A lithography method in semiconductor fabrication is provided. The method includes generating multiple groups of small drops of a target material through a number of nozzles in such a way that small drops in each of the groups are aggregated to an elongated droplet of the target material. The method also includes generating a laser pulse from a laser generator to convert the elongated droplets to plasma which generates an EUV radiation. The method further includes exposing a semiconductor wafer to the EUV radiation.

A laser processing method of performing laser processing on a transparent material that is transparent to ultraviolet light by using a laser processing system includes: performing relative positioning of a transfer position of a transfer image and the transparent material in an optical axis direction of a pulse laser beam so that the transfer position is set at a position inside the transparent material at a predetermined depth ΔZsf from a surface of the transparent material in the optical axis direction; and irradiating the transparent material with the pulse laser beam having a pulse width of 1 ns to 100 ns inclusive and a beam diameter of 10 μm to 150 μm inclusive at the transfer position.

A broadband light source includes a rotatable drum coated with plasma-forming target material, a rotational actuator configured to rotate the rotatable drum, and a rotary encoder connected to the rotatable drum. The broadband light source may include a linear actuator configured to axially translate the rotatable drum and linear encoder connected to the rotatable drum. The broadband light source includes a pulsed laser source configured to direct pulsed illumination to a set of spots on the material-coated portion of the rotatable drum for exciting the plasma-forming target material and emitting broadband light as the drum is actuated. The broadband light source includes a control system. The control system is configured to receive one or more rotational position indicators from the rotary indicator and control triggering of the laser source based on the one or more rotational position indicators from rotary encoder.

A pulsed light generation device includes: an optical coupler having four input/output ports including a first port, a second port, a third port and a fourth port; a connection optical path that connects the third port with the fourth port; and a phase modulation element disposed in the connection optical path. The optical coupler branches pulsed light input to the first port and outputs the branched input pulsed light as first-direction pulsed light and second-direction pulsed light to the third port and to the fourth port. The modulation element applies phase modulation to either one of the first-direction pulsed light and the second-direction pulsed light, thereby outputs output pulsed lights through the first port and the second port, wherein a waveform of one of the pulsed lights output through the first port is different from a waveform of the other of the output pulsed lights output through the second port.

A lithographic system comprises a radiation source and a lithographic apparatus. The radiation source provides radiation to the lithographic apparatus. The lithographic apparatus uses the radiation for imaging a pattern onto multiple target areas on a layer of photo-resist on a semiconductor substrate. The imaging requires a pre-determined dose of radiation. The system is controlled so as to set a level of a power of the radiation in dependence on a magnitude of the pre-determined dose.

A lithography method in semiconductor fabrication is provided. The method includes generating a plurality of drops of a target material through a plurality of nozzles, adjacent two of the plurality of nozzles having a distance less than a width of a first one of the adjacent two of the plurality of nozzles, wherein the plurality of drops are aggregated to an elongated droplet; generating a laser pulse to convert the elongated droplet into plasma that generates an extreme ultraviolet (EUV) radiation; exposing a semiconductor substrate to the EUV radiation.

An extreme ultraviolet light generation system includes: a chamber; a target generation unit; a laser system configured to output a first pre-pulse laser beam, a second pre-pulse laser beam, and a main pulse laser beam so that fluence of the first pre-pulse laser beam is 1.5 J/cm.sup.2 to 16 J/cm.sup.2 inclusive at a position where a target is irradiated with the first pre-pulse laser beam; and a control unit configured to control the laser system so that a first delay time from a timing of irradiation of the target with the first pre-pulse laser beam to a timing of irradiation with the second pre-pulse laser beam and a second delay time from the timing of irradiation of the target with the second pre-pulse laser beam to a timing of irradiation with the main pulse laser beam have a following relation:
the first delay time<the second delay time.

An extreme ultraviolet light generation system may include a chamber, a first partition wall having at least one opening which provides communication between a first space and a second space, an EUV light concentrating mirror located in the second space and configured to concentrate extreme ultraviolet light generated in a plasma generation region located in the first space, a first gas supply port formed at the chamber, and a gas exhaust port formed in the first partition wall, a distance between the center of the plasma generation region and an edge of the at least one opening being equal to or more than a stop distance L.sub.STOP [mm] calculated by the following equation.

L.sub.STOP=272.8.Math.E.sub.VG.sup.0.4522.Math.P.sup.−1

E.sub.AVG [eV] representing average kinetic energy of ions generated in the plasma generation region and P [Pa] representing a gas pressure inside the first partition wall

In accordance with some embodiments, a method of controlling an extreme ultraviolet (EUV) radiation in lithography system is provided. The method includes generating a plurality of target droplets. The method also includes generating a pre-pulse and a main pulse from an excitation laser module to generate EUV light and reflecting the EUV light by a collector mirror. The method further includes measuring a separation between a pre-pulse and a main pulse. Moreover, the method includes determining whether the separation between the pre-pulse and the main pulse in the y-axis is changed, if not adjusting a configurable parameter of the excitation laser module to set the variation in the energy of the EUV light within an acceptable range.

An optical pulse stretcher includes a first delay optical system including a plurality of concave toroidal mirrors; and a beam splitter including a first surface and a second surface, causing a part of pulse laser light incident on the first surface to be transmitted in a first direction and output as a first beam and another part thereof to be reflected in a second direction and enter the first delay optical system, and causing a part of pulse laser light incident on the second surface from the first delay optical system to be reflected in the first direction and output as a second beam.