1 W plasma x-ray source for lithography at 1 nm wavelength

A picosecond excimer laser-plasma source is used to generate average x-ray powers of 1.5 and 0.9 W at 1.4 and 1 nm wavelength, respectively. These wavelengths are required for proximity x-ray lithography in the semiconductor industry. The laser system uses a commercial KrF excimer amplifier for trains of 8 ps laser pulses which are focused to power densities of > 10(15) W/cm(2) on steel and copper tape targets, in atmospheric pressure helium gas. The laser to x-ray energy conversion efficiency is 10.4% at 1.4 nm and 5.4% at 1 nm x-ray wavelength. By using several, larger, commercial, excimer laser amplifiers, the x-ray power output of the laser-plasma source can be scaled up to the tens of watts required by the semiconductor industry. (C) 1996 American Institute of Physics.