Chamber air pressure calibration method and system of low-pressure plasma generator

文档序号：1859246 发布日期：2021-11-19 浏览：23次中文

阅读说明：本技术 一种低气压等离子体发生器的腔室气压校准方法及系统 (Chamber air pressure calibration method and system of low-pressure plasma generator ) 是由孙金海于 2021-09-07 设计创作，主要内容包括：本发明实施例提供了一种低气压等离子体发生器的腔室气压校准方法及系统。该方法包括：通过预设实验条件,测量低气压等离子体发生器腔室内的真实电子密度分布；其中,预设实验条件包括预设腔室气压；基于预设腔室气压,确定多个待输入腔室气压；将每一个待输入腔室气压及其它预设实验条件输入到预先构建好的仿真模型中,得到与该待输入腔室气压相对应的模拟电子密度分布；基于真实电子密度分布,在得到的多个模拟电子密度分布中确定出目标模拟电子密度分布,并将与目标模拟电子密度分布对应的待输入腔室气压作为腔室的气压。通过该方法可以精确校准等离子体发生器的腔室气压。(The embodiment of the invention provides a chamber air pressure calibration method and a chamber air pressure calibration system of a low-pressure plasma generator. The method comprises the following steps: measuring the real electron density distribution in the low-pressure plasma generator chamber through preset experimental conditions; wherein the preset experimental conditions comprise a preset chamber air pressure; determining a plurality of chamber air pressures to be input based on a preset chamber air pressure; inputting the air pressure of each chamber to be input and other preset experimental conditions into a pre-constructed simulation model to obtain simulated electron density distribution corresponding to the air pressure of the chamber to be input; and determining a target simulated electron density distribution from the obtained plurality of simulated electron density distributions based on the real electron density distribution, and taking the air pressure of the chamber to be input corresponding to the target simulated electron density distribution as the air pressure of the chamber. By the method, the chamber gas pressure of the plasma generator can be accurately calibrated.)

1. A chamber air pressure calibration method and system of a low-pressure plasma generator are characterized in that the plasma generator comprises a shell, wherein a chamber is arranged in the shell;

the method comprises the following steps:

measuring the real electron density distribution in the chamber under a preset experimental condition; wherein the preset experimental conditions comprise a preset chamber air pressure;

determining a plurality of chamber air pressures to be input based on the preset chamber air pressure; wherein the absolute value of the difference between the air pressure of the chamber to be input and the preset chamber air pressure is smaller than a first preset difference;

aiming at the air pressure of each chamber to be input, inputting the air pressure of the chamber to be input and preset experimental conditions except the preset chamber air pressure into a pre-constructed simulation model to obtain simulated electron density distribution corresponding to the air pressure of the chamber to be input;

and determining a target simulated electron density distribution in the obtained plurality of simulated electron density distributions based on the real electron density distribution, and taking the air pressure of the chamber to be input corresponding to the target simulated electron density distribution as the air pressure calibration value of the chamber.

2. The method of claim 1, wherein said measuring a true electron density distribution within said chamber comprises:

and measuring the real electron density distribution in the cavity by utilizing a Thomson scattering method.

3. The method of claim 1, wherein determining a plurality of chamber pressures to be input based on the predetermined chamber pressure comprises:

determining the fluctuation range of the air pressure of the chamber of the plasma generator according to the change direction of the air pressure by taking the air pressure of the preset chamber as a reference;

and determining a division threshold value based on the fluctuation range of the air pressure of the chamber, sequentially dividing the air pressure of a plurality of chambers to be input according to the change direction of the air pressure, wherein the absolute value of the pressure difference of the air pressure of two adjacent chambers to be input is smaller than a second preset difference value.

4. The method of claim 1, wherein the simulation model is constructed by:

and taking the axis of the plasma generator as a longitudinal axis, and sequentially constructing a cavity, a side wall of the cavity, an electric energy input device and an air layer on one side of the longitudinal axis.

5. The method of claim 1, wherein the predetermined experimental conditions include electrical parameters, a type of gas introduced into the chamber, a reaction coefficient of an electrochemical reaction, a surface reaction coefficient of a sidewall of the housing, and a material of the housing; wherein the reaction coefficient of the electrochemical reaction and the surface reaction coefficient of the side wall of the housing are both related to the type of gas introduced into the chamber.

6. The method of claim 1, wherein determining a target simulated electron density distribution among a plurality of the simulated electron density distributions based on the true electron density distribution comprises:

determining whether the absolute value of the difference between the maximum electron density in the simulated electron density distribution and the maximum electron density in the real electron density distribution is less than a third preset difference or not for each simulated electron density distribution; if yes, determining the simulated electron density distribution as a candidate simulated electron density distribution;

and calculating the difference value between the real electron density and the simulated electron density corresponding to each position of the measured electron density according to each candidate simulated electron density distribution, and determining the target simulated electron density distribution in the obtained candidate simulated electron density distribution based on the average value or mean square difference of the difference values corresponding to the positions of all the measured electron densities.

7. The method according to any one of claims 1 to 6, further comprising, after the setting of the chamber atmospheric pressure to be input corresponding to the target simulated electron density distribution as the atmospheric pressure of the chamber:

changing the preset chamber air pressure of the preset experimental condition, and continuing to measure the real electron density distribution in the chamber until the air pressure of the chamber under the experimental condition is obtained;

and aiming at each experimental condition, drawing a relation graph of the maximum electron density and the air pressure of the chamber based on the maximum electron density in the real electron density distribution corresponding to the experimental condition and the air pressure of the chamber.

8. A system for calibrating chamber gas pressure of a plasma generator, comprising:

a plasma generator comprising a housing having a chamber therein;

the electron density measuring device is used for measuring the real electron density distribution in the cavity under the preset experimental condition; wherein the preset experimental conditions comprise a preset chamber air pressure;

the simulation equipment is provided with a pre-constructed simulation model;

the simulation device is configured to perform:

acquiring the air pressure of a plurality of chambers to be input; wherein the absolute value of the difference between the air pressure of the chamber to be input and the preset chamber air pressure is smaller than a first preset difference;

inputting the air pressure of the chamber to be input and preset experimental conditions except the preset chamber air pressure into the simulation model aiming at the air pressure of each chamber to be input to obtain the simulated electron density distribution corresponding to the air pressure of the chamber to be input;

and determining a target simulated electron density distribution from the obtained plurality of simulated electron density distributions based on the real electron density distribution, and taking the air pressure of the chamber to be input corresponding to the target simulated electron density distribution as the air pressure of the chamber.

9. The system of claim 8, wherein the simulation device, when executing the determining of the target simulated electron density distribution among the plurality of simulated electron density distributions based on the real electron density distribution, is configured to execute the following steps:

10. The system of claim 8, wherein the simulation device is further configured to perform:

Technical Field

The invention relates to the technical field of plasma generators, in particular to a chamber air pressure calibration method and system of a low-pressure plasma generator.

Background

The electron density produced by the plasma generator is primarily affected by parameters such as the input electrical parameters (e.g., power or current) and the chamber gas pressure within the plasma generator. Therefore, in order to achieve a controllable density of electrons generated by the plasma generator, it is necessary to ensure accurate control of the input electrical parameters and the chamber gas pressure.

Generally, the input electrical parameters can achieve more accurate measurement, and the measurement of the chamber air pressure has certain errors.

Therefore, there is a need for a method for calibrating the chamber pressure of a plasma generator to solve the above problems.

Disclosure of Invention

The invention provides a chamber air pressure calibration method and a chamber air pressure calibration system of a low-pressure plasma generator, which can accurately correct the chamber air pressure in the plasma generator.

In a first aspect, an embodiment of the present invention provides a method for calibrating a chamber gas pressure of a plasma generator, including:

measuring the real electron density distribution in the chamber under a preset experimental condition; wherein the preset experimental conditions comprise a preset chamber air pressure;

In one possible design, the measuring the true electron density distribution within the chamber includes:

and measuring the real electron density distribution in the cavity by utilizing a Thomson scattering method.

In one possible design, the determining the plurality of chamber pressures to be input based on the preset chamber pressure includes:

In one possible design, the simulation model is constructed by:

In one possible design, the predetermined experimental conditions include electrical parameters, types of gases introduced into the chamber, reaction coefficients of electrochemical reactions, surface reaction coefficients of the side walls of the housing, and materials of the housing; wherein the reaction coefficient of the electrochemical reaction and the surface reaction coefficient of the side wall of the housing are both related to the type of gas introduced into the chamber.

In one possible design, the determining a target simulated electron density distribution among the plurality of simulated electron density distributions based on the true electron density distribution includes:

In one possible design, after the setting the chamber gas pressure to be input corresponding to the target simulated electron density distribution as the chamber gas pressure, the method further includes:

changing the preset chamber air pressure under the preset experimental condition, continuously executing the step of measuring the real electron density distribution in the chamber, and circulating the steps of simulating, comparing the electron density and the like until the air pressure calibration value of the chamber under the experimental condition is obtained;

and for each experimental condition, drawing a relation graph of the maximum electron density and the air pressure of the chamber based on the maximum electron density in the real electron density distribution corresponding to the experimental condition and the air pressure calibration value of the chamber.

In a second aspect, an embodiment of the present invention further provides a system for calibrating chamber gas pressure of a plasma generator, including:

a plasma generator comprising a housing having a chamber therein;

the simulation equipment is provided with a pre-constructed simulation model;

the simulation device is configured to perform:

In one possible design, the simulation device is configured to, when determining a target simulated electron density distribution among a plurality of simulated electron density distributions based on the real electron density distribution, perform the following steps:

In one possible design, the simulation device is further configured to perform:

The embodiment of the invention provides a chamber air pressure calibration method and a chamber air pressure calibration system of a low-pressure plasma generator, the method measures the real electron density distribution in a chamber of the plasma generator through preset experimental conditions, determines the air pressures of a plurality of chambers to be input based on the preset chamber air pressure, inputs the air pressure of each chamber to be input and other preset experimental conditions into a pre-constructed simulation model to obtain the simulated electron density distribution corresponding to the air pressure of the chamber to be input, determines the target simulated electron density distribution from the plurality of simulated electron density distributions based on the real electron density distribution, uses the air pressure of the chamber to be input corresponding to the target simulated electron density distribution as the chamber air pressure calibration value of the plasma generator, and can accurately calibrate the chamber air pressure of the plasma generator by the method.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a flow chart of a method for calibrating chamber pressure of a plasma generator according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a simulation model provided in accordance with an embodiment of the present invention;

FIG. 3 is a schematic view of electron density distribution corresponding to a certain chamber pressure according to one embodiment of the present invention;

FIG. 4 is a schematic diagram illustrating a comparison of an experimentally measured axial electron density distribution with a simulated axial electron density distribution at a certain chamber pressure according to an embodiment of the present invention;

FIG. 5 is a schematic diagram illustrating a comparison between experimentally measured radial electron density distribution and simulation calculated radial electron density distribution at a certain chamber pressure according to an embodiment of the present invention;

FIG. 6 is a graph of maximum electron density at 350W of electrical power versus chamber gas pressure provided by an embodiment of the present invention.

Reference numerals:

1-chamber, 2-side wall of chamber, 3-inductance coil, 4-air layer.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer and more complete, the technical solutions in the embodiments of the present invention will be described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention, and based on the embodiments of the present invention, all other embodiments obtained by a person of ordinary skill in the art without creative efforts belong to the scope of the present invention.

As previously mentioned, the electron density produced by the plasma generator is primarily affected by parameters such as the input electrical parameters (e.g., power or current) and the chamber gas pressure within the plasma generator. Therefore, in order to achieve a controllable density of electrons generated by the plasma generator, it is necessary to ensure accurate control of the input electrical parameters and the chamber gas pressure.

Generally, the input electrical parameters allow for more accurate measurements, since the vacuum gauge measuring the pressure in the chamber of the plasma generator is located outside the chamber of the plasma generator. Therefore, the pressure value measured by the vacuum gauge is different from the real chamber pressure of the plasma generator.

In order to solve this problem, it is conceivable to use a simulation calculation method to calibrate the chamber pressure of the plasma generator.

Specific implementations of the above concepts are described below.

Referring to fig. 1, an embodiment of the invention provides a method for calibrating chamber pressure of a plasma generator, the method comprising:

step 100, measuring the real electron density distribution in a plasma generator chamber under a preset experimental condition; wherein the preset experimental conditions comprise a preset chamber air pressure;

step 102, determining a plurality of chamber air pressures to be input based on preset chamber air pressures; the absolute value of the difference value between the air pressure of the chamber to be input and the preset chamber air pressure is smaller than a first preset difference value;

104, inputting the air pressure of the chamber to be input and preset experimental conditions except the preset chamber air pressure into a pre-constructed simulation model aiming at the air pressure of each chamber to be input to obtain simulated electron density distribution corresponding to the air pressure of the chamber to be input;

and 106, determining a target simulated electron density distribution from the obtained simulated electron density distributions based on the real electron density distribution, and taking the air pressure of the chamber to be input corresponding to the target simulated electron density distribution as the air pressure of the chamber.

In the embodiment of the invention, the real electron density distribution of the plasma generator is measured by an experimental method; establishing a simulation model of the plasma generator based on experimental conditions, determining the air pressure of a plurality of chambers to be input based on the air pressure of the experimental chambers, inputting the air pressure of each chamber into the simulation model to participate in calculation, and obtaining a plurality of simulated electron density distributions; and determining a target simulated electron density distribution by comparing the real electron density distribution with the simulated electron density distribution, wherein the chamber air pressure corresponding to the simulated electron density distribution is regarded as the chamber air pressure of the plasma generator. By the method, the chamber gas pressure of the plasma generator can be accurately calibrated.

The above steps will be described separately below.

With respect to step 100, in some embodiments, the true electron density distribution within the plasma generator chamber may be measured, for example, using thomson scattering.

The tomsung scattering spectrum carries information of plasma fluctuation, and the electron density in the plasma can be measured with high precision by measuring the tomsung scattering spectrum, so that the electron density distribution is obtained. Therefore, the electron density distribution obtained by thomson scatterometry can be considered as the true electron density distribution within the plasma generator chamber.

There are various methods for measuring the electron density of plasma, and for example, a barman spectroscopy method, a spectroscopic intensity method, an optical scattering method, an optical faraday rotation method, a laser beat method, a microwave resonator method, a microwave scattering method, a high-frequency conductivity probe method, and the like can be used. Different measurement methods can be selected for different ranges of electron density, and are not particularly limited herein.

With respect to step 102, in some embodiments, step 102 comprises:

determining the fluctuation range of the air pressure of the chamber of the plasma generator according to the change direction of the air pressure by taking the preset chamber air pressure as a reference;

In this embodiment, the chamber air pressure to be input is determined based on the change direction of the air pressure, so that the chamber air pressure to be input can more easily cover the real chamber air pressure, that is, the real chamber air pressure can be quickly found in the determined chamber air pressure to be input, and the workload of simulation calculation can be reduced.

Wherein the direction of change of the gas pressure is related to the position of the device for measuring the gas pressure, such as a vacuum gauge, in the chamber of the plasma generator. For example, if a vacuum gauge corresponding to a preset chamber pressure is located at the inlet end of the plasma generator chamber, the preset chamber pressure is the maximum value of the chamber pressure of the plasma generator, and if the vacuum gauge displays that the chamber pressure is 70Pa, the fluctuation range of the chamber pressure is determined to be 50-70 Pa; on the contrary, if the vacuum gauge corresponding to the preset chamber pressure is located at the tail end of the plasma generator chamber, the preset chamber pressure is the minimum value of the plasma generator chamber pressure, and if the vacuum gauge displays that the chamber pressure is 70Pa, the fluctuation range of the chamber pressure is determined to be 70-90 Pa; in the pressure fluctuation range of the chamber, the dividing threshold value is 0.5Pa, and 40 air pressures of the chamber to be input are obtained.

With respect to step 104, in some embodiments, as shown in fig. 2, the simulation model mentioned in step 104 is a two-dimensional axisymmetric structure, and the grid lines in fig. 2 correspond to the scale of the abscissa and the ordinate. Specifically, the simulation model takes the axis of the plasma generator as a longitudinal axis, and a cavity 1, a side wall 2 of the cavity, an inductance coil 3 and an air layer 4 are sequentially constructed on one side of the longitudinal axis; the inductance coil 3 is an electric energy input device, and in other simulation models, the inductance coil can be replaced by positive and negative electrodes.

In the embodiment, a two-dimensional axisymmetric simulation model is constructed based on the plasma generator as an axisymmetric structure, after the simulation is finished, the electron density distribution of a section plane is obtained, and the electron density distribution of the whole plasma generator chamber can be obtained by rotating 360 degrees by taking the symmetric axis as a reference point. Therefore, the two-dimensional model is not only simple and effective, but also can reduce simulation time. The air layer 4 is provided to facilitate effective closing and meshing of the magnetic induction lines generated by the induction coil 3.

It should be noted that, although the modeling simulation is performed only for the Inductively Coupled Plasma (ICP) generator, the embodiment is not to be construed as a limitation to the simulation model. For example, for Capacitively Coupled Plasma (CCP) simulation, positive and negative electrodes can be used as electric energy input devices (instead of inductance coils) when a simulation model is built; for example, in dielectric barrier discharge plasma (DBD) simulation, positive and negative electrodes can be used as electric energy input devices (instead of inductance coils) when a simulation model is built, and the side wall of a cavity is used as a barrier dielectric layer; also for example, helicon wave plasma simulation, a helicon wave antenna can be used as the power input device (instead of an inductor). In summary, it is within the scope of the present invention to utilize simulation methods to realize low-pressure plasma simulation of electron density measurement. It should be noted that, in order to ensure the real effectiveness of the simulated electron density distribution obtained by the simulation model as much as possible, the parameters such as the size of the chamber, the thickness of the sidewall of the chamber, the number of turns of the inductance coil, and the electric power input to the simulation model should be consistent with the preset experimental conditions.

In some embodiments, the predetermined experimental conditions include electrical parameters, the type of gas introduced into the chamber, the reaction coefficient of the electrochemical reaction, the surface reaction coefficient of the sidewall of the housing, and the material of the sidewall of the chamber; wherein the reaction coefficient of the electrochemical reaction and the surface reaction coefficient of the side wall of the housing are both related to the type of gas introduced into the chamber.

For example, the electric power is 350W, and argon is used as the ionized gas, 7 electrochemical reaction coefficients and 3 reaction coefficients of surface reaction at the side wall contact position need to be input in the simulation model in advance to ensure the consistency of the initial condition and the experimental condition of the simulation model, so as to ensure the accuracy of the simulation calculation result.

It should be noted that, in this embodiment, only argon is taken as an example, the parameter types that need to be set in the model construction are given, and the parameter types that need to be input into the simulation model for other gases, such as hydrogen, oxygen, etc., also include the reaction coefficient of the electrochemical reaction and the surface reaction coefficient of the side wall of the housing, which are not listed in this application.

In some embodiments, the step of "obtaining a simulated electron density distribution corresponding to the pressure of the chamber to be input" specifically comprises:

setting a sampling interval, acquiring the electron density in the plasma generator once every other sampling interval after the simulation is started, obtaining the electron density distribution in the plasma generator, comparing the electron density distribution with the electron density distribution obtained in the previous sampling interval, and considering that the plasma reaction in the plasma generator has reached a steady state when the electron density distribution obtained in two adjacent intervals is not changed any more;

at this time, the electron density distribution in the plasma generator obtained under the steady state condition is taken as a simulated electron density distribution corresponding to the gas pressure to be input into the chamber (see fig. 3).

In this embodiment, the transient change of the plasma reaction can be obtained by a computer sampling method, so as to determine the convergence time of the plasma reaction, obtain the simulated electron density under the steady-state condition, and end the calculation.

With respect to step 106, in some embodiments, step 106 includes:

In the embodiment, the candidate simulated electron density distribution is screened out by the maximum electron density in the simulated electron density distribution, so that the calculation time for determining the target simulated electron density distribution is reduced, and the calculation efficiency is improved; and then, the average value or mean square error of the difference values corresponding to all the positions for measuring the electron density is beneficial to determining the candidate simulated electron density distribution with highest stability or minimum error, so that the target simulated electron density distribution can be determined.

In some embodiments, the step of determining a target simulated electron density distribution among the obtained candidate simulated electron density distributions based on a mean or mean square error of differences corresponding to positions of all measured electron densities comprises:

and taking the candidate simulated electron density distribution with the minimum mean value or mean square error of the difference values corresponding to all the positions of the measured electron density as the target simulated electron density distribution.

Among them, the reason for screening out the candidate simulated electron density distribution by the maximum electron density in the simulated electron density distribution is that: referring to fig. 4 and 5, it can be seen that the maximum of the electron density occurs at the center point of the plasma generator, which is mainly determined by the axisymmetric structure of the plasma generator. Therefore, when the target simulated electron density distribution is determined, the maximum electron density is taken as a comparison standard, and the screening difficulty can be reduced.

In some embodiments, after step 106, further comprising:

changing the preset chamber air pressure under the preset experimental condition, and continuously measuring the real electron density distribution in the chamber until the air pressure of the chamber under the experimental condition is obtained;

for each experimental condition, the maximum electron density and the gas pressure of the chamber are plotted based on the maximum electron density in the real electron density distribution corresponding to the experimental condition and the gas pressure of the chamber (see fig. 6).

In this embodiment, after the electron density in the chamber is measured, the actual gas pressure in the chamber can be quickly determined from the relationship between the maximum electron density and the gas pressure in the chamber.

It should be noted that the electron density distribution in the plasma generator is not uniform and shows a distinct spatially symmetric distribution. Therefore, it is reasonably efficient to select the maximum electron density mapping chamber pressure. Wherein the chamber gas pressure and the maximum electron density within the chamber are linear in figure 6.

The embodiment of the invention also provides a calibration system for the chamber air pressure of the plasma generator, which comprises the following components:

the simulation equipment is provided with a pre-constructed simulation model;

an emulation device for performing:

acquiring the air pressure of a plurality of chambers to be input; the absolute value of the difference value between the air pressure of the chamber to be input and the preset chamber air pressure is smaller than a first preset difference value;

inputting the air pressure of the chamber to be input and preset experimental conditions except the preset chamber air pressure into a simulation model aiming at the air pressure of each chamber to be input to obtain simulated electron density distribution corresponding to the air pressure of the chamber to be input;

In some embodiments, the simulation model in the simulation apparatus is a two-dimensional axisymmetric structure, and the simulation model sequentially constructs the chamber 1, the sidewall 2 of the chamber, the induction coil 3, and the air layer 4 on one side of the longitudinal axis with the axis of the plasma generator as the longitudinal axis.

The simulation model in the simulation apparatus is modeled and simulated only for the Inductively Coupled Plasma (ICP) generator, but is not to be construed as limiting the simulation apparatus. As described in the calibration method, a low-pressure plasma simulation apparatus as long as electron density measurement can be achieved by using a simulation method falls within the scope of the present invention.

In some embodiments, the preset experimental conditions of the simulation model in the simulation apparatus include electrical parameters, the type of gas introduced into the chamber, the reaction coefficient of the electrochemical reaction, the surface reaction coefficient of the sidewall of the housing, and the material of the sidewall of the chamber; wherein the reaction coefficient of the electrochemical reaction and the surface reaction coefficient of the side wall of the housing are both related to the type of gas introduced into the chamber.

In some embodiments, the simulation device, when performing the step of determining the target simulated electron density distribution among the plurality of simulated electron density distributions based on the real electron density distribution, is configured to perform the steps of:

In some embodiments, the simulation device is further configured to perform:

and drawing a relation graph of the maximum electron density and the air pressure of the chamber according to each experimental condition based on the maximum electron density in the real electron density distribution corresponding to the experimental condition and the air pressure of the chamber.

Since the embodiments of the calibration system and the embodiments of the method of the present invention are based on the same concept, specific contents may be referred to the descriptions of the embodiments of the method of the present invention, and are not described herein again.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an …" does not exclude the presence of other similar elements in a process, method, article, or apparatus that comprises the element.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

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Chamber air pressure calibration method and system of low-pressure plasma generator

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