High power fiber laser driver for efficient EUV lithography source with tin-doped water droplet targets.

In this paper we report the development of nanosecond-pulsed fiber laser technology for the next generation EUV lithography sources. The demonstrated fiber laser system incorporates large core fibers and arbitrary optical waveform generation, which enables achieving optimum intensities and other critical beam characteristics on a laser-plasma target. Experiment demonstrates efficient EUV generation with conversion efficiency of up to 2.07% for in-band 13.5-nm radiation using mass-limited Sn-doped droplet targets. This result opens a new technological path towards fiber laser based high power EUV sources for high-throughput lithography steppers.

Comparative extreme ultraviolet emission measurements for lithium and tin laser plasmas.

Detailed spectroscopic studies on extreme UV emission from laser plasmas using tin and lithium planar solid targets were completed. At 13.5 nm, the best conversion efficiency (CE) for lithium was found to be 2.2% at intensities near 7 x 10(10) W/cm(2). The highest CE measured for tin was near 5.0% at an intensity close to 1 x 10(11) W/cm(2).

13.5 nm EUV generation from tin-doped droplets using a fiber laser.

A comprehensive study of the spectral and Mo-Si mirror inband EUV emission from tin-doped droplet laser plasma targets irradiated with a single 1064 nm beam from an Yb:doped fiber laser is reported.With pre-pulse enhancement, in-band conversion efficiency of approximately 2.1% is measured for laser irradiance intensities near 8 x 10(10) W/cm(2). This is the first study to be reported that uses a high-power, high repetition rate fiber laser with the high repetition rate droplet targets where EUV generation from plasmas is measured.