System and method to reduce oscillations in extreme ultraviolet light generation

摘要

A droplet generation system for use with a laser produced plasma (LPP) extreme ultraviolet (EUV) source plasma chamber is described. During EUV generation, oscillations can occur as a function of droplet time-of-flight within the plasma chamber. To reduce these oscillations, a droplet controller adjusts the rate at which droplets are generated which, in turn, dictates the droplet time-of-flight. The droplets are a result of coalescence of generated microdroplets such that the rate at which the droplets are generated is dictated by a frequency of a signal used to generate the microdroplets. This adjustment can be a modulation of a baseline droplet frequency. In some instances, the modulation function may be a sinusoid or implemented as a pseudo-random switch.

主权项

1. A system for use with a laser produced plasma (LPP) extreme ultraviolet (EUV) system having a plasma chamber and an irradiation site within the plasma chamber, comprising:
a droplet controller configured to adjust, according to a modulation function of a pre-defined droplet frequency over a specified time scale, a frequency of a microdroplet generation function for generating microdroplets that coalesce into droplets, the adjusted frequency dictating modulation of the pre-defined droplet frequency at which the droplets arrive at the irradiation site; and a droplet generator configured to generate the microdroplets according to the adjusted frequency of the microdroplet generation function.