We reported 1st generation Laser-Produced Plasma source system "ETS" device for EUV lithography one year ago 1) . In this paper we update performance status of the 1st generation system. We have improved the system further, maximum burst power is 104W (100kHz, 1 mJ EUV power @ intermediate focus), laser-EUV conversion efficiency is 2.5%. Also continuous operation time is so far up to 8 hours with 5% duty cycle is achieved. We have investigated EUV plasma creation scheme by small experimental device which is facilitated 10Hz operation (maximum). We have proposed double pulse method to create LPP plasma efficiently. This moment we found out 3.3% conversion efficiency operation condition.Based on the engineering data of ETS and small experimental device, now we are developing 2 nd generation HVM source; GL200E. The device consists of the original concepts (1) CO 2 laser driven Sn plasma, (2) Hybrid CO 2 laser system that is combination of high speed (>100kHz) short pulse oscillator and industrial cw-CO 2 , (3) Magnetic mitigation, and (4) Double pulse EUV plasma creation. The preliminary data are introduced in this paper.

The 1st generation Laser-Produced Plasma source system "ETS" device for EUV lithography is under development. We report latest status of the device which consists of the original concepts (1) CO2 laser driven Sn plasma, (2) Hybrid CO2 laser system that is combination of high speed (>100kHz) short pulse oscillator and industrial cw-CO2, (3) Magnetic mitigation, and (4) Double pulse EUV plasma creation. Maximum burst on time power is 69W (100kHz, 0.7 mJ EUV power @ intermediate focus), laser-EUV conversion efficiency is 2.3%, duty cycle is 20% at maximum. Continuous operation time is so far up to 3 hours. Debris is efficiently suppressed by pre-pulse plasma formation and magnetic field mitigation system. Long-term performance is now under investigation. Also future plan is updated

The effect of small amounts of gaseous additives and impurities on ArF laser performance has been studied. It has been found that the output characteristics of the ArF laser improves significantly at a xenon concentration of 10 ppm but strongly deteriorates at impurity concentrations above 10 ppm of e.g. O2, CF4 and HF, especially, at high laser repetition rates. A new laser discharge chamber has therefore been developed using metal seals and coating the inner chamber walls with thin fluoride layers. The layers prevent impurities that are otherwise generated through chemical reactions between the fluorine of the laser gas and the chamber wall. The output stability of the ArF excimer laser has been very successfully improved by the new chamber design for repetition rates up to 4 kHz.

No abstract

A feasibility study of next generation 6 kHz ArF laser for lithography is presented. High repetition rate operation of excimer lasers faces two technical challenges: 1) the occurrence of acoustic waves caused by the discharge in the laser chamber and 2) the huge energy consumption of the large gas flow fans. This paper describes our approach to dampen the acoustic waves. A computer simulation of acoustic wave generation inside the discharge chamber was done. The simulation correlates well with Schlieren photography measurements that visualized the acoustic waves. Based on these results, a chamber for 6 kHz repetition rate was newly designed. Measured spectral data (FHWM and E95) proved that the acoustic wave perturbation was remarkably reduced. A very efficient design method for high repetition rate laser chamber has therefore been established.