F 2 l a s e r (1 5 7 nm) l i t h o g r a p h y: m a t e r i a l s a nd p r o c e s s e s E. Tegou, E. Gogolides, P. Argitis, C. D. Diakoumakos, A. Tserepi, A.C. Cefalas 1, E. Sarantopoulou 1, J. Cashmore 2, P. Grunewald 2 Institute of Microelectronics, NCSR "Demokritos", Ag. Paraskevi, Attiki, Greece 1 National Hellenic Research Foundation, Theoretical and Physical Chemistry Institute, 48, Vass. Constantinou Avenue, Athens, Greece 2 Exitech Limited, Hanborough Park, Long Hanborough, Oxford OX8 8LH, England  novel single layer acrylate photoresists (optimized for 193 nm): negative-tone chemically amplified resists (CARS)  ADNR-3330 (Aqueous Developed Negative Resist) poly(hydroxyethyl methacrylate)-co- (cyclo hexyl methacrylate) -co-(isobornyl methacrylate) -co-(acrylic acid) positive-tone NON CARS a) Poly(hydroxyethylmethacrylate) (PHEMA) b) Hydroxyl ethyl methacrylate copolymers  PHECA poly(hydroxyethylmethacrylate)-co- (cyclohexylmethacrylate)-co-(acrylic acid)  Siloxanes (bilayer approach) based on PDMS (polydimethylsiloxane) M a t e r i a l s VUV s p e c t r aP r o c e s s e s 157 nm e x p o s u r e s We set out to explore the viability of single layer and bilayer resist approaches for 157 nm lithography. Spectroscopic studies of acrylic polymers, phenolic polymers and siloxanes have been used as a vehicle for a first screening of candidate materials Acrylic polymers with reduced amount of carbonyl moieties have an absorbance coefficient of 4-7 μm -1, therefore they can be imaged at a thickness of only 60 nm. Organosilicon materials have the right absorbance of 1-3 μm -1 at 157 nm and can be imaged as negative tone resists at a thickness of ~120 nm for bilayer processes. Exposures have been carried out at the first European 157 nm prototype microstepper constructed by Exitech ADNR-3330 : process steps 1.spin coating (film thickness 0.48μm) 2.prebake at 160 o C for 1 min 3.exposure 4.Post exposure bake at 90 o C for 2 min 5.Wet development in commercial AZ 726MIF, diluted in deionized water (H 2 O:AZ, 100:1) for 50 s PDMS : process steps 1.spin coating on ~0.5 μm hard baked novolac (film thickness ~0.1 μm) 2.prebake at 90 o C for 1 min 3.exposure 4.post exposure bake at 90 o C for 1 min 5.wet development in MIBK for 90 s 6.Dry development (RIE or HDP) in 2 steps including a BTE step 0.13μm lines0.14μm lines 193 nm exposure Dose: 56 mJ/cm 2 The resolution capability of the resists was tested with 193 nm exposures and electron-beam exposures 0.20μm lines/spaces 0.15μm / 0.30 lines/spaces 193 nm exposure e-beam exposure Dose: 3.4 mJ/cm 2 Dose: 5.75 μC/cm 2 d:2,.8 – f:24.75 d: 2.8 – f:25,25 d: f:25.75 d: f: : f: d:3.2 - f: E X P O S U R E D O S E  F O C U S  ADNR μm L/S d: f: 22 d:0.5 - f: 22 d: f: 22 d: f: 23 d: f: 24 d: f: 25 PDMS (on top of hard baked novolac) 1.0 μm L/S 0.5 μm L/S 0.35 μm L/S E X P O S U R E D O S E  F O C U S  Etching process not optimized. Lines were 250% overdeveloped. Mass spectrum of a tertiary-butyl acrylate during irradiation of the sample with a F 2 laser at 157 nm O u t g a s i n g s t u d i e s