WO2014007472A1

WO2014007472A1 - Plasma generation apparatus and plasma generation method

Info

Publication number: WO2014007472A1
Application number: PCT/KR2013/004682
Authority: WO
Inventors: Young-Gwan LEE; Sae-Hoon Uhm; Young-Rok Kim; Kyu-Hun Lee
Original assignee: Plasmart Inc.
Priority date: 2012-07-03
Filing date: 2013-05-29
Publication date: 2014-01-09

Abstract

Provided is a plasma generation apparatus which includes a toroidal-type magnetic core to form a closed loop, a chamber surrounding one section of the magnetic core and including a discharge space in which a closed loop is formed, an induction coil disposed to surround the other section of the magnetic core, AC power source supplying power to the induction coil to allow an induced electromotive force generated by the magnetic core to generate toroidal plasma in the discharge space, and a groove formed on an inner surface of the discharge space. The induction coil constitutes a primary coil of a transformer, and the toroidal plasma generated in the discharge space forms a secondary coil of the transformer.

Description

PLASMA GENERATION APPARATUS AND PLASMA GENERATION METHOD

The present invention relates to plasma generation apparatuses and, more particularly, to toroidal plasma generation apparatuses.

Plasma discharges can use dissociated gases to produce activated gases containing ions, free radicals, atoms, and molecules. Activated gases are used for numerous industrial and scientific applications including processing materials such as semiconductor wafers, powders, and other gases. The parameters of plasma and the conditions of the exposure of the plasma to the processed material vary widely depending on the application.

A toroidal plasma generation apparatus including a swirl injector is disclosed in U.S. Patent No. 6,388,226. The swirl injector enhances the interaction between an injection gas and plasma to increase a flow rate that is operated. A large toroidal plasma generation apparatus is disclosed in WO2009/051597. However, in U.S. Patent No. 6,388,226 and WO2009/051597, a gas flow path in a plasma channel is smoothly formed. Moreover, in U.S. Patent No. 6,388,226 and WO2009/051597, ignition discharge is performed using an ignition electrode. Therefore, it is difficult to perform the ignition discharge at high pressure above several Torr or a high flow rate.

Although ignition discharge is successfully performed, the discharge is often not maintained during a process. Accordingly, there is a need for a novel toroidal plasma generation apparatus that is capable of stably performing ignition discharge at higher flow rate or pressure, enhancing high plasma stability, and increasing a gas-plasma interaction and a dissociation rate.

Embodiments of the present invention provide a remote plasma generation apparatus in which a groove is formed on a surface of a discharge space in a toroidal plasma device to increase a dissociation rate and an etch rate.

Embodiments of the present invention also provide a remote plasma generation apparatus in which ignition discharge uses microwave plasma and main discharge uses inductively-coupled plasma to easily perform the ignition discharge, achieve discharge stability, and process a high flow rate.

A plasma generation apparatus according to an embodiment of the present invention may include a toroidal-type magnetic core to form a closed loop; a chamber surrounding one section of the magnetic core and including a discharge space in which a closed loop is formed; an induction coil disposed to surround the other section of the magnetic core; AC power sources supplying power to the induction coil to allow an induced electromotive force generated by the magnetic core to generate toroidal plasma in the discharge space; and a groove formed on an inner surface of the discharge space. The induction coil constitutes a primary coil of a transformer, and the toroidal plasma generated in the discharge space forms a secondary coil of the transformer.

In an exemplary embodiment, the discharge space may include a straight portion and a curved portion, and the groove may be formed on an inner surface of the chamber to surround a moving direction of the discharge space along the straight portion.

In an exemplary embodiment, the groove may have a helical shape, a shape of straight line formed in the moving direction of the discharge space or a circular shape.

In an exemplary embodiment, an interval between adjacent grooves may be several millimeters to several centimeters.

In an exemplary embodiment, the plasma generation apparatus may further include a microwave hole formed at the chamber to be connected to the discharge space to externally provide a microwave to the discharge space; an insulating window disposed around the microwave hole to allow a microwave to pass therethrough; a waveguide to provide a microwave to the insulating window; and a waveguide hole formed at the waveguide to radiate a microwave propagating in the waveguide and provide the radiated microwave to the microwave hole.

In an exemplary embodiment, the discharge space may include a straight portion and a curved portion, and a length direction of the waveguide may be disposed in an extending direction of the straight portion of the discharge space.

In an exemplary embodiment, the plasma generation apparatus may further include at least one of at least one impedance matching stub mounted on the waveguide; and an optical sensor disposed at the waveguide in a direction where the insulating window views the waveguide.

In an exemplary embodiment, the microwave hole and the waveguide hole may be circular.

In an exemplary embodiment, the microwave hole may be disposed in the center of the straight portion.

In an exemplary embodiment, the microwave hole may be disposed at the curved portion.

In an exemplary embodiment, the chamber may include a first leg having a first through-hole formed in a first direction; a second leg having a first connection path formed to be continuously connected to the first through-hole; a third leg having a second through-hole continuously connected to the first connection path and formed in the first direction; and a fourth leg having a second connection path formed to be continuously connected to the second through-hole. The first through-hole, the first connection path, the second through-hole, and the second connection path may form the discharge space.

In an exemplary embodiment, the second leg may include a first path formed to be connected to one end of the first through-hole; a second path formed to be connected to one end of the second through-hole; and a third path formed in a second direction perpendicular to the first direction to connect the first path and the second path to each other, and the first path, the third path, and the second path may be continuously connected to form a first connection path. The fourth leg may include a first path formed to be connected to the other end of the first through-hole; a second path formed to be connected to the other end of the second through-hole; and a third path formed in a second direction perpendicular to the first direction to connect the first path and the second path to each other, and the first path, the third path, and the second path may be continuously connected to form a second connection path.

In an exemplary embodiment, each of the second and fourth legs may include a support plate and a cover plate disposed on the support plate. The support plate may include a concave portion depressed on its top surface. The half of the third path may be formed on a bottom surface of the concave portion in the second direction. The cover plate may include a protrusion protruding on its lower surface. The other half of the third path may be formed on a bottom surface of the protrusion in the second direction.

In an exemplary embodiment, the discharge space may comprise first to fourth straight portions and first to fourth curved portions. The discharge space may further include a gas supply path connected to the first curved portion; and a gas exhaust path connected to the third curved portion diagonally disposed at the first curved portion.

In an exemplary embodiment, the plasma generation apparatus may further include a gas injector inserted in the gas supply path to provide a swirl flow and adapted to supply a supply gas to two different paths.

In an exemplary embodiment, the discharge space may include first to fourth straight portions and first to fourth curved portions. The discharge space may further include a first gas supply path connected to the first curved portion; a second gas supply path formed at the first curved portion to be perpendicular to the first gas supply path; and a gas exhaust path connected to the third curved portion diagonally disposed at the first curved portion.

In an exemplary embodiment, the discharge space may include first to fourth straight portions and first to fourth curved portions. The discharge space may further include a first gas supply path connected in the center of the second straight portion; and a gas exhaust path formed at the fourth straight portion disposed alongside of the second straight portion.

In an exemplary embodiment, the discharge space may include first to fourth straight portions and first to fourth curved portions. The discharge space may further include a first gas supply path connected to the first curved portion; a second gas supply path connected to the second curved portion; and a gas exhaust path formed at the fourth straight portion.

In an exemplary embodiment, the chamber may include a first leg having a first through-hole; a first elbow duct connected to one end of the first through-hole; a second leg having a second through-hole connected to the first elbow duct; a second elbow duct connected to the second through-hole; a third leg having a third through-hole connected to the second elbow duct; a third elbow duct connected to the third through-hole; a fourth leg having a fourth through-hole connected to the third elbow duct; and a fourth elbow connecting the fourth through-hole and the first through-hole to each other.

A plasma generation apparatus according to an embodiment of the present invention can increase plasma density, a dissociation rate or an etch rate by forming a groove in a discharge space in which a closed loop is formed. In addition, the plasma generation apparatus uses microwave plasma for ignition discharge and inductively-coupled plasma for main discharge to easily perform the ignition discharge and significantly enhance discharge stability and processing speed.

These and other aspects of the present invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a conceptual diagram of a plasma generation apparatus according to an embodiment of the present invention;

FIG. 2 is a cut-away perspective view under the state where a plasma generation apparatus according to an embodiment of the present invention is exploded.

FIG. 3 is a cross-sectional view taken along an x-y plane of the plasma generation apparatus in FIG. 2;

FIGS. 4 to 9 are cross-sectional views of plasma generation apparatuses according to other embodiments of the present invention;

FIGS. 10 and 11 illustrate grooves according to an embodiment of the present invention; and

FIG. 12 shows a test result according to an embodiment of the present invention.

A toroidal plasma generation apparatus using an ignition electrode suffers from problems such as contamination caused by sputtering of the ignition electrode, vacuum leak occurring at a portion of the ignition electrode, and ignition discharge failure.

Accordingly, there is a need for a novel toroidal plasma generation apparatus which is capable of overcoming the above-mentioned problems and increasing gas-plasma interaction and dissociation rate of a process gas.

A toroidal plasma generation apparatus according to an embodiment of the present invention adopts a structure having a groove formed on an inner surface of a discharge space. Thus, the toroidal plasma generation apparatus increased an etch rate about two times under the same condition as compared to a structure having a smooth surface of a discharge space. This enables the toroidal plasma generation apparatus to reduce a process time in half. It is supposed that the increased etch rate is caused by reduction of a contact area between toroidal plasma and an inner wall of a chamber. In addition, it is supposed that the increased etch rate is caused by variation of a flow pattern of injection gas.

In the toroidal plasma generation apparatus, a microwave discharge device is used as an ignition device. If plasma is generated by a microwave discharge device using an insulating tube, a microwave plasma generation apparatus is great in structural volume and a part such as waveguide is high in cost. Moreover, since microwave power is spatially concentrated to be supplied to the insulating tube, the insulating tube must be replaced periodically. Therefore, it is difficult to maintain the toroidal plasma generation apparatus.

However, a microwave ignition device used in an embodiment of the present invention does not use an insulating tube but uses a dielectric window. The microwave ignition device does not require high-output microwave power, uses a low-output microwave generator of several kilowatts or less used in a microwave oven, and may significantly decrease in volume by optimizing a structure of a waveguide or the like. In addition, microwave impedance matching may be achieved using the optimized structure. Since the microwave ignition device is used for ignition in ignition discharge, an insulator window is not excessively exposed to microwave plasma. The insulator window is not in direct contact with a discharge area in which main discharge occurs. Since plasma generated by the main discharge is also not directly exposed to the insulator window, periodical replacement of the insulator window is not required.

The microwave ignition device may easily perform ignition discharge at pressure of several milliTorr (mTorr) to an atmospheric pressure, as compared to an ignition electrode. Thus, the microwave ignition device may reduce the possibility of ignition discharge failure, as compared to the ignition electrode. Since a high voltage is not locally applied, a sputtering problem is less severe and thus a contamination problem is also less severe. Moreover, since a dielectric window is used, vacuum maintenance is easily done. In terms of structure, a waveguide is disposed alongside of the chamber to suppress volume increase caused by the waveguide.

Since a pressure or flow rate of a chamber is usually determined, microwave impedance matching depending on time is not necessary. Thus, impedance matching stub may be removed and the structure design of an optimized waveguide having an aperture coupled cavity structure may be realized to remove a dummy load and a reflected wave measuring unit. A microwave may be radiated to the discharge space through a microwave hole formed at the chamber via a waveguide slit or an aperture formed at the waveguide. Accordingly, since an electromagnetic wave flows into a toroidal discharge space through a dielectric window by using a minimum space, a structure of the dielectric window is simpler than a structure using a discharge tube. As a result, a process speed may be improved using a groove and stable ignition discharge may be provided through microwave ignition discharge. Moreover, since a capactive electrode is not used, occurrence of arc may be suppressed. A sputtering problem, a leak problem, and a contamination problem may be suppressed to enhance process stability and increase process reproducibility. In addition, the lifetime of products may increase.

A plasma generation apparatus according to an embodiment of the present invention may be used in an etching process, a cleaning process of a process chamber, a deposition process, a surface treating process, and the like. The plasma generation apparatus may be used to supply active species to a process chamber in which an etch process, a deposition process or a surface treating process is performed. Furthermore, the plasma generation apparatus may be used to supply active species for cleaning an inner wall of a process chamber in which a deposition process has been performed.

The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the present invention are shown. However, the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. In the drawings, elements or components are exaggerated for clarity. Like numbers refer to like elements throughout.

FIG. 1 is a conceptual diagram of a plasma generation apparatus according to an embodiment of the present invention.

Referring to FIG. 1, a toroidal plasma generation apparatus 100 includes toroidal-type

magnetic cores

142 and 144 to form a closed loop, a chamber 110 surrounding one section of the

magnetic cores

142 and 144 and including a discharge space 101 in which a closed loop is formed, induction coils 163 and 165 disposed to surround the other section of the

magnetic cores

142 and 144,

AC power sources

162 and 164 supplying power to the induction coils 163 and 165 to allow an induced electromotive force generated by the

magnetic cores

142 and 144 to generate toroidal plasma in the discharge space 101, and a groove 115 formed on an inner surface of the discharge space 101. The induction coils 163 and 165 constitute a primary coil of a transformer, and the toroidal plasma generated in the discharge space 101 forms a secondary coil of the transformer.

The induction coils 163 and 165 surround one section of the

magnetic cores

142 and 144, and the discharge space 101 surround the other section of the

magnetic cores

142 and 144. When AC current flows to the induction coils 163 and 165, an induced electromotive force is generated in the discharge space 101. The discharge space 101 is filled with the toroidal plasma. Since the plasma is conductive, it acts as a secondary coil of a transformer. Therefore, effective plasma discharge may be maintained. Energy of the plasma may be transferred to the inner wall of the chamber 110 to be consumed as heat. Therefore, it is necessary to minimize interaction between the plasma and the inner wall of the chamber 110. Particularly, when a frequency is a low frequency, skin depth is great and thus the low frequency may pass through the conductive chamber 110 to establish an induced electric field in the discharge space 101. The groove 115 is formed on the inner wall of the chamber 110 to prevent loss resulting from diffusion of the plasma to the inner wall of the chamber 110 or loss resulting from migration by the electric field. Thus, an etch rate of a silicon substrate inside a process chamber 172 connected to the chamber 110 through a pipe increased two times higher than a chamber having a smooth inner wall. The groove 115 blocks current flow caused by the induced electric field and thus plasma may not be generated in a valley of the groove 115. Since charged particles are accelerated along the induced electric field and the discharge space, the groove 115 may exhibit an effect to separate the plasma at regular intervals on the inner wall. Accordingly, the probability that the accelerated charged particles collide against the inner wall of the chamber 110 is reduced. Thus, it is supposed that an area directly contacting the plasma was reduced to increase discharge efficiency and etch rate.

AC current flowing to the induction coils 163 and 165 forms a magnetic flux at the

magnetic cores

142 and 144, and the magnetic flux generates toroidal-type inductively coupled plasma in the discharge space 101 of the chamber 110. When the discharge space 101 does not form a closed loop, discharge efficiency is significantly reduced.

The chamber 110 may be a conductor. An insulating spacer (not shown) may be disposed to block induced current generated in the chamber 110. The chamber 110 may form a single closed path surrounding one section of the

magnetic cores

142 and 144. The chamber 110 may form a toroidal-type discharge space 101. The chamber 110 is formed of a plurality of parts electrically insulated to block the induced current. A section of the discharge space 101 may be circular or elliptical. The section of the discharge space 101 along the discharge space may be in the form of race track.

The chamber 110 may be cooled by a coolant. The internal discharge space 101 of the chamber 110 may be coated with an insulator. For example, the chamber 110 may be made of aluminum and the discharge space 101 may be anodized to be coated with aluminum oxide.

An inner surface of the chamber may include the groove 115. The groove 115 blocks a path of induced current generated by the induced electric field. Thus, plasma generated in the discharge space 101 may reduce an area contacting the inner surface of the chamber 110. As a result, it is supposed that an interaction between the plasma and a gas and a dissociation rate of the gas increases.

The groove 115 may be helical or circular along the surface of the discharge space. A corner of the groove 115 may be rounded. The rounded corner of the groove 115 may suppress arc discharge. The groove 115 may have the shape of circular bellows or spiral bellows. The groove 115 may be formed on the inner surface of the chamber 110. An interval or pitch between adjacent grooves may be several millimeters to several centimeters. Depth of the groove 115 may be several millimeters. The grooves may be repeatedly arranged at regular intervals. The groove 115 may be disposed on an inner surface of the discharge space 101 surrounded by the

magnetic cores

142 and 144. The groove 115 may be linear, helical or circular.

The chamber 110 may include a gas supply path 32 and a gas exhaust path 33. The gas supply path 32 and the gas exhaust path 33 may be connected to the discharge space 101. The gas supply path 32 allows an ignition discharge gas and a process gas to be supplied to the discharge space 101. The ignition discharge gas may include at least one of an inert gas and a nitrogen gas. The process gas may include at least one of a fluorine-containing gas and an oxygen-containing gas. The gas exhaust path 33 may exhaust a process gas dissociated by plasma. A section of the gas supply path 32 or a section of the gas exhaust path 33 may be identical to that of the discharge space.

A gas injector (not shown) may be disposed to be inserted into the gas supply path 32. The gas injector may provide a swirl flow to the discharge space 101. Thus, a supply gas may provide the swirl flow. The swirl flow may provide mixture of plasma and the supply gas to significantly increase a dissociation rate or plasma density. The groove 115 may be helically formed to continuously maintain a spiral flow provided by the gas injector. Thus, the supply gas may maintain the spiral flow in the discharge space. The spiral flow may provide mixture of plasma and the supply gas.

The chamber 110 may include a microwave hole (not shown). The microwave hole may provide an external microwave to the discharge space 101. The microwave hole may be closed by the dielectric window 151. The dielectric window 151 is made of a material allowing a microwave to pass therethrough and maintaining vacuum. The material of the dielectric window 151 may be one selected from the group consisting of quartz, alumina, sapphire, aluminum nitride, aluminum oxide, and a combination thereof. The dielectric window 151 may be disk-shaped. The dielectric window 151 may have a double structure. The dielectric window 151 may include a first dielectric window and a second dielectric window that are sequentially stacked. The first dielectric window may be exposed to the discharge space, and the second dielectric window may be exposed to a waveguide. The first dielectric window may be made of sapphire, and the second dielectric window may be made of ceramic. Thus, cost may be reduced and durability may be improved.

A waveguide 153 has a waveguide hole (not shown) to radiate a microwave. The microwave is transmitted to the discharge space 101 through a microwave hole formed at the chamber 110 through the waveguide hole and the dielectric window 151. The microwave hole may form a new waveguide. The waveguide hole and the microwave hole may be circular. The dielectric window 151 may be disk-shaped. The waveguide 153 may have a TE mode or a TM mode. The waveguide 153 may be a rectangular waveguide.

The microwave transmitted into the chamber 110 generates microwave plasma. A support block (not shown) may be disposed to support the dielectric window 151 and connect the waveguide 153 to the chamber 110.

The microwave plasma is generated by a locally strong electrostatic wave. Accordingly, an area contacting the microwave plasma may be heated. In particular, when a fluorine-containing gas is discharged, the heated dielectric window 151 may be readily etched. The support block may be disposed between the waveguide 153 and the dielectric window 151 to cool the dielectric window 151. The support block may be made of a material, such as aluminum, having superior thermal conductivity. The support block may be cooled by a coolant or pressurized air. The dielectric window 151 may be disposed on an outer surface of the chamber 110 and thus may not be in direct contact with the discharge space.

A microwave generator 155 may supply a microwave to the waveguide 116. A frequency of the microwave generator 155 may be 1 GHz to 20 GHz. Power of the microwave generator 155 may be several watts (W) to several kilowatts (kW). The microwave generator 155 may be a magnetron of 2.45 GHz. A magnetron used in a household microwave oven is low in cost and small in size. Accordingly, the microwave generator 155 may generate microwave plasma with low cost.

A tuner 154 for impedance matching may be mounted on the waveguide 153. The tuner 154 may be a stub tuner. A directional coupler 157 may be mounted on the waveguide 153 to extract some of a reflected wave or a propagating wave. Thus, incident power and reflected power may be extracted. A dummy load 156 may consume the reflected wave. The dummy load 156, the directional coupler 157, and the tuner 154 may be removed for a simple structure.

The

magnetic cores

142 and 144 may have a toroidal shape to form a closed loop. A section of the

magnetic cores

142 and 144 may be circular or quadrangular. The

magnetic cores

142 and 144 may be transformed from toroid to have a straight portion and a curved portion. The shape of the

magnetic cores

142 and 144 may depend upon a structure of the chamber 110 of a wound portion.

The

magnetic cores

142 and 144 may be ferrite or nano-crystalline cores. In the case of a nano-crystalline core, permeability may be 15000 or more. Thus, the

magnetic cores

142 and 144 may decrease in volume and heat loss caused by hysteresis may be reduced. The

magnetic cores

142 and 144 may form a closed loop. Thus, a magnetic flux may be concentrated in the

magnetic cores

142 and 144. The

magnetic cores

142 and 144 may be divided into a plurality of parts to reduce heat loss caused by eddy current of the

magnetic cores

142 and 144. The

magnetic cores

142 and 144 may be disposed to surround one section of the discharge space of the chamber 110.

The induction coils 163 and 165 may be made of a material, such as copper or silver, having superior conductivity. The induction coils 163 and 165 have a wide band shape. The induction coils 163 and 165 may be coated with an insulator to be insulated from the chamber 110.

The induction coils 163 and 165 may be connected to the

AC power sources

162 and 164. A frequency of the

AC power sources

162 and 164 may be 10 kHz to 10 MHz. Power of the

AC power sources

162 and 164 increases in proportion to processing capacity, but may be usually several kilowatts (kW) to hundreds of kilowatts (kW).

AC current flowing to the induction coils 163 and 165 induce a magnetic flux to the

magnetic cores

142 and 144. A timing-varying magnetic flux induces an induced electric field in a direction of surrounding one section of the

magnetic cores

142 and 144. The discharge space 101 may be disposed in a direction of the induced electric field. Thus, the induced electric field generates inductively coupled plasma in a discharge space inside the chamber 122. In addition, the induced electric field generates heat through ohmic heating inside a conductive chamber. The chamber 110 may be made of a plurality of electrically insulated parts to reduce the ohmic heating. Particularly, by the skin effect, a frequency of the induced electric field is preferably less than several MHz.

A pressure of the chamber 110 may be hundreds of milliTorr (mTorr) to hundreds of Torr. It is difficult for inductively coupled plasma to maintain discharge in a process gas of tens of Torr or higher. However, a plasma generation apparatus according to an embodiment of the present invention may maintain discharge at a pressure of tens of Torr or more by using a process gas with the help of microwave discharge.

A controller 182 may control the

power sources

162 and 164 by receiving a measurement result of an optical sensor 158 and determining whether ignition discharge occurs. The controller 182

controls valves

184 and 183 to supply a gas to the chamber 110 and exhaust the gas.

A plasma generation apparatus according to an embodiment of the present invention includes a discharge space with a groove which may increase a dissociation rate or an etch rate about two times higher than a smooth discharge space. A microwave ignition discharge device may readily perform ignition discharge. Accordingly, an AC power source does not need a separate high voltage generator for operating an ignition electrode. Since the AC power source does not include a circuit for operating an ignition electrode, it may reduce an operating voltage. Thus, the price of the AC power source may be reduced.

The gas exhaust path 33 may provide a dissociated process gas to a process container 172. The process container 172 may perform an etch process, a deposition process, an ashing process, a cleaning process, and the like. In the case of the deposition process, the process container 172 receives a separate deposition process gas. The process container 172 may include a substrate 173 and a substrate holder 174. The substrate 173 may be a semiconductor substrate, a glass substrate, a plastic substrate or a metal substrate. When the process container 172 is contaminated, the plasma generation apparatus may provide a dissociated process gas to the process container 172 to perform a cleaning process for cleaning the inside of the process container 172.

As a substrate increases in size, the process container 172 increases in volume. Accordingly, the plasma generation apparatus may supply a dissociated process gas of several SLM (standard liter per minute) to hundreds of SLM to the process container 172.

The ignition discharge gas may be a nitrogen gas or an inert gas such as argon gas for readily performing ignition discharge. The process gas may be a fluorine-containing gas or an oxygen gas.

More specifically, the process gas may be NF₃, and the ignition discharge gas may be an argon gas. A dissociated gas dissociated by plasma inside the chamber 110 may be supplied into a process chamber to perform a cleaning process.

A conventional toroidal plasma generation apparatus perform discharge at a low pressure using an ignition discharge gas and introduces a process gas into a chamber while increasing a pressure. Thus, long waiting time is required until the process gas is dissociated.

However, a plasma generation apparatus according to an embodiment of the present invention may simultaneously introduce a process gas and an ignition discharge gas at a high pressure. A ratio of the process gas to the ignition discharge gas may be 5 percent or more. Microwave discharge is easily and stably performed even at a high pressure. Accordingly, a process gas may be discharged by controlling a flow rate of the process gas and the ignition discharge gas. Thus, waiting time is significantly reduced.

Although a conventional toroidal plasma generation apparatus uses a capacitively coupled electrode for ignition discharge, capacitively coupled plasma is readily discharged as an area increase. There is a limitation in increasing an area of a capacitively coupled electrode. Increase of an area of a capacitively coupled electrode induces sputtering. In addition, there is a requirement for a high-voltage power source that induces a separate high voltage to generate capacitively coupled plasma. The high-voltage power source requires additional cost. The capacitively coupled plasma is vulnerable to arc due to use of a strong electric field. Even when inductively coupled plasma is generated, a capacitively coupled electrode may generate an arc. Once an arc is generated, generation of the arc is repeated to significantly reduce the lifetime of equipment.

However, since ignition discharge according to the present invention uses a microwave, an arc is not generated. Moreover, there is no sputtering problem that occurs at capacitively coupled plasma.

Microwave ignition discharge may be performed only by a microwave generator and a waveguide. If the microwave generator is a household magnetron, the cost of equipment for microwave discharge is low.

FIG. 3 is a cross-sectional view taken along an x-y plane of the plasma generation apparatus in FIG. 2.

Referring to FIGS. 2 and 3, a plasma generation apparatus 100a includes toroidal-type

magnetic cores

142 and 144 to form a closed loop, a chamber 110 including a discharge space 101 surrounding one section of the

magnetic cores

142 and 144 and forming the closed loop, induction coils 163 and 165 disposed to surround the other section of the

magnetic cores

142 and 144,

AC power sources

162 and 164 supplying power to the induction coils to allow an induced electromotive force generated by the

magnetic cores

142 and 144 to generate toroidal plasma in the discharge space 101, and a groove formed on an inner surface of the discharge space 101. The induction coils 163 and 165 constitute a primary coil of a transformer, and the plasma generated in the discharge space 101 forms a secondary coil of the transformer.

The

magnetic cores

142 and 144 may have an opening that penetrates the center of a rectangular parallelepiped. Accordingly, the

magnetic cores

142 and 144 may have a toroidal shape. A portion of the chamber 110 may be inserted into the opening, and the chamber 110 may be formed to surround the opening. Inside the chamber 110, the discharge space 101 may be formed in a moving direction of the chamber 110. The discharge space 101 may be toroidal.

The

magnetic cores

142 and 144 may include a first magnetic core 142 and a second magnetic core 144. The first magnetic core 142 may be disposed to surround one section of the chamber 110, and the second magnetic core 144 may be disposed to surround the other section of the chamber 110. The first induction coil 163 may be disposed to surround one section of the first magnetic core 142, and the second induction coil 165 may be disposed to surround one section of the second magnetic core 144.

The chamber 110 may include a discharge space 101 in which a closed loop is formed. The discharge space 101 may have a similar shape to a toroidal shape.

The chamber 110 may include first to fourth legs 111~114. The first leg 111 may be disposed to extend in the x-axis direction, and the third leg 113 may be spaced in the y-axis direction to be disposed alongside of the first leg 111. The second leg 112 may be disposed to extend in the y-axis direction, and the fourth leg 114 may be spaced in the x-axis direction to be disposed alongside of the second leg 112.

The first leg 111 may include a first through-hole 11 formed in the first direction (x-axis direction). The second leg 112 may include a connection path 12 formed to be continuously connected to the first through-hole 11. The third leg 113 may be continuously connected to the first connection path 12 and include a second through-hole 13 formed in the first direction. The first through-hole 11, the first connection path 12, the second through-hole 13, and the second connection path 14 may be continuously connected to form the discharge space 101.

The first leg 111 may extend in the first direction in the form of a square pillar. The first through-hole 11 may have a shape of through-hole penetrating the central axis of the first leg 111. A plurality of grooves 115 may be formed around the first through-hole 11. The groove 115 may be circular or spiral.

The third leg 113 may have the shape of a square pillar, and the second through-hole 13 may have the shape of a cylinder penetrating the central axis of the third leg 113. A plurality of grooves 115 may be formed around the second through-hole 13. The groove 115 may be circular or spiral.

The second leg 112 may have the shape of a rectangular pillar extending in the y-axis direction. The second leg 112 includes a first path 12a connected to one end of the first through-hole 11 and formed in a first direction, a second path 12b connected to one end of the second through-hole 13 and formed in the first direction, and a third path 12c connecting the first path 12a and the second path 12b to each other and formed in a second direction perpendicular to the first direction. The first path 12a, the third path 12c, and the second path 12b are continuously connected to form the first connection path 12.

The second leg 112 may include a support plate 112b and a cover plate 112a disposed on the support plate 112b. The support plate 112b may include a concave portion 112c depressed on its top surface. The half of the third path 12c may be formed on a bottom surface of the concave portion 112c in the second direction (y-axis direction). The cover plate 112a may include a protrusion 112d protruding on its bottom surface, and the other half of the third path 12c may be formed on a bottom surface of the protrusion 112d in the second direction.

The fourth leg 114 may have the shape of a rectangular pillar extending in the y-axis direction. The fourth leg 114 includes a first path 14a connected to the other end of the first through-hole 11 and formed in the first direction, a second path 14b connected to the other end of the second through-hole 13 and formed in the first direction, and a third path 14c connecting the first path 14a and the second path 14b to each other and connected in a second direction perpendicular to the first direction. The first path 14a, the third path 14c, and the second path 14b are continuously connected to form the second connection path 14.

The fourth leg 114 may include a support plate 114b and a cover plate 114a disposed on the support plate 114b. The support plate 114b may include a concave portion 112c depressed on its top surface. The half of the third path 14c may be formed on a top surface of the concave portion 114c in the second direction (y-axis direction). The cover plate 114a may include a protrusion 114d protruding on its top surface, and the other half of the third path 14c may be formed on a top surface of the protrusion 112d in the second direction.

The second leg 112 may include the gas supply path 32 that is connected to a joining portion of the first path 12a and the third path 12c, penetrates one side surface of the second leg 112, and is disposed at a position that the third path 12c views. The gas supply path 32 may be disposed in the second direction.

A first flange 132 may be coupled to the one side surface of the second leg 112 at an inlet of the gas supply path 32. The gas injector 139 may be coupled to the first flange 132 to provide a swirl to a supply gas. The gas injector 139 may have a plurality of holes and supply a spirally flowing gas to the discharge space 101. The gas injector 139 may distribute a gas to the first path 12a and the third path 12c. The end of the gas injector 139 may be inserted to be in contact with a curved portion of the discharge space 101. The end of the gas injector 139 may have an inclined surface of 45 degrees. Thus, a gas injected from the inclined surface may be distributed to the first path 12a and the third path 12c while having a swirl.

The fourth leg 114 may include the gas exhaust path 33 that is connected to a joining portion of the second path 14b and the third path 14c, penetrates the other side surface of the fourth leg 114, and is formed at a position that the third path 14c views. The gas exhaust path 33 may be disposed in the second direction.

The second flange 133 may be coupled to the other side surface of the fourth leg 114 at an outlet of the gas exhaust path 33. The third flange 135 may be coupled to the second flange 133 to exhaust a dissociated gas to the outside.

An insulating spacer 119 may be inserted in an outer circumferential surface of one end of the first leg 111 to insulate the first leg 111 and the second leg 112 from each other. The insulating spacer 119 may be inserted in an outer circumferential surface of the other end of the first leg 111 to insulate the first leg 111 and the fourth leg 114 from each other. The insulating spacer 119 may be inserted in an outer circumferential surface of one end of the third leg 113 to insulate the second leg 112 and the third leg 113 from each other. The insulating spacer 119 may be inserted in an outer circumferential surface of the other end of the third leg 113 to insulate the third leg 113 and the fourth leg 114 from each other.

The induction coils 163 and 165 may include a first induction coil 163 surrounding the first magnetic core 142 and a second induction coil 165 surrounding the second magnetic core 144. A first power source may be electrically connected to the first induction coil 163, and a second power source may be electrically connected to the second induction coil 165.

According to a modified embodiment of the present invention, the first induction coil 163 and the second induction coil 165 may be connected in series to be connected to a single power source.

The groove 115 may be formed on an inner surface of the chamber 110 to surround a moving direction of the discharge space 101. The groove 115 may have the shape of a nut such as a female screw. The groove 115 may be helical or circular. An interval between adjacent grooves may be several millimeters (mm) to several centimeters (cm). The groove 115 may have the shape of circular bellows or spiral bellows. The groove 115 may be formed at a straight portion of the discharge space 101. More specifically, the groove 115 may be formed at the first through-hole 11, the second through-hole 13, the third path 12c of the second leg 112, and the third path 14c of the fourth leg 114.

The groove 115 may be rounded prevent formation of a corner. Thus, both a valley region and a protrusion of the groove 115 may be rounded.

A first cooling block 131 may be disposed on a side surface opposite to one side surface of the second leg 112 where the gas injector 139 is disposed. The first cooling block 131 may receive a coolant and provide the coolant to a coolant flow path formed at the second leg 112. The coolant flow path may be formed at the first leg 111, the third leg 113, and the fourth leg 114. A second cooling block 134 may be disposed on a side surface opposite to one side surface of the fourth leg 114 where the second flange 133 is disposed. The second cooling block 134 may exhaust a heat coolant while flowing along a coolant flow path. That is, the coolant may flow in through the first coolant block 131 and may be exhausted through a first coolant flow path of the second leg 112, the first leg 111, and the fourth leg 114 and a second coolant flow path of the second leg 112, the third leg 113, and the fourth leg 114.

FIG. 4 illustrates a plasma generation apparatus according to an embodiment of the present invention. In FIG. 4, the same explanations as those in FIGS. 2 and 3 will be omitted.

Referring to FIG. 4, a microwave ignition discharge unit includes a microwave hole 19, a waveguide 153,

dielectric windows

151a and 151b, and a waveguide hole 152. The microwave ignition discharge unit performs early ignition on a discharge space 101 using a microwave.

The discharge space 101 may include a straight portion and a curved portion, and a length direction (y-axis direction) of the waveguide 153 may be disposed in an extending direction of the straight portion of the discharge space 101. Thus, a mounting space may be minimized. The waveguide 153, the waveguide hole 152, and the microwave hole 19 may constitute an aperture coupled cavity. That is, the microwave hole 19 and plasma may provide a cavity. Thus, a diameter of the waveguide hole 152, a length of the microwave hole 19, and a diameter of the microwave hole 19 may be designed.

The microwave hole 19 may be disposed at the curved portion in the x-axis direction. Thus, the

dielectric windows

151a and 151b may not be in direct contact with a loop formed by the discharge space 101.

Returning to FIG. 3, the microwave hole 19 may be formed on the cover plate 112a of the second leg 112. A position where the microwave hole 19 is formed may be a position where the second through-hole 13 views the second leg 112. The microwave hole 19 may be disposed at the curved portion of the discharge space 101.

The waveguide 153 may supply a microwave. The waveguide 153 may be a rectangular waveguide, and the waveguide hole 152 may be formed on a sidewall of the waveguide 153 or a wall surface perpendicular to a moving direction to radiate a microwave propagating the waveguide 153. More specifically, the waveguide hole 152 may be mounted on the sidewall of the waveguide 153. The waveguide hole 152 may be circular.

The waveguide hole 19 may be formed at the chamber 101 to be connected to the discharge space 101 to externally provide a microwave to the discharge space 101. The microwave hole 19 may be circular.

The insulating

windows

151a and 151b are disposed around the microwave hole 19, and a microwave pass through the insulating

windows

151a and 151b. The insulating

windows

151a and 151b may be disposed at the outer circumferential surface of the chamber 110. The insulating

windows

151a and 151b are used to maintain vacuum and transmit a microwave. The insulating

windows

151a and 151b may include a first insulating window 151a and a second insulating window 151b. The first insulating window 151a is disposed in contact with an outer surface of the chamber 110, and the second window 151b may be disposed in contact with an outer surface of the waveguide 153. The insulating

windows

151a and 151b, the waveguide hole 152, and the microwave hole 19 may be linearly aligned with each other.

An impedance matching tuner 154 may be mounted on the waveguide 153. The impedance matching tuner 154 may be a stub tuner, and a mounting position of the impedance matching tuner 154 may vary. A plurality of stub mounting holes may be formed in a moving direction of the waveguide 153 to modify a position of a matching stub. A hole where the matching stub is not disposed may be closed by a metal plug 159.

The microwave hole 19 and the waveguide hole 152 may be coaxially aligned with each other. An optical sensor 158 may be disposed at the waveguide 153 in a direction where the insulating

windows

151a and 151b view the waveguide 153. That is, the optical sensor 158 may be mounted on an opposite wall surface where the waveguide hole 152 is formed. Accordingly, radiated light of plasma passing through the waveguide hole 152 may be sensed by the optical sensor 158. The optical sensor 158 may determine whether ignition discharge is performed and main discharge is maintained.

FIG. 5 illustrates a plasma generation apparatus according to another embodiment of the present invention. In FIG. 5, the same explanations as those in FIGS. 1 to 4 will be omitted.

Referring to FIG. 5, a plasma generation apparatus 100c includes toroidal-type

magnetic cores

142 and 144 to form a closed loop, a chamber 110 including a discharge space101 surrounding one section of the

magnetic cores

142 and 144 and forming a closed loop, an induction coil disposed to surround the other section of the

magnetic cores

142 and 144, an AC power source supplying power to the induction coil to an induced electromotive force generated by the magnetic core to generate toroidal plasma in the discharge space 101, and a groove 115 formed on an inner surface of the discharge space 101. The induction coil constitute a primary coil of a transformer, and the plasma generated in the discharge space 101 forms a secondary coil of the transformer.

A microwave ignition discharge unit includes a microwave hole 19, a waveguide 153, a dielectric window 151, and a waveguide hole 152. The microwave ignition discharge unit perform early ignition on the discharge space 101.

The discharge space 101 includes a straight portion and a curved portion, and a length direction (z-axis direction) of the waveguide 153 may be a z-axis direction perpendicular to an xy plane where the discharge space 101 is disposed.

The microwave hole 19 may be formed in the center of a cover plate 112a of a second leg 112. A position where the microwave hole 19 is formed may be a central position of the second leg 112. The microwave hole 19 may be disposed at the straight portion of the discharge space 101.

FIG. 6 illustrates a plasma generation apparatus according to another embodiment of the present invention.

Referring to FIG. 6, a plasma generation apparatus 100d includes toroidal-type

magnetic cores

142 and 144, an AC power source supplying power to the induction coil to allow an inducted electromotive force generated by the

magnetic cores

142 and 144 to generate toroidal plasma in the discharge space 101, and a groove formed on an inner surface of the discharge space 101. The induction coil constitutes a primary coil of a transformer, and the plasma generated in the discharge space 101 forms a secondary coil of the transformer.

The chamber 110 includes a first leg 111 having a first through-hole 11 formed in a first direction, a second leg 112 having a second connection path 12 formed to be continuously connected to the first through-hole 11, a third leg 113 having a second through-hole continuously connected to the first connection path 12 and formed in the first direction, and a fourth leg 114 having a second connection path 14 formed to be continuously connected to the second through-hole 113. The first through-hole 11, the first connection path 12, the second through-hole 13, and the second connection path 14 form the discharge space 101.

When a gas is distributed to two paths using a single gas injector, a distributed position is attacked by a process gas. Accordingly, there is a need for a path supply path to independently supply a swirl flow to each fluid path. For this reason, two gas supply paths and one gas exhaust path may be required. A first gas supply path 32a may be formed at the second leg 12 facing the first through-hole 11, and a second gas supply path 32b may be formed in a second direction at an intersection point of a straight portion of a discharge space of the second leg 112 and a central axis of the first through-hole 11.

A flange 132a may be coupled to the first gas supply path 32a, and a flange 132b may be coupled to the second gas supply path 32b. A first gas injector 139a may be inserted in the first gas supply path 32a to provide a swirl flow which surrounds the first direction while moving in the first direction. A second gas injector 139b may be inserted in the second gas supply path 32b to provide a swirl flow which surrounds a second direction while moving in the second direction. Thus, a method of distributing to two paths using two gas injectors may provide effective swirl flow. Ends of the first gas injector 139a and the second gas injector 139b are not inclined, and a plurality of holes are formed on a circumference having a constant radius with respect to the center. Thus, a curved portion of the discharge space 101 may be prevented from being attached by the process gas. Moreover, a processing flow rate and a dissociation rate may increase.

The discharge space 101 includes first to fourth straight portions and first to fourth curved portions. A first gas supply path 32a is connected to the first curved portion, and a second gas supply path 32b is formed at the first curved portion to be perpendicular to the first gas supply path 32a. A gas exhaust path 33 is connected to the third curved portion that is diagonally disposed at the first curved portion.

FIG. 7 illustrates a plasma generation apparatus according to another embodiment of the present invention.

Referring to FIG. 7, a plasma generation apparatus 100e includes toroidal-type

magnetic cores

The chamber 110 includes a first leg 111 having a first through-hole 11 formed in a first direction, a second leg 112 having a first connection path 12 formed to be continuously connected to the first through-hole 11, a third leg 113 having a second through-hole 13 continuously connected to the first connection path 12 and formed in the first direction, and a fourth leg 14 having a second connection path 14 continuously connected to the second through-hole 13. The first through-hole 11, the first connection path 12, the second through-hole 13, and the second connection path 14 form the discharged space 101.

A gas supply path 32 may be disposed in the center of a straight portion of the second leg 112, and a gas exhaust path 33 may be disposed in the center of a straight portion of the fourth leg 114. A gas injector 139 may be inserted in the gas supply path 32 to supply a gas to the discharge space 101 in a forward direction. The gas injector 139 may provide a swirl flow.

A microwave ignition discharge unit includes a microwave hole 19, a waveguide 153,

dielectric windows

151a and 151b, and a waveguide hole 152. The microwave ignition discharge unit performs early ignition on the discharge space using a microwave.

The discharge space 101 includes a straight portion and a curved portion, and a length direction of the waveguide 153 may be an x-axis direction. The microwave e hole 152 may be formed at a curved portion of the second leg 112.

FIG. 8 illustrates a plasma generation apparatus according to another embodiment of the present invention.

Referring to FIG. 8, a plasma generation apparatus 100f includes toroidal-type

magnetic cores

The chamber 110 includes a first leg 111 having a first through-hole 11 formed in a first direction, a second leg 112 having a first connection path 12 formed to be continuously connected to the first through-hole 11, a third leg 113 having a second through-hole 13 continuously connected to the first connection path 12 and formed in the first direction, and a fourth leg 114 having a second connection path 14 formed to be continuously connected to the second through-hole 13. The first through-hole 11, the first connection path 12, the second through-hole 13, and the second connection path 14 form the discharge space 101.

Gas supply paths

32a and 32b may be formed at each curved portion adjacent to both sides of the second leg 112, and a gas exhaust path may be formed in the center of a straight portion of the fourth leg 114. The first gas supply path 32a may be formed at a position that the first through-hole 11 views at the second leg 112, and the second gas supply path 32b may be disposed at a position that the second through-hole 13 views at the second leg 112.

A first gas injector 139a may be inserted in the first gas supply path 32a to supply a gas to the discharge space 101. The first gas injector 139a may provide a swirl flow to the discharge space 101 in the x-axis direction.

A second gas injector 139b may be inserted in the second gas supply path 32b to supply a gas to the discharge space 101. The second gas injector 139b may provide a swirl flow to the discharge space 101 in the x-axis direction.

A microwave ignition discharge unit includes a microwave hole 19, a waveguide 153, a dielectric window 151, and a waveguide hole 152. The microwave ignition discharge unit performs early ignition to the discharge space 101 using a microwave.

The discharge space 101 includes a straight portion and a curved portion, and a length direction of the waveguide 153 may be the z-axis direction. The microwave hole 19 may be formed at the straight portion of the second leg 112.

FIG. 9 illustrates a plasma generation apparatus according to another embodiment of the present invention.

Referring to FIG. 9, a plasma generation apparatus 100g includes toroidal-type

magnetic cores

142 and 144 to form a closed loop, a chamber 210 including a discharge space 101 surrounding one section of the

magnetic cores

The chamber 210 may include first to fourth legs 211~214 and first to fourth elbow ducts 215~218. The first leg 211 may be disposed in the x-axis direction, and the third leg 213 may be spaced in the y-axis direction to be disposed alongside of the first leg 211. The second leg 212 may be disposed in the y-axis direction, and the fourth leg 214 may be spaced in the y-axis direction to be disposed alongside of the second leg 212.

The first leg 211 may have a first through-hole 21 formed in a first direction (x-axis direction). The second leg 212 may have a second through-hole 22 formed in a second direction (y-axis direction). The third leg 213 may have a third through-hole 23 formed in the first direction (x-axis direction). The fourth leg 214 may have a fourth through-hole 24 formed in the second direction (y-axis direction). The first to fourth through-holes 21~24 may have the substantially same structure. Grooves may be formed at side surfaces of the first to fourth through-holes 21~24.

The first elbow duct 215 may connect the first through-hole 21 of the first leg 211 to the second through-hole 22 of the second leg 212. Thus, the first elbow duct 215 may have a curvature and include a first connection path bent a right angle (90 degrees).

The second elbow duct 216 may connect the second through-hole 22 of the second leg 212 to the third through-hole 23 of the third leg 213. Thus, the second elbow duct 216 may have a curvature and include a second connection path bent at a right angle (90 degrees).

The third elbow duct 217 may connect the third through-hole 23 of the third leg 213 to the fourth through-hole 24 of the fourth leg 214. Thus, the third elbow duct 217 may have a curvature and include a third connection path bent at a right angle (90 degrees).

The fourth elbow duct 218 may connect the fourth through-hole 24 of the fourth leg 214 to the first through-hole 21 of the first leg 211. Thus, the fourth elbow duct 218 may have a curvature and include a fourth connection path bent at a right angle (90 degrees).

The first through-hole 21, a first connection path, the second through-hole 22, a second connection path, the third through-hole 23, a third connection path, the fourth through-hole 24, and a fourth connection path may form the discharge space 101.

As the chamber 210 is dissembled into the first to fourth elbow ducts 215~218, grooves 219 of the first to fourth legs 211~214 may be easily formed. In addition, electrically insulated portions of the chamber 210 may increase to reduce energy loss caused by induction heating of the chamber 210. When a portion of the chamber 210 is damaged by an abnormal phenomenon such as arc, only the damaged portion may be selectively removed to reduce the cost of maintenance.

FIGS. 10 and 11 illustrate grooves according to an embodiment of the present invention.

Referring to FIG. 10, a helical groove 115 may be formed on an inner wall of a discharge space of a chamber 110. The helical groove 115 may provide a swirl to a supply gas. Moreover, the helical groove 115 may reduce an interaction between plasma and the inner wall of the chamber 110.

Referring to FIG. 11, a groove 115 may be formed on an inner wall of a discharge space of a chamber 110. The groove 115 may be formed in a moving direction of the discharge space. The groove 115 may reduce an interaction between plasma and the inner wall of the chamber 110.

Referring to FIGS. 1, 2, and 12, there are shown etch rates of plasma generation apparatuses having the same configuration except that a groove 115 is formed on an inner wall of a chamber 110. When a flow rate of NF3 supplied through a gas supply path is 8 slm, there was a difference of two times in an etch rate of a substrate 173 inside a process chamber 172. The etch rate of silicon was measured under the conditions that a substrate was a silicon substrate and powers were 7.0 kilowatts (kW), 7.7 kW, and 8.4 kW.

Although the present invention has been described in connection with the embodiment of the present invention illustrated in the accompanying drawings, it is not limited thereto. It will be apparent to those skilled in the art that various substitutions, modifications and changes may be made without departing from the scope and spirit of the present invention.

Claims

A plasma generation apparatus comprising:

a toroidal-type magnetic core to form a closed loop;

a chamber surrounding one section of the magnetic core and including a discharge space in which a closed loop is formed;

an induction coil disposed to surround the other section of the magnetic core;

AC power source supplying power to the induction coil to allow an induced electromotive force generated by the magnetic core to generate toroidal plasma in the discharge space; and

a groove formed on an inner surface of the discharge space,

wherein the induction coil constitutes a primary coil of a transformer, and the toroidal plasma generated in the discharge space forms a secondary coil of the transformer.
The plasma generation apparatus of claim 1, wherein the discharge space includes a straight portion and a curved portion, and

wherein the groove is formed on an inner surface of the chamber to surround a moving direction of the discharge space along the straight portion.
The plasma generation apparatus of claim 1, wherein the groove has a helical shape, a shape of straight line formed in the moving direction of the discharge space or a circular shape.
The plasma generation apparatus of claim 1, wherein an interval between adjacent grooves is several millimeters to several centimeters.
The plasma generation apparatus of claim 1, further comprising:

a microwave hole formed at the chamber to be connected to the discharge space to externally provide a microwave to the discharge space;

an insulating window disposed around the microwave hole to allow a microwave to pass therethrough;

a waveguide to provide a microwave to the insulating window; and

a waveguide hole formed at the waveguide to radiate a microwave propagating in the waveguide and provide the radiated microwave to the microwave hole.
The plasma generation apparatus of claim 5, wherein the discharge space includes a straight portion and a curved portion, and

wherein a length direction of the waveguide is disposed in an extending direction of the straight portion of the discharge space.
The plasma generation apparatus of claim 5, further comprising at least one of:

at least one impedance matching stub mounted on the waveguide; and

an optical sensor disposed at the waveguide in a direction where the insulating window views the waveguide.
The plasma generation apparatus of claim 5, wherein the microwave hole and the waveguide hole are circular.
The plasma generation apparatus of claim 5, wherein the microwave hole is disposed in the center of the straight portion.
The plasma generation apparatus of claim 5, wherein the microwave hole is disposed at the curved portion.
The plasma generation apparatus of claim 1, wherein the chamber comprises:

a first leg having a first through-hole formed in a first direction;

a second leg having a first connection path formed to be continuously connected to the first through-hole;

a third leg having a second through-hole continuously connected to the first connection path and formed in the first direction; and

a fourth leg having a second connection path formed to be continuously connected to the second through-hole,

wherein the first through-hole, the first connection path, the second through-hole, and the second connection path form the discharge space.
The plasma generation apparatus of claim 11, wherein the second leg comprises:

a first path formed to be connected to one end of the first through-hole;

a second path formed to be connected to one end of the second through-hole; and

a third path formed in a second direction perpendicular to the first direction to connect the first path and the second path to each other,

wherein the first path, the third path, and the second path are continuously connected to form a first connection path, and

wherein the fourth leg comprises:

a first path formed to be connected to the other end of the first through-hole;

a second path formed to be connected to the other end of the second through-hole; and

a third path formed in a second direction perpendicular to the first direction to connect the first path and the second path to each other, and

wherein the first path, the third path, and the second path are continuously connected to form a second connection path.
The plasma generation apparatus of claim 12, wherein each of the second and fourth legs comprises a support plate and a cover plate disposed on the support plate,

wherein the support plate includes a concave portion depressed on its top surface,

wherein the half of the third path is formed on a bottom surface of the concave portion in the second direction,

wherein the cover plate includes a protrusion protruding on its lower surface, and

wherein the other half of the third path is formed on a bottom surface of the protrusion in the second direction.
The plasma generation apparatus of claim 1, wherein the discharge space comprises first to fourth straight portions and first to fourth curved portions, and

wherein the discharge space further comprises:

a gas supply path connected to the first curved portion; and

a gas exhaust path connected to the third curved portion diagonally disposed at the first curved portion.
The plasma generation apparatus of claim 14, further comprising:

a gas injector inserted in the gas supply path to provide a swirl flow and adapted to supply a supply gas to two different paths.
The plasma generation apparatus of claim 1, wherein the discharge space comprises first to fourth straight portions and first to fourth curved portions, and

wherein the discharge space further comprises:

a first gas supply path connected to the first curved portion;

a second gas supply path formed at the first curved portion to be perpendicular to the first gas supply path; and

a gas exhaust path connected to the third curved portion diagonally disposed at the first curved portion.
The plasma generation apparatus of claim 1, wherein the discharge space comprises first to fourth straight portions and first to fourth curved portions, and

wherein the discharge space further comprises:

a first gas supply path connected in the center of the second straight portion; and

a gas exhaust path formed at the fourth straight portion disposed alongside of the second straight portion.
The plasma generation apparatus of claim 1, wherein the discharge space comprises first to fourth straight portions and first to fourth curved portions, and

wherein the discharge space further comprises:

a first gas supply path connected to the first curved portion;

a second gas supply path connected to the second curved portion; and

a gas exhaust path formed at the fourth straight portion.
The plasma generation apparatus of claim 1, wherein the chamber comprises:

a first leg having a first through-hole;

a first elbow duct connected to one end of the first through-hole;

a second leg having a second through-hole connected to the first elbow duct;

a second elbow duct connected to the second through-hole;

a third leg having a third through-hole connected to the second elbow duct;

a third elbow duct connected to the third through-hole;

a fourth leg having a fourth through-hole connected to the third elbow duct; and

a fourth elbow connecting the fourth through-hole and the first through-hole to each other.