LPP EUV light source employing high power C0 2 laser

Abstract

We are developing a high power CO₂ laser system for a LPP EUV light source. Recent theoretical and experimental data demonstrate the advantages of the combination of a CO₂ laser with a Sn target including the generation of a high CE and low debris plasma with low energy ions and low out-of-band radiation. Our laser system is a short pulse CO₂ MOPA (Master Oscillator Power Amplifier) system with 22 ns pulse width and multi kW average power at 100 kHz repetition rate. We achieved an average laser power of 8 kW with a single laser beam having very good beam quality. A EUV in-band power of 60 W at the intermediate focus was generated irradiating a rotating tin plate with 6 kW laser power.