JP2012089365A - Plasma potential and ion speed measurement method, plasma potential and ion speed measurement device and plasma processing apparatus and recording medium and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide inexpensive and compact measurement method and device of plasma state such as plasma potential, ion speed, or the like, in plasma processing.SOLUTION: Relationship of the ion speed and the plasma potential is calculated from the relationship of a voltage applied between the plasma and a mass spectrograph and the conditions of the spectrograph that the same ion is detected. While supposing that the mass spectrograph is a single probe, a voltage changing from negative to positive continuously or intermittently is applied between the mass spectrograph and the plasma, the plasma potential is calculated from these relationships, and then the ion speed in the plasma is calculated from the relationship of the ion speed and the plasma potential, and the relationship with the plasma potential thus calculated.

Description

  The present invention is one of parameters that indicate the state of plasma in order to perform a desired target process when performing processing such as film formation, ion implantation, etching, and surface cleaning processing on an article to be processed using plasma. The present invention relates to a method and apparatus for measuring a plasma potential and an ion velocity, and further to a plasma processing apparatus, and further relates to a program used for carrying out the method and a recording medium on which the program is recorded.

  In processing such as film formation (film formation), ion implantation, etching, and surface cleaning processing using plasma, ion species, radical species, plasma potential, etc. in plasma are used to perform desired processing. Control is important, and monitoring is essential for that. For example, for ion species measurement, mass analysis using a mass analyzer is generally performed.

  FIG. 5 shows that a plasma analysis apparatus PA that performs a target process under the plasma 2 on an object to be processed S installed in the vacuum chamber 1 performs mass analysis on the plasma using a so-called E × B type mass analyzer. An example is shown. As shown in FIG. 5, when the plasma 2 is formed in the vacuum chamber 1, the E × B type mass analyzer 3 is installed so as to be in contact with the plasma.

  A negative voltage is normally applied to the E × B mass analyzer 3 by a bias power source 10, and positive ions 5 are drawn from the plasma 2 through the entrance slit 4 into the analyzer 3. A magnetic field 16 is formed inside the E × B type mass analyzer 3 by a magnetic field generating means (not shown), and the drawn ions 5 receive a force in a downward direction 17 in FIG.

  On the other hand, opposing deflection plates 6 and 7 that are parallel to each other are arranged with their flat surfaces aligned in the direction of the lines of magnetic force of the magnetic field 16. A positive potential is applied to the deflection plate 6 from the deflection power source 8 and a negative potential is applied to the deflection plate 7 from the deflection power source 9. Is formed. The ions 5 are also subjected to a force in the upward direction 18 by this electric field.

  In this way, a force in the downward direction 17 and a force in the upward direction 18 are applied to the ion 5, and the ion 5 travels straight only when these two are balanced, passes through the FC slit 11, and enters the Faraday cup 13. On and detected by the ammeter 15.

  At this time, secondary electrons are emitted from the Faraday cup 13 and an accurate ion current may not be measured. Therefore, in order to suppress the influence, a suppressor 12 is installed between the FC slit 11 and the Faraday cup 13. In this case, a negative voltage is applied from the suppressor power supply 14 so that the emitted secondary electrons are pushed back to the Faraday cup 13 again.

  FIG. 6 is a diagram showing a plasma processing apparatus PB that performs a target process under the plasma 2 on an object to be processed S installed in the vacuum chamber 1. The plasma is subjected to mass spectrometry using a magnetic field deflection type mass analyzer 19. An example is shown. As shown in FIG. 6, when the plasma 2 is formed in the vacuum chamber 1, a magnetic field deflection type mass analyzer 19 is installed so as to be in contact with the plasma.

  A negative voltage is normally applied from the bias power source 22 to the magnetic field deflection type mass analyzer 19, and positive ions 21 are drawn from the plasma 2 through the entrance slit 20 into the analyzer 19. A magnetic field 28 is formed inside the magnetic field deflection type mass analyzer 19, and the drawn ions 21 receive a force in a direction 29 due to the influence of the magnetic field and fly in a circular orbit.

  Since the orbit radius r of the ions 21 is determined by the strength of the magnetic field 28, the FC slit 23 and the Faraday cup 25 are installed on the constant orbit radius, and the ions are finally detected by the ammeter 27.

  At this time, as in the case of the E × B mass analyzer 3, secondary electrons are emitted from the Faraday cup 25, and an accurate ion current may not be measured. The suppressor 24 is installed between the Faraday cup 25 and a negative voltage is applied to the suppressor power supply 26 so that the emitted secondary electrons are pushed back to the Faraday cup 25 again.

  The E × B type mass analyzer described above is described in, for example, Japanese Patent Application Laid-Open No. 4-212300, and the magnetic field deflection type mass analyzer is described in, for example, Japanese Patent Application Laid-Open No. 2000-46680.

For example, an electrostatic energy analyzer is used to measure ion energy in plasma. Although not shown here, the structure is composed of several grids and a collector into which ions flow, and a system is composed of a power source for applying a voltage to the grid and collectors. While being measured by the electrostatic energy analyzer is an energy of ions, ionic species, that is, if knowing the mass of the ions E the energy of the ions, the ion mass m, the ions from E = 1/2 mv ² The velocity v can be calculated.

  The probe method is generally used for measuring the plasma potential. The probe method is not shown here because it is already well known per se, but examples of the probe method include a single probe method, a double probe method compatible with a floating potential system, and a triple probe method capable of instantaneous measurement. Of these three methods, the plasma potential can be measured by the single probe method.

  These probe methods are described in, for example, “Latest Plasma Generation Technology” published by August 5, 1991, published by IPC Corporation and edited by Yoshinobu Kawai.

JP-A-4-212300 JP 2000-46680 A

August 5, 1991 published by IPC, edited by Yoshinobu Kawai, "Latest Plasma Generation Technology"

  As can be seen from the above description, in order to perform both ion velocity measurement and plasma potential measurement, a mass analyzer, an electrostatic energy analyzer, and a probe instrument are all necessary. However, if all of them are installed in the chamber, an installation space is required in the chamber, the chamber size increases, the installation area of the plasma processing apparatus increases, and the cost of the plasma processing apparatus increases.

  Therefore, the present invention can measure the plasma potential, which is a parameter indicating the state of the plasma, together with the analysis of the ion velocity by applying a mass analyzer without relying on the probe measuring device. It is a first object to provide a plasma potential measurement method that can perform both of them and is inexpensive.

  In addition, the present invention can measure the plasma potential, which is a parameter indicating the state of the plasma, together with the analysis of the ion velocity by applying a mass analyzer without relying on the probe measuring instrument. A second object is to provide an inexpensive plasma potential measuring apparatus that can perform both of them and is simplified.

  Furthermore, the present invention is a plasma processing apparatus for generating a plasma in a vacuum chamber and performing an intended process on an object to be processed under the plasma, and a plasma potential which is a parameter indicating a plasma state is probed. Without relying on measuring instruments, a mass analyzer can be applied to perform ion velocity analysis, and both ion velocity analysis and plasma potential measurement can be performed. Providing is a third problem.

  It is a fourth and fifth object of the present invention to provide a program for implementing the plasma potential and ion velocity measurement method capable of solving the first problem and a recording medium recording the program.

In order to solve the first problem, the present invention provides:
Disposing a mass analyzer capable of performing mass analysis of ions in the plasma with respect to a plasma potential measurement target plasma;
At least two different voltages are respectively applied between the mass analyzer and the plasma to perform mass analysis. In performing the mass analysis, at least two voltages Vb of the at least two different voltages are used. The mass analysis condition X corresponding to the mass analyzer capable of detecting the same ion as in the case of the other voltages among the two different voltages is obtained, and the mass analysis corresponding to each voltage Vb and the voltage thus obtained is obtained. Formula Vb = aX ² − (k + Vp) (k is mv ₀ ² / 2Ze, and m, v _{0 and} Z are the mass of ions and the initial velocity in the plasma, respectively. , E is the elementary electric charge, Vp is the plasma potential of the plasma to be measured, and the regression equation is fitted to the regression equation using the least square method. In And k + Vp to be to calculated, and determining the a to identify the ion species,
When the mass analyzer is regarded as a single probe, between the plasma potential measurement target plasma and the mass analyzer, a voltage from which the potential of the mass analyzer is lower than the potential of the plasma potential measurement target plasma. Apply continuously or intermittently, measure the applied voltage and the current flowing through the bias power supply,
From the relationship between the applied voltage and the current flowing through the mass analyzer, the potential Vp of the plasma potential measurement target plasma is calculated from analysis by a single probe method,
Obtaining an ion velocity in the plasma potential measurement target plasma from the relationship between the plasma potential measurement target plasma potential Vp and the a and k;
There is provided a plasma potential measurement method comprising:

In order to solve the second problem, the present invention
A mass analyzer capable of mass spectrometry of ions in the plasma to be arranged with respect to the potential measurement target plasma;
A bias power source for applying a voltage between the mass analyzer and the plasma;
A plasma potential calculator,
In measuring the plasma potential, at least two different voltages are applied to the bias power source between the mass analyzer and the plasma, respectively, and mass analysis of ions in the plasma is performed on the mass analyzer. Then, for each voltage Vb of the at least two different voltages, a mass analysis condition X corresponding to the mass analyzer that can detect the same ion as the other voltage of the at least two different voltages is obtained. It is possible,
The plasma potential calculation unit obtains a predetermined expression Vb = aX ² − (k + Vp) (k is mV ₀ ² ) in the data of each voltage Vb and the mass analysis condition X corresponding to the voltage thus obtained. / Ze, m, v _{0, and} Z are the mass of ions, initial velocity in plasma, and valence, respectively, e is the elementary charge, and Vp is the plasma potential of the potential measurement target plasma.) To obtain a for identifying the ion species by calculating a and k + Vp in the regression equation by fitting the regression equation to the regression equation using the least square method,
When the mass analyzer is regarded as a single probe, between the plasma potential measurement target plasma and the mass analyzer, a voltage from which the potential of the mass analyzer is lower than the potential of the plasma potential measurement target plasma. Continuously or intermittently applied, the applied voltage and the current flowing through the bias power source are measured. From the relationship between the applied voltage and the current flowing through the mass analyzer, the plasma potential measurement target plasma is measured by a single probe method. Provided is a plasma potential and ion velocity measuring device capable of calculating a potential Vp and obtaining an ion velocity in the plasma potential measurement target plasma from a relationship between the plasma potential measurement target plasma potential Vp and the a and k.

In the plasma potential and ion velocity measuring apparatus according to the present invention, when measuring the plasma potential and ion velocity, at least two different voltages are applied to the voltage application unit between the mass analyzer and the plasma, respectively. Allowing the mass analyzer to perform mass analysis of ions in the plasma, and for each voltage Vb of the at least two different voltages, the same ion as in the other of the at least two different voltages In order to obtain the mass analysis condition X corresponding to the mass analyzer, the user of the plasma potential and ion velocity measuring device operates the voltage application unit to set the voltage between the mass analyzer and the plasma. Apply mass analysis to obtain the mass analysis condition X, and the user calculates the plasma potential and ion velocity based on the data. It may be so.
Further, when the mass analyzer is regarded as a single probe, the user of the plasma potential and ion velocity measurement device can measure the plasma potential between the plasma potential measurement target plasma and the mass analyzer. Applying continuously or intermittently from a voltage lower than the potential of the target plasma to a higher voltage, measuring the applied voltage and the current flowing through the bias power source, and the relationship between the applied voltage and the current flowing through the mass analyzer From the above, the potential Vp of the plasma potential measurement target plasma is calculated by a single probe method,
The ion velocity in the plasma potential measurement target plasma may be obtained from the relationship between the plasma potential measurement target plasma potential Vp and the a and k.

However, the plasma potential and ion velocity measurement unit including the voltage Vb and the corresponding data of the mass analysis condition X and the plasma potential and ion velocity calculation unit are provided, and when measuring the plasma potential and ion velocity, A part for collecting data causes the voltage application unit to apply at least two different voltages between the mass analyzer and the plasma to cause the mass analyzer to perform mass analysis of ions in the plasma, For each voltage Vb of the at least two different voltages, a mass spectrometric condition X corresponding to the mass analyzer capable of detecting the same ions as in the other voltages of the at least two different voltages is obtained, The plasma potential and ion velocity calculation unit adds the data Vb and the mass analysis condition X data corresponding to the voltage thus obtained. Formula Vb = aX ²
-(K + Vp) is fitted using the least square method to calculate a and k + Vp in the equation, thereby obtaining a for identifying the ion species, and then measuring the plasma potential Between the target plasma and the mass analyzer, the potential of the mass analyzer is applied continuously or intermittently from a voltage lower than the potential of the plasma potential measurement target plasma to a higher voltage, and the applied voltage and the bias The current flowing through the power source is measured, and the potential Vp of the plasma potential measurement target plasma is calculated by the single probe method from the relationship between the applied voltage and the current flowing through the mass analyzer, and the potential Vp of the plasma potential measurement target plasma is calculated. And the relationship between a and k, the ion velocity in the plasma potential measurement target plasma may be obtained.

  In any case, the plasma potential and ion velocity calculation unit or the plasma potential and ion velocity measurement unit may be provided exclusively for the plasma potential and ion velocity measurement device according to the present invention. It may be used. A computer dedicated to the plasma potential and ion velocity measuring device can also be used.

  In the plasma potential and ion velocity measuring method and apparatus according to the present invention, the voltage applied between the mass analyzer and the plasma is applied by the bias power supply 10 in the mass analysis example shown in FIG. 4 is a voltage obtained by adding a plasma potential to the voltage applied by the bias power supply 10 in the example of mass spectrometry shown in FIG.

  According to the method and apparatus for measuring plasma potential and ion velocity according to the present invention, the identification of the ion species and the measurement of plasma potential and ion velocity can be performed with an inexpensive apparatus by applying a mass analyzer without relying on a probe measuring instrument.

  As a mass analyzer in the plasma potential and ion velocity measuring method and apparatus according to the present invention, an E × B type mass analyzer of the type illustrated in FIG. 1 as a representative example or a magnetic field deflection type mass spectrometer of the type illustrated in FIG. Can be mentioned.

  When the E × B type mass analyzer is employed, the relationship between the electric field intensity E in which the same ion is detected by the mass analyzer and the ratio E / B of the magnetic flux density B of the magnetic field is determined. In the case of using a detector, the plasma potential is calculated from the relationship between the product rB of the magnetic flux density B of the magnetic field in which the same ion is detected by the mass analyzer and the orbit radius r of the ion.

The case where the E × B type mass spectrometer is employed will be further described. In the plasma potential and ion velocity measuring method and the plasma potential and ion velocity measuring device,
The mass analyzer is an E × B type mass analyzer, the mass analysis condition X is a ratio (E / B) of the electric field intensity E and the magnetic flux density B, and a in the regression equation is the mass analyzer. (M / Z) / 2e, where Vb = aX ² , where m is the mass of the same ion detected by (2), Z is the valence of the ion, and e is the elementary charge.
− (K + Vp) is
Vb = [(m / Z) / 2e] × (E / B) ² − (k + Vp)
It is.

When a magnetic field deflection type mass analyzer is employed, the mass analyzer is a magnetic field deflection type mass analyzer, and the mass analysis condition X is a product of the magnetic flux density B and the flight trajectory radius r of ions by the mass analyzer. (R × B) where a in the regression equation is (Z / m) where m is the mass of the same ion detected by the mass analyzer, Z is the valence of the ion, and e is the elementary charge. ) × e / 2, and Vb = aX ²
− (K + Vp) is
Vb = [(Z / m) × e / 2] × (r × B) ² − (k + Vp)
It is.

In order to solve the third problem, the present invention
A plasma processing apparatus capable of generating plasma in a vacuum chamber and performing an intended process on an article to be processed under the plasma, comprising a plasma potential measuring apparatus according to the present invention. provide.

  Since the plasma processing apparatus according to the present invention includes the plasma potential and ion velocity measuring apparatus according to the present invention, the plasma potential and ion velocity, which are parameters indicating the state of the plasma, can be measured without depending on the probe measuring instrument. By applying an analyzer, measurement can be performed together with the analysis of ion species, both mass spectrometry and plasma potential measurement can be performed, and it can be provided at low cost without increasing the size.

  Examples of the plasma processing apparatus according to the present invention include a plasma processing apparatus that can perform one or more processes selected from film formation, ion implantation, etching, and article surface cleaning.

In order to solve the fourth problem, the present invention is a program for causing a computer to execute at least a part of a procedure for performing the plasma potential and ion velocity measurement method according to the present invention. At least two different voltages are respectively applied to the plasma to perform mass analysis, and in performing the mass analysis, for each voltage Vb of the at least two different voltages, the other of the at least two different voltages is used. Reading the data of each voltage Vb obtained by obtaining the mass analysis condition X corresponding to the mass analyzer and the mass analysis condition X corresponding to the voltage, which can detect the same ions as in the case of the voltage of wherein the read the data type Vb = aX ² - by (k + Vp) of the fitting using the least squares method, a in formula and X ²
-Vp is calculated to calculate the potential of the plasma potential measurement target plasma from the step of obtaining a for identifying the ion species and the relationship between the applied voltage and the current flowing through the mass analyzer, from the analysis by the single probe method. Calculating Vp;
Obtaining an ion velocity in the plasma potential measurement target plasma from the relationship between the plasma potential measurement target plasma potential Vp and the a and k;
A program for causing a computer to execute the program is also provided.

In order to solve the fifth problem, the present invention also provides a computer-readable recording recording a program for causing a computer to execute at least a part of a procedure for performing the plasma potential and ion velocity measuring method according to the present invention. The medium is configured to perform mass analysis by applying at least two different voltages between the mass analyzer and the plasma, and for performing the mass analysis, for each voltage Vb of the at least two different voltages, Each voltage Vb obtained by obtaining a mass analysis condition X corresponding to the mass analyzer capable of detecting the same ion as in the case of the other voltage of the at least two different voltages and the voltage corresponding to the voltage mass said analysis condition X of data read in step and read the data type Vb = aX ² - a (k + Vp) by using the least square method Calculating a and (k + Vp) in the equation, respectively, to obtain a for identifying the ion species, the mass analyzer is regarded as a single probe, and the plasma potential measurement object A step of continuously or intermittently applying between the plasma and the mass analyzer from a voltage at which the potential of the mass analyzer is lower than the potential of the plasma potential measurement target plasma to a higher voltage; the applied voltage and the bias Measuring the current flowing through the power supply,
Calculating the potential Vp of the plasma potential measurement target plasma by a single probe method from the relationship between the applied voltage and the current flowing through the mass analyzer;
Obtaining an ion velocity in the plasma potential measurement target plasma from the relationship between the plasma potential measurement target plasma potential Vp and the a and k;
There is also provided a computer-readable recording medium on which a program for causing a computer to execute is recorded.

  As described above, according to the present invention, the plasma potential and the ion velocity, which are parameters indicating the plasma state, can be measured together with the analysis of ion species by applying a mass analyzer without depending on the probe measuring instrument. In addition, it is possible to provide a plasma potential and ion velocity measuring method that can perform both mass spectrometry and plasma potential and ion velocity measurement, and can be inexpensive.

  Further, according to the present invention, the plasma potential, which is a parameter indicating the plasma state, can be measured together with the identification of the ion species by applying the mass analyzer without relying on the probe measuring instrument. It is possible to provide a simplified and inexpensive plasma potential measuring apparatus that can perform both ion velocity measurements.

  Furthermore, according to the present invention, there is provided a plasma processing apparatus capable of generating a plasma in a vacuum chamber and performing an intended process on an object to be processed under the plasma, wherein the plasma is a parameter indicating a plasma state. The potential can be measured together with the identification of the ion species by applying the mass analyzer without relying on the probe measuring instrument, and both the mass analysis and the plasma potential and ion velocity measurement can be performed. An inexpensive plasma processing apparatus can be provided.

  According to the present invention, there is also provided a program for implementing the above-described plasma potential and ion velocity measurement method and a recording medium on which the program is recorded, wherein the ion species can be identified, the plasma potential can be obtained, and the ion velocity can be easily obtained. Can be provided.

It is a figure which shows the example of a plasma processing apparatus provided with one example of the plasma potential and ion velocity measuring apparatus which concerns on this invention. It is a figure which shows the relationship between the detection ion current and the deflection | deviation electric field (deflection electric field strength) in the example of mass spectrometry by the BxE type | mold mass analyzer shown in FIG. It is a figure which shows the data of the deflection electric field which shows the bias voltage applied between a mass spectrometer and plasma, and the detection ion current peak corresponding to this voltage. It is a figure which shows the example of a plasma processing apparatus provided with the other example of the plasma potential measuring device which concerns on this invention. It is a figure which shows the prior art example which is implementing mass spectrometry using what is called an E * B type | mold mass spectrometer. It is a figure which shows the prior art example which is implementing mass spectrometry using what is called a magnetic field deflection type mass analyzer.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 shows an example of a plasma processing apparatus provided with an example of a plasma potential and ion velocity measuring apparatus according to the present invention.
The plasma processing apparatus PA shown in FIG. 1 includes a plasma potential and ion velocity measuring apparatus A. The plasma potential and ion velocity measuring apparatus A includes the same E × B type mass analyzer 3 as the mass analyzer shown in FIG. 5, and the program is recorded from the recording medium M1 on which one example of the program according to the present invention is recorded. A personal computer PC1 is included as an example of a plasma potential and ion velocity calculation unit that reads and calculates factors for plasma potential and ion species identification.

1 that are substantially the same as those shown in FIG. 5 are denoted by the same reference numerals as those used in FIG. That is,
PA is a plasma processing apparatus (in this example, an object to be processed S to which a bias voltage is applied from a bias power supply (not shown) is subjected to a target process (for example, a cleaning process by irradiation with ions such as argon ions) under plasma. Device].
For example, the plasma 2 supplies a gas (for example, argon gas) from a gas supply device (not shown) into the chamber 1 while maintaining the gas plasma generation pressure by evacuating the chamber 1 with an exhaust device (not shown). It can be generated by hot cathode arc discharge (not shown).

The mass analyzer 3 can perform mass analysis in the same manner as the mass analyzer of FIG.
According to the plasma potential and ion velocity measuring apparatus A in FIG. 1, factors for identifying ion species in plasma can be obtained together with the potential of plasma 2.
That is, at least two different voltages are respectively applied between the mass analyzer 3 and the plasma 2 to perform mass analysis. In performing the mass analysis, for each voltage Vb of the at least two different voltages, Obtaining a mass analysis condition X according to the mass analyzer 2 capable of detecting the same ion as in the case of other voltages of at least two different voltages;
Formula Vb = aX ² − (k + Vp) (k is mv ₀ ² / 2Ze) previously derived from the data of each voltage Vb and the mass analysis condition X corresponding to the voltage thus obtained, m , V _{0, and} Z are the ion mass, initial velocity, valence, e is the elementary electric charge, Vp is the plasma potential of the plasma to be measured, and the regression equation is the least square method. Can be obtained by calculating a and (k + Vp) in the regression equation, respectively.
Next, assuming that the mass analyzer is a single probe, the potential of the mass analyzer is increased between the plasma potential measurement target plasma and the mass analyzer from a voltage at which the potential of the mass analyzer is lower than the potential of the plasma potential measurement target plasma. Continuously or intermittently applied to a voltage to measure the applied voltage and the current flowing through the bias power supply,
From the relationship between the applied voltage and the current flowing through the mass analyzer, the potential Vp of the plasma potential measurement target plasma is calculated by a single probe method (see Non-Patent Document 1: p211 to p218 described in paragraph 0017),
The ion velocity in the plasma potential measurement target plasma can be obtained from the relationship between the plasma potential measurement target plasma potential Vp and the a and k.
Here, “applying continuously or intermittently from a voltage lower than the potential of the plasma potential measurement target plasma to a higher voltage” generally means that the plasma potential is about 10 to 50 V higher than the plasma container, and therefore the plasma For example, the voltage may be applied continuously or intermittently from −100 V that is sufficiently lower than the potential to about 100 V that is sufficiently higher.

In this example in which the E × B type mass analyzer 3 is employed as the mass analyzer, the mass analysis condition X in Vb = aX ² − (k + Vp) is the ratio of the electric field strength E to the magnetic flux density B (E / B) and a is (m / Z) / 2e (m is the mass of the same ion detected by the mass analyzer, Z is the valence of the ion, and e is the elementary charge). Therefore, Vb = aX ²
− (K + Vp) is
Vb = [(m / Z) / 2e] × (E / B) ² − (k + Vp).

The reason why Vb = [(m / Z) / 2e] × (E / B) ² − (k + Vp) will be described below.
The bias voltage applied from the power source 10 to the mass analyzer 3 is Vb, and the plasma potential of the plasma 2 is Vp. For example, the plasma potential in the plasma 2 in the vicinity of the evaporation surface as in the vacuum arc deposition method for forming a film. Is high, the ions in the plasma 2 have an initial velocity. Therefore, when the initial velocity of ions in the plasma 2 is v ₀ , the following equation (1) holds.

In the above formula (1), m is the mass of the ion, v is the ion velocity when entering the mass analyzer, v ₀ is the initial velocity of the ion in the plasma, Z is the valence of the ion, and e is the elementary charge. is there. In this example, the bias voltage is a negative voltage and the plasma potential is a positive potential, but both are described as absolute values.

In the E × B type mass analyzer 3, the ion detection condition is a case where the forces received from the magnetic field (magnetic flux density B) and the electric field (electric field strength) are balanced, and therefore the equation (3) derived from the following equation (2): )become that way.

式(4) は、バイアス電圧Ｖｂが電界（偏向電界強度Ｅ）と磁界（磁束密度Ｂ）との比（Ｅ／Ｂ）の２次式であることを示している。 Substituting equation (3) into equation (1) and rearranging results in the following equation (4).

Expression (4) indicates that the bias voltage Vb is a quadratic expression of the ratio (E / B) between the electric field (deflection electric field strength E) and the magnetic field (magnetic flux density B).

FIG. 2 shows the following. That is,
The chamber 1 is evacuated by an unillustrated exhaust device to maintain the argon gas plasma generation pressure, while argon gas is supplied into the chamber 1 from an unillustrated gas supply device, and plasma is generated by vacuum arc discharge (not illustrated). An example in the case of generating and analyzing with the mass analyzer 3 is shown. In FIG. 2, the vertical axis indicates the ion current detected by the ammeter 15, and the horizontal axis indicates the peak deflection electric field intensity E at which ions are detected.

In this case, when the bias voltage Vb was 380 V and the magnetic flux density B was fixed at 0.102 T, the peak deflection electric field intensity E in which ions were detected was 4.42 kV / m.
The measurement was performed in the same manner while changing the bias voltage Vb, and the result of examining the relationship between the bias voltage Vb and the peak deflection electric field strength E is shown by a black circle in FIG.
The coordinates (Vb, E) indicated by black circles in FIG. 3 are (380, 4.42), (330, 4.12), and (280, 3.82).

The computer PC1 serving as the plasma potential and ion velocity calculation unit reads the following program from the recording medium M1. That is,
From the keyboard of the bias voltage Vb and the corresponding peak deflection field strength E to magnetic flux density B ratio (E / B) data, in FIG. 2, the combination data of Vb and E / B corresponding to at least two black circles. The data is read in response to the input, and the equation (4) is fitted to the read data using the method of least squares, so that (m / Z) / 2e and ( k + Vp). Here, k is mv ₀ ² / 2Ze.

Therefore, mass analysis of the plasma by the mass analyzer 3 applies at least two bias voltages Vb and obtains (E / B) corresponding to each voltage Vb (B is known in this example) 0.102T), these data can be input to the computer PC1 to obtain (k + Vp) and (m / Z) / 2e for ion species identification.
Further, the computer PC1 is also loaded with the next program from the recording medium M1.
That is, when the mass analyzer is regarded as a single probe, the potential of the mass analyzer increases from a voltage lower than the potential of the plasma potential measurement target plasma between the plasma potential measurement target plasma and the mass analyzer. Voltage is applied continuously or intermittently, the applied voltage and the current flowing through the bias power supply are measured and recorded on the recording medium M1, and the applied voltage and the mass analyzer are calculated by a plasma potential and ion velocity calculation unit. The plasma potential Vp of the plasma potential measurement target plasma is calculated from the relationship of the current flowing through the plasma by the single probe method. The relationship between the plasma potential measurement target plasma potential Vp and the a, k It is a program for calculating the ion velocity.
When Vp and the like were calculated in this way, the plasma potential Vp was 11.8 [V]. When (m / Z) / 2e was calculated as (m / Z) / (2e × B ² ), it was 20.1. In any case, since e is also known for ionic species identification, m / Z can be obtained, whereby the ionic species can be identified. The program may include a procedure for further calculating m / Z from the calculated (m / Z) / 2e.

In this example, since B is fixed, it is sufficient to actually input E for the ratio (E / B). From the combinations of Vb and E shown in FIG. By inputting at least two, (m / Z) / (2e × B ²
) And Vp may be calculated.

Among (m / Z) / (2e × B ² ), since e and B are known, (m / Z) can be calculated, and the ion species can be identified from this. The program includes the calculated (m / Z) / (2e × B ²
) May further include a procedure for calculating m / Z.

In the example described above, the electric field strength E is changed by fixing B out of the ratio (E / B), but conversely, the magnetic flux density B may be changed by fixing E, and both are changed. Also good.
Further, for example, the computer PC1 issues an instruction to turn on / off the voltage application to each power source and reads information detected by the ammeter 15. The computer PC1 reads each bias voltage Vb and the corresponding peak ion. Data of the deflection electric field intensity E when the current is detected may be collected, and (k + Vp) and m / Z for ion species identification may be calculated based on the data.

FIG. 4 shows an example of a plasma processing apparatus provided with another example of the plasma potential and ion velocity measuring apparatus according to the present invention.
The plasma processing apparatus PB shown in FIG. 4 includes a plasma potential and ion velocity measuring apparatus B. The plasma potential and ion velocity measuring device B includes the same magnetic field deflection type mass analyzer 19 as the mass analyzer shown in FIG. 6, and the program from the recording medium M2 on which another example of the program according to the present invention is recorded. And a personal computer PC2 as an example of a plasma potential and ion velocity calculation unit for calculating factors for identifying plasma potential and ion velocity and ion species.

4 that are substantially the same as those shown in FIG. 6 are denoted by the same reference numerals as those used in FIG. That is, PB is a plasma processing apparatus (in this example, a target process under the plasma of the article to be processed S to which a bias voltage is applied from a bias power supply (not shown) (for example, a cleaning process by irradiation with ions such as argon ions). [Apparatus for applying].
Also in the apparatus PB, for example, the plasma 2 is gas (for example, argon gas) from a gas supply device (not shown) in the chamber 1 while maintaining the gas plasma generation pressure by evacuating the inside of the chamber 1 with an exhaust device (not shown). ), And can be generated by hot cathode arc discharge (not shown).

The mass analyzer 19 can perform mass analysis similarly to the mass analyzer of FIG.
According to the plasma potential and ion velocity measuring apparatus B in FIG. 4, a factor for identifying the ion species in the plasma can be obtained together with the potential of the plasma 2.
That is, at least two different voltages are respectively applied between the mass analyzer 19 and the plasma 2 to perform mass analysis. In performing the mass analysis, for each voltage Vb of the at least two different voltages, Obtaining a mass analysis condition X according to the mass analyzer 19 capable of detecting the same ions as in the case of other voltages of at least two different voltages;
Formula Vb = aX ² − (k + Vp) (k is mv ₀ ² / 2Ze) previously derived from the data of each voltage Vb and the mass analysis condition X corresponding to the voltage thus obtained, m , V _{0, and} Z are the mass of ions, initial velocity in plasma, valence, e is the elementary electric charge, and Vp is the plasma potential of the plasma to be measured for potential). By fitting using the least square method and calculating a and (k + Vp) in the regression equation, a for identifying the ion species can be obtained.
Next, the mass analyzer is regarded as a single probe, and the potential of the mass analyzer is increased between the plasma potential measurement target plasma and the mass analyzer from a voltage lower than the potential of the plasma potential measurement target plasma. Apply continuously or intermittently up to a voltage, measure the applied voltage and the current flowing through the bias power supply,
From the relationship between the applied voltage and the current flowing through the mass analyzer, the potential Vp of the plasma potential measurement target plasma is calculated by analysis using a single probe method,
The ion velocity in the plasma potential measurement target plasma can be obtained from the relationship between the plasma potential measurement target plasma potential Vp and the a and k.

In the present example in which the magnetic field deflection type mass analyzer 19 is adopted as the mass analyzer, the mass analysis condition X in Vb = aX ² − (k + Vp) is the magnetic flux density B and the flight trajectory of ions by the mass analyzer. Product of radius r (r × B), where a in the above equation is m, the mass of the same ion detected by the mass analyzer, the valence of the ion Z, and the elementary charge of the ion e Then
(Z / m) × e / 2, and Vb = aX ² − (k + Vp) is
Vb = [(Z / m) × e / 2] × (r × B) ² − (k + Vp).

The reason why Vb = [(Z / m) × e / 2] × (r × B) ² − (k + Vp) is derived is as follows.
Assuming that the bias voltage applied from the bias power source 22 to the mass analyzer 19 is Vb and the plasma potential of the plasma 2 is Vp, the following equation (5) is established as in the case of the E × B type mass analyzer.

  In the above formula (5), m is the ion mass, v is the velocity when entering the analyzer, Z is the valence of the ion, and e is the elementary charge. In this example as well, the bias voltage is a negative voltage and the plasma potential is a positive potential, but both are described as absolute values.

In the magnetic field deflection type mass analyzer 19, the ion detection condition is a case where the force received by the ion due to the magnetic field (magnetic flux density B) is balanced with the centrifugal force, so that the following equation (7) derived from the following equation (6): It becomes like this.

式(8) は、バイアス電圧Ｖｂが磁界（磁束密度Ｂ）とイオンの軌道半径ｒとの積（ｒ×Ｂ）の２次式であることを示している。 Substituting equation (7) into equation (5) and rearranging results in the following equation (8).

Expression (8) indicates that the bias voltage Vb is a quadratic expression of the product (r × B) of the magnetic field (magnetic flux density B) and the orbital radius r of ions.

Therefore, for example, the ion orbit radius r is fixed, and at least two different bias voltages are respectively supplied from the bias power source 22 between the mass analyzer 19 and the plasma 2 as in the case of the plasma potential and ion velocity measurement of FIG. Mass analysis is performed, and at least two sets of combination data of the product (r × B) of the magnetic flux density B and the orbital radius of the ions detected at each bias voltage Vb and its baice voltage are obtained. Can be input to the computer PC2 as a plasma potential calculation unit to calculate (k + Vp) and a factor for identifying the ion species.
Next, assuming that the mass analyzer is a single probe, the potential of the mass analyzer is increased between the plasma potential measurement target plasma and the mass analyzer from a voltage at which the potential of the mass analyzer is lower than the potential of the plasma potential measurement target plasma. The plasma potential is measured by a single probe method based on the relationship between the applied voltage and the current flowing through the mass analyzer. Calculate the potential Vp of the target plasma,
This program calculates the ion velocity in the plasma potential measurement target plasma from the relationship between the plasma potential measurement target plasma potential Vp and the a and k.

The computer PC2 reads the next program from the recording medium M2. That is,
The data is read according to the input from the keyboard of the combination data of at least two different bias voltages Vb and the product (r × B) of the magnetic flux density B and ion orbit radius r corresponding to each bias voltage. (8)
Is a program for calculating (Z / m) × e / 2 and (k + Vp) for identifying the ion species in the equation by fitting using the least square method.
Further, the computer PC1 is also loaded with the next program from the recording medium M1.
That is, when the mass analyzer is regarded as a single probe, the potential of the mass analyzer increases from a voltage lower than the potential of the plasma potential measurement target plasma between the plasma potential measurement target plasma and the mass analyzer. Voltage is applied continuously or intermittently, the applied voltage and the current flowing through the bias power supply are measured and recorded on the recording medium M1, and the applied voltage and the mass analyzer are calculated by a plasma potential and ion velocity calculation unit. The potential Vp of the plasma potential measurement target plasma is calculated by the single probe method from the relationship of the current flowing through
This program calculates the ion velocity in the plasma potential measurement target plasma from the relationship between the plasma potential measurement target plasma potential Vp and the a and k.

  Therefore, mass analysis of the plasma by the mass analyzer 19 obtains at least two bias voltages Vb and (r × B) corresponding to each voltage Vb, and inputs these data to the computer PC2 to obtain (k + Vp) and (Z / m) × e / 2 for ion species identification can be obtained. As for ion species identification, since e is known, (Z / m) can be obtained, whereby the ion species can be identified. The program may include a procedure for further calculating Z / m from the calculated (Z / m) × e / 2.

In this example, since r is fixed, in practice, it is sufficient to input B for the product (r × B), and at least two of the combinations of Vb and B are input. (Z / m) × e × r ²
/ 2 and Vp may be calculated.

(Z / m) of × e × r ^2/2, since e and r are known, it is possible to calculate the m / Z, can now be identified ion species. The program includes the calculated (Z / m) × e × r ²
A procedure for further calculating m / Z from / 2 may be included.

In the example described above, r of the product (r × B) is fixed and the magnetic flux density B is changed, but conversely, B may be fixed and the ion orbit radius r may be changed. May be. The ion orbit radius r can be changed by moving the Faraday cup 25, suppressor 24 and FC slit 23.
Further, for example, the computer PC2 issues an instruction to turn on / off the voltage application to each power source, instructs the output variable magnetic field generating means (not shown) to generate a magnetic field, and detects information detected by the ammeter 27. The computer PC2 collects data of each bias voltage Vb and the corresponding magnetic flux density B, and can calculate (k + Vp) and m / Z for ion species identification based on the data. May be.

  The present invention is capable of performing mass analysis of a plasma using a mass analyzer in processing such as film formation using plasma, ion implantation, etching, etc., and obtaining a plasma potential and ion velocity without using a probe measuring instrument. Available to:

PA, PB Plasma processing apparatus A, B Plasma potential and ion velocity measuring apparatus 1 Vacuum chamber 2 Plasma 3 B × E type mass analyzer 4 Mass analyzer entrance slit,
5 positive ions,
6, 7 deflection plate,
8, 9 Bias power supply 10 Bias power supply
11 FC slit at the ion outlet,
12 Suppressor 14 Suppressor Power Supply 13 Faraday Cup 15 Ammeter (Ion Current Meter)
16 Magnetic field 17 Direction of force exerted on ion by magnetic field (downward direction)
18 Direction of force exerted on ions by electric field between deflecting plates 6 and 7 (upward direction)
PC1, PC2 External computer M1, M2 Recording medium 19 Magnetic deflection type mass analyzer,
20 Mass spectrometer inlet slit,
21 positive ions,
22 Bias power supply,
23 FC slit at the ion exit,
24 suppressor 25 Faraday cup 26 suppressor power supply 27 ammeter (ion current measuring instrument)
28 Magnetic field 29 Direction of force that magnetic field exerts on ion r Radius of flight circle locus of ion

Claims (11)

A mass analyzer capable of performing mass analysis of ions in the plasma is arranged for the plasma potential measurement target plasma, and at least two different voltages are respectively applied between the mass analyzer and the plasma by a bias power source. The mass analysis is performed, and in performing the mass analysis, for each voltage Vb of the at least two different voltages, the same ion can be detected as in the case of the other voltages of the at least two different voltages. The step of obtaining the mass analysis condition X corresponding to the analyzer and the data Vb obtained in this way and the data of the mass analysis condition X corresponding to the voltage Vb = aX ² − (k + Vp ) (k is ^{_{mv 0 2 / 2Ze, m,}} v 0, Z mass of each ion, the initial velocity, valence, e is an elementary charge.) Vp is the plasma of the potential measuring object plasma It is a place. ) As a regression equation and fitting the regression equation using a least square method, respectively, calculating a and (k + Vp) in the regression equation;
Identifying an ion species from the calculated a;
Between the plasma potential measurement target plasma and the mass analyzer, the potential of the mass analyzer is applied continuously or intermittently from a voltage lower than the potential of the plasma potential measurement target plasma to a higher voltage, Measuring an applied voltage and a current flowing through the bias power supply;
Calculating the potential Vp of the plasma potential measurement target plasma from analysis by a single probe method from the relationship between the applied voltage and the current flowing through the mass analyzer;
Obtaining an ion velocity in the plasma potential measurement target plasma from the relationship between the plasma potential measurement target plasma potential Vp and the a, k;
A plasma potential and ion velocity measuring method including: The mass analyzer is an E × B type mass analyzer, the mass analysis condition X is a ratio (E / B) of the electric field intensity E and the magnetic flux density B, and a in the regression equation is the mass analyzer. (M / Z) (1 / 2e), where Vb = aX ² , where m is the mass of the same ion detected by (2), Z is the valence of the ion, and e is the elementary charge.
− (K + Vp) is
Vb = [(m / Z) / 2e)] × (E / B) ² − (mv ₀ ² / 2Ze + Vp)
The plasma potential and ion velocity measuring method according to claim 1. The mass analyzer is a magnetic field deflection type mass analyzer, and the mass analysis condition X is a product (r × B) of a magnetic flux density B and a flight orbit radius r of ions by the mass analyzer, and a in the regression equation Is (Z / m) × e / 2, where m is the mass of the same ion detected by the mass analyzer, Z is the valence of the ion, and e is the elementary charge of the ion. = AX ²
− (K + Vp) is
Vb = [(Z / m) × e / 2] × (r × B) ² − (mv ₀ ² / 2Ze + Vp)
The plasma potential and ion velocity measuring method according to claim 1. A mass analyzer capable of mass spectrometry of ions in the plasma to be arranged with respect to the potential measurement target plasma;
A bias power source for applying a voltage between the mass analyzer and the plasma;
A plasma potential and ion velocity calculator,
In measuring the plasma potential, at least two different voltages are applied to the bias power source between the mass analyzer and the plasma, respectively, and mass analysis of ions in the plasma is performed on the mass analyzer. Then, for each voltage Vb of the at least two different voltages, a mass analysis condition X corresponding to the mass analyzer that can detect the same ion as the other voltage of the at least two different voltages is obtained. It is possible,
The plasma potential and ion velocity calculation unit obtains a predetermined expression Vb = aX ² − (k + Vp) (k is set to the data of each voltage Vb and the mass analysis condition X corresponding to the voltage thus obtained. mv ₀ ² / 2Ze, where m, v _{0 and} Z are the mass of the ion, the initial velocity, the number of charges, and e is the elementary charge, respectively.) Vp is the plasma potential of the potential measurement target plasma) By fitting the regression equation as a formula using the least squares method, a and (k + Vp) in the regression formula are calculated respectively.
Further, between the plasma potential measurement target plasma and the mass analyzer, continuously or intermittently applied from a voltage at which the potential of the mass analyzer is lower than the potential of the plasma potential measurement target plasma to a higher voltage, The applied voltage and the current flowing through the bias power source are measured, and from the relationship between the applied voltage and the current flowing through the mass analyzer, the potential Vp of the plasma potential measurement target plasma from analysis by a single probe method,
An apparatus for measuring plasma potential and ion velocity, wherein the ion velocity in the plasma potential measurement target plasma can be obtained from the relationship between the plasma potential measurement target plasma potential Vp and the a and k. A portion for collecting data of the voltage Vb and the corresponding mass analysis condition X and a plasma potential and ion velocity measuring unit including the plasma potential and ion velocity calculating unit are provided, and the portion for collecting the data is the plasma In the measurement of the electric potential, at least two different voltages are applied to the bias power source between the mass analyzer and the plasma to cause the mass analyzer to perform mass analysis of ions in the plasma, For each voltage Vb of the at least two different voltages, a mass analysis condition X corresponding to the mass analyzer capable of detecting the same ions as in the other voltages of the at least two different voltages is obtained.
The plasma potential calculation unit fits the voltage Vb and the data of the mass analysis condition X corresponding to the voltage thus obtained to the equation Vb = aX ² − (k + Vp) using the least square method. 5. The plasma potential according to claim 4, wherein a and k for calculating the ion velocity are obtained by calculating a and (k + Vp) in the equation, respectively. And ion velocity measuring device. The mass analyzer is an E × B type mass analyzer, the mass analysis condition X is a ratio (E / B) of the electric field intensity E and the magnetic flux density B, and a in the regression equation is the mass analyzer. (M / Z) / 2e, where Vb = aX ² , where m is the mass of the same ion detected by m, Z is the valence of the ion, and e is the elementary charge of the ion.
− (K + Vp) is
Vb = [(m / Z) / 2e] × (E / B) ² − (k + Vp)
The plasma potential and ion velocity measuring device according to claim 4 or 5. The mass analyzer is a magnetic field deflection type mass analyzer, and the mass analysis condition X is a product (r × B) of a magnetic flux density B and a flight orbit radius r of ions by the mass analyzer, and a in the regression equation Is (Z / m) × e / 2, where m is the mass of the same ion detected by the mass analyzer, Z is the valence of the ion, and e is the elementary charge of the ion, and Vb = AX ²
− (K + Vp) is
Vb = [(Z / m) × e / 2] × (r × B) ² − (k + Vp)
The plasma potential and ion velocity measuring device according to claim 4 or 5.   8. A plasma processing apparatus capable of generating plasma in a vacuum chamber and performing a target process on an object to be processed under the plasma, wherein the plasma potential and the ion velocity according to claim 4 are used. A plasma processing apparatus comprising a measuring device.   9. The plasma processing apparatus according to claim 8, wherein the apparatus is capable of performing one or more processes selected from film formation, ion implantation, etching, and article surface cleaning. A program for causing a computer to execute at least part of a procedure for performing the plasma potential and ion velocity measurement method according to claim 1, 2, or 3, wherein at least two different voltages are provided between the mass analyzer and the plasma. Is applied to each of them, and in performing the mass analysis, for each voltage Vb of the at least two different voltages, the same ions as those of the other voltages of the at least two different voltages are detected. The step of reading the data of each voltage Vb obtained by obtaining the mass analysis condition X corresponding to the mass analyzer that can be performed and the data of the mass analysis condition X corresponding to the voltage, and the formula Vb = aX ^{2 in the} read data -By fitting (k + Vp) using the least squares method, a and (k + Vp) in the equation are calculated, respectively. Further, between the plasma potential measurement target plasma and the mass analyzer, continuously or intermittently from a voltage at which the potential of the mass analyzer is lower than a potential of the plasma potential measurement target plasma to a higher voltage. Applying, measuring the applied voltage and the current flowing to the bias power source, from the relationship between the applied voltage and the current flowing to the mass analyzer, from the analysis by a single probe method, the potential Vp of the plasma potential measurement target plasma,
The program for making a computer perform the step which calculates | requires the ion velocity in the said plasma potential measurement object plasma from the relationship between the electric potential Vp of the said plasma potential measurement object plasma, and said a, k. A computer-readable recording medium recording a program for causing a computer to execute at least a part of a procedure for carrying out the plasma potential and ion velocity measuring method according to claim 1, 2, or 3.
Mass analysis is performed by applying at least two different voltages between the mass analyzer and the plasma, and at least two different voltages Vb of the at least two different voltages are used in performing the mass analysis. Among the voltages, the same ions as in the case of other voltages can be detected. Each of the voltages Vb obtained by obtaining the mass analysis condition X corresponding to the mass analyzer and the mass analysis condition X corresponding to the voltage can be detected. A step of reading data and a step of calculating a and (k + Vp) in the equation by fitting the read data to the equation Vb = aX ² − (k + Vp) using a least square method, ,
Between the plasma potential measurement target plasma and the mass analyzer, the potential of the mass analyzer is applied continuously or intermittently from a voltage lower than the potential of the plasma potential measurement target plasma to a higher voltage, The applied voltage and the current flowing through the bias power source are measured. From the relationship between the applied voltage and the current flowing through the mass analyzer, the plasma potential measurement target plasma potential Vp and the plasma potential measurement target are analyzed from a single probe method. A computer-readable recording medium storing a program for causing a computer to execute a step of obtaining an ion velocity in the plasma potential measurement target plasma from the relationship between the plasma potential Vp and the a and k.

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