Development of the reliable high power pulsed carbon dioxide laser system for LPP EUV light source

Laser Produced Plasma (LPP) Extreme Ultra Violet (EUV) light source is expected to be used for next generation lithography. To realize such performance for industrial use, the main driver laser is one of the key components. Our source uses a high power pulsed carbon dioxide (CO2) laser as a plasma driver. A master oscillator and a power amplifier (MOPA) system based on a new configuration of an RF-excited CO2 laser is the key to high efficiency. And multiline amplification of CO2 laser is efficient to increase the extraction efficiency in the case of short pulse amplification like this amplification. Numerical result shows the amplification enhancement as 1.3 times higher than the single line amplification. This report shows its initial performance. Multiline configuration is applied to the master oscillator and the efficiency of multiline amplification is verified in our experimental amplifier system. We have achieved 10% energy extraction improvement using 2 lines (P20+P22) as compared to single line (P20).