Development of laser-plasma soft X-ray source for projection lithography

摘要

Laser-plasma soft X-rays as a projection X-raylithograph source are required to be used for more than 8successive hours. And serious problems are soft X-ray energystability, damages to optics by debris and successive supplytargets. From the measurements of soft X-ray spectra and amount,size and scattering direction of debris from target irradiated withfocused laser, we have developed a laser-plasma soft X-raysource system with debris-shield, debris free X-ray filter, tape-target driver and the low debris tape-target of the thin aluminumand polymer films. We demonstrated 8 successive hoursgeneration of soft X-rays with the developed laser-plasma soft X-ray system as a projection X-ray lithograph source. The energyconversion efficiency of the soft X-rays at the wavelength of 13nm in our system was estimated to be 0.29%.