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`Samsung Electronics Co., Ltd. v. Demaray LLC
`Samsung Electronic's Exhibit 1057
`Exhibit 1057, Page 1
`
`
`
`U.S. Patent
`
`
`
`
`Sep. 4, 2001
`
`
`
`
`Sheet 1 of 5
`
`
`
`US 6,284,110 B1
`
`
`
`i ElectricallyCharged |
`
`
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`
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`
`
`| Components
`
`
`
`Conduit
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`24
`
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`
`
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`
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`
`
`22
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`
`
`Liquid Supply
`
`
`
`wD ak
`
`—_h co
`
`7 { t { 1 t t t ! i i i i t
`
`
`
`neff
`
`proceso
`
`14
`
`
`
`Electrically
`
`Charged
`Components
`
`
`
`
`
`Ex. 1057, Page 2
`
`Ex. 1057, Page 2
`
`
`
`Sheet 2 of 5
`
`
`US 6,284,110 B1
`(MEGAOHMS)
`IMPEDANCE
`
`1351
`
`1350
`
`
`
`F| G . 4
`
`1554
`
`
`FREQUENCY (MHz)
`
`U.S. Patent
`
`
`
`
`Sep. 4, 2001
`
`
`
`
`
`
`
`
`
`
`1356
`
`1358
`
`136)
`
`
`Ex. 1057, Page 3
`
`Ex. 1057, Page 3
`
`
`
`U.S. Patent
`
`Sep. 4, 2001
`
`Sheet 3 of 5
`
`US 6,284,110 B1
`
`0Ol
`
`Vo
`
`Ol0
`(ly)110940JDNVISISIY010°00100'0
`
`
`
`0L000°0 9“Old
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`
`
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`
`
`
`HLGIMGNVS------
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`OWOOL=2y
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`(ZH) HLOIMONY
`oO>=awr©“=Q@<=oOrrOo>=OQrs
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`
`aQo=OoCc—
`
`Ex. 1057, Page 4
`
`Ex. 1057, Page 4
`
`
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`
`
`U.S. Patent
`
`
`
`
`Sep. 4, 2001
`
`
`
`
`Sheet 4 of 5
`
`
`
`US 6,284,110 B1
`
`AAA21FSS=A=aNftS~)
`tS A
`(ZZZR\29<a51hWL
`
`S
`
`2Sls
`
`s‘
`
`9
`
`Ex. 1057, Page 5
`
`§
`
`N
`
`araAAAAAAAAAAAA \
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`
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`
`
`
`Ex. 1057, Page 5
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`
`U.S. Patent
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`
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`
`Sep. 4, 2001
`
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`
`Sheet 5 of 5
`
`
`US 6,284,110 B1
`
`
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`
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`RF POWER
`
`IN
`
`i7103 ~
`
`
`
`
`IN
`
`
`
`
`b0L
`
`FIG. 8
`
`_ WATER
`
`Ex. 1057, Page 6
`
`Ex. 1057, Page 6
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`
`1
`METHOD AND APPARATUS FOR RADIO
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`FREQUENCY ISOLATION OF LIQUID HEAT
`TRANSFER MEDIUM SUPPLY AND
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`
`DISCHARGE LINES
`
`
`FIELD OF THE INVENTION
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`The present invention pertains to radio frequency isola-
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`tion to heat transfer supply and discharge lines through
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`which electrically conductive heat transfer medium flows.
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`Moreparticularly, the present invention pertains to high-
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`impedance heat transfer supply and discharge lines for use
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`in sputtering and etching equipment used in the semicon-
`
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`ductor industry.
`BACKGROUND OF THE INVENTION
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`Sputter coating is a coating process that involves the
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`transport of almost any material from a source, called the
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`target, to a substrate of almost any material. The process
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`takes place in a reduced pressure chamber containing argon
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`or other process gas. The reduced pressure, or vacuum, is
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`neededto increase the distance that the sputtered atoms can
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`travel without undergoing collision with each other or with
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`other particles. The argon gas is ionized which results in a
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`bluish-purple glow of a plasma. Ejection of target source
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`material
`is accomplished by bombardment of the target
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`surface with gas ions that have been accelerated toward the
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`target by a high voltage. As a result of momentum transfer
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`between incident ion and target, particles of atomic dimen-
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`sion are ejected from the target. These ejected particles
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`traverse the vacuum chamber and are subsequently depos-
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`ited on a substrate as a thin film. A similar process is
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`generally used in sputter etching, however,
`the target is
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`replaced by the object to be etched.
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`Radio frequency (RF) power, introduced into a process
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`chamber via an inductive coil encircling the chamber, is
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`often advantageously used in sputter coating and etching to
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`enhance the development of the plasma. RF sputter coating
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`and etching allows the deposition of insulating as well as
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`conductive materials and the etching of substrates, utilizing
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`lower voltages, such as 500 to 2,500 V, to accelerate the
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`argon gas ions to the target or substrate being etched. The
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`lowervoltage at the same powerprovides higher deposition
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`and etching rates with reduced substrate damage.
`In
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`addition, RF power may be used to bias the substrate to
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`change the characteristics of film deposition, especially for
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`insulating films. Such RF powerbiasing of the substrate can
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`improve adhesion and the added heat due to the bias power
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`can provide higher mobility of source material on the
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`substrate surface which can improve step coverage. Lower
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`resistivity and changesin film stress can be obtained with RF
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`voltage bias, as well. Gas incorporation into the film is
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`usually increased. Oxide films such as silicon dioxide will
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`have improved optical qualities and higher density when RF
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`bias is used during deposition.
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`Electronically isolating certain system components with
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`respect to RF energization is desirable when using RF power
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`in sputtering and etching. Otherwise, the plasma may be
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`altered, adversely affecting the sputtering or etching process.
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`In the case of RF biasing of the substrate,
`lack of RF
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`isolation can result
`in undesired RF power dissipation.
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`Consequently, it is desirable to RF isolate certain compo-
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`nents within a sputtering or etching system. This RF isola-
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`tion providesan interruption of a potential RF path to ground
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`from the RF energized component.
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`Another aspect of sputtering and etching systemsis the
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`requirement to thermally condition (heat or cool) certain
`
`
`
`US 6,284,110 B1
`
`
`2
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`
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`
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`
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`system components or the substrate. This is usually accom-
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`plished by circulating a liquid heat transfer medium in heat
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`transfer relationship to the system component, or substrate
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`support, as the case may be. As previously mentioned, the
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`substrate may be biased by RF power for improved depo-
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`sition or etching characteristics. Under such conditions, the
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`heat transfer components must beelectrically isolated from
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`the RF applied to the substrate support. For example, in
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`sputter coating target cooling is often desirable, whereas in
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`sputter etching wafer cooling may be needed.
`In such
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`situation, a liquid coolantis circulated through the susceptor
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`or wafer support, as the case may be. In wafer processing
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`configurations wherein an RF coil
`is placed around the
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`sputtering or etching chamber to create and/or enhance the
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`the RF coil has resistance that generates heat,
`plasma,
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`requiring the RF coil to be cooled by circulating a liquid heat
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`transfer coolant medium through the RF coil. The heat
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`transfer component mustbe isolated from the RF applied to
`the RF coil.
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`A problem arises when cooling an RF coil and/or heating
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`or cooling a substrate support or target holder as a result of
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`the fact that the heat transfer media, usually water, in the
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`lines used for circulating the heat transfer media through the
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`coil or substrate supportor target interferes with RF isolation
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`of components such as the RF coil, substrate support, target
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`holder, etc. Maintaining the desired RF isolation while
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`circulating a liquid heat
`transfer medium is required to
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`prevent degradation of the sputtering or etching process.
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`Wateris typically used as the heat transfer liquid medium
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`due to the safety, low cost, and ready availability of water.
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`For example,
`in a simple open cooling system, cool tap
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`water is supplied through a supply line to the sputtering or
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`etching system component to be cooled at which place the
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`wateris circulated and thereafter discharged to a drain via a
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`discharge line. Tap water typically contains dissolved min-
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`erals that cause the water to be less chemically reactive to
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`many materials. However, the dissolved minerals also create
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`ions in the water that make the waterelectrically conductive,
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`which can be disadvantageous when heating or cooling
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`sputtering or etching system components energized with RF.
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`Consequently, in many applications, the electrically conduc-
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`tive tap wateris first purified to remove the minerals, making
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`it resistive. Resistive water is corrosive to many materials
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`such as metals. As a consequence, a balance is sought in the
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`level of water purification to achieve an acceptable level of
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`conductivity versus corrosiveness.
`In addition, chemical
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`additives are generally added to the water to mitigate the
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`corrosive effects, incurring additional expense and inconve-
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`nience in preparation and disposal of the liquid. These
`additives in some instances introduce detrimental effects
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`such as reducingtheresistivity of the water or decreasing the
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`environmental safety of the liquid. Moreover, systems uti-
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`lizing this type of componentcooling or heating have to be
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`designed to accommodate a certain amount of electrical
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`powerloss through the liquid heat transfer medium.
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`Achieving the requisite balance in water purity involves
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`the expense of buying or processing the water to the appro-
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`priate purity level. Filtering and monitoring of the water is
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`then required to maintain the purity within the acceptable
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`range. Even with these additional requirements,there is still
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`some degradation of performance and reliability of the
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`components heated or cooled by the resistive water.
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`Other relatively abundant and environmentally safe heat
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`transfer liquids are also available; however, many of these
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`are alsoelectrically conductive, but by their nature cannot be
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`processed to a more resistive condition and are thus inap-
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`propriate for use.
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`10
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`15
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`20
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`25
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`30
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`35
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`45
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`50
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`55
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`60
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`65
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`Ex. 1057, Page 7
`
`Ex. 1057, Page 7
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`US 6,284,110 B1
`
`
`3
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`Relying on the resistivity of the water to provide the RF
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`isolation dictates that the water supply and dischargelines be
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`increased in length, since the electrical resistance afforded
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`by the water is a function of water path length to ground,
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`assuming the resistivity of the water and diameter of the
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`water lines are fixed. For example, typical resistive water
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`cooling systems employ 12 to 13 feet of polypropylene
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`tubing of about a quarter inch in outer diameter in each of
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`the water supply and discharge lines to generate 1 MQ of
`resistance.
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`Consequently, what is needed are high impedance liquid
`
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`heat transfer medium supply and discharge linesthat are not
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`dependentprincipally uponthe resistivity of the heat transfer
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`liquid in isolating radio frequency energized components.
`SUMMARYOF THE INVENTION
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`These and other needs are satisfied in accordance with
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`certain principles of the present invention by a) coiling at
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`least a portion of the liquid heat transfer medium supply
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`and/or discharge lines such that
`the lines have a high
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`inherent inductance and b) connecting a capacitive element
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`in parallel with the coiled lines, with the capacitance being
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`chosen such that the resonant frequency, and thus the highest
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`impedance, of the coiled line /capacitor combination occurs
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`at the RF frequency in use.
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`The present invention, by virtue of being a passive device,
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`requires no powersource, and is less sensitive to variations
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`in the electrical conductivity of the liquid, thus eliminating
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`expensive liquid processing and filtering. Other advantages
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`include reducing the length of liquid heat transfer medium
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`supply and discharge lines normally employed.
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`These and other objectives and advantages of the present
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`invention will be more readily apparent from the following
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`detailed description of the embodiments.
`BRIEF DESCRIPTION OF THE DRAWINGS
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`FIG. 1 is a block diagram of liquid cooled or heated
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`system componenthaving high impedanceliquid heat trans-
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`fer medium supply and dischargelines.
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`FIG. 2 is an electrical schematic of the liquid cooled or
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`heated system component of FIG. 1 wherein the high
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`impedance liquid heat transfer medium lines are shown in
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`both a fixed capacitance and variable capacitance embodi-
`ment.
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`FIG. 3 is a diagrammatic perspective view of a fixed
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`capacitance embodimentof a high impedanceline of FIGS.
`1 and 2.
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`FIG. 4 is a plot of impedance as a function of frequency
`for an illustrative embodiment.
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`FIG. 5 is an equivalent electrical schematic of a high
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`impedance line wherein the electrical resistance of the
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`components is shown.
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`FIG. 6 is a plot of the impedance and bandwidth of the
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`high impedance line of FIG. 5 shown as a function of the
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`resistance ofthe coil, illustrating that as DC resistance of the
`coil increases and/or resistance of an additional resistor in
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`parallel to the coil increases, the peak impedance decreases
`and the bandwidth widens.
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`FIG. 7 is a cross sectional depiction of a soft etching
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`system utilizing liquid cooling of an RF coil and a wafer
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`support, with the cooling supply and discharge lines appro-
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`priate candidates for the high impedancelines of this inven-
`tion.
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`FIG. 8 is a depiction of the cooling line to the RF coil
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`incorporating a high impedance conduit on the supply side.
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`4
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`FIG. 9 is a depiction of the cooling line to the wafer
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`support, incorporating a high impedance conduit to both the
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`supply and discharge sides.
`DETAILED DESCRIPTION OF THE
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`INVENTION
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`10
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`FIG. 1 diagrammatically illustrates a thermally condi-
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`tioned system 10 having a closed heat transfer system 12 for
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`heating or cooling one or moreelectrically charged compo-
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`nents 14. A heat exchanger 16 brings a liquid heat exchange
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`medium, such as water, into thermal and electrical contact
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`with the electrically charged components 14. The heat
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`exchanger 16, for example, may be metal tubing (not shown)
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`placed in physical contact with the components 14 or in
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`contact with a thermally conducting material (not shown)
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`located between,and in heat transfer contact with, the tubing
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`and the components 14. The closed heat transfer system 12
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`has a liquid supply line 18, and a liquid return heat line 20,
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`generally referred to as water lines. The liquid is processed
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`and pressurized by a liquid supply 22. Interposed in the lines
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`18, 20 are high impedance liquid conduits 24, 26 constructed
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`in accordance with the principles of the invention.
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`FIG. 2 showsan electrical schematic for the system 10 of
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`FIG. 1. The electrically charged components 14 are shown
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`as being electrified by a sinusoidal power supply 28 having
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`an output v(f), where the frequencyf is generally in the radio
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`frequency (RF) band. The supply heat transfer medium line
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`18 is shown having a knownresistivity R1 and the return
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`supply line 20 is shown having a knownresistance R2, these
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`values being a function of the resistivity of the liquid in the
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`lines 18 and 20, the length and diameter of the lines 18, 20,
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`and the resistivity of the material from which the lines 18
`and 20 are made.
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`The high impedance conduit 24 is shown as having an
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`inductor L1 electrically in parallel with the parallel combi-
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`nation of a fixed capacitor C1 and a trim capacitor C,.
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`Parallel capacitances are additive. Therefore, a small trim
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`capacitor can adjust
`the equivalent capacitance for the
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`overall capacitive element. Capacitors are electrical circuit
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`elements used to store electrical charge temporarily, typi-
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`cally comprising conductors separated by a dielectric.
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`Consequently, capacitors C1 and C, contribute to electrical
`characteristics but not to fluid flow characteristics of the
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`high impedance conduit 26.
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`The return high impedance conduit 26 is shown as having
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`an inductor L2 in parallel with a fixed capacitor C2. Both
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`conduits 24, 26 are referenced to ground. The embodiments
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`shown in FIG. 2 are exemplary and other embodiments are
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`contemplated. For instance, a single variable capacitor could
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`be used, or a plurality of fixed capacitors in parallel could be
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`used, to achieve the desired equivalent capacitance.
`The resistance values of R1 and R2 would dictate the
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`electrical power loss through the lines 18, 20 but for the
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`introduction of the high impedance conduits 24, 26.
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`However, the contribution of the resistance values of R1 and
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`R2 can be discounted as negligible as compared to the
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`conduits 24, 26, which would have the equivalent imped-
`ance of:
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`_ (Z#Zc)
`“(ZL +Zc)
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`Where Z, is the impedanceof an inductor(i.e., j2fL) and
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`Z, is the impedanceofthe capacitor(i.e., 1/j2afC). This
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`equivalent impedance Z,,, is maximized at the reso-
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`Ex. 1057, Page 8
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`Ex. 1057, Page 8
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`5
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`nant frequencyf, the inductor—capacitor combination,
`which can be calculated as:
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`US 6,284,110 B1
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`10
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`15
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`20
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`25
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`30
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`35
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`45
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`the
`In the illustrative embodiment shown in FIG. 3,
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`adjustable high impedance conduit 26 is designed for the
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`resonant frequency of 13.56 MHz, one of the standard
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`frequency used in the industry exciting the argon gas in
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`etching and sputter deposition systems. Lower frequencies,
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`such as 450 kHz, are often used when exciting inductively
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`couple plasmas. The water line 20 may be of an electric
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`insulative material tubing of about a quarter inch in outer
`diameter. The water line 20 is coiled into a five-turn coil L2
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`of two inch outer diameter, resulting in an inductance value
`of about 1.0 mH. Moreturnsfor the coil 29 could be chosen
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`to increase the impedance but this would trade off higher
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`impedance for a narrower bandwidth of a high impedance
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`region and would also increase the overall length of the coil
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`29. An enclosure 44 surrounds the coil 29, providing pro-
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`tection from physical damageto the coil 29. Preferably, the
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`enclosure 44 would be a grounded Faraday RF shield, a
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`conductive enclosure that protects internal components from
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`external electromagnetic radiation and reduces emission of
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`electromagnetic radiation from the coil 29 to the external
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`environment. A capacitor C2 of 332 pF is operatively placed
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`across the coil 29. Electrical connection between the liquid
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`and the capacitor C2 could be achieved in numerous ways.
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`For instance, an electrical conductor could be inserted
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`through the water line 20. Also, the coil could have metal
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`connectors at each end to aid in assembly and capacitor C2
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`could contact these connectors. Preferably, the capacitor C2
`and connections to the coil 29 would be insulated. These
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`inductance and capacitance values result in an impedance
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`for the high-impedance conduit of over 30 MQ, as shown in
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`FIG. 4. This value compares to a requirement of 900 feet of
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`water line 20 to achieve a comparable impedance if merely
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`coiling the water line 20 without the capacitor C2.
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`Referring to FIG. 5, an equivalent electrical schematic is
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`shown for a high impedance conduit 30 wherein the elec-
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`trical resistance of the components is considered. A first
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`resistor R,, shown in series with coil 32, models the resis-
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`tance of the coil 32 and liquid therein. For example, the coil
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`32 maybe of conductive material resulting in a low value for
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`first resistor R,. Alternatively, the coil 32 may be of insu-
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`lative material such that R, results from the characteristics
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`of the liquid, and thus R, has a higher resistance value. A
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`second resistor R,, in parallel to the series combination of
`50
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`the coil 32 and first resistor R,, represents an additional
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`resistor added to a high impedance conduit 30 to control the
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`peak impedance and bandwidth. The trimmable capacitor 34
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`is shown in parallel with the series combination of the coil
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`32 and first resistor R,. A second resistor R, is shown in
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`parallel to the series combination of the coil 32 and first
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`resistor R, and alsoin parallel to the trimmable capacitor 34.
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`Secondresistor R, represents an additional resistor added to
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`a high impedance conduit 30 to control the peak impedance
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`and bandwidth, or accounts for resistance characteristics of
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`trimmable capacitor 34.
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`Consideration of the resistance of the coil 32 may be
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`required, for example, in selecting an appropriate RF power
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`supply (not shown) to a componentin a sputtering or etching
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`system, for instance, when the specific amount of electrical
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`powerdissipated by the heat transfer system 12 is critical. As
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`another example, the frequency of the RF power supply may
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`not be constant, thus dictating a wider operable bandwidth
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`55
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`6
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`of the high impedance conduit 30. Consequently, the full
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`electrical responseof the heat transfer system 12 considering
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`resistance provides a more accurate prediction. Design
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`choice, such as choice of capacitive element 34 with appro-
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`priate resistive characteristics, may be made for the desired
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`peak impedance and width of band reject characteristics.
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`Referring to FIG. 6, a plot of the impedance and band-
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`width of the high impedance conduit 30 of FIG. 5, illustrat-
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`ing that as DC resistance R, of the coil 32 increases or the
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`additional resistance of a second resistor R, in parallel to
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`coil 30, decreases, the peak impedance decreases and the
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`bandwidth increases of the high impedance conduit 30.
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`Referring to FIG. 7, a cross sectional depiction is shown
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`of a soft etching system 50 utilizing water coolant heat
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`transfer lines 52, 54 for a housing seal 56, and for a wafer
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`support 58, respectively. An RF coil 60a for enhancing the
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`plasma, shownencircling the bell jar vacuum process cham-
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`ber 62, is water-cooled copper tubing, the copper providing
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`an electrical conductor for the RF power, with the frequency
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`of the RF power being 450 kHz. The RF coil 60ais a portion
`of a heat transfer line 605 shown and discussed below for
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`FIG. 8.
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`A high vacuum is maintained within the enclosure 61
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`formed by a bell jar vacuum process chamber 62 and
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`aluminum housing 64, in part by an o-ring seal 66 between
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`an aluminum support 68 anda stainlesssteel flange 70 of the
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`aluminum housing 64. High vacuum is maintained at the
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`contact betweenthe bell jar 62 and the aluminum support 68
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`by a high temperature VITON o-ring (not shown). To
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`prevent thermal damageto the o-ring seal 66, cooling water
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`is delivered to the support 68 by heat transfer line 52. Heat
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`transfer line 52, however, is not an appropriate candidate for
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`high impedance circuits since the line 52 is at ground
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`potential.
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`Heattransfer line 54 is an appropriate candidate for high
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`impedance conduits since line 54 is near RF energized
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`components.
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`The wafer support 58 has an internal volume 72 open to
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`atmospheric pressure through its downward opening 74. A
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`silicon wafer 76 sets upon an RF energized table 78, the RF
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`energy biasing the wafer 76, with the RF power supplied
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`having a frequency of 13.56 MHz.
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`Wafer hold-down components 80 are similarly RF ener-
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`gized and provide physical support to the quartz clamp 82
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`holding down the silicon wafer 76. The quartz clamp 82 is
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`held in position by support 84 beside the wafer receptacle
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`58. The upper portion of wafer receptacale 58, the susceptor
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`85, is raised to contact the clamp 82 and lowered to allow
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`placement of a wafer 76 on the table 78 by actuating the
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`bellowslike lower portion 86 of the wafer receptacle 58.
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`The table 78 has a downwardly extending thin flange 87,
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`made thin to minimize heat loss from the top of the heated
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`table 78 to the base 88 of the heated table 78, which provides
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`physical contact and support to the wafer hold-down com-
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`ponents 80. The base 88 in turn is supported by a receptacle
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`support 90, generally made ofstainless steel, which for ease
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`of manufacturing is shown composed of a plurality of
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`components. Internal seals 92 are thus provided to prevent
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`atmospheric pressure in the internal volume 72 from escap-
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`ing to the enclosure 61. RF isolation between the RF
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`energized base 88 and the receptacle support 90 is provided
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`by ceramic flange 94. Seals 96 prevent atmospheric pressure
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`from escaping past the ceramic flange 94. The bottom of the
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`flange 87 of the heated table 78 is positioned near the
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`ceramic flange 94 andits seals 96. The flange 87 is suscep-
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`tible to damagedueto heat as are the seals 96. Consequently,
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`the cooling water line 54 is provided at this point.
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`Ex. 1057, Page 9
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`Ex. 1057, Page 9
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`US 6,284,110 B1
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`7
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`The importance of isolating RF powerin the soft etching
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`system 50 is shown bythe addition of RF insulating ring 98,
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`a portion of the receptacle support 90 in close non-touching
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`proximity to the wafer hold-down components 80. The space
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`between the RF insulating ring 98 and the wafer hold-down
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`components 80 is so small as to form a dark space shield, a
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`space too small
`to allow the formation of a plasma.
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`Similarly,
`isolating heat transfer lines 52, 54, and 62 is
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`necessary to prevent RF power from generating plasma,or
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`otherwise conducting power to ground, at other locations.
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`The soft etching system 50 is exemplary, with other
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`sputter coating and sputter etching systems having heat
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`transfer lines and RF powered components similarly being
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`candidates for high impedance conduits.
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`Referring to FIG. 8, the cooling line 606 to the RF coil
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`60a is shown incorporating a high impedance conduit 100
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`on the supply side 102. The cooling line 605 is energized by
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`RF poweras represented by capacitive coupling 103.
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`Referring to FIG. 9, the cooling line 54 to the heated table
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`78 is shown incorporating high impedance conduits 104,
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`106 to both the supply side 108 and discharge side 110,
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`respectively. The cooling line 54 is energized by RF power
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`as represented by capacitive coupling 112.
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`Although the embodiments described utilize passive
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`capacitive elements to create a first-order notch filter,
`it
`would be further consistent with the invention to utilize
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`active elements such as operational amplifiers. In addition,
`it would be further consistent with the invention to create
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`higher-order notch filters or other filtering characteristics.
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`For example, the sputtering or etching system may have
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`components energized by an RF power source capable of
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`varying the frequency of the RF power. Active components
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`within a high impedance conduit can be employed to tune
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`the impedance to correspond to the frequency of the RF
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