012] S60. Determine whether the deviation is equal to zero. If the deviation is not equal to zero, proceed to step S61. Calibrate the flow reading of the gas flow meter under the gas supply flow according to the deviation, and return to step S30. If the deviation is equal to zero, the gas flow value calibration of the current gas supply flow is completed.

[0013] Optionally, within the range of the gas flow meter, gas flow calibration points are set at 10% intervals of the total range of the gas flow meter.

[0014] Optionally, after step S60, the following step is also included: S70, determining whether there are any uncalibrated gas flow calibration points within the range of the gas flow meter; if so, proceeding to S71, selecting an uncalibrated gas flow value from within the range of the gas flow meter as the gas supply flow, and returning to step S30; if not, ending the calibration.

[0015] Optionally, in step S10, the actual volumes of the first gas tank and the second gas tank are measured using the water weight method.

[0016] The present invention also provides a calibration method for a gas flow meter, comprising a calibration system connected to a gas source pipeline, the gas source pipeline including a gas source and a gas flow meter, the gas flow meter being located downstream of the gas source; the calibration system comprising: a first gas tank and a second gas tank of different volumes, the first gas tank and the second gas tank being connected in parallel and connected to the gas source pipeline, the volume of a first gas path between the first gas tank and the gas source being the same as the volume of a second gas path between the second gas tank and the gas source;

[0017] The calibration method includes:

[0018] S100. Obtain the true volumes of the first gas tank and the second gas tank, and assemble the calibration system to calculate the true volume difference between the first gas tank and the second gas tank, which is denoted as the first volume difference.

[0019] S200: Select a gas flow rate value from the range of the gas flow meter and set the gas flow rate value as the gas supply flow rate of the gas source;

[0020] S300: Supply gas to the first gas tank through the first gas path at the gas supply flow rate and fill the first gas tank, record the gas supply volume as the first volume, and measure the first gas pressure difference and the first time difference before and after the process of filling the first gas volume into the first gas tank and the first gas path; supply gas to the second gas tank through the second gas path at the gas supply flow rate and fill the second gas tank, record the gas supply volume as the second volume, and measure the second gas pressure difference and the second time difference during the process of filling the second gas tank and the second gas path with the second volume of gas.

[0021] S400. Calculate the true flow rate of the gas flow meter based on the first volume difference, the first pressure difference, the first time difference, the second pressure difference, and the second time difference. Then, calibrate the reading of the gas flow meter at the current gas supply flow rate based on the true flow rate, thus completing the calibration.

[0022] Optionally, the flow path volume of the gas source pipeline is calculated based on the true flow rate, and gas path calibration is performed based on the flow path volume.

[0023] Optionally, in step S100, the actual volumes of the first gas tank and the second gas tank are measured using the water weight method.

[0024] In summary, compared with the prior art, the calibration method for gas flow meters provided by the present invention has the following beneficial effects:

[0025] The calibration method for a gas flow meter of the present invention involves pre-measuring the actual volumes of a first gas tank and a second gas tank to obtain a first volume difference. A gas flow meter in the gas path is then used to measure the gas volumes flowing into the first and second gas tanks respectively. The volume difference is obtained by comparing the second volume difference with the first volume difference to calibrate the gas flow meter reading. This method eliminates the need to remove the gas flow meter from the gas source pipeline and also eliminates interference from unmeasurable gas path volumes in the gas source pipeline on the measurement results, thus achieving the calibration of the gas flow meter. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the calibration system used in the calibration method of the present invention.

[0027] Figure 2 A flowchart of a calibration method for a gas flow meter provided by the present invention.

[0028] Figure 3 A flowchart of another calibration method for a gas flow meter provided by the present invention.

[0029] Explanation of reference numerals in the attached figures:

[0030] Calibration System 1

[0031] Gas source 10

[0032] Gas flow meter 11

[0033] First gas cylinder 12

[0034] Second gas tank 13

[0035] First valve 14

[0036] Second valve 15 Detailed Implementation

[0037] The following will be combined with the appendix in the embodiments of the present invention. Figure 1 ~Attached Figure 3 The technical solutions, structural features, objectives and effects achieved in the embodiments of the present invention will be described in detail.

[0038] It should be noted that the accompanying drawings are in a very simplified form and use non-precise proportions. They are only used to facilitate and clarify the purpose of illustrating the embodiments of the present invention, and are not intended to limit the implementation conditions of the present invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportional relationship, or adjustments to the size should still fall within the scope of the technical content disclosed in the present invention, provided that they do not affect the effects and objectives that the present invention can produce.

[0039] It should be noted that, in this invention, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only the expressly listed elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0040] This invention provides a calibration method for a gas flow meter. The calibration method utilizes, for example... Figure 1The calibration system 1 shown is implemented. Before calibrating the gas flow meter 11 using the calibration method, the gas source pipeline within the calibration system 1 is first connected. The gas source pipeline includes a gas source 10 and a gas flow meter 11. The gas source 10 is used to supply nitrogen or other gases into the gas source pipeline. The gas flow meter 11 is located downstream of the gas source 10 and is used to measure the gas flow rate from the gas source 10. The calibration system 1 also includes a first gas tank 12 and a second gas tank 13 of different volumes. The first gas tank 12 and the second gas tank 13 are connected in parallel and connected to the gas source pipeline. Both the first gas tank 12 and the second gas tank 13 are located downstream of the gas flow meter 11. A first valve 14 is provided between the first gas tank 12 and the gas flow meter 11, and a second valve 15 is provided between the second gas tank 13 and the gas flow meter 11.

[0041] Because the gas flow meter 11 is connected to the first gas tank 12 and the second gas tank 13 via a gas path, and there are gaps at the connecting parts between the gas flow meter 11 and the first gas tank 12 and the second gas tank 13 in the gas path, the volume of gas that can be contained in these gaps cannot be accurately measured. To eliminate the measurement error caused by these gaps in the gas path, the first gas tank 12 and the second gas tank 13 are installed at the same distance from the gas source 10 in the gas path, so that the volume of the first gas path between the first gas tank 12 and the gas source 10 is the same as the volume of the second gas path between the second gas tank 13 and the gas source 10.

[0042] The calibration method of the present invention calibrates the gas flow meter 11 by measuring the volume difference between the first gas volume filling the first gas tank 12 and the first gas path and the second gas volume filling the second gas tank 13 and the second gas path. In the process of comparing the first gas volume and the second gas volume, the volumes of the first gas path and the second gas path that cannot be accurately measured are canceled out when they are subtracted, thereby calibrating the gas flow meter 11.

[0043] Specifically, such as Figure 2 As shown, the calibration method includes:

[0044] S10. Obtain the true volumes of the first gas tank 12 and the second gas tank 13. In this step, the true volumes of the first gas tank 12 and the second gas tank 13 are measured separately outside the gas path. The true volume refers to the volume accuracy of the first gas tank 12 and the second gas tank 13 measured in this step, which is sufficient for calibrating the gas flow meter 11 in subsequent calibration processes. Therefore, the volumes of the first gas tank 12 and the second gas tank 13 measured in this step can be used as calibration benchmarks for subsequent calibration of the gas flow meter 11. After the volume measurement is completed, the first gas tank 12 and the second gas tank 13 are respectively installed in the gas source pipeline and connected to the gas source 10 and the gas flow meter 11 to form the calibration system 1. Figure 1In the preferred embodiment shown, the calibration system 1 further includes a first valve 14 and a second valve 15, which are used to control the opening and closing of the first gas path and the second gas path, respectively. In addition, in step S10, the actual volume difference between the first gas tank 12 and the second gas tank 13 is calculated based on the measured actual volumes of the first gas tank 12 and the second gas tank 13, and is denoted as the first volume difference.

[0045] S20. Select a gas flow rate value from the range of the gas flow meter 11 and set the gas flow rate value as the current gas supply flow rate of the gas source 10.

[0046] Because the measurement error varies at different ranges within the overall range of the gas flow meter 11, it is necessary to calibrate the gas flow rate values ​​at different ranges within the overall range of the gas flow meter 11 separately. To achieve this, this method selects multiple different flow rates at intervals as gas flow calibration points within the range of the gas flow meter 11, and controls the gas source 10 to supply gas to the gas source pipeline at the corresponding gas flow rate, so as to calibrate the gas flow meter 11 at different ranges separately, thereby achieving full-range calibration of the gas flow meter 11.

[0047] Taking the range of gas flow meter 11 as 0-100 sccm (Standard Cubic Centimeters per Minute) as an example, if 50 sccm or other flow values ​​are selected as the gas supply flow to the gas source pipeline, then the gas source 10 is controlled to supply gas to the gas source pipeline at a flow rate of 50 sccm. The slight deviation between the actual gas supply flow of the gas source 10 and the set gas supply flow (50 sccm in this embodiment) will not affect the calibration accuracy of the gas flow meter 11, so the gas supply flow deviation of the gas source 10 can be ignored.

[0048] S30. Gas is supplied to the first gas tank 12 through the first gas path at the current gas supply flow rate until the first gas tank 12 is full. During the gas supply to the first gas tank 12, the second valve 15 located on the second gas path is closed to ensure that the gas supply from the gas source 10 completely fills the first gas path and the first gas tank 12 without flowing into the second gas tank 13. During the process of the gas filling the first gas path and the first gas tank 12, the gas flow meter 11 records the first gas volume when the first gas tank 12 and the first gas path are filled.

[0049] After recording the first gas volume, gas continues to be supplied to the second gas tank 13 through the second gas path at the current gas supply flow rate until the second gas tank 13 is full. During the gas supply to the second gas tank 13, the first valve 14 located on the first gas flow is closed to ensure that the gas supply from the gas source 10 completely fills the second gas path and the second gas tank 13 without flowing into the first gas tank 12. During the process of filling the second gas path and the second gas tank 13, the gas flow meter 11 records the second gas volume that fills the second gas tank 13 and the second gas path.

[0050] S40. Calculate the difference between the first gas volume and the second gas volume to obtain the second volume difference. The first gas volume is the volume of gas filling the first gas path and the first gas tank 12, as measured by the gas flow meter 11 at the current gas supply flow rate. The second gas volume is the volume of gas filling the second gas path and the second gas tank 13, as measured by the gas flow meter 11 at the current gas supply flow rate. Since the first gas tank 12 and the second gas tank 13 are symmetrically installed in the gas source pipeline, the volume of the first gas path between the first gas tank 12 and the gas source 10 is the same as the volume of the second gas path between the second gas tank 13 and the gas source 10. During the subtraction of the first gas volume and the second gas volume, the volumes of the first gas path and the second gas path cancel each other out. The resulting second volume difference is the volume difference between the first gas tank 12 and the second gas tank 13 measured by the gas flow meter 11.

[0051] S50. Compare the second volume difference with the first volume difference to obtain the deviation;

[0052] S60. Determine if the deviation is zero. If yes, the gas flow rate value of the current gas supply is calibrated. Otherwise, continue with steps S61 and S30.

[0053] Understandably, when the gas flow meter 11 measures accurately and without error, the second volume difference between the first gas tank 12 and the second gas tank 13 obtained in step S40 should be equal to the first volume difference between the first gas tank 12 and the second gas tank 13 measured in step S10. In other words, if it is determined in step S50 that the deviation is zero, then the reading of the gas flow meter 11 is accurate at the current gas supply flow rate, and calibration is complete at the current gas supply flow rate.

[0054] If the deviation is not equal to zero, that is, there is a deviation between the second volume difference between the first gas tank 12 and the second gas tank 13 measured by the flow meter and the first volume difference between the first gas tank 12 and the second gas tank 13 measured in step S10, it indicates that there is an error in the reading of the gas flow meter 11 under the current gas supply flow rate.

[0055] Specifically, in step S61, the flow reading of the gas flow meter 11 at the gas supply flow rate is calibrated based on the deviation between the second volume difference obtained by the gas flow meter 11 and the first volume difference measured by the water weight method, so as to eliminate the deviation of the gas flow meter 11 at the current gas supply flow rate. After completion, the process returns to step S30 to measure the reading of the gas flow meter 11 at the current gas supply flow rate again and confirm whether the deviation has been eliminated. If it has not been eliminated, the calibration continues until the deviation is determined to be zero in step S60.

[0056] As a preferred embodiment, after step S60, the method further includes step S70: determining whether there are any uncalibrated gas flow calibration points within the range of the gas flow meter 11.

[0057] If there is an uncalibrated gas flow calibration point, proceed to step S71, select an uncalibrated gas flow value from the range of gas flow meter 11 as the gas supply flow, and return to step S30; if there is no uncalibrated gas flow calibration point, it indicates that all gas flow calibration points that need to be calibrated have been calibrated, and the calibration method ends.

[0058] The calibration method for a gas flow meter 11 of the present invention involves pre-measuring the volumes of a first gas tank 12 and a second gas tank 13, and then installing the first gas tank 12 and the second gas tank 13 into a gas source pipeline. Subsequently, it is not necessary to remove the first gas tank 12, the second gas tank 13, or the gas flow meter 11 from the gas source pipeline; calibration of the gas flow meter 11 can be achieved by measuring the volume difference between the first gas tank 12 and the second gas tank 13 using the gas flow meter 11. This calibration method eliminates the influence of gas path volume and component clearances on the measurement results through a comparison method. The calibration system 1 has a simple structure, and the calibration method has high calibration accuracy, achieving high-precision calibration of the gas flow meter 11.

[0059] In this embodiment, the volumes of the first gas tank 12 and the second gas tank 13 are measured using the water weight method as the actual volumes. In other embodiments, other methods can also be used to measure the volumes of the first gas tank 12 and the second gas tank 13, as long as the actual volumes of the first gas tank 12 and the second gas tank 13 can be measured, and no limitation is imposed here.

[0060] In this embodiment, within the range of the gas flow meter 11, gas flow calibration points are set at intervals of 10% of the total range of the gas flow meter 11.

[0061] In other embodiments, gas flow calibration points can be set at intervals of 5% or 20% of the total range of the gas flow meter 11 or other intervals. The setting of the gas flow calibration points can be selected according to the commonly used flow range and calibration accuracy of the gas flow meter 11, and there are no restrictions here.

[0062] refer to Figure 3 As shown, the present invention also provides another calibration method for the gas flow meter 11, and similarly utilizes... Figure 1 The calibration system 1 shown is implemented in the same way as the previous embodiment, and the components and connection methods are the same, so they will not be described again here.

[0063] The calibration method of the present invention calibrates the gas flow meter 11 by measuring the first gas pressure difference Δp1 before and after filling the first gas volume of the first gas tank 12 and the first gas path, the first time difference Δt1 required for filling, the second gas pressure difference Δp2 before and after filling the second gas volume of the second gas tank 13 and the second gas path, the second time difference Δt2 required for filling, and the first volume difference a between the first gas tank 12 and the second gas tank 13. In the process of comparing the first gas volume and the second gas volume, the volumes of the first gas path and the second gas path that cannot be accurately measured cancel each other out when subtracted, thereby ignoring the influence of the unmeasurable volume on the calibration result.

[0064] like Figure 3 As shown, the calibration method includes:

[0065] S100: Obtain the actual volumes of the first gas tank 12 and the second gas tank 13. In this step, the actual volumes of the first gas tank 12 and the second gas tank 13 are measured separately outside the gas path. The volumes of the first gas tank 12 and the second gas tank 13 measured in this step are used as calibration benchmarks to calibrate the gas flow meter 11. After the volume measurement is completed, the first gas tank 12 and the second gas tank 13 are respectively installed in the gas source pipeline and connected to the gas source 10 and the gas flow meter 11 to form the calibration system 1. The actual volume difference between the first gas tank 12 and the second gas tank 13 is calculated based on the measured actual volumes and denoted as the first volume difference a.

[0066] S200. Select a gas flow rate value from the range of the gas flow meter 11 and set this gas flow rate value as the current gas supply flow rate of the gas source 10. Control the gas source 10 to supply gas to the gas source pipeline at the corresponding gas flow rate to calibrate the gas flow meter 11 at different ranges. Taking the range of the gas flow meter 11 as 0-100 sccm (Standard Cubic Centimeters per Minute) as an example, if 50 sccm or other flow rates are selected as the gas supply flow rate to the gas source pipeline, then the gas source 10 is controlled to supply gas to the gas source pipeline at a flow rate of 50 sccm. The slight deviation between the actual gas supply flow rate of the gas source 10 and the set gas supply flow rate (50 sccm in this embodiment) will not affect the calibration accuracy of the gas flow meter 11, so the deviation of the gas supply flow rate of the gas source 10 can be ignored.

[0067] S300. At the current gas supply flow rate, gas is supplied to the first gas tank 12 through the first gas path until the first gas tank 12 is full. The gas supply volume is recorded as the first volume V1 + v, where V1 is the volume of the first gas tank 12 and v is the volume of the first gas path. The first pressure difference Δp1 and the first time difference Δt1 are measured before and after the process of filling the first gas tank 12 and the first gas path with the first volume of gas. At the same current gas supply flow rate, gas is supplied to the second gas tank 13 through the second gas path until the second gas tank 13 is full. The gas supply volume is recorded as the second volume V2 + v, where V2 is the volume of the second gas tank 13 and v is the volume of the second gas path. Since the first gas tank 12 and the second gas tank 13 are symmetrically installed in the gas path, the volumes of the first and second gas paths are the same, both represented by v. The second pressure difference Δp2 and the second time difference Δt2 are measured during the process of filling the second gas tank 13 and the second gas path with the second volume of gas.

[0068] S400. Based on the first volume difference a, the first gas pressure difference Δp1, the first time difference Δt1, the second gas pressure difference Δp2, and the second time difference Δt2, calculate the true flow value of the gas flow meter 11. Based on the true flow value, calibrate the reading of the gas flow meter 11 under the current gas supply flow rate to complete the calibration.

[0069] Specifically, according to the ideal gas law pV=nRT, p is the gas pressure in Pascals (Pa); V is the gas volume in cubic meters; n represents the amount of gas in moles (mol); T is the gas thermodynamic temperature in Kelvin (K); and R is the molar gas constant, with a value of approximately 8.314 JJ / (mol·K).

[0070] When the temperature remains constant before and after gas injection, considering only the first time difference Δt1, when gas is supplied to the first gas tank 12 at a flow rate of x sccm through the first gas path and fills the first volume V1+v of the first gas tank 12, the pressure change before and after the first gas tank 12 and the first gas path is the first pressure difference Δp1. Before and after gas injection, the left side of the above ideal gas law can be transformed into Δp1(V1+v), and the right side of the ideal gas law, represented by xΔt1, represents the amount of gas input at a flow rate of x sccm within the first time difference Δt1. Thus, the ideal gas law can be transformed into: xΔt1=Δp1(V1+v). Similarly, considering only the second time difference Δt2, when gas is supplied to the second gas tank 13 at a flow rate of x sccm through the second gas path and fills the second volume V2+v of the second gas tank 13, the pressure change before and after the second gas tank 13 and the second gas path is the second pressure difference Δp2. Before and after the gas is introduced, the ideal gas law can be transformed into: xΔt2=Δp2(V2+v). Subtracting xΔt1=Δp1(V1+v) from xΔt2=Δp2(V2+v) eliminates the irrelevant term v of the first and second gas paths, and the first volume difference 'a' between the first volume V1+v and the second volume V2+v is known.

[0071] The calculation method for the true flow rate x of gas flow meter 11 is as follows, based on the first volume difference a, the first pressure difference Δp1, the first time difference Δt1, the second pressure difference Δp2, and the second time difference Δt2.

[0072] After the above calibration method, the true flow rate of gas flow meter 11 at a certain flow rate can be obtained. After obtaining the true flow rate of gas flow meter 11, the flow path volume of the gas source pipeline is calculated based on the true flow rate and the ventilation time. Based on the flow path volume, the gas path calibration is completed, and the true volume of the gas path is obtained.

[0073] In this embodiment, the volumes of the first gas tank 12 and the second gas tank 13 are measured using the water weight method in step S100 as the actual volumes. In other embodiments, other methods can also be used to measure the volumes of the first gas tank 12 and the second gas tank 13, as long as the actual volumes of the first gas tank 12 and the second gas tank 13 can be measured.

[0074] The calibration method for a gas flow meter 11 of the present invention involves pre-measuring the volumes of a first gas tank 12 and a second gas tank 13, and then installing the first gas tank 12 and the second gas tank 13 into a gas source pipeline. Subsequently, the gas flow meter 11 can be calibrated without removing the first gas tank 12, the second gas tank 13, or the gas flow meter 11 from the gas source pipeline. The calibration system 1 has a simple structure, and the calibration method has high calibration accuracy, achieving high-precision calibration of the gas flow meter 11.

[0075] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A calibration method for a gas flow meter, characterized in that, A calibration system is provided and connected to a gas source pipeline, the gas source pipeline including a gas source and a gas flow meter, the gas flow meter being located downstream of the gas source; the calibration system includes: a first gas tank and a second gas tank of different volumes, the first gas tank and the second gas tank being connected in parallel and connected to the gas source pipeline, the volume of a first gas path between the first gas tank and the gas source being the same as the volume of a second gas path between the second gas tank and the gas source; The calibration method includes: S10. Obtain the true volumes of the first gas tank and the second gas tank, and assemble the calibration system to calculate the true volume difference between the first gas tank and the second gas tank, which is denoted as the first volume difference. S20. Select a gas flow rate value from the range of the gas flow meter and set the gas flow rate value as the gas supply flow rate of the gas source; S30. Gas is supplied to the first gas tank through the first gas path at the gas supply flow rate until the first gas tank is full, and the gas flow meter records the first gas volume when the first gas tank and the first gas path are full; gas is supplied to the second gas tank through the second gas path at the gas supply flow rate until the second gas tank is full, and the gas flow meter records the second gas volume when the second gas tank and the second gas path are full. S40. Calculate the difference between the first gas quantity and the second gas quantity to obtain the second volume difference; S50. Compare the second volume difference with the first volume difference to obtain the deviation; S60. Determine whether the deviation is equal to zero. If the deviation is not equal to zero, proceed to step S61. Calibrate the flow reading of the gas flow meter under the gas supply flow according to the deviation, and return to step S30. If the deviation is equal to zero, the gas flow value calibration of the current gas supply flow is completed.

2. The calibration method as described in claim 1, characterized in that, Within the range of the gas flow meter, gas flow calibration points are set at intervals of 10% of the total range of the gas flow meter.

3. The calibration method as described in claim 2, characterized in that, After step S60, the following steps are also included: S70, determining whether there are any uncalibrated gas flow calibration points within the range of the gas flow meter; if so, proceeding to S71, selecting an uncalibrated gas flow value from within the range of the gas flow meter as the gas supply flow, and returning to step S30; if not, the calibration ends.

4. The calibration method as described in claim 1, characterized in that, In step S10, the actual volumes of the first gas tank and the second gas tank are measured using the water weight method.

5. A calibration method for a gas flow meter, characterized in that, A calibration system is provided and connected to a gas source pipeline, the gas source pipeline including a gas source and a gas flow meter, the gas flow meter being located downstream of the gas source; the calibration system includes: a first gas tank and a second gas tank of different volumes, the first gas tank and the second gas tank being connected in parallel and connected to the gas source pipeline, the volume of a first gas path between the first gas tank and the gas source being the same as the volume of a second gas path between the second gas tank and the gas source; The calibration method includes: S100. Obtain the true volumes of the first gas tank and the second gas tank, and assemble the calibration system to calculate the true volume difference between the first gas tank and the second gas tank, which is denoted as the first volume difference. S200: Select a gas flow rate value from the range of the gas flow meter and set the gas flow rate value as the gas supply flow rate of the gas source; S300: Supply gas to the first gas tank through the first gas path at the gas supply flow rate and fill the first gas tank, record the gas supply volume as the first volume, and measure the first gas pressure difference and the first time difference before and after the process of filling the first gas volume into the first gas tank and the first gas path; supply gas to the second gas tank through the second gas path at the gas supply flow rate and fill the second gas tank, record the gas supply volume as the second volume, and measure the second gas pressure difference and the second time difference during the process of filling the second gas tank and the second gas path with the second volume of gas. S400. Calculate the true flow rate of the gas flow meter based on the first volume difference, the first pressure difference, the first time difference, the second pressure difference, and the second time difference. Then, calibrate the reading of the gas flow meter at the current gas supply flow rate based on the true flow rate, thus completing the calibration.

6. The calibration method as described in claim 5, characterized in that, The flow path volume of the gas source pipeline is calculated based on the true flow rate, and gas path calibration is performed based on the flow path volume.

7. The calibration method as described in claim 5, characterized in that, In step S100, the actual volumes of the first gas tank and the second gas tank are measured using the water weight method.

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