WO2014030919A1

WO2014030919A1 - Method and apparatus for monitoring ion distribution in plasma sheath

Info

Publication number: WO2014030919A1
Application number: PCT/KR2013/007486
Authority: WO
Inventors: 김병환
Original assignee: 세종대학교 산학협력단
Priority date: 2012-08-22
Filing date: 2013-08-21
Publication date: 2014-02-27
Also published as: KR101398578B1; KR20140026675A

Abstract

The present invention relates to a method and apparatus for monitoring ion distribution in a plasma sheath. The method comprises the steps of: taking, as an input, a first captured image of particles in a plasma chamber in a vacuum state; taking, as an input, a second captured image of the particles in the plasma chamber when gas has been injected into the plasma chamber and power is supplied to the plasma chamber; acquiring a first particle distribution and a second particle distribution using the grayscale values of the pixels constituting each sheath region in the first and second captured images; acquiring a corrected second particle distribution by subtracting the first particle distribution from the second particle distribution based on the grayscale values; and monitoring the ion distribution for the sheath region using the corrected second particle distribution. According to the present invention, the ion distribution in the sheath region can be easily monitored on a real-time basis using the grayscale values of the pixels constituting the sheath region in the captured images of the particles in the chamber.

Description

Method and apparatus for monitoring ion distribution in plasma sheath

The present invention relates to a method and apparatus for monitoring ion distribution in a plasma sheath, and more particularly, to a method and apparatus for monitoring ion distribution in a plasma sheath capable of monitoring the distribution of ions in a sheath region occurring in a plasma state. It is about.

A sheath region in a plasma refers to a thin layer of non-emitting region that appears to surround the plasma around the plasma. The distribution of ion energy in the sheath region indicates the distribution of the energy of the ions and their number. In general, the ion energy distribution function (IEDF) is required for the analysis, monitoring and optimization of thin film etching or deposition processes. In order to obtain a uniform thin film and an etching pattern, a uniform IEDF is required. In particular, an abnormal occurrence of ion energy during the etching process damages a thin film or an etching pattern to be manufactured, and thus, a system for measuring the IEDF in real time is required. .

Conventionally, the IEDF measurement is performed by using an Electron Spectrum Analyzer (ESA) method or a non-contact ion energy distribution measurement method. Here, the ESA method does not provide an ion energy distribution in real time. In addition, the non-contact ion energy distribution measurement method combines a physical plasma model with electrical real-time data measured using an IV probe to provide an IEDF, which is different from the actual distribution due to the assumptions inherent in the physical sheath model. Can be calculated. Background art regarding the plasma processing apparatus using the IEDF measurement has been disclosed in Korea Patent Publication No. 2011-0116955.

Unlike the constant ion energy distribution function, the electron energy distribution function (EEDF) is required for the analysis of dissociation and ionization of gases. However, until now, there is no device capable of measuring EEDF in real time, and there is no method to measure electron energy distribution in three-dimensional plasma space.

The present invention provides a method and apparatus for monitoring ion distribution in a plasma sheath capable of real-time monitoring of distribution of ions in the sheath region using gray scale values of pixels constituting the sheath region in the captured image of particles present in the plasma chamber. The purpose is to.

The present invention includes receiving a first captured image of particles in a plasma chamber in a vacuum state, and second particles for particles present in the plasma chamber in a state where gas is injected into the plasma chamber and power is applied thereto. Receiving a captured image, using a gray scale value of pixels constituting each sheath region in the first captured image and the second captured image, and distributing a first particle number according to the gray scale value; Acquiring a second particle number distribution, respectively, subtracting the first particle number distribution with respect to a second particle number distribution according to the gray scale value, and obtaining a corrected second particle number distribution; and Providing an ion distribution monitoring method in a plasma sheath comprising monitoring an ion distribution for the sheath region using a second particle number distribution The.

In the obtaining of the corrected second particle number distribution, an offset may be added to the subtracted particle number result.

In the monitoring of the ion distribution of the sheath region, the distribution of ions of the sheath region may be monitored using the number of particles within an arbitrary gray scale range.

The arbitrary gray scale range may be defined by the following equation.

T1 ≤ any grail scale ≤ T2

Here, T1 represents values corresponding to 17 to 23% and 55 to 60% of the maximum gray scale values for the captured image.

The monitoring of the ion distribution of the sheath region may include monitoring the ion distribution of the sheath region by using a particle number distribution within a gray scale range in which the particle number is positive in the corrected second particle number distribution. can do.

The first and second captured images may be two-dimensional images reconstructed in an arbitrary space including the sheath region in the plasma chamber.

In addition, the present invention comprises the steps of receiving a captured image of the particles present in the plasma chamber in the state that the gas is injected into the plasma chamber and the power is applied, and the pixels constituting the sheath region in the captured image Obtaining a particle number distribution according to the gray scale value using a gray scale value, and monitoring ion distribution for the sheath region using the particle number distribution according to the gray scale value It provides a method for monitoring ion distribution in the interior.

In addition, the present invention provides a first imaging image of the particles in the plasma chamber in a vacuum state, and a second imaging image of the particles present in the plasma chamber in a state where gas is injected into the plasma chamber and power is applied. A first particle number distribution and a first particle number distribution according to the gray scale value by using an image input unit respectively input and a gray scale value of pixels constituting the respective sheath areas in the first and second captured images A particle number distribution acquiring unit for acquiring each particle number distribution, and a particle number distribution for acquiring a corrected second particle number distribution by subtracting the first particle number distribution from a second particle number distribution according to the gray scale value And a correction unit, and an ion distribution monitoring unit configured to monitor ion distribution of the sheath region using the corrected second particle number distribution. It provides an ion distribution monitoring device in a sheath.

Here, the particle number distribution corrector may add an offset to the subtracted particle number result.

The ion distribution monitoring unit may monitor the distribution of ions in the sheath region using the number of particles within an arbitrary gray scale range.

The ion distribution monitoring unit may monitor the ion distribution of the sheath region using a particle number distribution within a gray scale range in which the particle number has a positive value among the corrected second particle number distribution.

In addition, the present invention, the image input unit for receiving a captured image of the particles present in the plasma chamber in a state in which gas is injected into the plasma chamber and the power is applied, and a sheath region in the captured image A particle number distribution obtaining unit for obtaining a particle number distribution according to the gray scale value using the gray scale value of the pixels, and an ion distribution for the sheath region using the particle number distribution according to the gray scale value An ion distribution monitoring apparatus in a plasma sheath including an ion distribution monitoring unit is provided.

According to the ion distribution monitoring method in the plasma sheath according to the present invention, the distribution of ions in the sheath region can be easily monitored in real time using the gray scale values of the pixels constituting the sheath region in the captured image of the particles present in the plasma chamber. There is an advantage to that.

1 is a schematic structural diagram of an optical microscope for an embodiment of the present invention.

2 is a block diagram of an ion distribution monitoring apparatus in a plasma sheath according to an embodiment of the present invention.

3 is a flowchart of a method for monitoring ion distribution in a plasma sheath using FIG. 2.

4 illustrates an example of an image acquired through step S320 of FIG. 3.

FIG. 5 shows an example of the second particle number distribution obtained by step S330 of FIG. 3.

FIG. 6 is a graph illustrating the number of pixels having a specific gray scale value for each pixel layer of FIG. 4.

FIG. 7 illustrates the number of pixels for each gray scale in the sheath region of the captured image of FIG. 4.

8 illustrates a conventional commercialized IEDF function.

9 and 10 illustrate the step S340 of FIG. 3.

FIG. 11 is a diagram illustrating a partial section after adding an offset to FIG. 10.

FIG. 12 illustrates energy distribution in an upper space except for the sheath region of FIG. 4.

13 shows particle distribution in the center of the chamber obtained by applying the equations (1) to (3).

FIG. 14 is a distribution obtained by subtracting the first particle number distribution from the second particle number distribution shown in FIG. 13.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention.

1 is a schematic structural diagram of an optical microscope for an embodiment of the present invention. Figure 1 (a) is a conventional In-Line optical system composed of a laser (Laser), a beam expander, a CCD sensor. Two windows (window 1, window 2) are required for the plasma equipment, ie the plasma chamber. The wafer is placed on the chuck and a thin film to be deposited or etched is disposed.

The light emitted by the laser extends from the beam expander to illuminate the top, including the chuck. At this time, information of the material particles that absorb, reflect, or transmit the laser light is stored in the CCD sensor. In general, the sheath space is a space where the number of electrons is smaller than the number of ionized water, which is generated near the chuck.

Figure 1 (b) is a modification of the existing On-Axis optical system is a structure without a reflector at the top of the beam splitter. 1 (b) is composed of a laser, a beam splitter, a beam expander, and a CCD sensor. One window (window 1) is required for the plasma chamber.

The light emitted by the laser is split into light in the horizontal and vertical directions in the beam splitter. The split horizontal light passes through window 1 to illuminate the top of the chuck and then reflect back from the opposite wall of the chamber. In addition, the light reflected from the wall reacts with the etching material and the plasma particles, and the distribution of the reacted particles is stored in the CCD sensor. In the case of both (a) and (b) of FIG. 1, when various filters (ex, spatial filters) are installed at the front end of the CCD sensor, the resolution of the particles may be improved.

If the image taken through FIG. 1 is used, the particle number distribution may be obtained in an arbitrary space in the horizontal (or vertical) direction of the chamber. The algorithm used for spatial decomposition of the particle number distribution uses Fresnel zone transformation.

The CCD image obtained using FIG. 1 is composed of the X and Y axes, which are originally two-dimensional planes, but the object can be distinguished from the three-dimensional space by moving the two-dimensional planes to the Z axis through reconstruction. This reconstruction technique is a known general method and is applied to the calculation of electron or ion distribution in the plasma space. Refer to Equation 1 for the recovery equation.

Equation 1

Where u (x, y) is the input image and d is the distance the object is apart. For example, the d value may refer to the distance between the CCD sensor and any point in the chamber. kx, ky are singular functions for creating Fresnel zone patterns. h (r, c) is divided into a real part and an imaginary part. Equation 2 represents the phase, and Equation 3 represents the magnitude, thereby allowing reimaging.

Equation 2

Equation 3

Equation 1 can be adjusted to restore the two-dimensional 2D particle distribution in any space in the plasma chamber through Equation 3. Equation 3 is obtained using image information of the real part and the imaginary part. The image information of the real part is similar to the image reconstructed by Equation 3, and thus may be used as a substitute for the reconstructed image.

Here, it is also possible to obtain a three-dimensional 3D particle distribution by calculating the 2D particle distribution with respect to the total distance in the horizontal (or longitudinal) direction of the plasma chamber and then combining them. That is, an EEDF (Electron energy distribution function) can be obtained at any position of the plasma in the 2D reconstructed image, and an IEDF (Ion energy distribution function) can be obtained in the sheath region adjacent to the wafer. . In addition, by combining the EEDF (or IEDF) obtained at each position, it is possible to obtain a 3D EEDF (or IEDF).

Hereinafter, an apparatus and method for monitoring ion distribution in a plasma sheath using an image captured by the optical microscope will be described in detail.

2 is a block diagram of an ion distribution monitoring apparatus in a plasma sheath according to an embodiment of the present invention. The apparatus 100 includes an image input unit 110, a particle number distribution obtaining unit 120, a particle number distribution correcting unit 130, and an ion distribution monitoring unit 140.

The image input unit 110 receives a first captured image of particles in the plasma chamber in a vacuum state. In addition, the image input unit 110 receives a second captured image of particles present in the plasma chamber in a state in which gas is injected into the plasma chamber and power is applied, that is, in a plasma state.

The first and second captured images may correspond to two-dimensional images reconstructed in an arbitrary space including the sheath region in the plasma chamber. This can be done using the method of Equations 1 to 3 above.

The particle number distribution obtaining unit 120 uses the gray scale values of pixels constituting the respective sheath areas in the first and second captured images, to determine the first particle number according to the gray scale values. Distribution and second particle number distribution are obtained, respectively.

The particle number distribution correcting unit 130 obtains a corrected second particle number distribution by subtracting the first particle number distribution from the second particle number distribution according to the gray scale value. This is to ensure that the particle number does not include the laser particles and the negative background energy that reacts with them. Here, the particle number distribution correction unit 130 adds an offset to the subtracted particle number result. This is to prevent negative particle numbers from occurring in the second particle number distribution.

The ion distribution monitoring unit 140 monitors the ion distribution of the sheath region using the corrected second particle number distribution. When the adjusted second particle number distribution is within a preset reference distribution range, it may be determined that the plasma is normal.

3 is a flowchart of a method for monitoring ion distribution in a plasma sheath using FIG. 2. Hereinafter, a method of monitoring ion distribution in the sheath space will be described in detail with reference to FIGS. 2 and 3.

First, the image input unit 110 receives a first captured image of particles in a plasma chamber in a vacuum state (S310). In the case of a vacuum state, since it does not correspond to a plasma generation state, a plasma particle is not contained in a component particle.

In addition, the image input unit 110 receives a second captured image of particles present in the plasma chamber in a state in which gas is injected into the plasma chamber and power is applied, that is, in a plasma state (S320). In such a plasma state, the constituent particles in the chamber contain plasma particles.

4 illustrates an example of an image acquired through step S320 of FIG. 3. The portion indicated by the arrow in FIG. 4 corresponds to the sheath region located closest to the wafer. The sheath region is divided into an upper layer portion (part of which ions are mainly present) expressed in white color and a lower layer part (part in which electron particles are mainly present) represented by black color.

In the captured image of FIG. 4, the top pixel layer portion corresponds to y = 1 and the bottom pixel layer portion corresponds to y = 2000. The range of x = 1 to 1000 corresponds to the horizontal direction of the image. That is, the captured image has a size of 1000 (width) x 2000 (length) pixels. In the present embodiment, the upper region of the sheath region of FIG. 4 corresponds to the y = 1500 to 1600 region, and the lower region corresponds to the y = 1600 to 1739 region.

Subsequently, the particle number distribution obtaining unit 120 uses the gray scale values of the pixels constituting the sheath area in the first and second captured images, and according to the gray scale value, to obtain the particle size distribution obtaining unit 120. One particle number distribution and a second particle number distribution are obtained, respectively (S330).

That is, in operation S330, the first particle number distribution according to the gray scale value may be obtained by using the gray scale values of the pixels constituting the sheath region of the first captured image photographed in the vacuum state. Also, the second particle number distribution according to the gray scale value is obtained by using the gray scale values of the pixels constituting the sheath region of the second captured image photographed in the plasma state.

Before describing the particle number distribution of the sheath region in the captured image, the result of analyzing the number of pixels for each gray scale of the entire image will be described. FIG. 5 illustrates an EEDF for the captured image of FIG. 4.

In FIG. 5, the horizontal axis represents a gray scale value and represents an energy state of electrons, which is used to classify states of ion energy into anions and cations. The vertical axis is the number of pixels for each gray scale. The number of pixels here corresponds to the number of particles. In the present embodiment, since the gray scale value of the pixel is used as 8 bits, the gray scale value has a value between 0 and 255. For reference, FIG. 5 shows data of a gray scale range of 1 to 222. FIG.

FIG. 5 illustrates a distribution function of calculating the number of pixels corresponding to each gray scale value in the y = 1 to 1739 range region of the entire image of FIG. 4. As a result, among the pixels constituting the image ranging from y = 1 to 1739, the total number of pixels corresponding to the gray scale value g = 67 is about 10,000 and the total number of pixels corresponding to g = 122 is about 50000.

FIG. 6 is a graph illustrating the number of pixels having a specific gray scale value for each pixel layer of FIG. 4. The horizontal axis of FIG. 6 has a range from 1 to 2000 as the pixel layer unit of FIG. 4, and the vertical axis represents the number of pixels having a value of g = 103 for each pixel layer. That is, FIG. 6 shows a change in the number of particles in the axial direction in the plasma space for particles having a gray scale value g = 103. In the case of the present embodiment is shown a number of particles satisfying a specific gray scale value, but the present invention is not necessarily limited thereto. That is, by applying the same to the particles included in the arbitrary gray scale range, the number of particles corresponding to the arbitrary gray scale range may be expressed for each pixel layer in the image.

In the case of the pixel layer portion in the range of y = 1500 to 1600 in FIG. 6, the number of pixels corresponding to g = 103 decreases sharply. This portion corresponds to the upper layer portion expressed in bright colors in the sheath region of FIG. 4 and is a space in which positive ions are distributed. In addition, in FIG. 6, the pixel layer portion having a range of y = 1600 to 1742 is a space in which negative ions are distributed and correspond to the lower layer portion represented by black color in the sheath region of FIG. 4.

FIG. 7 illustrates the number of pixels for each gray scale in the sheath region of the captured image of FIG. 4. 7 corresponds to the result of the second particle number distribution according to the step S330 corresponds to the IEDF distribution. Each gray scale on the horizontal axis represents a specific energy state, with smaller gray scale values representing higher energy states.

Specifically, the example of FIG. 7 illustrates the number of pixels according to the gray scale value in the sheath region corresponding to the pixel layer y = 1531 to 1742. It can be seen that the total number of pixels having a value of g = 65 in the sheath region in the range of y = 1531 to 1742 is about 9000, and the total number of pixels having a value of g = 121 is about 5000. Where E _{h corresponds} to the high ion energy and E ₁ corresponds to the low ion energy portion. A large number of pixels means a large number of particles, that is, an electron mass. According to E = mc ² , E is proportional to m, so the largest pixel number corresponds to the high ion energy. This high ion energy portion is near the gray scale value g = 65 and corresponds to the vicinity of the lower layer in the sheath region. The low ion energy portion is near g = 121 and corresponds to the vicinity of the upper layer in the sheath region.

8 illustrates a conventional commercialized IEDF function. (A) of FIG. 8 is based on a system combining an I-V probe and a physical model, and (b) is calculated using a mass spectrometer. The IEDF function of FIG. 8 is similar to the result of FIG. 7 according to the present embodiment. However, the result of FIG. 7 does not have a clear presence of a peak corresponding to low energy. In order to correct this, the present embodiment uses the following step S340.

That is, the particle number distribution correcting unit 130 obtains the second particle number distribution corrected by subtracting the first particle number distribution from the second particle number distribution according to the gray scale value obtained in operation S330 (S340). ). This is to ensure that the particle number does not include the laser particles and the negative background energy that reacts with them.

9 and 10 illustrate the step S340 of FIG. 3. FIG. 9 shows the first particle number distribution (graph A) obtained in a vacuum state and the second particle number distribution (graph B; corresponding to FIG. 7) obtained in a plasma state. The particle number was calculated for the particles in the sheath region included in the range Y = 1531 ~ 1742 as the pixel position in the y-axis direction, the space corresponding to the arrow in the image of FIG.

Here, the same principle as in Fig. 7 is obtained as well as graph A. Of course, the embodiment of the present invention is not necessarily limited to monitoring the ion energy distribution from the corrected result of subtracting the first particle number distribution from the second particle number distribution. That is, the second particle number distribution itself can be used for monitoring the ion energy distribution without the above correction.

FIG. 10 shows the result of subtracting graph A (first particle number distribution) from graph B (second particle number distribution) of FIG. 9. After subtraction as shown in FIG. 10, it can be seen that a section in which the number of pixels (number of particles) becomes negative occurs. In FIG. 10, the particle number becomes a positive value from the grayscale value 61, and the particle number distribution that becomes this positive value represents a distribution of actual ion energy due to plasma generation. Accordingly, the particle number distribution correcting unit 130 corrects the graph by adding an offset to the subtracted particle number result so that the negative particle number does not occur in the second particle number distribution in step S340.

FIG. 11 is a diagram illustrating a partial section after adding an offset to FIG. 10. The corrected results show that the two peak points, including the high energy section and the low energy section, are clearly visible, which is very similar to the conventional commercialized IDEF function. The overall appearance of FIG. 11 is more similar to that of FIG. 8B using a mass spectrometer. This embodiment demonstrates its effectiveness because it exhibits similar characteristics to the IEDF provided by the existing measurement system.

The particle number distribution pattern form of FIG. 11 or particle number variation information for each gray scale can be applied to plasma monitoring. That is, based on the result of FIG. 11, the ion distribution monitoring unit 140 may monitor the ion distribution of the sheath region using the corrected second particle number distribution (S350). Here, the ion may have a meaning encompassing a cation and an anion.

The ion distribution monitoring for the sheath region may monitor the ion distribution for the sheath region using a particle number distribution within a gray scale range in which the particle number has a positive value among the second particle number distribution corrected as shown in FIG. 10. Can be.

In operation S350, the distribution of ions in the sheath region may be monitored using the number of particles within an arbitrary gray scale range as illustrated in FIG. 11. Here, the arbitrary gray scale range is T1 ≤ any grail scale ≤ T2. Here, T1 corresponds to 17 to 23% and 55 to 60% of the maximum gray scale value (ex, G _max = 255) for the captured image. 57 and 145 used in FIG. 11 correspond to approximately 22.4% and 56.9% of 255.

In step S350, when the corrected second particle number distribution is greatly out of a preset reference pattern (reference distribution range), or when the particle number value is out of the reference range in a specific gray scale or in a specific gray scale range, a failure in the plasma may be caused. ) Can be judged to have occurred. Here, the reference range of the reference pattern or the number of particles is obtained from the EEDF or IEDF results previously collected for the normal plasma.

The present invention as described above can be easily applied to the measurement of the ion energy distribution in the plasma space other than the sheath. FIG. 12 illustrates energy distribution in an upper space except for the sheath region of FIG. 4. The energy distribution is a distribution obtained by subtracting the first particle number distribution in a vacuum state from the second particle number distribution in a plasma state. In FIG. 12, when the grayscale value is 115, a positive particle number is generated, and a distribution composed of positive particle numbers, that is, an ion energy distribution in which an upper end distribution is changed by plasma generation.

The present invention provides ion energy distribution at any location in the sheath. 13 shows particle distribution in the center of the chamber obtained by applying the equations (1) to (3). The particle number was calculated in the same space as applied in FIG. Of course, the second particle number distribution obtained in the plasma state of FIG. 13 may be used as the ion energy distribution without correction.

FIG. 14 is a distribution obtained by subtracting the first particle number distribution from the second particle number distribution shown in FIG. 13. The result is a positive particle count starting from gray scale 46. The distribution showing a positive particle number represents the actual ion energy distribution of the plasma and can be used as the ion energy distribution without correction. As in the above example, the present invention makes it possible to calculate the energy distribution at any position of the sheath and other regions in the chamber, thus enabling the calculation of the distribution of three-dimensional energy.

According to the exemplary embodiment of the present invention, the distribution of ions in the sheath region may be monitored in real time using gray scale values of pixels constituting the sheath region in the captured image of the particles present in the plasma chamber. Here, since the plasma is mainly composed of electrons and ions, the EEDF which is an electron distribution is obtained in the plasma space excluding the sheath, and the IEDF which is an ion distribution in the sheath region.

The present invention as described above is applicable to various process control such as thin film etching, deposition. First, application examples of the thin film etching process control are as follows.

In general, near the etch endpoint, the ion energy should be reduced to reduce damage to the thin film. While monitoring the distribution of ionic energy using the method according to the present embodiment, it is possible to reduce the damage of the thin film by replacing with a process recipe in which the ionic energy is reduced before reaching the etching end point. Here, a process recipe for reducing damage by plasma may be developed in advance before etching proceeds. In addition to etching damage, etch rate and etch profile can be controlled by controlling the number of particles and energy at specific times. That is, since the three-dimensional ion and electron energy can be monitored for the entire wafer area, it can be applied to control various etching process characteristics (etch rate, etching profile, uniformity between etching rate and etching profile).

Application examples of the thin film deposition process control are as follows. If the number and energy distribution of electrons or ions are different during thin film deposition, thin films of various characteristics can be deposited. In other words, while monitoring the IEDF during thin film deposition, other process recipes developed at specific times can be applied to improve thin film properties. The variation of the ion energy distribution after applying the process recipe can be confirmed through the IEDF or EEDF results according to the present embodiment. It is possible to monitor three-dimensional ions and electron energy for the entire wafer area, and can be applied to control the deposition process characteristics (deposition rate, surface roughness, uniformity between deposition rate and surface roughness).

Flow chart for process control of the thin film is as follows. First, EEDF or IEDF is measured in real time using the method of the present invention as shown in FIG. Before reaching the etching end point, the recipe currently being applied is replaced with a process recipe prepared in advance to improve the thin film properties. After replacement, check the EEDF or IEDF to see if the recipe has been successfully replaced. That is, the IEDF and EEDF collected after the replacement can be applied to determine whether the distribution matches with the previously identified distribution.

Although the present invention has been described with reference to the embodiments shown in the drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims

Receiving a first captured image of the particles in the plasma chamber in a vacuum state;

Receiving a second captured image of particles present in the plasma chamber while a gas is injected into the plasma chamber and power is applied;

Obtaining the first particle number distribution and the second particle number distribution according to the gray scale value, respectively, using the gray scale values of the pixels constituting the respective sheath regions in the first captured image and the second captured image Doing;

Obtaining a corrected second particle number distribution by subtracting the first particle number distribution from a second particle number distribution according to the gray scale value; And

Monitoring ion distribution for the sheath region using the corrected second particle number distribution.
The method according to claim 1,

Acquiring the corrected second particle number distribution,

Ion distribution monitoring method in the plasma sheath adding an offset to the subtracted particle number result.
The method according to claim 1 or 2,

Monitoring the ion distribution for the sheath region,

A method for monitoring ion distribution in a plasma sheath using a number of particles within an arbitrary gray scale range to monitor the distribution of ions in the sheath region.
The method according to claim 3,

The arbitrary gray scale range is ion distribution monitoring method in the plasma sheath defined by the following equation:

T1 ≤ any grail scale range ≤ T2

Here, T1 represents values corresponding to 17 to 23% and 55 to 60% of the maximum gray scale values for the captured image.
The method according to claim 1,

Monitoring the ion distribution for the sheath region,

And monitoring the ion distribution in the sheath region by using the particle number distribution in the gray scale range in which the particle number is positive among the corrected second particle number distribution.
The method according to claim 1,

The first and second captured images,

And a two-dimensional image reconstructed in an arbitrary space including the sheath region in the plasma chamber.
Receiving a captured image of particles present in the plasma chamber while a gas is injected into the plasma chamber and power is applied;

Obtaining a particle number distribution according to the gray scale value by using gray scale values of pixels constituting a sheath region in the captured image; And

Monitoring the ion distribution for the sheath region using the particle number distribution according to the gray scale value.
An image input unit configured to receive a first captured image of particles in the plasma chamber in a vacuum state and a second captured image of particles in the plasma chamber in a state where gas is injected into the plasma chamber and power is applied thereto; ;

Obtaining the first particle number distribution and the second particle number distribution according to the gray scale value, respectively, using the gray scale values of the pixels constituting the respective sheath regions in the first captured image and the second captured image A particle number distribution obtaining unit;

A particle number distribution correction unit for obtaining a second particle number distribution corrected by subtracting the first particle number distribution from a second particle number distribution according to the gray scale value; And

And an ion distribution monitoring unit configured to monitor an ion distribution of the sheath region using the corrected second particle number distribution.
The method according to claim 8,

The particle number distribution correction unit,

And an ion distribution monitoring device in the plasma sheath adding an offset to the subtracted particle number result.
The method according to claim 8 or 9,

The ion distribution monitoring unit,

An ion distribution monitoring device in a plasma sheath for monitoring the distribution of ions in the sheath region using the number of particles within an arbitrary gray scale range.
The method according to claim 10,

The arbitrary gray scale range is ion distribution monitoring device in the plasma sheath defined by the following equation:

T1 ≤ any grail scale ≤ T2

Here, T1 represents values corresponding to 17 to 23% and 55 to 60% of the maximum gray scale values for the captured image.
The method according to claim 8,

The ion distribution monitoring unit,

And an ion distribution monitoring device in the plasma sheath using the particle number distribution within the gray scale range in which the particle number has a positive value among the corrected second particle number distribution.
The method according to claim 8,

The first and second captured images,

And an ion distribution monitoring device in the plasma sheath which is a two-dimensional image reconstructed in an arbitrary space including the sheath region in the plasma chamber.
An image input unit configured to receive a captured image of particles present in the plasma chamber while a gas is injected into the plasma chamber and power is applied;

A particle number distribution obtaining unit obtaining a particle number distribution according to the gray scale value by using gray scale values of pixels constituting a sheath region in the captured image; And

And an ion distribution monitor configured to monitor ion distribution in the sheath region by using the particle number distribution according to the gray scale value.