High brightness lpp euv light source with fast rotating target and method of cooling thereof

Abstract

A laser produced plasma (LPP) light source comprises a rotating target assembly supplying a target into an interaction zone with a focused beam of a high-repetition-rate pulsed laser. High effective cooling of the light source is provided by thermal radiation of a peripheral part of the rotating target assembly and through a meander-shaped gap between the rotating target assembly and a fixed heat exchanger with a gas blowing through the slit gap. In an embodiment, a sealing between the vacuum chamber and a shaft of rotating drive unit is provided by a magnetic fluid seal (MFS) with an additional heat exchanger. A heat transfer from the rotating target assembly is provided through the shaft and MFS to additional heat exchanger and by convection air cooling of a counterweight of the rotating target assembly fixed on the shaft. High brightness and high output power of LPP light source are provided.