Velocity characterization of particulate debris from laser-produced plasmas used for extreme-ultraviolet lithography

Debris from laser-produced plasmas created with solid Sn and Au targets has been characterized according to speed and particulate size. Conditions for the experiments were those appropriate for producing an optimum laser-produced plasma emission at 13.5 nm for use in extreme-ultraviolet lithography. Results in the form of histogram data show that the speed distribution of the debris particulates is quite varied and in general exhibits an upper limit of ~640 m/s. In the case of Sn a peak in the velocity distribution is observed near 300 m/s. Small particulates, of the order of 1 µm or less, constitute the majority of the particulate emission in both materials. The implications for debris reduction based on the measurements are also discussed.