DEVICE FOR TREATING SEMICONDUCTOR PROCESS EXHAUST GAS

Abstract

Provided is an exhaust gas treatment apparatus that treats exhaust gas generated from semiconductor process and directed to a vacuum pump. Exhaust gas treatment apparatus includes a plasma generating unit for generating plasma, a reaction chamber in which perfluoride is decomposed by the plasma to generate a decomposition gas, and gas supplying unit for supplying the decomposition gas from the reaction chamber to a processing chamber in which the exhaust gas from the semiconductor process is introduced and treated exhaust gas is discharged to the vacuum pump. Decomposition gas reacts with the exhaust gas in the processing chamber to suppress generation of salt in solid state by a component of the exhaust gas.

Claims

1. An exhaust gas treatment apparatus for processing an exhaust gas generated from a semiconductor process and directed to a vacuum pump, the apparatus comprising: a plasma generating unit for generating plasma; a reaction chamber in which perfluoride is decomposed by the plasma to generate decomposition gas; and a gas supplying unit for supplying the decomposition gas from the reaction chamber to a processing chamber in which the exhaust gas from the semiconductor process is introduced and treated exhaust gas is discharged to the vacuum pump, wherein the decomposition gas reacts with the exhaust gas in the processing chamber to suppress generation of salt in solid state by a component of the exhaust gas.

2. The apparatus of claim 1, wherein the plasma generating unit generates N.sub.2 plasma by arc plasma, wherein NF.sub.3 as the perfluoride supplied too the reaction chamber is decomposed by the N.sub.2 plasma to generate the decomposition gas containing N.sub.2, NF.sub.3 or F.sup.−, wherein the decomposition gas supplied to the processing chamber reacts with NH.sub.3 of the exhaust gas or generated NH.sub.4Cl to form gaseous NH.sub.4F so that forming of solid NH.sub.4Cl is suppressed.

3. The apparatus of claim 2, wherein the gas supplying unit comprises, a connection pipe through which the decomposition gas from the reaction chamber is moved; and a gas injecting unit disposed between the connection pipe and the processing chamber, and injecting the decomposition gas into the processing chamber.

4. The apparatus of claim 3, wherein the gas injection unit includes, an exterior portion having one end coupled to the connection pipe; and a differential pressure centering ring coupled to the other end of the exterior portion, provided inside the connection pipe and spaced apart from an inner surface of the connection pipe, and injecting the decomposition gas into the processing chamber by a pressure difference between the connection pipe and the processing chamber.

5. The apparatus of claim 4, wherein the decomposition gas has uniformity by vortex caused by a space between the differential pressure centering ring and the inner surface of the connection pipe, and flows into the differential pressure centering ring.

6. The apparatus of claim 3, wherein the NF.sub.3 gas is supplied to the reaction chamber rather than between anode and cathode generating the arc plasma, so that the lifetime of the anode and the cathode is improved.

7. The apparatus of claim 2, wherein the exhaust gas forms ammonium chloride salt due to Reaction Formula 1, and the generation of the ammonium chloride salt in solid state is suppressed due to Reaction Formula 2 and Reaction Formula 3 in the processing chamber.
3TiCl.sub.4+8NH.sub.3.fwdarw.3TiN+1/2N.sub.2+8HCl+4NH.sub.4Cl   [Reaction Formula 1]
TiCl.sub.4+N.sub.2+NH.sub.3+NF.sub.3.fwdarw.TiN+Ti.sub.xF.sub.y+NF.sub.3+HF+HCl+Ti.sub.3N.sub.4+NH.sub.4F   [Reaction Formula 3]
NH.sub.4Cl+NF.sub.3.fwdarw.NH.sub.4F+Cl.sub.2+HCl

8. The apparatus of claim 3, further comprises control unit for controlling a supply amount and component of the decomposition gas by controlling supply amount of the N.sub.2 plasma and supply amount of the NF.sub.3 gas.

Description

DESCRIPTION OF DRAWINGS

[0026] FIG. 1 is view for explaining an example in which salt powder is generated due to exhaust gas in a semiconductor process.

[0027] FIG. 2 is a view showing an exhaust gas treatment apparatus for semiconductor process according to an embodiment of the present inventive concept.

[0028] FIG. 3 is a view for explaining a process in which the exhaust gas treatment apparatus operates between semiconductor processing equipment and vacuum pump according to an embodiment of the present inventive concept.

[0029] FIG. 4 is a view for explaining a method in which the exhaust gas treatment apparatus is connected to the exhaust gas supplied from a semiconductor process and connected to a vacuum pump.

[0030] FIG. 5 a diagram illustrating an example of a plasma generating unit and a reaction chamber of exhaust gas treatment apparatus.

[0031] FIG. 6 is a view for explaining that NF.sub.3 is supplied to reaction chamber.

[0032] FIG. 7 is a view for explaining a connection part of exhaust gas treatment apparatus.

[0033] FIG. 8 is a diagram for explaining pressure differential centering ring in a connection part of an exhaust gas treatment apparatus.

[0034] FIG. 9 is a view for explaining a process of reducing salt powder by exhaust gas treatment apparatus according to an embodiment of the present inventive concept.

[0035] FIGS. 10 and 11 are views showing test results of NF.sub.3 decomposition efficiency of exhaust gas treatment apparatus according to an embodiment of the present inventive concept.

[0036] FIGS. 12 and 13 are diagrams showing performance test results of an exhaust gas treatment apparatus according to an embodiment of the present inventive concept.

[0037] FIG. 14 is diagram for explaining performance and effects of exhaust gas treatment apparatus according to an embodiment of the present inventive concept.

MODES OF THE INVENTION

[0038] Since the present inventive concept may be variously changed and have various forms, specific embodiments will be exemplified in the drawings and described in detail in the text. However, it should be understood that this does not limit the present inventive concept to a specific disclosure, and includes all modifications, equivalents and substitutes included in the spirit and the scope of the present inventive concept. In a description of each drawing, similar reference numerals are used for similar elements.

[0039] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art. Terms such as terms defined in generally used dictionaries should be interpreted as having meanings consistent with the meanings in the context of the related art, and should not be interpreted in an idealistic or excessively formal sense unless otherwise defined in the present application.

[0040] Hereinafter, exemplary embodiments of the present inventive concept will be described in more detail with reference to the accompanying drawings.

Embodiment

[0041] The present inventive concept is related to exhaust gas treatment apparatus that treats exhaust gas generated from a semiconductor process and directed to a vacuum pump. The exhaust gas treatment apparatus of the present inventive concept prevents by-products caused by specific gases generated in the semiconductor main process from flowing into the vacuum pump and causing problems in pump maintenance and facility operation. Accordingly, it is possible to improve the efficiency of pump maintenance and facility operation and to improve the lifetime of the vacuum pump.

[0042] FIG. 2 is a view showing an exhaust gas treatment apparatus for semiconductor process according to an embodiment of the present inventive concept.

[0043] Referring to FIG. 2, exhaust gas treatment apparatus 100 for semiconductor process has plasma generating unit 110, reaction chamber 120 and gas supplying unit 130.

[0044] The plasma generating unit 110 has an anode and a cathode, and may generate arc plasma. In addition, nitrogen (N.sub.2) gas may be supplied to the plasma generating unit 110, and nitrogen (N.sub.2) plasma may be generated by arc plasma.

[0045] In the reaction chamber 120, perfluoride is decomposed by the plasma to generate decomposition gas. That is, perfluoride and plasma are introduced into the reaction chamber 120, and the perfluoride is changed to a decomposition gas by the plasma.

[0046] The gas supplying unit 130 may supply decomposition gas from the reaction chamber 120 to the processing chamber 200. The decomposition gas in the gas supplying unit 130 has a uniform concentration. To acquire uniform concentration, the gas supplying unit 130 has a connection pipe 131 and a gas injecting unit 132.

[0047] The connection pipe 131 is a double-structured elbow part, cooling is performed through water in the outer space of the connection pipe 131, and decomposition gas is supplied from the reaction chamber 120 to inner space of the connection pipe 131. The connection pipe 131 is disposed between the reaction chamber 120 and the gas injecting unit 132, cools the decomposition gas supplied from the reaction chamber 120, and supplies it to the gas injecting unit 132.

[0048] The gas injecting unit 132 has an exterior portion 1321 and a differential pressure centering ring 1322. One side of the exterior portion 1321 is connected to the connection pipe 131, and the pressure differential centering ring 1322 is fastened to the other side. The differential pressure centering ring 1322 is disposed inside the exterior portion 1321 and has a shape protruding toward the connection pipe 131. The decomposition gas in the gas injecting unit 132 has a uniform concentration by eddy current and is discharged to the outside.

[0049] FIG. 3 is a view for explaining a process in which the exhaust gas treatment apparatus operates between semiconductor processing equipment and vacuum pump according to an embodiment of the present inventive concept.

[0050] Referring to FIG. 3, exhaust gas from the semiconductor process flows into the processing chamber 200, and decomposition gas supplied from the exhaust gas treatment apparatus 100 also flows into the processing chamber 200. In the processing chamber 200, a treated exhaust gas is generated by a reaction between the exhaust gas and the decomposition gas, and the treated exhaust gas is discharged to a vacuum pump.

[0051] The decomposition gas supplied from the gas supplying unit 130 to the processing chamber 200 may react with the exhaust gas in the processing chamber 200 to suppress generation of salt of solid state or remove already generated salt of solid state.

[0052] FIG. 4 is a view for explaining a method in which the exhaust gas treatment apparatus is connected to the exhaust gas supplied from a semiconductor process and connected to a vacuum pump.

[0053] Referring to FIG. 4, nitrogen gas is supplied to the plasma generating unit, and cooling water is supplied to the plasma generating unit. In addition, as an example of perfluoride, NF.sub.3 gas is supplied to the reaction chamber, and cooling water is supplied to the reaction chamber. Cooling water is also supplied to the gas supplying unit, and the supplied cooling water is filled in the outer space of the connection pipe, which is a double-structured elbow part, and is used to cool the decomposition gas.

[0054] FIG. 5 is a cross-sectional view showing the plasma generating unit of FIG. 2 of the present inventive concept.

[0055] Referring to FIG. 5, the plasma generating unit 110 may generate N.sub.2 plasma by arc plasma. The plasma generating unit 110 may include an electrode cooling PCW unit 111, a cathode 112, an anode 113, an N.sub.2 supply unit 114, a plasma circular tube 115, and a cooling PCW unit 116. The PCW is an abbreviation of process cooling water and refers to a cooling operation through water. However, the cooling operation does not necessarily have to be water, and any liquid capable of performing the cooling operation may be used.

[0056] When N.sub.2 gas is introduced through the N.sub.2 supply unit 114, N.sub.2 plasma is generated between the cathode 112 and the anode 113 through arc discharge of the cathode 112 and the anode 113. The generated N.sub.2 plasma is discharged through the plasma circular tube 115. The electrode cooling PCW unit 111 prevents the cathode 112 or the anode 113 from overheating and performs a cooling operation. In addition, the cooling PCW unit 116 prevents high-temperature heat of the plasma generating unit 110 from being transferred to the reaction chamber 120 to hinder decomposition operation of gas.

[0057] FIG. 6 is a cross-sectional view showing the reaction chamber of FIG. 2 of the present inventive concept.

[0058] Referring to FIG. 6, the reaction chamber has a perfluoride inlet 121 and an inner chamber 122. Gaseous perfluoride is supplied through the perfluoride inlet 121 and introduced into the inner chamber 122. NF.sub.3 gas which is an example of perfluoride supplied to the inner chamber 122 of the reaction chamber 120 is decomposed by N.sub.2 plasma to generate decomposition gas containing N.sub.2, NF.sub.3, or F.sup.−. That is, F radicals may be generated by plasma decomposition of NF.sub.3 gas.

[0059] The NF.sub.3 gas is not directly supplied to the torch of the plasma generating unit, but flows into the reaction chamber 120 connected to the plasma generating unit. That is, since the NF.sub.3 gas is supplied to the reaction chamber 120 instead of between the anode and cathode generating the arc plasma, the lifetime of the anode and cathode of the plasma generating unit can be improved.

[0060] Since the reaction chamber 120 has a double-structured chamber structure, a plasma flame is maintained at a state close to atmospheric pressure and plasma density can be secured.

[0061] The generated decomposition gas is supplied to the processing chamber as described above, and the decomposition gas reacts with NH.sub.3 of the exhaust gas or generated NH.sub.4Cl to generate gaseous NH.sub.4F, so that the generation of solid NH.sub.4Cl can be suppressed.

[0062] FIG. 7 is a view for explaining a connection pipe of a gas supplying unit of exhaust gas treatment apparatus.

[0063] FIG. 8 is a diagram for explaining a gas injecting unit of a gas supplying unit of an exhaust gas treatment apparatus.

[0064] FIG. 9 is a diagram for explaining a process of suppressing generation of salt powder by exhaust gas treatment apparatus according to an embodiment of the present inventive concept.

[0065] The gas supplying unit 130 may include a connection pipe 131 and a gas injecting unit 132.

[0066] Referring to FIG. 7, one end of the connection pipe 131 is connected to the reaction chamber 120 and the other end is connected to the gas supplying unit. Decomposition gas from the reaction chamber 120 may be moved through the connection pipe 131. For example, the connection pipe 131 may be a double-structured elbow part. The double-structured elbow part may have a PCW (process cooling water) supply structure, and accordingly, the temperature of the decomposition gas in the connection pipe may be controlled through cooling effect in the inner pipe. That is, in the double structure, the outer space is filled with cooling water, and the decomposition gas is supplied to the inner space. The temperature-controlled decomposition gas is introduced into the gas injecting unit.

[0067] Referring to FIG. 8, a gas injecting unit 132 may be provided between the connection pipe 131 and the processing chamber. The gas injecting unit 132 may inject the decomposition gas from the connection pipe 131 into the processing chamber.

[0068] For example, the gas injecting unit 132 may include an exterior portion 1321 having one end coupled to the connection pipe 131 and a differential pressure centering ring 1322. The gas injecting unit 132 may be a connection centering ring structure that distributes pressure inside the connection pipe 131.

[0069] The exterior portion 1321 may be a tubular connector connecting the connection pipe 131 and the processing chamber. The exterior portion 1321 may have a shape in which a diameter decreases as it approaches the differential pressure centering ring 1322. One side of the exterior portion 1321 is connected to the connection pipe, and the other side of the exterior portion 1321 is connected to the differential pressure centering ring 1322.

[0070] The differential pressure centering ring 1322 may be provided inside the exterior portion 1321 to be spaced apart from the inner surface of the exterior portion 1321. The differential pressure centering ring 1322 has a tubular structure with a smaller diameter than the exterior portion 1321 and has a shape protruding toward the connection pipe 131. The differential pressure centering ring 1322 may inject the decomposition gas into the processing chamber by a pressure difference between the processing chamber and the connection pipe 131. For example, the pressure of the connection pipe 131 may be 10.sup.−1 Torr and the pressure of the processing chamber may be 10.sup.−3 Torr. Due to the structural characteristics of the differential pressure centering ring, fluid vortex and fluid pressure increase at neighboring region of the differential pressure centering ring. Accordingly, the fluidic pressure in the inner region of the exterior portion where the differential pressure centering ring is positioned has a higher value than the pressure in the area discharged from the differential pressure centering ring. Therefore, the decomposition gas of the differential pressure centering ring may flow into the processing chamber due to the difference of pressure.

[0071] A vortex may be generated due to a space between the outer surface of the pressure differential centering ring 1322 and the inner surface of the exterior portion 1321. A vortex is a phenomenon in which a part of a fluid is disturbed and flows in the opposite direction to the main current. The decomposition gas introduced from the connection pipe 131 has a main stream from the connection pipe toward the differential pressure centering ring 1322. The decomposition gas forms a vortex flowing in the opposite direction to the main stream in space between the outer surface of the differential pressure centering ring 1322 and inner surface of the exterior portion 1321. Since the radius of the exterior portion 1321 decreases as the distance from the connection pipe 131 increases, the pressure increases as it approaches the processing chamber of FIG. 3. Therefore, the speed of the vortex has a higher value than the speed of the main current, and the decomposition gas in the gas injecting unit has a uniform concentration. Accordingly, the uniformity of the decomposition gas flowing from the connection pipe 131 to the gas injecting unit 132 is improved so that it can flow into the inlet of the differential pressure centering ring. Thus, decomposition gas with improved uniformity can be supplied to the processing chamber.

[0072] Due to the semiconductor process, an ammonium salt may be formed as shown in reaction formula 1 below.

6TiCl.sub.4+20NH.sub.3.fwdarw.6TiN+N.sub.2+12HCl+12NH.sub.4Cl   [reaction formula 1]

[0073] As described above, such ammonium chloride may undergo a phase change from a gas phase to a solid phase depending on temperature and pressure conditions. When the solid salt is formed and flows into the vacuum pump, it may cause a failure of the vacuum pump and cause a great difficulty in ordinary operation such as stopping the process.

[0074] The exhaust gas treatment apparatus for semiconductor process according to the present embodiment gasifies solid salts generated from exhaust gas of the semiconductor process before being discharged to the vacuum pump, thereby preventing problems such as failure of the vacuum pump.

[0075] Specifically, as shown in reaction formula 2 and reaction formula 3 below in the processing chamber, the generation of solid ammonium chloride salt can be suppressed.

TiCl.sub.4+4NH.sub.3+3F.fwdarw.TiN+3NH.sub.4F+2Cl.sub.2   [reaction formula 2]

8NH.sub.4Cl+6F.fwdarw.6NH.sub.4F+8HCl+N.sub.2

[0076] The decomposition gas formed by the N.sub.2 plasma may include N.sub.2, NF.sub.3 or F.sup.−. The high energy components of the decomposition gas react with ammonia in the exhaust gas to suppress the production of ammonium chloride, or react with already produced ammonium chloride to decompose ammonium chloride, so that the production of solid ammonium chloride salt can be suppressed.

[0077] FIG. 10 is a diagram showing test results of the decomposition efficiency of NF.sub.3 gas of exhaust gas treatment apparatus according to an embodiment of the present inventive concept.

[0078] FIG. 11 is a table disclosing test conditions of FIG. 10 according to an embodiment of the present inventive concept.

[0079] FIG. 11 shows process conditions such as N.sub.2 plasma supply amount.

[0080] Referring to FIGS. 10 and 11, N.sub.2 plasma is generated according to current and voltage conditions set in the table. The amount of N.sub.2 plasma generated by flowing into the plasma generating unit is shown in the table of FIG. 11. In addition, NF.sub.3, which is a perfluoride, is supplied to the reaction chamber at a flow rate of 3 L/m. Under the condition that exhaust gas is not supplied, the amount of NF.sub.3 gas is measured at the rear end of the vacuum pump. It can be seen that a large amount of NF.sub.3 gas is detected when the plasma is off, and when N.sub.2 plasma is supplied at 6 L/m, NF.sub.3 is reduced and decomposition is proceeded. Thereafter, when the N.sub.2 plasma increases, it can be confirmed that the decomposition is effectively performed because the amount of NF.sub.3 detected is very small or almost not detected.

[0081] As described above, the amount and composition of the decomposition gas may be controlled by adjusting the amount of N.sub.2 plasma, and adjusted decomposition gas may be supplied to the processing chamber. That is, the N.sub.2, NF.sub.3, or F.sup.− component included in the decomposition gas can be controlled.

[0082] The exhaust gas treatment apparatus of the present embodiment may further include a control unit configured to control the components and supply amount of the decomposition gas by adjusting the N.sub.2 plasma supply amount and the NF.sub.3 supply amount.

[0083] FIG. 12 is a view showing testing result for reaction of ammonia in a processing chamber according to an embodiment of the present inventive concept.

[0084] FIG. 13 is a table disclosing the test conditions of FIG. 12 according to an embodiment of the present inventive concept.

[0085] Referring to FIGS. 12 and 13, NH.sub.3 gas is supplied to the process chamber, and N.sub.2 gas as shown in FIG. 12 is supplied to the plasma generating unit. In addition, NF.sub.3 gas is supplied to the reaction chamber at a flow rate of 3 L (liter)/min The flow rate of N.sub.2 discharged through the vacuum pump is 20 L/min. The current voltage condition represents power for generating N.sub.2 plasma in the plasma generating unit. In the graph of FIG. 12, the concentrations of NF.sub.3 and NH.sub.3 are indicated, and the concentrations are those measured in gas discharged through a vacuum pump.

[0086] From 30 seconds after the performance test starts, ammonia flows into the process chamber. When one and half minutes have elapsed, supply of NH.sub.3 is stopped, and NF.sub.3 gas is supplied to the N.sub.2 plasma. In addition, NH.sub.3 gas is supplied from about 3 and half minutes, and N.sub.2 plasma is repeatedly turned on/off by dividing the time interval. Through repeated on/off of the N.sub.2 plasma, the processing gases are evenly distributed in the reaction chamber, the gas supplying unit, and the processing chamber, and conditions for normal operation of various components are provided.

[0087] When the N.sub.2 plasma is turned on after about 8 minutes and 45 seconds have elapsed, the NH.sub.3 gas supplied to the processing chamber starts to be decomposed and the concentration rapidly decreases. In addition, when 10 minutes and 20 seconds have elapsed, the N.sub.2 plasma is turned off and the supply of the NH.sub.3 gas is also stopped. By turning off the N.sub.2 plasma, decomposition gas due to the decomposition of NF.sub.3 is not generated, and the supplied NF.sub.3 is discharged through the vacuum pump, and the amount of discharged NF.sub.3 increases. In addition, since the supply of NH.sub.3 gas is also stopped, NH.sub.3 discharged through the vacuum pump is not detected.

[0088] Finally, when the N.sub.2 plasma is turned on after 11 minutes and 35 seconds have elapsed, the NF.sub.3 gas is decomposed by the plasma and generated as a decomposition gas. Thus, the amount of NF.sub.3 in the vacuum pump is drastically reduced.

[0089] That is, it can be confirmed that the components of the decomposition gas generated when the plasma is on reacts very well with ammonia in the exhaust gas, and only N.sub.2 is supplied by controlling the decomposition gas, or the decomposition gas of NF.sub.3 is supplied together with the N.sub.2 plasma to induce a reaction with ammonia.

[0090] Accordingly, the production of ammonium chloride may be inhibited or the generated ammonium chloride may be decomposed into a gas in the form of NH.sub.4F.

[0091] FIG. 14 is a table for explaining the performance of exhaust gas treatment apparatus according to an embodiment of the present inventive concept.

[0092] Referring to FIG. 14, it can be seen that exhaust gas treatment apparatus according to the present inventive concept has superior and remarkable effects compared to conventional methods.

[0093] The conventional technology is a non-contact method of applying microwave or ICP for NF.sub.3 gas to NF.sub.3 gas, indirect decomposition method is used, and power consumption increases due to the indirect decomposition method. On the other hand, in the present inventive concept, a direct decomposition method is used in which arc discharge is directly performed on N.sub.2 gas to generate plasma and NF.sub.3 gas is brought into contact with the generated plasma to generate decomposition gas. Therefore, high-density plasma can be generated by using low power and a large amount of decomposition gas can be generated.

[0094] That is, by suppressing the generation of ammonium chloride salt by decomposition gas as described above, productivity is improved by reducing the number of vacuum pump failures and reducing stop loss. Also, the PM (Preventive Maintenance) cycle can be extended.

[0095] In addition, the exterior portion 1321 and the differential pressure centering structure in the gas supplying unit 130 allow the components of the decomposition gas to be more uniformly supplied.

[0096] In addition, according to the exhaust gas decomposition apparatus of the present inventive concept, it is possible to overcome the capacity limitations of conventional microwave, ICP, and RF methods. That is, the conventional technology has handicap which is an increase in capacity, energy use, and operating cost due to an increase of gas consumption in the recent nano process. However, according to the exhaust gas treatment apparatus of the present inventive concept, the supply amount of decomposition gas is easily controlled so that it is possible to smoothly solve the increase of the amount of process gas used.

[0097] In addition, a method of supplying NF.sub.3 to the reaction chamber 120 and decomposing NF.sub.3 by N.sub.2 plasma to generate decomposition gas is used instead of directly spraying NF.sub.3 to the electrode of the plasma generating unit 110. Thus, the problem of shortening the life time of the electrodes in the plasma generating unit is resolved, and the life time of the electrodes of the plasma generating unit 110 can be extended. Of course, a material having strong corrosion resistance may be used for a reaction unit such as a reaction chamber.

[0098] The above description of the present inventive concept is for illustration, and those of ordinary skill in the art to which the present inventive concept pertains will understand that it can be easily modified into other specific forms without changing the subject matter or essential features of the present inventive concept. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. For example, each component described as a single type may be implemented in a dispersed form, and likewise components described as distributed may be implemented in a combined form.

[0099] The scope of the present inventive concept is indicated by the following claims, and all changes or modifications derived from the meaning and scope of the claims and equivalent concepts should be interpreted as being included in the scope of the present inventive concept.