Laser system for LPP EUV light source T.Ohta*, K.Nowak*, - PowerPoint PPT Presentation

Confidential Improving efficiency of pulsed CO 2 Laser system for LPP EUV light source T.Ohta*, K.Nowak*, T.Suganuma*, T.Yokotsuka*, K.Fujitaka*, M.Moriya*, A.Kurosu*, A.Sumitani**, J.Fujimoto*** and H.Mizoguchi*** * KOMATSU ** KOMATSU/EUVA *** Gigaphoton 2010 International symposium on Extreme Ultraviolet Lithography October 17-20, 2010 – Kobe, Japan

Abstract Laser Produced Plasma (LPP) EUV light source system has been developed for EUV lithography. For this LPP EUV light source system, high pow er pulsed CO 2 laser is required as a main drive laser. Current approach for this application is a MOPA system based on a small average pow er pulsed master oscillator and a chain of pow er amplifiers. The current MOPA system cannot provide more than 25% overall operation efficiency. The main reason is an insufficient pow er level at initial amplifier stages. In this presentation, some of the pressing technical challenges of the LPP laser driver, such as efficiency and stability of operation, are show n. A new master oscillator system and a pre-amplifier system based on a novel configuration of a RF-excited CO 2 laser are the key to high efficiency. Higher energy efficiency and multi-kW output from low input pow er level are predicted and verified in our experimental pre-amplifier. Feasibility of over 15kW CO 2 laser system is show n by numerical modeling. 2010 International Symposium on Extreme Ultraviolet Lithography October 17-20, 2010 – Kobe, Japan P2

OUTLINE � LPP EUV light source � CO 2 laser system � High-quality 20kW CO 2 laser system � Current status of multi-kW CO 2 � Multi-line amplification for higher efficiency � Initial performance � Multi-line oscillator � High efficiency Pre-Amplifier � Main Amplifier � Summary 2010 International Symposium on Extreme Ultraviolet Lithography October 17-20, 2010 – Kobe, Japan P3

LPP EUV light source Sn supply Plasma guiding magnet Beam transfer EUV source Scanner system Intermediate Plasma Focus EUV collector High power pulsed CO 2 laser 2010 International Symposium on Extreme Ultraviolet Lithography October 17-20, 2010 – Kobe, Japan P4

EUV light generation process Neutral Droplet Small fragments Plasma Guided ion • scattered by ion • Charge exchange (liquid) (liquid) (gas) EUV light Main-pulse Pre-pulse CO 2 laser Ions with low energy Neutrals tapped by Vaporization High power trapped by B field charge exchange with CO 2 laser irradiation High beam quality ions Ionization 2010 International Symposium on Extreme Ultraviolet Lithography October 17-20, 2010 – Kobe, Japan P5 Atom 0

CO 2 laser system � High pow er pulsed CO 2 laser � Combination of short pulsed high rep. rate Osc. and Industrial RF-excited CO 2 laser. Main amplifier Pre- Main Main OSC Amplifier AMP1 AMP2 20 kW 3 kW 150 W (1.5mJ at 100kHz) (30mJ at 100kHz) (200mJ at 100kHz) 2010 International Symposium on Extreme Ultraviolet Lithography October 17-20, 2010 – Kobe, Japan P6

CO 2 laser system 2010 International Symposium on Extreme Ultraviolet Lithography October 17-20, 2010 – Kobe, Japan P7

Current status of multi-kW CO 2 ： Laser Power 13 kW @ 30% duty ： Pulse Width 20 ns ： Repetition Rate 100 kHz Beam quality : M2 <1.2 ■ Laser System 13 kW 3 kW EUV100 W 60W at I/F equivalent Oscillator Wave length: 10.6um Main-Amplifier Pre-Amplifier Rep. rate :100kHz RF-excited CO 2 laser RF-excited CO 2 laser Pulse width :20 ns (FWHM) Laser beam profile 2010 International Symposium on Extreme Ultraviolet Lithography October 17-20, 2010 – Kobe, Japan P8

Current status of multi-kW CO 2 � Pulse shape and beam profile of current system Temporal pulse shape Laser beam profile 0 . 9 0 . 8 0 . 7 0 . 6 y t i 0 . 5 s n e t 0 . 4 n I 0 . 3 0 . 2 0 . 1 0 T i m e 5 0 n s / d i v . Pulse duration : 20 ns (FWHM) Pedestal component : <10% 2010 International Symposium on Extreme Ultraviolet Lithography October 17-20, 2010 – Kobe, Japan P9

Multi-line amplification for higher efficiency � Efficiency of Multi-line amplification Energy extraction � prediction of 1.3 times higher than Single-line � Single line Single-line Amplification Rotation level of CO2 Extraction efficiency Extraction efficiency Low CO 2 Amplifier � Multi-line Multi-line Amplification High This work was preformed by Research Institute for Laser Physics, St. Petersburg, Russia [V.E. Sherstobitov et al] CO 2 Amplifier Multi-line input 2010 International Symposium on Extreme Ultraviolet Lithography October 17-20, 2010 – Kobe, Japan P10

Multi-line Master Oscillator Multi-wavelength seeded oscillator Seeder Amplifier λ 1 =Px1 λ 2 =Px2 (more planned) High output beam quality M 2 <1.3 (Far-field beam profile) Px1 Px2 2010 International Symposium on Extreme Ultraviolet Lithography October 17-20, 2010 – Kobe, Japan P11

Multi-line Master Oscillator � Energy stability � High pulse energy stability Repetition rate : 100kHz Closed loop operation 1.2 1.15 P.Energy 1.1 Pulse energy [A.U.] 1.05 1 0.95 σ=0.56% 0.9 0.85 0.8 0 10000 20000 30000 40000 50000 (3.5Mpulses) 500msec Pulse number 2010 International Symposium on Extreme Ultraviolet Lithography October 17-20, 2010 – Kobe, Japan P12

High efficient Pre-Amplifier � Efficient pre-amplification – simulation results Pre-amplifier 150W >3kW Input beam Gaussian (M 2 =1), 16mm 1/e2 diameter � >3kW output achieved at 150W input pow er Good beam quality M 2 < � 2 at multi-kW level Compact size � � Improved efficiency 2010 International Symposium on Extreme Ultraviolet Lithography October 17-20, 2010 – Kobe, Japan P13

Main Amplifier � Main amplifier characteristics – simulation � Good performance at 20kW average pow er predicted � Beam tilts and offset typical for good alignment 2010 International Symposium on Extreme Ultraviolet Lithography October 17-20, 2010 – Kobe, Japan P14

Main Amplifier � Main amplifier characteristics : experimental results � >9kW output achieved at 3kW input pow er � Good beam quality Output Main-AMP Input - 3kW 1 2 0 0 0 Output beam profile 1 0 0 0 0 ] W 8 0 0 0 [ r e w o 6 0 0 0 p t u p t 4 0 0 0 u o 2 0 0 0 0 0 5 0 0 1 0 0 0 1 5 0 0 2 0 0 0 2 5 0 0 3 0 0 0 3 5 0 0 i n p u t p o w e r [ W ] 2010 International Symposium on Extreme Ultraviolet Lithography October 17-20, 2010 – Kobe, Japan P15 P15

20kW average pow er system Output beam profile 100% duty operation modelled Pre- Main amplifier system Osc. Amplifier – simulation results � 20kW operation at 100% duty Single-lobe high quality spot at focal � High beam quality point (far-field) maintained thanks to phase distortion compensation by adaptive optics � Improved overall efficiency thanks to efficient pre- amplification � Reduced footprint 2010 International Symposium on Extreme Ultraviolet Lithography October 17-20, 2010 – Kobe, Japan P16

Operation data of current system � 30% Duty operation for 1 Hour 4000 3500 3.4kW@ 30% Stability σ1% 3000 Power (W) 2500 2000 1500 1000 500 0 0 10 20 30 40 50 60 70 Time (minute) � 30% duty operation for 1 hr has been achieved. � 3.4kW @ 30% is equivalent of 11.3kW at 100% duty cycle operation. 2010 International Symposium on Extreme Ultraviolet Lithography October 17-20, 2010 – Kobe, Japan P17

Summary � High pow er CO 2 laser MOPA system has been achieved w ith : � 13kW output pow er at 100kHz, 20ns, duty 30% (on 30msec, off 100msec) � Computer model capable of realistic performance prediction developed � Efficient amplification w ith RF-excited CO 2 laser – effective pre-amplification + multi-line � Efficiency of Multi-line amplification – prediction of 1.3 times higher than Single-line � 20kW system technically feasible � No show stopper at 20kW pow er level (as predicted by numerical modelling) 2010 International Symposium on Extreme Ultraviolet Lithography October 17-20, 2010 – Kobe, Japan P18

Acknowledgments This work was supported by the New Energy and Industrial Technology Development Organization -NEDO- Japan. 2010 International Symposium on Extreme Ultraviolet Lithography October 17-20, 2010 – Kobe, Japan P19