Non-contact plasma monitoring method and non-contact plasma monitoring device using the same

Abstract

A non-contact plasma monitoring method and a non-contact plasma monitoring device using the same are disclosed. The non-contact plasma monitoring method may include: a first step of arranging one or more RF sensors outside an inductively coupled plasma generator including an antenna, and measuring, as functions of time, the induced electromotive forces induced in the RF sensors by the antenna; a second step of Fourier-transforming the functions of the induced electromotive forces with respect to each time, and then deriving the amplitude values of the nth harmonics; and a third step of deriving the state of the plasma in the plasma generator from the amplitude values of the respective nth harmonics.

Description

[Technical Field]

[0001] The present invention relates to a non-contact plasma monitoring method and a non-contact plasma monitoring device using the method. [Background technology]

[0002] During operation of a plasma generator, a diagnostic device is installed directly inside the plasma reactor to measure plasma conditions such as plasma electron density and electron temperature. However, this method can cause contamination of the diagnostic device depending on process conditions. Furthermore, if the diagnostic device is turned on during a process, it can destabilize the process and introduce impurities. Therefore, a method for measuring plasma conditions outside the plasma generator is required. Summary of the Invention [Problem to be solved by the invention]

[0003] An object of the present invention is to provide a non-contact plasma monitoring method that can measure the plasma state outside the plasma reactor without installing a diagnostic device inside the plasma reactor.

[0004] Another object of the present invention is to provide a non-contact plasma monitoring device that embodies the non-contact plasma monitoring method. [Means for solving the problem]

[0005] In one aspect, the present invention provides a non-contact plasma monitoring method, including a first step of disposing one or more RF sensors outside an inductively coupled plasma (ICP) generator including an antenna and measuring induced electromotive forces induced in the RF sensors by the antenna as a function of time, a second step of Fourier transforming the function of the induced electromotive forces with respect to each time and deriving amplitude values ​​of n-th harmonic, and a third step of deriving a state of plasma in the plasma generator from the amplitude values ​​of each n-th harmonic, where n may be a natural number greater than or equal to 1.

[0006] Through the above steps, the non-contact plasma monitoring method of the present invention can monitor the plasma state outside the plasma generator.

[0007] In one embodiment, the antenna may be formed on at least one plane of the inductively coupled plasma generator. In one embodiment, the antenna may be formed on one plane above the inductively coupled plasma generator. In one embodiment, the antenna may be formed in a spiral shape on the plane above the inductively coupled plasma generator. In one embodiment, each RF sensor may be disposed outside the antenna. In one embodiment, each RF sensor may be disposed so that a plane formed by each RF sensor is perpendicular to a plane on which the antenna is formed. In one embodiment, each RF sensor may be disposed so that a plane formed by each RF sensor is perpendicular to a plane on which the spiral antenna is formed.

[0008] By disposing the RF sensor as described above, an induced electromotive force can be induced from the antenna to the RF sensor.

[0009] In one embodiment, n is 1, and the third step may derive a linear proportional relationship between the plasma electron density directly measured inside the plasma generator and each of the amplitude values, and then derive an unknown plasma electron density from the amplitude value measurement results using the linear proportional relationship.

[0010] In one embodiment, two or more RF sensors may be disposed in the first step. In one embodiment, the antenna may be formed in a spiral shape on a single plane above the inductively coupled plasma generator. In one embodiment, two or more of the RF sensors may be disposed so that the radial distances of the spiral formed by the antenna are different. In one embodiment, in the third step, a distribution of unknown plasma electron density may be derived by deriving plasma electron density from each RF sensor.

[0011] In one embodiment, each of the RF sensors may be positioned over the antenna.

[0012] In one embodiment, the third step may determine whether impurities have been introduced into the plasma by determining whether the amplitude value of the nth harmonic has changed by a predetermined level or more. In one embodiment, n may be 5 or 6.

[0013] In another aspect, the present invention provides a non-contact plasma monitoring device including a sensor unit including one or more RF sensors and a recording unit capable of measuring an induced electromotive force induced in each of the RF sensors and recording the measured electromotive force as a function of time, and a monitor unit including a calculation unit capable of Fourier transforming each of the recorded functions of the induced electromotive force as a function of time, and an output unit for deriving a plasma state through an amplitude value of an nth harmonic from each Fourier transform result of the calculation unit, where n may be a natural number greater than or equal to 1.

[0014] The above-described apparatus can ensure the stability of the plasma by monitoring the state of the plasma outside the plasma generator.

[0015] In one embodiment, the non-contact plasma monitoring device may monitor plasma in an inductively coupled plasma generator having an antenna formed on at least one plane. In one embodiment, the non-contact plasma monitoring device may monitor plasma in an inductively coupled plasma generator having an antenna formed on one plane above. In one embodiment, the non-contact plasma monitoring device may monitor plasma in an inductively coupled plasma generator having a spiral-shaped antenna formed on one plane above. In one embodiment, each of the RF sensors may be formed to be disposed outside the antenna. In one embodiment, each of the RF sensors may be formed such that a plane formed by the RF sensor is perpendicular to a plane on which the antenna is formed. In one embodiment, each of the RF sensors may be formed such that a plane formed by the RF sensor is perpendicular to a plane on which the spiral-shaped antenna is formed.

[0016] By disposing the RF sensor as described above, an induced electromotive force can be generated from the antenna in the RF sensor of the device.

[0017] In one embodiment, n is 1, and the output unit derives a linear proportional relationship between the plasma electron density directly measured inside the plasma generator and each of the amplitude values, and then derives an unknown plasma electron density from the amplitude value measurement results using the linear proportional relationship.

[0018] In one embodiment, the sensor unit may include two or more RF sensors. In one embodiment, the antenna may be spirally formed on a single plane above the inductively coupled plasma generator. In one embodiment, two or more of the RF sensors may be arranged at different radial distances on the spiral formed by the antenna. In one embodiment, the output unit may derive a distribution of unknown plasma electron density by deriving plasma electron density from each of the RF sensors.

[0019] In one embodiment, one or more of the RF sensors may be positioned to be located on the antenna.

[0020] In one embodiment, the output unit may determine whether impurities have flowed into the plasma by determining whether the amplitude value of the nth harmonic has changed by a predetermined level or more. In one embodiment, n may be 5 or 6. [Effects of the Invention]

[0021] The non-contact plasma monitoring device according to the embodiment of the present invention can monitor the plasma state, including the plasma electron density and the presence or absence of impurities, from outside the plasma, thereby ensuring the stability of the plasma.

[0022] The non-contact plasma monitoring device according to the embodiment of the present invention can monitor the plasma state while maintaining the stability of the plasma by implementing the non-contact plasma monitoring method. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a flowchart illustrating a method for non-contact plasma monitoring according to an embodiment of the present invention. [Figure 2] 1 shows the configuration of a non-contact plasma monitoring device according to an embodiment of the present invention. [Figure 3]1 is a diagram illustrating an embodiment of a method for arranging a plurality of RF sensors when the non-contact plasma monitoring device according to an embodiment of the present invention includes two or more RF sensors. [Figure 4] 10 is a graph showing the results of an experimental example of the present invention. [Figure 5] 10 is a graph showing the results of an experimental example of the present invention. [Figure 6] 10 is a graph showing the results of an experimental example of the present invention. [Figure 7] 10 is a graph showing the results of an experimental example of the present invention. [Figure 8] 10 is a graph showing the results of an experimental example of the present invention. [Figure 9] 10 is a graph showing the results of an experimental example of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention may be modified in various ways and may have various forms. Specific examples are illustrated in the drawings and described in detail herein. However, this is not intended to limit the present invention to the particular disclosed form, but it should be understood that the present invention encompasses all modifications, equivalents, and alternatives within the spirit and technical scope of the present invention. In describing the various drawings, like reference numerals are used to refer to like elements. In the accompanying drawings, the dimensions of structures are exaggerated to clarify the present invention.

[0025] The terms used in this application are used only to describe specific embodiments and are not intended to limit the present invention. The singular expressions include the plural expressions unless the context clearly dictates otherwise. In this application, the terms "comprise" or "have" are intended to specify the presence of features, numbers, steps, operations, components, or combinations thereof described in the specification, and should be understood not to preclude the presence or additional possibility of one or more other features, numbers, steps, operations, components, or combinations thereof.

[0026] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms as defined in commonly used dictionaries should be interpreted to have a meaning consistent with the meaning they have in the context of the relevant art, and should not be interpreted in an idealized or overly formal sense unless expressly defined in this application.

[0027] FIG. 1 is a flow chart illustrating a method for non-contact plasma monitoring according to an embodiment of the present invention.

[0028] Referring to FIG. 1, a non-contact plasma monitoring method according to an embodiment of the present invention includes a first step (S110) of disposing one or more RF sensors outside an inductively coupled plasma (ICP) generator including an antenna and measuring an induced electromotive force induced in the RF sensor by the antenna as a function of time; a second step (S120) of Fourier-transforming the function of the induced electromotive force with respect to each time and deriving an amplitude value of each nth harmonic; and a third step (S130) of deriving a plasma state within the plasma generator from the amplitude value of each nth harmonic. Here, n may be a natural number greater than or equal to 1. Through these steps, the non-contact plasma monitoring method of the present invention can monitor a plasma state outside the plasma generator.

[0029] The first step (S110) is a step of measuring an induced electromotive force generated from a plasma generator, particularly as a function of time. The plasma generator, particularly an inductively coupled plasma generator, may include an antenna, and plasma may be generated inside the plasma generator by a current applied to the antenna and a change in the current, and a change in the surrounding magnetic field may occur from the antenna. Therefore, when an RF sensor is disposed around the antenna, an induced electromotive force may be induced in the RF sensor due to the change in the magnetic field. Therefore, the RF sensor may be disposed in a position and orientation where an induced electromotive force can be induced from the antenna. In one embodiment, the antenna may be formed on at least one plane of the inductively coupled plasma generator. In one embodiment, the antenna may be formed on a plane above the inductively coupled plasma generator. In one embodiment, the antenna may be formed in a spiral shape on a plane above the inductively coupled plasma generator. In one embodiment, each RF sensor may be disposed outside the antenna. In one embodiment, each RF sensor may be disposed so that a plane formed by each RF sensor is perpendicular to a plane on which the antenna is formed. In one embodiment, the RF sensors may be arranged such that a plane formed by the RF sensors is perpendicular to a plane on which the spiral antenna is formed. By arranging the RF sensors in this manner, an induced electromotive force can be induced from the antenna to the RF sensors.

[0030] The second step (S120) is a process of performing a Fourier transform on the time function of the induced electromotive force. As known in the art, a Fourier transform can decompose a time function into frequency components, which can be numbered in order from the most dominant frequency component to the first harmonic, second harmonic, and so on. That is, in the context of this specification, a harmonic refers to the result of a Fourier transform, an nth harmonic refers to the nth harmonic wave in the order of the dominant frequency component appearing in the Fourier transform, and the amplitude value of the nth harmonic refers to the amplitude value of the harmonic wave. The second step (S120) performs a Fourier transform on the time function of the induced electromotive force to separate each frequency component and derive the amplitude value of each frequency component or a specific nth harmonic.

[0031] The third step (S130) is a step for extracting information about the plasma state from the amplitude value derived in the second step (S120). The amplitude value of the nth harmonic is derived in the second step (S120), and the value of n determines how close the amplitude value is to the main frequency component of the time function of the induced electromotive force. Therefore, a specific plasma state can be derived from a combination of the second step (S120) and the third step (S130) in the non-contact plasma monitoring method according to an embodiment of the present invention.

[0032] In one embodiment, n is 1, and the third step (S130) derives a linear proportional relationship between the plasma electron density measured directly inside the plasma generator and each of the amplitude values, and then derives the unknown plasma electron density from the amplitude value measurement results based on the linear proportional relationship. The direct measurement method inside the plasma generator may be measurement using a probe. As described above, the method of directly measuring the plasma electron density inside the plasma generator is a conventional technique that has the disadvantage of affecting the plasma electron density. The non-contact plasma monitoring method according to an embodiment of the present invention is based on the discovery that the plasma electron density measured by the conventional technique has a linear proportional relationship with the amplitude value of the first harmonic of the Fourier transform result of the induced electromotive force as a function of time derived in the second step (S120) and the third step (S130). In one embodiment, the non-contact plasma monitoring method according to an embodiment of the present invention can be calibrated using the conventional direct measurement method.

[0033] The above method is related to the relative positional relationship between the RF sensor and the antenna and the electron density at the point to be measured. Therefore, if two or more RF sensors are used, the plasma electron density can be measured at multiple points. This makes it possible to measure the unknown electron density distribution. In one embodiment, two or more RF sensors may be disposed in the first step (S110). In one embodiment, two or more of the RF sensors may be disposed at different radial distances in the spiral formed by the antenna. In one embodiment, in the third step (S130), the plasma electron density is derived from each RF sensor, thereby deriving the unknown plasma electron density distribution.

[0034] The RF sensors are not particularly limited as long as they are disposed around the antenna, particularly above the antenna, and are positioned so that an induced electromotive force can be induced. In one embodiment, the RF sensors may be disposed above the antenna.

[0035] As described above, measuring the plasma electron density or the plasma electron density distribution is only one embodiment of a plasma state that can be derived by the non-contact plasma monitoring method according to an embodiment of the present invention, and the type of plasma state is not particularly limited as long as a correlation with other plasma states measured by conventional techniques can be derived using the above method.

[0036] In one embodiment, the third step (S130) may determine whether impurities have been introduced into the plasma by determining whether the amplitude value of the nth harmonic has changed by a predetermined level or more. In one embodiment, n may be 5 or 6.

[0037] As described above, the non-contact plasma monitoring device according to the embodiment of the present invention can monitor the plasma state, including the plasma electron density and the presence or absence of impurities, outside the plasma, thereby ensuring the stability of the plasma.

[0038] FIG. 2 shows the configuration of a non-contact plasma monitoring device according to an embodiment of the present invention.

[0039] Referring to FIG. 2, a non-contact plasma monitoring device according to an embodiment of the present invention provides a non-contact plasma monitoring device 1 including a sensor unit 10 including one or more RF sensors 11 and a recording unit 12 that measures induced electromotive forces induced in each RF sensor 11 and records the measured values ​​as a function of time; a monitor unit 20 including a calculation unit 21 that performs a Fourier transform on the recorded functions of the induced electromotive forces over time, and an output unit 22 that derives the state of plasma as an amplitude value of an nth harmonic from each Fourier transform result of the calculation unit 21. Here, n may be a natural number greater than or equal to 1. Such a device can ensure plasma stability by monitoring the state of plasma outside the plasma generator.

[0040] The non-contact plasma monitoring device according to an embodiment of the present invention is one example of a device that can implement the non-contact plasma monitoring method described above, and descriptions regarding terms that are identical or similar to those used in the detailed description of the non-contact plasma monitoring method described above can be applied identically or similarly to the same or similar components of the non-contact plasma monitoring device according to an embodiment of the present invention.

[0041] The RF sensor 11 is a component in which an induced electromotive force can be induced from a plasma generator or a part of a plasma generator. In the context of this specification, an RF sensor is a device capable of sensing a signal having a radio frequency (RF), and may include, for example, a coil. In the context of this specification, a coil refers to an electric wire member in which a conductor forms one or more closed surfaces, and when a change occurs in the magnetic field passing through the closed surfaces formed by the conductor, an electromotive force is induced in the conductor so that a current can flow in the conductor.

[0042] There may be one or more RF sensors 11. In one embodiment, there may be one RF sensor 11. In another embodiment, there may be more than one RF sensor 11.

[0043] The recording unit 12 is a device that can measure and record the induced electromotive force induced in the RF sensor 11. The induced electromotive force can be recorded as a function of time, and the recording unit 12 may further include a separate storage device. In one embodiment, the recording unit 12 can directly measure the induced electromotive force. In another embodiment, the recording unit 12 can measure the induced electromotive force by measuring a physical quantity other than the induced electromotive force, such as a current, and then calculating the electromotive force. In this case, the recording unit 12 may further include a separate calculation device.

[0044] The calculation unit 21 can identify component frequencies and derive the amplitude value of each frequency by Fourier transforming the function of the induced electromotive force versus time measured and recorded by the recording unit 12. In one embodiment, the calculation unit 21 can derive the amplitude value of the nth harmonic from the Fourier transform result.

[0045] The output unit 22 can derive the plasma state from the information on the component frequency, particularly the amplitude value of the nth harmonic, derived by the calculation unit 21. In one embodiment, the method by which the output unit 22 derives the plasma state is related to the correlation between the specific plasma state measured by conventional techniques and the information on the component frequency, particularly the amplitude value of the nth harmonic, derived by the calculation unit 21, and can be derived by calibration using a linear correlation.

[0046] 2, the calculation unit 21 and the output unit 22 are shown as separate components, but this is for illustrative purposes only and is intended to explain functional aspects. The calculation unit 21 and the output unit 22 may be integrated into a single component if the object of the present invention can be achieved and all of the functions of the calculation unit 21 and the output unit 22 can be performed. In one embodiment, the calculation unit 21 and the output unit 22 may be integrated into a single computing device.

[0047] 2, the recording unit 12 and the monitor unit 20 are shown as separate components, but this is merely an example and is for the purpose of explaining functional aspects. The recording unit 12 and the monitor unit 20 may be integrated into a single component if the objectives of the present invention can be achieved and all of the functions of the recording unit 12 and the monitor unit 20 can be performed. In one embodiment, the recording unit 12 and the monitor unit 20 may be integrated into a single computing device.

[0048] Referring now to FIG. 2, the non-contact plasma monitoring device can monitor plasma in an inductively coupled plasma generator. In one embodiment, the non-contact plasma monitoring device can monitor plasma in an inductively coupled plasma generator having an antenna formed on at least one plane. In one embodiment, the non-contact plasma monitoring device can monitor plasma in an inductively coupled plasma generator having an antenna formed on one plane above it. In one embodiment, the non-contact plasma monitoring device can monitor plasma in an inductively coupled plasma generator having a spiral antenna formed on one plane above it. While the antenna is shown in FIG. 2 as having a spiral shape, this is merely an example and the shape of the antenna is not particularly limited. Although the inductively coupled plasma generator and / or the antenna of the inductively coupled plasma generator are not included or integrated in the non-contact plasma monitoring device according to an embodiment of the present invention, the non-contact plasma monitoring device and / or the RF sensor 11 included in the device can be positioned and oriented to be optimized for measuring the plasma state of a general inductively coupled plasma generator and / or a specific inductively coupled plasma generator. In one embodiment, each RF sensor can be configured to be disposed outside the antenna. In one embodiment, each RF sensor may be formed such that a plane formed by the RF sensor is perpendicular to a plane on which the antenna is formed. In another embodiment, each RF sensor 11 may be formed such that a plane formed by the RF sensor is perpendicular to a plane on which the spiral antenna is formed. By arranging the RF sensors as described above, an induced electromotive force may be generated from the antenna in the RF sensor of the device.

[0049] The component frequency information output by the calculation unit 21 after Fourier transform and the plasma state derived by the output unit 22 are not particularly limited as long as a correlation therebetween can be derived. In one embodiment, n is 1, i.e., the component frequency information derived by the calculation unit 21 is the amplitude value of the first harmonic, and the output unit 22 derives a linear proportional relationship between the plasma electron density directly measured inside the plasma generator and each of the amplitude values, and then derives the unknown plasma electron density from the amplitude value measurement result using the linear proportional relationship. In one embodiment, the non-contact plasma monitoring device according to an embodiment of the present invention can be pre-calibrated using values ​​derived by a conventional measuring device inserted into the plasma, including a probe type.

[0050] Referring now to FIG. 2, in one embodiment, the sensor unit 10 may include two or more RF sensors 11. FIG. 3 is a diagram illustrating an embodiment of a method for arranging a plurality of RF sensors when a non-contact plasma monitoring device according to an embodiment of the present invention includes two or more RF sensors. Referring to FIG. 3 together with FIG. 2, in one embodiment, two or more of the RF sensors 11 may be arranged at different radial distances in the spiral formed by the antenna. In this case, in one embodiment, the output unit may derive the plasma electron density from each of the RF sensors to derive the distribution of the unknown plasma electron density.

[0051] Continuing with reference to FIG. 3, in one embodiment, one or more of the RF sensors may be positioned to be located on the antenna.

[0052] 2, in another embodiment, the calculation unit 21 can derive amplitude values ​​of multiple harmonics, from which the output unit 22 can derive plasma-related information in addition to plasma electron density and plasma electron density distribution. In one embodiment, the output unit 22 can determine whether impurities have flowed into the plasma by determining whether the amplitude value of the nth harmonic has changed by more than a predetermined level. In one embodiment, n may be 5 or 6.

[0053] As described above, the non-contact plasma monitoring device according to the embodiment of the present invention can monitor the plasma state while maintaining the stability of the plasma by implementing the non-contact plasma monitoring method.

[0054] Hereinafter, embodiments of the present invention will be described. However, the embodiments described below are merely some of the embodiments of the present invention, and the scope of the present invention is not limited to the following embodiments.

[0055] Manufacture of non-contact plasma monitoring devices

[0056] The RF sensors were positioned on the antenna of a specific inductively coupled plasma generator. The inductively coupled plasma generator included a spiral antenna, and the RF sensors were positioned radially at points 40, 88, 120, 152, 180, and 200 mm from the center of the spiral, respectively, with the plane formed by the RF sensors perpendicular to the plane formed by the spiral. The induced electromotive force induced in each RF sensor was measured over time, and the function of the induced electromotive force over time was Fourier transformed. The RF sensors were then connected to a computing device equipped with software capable of deriving the amplitude value of the nth harmonic. In this manner, a non-contact plasma monitoring device according to an embodiment of the present invention was manufactured.

[0057] Calibration and measurement of non-contact plasma monitoring devices

[0058] The inductively coupled plasma generator was charged with nitrogen gas and operated at operating pressures of 10, 20, and 30 mTorr. The power applied to the antenna was 400, 600, and 800 W. A probe capable of measuring the electron density of the plasma was inserted into the inductively coupled plasma generator in advance, and the amplitude value of the nth harmonic derived by the non-contact plasma monitoring device and its correlation were analyzed.

[0059] Figure 4 shows the induced electromotive force as a function of time. The left side of Figure 4 shows the experimental results when the operating pressure was fixed at 20 mTorr, and the right side shows the experimental results when the applied power was fixed at 600 W.

[0060] During the above operation, the probe simultaneously measured the electron density, and the results are shown in the graph of FIG.

[0061] The amplitude of the first harmonic was compared with the electron density measured by the probe depending on the operating conditions of the plasma generator. The results are shown in a graph in Figure 6. Referring to Figure 6, it can be seen that the electron density measured directly by the probe and the amplitude of the first harmonic derived by the plasma monitoring device tend to be similar.

[0062] Figure 7 shows the results of comparing the direct measurement value by the probe and the derived value based on the amplitude value of the first harmonic to quantitatively confirm the similar tendency. Referring to Figure 7, the dot graph of the two values ​​shows a linear trend, R 2 It can be seen that the value is 0.95835, which indicates a very high linear correlation. This confirms that the electron density and its distribution in the inductively coupled plasma device can be derived from the amplitude value of the first harmonic without direct measurement using the probe.

[0063] Figure 8 is a graph showing the change in the amplitude of each nth harmonic as the probe moves within the inductively coupled plasma generator. Center indicates that the probe is located at the center of the plasma generator, and edge and edge2 indicate that the probe is located at the ends of the generator. Referring to Figure 8, the amplitude of the first harmonic does not change significantly with the position on the probe, while the amplitudes of the fifth and sixth harmonics clearly tend to increase and then decrease, or decrease and then increase. This confirms that when the amplitudes of the fifth and sixth harmonics fluctuate more than a predetermined value, this can be used as a detection signal indicating that impurities have entered the plasma.

[0064] Simulation of spatial magnetic field distribution

[0065] Figure 9 shows the results of a simulation of the spatial magnetic field distribution while controlling the current applied to the antenna on the plasma generator. Referring to Figure 9, it can be seen that the magnetic field distribution around the antenna changes as the antenna operating conditions change. Therefore, if an RF sensor is placed around the antenna, the induced electromotive force measured by the RF sensor can be compared with the magnetic field value obtained through simulation, ultimately deriving plasma variables such as electron density and temperature. This confirms that the plasma state and uniformity can be monitored outside the plasma generator using an RF sensor.

[0066] Although the present invention has been described above with reference to preferred embodiments, it should be understood that those skilled in the art can make various modifications and changes to the present invention without departing from the spirit and scope of the present invention as set forth in the following claims.

Claims

1. A first step of disposing one or more RF sensors outside an inductively coupled plasma (ICP) generator including an antenna and measuring an induced electromotive force induced in the RF sensor by the antenna as a function of time; a second step of Fourier transforming the function of the induced electromotive force for each of the times and then deriving the amplitude values ​​of the n-th harmonic; and a third step of deriving a state of plasma in the plasma generator from the amplitude value of each of the n-th harmonic; Including, The non-contact plasma monitoring method, wherein n is a natural number of 1 or more.

2. the antenna is formed on at least one plane of the inductively coupled plasma generator; each of the RF sensors being disposed outside the antenna; The non-contact plasma monitoring method according to claim 1 .

3. wherein n is 1; 2. The non-contact plasma monitoring method of claim 1, wherein the third step derives a linear proportional relationship between the plasma electron density directly measured inside the plasma generator and each of the amplitude values, and then derives the unknown plasma electron density from the amplitude value measurement results through the linear proportional relationship.

4. In the first step, two or more RF sensors are arranged; 4. The non-contact plasma monitoring method according to claim 3, wherein in the third step, a distribution of unknown plasma electron density is derived by deriving the plasma electron density from each of the RF sensors.

5. 3. The non-contact plasma monitoring method of claim 2, wherein the third step determines whether impurities have flowed into the plasma depending on whether the amplitude value of the nth harmonic has changed by a predetermined level or more.

6. 6. The non-contact plasma monitoring method according to claim 5, wherein n is 5 or 6.

7. a sensor unit including one or more RF sensors and a recording unit capable of measuring an induced electromotive force induced in each of the RF sensors and recording the measured electromotive force as a function of time; and a monitor unit including a calculation unit capable of performing a Fourier transform on the function of each induced electromotive force according to the recorded time, and an output unit for deriving the state of plasma from the amplitude value of the nth harmonic from each Fourier transform result of the calculation unit; Including, The non-contact plasma monitoring device, wherein n is a natural number of 1 or more.

8. The non-contact plasma monitoring device may monitor plasma in an inductively coupled plasma generator having an antenna formed on at least one plane, The non-contact plasma monitoring device according to claim 7 , wherein each of the RF sensors is configured to be disposed outside the antenna.

9. wherein n is 1; 8. The method of claim 7, wherein the output unit derives a linear proportional relationship between the plasma electron density directly measured inside the plasma generator and each of the amplitude values, and then derives the unknown plasma electron density from the amplitude value measurement results according to the linear proportional relationship. Non-contact plasma monitoring device.

10. the sensor unit includes two or more RF sensors; The output unit according to claim 9 , deriving a distribution of unknown plasma electron densities by deriving plasma electron densities from each of the RF sensors. Non-contact plasma monitoring device.

11. 9. The non-contact plasma monitoring device of claim 8, wherein the output unit determines whether impurities have flowed into the plasma based on whether the amplitude value of the nth harmonic has changed by a predetermined level or more.

12. The non-contact plasma monitoring device according to claim 11 , wherein n is 5 or 6.

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