EXTREME ULTRAVIOLET LIGHT SOURCE AND TARGET FOR EXTREME ULTRAVIOLET LIGHT SOURCE TARGET

摘要

An object of the present invention is to provide an extreme ultraviolet light source target which can emits extreme ultraviolet light with high emission efficiency. A solid target made of heavy metal or heavy-metal compound and having a density 0.5 to 80% that of the crystal density is used. When the target is irradiated with a laser beam, plasma of the heavy metal contained in the target is generated, and extreme ultraviolet light having a predetermined wavelength which corresponds to the kind of the heavy metal is emitted from the plasma. When the density of the target is made to be smaller than the crystal density as described above, space distribution of the density of the generated plasma can be controlled, and the region in which plasma absorbs energy of the laser beam overlaps the region in which the plasma emits the extreme ultraviolet light. Thus, emission efficiency can be improved, preventing energy loss. For example, in a case where the SnO2 target having a density 24% of the crystal density is used, the emission efficiency at around 13.5 nm wavelength is higher than in the case where a Sn crystal target is used.