Patent ID: 12243727

DETAILED DESCRIPTION OF THE INVENTION

The terminology employed in the present specification and accompanying drawings are provided for the convenience of explanation, but the inventive concept is not limited thereto. In describing the present disclosure, a detailed description of known functions and configurations will be omitted when it may obscure the subject matter of the present disclosure. The embodiments set forth in the following description are provided to allow those skilled in the art to apparent understand the inventive concept and thus the inventive concept is not limited to the embodiments set forth in the following description. The modifications and the variations of the inventive concept are possible within the scope of the inventive concept.

In an embodiment of the present disclosure, a substrate processing apparatus etching a substrate by using plasma, the apparatus having an Inductively Coupled Plasma (ICP) source, will be described. However, the present disclosure is not limited thereto. Further, the present disclosure is applicable to various types of apparatuses, such as a substrate processing apparatus having a Capacitively Coupled Plasma (CCP) source, performing a process for a substrate and having a lift pin.

In addition, in an embodiment of the present disclosure, an electrostatic chuck will be described as an example of a substrate supporting unit. However, the present disclosure is not limited thereto. Further, when the electrostatic chuck is not necessarily required, the substrate supporting unit may support a substrate by mechanical clamping or by using vacuum.

FIG.1is a cross-sectional view illustrating a substrate processing apparatus according to an embodiment of the present disclosure.

Referring toFIG.1, a substrate processing apparatus10processes a substrate W by using plasma. For example, the substrate processing apparatus10may perform an etching process on the substrate W. The substrate processing apparatus10may include a chamber100, a substrate supporting unit200, a gas supply unit300, and a plasma source unit400.

The chamber100provides a space in which a plasma processing is performed, and the substrate supporting unit200supports the substrate W inside the chamber100. The gas supply unit300supplies process gas into the chamber100and the plasma source unit400provides electromagnetic waves into the chamber100to generate plasma from the process gas. Hereinafter, each configuration will be described in detail.

The chamber100includes a chamber body110and a cover120. The chamber body110has an open upper surface, and a space is formed inside the chamber body110. An exhaust hole113is formed in a bottom wall of the chamber body110. The exhaust hole113is connected to an exhaust line117, and provides a passage for discharging gas remaining inside the chamber body110and for discharging reaction by-products that are produced during a process procedure, to the outside. A plurality of exhaust holes113may be formed in edge regions of the bottom wall of the chamber body110.

The cover120seals the open upper surface of the chamber body110. The cover120has a radius corresponding to a circumference of the chamber body110. The cover120may be formed of a dielectric material. The cover120may be formed of an aluminum material. A space surrounded by the cover120and the chamber body110is provided as a processing space130in which the plasma processing process is performed.

A baffle250controls a flow of the process gas inside the chamber100. The baffle250is provided in a ring shape, and is interposed between the chamber100and the substrate supporting unit200. Distribution holes251are formed in the baffle250. The process gas remaining in the chamber100is introduced into the exhaust holes113through the distribution holes251. The flow of the process gas introduced into the exhaust holes113may be controlled according to a shape and an arrangement of the distribution holes251.

The gas supply unit300supplies the process gas into the chamber100. The gas supply unit300includes a nozzle310, a gas storage portion320, and a gas supply line330.

The nozzle310is mounted at the cover120. The nozzle310may be positioned at a center region of the cover120. The nozzle310is connected to the gas storage portion320through the gas supply line330. A valve340is mounted at the gas supply line330. The valve340opens and closes the gas supply line330, and adjusts the supply flow rate of the process gas. The process gas stored in the gas storage portion320is supplied to the nozzle310through the gas supply line330, and is sprayed into the chamber100from the nozzle310. The nozzle310mainly supplies the process gas to a central region of the processing space130. In an embodiment, the gas supply unit300may further include another nozzle (not illustrated) mounted on a sidewall of the chamber body110. Another nozzle supplies the process gas to an edge region of the processing space130.

The plasma source unit400produces plasma from the process gas. The plasma source unit400includes an antenna410, a power supply420, and an upper cover430.

The antenna410is provided at an upper portion of the chamber100. The antenna410may be provided in the form of a spiral coil. The power supply420is connected to the antenna410through a cable, and applies high-frequency power to the antenna410. As the high-frequency power is applied to the antenna410, electromagnetic waves are generated from the antenna410. The electromagnetic waves form an induced electric field inside the chamber100. The process gas is changed to plasma by obtaining energy required for ionization from the induced electric field. The plasma may be applied to the substrate W and an etching process may be performed.

The substrate supporting unit200is positioned in the processing space130, and supports the substrate W. The substrate supporting unit200may fix the substrate W by using an electrostatic force or may support the substrate W in a mechanical clamping manner. Hereinafter, an example in which the substrate supporting unit200is an electrostatic chuck that fixes the substrate W by using the electrostatic force will be described.

The electrostatic chuck200includes a chuck member210, a housing230, and a lift pin240.

The chuck member210holds the substrate W by using the electrostatic force. The chuck member210may include a dielectric plate211, an electrode212, a heater213, a focus ring214, an insulating plate215, and a grounding plate216.

The dielectric plate211is provided in a circular plate shape. An upper surface of the dielectric plate211may have a radius corresponding to or smaller than a radius of the substrate W. Protrusion portions211amay be formed on the upper surface of the dielectric plate211. The substrate W is placed on the protrusion portions211aand is spaced apart from the dielectric plate211by a predetermined distance. A side surface of the dielectric plate211may be stepped such that a lower region of the dielectric plate211has a radius larger than a radius of an upper region of the dielectric plate211. For example, the dielectric plate211may be formed of Al2O3.

The electrode212is buried inside the dielectric plate211. The electrode212is a circular plate having a thinner thickness and is formed of a conductive material. Further, the electrode212is connected to an external power source (not illustrated) through a first cable221. A power applied from the external power source generates the electrostatic force between the electrode212and the substrate W, and fixes the substrate W on the upper surface of the dielectric plate211. The external power source may be a DC power source.

The heater213is provided inside the dielectric plate211. The heater213may be provided under the electrode212. The heater213is connected to the external power source (not illustrated) through a second cable222. The heater213generates heat by resisting against a current applied thereto from the external power source. The generated heat is transferred to the substrate W through the dielectric plate211, and heats the substrate W to a predetermined temperature. The heater213is provided in the form of a spiral coil. Further, the heater213may be buried inside the dielectric plate211at a uniform distance.

The focus ring214is provided in a ring shape and is disposed along a circumference of the upper region of the dielectric plate211. An upper surface of the focus ring214may be stepped such that an inner portion of the upper surface of the focus ring214adjacent to the dielectric plate211is lower than an outer portion of the upper surface of the focus ring214. The inner portion of the upper surface of the focus ring214may be positioned such that a height of the inner portion of the upper surface of the focus ring214is equal to a height of the upper surface of the dielectric plate211. The focus ring214expands a region where the electromagnetic field is formed such that the substrate W is positioned at the center of a region where the plasma is formed. Accordingly, the plasma may be uniformly formed throughout the whole region of the substrate W.

The insulating plate215is positioned under the dielectric plate211, and supports the dielectric plate211. The insulating plate215is a circular plate having a predetermined thickness, and may have a radius corresponding to the radius of the dielectric plate211. The insulating plate215is formed of an insulating material. The insulating plate215is connected to the external power source (not illustrated) through a third cable223. The high-frequency current applied to the insulating plate215through the third cable223forms the electromagnetic field between the electrostatic chuck200and the cover120. The electromagnetic field is provided as an energy to generate the plasma.

A cooling flow passage211bmay be formed in the insulating plate215. The cooling flow passage211bis positioned under the heater213. The cooling flow passage211bprovides a passage through which a cooling fluid circulates. The heat of the cooling fluid is transferred to the dielectric plate211and the substrate W, and the dielectric plate211and the substrate W that are heated are rapidly cooled. The cooling flow passage211bmay be formed in a spiral shape. In an embodiment, the cooling flow passage211bmay be provided such that passages which are famed in a ring shape and which respectively have a radius different from each other have an equal center. Each of the passages may communicate with each other. In an embodiment, the cooling flow passage211bmay be formed in the grounding plate216.

The grounding plate216is positioned under the insulating plate215. The grounding plate216is a circular plate having a predetermined thickness, and may have a radius corresponding to the radius of the insulating plate215. The grounding plate216is grounded. The grounding plate216electrically insulates the insulating plate215from the chamber body110.

A pin hole220is formed in the chuck member210. The pin hole220is formed in an upper surface of the chuck member210. In addition, the pin hole220may be vertically formed through the chuck member210. The pin hole220is provided from the upper surface of the dielectric plate211toward a lower surface of the grounding plate216by sequentially passing through the dielectric plate211, the insulating plate215, and the grounding plate216.

A plurality of pin holes220may be formed. The plurality of pin holes220may be arranged in a circumferential direction of the dielectric plate211. For example, three pin holes220may be arranged in the circumferential direction of the dielectric plate211while being spaced apart from each other at120degrees. In addition, four pin holes220may be arranged in the circumferential direction of the dielectric plate211while being spaced apart from each other at 90 degrees. Further, various numbers of pin holes220may be formed.

In addition, the pin hole220may be formed in the protrusion portion211aof the dielectric plate211. For example, the pin hole220having a circular shape may be formed at the center of the protrusion portion211ahaving a circular planar shape. However, the protrusion portion211aand the pin hole220may be variously provided when viewed from the plane view. The pin hole220may be formed in a portion of the protrusion portion211a.For example, six protrusion portions211amay be arranged in the circumferential direction of the dielectric plate211while being spaced apart from each other at 60 degrees, and three pin holes220may be arranged while being spaced apart from each other at 30 degrees. An accommodating groove in which an expansion member500that will be described later is accommodated may be formed in an upper end of the pin hole220.

The housing230is positioned under the grounding plate216, and supports the grounding plate216. The housing230is formed in a cylindrical shape having a predetermined height, and a space is formed inside the housing230. The housing230may have a radius corresponding to the radius of the grounding plate216. Various cables (not illustrated) and the lift pin240are positioned inside the housing230.

As the lift pin240moves up and down, the lift pin240loads the substrate W onto the dielectric plate211or unloads the substrate W from the dielectric plate211. The lift pin240supports the substrate W.

A plurality of lift pins240is provided, and is respectively accommodated inside the pin holes220. Here, a diameter of the lift pin240may be slightly less than a diameter of the pin hole220. Specifically, the diameter of the lift pin240may be provided to a minimum diameter at which the lift pin240does not contact an inner wall of the pin hole220when the lift pin240and the pin hole220are disposed to have an equal central axis.

The lift pin240may be driven in a vertical direction by a driving portion (not illustrated).

Referring toFIGS.2A and2B, the pin hole220may be configured such that the diameter of the pin hole220can be changed.

The electrostatic chuck200according to an embodiment of the present disclosure may further include the expansion member500provided at an inner circumference of the pin hole220. The expansion member500may reversibly and repeatedly perform expansion and restoration, and is configured such that a size of an inner circumference of the expansion member500is changed according to the expansion and the restoration of the expansion member500. In a normal state, the size of the inner circumference of the expansion member500is slightly larger than the diameter of the lift pin240. Further, when the expansion member500expands, the size of the inner circumference of the expansion member500is changed to be equal to the diameter of the lift pin240as the expansion member500expands toward an inner portion of the pin hole220. Therefore, when the expansion member500expands, an inner circumferential surface of the expansion member500is in close contact with an outer circumferential surface of the lift pin240, and the diameter of the pin hole220in which the expansion member500is applied becomes smaller than the diameter of the pin hole220in the normal state.

For example, the expansion member500may include or may be formed of a piezoelectric element (i.e., a piezoelectric material) that expands when the power is supplied. The reference number of500may interchangeably refer to the expanding member and the piezoelectric element. Specifically, a piezoelectric element500formed in a tubular shape may be inserted into the upper surface of the dielectric plate211where the upper end portion of the pin hole220is formed. Here, an inner diameter of the piezoelectric element500formed in the tubular shape in a state in which no current flows is formed to have the same diameter of the pin hole220. At this time, the piezoelectric element500is mounted such that the piezoelectric element500is electrically connected to the electrode212which is buried inside the dielectric plate211and which generates the electrostatic force on the chuck member210.

A piezoelectric effect is a phenomenon in which a polarization is formed on an entire of an object. In this phenomenon, an ionic crystal structure is changed when a pressure is applied, and the center of +ions and the center of −ions are dislocated and a symmetry is dislocated, so that a dipole moment is formed, thereby forming the polarization. As a result, the piezoelectric effect is a phenomenon in which a mechanical energy is converted into an electrical energy, and the piezoelectric element refers to an element generating the piezoelectric phenomenon. Since the piezoelectric effect is reversible, an inverse piezoelectric effect in which a mechanical deformation occurs is generated when the electrical energy is applied to the piezoelectric element.

FIGS.3A,3B and4are views illustrating the inverse piezoelectric effect occurring on the piezoelectric element.

According to an embodiment of the present disclosure, when a chucking operation for the substrate W is performed, the power is supplied to the piezoelectric element500by the power applied to the electrode212, the piezoelectric element500being electrically connected to the electrode212, and the inverse piezoelectric effect occurs. That is, the piezoelectric element500inserted into the upper end portion of the pin hole220may expand (seeFIG.3A). As the piezoelectric element500applied to the pin hole220expands by the inverse piezoelectric effect, the diameter of the pin hole220may be reduced compared to the diameter of the pin hole220in the normal state (seeFIG.3). That is, when the power is applied in order to generate the electrostatic force on the chuck member210, the power is also applied to the piezoelectric element500that is connected to the electrode212of the chuck member210, and an electric energy is applied to the piezoelectric element500. Accordingly, the mechanical deformation in which the piezoelectric element500expands occurs, and the diameter of the pin hole220is reduced.

On the other hand, when a dechucking operation for the substrate W is performed, the power applied to the electrode212is blocked and also the power applied to the piezoelectric element500is blocked, and the inverse piezoelectric effect disappears. Therefore, the expanded piezoelectric element500may be restored to an original (normal) size (seeFIG.3B). As a result, the diameter of the pin hole220may be restored to the diameter before the pin hole220is reduced (seeFIG.3B). That is, when the power applied to the chuck member210is blocked, the piezoelectric element500is restored to an original state, and the diameter of the pin hole220is also restored to an original state.

Generally, the chucking operation of the substrate W is maintained when the process for the substrate W is performed. Further, when the process for the substrate W is completed, the dechucking operation of the substrate W is performed. Therefore, when the process for the substrate W is performed, the diameter of the pin hole220may be in the reduced state.

When the piezoelectric element500expands and the diameter of the pin hole220is reduced, the inner circumferential surface of the piezoelectric element500is in close contact with the outer circumferential surface of the lift pin240, so that a gap existing between the pin hole220and the lift pin240disappears. Therefore, a possibility of inflow of a cooling gas that frequently inflows through the gap between the pin hole220and the lift pin240is reduced. Further, a possibility of leaking of particles generated inside the pin hole220by the vertical movement of the lift pin240to a surface of the chuck member210through the gap between the pin hole220and the lift pin240may be significantly reduced.

In addition, when the piezoelectric element500is provided with a material having a high volume resistivity compared to the dielectric plate211, a resistivity around the pin hole220is increased, and a possibility of inflow of the plasma through the pin hole220may be reduced.

As such, as the possibility of inflow of the cooling gas and the plasma toward the inner portion of the pin hole220is reduced, an electrical discharge phenomenon is prevented from occurring inside the pin hole220.

Meanwhile, the piezoelectric element500is provided in a state in which the piezoelectric element500is completely coupled to the inside of the pin hole220formed at the dielectric plate211by using a sintering method and so on. Therefore, by providing the piezoelectric element500with a material having a dielectric constant equal to a dielectric constant of the dielectric plate211, the ease of coupling the piezoelectric element500to the dielectric plate211may be increased. For example, the piezoelectric element500may be formed of a piezoelectric ceramic material which has a dielectric constant equal to the dielectric constant of the dielectric plate211and which has a high volume resistivity.

Meanwhile, although not illustrated in detail, the piezoelectric element500may be provided such that the piezoelectric element500is supplied with the power separately from the electrode212. That is, the piezoelectric element500may be supplied with the electric energy by being connected to a power source (not illustrated) that is controlled independently from a power source applied to the electrode212. The piezoelectric element500may reduce the diameter of the pin hole220by receiving the electric energy from the separate power source (not illustrated) and by expanding. Further, the piezoelectric element500may be maintained (restored) to the original state when the electric energy is not supplied to the piezoelectric element500.

As described above, a substrate processing method according to an embodiment of the present disclosure may include a substrate chucking process, a plasma processing process performed on a chucked substrate, and a substrate dechucking process.

The substrate chucking process is performed by applying the power to the electrode212mounted in the chuck member210, thereby generating the electrostatic force for the substrate. At this time, the electric energy is supplied to the piezoelectric element500that is electrically connected to the electrode212, and the diameter of the inner circumference of the pin hole220is reduced since the piezoelectric element500expands by the inverse piezoelectric effect. The substrate chucking process is maintained during performing the plasma processing process performed on the substrate. Therefore, during performing the plasma processing process, the diameter of the inner circumference of the pin hole220remains reduced.

When the piezoelectric element500expands and the diameter of the pin hole220is reduced, the inner circumferential surface of the piezoelectric element500is in close contact with the outer circumferential surface of the lift pin240, so that the gap existing between the pin hole220and the lift pin240disappears. Therefore, the possibility of inflow of the cooling gas that frequently inflows through the gap between the pin hole220and the lift pin240is reduced. Further, the possibility of leaking of particles generated inside the pin hole220by the vertical movement of the lift pin240to the surface of the chuck member210through the gap between the pin hole220and the lift pin240may be significantly reduced.

In addition, when the piezoelectric element500is provided with a material having a high volume resistivity compared to the dielectric plate211, a resistivity around the pin hole220is increased, and the possibility of inflow of the plasma through the pin hole220may be reduced.

As such, during performing the plasma processing process, the possibility of inflow of the cooling gas and the plasma toward the inner portion of the pin hole220is reduced by the expansion member500, so that the electrical discharge phenomenon is prevented from occurring inside the pin hole220.

When the plasma processing process is completed, the substrate dechucking process is performed. Further, in the substrate dechucking process, the power supplied to the electrode212of the chuck member210is blocked. Accordingly, the power supplied to the piezoelectric element500is also blocked, and the inverse piezoelectric effect disappears, so that the expanded piezoelectric element500may be restored to the original state. As the piezoelectric element500is restored, a length of the inner circumference of the pin hole220that is reduced may also be restored to a length before the pin hole220is reduced.

Then, in order to take the substrate on which the plasma processing process has been completed out of the processing space, the lift pin240may be moved upward.

FIG.5is a flowchart illustrating a method of manufacturing an electrostatic chuck according to an embodiment of the present disclosure.

The electrostatic chuck200according to an embodiment of the present disclosure is manufactured to include the expansion member500. The expansion member500is inserted into the upper end portion of the pin hole220formed in the chuck member210. Further, the expansion member500includes an inner circumferential surface that is in close contact with the outer circumferential surface of the lift pin240that is accommodated in the pin hole220while the lift pin240is capable of moving up and down when the expansion member500expands. A size of the inner circumference of the expansion member500in the normal state is provided to be equal to a size of the inner circumference of the pin hole220. For example, the expansion member500may be a piezoelectric element that expands by receiving the power.

By using the expansion member500that is applied to the upper end portion of the pin hole220that is formed through the chuck member210, the diameter of the pin hole220may be changed.

The method of manufacturing the electrostatic chuck according to an embodiment of the present disclosure may include processing the pin hole220in the chuck member210(S1), inserting the expansion member500into the upper end portion of the pin hole220(S2), and fixing the expansion member to the chuck member210(S3).

The processing of the pin hole220(S1) is a process of processing the pin hole220in which the lift pin240capable of moving up and down is accommodated in the chuck member210, and is a process of processing the pin hole220such that the pin hole220penetrates through the upper surface and the lower surface of the chuck member210. The processing of the pin hole220(S1) may include a counter-boring process in which the upper surface of the chuck member210that is also the upper end portion of the pin hole220is processed to have a shape of the expansion member500that will be inserted. In the processing of the pin hole220process (S1), at least one of the pin holes220are processed, and at least one of the pin holes220may be processed before sintering the electrostatic chuck.

The piezoelectric element500formed in a tubular shape may be inserted into the upper surface of the processed chuck member210. Specifically, the piezoelectric element500may be inserted into the upper surface of the dielectric plate211. The piezoelectric element500is an element generating the piezoelectric effect, and may expand according to the supplied power. In addition, the piezoelectric element500may be formed of a material having a volume resistivity higher than a volume resistivity of the dielectric plate211, and may have the dielectric constant equal to the dielectric constant of the dielectric plate211.

The piezoelectric element500may be inserted into the dielectric plate211so that the piezoelectric element500is electrically connected to the electrode212. In an embodiment, the piezoelectric element500may be connected with a separate power supply and may be inserted into the dielectric plate211.

After then, the inserted piezoelectric element500may be fixed to the chuck member210(S3). The fixing process (S3) may be performed by sintering the electrostatic chuck while the piezoelectric element500is inserted into the upper end portion of the pin hole220. Meanwhile, when the pin hole220is processed before sintering the electrostatic chuck and then the sintering of the electrostatic chuck is performed, a distance between the pin holes220may not be uniform according to a shrinkage rate. Therefore, when the pin hole220is processed before sintering the electrostatic chuck, the pin hole220is required to be accurately processed so that the pin hole220corresponds to a predetermined position in consideration of the shrinkage rate. Meanwhile, another coupling method may be used as a fixing method of the piezoelectric element500.

The inner diameter of the piezoelectric element500in the normal state is equal to the diameter of the pin hole220in the normal state. That is, the inner diameter of the piezoelectric element500is slightly larger than the diameter of the lift pin240. Specifically, the diameter of the piezoelectric element500may be provided to have a minimum diameter at which the lift pin240does not contact the inner wall of the piezoelectric element500when the lift pin240and the piezoelectric element500are disposed to have the same central axis.

When the chucking operation of the substrate W is performed, the piezoelectric element500mounted such that the piezoelectric element500is electrically connected to the electrode212may generate the inverse piezoelectric effect by receiving the power. Specifically, when the power is applied to the piezoelectric element500, the piezoelectric element500may expand. As the piezoelectric element500expands, the diameter of the inner circumference of the piezoelectric element500is reduced, so that the diameter of the inner circumference of the pin hole220may be reduced. The inner circumferential surface of the expanded piezoelectric element500may be in close contact with the outer circumferential surface of the lift pin240.

When the dechucking operation of the substrate W is performed, the expanded piezoelectric element500is restored to the original state, and the reduced diameter of the pin hole220may be restored to the original state. When the inverse piezoelectric effect is generated on the piezoelectric element500and the diameter of the pin hole220is reduced, the gap between the pin hole220and the lift pin240, the gap existing on the upper surface of the chuck member210, may disappear. Therefore, the plasma and the cooling gas may be prevented from entering inside the pin hole220, and the particles may be prevented from leaking to the surface of the chuck member210from the pin hole220. Accordingly, the occurrence of electrical discharge (arcing) in the pin hole220and in the substrate processing apparatus may be minimized.

As described above, the electrostatic chuck200, the substrate processing apparatus including the electrostatic chuck200, the substrate processing method, and the method of manufacturing the electrostatic chuck200according to an embodiment of the present disclosure have been described with reference toFIGS.1to5. The electrostatic chuck200according to an embodiment of the present disclosure includes the expansion member500inserted into the inner circumference of the pin hole220. The expansion member500may reversibly and repeatedly perform the expansion and the restoration. Further, by the inner circumferential surface of the expansion member500that is in close contact with the outer circumferential surface of the lift pin240when the expansion member500expands, the fine gap existing between the pin hole220and the lift pin240may be temporarily removed. The expansion member500may be the piezoelectric element that expands by receiving the power, and may maintain the expanding state during performing the plasma processing process. When the expansion member500remains expanded during performing the plasma processing process, the plasma and the cooling gas that are entering the inside of the pin hole220through the gap between the pin hole220and the lift pin240may be prevented from entering. Further, particles from the inside of the pin hole220may be prevented from leaking to the surface of the chuck member210. Accordingly, the occurrence of electrical discharge (arcing) in the substrate processing apparatus may be minimized.

Meanwhile, the shape of the piezoelectric element500is not limited to the example as described above, and may be applied in any shape that can reduce the diameter of the upper portion pin hole220or the entire diameter of the pin hole220. For example, the piezoelectric element500may be applied to the entire inner wall of the pin hole220.

In addition, as described above, the example in which the expansion member applied to the upper end portion of the pin hole220is the piezoelectric element500that expands when the power is applied to the piezoelectric element500has been described, but the shape of the expansion member is not limited thereto. Further, any shape of the expansion member capable of changing the diameter of the pin hole220as the expansion state and the restoration state are reversibly changed may be applied.

Although the embodiments of the present disclosure have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the present disclosure. As described above, the embodiments and the accompanying drawings disclosed in the present disclosure are provided for describing the present disclosure and are not intended to limit the technical ideas of the present disclosure. The technical ideas of the present disclosure are not limited to the embodiments and the drawings. The scope of the present disclosure should be construed as being covered by the scope of the appended claims, and all technical ideas falling within the scope of the claims should be construed as being included in the scope of the present disclosure.