High Brightness EUV Light Source for Actinic Inspection & Microscopy P. Choi, V.S. Zakharov, S.V. Zakharov, R. Aliaga-Rossel, A. Bakouboula, O. Benali, P. Bove, M. Cau, G. Duffy, O. Iwase, B. Lebert, O. Sarroukh, C. Zaepffel Nano-UV EPPRA
EUV for EUV Lithography Diffraction restricts the resolution r k1 NA 13.5nm (h =92eV) 6.Xnm? / 2% NOW EUV for HVM beyond 16 nm For HVM: > 2 W of in-band power @ IF within < 3mm 2 sr etendue For mask inspections ABI AIMS APMI : 3 >1 W/mm 2 sr within etendue of 4 1-3 5 1-4 1.5 1-2 mm 2 sr COPIRIGHT, NANO-UV LPP & DPP can produce Sn, Xe plasma radiating at EUV range EUV sources are still the main issue of EUVL deployment 2
i-socomo - GEN II cell Cathode chamber + shielding shell + gas distribution + air cooling Anode chamber + water cooled structure Plasma expansion chamber - water cooled collimator structure COPIRIGHT, NANO-UV Physical Dimensions: Source : 15 mm diameter, 52 mm length, 7 kg Instrument rack : 13 x 6 x 8 mm, 2 kg Utility requirements: Electrical : 2-24V, 2Ø, 5/6 Hz, 16A Cooling : Water cooled (2 litres per minute, 15 C - 25 C inlet) He, N 2 and Xe : 3 bar inlet 3
MPP Discharge Experiment - plasma discharge emission from a channel produced by hollow cathode electrons Intensity (arb. units) COPIRIGHT, NANO-UV optical streak photograph pulse charged local energy storage sub-mm diameter capillary t hollow cathode e-beam for onaxis discharge initiation rapid current heating - 1st EUVL Symposium, Dallas 22 - ultra-bright high energy density radiator 5 1 15 2 25 Wavelength (nm) o.1 o.2 o.3 o.4 5 45 4 35 3 25 2 15 1 5 pressure (mbar) 4
Photodiode signal (mv) Photodiode signal (mv) Nano-UV: EUV Source micro - pulsed plasma MPP Performance @ 21kV with SXUV2 A Mo/Si (35/5 nm) filtered diode from IRD in 3 nm EUV band (12.4 nm -15.4 nm) Al coated (11 nm) on Si 3 N 4 (25 nm) to reject OoB 2µm pinhole aperture in front of the diode typical etendue < 1-3 mm 2.sr Discharge in He/N 2 /Xe admixture, total Flow 3.2 sccm/min Cell capacity 1.7nF The low charge energy resolves heat-loading issues 2 15 1 5 Profil@74cm (21kV1mtorr ) Gauss fit of A74cm_Maxpulse 5 1 15 2 25 3 35 4 45 5 55 Distance (mm) Scanned signal profile @ 74cm COPIRIGHT, NANO-UV Data: A74cm_Maxpulse Model: Gauss Chi^2/DoF = 16.7688 R^2 =.92955 y 8.65922 ±2.19153 xc 3.3587 ±.22859 w 9.72997 ±.53783 A 1291.53952 ±77.2276 6 5 4 3 2 1 Maxpulse B 2 25 3 35 4 45 5 55 6 65 7 75 8 Distance (mm) @ 98cm Data: Data3_Maxpulse Model: Gauss Chi^2/DoF = 7.33844 R^2 =.96391 y 3.35674 ±.74899 xc 47.7185 ±.2948 w 15.7751 ±.71427 A 723.19786 ±38.68627 Distance source to diode (cm) 74 98 Irrandiance @ 1kHz Ph/cm 2 /s 8.2e17 1.8e17 Beam HWHM (mm) 6.13 9.65 Radiation solid angle = 2* (1-cos )= 6e-4 sr Radiation half angle divergence (deg).8 Estimated in-band brightness is of 31 W/mm 2 sr per khz 5
Source Characteristics - measurement schematics Set up Cell Aperture : 2 mm + grid Filtered Photodiode Pinhole : 5 µm CCD Camera 17 cm 49 cm 56-98 cm 62 cm 68 cm 8 cm 14 cm Aperture 8 mm Aperture 2 mm Pinhole scan time averaged source diameter; size & stability angular emission properties source etendue.5.45.4.35.3.25.2.15.1.5 COPIRIGHT, NANO-UV EUV filter Phystex SPF 1 2 3 4 Photodiode scan filtered (Mo35nm/Si5nm) SXUV_2A diode with 3 nm band (12.5-15.4 nm) with Al coated Si 3 N 4 to reject Oob CCD with Spectral Purity Filter (SPF) or Al coated Si 3 N 4 filter scan diode to get radiation profile and power delivered fold with pinhole scan source image data to get radiant brightness 6
Photodiode signal (V) Output power @ 3 nm bandwidth (W) Irrandiance E17 ph/cm2/s Photodiode signal (mv) Source Characteristics I - irradiance & power vs stored energy Discharge Voltage 3 25 2 Profil@74cm (22.6kV1mtorr ) Gauss fit of A74cm_Maxpulse Data: A74cm_Maxpulse Model: Gauss Chi^2/DoF = 99.6118 R^2 =.97639 At 74 cm, 22.6 kv, 45mJ, 1 khz, (3nm EUV band): EUV diode 15 1 5 y 1.79845 ±1.99588 xc 28.2894 ±.1214 w 9.25 ±.27894 A 298.37622 ±68.43663 Peak irradiance 1.19 E18 ph/cm 2 /s Sigma: 4.1 mm 5 1 15 2 25 3 35 4 45 5 55 Distance (mm) Power: 18.5W (3nm band).35.3.25.2 23.5kV 23.2kV 22.7kV 21.5V 2.8kV 19.5kV 3 25 2 Power W Linear Fit of Data1_W 25 2 15 Irradiance Linear Fit of Data1_phcm2s.15.1.5. -1-5 5 1 15 2 25 Time (ns) Photodiode pulse over 16 shots COPIRIGHT, NANO-UV 15 1 5 35 4 45 5 Stored energy (mj) 3nm EUV band power versus stored energy 1 5 3 35 4 45 5 55 Stored energy (mj) Irradiance versus stored energy Output power and irradiance increase with increasing stored energy 7
Source Characteristics higher resolution source projection Pinhole scan EUV SPF filter, F4 mesh grid over SEA (2mm) - far field image showing collective features The measured source size is less than 18um Pseudo colour COPIRIGHT, NANO-UV pinhole-scan image profile - 5 m pinhole,.5 mm scan step, 5s exposure, 2x2 bin on CCD, 1 khz EUV pulses, image sensor to source 14 cm, untreated raw data 8
COPIRIGHT, NANO-UV Source Characteristics II - wavefront measurement HASO X-EUV Shack Hartmann wavefront sensor - (from Imagine Optic) EUV source HASO 189 mm EUV beam diameter d= 9.75 mm at 189 mm from source Beam divergence half angle =.19 Acquired image 6s exposure, source at 1 khz Derived wavefront 166 nm RMS (12 ) & 76nm PV (58 ) Solid angle =.345 msr Etendue E = 5 1-5 mm 2 sr * With support of G. Dovillaire, E. Lavergne from Imagine Optic and P. Mercere, M.Idir from SOLEIL Synchrotron 9
Photodiode signal (mv) Photodiode signal (mv) Photodiode signal (mv) Source Structure Tuning - different cathode materials Measured Parameters SXUV2 A Mo/Si (35/5 nm) filtered diode from IRD, 3 nm EUV band (12.4 nm - 15.4 nm), Al coated (11 nm) on Si 3 N 4 (25 nm) to reject OoB, typical etendue 1.7 E-2 mm 2.sr, discharge in He/N 2 /Xe admixture with a total Flow 3.2 sccm/min, Cell capacity 1.7nF, Stored energy 44mJ. 2 15 1 5 Al -alloy cathode Profil@74cm (22.3kV1mtorr ) Gauss fit of A74cm_Maxpulse Data: A74cm_Maxpulse Model: Gauss Chi^2/DoF = 35.28792 R^2 =.98441 y 8.23923 ±1.21749 xc 29.3458 ±.1429 w 9.85236 ±.24383 A 1658.3417 ±44.687 2 15 1 5 SS cathode Profil@74cm (22.3kV1mtorr ) Gauss fit of A74cm_Maxpulse Data: A74cm_Maxpulse Model: Gauss Chi^2/DoF = 3.88935 R^2 =.98229 y 7.15124 ±1.23586 xc 29.8646 ±.12177 w 11.2412 ±.29732 A 1611.36277 ±47.69539 3 25 2 15 1 5 Sn-alloy cathode Profil@74cm (22.3kV1mtorr ) Gauss fit of A74cm_Maxpulse Data: A74cm_Maxpulse Model: Gauss Chi^2/DoF = 165.91928 R^2 =.9662 y 9.6813 ±2.52485 xc 28.73634 ±.157 w 9.1689 ±.35898 A 291.24876 ±87.41433 5 1 15 2 25 3 35 4 45 5 55 Distance (mm) irradiance at 74cm, 1mtorr and 22.3kV- 7.4e17 ph/cm 2 /s at 1 khz (3nm EUV band) Power= 13.7W Sigma= 4.92mm COPIRIGHT, NANO-UV 5 1 15 2 25 3 35 4 45 5 55 Distance (mm) irradiance at 74cm, 1mtorr and 22.3kV- 6.9e17 ph/cm 2 /s at 1 khz (3nm EUV band) Power= 16.3W Sigma= 5.6mm 5 1 15 2 25 3 35 4 45 5 55 Distance (mm) irradiance at 74cm, 1mtorr and 22.3kV- 1.1e18 ph/cm 2 /s at 1 khz (3nm EUV band) Power= 18W Sigma= 4.5mm Sn alloy cathode improves radiation output 1
Irrandiance E17 ph/cm2/s Irrandiance E17 ph/cm2/s Photodiode signal (V) Photodiode signal (V) Tin addition to the gas admixture - different Tin alloy cathode Voltage scan using Sn-alloy cathode 1 Voltage scan using Sn-alloy cathode 2 higher Sn content.35.3.25.2.15.1.5. 25 2-1 -5 5 1 15 2 25 Time (ns) 23.5kV 23.2kV 22.7kV 21.5V 2.8kV 19.5kV Irradiance Linear Fit of Data1_phcm2s.4.35.3.25.2.15.1.5. 25 2 23.8kV 23.3kV 23kV 22kV 21.6kV 2.1kV -1-5 5 1 15 2 25 Time (ns) Irradiance Linear Fit of Data1_phcm2s 15 15 COPIRIGHT, NANO-UV 1 1 5 5 3 35 4 45 5 55 3 35 4 45 Stored energy (mj) Stored energy (mj) 5 55 At high energy, radiation output > 1.25x using Sn alloy 2 compared to Sn alloy 1 Need to assess life time issues 11
Irradiance at the signal peak (x 1e17 ph/cm2/s) Irrandiance E17 ph/cm2/s Photodiode signal (V) Photodiode signal (V) Progress in experiment Results presented at EUVL october 21.35 - irradiance vs stored energy Current Results 2.5 2. 1.5 19.9kV 2.5kV 21.3kV 22kV 22.6kV 23.1kV.3.25.2 23.5kV 23.2kV 22.7kV 21.5V 2.8kV 19.5kV 1..15.1.5.5.. -2 2 4 6 8 1 Time (ns) 8 7 6 5 4 3 2 1.36.38.4.42.44.46.48.5.52 Stored energy (J) 25 2 15 1 5-1 -5 5 1 15 2 25 Time (ns) Irradiance Linear Fit of Data1_phcm2s 3 35 4 45 5 55 Stored energy (mj) At same operating voltage by optimisations made on the fuel gas mix and flow rate 2 fold increase in the irradiance 3 fold increase on power COPIRIGHT, NANO-UV Scaling to higher power demonstrated with Sn admixture 12
In-band EUV energy per shot, uj In-band EUV energy per shot, uj Gen II EUV Source - characteristics & optimization from Z* modelling 1 8 6 4 2 885 J/shot 496mJ stored energy Optimization by gas mixture pressure 5 1 15 2 25 3 Pressure, a.u. 1 Resistive regime COPIRIGHT, NANO-UV EUV source scan by stored electrical energy for more details, at theoretical talk (S44): S.V.Zakharov et al 8 6 4 2 Energy scan calculated (in 2% band) 2 25 3 35 4 45 5 55 6 Stored energy, mj 13
CYCLOPS - AIMS Aerial Image Microscope System (AIMS) tool source Design Specifications - high brightness with small etendue 1 W/mm 2.sr in-band 2% EUV radiant brightness 5mW within etendue - 5 1-4 mm 2.sr IF source area < 9 mm 2 optimized for aerial image measurements i-socomo unit, 5 khz working energy stability < 1% no debris / membrane filter Current Status system characterization stability optimization life time components testing COPIRIGHT, NANO-UV 14
EUV Radiance, MW/mm2 sr Multiplexing - a solution for high power & brightness Small size sources, with low enough etendue E 1 =A s << 1 mm 2 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 1/2 This allows efficient re-packing of radiators from 1 into N separate smaller volumes without losses in EUV power f 1 2 1 1 1 1-1 1-2 1-3 1-4 1-5 tin Z* Scan 1-9 1-7 1-5 1-3 1-1 Mass Depth (rho*r), g/cm2 R=.4mm R=.8mm R=.16mm R=.31mm R=.625mm R=1.25mm R=2.5mm 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 COPIRIGHT, NANO-UV - compact physical size of SoCoMo is required 15
HYDRA 4 -ABI - spatial multiplexing for blank inspection Actinic Blank Inspection (ABI) tool source Design Specifications 6 W/mm 2.sr in-band 2% EUV brightness.6 W at the IF effective etendue 1-2 mm 2.sr source area - 31 mm 2 / TBD optimized for mask blank inspection 4x i-socomo units working at 3 khz each no debris / membrane filter close packed pupil fill Current Status 4 units integration & characterization single unit optimization ML mirrors evaluation & modelling COPIRIGHT, NANO-UV Z= 7 mm 25 mm Z= mm @ Cross Over Z= 5 mm All 4 sources aligned to a point without use of any solid optical collector 16
COPIRIGHT, NANO-UV HYDRA 4 -ABI - spatial multiplexing 4 cells operating @ 1 KHz @ 22 KV Cells capacity : 1.2nF each Operating Pressure ; 3mTorr Profile scans (3nm EUV band) @ 7 cm perpendicular to the optical beam axis Summation of 4 single Beams 4 Beams simultaneous 9.6 1 13 ph/pulse 1.4mJ/pulse 1.4 W @ 1 KHz 17
y(sig).98.981.984.985.986.987.988.99.993.994.995.992.991.99.987.986.985.983.981 y(sig).9988 HYDRA 4 -ABI - 4-beams flatness optimization Overlaping of 4 suitably appertured Gaussian beam at a given flatness of.2% Frame 1 9 Aug 21 Z-ray - code output, cell values Frame 1 9 Aug 21 Z-ray - code output, cell values 1 a= 1.18E+ s= 1.3924E+ 1 a= 1.18E+ s= 1.3924E+.8.6.4.2 -.2 -.4 -.6 -.8.983.982.983.981.986.988.982.989.991.989.992.98.98.994.993.987.985.984.992.997.996.995.99.997.984.998.985.987.991.993.989.984.981.996.99.996.988.98.986.982.983.983.986.993.997.988.994.99.995.998.998.982.989.991.997.992.98.995.992.987.998.994.984.981.985.991.997.985.987.996.995.996 2% -1-1 -.8 -.6 -.4 -.2.2.4.6.8 1 x(sig).994.993.989.984.981.99.993.988.988.989.986.984.982.98.982.983.98 f 1.998.997.996.995.994.993.992.991.99.989.988.987.986.985.984.983.982.981 An efficiency with flatness of.2% is of 22%..8.6.4.2 -.2 -.4 -.6 -.8.9982.9986.9984.998.9988.9982 4 2.9988 2 8 6.998 6 2.9988.9984 4.9986.9982.9984 4.9986.9984.9986 6.9988.9982 6 8 2 8-1 -1 -.8 -.6 -.4 -.2.2.4.6.8 1 x(sig).998.2%.9984.9986 4.998.9982 22.9988 f 1 8 6 4 2.9988.9986.9984.9982 COPIRIGHT, NANO-UV 18
HYDRA-APMI - unique temporal & spatial multiplexing Actinic Patterned Mask Inspection (APMI) tool source Design Specifications 6-12 W/mm 2.sr in-band EUV brightness.6-1.2 W at the IF etendue 1-2 mm 2.sr IF source area - 2 mm 2 optimized for patterned mask inspection 4-8x i-socomo units working at 3 khz each 12-24 khz temporally multiplexed no debris / membrane filter Gaussian output spot Current Status optics design & modelling single unit optimization mechanical design COPIRIGHT, NANO-UV 19
Multiplexing - Spatial & Temporal Temporal Multiplexing Technically NOT challenging - needs development COPIRIGHT, NANO-UV 2
COPIRIGHT, NANO-UV Acknowledgements Collaborators Pontificia Universidad Catolica de Chile NRC Kurchatov Institute, Moscow, Russia Keldysh Institute of Applied Mathematics RAS, Moscow, Russia University College King s College London Sponsors - EU & French Government FP7 IAPP OSEO-ANVAR Investor - RAKIA 21