New Structure of Monocyclic Fluoropolymer for 157nm Photoresist

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Ronald Benson
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1 New Structure of Moocyclic luoropolymer for 157m Photoresist Masataka Eda, Yoko Takebe, Osamu Yokokoji Research eter, Asahi Glass o., Ltd. Akihiko Otoguro, Shigeo Irie, Toshiro Itai, Kiyoshi ujii Semicoductor Leadig Edge Techologies, Ic.

2 Outlie Itroductio ocept for developmet Sythesis of ew moomers haracteristics of ew homopolymers Simulatio of characters opolymerizatio Summary

3 Itroductio 157m lithography Next geeratio techology for semicoductor productio. It is ecessary to develop a resist material which is trasparet at 157m wavelegth. luoropolymer Good cadidate as a resist i 157m lithography for its good trasparecy luorie chemistry AG core techology & polymerizatio techology Study of luoropolymer for 157m Lithography

4 Requiremets for 157m Resist Lithography process Requiremets for 157m resist Resist coatig Exposure Resist Si wafer 157m light Photo mask High trasparecy Developmet (developer : TMAHaq.) Bakig Etchig Ashig Solubility i alkalie sol. Heat resistace (high Tg) Etchig resistace

5 Strategy Developmet of Moocyclic Polymer cotaiig essetial fuctios i oe uit luoriated mai-chai High trasparecy yclic structure Proper dry-etchig resistace & heat resistace Alkalie soluble group Good dissolutio behavior Uiformity of the polymer is superior to co-polymers.

6 1 st geeratio resist PR Absorptio coefficiet : [µm -1 ] 2 HH H 2 3 OR Heat resistace : Tg [ O ] Etchig rate : 2 [times vs Kr resist] Should be improved R=H, -H 2 OH 3 Dissolutio rate : 80 [m/sec]

7 Previous report UGU series Motivatio A little structural chage causes a big ifluece o polymer performace. 3 3 AS-1 -H 2 AS-2 Dissolutio rate : 8m/sec >600m/sec This report 3 3 urther work : See poster sessio! 2 HH H 2 3 OR PR -H 2 or + H 2 How do the modificatios work o polymer performaces?

8 ocept of ew moomers Improvemet of etchig resistace or dissolutio behavior 3 PR moomer [M 1 ] -H 2 + H 2 keepig high trasparecy New moomer [M 0 ] 3 3 New moomer [M 2 ] polymerizatio polymerizatio 3 New polymer [P 0 ] Higher acidity? 3 New polymer [P 2 ] High etchig resistace?

9 Geeral sythetic route MgX / TH l l 3 O Z l 0-10 O O l 3 3 Itermediate of New moomers PR moomer =0 :M 0 1 :M 1 2 :M 2

10 yclopolymerizatio M 0 : 3 polymerizatio 3 l m 3 3 l + m + = 1 P polymerizatio l m M 1 : P l + m + = 1 polymerizatio M 2 : l P m 2 3 Stadard polymerizatio coditios Polymerizatio temp. Polymerizatio time Solvet Moomer coc. Iitiator o, 40 o 18hrs. R225, AcOEt wt% Perfluorobutyryl peroxide Diisopropyl peroxy dicarboate l + m + = 1

11 P 0 haracteristics of homopolymers P 1 (PR) P Mw Abs. Dissolut io Et chig Tg coeffciet * rat e rat e [µm -1 ] [m/ sec] [ vs Kr resist] [ O ] P ca. > P 1 (PR) P * : at 157m Homopolymers from ew moomers are ufavorable as a resist polymer. These moomers are useful as comoomers.

Modelig Study Model : eicosamer structure 3 3 3

12 Modelig Study Model : eicosamer structure P 0 P 1 (PR) P 2 :Hydroge, :arbo, :Oxyge, :luorie

13 lexibility of polymer ad Tg More balky rig structure suppresses movemet of mai chai at higher temp P P 1 0 (PR) High (easy) lexibility of mai chai (free rotatio of mai chai) P 2 Low (difficult) Tg : 85 O < 150 O < 169 O

14 Solvet excluded surface 1 alculatio based o solvet excluded surface of model polymers Hypothesis : reactio rate surface area Dissolutio rate alculatio with a probe : r=0.215µm (Ttramethyl ammoium catio) : r=0.119µm (Hydroxyl aio) Hydrophilic surface area ( group) Polymer surface area Probe (TMA + ) or ( - ) :Hydroge, :arbo, :Oxyge, :luorie The other factors :Acidity (pka), cocetratio*, Hydrophilicity ( * partly cosidered i this calculatio )

R =R O >> R,R H (R,R O,R,R H :Reactivity of fluorie,oxyge,carbo ad hydroge atom)

15 Solvet excluded surface 2 Hypothesis : reactio rate surface area Reactivity of each atom for etchig gas. R =R O >> R,R H (R,R O,R,R H :Reactivity of fluorie,oxyge,carbo ad hydroge atom) Etchig rate surface area of fluorie & oxyge atom Polymer surface area alculatio with a probe : r=0.133µm ( cataio) + Probe :Hydroge, :arbo, :Oxyge, :luorie

16 Results of calculatio alculated ratio Dissolutio rate (observed [m/s]) Etchig rate (observed [vs Kr resist]) P 0 P 1 (Stadard) P 2 88 : 80 : 58 (800) (80) (2) 2.2 : 2.0 : 1.9 (2.7) (2.0) (1.7) Qualitatively agreed ause of discrepacy betwee calculatio ad observatio The other factors (especially o dissolutio rate estimatio) Model of uit structure

17 opolymerizatio 1. opolymerizatio of M 0 ad M 1 [P 0/1 ] Improvemet of P 1 (PR) s dissolutio rate by itroductio of M m 3 2. opolymerizatio of M 0 ad M 2 [P 0/2 ] ombiatio of P 0 s good dissolutio rate ad P 2 s high Tg ad etchig resistace m 3

18 opolymerizatio of M0 ad M M 0 M 1 P 0/1 m 3 Dissolutio rate ad Tg of P 0/1 Dissolutio rate [m/sec] Tg Dissolutio rate Tg [ O ] P 1 homopolymer M0 ratio i polymer [mol%] P 0 homopolymer (PR)

19 opolymerizatio of M0 ad M M 0 M 2 P 0/2 m 3 Dissolutio rate [m/sec] Dissolutio rate ad Tg of P 0/2 Dissolutio rate Tg P 0 homopolymer P 2 homopolymer M2 ratio i polymer [mol%] Tg [ O ]

20 Partial protectio of acidic group opolymerizatio with protected moomer (Method A) 3 M 0 or M 2 p + 3 MOM O M 1 -MOM 3 O m MOM 3 p Itroductio of protectig group ito polymer (Method B) 3 m 3 p (1) Na (2) MOMl 3 O m MOM 3 p P 0/1 or P 0/2 Protectig group is desired to be preferetially itroduced ito M0 uit.

21 Protectio of M0 uit (Method B) Before protectio After protectio (MOM) Protectio reactio O 3 H 2 3 OH H NMR 1 H NMR M2 H 2 OH 3M0 M0 :51mol% M2 :49mol% M0 :28mol% :49mol% :23mol% ppm ppm Protectig group is preferetially itroduced ito M 0 uit. advatage i high R max /R mi cotrast

22 Patterig MOM blocked P 0/1 [M0/M1] (18mol% protectio by method A) 62.0 mj/cm mj/cm 2 95m 80m 90m 75m 58.0 mj/cm 2 85m 70m 54.0 mj/cm 2 150m thickess NA=0.9, 157m microstepper, Alt-PSM

23 Result of ew fluoropolymer P 0 ~P P 0 Etchig rate [vs Kr resist] P 0 P 1 (PR) P 2 Dissolutio rate [m/sec] Absorptio coefficiet [/µm] P 1 (PR) P 0/2 P 0/1 P Absorptio coefficiet [/µm] Others polymers

24 Summary New moocyclic fluoropolymers (PR derivatives) have bee developed for 157m resist base polymer. Dissolutio rate of P 0 was excellet ad over 800m/sec. However its etchig rate was sigificatly icrease to 2.7 [vs Kr resist]. Etchig resistace ad Tg of P 2 were improved to 1.7 [vs Kr resist] ad 169 O, respectively, compared to PR. These moomers are useful as comoomers for 157m resist due to their good trasparecy. Protectio of polymer ad patterig work are ow uder study.

25 uture work The same modificatio will be applied to AS. 3 -H 2 3 or AS-2 + H 2 (UGU) How do the modificatios work o polymer performaces?

26 Ackowledgemets

27 Thak you for your kid attetio.

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