Pulsed-power based bright EUV light source for metrology Sergey V. Zakharov NaextStream sas, Buc, France sergey.zakharov@naextstream.com + also with NRC Kurchatov Institute, Moscow, Russia 1
Sources for EUV & Beyond Lithography Diffraction restricts the resolution r k1 NA 13.5nm 6.Xnm (h=9ev 185eV) / % NOW EUV for HVM beyond 16 nm The optics is made of multi-layer mirrors with reflection efficiency ~7% For HVM: >> W of in-band power at IF within < 3mm sr etendue For mask inspections ABIAIMSAPMI : 3 >1 W/mm sr Sn (4d-4f), Xe (5p-4d) High Energy Density plasma (T e =-4eV) radiates in EUV range LPP & DPP
ZETA Z * RMHD ZENITH Code multi-physics model TABLES: nonlte atomic & spectral data for materials and mixtures (Te,ρ,U) Atomic kinetics: ion level population (including inverse), chemical reactions Spectral postprocessing 3D PIC: gas ionization, weekly ionized plasma, discharge triggering RMHD ( D, 3D ) with: spectral multigroup radiation transport in nonlte; nonstationary, nonlte ionization; sublimation condensation; etc DPP, LPP, LADPP etc Plasma simulation in real geometry Data output: r,z,v,t e,i,ρ,e,b,z,u ω, etc; visualization Energy source: radiation, laser, electric circuit, energy storage line, chemical, nuclear, heat flux etc Heat flux postprocessing 3
Hollow cathode capillary discharge EUV sources Plasma gun CATHODE capillary insulator Energy storage capacitor Voltage monitor Current monitor XRD spectrometer slit-wire camera ANODE pulse charged local energy storage sub-mm diameter capillary hollow cathode e-beam for onaxis discharge initiation rapid current heating small high energy density radiation emitter Original EPPRA design low inductance solid insulator fast pulse high photon collection efficiency PUC design low inductance water: insulator & cooling agent medium pulse high CE~1.6% in Xe lower frequency operation NanoUV design high inductance capacitor array slow pulse low instant power
Bright EUV plasma source pulsed-power capillary discharge Pulsed-power Energy storage line 1 5 J Liquid dielectric & coolant Voltage -3 kv Current 1 - ka Pulse ~15-3 ns 1.6-3. mm L = 1-18 mm Capillary dimension Energy storage line Experimental set up capillary EUV, soft-x Operation frequency 1-6 khz Gas:.1-4 Torr gradients He; Xe, N, Ar, Kr,, admixtures (for narrow-band radiation source) Capillary discharge dynamics & emission features: E-beam, plasma channelling (>>1) Example of central part of the simulated geometry Volumetric MHD compression (skin depth >>plasma diameter) Highly ionized ions (fast electrons) 5
capillary capillary Hollow-cathode Capillary Discharge triggering by fast electrons Anode modelling together with KIAM RAS Electron beam in the HC capillary discharge optical streak photograph run-away electrons electric field drops deeper into HC e-beam concentration (ɛ >>1) e-beam-gas ionization Hollow cathode ionization wave EPPRA, EUVL Symposium, In the first few nanoseconds, run-away electrons from the hollow cathode generate a tight ionized channel (< m diameter) in the gas 6
In-band Emission, mj/pulse Capillary Discharge EUV Source modelling source optimization Discharge current, ka 1 8 6 energy storage 4.9J/pulse energy storage.7j/pulse Electric current through discharge at optimums 4 1 1 1 Gas Pressure, a.u. Optimization by gas mixture pressure 15 1 5-5 -1-15 - 3776 37478 3768 3788 3884 3886 38488 3869 388 Time, ns 7
Z(cm) capillary capillary EUV Emission, MW Z(cm) capillary capillary - code output, cell values 7 6.5 6 5.5 Capillary Discharge EUV Source dynamics & EUV emission t= 3.749E+3 ns -.4 -...4 R(cm) 3D volumetric compression Ne(Av) 5.E-5 3.7E-5.74E-5.3E-5 1.5E-5 1.11E-5 8.5E-6 6.11E-6 4.5E-6 3.35E-6.48E-6 1.84E-6 1.36E-6 1.1E-6 7.46E-7 5.53E-7 4.9E-7 3.3E-7.4E-7 1.66E-7 1.3E-7 9.1E-8 6.75E-8 5.E-8.45.4.35.3.5..15.1.5 The traced along the axis, EUV intensity in % band at 13.5nm wavelength 6 W/mm sr per khz N e =1-1.5 1 18 cm -3, T e =5-4eV. in % @ =13.5nm 37 37 374 376 378 38 38 Time, ns Calculated in-band EUV emission 7.6 W/kHz in Frame 1 31 Oct 13 ZSTAR - code output, cell values 7 6.5 6 5.5 time-integrated -.4 -...4 R(cm) EUV source crosssection Source diameter.16mm Qinband(J/ccm) 8. 76.5 73.4 69.57 66.9 6.61 59.13 55.65 5.17 48.7 45. 41.74 38.6 34.78 31.3 7.83 4.35.87 17.39 13.91 1.43 6.96 3.48. 8
Further optimization of the source switching from inductive to resistive regime discharge current, ka Discharge current, ka Inductive regime Resistive regime 4 3 1-1 I, ka Nitrogen as buffer gas 1-1 - -3-4 -5 - -3-4 -6 5 1 15 5 3 35 4 time, ns -5 4 6 8 1 Time, ns In the 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. Also, fast electrons increase the ionization degree of heavy ions (Xe, ) plasma increasing eo ipso EUV yield. 9
Example of double unit EUV source for ABI In-band brightness: 8 W/mm.sr Etendue: 4.1-3 mm.sr In-band power at IF:.4W Efficiency 65% 3.5% ~6mW filtered ~6mW Efficiency 5% 1
Spatial mutiplexing - static combination of beams into one beam Etendue of a single source is E 1 S 4 IN FAR-FIELD the etendue of equivalent sources is E FF S 4 (+) 4 E 1 IN NEAR-FIELD the declination due to can be corrected and the etendue of equivalent sources is E NF S E 4 1 Brightness may slightly decrease due to additional reflection Power increases 1.5 - times Source S1 S1+S (source image) + EUV Facet mirror Source S 11
Sources for AIMS or APMI AIMS source requirements 3-1 W/mm.sr in-band Etendue 5.1-4 mm.sr EUV In-band power at IF 15-5 mw - Proposal 1 source APMI source requirements In-band brightness : 4-8 W/mm.sr Etendue: 1.5.1- mm.sr In-band power at IF:.6-1. W Operation frequency >1kHz - Proposal 4 sources temporally multiplexed Averaged brightness increases 3-4 times Averaged power increases 3-4 times (grazing incident optics or ML mirror optics) 5 mm 1
radial distance (mm) EUV band(zr filter)axuv signal (mv) Focusing effect observation 3 1 e n 1 f1( ) 75cm Source EPPRA measurements n =1-n<<1; n ~.1.5 (in solid matter) and n =.. (in plasma) for EUV range How it is possible in geometrical optics? Know - How 5 15 1 5-8 -6-4 - 4 6 8 radial distance (mm) Scanned signal profile Data: 13 mm Model: Lorentz Chi^/DoF = 366. R^ =.99 y -8.4 ±17.95 xc -.5 ±. w 1.93 ±.8 A 6711.4 ±34.59 EUV band (Zr filter) radiation beam profile at 13mm from collimator exit 4 3 1 HWHM angle = tan -1 (1.8/4) =.6 degree solid angle = 6.36 e-5 steradian measured half width Linear fit of Data 1 3 4 5 6 axial distance from end of collimator (mm) 13
rk Wave-guiding refractive structure dr/dz n Focussing : d dl N n sin( ) dr n ( r ) n ( r ) dl e-beam Refractive Structure: e-beam generates plasma-acoustic waves, k r -1 D 16 14 1 1 8 6 4 Trajectories Trajectories 51155335 zk ( z) r.5 k.15.1.5 -.5 -.1 -.15 refractions are required light trajectory equation k n 1.5 n k resonator r z dz tg(angle) tg(angle) analytical numerical -. 51155335 zk 14
Source for soft X-ray microscopy deep penetration & high contrast Water Window Soft X-ray Soft X-ray microscopes and their biological applications Janos Kirz, Chris Jacobsen & Malcolm Howells - Q. Rev. Biophys. 8, 33{13 (1995) N, Kr, Zr, Bi, High Energy Density plasma (T e =8-eV) radiates in WW range Table-top water window transmission x-ray microscopy: Review of the key issues, and conceptual design of an instrument for biology. Jean-François Adam and Jean-Pierre Moya, Jean Susini - Rev. Sci. Instrum. 76, 9131 5 poster: Vassily Zakharov "Radiative Properties of Krypton Plasma & Emission of Krypton DPP Source in Water-Window Spectral Range" 15
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