An EUV radiation source that employs a low energy laser pre-pulse and a high energy laser main pulse. The pre-pulse generates a weak plasma in the target area that improves laser absorption of the main laser pulse to improve EUV radiation emissions. High energy ion flux is reduced by collisions in the localized target vapor cloud generated by the pre-pulse. Also, the low energy pre-pulse arrives at the target area 20-200 ns before the main pulse for maximum output intensity. The timing between the pre-pulse and the main pulse can be reduced below 160 ns to provide a lower intensity of the EUV radiation. In one embodiment, the pre-pulse is split from the main pulse by a suitable beam splitter having the proper beam intensity ratio, and the main pulse is delayed to arrive at the target area after the pre-pulse.
A debris collector for EUV light generators is disclosed which enables to improve durabilities of optical units in a chamber including a collector mirror, to keep the vacuum degree in the chamber, and to suppress decrease in EUV light output by efficiently collecting debris bumping into the collector mirror at high speed from a target transformed into a plasma or debris adhering the collector mirror. A laser light irradiator (10) is so arranged that the irradiation direction of a laser light (L) is opposite to the traveling direction of a target (1). A debris collector (30) for collecting debris (3) is arranged in the travel path of the target (1).
The device comprises a device (2) for creating an essentially linear target (4) in an evacuated space where laser beams (1) are focused, the target being suitable for interacting with the focused laser beams (1) to emit a plasma emitting radiation in the extreme ultraviolet. A receiver device (3) receives the target (4) after it has interacted with the focused laser beams (1), and a collector device (110) collects the EUV radiation emitted by the target (4). The focusing elements (11) for focusing the laser beams on the target (4) are arranged in such a manner that the laser beams (1) are focused on the target (4) laterally, being situated in a common half-space relative to the target (4) and being inclined at a determined angle lying in the range about 60.degree. to about 90.degree. relative to a mean collection axis (6) perpendicular to the target (4). The collector device (110) is disposed symmetrically about the mean collection axis (6) in the half-space containing the laser beams (1) focused on the target (4) and inside a conical space (8) centered on the mean collection axis (6) with a vertex situated at the target (4) and a half-angle at the vertex that is less than the angle of inclination of the focused laser beams (1) relative to the mean collection axis (6). The device is suitable for use as a source for EUV radiation in lithography for fabricating integrated circuits.
A high energy photon source for generating EUV radiation comprises a nozzle emitting a supersonic stream of source material, a laser or electrical/magnetic pre-ionization mechanism and a laser or electrical/magnetic excitation mechanism and a skimmer plate between them providing a collimated high density beam of source material for excitation.
An EUV light generation system and method is disclosed that may comprise a droplet generator producing plasma source material target droplets traveling toward the vicinity of a plasma source material target irradiation site; a drive laser; a drive laser focusing optical element having a first range of operating center wavelengths; a droplet detection radiation source having a second range of operating center wavelengths; a drive laser steering element comprising a material that is highly reflective within at least some part of the first range of wavelengths and highly transmissive within at least some part of the second range of center wavelengths; a droplet detection radiation aiming mechanism directing the droplet detection radiation through the drive laser steering element and the lens to focus at a selected droplet detection position intermediate the droplet generator and the irradiation site. The apparatus and method may further comprise a droplet detection mechanism that may comprise a droplet detection radiation detector positioned to detect droplet detection radiation reflected from a plasma source material droplet.
