Method and apparatus for controlling power provided to load

Abstract

Disclosed in the present disclosure is a plasma generation apparatus for generating plasma. In particular, the plasma generation apparatus may comprise: a discharging tube that provides a plasma generation space; an antenna disposed to surround the outer wall of the discharging tube; an inverter which includes two input terminals for receiving a direct current voltage from a DC power source, two output terminals for supplying an alternating current voltage to the antenna, and four switches, and which converts the direct current voltage to the alternating current voltage according to operation of the four switches; and a controller that controls the operation of the four switches.

Description

Method for controlling power supplied to a load and device therefor

[0001] The present disclosure relates to a method for controlling power supplied to a load and a device therefor. More specifically, the present disclosure relates to a method for controlling the magnitude of an alternating current flowing to a load according to changes in the impedance of the variable load, thereby preventing damage to the load and power supply device, and to a device therefor for efficiently controlling the impedance of a variable load.

[0002] Technologies utilizing plasma are being used in a variety of industrial fields, including semiconductor, display, and medical equipment technologies, as well as environmental technologies such as air, water, and soil purification, and energy technologies such as solar cells and hydrogen energy.

[0003] There are many ways to generate such plasma, including direct current discharges such as corona discharge, glow discharge, and arc discharge, alternating current discharges such as capacitive coupled discharge and inductive coupled discharge, shock waves, and high-energy beams. Among them, the inductive coupling method, which is highly versatile due to its simple structure, is attracting attention.

[0004] Meanwhile, efficient plasma generation requires efficient control of the amount of power supplied to the load that generates the plasma. For example, to ignite plasma, a high current must be applied to the load to form an electromagnetic field. However, if the current is too high, it can damage the load and the power supply used to supply the current. Furthermore, as the amount of generated plasma increases, the load's impedance also increases. Therefore, maintaining the plasma after ignition requires a higher current than before.

[0005] Accordingly, a method is required to provide an appropriate current according to the load impedance that changes due to plasma generation.

[0006] The present disclosure seeks to provide a method for controlling power provided to a load and a device therefor.

[0007] The problem that the present disclosure seeks to solve is to provide a method and a device for preventing damage to a load and an inverter that may occur due to an excessively high magnitude of an alternating current flowing to a load by a voltage applied from an inverter.

[0008] The problem to be solved by the present disclosure is to provide a method and a device therefor that enable an appropriate current to flow to a load for igniting and maintaining plasma according to the impedance of the load that changes before and after plasma ignition.

[0009] The problems to be solved by the present disclosure are not limited to the problems described above, and problems not mentioned can be clearly understood by a person having ordinary skill in the technical field corresponding to the present disclosure from this specification and the attached drawings.

[0010] According to the present disclosure, a plasma generating device for generating plasma comprises: a discharging tube providing a space for generating the plasma; an antenna disposed to surround an outer wall of the discharging tube; An inverter having two input terminals for receiving a DC voltage from a DC power source, wherein the two input terminals are a first input terminal and a second input terminal, two output terminals for applying an AC voltage to the antenna, wherein the two output terminals are a first output terminal and a second output terminal, and four switches, wherein the four switches are composed of a first switch electrically interposed between the first input terminal and the first output terminal, a second switch electrically interposed between the second input terminal and the first output terminal, a third switch electrically interposed between the first input terminal and the second output terminal, and a fourth switch electrically interposed between the second input terminal and the second output terminal, and converting the DC voltage into the AC voltage according to the operation of the four switches; and a controller that controls the operation of the four switches.

[0011] Meanwhile, the controller may control the operation of the first switch to be turned on and the operation of the second switch to be turned off so that the DC voltage is converted into a first AC voltage, while controlling the operation of each of the third switch and the fourth switch to be selectively turned on or off, and determine whether the plasma is generated in the discharge tube in an amount greater than or equal to a reference amount by the first AC voltage applied to the antenna, and may control the operation of each of the first switch, the second switch, the third switch, and the fourth switch to be selectively turned on or off based on the generated plasma being greater than or equal to the reference amount so that the DC voltage is converted into a second AC voltage.

[0012] In one embodiment of the present disclosure, a control method for controlling four switches included in an inverter of a plasma generating device, wherein the inverter has a first switch electrically interposed between a first input terminal and a first output terminal, a second switch electrically interposed between a second input terminal and the first output terminal, a third switch electrically interposed between the first input terminal and the second output terminal, and a fourth switch electrically interposed between the second input terminal and the second output terminal, wherein the first input terminal and the second input terminal receive a DC voltage from a DC power source, and the first output terminal and the second output terminal can apply an AC voltage to an antenna arranged to surround an outer wall of a discharge tube.

[0013] Meanwhile, the control method may include: controlling the operation of the first switch to be turned on and the operation of the second switch to be turned off so that the DC voltage is converted into a first AC voltage, while controlling the operation of each of the third switch and the fourth switch to be selectively turned on or off; determining whether the plasma has been generated inside the discharge tube in an amount greater than or equal to a reference amount by the first AC voltage applied to the antenna; and controlling the operation of each of the first switch, the second switch, the third switch, and the fourth switch to be selectively turned on or off so that the DC voltage is converted into a second AC voltage based on whether the generated plasma is greater than or equal to the reference amount.

[0014] According to one embodiment of the present disclosure, damage that may be inflicted on the inverter and antenna structure due to high current can be minimized.

[0015] Additionally, according to one embodiment of the present disclosure, it is possible to supply appropriate power to efficiently ignite and maintain plasma before and after ignition of the plasma.

[0016] The effects according to the present disclosure are not limited to the effects described above, and effects not mentioned can be clearly understood by a person having ordinary skill in the art to which the present invention pertains from the present disclosure and the attached drawings.

[0017] FIG. 1 is a drawing showing a plasma induction device according to the present disclosure.

[0018] FIG. 2 is a drawing of an RF (Radio Frequency) generator according to the present disclosure.

[0019] FIGS. 3 to 5 are drawings for explaining an inverter structure included in an RF generator according to embodiments of the present disclosure.

[0020] FIG. 6 is a drawing showing an antenna structure according to the present disclosure.

[0021] FIGS. 7 and 8 are drawings showing a process of inducing plasma according to an embodiment of the present disclosure.

[0022] FIGS. 9 and 10 are drawings for explaining a method for converting a direct current voltage into an alternating current voltage by controlling four switches included in an inverter by a controller according to an embodiment of the present disclosure.

[0023] FIGS. 11 to 13 are drawings for explaining a method for a controller to control four switches included in an inverter so that a high current does not flow to a load according to an embodiment of the present disclosure.

[0024] FIGS. 14 and 15 are drawings for explaining a method for changing an operation mode for controlling four switches included in an inverter according to an embodiment of the present disclosure.

[0025] FIG. 16 is a drawing for explaining a method for determining whether an operation mode for controlling four switches included in an inverter has changed according to an embodiment of the present disclosure.

[0026] FIGS. 17 to 20 are drawings for explaining various forms of operation flows of a plasma induction device according to an embodiment of the present disclosure.

[0027] FIGS. 21 to 23 are for explaining a power control method using a freewheeling section in an operation mode according to an embodiment of the present disclosure.

[0028] FIGS. 24 and 25 are for explaining a power control method using a freewheeling section in another operation mode according to an embodiment of the present disclosure.

[0029] Figures 26 and 27 are for explaining the configuration of a half-bridge inverter.

[0030] FIGS. 28 to 31 are for explaining a method of controlling power using a half-bridge inverter according to an embodiment of the present disclosure.

[0031] Figure 32 is intended to explain various examples of setting a freewheeling section in the above-described operation mode.

[0032] The above-described purposes, features, and advantages of the present disclosure will become more apparent through the following detailed description taken in conjunction with the accompanying drawings. However, since the present disclosure is susceptible to various modifications and various embodiments, specific embodiments will be illustrated in the drawings and described in detail below.

[0033] Since the embodiments described in this specification are intended to clearly explain the spirit of the present disclosure to a person having ordinary skill in the art to which the present disclosure pertains, the present disclosure is not limited to the embodiments described in this specification, and the scope of the present disclosure should be interpreted to include modified or altered examples that do not depart from the spirit of the present disclosure.

[0034] The drawings attached to this specification are intended to facilitate explanation of the present disclosure, and the shapes depicted in the drawings may be exaggerated as necessary to help understanding of the present disclosure, and thus the present disclosure is not limited by the drawings.

[0035] If a detailed description of a known function or configuration related to this disclosure is deemed to unnecessarily obscure the gist of this disclosure, such detailed description will be omitted. Furthermore, numbers (e.g., "first," "second," etc.) used throughout the description of this specification are merely identifiers used to distinguish one component from another.

[0036] In addition, the suffixes "unit," "module," and "part" used for components in the description below are given or used interchangeably only for the convenience of writing the specification, and do not have distinct meanings or roles in themselves.

[0037]

[0038] According to the present disclosure, a plasma generating device for generating plasma comprises: a discharging tube providing a space for generating the plasma; an antenna disposed to surround an outer wall of the discharging tube; An inverter having two input terminals for receiving a DC voltage from a DC power source, wherein the two input terminals are a first input terminal and a second input terminal, two output terminals for applying an AC voltage to the antenna, wherein the two output terminals are a first output terminal and a second output terminal, and four switches, wherein the four switches are composed of a first switch electrically interposed between the first input terminal and the first output terminal, a second switch electrically interposed between the second input terminal and the first output terminal, a third switch electrically interposed between the first input terminal and the second output terminal, and a fourth switch electrically interposed between the second input terminal and the second output terminal, and converting the DC voltage into the AC voltage according to the operation of the four switches; and a controller that controls the operation of the four switches.

[0039] Meanwhile, the controller may control the operation of the first switch to be turned on and the operation of the second switch to be turned off so that the DC voltage is converted into a first AC voltage, while controlling the operation of each of the third switch and the fourth switch to be selectively turned on or off, and determine whether the plasma is generated in the discharge tube in an amount greater than or equal to a reference amount by the first AC voltage applied to the antenna, and may control the operation of each of the first switch, the second switch, the third switch, and the fourth switch to be selectively turned on or off based on the generated plasma being greater than or equal to the reference amount so that the DC voltage is converted into a second AC voltage.

[0040] Additionally, the controller can control the operations of the first switch, the second switch, the third switch, and the fourth switch so that the second AC voltage is applied to the antenna and the generated plasma is maintained.

[0041] Additionally, the difference between the maximum and minimum values ​​of the second AC voltage may be twice the difference between the maximum and minimum values ​​of the first AC voltage.

[0042] Additionally, the controller can determine that the generated plasma is greater than or equal to the reference amount based on the fact that the amount of power applied to the inverter is less than the first threshold value.

[0043] Additionally, the controller can calculate the amount of power using the DC voltage applied to the inverter and the input current flowing to the inverter.

[0044] In addition, the controller may assume a virtual signal in which a control signal controlling at least one of the four switches is shifted by a predetermined time, determine a delay time between the output current of the inverter and the virtual signal, and determine that the generated plasma is greater than or equal to the reference amount if the delay time is less than or equal to a reference value.

[0045] Additionally, the controller can control the operation of each of the third switch and the fourth switch so that the delay time exceeds the reference value when the inverter applies the first AC voltage to the antenna.

[0046] In one embodiment of the present disclosure, a control method for controlling four switches included in an inverter of a plasma generating device, wherein the inverter has a first switch electrically interposed between a first input terminal and a first output terminal, a second switch electrically interposed between a second input terminal and the first output terminal, a third switch electrically interposed between the first input terminal and the second output terminal, and a fourth switch electrically interposed between the second input terminal and the second output terminal, wherein the first input terminal and the second input terminal receive a DC voltage from a DC power source, and the first output terminal and the second output terminal can apply an AC voltage to an antenna arranged to surround an outer wall of a discharge tube.

[0047] Meanwhile, the control method may include: controlling the operation of the first switch to be turned on and the operation of the second switch to be turned off so that the DC voltage is converted into a first AC voltage, while controlling the operation of each of the third switch and the fourth switch to be selectively turned on or off; determining whether the plasma has been generated inside the discharge tube in an amount greater than or equal to a reference amount by the first AC voltage applied to the antenna; and controlling the operation of each of the first switch, the second switch, the third switch, and the fourth switch to be selectively turned on or off so that the DC voltage is converted into a second AC voltage based on whether the generated plasma is greater than or equal to the reference amount.

[0048] At this time, the operation of each of the first switch, the second switch, the third switch, and the fourth switch is controlled to be selectively turned on or off; may include: controlling the operation of the first switch, the second switch, the third switch, and the fourth switch so that the second AC voltage is applied to the antenna and the generated plasma is maintained.

[0049] Additionally, the difference between the maximum and minimum values ​​of the second AC voltage may be twice the difference between the maximum and minimum values ​​of the first AC voltage.

[0050] In addition, determining whether the plasma is generated to a reference amount may include determining that the generated plasma is greater than or equal to the reference amount based on whether the amount of power applied to the inverter is less than or equal to a first threshold value.

[0051] In addition, determining whether the plasma is generated in a reference amount may further include calculating the amount of power using the DC voltage applied to the inverter and the input current flowing to the inverter.

[0052] In addition, determining whether the plasma is generated in a reference amount may include: assuming a virtual signal in which a control signal controlling at least one of the four switches is shifted by a predetermined time; determining a delay time between the output current of the inverter and the virtual signal; and determining that the generated plasma is greater than or equal to the reference amount if the delay time is less than or equal to a reference value.

[0053] In addition, the operation of the first switch is controlled to be turned on and the operation of the second switch is turned off, while the operation of each of the third switch and the fourth switch is selectively turned on or off; may include controlling the operation of each of the third switch and the fourth switch so that the delay time exceeds the reference value.

[0054]

[0055] [Glossary]

[0056] The present disclosure relates to a plasma induction device for inducing plasma, and more specifically, to a plasma induction device for a plasma process, which can increase stability and durability by not causing damage or malfunction of the plasma induction device due to induced current generated from a plurality of antennas disposed in the plasma induction device.

[0057] In the present disclosure, the plasma process refers to a process of generating and utilizing plasma, and is used in semiconductor processes, display processes, nano processes, environmental improvement, etc. In the present disclosure, for convenience of explanation, semiconductor processes such as plasma ashing, plasma CVD (chemical vapor deposition), plasma etching, thin film deposition (sputtering), and surface modification are described as main examples of plasma processes, but the technical idea of ​​the present disclosure is not limited thereto.

[0058] Plasma is a state (phase) in which matter is separated into negatively charged electrons and positively charged ions by applying high energy, and can be induced or generated in various ways.

[0059] There are many methods for generating plasma, but among them, inductively coupled plasma (ICP) is a plasma that is induced by supplying power to a coil or antenna, thereby forming an induced electric field or capacitive electric field in a specific space, and can generally be driven by a high-frequency power source such as radio frequency (RF).

[0060] An antenna structure may refer to an object that, including the aforementioned antenna, receives power and forms an inductive or capacitive electric field for plasma generation. The antenna structure may be designed in various ways depending on the purpose and specifications of the plasma induction system, and the shape and structure of the antenna structure can significantly affect the efficiency and durability of the plasma induction system.

[0061]

[0062] [Plasma Generator]

[0063] Hereinafter, a plasma generation device and its configuration will be described with reference to Fig. 1.

[0064] FIG. 1 is a drawing showing a plasma generation device (100) according to one embodiment.

[0065] Referring to FIG. 1, a plasma generation device (100) may include an RF generator (1000), an antenna structure (2000), and a discharge tube (3000).

[0066] The RF generator (1000) can provide power to the antenna structure (2000). For example, the RF generator (1000) can apply AC power having a specific driving frequency to the antenna structure (2000). Here, AC power can be understood to mean AC current or AC voltage.

[0067] The RF generator (1000) can monitor the impedance of the antenna structure (2000) and / or the power applied to the antenna structure (2000). Specifically, the RF generator (1000) can obtain information about the current or voltage flowing in the antenna structure (2000), as described below.

[0068] The RF generator (1000) can change the driving frequency of the AC power provided to the antenna structure (2000). The RF generator (1000) can change the driving frequency of the AC power provided based on the impedance of the antenna structure (2000) and / or the power applied to the antenna structure (2000).

[0069] The antenna structure (2000) may be electrically connected to the RF generator (1000). For example, one end of the RF generator (1000) may be electrically connected to one end of the antenna structure (2000), and the other end of the RF generator (1000) may be electrically connected to the other end of the antenna structure (2000). The RF generator (1000) may also be electrically connected to the antenna structure (2000) through a separate electrical component.

[0070] In the present disclosure, one end or the other end refers to an end portion of an object, but is not limited to referring only to the end portion of the object or necessarily including the end portion. For example, electrical connection between one end of an antenna structure (2000) and one end of an RF generator (1000) may mean that one end portion of the antenna structure (2000) or a portion adjacent to the end portion is connected to one terminal of the RF generator (1000) via a conductor such as a wire. In addition, one end or the other end may refer to an end portion of a portion of an object, which may be understood as an end portion of the portion, a portion including the end portion, or a portion spaced apart from the end portion by a predetermined distance.

[0071] As described above, one end or the other end is an expression to indicate a part of an object, and the expression itself does not limit the structure or properties of the object, or the connection relationship between the objects. For example, as described below, when an antenna structure (2000) is composed of a plurality of antenna segments and one end of one antenna segment is connected to the other end of another antenna segment, the two antenna segments may be formed integrally or may be implemented in a physically separate form.

[0072] The antenna structure (2000) can form an electromagnetic field inside the discharge tube (3000) to induce plasma generation. For example, the antenna structure (2000) can receive power from an RF generator (1000) to form an electromagnetic field inside the discharge tube (3000) to induce plasma generation. More specifically, the direction of the electromagnetic field formed inside the discharge tube (3000) by the antenna structure (2000) is periodically changed due to the AC power supplied by the RF generator (1000), and the gas supplied inside the discharge tube (3000) is supplied with energy by the electromagnetic field that changes according to the period and undergoes a phase transition into plasma.

[0073] The antenna structure (2000) may basically have a ring shape or coil-like shape that surrounds the outer surface of the discharge tube (or dielectric tube).

[0074] However, it may have a special structure engineered to generate plasma and maintain plasma density even when high frequency and high power are supplied to the antenna structure for plasma formation.

[0075] The antenna structure (2000) may have a layered structure. For example, it may have a structure in which identical or very similar structures are stacked in the longitudinal direction of a discharge tube (or dielectric tube).

[0076] One layer of the antenna structure (2000) may be composed of multiple turns. For example, one layer of the antenna structure (2000) may be composed of at least one turn. For example, one layer of the antenna structure (2000) may be composed of one, two, three, or more turns.

[0077] The antenna structure (2000) may include at least one capacitive element. For example, a plurality of antennas constituting the antenna structure (2000) may be electrically connected by the capacitive element. In addition, the antenna structure (2000) may further include a capacitive element for connecting to the RF generator (1000).

[0078] Meanwhile, the capacitive element described in the present disclosure may mean a capacitor, a capacitor, a multilayer ceramic capacitor, an ultracapacitor, or an equivalent circuit of a capacitive element having a function of storing electric energy.

[0079] The discharge tube (3000) can create an environment for generating plasma. For example, the discharge tube (3000) can define an internal space in which plasma is generated.

[0080] The discharge tube (3000) can provide a space where plasma generation is induced. The discharge tube (3000) can have a pipe shape (or a hollow cylindrical shape). However, the shape of the discharge tube (3000) is not limited to a pipe shape, and any shape including an internal space for generating plasma is sufficient. Meanwhile, in the present specification, the generation of plasma can mean that plasma is induced or plasma generation is induced inside the discharge tube (3000). That is, plasma can be generated by inducing plasma or plasma generation by utilizing an electromagnetic field generated by an alternating current flowing in an antenna structure (2000) surrounding the outer wall of the discharge tube (3000).

[0081] A gas (e.g., NF3, Ar, CO2, CH4, O2, He, and / or H2) for plasma generation can be introduced into the discharge tube (3000). For example, the discharge tube (3000) is fluidly connected to at least one gas storage unit, and gas can be introduced from the gas storage unit into the discharge tube (3000) through a mass flow controller (MFC).

[0082] The discharge tube (3000) can be made of various materials. For example, the discharge tube (3000) can be made of a non-conductor or a material with high thermal conductivity. Specifically, the discharge tube (3000) can be made of aluminum nitride (AlN), aluminum oxide (Al2O3), silicon nitride (SiN), silicon nitride (Si3N4), silicon dioxide (SiO2), yttrium oxide (Y2O3), or silicon carbide (SiC). Furthermore, the discharge tube (3000) can be made of a material that does not generate impurities (particles) by reacting with a gas introduced into the discharge tube (3000) to induce plasma.

[0083] The discharge tube (3000) may be fluidly connected to a process chamber. Here, the process chamber may be understood as a chamber defining a space where a plasma process takes place and into which products (e.g., active species, etc.) generated in the discharge tube (3000) are introduced. For example, the discharge tube (3000) and the process chamber may be connected via a conduit, and fluid may flow from the discharge tube (3000) to the process chamber via the conduit.

[0084] The internal environment of the discharge tube (3000) can be controlled. Specifically, the temperature or pressure within the discharge tube (3000) can be controlled to have an appropriate value or maintained within a certain range for plasma generation. To this end, the discharge tube (3000) may include a temperature control unit such as a heating wire or a thermoelectric element. In addition, the discharge tube (3000) may include a gas discharge unit for controlling the internal pressure.

[0085] Below, the RF generator (1000) and antenna structure (2000) described above will be described in more detail.

[0086]

[0087] [Structure of RF generator]

[0088] [1] Overall structure of the RF generator

[0089] Below, the configuration and structure of the RF generator (1000) are described with reference to FIG. 2.

[0090] FIG. 2 is a drawing of an RF generator (1000) according to one embodiment of the present specification.

[0091] Referring to FIG. 2, an RF generator (1000) may include an AC power source (1100), a rectifier (1200), an inverter (1300), a controller (1500), and a sensor (1400). The RF generator (1000) may convert AC supplied from the AC power source (1100) into another AC and supply it to a load. For example, the RF generator (1000) may convert AC used in typical households or industries into another AC having a frequency of several hundred kHz to several tens of MHz and a power of several kW or more and supply it to a load.

[0092] Meanwhile, the RF generator (1000) and the load may be electrically and / or physically connected by one or more nodes. Referring to FIG. 2, two nodes (1610, 1630) on the RF generator (1000) side and two nodes (1710, 1730) on the load side may be electrically and / or physically connected. For example, node (1610) may be connected to node (1710), and node (1630) may be connected to node (1730). For example, node (1610) may be connected to node (1710) with one conductor, and node (1630) and node (1730) may be connected with another conductor.

[0093] Meanwhile, nodes (1610, 1630, 1710, 1730) may also be implemented in the form of terminals. In this case, the terminal of node (1610) and the terminal of node (1710) may be connected by wires, cables, or connectors, and the terminal of node (1630) and the unit price of node (1730) may be connected by wires, cables, or connectors.

[0094] Hereinafter, for convenience of explanation, it is assumed and explained that the RF generator (1000) and the load are connected through nodes (1610, 1630, 1710, 1730). That is, for convenience of explanation, the configurations of the nodes (1610, 1630, 1710, 1730) may be omitted from the drawing or may be omitted from the specific description of the specification, but it can be easily inferred from the above description and a person skilled in the art that the RF generator (1000) and the load are connected through nodes (1610, 1630, 1710, 1730).

[0095] Here, the load may include an antenna structure (2000) and plasma generated by the antenna structure (2000). At this time, the impedance of the load becomes a composite impedance of the impedance of the antenna structure (2000) and the impedance of the plasma, and since the impedance of the plasma varies with time depending on the state of the plasma, the load has a resonant frequency that varies with time depending on the plasma induction.

[0096] The rectifier (1200) can convert the output of the AC power source (1100) into DC. The rectifier (1200) can convert the AC supplied from the AC power source (1100) into DC and apply it to both ends of the inverter (1300) (e.g., input terminals of the inverter (1300)).

[0097] The inverter (1300) can receive direct current from the rectifier (1200) and supply alternating current to the load. For example, the inverter (1300) can receive a switch control signal from the controller (1500) and provide alternating current to the load using the received switch control signal. Here, the inverter (1300) can include at least one switch element controlled by the switch control signal. In addition, the switch control signal received from the controller (1500) can control the operation of at least one switch element. For example, at least one switch element can be turned on and / or turned off according to the switch control signal. Here, the switch element can refer to an element that constitutes a switch. For example, the switch element can include a transistor and a diode. For example, the switch element can refer to a transistor or a diode. In addition, the switch element can also refer to a transistor and a diode that are electrically connected. However, for the convenience of explanation, in this disclosure, a set of switching elements, in which transistors and diodes are electrically connected to perform the function of a switch, is referred to as a switch. A detailed description thereof will be provided later.

[0098] Meanwhile, the alternating current supplied to the load from the inverter (1300) may have a specific frequency (e.g., driving frequency) set based on a switch control signal provided to the inverter (1300) from the controller (1500).

[0099] Meanwhile, a capacitive element may be placed between the rectifier (1200) and the inverter (1300). For example, the RF generator (1000) includes a capacitor connected in parallel with the rectifier (1200) and the inverter (1300), and the capacitor can discharge the AC component of the voltage or current applied to the inverter (1300) to the ground node (GND).

[0100] The controller (1500) can receive sensed data from the sensor (1400) described below. In addition, the sensed data can be used to generate a switching control signal. For example, the controller (1500) can be implemented to obtain data related to a resonant frequency, such as a current and voltage of a load, from the sensor (1400) and generate a switching control signal. Specifically, the controller (1500) can obtain a phase signal of an output current of an inverter (1300) from the sensor (1400). Here, obtaining a phase signal of an output current can mean detecting / sensing a phase signal of an output current. Therefore, in the descriptions described below, “obtaining” can mean “sensing” or “detecting.”

[0101] The controller (1500) can generate a switch control signal for controlling the frequency of the AC voltage output from the inverter (1300) using the phase signal of the output current. For example, the controller (1500) can obtain a phase difference or delay time between the phase signal of the output current and the output voltage of the inverter (1300). Based on the obtained phase difference or delay time, a second switch control signal for outputting a second AC voltage having a second frequency can be generated and applied to the inverter (1300).

[0102] Meanwhile, for example, the controller (1500) may use a first switch control signal for outputting a first AC voltage having a first frequency from the inverter (1300) to obtain a phase signal of the output voltage. For example, the controller (1500) may assume a virtual signal obtained by shifting the first switch control signal by a predetermined time as the phase signal of the output voltage, and may obtain a phase difference or delay time between the virtual signal and the phase signal of the output current. Here, the first frequency and the second frequency may be the same or different. In addition, the controller (1500) may control the frequency of the AC voltage to be as close as possible to the resonant frequency of the load. At this time, the controller (1500) may obtain the phase difference or delay time of the output current and the output voltage at predetermined cycles, thereby controlling the frequency of the AC voltage.

[0103] Therefore, the first frequency described above may be the frequency of the first AC voltage applied to the load during the nth period, and the second frequency may be the frequency of the second AC voltage applied to the load during the (n+1)th period.

[0104] Meanwhile, the controller (1500) can control the amount of power output from the inverter (1300). For example, the controller (1500) can measure the power supplied to the load from the inverter (1300), and if the power supplied to the load is greater than a first reference value, the controller (1500) can generate a switch control signal and apply it to the inverter (1300) so that the power supplied to the load can be reduced.

[0105] For example, the first reference value may be a reference value set to avoid damage to the load or the inverter (1300), or may be a reference value set by the user for the operational efficiency of the plasma generation device (100). Alternatively, the first reference value may be a reference value set to not exceed the range of power for efficiently inducing / generating plasma. However, the present invention is not limited to the above-described example, and the first reference value may be set to achieve a specific purpose of the operation of the plasma generation device (100). In addition, the controller (1500) may measure the power supplied to the load from the inverter (1300), and if the power supplied to the load is less than the second reference value, generate a switch control signal to increase the power supplied to the load, and apply the switch control signal to the inverter (1300). For example, the second reference value may be set to prevent plasma from not being sufficiently induced or maintained in the load. However, the present invention is not limited to the above-described examples, and a second reference value may be set to achieve a specific purpose of the operation of the plasma generation device (100). In this case, the first reference value and the second reference value may be the same, or the second reference value may be lower than the first reference value.

[0106] The controller (1500) can be implemented using FPGA (Field Programmable Gate Array) technology. The specific configuration and structure of the controller (1500) will be described later.

[0107] The phase signal of the output current sensed from the sensor (1400) may be a signal or data regarding the direction of the output current applied to the load (i.e., output from the inverter (1300)) and the time for which the output current flows in each direction. That is, the wave of the output current may be a square wave signal as a digitized signal that measures the direction in which the current flows and the time for which the current flows in the corresponding direction.

[0108] The sensor (1400) can obtain data on the resonant frequency of the load or data on the current or power supplied to the load from the controller (1500). Referring again to FIG. 2, the sensor (1400) can include a current transformer (1410), a filter (1420), and a comparator (1430). The sensor (1400) can receive an AC current or voltage signal flowing in the load through the current transformer (1410), convert the AC current or voltage signal into a current or voltage signal of different magnitude, filter the converted current or voltage signal using the filter (1420), and output a phase signal of the output current to the controller (1500) through the comparator (1430).

[0109] Here, the current transformer (1410) can be inductively coupled to the wiring between the inverter (1300) and the load and can convert a voltage or current signal applied to the load and provide it to the filter (1420). Specifically, the current transformer (1410) can convert a current flowing in a wire connected to the load into a voltage signal.

[0110] Here, the filter (1420) can remove high-frequency noise from the input current or voltage signal and output it to the comparator (1430). To this end, the filter (1420) can perform high-pass filtering or low-pass filtering.

[0111] Here, the phase signal of the output current can be obtained through the comparator (1430). For example, the comparator (1430) can be used to obtain the phase signal of the output current by comparing the voltage signal obtained from the current transformer (1410) or the filter (1420) with a preset value. At this time, the phase signal can mean phase data of the output current applied to the load (i.e., output from the inverter (1300)) or data regarding the magnitude and direction of the current.

[0112] At least one of the components included in the above-described sensor (1400) may be omitted.

[0113] Although not shown in FIG. 2, the RF generator (1000) may include memory.

[0114] Here, the memory can store various types of data. Various types of data can be stored in the memory temporarily or semi-permanently. Examples of the memory may include a hard disk drive (HDD), a solid state drive (SSD), flash memory, read-only memory (ROM), random access memory (RAM), etc. The memory may be provided in a form built into the RF generator (1000) or in a detachable form.

[0115] As described above, the RF generator (1000) can control the frequency of the AC provided to the load and / or the power provided to the load. In other words, the RF generator (1000) can track the resonant frequency of the load, which changes according to the change in the state of the plasma, control the frequency of the output AC to correspond to the resonant frequency of the load, and output the AC having the controlled frequency. In addition, the RF generator (1000) can calculate the amount of power required according to the change in the state of the plasma and determine the time and section at which the AC is output. This can prevent unnecessary power consumption and improve the durability of the plasma system.

[0116] The RF generator (1000) described above may omit at least one of its components. For example, the RF generator (1000) may not include a sensor (1400) and may acquire electrical data about a load from an external sensor. For another example, the RF generator (1000) may not include an AC power source (1100) and a rectifier (1200) and may receive direct current or rectified direct current from an external source.

[0117]

[0118] [2] Structure of inverter (1300)

[0119] FIG. 3 is a drawing for explaining the configuration of an inverter (1300) according to an embodiment of the present disclosure. The inverter (1300) according to an embodiment of the present disclosure may be implemented as a full bridge inverter.

[0120] Specifically, the inverter (1300) may include four switches (S1, S2, S3, S4). As described above, each switch represents a set of transistors and diodes electrically connected. As shown in Fig. 3, the transistors and diodes are electrically connected in parallel, and a configuration in which transistors and diodes are electrically connected in parallel can be defined as a switch.

[0121] Hereinafter, for convenience of explanation, a switch in which a transistor and a diode are electrically connected in parallel is expressed as in Fig. 4.

[0122] Referring to Fig. 4, a form in which a transistor and a diode are electrically connected in parallel is expressed as a switch. Referring to Fig. 4, the inverter (1300) includes four switches (S1, S2, S3, S4).

[0123] In addition, the inverter (1300) may include two input nodes (1650, 1670) and two output nodes (1610, 1630). In addition, the two input nodes (1650, 1670) may be implemented in the form of input terminals. Similarly, the two output nodes (1610, 1630) may be implemented in the form of output terminals. Hereinafter, for convenience, the two input nodes (1650, 1670) will be expressed as two input terminals (1650, 1670) in the specification of the present disclosure. Similarly, the two output nodes (1610, 1630) will be expressed as two output terminals (1610, 1630).

[0124] Two input terminals (1650, 1670) are connected to a rectifier (1200), and the inverter can receive a direct current voltage from the rectifier (1200) through the two input terminals (1650, 1670). In addition, two output terminals (1610, 1630) are connected to terminals (1710, 1730) of a load, and the inverter can apply an alternating current voltage to the load through the two output terminals (1610, 1630).

[0125] Meanwhile, one of the two input terminals (1650, 1670) can be connected to GND. GND is to provide a reference voltage (Vref). If GND is earth ground, it can be a reference of 0V. Alternatively, GND can be chassis ground or signal ground, in which case the reference voltage can be 0V, but can also have a value other than 0V.

[0126] Referring again to FIG. 4, switch S1 may be electrically interposed between input terminal (1650) and output terminal (1610). Switch S2 may be electrically interposed between input terminal (1670) and output terminal (1610). Switch S3 may be electrically interposed between input terminal (1670) and output terminal (1630). Switch S4 may be electrically interposed between input terminal (1650) and output terminal (1630).

[0127] That is, each switch can be electrically interposed between one input terminal and one output terminal, and only one switch can be electrically interposed between one input terminal and one output terminal.

[0128] Figure 5 is for explaining the turn-on operation and turn-off operation of the switch.

[0129] When the controller (1500) applies a switch control signal to the inverter (1300), each switch is selectively turned on or off depending on the value of the switch control signal. For example, when the switch control signal input to the switch has a high level, the switch can be turned on. On the other hand, when the switch control signal input to the switch has a low level, the switch can be turned off.

[0130] Fig. 5 shows that switches S1 and S3 are turned off, and switches S2 and S4 are turned on. In the turned-on state, it means that the circuit is electrically connected through the turned-on switch, and current can flow through the turned-on switch. On the other hand, in the turned-off state, it means that the turned-off switch is open, and the circuit is not electrically connected, and current cannot flow through the turned-off switch. For example, in Fig. 5, current flows through switches S2 and S4, but no current flows through switches S1 and S3.

[0131]

[0132] [Antenna structure]

[0133] Below, the antenna structure (2200) is described in detail with reference to FIG. 6.

[0134] FIG. 6 is a drawing showing an antenna structure (2000) according to one embodiment.

[0135] Referring to FIG. 6, the antenna structure (2000) may include an ignition antenna structure (2100) and a maintenance antenna structure (2200). The ignition antenna structure (2100) may be understood as an antenna module for igniting plasma, and the maintenance antenna structure (2200) may be understood as an antenna module for maintaining the ignited plasma. The process of igniting and maintaining the plasma will be described later.

[0136] The ignition antenna structure (2100) can be arranged around the discharge tube (3000) based on the central axis of the discharge tube (3000). The ignition antenna structure (2100) can be implemented in a coil-like shape or ring shape that surrounds the outer surface of the discharge tube (3000).

[0137] The ignition antenna structure (2100) may have a layered structure. The ignition antenna structure (2100) may have a structure in which identical or similar structures are stacked in the longitudinal direction of the discharge tube (3000). For example, as illustrated in FIG. 3, the ignition antenna structure (2100) may have a two-layer structure including two layer antennas. It should be understood that the number of layers of the ignition antenna structure (2100) is not limited to two layers and may be appropriately determined as needed.

[0138] One layer of the ignition antenna structure (2100) may be composed of multiple turns. For example, as illustrated in FIG. 6, the ignition antenna structure (2100) may be composed of two turn antennas, i.e., an inner turn antenna that surrounds the outer surface of the discharge tube (3000) and an outer turn antenna that surrounds the inner turn antenna. The number of turns constituting each layer of the ignition antenna structure (2100) is not limited to two turns and may be appropriately determined as needed.

[0139] The maintenance antenna structure (2200) can be arranged around the discharge tube (3000) based on the central axis of the discharge tube (3000). The maintenance antenna structure (2200) can be implemented in a coil-like shape or ring shape that surrounds the outer surface of the discharge tube (3000).

[0140] The sustain antenna structure (2200) may have a layered structure. The sustain antenna structure (2200) may have a structure in which identical or similar structures are laminated in the longitudinal direction of the discharge tube (3000). For example, as illustrated in FIG. 6, the sustain antenna structure (2200) may have a seven-layer structure. The number of layers of the sustain antenna structure (2200) is not limited to seven layers and may be appropriately determined as needed.

[0141] One layer of the sustain antenna structure (2200) may be composed of multiple turns. For example, as illustrated in FIG. 6, the sustain antenna structure (2200) may be composed of two turn antennas, i.e., an inner turn antenna that surrounds the outer surface of the discharge tube (3000) and an outer turn antenna that surrounds the inner turn antenna. The number of turns constituting each layer of the sustain antenna structure (2200) is not limited to two turns and may be appropriately determined as needed.

[0142] The sustain antenna structure (2200) may include at least one capacitive element. For example, the capacitive element may be electrically interposed between a plurality of antennas constituting the sustain antenna structure (2200). Specifically, when the sustain antenna structure (2200) includes a plurality of layer antennas, each layer antenna including a plurality of turn antennas, the capacitive element may be electrically interposed between the plurality of layer antennas and / or between the plurality of turn antennas.

[0143] Here, the capacitive element may mean an element having the function of storing electric energy, such as a capacitor, a multilayer ceramic capacitor, or an ultracapacitor, or an equivalent circuit thereof.

[0144] Unlike the sustain antenna structure (2200), the ignition antenna structure (2100) may not include capacitive elements between the plurality of layer antennas and / or between the plurality of turn antennas, even if each layer antenna includes a plurality of turn antennas. This is because when a capacitive element is included in the antenna module, the voltage applied to both ends of the antenna module becomes relatively low, whereas a relatively high voltage must be applied to the ignition antenna structure (2100) during the plasma induction process, as described below. Of course, the ignition antenna structure (2100) may include a capacitive element, and the sustain antenna structure (2200) may not include a capacitive element.

[0145] The ignition antenna structure (2100) and the sustaining antenna structure (2200) may be arranged around the discharge tube (3000) at a predetermined distance apart from each other. For example, as illustrated in FIG. 3, the sustaining antenna structure (2200) may be arranged at a predetermined distance apart from the ignition antenna structure (2100) in the longitudinal direction of the discharge tube (3000).

[0146] Meanwhile, the energy conversion efficiency (ECE) may vary depending on the shape of the maintenance antenna structure (2200). Here, the energy conversion efficiency may refer to the degree to which gases supplied to the discharge tube (3000) are converted into synthetic gas through plasma reforming.

[0147] Meanwhile, the ignition antenna structure (2100) and the maintenance antenna structure (2200) may be connected to one or more RF generators (1000). For example, the ignition antenna structure (2100) and the maintenance antenna structure (2200) may be connected to the same RF generator (1000). At this time, the frequency of the RF generator (1000) when applying an AC voltage to the ignition antenna structure (2100) and the frequency of the RF generator (1000) when applying an AC voltage to the maintenance antenna structure (2200) may be the same or different.

[0148] Additionally, one RF generator (1000) can supply an AC voltage to the ignition antenna structure (2100) and the sustaining antenna structure (2200) simultaneously. One RF generator (1000) and the ignition antenna structure (2100) can be electrically connected in series, and the sustaining antenna structure (2200) and one RF generator (1000) can be electrically connected in series. At the same time, the ignition antenna structure (2100) and the sustaining antenna structure (2200) can be electrically connected in parallel.

[0149] Meanwhile, the ignition antenna structure (2100) and the sustaining antenna structure (2200) may be connected to two RF generators (1001, 1002) (see FIG. 7). The ignition antenna structure (2100) may be connected to the first RF generator (1001), and the sustaining antenna structure (2200) may be connected to the second RF generator (1002). The first RF generator (1001) and the second RF generator (1002) may apply an AC voltage to the ignition antenna structure (2100) and the sustaining antenna structure (2200), respectively, and the time intervals during which the first RF generator (1001) and the second RF generator (1002) apply an AC voltage to the ignition antenna structure (2100) and the sustaining antenna structure (2200), respectively, are determined independently from each other, but at least some of them may overlap. For example, the first RF generator (1001) and the second RF generator (1002) may start applying AC voltage to the ignition antenna structure (2100) and the sustaining antenna structure (2200) at the same time, respectively, and the second RF generator (1002) may start applying AC voltage to the sustaining antenna structure (2200) after the first RF generator (1001) starts applying AC voltage to the ignition antenna structure (2100). Conversely, the first RF generator (1001) may start applying AC voltage to the ignition antenna structure (2100) after the second RF generator (1002) starts applying AC voltage to the sustaining antenna structure (2200).

[0150] Meanwhile, when the first RF generator (1001) ends applying the AC voltage to the ignition antenna structure (2100), the second RF generator (1002) may start applying the AC voltage to the sustaining antenna structure (2200), or the second RF generator (1002) may start applying the AC voltage to the sustaining antenna structure (2200) while the first RF generator (1001) is applying the AC voltage to the ignition antenna structure (2100). In addition, the first RF generator (1001) may start applying the AC voltage to the ignition antenna structure (2100) while the second RF generator (1002) is applying the AC voltage to the sustaining antenna structure (2200).

[0151] Meanwhile, unlike the configuration in FIG. 6, the plasma generating device (100) may be configured without an ignition antenna structure (2100). That is, a sustaining antenna structure (2200) may surround the outer wall of the discharge tube (3000), and the ignition antenna structure (2100) may be absent. In this case, the RF generator (1000) may be electrically connected in series to the sustaining antenna structure (2200).

[0152] Hereinafter, in this specification, a first embodiment in which an ignition antenna structure (2100) and a maintenance antenna structure (2200) are spaced apart and surround the outer wall of a discharge tube (3000) and a second embodiment in which a maintenance antenna structure (2200) surrounds the outer wall of a discharge tube (300) and the ignition antenna structure (2100) is not present are described separately.

[0153] Meanwhile, when explaining the first embodiment, for the convenience of explanation, it is assumed that the ignition antenna structure (2100) is electrically connected in series with the first RF generator (1001), and the sustaining antenna structure (2200) is electrically connected in series with the second RF generator (1002). However, it is not limited thereto, and it is obvious that the idea of ​​the present disclosure can be equally applied even when the ignition antenna structure (2100) and the sustaining antenna structure (2200) are connected to a single RF generator (1000).

[0154]

[0155] [Plasma generation / induction process]

[0156] Hereinafter, according to the first embodiment, the plasma generation / induction process when the ignition antenna structure (2100) and the maintenance antenna structure (2200) surround the outer wall of the discharge tube (3000) will be examined.

[0157] FIG. 7 is a diagram showing a process of generating / inducing plasma according to the first embodiment of the present disclosure.

[0158] Referring to FIG. 7, a plasma generation device (100) may include a discharge tube (3000) that provides a space where plasma is generated, an ignition antenna structure (2100) disposed around the discharge tube (3000), a maintenance antenna structure (2200), a first RF generator (1001) that applies power to the ignition antenna structure (2100), and a second RF generator (1002) that applies power to the maintenance antenna structure (2200). Meanwhile, the discharge tube (3000) may include an inlet (3100) for injecting an auxiliary gas and an outlet (3200) for processing the auxiliary gas and discharging it from the discharge tube (3000). Meanwhile, the auxiliary gas is a gas used for plasma generation and may also be referred to as a process gas.

[0159] The process of inducing plasma can be broadly divided into the plasma ignition process and the plasma maintaining process.

[0160] In the plasma ignition process, auxiliary gas is introduced into the discharge tube (3000) through the injection part (3100) of the discharge tube (3000), and when voltage is applied to the ignition antenna structure (2100) by the first RF generator (1001) to form an electric field (E1), the introduced auxiliary gas is accelerated by the electric field (E1) and undergoes a phase transition into plasma. In the plasma ignition process, the plasma transitions from the E mode, in which capacitive coupling is dominant, to the H mode, in which inductive coupling is dominant, as the electron density increases. For example, referring to FIG. 7, in the plasma ignition process, the plasma of the auxiliary gas can be generated / induced in the internal space of the discharge tube (3000) corresponding to the ignition antenna structure (2100), like the plasma (1) of FIG. 7.

[0161] Meanwhile, for example, during the plasma ignition process, when the first RF generator (1001) applies voltage to the ignition antenna structure (2100), the second RF generator (1002) may also apply voltage to the sustaining antenna structure (2200). Or, as another example, during the plasma ignition process, the first RF generator (1001) may apply voltage to the ignition antenna structure (2100), while the second RF generator (1002) may not apply voltage to the sustaining antenna structure (2200). However, during the plasma ignition process, the second RF generator (1002) may also apply voltage to the sustaining antenna structure (2200) after or simultaneously with the first RF generator (1001) applying voltage to the ignition antenna structure (2100). In some cases, the first RF generator (1001) may apply voltage to the ignition antenna structure (2100) after the second RF generator (1002) applies voltage to the sustain antenna structure (2200) during the plasma ignition process.

[0162] Meanwhile, it is to be noted in advance that the ignition antenna structure (2100) is an expression used to distinguish it from the maintenance antenna structure (2200) for convenience of explanation. The ignition antenna structure (2100) may also be referred to as a first antenna structure, which means any antenna structure.

[0163] A process for increasing the charge density inside the discharge tube (3000) may be additionally performed prior to the plasma ignition process, or a process for increasing the charge density inside the discharge tube (3000) may be additionally performed during the plasma ignition process. Specifically, a high voltage may be applied inside the discharge tube (3000) by applying a DC pulse voltage to an electrode attached to the discharge tube (3000). When a high voltage is applied inside the discharge tube (3000), electrons may be emitted from the electrode into the discharge tube (3000). In addition, the gas inside the discharge tube (3000) may be ionized due to the high voltage applied from the electrode. Accordingly, the charge density inside the discharge tube (3000) may be increased. If, prior to the ignition process, a DC pulse voltage is not applied to the electrode attached to the discharge tube (3000) to apply a high voltage inside the discharge tube (3000), or if the DC pulse voltage is not applied during the plasma ignition process and / or the plasma maintenance process described below, the electrode attached to the discharge tube (300) may be omitted from the plasma generation device (100).

[0164] During the plasma maintenance process, an alternating current is applied to the maintenance antenna structure (2200) by the second RF generator (1002), thereby generating a continuously changing magnetic field. When an induced electric field (E2) is formed according to the change in this magnetic field, particles in the H mode plasma state continuously move by the induced electric field (E2), so that the plasma can be stably maintained. Here, the movement of the plasma into the internal space of the discharge tube (3000) corresponding to the maintenance antenna structure (2200) means that the plasma (1) generated in the internal space of the discharge tube (3000) corresponding to the ignition antenna structure (2100), like the plasma (2) in FIG. 7, spreads to the internal space of the discharge tube (3000) corresponding to the maintenance antenna structure (2200). That is, the plasma (1) generated during the ignition process spreads during the plasma maintenance process and exists inside the discharge tube (3000) like the plasma (2).

[0165] Meanwhile, the maintenance antenna structure (2200) is an expression used to distinguish it from the ignition antenna structure (2100) for convenience of explanation. The maintenance antenna structure (2200) may be referred to as a second antenna structure, which refers to any antenna structure.

[0166] In other words, the process of inducing plasma can be understood as the ignition antenna structure (2100) and the first RF generator (1001) are used to cause the auxiliary gas to be in an E mode plasma state and then to be transferred to an H mode plasma state, and the maintenance antenna structure (2200) and the second RF generator (1002) are used to maintain the H mode plasma state.

[0167] Meanwhile, when the second RF generator (1002) applies voltage to the sustain antenna structure (2200) during the plasma sustain process, the first RF generator (1001) may also still apply voltage to the ignition antenna structure (2100). For example, after the second RF generator (1002) applies voltage to the sustain antenna structure (2200) during the plasma sustain process, when the plasma has completely moved toward the sustain antenna structure (2200) as in the plasma (2) of FIG. 7, the voltage supply of the first RF generator (1001) may be stopped.

[0168] At this time, when the auxiliary gas transitions from the E mode plasma state to the H mode plasma state, it can be said that the ignition of the plasma is completed. That is, in this specification, the completion of the ignition of the plasma can mean that the auxiliary gas transitions from the E mode plasma state to the H mode plasma state. Therefore, in this specification, after the ignition of the plasma is completed, an operation for maintaining the H mode plasma state can be performed. Meanwhile, in the E mode plasma state, the plasma can be transitioned to the H mode plasma state as the amount of plasma increases while continuously induced / generated. Therefore, when the ignition of the plasma is completed, the plasma generated inside the discharge tube (3000) can be greater than or equal to a reference amount. In other words, when the plasma is generated within the discharge tube (3000) in an amount greater than or equal to a reference amount, it can be determined that the ignition of the plasma is completed.

[0169] Hereinafter, according to the second embodiment, the plasma generation / induction process when the maintenance antenna structure (2200) surrounds the outer wall of the discharge tube (3000) will be examined.

[0170] FIG. 8 is a diagram showing a process of generating / inducing plasma according to a second embodiment of the present disclosure.

[0171] Referring to FIG. 8, a plasma generation device (100) may include a discharge tube (3000) that provides a space where plasma is generated, a maintenance antenna structure (2200) arranged around the discharge tube (3000), and an RF generator (1000) that applies power to the maintenance antenna structure (2200). Meanwhile, the discharge tube (3000) may include an inlet (3100) for injecting an auxiliary gas, and an outlet (3200) for processing the auxiliary gas and discharging it from the discharge tube (3000). Meanwhile, the auxiliary gas is a gas used for plasma generation and may also be referred to as a process gas.

[0172] In Fig. 8, the process of inducing plasma can be broadly divided into a plasma ignition process and a plasma maintaining process.

[0173] During the plasma ignition process, auxiliary gas is introduced into the discharge tube (3000) through the injection part (3100) of the discharge tube (3000), and when voltage is applied to the sustain antenna structure (2200) by the RF generator (1000) to form an electric field (E1), the introduced auxiliary gas is accelerated by the electric field (E1) and undergoes a phase transition into plasma. During the plasma ignition process, the plasma transitions from the E mode, in which capacitive coupling is dominant, to the H mode, in which inductive coupling is dominant, as the electron density increases. For example, referring to FIG. 8, during the plasma ignition process, plasma of the auxiliary gas can be generated / induced in the internal space of the discharge tube (3000) corresponding to the sustain antenna structure (2200).

[0174] A process for increasing the charge density inside the discharge tube (3000) may be additionally performed prior to the plasma ignition process, or a process for increasing the charge density inside the discharge tube (3000) may be additionally performed during the plasma ignition process. Specifically, a high voltage may be applied inside the discharge tube (3000) by applying a DC pulse voltage to an electrode attached to the discharge tube (3000). When a high voltage is applied inside the discharge tube (3000), electrons may be emitted from the electrode into the discharge tube (3000). In addition, the gas inside the discharge tube (3000) may be ionized due to the high voltage applied from the electrode. Accordingly, the charge density inside the discharge tube (3000) may be increased. If, prior to the ignition process, a DC pulse voltage is not applied to the electrode attached to the discharge tube (3000) to apply a high voltage inside the discharge tube (3000), or if the DC pulse voltage is not applied during the plasma ignition process and / or the plasma maintenance process described below, the electrode attached to the discharge tube (300) may be omitted from the plasma generation device (100).

[0175] During the plasma maintenance process, a magnetic field that continuously changes is generated by an alternating current flowing through the maintenance antenna structure (2200) by an RF generator (1000). When an induced electric field (E2) is formed according to this change in the magnetic field, the plasma can be stably maintained as particles in the H mode plasma state continuously move in the internal space of the discharge tube (3000) by the induced electric field (E2).

[0176] At this time, when the auxiliary gas transitions from the E mode plasma state to the H mode plasma state, it can be said that the ignition of the plasma is completed. That is, in this specification, the completion of the ignition of the plasma can mean that the auxiliary gas transitions from the E mode plasma state to the H mode plasma state. Therefore, in this specification, after the ignition of the plasma is completed, an operation for maintaining the H mode plasma state can be performed.

[0177]

[0178] [Previous Problems]

[0179] [1] Conventional inverter (1300) switch control method,

[0180] Fig. 9 shows an example in which a controller (1500) controls four switches (S1 to S4) included in an inverter (1300) through first to fourth switch control signals. In Fig. 9, the horizontal axes indicate time (T), the vertical axes indicate the first to fourth switch control signals and the output voltage (VO), and the unit of the vertical axes may be voltage (V). For convenience of explanation, the symbols corresponding to the first to fourth switch control signals are named as switches (S1 to S4) corresponding to the respective switch control signals. That is, in Fig. 9, S1 indicates a first switch control signal for controlling switch S1, S2 indicates a second switch control signal for controlling switch S2, and so on. Similarly, S3 indicates a third switch control signal for controlling switch S3, and S4 indicates a fourth switch control signal for controlling switch S4.

[0181] Referring to FIG. 9, the first and third switch control signals (S1, S3) can be controlled as a pair, and the second and fourth switch control signals (S2, S4) can be controlled as a pair. For example, when the first switch control signal (S1) has a high level, the third switch control signal (S3) can also have a high level. When the first switch control signal (S1) has a low level, the third switch control signal (S3) can also have a low level. Similarly, when the second switch control signal (S2) has a high level, the fourth switch control signal (S4) can also have a high level. When the second switch control signal (S2) has a low level, the fourth switch control signal (S4) can also have a low level.

[0182] For example, the first and third switch control signals (S1, S3) and the second and fourth switch control signals (S2, S4) can be complementarily controlled. For example, when the first and third switch control signals (S1, S3) have a high level, the second and fourth switch control signals (S2, S4) can have a low level. When the first and third switch control signals (S1, S3) have a low level, the second and fourth switch control signals (S2, S4) can have a high level.

[0183] When the switch control signal has a high level, the switch corresponding to the switch control signal can be turned on. On the other hand, when the switch control signal has a low level, the switch corresponding to the switch control signal can be turned off.

[0184] Referring to FIGS. 9 and 10, when the first and third switches (S1, S3) are turned on and the second and fourth switches (S2, S4) are turned off, the output voltage (Vo) can have a value of +Vin (hereinafter, the first value).

[0185] On the other hand, when the first and third switches (S1, S3) are turned off and the second and fourth switches (S2, S4) are turned on, the output voltage (Vo) can have a value of -Vin (hereinafter, the second value).

[0186] Here, Vin may refer to the magnitude of the DC voltage supplied from the DC power source to the inverter (1300). In addition, the first value may refer to the potential applied to the node (1610) being higher by Vin than the potential applied to the node (1630). In addition, the second value may refer to the potential applied to the node (1610) being lower by Vin than the potential applied to the node (1630).

[0187] Referring again to FIGS. 9 and 10, by controlling the four switches (S1 to S4) as described above so that the output voltage Vo alternately has the first value and the second value, an AC voltage can be generated. In other words, an AC voltage can be applied to the load by controlling the four switches (S1 to S4) described above.

[0188]

[0189] [2] Problems with the existing inverter (1300) switch control method

[0190] However, if the four switches (S1 to S4) are controlled so that the first value and the second value alternately form the output voltage Vo as described above, damage may occur to the switches (S1 to S4) of the inverter (1300) and the antenna structure (2000).

[0191] For example, when Vo is applied to the antenna structure (2000) as in FIG. 10, the magnitude of the current flowing in the antenna structure (2000) may increase significantly. For example, when a high voltage having a significantly large value of Vin is applied, if an AC voltage is applied to the antenna structure (2000), the difference between the minimum value and the maximum value of the AC voltage may be 2Vin. Meanwhile, before the ignition of the plasma inside the discharge tube (3000) is completed (i.e., before the plasma is sufficiently generated), the load due to the plasma may not be large, and accordingly, the total load may not be large.

[0192] Therefore, if 2Vin is a considerably high voltage and plasma is not sufficiently generated, and the total load of the load is considerably small, the magnitude of the current flowing in the antenna structure (2000) may become very large. The very large current generated accordingly may cause considerable damage to the switches (S1 to S4) of the antenna structure (2000) and the inverter (1300). In particular, it may cause considerable damage to the transistors included in the switches. In addition, an arcing phenomenon may occur in the antenna structure (2000).

[0193] Therefore, a method is needed to control the current flowing through the switches (S1 to S4) of the antenna structure (2000) and the inverter (1300) so that it does not become too large before the plasma is ignited (i.e., before the plasma is sufficiently generated).

[0194] Accordingly, the following describes a method for solving the above-described problem and an operation process for efficiently generating / inducing plasma accordingly.

[0195]

[0196] [Control method for "First Operation Mode"]

[0197] By reducing the amount of power supplied to the load by the inverter (1300), the magnitude of the current supplied to the load can be reduced. For example, if the amount of power is reduced by a factor of four, the magnitude of the AC current flowing to the load can be reduced by a factor of two. By reducing the magnitude of the AC current flowing to the load, damage that may occur to the switches (S1 to S4) of the inverter (1300) and the antenna structure (2000) can be reduced. In addition, by reducing the magnitude of the AC current flowing to the load, the arcing phenomenon that may occur in the antenna structure (2000) can be reduced.

[0198] Therefore, a method of controlling the switches (S1 to S4) of the inverter (1300) to reduce the amount of power applied to the load is required.

[0199] Fig. 11 shows a method of controlling switches (S1 to S4) of an inverter (1300) to reduce the amount of power applied to a load in a structure of a conventional inverter (1300) as described above.

[0200] Referring to FIG. 11, among two switches interposed between one of two output terminals (1610, 1630) and each of two input terminals (1650, 1670), if one switch is kept turned on and the other switch is kept turned off, and the remaining switches are selectively alternately turned on or off, Vo ​​can alternately have a first value (or a second value) and a 0 [V] value. Here, the meaning of Vo having 0 [V] or 0 [V] may mean that the inverter (1300) outputs 0 [V], which may mean that the inverter (1300) does not output any voltage. In other words, the meaning of Vo having 0 [V] or 0 [V] may mean that the inverter (1300) does not output either the first value or the second value.

[0201] In this case, since Vo does not have a second value (or a first value), the average voltage is reduced by half and the average power is reduced by four times compared to the existing switch control method according to Fig. 10. Accordingly, the current applied to the load can be reduced by two times, thereby reducing damage that may occur to the switches (S1 to S4) of the inverter (1300) and the antenna structure (2000).

[0202] Fig. 11 shows that switches S1 and S2 are selectively turned on or off by alternating while keeping switch S3 turned on and keeping switch S4 turned off. Then, as shown in the right figure of Fig. 11, Vo is output as an AC voltage having a first value (+Vin) and a 0 [V] value alternately, and the AC current flowing to the load can be reduced by half compared to selectively turning on or off all of switches S1 to S4.

[0203] FIGS. 12 and 13 show examples of controlling only two switches among the four switches (S1 to S4) of the inverter (1300) as described above, and controlling one of the remaining two switches to be kept turned on and the other to be kept turned off.

[0204] FIG. 12(a) shows an operation in which the controller (1500) selectively alternately turns on or off the switches S1 and S2 while controlling the switch S3 to be turned on and the switch S4 to be turned off, as in FIG. 11.

[0205] At this time, Vo is output as an AC voltage having the first value (+Vin) and 0 [V] values ​​alternately as described above, and is applied to the load.

[0206] Figure 12(b) shows an operation in which the controller (1500) selectively alternately turns the switches S1 and S2 on or off while controlling the switch S4 to be turned on and the switch S3 to be turned off.

[0207] At this time, Vo is output as an AC voltage that alternately has 0[V] and the second value (-Vin) and is applied to the load.

[0208] Figure 13(a) shows an operation in which the controller (1500) controls the switch S1 to be turned on and the switch S2 to be turned off, while selectively alternating the switches S3 and S4 to be turned on or off.

[0209] At this time, Vo is output as an AC voltage having the first value (+Vin) and 0 [V] values ​​alternately, and is applied to the load.

[0210] Figure 13(b) shows an operation in which the controller (1500) controls the switch S2 to be turned on and the switch S1 to be turned off, while selectively alternating the switches S3 and S4 to be turned on or off.

[0211] At this time, Vo is output as an AC voltage that alternately has 0[V] and a second value (-Vin) and is applied to the load.

[0212] As shown in FIGS. 12 and 13, if the controller (1500) selectively turns on or off only two of the four switches (S1 to S4) included in the inverter (1300) and controls the remaining switches to remain turned on or off, the power amount can be reduced by four times as described above, and the AC current flowing to the load can be reduced by two times.

[0213]

[0214] Hereinafter, among the examples disclosed in FIGS. 11 to 13, an operation mode in which four switches (S1 to S4) are controlled by one of the examples so that Vo has one of the first value and the second value and 0 [V] (i.e., two values) is defined as a “first operation mode.”

[0215] That is, the operation in which the controller (1500) selectively turns on or off the switches S1 and S2, while keeping the switch S3 (or switch S4) turned on and keeping the switch S4 (or switch S3) turned off is defined as a “first operation mode.”

[0216] Similarly, an operation in which the controller (1500) selectively turns on or off the switches S3 and S4, while keeping the switch S1 (or switch S2) turned on and keeping the switch S2 (or switch S1) turned off is also defined as a “first operation mode.”

[0217] Additionally, the operation in which the controller (1500) selectively turns on or off all four switches (S1 to S4) as described in FIGS. 9 and 10 is defined as a “second operation mode.”

[0218] Meanwhile, the "second operation mode" described in FIGS. 9 and 10 is described as having Vo only having the first and second values, but may also include a time interval having 0[V] in addition to the first and second values ​​of Vo.

[0219] For example, in the "second operation mode", the controller (1500) can control switches S1 and S3 to have different levels in one time interval, or control switches S2 and S4 to have different levels in one time interval, so that a time interval having 0[V] is included. For example, the controller (1500) can control Vo to be output in the order of "first value - 0[V] - second value" in the second operation mode, or control Vo to be output in the order of "second value - 0[V] - first value", and the time intervals during which the first value, 0[V], and the second value are continuously output can be the same or different, respectively.

[0220] Accordingly, the “first operation mode” may mean that the controller (1500) controls Vo to output two values, 0 [V] and a first value (or a second value). In addition, the “second operation mode” may mean that the controller (1500) controls Vo to output two values, the first value and the second value, or Vo to output three values, the first value, the second value, and 0 [V].

[0221] Therefore, the difference between the maximum and minimum values ​​of Vo when the controller (1500) controls the output of Vo according to the “second operation mode” may be twice as large as the difference between the maximum and minimum values ​​of Vo when the controller (1500) controls the output of Vo according to the “first operation mode”.

[0222]

[0223] [Transition from "First Operation Mode" to "Second Operation Mode" and Method for Determining the Transition Timing]

[0224] As described above, the "first operating mode" was a method for reducing the amount of AC current flowing in the load by lowering the amount of power applied to the load. However, if plasma is sufficiently generated in the discharge tube (3000), the impedance of the load increases accordingly, so that even if the same AC voltage is applied to the load, the amount of power consumed by the load may decrease. In addition, as the amount of power consumed decreases due to the increase in the impedance of the load, the AC current flowing in the load may decrease. In this case, the induced electric field induced by the AC current flowing in the load decreases, so that it may become difficult to maintain the generated plasma.

[0225] Therefore, after sufficient plasma is generated, it may be necessary to supply a greater amount of power than can be supported in the “first operating mode” to maintain the generated plasma.

[0226] Additionally, even before sufficient plasma is generated, a larger amount of power may need to be supplied to the load than the power consumption that can be supported in the "first operating mode" depending on the generation of plasma.

[0227] When the above-described cases occur, maintaining the "first operation mode" may be inefficient for plasma generation and maintenance. Therefore, the controller (1500) needs to control the switches (S1 to S4) by switching from the "first operation mode" to the "second operation mode" depending on the situation.

[0228] Hereinafter, examples in which the controller (1500) switches from the “first operation mode” to the “second operation mode” will be examined.

[0229]

[0230] [1] The controller (1500) controls the switches (S1 to S4) according to the “first operation mode”, and when the ignition of the plasma is completed, it controls the switches (S1 to S4) according to the “second operation mode”.

[0231] As described above, when the ignition of the plasma is completed and the generated plasma needs to be maintained, the inverter (1300) may be required to supply a greater amount of power to the load than before the ignition of the plasma was completed. For example, when a sufficient amount of plasma is generated to complete the ignition of the plasma, the impedance of the load increases, so that in order to supply the amount of power to maintain the plasma, it is necessary to increase the potential difference between the maximum value (e.g., the first value) and the minimum value (e.g., the second value) of the AC voltage applied across the antenna structure (2000).

[0232] Meanwhile, as seen in FIGS. 10 and 11, when the inverter (1300) supplies power to the load according to the “second operation mode”, more power can be supplied than when it supplies power to the load according to the “first operation mode”. For example, when the inverter (1300) applies the AC voltage to the antenna structure (2000) according to the “second operation mode”, the potential difference between the maximum value (e.g., the first value) and the minimum value (e.g., the second value) of the AC voltage is twice the potential difference between the maximum value (e.g., the first value) and the minimum value (e.g., the second value) of the AC voltage when the inverter (1300) applies the AC voltage to the antenna structure (2000) according to the “first operation mode”, so the power that the inverter (1300) can supply to the antenna structure (2000) according to the “second operation mode” can be four times the power that the inverter (1300) can supply to the antenna structure (2000) according to the “first operation mode”.

[0233] Therefore, after the ignition of the plasma is completed, it may be desirable for the controller (1500) to control the four switches (S1 to S4) of the inverter (1300) according to the “second operation mode” so that the inverter (1300) supplies sufficient power to the antenna structure (2000) to maintain the plasma.

[0234] In addition, when the impedance of the load increases, the AC current flowing through the load decreases even if the same power is supplied to the load. Therefore, after the ignition of the plasma is completed, since the impedance of the load has sufficiently increased, even if the power provided to the antenna structure (2000) according to the "second operation mode" is four times the power provided to the antenna structure (2000) according to the "first operation mode", the AC current flowing through the load may not increase compared to before the ignition of the plasma is completed, or even if it increases, the risk of causing damage to the antenna structure (2000) or the switch (or the risk of causing an arcing phenomenon) may be significantly reduced.

[0235] Therefore, it may be necessary to switch from “first operation mode” to “second operation mode” before and after the plasma is completed.

[0236] Let us examine this transition process with reference to Figure 14.

[0237] Referring to FIG. 14, the controller (1500) can control the four switches (S1 to S4) of the inverter (1300) according to the “first operation mode” until the ignition of the plasma is completed (S1401). The controller (1500) determines whether the ignition of the plasma is completed (S1403). If the controller (1500) determines that the ignition of the plasma is completed, the controller (1500) can control the four switches of the inverter (1300) according to the “second operation mode” (S1405). If the controller (1500) determines that the ignition of the plasma is not completed, the controller (1500) returns to S1401 and can still control the four switches of the inverter (1300) according to the “first operation mode”.

[0238] In other words, the controller (1500) determines whether the ignition of the plasma is complete and maintenance of the generated plasma is required, and if maintenance of the generated plasma is determined to be required, the controller can control the switches (S1 to S4) controlled according to the “first operation mode” according to the “second operation mode”.

[0239] Meanwhile, as described above, the fact that the ignition of the plasma is complete and that the generated plasma needs to be maintained means that the plasma has transitioned from the E mode state to the H mode state, and thus, it may mean that the amount of plasma generated inside the discharge tube (3000) is greater than a certain standard amount.

[0240] Meanwhile, a method for determining whether ignition of the plasma is complete, i.e., whether the amount of plasma generated inside the discharge tube (3000) is greater than a certain standard amount, will be described later.

[0241]

[0242] [2] The controller (1500) controls the switches (S1 to S4) according to the “first operation mode”, and when the power consumption of the load reaches the power consumption that the “first operation mode” can support, the controller controls the switches (S1 to S4) according to the “second operation mode”.

[0243] Meanwhile, in some cases, even if the ignition of the plasma is not completed (i.e., even if the plasma is not generated in an amount exceeding the reference amount), the controller (1500) may need to control the switches (S1 to S4) by switching from the “first operation mode” to the “second operation mode.”

[0244] For example, in order to prevent damage to the switches (S1 to S4) of the inverter (1300) and the antenna structure (2000), a limitation of the current that can flow to the plasma generation device (100) can be set. That is, the value of the maximum current that can flow to the plasma generation device (100) can be set.

[0245] However, when a current that is equal to or less than the maximum current value flows through the load, plasma is generated and the impedance value of the load increases, so the amount of power consumed by the load increases.

[0246] In other words, when an AC voltage is applied to the antenna structure (2000), plasma is generated inside the discharge tube (3000), and the amount of generated plasma increases. Therefore, when a current that is equal to or less than a certain value of the maximum current flows to the load, if the impedance of the load continues to increase, the amount of power required to continuously induce / generate and maintain the plasma increases. Therefore, even before the plasma is generated above a reference amount (i.e., before the ignition of the plasma is completed), the amount of power required to continuously induce / generate and maintain the plasma may become greater than the amount of power that the inverter (1300) can supply according to the “first operation mode”.

[0247] Additionally, if the amount of power that the inverter (1300) can supply is less than the amount of power required to continuously induce / generate and maintain plasma, plasma cannot be properly generated, in other words, ignition of the plasma cannot be completed.

[0248] Therefore, when the amount of power required to continuously induce / generate and maintain plasma reaches the amount of power that the inverter (1300) can supply according to the “first operation mode”, the controller (1500) may need to control the switches (S1 to S4) of the inverter (1300) by switching from the “first operation mode” to the “second operation mode” to increase the amount of power supplied to the load. Here, the amount of power that can be supplied according to the “first operation mode” can be determined by the value of the set maximum current and the AC voltage that can be applied to the load according to the “first operation mode”.

[0249] Let us examine this transition process with reference to Figure 15.

[0250] Referring to FIG. 15, the controller (1500) can control four switches (S1 to S4) of the inverter (1300) according to a “first operation mode” (S1501). The controller (1500) can determine whether the amount of power applied to the load has reached the maximum amount of power that can be provided to the load through the inverter (1300) using the “first operation mode” or a preset reference amount of power (S1503). Here, the fact that the amount of power applied to the load has reached the maximum amount of power or the preset reference amount of power may mean that the amount of power applied to the load is equal to the maximum amount of power or the preset reference amount of power, or differs from it within a certain range.

[0251] If the amount of power applied to the load has reached the maximum amount of power or the preset reference amount of power, the controller (1500) can control the four switches (S1 to S4) of the inverter (1300) according to the “second operation mode” (S1505). If the amount of power applied to the load has not reached the maximum amount of power or the preset reference amount of power, the controller (1500) can return to S1501 and control the four switches (S1 to S4) of the inverter (1300) according to the “first operation mode”.

[0252] Meanwhile, the amount of power applied to the load can be monitored in the same manner as in the “Method for determining whether ignition of plasma is complete” described later, “[1] Method for determining by monitoring power.” That is, the amount of power applied to the load can be calculated based on the input DC voltage and input DC current applied to the inverter (1300).

[0253]

[0254] [Method for determining whether plasma ignition is complete]

[0255] Below, we will examine a method for determining whether ignition of plasma is complete, i.e., whether plasma has been generated in excess of a standard amount inside the discharge tube (3000).

[0256] [1] A method for determining whether plasma ignition is complete by monitoring power.

[0257] In one embodiment, the controller (1500) can monitor the power applied to the load and determine that the ignition of the plasma is complete when the monitored power satisfies a certain condition.

[0258] Meanwhile, since it is difficult to directly measure the power applied to the load, the controller (1500) can estimate the power applied to the load based on the input DC voltage and input DC current applied to the inverter (1300).

[0259] This is because the transfer efficiency between the power applied to the inverter (1300) and the power delivered to the load is close to 100%. Accordingly, the input DC power of the inverter (1300) is very similar to the power applied to the load. Therefore, if the input DC power is calculated based on the input DC voltage and input DC current of the inverter (1300), the calculated input DC power can be estimated as the power applied to the load.

[0260] Therefore, in the following, the meaning of monitoring the power applied to the load or measuring the power applied to the load in this specification may be interpreted to mean calculating the input DC power applied to the inverter (1300).

[0261] Meanwhile, as plasma is generated, the impedance value of the load changes. Accordingly, the resonant frequency of the entire load also changes according to the variable impedance value of the load. If the resonant frequency and the frequency of the AC voltage applied to the load by the inverter (1300) are different, the power efficiency decreases, thereby lowering the efficiency of plasma generation / induction.

[0262] Accordingly, the controller (1500) can control the frequency of the switch control signal based on the phase difference or delay time between the AC voltage applied to the load and the AC current flowing in the load so that the resonant frequency of the load and the frequency of the AC voltage are identical. That is, since the frequency of the AC voltage applied to the load is adjusted by the frequency of the switch control signal, the frequency of the AC voltage can be controlled to be as close as possible to the resonant frequency of the load by the controller (1500) controlling the frequency of the switch control signal. This frequency control method can be defined as "frequency tracking."

[0263] Meanwhile, the aforementioned frequency tracking may or may not be used during the plasma generation process. Furthermore, depending on whether frequency tracking is applied, the method for determining whether plasma ignition is complete through power monitoring may vary.

[0264]

[0265] [1-1] Method for determining whether plasma ignition is complete when frequency tracking is applied

[0266] Since the AC voltage applied to the load is constant according to the "first operation mode", as the impedance value of the load increases, the amount of power applied to the load decreases. Therefore, when the ignition of the plasma is complete and the plasma is generated in an amount exceeding the reference amount, the impedance value and equivalent resistance of the load will increase, and since the AC voltage applied to the load is constant according to the "first operation mode", the amount of power applied to the load will decrease.

[0267] Accordingly, the controller (1500) can determine that plasma is generated in an amount greater than a reference amount and that ignition of the plasma is complete when the monitored power falls below a first threshold value or the amount of power reduction per unit time is greater than a certain level.

[0268]

[0269] [1-2] Method for determining whether plasma ignition is complete when frequency tracking is not applied - i.e., when the frequency of the AC voltage applied to the load is fixed.

[0270] In general, the impedance of the load is set so that the phase of the AC voltage applied to the load is ahead of the phase of the AC current flowing in the load. In other words, the impedance of the load is in an inductive state. Accordingly, when applying the AC voltage to the antenna structure (2000) to generate / induce plasma, the frequency of the AC voltage applied to the load by the inverter (1300) is set to a value slightly higher than the resonant frequency of the load.

[0271] This is because if the frequency of the AC voltage and the resonant frequency of the load are matched from the beginning, too high a current will flow to the load, which may damage the load or the switch of the inverter (1300) and cause an arcing phenomenon.

[0272] Additionally, the phase of the AC voltage applied to the load must be set to lead the phase flowing through the load to ensure ZVS (Zero Voltage Switching) or near-ZCS (near-Zero Current Switching).

[0273] Meanwhile, the input DC power applied to the inverter (1300) when the AC voltage starts to be applied to the load is very small. In addition, when the plasma ignition is completed and the generated plasma becomes more than the reference amount, the impedance of the load may be such that the phase of the AC current flowing in the load is ahead of the phase of the AC voltage applied to the load, or even if the phase of the AC voltage applied to the load is ahead of the phase of the AC current flowing in the load, the phase difference or delay time may be less than the phase difference or delay time at the time when the power starts to be applied.

[0274] This means that the frequency of the AC voltage applied to the load has become closer to the resonant frequency of the load. This means that as the AC current applied to the load increases, the power applied to the load increases. Accordingly, the controller (1500) can determine that plasma is generated in an amount greater than a reference amount and that plasma ignition is complete when the monitored power exceeds a second threshold value or the amount of increase in power per unit time is greater than a certain level.

[0275]

[0276] [2] A method for determining whether plasma ignition is complete by monitoring the phase difference or delay time between the AC voltage applied to the load and the current flowing through the load.

[0277] As described above, the impedance of the load is generally set so that the phase of the AC voltage applied to the load is ahead of the phase of the AC current flowing in the load. In other words, the impedance of the load is in an inductive state. Accordingly, when applying the AC voltage to the antenna structure (2000) to generate / induce plasma, the frequency of the AC voltage applied to the load by the inverter (1300) is set to a value slightly higher than the resonant frequency of the load.

[0278] As described above, when plasma ignition is completed and the generated plasma exceeds the reference amount, the phase of the AC current flowing through the load leads the phase of the AC voltage applied to the load in the impedance of the load. This is because when plasma ignition is completed, the impedance value of the load increases and the inductance of the load decreases, resulting in a capacitive state in which the phase of the AC current flowing through the load leads the phase of the AC voltage applied to the load.

[0279] Therefore, it is possible to determine whether plasma ignition is complete by monitoring the phase difference or delay time between the AC voltage applied to the load and the AC current flowing through the load.

[0280] Specifically, let us examine a method for determining whether plasma ignition is complete by using the phase difference or delay time of the AC voltage applied to the load and the AC current flowing to the load through FIG. 16.

[0281] Referring to Fig. 16, the phase difference or delay time of the applied AC voltage and the AC current flowing in the load can be determined by calculating the delay time between the virtual signal that shifts the switch control signal for controlling the operation of the four switches of the inverter (1300) by a certain amount of time and the phase signal of the output current sensed through the sensor (1400).

[0282] Specifically, the controller (1500) assumes a virtual signal by shifting the switch control signal by a certain period of time. At this time, the certain period of time may be the time required for the switch control signal to be input to the inverter (1300) and for the AC voltage to be output through the inverter (1300). For example, in FIG. 16, it corresponds to (1). In addition, the switch control signal shifted to assume a virtual signal may be input to the switch S1 or the switch S3. For example, if the controller (1500) operates according to the “first operation mode” and maintains the switch S3 turned on or off while controlling the switch S1 to be selectively turned on or off, the switch control signal for assuming a virtual signal may be the switch S1.

[0283] For example, if the controller (1500) operates in the “first operation mode” and controls the switch S3 to be selectively turned on or off while keeping the switch S1 turned on or off, the switch control signal for assuming the virtual signal may be the switch S3.

[0284] However, it is not limited thereto, and the switch control signal for assuming a virtual signal may be a switch control signal input to switch S2 or switch S4. For example, if switch S2 is controlled to be selectively turned on or off while maintaining switch S4 turned on or off while operating according to the “first operation mode”, the switch control signal for assuming a virtual signal may be switch S2. In this case, the controller (1500) may invert the switch control signal input to switch S2 and shift it by a certain period of time to assume a virtual signal. Alternatively, the controller (1500) may shift the switch control signal input to switch S2 by a certain period of time to assume a virtual signal, and invert the phase signal of the output current.

[0285] For example, if the switch S4 is controlled to be selectively turned on or off while the switch S2 is kept turned on or off while operating according to the “first operation mode”, the switch control signal for calculating the phase difference or delay time may be the switch S4. In this case, the controller (1500) may invert the switch control signal input to the switch S4 and shift it by a certain period of time to assume it as a virtual signal. Alternatively, the controller (1500) may shift the switch control signal input to the switch S4 by a certain period of time to assume it as a virtual signal and invert the phase signal of the output current.

[0286] The controller (1500) can count the value from the rising edge of the virtual signal to the falling edge of the virtual signal according to the clock of the controller (1500). For example, the section corresponding to (2) in FIG. 16 can be counted according to the clock of the controller (1500). This is called a “first counting value.”

[0287] Meanwhile, the controller (1500) can count from the rising edge of the virtual signal to the falling edge of the phase signal of the output current according to the clock of the controller (1500). For example, the section corresponding to (3) in FIG. 16 can be counted according to the clock of the controller (1500). This is called a "second counting value."

[0288] The controller (1500) can determine that the plasma ignition is completed by determining that the phase of the AC current flowing in the load is in a capacitive state that is ahead of the phase of the AC voltage applied to the load when "the first counting value - the second counting value < 0". That is, the value obtained by subtracting the second counting value from the first counting value may mean the phase difference or delay time between the AC voltage applied to the load and the AC current flowing in the load. In addition, when the value obtained by subtracting the second counting value from the first counting value is 0 or less, it can be determined that the phase of the AC current flowing in the load is in a capacitive state that is ahead of the phase of the AC voltage applied to the load.

[0289]

[0290] Meanwhile, whether to monitor the power applied to the load (or the input DC power applied to the inverter (1300)) to determine whether plasma ignition is complete or to monitor the phase difference between the AC voltage applied to the load and the AC current flowing in the load to determine whether plasma ignition is complete may vary depending on the situation. Determining whether plasma ignition is complete by monitoring the phase difference or delay time has the effect of being able to determine whether plasma ignition is complete even if the power loss of the antenna structure (2000) itself is large. That is, when the power loss of the antenna structure (2000) itself is large, even though plasma ignition is not complete, it may be determined that plasma ignition is complete because the power supplied to the load is measured to be large. Therefore, when the power loss of the antenna structure (2000) itself is large, it is effective to determine whether plasma ignition is complete by monitoring the phase difference or delay time.

[0291] In addition, monitoring the phase difference or delay time to determine whether plasma ignition is complete has the advantage of being able to monitor regardless of the magnitude of the AC voltage applied to the load and the AC current flowing in the load or the magnitude of the input DC voltage and input DC current applied to the inverter (1300).

[0292] On the other hand, in a case where a high AC current must be applied to the load from the start of driving the plasma generation device (100) for plasma ignition, the operation of the plasma generation device (100) may be started in a state where there is almost no phase difference or delay time between the resonant frequency of the load and the frequency of the AC voltage applied to the load. In this case, it may be more efficient to determine whether plasma ignition is complete by monitoring the phase difference or delay time between the AC voltage applied to the load and the AC current flowing to the load.

[0293]

[0294] [Operation process according to the configuration of the plasma generation device (100)]

[0295] Hereinafter, as disclosed in FIG. 7, the case where the antenna structure (2000) surrounding the outer wall of the plasma generation device (100) is an ignition antenna structure (2100) and a maintenance antenna structure (2200) is two, and as disclosed in FIG. 8, the case where the antenna structure (2000) surrounding the outer wall of the plasma generation device (100) is a single maintenance antenna structure (2200), and the process in which the controller (1500) controls four switches (S1 to S4) of the inverter (1300) according to the “first operation mode” and the “second operation mode” will be examined.

[0296] [1] Operation process based on the plasma generation device (100) of Fig. 8

[0297] As can be seen in Fig. 8, the antenna structure (2200) surrounding the outer wall of the plasma generation device (100) may be a single maintenance antenna structure (2200). In this case, the plasma generation device (100) may operate as described in Figs. 14 and 15.

[0298] For example, according to FIG. 14, the plasma generation device (100) can operate the RF generator (1000) to supply an AC voltage to the sustain antenna structure (2200) according to the “first operation mode.” At this time, the controller (1500) can apply a switch control signal to the inverter (1300) according to the “first operation mode” to supply an AC voltage to the antenna structure (2200). When the controller (1500) determines that plasma ignition is complete as described in FIG. 14, it can apply a switch control signal to the inverter (1300) according to the “second operation mode” to supply an AC voltage to the antenna structure (2200).

[0299] At this time, the method by which the controller (1500) determines that plasma ignition is complete is omitted as described in “[Method for determining whether plasma ignition is complete]”.

[0300] For example, according to FIG. 15, the plasma generation device (100) can operate the RF generator (1000) to supply an AC voltage to the sustain antenna structure (2200) according to the “first operation mode.” At this time, the controller (1500) can supply an AC voltage to the antenna structure (2200) by applying a switch control signal to the inverter (1300) according to the “first operation mode.” When the controller (1500) determines that the maximum power amount that can be supplied according to the “first operation mode” or a preset reference power amount has been reached as described in FIG. 15, the controller (1500) can supply an AC voltage to the antenna structure (2200) by applying a switch control signal to the inverter (1300) according to the “second operation mode.”

[0301]

[0302] [2] Operation process based on the plasma generation device (100) of Fig. 7

[0303] As can be seen in Fig. 7, the antenna structure (2200) surrounding the outer wall of the plasma generation device (100) may be composed of two antenna structures: an ignition antenna structure (2100) and a maintenance antenna structure (2200).

[0304] When the plasma generation device (100) is configured using an ignition antenna structure (2100) and a maintenance antenna structure (2200) as shown in FIG. 7, the operation process of the plasma generation device (100) can be varied.

[0305] Let us examine this through Figures 17 to 20.

[0306] Meanwhile, in the description to be described below, the operation performed by the first RF generator (1001) or the second RF generator (1002) should be understood as an operation controlled by the controller of the first RF generator (1001) or the controller of the second RF generator (1002). In addition, the specific operation process of such a controller may follow the descriptions described above in this specification.

[0307] Referring to FIG. 17, a first RF generator (1001) can supply a first AC voltage to an ignition antenna structure (2100) according to a first operation mode (S1701). At this time, the first RF generator (1001) determines whether plasma ignition is completed (i.e., whether plasma is generated in an amount greater than a reference amount) in an internal space of a discharge tube (3000) corresponding to a position where the ignition antenna structure (2100) is arranged (S1703), and if it is determined that plasma ignition is completed, a second AC voltage can be supplied to the ignition antenna structure (2100) according to a second operation mode (S1705). Meanwhile, (i) simultaneously with the first RF generator (1001) supplying the second AC voltage, or (ii) after the first RF generator (1001) supplies the second AC voltage, or (iii) before the first RF generator (1001) supplies the second AC voltage after determining that the plasma has been ignited, the second RF generator (1002) can supply the third AC voltage according to the second operation mode to the sustain antenna structure (2200) (S1707).

[0308] The second RF generator (1002) can determine whether the plasma generated in the internal space of the discharge tube (3000) corresponding to the position where the ignition antenna structure (2100) is placed has moved or spread to the internal space of the discharge tube (3000) corresponding to the position where the sustaining antenna structure (2200) is placed (S1709).

[0309] At this time, the second RF generator (1002) can determine whether the plasma has moved or spread by applying the same method as [Method for determining whether ignition of plasma is complete]. This is because, when the plasma has moved or spread to the internal space of the discharge tube (3000) corresponding to the position where the sustaining antenna structure (2200) is arranged, the impedance of the sustaining antenna structure (2200) will increase like the impedance of the ignition antenna structure (2100) until the ignition of the plasma is complete.

[0310] Accordingly, by applying the same method as [Method for determining whether ignition of plasma is complete], the second RF generator (1002) can determine whether the plasma has moved or spread to the internal space of the discharge tube (3000) corresponding to the position where the maintenance antenna structure (2200) is placed.

[0311] When the movement or spreading of the plasma is completed, the second RF generator (1002) continuously supplies a third AC voltage to the maintenance antenna structure (2200) to maintain the plasma (S1711), while the first RF generator (1001) can stop supplying the AC voltage to the ignition antenna structure (2100) (S1713).

[0312] Meanwhile, the time interval from the start of S1701 in FIG. 17 until the completion of S1703 may be referred to as the first time interval. Furthermore, the time interval from the start of S1705 in FIG. 17 until the completion of S1709 may be referred to as the second time interval. Furthermore, the interval in which S1711 and S1713 in FIG. 17 are performed may be referred to as the third time interval.

[0313] Referring to Fig. 18, let us look at another example of the operation process of the plasma generation device (100).

[0314] Referring to FIG. 18, a first RF generator (1001) can supply a first AC voltage to an ignition antenna structure (2100) according to a first operation mode (S1801). In addition, a second RF generator (1002) can supply a fourth AC voltage to a sustaining antenna structure (2200) according to the first operation mode or the second operation mode (S1803). For example, the second RF generator (1002) can supply the fourth AC voltage to the sustaining antenna structure (2200) according to the first operation mode or the second operation mode (i) simultaneously with the first RF generator supplying the first AC voltage to the ignition antenna structure (2100), or (ii) before the first RF generator supplies the first AC voltage to the ignition antenna structure (2100), or (iii) after the first RF generator supplies the first AC voltage to the ignition antenna structure (2100) but before plasma ignition is completed.

[0315] For example, if there is a need to supply power exceeding a certain value for plasma discharge even before plasma ignition is completed, the second RF generator (1002) can supply a fourth AC voltage to the sustain antenna structure (2200) according to the second operation mode. This is because supplying the fourth AC voltage according to the second operation mode can supply greater power to the sustain antenna structure (2200) than supplying the fourth AC voltage according to the first operation mode.

[0316] However, if there is no need to supply power exceeding a certain value to the maintenance antenna structure (2200) or if there is still a need to limit the size of the current, the second RF generator (1002) may supply a fourth AC voltage according to the first operating mode.

[0317] The first RF generator (1001) determines whether plasma ignition is completed (i.e., whether plasma is generated in an amount greater than a reference amount) in the internal space of the discharge tube (3000) corresponding to the position where the ignition antenna structure (2100) is arranged (S1805), and if it is determined that plasma ignition is completed, the second AC voltage can be supplied to the ignition antenna structure (2100) according to the second operation mode (S1807). Meanwhile, the second RF generator (1002) can supply a third AC voltage according to the second operation mode to the maintenance antenna structure (2200) (S1809).

[0318] The second RF generator (1002) can determine whether the plasma generated in the internal space of the discharge tube (3000) corresponding to the position where the ignition antenna structure (2100) is arranged has moved or spread to the internal space of the discharge tube (3000) corresponding to the position where the sustain antenna structure (2200) is arranged (S1811). At this time, whether the plasma movement or spreading is complete is the same as that described while describing S1709 of FIG. 17, and thus, a detailed description thereof will be omitted.

[0319] When the movement or spreading of the plasma is completed, the second RF generator (1002) continuously supplies a third AC voltage to the maintenance antenna structure (2200) to maintain the plasma (S1813), while the first RF generator (1001) can stop supplying the AC voltage to the ignition antenna structure (2100) (S1815).

[0320] Meanwhile, the time interval from the start of S1801 in FIG. 18 until the completion of S1805 may be referred to as the first time interval. Furthermore, the time interval from the start of S1807 in FIG. 18 until the completion of S1811 may be referred to as the second time interval. Furthermore, the interval in which S1813 and S1815 in FIG. 18 are performed may be referred to as the third time interval.

[0321]

[0322] Referring to Fig. 19, let us look at an example of the operation process of the plasma generation device (100).

[0323] Referring to FIG. 19, a first RF generator (1001) can supply a first AC voltage to an ignition antenna structure (2100) according to a first operation mode (S1901). The first RF generator (1001) measures the amount of power supplied to a load and determines whether the amount of power supplied in the first operation mode has reached the maximum amount of power supplyable or the preset reference amount of power (S1903). If it is determined that the amount of power supplied to the load has reached the maximum amount of power supplyable or the preset reference amount of power supplyable in the first operation mode, the first RF generator (1001) supplies a second AC voltage according to a second operation mode to the ignition antenna structure (2100) (S1905). The first RF generator (1001) can determine whether plasma ignition is completed (S1907). If it is determined that plasma ignition is completed, steps S1909 to S1915 can be performed. At this time, the operation process of S1909 to S1915 is the same as the operation process of S1707 to S1713 of Fig. 17, so a detailed description will be omitted.

[0324] Meanwhile, the time interval from the start of S1901 in FIG. 19 until the completion of S1907 may be referred to as the first time interval. Furthermore, the time interval from the start of S1709 in FIG. 19 until the completion of S1711 may be referred to as the second time interval. Furthermore, the interval in which S1913 and S1915 in FIG. 19 are performed may be referred to as the third time interval.

[0325] Referring to Fig. 20, let us look at an example of the operation process of the plasma generation device (100).

[0326] Referring to FIG. 20, a first RF generator (1001) can supply a first AC voltage to an ignition antenna structure (2100) according to a first operation mode (S2001). In addition, a second RF generator (1002) can supply a fourth AC voltage to a sustaining antenna structure (2200) according to the first operation mode or the second operation mode (S2003). For example, the second RF generator (1002) can supply the fourth AC voltage to the sustaining antenna structure (2200) according to the first operation mode or the second operation mode (i) simultaneously with the first RF generator supplying the first AC voltage to the ignition antenna structure (2100), or (ii) before the first RF generator supplies the first AC voltage to the ignition antenna structure (2100), or (iii) after the first RF generator supplies the first AC voltage to the ignition antenna structure (2100) but before plasma ignition is completed. Meanwhile, the example of the second RF generator (1002) supplying the fourth AC voltage according to the first operation mode and the example of supplying the fourth AC voltage according to the second operation mode are the same as those disclosed in the description related to S1803 of FIG. 18, and are omitted as they are redundant descriptions.

[0327] The first RF generator (1001) can perform steps S2005 to S2009. Steps S2005 to S2009 are identical to steps S1903 to S1907 of FIG. 19, and thus, a redundant description thereof will be omitted. Subsequently, steps S2011 to S2017 are performed, and steps S2011 to S2017 are identical to steps S1809 to S1815 of FIG. 18, and thus, a redundant description thereof will be omitted.

[0328] Meanwhile, in FIG. 20, the time interval from the start of S2001 until the completion of S2009 can be referred to as the first time interval. Furthermore, in FIG. 20, the time interval from the start of S2011 until the completion of S2013 can be referred to as the second time interval. Furthermore, in FIG. 20, the interval during which S2015 and S2017 are performed can be referred to as the third time interval.

[0329] Meanwhile, in FIGS. 17 to 20, the first RF generator (1001) continuously supplies the second AC voltage to the ignition antenna structure (2100) according to the second operation mode during the second time interval. That is, it should be understood that the first RF generator (1001) continuously supplies the second AC voltage to the ignition antenna structure (2100) according to the second operation mode until the AC voltage supply of the first RF generator (1001) is stopped (e.g., until the third time interval begins) after supplying the second AC voltage to the ignition antenna structure (2100) according to the second operation mode during the first time interval.

[0330]

[0331] [Transition from "Second Operation Mode" to "First Operation Mode" and Method for Determining the Transition Timing]

[0332] Meanwhile, in order to maintain the plasma after the plasma is ignited, the controller (1500) may control the switches S1 to S4 of the inverter (1300) according to the "second operation mode." However, while maintaining the plasma, there may be a need to supply lower power than the current power supplied to the load (2000). In this case, the controller (1500) may switch back to the "first operation mode" and control the switches S1 to S4 of the inverter (1300).

[0333] This will be explained in more detail in “[3] Operation Example 3” described later.

[0334]

[0335] [Power control method using the freewheeling section in the “second operation mode”]

[0336] Through FIGS. 9 and 10, it has already been explained that the “second operation mode” means that the controller (1500) controls Vo to have two values, a first value (+Vin) and a second value (-Vin), or three values, a first value (+Vin), a second value (-Vin), and 0[V]. In addition, it has been explained that in the “second operation mode,” the controller (1500) can continuously output the first value, 0[V], and the second value as Vo at different time intervals or can be the same.

[0337] As described above, if the controller (1500) differently controls the time intervals during which the first value, 0 [V], and second value are continuously output as Vo, the AC power provided to the load can be controlled.

[0338] Hereinafter, in the present disclosure, a method for controlling power provided to a load by a controller (1500) by controlling the Vo value will be examined. Hereinafter, for convenience of explanation, it is described that the controller (1500) controls the power of the load. However, this should not be interpreted as the controller (1500) controlling only power, but should be interpreted as the current flowing to the load and the electromotive force provided to the plasma also change as the power changes. This is because it is obvious to those skilled in the art that power, current, and electromotive force are interdependent, and that when power changes, the current and electromotive force also change.

[0339] In addition, in the description to be described below, the driving frequency of the output voltage means the target frequency of the AC voltage, AC current and / or AC power that the controller (1500) intends to output to the load. If, in a time interval such as Time Interval A of Fig. 21 where the first value and the second value are alternately output, the driving frequency becomes the fundamental frequency, which is the strongest frequency component among the frequency components of the square pulse waveform. In addition, when the driving frequency matches the resonant frequency of the load, the transfer efficiency of the power applied to the load is maximized.

[0340] Based on the above description, a method for controlling AC power provided to a load by a controller (1500) will be described. Fig. 21 shows an embodiment of an output voltage pattern that the controller (1500) outputs by adjusting the value of Vo. Referring to Fig. 21, the output voltage pattern may include at least one of (i) a powering period (P-period) in which a first value or a second value is output during a half-cycle of a driving frequency of the output voltage (or output power), and (ii) a freewheeling period (F-period) in which 0 [V] is output during a continuous time period having a length of N times the half-cycle of the driving frequency (N is a natural number greater than or equal to 1). As described above, 0 [V] may be a control that the controller (1500) performs so that no voltage is output during the freewheeling period.

[0341] The controller (1500) can control the power provided to the load by adjusting the length of the freewheeling section. Alternatively, the controller (1500) can control the power provided to the load by changing the ratio and / or arrangement of the freewheeling section having a predetermined length. Alternatively, the controller (1500) can control the power provided to the load by adjusting the length of the freewheeling section and changing the ratio and / or arrangement of the freewheeling section having the adjusted length.

[0342] The above freewheeling section causes the frequency component corresponding to the driving frequency of the output voltage to be attenuated or disappear when Vo is output. In other words, as the freewheeling section becomes longer, the frequency component of the driving frequency may not reach the fundamental frequency within a certain time interval including the freewheeling section, or even if it reaches the fundamental frequency, the frequency component thereof may be gradually attenuated. As the frequency component of the driving frequency of the output voltage is gradually attenuated, the current flowing to the load is exponentially reduced according to the time constant of the load, and accordingly, the AC power and AC current delivered to the load, and the electromotive force delivered to the plasma are reduced. Therefore, when the controller (1500) outputs Vo, by appropriately arranging and outputting the freewheeling section, the AC power and AC current provided to the load, and the electromotive force delivered to the plasma can be controlled.

[0343] Meanwhile, since the required electromotive force also differs depending on (i) the flow rate and type of the processing gas to be processed using the plasma, (ii) the processing purpose of processing the processing gas (e.g., radical generation, ion generation, processing gas decomposition, etc.), and (iii) the flow rate and type of the ignition gas for igniting the plasma, it is important to provide the plasma with an appropriate electromotive force suitable for the processing purpose. To this end, if the controller (1500) appropriately adjusts the ratio and the output time of the first value, 0 [V], and the second value of Vo to control the power provided to the load, an appropriate electromotive force suitable for the processing purpose is provided to the plasma, so that the processing gas can be processed in a manner suitable for the processing purpose.

[0344] Figure 22 shows an example of how the controller (1500) controls the power provided to the load using the freewheeling section.

[0345] Referring to FIG. 22, the controller (1500) sets a target power amount (S2201). The controller (1500) can set the target power amount by having the user input the target power amount into the RF generator (1000), selecting it from among candidate target power amounts stored in advance, or receiving it from an external device. In addition, the target power amount can be set based on at least one of (i) the flow rate and type of the processing gas to be processed using the plasma, (ii) the processing purpose of processing the processing gas, (iii) the flow rate and type of the ignition gas for igniting the plasma, and (iv) the limit allowable current of the switch.

[0346] In addition, the controller (1500) can repeat the processes of S2203 to S2213 described below at predetermined intervals. Looking into this in detail, the controller (1500) monitors the current amount of power currently being provided to the load (S2203). The method for monitoring the current amount of power overlaps with the power monitoring method described in “[1] Method for Determining Whether Plasma Ignition is Complete by Monitoring Power,” and therefore, a detailed description thereof will be omitted.

[0347] The controller (1500) determines whether the difference between the target power amount and the current power amount is within a preset range (S2205). If the difference is within the preset range, the switches (S1 to S4) can be controlled to maintain the output voltage pattern of the currently output Vo. Here, the output voltage pattern refers to a pattern determined according to the ratio of the powering section and the freewheeling section included in one predetermined cycle, the arrangement of the powering section, and the length and arrangement of the freewheeling section.

[0348] If the difference between the target power amount and the current power amount is outside the preset range and the target power amount is greater than the current power amount (S2209), the controller (1500) changes the output voltage pattern so that at least one of the ratio and the length of the freewheeling section is reduced compared to the current output voltage pattern, and controls the switches (S1 to S4) so ​​that Vo is output according to the changed output voltage pattern, thereby increasing the power provided to the load (S2211). If the difference between the target power amount and the current power amount is outside the preset range and the target power amount is less than the current power amount (S2209), the controller (1500) changes the output voltage pattern so that at least one of the ratio and the length of the freewheeling section is increased compared to the current output voltage pattern, and controls the switches (S1 to S4) so ​​that Vo is output according to the changed output voltage pattern, thereby reducing the power provided to the load (S2213).

[0349] Meanwhile, in the power control method described above, when the controller (1500) determines the output voltage pattern, it may determine that the Vo values ​​immediately before and immediately after the freewheeling section are different. For example, the controller (1500) may determine the output voltage pattern such that if the first value (or the second value) is placed immediately before the freewheeling section, the second value (or the first value) is placed immediately after. An inductor for zero voltage switching (ZVS) may be electrically connected between the node (1610) and the node (1630). In order for the operation of the four switches (S1 to S4) included in the inverter (1300) to be a soft switching operation, the peak value of the current flowing in one direction in the inductor must be the same as the peak value of the current flowing in the opposite direction to the one direction. In addition, in order for the peak value of the current flowing in the one direction and the peak value of the current flowing in the opposite direction to be the same, the Vo values ​​immediately before and immediately after the freewheeling section must be different.

[0350] This is to increase the efficiency of applying an AC voltage having a frequency component of the driving frequency to a load by strengthening the frequency component of the driving frequency when the first or second value is output in the powering section. For example, due to the determination of the output voltage pattern described above, when the first or second value is output in the powering section, the frequency component of the driving frequency may become the fundamental frequency component.

[0351]

[0352] Meanwhile, if the controller (1500) controls the AC power provided to the load according to the above-described method, the value of the current flowing to the load is adjusted, so that even if the “first operation mode” is not performed, damage to the switch or an arcing phenomenon that may occur in the antenna structure (2000) can be prevented.

[0353] For example, the controller (1500) may set the target power to be lower than a first power before plasma ignition. Then, the controller (1500) may determine an output voltage pattern in which the ratio of the freewheeling section is higher than or equal to the first ratio or the length of the freewheeling section is higher than or equal to the first length according to the lowered target power, and control the switches (S1 to S4) to output Vo according to the determined output voltage pattern. At this time, the lowered target power, the first ratio of the freewheeling section, and the first length of the freewheeling section may be determined so that the current flowing to the load is lower than or equal to the allowable current limit of the switches (S1 to S4) included in the inverter (1300), or may be values ​​determined so as to prevent an arcing phenomenon that may occur in the antenna structure (2000).

[0354] In addition, if there is a need to provide power to the load higher than the target power set low even after or before plasma ignition, the controller (1500) may set the target power high to a second power or higher. Here, the second power may be equal to or higher than the first power. In addition, the controller (1500) may determine an output voltage pattern in which the ratio of the freewheeling section is equal to or lower than the second ratio or the length of the freewheeling section is equal to or lower than the second length according to the target power set high, and control the switches (S1 to S4) to output Vo according to the determined output voltage pattern. Here, the second ratio may be equal to or lower than the first ratio, and the second length may be equal to or shorter than the first length.

[0355]

[0356] However, in the case of the "second operation mode", since both the first value (+Vin) and the second value (-Vin) are output as Vo, the amplitude of the output voltage applied to the load becomes considerably large at 2Vin, and accordingly, when the target power amount is relatively low or the current power amount is very large, the length of the freewheeling section can be set to be very long. For example, the freewheeling section included in the output voltage pattern determined according to the target power amount and / or the current power amount may not have a relatively short section as in Fig. 23(a), but may have a considerably long section as in Fig. 23(b).

[0357] If the length of the freewheeling section included in the output voltage pattern becomes significantly long, as in Fig. 23(b), the current flowing to the load within the freewheeling section may be reduced more than necessary, so that the ignited plasma may not be maintained and may disappear, or the plasma may not be ignited. Accordingly, an increase in the length of the freewheeling section beyond a predetermined maximum length may not be permitted for maintaining the plasma. In particular, since the current decays faster as the time constant of the load decreases, the length of the freewheeling section may become shorter than the predetermined maximum length as the time constant of the load decreases.

[0358]

[0359] [Method of power control using the freewheeling section in the "first operation mode"]

[0360] In order to solve the problem that the freewheeling section for controlling the power provided to the load in the "second operation mode" as described above is set to be longer than necessary, making it difficult to ignite or maintain the plasma, or that the length of the freewheeling section is not set to be longer than the predetermined maximum length, making it difficult to sufficiently lower the power, the controller (1500) can control the power provided to the load by controlling the Vo value according to an output voltage pattern including at least one freewheeling section and one powering section in the "first operation mode".

[0361] Fig. 24 shows the length of the freewheeling section set in the "second operation mode" (Fig. 24(a)) and the length of the freewheeling section set in the "first operation mode" (Fig. 24(b)) to provide the same amount of power. Referring to Fig. 24, in the "first operation mode", since the controller (1500) outputs only one of the first value and the second value as Vo, the amplitude of the output voltage applied to the load is reduced to Vin. Therefore, in order to provide the same amount of power in the "first operation mode", the controller (1500) must set a shorter freewheeling section than the freewheeling section in the "second operation mode".

[0362] Therefore, even when the target power is relatively low or the current power is very large and the time constant of the load is small, in the “first operation mode” the controller (1500) can set the length of the freewheeling section to be short, which may be more advantageous in maintaining the ignited plasma or igniting the plasma.

[0363] Therefore, considering the amount of power to be provided to the load and the length of the freewheeling section advantageous for maintaining / igniting the plasma, the controller (1500) can select a “first operation mode” or a “second operation mode” and determine an output voltage pattern including the freewheeling section according to the selected operation mode. At this time, the selection of the operation mode may be performed by a user input rather than by the controller (1500).

[0364] Below, examples of controlling power provided to a load by placing a freewheeling section within the output voltage pattern in the “first operating mode” by the controller (1500) will be examined.

[0365] FIG. 25(a) shows power control in a “first operation mode” in which the controller (1500) controls the switches (S1 to S4) of the inverter (1300) to output a first value (+Vin) and 0[V], and FIG. 25(b) shows power control in a “second operation mode” in which the controller (1500) controls the switches (S1 to S4) of the inverter (1300) to output a second value (-Vin) and 0[V].

[0366] Here, referring to FIG. 25(a) and FIG. 25(b), the powering section (P-section) in the “first operation mode” means a section in which the first value (or second value) or 0[V] is output during a half cycle of the driving frequency of the output voltage (or output power), and accordingly, the powering section in the “first operation mode” has a length equal to the half cycle of the driving frequency.

[0367] Meanwhile, the freewheeling section (F-section) in the "first operation mode" means a section in which 0[V] is continuously output for M times the half-cycle of the driving frequency of the output voltage (or output power) (M is a natural number greater than or equal to 2), and accordingly, the freewheeling section in the "first operation mode" has a length that is an integer multiple of two or more times the half-cycle of the driving frequency.

[0368] At this time, the powering section has a length equal to half a period of the driving frequency, and the freewheeling section has a length equal to an integer multiple of two or more times the half period of the driving frequency, so that the phase of the output voltage of the inverter (1300) corresponds to or is the same as the phase of the output current, thereby enabling soft switching of the switches (S1 to S4).

[0369] Meanwhile, as already explained, the freewheeling section causes the frequency component corresponding to the driving frequency of the output voltage to be attenuated or disappear when Vo is output, thereby reducing the current flowing to the load and controlling the power provided to the load.

[0370] Additionally, the controller (1500) can control the power provided to the load at predetermined cycles according to S2201 to S2213 described in FIG. 22 even in the “first operation mode”.

[0371] However, the power control operation of the controller (1500) in the “first operation mode” is different from the power control operation of the controller (1500) in the “second operation mode” described above in that it controls the operation of two switches as described below.

[0372] Specifically, in the "first operation mode", when the value output in the powering section is the first value, the controller (1500) can control the switches S1 and S2 to be selectively turned on or off so that Vo is output according to the changed / determined output voltage pattern, while keeping S3 turned on and keeping S4 turned off. Alternatively, the controller (1500) can control the switches S1 to be turned on and S2 to be turned off so that Vo is output according to the changed / determined output voltage pattern, while controlling the switches S3 and S4 to be selectively turned on or turned off.

[0373] In addition, when the value output in the powering section in the "first operating mode" is the second value, the controller (1500) can control the switches S1 and S2 to be selectively turned on or off so that Vo is output according to the changed / determined output voltage pattern, while keeping S4 turned on and keeping S3 turned off. Alternatively, the controller (1500) can control the switches S2 to be turned on and S1 to be turned off so that Vo is output according to the changed / determined output voltage pattern, while controlling the switches S3 and S4 to be selectively turned on or off.

[0374] Also, it is easy for a person skilled in the art to understand that in the "first operating mode", a powering section having the same first value (or second value) is placed immediately before and immediately after the freewheeling section.

[0375]

[0376] [Operation example of power control method using freewheeling section]

[0377] Meanwhile, examples of operation of the power control method using the "first operation mode" and "second operation mode" described above and the freewheeling section in each operation mode may be as follows.

[0378] [1] Example 1 of operation

[0379] If the target power amount set before plasma ignition is less than the power amount that can be provided to the load when power is supplied only with the powering section without the freewheeling section in the “first operation mode”, the controller (1500) performs the “power control method using the freewheeling section in the first operation mode” to control the switches of the inverter (1300) according to an output voltage pattern including at least one freewheeling section, thereby providing relatively less AC power to the load.

[0380] Alternatively, before plasma ignition, the controller (1500) may operate in the "first operation mode", and control the switches of the inverter (1300) according to a predetermined output voltage pattern to provide relatively small AC power to the load. At this time, the total length of the freewheeling section included in the predetermined output voltage pattern may be a predetermined length, and the length of each freewheeling section included in the predetermined output voltage pattern and the arrangement of each freewheeling section may also be predetermined. Then, when the plasma is ignited and the impedance of the load increases, the controller (1500) may control the total length of the freewheeling section and / or the ratio of the freewheeling section in the "first operation mode" to decrease compared to before plasma ignition. At this time, if the target power amount is set before plasma ignition, the target power amount after plasma ignition may be the same as, or smaller or larger than, the target power amount before plasma ignition. Meanwhile, the controller (1500) can operate by switching to the "second operation mode" as described above when the plasma is ignited. At this time, after switching to the "second operation mode," the controller (1500) can perform the "power control method using the freewheeling section in the second operation mode" as described in FIG. 22. Even at this time, if the target power amount was set before the plasma ignition, the target power amount after the plasma ignition may be the same as the target power amount before the plasma ignition, or may be smaller or larger.

[0381] Of course, depending on the target power amount, the controller (1500) may also control the switches of the inverter (1300) according to an output voltage pattern consisting only of a powering section without a freewheeling section in the “second operating mode”.

[0382] [2] Example 2 of the operation

[0383] The controller (1500) can configure an output voltage pattern with only a powering section without a freewheeling section in the first operation mode, and control the switches of the inverter (1300) according to the configured output voltage pattern.

[0384] And, when the plasma is ignited and the impedance of the load increases, or even before the plasma is ignited, when it is necessary to provide the load with an amount of power exceeding the amount of power that can be supplied only with the powering section in the “first operation mode,” the controller (1500) switches to the “second operation mode” and can perform the “power control method using the freewheeling section in the second operation mode” as described in FIG. 22.

[0385] [3] Example 3 of the operation

[0386] After plasma ignition, the controller (1500) can control the switches S1 to S4 of the inverter (1300) according to the “second operation mode” to maintain the plasma. At this time, the controller (1500) can select an output voltage pattern including a freewheeling section according to [a method for controlling power using a freewheeling section in the “second operation mode”], and control the switches S1 to S4 according to the selected output voltage pattern. However, if less power is needed than the power currently provided to the load (2000) depending on the plasma situation, the type and flow rate of gas injected into the plasma, the purpose, etc., and thus the length of one freewheeling section is increased to a certain level or more, the magnitude of the current flowing to the load (2000) during the freewheeling section may be reduced too much, making it difficult to maintain the plasma. In this case, the controller (1500) can control the switches S1 to S4 of the inverter (1300) by switching from the “second operation mode” back to the “first operation mode”, or can control the switches S1 to S4 according to the [power control method using the freewheeling section in the “first operation mode”] after switching to the “first operation mode”.

[0387] For example, if power is continuously supplied to the load (2000) to maintain the plasma, the impedance of the load (2000) may change due to reasons such as an increase in the plasma's actual resistance, and accordingly, the time constant of the load (2000) may decrease, causing the current to decrease more quickly in the freewheeling section. Accordingly, it is necessary to keep the freewheeling section shorter, and the controller (1500) controls the switches S1 to S4 of the inverter (1300) by switching from the "second operation mode" to the "first operation mode", or controls the switches S1 to S4 according to the [power control method using the freewheeling section in the "first operation mode"] after switching to the "first operation mode", so that the freewheeling section can be set shorter than when operating in the "second operation mode".

[0388] In other words, in order to supply the amount of power required for the load (2000), if the length of the freewheeling section must increase beyond a predetermined maximum length (or according to the time constant of the load (2000)), the controller (1500) may control the switches S1 to S4 of the inverter (1300) by switching from the "second operation mode" to the "first operation mode" to prevent the plasma from being maintained and disappearing, or may control the switches S1 to S4 according to the [power control method using the freewheeling section in the "first operation mode"] after switching to the "first operation mode".

[0389]

[0390] Meanwhile, since the above-described "Operation Example 1" and "Operation Example 2" are transitions from the "first operation mode" to the "second operation mode", and "Operation Example 3" is transitions from the "second operation mode" to the "first operation mode", it is obvious that "Operation Example 1" and "Operation Example 3" can be performed in combination, and "Operation Example 2" and "Operation Example 3" can be performed in combination. Alternatively, it is also obvious that the controller (1500) can be operated according to "Operation Example 3" after the controller (1500) operates based on the above-described [Method for transitioning from the "first operation mode" to the "second operation mode" and determining the transition time].

[0391]

[0392] [Power Control Method Using Freewheeling Section in Half-Bridge Inverter]

[0393] The inverter (1300) described in FIGS. 3 and 4 is a full-bridge inverter that provides an AC voltage to a load using four switches (S1 to S4). Meanwhile, the "first operating mode" is an example of an operating mode in which two of the four switches (S1 to S4) of the full-bridge inverter are controlled so that the output voltage value has one of two values, thereby operating like a half-bridge inverter.

[0394] That is, when an AC voltage is supplied to a load using a half-bridge inverter, the output voltage is output as one of two values. Therefore, even with a half-bridge inverter, it is possible to implement a power control method utilizing the freewheeling section in the "first operating mode." Accordingly, below, we will examine a power control method utilizing the freewheeling section in a half-bridge inverter.

[0395] Figures 26 and 27 show an RF generator (1000) including a half-bridge inverter (1800). The half-bridge inverter (1800) includes four switches (S1 to S4) included in a full-bridge inverter (1300), including switch S1 and switch S2, and switch S3 and switch S4 are connected to a capacitor (C DC ) is replaced by.

[0396] Accordingly, the controller (1500) controls the operation of the switches S1 and S2 to provide the output voltage to the load. Referring to FIG. 28, the controller (1500) can control the output voltage Vo to be (+Vin) / 2 (hereinafter, the third value) by turning on the switch S1 and turning off the switch S2. On the other hand, the controller (1500) can control the output voltage Vo to be (-Vin) / 2 (hereinafter, the fourth value) by turning on the switch S2 and turning off the switch S1. That is, the half-bridge inverter (1800) can output an output voltage having a value of (+Vin) / 2 or (-Vin) / 2.

[0397] Based on the above, let's look at examples of controlling power provided to a load using a half-bridge inverter (1800) and a freewheeling section. FIG. 29(a) shows that the controller (1500) controls the switches (S1 to S2) of the half-bridge inverter (1800) to output a fourth value in the freewheeling section, thereby controlling power provided to the load, and FIG. 29(b) shows that the controller (1500) controls the switches (S1 to S2) of the half-bridge inverter (1800) to output a third value in the freewheeling section, thereby controlling power provided to the load.

[0398] Referring to FIG. 29(a) and FIG. 29(b), the powering section (P-section) of the half-bridge inverter (1800) means a section in which the third value or the fourth value is output during a half cycle of the driving frequency of the output voltage (or output power), and accordingly, the powering section of the half-bridge inverter (1800) has a length equal to the half cycle of the driving frequency.

[0399] Meanwhile, the freewheeling section (F-section) of the half-bridge inverter (1800) means a section in which the fourth value or the third value is output for M times (M is a natural number greater than or equal to 2) the half-cycle of the driving frequency of the output voltage (or output power), and accordingly, the freewheeling section of the half-bridge inverter (1800) has a length that is an integer multiple of two or more times the half-cycle of the driving frequency. As described above, even if the third value or the fourth value is output in the freewheeling section, if the length in which the third value or the fourth value is output is longer than the half-cycle of the driving frequency, the frequency component of the driving frequency in the output voltage is attenuated or disappears. Accordingly, the effective power actually provided to the load decreases, the current flowing to the load decreases, and accordingly, the electromotive force provided to the plasma is weakened.

[0400] Accordingly, by adjusting the length for which the third or fourth value is continuously output, the power provided to the load can be controlled. Meanwhile, as described above, the powering section has a length equal to half a period of the driving frequency, and the freewheeling section has a length equal to an integer multiple of two or more times the half period of the driving frequency, so that the phase of the output voltage of the inverter (1300) corresponds to or is the same as the phase of the output current, thereby enabling soft switching of the switches (S1 to S4).

[0401] In addition, even when the half-bridge inverter (1800) is used, the controller (1500) can control the power provided to the load at predetermined cycles according to S2201 to S2213 described in FIG. 22. However, when the value output in the freewheeling section is the third value, the controller (1500) can control the switch S1 to be turned on and the switch S2 to be turned off in order to output Vo according to the changed / determined output voltage pattern. In addition, when the value output in the freewheeling section is the fourth value, the controller (1500) can control the switch S2 to be turned on and the switch S1 to be turned off in order to output Vo according to the changed / determined output voltage pattern.

[0402] Meanwhile, the half-bridge inverter can be implemented not only as the half-bridge inverter (1800) of FIGS. 26 and 27, but can also be implemented as the half-bridge inverter (1900) described in FIGS. 30 and 31. FIGS. 30 and 31 show an RF generator (1000) including a half-bridge inverter (1900) of a different type from the half-bridge inverter (1800). The half-bridge inverter (1900) of FIGS. 30 and 31 includes switch S1 and switch S2 among the four switches (S1 to S4) included in the full-bridge inverter (1300), and can be implemented in a form in which the switch S3 portion is shorted and the switch S4 portion is open, as shown in FIG. 30(a), or can be implemented in a form in which the switch S3 portion is open and the switch S4 portion is shorted, as shown in FIG. 31(a).

[0403] Meanwhile, referring to Fig. 30(b), in the case of a half-bridge inverter (1900) such as Fig. 30(a), when switch S1 is turned on and switch S2 is turned off, a voltage of a first value is output, and when switch S2 is turned on and switch S1 is turned off, 0 [V] is output. This is the same as controlling the switch S1 and switch S2 to be selectively turned on or off while controlling the switch S3 to always be turned on and the switch S4 to always be turned off in the above-described “first operation mode.”

[0404] On the other hand, referring to FIG. 31(b), in the case of the half-bridge inverter (1900) as in FIG. 31(a), when switch S2 is turned on and switch S1 is turned off, a voltage of the second value is output, and when switch S1 is turned on and switch S2 is turned off, 0 [V] is output. This is the same as controlling the switch S1 and switch S2 to be selectively turned on or off while controlling the switch S4 to always be turned on and the switch S3 to always be turned off in the above-described "first operation mode". Therefore, the half-bridge inverter (1900) of FIG. 30(a) and FIG. 30(b) according to the present disclosure can operate in the same manner as the operations described in [Method for Power Control Using a Freewheeling Section in the "First Operation Mode"] and "[1] Operation Example 1". That is, the controller (1500) can control the half-bridge inverter (1900) of FIGS. 30(a) and 30(b) in the same manner as the operations described in [Method for controlling power using a freewheeling section in the “first operation mode”] and "[1] Operation example 1". However, since the half-bridge inverter (1900) of FIGS. 30(a) and 30(b) does not have switches S3 and S4, it cannot perform the operation of switching to the second operation mode. Therefore, it should be understood that the operation after switching to the “second operation mode” in "[1] Operation example 1” is not implemented through the half-bridge inverter (1900) of FIGS. 30(a) and 30(b). Meanwhile, in the half-bridge inverter (1900) of FIGS. 30(a) and 31(a), there may be a capacitor electrically connected in series to at least one of the nodes (1610) and (1630).

[0405] By using the above half-bridge inverter (1800, 1900), similar to the "first operation mode", it is possible to set a shorter freewheeling section than the "second operation mode" to provide the same amount of power, which may be more advantageous in maintaining the ignited plasma or igniting the plasma.

[0406] In addition, even if a half-bridge inverter (1800, 1900) is used, the length and / or ratio of the freewheeling section can be increased before the plasma to prevent damage to the switch of the half-bridge inverter (1800) or arcing that may occur in the antenna structure (2000), and after the plasma ignition, the length and / or ratio of the freewheeling section can be reduced to provide power matching the target power amount to the load, thereby maintaining the plasma.

[0407]

[0408] [Examples of actions for setting the freewheeling section in "Second Operation Mode"]

[0409] As discussed above, when setting a freewheeling section using a half-bridge inverter (1800), the voltage output in the freewheeling section can be a third or fourth value. Based on this, even in the "second operating mode," the controller (1500) can control the power provided to the load by outputting the first or second value in the freewheeling section.

[0410] FIG. 32 shows various methods by which a controller (1500) sets a freewheeling section when using an inverter (1300) (i.e., a full-bridge inverter) performing “first operation mode” and “second operation mode.”

[0411] As can be seen in the first freewheeling operation of FIG. 32, the controller (1500) can control the power applied to the load by controlling the operation of the switches (S1 to S4) of the inverter (1300) so that a second value (-Vin) is output during the freewheeling period. Meanwhile, as can be seen in the second freewheeling operation of FIG. 32, the controller (1500) can control the power applied to the load by controlling the operation of the switches (S1 to S4) of the inverter (1300) so that 0 [V] is output during the freewheeling period. In addition, as can be seen in the third freewheeling operation of FIG. 32, the controller (1500) can control the power applied to the load by controlling the operation of the switches (S1 to S4) of the inverter (1300) so that a first value (+Vin) is output during the freewheeling period.

[0412] Therefore, although the freewheeling section is defined as a section that outputs 0 [V] in the above FIGS. 21 and 22 and [the power control method using the freewheeling section in the “second operation mode”], it should not be interpreted as being limited thereto, and the value output in the freewheeling section may be a first value (+Vin) or a second value (-Vin). In addition, the controller (1500) may determine the output voltage pattern by selecting any one of the first freewheeling operation, the second freewheeling operation, and the third freewheeling operation in the “second operation mode”, or may determine the output voltage pattern by combining two or more freewheeling operations among the first freewheeling operation, the second freewheeling operation, and the third freewheeling operation.

[0413] However, in order to obtain a power control effect by outputting the first value or the second value in the freewheeling section, the freewheeling section must have a length that is an integer multiple of two or more of the half-cycle of the driving frequency of the output voltage, and this is to attenuate the frequency component of the driving frequency of the output voltage, as explained above.

[0414]

[0415] Meanwhile, although the table of contents is described separately for the convenience of explanation in this specification, it should not be considered that the embodiments are described separately due to such a separated table of contents. That is, in order to solve the problem disclosed in [Previous Problem], this specification proposes to appropriately switch and use the "second operation mode" which is the switch control method of the existing inverter (1300) and the "first operation mode" which is the switch control method proposed in this specification. That is, for the convenience of understanding of the present disclosure, after explaining the "first operation mode", the conditions for switching from the "first operation mode" to the "second operation mode" and the method for determining whether the conditions are satisfied are disclosed.

[0416] In addition, the method of controlling the power applied to the load by setting the freewheeling section in the "first operation mode" and the method of controlling the power applied to the load by setting the freewheeling section in the "second operation mode" are described separately, but as described in the above-described operation example, it is obvious to those skilled in the art that the power control method in the "first operation mode" and the power control method in the "second operation mode" can be appropriately combined depending on the environment for generating plasma, the flow rate and type of the processing gas, and the application for which the plasma generating device (100) described in the present specification is used, and the scope of rights intended to be taken by the present specification should not be interpreted as being limited to each embodiment.

[0417] In addition, based on the above-described content, the overall operation process according to the configuration of the plasma generation device (100) has been described. Therefore, it should be understood that each of the separated tables of contents does not disclose a single embodiment, but rather is described to enable a person skilled in the art to more easily understand the operation process of the plasma generation device (100).

[0418]

[0419] The method according to the embodiment may be implemented in the form of program commands that can be executed through various computer means and recorded on a computer-readable medium. The computer-readable medium may include program commands, data files, data structures, etc., alone or in combination. The program commands recorded on the medium may be those specially designed and configured for the embodiment or may be those known and available to those skilled in the art of computer software. Examples of the computer-readable recording medium include magnetic media such as hard disks, floppy disks, and magnetic tapes, optical media such as CD-ROMs and DVDs, magneto-optical media such as floptical disks, and hardware devices specially configured to store and execute program commands, such as ROMs, RAMs, and flash memories. Examples of the program commands include not only machine language codes generated by a compiler, but also high-level language codes that can be executed by a computer using an interpreter, etc. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the embodiment, and vice versa.

[0420] Although the embodiments described above have been described by way of limited examples and drawings, those skilled in the art will appreciate that various modifications and variations can be made based on the above description. For example, appropriate results can still be achieved even if the described techniques are performed in a different order than described, and / or components of the described systems, structures, devices, circuits, etc. are combined or combined in a different manner than described, or are replaced or substituted with other components or equivalents.

[0421] Therefore, other implementations, other embodiments, and equivalents to the claims also fall within the scope of the claims described below.

Claims

1. In a plasma generating device that generates plasma, A discharging tube that provides a space for generating the plasma; An antenna disposed to surround the outer wall of the above discharge tube; Two input terminals receiving a DC voltage from a DC power source, wherein the two input terminals are a first input terminal and a second input terminal, Two output terminals for applying an AC voltage to the antenna, wherein the two output terminals are a first output terminal and a second output terminal, and having four switches, wherein the four switches comprise a first switch electrically interposed between the first input terminal and the first output terminal, a second switch electrically interposed between the second input terminal and the first output terminal, a third switch electrically interposed between the first input terminal and the second output terminal, and a fourth switch electrically interposed between the second input terminal and the second output terminal; An inverter that converts the DC voltage into the AC voltage according to the operation of the four switches; and A controller that controls the operation of the above four switches; The above controller, In order to convert the DC voltage into a first AC voltage, the operation of the first switch is turned on and the operation of the second switch is turned off, and the operation of each of the third switch and the fourth switch is controlled to be selectively turned on or off. It is determined whether the plasma is generated in an amount greater than a reference amount inside the discharge tube by the first AC voltage applied to the antenna, Based on the generated plasma being greater than or equal to the reference amount, the operation of each of the first switch, the second switch, the third switch, and the fourth switch is controlled to be selectively turned on or off so that the direct current voltage is converted into a second alternating current voltage. Plasma generator.

2. In paragraph 1, The above controller, The second AC voltage is applied to the antenna to control the operation of the first switch, the second switch, the third switch, and the fourth switch so that the generated plasma is maintained. Plasma generator.

3. In paragraph 1, The difference between the maximum and minimum values ​​of the second AC voltage is twice the difference between the maximum and minimum values ​​of the first AC voltage. Plasma generator.

4. In paragraph 1, The above controller, Based on the fact that the amount of power applied to the inverter is less than the first threshold value, it is determined that the generated plasma is greater than the reference amount. Plasma generator.

5. In paragraph 4, The above controller, The power amount is calculated using the DC voltage applied to the inverter and the input current flowing to the inverter. Plasma generator.

6. In paragraph 1, The above controller, Assuming a virtual signal that shifts a control signal controlling at least one of the above four switches by a predetermined amount of time, Determine the delay time between the output current of the inverter and the virtual signal, If the above delay time is less than or equal to the reference value, it is determined that the generated plasma is greater than or equal to the reference amount. Plasma generator.

7. In paragraph 6, The above controller, When the inverter applies the first AC voltage to the antenna, the operation of each of the third switch and the fourth switch is controlled so that the delay time exceeds the reference value. Plasma generator.

8. In a control method for controlling four switches included in an inverter of a plasma generating device, - The inverter has a first switch electrically interposed between a first input terminal and a first output terminal, a second switch electrically interposed between a second input terminal and the first output terminal, a third switch electrically interposed between the first input terminal and the second output terminal, and a fourth switch electrically interposed between the second input terminal and the second output terminal. The first input terminal and the second input terminal receive a DC voltage from a DC power source, and the first output terminal and the second output terminal apply an AC voltage to an antenna arranged to surround the outer wall of the discharge tube. The operation of the first switch is turned on and the operation of the second switch is turned off, so that the DC voltage is converted into the first AC voltage, and the operation of each of the third switch and the fourth switch is controlled to be selectively turned on or off; Determining whether the plasma is generated in an amount greater than a reference amount inside the discharge tube by the first AC voltage applied to the antenna; Based on the generated plasma being greater than or equal to the reference amount, the operation of each of the first switch, the second switch, the third switch, and the fourth switch is controlled to be selectively turned on or off so that the direct current voltage is converted into a second alternating current voltage; How to control the switch.

9. In paragraph 8, Controlling the operation of each of the first switch, the second switch, the third switch and the fourth switch to be selectively turned on or off; The second AC voltage is applied to the antenna, and the operation of the first switch, the second switch, the third switch, and the fourth switch is controlled so that the generated plasma is maintained; How to control the switch.

10. In paragraph 8, The difference between the maximum and minimum values ​​of the second AC voltage is twice the difference between the maximum and minimum values ​​of the first AC voltage. How to control the switch.

11. In paragraph 8, Determining whether the above plasma has been generated in a reference amount; Based on the fact that the amount of power applied to the inverter is less than the first threshold value, it is determined that the generated plasma is greater than or equal to the reference amount; How to control the switch.

12. In paragraph 11, Determining whether the above plasma has been generated in a reference amount; Further comprising calculating the amount of power by using the DC voltage applied to the inverter and the input current flowing to the inverter; How to control the switch.

13. In paragraph 8, Determining whether the above plasma has been generated in a reference amount; Assume a virtual signal that shifts a control signal controlling at least one of the above four switches by a predetermined amount of time; Determining the delay time between the output current of the inverter and the virtual signal; and If the delay time is less than or equal to the reference value, it is determined that the generated plasma is greater than or equal to the reference amount; How to control the switch.

14. In paragraph 13, The operation of the first switch is controlled to be turned on and the operation of the second switch is controlled to be turned off, while the operation of each of the third switch and the fourth switch is controlled to be selectively turned on or off; Controlling the operation of each of the third switch and the fourth switch so that the delay time exceeds the reference value; How to control the switch.

Images