(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2014/0097912 A1
`Lee
`(43) Pub. Date:
`Apr. 10, 2014
`
`US 201400.97912A1
`
`(54) IMPEDANCE MATCHING DEVICE, LINEAR
`MOTION MODULE, AND RADIO
`FREQUENCY POWER SUPPLY DEVICE
`Applicant: PLASMART INC., Daejeon (KR)
`Inventor: Wonoh Lee, Daejeon (KR)
`Assignee: PLASMART INC., Daejeon (KR)
`Appl. No.: 14/101,854
`
`(71)
`(72)
`(73)
`(21)
`(22)
`
`Filed:
`
`Dec. 10, 2013
`
`(63)
`
`Related U.S. Application Data
`Continuation of application No. PCT/KR2012/
`005107, filed on Jun. 28, 2012.
`Foreign Application Priority Data
`
`(30)
`Jul. 1, 2011 (KR) ........................ 10-2011-OO65347
`
`Publication Classification
`
`(51) Int. Cl.
`HO3H 7/38
`(52) U.S. Cl.
`CPC ....................................... H03H 7/38 (2013.01)
`USPC ............................................................ 333A32
`
`(2006.01)
`
`(57)
`
`ABSTRACT
`
`An impedance matching device includes a first variable
`capacitor connected to an RF power source and including a
`first shaft moving linearly, a first linear motion unit axially
`coupled to the first shaft of the first variable capacitor to
`provide linear motion, a first insulating joint connecting the
`first shaft to a first driving shaft of the first linear motion unit,
`and a first displacement sensor adapted to measure a move
`ment distance of the first driving shaft of the first linear
`motion unit.
`
`192
`
`
`
`Control
`Unit
`
`External
`Interface
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`RENO EXHIBIT 2027
`Advanced Energy v. Reno, IPR2021-01397
`
`

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`Patent Application Publication
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`Fig. 1
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`Motion
`Control Unit
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`124
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`125
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`Control
`Unit
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`External
`Interface
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`Patent Application Publication
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`Fig. 2
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`Patent Application Publication
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`Inductor
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`Patent Application Publication
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`112
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`340-
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`H
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`C
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`Patent Application Publication
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`Fig. 8
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`340
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`Patent Application Publication
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`Apr. 10, 2014 Sheet 9 of 9
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`Fig
`... 10
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`492a
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`492b
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`492n
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`492
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`US 2014/00979 12 A1
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`Apr. 10, 2014
`
`IMPEDANCE MATCHING DEVICE, LINEAR
`MOTION MODULE, AND RADIO
`FREQUENCY POWER SUPPLY DEVICE
`
`CROSS-REFERENCE TO RELATED
`APPLICATIONS
`0001. This application is a continuation of and claims
`priority to PCT/KR2012/005107 filed on Jun. 28, 2012,
`which claims priority to Korea Patent Application No.
`10-2011-0065347 filed on Jul. 1, 2011, the entirety of which
`is hereby incorporated by reference.
`
`BACKGROUND OF THE INVENTION
`0002 1. Field of the Invention
`0003. The present invention described herein generally
`relates to impedance matching devices and, more particu
`larly, to an impedance matching device that includes a linear
`motion unit and directly drives a variable capacitor.
`0004 2. Description of the Related Art
`0005. An impedance matching device employing a vari
`able capacitor is low in response speed due to the use of
`rotational motion.
`
`SUMMARY OF THE INVENTION
`0006 Embodiments of the present invention provide an
`impedance matching device with high-speed response.
`0007 An impedance matching device according to an
`exemplary embodiment of the present invention may include
`a first variable capacitor connected to an RF power source and
`including a first shaft moving linearly; a first linear motion
`unit axially coupled to the first shaft of the first variable
`capacitor to provide linear motion; a first insulating joint
`connecting the first shaft to a first driving shaft of the first
`linear motion unit; and a first displacement sensor adapted to
`measure a movement distance of the first driving shaft of the
`first linear motion unit.
`0008. In an exemplary embodiment, the impedance
`matching device may further include a second variable
`capacitor including a second shaft moving linearly; a second
`linear motion unit axially coupled to the second shaft of the
`second variable capacitor to provide linear motion; a second
`insulating joint connecting the second shaft to a second driv
`ing shaft of the second linear motion unit; and a second
`displacement sensor adapted to measure a movement dis
`tance of the second driving shaft of the second linear motion
`unit.
`0009. In an exemplary embodiment, the first linear motion
`unit may include a coil bobbin coupled to the other end of the
`first driving shaft; and a first permanent magnet unit disposed
`to encircle the first driving shaft and provide linear motion to
`the coil bobbin.
`0010. In an exemplary embodiment, the impedance
`matching device may further include a front-end flange
`coupled to a first electrode of the first variable capacitor; a
`back-end flange coupled to the first linear motion unit; and an
`insulating fixing part disposed to encircle the first insulating
`joint and having one end coupled to the front-end flange and
`the other end coupled to the back-end flange.
`0011. In an exemplary embodiment, the impedance
`matching device may further include a motion control unit
`adapted to control the first linear motion unit; a power detec
`tion unit adapted to detect a reflected wave reflected in a
`direction of the RF power source; and a control unit adapted
`
`to control the motion control unit by receiving an output
`signal of the power detection unit and an output signal of the
`first displacement sensor.
`0012. In an exemplary embodiment, the first displacement
`sensor may include a displacement sensor mount extending
`from the first driving shaft of the first linear motion unit; an
`encoder Scaler mounted on the displacement sensor mount;
`and an encoder readout unit spaced apart from the encoder
`scaler.
`0013. In an exemplary embodiment, a frequency of the RF
`power source is variable.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`0014. The present invention will become more apparent in
`view of the attached drawings and accompanying detailed
`description. The embodiments depicted therein are provided
`by way of example, not by way of limitation, wherein like
`reference numerals refer to the same or similar elements. The
`drawings are not necessarily to scale, emphasis instead being
`placed upon illustrating aspects of the present invention.
`0015 FIG. 1 illustrates an impedance matching device
`according to an embodiment of the present invention.
`0016 FIG. 2 illustrates a first linear motion unit in FIG.1.
`0017 FIG. 3 illustrates a displacement sensor.
`0018 FIGS. 4 to 9 illustrate a linear motion module
`according to an embodiment of the present invention.
`0019 FIG. 10 is a circuit diagram of a radio-frequency
`power Supply device according to an embodiment of the
`present invention.
`
`DETAILED DESCRIPTION OF EMBODIMENTS
`0020. When RF plasma is generated in a semiconductor
`process or the like, it is necessary to perform matching in the
`early time. Accordingly, impedance matching has been per
`formed by changing a frequency without use of a variable
`passive element. However, a frequency-Variable impedance
`matching device must be connected to an RF power source to
`perform impedance matching. The frequency-Variable
`impedance matching device may have high response speed.
`However, since the frequency-Variable impedance matching
`device uses a frequency as a parameter, it is difficult for the
`frequency-Variable impedance matching device to minimize
`a reflected wave in an impedance matching device that
`requires two degrees of freedom. Moreover, when a load
`significantly varies depending on time, it is difficult for the
`frequency-Variable impedance matching device to perform
`impedance matching.
`0021 Conventionally, capacity of a variable capacitor is
`moved by converting a rotational motion into a linear motion.
`Long-term use of an expensive apparatus results in a wear
`problem caused by friction that occurs when a rotational
`motion is converted into a linear motion, rather than a struc
`tural defect of a variable capacitor itself. Accordingly, when a
`lubricant is used to eliminate the wear problem, other prob
`lems such as lubricant contamination and lubricant vaporiza
`tion occur. Moreover, a driving unit using a rotational motion
`requires high manufacturing cost and space to achieve high
`speed.
`0022. An impedance matching device according to an
`embodiment of the present invention directly provides a lin
`ear motion to a variable capacitor. Since a friction movement
`distance of a linear motion unit providing the linear motion is
`relatively short, the lifetime of the linear motion unit may be
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`Apr. 10, 2014
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`extended and a connection structure of the linear motion unit
`may be simplified. In addition, the linear motion unit may
`perform high-speed matching.
`0023. In case of an electronic impedance matching device
`employing a conventional capacitor Switching scheme, a size
`of a matching network increases as allowable current and
`voltage increases. Moreover, the degree of allowable current
`and Voltage is limited.
`0024 However, an impedance matching device according
`to an embodiment of the present invention uses a linear
`motion unit that allows a linear motion to be performed in a
`narrow space. Moreover, the impedance matching device
`uses a variable capacitor to reduce limitation in current and
`Voltage of the variable capacitor. Thus, space saving in a clean
`room obtains again in term of cost.
`0025. An impedance matching device according to an
`embodiment of the present invention includes a linear motion
`driving unit to drive a variable reactance passive element. The
`linear motion driving unit has high response speed. Thus, the
`impedance matching device matches impedance with a wide
`range load.
`0026. A plasma process of a few seconds or less or a
`plasma process treated with a process having time-dependent
`parameters has been used in semiconductor manufacturing.
`For this reason, the plasma process must be stabilized within
`hundreds of milliseconds (msec) or tens of milliseconds
`(msec). Accordingly, there is a need for an impedance match
`ing device that is capable of performing high-speed imped
`ance matching.
`0027 Exemplary embodiments of the present invention
`will now be described more fully with reference to the accom
`panying drawings, in which exemplary embodiments of the
`present invention are shown. Exemplary embodiments of the
`present invention may, however, be embodied in many differ
`ent forms and should not be construed as limited to the
`embodiments set forth herein. Rather, these exemplary
`embodiments of the present invention are provided so that this
`description will be thorough and complete, and will fully
`convey the concept of exemplary embodiments of the present
`invention to those of ordinary skill in the art. In the drawings,
`the sizes and relative sizes of elements may be exaggerated
`for clarity. Like numerals refer to like elements throughout.
`0028 FIG. 1 illustrates an impedance matching device
`according to an embodiment of the present invention.
`0029 FIG. 2 illustrates a first linear motion unit in FIG. 1.
`0030 FIG. 3 illustrates a displacement sensor.
`0031
`Referring to FIGS. 1 to 3, an impedance matching
`device 100 includes a first variable capacitor 112 connected to
`an RF power source 190 and including a first shaft 112a
`moving linearly, a first linear motion unit axially coupled to
`the first shaft 112a of the first variable capacitor 112 to pro
`vide linear motion, a first insulating joint 142 connecting the
`first shaft 112a to a first driving shaft of the first linear motion
`unit 121, and a first displacement sensor 124 adapted to
`measure a movement distance of the first driving shaft 121a of
`the first linear motion unit 121.
`0032. The impedance matching device 100 may include
`an outer cover 110. The outer cover 110 may be divided into
`an RF region 110a and a system region 110b by a divider 102.
`The divider 102 may be formed of a conductor plate. The
`outer cover 110 may be formed of a conductive material.
`0033. In the RF region 110a, the first variable capacitor
`112 and/or the second variable capacitor 114 may be dis
`posed. A first electrode 311 of the first variable capacitor 112
`
`may be connected to an output of the RF power source 190
`and one end of a first inductor 119, and a second electrode 312
`of the first variable capacitor 112 may be grounded.
`0034. A first electrode of the second variable capacitor 114
`may be connected to the other end of the first inductor 119. A
`second electrode of the second variable capacitor 114 may be
`connected to a load 192.
`0035. A power detector 132 may be disposed in the vicin
`ity of an input line 182 connecting the output of the RF power
`Source 190 to the first electrode 311 of the first variable
`capacitor 112. A shield layer 104 may be disposed in the
`vicinity of the power detector 132. The shield layer 104 may
`shield an external electromagnetic wave.
`0036) A frequency of the RF power source 190 may be
`between 400 kilohertz (kHz) and several hundreds of mega
`hertz (MHz). The frequency of the RF power source 190 is
`variable.
`0037. The load 192 may be energy apply means for gen
`erating plasma. For example, the load 192 may include an
`electrode to generate capacitively coupled plasma or an
`antenna to generate inductively coupled plasma Impedance of
`the load 192 may vary depending on time. The impedance of
`the load 192 may be dependent on a pressure of process gas to
`generate plasma or a process by-product that is produced as a
`process is performed.
`0038. Each of the first and second variable capacitors 112
`and 114 may be a variable vacuum capacitor. The vacuum
`variable capacitor may allow a high Voltage and much current
`to flow. The variable capacitor includes a first electrode and a
`second electrode, and capacitance may vary depending on a
`distance between the first electrode and the second electrode
`or the cross-coupled or inserted degree of the first electrode
`and the second electrode.
`0039. The first linear motion unit 121 may include a first
`driving shaft 121a, a coil bobbin 217, and a permanent mag
`net unit 216. The first linear driving unit 121 may be a voice
`coil motor. The first linear motion unit 121 may have high
`speed response characteristics. A maximum movement dis
`tance of the first linear motion unit 121 may be around 20
`millimeters (mm) The maximum movement distance may be
`obtained for 0.5 second or less.
`0040. One end of the first driving shaft 121a is axially
`coupled to the first insulating joint 142. The other end of the
`driving shaft 121a is coupled to the coil bobbin 217.
`0041. One end of the coil bobbin 217 may have an open
`cylinder shape. The coil may include an induction coil. The
`coil bobbin 217 may include a disc-shaped plate and a cylin
`drical cylinder coupled to the disc-shaped plate. The induc
`tion coil 217a is wound on an external side surface of the coil
`bobbin 217. The induction coil 217a may be connected to a
`motion control unit 123.
`0042. The permanent magnet unit 216 encircles the first
`driving shaft 121a and provides a linear motion to the coil
`bobbin 217. The permanent magnet unit 216 may has a cir
`cular groove 216a which is formed in the vicinity of the
`permanent magnet unit 216 such that the coil bobbin 217 is
`inserted into the circular groove 216a. The circular groove
`216.a may perform a guide function for the coil bobbin 217.
`Depth of the circular groove 216a may be greater than the
`maximum movement length of the first shaft 112a of the
`variable capacitor.
`0043. The permanent magnet unit 216 includes a perma
`nent magnet 216b and a magnetic induction housing 216c
`encircling the permanent magnet 216b. The circular groove
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`Apr. 10, 2014
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`may be a space between the permanent magnet 216b and the
`magnetic induction housing 216c.
`0044) The center of one surface of a circular plate of the
`coil bobbin 217 may be connected to the first driving shaft
`121a, and the center of the other surface of the circular plate
`may be connected to a displacement sensor mount 218.
`0045. The first insulating joint 142 may be a plastic, resin
`or Teflon material. The first insulating joint 142 may be
`formed of an insulating material. The first insulating joint 142
`may have a cylindrical shape. One end of the first insulating
`joint 142 may be axially coupled to the first shaft 112a, and
`the other end of the first insulating joint 142 may be axially
`coupled to the first driving shaft 121a. The first insulating
`joint 142 may have a plurality of ring-shaped grooves 142
`which is formed on its Surface Such that a current transmission
`distance increases to enhance the insulation effect.
`0046. If the first variable capacitor is a vacuum capacitor,
`the first shaft may be pulled in the first variable capacitor by
`a difference between vacuum pressure and atmospheric pres
`Sure. Especially, when a power Source is not supplied to the
`linear motion unit, a linear motion stop unit (not shown) may
`be disposed in the vicinity of the first insulating joint 142 to
`prevent the first insulating joint 142 from being released by
`vacuum. The linear motion stop unit may prevent component
`damage caused by an impact that occurs when the first insu
`lating joint 142 is released by vacuum. The linear motion stop
`unit may be a spring, a damperor a breaker.
`0047 A front-end flange 213 may be coupled to the first
`electrode 311 of the first variable capacitor 112. The front-end
`flange 213 may be closely coupled to the first electrode 311
`and may be formed of a conductive material. The front-end
`flange 213 may be electrically connected to the RF power
`source 190. The front-end flange 213 may be coupled to the
`first electrode 213 by a screw.
`0048. A back-end flange 215 may be coupled to the first
`linear motion driving unit 121. The back-end flange 215 may
`be coupled to the permanent magnet unit 216. The back-end
`flange 215 may be fixed to the divider 102.
`0049. An insulating fixing part 214 may encircle the first
`insulating joint 142 and have one end coupled to the front-end
`flange 213 and the other end coupled to the back-end flange
`215. The insulating fixing part 214 may be formed of an
`insulating material. The insulating fixing part 214 may be
`cylindrical. The insulating fixing part 214 may have a plural
`ity of ring-shaped grooves 214a on its surface to be flexible.
`0050. As the coil bobbin 217 moves in its central axis
`direction or in the Z-axis direction, the first shaft 112 may
`moves in the Z-axis direction. Thus, the capacitance of the first
`variable capacitor 112 varies. The coil bobbin 217 may move
`through the maximum movement distance within 0.5 second
`or less.
`0051. A displacement sensor may be mounted to detect a
`movement distance of the coil bobbin 217. A first displace
`ment sensor 124 may include a displacement sensor mount
`218 extending from the first driving shaft 121a of the first
`linear motion unit 121, an encoder scaler 270 mounted on the
`displacement sensor mount 218, and an encoder readout unit
`272 spaced apart from the encoder scaler 270. The displace
`ment sensor may have a resolution of 1000 count or more with
`respect to the maximum movement distance.
`0052. The displacement sensor mount 218 may be screw
`coupled to the coil bobbin 217. The displacement sensor
`
`mount 218 may have a square cylindrical shape. The encoder
`scaler 270 may be disposed on one surface of the displace
`ment sensor mount 218.
`0053. The encoder readout unit 272 may be disposed to
`face the encoder scaler 270 and to be spaced apart from the
`encoder scaler 270. The encoder readout unit 272 may mea
`sure a reciprocal distance from the encoder scaler 270 while
`moving along the encoder Scaler 270. An output signal of the
`encoder readout unit 272 is provided to a control unit 126.
`0054. The motion control unit 123 drives the first linear
`motion unit 121 and/or the second linear motion unit 122.
`0055. A power detection unit 132 may detect power
`reflected at an input terminal of an impedance matching
`device from the RF power source 190. The power detection
`unit 132 may be a directional coupler or a current/voltage
`sensor. The power detection unit 132 may detect a signal
`associated with a reflected wave.
`0056. The power detection unit 132 may be disposed at an
`output terminal of the impedance matching device or may
`also be disposed inside the impedance matching device.
`0057 By detecting an output signal of the power detection
`unit 132, the control unit 126 may control capacitances of the
`first variable capacitor 112 and the second variable capacitor
`114 Such that the impedance matching device transfers maxi
`mum power to the load 192. The capacitance of the first
`variable capacitor 112 may be controlled by the first linear
`motion unit 121, and the capacitance of the second variable
`capacitor 114 may be controlled by the second linear motion
`unit 122. The control unit 126 may communicate with an
`external device. For example, the control unit 126 may com
`municate with the RF power source 190 and/or a computer.
`0.058 An algorithm where the control unit 126 controls the
`capacitances of the first variable capacitor 112 and the vari
`able capacitor 114 may employ a conventional method. For
`example, the algorithm is disclosed in Korean Patent Publi
`cation No. 10-2008-0094155. In addition, an impedance
`matching scheme of the impedance matching device may be
`one of L-type, inverted L-type, T-type, and L-type.
`0059. The second linear motion unit 122 may have the
`same structure as the first linear motion unit 121.
`0060. The second insulating joint 144 may have the same
`structure as the first insulating joint 142.
`0061. A second displacement sensor 125 may have the
`same structure as a first displacement sensor 124. The first
`displacement sensor 124 may employ a potentiometer
`method, an optical method, a magnetic method, an electronic
`induction method, a linear encoder method, an eddy current
`method, an ultrasonic method or the like.
`0062 According to a modified embodiment of the present
`invention, the impedance matching device may be used in
`double-frequency matching having a plurality of frequencies.
`0063. According to a modified embodiment of the present
`invention, the impedance matching device may be used in
`hybrid impedance matching using an RF power source having
`a variable frequency and a separate variable capacitor.
`0064 FIGS. 4 to 9 illustrate a linear motion module
`according to an embodiment of the present invention.
`0065. In order to avoid duplicate explanations, the follow
`ing explanations relate only to aspects that are different from
`FIGS 1 to 3.
`0066 Referring to FIGS. 4 to 7, a linear motion module 10
`includes a first linear motion unit 121 axially coupled to a first
`shaft of a first variable capacitor 112 connected to an RF
`power source and including the first shaft moving linearly, a
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`Apr. 10, 2014
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`first insulating joint 142 connecting the first shaft to a first
`driving shaft of the first linear motion unit 121 to provide
`linear motion, and a first displacement sensor 124 adapted to
`measure a movement distance of the first driving shaft of the
`first linear motion unit 121. A linear motion stop unit 340 is
`disposed in the vicinity of the first insulating joint 142 to
`prevent the first shaft from being pulled by a difference
`between vacuum pressure and atmospheric pressure. A
`capacitor oran inductor may be connected in series or parallel
`to the first variable capacitor 112.
`0067. Referring to FIG. 8, the linear motion stop unit 340
`may be a spring. The first linear motion stop unit 340 may be
`a spring disposed to encircle the first insulating joint 142. One
`end of the first insulating joint 142 connected to a linear
`motion driving unit may have a projection. The projection of
`the insulating joint 142 may function as a breaker to prevent
`the insulating joint 142 from being pulled by a vacuum force.
`0068. The spring is disposed between the projection and a
`front-end flange 213. The spring may allow a vacuum force
`applied in an axis direction of the first variable capacitor 112
`to be offset by a repulsive force and may provide a force
`required for the linear motion unit 121.
`0069. Referring to FIG.9, the linear motion stop unit 340
`includes a protrusion 341 inserted into a groove 142a formed
`on an external circumferential Surface of the first insulating
`joint 142 and a driver 342 coupled to the protrusion 341 to
`move the protrusion 341. The protrusion 341 may have a
`saw-toothed shape. One end of the first insulating joint 142
`connected to a linear motion driving unit may have a projec
`tion.
`0070 FIG. 10 is a circuit diagram of a radio-frequency
`power Supply device according to an embodiment of the
`present invention.
`0071. In order to avoid duplicate explanations, the follow
`ing explanations relate only to aspects that are different from
`FIGS 1 to 9.
`0072 Referring to FIG. 10, a radio frequency (RF) power
`supply device includes a single RF power source (RF) 490
`and an impedance matching unit 410 disposed between the
`RF power source 490 and at least one load 492.
`0073. The impedance matching unit 410 includes a first
`variable capacitor 412 including a first shaft moving linearly,
`a first linear motion unit (not shown) axially coupled to the
`first shaft of the first variable capacitor 412 to provide linear
`motion, a first insulating joint (not shown) connecting the first
`shaft to a first driving shaft of the first linear motion unit, and
`a first displacement sensor (not shown) adapted to measure a
`movement distance of the first driving shaft of the first linear
`motion unit.
`0074 The impedance matching unit 410 is disposed
`between a first load 492a and the RF power source 490. The
`impedance matching unit 410 may include a first variable
`capacitor 412, a second variable capacitor 414, and an induc
`tor 419. One end of the first variable capacitor 412 may be
`connected to an output terminal of the RF power source 490,
`and the other end of the first variable capacitor 412 may be
`grounded. One end of the inductor 419 is connected to the
`output terminal of the RF power source 490, and the other end
`of the inductor 419 may be connected to one end of the second
`variable capacitor 414. One end of the second variable capaci
`tor 414 is connected to the other end of the inductor 419, and
`the other end of the second variable capacitor 414 is con
`nected to the first load 492a.
`
`0075. The load 492 includes the first load 492a and the
`second load 492b. A power distribution unit 420a is disposed
`between the first load 492a and the second load 492b. The first
`load 492a may be an outside antenna for generating induc
`tively coupled plasma, and the second load 492b may be an
`inner antenna disposed inside the outside antenna. Alterna
`tively, the load 492 may be an electrode for generating capaci
`tively coupled plasma.
`0076. The power distribution unit 420a may include a
`capacitor 427 and an inductor 428 serially coupled between
`the first load 492a and the second 492b and a variable capaci
`tor 429 having one end that is coupled between the capacitor
`427 and the inductor 428 and the other end that is grounded.
`The power distribution unit 420a may distribution power
`between the first load 492a and the second load 492b at a
`constant rate. The variable capacitor 429 may be driven by a
`linear motion unit in the same manner as the first and second
`variable capacitor 412 and 414 of the impedance matching
`unit 410.
`(0077. The load 492 may be modified to include two or
`more loads 492a, 492b, and 492n. Accordingly, power distri
`bution units 420a and 420b may be additionally disposed
`between the loads 492a, 492b, and 492n.
`0078. As described so far, an impedance matching device
`according to an embodiment of the present invention can
`provide high-speed matching.
`0079 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.
`What is claimed is:
`1. An impedance matching device comprising:
`a first variable capacitor connected to an RF power source
`and including a first shaft moving linearly;
`a first linear motion unit axially coupled to the first shaft of
`the first variable capacitor to provide linear motion;
`a first insulating joint connecting the first shaft to a first
`driving shaft of the first linear motion unit; and
`a first displacement sensor adapted to measure a movement
`distance of the first driving shaft of the first linear motion
`unit.
`2. The impedance matching device of claim 1, further
`comprising:
`a second variable capacitor including a second shaft mov
`ing linearly;
`a second linear motion unit axially coupled to the second
`shaft of the second variable capacitor to provide linear
`motion;
`a second insulating joint connecting the second shaft to a
`second driving shaft of the second linear motion unit;
`and
`a second displacement sensor adapted to measure a move
`ment distance of the second driving shaft of the second
`linear motion unit.
`3. The impedance matching device of claim 1, wherein the
`first linear motion unit comprises:
`a coil bobbin coupled to the other end of the first driving
`shaft; and
`a first permanent magnet unit disposed to encircle the first
`driving shaft and provide linear motion to the coil bob
`bin.
`
`

`

`US 2014/00979 12 A1
`
`Apr. 10, 2014
`
`4. The impedance matching device of claim 3, further
`comprising:
`a front-end flange coupled to a first electrode of the first
`variable capacitor,
`a back-end flange coupled to the first linear motion unit;
`and
`an insulating fixing part disposed to encircle the first insu
`lating joint and having one end coupled to the front-end
`flange and the other end coupled to the back-end flange.
`5. The impedance matching device of claim 1, further
`comprising:
`a motion control unit adapted to control the first linear
`motion unit;
`a power detection unit adapted to detect a reflected wave
`reflected in a direction of the RF power source; and
`a control unit adapted to control the motion control unit by
`receiving an output signal of the power detection unit
`and an output signal of the first displacement sensor.
`6. The impedance matching device of claim 1, wherein the
`first displacement sensor comprises:
`a displacement sensor mount extending from the first driv
`ing shaft of the first linear motion unit;
`an encoder scaler mounted on the displacement sensor
`mount; and
`an encoder readout unit spaced apart from the encoder
`Scaler.
`7. The impedance matching device of claim 1, wherein a
`frequency of the RF power source is variable.
`8. The impedance matching device of claim 1, further
`comprising:
`a fixed reactive element connected in series or parallel to
`the first variable capacitor.
`9. The impedance matching device of claim 1, further
`comprising:
`a linear motion stop unit disposed in the vicinity of the first
`insulating joint to prevent the first shaft from being
`pulled by a difference between vacuum pressure and
`atmospheric pressure.
`
`10. A linear motion module comprising:
`a first linear motion unit axially coupled to a first shaft of a
`first variable capacitor connected to an RF power source
`and including the first shaft moving linearly;
`a first insulating joint connecting the first shaft to a first
`driving shaft of the first linear motion unit to provide
`linear motion; and
`a first displacement sensor adapted to measure a movement
`distance of the first driving shaft of the first linear motion
`unit.
`11. The linear motion module of claim 10, further compris
`1ng:
`a linear motion stop unit disposed in the vicinity of the first
`insulat