Solid-state lasers for 193 nm lithography

Advances in technology now make possible solid-state 193 nm lasers. Solid-state sources call operate with pulse repetition rates of > 10 kHz, minimizing peak-power damage to stepper optics. Furthermore, solid-state lasers are potentially more reliable and could have lower operating costs than ArF excimer lasers. Achievement of spectral linewidths < 0.1 pm for use with refractive lens systems is straightforward in solid-state laser systems. Ultraviolet solid-state laser technology is much less mature than excimer laser technology, so while there is far td go, there is much more potential for rapid progress in solid-state lasers than in excimer lasers. Aculight has begun a program to develop a multiwatt, 10 kHz solid-state 193 nm laser. Although efficient conversion from 1064 nm to 193 nm is easiest for high peak power pulses, minimization of lens damage requires low peak power. Eventual goals for the technology are to achieve output powers 10-20 W at > 20 kHz repetition rate in > 10 ns pulses, limiting peak powers to < 200 kW. High pulse repetition rates will permit excellent dose control, and facilitate decoherence of the high-coherence beam from the solid-state laser system.