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`Samsung Electronics Co., Ltd. v. Demaray LLC
`Samsung Electronic's Exhibit 1023
`Exhibit 1023, Page 1
`
`

`

`U.S. Patent
`
`
`
`
`Apr. 12, 1994
`
`
`
`
`
`Sheet 1 of 4
`
`
`
`5,302,882
`
`
`
`
`
`
`
`
`
`Hf
`
`
`
`12
`
`
`
`
`COUPLER
`
`
`REACTOR
`
`10 GENERATOR
`
`Gee
`
`
`
`PRIOR ART
`
`
`
`
`
`
`
`
`
`
`
`GENERATOR
`
`
`
`
`
`
`
`
`
`19
`
`Ex. 1023, Page 2
`
`Ex. 1023, Page 2
`
`

`

`U.S. Patent
`
`
`
`
`Apr. 12, 1994
`
`
`
`
`
`Sheet 2 of 4
`
`
`5,302,882
`
`
`
`
`
`
`
`
`
`1,000
`
`
`
`0.100
`
`Vour/Vin(502LOAD)
`
`
`
`
`
`
`
`
`
`
`0.010
`
`
`
`
`
`fe =16.9MHz
`
`
`Zo= G12
`
`
`
`1 - Wb AIPPLE
`
`
`
`
`
`
`poy 4
`
`
`
`3
`
`10
`
`
`FREQUENCY (MHz)
`
`
`20
`
`
`
`
`IO
`
`
`
`8. ~c#
`
`
`
`(eer|=Hearn
`REACTOR
`
`
`
`3
`/9
`GENERATOR
`75 u— REACTOR
`
`
`
`
`
`ana|
`7
`
`
`On.Te ee J4
`
`
`
`Haare
`me
`SHS ST |
`
`~~ 77 JA rT ae’
`ssoxaron(AG)
`
`
`|
`
`|
`GENERATOR
`
`
`3/
`
`
`
`
`
`32
`
`
`32
`
`3
`
`
`JO
`
`
`GENERATOR
`
`
`
`
`MATCHING
`
`
`
`
`
`
`REACTOR
`
`
`{REACTOR
`
`
`Ex. 1023, Page 3
`
`Ex. 1023, Page 3
`
`

`

`
`U.S. Patent
`
`
`
`
`
`Apr. 12, 1994
`
`
`
`Sheet 3 of 4
`
`
`5,302,882
`
`
`
`REACTOR A
`
`
`
`REACTOR A
`
`
`Q&Nxuyx
`
`
`
`SOYTIZ
`
`cSxs (SY/OA)
`
`(SJ/OA)ZNPINPOD)/ONDUISD/
`SsOSHg80OFSs§8NS
`
`&Xe
`
`Ex. 1023, Page 4
`
`Ex. 1023, Page 4
`
`
`

`

`
`U.S. Patent
`
`
`
`
`
`Apr. 12, 1994
`
`
`
`Sheet 4 of 4
`
`
`5,302,882
`
`
`
`
`
`
`q&RSx
`
`
`
`Q&Rxe
`
`REACTOR A (WU)ZTVTLUBMLUEOfef
`
`‘ZATN£0&SOYe/
`
`
`
`
`
`
`
`
`
`
`
`GO
`
`(saelbap\Z]pun
`
`Ip I-
`
`Ir I, YW, LU, W-
`
`Ex. 1023, Page 5
`
`Ex. 1023, Page 5
`
`
`

`

`
`
`
`
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`
`
`
`
`LOWPASS FILTER FOR PLASMA DISCHARGE
`
`
`
`
`
`This application is a continuation of U.S. patent appli-
`
`
`
`
`
`
`
`
`cation Ser. No. 756,649, filed Sep. 9, 1991, now aban-
`doned.
`
`
`
`BACKGROUND OF THE INVENTION
`1. Field of the Invention
`
`
`
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`
`
`
`
`
`
`The present invention relates to the field of plasma
`
`
`
`
`
`
`processing and, moreparticularly, to the use of plasma
`
`
`
`
`equipment for modification of materials.
`
`
`
`2. Prior Art
`
`
`
`
`
`Plasma processing equipment is used extensively in
`
`
`
`
`
`
`
`
`the industry for the modification of materials. These
`
`
`
`
`
`
`modifications include etching and deposition of films
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`
`
`for fabrication of microelectronic circuits and semicon-
`
`
`
`
`
`
`
`ductor devices. The modifications also may include
`
`
`
`
`
`
`
`implantation of chemical species that change the fric-
`20
`
`
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`
`
`tion and wear properties of surfaces.
`
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`
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`
`
`A plasmais a gas (or a gas mixture) which is ener-
`
`
`
`
`
`
`
`gized so that it is partially decomposedinto species that
`
`
`
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`
`
`are electrically charged. A variety of techniques are
`
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`
`
`
`known for energizing the gas. One commonly used
`
`
`
`
`
`
`25
`technique is the energizing of the gas by imposing an
`
`
`
`
`
`
`
`
`electric field on the gas from an external source. A
`
`
`
`
`
`
`
`common practice is to use high frequency alternating-
`
`
`
`
`
`
`
`
`current (AC) fields to energize or excite the gas. For
`
`
`
`
`
`
`example, radio-frequency (RF). fields are generated at
`
`
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`
`
`
`frequency ranges near 10 MHz.Atstill higher frequen-
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`
`
`cies, in the order of 1000 MHz, microwavefields are
`
`
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`
`
`generated. In some instances, these electric fields are
`
`
`
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`
`
`utilized in combination with magnetic fields which are
`
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`
`
`
`used for the purpose of confining the plasma. Electron
`35
`
`
`
`
`
`
`cyclotron resonance (ECR) plasma processing is one
`
`
`
`
`
`
`
`
`
`technique for controlling the plasma with the use of.
`
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`
`
`electric and magneticfields.
`
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`
`The plasma is typically retained in a chamber of a
`
`
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`
`processing equipment and isolated from the surround-
`40
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`
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`
`
`
`ing ambientand this plasma usually contains species that
`
`
`
`
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`
`
`undergo chemical reactions. The plasma chamber and
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`
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`
`
`
`its gas-handling equipmentare typically referred to as a
`
`
`
`
`
`
`
`
`reactor. The source of the electrical power that ener-
`
`
`
`
`
`
`gizes the plasma is commonly referred to as a generator.
`45
`
`
`
`
`
`
`Usually, there are a number of components, including
`
`
`
`
`
`
`cables, wave guides,
`inductors, capacitors, matching
`
`
`
`
`
`
`network, tuner and/or an impedance transforming net-
`
`
`
`
`
`
`
`
`work coupling the generator to the reactor. These com-
`
`
`
`
`
`
`ponents are included in a system sometimesreferred to
`50
`
`
`
`
`
`
`
`as a coupler or a coupling system. The generator and
`
`
`
`
`
`
`
`the coupling system together comprise the AC source
`
`
`
`
`that energizes the plasma.
`
`
`
`
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`
`
`Various schemes have been devised in the prior art
`
`
`
`
`
`
`
`
`for coupling the generator, coupler, and the reactor to
`
`
`
`
`
`
`' operate as a plasma processing system for example, in
`
`
`
`
`
`
`
`U.S. Pat. No. 4,824,546 (Ohmi) an RF powersourceis
`
`
`
`
`
`
`coupled to a vacuum vessel through a matching circuit
`
`
`
`
`
`
`
`in order to provide a sputtering apparatus for forming
`
`
`
`
`
`
`
`
`
`an insulating thin film. Bandreject filters are provided
`
`
`
`
`
`
`to permit only high frequencies to be supplied.
`
`
`
`
`
`
`
`Another example is disclosed in U.S. Pat. No.
`
`
`
`
`
`
`
`4,579,618 (Celestinoet al.) in which two power sources
`
`
`
`
`
`
`are each coupled through a matching network to a
`
`
`
`
`
`plasma reactor. A filter/combiner is coupled between
`65
`
`
`
`
`
`
`
`
`
`the low frequency powersupply andthe high frequency
`
`
`
`
`
`
`
`power supply. The filter/combiner serves three pur-
`
`
`
`
`
`
`
`
`poses which are unique to a single electrode, dual fre-
`
`
`
`
`
`
`
`
`quency plasma reactor. The power of each powersup-
`
`
`
`
`
`
`
`
`
`
`
`1
`
`
`
`5,302,882
`
`
`
`
`
`
`—_0
`
`
`
`
`
`
`
`
`
`
`
`2
`
`
`
`
`
`
`
`
`ply must be largely prevented from reaching the other
`
`
`
`
`
`
`
`
`power supply, the mixing products caused by the cou-
`
`
`
`
`
`
`pling of two different frequencies to a non-linear load
`
`
`
`
`
`
`
`must be attenuated and the radiation emitted by the
`reactor and the various interconnections must be mini-
`
`
`
`
`
`
`
`mized.
`
`
`
`
`
`
`
`
`
`is that the plasmas
`A key feature of most plasmas,
`
`
`
`
`
`have “non-linear” impedance characteristics. Non-
`
`
`
`
`
`
`linearity is a mathematical definition signifying that the
`
`
`
`
`
`
`
`magnitudeofthe voltage (electric field) in the plasmais
`
`
`
`
`
`
`
`not directly proportional to the magnitude of the cur-
`
`
`
`
`
`
`
`rent (magnetic field). Typically,
`the generators em-
`
`
`
`
`
`
`
`ployed in various plasma systems are designed to gener-
`
`
`
`
`
`ate an output of predominantly single-frequency. How-
`
`
`
`
`
`
`
`ever, because of the non-linearity of the plasma, signals
`
`
`
`
`
`
`at multiples of the fundamental generator frequency are
`
`
`
`
`
`generated by the plasma. These multiple frequencies of
`
`
`
`
`
`
`
`the fundamental frequency are called harmonic fre-
`
`
`
`
`
`
`
`quencies (or harmonics). The amplitude of the harmon-
`
`
`
`
`
`
`
`
`ics affect certain properties of the plasma, such as direct
`
`
`
`
`
`
`
`
`current (DC) bias, which impact the particular plasma
`
`
`
`
`
`
`process. The amplitude of the harmonics is determined
`
`
`
`
`
`
`
`
`bythe interaction of the plasma with the generator and
`
`
`
`
`
`
`
`the coupling system andis difficult to control simply by
`
`
`
`
`
`
`adjusting the amplitude of the fundamental frequency
`
`component.
`
`
`
`
`
`Plasma non-linearity is a phenomenon which plays an
`
`
`
`
`
`
`important role in causing the plasma conditions to be
`
`
`
`
`
`
`
`' dependent upon the electrical characteristics of the
`
`
`
`
`
`
`
`
`generator, as well as the coupling system, at both the
`
`
`
`
`
`operating (fundamental) frequency of the generator and
`
`
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`
`
`
`
`at the various harmonic frequencies. Thatis, if satisfac-
`
`
`
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`
`
`
`tory operation of a plasma reactor is achieved for a
`
`
`
`
`
`
`
`given generator and coupling system, the parameters of
`
`
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`
`
`the generator and the coupling system cannot bereadily
`
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`
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`changed withoutaffecting the plasmaitself. Thus, gen-
`
`
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`
`
`erally it is impractical, if not possible, to make changes
`
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`
`
`
`to the electrical parameters of the generator and/or the
`
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`
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`
`
`coupling system andstill be able to reproduce the de-
`
`
`
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`
`
`sired plasma conditions, simply by readjusting the am-
`
`
`
`
`
`
`
`plitude of the generator output. Typically, whatis re-
`
`
`
`
`
`
`quired is a considerable retuning of the system in order
`
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`
`
`to satisfactorily couple the reactor to the generator
`
`
`
`
`
`
`
`
`and/or the coupling system to obtain the desired plasma
`conditions.
`
`
`
`
`
`
`Therefore,it is difficult to replace a generator from a
`
`
`
`
`
`
`
`first manufacturer with a generator from a second man-
`
`
`
`
`
`
`
`
`ufacturer and obtain the same plasma conditions, unless
`
`
`
`
`
`
`
`
`the electrical parameters of the two generators are iden-
`
`
`
`
`
`tical. Similarly, if a change is made to an impedance
`
`
`
`
`
`
`matching network in the coupling system, due to a
`
`
`
`
`
`
`
`component change for example, the same plasma condi-
`
`
`
`
`
`
`
`
`tions cannot be reproduced unless the networks are
`
`
`
`
`
`
`substantially identical. Merely changing the amplitude
`
`
`
`
`
`
`
`
`
`of the generator output will not compensate for the
`
`
`
`
`
`
`
`impedancedifferences in the generator and/or the cou-
`
`
`pling system.
`
`
`
`
`
`
`
`
`An added problem also exists when certain parame-
`
`
`
`
`
`
`
`
`ters associated with two systemsare not substantially
`
`
`
`
`
`
`
`
`identical. If two installations of plasma systems are
`
`
`
`
`
`
`
`
`made using identical generators and reactors but differ-
`
`
`
`
`
`
`
`
`ent lengths of coaxial cable (wave guides and/or other
`
`
`
`
`
`
`
`transmission mediums) are utilized in the systems then
`
`
`
`
`
`
`generally identical plasma conditions cannot be repro-
`
`
`
`
`
`
`duced. In actual practice, this lack of reproducibility of
`
`
`
`
`
`
`
`desired operating plasma conditions underrealistic con-
`
`
`
`
`
`
`
`ditions presents significant difficulties to the user. For
`
`
`
`
`
`
`example, if an RF generator requires service and/or
`
`Ex. 1023, Page 6
`
`Ex. 1023, Page 6
`
`

`

`5,302,882
`
`
`
`4
`
`
`
`
`
`
`
`that the present invention may be practiced without
`
`
`
`
`
`
`
`these specific details. In other instances, well-known
`
`
`
`
`
`
`
`processes and structures have not been described in
`
`
`
`
`
`
`
`detail in order not to unnecessarily obscure the present
`invention.
`
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`
`30
`
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`
`3
`
`
`
`
`
`
`
`corrective repair, it can only be replaced with another
`
`
`
`
`
`
`
`identical RF generator without undue tuning and ad-
`
`justment.
`
`
`
`
`
`
`Accordingly, it is appreciated that a plasma system
`
`
`
`
`
`whichis flexible in design to accommodate a multitude
`
`
`
`
`
`
`
`of generator sources, as well as coupling systems, such
`
`
`
`
`
`
`
`that the reactor could repeatedly reproduce desirable
`
`
`
`
`
`
`
`plasma operating conditions, will provide for an im-
`
`
`
`
`
`provement overthepriorart.
`10
`SUMMARYOF THE INVENTION
`
`
`
`
`
`
`
`
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`Thepresent invention describes an isolatorforisolat-
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`ing a plasma reactor from its electrical energy source.
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`Theisolatoris a low-passelectrical filter which permits
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`the passage of the fundamental frequency of an electri-
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`cal energy source supplying electrical energy to the
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`reactor, but blocks transmission of harmonic frequen-
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`cies. Because the plasma operates with non-linear impe-
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`dance characteristics and the amplitudes of these har-
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`monics affect properties of the plasma, the plasma con-
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`ditions are usually dependent upon theelectrical char-
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`sacteristics of the generator, as well as the entire cou-
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`pling system. However, by attenuating and substantially
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`preventing the harmonics from interacting with the
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`25
`generator and with the coupling circuitry that couples
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`the generator to the isolator, this dependence is elimi-
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`nated. The reactor is made to operate substantially inde-
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`pendent of the effects in the change of the generator
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`and/or the coupling system due to the harmonic isola-
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`tion and permits substitution of the generator and/or
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`the coupling system without undue hardship in tuning
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`the system to reproduce the desired plasma conditions.
`‘ BRIEF DESCRIPTION OF THE DRAWINGS
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`35
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`FIG.1 is a block diagram ofa prior art plasma reactor
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`showing a generator and a reactor coupled by a cou-
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`pler.
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`FIG.2 is a block diagram of a plasma reactor system
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`of the present invention utilizing an isolator to isolate
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`the reactor from the generator and the coupler.
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`FIG.3 is a circuit schematic diagram of a low-pass
`filter which is utilized as one embodimentfortheisola-
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`tor of FIG. 2.
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`FIG. 4 is a graphic representation of a frequency
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`response curve Voy7/Vwn ofan ideal filter and mea-
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`sured values for the circuit of FIG.3.
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`FIG. 5 is a block diagram showing four different
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`plasma system arrangements with and withoutthe isola-
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`tor of the present invention which were usedin provid-
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`50
`ing experimental results.
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`FIG.6 is a graphical representation of DC Bias volt-
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`age measured for the eight systems shownin FIG.5.
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`FIG.7 is a graphical representation of plasma volt-
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`ages measured for the eight systems shownin FIG.5.
`55
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`FIG.8 is a graphical representation of plasma cur-
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`rents measured for the eight systems shownin FIG.5.
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`FIG.9 is a graphical representation of phase differ-
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`ences for plasma voltages and currents measured for the
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`eight systems shownin FIG.5.
`DETAILED DESCRIPTION OF THE
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`PREFERRED EMBODIMENTS
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`An apparatus and method for providing an isolator
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`for a plasma reactoris described. In the following de-
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`scription, numerous specific details are set forth, such as
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`specific circuits, reactors, processes, etc.,
`in order to
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`provide a thorough understanding ofthe present inven-
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`tion. However,it will be obvious to on skilled in the art
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`Prior Art
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`Referring to FIG.1, a prior art plasma reactor system
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`is shown. A generator 10 for providing an alternating
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`currentelectric field to energize or excite the gas (or gas
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`mixture) to form the plasma is coupled to reactor 12
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`through a coupler 11. The generator 10is typically of
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`RF or microwave frequency in which the desired oper-
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`ating (fundamental) frequency is selected. The ampli-
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`tude of the output of generator 10 is adjustable.
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`Reactor 12 includes the equipment containing the
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`plasma chamber, as well as its gas handling apparatus.
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`The plasma gas (or gas mixture) is introduced into the
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`chamberforit to operate on a target device. The target
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`device for whose properties are to be modified is also
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`present in the chamber. The coupler 11 can be of a
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`variety of couplersutilized in coupling generator 10 to
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`reactor 12, For example, coupler 11 can be a blocking
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`capacitor or an impedance matching network. Al-
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`though shown as coupler 11 it also includes the com-
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`plete coupling system, including the various transmis-
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`sion cables, wave guides, connectors, etc., which com-
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`prise the transmission medium between generator 10
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`and reactor 12. The purpose of the coupler 11 is to
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`match the impedance, as well as other circuit parame-
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`ters, between the generator 10 and reactor 12, in order
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`to provide for an efficient transfer of electrical energy
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`from generator 16 to reactor 12.
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`As was earlier described in the background of the
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`invention, a particular reactor 12 is coupled to operate
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`with a particular generator 10 and coupler 11. In order
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`to obtain the desired plasma conditions, considerable
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`amount of tuning is required to obtain those desired
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`plasma conditions in reactor 12. During operation of the
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`system in FIG. 1, the amplitude of generator 10 can be
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`adjusted to vary the plasma conditions in reactor 12.
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`A significant disadvantage of the prior art plasma
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`system of FIG.1 is that the desired plasma conditions
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`typically cannot be reproduced readily, if any signifi-
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`cant characteristic of the generator 10 and/or the cou-
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`pler 11 is changed.If, for example, another generatoris
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`substituted in place of generator 10 and/or another
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`- coupler is substituted for coupler 11, then in mostin-
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`stances, unless the new generator and/or coupler is
`identical in electrical characteristics to the one substi-
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`tuted, the desired plasma conditions typically cannot be
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`reproducedin reactor 12 without further adjustment.
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`In order to obtain the desired plasma conditions
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`again, the system of FIG. 1 must be retuned to accom-
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`modate the new generator and/or coupler. Thus, the
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`system of FIG. 1 must necessarily depend on the partic-
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`ular generator 10 and coupler 11 to be tuned to operate
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`with reactor 12. In the event a componenthavingdiffer-
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`ent electrical characteristics is to be substituted, consid-
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`erable amountof time and effort are required to retune
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`the system. Thus, anytime generator 10 and/or coupler
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`11 require repair and/or service, the plasma system will
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`necessarily require a complete “shut-down” while the
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`reactor is reconfigured and retuned to the new system.
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`In practice, the lack of reproducibility of desired plasma
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`conditions in reactor 12 provides for an inflexible sys-
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`tem which may pose economic hardship to the user of
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`the plasma equipment.
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`Ex. 1023, Page 7
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`Ex. 1023, Page 7
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`

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`5
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`5,302,882
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`Present Invention
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`Referring to FIG. 2, a plasma reactor system of the
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`present invention is shown. The apparatus ofthe pres-
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`ent invention is comprised of the sameprior art genera-
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`tor 10, coupler 11 and reactor 12. However,isolator 19
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`of the present invention is inserted between coupler 11
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`and reactor 12. The purposeofisolator 19 is to isolate
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`the reactor 12 from the electrical energy generating
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`source and transmission medium provided by generator
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`10 and coupler 11.
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`Isolator 19 is designed to permit the transmission of
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`the electrical energy at the fundamental operatingfre-
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`quency of the generator 10, but to inhibit the transmis-
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`sion of higher frequencies, predominantly the harmon-
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`ics. Therefore, the harmonic content of the electrical
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`signal from reactor 12 is significantly prevented from
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`reaching coupler 11 and generator 10. Because of the
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`harmonic isolation, the plasma in reactor 12 cannot
`20
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`interact with, nor respond to changes in, the imped-
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`ances of generator 10 and coupler 11 at the harmonic
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`frequencies. Changes madeto generator 10 and/or cou-
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`pler 11 can be readily compensated by the adjustment of
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`the amplitude of the output signal from generator 10,
`25
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`which is for the purpose of adjusting the amplitude of
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`the fundamental frequency component.
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`Thus, substitutions for generator 10 and coupler 11
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`can be readily made by non-identical generators and
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`couplers, wherein the desired plasma conditions in the
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`30
`reactor 12 can be reproduced by adjusting the ampli-
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`tude of the output signal from generator 10. The har-
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`monics generated due to the nonlinearity of the plasma
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`are prevented from substantially interacting with the
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`generator 10 and/or the coupler 11. A variety of inter-
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`actions can occur, one such being the change of the
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`impedance of the generator 10 and/or coupler 11
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`caused by the harmonics. Anotherinteraction being the
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`feedback of harmonics generated by reactor 12, trans-
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`‘mitted to generator 10 and coupler 11, and reflected
`40
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`from generator 10 and/or coupler 11, so as to either
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`strengthen or cancel the harmonicsat the reactor 12.
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`Although a variety of electrical devices can be uti-
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`lized for isolator 19, the preferred embodimentutilizes a
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`tunedelectrical filter. The tunedelectrical filter of the
`45
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`preferred embodimentis a low-passfilter and is shown
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`in FIG. 3. Referring to FIG.3, the particular low-pass
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`filter utilized in the preferred embodimentis a Cheby-
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`shev filter, which is comprised.of five circuit compo-
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`nents 22-26. Two 7-sections are utilized between input
`50
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`terminals 20 and output terminals 21. The input termi-
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`nals 20 are coupled to the coupler 11 (actually the trans-
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`mission medium), while the output terminals 21 are
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`coupled to reactor 12. Oneof the input terminals 20and
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`one of the output terminals 21 are coupled together to
`35
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`operate as an electrical return (typically ground poten-
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`tial of the electrical system). Capacitor 22 is coupled
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`across the input terminals 20, while capacitor 24 is cou-
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`pled across the output terminals 21. Two inductors 25
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`and 26 are coupled in series between the non-returning
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`input and output terminals. A third capacitor 23 is cou-
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`pled between the junction of the two inductors and the
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`return line. In the preferred embodiment, capacitors 22
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`and 24 have the values of 220.9 pF, while capacitor 23
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`has the value of 310.6 pF. The inductors 25 and 26 each
`65
`have a value of 935.1 nH.
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`FIG.4 showsa graphical representation of the theo-
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`retically designed response of the filter of FIG. 3 as
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`curve 18 and the actual measured responseofthe filter
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`35
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`oo
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`Ex. 1023, Page 8
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`6
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`of FIG. 3 as curve 29. As is noted, the fundamental
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`frequencyis set at 13.56 MHz. Asis also noted in the
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`graph of FIG. 4 the second harmonic frequency of
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`27.12 MHzis well below the —3 db point. Thus, by
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`utilizing a low-pass filter for isolator 19, the harmonic
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`signals generated by the reactor 12 are largely pre-
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`vented from interacting with the generator 10 and/or
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`coupler 11. The fundamental
`frequency component
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`from generator 10 is passed through coupler 11 and
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`throughtheisolator 19 to energize the plasma in reactor
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`12. The desired operating conditions can be readily
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`achieved by adjusting the amplitude of generator 10.
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`- Accordingly, substitution of generator 10, coupler 11
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`and/or other components in the transmission medium
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`can be easily compensated by adjusting the amplitude of
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`generator 10 to obtain the desired plasma conditions in
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`reactor 12. The harmonics generated by the reactor 12
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`are essentially “trapped” by isolator 19 and are substan-
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`tially prevented from interacting with generator 10 and
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`coupler 11.
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`It is appreciated then that reactor 12 can be readily
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`coupled to a variety of generators, couplers, and/or
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`transmission medium, wherein the desired plasma con-
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`ditions can be readily reproduced by simply adjusting
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`the frequency of the generator 10 to the desired funda-
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`mental frequency and adjusting the amplitude of the
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`electrical signal from generator 10.
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`Experimental Results
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`Referring to FIG.5, block diagramsfor four different
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`plasma systems with and withoutthe isolator 19 are
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`shown. These eight different arrangements provided
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`the experimental results illustrated in FIGS. 6-9. In
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`Configuration I, generator 31 is coupled to reactor 33
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`(designated also as “Reactor A”), wherein blocking
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`capacitor35 is utilized as part of coupler 11. In Configu-
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`ration I], a second generator 32is coupled to reactor 33
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`throughthe blocking capacitor 35. In ConfigurationIII,
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`generator 32 is coupled to a second reactor 34 (desig-
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`nated also as “Reactor B’’) through the blocking capaci-
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`tor 35. In Configuration IV, generator 32 is coupled to
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`the same reactor 34, but a matching network 36 is uti-
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`lized instead of blocking capacitor 35. These four con-
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`figurations which do notincludeisolator 19 are desig-
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`natedasIo, Io, IIo, and IVoand representfour different
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`prior art arrangements. With the same four configura-
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`tions, isolator 19 (shown as dotted in FIG. 5) is now
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`included and represent four arrangementsIr, IIp, III-,
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`and IVp.
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`Theresults of the four configurations with and with-
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`out the filter of the present invention are shownin the
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`resultant graphs of FIGS. 6-9. All data represent dis-
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`charges in argon gas at 100 mTorr pressure and 200
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`volts peak-to-peak excitation at fundamental frequency
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`of 13.56 MHz.In theparticular example,thefirst gener-
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`ator 31 is model SG-1250 manufactured by R. D. Mathis
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`Co., while the second generator 32 is model ACG-5
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`manufactured by ENI Power Systems. The matching
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`network 36 is “Matchwork MW-5”, also from ENI
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`Power Systems.
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`Referring to FIGS. 6-9,in all four of these graphs,
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`the results obtained from thefirst two configurations (1
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`and II) pertaining to reactor A are shown on theleft
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`half portion of the diagram, while configurations III
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`and IV,pertaining to reactor B are shown ontheright
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`half portion of the diagram. FIG. 6 shows the measure-
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`ment of the DC Bias voltage in each of the configura-
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`tions. FIG. 7 shows the magnitudeofthe Fouriercoeffi-
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`Ex. 1023, Page 8
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`5,302,882
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`7
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`cients of the fundamental (V1) and the second harmonic
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`an electrical filter coupled between said reactor and
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`(V2) of the plasmavoltage in each ofthe four configura-
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`said first electrical source for passing said fre-
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`tions with and without the filter. FIG. 8 shows the
`quencyf, but inhibiting harmonics of said funda-
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`magnitude of the Fourier coefficient of the plasma cur-
`mental frequency f generated due to a non-linear
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`rent at the fundamental (11) and at the second harmonic
`response characteristic of said plasma in said reac-
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`frequency (12) in each of the four configurations with
`' tor from interacting with electrical circuit parame-
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`and without the filter. FIG. 9 shows the phase ¢ of the
`ters of said first electrical source, such that a sec-
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`Fourier coefficients of the voltages V1, V2 and current
`ond electrical source can be readily substituted in
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`12. The phase of the current I1 is not indicated on the
`place of the first electrical source and wherein
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`graph simply because the selected value for the phase of
`original plasma characteristics can be substantially
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`11 is chosen as zero degrees.
`restored by adjusting the amplitude ofan electrical
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`signal from said second electrical source at fre-
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`Notice that in FIG. 6, for Reactor A, the DC Bias
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`’ quency f, but without requiring retuning of said
`voltage of the reactor is measured at approximately 155
`secondelectrical source.
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`volts for configuration Ip. (without the filter). When
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`2. The improvementof claim 1 whereinsaid electrical
`generator 31 is substituted by a different generator 32,
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`filter is a low-pass electrical filter.
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`whichis the condition shown in Configuration Ilo, the
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`'3. In a plasma processing apparatus, having a reactor
`DCBiasvoltage in the reactor drops to approximately
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`for processing a reactive gas and wherein said reactoris
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`129 volts. However, whentheisolator 18, in the form of
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`coupled to a first electrical energy source which pro-
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`the low-pass Chebyshevfilter is used, the same DC bias,
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`videsan electrical signal at a fundamental frequency f to
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`approximately 138 volts,
`is measured regardless of
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`generate an electrical energy field for generation of
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`which generator 31 or 32 is used to energize the reactor
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`plasmain said reactor, and an electricalfilter is coupled
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`(Configurations Irand II). This illustrates the fact that
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`between said reactor and said first electrical energy
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`the presence of isolator 19 of the present
`invention
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`source for passing said frequency f, but inhibiting har-
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`permits for the substitution of the generator 32 for 31,
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`monics of said fundamental frequency f generated due
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`but wherein such substitution does not appreciably
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`to a non-linear response characteristic of said plasma in
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`change the DC Bias voltage of Reactor A. Similar re-
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