High intensity EUV and soft X-ray X plasma sources modelling

High intensity EUV and soft X-ray X plasma sources modelling Sergey V. Zakharov +, Vasily S. Zakharov +,Peter Choi, Alex Yu. Krukovskiy, Vladimir G. Novikov, Anna D. Solomyannaya NANO UV sas EPPRA sas KIAM RAS + also with RRC Kurchatov Institute Extreme Ultraviolet Sources University College Dublin,, November 13-15,

ABSTRACT The average power of EUV sources at IF required for lithography HVM is higher than presently available. At the same time, for actinic mask blanks, patterned mask and in-situ inspection tools, EUV sources of moderate power but very high brightness are required. In practice, the non-equilibrium plasma dynamics and self-absorption of radiation limits the in-band EUV radiance of the source plasma, and the etendue constraint limits the usable power of a conventional single unit EUV source. Under those conditions one of the primary goals in the development of EUVL is the modelling of plasma-based light sources created by intense lasers and high-current pulsed discharges. A new generation of the computational code Z* is currently developed under international collaboration in the frames of FP7 IAPP project FIRE for modelling of multi-physics phenomena in radiation plasma sources to contribute considerably to solving current EUVL source problems as well as extending their application to subsequent nodes (16nm and beyond) and to shorter wavelength radiation applications. The radiation plasma dynamics, the spectral effects of self-absorption in LPP and DPP and resulting conversion efficiencies are discussed. The modelling results are guiding a new generation of multiplexed sources being developed at NANO-UV, based on spatial/temporal multiplexing of individual high brightness units, to deliver the requisite brightness and power for lithography, actinic metrology and soft X- ray imaging applications.

EUV Lithography chosen for nano features microchip production HP EUV source for HVM & actinic mask inspection - a key challenge facing the industry NOW EUV to 16 nm HVM

EUV Light Source Sn, Xe, Li high energy density plasma (T e =0-40eV) - EUV light source in narrow % band around 13.5nm wavelength LPP & DPP - methods to produce the the right conditions for HED plasma LPP combined NdYAG +CO I = 10 11 W/cm T e = 40eV N e =10 19-10 1 cm -3 DPP DPP micro plasma j = 1-10 MA/cm T e = 0-30eV N e =10 15-10 17 cm -3 Z * MHD code modeling For HVM - 00-500 W of in-band power @ IF with etendue < 3mm sr For mask inspections ABI AIMS APMI 10 100 1000 W/mm sr at-wavelength radiance kw (source) W (IF) is the source of the problem -

Next Generation Modelling Tools - FP7 IAPP project FIRE Theoretical models and robust modeling tools are developed under international collaboration in the frames of European FP7 IAPP project FIRE The FIRE project aims to substantially redevelop the Z* code to include improved atomic physics models and full 3- D plasma simulation of plasma dynamics spectral radiation transport non-equilibrium atomic kinetics with fast electrons transport of fast ions/electrons condensation, nucleation and transport nanosize particles. Modelling can be the key factor to scientific and technological solutions in EUVL source optimization with fast particles and debris to solve current EUVL source problems as well as extending their application to nm and beyond. The research and transfer of knowledge is focused on two major modeling applications; EUV source optimization for lithography and nanoparticle production for nanotechnology. Theoretical modelling will be benchmarked by LPP and DPP experiments

ZETA Z * RMHD Code Z * BME complete physical model TABLES nonlte atomic & spectral data (Te,ρ,U) Spectral postprocessing RMHD (r,z+φ) with: spectral multigroup radiation transport in nonlte; nonstationary, nonlte ionization; sublimation condensation; energy supply (electric power, laser) etc DPP simulation in real geometry LPP Data output: r,z,v,t e,i,ρ,e,b,z,u ω, etc; visualization EMHD or 3D PIC with: ionization of weekly ionized plasma Heat flux postprocessing

EUV Brightness Limit of a Source The intensity upper Planckian limit of a single spherical optically thick plasma source in / =% band around =13.5nm I hc / 7 ( MW / mm sr) 4 hc 9 T T ( ev ) e 1 e Source with pulse duration and repetition rate f yields the time-average radiance L =I ( f) 1 EUV Radiance, MW/mm sr 10 10 1 10 0 10-1 10-10 -3 10-4 tin Z* Scan R=0.04mm R=0.08mm R=0.16mm R=0.31mm R=0.65mm R=1.5mm R=.5mm R=5mm At T ev L 1.1(W/mm sr) (ns) f(khz) 10-5 10-18 10-16 10-14 10-1 10-10 10-8 10-6 10-4 10 - Plasma self-absorption defines the limiting brightness of a single EUV source and required radiance The plasma parameters where EUV radiance is a maximum are not the same as that when the spectral efficiency is a maximum. - the Conversion Efficiency of a single. source decreases if the in-band EUV output increases (at the same operation frequency) Spectral Efficiency (Peuv/Prad) 0.15 0.1 0.05 tin Effective Depth (rho*r), gg/cm3 5 0 10-18 10-16 10-14 10-1 10-10 10-8 10-6 10-4 10 - R=0.04mm R=0.08mm R=0.16mm R=0.31mm R=0.65mm R=1.5mm R=.5mm R=5mm Effective Depth (rho*r), gg/cm5 5

EUV IF Power Limitation: prediction vs. observation Low temperature Xenon plasma EUV emission xenon Xenon plasma parameter scan with Z*-code showing the inband radiance limitation from XeI-XeXI ions Experimental observation of limitation of the inband EUV power at IF from xenon DPP source [M. Yoshioka et al. Alternative Litho. Tech. Proc. of SPIE, vol. 771 77109-1 (009)]

Bright EUV Emission from highly charged xenon ions Tokamak experimental data T Kato et al. J. Phys. B: At. Mol. Opt. Phys. 41 (008) XeXXII - XeXXX produce bright 4f-4d*, 4d-4p*, 5p-4d* [White, O Sulivan] (3d n 4f 1 + 3d n 4p 1 3d n 4d 1 ) satellites in EUV range near 13.5nm XeXXII has ionization potential 619eV (for more details see poster: Vasily S. Zakharov et al) There are two regimes in transparent plasma of xenon: Low - Temperature (LT) with XeXI and High - Temperature (HT) with XeXVII-XeXXX ions contributing into % bandwidth at 13.5nm. For small size xenon plasma, the maximum EUV radiance in the HT can exceed the tin plasma emission 10 xenon EUV Radiance, MW/mm sr 10 1 10 0 10-1 10-10 -3 HT LT Z* Scan R=0.04mm R=0.08mm R=0.16mm R=0.31mm R=0.65mm R=1.5mm R=.5mm R=5mm 10-7 10-6 10-5 10-4 10-3 10-10 -1 10 0 Mass Depth (rho*r), g/cm

LPP Dynamics under CO - laser pulse CO -laser pulse: Pulse energy 00mJ Pulse duration 15ns FWHM Focal spot size 00 m Power, MW 14 1 10 8 6 4 irradiation absorption Loses: reflections and large focal size at initial moment 0-0 -10 0 10 0 30 40 50 60 Time, ns Frame 001 1 Oct ZSTAR - code output, cell values Frame 001 1 Oct ZSTAR - code output, cell values Z(cm) 0.3 0.8 0.6 0.4 0. 0. t= -1.8000E+01 ns laser 40 m tin droplet -0.04-0.0 0 0.0 0.04 R(cm) DENS(g/ccm) 5.5E+00 3.3E+00.0E+00 1.E+00 7.4E-01 4.5E-01.7E-01 1.7E-01 1.0E-01 6.1E-0 3.7E-0.E-0 1.4E-0 8.E-03 5.0E-03 3.0E-03 1.8E-03 1.1E-03 6.7E-04 4.1E-04.5E-04 1.5E-04 9.1E-05 5.5E-05 Z(cm) 0.3 0.8 0.6 0.4 0. 0. t= 1.946E+01 ns plasma mass density -0.04-0.0 0 0.0 0.04 R(cm) DENS(g/ccm) 5.5E+00 3.3E+00.0E+00 1.E+00 7.4E-01 4.5E-01.7E-01 1.7E-01 1.0E-01 6.1E-0 3.7E-0.E-0 1.4E-0 8.E-03 5.0E-03 3.0E-03 1.8E-03 1.1E-03 6.7E-04 4.1E-04.5E-04 1.5E-04 9.1E-05 5.5E-05

5.4E-06 EUV Emission under CO - laser pulse plasma electron density N e Frame 001 1 Oct ZSTAR - code output, cell values Z(cm) t= 1.946E+01 ns 0.3 0.8 0.6 0.4 1.7E-06 5.4E-06 1.7E-06 1.7E-05 5.4E-05 5.4E-05 1.7E-04 1.7E-06 5.4E-05 1.7E-05 5.4E-06 1.7E-06 Ne(Av) 1.7E-03 5.4E-04 1.7E-04 5.4E-05 1.7E-05 5.4E-06 1.7E-06 Power, MW 0.4 0.35 0.3 0.5 0. 0.15 0.1 EUV emission in % @ 13.5nm 0. 0.05 0. -0.04-0.0 0 0.0 0.04 R(cm) 0-0 -10 0 10 0 30 40 50 60 Time, ns Frame 001 1 Oct ZSTAR - code output, cell values Frame 001 1 Oct ZSTAR - code output, cell values 0.3 t= 1.946E+01 ns Te(eV) 0.3 Time-integrated Qeuv(J/ccm) plasma electron temperature T e Z(cm) 0.8 0.6 0.4 0. 0. -0.04-0.0 0 0.0 0.04 R(cm) 8.4E+01 8.1E+01 7.7E+01 7.4E+01 7.0E+01 6.7E+01 6.3E+01 6.0E+01 5.6E+01 5.3E+01 4.9E+01 4.6E+01 4.E+01 3.9E+01 3.5E+01 3.E+01.8E+01.5E+01.1E+01 1.8E+01 1.4E+01 1.1E+01 7.0E+00 3.5E+00 Z(cm) 0.8 0.6 0.4 0. 0. EUV source cross-section -0.04-0.0 0 0.0 0.04 R(cm) 4.0E+04 3.8E+04 3.7E+04 3.5E+04 3.3E+04 3.1E+04 3.0E+04.8E+04.6E+04.4E+04.3E+04.1E+04 1.9E+04 1.7E+04 1.6E+04 1.4E+04 1.E+04 1.0E+04 8.7E+03 7.0E+03 5.E+03 3.5E+03 1.7E+03-1.0E+00

Conversion Efficiency of CO -laser on pulse duration, with & w/out pre-pulse pulse Main pulse: CO -laser 0. J/pulse, 15, 30 and 50ns fwhm, 00 m focal spot size Pre-pulse laser (if applied): Nd:YAG 5 mj/pulse, 10ns fwhm, 40 m spot size Target: 40 m diameter tin droplet (0 m for 100mJ laser) Calculated EUV brightness is up to 4 W/mm sr khz Conversion Efficiency, % 3.5 1.5 1 0.5 00mJ w/out pre-pulse 00mJ with 5mJ pre-pulse 100mJ with pre-pulse (EUVA) Z* Scan 0 0 10 0 30 40 50 60 Pulse duration, ns

Capillary Discharge EUV Source resistive regime discharge current, ka Inductive regime 4 I, ka 3 1 0-1 - -3 19kV charge -4 1. nf capacitor -5-6 0 5 10 15 0 5 30 35 40 time, ns Discharge current, ka 1 0-1 - -3-4 Resistive regime 3kV charge 1.9 nf capacitor -5 0 0 40 60 80 100 Time, ns In a resistive regime of capillary discharge, the high joule dissipation in the tight conductive channel produced by hollow cathode electron beam creates an efficient mechanism of plasma heating and EUV or soft X-ray emission consequently. Also, fast electrons increase the ionization degree of heavy ion (Xe, ) plasma increasing eo ipso EUV yield.

Capillary Discharge EUV Source dynamics & EUV emission Frame 001 1 Oct ZSTAR - code output, cel Z(cm).4 Anode Ne(Av). 1.8 1.6 1.4 1. 1 0.8 0.6 0.4 t= 3.3114E+01 ns capillary 1.0E-07 8.E-08 6.7E-08 5.5E-08 4.5E-08 3.7E-08 3.0E-08.5E-08.0E-08 1.6E-08 1.4E-08 1.1E-08 9.0E-09 7.4E-09 6.1E-09 5.0E-09 4.1E-09 3.3E-09.7E-09.E-09 1.8E-09 1.5E-09 Cathode 1.E-09 1.0E-09 0 0.5 R(cm) 3D volumetric compression capillary Power, MW 0.05 0.04 0.03 0.0 0.01 0 0 0 40 60 80 100 Time, ns At EUV emission maximum: N e =-3 10 16 cm -3, T e =5-40eV. EUV emission in % @ 13.5nm 496mJ stored energy Calculated EUV brightness is up to 10 W/mm sr khz Frame 001 13 Oct ZSTAR - code output, cel Z(cm).4 Anode Qeuv(J/ccm). 1.8 1.6 1.4 1. 1 0.8 0.6 0.4 Time-integrated capillary 1.0E+00 9.7E-01 9.4E-01 9.1E-01 8.8E-01 8.5E-01 8.E-01 7.9E-01 7.6E-01 7.3E-01 7.0E-01 6.7E-01 6.3E-01 6.0E-01 5.7E-01 5.4E-01 5.1E-01 4.8E-01 4.5E-01 4.E-01 3.9E-01 3.6E-01 Cathode 3.3E-01 3.0E-01 0 0.5 R(cm) capillary EUV source cross-section

Gen II EUV Source - characteristics & optimization from Z* Z modelling In-band EUV energy per shot, uj 1000 800 600 400 00 885 J/shot 496mJ stored energy 0 0 5 10 15 0 5 30 Pressure, a.u. EUV source scan by stored electrical energy Optimization by gas mixture pressure In-band EUV energy per shot, uj 1000 800 600 400 00 Energy scan calculated (in % band) 0 00 50 300 350 400 450 500 550 600 Stored energy, mj

Multiplexing - a solution for high power & brightness Small size sources, with low enough etendue E 1 =A s << 1 mm sr can be multiplexed. The EUV power of multiplexed N sources is P EUV E N The EUV source power meeting the etendue requirements increases as N 1/ This allows efficient re-packing of radiators from 1 into N separate smaller volumes without losses in EUV power f EUV Radiance, MW/mm sr 10 10 1 10 0 10-1 10-10 -3 10-4 10-5 tin Z* Scan 10-9 10-7 10-5 10-3 10-1 Mass Depth (rho*r), g/cm R=0.04mm R=0.08mm R=0.16mm R=0.31mm R=0.65mm R=1.5mm R=.5mm R=5mm Spatial-temporal multiplexing: The average brightness of a source and output power can be increased by means of spatial-temporal multiplexing with active optics system, totallizing sequentially the EUV outputs from multiple sources in the same beam direction without extension of the etendue or collection solid angle

MPP source for soft x-ray x microscopy Nitrogen plasma at emission maximum Frame 001 13 Aug ZSTAR - code output, cell values Time integrated image of soft x-ray (400-600eV) source Frame 001 13 Aug ZSTAR - code output, cell values Z*-code modelling Discharge current and soft x-ray pulse t= 1.9037E+01 ns anode Ne(Av) time integrated anode Z(cm) 1.5 1 0.5 capillary capillary cathode -0. 0 0. R(cm) 3.6E-07 3.4E-07 3.3E-07 3.1E-07 3.0E-07.8E-07.7E-07.5E-07.3E-07.E-07.0E-07 1.9E-07 1.7E-07 1.6E-07 1.4E-07 1.3E-07 1.1E-07 9.4E-08 7.8E-08 6.3E-08 4.7E-08 3.1E-08 1.6E-08 0.48J/pulse charge Fast electrons induced discharge in 3-D volumetric compression regime Z(cm) 1.5 1 0.5 capillary capillary cathode -0. 0 0. R(cm) Qww(J/ccm) 0.55 0.5 0.48 0.45 0.4 0.38 0.35 0.3 0.8 0.5 0. 0.18 0.15 0.1 0.08 0.05 <Z> 5 T e = 45-55eV N e 10 17 cm -3 Nitrogen: He-like and H-like 0.48J/pulse charge

Acknowledgement R&D team & collaborators R&D team of EPPRA and Nano UV Pontificia Universidad Catolica de Chile RRC Kurchatov Institute, Moscow, Russia Keldysh Institute of Applied Mathematics RAS, Moscow, Russia University College Dublin King s College London EUVA, Manda Hiratsuka, Japan Sponsors - EU & French Government ANR EUVIL FP7 IAPP OSEO ANVAR RAKIA COST