Apparatus for processing a substrate and method for processing a substrate

Abstract

A substrate processing apparatus is provided. The substrate processing apparatus includes a processing chamber having an internal processing space, a support unit supporting a substrate in the processing space, a gas supply unit supplying a processing gas into the processing space, and an RF power source providing an RF signal to excite the processing gas into a plasma state, wherein the support unit includes a edge ring surrounding the substrate, a coupling ring disposed below the edge ring and including an electrode therein, and a cable connected with the electrode, wherein an end of the cable is grounded.

Description

TECHNICAL FIELD

[0001] Exemplary embodiments of the inventive concept described herein relate to an apparatus for processing a substrate and a method for processing a substrate. More particularly, embodiments of the inventive concept disclosed herein relate to a substrate processing apparatus and method for controlling harmonics generated during plasma processing. BACKGROUND

[0002] During a semiconductor device manufacturing process, a desired pattern is formed on a substrate by performing various processes such as photolithography, etching, ashing, ion implantation, thin film deposition, cleaning, etc. Among them, the etching process is a process of selectively removing at least a portion of a film formed on a substrate, and uses wet etching and dry etching. For dry etching, an etching apparatus using plasma is employed.

[0003] In general, in order to generate plasma, an electromagnetic field is formed in an inner space of a process chamber, and the electromagnetic field excites a process gas provided in the process chamber into a plasma state. Plasma refers to an ionized gas state including ions, electrons, radicals, etc. Plasma is generated by a very high temperature, a strong electric field, or an RF electromagnetic field.

[0004] For a plasma etcher, an RF signal is applied to an electrostatic chuck to generate plasma. In this case, since the area of the electrostatic chuck is limited, the plasma density is not uniformly distributed, and thus a focus ring or an edge ring is provided at the edge of the electrostatic chuck. Such a focus ring or edge ring can only control the initial plasma state in the edge region, and the initial controlled state changes as the focus ring or edge ring is consumed by plasma during the plasma process.

[0005] That is, the initial edge plasma can be controlled by the focus ring or edge ring, but plasma control in the center of the substrate is not possible. Therefore, it is not possible to control the high etching rate in the center region by high frequency harmonic control of the high density plasma. SUMMARY

[0006] Embodiments of the inventive concept provide a substrate processing apparatus for controlling harmonics generated during plasma processing.

[0007] The technical objects of the inventive concept are not limited to the above-mentioned ones, and other technical objects not mentioned above will be clearly understood by persons skilled in the art from the following description.

[0008] Embodiments of the inventive concept provide a substrate processing apparatus.

[0009] The apparatus includes a processing chamber having a processing space therein, a support unit for supporting a substrate in the processing space, a gas supply unit for supplying a processing gas into the processing space, and an RF power source for providing an RF signal to excite the processing gas into a plasma state, wherein the support unit includes an edge ring surrounding the substrate, a coupling ring disposed below the edge ring and including an electrode therein, and a cable having one end connected to the electrode and the opposite end grounded.

[0010] In one embodiment, the cable is provided to be variable in length.

[0011] In one embodiment, the length of the cable is provided to have a low impedance with respect to a harmonic component desired to be removed from a harmonic component generated in the processing chamber.

[0012] In one embodiment, the cable is provided in length to have an impedance of about 50 Ω to 1000 Ω.

[0013] In one embodiment, the substrate processing apparatus can further include a circuit unit connected between the cable and the ground.

[0014] In one embodiment, the circuit unit includes a resistor connected in series with the cable.

[0015] In one embodiment, the circuit unit includes a filter circuit that passes only a specific wavelength.

[0016] In one embodiment, the filter circuit includes at least one of a band pass filter, a low pass filter, a high pass filter, or a combination thereof.

[0017] In one embodiment, the filter circuit is any one of the band pass filter, the high pass filter, or a combination of the band pass filter and the high pass filter.

[0018] A substrate processing apparatus according to another aspect of the inventive concept is provided.

[0019] The apparatus includes a processing chamber having an internal processing space therein, a support unit for supporting a substrate in the processing space, a gas supply unit for supplying a processing gas into the processing space, and an RF power source for providing an RF signal to excite the processing gas into a plasma state, wherein the support unit includes an edge ring surrounding the substrate, a coupling ring disposed below the edge ring and including an electrode therein, and a cable having one end connected with the electrode and an opposite end grounded, the cable having a fixed length, and wherein the substrate processing apparatus further includes a circuit unit connected with the ground and the cable.

[0020] In one embodiment, the impedance of the circuit unit is adjusted to be lower than that of a harmonic component desired to be removed from harmonic components generated in the processing chamber.

[0021] In one embodiment, the impedance of the circuit unit is adjusted by comparing the harmonic component with the total impedance of the circuit unit and the cable.

[0022] In one embodiment, the total impedance of the circuit unit and the cable is adjusted to be in a range of about 50Ω to 1000Ω.

[0023] In one embodiment, the circuit unit includes a variable device, and the impedance of the circuit unit is adjusted by adjusting the variable device.

[0024] In one embodiment, the variable device includes at least one of a variable capacitor, a variable inductor, a variable resistor, or a combination thereof.

[0025] A substrate processing method of generating plasma in a processing chamber using another embodiment of the inventive concept is provided.

[0026] The method adjusts a length of the cable to remove a harmonic component generated in the processing chamber.

[0027] In one embodiment, the length of the cable is adjusted such that the cable has an impedance in a range of about 50Ω to 1000Ω.

[0028] The method removes a harmonic component in the processing chamber by adjusting an impedance of a variable device of the circuit unit.

[0029] In one embodiment, the impedance of the variable device is adjusted such that a total impedance of the circuit unit and the cable is about 50Ω to 1000Ω.

[0030] According to the present inventive concept, the harmonics generated in the plasma processing can be controlled by the length adjustment of the cable.

[0031] According to another embodiment of the present inventive concept, the harmonics generated in the plasma processing can be controlled by adjusting a circuit unit connected to the cable.

[0032] According to the present inventive concept, the etching rate of the center region of the substrate can be controlled.

[0033] Effects of the present inventive concept are not limited to what has been described expressly above and will be understood by those skilled in the art from the foregoing description and the accompanying drawings that effects not expressly described can be included. BRIEF DESCRIPTION OF DRAWINGS

[0034] The above and other objects and features will become apparent from the following description, taken in conjunction with the accompanying drawings, wherein like reference numerals refer to like elements throughout the various figures, and wherein:

[0035] Figures la-lb An exemplary diagram illustrates a substrate processing apparatus according to an embodiment of the present inventive concept;

[0036] Figure 2 is an enlarged block diagram of a substrate processing apparatus according to an embodiment of the present inventive concept;

[0037] Figure 3 illustrates calculating the impedance of the cable;

[0038] Figure 4 illustrates adjusting the etching rate ER of the center region according to the change in the f3 MHz component impedance |Z| of the cable;

[0039] Figure 5 An exemplary diagram illustrates a substrate processing apparatus according to another embodiment of the present inventive concept;

[0040] Figures 6a-6b illustrates a configuration of a circuit unit according to an embodiment of the present inventive concept. DETAILED DESCRIPTION

[0041] The present inventive concept can be modified variously and can have various forms, and a specific embodiment thereof will be illustrated in the accompanying drawings and described in detail. However, the embodiments according to the present inventive concept are not intended to limit the forms specifically disclosed, and it should be understood that the present inventive concept includes all modifications, equivalents, and substitutions included in the spirit and technical scope of the present inventive concept. In the description of the present inventive concept, detailed description of the related known technology can be omitted when it can obscure the essence of the present inventive concept.

[0042] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the inventive concept. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises", "comprising", "includes" and / or "including", when used herein, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. In addition, the term "exemplary" is intended to refer to an example or illustration.

[0043] It will be understood that, although the terms "first", "second", "third", etc. can be used herein to describe various elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another region, layer or section. Therefore, the first element, component, region, layer or section discussed below can be called the second element, component, region, layer or section without departing from the teachings of the inventive concept. As used herein, a "~ unit" and a "~ module" can refer to an appliance for processing at least one function or operation, and can refer to, for example, a software or hardware component, such as an FPGA or an ASIC. However, the "~ unit" and the "~ module" can not be limited to software or hardware. The "~ unit" and the "~ module" can be configured to reside on an addressable storage medium and can be configured to reproduce one or more processors. In one example, the "~ unit" and the "~ module" can refer to, for example, a software component, an object-oriented software component, a class component, and a task component, a process, a function, an attribute, a program, a subroutine, a program code segment, a driver, firmware, a microcode, a circuit, data, a database, a data structure, a table, an array, and a variable. A plurality of components, a plurality of "~ units" or a plurality of "~ modules" can be used to perform the functions provided by the components, "~ units" or "~ modules" in a separate manner. The components, "~ units" or "~ modules" can be integrated with additional components.

[0044] Hereinafter, embodiments of the inventive concept will be described in detail with reference to the accompanying drawings.

[0045] Figures la-lb A substrate processing apparatus 10 according to an embodiment of the inventive concept is illustrated.

[0046] Reference Figure laThe substrate processing apparatus 10 processes the substrate W using plasma. For example, the substrate processing apparatus 10 can perform an etching process on the substrate W. The substrate processing apparatus 10 includes a chamber 100, a substrate support unit 200, a gas supply unit 300, a plasma generation unit 400, and a heating unit 500.

[0047] An inner space 101 is defined in the chamber 100. The inner space 101 serves as a space for plasma processing of the substrate W. The plasma processing on the substrate W includes an etching process. An exhaust port 102 is formed in a bottom portion of the chamber 100. The exhaust port 102 is connected to an exhaust line 121. Reaction byproducts generated during a process and gas remaining in the chamber 100 can be exhausted to the outside through the exhaust line 121. The inner space 101 of the chamber 100 is depressurized to a predetermined pressure through an exhaust process.

[0048] The substrate support unit 200 is located inside the chamber 100. The substrate support unit 200 supports the substrate W. The substrate support unit 200 includes an electrostatic chuck for adsorbing and fixing the substrate W using electrostatic force. The substrate support unit 200 can include a dielectric plate 210, a lower electrode 220, a heater 230, a support plate 240, and an insulating plate 270.

[0049] The dielectric plate 210 is located at an upper end of the substrate support unit 200. The dielectric plate 210 serves as a circular dielectric plate. The substrate W can be disposed on a top surface of the dielectric plate 210. A diameter of the top surface of the dielectric plate 210 is smaller than the substrate W. Accordingly, an edge region of the substrate W is located outside the dielectric plate 210. A first supply passage 211 is formed in the dielectric plate 210. The first supply passage 211 extends from the top surface to the bottom surface of the dielectric plate 210. A plurality of first supply passages 211 are spaced apart from each other and serve as passages for supplying a heat transfer medium to the bottom surface of the substrate W. A separate electrode for adsorbing the substrate W to the dielectric plate 210 can be embedded in the dielectric plate 210. A direct current can be applied to the electrode. Under the applied current, electrostatic force acts between the electrode and the substrate, so that the substrate W can be adsorbed to the dielectric plate 210 by the electrostatic force.

[0050] The lower electrode 220 is connected to a lower power supply unit 221. The lower power supply unit 221 supplies power to the lower electrode 220. The lower power supply unit 221 includes lower RF power supplies 222 and 223 and a lower impedance matching unit 225. As shown in FIG. 1, a plurality of lower RF power supplies 222 and 223 can be provided, or only one lower RF power supply 222 and 223 can be provided. The lower RF power supplies 222 and 223 can control a plasma density. The lower RF power supplies 222 and 223 mainly control ion bombardment energy. The plurality of lower RF power supplies 222 and 223 can respectively generate frequency power of 2 MHz and 13.56 Hz. The lower impedance matching unit 225 is electrically connected with the lower RF power supplies 222 and 223, and matches the frequency power of different magnitudes with each other and applies the matched frequency power to the lower electrode 220.

[0051] The heater 230 is electrically connected to an external power source (not shown). The heater 230 generates heat by resisting an electric current applied from the external power source. The generated heat is transferred to the substrate W via the dielectric plate 210. The substrate W is maintained at a predetermined temperature using the heat generated by the heater 230. The heater 230 includes a coil having a spiral shape. The heater 230 can be embedded in the dielectric plate 210 and spaced apart from each other by a uniform pitch.

[0052] The support plate 240 is located below the dielectric plate 210. The bottom surface of the dielectric plate 210 and the top surface of the support plate 240 can be combined with each other by an adhesive 236. The support plate 240 can be made of an aluminum material. The top surface of the support plate 240 can be stepped such that a central region thereof is higher than an edge region thereof. The central region of the top surface of the support plate 240 has an area corresponding to that of the bottom surface of the dielectric plate 210, and is adhered to the bottom surface of the dielectric plate 210. First circulation passages 241, second circulation passages 241 circulation passages 242, and a second supply passage 243 are formed in the support plate 240.

[0053] The first circulation passages 241 serve as passages through which a heat transfer medium is circulated. The first circulation passages 241 can be formed in a spiral shape and located inside the support plate 240. Alternatively, the first circulation passages 241 can be configured such that annular passages having different radii can be arranged around the same center. The first circulation passages 241 can be in communication with each other. The first circulation passages 241 can be located at the same vertical height.

[0054] The second circulation passages 242 serve as passages through which a cooling fluid circulates. The second circulation passages 242 can be formed in a spiral shape and located inside the support plate 240. Alternatively, the second circulation passages 242 can be configured such that annular passages having different radii can be arranged around the same center. The second circulation passages 242 can communicate with each other. The second circulation passages 242 can have a larger cross-sectional area than that of the first circulation passages 241. The second circulation passages 242 can be located at the same vertical height. The second circulation passages 242 can be located below the first circulation passages 241.

[0055] The second supply passages 243 extend upward from the first circulation passages 241 and to the top surface of the support plate 240. A plurality of second supply passages 243 are provided such that the number thereof corresponds to that of the first supply passages 211. The second supply passages 243 connect the first circulation passages 241 and the first supply passages 211 to each other.

[0056] The first circulation passages 241 are connected to a heat transfer medium storage unit 252 via a heat transfer medium supply line 251. A heat transfer medium is stored in the heat transfer medium storage unit 252. The heat transfer medium includes an inert gas. According to one embodiment, the heat transfer medium includes helium. The helium is supplied to the first circulation passages 241 through the supply line 251 and sequentially flows through the second supply passages 243 and the first supply passages 211 and then is supplied to the bottom surface of the substrate W. The helium serves as a medium that transfers heat transferred from a plasma to the substrate W to the substrate support unit 200. Ion particles included in the plasma are attracted and travel to the substrate support unit 200 using electric power generated in the substrate support unit 200 and collide with the substrate W during the travel to perform an etching process. When the ion particles collide with the substrate W, heat is generated in the substrate W. The heat generated from the substrate W is transferred to the substrate support unit 200 through the helium supplied to the space between the bottom surface of the substrate W and the top surface of the dielectric plate 210. Accordingly, the substrate W can be maintained at a set temperature.

[0057] The second circulation passages 242 are connected to a cooling fluid storage unit 262 via a cooling fluid supply line 261. A cooling fluid is stored in the cooling fluid storage unit 262. A cooler 263 can be provided inside the cooling fluid storage unit 262. The cooler 263 cools the cooling fluid to a predetermined temperature. Alternatively, the cooler 263 can be installed on the cooling fluid supply line 261. The cooling fluid supplied to the second circulation passages 242 through the cooling fluid supply line 261 circulates along the second circulation passages 242 and cools the support plate 240. The cooling of the support plate 240 cools the dielectric plate 210 and the substrate W together to maintain the substrate W at a predetermined temperature.

[0058] An electrically insulating plate 270 is disposed below the support plate 240. The electrically insulating plate 270 has a size corresponding to that of the support plate 240. The electrically insulating plate 270 is located between the support plate 240 and the bottom surface of the chamber 100. The electrically insulating plate 270 is made of an insulating material and electrically insulates the support plate 240 and the chamber 100 from each other.

[0059] An edge ring 280 is disposed in the edge region of the substrate support unit 200. The edge ring 280 has a ring shape and extends along the periphery of the dielectric plate 210. The top surface of the edge ring 280 can be stepped such that its outer portion 280a can be higher than its inner portion 280b. The inner portion 280b of the top surface of the edge ring 280 is located at the same vertical level as the top surface of the dielectric plate 210. The inner portion 280b of the top surface of the edge ring 280 supports the edge region of the substrate W located outside the dielectric plate 210. The outer portion 280a of the edge ring 280 is provided to surround the edge region of the substrate W. The edge ring 280 extends the electric field formation region such that the substrate W is located at the center of the plasma generation region. Thus, plasma is uniformly generated over the entire region of the substrate W such that the region of the substrate W can be uniformly etched. A coupling ring (not shown) can be disposed below the edge ring 280. The cable 600 can be connected to the coupling ring (not shown in FIG. 1) via one end thereof. The opposite end of the cable 600 can be grounded. In one embodiment, the cable 600 can be a variable cable having a variable length. According to another embodiment, the length of the cable 600 can be fixed, in which case a circuit unit (not shown in FIG. 1) capable of controlling the cable impedance can be further provided. In the exemplary embodiment according to the inventive concept, the impedance of the cable connected to the coupling ring can be controlled, for example, by controlling its length and / or the control circuit unit, to remove the harmonics generated by the RF power source. This will be described later with reference to FIG. 6. Figure 2 This will be described in detail.

[0060] A gas supply unit 300 supplies a process gas to the chamber 100. The gas supply unit 300 includes a gas storage unit 310, a gas supply line 320, and a gas inlet 330. The gas supply line 320 connects the gas storage unit 310 and the gas inlet 330 to each other and supplies the process gas stored in the gas storage unit 310 to the gas inlet 330. The gas inlet 330 is connected to the gas supply hole 412 formed in the upper electrode 410.

[0061] A plasma generation unit 400 excites the process gas left inside the chamber 100. The plasma generation unit 400 includes the upper electrode 410, a distribution plate 420, and an upper power supply unit 440.

[0062] The upper electrode 410 has a disk shape and is located above the substrate support unit 200. The upper electrode 410 includes an upper plate 410a and a lower plate 410b. The upper plate 410a has a disk shape. The upper plate 410a is electrically connected to an upper RF power source 441. The upper plate 410a excites a process gas by applying first RF power generated by the upper RF power source 441 to the process gas remaining in the chamber 100. The process gas is excited and converted into a plasma state. A bottom surface of the upper plate 410a is stepped such that a central region thereof is higher than an edge region thereof. A gas supply hole 412 is formed in the central region of the upper plate 410a. The gas supply hole 412 is connected to the gas inlet 330 and supplies the process gas to a buffer space 414. A cooling passage 411 can be formed inside the upper plate 410a. The cooling passage 411 can be formed in a spiral shape. Alternatively, the cooling passage 411 can be configured such that annular passages having different radii can be arranged around the same center. The cooling passage 411 is connected to a cooling fluid storage unit 432 via a cooling fluid supply line 431. Cooling fluid is stored in the cooling fluid storage unit 432. The cooling fluid stored in the cooling fluid storage unit 432 is supplied to the cooling passage 411 via the cooling fluid supply line 431. The cooling fluid circulates through the cooling passage 411 and cools the upper plate 410a.

[0063] The lower plate 410b is located below the upper plate 410a. The lower plate 410b has a size corresponding to that of the upper plate 410a and is positioned to face the upper plate 410a. A top surface of the lower plate 410b is stepped such that a central region thereof is lower than an edge region thereof. The top surface of the lower plate 410b and the bottom surface of the upper plate 410a are combined with each other to form the buffer space 414. The buffer space 414 serves as a space in which gas supplied through the gas supply hole 412 temporarily stays before being supplied to the chamber 100. A plurality of gas supply holes 413 are formed in the central region of the lower plate 410b. The plurality of gas supply holes 413 are arranged and spaced apart from each other at regular intervals. The gas supply holes 413 are connected to the buffer space 414.

[0064] The distribution plate 420 is located below the lower plate 410b. The distribution plate 420 has a disk shape. Distribution holes 421 are formed in the distribution plate 420. The distribution holes 421 extend from a top surface to a bottom surface of the distribution plate 420. The number of the distribution holes 421 corresponds to that of the gas supply holes 413, and the distribution holes 421 are respectively located at positions corresponding to positions at which the gas supply holes 413 are located. The process gas staying in the buffer space 414 is uniformly supplied into the chamber 100 through the gas supply holes 413 and the distribution holes 421.

[0065] The upper power source unit 440 applies RF power to the upper plate 410a. The upper power source unit 440 includes the upper RF power source 441 and a matching circuit 442.

[0066] The heating unit 500 heats the lower plate 410b. The heating unit 500 includes a heater 510, a second upper power supply 520, and a filter 530. The heater 510 is installed inside the lower plate 410b. The heater 510 can be disposed in an edge area of the lower plate 410b. The heater 510 can include a heating coil and can be disposed to surround a central area of the lower plate 410b. The second upper power supply 520 is electrically connected to the heater 510. The second upper power supply 520 can generate DC power. Alternatively, the second upper power supply 520 can generate AC power. Second frequency power generated by the second upper power supply 520 is applied to the heater 510, and the heater 510 generates heat by resisting the applied current. The heat generated by the heater 510 heats the lower plate 410b, and the heated lower plate 410b heats the distribution plate 420 located below the lower plate 410b to a predetermined temperature. The lower plate 420 can be heated to a temperature of about 60°C. The filter 530 is electrically connected to and disposed between the second upper power supply 520 and the heater 510.

[0067] Figure lb A substrate processing apparatus 10 according to another embodiment of the present inventive concept is illustrated.

[0068] Description of configurations repeated with respect to the embodiments of the substrate processing apparatus 10 will be omitted. Figure la Figure lb Description of configurations repeated with respect to the embodiments of the substrate processing apparatus 10 will be omitted.

[0069] According to the embodiments of the substrate processing apparatus 10, Figure lb According to the embodiments of the substrate processing apparatus 10,

[0070] In one embodiment, two of the three lower power supplies 222, 223, and 224 can be a first frequency power supply 222 and a second frequency power supply 223 having a frequency of 10 MHz or less, and the other lower power supply can be a third frequency power supply 224 having a frequency of 10 MHz or more. The first frequency power supply 222 and the second frequency power supply 223 can control ion bombardment energy, and the third frequency power supply 224 can control plasma density. The upper electrode 410 can be grounded.

[0071] However, the number of power supplies in the embodiment illustrated in FIG. 1 is limited. Figure la Figure lb The present inventive concept is not limited thereto and can be implemented only as an embodiment.

[0072] Figure 2 A substrate processing apparatus according to an embodiment of the present inventive concept is illustrated. ​​

[0073] The support unit 200 according to the inventive concept can include an edge ring 280 surrounding the substrate W and a coupling ring 290 disposed below the edge ring 280. Insulators 281 and 282 can be included between the edge ring 280 and the coupling ring 290. In the Figure 2 embodiment, two insulators 281 and 282 are provided, but the two can be combined into one insulator.

[0074] An electrode 291 can be included within the coupling ring 290. One end of a cable 600 can be connected to the electrode 291 included within the coupling ring 290. The opposite end of the cable 600 can be grounded. The cable 600 can provide an impedance path for an RF signal of an input RF signal in an edge region of the substrate W to ground. The RF signal can flow to the electrode 291 using a capacitance between the edge ring 280 and the electrode 291. The electrode 291 can output the RF signal.

[0075] As Figure 2 shown, the cable 600 can be provided in the form of a variable cable having a length that is adjustable. Although Figure 2 not shown in the drawings, the cable 600 can further include a length adjusting means capable of adjusting the length of the cable. According to another embodiment, the cable 600 can have a fixed length. By adjusting the length of the cable 600, the impedance of the cable 600 can be adjusted. By adjusting the impedance of the cable to a constant value, a target harmonic component among harmonic components generated in the process chamber can be selectively removed.

[0076] According to one embodiment, the cable 600 can be adjusted to have a length that can remove harmonics of a frequency of about 100 MHz or more. This is because the plasma density concentration of the central region is greatly affected at a frequency of about 100 MHz or more.

[0077] According to the inventive concept, the electrode 291 can be embedded inside the coupling ring 290 located below the edge ring 280, and the electrode 291 and the ground can be connected to each other through the cable 600 to remove only harmonics of plasma passing from the process chamber to the ground. According to the inventive concept, when connected to the electrode 291 included inside the coupling ring 290 located below, plasma uniformity can be controlled by setting the length of the cable 600 to remove harmonics. The length of the cable 600 can be set in advance by calculation before being connected to the electrode 291. Alternatively, a variable cable having a length that can be changed can be used to change the length of the cable 600 during processing.

[0078] In one embodiment, if the impedance of the grounded cable is lower than the impedance of the harmonic, the harmonic in the process chamber can be removed to the ground through the cable. Removing the harmonic can allow the high plasma density in the center region of the substrate W and thus the high etching rate to be suppressed. According to one embodiment, the impedance of the cable (cable impedance) can be adjusted to a value of about 50Ω to 1000Ω for all harmonics. The length of the cable can be adjusted to eliminate all harmonics. According to one embodiment, the length of the cable can be adjusted so that the cable 600 has an impedance of about 200Ω or less. According to one embodiment, the length of the cable can be adjusted so that the cable 600 has an impedance in the range of about 50Ω to 1000Ω.

[0079] That is, the length of the cable according to the embodiment of the inventive concept can be provided as a fixed length by pre-calculation, or the cable can be provided as a variable length cable so that the length of the cable can be changed in real time according to the application frequency of the RF signal.

[0080] Hereinafter, adjusting the impedance of the cable by adjusting the length of the cable will be described in more detail.

[0081] Figure 3 Calculating the impedance of the cable is shown.

[0082] In the case of a coaxial cable, the impedance Z in of the cable varies according to the length of the cable and the frequency. The impedance Z in of the cable can be represented by the following equation.

[0083]

[0084] In the above equation, Z in is the impedance of the cable, Z L is the impedance of the load connected to the cable, β is the propagation constant, and Z0is the characteristic impedance of the cable. According to one embodiment, the characteristic impedance Z0of the cable can be 50Ω. In this case, the propagation constant has a relationship of β = 2πf / cη (where f is the frequency, c is the propagation speed in a vacuum, and η is a velocity factor (VF) determined by the characteristics of the cable), and varies according to the frequency f.

[0085] As Figure 2 shown, when the opposite end of the cable is directly grounded, the load impedance Z L = 0, and thus the impedance of the cable can be represented as follows. Z in = j50tan(βl)

[0086] That is, the impedance of the cable can be adjusted according to the applied frequency and the length of the cable.

[0087] According to one embodiment, when the frequency of the RF power source is f1 MHz, the frequencies of the harmonics include f2(=f1X 2) MHz, f3(f1 X 3) MHz, f4(f1 X 4) MHz,...., and f n (f1 x n) MHz (which is an integer multiple of f1 MHz). Here, f1 can be 10 MHz or more, and the frequency of the harmonics can be 100 MHz or more. In this case, the cable impedance can be calculated based on the length of the cable and the speed factor η.

[0088] f (MHz) | Z | (Ω) f1 ​ f2 [Z2(< < Z1)] f3 [Z3(< Z1)] f4 [Z4(<< Z1)]

[0089] According to Table 1, f2 MHz and f4 MHz harmonics, which cause asymmetry of the plasma, can be removed by grounding, while maintaining a high impedance to suppress the loss of f1 MHz passing through the cable by the RF power application. In Table 1, f1, f2, f3, and f4 can be 60 MHz, 120 MHz, 180 MHz, and 240 MHz, respectively, Z1, Z2, Z3, and Z4 can be 2124 Ω, 2 Ω, 707 Ω, and 5 Ω, respectively, the length of the cable can be 2.9 m, and η can be 0.77.

[0090] When the plasma is severely asymmetric due to f2 MHz and f4 MHz harmonics, such a cable length can be used. When the plasma in the central region is severely asymmetric due to f3 MHz harmonics, the cable length can be adjusted so that the cable has a low impedance to f3 MHz.

[0091] That is, according to the inventive concept, since the plasma density in the central region of the substrate due to the harmonics is controlled according to the length of the cable, the etching rate in the central region of the substrate can be controlled by replacing the cable or using a cable of a variable length.

[0092] Figure 4 It is shown that the etching rate ER in the central region of the substrate is adjusted according to the change in the impedance |Z| of the cable for f3 MHz harmonics.

[0093] Referring to Figure 4 , it is shown that the etching rate in the central region of the substrate can be changed by adjusting the impedance |Z| for f3 MHz harmonics.

[0094] Figure 5 A substrate processing apparatus according to another embodiment of the inventive concept is shown.

[0095] According to Figure 5In an embodiment, the cable 600 can further include a circuit unit 700. The circuit unit 700 can be connected between the cable 600 and the ground. According to an embodiment, when the cable 600 connected to the electrode 291 is a variable cable capable of length adjustment, since the impedance of the cable can be adjusted by adjusting the length of the variable cable, the circuit unit 700 connected to the variable cable can be configured to have an auxiliary function, such as suppressing heat generation or preventing loss of the main RF frequency, rather than a main function of controlling the impedance of the cable. However, the circuit unit 700 can have a function of controlling the impedance of the cable.

[0096] Figures 6a-6b A configuration of the circuit unit 700 according to an embodiment of the inventive concept is illustrated.

[0097] Referring to Figure 6a , the circuit unit 700 includes a resistor R. When the circuit unit 700 includes the resistor R, heat generation due to high current can be suppressed.

[0098] Referring to Figure 6b , the circuit unit 700 includes an inductor, a capacitor, and a resistor. The inductor and the capacitor are combined to function as a filter circuit, which can prevent the main RF frequency from being transmitted to the ground regardless of the length of the cable. According to an embodiment, the filter circuit can be a band pass filter BPF or a low pass filter LPF. According to an embodiment, the filter circuit can be a high pass filter HPF. According to another embodiment, the filter circuit can include a combination of a high pass filter HPF, a band pass filter BPF, and / or a low pass filter LPF.

[0099] However, Figures 6a-6b The configuration illustrated in FIG. 7 is just an embodiment, and the circuit unit 700 according to the inventive concept can be provided to have the above-described functions through various combinations of an inductor, a capacitor, and a resistor. The configuration illustrated in FIG. 7. Figures 6a-6b The configuration illustrated in FIG. 7 can be an exemplary configuration of a circuit unit connected to a variable cable whose length can vary according to an embodiment.

[0100] However, according to another embodiment of the inventive concept, the cable 600 can be provided as a cable having a fixed length. In the case where the circuit unit is connected to a cable having a fixed length, since the impedance of the fixed cable varies only with frequency, the circuit unit connected to the cable having a fixed length can control the impedance of the cable when a desired impedance cannot be achieved through frequency control. That is, when there is a limitation in the configuration of the length of the cable, the impedance can be compensated for by the circuit unit.

[0101] At this time, the circuit unit is provided to include at least one of a variable resistor, a variable capacitor, a variable inductor, or a combination thereof, so that the impedance can be adjusted by adjusting the variable device.

[0102] Even in the case of the circuit unit connected to the cable having a fixed length, a resistor and / or a filter circuit serving as an auxiliary function can be included, for example, the circuit unit connected to the variable cable. However, in the case of the circuit unit connected to the cable having a fixed length, it can include a variable element capable of adjusting the impedance in addition to the circuit performing the auxiliary function. That is, in the case of such an embodiment, the impedance control can be performed by adjusting the variable element included in the circuit without replacing the cable.

[0103] That is, in this case, the impedance of the circuit unit can be controlled by comparing the total impedance of the impedance adjusted by the circuit unit and the impedance of the cable having a fixed length with the harmonic generated in the process chamber. According to one embodiment, the variable element included in the circuit unit can be controlled so that the total impedance of the impedance adjusted by the circuit unit and the impedance of the cable having a fixed length is in the range of about 50Ω to 1000Ω.

[0104] In addition, according to another embodiment of the present inventive concept, if the impedance TTTM between facilities is desired by compensating for the deviation between the cables, the impedance can be controlled by the circuit unit to achieve the cable impedance TTTM.

[0105] That is, the circuit unit 700 connected to the cable 600 according to the present inventive concept can include an overcurrent prevention circuit, a main RF frequency block filter, a variable impedance control circuit, a harmonic block filter, a harmonic transmission filter, etc., and / or a combination thereof.

[0106] That is, according to one embodiment of the present inventive concept, the plasma asymmetry can be suppressed by selecting the cable length so that the cable has a low impedance for the harmonic to be removed and connecting the cable between the electrode and the ground to eliminate the target harmonic to the ground. Alternatively, the target harmonic can be removed to the ground by changing the cable length in real time.

[0107] According to another embodiment of the present inventive concept, when the length of the cable cannot be changed, the plasma asymmetry can be suppressed by additionally controlling the impedance to be low via the circuit unit to remove the target harmonic to the ground.

[0108] Further, the circuit unit 700 according to the present inventive concept can further include an impedance control circuit for controlling a sheath voltage in the edge region. Accordingly, the sheath voltage of the edge region can be controlled in real time, and initial setting of the plasma density in the center region can be performed. Accordingly, the sheath voltage and ion tilt of the edge region can be controlled.

[0109] Further, the circuit unit 700 according to the present inventive concept can further include an impedance control circuit for sheath voltage control in the edge region and an impedance control circuit for harmonic control, thereby simultaneously controlling the sheath voltage and ion tilt in the edge region and controlling the harmonics and plasma density in the center region.

[0110] According to another embodiment of the present inventive concept, when the etching rate in the center region is low, in addition to removing the harmonics, the plasma asymmetry can be compensated for and controlled by amplifying or adjusting the harmonics according to the chamber. Thereby, the etching rate in the entire region can be uniformly adjusted.

[0111] Effects of the present inventive concept are not limited to what has been described hereinabove merely by way of example, and it should be understood by those skilled in the art that other effects which have not been described hereinabove can be derived from the above description and the accompanying drawings.

[0112] While the preferred embodiments of the present inventive concept have been illustrated and described above, the present inventive concept is not limited to the aforementioned specific embodiments, and it should be appreciated that those skilled in the art to which the present inventive concept pertains can implement the present inventive concept in various ways without departing from the essential characteristics of the present inventive concept claimed in the claims, and such modifications should not be interpreted as being separated from the technical spirit or prospect of the present inventive concept.

Claims

1. A substrate processing apparatus comprising: a processing chamber having a processing space therein; a support unit for supporting a substrate in the processing space; a gas supply unit for supplying a processing gas into the processing space; and an RF power source for providing an RF signal to excite the processing gas into a plasma state, wherein the support unit comprises: an edge ring surrounding the substrate; a coupling ring disposed below the edge ring and including an electrode therein; a cable having one end connected to the electrode and an opposite end grounded; and a circuit unit connected between the cable and the ground, wherein the circuit unit comprises: a first impedance control circuit for controlling a sheath voltage at an edge region of the substrate; and a second impedance control circuit for controlling a harmonic component, wherein the first impedance control circuit controls ion tilt at the edge region of the substrate to adjust an etching rate in the edge region of the substrate, and wherein a length of the cable is set based on Z in = wherein the second impedance control circuit controls a plasma density and adjusts an etching rate in a central region of the substrate through harmonic control with the cable. o tan( βl ) such that a harmonic component of 100 MHz or higher frequency among harmonics generated in the processing chamber by the RF power source has a low impedance of 50 Ω to 1000 Ω, while a fundamental frequency of the RF power source has a high impedance greater than the low impedance to suppress a loss of the RF signal applied by the RF power source through the cable, wherein Z in is an impedance of the cable, Z o is a characteristic impedance of the cable, l is a length of the cable, β is a propagation constant, wherein β = 2πf / cη, where f is a frequency, c is a propagation speed in vacuum, and η is a speed factor determined by characteristics of the cable.

2. The substrate processing apparatus according to claim 1, wherein the cable is disposed to be variable in length.

3. The substrate processing apparatus according to claim 1, wherein the second impedance control circuit includes a resistor connected in series with the cable.

4. The substrate processing apparatus according to claim 1, wherein the second impedance control circuit includes a filter circuit that passes only a specific wavelength.

5. The substrate processing apparatus according to claim 4, wherein the filter circuit includes at least one of a bandpass filter, a lowpass filter, a highpass filter, or a combination thereof.

6. The substrate processing apparatus according to claim 5, wherein the filter circuit is any one of the bandpass filter, the highpass filter, or a combination of the bandpass filter and the highpass filter.

7. A substrate processing apparatus comprising: a processing chamber having a processing space therein; a support unit for supporting a substrate in the processing space; a gas supply unit for supplying a processing gas into the processing space; and an RF power source for providing an RF signal to excite the processing gas into a plasma state, wherein the support unit comprises: an edge ring surrounding the substrate; a coupling ring disposed below the edge ring and including an electrode therein; and a cable having one end connected to the electrode and an opposite end grounded, the cable having a fixed length, and wherein the substrate processing apparatus further comprises a circuit unit connected between the ground and the cable, wherein the circuit unit comprises: a first impedance control circuit for controlling a sheath voltage at an edge region of the substrate; and a second impedance control circuit for controlling a harmonic component, wherein the first impedance control circuit controls ion tilt at the edge region of the substrate to adjust an etching rate in the edge region of the substrate, and wherein the second impedance control circuit controls a plasma density and adjusts an etching rate in a central region of the substrate through harmonic control with the cable. ​ wherein an impedance of the second impedance control circuit is adjusted based on such that the second impedance control circuit and the cable have a low total impedance of 50 Ω to 1000 Ω for harmonic components of 100 MHz or higher frequencies in harmonics generated in the process chamber by the RF power source, while having a high total impedance greater than the low total impedance for a fundamental frequency of the RF power source to suppress a loss of the RF signal applied by the RF power source through the cable, wherein Z in is an impedance of the cable, Z L is an impedance of the circuit unit, Z o is a characteristic impedance of the cable, l is a length of the cable, β is a propagation constant, wherein β = 2πf / cη, wherein f is a frequency, c is a propagation speed in vacuum, and η is a speed factor determined by characteristics of the cable, wherein the first impedance control circuit controls ion skew at the edge region of the substrate to adjust an etch rate in the edge region of the substrate, and wherein the second impedance control circuit controls plasma density through harmonic control with the cable and adjusts an etch rate in a center region of the substrate.

8. The substrate processing apparatus of claim 7, wherein the impedance of the second impedance control circuit is adjusted by comparing the harmonic component to the low total impedance of the second impedance control circuit and the cable.

9. The substrate processing apparatus of claim 7, wherein the second impedance control circuit comprises a variable device.

10. The substrate processing apparatus of claim 9, wherein the impedance of the second impedance control circuit is adjusted by adjusting the variable device.

11. The substrate processing apparatus of claim 10, wherein the variable device comprises at least one of a variable capacitor, a variable inductor, a variable resistor, or a combination thereof.

12. A substrate processing method using the substrate processing apparatus of claim 1, the substrate processing method comprising adjusting a length of the cable to remove a harmonic component within the processing chamber.

13. The substrate processing method of claim 12, wherein the length of the cable is adjusted such that the cable has a low impedance in a range of 50 Ω to 1000 Ω.

14. A substrate processing method using the substrate processing apparatus of claim 7, the substrate processing method comprising removing the harmonic component within the processing chamber by adjusting an impedance of a variable device of the second impedance control circuit.

15. The substrate processing method of claim 14, wherein the impedance of the variable device is adjusted such that a low total impedance of the second impedance control circuit and the cable is 50 Ω to 1000 Ω.

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