System and method for optimizing target rarefaction for enhancing EUV radiation from a laser-produced plasma

Abstract

A method of operating an EUV radiation source includes generating a stream of droplets of target material. The method includes illuminating a droplet using a first laser pulse to adjust a shape of the droplet into a target. The method includes illuminating the target using a second laser pulse to rarefy the target. The method includes illuminating the rarefied target using a third laser pulse to ionize the rarefied target to generate EUV radiation. The method includes measuring an EUV performance metric as a function of a time between the second and third laser pulses and as a function of an energy of the second laser pulse. The method includes determining a value for the time between the second and third laser pulses and a value for the energy of the second laser pulse based on a maximum value of the EUV performance metric determined from the measuring.

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