US00896984l B2
`
`(12) United States Patent
`Smith
`
`(10) Patent N0.:
`(45) Date of Patent:
`
`US 8,969,841 B2
`Mar. 3, 2015
`
`(54) LIGHT SOURCE FOR GENERATING LIGHT
`FROM A LASER SUSTAINED PLASNIA IN A
`ABOVE—A'I'MOSPHERIC PRESSURE
`CHAMBER
`
`USPC .................................................... .. 250/504 R
`See application file for complete search history.
`_
`References Cited
`
`(56)
`
`'5
`‘
`5
`.. 3
`‘S
`1
`(71) Applicant‘ Enerlretiq Technologv Inc Woburn.
`M/“U5?
`Inventor: Donald K. Smith, Boston, MA (US)
`
`(72)
`
`(73) Assignee: Encrgetiq Technology, Inc..Woburn.
`I
`‘
`
`( "‘ ) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U_3_C_ 154(1)) by 0 days_
`
`.
`(21) Appl. No.. 14/510,959
`
`(22)
`
`Filed:
`
`Oct. 9. 2014
`
`{65 )
`
`Prior Publication Data
`US 2015i'002l500 Al
`Jan. 22. 2015
`
`Related U.S. Application Data
`
`(63) Continuation of application No. 13/964,938. filed on
`Aug. 12, 2013, which is a continuation of application
`No.
`l3r’O2-4.027. filed on Feb. 9, 2011, now Pat. No.
`8.525.138. which is
`a
`continuation-in-part of
`
`(Continued)
`
`(51)
`
`(2006-01‘)
`(200601 -’
`
`Int‘ Cl‘
`G011 3:/10
`G21K 3/04
`(52) U.S. C1.
`CFC -------------------------------------- -- G-21K 5/04 (201301)
`USPC ---------------------------------------------------- ~ 250/504 R
`(53) Field Of ClaSSifi¢3fi0I1 Search
`(‘PC ........... .. H01} 5/00: H01} 61/62; H01} 15/O0;
`HOlJ 15./'02‘. H050 2/00
`
`US‘ PATENT DOCUMENTS
`3,826,996 A
`7,1-1974
`Jaegle etal.
`4.088.966 A
`5s'l978 Samis
`4,152_525 A
`51979 comm
`4,179,566 A
`1251979 Nadelson
`4498-039 A
`2/1935 Y0ShiZé1W=1 6L <11
`4.646.215 A
`2/T937 LCVTII CI éll.
`RE32.626 E
`3/"i988 Yoshizawa et al.
`
`CC0mi11UCd)
`
`JP
`JP
`
`FOREIGN PATENT DOCUMENTS
`61 l93358
`8.11986
`1_296560
`“.1989
`
`(Continued)
`
`OTHER PUBLICATIONS
`Beck. “Simple Pulse Generator for Pulsing Xenon Arcs with High
`Repetition Rate.” Rev. Sci.
`ln.v2‘rmn., vol. 45. N0. 2, Feb. 1974. pp.
`3l8«3l9.
`
`(Continued)
`
`Primary Examiner — Nicole lppolito
`Assistant Examiner —— Jason McC'.onnacl<
`
`(74) Allorizey. Agent, or Firm — Proskauer Rose LLP
`
`(57)
`ABSTRACT
`An apparatus for producing light includes a chamber and an
`ignition source that ionizes a gas within the chamber. The
`apparatus also includes at least one laser that provides energy
`to the ionized gas within the chamber to produce a high
`brightness light. The laser can provide a substantially con-
`tinuous amount of energy to the ionized gas to generate a
`substantially continuous high brightness light.
`
`30 Claims, 39 Drawing Sheets
`
`
`
`4!‘
`tot
`
`ASML 1101
`
`

`
`US 8,969,841 B2
`Page 2
`
`Related U.S. Application Data
`
`application No. 12./166,918. filed on Jul. 2. 2008, now
`Pat. No. 7.989.786. which is a continuation-ir1-part of
`application No. 1 1./695.348, filed onApr. 2, 2007, now
`Pat. No. 7.786.455. which is a continuation-in—part of
`application No. 11/395,523, filed on Mar. 31. 2006,
`now Pat. No. 7.435.982.
`
`Provisional application No. 61/302,797. filed on Feb.
`9, 2010.
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`(60)
`
`(56)
`
`JP
`JP
`JP
`JP
`JP
`JP
`WO
`
`FOREIGN PATENT DOCUMENTS
`
`04-144053
`05-82087
`08-299951
`09-288995
`2006-10675
`2006-08025 5
`2010:’093903
`
`5/"1992
`4; 1993
`11/ 1996
`1151997
`1.12006
`320116
`8/2010
`
`OTHER PUBLICATIONS
`
`Bussiahn. R., et. :11. “Experimental and theoretical investigations of
`a low-pressure He-Xe discharge for ligting purpose.” Journal of
`Applied Physics. vol. 95. No. 9. May 1, 2004. pp. 4627-4634.
`Carlhoff et 211.. “Continuous Optical Discharges at Very High Pres-
`sure.” P/zy.s’/'c'a 103C. 1981. pp. 439-447.
`Cremers et 21., “Evaluation of the Continuous Optical Discharge for
`Spectrochemical Analysis,” Spectroclzimica Acza. vol. 40B. No. 4.
`1985. pp. 665-679.
`Fiedorowicz er :11. '‘X—Ray Emission form Laser-Irradiated Gas Puff
`Targets.” Appl. Pitys. Let)‘. 62 (22). May 31. 1993. pp. 2778-2780.
`Franzen. “CW Gas Breakdown in Argon Using 10.6-pm Laser Radia-
`tion.”/lpp/. Pizys. Letzt. Vol. 21.
`2. Jul. 15. 1972. pp. 62-(4.
`Generalov et al.. “Continuous Optical Discharge.” ZfIETF Pis. Red.
`11. No. 9, May 5, 1970. pp. 302-304.
`Gerxeralov et 211.. “Experimental Investigation of :1 Continuous Opti-
`cal Discharge.” Soviez P}zysics.IETP. Vol. 34. _\‘o. 4. Apr. 1972. pp.
`763-769.
`Hamamatsu Product Information. “Super-Quiet Xenon Lamp Super-
`Quiet .\/lercury-Xenon Lamp,” Nov. 2005. pp. 1-16.
`Hecht. “Refraction”. Optics (Third Edition). 1998. Chapter 4. pp.
`100-101.
`Jeng et al.. “Theoretical Investigation ofLaser-Sustained Argon Plas-
`mas.” .2 Appl. Phys. 60 (7). Oct. 1. .1986. pp. 2272-2279.
`Keefer et 211.. “Experimental Study ofa Laser-Sustained Air Plasma.”
`Journal 0‘/“App[iedP}1ysics. Vo1.46..\’o. 3, .\/Iar. 1975,pp. 1080-1083.
`Keefer. “Laser-Sustained Plasmas,” Lase2'—Ina'uced Plasmas and
`/tpplz'zraIion.s. published by Marcel Dekker. edited by Radziemski ct
`a1.. 1989. pp. 169-206.
`Kozlov et a1., “Radiative Losses by Argon Plasma and the Emissive
`Model of 21 Continuous Optical Discharge.” Sov: Phys. JED’. vol. 39.
`No. 3. Sep. 1974. pp. 463-468.
`Kozlov et 211.. “Sustained Optical Discharges in Molecular Gases.”
`Sov. Phys. Tech. P1233’. 49(11). Nov. 1979. pp. 1283-1287.
`Moody, "Maintenance ofa Gas Breakdown in Argon Using 10.6—_u cw
`Radiation.” Joumal Qf/Ippiied Physics. vol. 46. No. 6. Jun. 1975, pp.
`2475-2482.
`“Radiometric Characterization of Ultrahigh Radiance Xenon
`Short-acr Dichage Lamps”. Applied Optics. vol. 47.
`2. Jan. 9.
`2008. pp. 224-229.
`Raizer. “Optical Discharges.”So1r: Phys. Usp. 23( 1 1). Nov. 1980. pp.
`789-806.
`Wilbers et 31.. “The Continuum Emission of an Arc Plasma.” J.
`Qurzm. SpeCI7'osc. Raziiai. ?}'a;z.gf2>r'. vol. 45. No. 1. 1991. pp. 1-10
`Wilbers et 21.1.. "The VLW’ Emissivity of a High-Pressure Cascade
`Argon Arc from 125 to 200 nm.” J. Qzmm‘. .S:pecI;'0.w.'. Radial. Trans-
`fer. vol. 46. 1991. pp. 299-308.
`
`cited by examiner
`
`4.780.608 A *
`4.789.788 A
`4.868.458 A
`5.801.495 A
`6.184.517 B1
`6,288,780 B1
`6,417,625 B1
`6.541.924 B1"‘
`6.788.404 B2
`6.956.329
`2
`7.050.149 B2
`7.427.167 B2
`7.429.818
`2
`7.652.430 B1
`200250021508 A1
`200250044629 A1
`2002/0080834 A1
`‘2002.~‘01'72235 A1
`200350052609 A1*
`200350068012 Al
`2003/0
`7499 Al""
`2003/0-68982 Al
`2003:'0231496 A1
`2004/0016894 A1
`200410026512 A1
`200450 29896 A1
`200450183038 A1
`200400238762 A1
`2004:’0264512 A1
`200550 67618 A1
`2005:’0.99829 A1
`2()(15/0205811 A1
`2005.‘0243390 A1
`2006511039435 Al
`200610 31515 A1
`20060 52128 A1“
`2006/0 86356 A1
`2006:"0 92152 Al*
`2006/0219957 A1"
`20070228288 A1
`200750228300 A1
`2007/0285921 A1
`200950032740 A1
`
`................. .. 2505281
`
`
`
`315./246
`
`10.51988 Cross etal.
`12.-’1988 Cox
`9.='1989 Davenpoitetal.
`9.-1998 Smolkaetal.
`2.12001 Sawada
`9/2001 Fairley etal.
`7.=’2002 Brooks et al.
`412003 Kane et a1.
`9.-"2004
`lange
`10/2005 Brooks etal.
`5/2006 Owaet al.
`9.92008 Holder etal.
`912008 Chang etal.
`1.20.10 Delgado
`2-"2002
`lshihara
`452002 Hertz etal.
`6/2002 Kusunosc
`1112002 Changer al.
`3.2003 Eastlund etal.
`432003 Ahmad et al.
`812003 Kondo ........................ .. 378.-1119
`932003 Kim
`127003 Sato etal.
`1.52004 VVester
`252004 Otsubo
`7-2004 Schmidt et :11.
`912004 Hiramoto et al.
`1232004 Mizoguchi et al.
`12.-12004 Hartlove etal.
`2005 lloshino et al.
`912005 Partlo etal.
`9.-’20()5 Partlo et al.
`11.52005 Tejnil
`242006 Cheymol er al.
`6.52006 Partlo et al.
`.7-2006 Manning
`8.-[2006
`Iamiei al.
`852006 Ershovctal.
`10.12006 Ershov el al.
`1012007 Smith
`10.2007 S1‘1’11l.I‘1
`1212007 Zulim et :11.
`2.12009 Smith et al.
`
`3.13-’634
`
`313/113
`
`250-5503.1
`........... .. 250/504 R
`
`

`
`U.S. Patent
`
`Mar. 3, 2015
`
`Sheet 1 of 39
`
`US 8,969,841 B2
`
`QL
`
`L.
`
`

`
`U.S. Patent
`
`Mar. 3, 2015
`
`Sheet 2 of 39
`
`US 8,969,841 B2
`
`

`
`U.S. Patent
`
`D4ar.3,2015
`
`Sheet30f39
`
`US 8,969,841 B2
`
`
`
`
`
`.53Q&Emma..m>mwmfiwxmtm>3
`
`
`
`....................................4«..I...».11..!.1......2.2!.........II3......I.I.213...2..3.....Z¥.!..........3......!Z....1.1....25»..£33.}....I.I».....,.1.Z:ILL
`
`.5§amEmmaW“
`mayonN.om3av3.5Q
`
`W.............
`
`(As zW‘«B:’M:’ éwuoaveuz? sswuafizsa
`
`Twmww_..-mmmMmM_MmmwwwmmnMWmmm
`
`i§i§i:1mwm
`
`
`

`
`U.S. Patent
`
`Mar. 3, 2015
`
`Sheet 4 of 39
`
`US 8,969,841 B2
`
`
`
`£35an§o.§.$23.5_a_m_.o,_%§
`
`w.@E
`
`

`
`U.S. Patent
`
`Mar. 3, 2015
`
`Sheet 5 of 39
`
`Us 8,969,841 B2
`
`C3
`CW
`3&3
`
`Em3-
`..\,...........~...-........4..
` §
`
`............»~.
`
`3%
`
`
`
`
`
`3........:.....Z.........2....................................................2
`
`ii"?
`
`9%
`
`wmm
`
`
`
`

`
`U.S. Patent
`
`Mar. 3, 2015
`
`Sheet 6 of 39
`
`US 8,969,841 B2
`
`3%
`
`w.@E
`
`

`
`U.S. Patent
`
`Mar. 3, 2015
`
`Sheet 7 of 39
`
`US 8,969,841 B2
`
`am.“
`
`Saw
`
`am.”
`
`
`

`
`U.S. Patent
`
`Mar. 3, 2015
`
`Sheet 8 of 39
`
`US 8,969,841 B2
`
`
`
`%_I,{.\\\.whmw_......z.i.....31...:..$3..
`
`W
`
`

`
`U.S. Patent
`
`Mar. 3, 2015
`
`Sheet 9 of39
`
`US 8,969,841 B2
`
`

`
`U.S. Patent
`
`m
`
`3
`
`US 8,969,841 B2
`
`m.E2,
`
`
`
`
`
`
`..m......,..4....,.z......n.......................-\
`
`
`
` fimewx»0x..
`
`gammy
`
`.§..3/,
`
`
`
`
`
`sw\..z............,,..:.....!.o../.%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%m..............
`
`
`M,,£3.$59.mug,/£38aammtmx,
`
`m\Sm?.\m\.
`9“W92mmxaa.
`
`mm:Ga3:3K
`
`11.£2:
`
`
`

`
`U.S. Patent
`
`Mar. 3, 2015
`
`Sheet 11 of 39
`
`US 8,969,841 B2
`
`A
`
`3.W.W.x
`
`0&2,
`
`.§C
`
`8:
`
`S,;@E
`
`
`

`
`U.S. Patent
`
`Mar. 3, 2015
`
`Sheet 12 of 39
`
`US 8,969,841 B2
`
`€268
`
`?25é
`
`
`
`33:32:§..f..z.§:_s..:icyt5:2...2253;::§..:......:,:f.»\
`
`..7
`
`g
`
`X....,4.o4n.R:
`.f.,,
`
`it\
`1,.
`
`.1cf
`....,..,..
`
`.)7J....
`
`:_E
`
`...5..r...A.JR.t.L
`.x...s..321...:;.:..»
`
`Fifi, 12
`
`
`

`
`U.S. Patent
`
`mm
`
`US 8,969,841 B2
`
`MM3,wLH..mmawNmea%M1:M\........
`
`.¥1¥¥!,..i..za..................-c.1.1552:m
`
`.3
`
`m.
`
`....u.......a.l.....s.la.........§.
`
`mwmwx ,M.V
`NmwWF;;mamw
`
`wmmw
`
`AEEV3mmxmmmumao
`
`mw“GE
`
`
`

`
`U.S. Patent
`
`Mar. 3, 2015
`
`Sheet 14 of 39
`
`Us 8,969,841 B2
`
`Q?
`
`a
`
`a
`1E
`LN-“
`
`
`
`3...mi
`
`
`

`
`U.S. Patent
`
`Mar. 3, 2015
`
`Sheet 15 of 39
`
`Us 8,969,841 B2
`
`r.¢D.«:t.k:.
`
`£3.m,E
`
`..
`
`$....:..>x:..}«.2..
`
`....
`
`.......:3..:2\A
`
`‘V.
`
`mama
`\
`
`\,,1%‘
`..§§..&.§¥
`SE..».z.._1..
`\.§§
`
`..m.u.
`
`
`
`
`
`

`
`U.S. Patent
`
`m
`
`e
`
`US 8,969,841 B2
`
`3»,\\¢LN{Q
`
`5Kxim\.\2Pa
`
`e\Av(h..LS/..\\.
`
`9..3.M/6...1W.
`tM
`
`..~/.w«xxx
`
`x.,:,mm;65
`
`
`

`
`U.S. Patent
`
`n3M
`
`11023,
`
`e
`
`US 8,969,841 B2
`
`e_h_S._
`
`sa:T:....azI.5_.\
`
`_
`
`9H"3_£1:z;;rs..2..Ls....xz)...0.7H11_t.L.I}..17.
`\.V»‘\.<I‘1»t.1.2E»
`
`gmC_ME
`
`3ma
`
`E9%.0E:E:Q.
`
`\....
`«fit
`
`
`

`
`U.S. Patent
`
`Mar. 3, 2015
`
`Sheet 18 of39
`
`US 8,969,841 B2
`
`
`
`-—-.ya»--—-.«u~..-.---.«—~5..
`
`
`
`
`
`

`
`U.S. Patent
`
`Mar. 3, 2015
`
`Sheet 19 of 39
`
`US 8,969,841 B2
`
`)
`i 35304-'§.;'2:2"‘
`
`Ne
`
`
`
`Ch‘?
`
`';g§;72
`Kr
`
`-
`
`I
`
`'5 ’.“C‘-’.";<"';(.‘.'”.':'
`Xe
`
`

`
`U.S. Patent
`
`Mar. 3, 2015
`
`Sheet 20 of 39
`
`US 8,969,841 B2
`
`
`
`'\r’v‘ave!ength, sun
`
`Fifi ‘£9
`
`

`
`U.S. Patent
`
`Mar. 3, 2015
`
`Sheet 21 of 39
`
`US 8,969,841 B2
`
`G2
`
`.xN.M\\.....Q\.2Gx
`
`K.\.\
`
`.\A
`
`ii’?
`
`
`
`....3553.....:.....}.>2..5<2:..«.32<<s.e<25.s>..es.
`
`......-.-..s..,,...........w».~..w....~.w..............-.....m..‘»,. .‘.
`
`.,.,.«........-...»..._.‘.,_.,.,.,M,.,,.,.‘.,......
`
`m
`
`S2G.
`
`»x....i§$é..$tz.>i...::z§s.....zz;z.a§.§.§zs..€>z.c.££2..._5;z§?,5.£x....i.
`.GMWn3
`
`......-.\-4.»...-......,..4.«.«»... ....,,...w..«».-.
`
`
`
`

`
`U.S. Patent
`
`Mar. 3, 2015
`
`Sheet 22 of 39
`
`Us 8,969,841 B2
`
`5
`
`0.
`
`HG. 21
`
`
`

`
`U.S. Patent
`
`Mar. 3, 2015
`
`Sheet 23 of 39
`
`US 8,969,841 B2
`
`-Spectra? Radiance vs NA
`
`..o/
`_/r‘
`Mg’/’
`
`xv!”
`
`-
`/,/sxw
`
`.....-~~«»——v-“~91”
`
`\\
`
`X‘
`
`M//’
`
`13”’
`
`~<.«-3-75:.»-n
`
`G3
`
`835
`
`C4
`
`€3.43
`
`05
`
`05$
`
`Fifi}. 22
`
`2?
`3
`g
`E 1.1‘
`9;
`=7
`,—
`E
`ii
`2
`5» 4.7
`Q,
`.-
`
`7%
`
`\‘:‘‘
`.3} 4;}
`
`E rs
`K:
`O
`
`4
`2
`
`E5
`
`.
`8
`<2;
`
`

`
`U.S. Patent
`
`Mar. 3, 2015
`
`Sheet 24 of 39
`
`Us 8,969,841 B2
`
`

`
`U.S. Patent
`
`Mar. 3, 2015
`
`Sheet 25 of 39
`
`US 8,969,841 B2
`
`40....
`
`Q\nu\.
`
`\..\
`..x..
`\.X
`
`\
`
`5..x«,,,,
`\//,\//\a.z/0\///
`
`
`fi\\._w......1§2»{2Ut3.£1u....u./M.54...
`Mumxx//,\>7|l........uc.%.I.l...1
`1..n.c1;.<».,..».,2Ev\\/..xx/xx1...//1/;
`:./i.8m,.......3\.un.l...r/..;n//A..AL
`
`..\,,fll.W////.xxiv/AM.
`\\\_../........,./,,xf,:
`,7x,./.,,,,\\/,2\/..n..,L.,/\\//V,/....Xx//\5.:...:
`
`
`all,,,,,,,,,L,/u..1.v\¢\Wit21-:,I..l
`xx.,..\a....////xx..\\.\x!;\/,\.\,\.\..,/xx/\.x.\x..\/...
`
`.......&2:.u.
`,,,,,./.\,/x,.\
`.\...s./\.1/.\\\/\,,xxx,,\/,K...\,,
`
`//r../\/Iln.1!.\(4;‘xva.\..;4vv......'.
`
`/\\\\\(.:l.s
`_..,./
`\.\\.///\//\//\/./.\//,,
`/1\\\\AVpi/,«xix...
`\._.,...5..:.zz3.2...$12.5,
`
`.................1
`
`.47.
`
`E...
`
`353. 24
`
`

`
`U.S. Patent
`
`Mar. 3, 2015
`
`Sheet 26 0:39
`
`US 8,969,841 B2
`
`
`
`

`
`U.S. Patent
`
`Mar. 3, 2015
`
`Sheet 27 of 39
`
`US 8,969,841 B2
`
`2300
`
`x\
`
`; ~~~~~~~~~{ Cafiecting a sam;:>§e of Eight
`
`§'*?~"5‘*9
`
`2
`
`g
`f
`
`+
`Convgvriing the sampie to an
`eéectzzcai Curran
`“‘“'”““"""""""‘;““““““““““““““““““"“““““““”'
`
`1
`
`252,3
`
`2
`‘1'"'
`Comparing converted sampée
`ETC) 9. refefence sampie is obtain §‘"’"" 2539
`1 an ezmr signaé
`§
`
`~‘
`
`E
`__.‘____"__.i...__.__....‘_,._.__.__..__._._~___.,
`i Processing me ermr signai to
`i Swain a cont:'o3 signaé
`
`‘
`
`€ E I
`
`?
`Seiéing a magnéiude «:3? a iaser
`based an the can‘-:m§ sigma?
`
`
`
`4
`
`_______,2R:.,‘
`
`‘
`5
`
`
`
`,‘..'\/¢1‘vlF'...vwfi........|¢1fl..'r\5.4........,..,.....,..............4..,.M......,.,.
`
`

`
`U.S. Patent
`
`Mar. 3, 2015
`
`Sheet 28 of 39
`
`Us 8,969,841 B2
`
`PL: rge R-mom
`(335
`Ag:
`
`Exhausi
`
`PKG. 27'
`
`
`

`
`U.S. Patent
`
`Mar. 3, 2015
`
`Sheet 29 of 39
`
`US 8,969,841 B2
`
`\~\
`.1
`
`Las>:~:' C::»rr«:=n:
`5:gna§ on »’\nz-flog
`Om 4-
`
`
`
`

`
`U.S. Patent
`
`Mar. 3, 2015
`
`Sheet 30 of 39
`
`US 8,969,841 B2
`
`
`
`HG, 29
`
`

`
`U.S. Patent
`
`Mar. 3, 2015
`
`Sheet 31 of 39
`
`US 8,969,841 B2
`
`HG.
`
`OJ
`
`

`
`U.S. Patent
`
`Mar. 3,2015
`
`Sheet 32 of 39
`
`US 8,969,841 B2
`
`

`
`U.S. Patent
`
`Mar. 3, 2015
`
`Sheet 33 of 39
`
`US 8,969,841 B2
`
`
`
`

`
`U.S. Patent
`
`Mar. 3, 2015
`
`Sheet 34 of 39
`
`US 8,969,841 B2
`
`
`
`Z33
`
`

`
`U.S. Patent
`
`Mar. 3, 2015
`
`Sheet 35 of 39
`
`US 8,969,841 B2
`
`Fifi-3. 34
`
`

`
`U.S. Patent
`
`Mar. 3, 2015
`
`Sheet 36 of 39
`
`US 8,969,841 B2
`
`mu
`
`OJ
`
`5
`
`£...\3
`
`5AU
`
`
`
`T0 waste
`
`RS. 35
`
`
`
`

`
`U.S. Patent
`
`Mar. 3, 2015
`
`Sheet 37 of39
`
`US 8,969,841 B2
`
`

`
`U.S. Patent
`
`Mar. 3, 2015
`
`Sheet 38 of 39
`
`US 8,969,841 B2
`
`40Q
`
`
`

`
`U.S. Patent
`
`Mar. 3, 2015
`
`Sheet 39 M39
`
`US 8,969,841 B2
`
`av
`avI
`Lx/..
`
`_G___
`
`
`

`
`US 8,969,84l B2
`
`1
`LIGHT SOURCE FOR GENERATING LIGHT
`FROM A LASER SUSTAINED PLASMA IN A
`ABOVE-ATLVIOSPHERIC PRESSURE
`CHAMBER
`
`RELATED APPLICATIONS
`
`2
`Accordingly. a need therefore exists T01‘ an improved light
`source whose emitted light is not significantly affected when
`the light passes through a wall ofa chamber that includes the
`location from which the light is emitted.
`
`'1:
`
`SUMMARY OF THE INVENTION
`
`to
`
`‘Jr
`
`The present invention features a light source for generating
`a high brightness light.
`The invention. in one aspect, features a light source having
`a chamber. The light source also includes an ignition source
`for ionizing a gas within the chamber. The light source also
`includes at least one laser for providing energy to the ionized
`gas within the chamber to produce a high brightness light.
`In some embodiments. the at least one laser is a plurality of
`lasers directed at a region from which the high brightness
`light originates. In some embodiments, the light source also
`includes at least one optical element for modifying a property
`of the laser energy provided to the ionized
`The optical
`'_ “ element can be. for example. a lens (e.g._. an aplanatic lens. am
`achromatic lens. a single element lens. and a fresnel lens) or
`mirror (eg. a coated mirror. a dielectric coated mirror, a
`narrow band mirror. and an ultraviolet transparent infrared
`retlecting mirror). In some embodiments. the optical element
`is one or more fiber optic elements for directing the laser
`energy to the gas.
`The chamber can include an ultraviolet transparent region.
`The chamber or a window in the chamber can include a
`material selected from the group consisting of quartz, Supra-
`sili'f.C quartz (Heraeus Quartz America, LLC, Buford, Ga),
`sapphire. Mg}?1. diamond, and CaF2. ln some embodiments,
`the chamber is a sealed chamber. In some embodiments, the
`chamber is capable of being actively pumped. In some
`embodiments,
`the chamber includes a dielectric material
`(eg. quartz). The chamber can be. for example. a glass bulb.
`In some embodiments, the chamber is an ultraviolet transpar-
`ent dielectric chamber.
`The gas can be one or more ofa noble gas. Xe. Ar, Ne. Kr.
`He. D2. H2, 02, F2, 3 metal halide, a halogen, Hg, Cd, Zn. Sn,
`Ga. Fe, Li. Na, an excimer forming gas, air. a vapor. a metal
`oxide. an aerosol. a flowing media, or a recycled media. The
`gas can be produced by a pulsed laser beam that impacts a
`target (c.g.. a solid or liquid) in the chamber. The target can be
`a pool or film of metal. in some embodiments. the target is
`capable of moving. For example. the target may be a liquid
`that is directed to a region from which the high brightness
`ligit originates.
`In some embodiments. the at least one laser is multiple
`diode lasers coupled into a fiber optic element. In some
`‘ embodiments, the at least one laser includes a pulse or con-
`tinuous wave laser. In some embodiments, the at least one
`laser is an IR laser, a diode laser. a fiber laser, an ytterbium
`laser. a C03 laser, a YAG laser. or a gas discharge laser. In
`some embodiments. the at least one laser emits at least one
`wavelength of electromagnetic energy that
`is
`strongly
`absorbed by the ionized medium.
`The ignition source can be or can include electrodes. an
`ultraviolet ignition source. a capacitive ignition source. an
`inductive ignition source, an RF ignition source. a microwave
`ignition source. a llash lamp. a pulsed laser. or a pulsed lamp.
`The ignition source can he a continuous wave (CW) or pulsed
`laser impinging on a solid or liquid target in the chamber. The
`ignition source can be external or internal to the chamber.
`The light source can include at least one optical element for
`‘ modifying a property ofeleetromagnetic radiation emitted by
`the ionized gas. The optical element can be. for example. one
`or more mirrors or lenses. In some embodiments. the optical
`
`This application is a continuation ofU.S. Ser. No. 13/964,
`938, filed on Aug. 12, 2013. which is a continuation of U.S.
`Ser. No. l3/024,027, filed on Feb. 9, 201 l. now US, Pat. No.
`8.525.138, which claims the benefit of. and priority to U.S.
`Provisional Patent Application No. 61/302,797, filed on Feb.
`9. 2010, the entire disclosure of which is incorporated by
`reference herein, Ser. No. 13/024.027 is also a continuation-
`in-part ofU.S. Ser. No. 12/166,918. filed on Jul. 2, 2008. now
`U.S. Pat. No. 7,989,786. which is a continuation—in—part of
`U.S. Ser. No. l 1/695.348, filed onApr. 2, 2007. now US. Pat.
`No. 7.786,-455, which is a continuation-in-part of U.3. Ser.
`No. ll./395.523. filed on Mar. 31. 2006, now U.S. Pat. No.
`7,435,982. the entire disclosures of each ofwhich are hereby
`incorporated by reference herein.
`
`FIELD OF THE INVENTION
`
`The invention relates to methods and apparatus for provid-
`ing a laser—driven light source.
`
`BACKGROUND OF THE; lN\/l£N'l'lON
`
`High brightness light sources can be used in a variety of
`applications. For example. a high brightness light source can
`be used for inspection. testing or measuring properties asso-
`ciated with semiconductor waters or materials used in the
`fabrication of wafers (e.g.. reticles and photomasks). The
`electromagnetic energy produced by high brightness light
`sources can, alternatively, be used as a source ofillumination
`in a lithography system used in the fabrication of wafers, :1
`microscopy system. or a photoresist curing system. The
`parameters (e. g.. wavelength. power level and brightness) of
`the light vary depending upon the application.
`The state ofthc art in. for example. wafer inspection sys-
`tems involves the use of xenon or mercury arc lamps to
`produce light. The are lamps include an anode and cathode
`that are used to excite xenon or mercury gas located in a
`chamber of the lamp. An electrical discharge is generated
`between the anode and cathode to provide power to the
`excited ( ionized) gas to sustain the light emitted by the
`ionized gas during operation of the light source. During
`operation. the anode and cathode become very hot due to
`electrical discharge delivered to the ionized gas located
`between the anode and cathode. As a result. the anode and/’or
`cathode
`prone to wear and may emit particles that can
`contaminate the light‘ source or result in failure of the light
`source. Also. these are lamps do not provide sufiicient bright-
`ness for some applications. especially in the ultraviolet spec-
`trum. Further. the position oi‘ the arc can be unstable in these
`lamps.
`Accordingly. a need therelore exists for improved high
`brightness light sources. A need also exists for improved high
`brightness light sources that do not rely on an electrical dis-
`charge to maintain a plasma that generates a high brightness
`light.
`The properties of light produced by many light sources
`(e, g.. are lamps. microwave lamps) are aifec ted when the light
`passes through a wall of. for example. a chamber that includes
`the location from which the light is emitted.
`
`I.2or
`
`3 I‘)
`
`m wt
`
`40
`
`at
`
`U» v.
`
`61‘)
`
`

`
`US 8,969,841 B2
`
`3
`element is configured to deliverthe electromagnetic radiation
`emitted by the ionized gas to a tool (e.g._. a wafer inspection
`tool. a microscope. a metrology tool. a lithography tool. or an
`endoscopic tool).
`The invention, in another aspect. relates to a method for
`producing llflll. The method involves ionizing with an igni-
`tion source a gas within a chamber. The method also involves
`providing laser energy to the ionized gas in the chamber to
`produce a high brightness light.
`In some embodiments. the method also involves directing
`the laser energy through at least one optical element for
`modifying a property of the laser energy provided to the
`ionized gas. In some embodiments, the method also involves
`actively pumping the chamber. The ionizable medium can be
`a moving target. In some embodiments, the mediod also
`involves directing the high brightness light througi at least
`one optical element to modify a property ofthe light. In some
`embodiments, the method also involves delivering the high
`brightness light emitted by the ionized medium to a tool (eg..
`a wafer inspection tool. a microscope. u metrology tool, a
`lithography tool, or an endoscopic tool).
`In another aspect. the invention features a light source. The
`lights source includes a chamber and an ignition source for
`ionizing an ionizable medium within the chamber. The light
`source also includes at least one laser for providing substan-
`tially continuous energy to the ionized medium within the
`chamber to produce a high brightness light.
`In some embodiments. the at least one laser is a continuous
`wave laser or a high pulse rate laser. In some embodiments.
`the at least one laser is a high pulse rate laser that provides
`pulses ofenerg; to the ionized medium so the high brightness
`light is substantially continuous. In some embodiments. the
`magnitude of the high brightness light does not vary by more
`than about 90% during operation. In some embodiments, the
`at least one laser provides energy substantially continuously
`to minimize cooling of the ionized medium when energy is
`not provided to the ionized medium.
`In some embodiments, the light source can include at least
`one optical element (eg. a lens or mirror) for modifying a
`property of the laser energy provided to the ionized medium.
`The optical element can be. for example, an aplanatic lens, an
`achromatic lens. a single element lens. a frcsnel lens. a coated
`mirror, a dielectric coated mirror. a narrow band mirror. or an
`ultraviolet transparent infrared reflecting mirror.
`In some
`embodiments, the optical element is one or more fiber optic
`elements for directing the laser energy to the ionizable
`medium.
`In some embodiments. the chamber includes an ultraviolet
`transparent region. In some embodiments. the chamber or a
`window in the chamber includes a quartz material. suprasil
`quartz material. sapphire material, MgF3 material. diamond
`material. or Calfi material. In some embodiments. the cham-
`ber is a sealed chamber. The chamber can be capable ofbeing
`actively pumped.
`In some embodiments.
`the chamber
`includes a dielectric material
`quartz). In some embodi-
`ments. the chamber is a glass bulb. In some embodiments. the
`cliamber is an ultraviolet transparent dielectric chamber.
`The ionizable medium can be a solid. liquid or gas. The
`ionizable medium can include one or more olia noble gas. Xe.
`Ar. Ne.
`He. I)_,. I'll. 02, F_,. a metal halide. a halogen. Hg.
`Cd. Zn. Sn. Ga. Fe. Li. Na. an excimer forming gas. air. a
`vapor. a metal oxide. an aerosol. a flowing media. a recycled
`media. or an evaporating target. In some embodiments. the
`ionizable medium is a target in the chamber and the ignition
`source is a pulsed laser that provides a pulsed laser beam that
`strikes the target. The target can be a pool or film of metal. In
`some embodiments. the target is capable of moving.
`
`3
`
`l0
`
`l4) at
`
`40
`
`I):
`
`III '4.
`
`60
`
`4
`In some embodiments, the at least one laser is multiple
`diode lasers coupled into a fiber optic element. The at least
`one laser can emit at least one wavelength ofelectromagnetie
`energy that is strongly absorbed by the ionized medium.
`The ignition source can be or can include electrodes. an
`ultraviolet ignition source. a capacitive ignition source. an
`inductive ignition source. an
`ignition source. a microwave
`ignition source. a flash lamp. a pulsed laser. or a pulsed lamp.
`The ignition source can be external or internal to the chamber.
`In some embodiments, the light source includes at least one
`optical element (e.g.. a mirror or lens) for modifying a prop-
`erty of electromagnetic radiation emitted by the ionized
`medium. The optical element can be configured to deliver the
`electromagnetic radiation emitted by the ionized medium to a
`tool (e. g.. a wafer inspection tool. a microscope, a rnetrology
`tool. a lithography tool. or an endoscopic tool).
`The invention. in another aspect relates to a method for
`producing light. The method involves ionizing with an igni-
`tion source an ionizable medium within a chamber. The
`method also involves providing substantially continuous
`laser energy to the ionized medium in the chamber to produce
`a high brightness light.
`In some embodiments. the method also involves directing
`the laser energy through at least one optical element for
`modifying a property of the laser energy provided to the
`ionizable medium. The method also can involve actively
`pumping the chamber. In some embodiments, the ionizable
`medium is a moving target. ‘the ionizable medium can
`include a solid. liquid or gas. In some embodiments. the
`method also involves directing the high brightness light
`through at least one optical element to modify a property of
`the light. In some embodiments, the method also involves
`delivering the
`brigtness light emitted by the ionized
`medium to a tool.
`The invention. in another aspect. features a light source
`having a chamber. The light source includes a first ignition
`means for ionizing an ionizable medium within the chamber.
`The light source also includes a means for providing substan-
`tially continuous laser energy to the ionized medium Within
`the chamber.
`The invention, in another aspect, features a light source
`having a chamber that includes a reflective surface. The light
`source also includes an ignition source for ionizing a gas
`within the chamber. The light source also includes a reflector
`that at least substantially reflects a first set of predefined
`wavelengths of electromagnetic energy directed toward the
`reflector and at least substantially allows a second set of
`predefined wavelengths of electromagnetic energy to pass
`through the reflector. The light source also includes at least
`one laser (eg, a continuous-wave fiber laser) external to the
`chamber for providing electromagnetic energy to the ionized
`gas within the chamber to produce a plasma that generates a
`high brightness light. A continuous-vv‘ave laser emits radia-
`tion continuously or substantially continuously rather than in
`short bursts. as in a pulsed laser.
`In some embodirnents. at least one laser directs a lirst set of
`wavelengths olielectromagnelic energy through the reflector
`toward the re tlective surface (g.. inner surface) of the cham-
`ber and the relleetive surface directs at least a portion of the
`first set of wavelengths o T electromagnetic energy toward the
`plasma. In some embodiments. at least a portion of‘ the high
`brightness light is directed toward the reflective surface of the
`chamber. is reflected toward the reflector. and is reliected by
`the reflector toward a tool. In some embodiments. at least one
`laser directs a first set of wavelengths of electromagnetic
`energy toward the reflector.
`the rellector reflects at least a
`portion of the first wavelengths of electromagnetic energy
`
`

`
`US 8,969,841 B2
`
`5
`towards the reflective surface of the chamber, and the reflec-
`tive surface directs a portion of the first set of wavelengths of
`electromagnetic energy toward the plasma.
`In some embodiments. at least a portion ofthe high bright-
`ness light is directed toward the reflective surface of the
`chamber. is reflected toward the reflector. and passes through
`the reflector toward an output of the light source. In some
`embodiments, the light source comprises a microscope, ultra-
`violet microscope, wafer inspection system. reticle inspec-
`tion system or lithography system spaced relative to the out-
`put of the light source to receive the high brightness light. In
`some embodiments, a portion of the high brightness light is
`directed toward the reflective surface of the chamber.
`is
`reflected toward the reflector. and electromagnetic energy
`comprising the second set ofpredeflned wavelengths of elec-
`tromagnetic energy passes through the reflector.
`The chamber of the light source can include a window. In
`some embodiments. the chamber is a sealed chamber. In some
`embodiments, the reflective surface of the chamber com-
`prises a curved shape, parabolic shape, elliptical shape,
`spherical shape or aspherical shape. In some embodiments.
`the chamber has a reflective inner surface. In some embodi-
`ments, a coating or film is located on the outside of the
`chamber to produce the reflective surface. In some embodi-
`ments, a coating orfilm is located on the inside ofthe chamber
`to produce the reflective surface. In some embodiments. the
`reflective surface is a structure or optical element that is
`distinct from the inner surface of the chamber.
`The light source can include an optical element disposed
`along a path the electromagnetic energy from the laser travels.
`In some embodiments, the optical element is adapted to pro-
`vide electromagnetic energy from the laser to the plasma over
`a large solid angle. In some embodiments. the reflective sur-
`face of the chamber is adapted to provide electromagnetic
`energy from the laser to the plasma over a large solid angle. In
`some embodiments, the reflective surface of the chamber is
`adapted to collect the high brightness light generated by the
`plasma over a large solid angle. In some embodiments, one or
`more of the reflective surface. reflector and the window
`include (e.g._, are coated or include) a material to filter pre-
`defined wavelengths (e.g.. infrared wavelengths of electro-
`magnetic energy) of electromagnetic energy.
`The invention. in anothcraspcct. features a light sourcethat
`includes a chamber that has a reflective surface. The light
`source also includes an ignition source for ionizing a gas
`within the chamber. The light source also includes at least one
`laser external to the chamber for providing electromagnetic
`energy to the ionized gas within the chamber to produce a
`plasma that generates a high brightness light. The light source
`also includes a rellector positioned along a path that the
`electromagnetic energy travels from the at least one laser to
`the reflective surface of the chamber.
`In some embodiments. the reflector is adapted to at least
`substantially reflect a first set oil’ predefined wavelengths of
`electromagnetic energy directed toward the reflector and at
`least substantially allow a second set of predefined wave-
`lengths ofelectromagnetic energy to pass through the reflec-
`tor.
`
`The invention. in another aspect. relates to a method for
`producing light. The method involves ionizing with an igni-
`tion source a gas within a chamber that has a reflective sur-
`face. The method also involves providing laser energy to the
`ionized gas in the chamber to produce a plasma that generates
`a high brightness light.
`In some embodiments. the method involves directing the
`laser energy comprising a tlrst set of wavelengths of electro-
`magnetic energy through a reflector toward the reflective
`
`l0
`
`in at
`
`<10
`
`vi
`
`Jt vi
`.,
`
`6
`surface of the chamber. the reflective surface refiecting at
`least a portion of the first set of wavelengths ofelectromag-
`netic enery toward the plasma. In some embodiments, the
`method involves directing at least a portion ofthe high bright-
`ness light toward the reflective surface of the chamber which
`is reflected toward the reflector and is reflected by the reflec-
`tor tow