Apparatus and method for measuring plasma density

Abstract

The present disclosure relates to an apparatus for measuring plasma density and a method for measuring plasma density, the apparatus comprising: a chamber having a processing space inside; a plasma generation unit for generating plasma in the processing space; an upper plate disposed at an upper portion of the chamber and having a plurality of through holes; and a measurement unit including a measurement cable penetrating the upper plate, and measuring the plasma density at each position in the processing space based on a transmission coefficient measured using the measurement cable.

Description

Cross - reference to Related Applications

[0001] This application claims priority to Korean Patent Application No. 10 - 2023 - 0195978, filed with the Korean Intellectual Property Office on December 29, 2023, the entire disclosure of which is incorporated herein by reference. Technical Field

[0002] The present disclosure relates to an apparatus for measuring plasma density and a method for measuring plasma density. Background Art

[0003] Plasma is a gas state separated into ions, free radicals, electrons, etc. at high temperatures. Plasma is generated by extremely high temperatures, strong electric fields, or high - frequency electromagnetic fields (RF electromagnetic fields).

[0004] The process for manufacturing semiconductor devices may include a process of etching the surface of a substrate to form a desired pattern on the substrate. The etching process may be performed by the collision or reaction of ions or free radicals included in the plasma with a thin film formed on the substrate.

[0005] To control the processing process of a substrate using plasma, it is necessary to detect distribution information of the plasma in the chamber. As a method for observing the plasma in the chamber, there is provided a method of indirectly observing the plasma through the spectrum emitted from the plasma using an optical emission spectroscopy (OES) sensor, and a method of directly inserting a probe into the space where the plasma is formed.

[0006] The method of indirectly observing the plasma through the spectrum may have a problem of reduced accuracy of the observed value, while the method of indirectly inserting the probe may have a problem of interference with the plasma. Summary of the Invention

[0007] One aspect of the present disclosure provides an apparatus for measuring plasma density and a method for measuring plasma density, which can monitor plasma density information at each position in the processing space.

[0008] One aspect of the present disclosure provides an apparatus for measuring plasma density and a method for measuring plasma density, which can use a measurement cable that penetrates the upper plate and has a planar probe (not protruding into the processing space) to measure the transmission coefficient, and deduce the density value of the plasma based on the transmission coefficient.

[0009] One aspect of the present disclosure provides an apparatus for measuring plasma density and a method for measuring plasma density, which can observe plasma density information at each position in the processing space by switching.

[0010] According to one aspect of the present disclosure, there is provided an apparatus for measuring plasma density and a method for measuring plasma density.

[0011] According to one aspect of the present disclosure, there is provided an apparatus for measuring plasma density, the apparatus including: a chamber having a processing space therein; a plasma generation unit configured to generate plasma in the processing space; an upper plate disposed on an upper portion of the chamber and having a plurality of through holes; and a measurement unit including a measurement cable penetrating the upper plate and configured to measure the plasma density at each position in the processing space based on a transmission coefficient measured using the measurement cable.

[0012] According to one aspect of the present disclosure, there is provided a method for measuring plasma density, the method including: generating plasma in a processing space inside a chamber; measuring a transmission coefficient using a measurement cable that penetrates an upper plate disposed in an upper portion of the chamber; and measuring the plasma density at each position in the processing space based on the transmission coefficient.

[0013] According to one aspect of the present disclosure, there is provided an apparatus for measuring plasma density, the apparatus including: a chamber having a processing space therein; an upper plate disposed on an upper portion of the chamber and having a plurality of through holes; a plasma generation unit configured to supply a processing gas to the processing space and generate plasma from the processing gas in an upper portion of the upper plate; a substrate support unit disposed in a lower portion of the upper plate and configured to support a substrate; a signal generator configured to generate a measurement signal; a signal analyzer configured to analyze a collected signal; and a measurement unit including a measurement cable penetrating the upper plate and configured to measure the plasma density at each position in the processing space based on a transmission coefficient measured using the measurement cable, wherein the measurement cable includes: a signal application cable connected to the signal generator and configured to apply the measurement signal generated from the signal generator to a lower portion of the upper plate; and a signal collection cable connected to the signal analyzer and configured to transmit the collected signal collected from the lower portion of the upper plate to the signal analyzer. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The above and other aspects, features, and advantages of the present disclosure will be more clearly understood from the following detailed description in conjunction with the accompanying drawings, in which:

[0015] Figure 1 An apparatus for measuring plasma density according to an embodiment of the present disclosure is shown;

[0016] Figure 2 A partial configuration of an apparatus for measuring plasma density according to an embodiment of the present disclosure is shown;

[0017] Figure 3Shows a partial configuration of an apparatus for measuring plasma density according to an embodiment of the present disclosure;

[0018] Figure 4 is a graph exemplarily showing a transmission coefficient measured by a method for measuring plasma density according to an embodiment of the present disclosure; and

[0019] Figure 5 is a flowchart of a method for measuring plasma density according to an embodiment of the present disclosure. Detailed Description of Embodiments

[0020] Hereinafter, embodiments will be described in detail so that those skilled in the art can easily practice the present disclosure with reference to the accompanying drawings. However, when determining that a detailed description of related known functions or configurations may unnecessarily obscure the gist of the present disclosure during the detailed description of the embodiments, the detailed description will be omitted. Additionally, throughout the drawings, the same reference numerals are used for components having similar functions and operations. Also, in this specification, terms such as "upper", "upper part", "upper surface", "lower", "lower part", "lower surface", "side surface", etc. are based on the drawings and may change according to the actual setting direction of the components.

[0021] Furthermore, throughout the specification, when a component is referred to as being "connected" to another component, it includes not only "directly connected" but also "indirectly connected" with other components existing therebetween. In addition, "including" a certain component means that other components may also be included, unless otherwise specified, rather than excluding other components.

[0022] Figure 1 Shows an apparatus for measuring plasma density according to an embodiment of the present disclosure. Referring to Figure 1 , the apparatus 100 for measuring plasma density may include a chamber 110, a substrate support unit 120, a plasma generation unit 130, an upper plate 140, and a measurement unit 150.

[0023] The apparatus 100 for measuring plasma density may include a part or all of an apparatus for processing a substrate, and the apparatus uses plasma to perform processing on the substrate W. The processing of the substrate W may include, for example, an etching process.

[0024] The interior of the chamber may form a processing space 111. The processing space 111 may be an environment that can be controlled to have an appropriate temperature and pressure to perform processing on the substrate W.

[0025] The substrate support unit 120 may be disposed inside the chamber 110. The substrate support unit 120 may include a substrate support surface that supports the substrate W and adsorbs and fixes the substrate W.

[0026] The substrate support unit 120 can receive a DC voltage and adsorb the substrate W by electrostatic force. Additionally, the substrate support unit 120 can be controlled to have a preset temperature, thereby controlling the processing of the substrate W.

[0027] The plasma generation unit 130 can generate plasma in the processing space 111. The plasma generation unit 130 can include a voltage application unit 131, a gas supply unit 132, and a gas inlet unit 133.

[0028] The voltage application unit 131 can generate a high-frequency voltage for generating plasma. The high-frequency voltage generated by the voltage application unit 131 can be applied to an electrode provided in the upper part of the chamber 110.

[0029] The gas supply unit 132 can supply a processing gas to the processing space 111 through the gas inlet unit 133. When a high-frequency voltage is applied by the voltage application unit 131, plasma can be generated from the processing gas supplied to the processing space 111.

[0030] The upper plate 140 can be disposed above the chamber 110 and on the upper part of the substrate support unit 120. The upper plate 140 can have a plurality of through holes 141 formed to penetrate the upper plate 140 in the vertical direction.

[0031] The upper plate 140 can include a showerhead that provides plasma radicals, or one or more gases, to the substrate W disposed below it through the plurality of through holes 141.

[0032] The measurement unit 150 can measure the plasma density at each position in the processing space 111. The measurement unit 150 can include a measurement cable disposed inside the upper plate 140.

[0033] The measurement unit 150 can include a plurality of measurement cables. The plurality of measurement cables can be disposed at different positions on the upper plate 140. The measurement cables can penetrate the upper plate 140. The measurement unit 150 can use the measurement cables to measure the transmission coefficient.

[0034] Figure 2 The lower surface 140a of the upper plate 140 in the apparatus 100 for measuring plasma density according to an embodiment of the present disclosure is shown.

[0035] The measurement cable can include a signal application cable 151 and a signal collection cable 152. A signal application tip 151a can be formed below the signal application cable 151, and a signal collection tip 152a can be formed below the signal collection cable 152.

[0036] In the upper plate 140, the signal application cable 151 and the signal collection cable 152 can be disposed adjacent to each other. Thus, as Figure 2As shown, the signal application tip 151a and the signal collection tip 152a can be disposed adjacent to each other on the lower surface 140a of the upper plate 140.

[0037] The measuring unit 150 may further include a signal generator 153 for generating a measurement signal, and a signal analyzer 154 for analyzing the collected signal.

[0038] The measurement signal generated from the signal generator 153 may be applied to the lower part of the upper plate 140 by the signal application cable 151.

[0039] In addition, the signal collection cable 152 may transmit the collected signal collected from the lower part of the upper plate 140 to the signal analyzer 154. The collected signal collected by the signal collection cable 152 may be a signal obtained after the signal applied by the signal application cable 151 passes through the plasma in the processing space 111.

[0040] The lower cross-section of the signal application tip 151a may be located in the same plane as the lower surface 140a of the upper plate 140, and the lower cross-section of the signal collection tip 152a may be located in the same plane as the lower surface 140a of the upper plate 140.

[0041] In the present disclosure, by using a planar probe as a device for measuring the plasma density in the processing space 111, the space occupied by the probe in the device can be optimized, and the influence on the environment or process inside the chamber 110 can be minimized.

[0042] A measurement signal of variable frequency may be applied to the plasma in the processing space 111 through the signal application cable 151.

[0043] The measuring unit 150 may include a plurality of measurement cables disposed at different positions on the upper plate 140. The measuring unit 150 may further include a switching member 155 for switching between the plurality of measurement cables.

[0044] Figure 3 A part of the side cross-section of the upper plate 140 is shown. For example, the plurality of measurement cables may include a first measurement cable and a second measurement cable.

[0045] The first measurement cable may include a first signal application cable 151-1 and a first signal collection cable 152-1. In addition, the second measurement cable may include a second signal application cable 151-2 and a second signal collection cable 152-2.

[0046] As Figure 3 shown, the first signal application cable 151-1, the first signal collection cable 152-1, the second signal application cable 151-2, and the second signal collection cable 152-2 may be arranged to penetrate the upper plate 140.

[0047] The first signal application tip 151-1a may be formed at the lower part of the first signal application cable 151-1, and the first signal collection tip 152-1a may be formed at the lower part of the first signal collection cable 152-1.

[0048] The lower cross-section of the first signal application tip 151-1a may be located in the same plane as the lower surface 140a of the upper plate 140, and the lower cross-section of the first signal collection tip 152-1a may be located in the same plane as the lower surface 140a of the upper plate 140.

[0049] The second signal application tip 151-2a may be formed at the lower part of the second signal application cable 151-2, and the second signal collection tip 152-2a may be formed at the lower part of the second signal collection cable 152-2.

[0050] The lower cross-section of the second signal application tip 151-2a may be located in the same plane as the lower surface 140a of the upper plate 140, and the lower cross-section of the second signal collection tip 152-2a may be located in the same plane as the lower surface 140a of the upper plate 140.

[0051] In addition, the switching member 155 may include an application switching member 155A and a collection switching member 155B.

[0052] The application switching member 155A may connect the signal generator 153 to any one of the first signal application cable 151-1 or the second signal application cable 151-2.

[0053] The collection switching member 155B may connect the signal analyzer 154 to any one of the first signal collection cable 152-1 or the second signal collection cable 152-2.

[0054] When the signal generator 153 is connected to the first signal application cable 151-1 through the application switching member 155A, the measuring unit 150 may connect the signal analyzer 154 to the first signal collection cable 152-1 through the collection switching member 155B.

[0055] In addition, when the signal generator 153 is connected to the second signal application cable 151-2 through the application switching member 155A, the measuring unit 150 may connect the signal analyzer 154 to the second signal collection cable 152-2 through the collection switching member 155B.

[0056] That is, the measuring unit 150 may control the application switching member 155A and the collection switching member 155B to operate the signal application cable and the signal collection cable that are disposed adjacent to each other and correspond to each other on the upper plate 140.

[0057] The measuring unit 150 can scan the frequency of the measurement signal. Specifically, the signal generator 153 can change the frequency of the measurement signal in a gradually increasing or gradually decreasing direction.

[0058] The signal analyzer 154 can receive the collected signal obtained after the measurement signal at a variable frequency passes through the plasma in the processing space 111 via the signal collection cable 152.

[0059] The signal analyzer 154 can derive the transmission coefficient based on the wave of the collected signal and derive the resonance frequency of the plasma based on the transmission coefficient.

[0060] The transmission coefficient according to the frequency of the collected signal can be derived by Equation 1.

[0061] [Equation 1]

[0062]

[0063] In addition, the resonance frequency of the plasma can be derived at the point where Z total is maximum, as shown in Equation 2. In Equation 2, j represents the imaginary unit in complex number representation, ω represents the frequency, C s represents the sheath capacitance, C0 represents the plasma capacitance, R p represents the plasma resistance, and L p represents the plasma inductance.

[0064] [Equation 2]

[0065]

[0066] Figure 4 is a graph exemplarily showing the transmission coefficient measured by the method for measuring plasma density according to an embodiment of the present disclosure. Figure 4 shows a graph of the transmission coefficient (S 21 ) varying with frequency, which shows the electromagnetic wave transmission characteristics of the plasma.

[0067] Based on Figure 4 the value of the transmission coefficient (S 21 ) shown in the graph of, the resonance frequency (F total ) of the plasma can be derived at the point where Z p is maximum.

[0068] The resonance frequency (F p ) of the plasma can quantitatively represent the plasma density. The signal analyzer 154 can derive the plasma density based on the resonance frequency of the plasma. For example, when the resonance frequency of the plasma is F p the plasma density D can be derived by Equation 3p 。

[0069] [Equation 3]

[0070] [1 / cm 3

[0071] In the present disclosure, a plurality of cables disposed at different positions on the upper plate 140 can be used to measure the transmission coefficient, and thereby, plasma density information at each position in the processing space 111 can be derived, and information related to the temporal change of the plasma density gradient can be obtained by repeating the measurement.

[0072] Figure 5 is a flowchart of a method for measuring plasma density according to an embodiment of the present disclosure. The method 500 for measuring plasma density can be performed in whole or in part by the apparatus 100 for measuring plasma density described by Figures 1 to 4 described.

[0073] Refer to Figure 5 , the method 500 for measuring plasma density may include: generating plasma in a processing space inside a chamber (S510), measuring the transmission coefficient using a measurement cable (S520), the measurement cable penetrating an upper plate provided in an upper portion of the chamber, and measuring the plasma density at each position in the processing space based on the transmission coefficient (S530).

[0074] When measuring the transmission coefficient (S520), the measurement cable may include a signal application cable and a signal collection cable that penetrate the upper plate. The signal application cable and the signal collection cable may be disposed adjacent to each other on the upper plate.

[0075] In addition, a signal application tip may be formed at a lower portion of the signal application cable, and a signal collection tip may be formed at a lower portion of the signal collection cable. A lower cross-section of the signal application tip may be located in the same plane as a lower surface of the upper plate, and a lower cross-section of the signal collection tip may be located in the same plane as a lower surface of the upper plate.

[0076] In the present disclosure, by using a planar probe that does not protrude into the processing space inside the chamber to measure the plasma density, the space occupied by the probe in the apparatus can be minimized, and the influence on the environment and process inside the chamber can be minimized.

[0077] Measuring the transmission coefficient (S520) may include: applying a signal to a lower portion of the upper plate through the signal application cable and collecting the signal from the lower portion of the upper plate through the signal collection cable.

[0078] ​The applied signal may include: generating a signal by a signal generator connected to a signal application cable and inputting the signal into the signal application cable. The signal generator may change the frequency of the signal in a direction of gradually increasing or gradually decreasing the frequency of the signal.

[0079] The collected signal may include: detecting a signal with a signal collection cable and transmitting the detected signal to a signal analyzer connected to the signal collection cable.

[0080] Measuring the transmission coefficient (S520) may derive the transmission coefficient based on the wave of the signal transmitted to the signal analyzer.

[0081] Measuring the plasma density at each position in the processing space (S530) may include: deriving the resonance frequency of the plasma based on the transmission coefficient and deriving the plasma density based on the resonance frequency of the plasma.

[0082] The measurement cable for measuring the transmission coefficient may include a plurality of measurement cables located at different positions on the upper plate.

[0083] The method (500) for measuring the plasma density may further include: switching between the plurality of measurement cables.

[0084] Switching between the plurality of measurement cables may include: switching the applied signal and switching the collected signal.

[0085] For example, the plurality of measurement cables may include a first measurement cable and a second measurement cable. The first measurement cable may include a first signal application cable and a first signal collection cable arranged adjacent to each other, and the second measurement cable may include a second signal application cable and a second signal collection cable arranged adjacent to each other.

[0086] When switching the applied signal, the signal generator may be connected to the first signal application cable, and when switching the collected signal, the signal analyzer may be connected to the first signal collection cable.

[0087] In addition, when switching the applied signal, the signal generator may be connected to the second signal application cable, and when switching the collected signal, the signal analyzer may be connected to the second signal collection cable.

[0088] That is to say, in the method for measuring the plasma density, the signal application cable and the signal collection cable arranged adjacent to each other and corresponding to each other may be switched for operation.

[0089] In addition, when describing the present disclosure, a “section” or “unit” may be implemented in various ways (e.g., by a processor, program instructions executed by the processor, software modules, microcode, computer program products, logic circuits, application specific integrated circuits, firmware, etc.).

[0090] The method content disclosed in the embodiments of the present application can be directly implemented by a hardware processor, or can be implemented and completed by a combination of hardware and software modules among processors. The software modules can be stored in a storage medium of the prior art (for example, random access memory, flash memory, read-only memory, programmable read-only memory, or electrically erasable programmable memory, registers, etc.). The storage medium is located in the memory, and the processor reads the information stored in the memory and combines it with the hardware to complete the content of the above method. To avoid redundancy, detailed descriptions are omitted herein.

[0091] In the process of implementation, each content of the above method can be completed by the logic integrated circuit of the hardware in the processor or instructions in the form of software.

[0092] That is to say, those skilled in the art know that it can be implemented by combining each example unit and algorithm operation described in the embodiments disclosed in this specification, either by electronic hardware or by a combination of computer software and electronic hardware. Whether these functions are executed by hardware or software is determined by the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for corresponding specific applications, but such implementation should not be considered to exceed the scope of the present application.

[0093] In several embodiments provided by the present application, it should be understood that the disclosed devices and methods can also be implemented in other ways. For example, the above device embodiments are merely exemplary, and for example, the division of units is only a logical function division, and other division methods can also be provided in actual implementation. For example, multiple units or components can be coupled or integrated into another system, or some features can be ignored or not executed. On the other hand, the shown or discussed coupling or direct coupling or mutual communication connection can be an indirect coupling or communication connection through some interface, device or unit, and can be electrical, mechanical or other types.

[0094] The units described as separate components above can be physically separated, and the components indicated as units can be or can not be physical units. For example, they can be located in one place, or can be distributed among multiple network units. According to actual needs, some or all of them can be selected to achieve the purpose of the solution of this embodiment.

[0095] That is to say, each functional unit in each embodiment of the present application can be integrated into a processing unit, each unit can exist alone, or two or more units can be integrated into one unit.

[0096] If a function is implemented in the form of a software functional unit and sold or used as an independent product, the function can be stored in a single computer-readable storage medium. Based on this understanding, the technical solution of this application that makes a substantial contribution to the prior art, or a part of this technical solution, can be implemented in the form of a software product, and this computer software product is stored in a single storage medium. Therefore, a computer device (which can be a personal computer, a server, a network device, etc.) including some instructions can perform all or part of the operations of the methods described in each embodiment of this application. Examples of the above storage medium include various media capable of storing program codes (for example, USB memory, removable hard disk, read-only memory (ROM), random access memory (RAM), magnetic disk or CD-ROM, etc.).

[0097] As described above, according to the present disclosure, a device for measuring plasma density and a method for measuring plasma density can be provided, which can monitor plasma density information at each position in a processing space.

[0098] In an embodiment of the present disclosure, a device for measuring plasma density and a method for measuring plasma density can be provided, which can measure a transmission coefficient using a measurement cable that penetrates an upper plate and has a planar probe (not protruding into the processing space), and derive a plasma density value based on the transmission coefficient.

[0099] In an embodiment of the present disclosure, a device for measuring plasma density and a method for measuring plasma density can be provided, which can observe plasma density information at each position in a processing space by switching.

[0100] Although the example embodiments have been shown and described above, it will be apparent to those skilled in the art that modifications and changes can be made without departing from the scope of the present disclosure defined by the appended claims.

Claims

1. A device for measuring plasma density, comprising: a chamber having a processing space therein; a plasma generating unit for generating plasma in the processing space; an upper plate, disposed at the upper portion of the chamber and having a plurality of through holes; as well as A measuring unit includes a measuring cable penetrating the upper plate and measures a plasma density at each position in the processing space based on a transmission coefficient measured using the measuring cable.

2. The device for measuring plasma density according to claim 1, wherein: The measuring cable includes a signal applying cable and a signal collecting cable which are disposed adjacent to each other on the upper plate.

3. The device for measuring plasma density according to claim 2, wherein: The measuring unit further comprises a signal generator for generating a measuring signal and a signal analyzer for analyzing the collected signal. The signal applying cable applies the measurement signal generated from the signal generator to the lower portion of the upper plate, and The signal collecting cable transmits the collected signal collected from the lower portion of the upper plate to the signal analyzer.

4. The device for measuring plasma density according to claim 3, wherein: The signal applying cable includes a signal applying tip formed thereunder, The signal collecting cable includes a signal collecting tip formed thereunder, The lower cross section of the signal applying tip is located on the same plane as the lower surface of the upper plate, A lower cross-section of the signal collecting tip is located on the same plane as the lower surface of the upper plate.

5. The device for measuring plasma density according to claim 4, wherein: The signal generator changes the frequency of the measurement signal in a gradually increasing or decreasing direction, The signal analyzer derives a transmission coefficient based on the wave of the collected signal, derives a resonant frequency of the plasma based on the transmission coefficient, and derives the plasma density based on the resonant frequency of the plasma.

6. The device for measuring plasma density according to claim 3, wherein: The measuring cables include a plurality of measuring cables arranged at different positions of the upper plate, The measuring unit further includes a switching member for switching between the plurality of measuring cables.

7. The device for measuring plasma density according to claim 6, wherein: The measuring unit changes a measurement position of the transmission coefficient using the switching member, and measures a plasma density at each position in the processing space.

8. The device for measuring plasma density according to claim 6, wherein: The plurality of measuring cables include: A first measurement cable, comprising a first signal applying cable and a first signal collecting cable; and The second measuring cable comprises a second signal applying cable and a second signal collecting cable, Wherein, the switching component comprises: applying a switching member to connect the signal generator to any one of the first signal applying cable or the second signal applying cable; and A collection switching component connects the signal analyzer to any one of the first signal collection cable or the second signal collection cable.

9. The device for measuring plasma density according to claim 8, wherein: When the signal generator is connected to the first signal applying cable through the applying switching member, the measuring unit connects the signal analyzer to the first signal collecting cable through the collecting switching member, and When the signal generator is connected to the second signal applying cable through the applying switching member, the measuring unit connects the signal analyzer to the second signal collecting cable through the collecting switching member.

10. A method for measuring plasma density, comprising: generating a plasma in a processing space within the chamber; measuring the transmission coefficient using a measuring cable penetrating an upper plate disposed in an upper portion of the chamber; as well as A plasma density at each location in the processing space is measured based on the transmission coefficient.

11. The method for measuring plasma density according to claim 10, wherein: The measuring cable comprises: a signal applying cable penetrating the upper plate; and a signal collecting cable, penetrating the upper plate and disposed adjacent to the signal applying cable on the upper plate, Wherein, measuring the transmission coefficient comprises: applying a signal to a lower portion of the upper board through the signal applying cable; and The signals are collected from the lower portion of the upper board through the signal collecting cable.

12. The method for measuring plasma density according to claim 11, wherein: Applying the signal comprises: generating the signal by a signal generator connected to the signal applying cable; and The signal is input to the signal applying cable.

13. The method for measuring plasma density according to claim 12, wherein: Collecting the signal includes: Detecting the signal with the signal collection cable; and The detected signal is transmitted to a signal analyzer connected to the signal collecting cable.

14. The method for measuring plasma density according to claim 13, wherein: The signal applying cable includes a signal applying tip formed thereunder, The signal collecting cable includes a signal collecting tip formed thereunder, The lower cross section of the signal applying tip is located on the same plane as the lower surface of the upper plate, A lower cross-section of the signal collecting tip is located on the same plane as the lower surface of the upper plate.

15. The method for measuring plasma density according to claim 13, wherein: Generating the signal comprises: changing the frequency of the signal in a gradually increasing or decreasing direction, Wherein, measuring the transmission coefficient comprises: The transmission coefficient is derived based on the wave of the signal transmitted to the signal analyzer.

16. The method for measuring plasma density according to claim 15, wherein: Measuring the plasma density comprises: deriving a resonant frequency of the plasma based on the transmission coefficient; and The plasma density is derived based on the resonant frequency of the plasma.

17. The method for measuring plasma density according to claim 16, wherein: The measuring cables include a plurality of measuring cables arranged at different positions of the upper plate, The method further comprises: Switching is performed between the plurality of measurement cables.

18. The method for measuring plasma density according to claim 17, wherein: Switching between the plurality of measurement cables comprises: switching the applied signal; and Toggle collection signal.

19. The method for measuring plasma density according to claim 18, wherein: The plurality of measuring cables include: a first signal applying cable; a first signal collecting cable, disposed adjacent to the first signal applying cable; a second signal applying cable; a second signal collecting cable, arranged adjacent to the second signal applying cable, wherein, when the signal generator is connected to the first signal applying cable when the applying signal is switched, the signal analyzer is connected to the first signal collecting cable when the collecting signal is switched, and When the signal generator is connected to the second signal applying cable when the applying signal is switched, the signal analyzer is connected to the second signal collecting cable when the collecting signal is switched.

20. A device for measuring plasma density, comprising: a chamber having a processing space therein; an upper plate, disposed at the upper portion of the chamber and having a plurality of through holes; a plasma generating unit that supplies a process gas to the process space and generates plasma from the process gas in an upper portion of the upper plate; a substrate supporting unit disposed in a lower portion of the upper plate and supporting a substrate; a measuring unit including a signal generator for generating a measurement signal, a signal analyzer for analyzing the collected signal, and a measurement cable penetrating the upper plate, and measuring a plasma density at each position of the processing space based on a transmission coefficient measured using the measurement cable, wherein the measuring cable comprises: a signal applying cable connected to the signal generator and applying the measuring signal generated from the signal generator to the lower portion of the upper plate; and A signal collecting cable is connected to the signal analyzer and transmits the collected signal collected from the lower portion of the upper plate to the signal analyzer.

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