||||||||||||||||||||||||||||||||lllll||||||||||||||||||||||||||||||||||||||
`
`USOO7147759BE
`
`(12) United States Patent
`Chistyakov
`
`(10) Patent N0.:
`(45} Date of Patent:
`
`US 7,147,759 32
`*Dec. 12. 2006
`
`(54}
`
`I-lIGH-POVVER PULSE!) MAGNETRON
`SPUTTERING
`
`[75)
`
`Inventor: Roman (Ihistyakm'. .Midover. MA
`(US)
`
`(73) Assignce: Zond, lnc.. Mansfield. MA (US)
`
`6.393.929 Bl “
`6.413.332 Bl
`5.436.251 131
`
`6.21102 Chiang et' at.
`752002 Wing. el .11.
`8:"2002 Gopalraja c1' :1].
`
`......... 2045298211
`204193.11
`204898.12
`
`3‘35”: 59“?“ *1 at.
`65140-38” BI
`9-2002 “llllald
`6.456.642 Bl
`312002 Kawnmiilii ct nl.
`20020033430 Al
`11-2005 Cliislyakov ............ Ell-'1: [92.12
`2(105311252't'63 Al °
`FOREIGN l‘A'I‘EN'I‘ DOCUMENTS
`
`( i‘
`
`) Notice:
`
`Subject to any disclaimer. the term ol'tltis
`patent is extended or adjusted under 35
`LI...S(w 154(1)] by 0 days.
`
`_
`D11
`
`This patent is subject to a terminal dis-
`clztimer.
`
`.
`,
`’3
`(“H AWL N0" "”116ng
`(22)
`Filed:
`Sep. 30! 2002
`
`(65)
`
`Prior Publication Data
`
`91933
`3210351 A]
`[(lel‘iljllliCd}
`
`OTHER PUBLICJU'IONS
`
`[he 'l't':m5ition From Symmetric 'I'o Asymmetric
`Booth. at 31..
`Discharges In Pulsed 13.56 M112 Capacity Coupled Plasmas.
`.l.
`Appl. Phys... Jul. 15.
`I992. pp. 552-560. vol. 32 at. American
`Institute of Physics.
`
`[Continued]
`
`Primaijr Examiner Rodney G. McDonald
`(74)
`slimmer.
`.slgent. or Firm-"Kurt Ranscitenbach:
`.
`.
`t
`_‘
`)
`r
`'
`"
`RdLISLhLHbBCll latent Law Group. l.l_.C.
`[57)
`ABSTRACT
`
`Magnetically enhanced Sputtering methods and apparatus
`are described. A magnetically enhanced sputtering source
`according. to the present invention includes an anode and 3
`cathode assembly having a target that is positioned adjacent
`to the anode. An ionization source generates a weakly-
`ionized plasma proximate to the anode and the cathode
`tisseutbl
`. A ma met is osilioned to
`cnernle a ma tetic
`field profitirnale ti: the Writkly-ionired plgosruo. The magnetic
`field substantially traps electrons in the weakly-ionized
`plasma proximate to the sputtering target. A power supply
`produces an electric field in o gap between the anode and the
`cathode assembly. The electric field generates excited atoms
`in a...
`...-......- ...... rim a... .....m... secondary
`electrons from the sputtering target. The secondary electrons
`ionize the eitctled atoms. thereby crttilttttga strongly-longed
`plasma ltzwing iOl‘lS that impact a surlacc ol the sputtering
`target to generate sputtering flux.
`
`A?“ 1~ 2004
`
`US 200450060813 A]
`Int. Cl.
`(2006.011
`C33C' 14/35
`204!l92.12;204llg2.l3;
`[1.5. CI.
`2041291403; 204f298.06: 2041291538; 2041129814:
`204139319
`204f192.12.
`(581 Ficld of Classification Search
`204119213. 298.03. 298.06. 293.08. 298.14.
`204138.19. 298.26
`Sce application tile for complete search history.
`..
`References (“Ed
`[1.5. [DNI'IEN'J' DOCUMENTS
`
`[51)
`
`[52}
`
`[56)
`
`3.515.920 A
`4.953J7-1 A
`iii??? :2
`5.1515'324 A
`$875.21)? A
`5342.039 A
`5.083.36l A
`6.296.742 131
`
`6.519711 Muly. Jr. ct al.
`8-1990 Eldridge el :11.
`372-37
`1212133? 3‘15:‘i‘..‘.‘.‘:..1111:111111111"43351.1;
`4.199? Billing
`3.1999 Oamariow
`331999 5pm” ct' at.
`TIEUUU Kobttyashi cl M
`[[13200] Kouznetsov
`
`204.192.”
`
`3725861
`
`6.342.132 Bl
`
`132002 Rossnagel
`
`50 Claims. 18 Drawing Sheets
`
`
`
`TSMC-1301
`
`TSMC v. Zond, Inc.
`
`Page 1 of 32
`
`TSMC-1301
`TSMC v. Zond, Inc.
`Page 1 of 32
`
`

`

`US 7,147,759 32
`Page 2
`
`FOREIGN PKIENT DOCUMENTS
`
`l:'P
`GB
`.IT’
`1?
`WO
`W0
`WC)
`
`{l 733 139 Al
`13399l0
`STI94254
`10204633
`“(09504368
`W0 9340532
`WO 01398553 Al
`
`”‘
`
`3.31997
`[2"1973
`11:198.?
`3.31998
`2-1995
`9. 1998
`12'2001
`
`OTHER PUBLIC ATIONS
`
`Bunshah. et al.. Deposition 'l'echnologies For Films And Coatings.
`Materials Science Series. pp.
`[76-183. Noyes Publications. Park
`Ridge. New Jersey.
`Daugherty. et at. Attachment—Dominated Flectwn-Beam-Ionizeit
`Discharges. Applied Science Letters. May 15. 1976. vol. 2S. No. it).
`.Mnericnn Institute of Physics.
`Goto. et a1.. [)qu Excitation Reactive Ion Etc-her for low Energy
`Plasma Processing. J. Vac. Sci. Technol. A. Sep..0ct. 1992. pp.
`3048-3054, vol.
`lift, No. 5. American Vacuum Society.
`lionzneisov. et al.. A Novel Pulsed Magnetron Spotter Technique
`Utilizing Very High Target Power Densities. Surface 8: Coatings
`Tecimology. pp. 290-293. Elsevier Sciences SA.
`Lindquist. et 31.. High Selectivity Plasma Etching Of Silicon Diox-
`ide With A Dual Frequency 27”! MHZ Capacitive 11F Discharge.
`Macak. Reactive Splitter Deposition Process of A1203 and C harae-
`terization 01' A Novel High Plasma Density Pulsed Magnetron
`Discharge. Linkoping Studies in Science And Technology. 1999. pp.
`[—2. Sweden.
`Macak. et al.. Ionized Splitter Deposition Using M Extremely High
`Plasma IJensil'y Pulsed MagneLrun Discharge. J. Vac. Sci. Technol.
`A..
`lulu-sling.
`.1000. pp. [533-531 vol.
`[8. No. 4. American
`Vacuum Sociew.
`
`Mozgrin. et a1., High-Current [ow-Pressure Quasi Stationary Dis-
`charge In A Magnelic Field: [mtimcntal Research. Plasma Phys-
`ics Reports. [995. pp. 400-409. vol. 2|. No. 5. Mozgrin. Fcitsoy'.
`Khodachenko.
`
`induced Drift Currents In Circular Planar
`Rossnagei. et al..
`Magnetrons. J. Vac. Sci. Technol. A.. .Ian..'I"eb. 1911?. pp. 38-9 I. vol.
`5. No. l, American Vacuum Society.
`Sheridan. el
`.11.. Electron Velocity Distribution Functions In A
`Sputtering Magnetron Discharge For The EXP; Direction. J. Vac.
`Sci. Technol. A.. Jul..-'A1Ig.
`[933. pp. Elli-211%. vol.
`l6. No. 4.
`American Vacuum Society.
`Sleil1}_'trucltci1 A Simple Formula For Law—Energy Sputtering Yields,
`Applied Physics .-\.. [985. pp. 37-42. vol. 36. Springer-Verlag.
`I'urcnko. et 31.. Magnetron Discharge In The Vapor Of'lhe Cathode
`Material. Soviet Technical Physics Letters. Jul. [989. pp. 519-520;
`vol. 15. No. 7. New York. US.
`
`Encyclopedia Of Low Temperature Plasma. p. 119. vol. 3.
`Encyclopedia Of Low 'l'empernture Plasma. p. 123. vol. 3.
`Sugimoto. el al; Magnetic Condensation Oi'A Photoexcited Plasma
`During Fluoropoiymer Sputtering; J. Appl. Phys; Feb. 15. 1991}; pp.
`2093-2099; vol. 6?. No. 4; American Institute of Physics; New
`York. US.
`
`Yamaya. et a1: Use Of A I'Iclicon-ane Excited Plasma For Alt!»
`minum~Dopcd 3111'1 Thin-Film Sputtering; Appl. Phys. Lem Jan.
`12. 1998; pp. 235-‘23T; vol. T3310. 2; American Institute 01" Physics:
`New York US.
`
`* cited by examiner
`
`TSMC-1301 I Page 2 of 32
`
`TSMC-1301 / Page 2 of 32
`
`

`

`US. Patent
`
`Dec.12,2006
`
`Sheet 1 of 18
`
`US 7,147,759 32
`
`102
`100
`
`PULSED
`POWER
`SUPPLY
`
`
`132
`
`
`
`Ik—
`‘W i V\\\\\\\\'\V§a£\\\\ \‘\\ it““\\\‘.\".II." L 'V
`
`
`amazmwnas:trlym
`
`\\\\\\\\‘\\\YL\\\\\.\\\“\\‘\\\fi\\\‘\‘1
`§‘\\\\\\\\\\\\\\\‘1n‘\\\\\\\“\\\\\\\“
`\a/
`
`PRIOR ART
`
`FIG. 1
`
`TSMC-1301 / Page 3 of 32
`
`TSMC-1301 / Page 3 of 32
`
`

`

`US. Patent
`
`Dec.12,2006
`
`Sheet 2 of 18
`
`US 7,147,759 32
`
`V;§
`
`x
`L4.
`m
`m
`MVEZW/IM
`//V;
`\‘f
`‘—
`2;
`'-
`A
`JEEWHII”
`fl
`m E m
`213 l‘
`
`\\‘3““\‘.‘t‘.‘“‘k\““I.‘““‘3‘.
`m
`mmnyllmllawr\\\\\
`54 233 mxm
`III/IIIlf\f/\”/\flfl/iflIII/fl/fl/M'fllfl’flll‘tlffi
`am
`
`[/2
`
`WW
`
`ZEE‘EN.
`
`'E
`
`\\‘
`
`M2;
`W
`
`n
`
`\
`
`MCW
`
`'l
`
`/m
`%W
`(ff/1W
`
`V1
`
`6g
`
`:
`,4
`,5
`,4
`
`g6
`
`1/1"
`
`.
`
`2“ \\\\\\\\\\\\\\\“ 248
`§
`
`TSMC-1301 / Page 4 of 32
`
`TSMC-1301 / Page 4 of 32
`
`

`

`US. Patent
`
`Dec. 12. 2006
`
`Sheet 3 of 18
`
`US 7,147,759 B2
`
`”WWWW/
`7
`
`W\\\\\\\\\\\\\\\
`
`
`/////M//lur/IJ
`—r——>5mE/
`.l.E SN8m
`
`
`\\\\\v.fiwfi\\.....\\\\
`pwnnmml“my“
`...............7/44:74....Aflflfi/4.7/7
`
`£41.“...-................m.4.‘6”
`\\\_._..I.§\\§\5J.\\\\
`E>5.
`
`Hwnnwvm»
`
`IIIIIIIII
`
`I/Il/IM/
`////////
`
`mwN
`
`TSMC-1301 / Page 5 of 32
`
`TSMC-1301 / Page 5 of 32
`
`

`

`U.S. Patent
`
`Dec. 12., 2006
`
`Sheet 4 0f 18
`
`US 7.147.,759 BZ
`
`lllllllllllllllllll
`
`m2...
`
`_—_1------u-
`
`h.—
`
`mM
`
`Smmom_u
`
`3m
`
`8»
`
`h$38
`
`
`
`
`
`lllllllllllllllllllllllllllll.:-Io-n.on....u-IsII-lutlr‘lnanuunlutut!.niI£50?Igxrll
`
`
`
`+............+.....m..................-232-So:M«on
`
`
`
`
`
`ym.Ja“Nu:o.
`
`TSMC-1301 / Page 6 of 32
`
`TSMC-1301 / Page 6 of 32
`
`

`

`US. Patent
`
`Dec. 12, 2006
`
`Sheet 5 0f 18
`
`US 7,147,759 B2
`
`~200V-30kV
`
`"1 00V—5kV
`
`~10A*5000A
`
`-0.1A-100A
`
`~1kW-1OMW
`
`
`lllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllll
`lllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllll
`IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII
`llllllllllllllllllllllllllllllll
`
`324
`l
`
`lllllllllllllllllllllll
`
`~0.01kW-1GOKW
`
`‘1
`
`Eta t4
`
`t5
`
`FIG. 5
`
`TSMC-1301 / Page 7 of 32
`
`TSMC-1301 / Page 7 of 32
`
`
`

`

`U.S. Patent
`
`Dec. 1
`
`US 7,147,759 BZ
`
`I-INEE_=NN\EJI§Km2m)rrywjmfijafiw
`
`,0‘J5_Hd
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`rfl
`
`
`v
`
`g1‘35
`
`4CMST
`
`TSMC-1301 / Page 8 of 32
`
`
`
`
`
`
`

`

`U.S. Patent
`
`Dec. 12 2006
`
`Sheet 7 0f18
`
`
`I‘d-x.“4‘:/,.S\\\}fl/J=HP,.f.
`ii:IIII'r/l/fiigh‘}
`‘IfiIfl/fi“
`Jilllilfi'rflf.’
`
`TSMC-1301 / Page 9 of 32
`
`

`

`U.S. Patent
`
`Dec. 12, 2006
`
`Sheet 8 0f 18
`
`US 7,147,759 BZ
`
`
`
`
`
`
`
`
`
`
`
`
`2N1V=E§EJ§
`
`
`
`3"figgvuuwr-EE/Hikg
`'1‘}Jfi=fi"fldm
`)3,.V).Iafi))é
`
`J\JJJJA/4JJ.
`
`~i‘lIIl"!§
`
`
`
`TSMC-1301 / Page 10 of 32
`
`TSMC-1301 / Page 10 of 32
`
`
`
`
`
`

`

`m'Lfi‘ggqidg
`2NIlla!2L
`Fraggfz/gégé”é
`Ii‘Qiq,
`aifigfiyge
`
`1“!"i‘drr
`
`
`
`
`
`
`
`
`
`ill!
`
`
`
`D
`
`TSMC-1301 / Page 11 of 32
`
`
`
`

`

`US. Patent
`
`Dec. 12, 2006
`
`Sheet 10 01'18
`
`US 7,147,759 B2
`
`450
`\
`
`460
`
`MATCHING
`UNIT
`
`F13
`
`EVA
`155.: sWA§?
`HW§V
`
`fl
`
`a
`
`”Ir/43%;1"
`mffkvlgig
`
`6
`
`a“
`
`1mm
`
`,flflr/1/§x§
`
`
`\xxxxKN
`
`ghw‘kg
`
`
`
`§x§§\\\‘&\\\\
`
`.T
`254 233
`246
`”II/”ff/WJI/IlIll/l/flfffllllf/MM/Ilflfl‘fl
`
`§x§
`§\\Mfi
`“\u‘
`\m\\\L@—\\\\ms5
`“M.“I:
`NS
`E 220
`S
`N
`
`
`‘I k\“““}““\i\\\l‘u “m
`.'L
`“v
`‘32
`-.
`\31:=:l.-_1:
`‘zm-J; - - —
`\.
`Hi;
`
`\HJ“\HI
`.
`____‘""-_-.---------4
`____'M_I,’-__-_
`452
`
`"PM.
`
`(flglp’f’{Vianf’lfllf/lfff/idt
`
`and{/4
`
`\ugfimfimcfi
`
`
` \\\:\N\§Q§fiSxKNK.‘
`
`W§
`
`mm
`
`FIG. 7
`
`TSMC-1301 / Page 12 of 32
`
`TSMC-1301 / Page 12 of 32
`
`
`
`
`
`
`

`

`US. Patent
`
`Dec. 12., 2006
`
`Sheet 11 of 18
`
`US 7,147,759 BZ
`
`m.OE
`
`use...
`
`3w.J
`
`TSMC-1301 / Page 13 of 32
`
`mam
`
`lllllllllllllllllllllllllllll
`
`...........................-EES.ET
`
`05
`
`man
`
`con
`
`mmgou
`
`Nam
`
`2650..-Edi
`
`TSMC-1301 / Page 13 of 32
`
`

`

`US. Patent
`
`Dec.12,2006
`
`Sheetl2 of18
`
`US 7,147,759 B2
`
`arm.mrm
`
`mmw\.9%:8“ERNEn
`@Ia?v
`
`
`
`
`
`§
`
`\wmm
`
`§§m2
`
`
`
`«5.0E
`
`TSMC-1301 I Page 14 of 32
`
`TSMC-1301 / Page 14 of 32
`
`
`
`
`

`

`US. Patent
`
`Dec. 12. 2006
`
`Sheet 13 0f18
`
`US 7.147359 B2
`
`KAI.
`
`
`
`7d.”.Icr/
`
`upIIIJIPLHIIIhflfl’IIIIJn’III/IIIt
`\-=E
`Wfix‘xg
`
`mm
`
`J§.\
`
`fi\\k\§§N\\
`x§§§\\\\%\\x§
`
`x\\\\\\\\\\\.k
`
`\“‘\\\\“‘\\\‘
`
`“\‘\“\“
`
`\§Wr
`
`/f/J/IJV/If/fi'flfllfl/Iflflfl/f/le/f/flllllift
`
`§§
`[155‘
`
`Wl/
`
`war/IA§\\\\\/
`
`flrlr/—W
`
`WAN/g},
`filial/7.x?
`
`FIG. 10
`
`TSMC-1301 / Page 15 of 32
`
`TSMC-1301 / Page 15 of 32
`
`
`
`
`
`
`
`
`
`
`

`

`US. Patent
`
`Dec.12,2006
`
`Sheet 14 ONE
`
`US 7,147,759 32
`
`M\\\\‘\\\\\\\\
`
`W
`v"?
`fi
`fi
`
`/E
`
`w.
`l6f
`¢f
`
`?/W
`
`. “fiiiiiiiliiifififiim ,.
`
`C:I‘-,7
`
`/.Wm
`
`W
`
`m#I/I/I/I/fl/IIWMIJ’I/IllllW/fM/Illlf/Wlfl
`
`TSMC-1301 / Page 16 of 32
`
`TSMC-1301 / Page 16 of 32
`
`

`

`U.S. Patent
`
`Dec..12.,2006
`
`Sheet 15 of 18
`
`US 7,147,759 32
`
`500
`\.
`
`802
`
`
`
`604
`
`
`
`
`
`PRESSURE
`CORRECT?
`
`Y
`
`608
`
`PASS FEED GAS INTO CHAMBER
`
`PROXIMATE TO A CATHODE (TARGET ASSEMBLY
`
`
`GAS
`
`
`CHAMBE R
`PRESSURE
`PRESSURE
`
`
`
`CORRECT?
`CORRECT?
`
`
`
`
`FIG. 12A
`
`FIG. 128
`
`FIG. 12
`
`FIG. 12A
`
`TSMC-1301 / Page 17 of 32
`
`TSMC-1301 / Page 17 of 32
`
`

`

`US. Patent
`
`Dec..12.,2006
`
`Sheet 16 of 18
`
`US 7,147,759 32
`
`GENERATE STRONGLY-IONIZED SUBSTANTIALLY
`
`UNIFORM PLASMA FROM WEAKLY-IONIZED PLASMA
`
`
`
`
`
`
`
`MONITOR SPU'ITER DEPOSITION
`
`DEPOSITION
`
`COMPLETE
`?
`
`FIG. 128
`
`TSMC-1301 / Page 18 of 32
`
`TSMC-1301 / Page 18 of 32
`
`

`

`US. Patent
`
`Dec.12,2006
`
`Sheet 17 of 18
`
`us 7,147,759 132
`
`PUMP DOWN CHAMBER
`
`604
`
`
`
`PRESSURE
`CORRECT?
`
`650
`
`swim“
`
`
`
`
`
`
`
`
`
`GAS
`
`CHAMBER
`PRESSURE
`PRESSURE
`
`
`
`CORRECT?
`
` 614
`
`Y
`
`608
`
`PASS FEED GAS INTO CHAMBER
`
`PROXIMATE TO A CATHODE (TARGET ASSEMBLY
`
`
`
`FIG. 13A
`
`FIG. 133
`
`FIG. 13
`
`TSMC-1301 / Page 19 of 32
`
`TSMC-1301 / Page 19 of 32
`
`

`

`US. Patent
`
`Dec..12.,2006
`
`Sheet 13 of 18
`
`US 7.1475759 32
`
`GENERATE STRONGLY—IONIZED SUBSTANTlALLY
`
`
`
`
`GAS
`STRONGLY-
`ONIZED"
`
`
`
`
`UNIFORM PLASMA FROM WEAKLY—IDNIZED PLASMA
`
` MONITOR SPUTTER RATE
`
` INCREASE HIGH-POWER
`
` FIG. 138
`
`
`PULSE TO CATHODE
`(TARGET) ASSEMBLY
`
`TO INCREASE
`SPUT‘I’ER RATE
`
`SPUTTER
`RATE
`SUFFJCENT
`
`
`SPUTTER
`DEPOSITiON
`
`
`TSMC-1301 / Page 20 of 32
`
`TSMC-1301 / Page 20 of 32
`
`

`

`US ?,147,759 B2
`
`1
`HIGH-POWER PULSED MAGNETRON
`SPLITTER] NG
`
`BACKGROUND OF INVENTION
`
`Sputtering is a well-loiown technique for depositing films
`on substrates. Sputtering is the physical ejection of atoms
`from a target surface and is sometimes referred to as
`physical vapor deposition (PHD). Ions. sttch as argon ions.
`are generated and then directed to a target surface where the
`ions physically sputter target material atoms. The target
`material atoms ballistically flow to a substrate where they
`deposil as a liltn of target material.
`Diode sputtering systems include a target and an anode.
`Sputtering is achieved in a diode sputtering system by
`establishing an electrical discharge in a gas bent-ecu two
`paradlel-plal'e electrodes inside a chamber. A potential of
`several kilovolts is typically applied between planar elec-
`trodes in an inert gas atmosphere (cg... argon] at pressures
`that are between about 10" and 10‘: Torr. A plasma dis-
`charge is then formed. The plasma discharge is separated
`from each electrode by what is referred to as the dark space.
`The plasma discharge has a relatively constant positive
`potential with respect to the target. Ions are drawn out of the
`plasma. and are accelerated across the cathode dark space.
`The target has a lower potential than the region in which the
`plasma is formed. Therefore, the target attracts positive ions.
`Positive ions move towards the target with a hi git velocity.
`Positive ions impact the target and cause atoms to physically
`dislodge or sputter from the target. The sputtered atoms then
`propagate to a substrate where tltey deposit a film of
`sputtered target material. The plasma is replenished by
`electron-ion pairs fanned by the collision of neutral mol-
`ecules with secondary electrons generated at
`the target
`surface.
`
`Magnetron sputtering systems use magnetic fields that are
`shaped to trap and to concentrate secondary electrons. which
`are produced by ion bombardment ol'the target surface. The
`plasma discharge generated by a magnetron sputtering sys-
`tem is located proximate to the surface of the target and has
`a high density of electrons. The high density of electrons
`causes ionization of the sputtering. gas in a region that is
`close to the target surface.
`One type of magnetron sputtering system is a planar
`magnetron sputtering system. Planar magnetron sputtering
`systems are similar in configuration to diode sputtering
`systems. However. the magnets (upenuanent or electromag-
`nets) in planar magnetron sputtering systems are placed
`behind the cathode. The magnetic field lines generated by
`the magnets enter and leave the target cathode substantially
`normal to the cathode surface. Electrons are trapped in the
`electric and magnetic fields. The trapped electrons enhance
`the efficiency of the discharge and reduce the energy dissi-
`pated by electrons arriving at the substrate.
`Conventional magnetron sputtering systems deposit [iirns
`that have relatively low uniformity. However.
`the film
`uniformity can be increased by mechanically moving the
`substrate andfor the magnetron. but such systems are rela—
`ti vely complex and expensive to implement. Conventional
`magnetron sputtering systems also have relatively poor
`target utilization. By poor target utilization. we mean that the
`target material erodes in a non-unifiirtn manner.
`
`BRIEF DESCRIPTION OF DRAWINGS
`
`This invention is described with particularity in the
`detailed description. 'I‘he above and further advantages of
`
`2
`
`Jr
`
`Ill
`
`this invention may be better understood by referring to the
`following description in conjunction with the accompanying
`drawings.
`in which like numerals indicate like structural
`elements and features in various figures. The drawings are
`not necessarily to scale. emphasis instead being placed upon
`illustrating the principles of the hivention.
`FIG.
`1
`illustrates a cross—sectional view of a known
`
`magnetron sputtering apparatus having a pulsed power
`source.
`
`FIG. 2 illustrates a croSs-sectional view ot'an embodiment
`of a magnetron sputtering apparatus according to the present
`invention.
`FIG. 3 illustrates a emits-sectional view of the anode and
`
`15
`
`the cathode assembly of the magnetron sputtering apparatus
`of FIG. 2.
`
`FIG. 4 illustrates a graphical representation of the applied
`power of a pulse as a function of time For periodic pulses
`applied to the plasma in the magnetron sputtering system of
`FIG. 2.
`
`FIG. 5 illustrates graphical representations ol‘ the absolute
`value of applied voltage. current. and power as a function of
`time for periodic pulses applied to the plasma in the mag-
`netron sputtering system of FIG. 2.
`FIG. 6A through FIG. 6D illustrate various simulated
`magnetic field distributions proximate to the cathode assem~
`bly for various electron ExB drift currents according to the
`present invention.
`FIG.
`3'
`illustrates a cross-sectional view of another
`embodiment ol'a magnetron sputtering apparatus according
`to the present invention.
`FIG. 8 illustrates a graphical representation of pulse
`power as a function of time for periodic pulses applied to the
`plasma in the magnetron sputtering system of FIG. 7.
`FIG. 9A through FIG. 9C are cross-sectional views of
`various embodiments of cathode assemblies according to the
`present invention.
`FIG. 10 illustrates a cross-sectional view of another
`
`3ft
`
`4!]
`
`43
`
`illustrative embodiment ofa magnetron sputtering apparatus
`according to the present invention.
`FIG. 11 is a crosseectiona] view of another illustrative
`embodiment of a magnetron sputtering apparatus according
`to the present invention.
`FIG. 12 is a flowchart ofun illustrative process ofsputter
`deposition according to the present invention.
`FIG. 13 includes FIG 3.13 A and 13 B which is a tlowchart
`
`of an illustrative process of controlling sputtering rate
`according to the present invention.
`
`DETAIL ED DESCRIPTION
`
`"lhc magnetic and electric fields in magnetron sputtering
`systems are concentrated in narrow regions close to the
`surlace of the target. These narrow regions are located
`between the poles of the magnets used for producing the
`magnetic field. Most of the ionization of the sputtering gas
`occurs in these localized regions. The location of the ion—
`ization regions causes a non-uniform erosion or wear of the
`target that results in poor target utiliration.
`Increasing the power applied between the target zmd the
`anode can increase the amount of ionized gas and. therefore.
`increase the target utilization. I-[owever. undesirable target
`heating and target damage can occur. Furthermore. increas-
`ing the voltage applied between the target and the anode
`increases the probability of establishing an undesirable
`electrical discharge Ian electrical arc} in the process cham-
`ber.
`
`..'
`
`Etll
`
`’
`
`TSMC-1301 I Page 21 of 32
`
`TSMC-1301 / Page 21 of 32
`
`

`

`3
`
`4
`
`US 2,147,759 B2
`
`the ions sputter the target material 116. A portion of the
`spunened target material 116 is deposited on the substrate
`134.
`
`The electrons. which cause the ionization. are generally
`confined by the magnetic fields produced by the magnet 126.
`The [magnetic confinement is strongest in a confinement
`region 142 where there is relatively low magnetic field
`intensity. The conlineluent region 142 is substantially in the
`shape of a ring that
`is located proximate to the target
`material. Generally. a higher concentration of positively
`charged ions in the plasma is present in the confinement
`region 142 than else-Where in the chamber 104. Conse-
`quently. the target material 116 is eroded rapidly in areas
`directly adjacent to the higher concentration of positively
`charged ions. The rapid erosion in these areas results in
`undesirable non-uniform erosion of the target material 1.16
`and. thus relatively poor inr'get utilization.
`Dramatically increasing the power applied to the plasma
`can result in tnore uniform erosion o l‘ the target male-rial 116.
`However. the :unottltt ol'applicd power necessary to achieve
`this increased uniformity can increase the probability of
`generating an electrical breakdown condition that leads to an
`undesirable electri ‘al discharge between the cathode assent-
`bl},r 114 and the anode 130 regardless of the duration of the
`pulses. An tmdesirable electrical discharge will corrupt the
`sputtering process and cause contamination in the vacuum
`chamber 104. Additionally. the increased power can over-
`heat the target and cause target damage.
`F It]. 2 illustrates a cross~sectional view ofan embodiment
`
`In
`
`15
`
`Eli
`
`3t]
`
`l’nlsing the power applied to the plasma can be advanta-
`geous since the average discharge power can remain low
`while relatively large power pulses ctut be periodically
`applied. Additionally. the duration of these large voltage
`pulses can he preset so as to reduce the probability of i
`establishing an electrical breakdown condition leading to an
`undesirable electrical discharge. However. very large power
`pulses can still result in undesirable electrical discharges and
`undesirable target heating regardless of their duration.
`FIG.
`1
`illustrates a cross-sectional view of a known
`magnetron sputtering apparatus 100 having a pulsed power
`source 102. The known magnetron sputtering apparatus 100
`includes a vacuum chamber 104 where the sputtering pro-
`cess is performed. The vacuum chamber 104 is positioned in
`fluid communication with a vacuum pump 106 via a conduit
`108. The vacuum pump 106 is adapted to evacuate the
`vacuum chamber 104 to high vacuum. The pressure inside
`the vacuum chamber 104 is generally less than 100 Pa
`during operation. A Iced gas source .109. such as an argon
`gas sotu'L‘e.
`is introduced into the vacutuu chamber 104
`through a gas inlet 110. The gas [low is controlled by a valve
`112.
`The magnetron sputtering apparatus 100 also includes a
`cathode assembly 114 having a target material 116. The
`cathode assembly 114 is generally in the shape of a circular
`disk. The cathode assembly 114 is electrically connected to
`a first output 118 of the pulsed power supply 102 with an
`electrical transmission line 120. The cathode assembly 114
`is typically coupled to the negative potential of the pulsed
`povvcr supply 102. In order to isolate the cathode assembly
`114 from the vacuum chamber 104. m insulator 122 can be
`used to pasa the electrical transmission line 120 tl'rrough a
`wall ol‘tltc vacuum chamber 104. A grounded shield .124 can
`be positioned behind the cathode assembly 114 to protect a
`magnet 126 from bombarding ions. The magnet 126 shown
`in FIG. 1 is generally ring—shaped having its south pole 127
`on the inside ol'the ring and its north pole 128 on the outside
`of the ring. Many other magnet configurations can also be
`used.
`An anode 130 is positioned in the vacuum chamber 104
`proximate to the cathode assembly 114. "The anode 130 is
`typically coupled to ground. A second output 132 of the
`pulsed power supply 102 is also typically coupled to ground.
`A substrate 134 is positioned in the vacuum chamber 104 on
`a substrate support 135 to receive the sputtered target
`material 116. The substrate 134 can be electrically connected
`to a bias voltage power supply 136 with a transmission line
`138. In order to isolate the bias voltage power supply 136
`from the vacuum chamber 104. an insulator 140 can be used
`to pass the electrical transmission line 138 through a wall of
`the vacuum chamber 104.
`
`of a magnetron sputtering apparatus 200 according to the
`present invention. The magnetron sputtering apparatus 200
`includes a chamber 202, such as a vacuum chamber. The
`chamber 202 is coupled in fluid communication to a vacuum
`system 204 through a vacuum control system 206. In one
`_ embodiment. the chamber 202 is electrically coupled to
`ground potential. The chamber 202 is coupled by one or
`more gas lines 20"lr
`to a iced gas source 208.
`In one
`embodiment, the gas lines 20‘lr are isolated from the chamber
`and other components by insulators 209. Additionally. the
`gas litres 207 can be isolated from the feed gas source using
`in-line insulating couplers (not shown]. A gas [low control
`system 210 controls the gas flow to the chamber 202. The
`gas source 208 can contain any feed gas. such as argon. In
`some embodiments. the feed gas includes a mixture of gases.
`ln sortie embodiments. the feed gas includes a reactive gas.
`A substrate 211 to be sputter coated is supported in the
`chamber 202 by a substrate support 212. The substrate 211
`can be any type of work piece such as a semiconductor
`wafer.
`In one embodiment.
`the substrate support 212 is
`' electrically coupled to an output 213 ofa bias voltage source
`214. An insulator 215 isolates the bias voltage source 214
`from a Wall of the chamber 202. In one embodiment. the bias
`voltage source 214 is an alternating current (AC) power
`source. such as a radio frequency {RF} power source. In
`other embodiments (not shown). the substrate support 212 is
`coupled to ground potential or is electrically floating.
`The magnetron sputtering apparatus 200 also includes a
`cathode assembly 216.
`In one embodiment.
`the cathode
`assembly 216 includes a cathode 213 and a sputtering target
`220 composed of target material. The sputtering target 220
`is in contact with the cathode 218. In one embodiment. the
`sputtering target 220 is positioned inside the cathode 218.
`The distance from the sputtering target 220 to the substrate
`211 can vary from a few centimeters to about one hundred
`’ centimeters.
`111.:
`target material can be any material suitable for
`sputtering. For example. the target material can be a metallic
`
`40
`
`.13
`
`the pulsed power supply 102 applies a
`in operation.
`voltage pulse between the cathode assembly 114 and the
`anode 130 that has a sufficient amplitude to ioniae the argon
`['eed gas in the vacuum chamber 104. This typical ionization
`process is referred to as direct ionization or atomic ioniza-
`tion by electron impact and can be described as follows:
`.-\r+e' 15-13” “+2c'
`
`where Ar represents a neutral argon atom in the feed gas
`and e‘ represents alt ioniring electron generated in response
`to the voltage pulse applied between the cathode assembly
`114 and the anode 130. The collision between the neutral
`
`argon atom and the ionizing electron results in an argon ion
`(AF) and two electrons.
`The negatively biased cathode assembly 114 attracts
`positively charged ions with sullicient acceleration so that
`
`6|]
`
`TSMC-1301 I Page 22 of 32
`
`TSMC-1301 / Page 22 of 32
`
`

`

`q
`
`US 2,147,759 B2
`
`6
`
`material, polymer material. superconductive material, mag-
`netic material including ferromagnetic material. non-mag-
`netic material. conductive material. non-conductive mate-
`rial. composite material. reactive material. or a refractory
`material.
`
`The cathode assembly 216 is coupled to an output 222 of
`a matching unit 224. An insulator 226 isolates the cathode
`assembly 216 from a grounded wall ofthe chamber 202. An
`input 230 o f the matching unit 224 is coupled to a first output
`232 of a pulsed power supply 234. A second output 236 of
`the pulsed power supply 234 is coupled to an anode 238. An
`insulator 240 isolates the anode 238 [tom a grounded wall of
`the chamber 202. Another insulator 242 isolates the anode
`238 from the cathode assembly 216.
`In one embodiment. the first output 232 of the pulsed
`power supply 234 is directly coupled to the cathode assem-
`bly 216 (not shown). in one embodiment. the second output”
`236 of the pulsed power supply 234 is coupled to ground
`(not shown}. In this embodiment.
`the anode 238 is also
`coupled to ground (not shown}.
`In one embodiment (not shown)- the first output 232 of the
`pulsed power supply 234 couples a negative voltage impulse
`to the cathode assembly 216. In mother embodiment {not
`shown). the first output 232 of the pulsed power supply 234
`couples a positive voltage impulse to the anode 238.
`In one embodiment. the pulsed power supply 234 gener-
`ates peak voltage levels of up to about 30.000V.
`'l‘ypical
`operating voltages are generally between about 100V and 30
`kV. In one embodiment.
`the pulsed power supply 234
`generates peak current levels of less than one ampere to
`about 5.000 A or more depending on the size of the mag-
`netron sputtering system. 'l‘ypical operating currents varying
`from less than a few ampch to more than a few thousand
`aniperes depending on the Sire of the magnetron sputtering
`system. In one embodiment. the power pulses have a rep
`etition rate that is below 1 kHz.
`In one embodiment. the
`pulse width of the pulses generated by the pulsed power
`supply 234 is substantially betvveen about one microsecond
`and several seconds.
`
`The anode 238 is positioned so as to fault a gap 244
`between the anode 238 and the cathode assembly 216 that is
`sufficient
`to allow current to flow through a region 245
`between the anode 238 and the cathode assembly 216. In one
`embodiment.
`the gap 244 is between approximately 0.3
`centimeters (0.3 cm] and ten centimeters (10 cm). The
`volume of region 245 is determined by the area of the
`sputtering target 220. The gap 244 and the total volume of
`region 245 are parameters in the ionization process as will
`be discussed with relerence to FIG. 3.
`
`In one embodiment. the magnet assembly 252 includes
`switching electro-inagnets. which generate a pulsed mag-
`netic field proximate to the cathode assembly 216. In some
`embodiments. additional magnet assemblies (not shown)
`can be placed at various locations throughout the chamber
`202 to direct different types of sputtered target materials to
`the substrate 212.
`
`In one embodiment. the magnetron sputtering apparatus
`200 is operated by generating the magnetic field 254 proxi-
`mate to the cathode assembly 2 I 6. In the embodiment shown
`in FIG. 2. the permanent magnets 256 continuously generate
`the magnetic field 254. 111 other embodiments, the magnetic
`field 254 is generated by energizing a current source {not
`shown] that is coupled to electro—rnagnets. In one embodi—
`ment. the strength of the magnetic field 254 is between about
`one hundred and two thousand gauss. After the ntamtetic
`field 254 is generated. the feed gas from the gas source 208
`is supplied to the chamber 202 by the gas flow control
`system 210. In one embodiment. the feed gas is supplied to
`the chamber 202 directly between the cathode assembly 216
`and the anode 238.
`
`Jr
`
`III
`
`15
`
`Eli
`
`in one embodiment. the pulsed power supply 234 is a
`component
`in an ionisation source that generates the
`weakly-ionized plasma. The pulsed power supply applies a
`voltage pulse between the cathode assembly 216 and the
`anode 238. In one embodiment. the pulsed power supply 234
`applies a negative voltage pulse to the cathode assembly
`216. The amplitude and shape of the voltage pulse are such
`that a weakly—ionized plasma is generated in the region 246
`between the anode 238 and the cathode assembly 216. The
`weakly-ionized plasma is also referred to as a pro-ionized
`plasma. In one embodiment. the peak plasma density ofthe
`pre-ionized plasma is between about 10‘I and ID” cm‘3 for
`argon teed gas. The pressure in the chamber can vary from
`_ about 10‘3 to 10 Torr. The peak plasma density of the
`pre—iouized plasma depends on the properties of the specific
`magnetron sputtering system and is a function of the loca-
`tion of the measurement in the pre-ionired plasma.
`ln one embodiment. the pulsed power supply 234 gener-
`ates a low power pulse having an initial voltage of between
`about one hundred volts and five kilovolts with a discharge
`current of between about 0.1 ampercs and one hundred
`amperes in order to generate the weaklydonized plasma. In
`some embodiments the width of the pulse can be in on the
`order of 0.] microseconds up to one hundred seconds.
`Specific parameters a fthe pulse are discussed herein in more
`detail in connection with FIG. 4 and FIG. 5.
`
`3ft
`
`4t)
`
`43
`
`An anode shield 248 is positioned adjacent to the anode '
`238 so as to protect the interior wall ofthe chamber 202 frotn
`being exposed to sputtered target material. Additionally. the
`anode shield 248 can function as an electric shield to
`electrically isolate the anode 238 from the plasma. In one
`embodiment.
`the anode shield 248 is coupled to ground .7
`potential. An insulator 250 is positioned to isolate the anode
`shield 248 from the anode 238.
`The magnetron sputtering apparatus 200 also includes a
`magnet assembly 252.
`In one embodiment.
`the magnet
`assembly 252 is adapted to create a magnetic field 254
`proximate to the cathode assembly 216. The magnet assem-
`bly 252 can include penuaucnt magnets 256, or alterna-
`tively. elector-magnets (not shown). The configuration of the
`magnet assembly 252 can be varied depending on the
`desired shape and strength of the magnetic field 254. In
`alternate embodiments. the magnet assembly can have either
`a balanced or unbalzmced configuration.
`
`in one embodiment. prior to the generating ofthe weakly-
`ionized plasma. the pulsed power su