JP2010232110A - Measurement method and measuring device capable of measuring electron density and/or electron collision frequency of high-pressure plasma - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a measurement method and a measuring device capable of measuring the electron density and/or electron collision frequency of high-frequency plasma, without using an expensive measuring device. <P>SOLUTION: With the measurement method of electron density and electron collision frequency of high-pressure plasma and a plasma characteristics measurement device 1, a probe 10 is inserted into high-pressure plasma P and is supplied with high-frequency power, while the probe 10 sweeps high frequencies by a high-frequency oscillator 21. A spectrum of a reflection coefficient obtained from power reflected from the probe 10 is measured with a reflection coefficient spectrum display part 25 for detecting the resonance spectrum of the probe 10; a resonance frequency and a half-value width of resonance are calculated from the resonance spectrum; and based on the resonance frequency and the half-value width of resonance, the electron density and/or the electron collision frequency of the high-pressure plasma can be calculated at a plasma characteristics calculating part 26. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a method and an apparatus for measuring electron density and / or electron collision frequency of high-pressure plasma having a pressure exceeding 1 Torr.

Conventionally, plasma processing for performing CVD (chemical vapor deposition), etching, and the like has been widely performed in manufacturing processes of semiconductor devices. Diagnosis of plasma parameters is one of the basic requirements for monitoring plasma processing. Active particles that determine material processes are mainly generated by electron impact reactions with neutral particles (for example, excitation, ionization, dissociation, etc.), so the electron density is measured, and the size, spatial distribution, and changes over time are ascertained. It is important to control and measure the electron collision frequency. For low-pressure discharge plasma, various electron density analysis tools have been developed. As such an electron density analysis tool, for example, when a metal probe is directly exposed to plasma and a DC bias voltage or a DC bias voltage superimposed with a high frequency voltage is applied to a metal probe, A Langmuir probe method for obtaining an electron density based on the value of a current flowing through a metal probe is widely known. Various probes for measuring the electron density from the resonance frequency of the microwave band have also been proposed. For example, Non-Patent Document 1 discloses an electron density measurement method using a resonance phenomenon of electromagnetic waves by a metal antenna. . Patent Document 1 discloses a microwave interference method for obtaining an electron density based on a phase difference between a microwave such as a monochromatic laser beam propagating in plasma and a microwave propagating in the atmosphere.
R. B. Piejak, V.M. A. Godyak, R .; Gamer and B.M. M.M. Alexandrovich, N .; Stemberg, J.M. APPl. Phys. 95,3785 (2004) Japanese Patent Laid-Open No. 6-253871

In recent years, plasma processing using high-pressure plasma such as atmospheric pressure plasma has been proposed. For example, plasma processing using atmospheric pressure plasma does not require a high vacuum state in a chamber in which plasma is generated and processed, so that the configuration of the plasma processing apparatus can be simplified and manufacturing costs can be reduced. it can. On the other hand, since such high-pressure plasma tends to become unstable because it tends to transition to arc-shaped filament discharge, it is important to grasp the state of plasma such as electron density in order to maintain it in a desired state. It becomes. However, the Langmuir probe method is beyond the scope of the probe theory that has been proposed in the past, and when used in a material process, there is a risk that the surface of the probe will be contaminated by the formation of plasma. Had a problem that it was difficult to apply. In the measurement using the probe for measuring the resonance frequency of the microwave band, when the plasma reaches a high pressure exceeding 1 Torr, the resonance spectrum expands, so that the accuracy of the measurement value of the resonance frequency decreases, or when the plasma exceeds 30 Torr, Since the resonance frequency does not depend on the electron density of the plasma, there is a problem that it cannot be applied to the measurement of high pressure plasma. Microwave interferometry has the following problems: a large window for transmitting microwaves must be provided in the chamber, the plasma size must be large, the spatial resolution is poor, and the measuring device is expensive. .
Other methods, such as the laser Thomson scattering method, have a problem that the measuring apparatus is expensive.

Therefore, an object of the present invention is to realize a measurement method and a measurement apparatus that can measure the electron density and / or electron collision frequency of high-pressure plasma without using an expensive measurement apparatus.

In order to achieve the above object, according to the first aspect of the present invention, in the method for measuring the electron density and / or electron collision frequency of high-pressure plasma, a probe acting as a resonant antenna in the microwave region is provided in the plasma. The high frequency power is supplied to the probe while sweeping the frequency, the resonance frequency and the half width of resonance are measured from the spectrum of the reflection coefficient obtained by the power reflected from the probe, and the resonance frequency and resonance are measured. The technical means of calculating the electron density and / or the electron collision frequency of the high-pressure plasma based on the half-value width is used.

According to the first aspect of the present invention, the probe acting as a resonance antenna in the microwave region is inserted into the plasma, and the high frequency power is supplied while sweeping the frequency to the probe, which is obtained by the power reflected from the probe. The resonance frequency and the half width of resonance are measured from the spectrum of the reflection coefficient. Since the half width of resonance changes sensitively to the electron density and electron collision frequency of high pressure plasma, the electron density and electron collision frequency of high pressure plasma are accurately measured based on the resonance frequency and half width of resonance. can do. The probe can be formed from a metal wire having a length of about several centimeters, for example, and is small in size, has a spatial resolution, and can be measured by a simple operation using, for example, a commercially available network analyzer. The electron density and electron collision frequency of high pressure plasma can be measured without using a large measuring device. Here, the high pressure plasma means plasma having a pressure of 1 Torr or more.

According to a second aspect of the present invention, in the method for measuring the electron density and / or electron collision frequency of the high-pressure plasma according to the first aspect, the half width of the resonance of the probe and the resonance frequency when no plasma is generated. A technical means is used in which the electron density is calculated based on the ratio of the half-value width of resonance of the probe in the plasma and the resonance frequency, corrected by the ratio.

As an error factor of the measured electron density, there is radiation loss of electromagnetic waves from the probe, and the half width does not become zero even in the absence of plasma. In the invention according to claim 2, in order to correct the ratio between the half width obtained from the resonance spectrum of the probe in the plasma and the resonance frequency by the ratio between the half width when the plasma is not generated and the resonance frequency, The above-mentioned error factor is eliminated, and a more accurate electron density can be measured.

According to a third aspect of the present invention, in the method for measuring the electron density and / or electron collision frequency of high-pressure plasma, two probes having different lengths acting as resonant antennas in the microwave region are inserted into the plasma. The high frequency power is supplied to each probe while sweeping the frequency, and the resonance frequency and the half width of the resonance are measured from the spectrum of each reflection coefficient obtained by the power reflected from each probe. A technical means of calculating the electron density and / or the electron collision frequency of the high pressure plasma based on the frequency and the half width of the resonance is used.

According to the invention described in claim 3, the same effect as that of the invention described in claim 1 can be obtained. Further, the measurement error due to one probe increases as the plasma pressure increases, but the measurement accuracy can be remarkably improved by using two probes having different lengths.

According to a fourth aspect of the present invention, in the apparatus for measuring electron density and / or electron collision frequency of high pressure plasma, a probe inserted in a high pressure plasma atmosphere and acting as a resonant antenna in a microwave region, A high-frequency oscillator that is electrically connected via a coaxial cable and supplies high-frequency power while sweeping the frequency, and a spectrum of a reflection coefficient obtained by the power reflected from the probe is measured to detect a resonance characteristic of the probe Resonance spectrum detection unit, and calculating resonance frequency and half width of resonance from resonance characteristics detected by resonance spectrum detection unit, and based on resonance frequency and half width of resonance, electron density of high pressure plasma and / or A technical feature that includes a plasma characteristic calculator for calculating the electron collision frequency. It is used.

According to the fourth aspect of the present invention, a probe that acts as a resonant antenna in the microwave region is inserted into a high-pressure plasma atmosphere, and a high-frequency power is supplied to the probe while sweeping the frequency by a high-frequency oscillator to detect a resonance spectrum. The spectrum of the reflection coefficient obtained by the power reflected from the probe is measured by the unit, the resonance spectrum of the probe is detected, and the resonance spectrum detection unit calculates the resonance frequency and the half width of the resonance from the detected resonance characteristics. The plasma characteristic calculation unit can calculate the electron density and / or the electron collision frequency of the high pressure plasma based on the resonance frequency and the half width of the resonance. Since the half width of resonance changes sensitively to the electron density and electron collision frequency of high pressure plasma, the electron density and electron collision frequency of high pressure plasma are accurately measured based on the resonance frequency and half width of resonance. can do. The probe can be formed from a metal wire having a length of about several centimeters, for example, and is small in size, has a spatial resolution, and can be measured by a simple operation using, for example, a commercially available network analyzer. The electron density and electron collision frequency of high pressure plasma can be measured without using a large measuring device. Here, the high pressure plasma means plasma having a pressure of 1 Torr or more.

According to a fifth aspect of the present invention, in the apparatus for measuring the electron density and / or electron collision frequency of the high pressure plasma according to the fourth aspect, the probe is formed of a U-shaped metal conductor. Use appropriate means.

According to the invention described in claim 5, a probe formed of a U-shaped metal conductor is employed as the probe. A U-shaped probe can be preferably used because a port for insertion into a chamber where plasma is generated can be made smaller than a T-shaped probe or the like.

According to a sixth aspect of the present invention, the high pressure plasma electron density and / or electron collision frequency measuring device according to the fourth or fifth aspect is provided with two probes having different lengths. Use appropriate means.

According to the invention described in claim 6, by using two probes having different lengths, a measurement error at a high pressure can be significantly suppressed as compared with the measurement using one probe.

A plasma density measuring apparatus and a plasma density measuring method according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram of a plasma processing apparatus and a plasma density measuring apparatus. FIG. 2 is an explanatory view showing the outer shape of the probe. FIG. 3 is an explanatory view showing a method of connecting the probe and the coaxial cable.

As shown in FIG. 1, the plasma density measuring apparatus 1 includes a probe 10 attached inside a chamber 31 of a plasma processing apparatus 30, and a probe control apparatus 20 connected to the probe 10 and disposed outside the chamber 31. And.

The plasma processing apparatus 30 includes a chamber 31 having a plasma P generated by a high frequency power source and an object to be processed therein, and a control unit 32 that controls a plasma density control factor such as high frequency power.

The probe 10 is attached to the inside of the chamber 31 and the rear end is connected to the probe control device 20 by a coaxial cable. A specific configuration will be described later.

The probe control device 20 includes a frequency sweep type high frequency oscillator 21, a directional coupler 22, an attenuator 23, a filter 24, a reflection coefficient spectrum display unit 25, and a plasma characteristic calculation unit 26. Each is connected as shown in FIG.

The high frequency oscillator 21 supplies power while sweeping the frequency from a predetermined frequency range, for example, 100 kHz to 3 GHz. The high frequency power output from the high frequency oscillator 21 is applied to the probe 10 through the directional coupler 22, the attenuator 23, and the filter 24. The high frequency power output from the high frequency oscillator 21 is sent to the reflection coefficient spectrum display unit 25, and the frequency is sent to the plasma characteristic calculation unit 26.

The directional coupler 22 detects a change in the reflectance frequency due to the high-frequency power plasma supplied from the probe 10 and outputs the change to the reflection coefficient spectrum display unit 25.

The attenuator 23 adjusts the amount of high frequency power for measurement fed into the probe 10. The filter 24 removes high-frequency signal noise for plasma excitation mixed into the probe control unit 20 via the probe 10.

The reflection coefficient spectrum display unit 25 detects a frequency change of the reflectance of the probe 10 as a resonance spectrum.

The plasma characteristic calculation unit 26 obtains the resonance frequency and the half-value width of resonance based on the resonance spectrum transmitted from the reflection coefficient spectrum display unit 25, and based on these, the electron density and the electron collision frequency are calculated based on the measurement principle described later. calculate.

The probe 10 uses a metal antenna that utilizes the resonance phenomenon of electromagnetic waves. In this embodiment, as shown in FIG. 2, a U-shaped probe (hairpin probe) in which two metal wires having a diameter 2a and a length l are arranged in parallel with a distance d apart and connected in a U-shape at one end. Is adopted. Such a U-shaped probe can be handled as two parallel long transmission lines (parallel two-wire model). The probe 10 can be formed of, for example, stainless steel. In addition, if it is made of a corrosion-resistant metal such as gold, platinum, tungsten, molybdenum, and tantalum, it can hardly be corroded by plasma and can extend its life. The probe 10 can be coated with glass, ceramics, or the like. Thereby, it is hard to receive the corrosion by a plasma and can extend a lifetime. Further, in the material process, the probe 10 can be prevented from releasing metal impurities and contaminating the plasma atmosphere.

In the probe 10, the distance d between the two metal wires is preferably set sufficiently larger than the sheath thickness determined by the plasma density and the electron temperature. The length l of the metal wire is set based on conditions such as the plasma density to be measured and the measurement accuracy.

In the probe 10, the tip and the bottom of the core conductor 11b of the coaxial cable 11 are connected by an arc-shaped lead wire 11a. Furthermore, the bottom is connected to the outer conductor 11 c of the coaxial cable 11. The other end of the coaxial cable 11 is connected to the probe control device 20.

When high frequency power is supplied to the probe 10 while sweeping the frequency by the high frequency oscillator 21, it is used to excite the probe 10 with the arc-shaped lead wire 11 a, and electromagnetic waves are excited, and the excited electromagnetic waves are emitted to the plasma P. Is done. The rest returns from the coaxial cable 11 to the probe controller 20 as reflected power.

The reflected power is detected by the directional coupler 22 as a change in the frequency of the reflectance due to the high-frequency power plasma supplied from the probe 10, and the reflection coefficient spectrum display unit 25 detects the change in the frequency of the reflectance as a resonance spectrum (for example, The resonance spectrum is detected as shown in FIG.

Then, in the plasma characteristic calculation unit 26, and the resonance frequency f _r the reflected power decreases resonantly, seek, and half-value width Δf of the resonance peak, on the basis of these, the electron density n _e or electron collision frequency in the plasma ν _m is calculated. Note that when there are no negative ions in the plasma, the electron density is equal to the plasma density.

When the U-shaped probe shown in FIG. 2 is regarded as a parallel two-wire transmission line having a length l and inserted into a plasma having an electron density ne and an electron collision frequency ν _m , a resonance frequency f causing half-wave dipole resonance. _{When r} and the half width Df of resonance are obtained, the following expression 1 is obtained. Where c is the speed of light, ε ₀ is the dielectric constant of vacuum ε _pr is the dielectric constant of the plasma, ω _p is the electron plasma angular frequency determined by the electron density, and ν _m is determined by the gas type, pressure and electron temperature used for the discharge. Electron collision frequency.

Here, c / 4l = f _{0 is set} , and when the electron collision frequency and the electron plasma angular frequency are obtained from Equation 1 and Equation 2 and arranged, the following relational expression is obtained.

When the values of f _r , f ₀ , and Δf are obtained from the measurement of the resonance spectrum and substituted into Equation 4, the value of the collision frequency ν _m is determined. Substituting it into Equation 5, the value of ω _p ² is determined. Furthermore, by substituting this value into the following equation 6, the electron density _ne (m ⁻³ ) can be obtained using the MKS unit system. [Measurement method A]

In the parallel two-wire transmission line model described above, the radiation of electromagnetic waves from the transmission line is not considered. The actually measured resonance characteristic of the probe has a half-width spread due to this radiation loss, and the half-width does not become zero even in the absence of plasma. In order to correct this, a value obtained by subtracting the ratio of the half-value width Δf and the resonance frequency f ₀ when there is no plasma from the ratio of the half-value width Δf actually measured in the plasma and the resonance frequency f _r is defined by Expression 7.

Since this value is considered to be the value on the left side of Equation 3 obtained by the transmission line model, when ν _m is given in GHz, the probe length l is given in mm, and the electron density (m ⁻³ ) is obtained, Equation 8 is obtained. can get.

Therefore, the ratio Δf / f ₀ between the half-value width and the resonance frequency when no plasma is generated in advance is obtained, and this is subtracted from the ratio Δf / f _r between the half-value width and the resonance frequency in the plasma. The plasma density can be calculated using Equation 8. [Measurement method B]

Note that the electron collision frequency data is required to calculate the electron density using Equation 8. For some representative gas species, the data is examined as a function of electron temperature. For gas types that do not have such a database, the electron collision frequency can be approximately calculated from the following equation (9). Here, in Equation 9, r is the radius of gas molecules given in units of 10 ⁻¹⁰ m, the electron temperature Te is given in eV, and the pressure p is given in units of Torr.

Since the radiation loss of the electromagnetic wave from the probe is usually not so large, it is possible to calculate the electron collision frequency only from the measured value of the resonance spectrum using Equation 4. However, at a more high pressure 10 Torr, the resonance frequency f _r is to approach the value f ₀ in the absence of plasma, measurement error increases. Therefore, a method for obtaining the electron collision frequency and the electron density with higher accuracy by using two probes having different lengths is proposed below.

Assuming that the resonance frequencies measured by the two probes of lengths l ₁ and l ₂ are f ₁ and f ₂ and the resonance widths are Δf ₁ and Δf ₂ , respectively, Two relational expressions are obtained.

If the experimental value is substituted into the right side of Equation 10 to obtain the value of the collision frequency ν _m and is substituted into Equation 11, the value of ω _p ² is determined. By substituting this value into Equation 6, the electron density can be obtained. [Measurement method C]

The plasma characteristic calculator 26 is connected to the controller 32 of the plasma generator 30, and the electron density calculated by the plasma density calculator 26 is sent to the controller 32. Based on the measured plasma density, the control unit 32 can control factors that dominate the plasma state, such as high-frequency power for plasma generation (high-frequency power) and gas pressure.

(Example)
As described above, the probe that causes microwave resonance is analyzed as a parallel two-wire transmission line, and based on the results, three types of measurements are performed to obtain the electron density _ne and the electron collision frequency ν _m from the measured values of the resonance spectrum of the probe. The law (A, B, C) is described. In order to show the validity of this method, it will be described below that the resonance characteristics of the probe are obtained from electromagnetic field simulation by giving the electron density _ne and the electron collision frequency ν _m in advance and are well matched with the prediction by the transmission line model. Note that the measurement method, measurement conditions, and the like of the present invention are not limited to the example of the simulation performed.

The example of the resonance spectrum obtained by the electromagnetic field simulation is shown. Resonance characteristics of a probe when a U-shaped probe of a = 1 mm, d = 4 mm, and l = 27 mm is used and the probe is placed in a uniform plasma having a given electron density, electron temperature, and argon gas pressure. Was investigated by performing electromagnetic field simulation. An example of the resonance spectrum obtained by the simulation is shown in FIG. Here, a resonance spectrum is shown when the electron density _ne = 3 × 10 ¹⁶ m ⁻³ , the electron temperature Te = 0.5 eV is constant, and the pressure p (Torr) is changed.

The behavior of the resonance spectrum differs between low-pressure plasma having a pressure of 10 Torr or less and high-pressure plasma having a pressure of 50 Torr or more. In the low-pressure plasma having a pressure of 10 Torr or less, the resonance frequency is about 2.89 GHz, and the peak of the resonance spectrum tends to become broader as the pressure increases. On the other hand, in the high-pressure plasma having a pressure of 50 Torr or higher, the resonance frequency was about 2.44 GHz, and a tendency was found that the peak became sharper as the pressure increased. The resonance frequency when the plasma is not generated is about 2.44 GHz, and the resonance spectrum is sharper than that of the atmospheric pressure plasma (760 Torr), but a broadening is recognized.

FIG. 5 shows the resonance frequency and half width from the reflection coefficient spectrum shown in FIG. The change of the resonance frequency in FIG. 5A with respect to the pressure agrees with Equation 1 predicted from the transmission line model, considering that the pressure is directly proportional to the electron collision frequency. That is, in Equation 1, the resonance frequency of ν _m → ∞ (high pressure) is c / 4l = f ₀ , and the resonance frequency of ν _m << 2πf _r (low pressure) is f _r = (c / 4l) (1 -ω _p ² / (2πf ₁ ) ² ) ^-1/2 . On the other hand, the full width at half maximum in FIG. That is, at ν _m → ∞ (high pressure), the full width at half maximum decreases according to Δf m1 / ν _m , and conversely, at ν _m → 0 (low pressure), the full width at half maximum increases according to Δf∝ν _{m and} reaches a maximum at about 20 Torr. Indicates the value. Actually, when the electron collision frequency is estimated from the collision cross-section data of argon and the pressure indicating the maximum half-value width is obtained from Equation 2, it is about 20 Torr. In other words, the validity of the electron density measurement method A shown in Equation 6 was proved.

Figure 6 shows the relationship between the ratio Delta] f / f _r and the electron density n _e of the half width and the resonance frequency determined from the resonance spectrum of FIG. 4 or FIG. 5 (b). The pressure p is two levels of 160 Torr and 760 Torr, the electron temperature Te is two levels of 0.5 eV and 1.0 eV, and the ratio Δf / f ₀ between the half-width and the resonance frequency when no plasma is generated is defined as Vacuum level. Indicated. In either condition, Delta] f / f _r is the Vacuum level Δf / f ₀ sectioned, has a proportional relationship with respect to the electron density. Thereby, the validity of the measurement method B that the plasma density can be calculated by Equation 8 was confirmed.

[Effect of Best Embodiment]
(1) According to the method of measuring the electron density and electron collision frequency of the high pressure plasma and the plasma characteristic measuring apparatus 1 of the present invention, the probe 10 acting as a resonant antenna in the microwave region is inserted into the high pressure plasma P, and the high frequency plasma A high frequency power is supplied to the probe 10 while sweeping the frequency by the oscillator 21, a spectrum of a reflection coefficient obtained by the power reflected from the probe 10 is measured by the reflection coefficient spectrum display unit 25, and a resonance spectrum of the probe 10 is detected. Then, the resonance frequency and the half width of the resonance are calculated from the resonance characteristics detected by the reflection coefficient spectrum display unit 25, and the electrons of the high pressure plasma are calculated by the plasma characteristic calculation unit 26 based on the resonance frequency and the half width of the resonance. Density and electron collision frequency can be calculated. Since the half width of resonance changes sensitively to the electron density and electron collision frequency of high pressure plasma, the electron density and electron collision frequency of high pressure plasma are accurately measured based on the resonance frequency and half width of resonance. can do. The probe 10 can be formed from, for example, a metal wire having a length of about several centimeters, so that the probe 10 is small in size, has spatial resolution, and can be measured by a simple operation using, for example, a commercially available network analyzer. The electron density and electron collision frequency of high-pressure plasma having a pressure of 1 Torr or higher can be measured without using an expensive large-sized measuring device. Further, when a probe formed of a U-shaped metal conductor is adopted as the probe 10, a port for insertion into the chamber 31 in which plasma is generated can be made smaller than a T-shaped probe or the like, which is preferable. Can be used.

(2) In the measurement method B, and the ratio Delta] f / f _r and half width and the resonance frequency obtained from the resonance spectrum is corrected by the ratio Delta] f / f ₀ and the half-value width and resonance frequency when a plasma is not generated Therefore, an error factor can be eliminated and a more accurate electron density can be measured.

(3) In the measurement method C, the measurement error at high pressure can be significantly suppressed by using two probes 10 having different lengths compared to the measurement using a single probe. It can be improved significantly.

[Other Embodiments]
In the above-described embodiment, a U-shaped probe is used as the probe 10. However, the present invention is not limited to this. For example, various probes described in JP WO2007 / 02659 developed by the inventors are used. be able to.

It is the schematic of a plasma processing apparatus and a plasma density measuring apparatus. It is explanatory drawing which shows the external shape of a probe. It is explanatory drawing which shows the connection method of a probe and a coaxial cable. It is explanatory drawing which shows the example of the resonance spectrum obtained by the electromagnetic field simulation in an Example. It is explanatory drawing which shows the pressure dependence of (a) resonance frequency and (b) half value width in an Example. It is explanatory drawing which shows the relationship between the ratio of the half value width calculated | required from the resonance spectrum in an Example, and a resonance frequency, and an electron density.

DESCRIPTION OF SYMBOLS 1 Plasma characteristic measuring apparatus 10 Probe 11 Coaxial cable 20 Probe control apparatus 21 High frequency oscillator 22 Directional coupler 23 Attenuator 24 Filter 25 Reflection coefficient spectrum display part 26 Plasma characteristic calculation part 30 Plasma processing apparatus 31 Chamber 32 Control part

Claims (6)

Insert a probe that acts as a resonant antenna in the microwave region into the plasma,
A high frequency power is supplied to the probe while sweeping the frequency, and a resonance frequency and a half width of the resonance are measured from a spectrum of a reflection coefficient obtained by the power reflected from the probe, and the resonance frequency and the half width of the resonance are obtained. A method for measuring an electron density and / or an electron collision frequency of a high pressure plasma, wherein the electron density and / or the electron collision frequency of the high pressure plasma is calculated based on the above. The electron density is calculated based on the ratio of the resonance half-width of the probe in the plasma and the resonance frequency, corrected by the ratio of the resonance half-width of the probe and the resonance frequency when no plasma is generated. The method for measuring electron density and / or electron collision frequency of high-pressure plasma according to claim 1. Two probes with different lengths that act as resonant antennas in the microwave region are inserted into the plasma, high frequency power is supplied to each probe while sweeping the frequency, and the power reflected by each probe is obtained. Resonance frequency and half width of resonance are measured from the respective reflection coefficient spectra, and the electron density and / or electron collision frequency of high-pressure plasma is calculated based on the resonance frequency and half width of resonance. A method for measuring electron density and / or electron collision frequency of high-pressure plasma. A probe inserted into a high pressure plasma atmosphere and acting as a resonant antenna in the microwave region;
A high-frequency oscillator that is electrically connected to the probe via a coaxial cable and supplies high-frequency power while sweeping the frequency;
A spectrum of a reflection coefficient obtained by the power reflected from the probe, and a resonance spectrum detector for detecting a resonance characteristic of the probe;
A resonance frequency and a resonance half width are calculated from the resonance characteristics detected by the resonance spectrum detector, and an electron density and / or an electron collision frequency of high-pressure plasma are calculated based on the resonance frequency and the resonance half width. A plasma characteristic calculator,
An apparatus for measuring electron density and / or electron collision frequency of high-pressure plasma. The said probe is formed of the U-shaped metal conductor, The measuring device of the electron density and / or electron collision frequency of the high pressure plasma of Claim 4 characterized by the above-mentioned. 6. The apparatus for measuring electron density and / or electron collision frequency of high-pressure plasma according to claim 4 or 5, comprising two probes having different lengths.

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