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`PATENT DATE
`
`PATENT
`NUMBER
`
`!8
`OB/567224
`12/04/95' ~;;;r_
`
`08/567,224
`
`FIUNQ OAT£ CLASS
`
`GROUP ART UNIT
`).-1-1"2
`lfO;).; '
`DANIEL L. FL AMM, WALNUT CREEi<, CA ; 1'.:,EOFH:.V VI NO(:lRADOV, YAMANASHI,,. ,TAPAN;
`SHIMAO YONEYAMA, YAMANASHI,
`.JAPAN .
`
`j.,
`
`SUBCLASS
`
`' i
`
`\ ·-- \
`
`"XAMINER
`
`**CONTINUING DATA******** *********** *}
`VERIFIED
`
`'f
`**FOREIGN/PCT APPLICATIONS****** ** ****
`VERIFIED
`
`11
`)
`
`FOREIGN FILING LICENSE GRANTED 06/22/96
`O Y" 0 no
`0 Y" 0110
`
`STATE OR SHEETS TOTAL
`COUNTRY DRWGS. CLAIMS
`
`FILING FEE
`INDEP.
`CLAIMS RECEIVED
`
`ATTORNEY'S
`OOCKETNO.
`
`F°""lgn prtortty ctolm..i
`35USC118condltlonomo1
`
`AS
`FILED
`
`......
`
`ine?s lnltta&
`E
`RICHARD T OGAWA
`TOWNSEND t, TOWNSEND & CREW
`TWO EMBARCADERO CENTER 8TH FLOOR
`SAN FRANCISCO CA
`94111
`
`r·
`
`PROCESS tiEPEND-ING ON f'LASMA DISCHARGES SUSTAINED BY INDUCTIVE
`COUPLING
`
`U.S; DEPT. of COMMERCE• Patent and Trademark Offlce-PCT-436L (rev. 7·94)
`
`NOTICE OF ALLOWANCE MAILED
`
`Assistant Examiner
`
`ISSUE FEE
`Date Paid
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`Total Claims
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`Pri'nt Claim
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`DRAWING
`Sheets D,wg. Figs. Drwg.
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`Print Fig.
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`ISSUE
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`PREPARED FOR ISSUE
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`WARNING: The lnformalfon diselosed herein may be restricted. Unauthorized dlsdosure may be prohibited
`by the United Slates Code Tine 35, Sections 122. 181 and 368. Possession outside the U.S.
`Patent & Trademark Office Is restricted to authorized employees and contractors·only.
`
`(cid:55)(cid:82)(cid:78)(cid:92)(cid:82)(cid:3)(cid:40)(cid:79)(cid:72)(cid:70)(cid:87)(cid:85)(cid:82)(cid:81)(cid:3)(cid:47)(cid:76)(cid:80)(cid:76)(cid:87)(cid:72)(cid:71)
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`
`(FACE)
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`Page 1 of 130Page 1 of 130
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`SEARCHED
`
`Class
`
`Sub.
`
`Date
`
`Exmr.
`
`SEARCH NOTES
`
`Date
`
`Exmr.
`
`INTERFERENCE SEARCHED
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`Date
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`
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`
`Page 4 of 130Page 4 of 130
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`08/ 567224
`PATENT APPLICATION SERIAL NO.
`------
`
`U.S . DEPARTMENT OF COMMERCE
`PATENT AND TRADEMARK OFFICE
`FEE RECORD SHEET
`
`\
`
`(
`
`PT0-1556
`(5/87)
`
`
`
`Page 5 of 130Page 5 of 130
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`

`

`1 -
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`I
`, I,
`t
`
`BAR COOE wa
`
`-
`
`lllllllllllllllllllllll~llllllllllllllllllll~II
`
`U .S. PATENT APPLICATION
`
`SEl\lAl NUMBER
`
`ALING DATI:
`
`CIASS
`
`GROUP AIIT UNIT
`
`08/567,224
`
`12/04/95
`
`427
`
`1112
`
`DANIELL. FLAMM, WALNUT CREEK, CA; GEORGY VINOGRADOV, YAMANASHI, JAPAN;
`SHIMAO YONEYAMA, YAMANASHI, JAPAN.
`
`**CONTINUING DATA*********************
`VERIFIED
`
`**FOREIGN/PCT APPLICATIONS************
`VERIFIED
`.
`
`FOREIGN FILING LICENSE GRANTED 06/22/96
`
`STATE OR
`COUNTRY
`
`SIIEETS
`DRAWING
`
`TOTAL
`aAIMS
`
`INOEPENOEHT
`Cl.AIMS
`
`FU.INGFEE
`RECENED
`
`ATTORNEY DOCKET NO.
`
`CA
`
`13
`
`20
`
`3
`
`$880.00
`
`16655-000300
`
`RICHARDT OGAWA
`TOWNSEND & TOWNSEND & CREW
`TWO EMBARCADERO CENTER 8TH FLOOR
`SAN FRANCISCO CA 94111
`
`I
`
`PROCESS DEPENDING ON PLASMA DISCHARGES SUSTAINED BY INDUCTIVE
`COUPLING
`
`This is to certify that annexed hereto is a true copy from the records of the United States
`Patent and Trademark Office of the application wn,ch is identified above.
`By autllority of tho
`COMMISSIOIIER Of PATENTS ANO TRAOEMAIIKS
`
`Dall
`
`
`
`Page 6 of 130Page 6 of 130
`
`

`

`'.. -..
`
`08/ 567214
`
`Atty. Docket No . ...,166""'""'55.._-0003=""00=------(cid:173)
`
`~Itxpress Mail" Label No. EM232444814US
`
`. .
`1° 1 I
`Date of Deposit December 4. 1995
`I
`, 1
`'
`
`Washington, D. C. 20231
`
`Sir:
`Transmitted herewith for filing is the
`[X] patent application of
`( J design patent application of
`[ J continuation-,in-part pa':/:J;!lication of
`lnventor(s): Daniel L( ~ rg y Vinogradov, Shimao Yoneyama
`
`I hereby certify that this is being deposited with the
`United StateS Postal Service "Express Mail Post Office
`to Addressee" service under 37 CFR 1.10 on the date
`and is
`il)di
`sed to
`of Pa
`
`By~',:e_~~~~-~=tL.~=-:....:....:::..::....::...=....:::__
`
`For: PROCESS DEPENDING ON P4\SMA DISCHARGES SUSTAINED BY INDUCTIVE COUPLING
`
`( ) This application claims priority from each of the following Ap~lica~on Nos.lfiling dates:
`______ /
`;
`; - - - -~ ' - - - - - -
`I
`
`i
`Enclosed are:
`[X] Patent Application (including 36 pages specification, 3 pages claims, 1 page abstraet).
`[X] 13 sheet(s) of [ J fon_nal [X] infonnal drawing(s).
`[] An assignment of the invention tO - - - - - - - - - -~ - - - - - , -- - -- - - - (cid:173)
`[ ] A [ ) signed ( ) unsigned Declaration & Power of Attorney.
`[ J A [ J signed [ J unsigned Declaration.
`[] A Power of Attorney.
`•
`1
`[ ) A verified statement tO establish small entity status under 37 CFR 1.9 and 37 CFR l.27 [ ] is enclosed [ ] was filed
`in the earliest of the above-identified patent application(s).
`[ J A .certified copy of a
`[ ] Information Disclosure Statement under 37 CFR 1.97.
`[X] Postcard.
`
`application.
`
`i
`In view of the Unsigned Declaration as filed with thls!appllcation and pursuant to 37 CFR §1.53(<1);
`Applicant requests 'deferral of the flling fee until sub.:Uisslon of the Missing Parts of Application.
`
`I
`
`DO lli!I CHARGE TIIE FILING FEE AT THIS TIME.
`
`Telephone:
`(415) 326-2400
`no\wodM66SS\)..app.cro
`
`,j
`
`,
`
`I
`
`I '
`
`'
`
`I
`
`
`
`Page 7 of 130Page 7 of 130
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`

`

`08/567224 .
`
`Any. Docket No. ~166=5S.._--000==3=00..__ _ __ __ _
`
`. "f press Mail" Label No. EM232444814US
`Date J, Deposit December 4. 1995
`
`I
`
`Sir:
`. Tranmtitted herewith for filing is the
`[X] patent application of
`[ ] design patent application of
`[ ] continuation-in-part patent application of
`
`Inventor(s): Daniel L. Flamm, Geor~ Vinogradov, Shimao Yoneyama
`
`For: PROCESS DEPENDING ON PLASMA DISCHARGES SUSTAINED· BY INDUCTIVE COUPLING
`
`I
`[ ] This application cla.irns priority from each of the following Application Nos./ftling dates:
`_____ ./
`•
`I
`
`Enclosed are:
`[X] Patent Application (including 36 pages specification, 3 pages claims, 1 page abstraet).
`(X] 13 sheet(s) of [ ] formal [X] informal drawing(s).
`[ J An assignment of the invention to-----------------------(cid:173)
`[ ] A [ ] signed [ J unsigned Declaration & Power of Attorney.
`[ ] A [ ] signed [ ] unsigned Declaration.
`[ ] A Power of Attorney.
`[ l A verified statement to establish small entity status under 37 CFR 1.9 and 37 CFR 1.27 [] is enclosed [] was filed
`in the earliest of the above-identified patent application(s).
`[ J A certified copy of a
`application.
`[ l Information Disclosure Statement under 37 CFR 1.97.
`[X] Postcard.
`
`In view of the Unsigned Declaration as flied with this;appllcatlon and pursuant to 37 CFR §l.S3(d),
`Applicant requests deferral of the filing fee untll subin~lon or the Missing Parts of Application.
`
`DO ~ CHARGE THE FILING FEE AT nns TIME.
`
`Telephone;
`(415) 326-2400
`
`- ------
`
`
`
`Page 8 of 130Page 8 of 130
`
`

`

`TOWN~~~~d CREW
`Ste.•!lllt Str T~r ~ f
`Goe Market ~ 'm~!\i
`San Francisco.~~ ' Wfb:f ,·
`'D?Aor.~
`(415) 326-2400
`
`I
`PATENT APPLICATION ..
`COMMISSIONER OF PATENT AND TRADEMARKS
`Washington, D. C. 20231
`·
`
`. Sir:
`Transmitted herewith for filing is the
`[X} patent application of
`[ J design patent application of
`[ ] continuation-in-part patent application of
`
`I
`
`08/567224
`
`Atty. Docket No . ...,166=55'---000=3,.,.,00""------(cid:173)
`
`"Express Mail" Label No. EM232444814US
`
`ol1e J, Deposit December 4, 1995
`
`.
`
`t
`
`I hereby certify that this is being deposited with the
`United States Postal Service "Express Mail Post Office
`to Addressee" service under 37 CFR 1.10 on the date
`indica
`and isU!!ldre;sed
`of Pa
`W11uliu,Jf'i
`
`Inventor(s): Dani.el L. Flamm, Geora1 Vioogradov, Shimao Yo.neyama
`.
`'
`For: PROCESS DEPENDING ON PLASMA DISCHARGES SUSTAINED BY INDUCTIVE COUPLING
`
`[ ] This application claims priority from each of the following Application Nos./filing dates:
`'----- -----·------
`-----·'
`,
`Enclosed are:
`[X} Patent Application (including 36 pages specification, 3 pages claims, 1 page abstract).
`[X) 13 sheet(s) of [] fonrlal [X) infonnal drawing(s).
`[ J An assignment of the inv en t ion . to - - - - - - - - - - - - - - - - - - - - - - - (cid:173)
`[ J A [ ] signed [ J unsigned Declaration & Power of Attorney.
`[ J A [ ] signed [ ] unsigned Declaration.
`[ ] A Power of Attorney.
`[ ] A verified statement to establish small entity status under 37 CFR 1.9 and 37 CFR 1.27 [] is enclosed [] was filed
`in the earliest of the above-identified patent application(s).
`[ ] A certified copy of a
`[ J Information Disclosure Statement under 37 CFR 1.97.
`[X) Postcard.
`
`application.
`
`In view of the Unsljtned Declaration as filed with thls;appllcatfon and punuant to 37 CFR §1.53(d),
`Applicant requests deferral of the flllng fee until submission of the Missing Parts of Application.
`
`DO NOT CHARGE THE FILING FEE AT TinS TIME.
`
`Telephone:
`(415) 326-2400
`
`
`
`Page 9 of 130Page 9 of 130
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`

`

`...• I
`
`I \ •• ,_
`
`I
`
`•
`
`i6655-003000
`
`I
`
`P;ATENT APPLICATION
`'I
`,
`
`PROCESS DEPENDING ON PLASMA DISCHARGES
`SUSTAINED BY INDUCTI;v'E COUPLING
`
`I
`
`'
`
`Inventors:
`
`Dapiel L. Flamm, a citizen of the !united States, residing at 476
`Green View Drive, Walnut Creek, California 94596;
`
`Georgy Vinogradov, a citizen of Russia, residing at Dragons
`Mansion Apt. 306, 5860-5 R'yuchi, Futaba-cho, Kitakomagun,
`Yamanashi, 4QO-Ol Japan; and
`
`Shimao Yoneyama, a citizen Qf Japan, residing at 5875-4 Ryuchi,
`Futaba-cho, iKitakomagun,' Yamanashi, 400-01 Japan.
`I ~
`
`I
`
`Assignee:
`
`M~ Electronics Co., 1=,~.
`
`,. i.;
`
`Entity Status:
`
`Large
`
`l '
`
`I
`.,1
`TOWNSEND and TOWNSEND and CREW(cid:173)
`Steuart Street Tower
`One Market
`San Francisco, CA 94105
`(415) 326-2400
`
`. :·,·
`- - - - - -------=-------
`
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`Page 10 of 130Page 10 of 130
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`16655-003000
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`PROCESS DEPENDING ON PLASMA DISCHARGES SUSTAINED
`BY INDUCTIVE COUPLING
`
`I
`
`j
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`•
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`BACKGROUND OF .THE INVENTION
`This invention relates generally to plasma processing. More
`particularly, the invention is for plasma processing of devices using an inductive
`dischru:ge . . This in~ention is illustrated in an example with regard to plasma
`etching and resist stripping of semiconductor devices. The invention also is
`illustrated with regard to chemical vapor deposition (CVD) of semiconductor
`devices. But it will be recogniud that the invention has a wider range of
`applicability. Merely by way of example, the invention also can be applied in
`other plasma etching applications, and deposition of materials such as silicon,
`silicon dioxide, silicon nitriqe, polysilicon, among others.
`Plasma processing techniques can occur in a variety of
`semiconductor 11$1Ufacturl'ng processes. Examples of plasma processing
`techniques occur in chemical dry etching (CI>E), ion-assisted etching (IAE), and
`plasma enhanced chemical 'vapor deposition (PECVD), including remote plasma
`deposition (RPCVD) and ion-assisted plasma enhanced chemical vapor· deposition
`(IAPECVD). These plasma processing techniques often rely upon radio frequency
`power (rt) supplied to an inductive coil for providing power to gas phase species in
`forming a plasma.
`Plasmas can be used to form neutral species (i.e., uncharged) for
`purposes of removing or forming films in the manufacture of integrated circuit
`devices. For instance, chemical dry 'etching gen~rally depends on gas-surface
`reactions involving these neutral species wi~out '.substantial ion bombardment.
`1
`In other manufacturing processes, ion bombardment to substrate
`surfaces is often.undesirable. This ion bombardment, however, is known to have
`harmful effects on properti~s of material layers in devices and excessive ion
`bombardment flux and energy can lead to intermixing of materials in adjacent
`device layers, breaking• down oxide and "wear out,. injecting of contaminative
`material fonned in the processing environment into substrate material layers,
`.
`harmful changes in substrate morphology (e.g. amophotization), etc.
`
`•
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`i6655-003000
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`Ion assisted etching processes, however, rely upon ion bombardment
`
`.
`
`to the substrate surface ·in defining selected films. But these ion assisted· etching
`
`processes commonly have jl lower selectivity relative to conventional CDE
`
`processes. Hence, CDE is often chosen when high selectivity is desired and ion
`
`5
`
`bombardment to substrates are to be avoided.
`
`One.commonly used chemical dry etching technique is conventional
`
`photoresist stripping, often termed ashing or stripping. Conventional resist
`
`stripping relies upon a reaction between a neutral gas phase species and a surface
`
`material layer, typi~lly for removal. This';reaction generally forms volatile
`
`products with the' surface material layer for' its removal. The neutral gas phase
`
`species is formed by a plasma discharge. 'Fhis plasma discharge can be sustained
`
`by a coil (e.g., helical coil, .etc.) operating at a selected frequency in a
`conventional phot0resist stripper. An example of th·e conventional photoresist
`
`stripper is a quarter-wave helical resonator ~tripper, which is described by U.S.
`Patent No. 4,368,~ in-~e name of 0Steinoei'g ~ fil.
`Referring to the above, an objective in chemical dry etching is to
`
`reduce or even eliminate ion bombardment (or ion flux) to surfaces being
`
`processed to maintain the desired etching se1ectivity. In practice, however, it is
`
`often difficult to achieve using conventional techniques. These conventional
`
`techniques gene~ly attempt to contr~I ion flux by suppressing the amount of
`
`charged species in the plasma source reaching the process chamber. A variety of
`techniques for suppressing these charged species have been proposed.
`,·
`These techniques often rely upon shields, baffles, large separation
`
`I
`
`distances between the plasma source and the· chamber, or the like, placed between
`the plasma source and the process chamber} The conventional techniques
`I
`• •
`generally attempt to directly suppress charg~ density downstream of the plasma
`
`source by interfering with convective and d1ffusive transport of charged species.
`
`They tend to promote recotnbination of charged species by either increasing the
`
`surface area (e.g.', baffles,!etc.) relative to ~olu~e. or increasing flow time, which
`relates to increasi~g the distance between the plakma source and the process
`I
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`These baffles, however, cau~ loss of desirable neutral etchant
`species as well. The baffles, shields, •and alike, also are often cumbersome.
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`Baffles,: shields, or the large separation dis~ces: also cause undesirable'
`recombinative loss of active species and sometimes cause radio frequency power
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`.loss and' other prdbleuis. These baffles andl shields also are a potential source of
`particulate contamination, which is often damaging to integrated circuits.
`Baffles, shields, spatial separation, and alike, when used alone also
`are often insufficient to subs~tially prevent, unwanted parasitic plasma currents.
`These plasma currents are generated between the wafer and the plasma source, or
`between the plasma source.jand walls of the chamber. It is commonly known that
`when initial charged species levels are present in an electrical field, the charged
`species are accelerated and dissociative colllsions with neutral particles can
`multiply the concentration ~f charge tb higlier levels. If sufficient "seed" levels of
`charge and rf pot~ntials are present: the parasitic plasma in the vicinity of the
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`process wafer can reach ha:nnful charge density levels. In some cases, these
`charge densities ~ ay be .siAillar to or even grea~r than plasma density within the
`source plasma region, thereby causing even more ion flux to the substrate.
`Charge densities also create :a voltage difference between the plasma
`source and processing chamber or substrate support, which can have an additional
`deleterious effect. This voltage difference enhances electric fields that can
`accelerate extraction of charge froni the plasma source. Hence, their presence
`often induces increased levels of charge to ~e irregularly transported from the
`plasma source to process substrates, thereb} causing non-uniform ion assisted
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`etching.
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`cohventional ion assisi1d pl~ma etching, however, often requires
`control and main<enance of ion flux intensity and uniformity within selected
`process limits and within ~lected process e~ergy ranges. Control and maintenance
`of ion flux intensity and uniformity are often· difficult to achieve using conventional
`techniques. For instance, capacitive coupling between high voltage selections
`of the coil and the plasrtla discharge often cause high and uncontrollable plasma
`potentia;s relative to ground. It is generalli understood that voltage difference
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`between the plasma ~d gri>und can cause damaging high energy ion bombardment
`of articles being processed 1by the plasma, as 'illustrated by U.S. Patent No.
`5,234,529 in the ~e of Johnson. It is further often understood that rf
`component of the 'plasma potential varies in time since it is derived from a
`coupling to time varying rf excitation. Hence, the energy of charged particles
`from' plasma in oonventional inductive sources is spread over a relatively wide
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`range of energies, which undesirably tends to introduce uncontrolled variations in
`the processing of articles by the plasma.
`Th~ voltage difference. between the region just outside of a plasma
`source and the processing chamber can be modified by introducing internal
`conductive shield~ or electrode elements into the iprocessing apparatus downstream
`of the 59urce. When the plasma potential is elevated with respect to these shield
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`electrodes, however, there ·is a tendency to generate an undesirable capacitive
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`discharge between the shield and plasma source. These electrode elements are
`often a source of contami~tion and the likelihood for contamination is even
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`greater when there is capacitive discharge (ion bombardment from capacitive
`discharge is a potential sou'rce of sputtered material). Contamination is damaging
`to the manufacture of integrated circuit devi&:s.
`Another limitation is that the'shield or electrode elements generally
`require small holes therein· as structural elements. These small holes are designed
`to allow gas to fl6w therethrough. The sm~I ho~es, however, tend to introduce
`unwanted pressurb drops and neutral species recombination. If the holes are made
`larger, the plasma from the source tends to survive transport through the holes and
`unwanted downstream charge flux will often:'result. In addition, undesirable
`discharges to these holes in shields can, at ti!Des, produce an even more
`undesirable hollow cathode effect.
`In conventional helical reso\iator designs, conductive external
`shields are interposed between the inductivd power (e.g., coil, etc.) and walls of
`the vacuum vessel containing the plasma. A 'variety limitations with these external
`capacitive shielde<i plasma <lesigns (e.g., heii~l resonator, inductive discharge,
`etc.) have been observed. ·1n particular, the i:apacitively shielded design often
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`produces plasmas that are difficult to tune l\1}d even ignite. Alternatively, the use
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`of unshielded plasma SQUrces (e.g., ·conventional quarter-wave resonator,
`conventional half-wave re~nator, etc.) atta(n:a substantial plasma potential from ·
`capacitive coupliri,& to the <:<>ii, and hence are, prone to' create uncontrolled parasitic
`plasma currents tb grounded surfaces.: Accordingly, the use of either the shielded
`or the unshielded :sources using conventional 'quarter and half-wave rf frequencies
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`produce undesirable results.
`In many conventional plasma sources a means of cooling i's required
`to maintain the plasma source and substrates being treated below a maximum
`temperature limit. Power dissipation in the ~tructure .causes heating and thereby
`increases the difficulty and expense of implementing effective cooling means.
`Inductive currents may also be coupled fro~ 1the excitation coil into internal or
`capacitive shields and these currents are an additio~ source of undesirable power
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`loss and heating. Conventional capacitive \hielding in helical resonator discharges
`utilized a Shield which was substantially split.along the long axis of the resonator
`to lessen eddy cutrent loss.: Howev~r. such a shield substantially perturbs the
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`resonator charactyristics owing to unwante<l capacitive coupling and current which
`flows from the cJil to the shield. Since there are no general design equations, nor
`are properties cutrently known for resonators which are "loaded" with a shield
`along the axis, sources using this design md~i be sized and made to work by trial
`and errdr.
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`In inductive :discharges, it is highly desirable to be able to
`substantially conttol the pl~ma potbntial re1~tive to ground potential, independent
`of input power, pressure, gas composition arid other variables. In many cases, it
`is desired to have the plasma potential be substarltially. at ground potential (at least
`offset from grou~d potential by an ainount insigtlificantly different from the
`floating potential ior intrinsic DC plasma·~~nti~). For example, when a plasma
`source is utilized '.to generite neutral species to be transported downstream of the
`source for use in 1ashing resist on a semiconductor device substrate (a wafer or flat
`panel electronic ~isplay), the concentration .and potential of charged plasma species
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`in the reaction zone are desirably reduced to avoid charging damage from electron
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`or ioni.c current from the plasma to .the dev\ce. Wheni there is a substantial
`potentiaf differen<!e between plasma in the sour~ and grounded surface~ beyond
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`the source, there is a tendency for unwanted parasitic plasma discharges to form
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`outside of the source region.
`Another undesirable effect of potential difference is the acceleration
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`of ions toward grounded surfaces and subsequent impact of the energetic ions with
`surfaces. High energy ion bombardment may cause lattice 'damage to the device
`substrate being processed and may cause th~ chamber wall or other chamber
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`materials to sputter and contaminate devi~ wafers. ~n other plasma processing
`procedures, however, some ion bombardme.nt may be necessary or desirable, ~sis
`the case particularly for anisotropic ion-induced plasma etching procedures (for a
`discussion of ion-~nhanced plasma etching mechlioisms ~ Flamm (Ch. 2,pp.94-
`183 in Plasma Eti:hing, An Introduction, D! M. Manos and D.L. Flamm, eds.,
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`Academ1c Press, 1989)). Consequently, uncontrolled potential differences, suc;h as
`that caused by "stray" capacitive coupling frbm the coil of an inductive plasma
`source to the plasma, are undesirable.
`Referring to the above limitations, conventional plasma sources also
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`have disadvantages when used in conventional plasma enhanced CVD techniques.
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`These techniques commonly form a reaction of a gas composition in a plasma
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`discharge. One conventional plasma· enhanced technique relies upon ions aiding in
`rearranging and stabilizing' the film, provided the bombardment from the plasma is
`not sufficiently et\ergetic to damage the underlying substrate or the growing film.
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`Conventional resdnators ~d other types of indud,tive discharges often produce
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`parasitic plasma ~urrents from capacitive coupli~g, which of~en detrimentally
`influences film quality, e.g., an inferior film, etc. These parasitic plasma currents
`are often uncontrollable, and highly undesirable. These plasma sources also have
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`disadvai!tages in other plasma processing tec'hniques such as ion-assisted etching,
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`and others. Of course, the particular disadtantage will often depend upon the
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`To clarify certain concepts uscl! iii this application, it will be
`convenient to introduce th~se definiti4ns.
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`Ground (or ground potential); 'These terms are defined as a
`reference potential which is g~nerally taken as the potential of a
`highly conductive shield or other highly conductive surface which
`surrounds tlie plasma source.' · To be a true ,ground shield in the
`sense of.this definition, the ~ conductance at the operating
`frequency is often substantially high so that potential differences
`generated by current' within $e shield are of negligible magnitude
`compared to potentials 1ntenti.onally applied to the various structures
`and ·elements of the plasma source or substrate support assembly.
`Ho~ever, some realizations of plasma sources do not incorporate a
`shield or surface with adequate electrical susceptance to meet this
`definipon. In implementations where there is a surrounding
`conductive surface that is somewhat similar to a ground shield or
`ground plane, the ground potential is taken to be the fictitious
`potential which the imperfect grounded surface would have
`equilibrated to if it had rero high frequency impedance. In designs
`where there is no physical surface which is adequately configured or
`which does not have.insufficient susceptance to act as a "ground"
`according to the above -definition, ground potential is the potential of
`a fictitious surface which is equi-potential with th~ shield or
`"ground" conductor of an unbalanced transmission line connection to
`the plasma source at its RF fbed point. In designs where the plasma
`source is connected to .an RFj generator with a balanced transmission
`line RF feed, "ground"1 poteqti~l is the average of the driven feed
`line potentials at the point w~ere the feed lines are coupled to the
`pla~ma source.
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`Inductively Coupled Power: ,This term is defined as power
`transferred ~o the plasma substantially by means of a time-varying
`magnetic flux which is induced within the volume containing the
`plasma source. A time-varying magnetic flux induces an
`electromotive force in accord' with Maxwell's equations. This
`electromotive force induces motion by electrons and other charged
`particles in the plasma and thereby imparts energy to these particles.
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`RF inductive power *'urce and bias power supply: In most
`conventional inductiv~·plasma ~urce reacto,rs, power is supplied to
`an inductive coupling element· (th~ inductive coupling element is
`often a multi-tum coil which :abu~ a dielectric wall containing a gas
`wh~re the plasma is ig~ited aF low: pressure) by an rf power
`ge[)erator.
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`Conventional Helical' Resonator: Conventional helical resonator can
`be 'defined as plasma 'applicators. ·These plasma applicators have
`been desig~ and operated in mu~tiple configuration.s, which were
`despribed in1 for example, U.S. Patent No. 4,918,031 in the names
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`of flamm ~ill.,, U.S. Patent: No. 4,368~092 in the name of
`Steinberg ~:fil., U.S. Patent No. 5,304,282 in the name of Flamm,
`U.~. Patent No. 5,234,529 ii] the name of Johnson, U.S. Patent No.
`5,4,31,968 in the name of Miller, and others. In these
`corlfiguratiOJ?.S, orie end of the helib.I resonator applicator coil has
`~n grounqed to its outer shield. i In one conventional
`configuration, a quarter wavelength helical resonator section is
`employed with one end of the,~plicator coil grounded and the other
`end floating (i.e., open circuited). A trimmi11g capacitance is
`sometimes connected between the grounded outer shield and the coil
`to "fiqe tune" the quarter wave structure to a desired resonant
`frequency that is below the native resonant frequency without added
`capacitru}Ce., In another.,conv.e11tional configuration, a half(cid:173)
`wavelength helical resonator section was employed in which both
`ends of the coil were' ground~. The function of grounding the one
`or both ends' of the coil was· believed to be not essential, but
`ad'!antageous 'to "stabilize the 'plasjlia operating characteristics" and
`"repuce the possibility, pf coupling stray current ~ nearby objects."
`~ U.S. Patent No. '4,918,031.
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`Cojwentional resonators have: also;been constructed in other
`geometrical 'configurations. For i1,1stance, the design of helical
`resonators with a shield of sqlljll"e 'cross section is described in
`Zverev ~ ru.1, IRE TransactiQns OJ) Component Parts, pp. 99-110,
`Sept. 1961. Johnson (U.S. Patent No. 5,234,529) teaches that one
`end of the cylindrical spiral coil in a conventional helical resonator
`may be deformed into a plal]M spiral above the top surface of the
`plasma reactor tube. U.S. P~tent No. 5,241,245 in the names of
`Barnes ~ ru,. teach th~ use of: conventional helical resonators in
`which the spiral cylil1(i,;ical. Cf)iJ is,entirely deformed into a planar
`spiral arrangement with no helical ' coil component along the
`sidewalls of the plasma sourch : (this geometry has often been
`referred to as a "transformer coupled plasma," termed a TCP).
`From the abbve it is seen that' :m improved technique, including a
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`method and apparatus, for plasma p'rocessin'.g is 9ften desired.
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`SUMMARY OF THE INVENTION
`The present invention provides. a technique, including a method and
`apparatus, for fabricating a product using a.plas'!13- discharge. The present
`technique relies upon the control of the insqmtaneous plasma AC potential to
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`selectively control a variety of. plasma ch~~ristics. These characteristics
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`include the amount of neutral species, the amount of charged species, overall
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`plasma potential, the spatial extent and distribution of plasma density, the
`distribution of electricai cu~rent, and others.:; This technique can be used in
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`applications including c