Laser unit and extreme ultraviolet light generating system

Patent metadata

Field	Value
Publication number	US-2016285222-A1
Application number	US-201615172757-A
Country	US
Kind code	A1
Filing date	Jun 3, 2016
Priority date	Jan 27, 2014
Publication date	Sep 29, 2016
Grant date	—

Abstract

There is provided a laser unit that may include a master oscillator, a laser amplifier, and an adjuster. The master oscillator may be configured to output a laser light beam. The laser amplifier may be disposed in a light path of the laser light beam outputted from the master oscillator. The adjuster may be disposed in the light path of the laser light beam, and may be configured to adjust a beam cross-sectional shape of the laser light beam amplified by the laser amplifier to be a substantially circular shape. The beam cross-sectional shape may be at a beam waist of the laser light beam or in the vicinity of the beam waist of the laser light beam, and may be in a plane orthogonal to a light path axis.

First claim

What is claimed is:

1 . A laser unit, comprising:
a master oscillator configured to output a laser light beam; a laser amplifier disposed in a light path of the laser light beam outputted from the master oscillator; and an adjuster disposed in the light path of the laser light beam, and configured to adjust a beam cross-sectional shape of the laser light beam amplified by the laser amplifier to be a substantially circular shape, the beam cross-sectional shape being at a beam waist of the laser light beam or in the vicinity of the beam waist of the laser light beam, and being in a plane orthogonal to a light path axis.

2 . The laser unit according to claim 1 , further comprising a rotary mechanism configured to rotate the adjuster around the light path axis.

3 . The laser unit according to claim 1 , wherein the laser amplifier is a slab amplifier that includes a pair of discharge electrodes disposed to oppose each other.

4 . The laser unit according to claim 3 , wherein
the adjuster includes an adjusting mechanism configured to adjust a beam diameter of the laser light beam in one direction that is orthogonal to the light path axis, and an opposing direction of the discharge electrodes is substantially the same as a direction in which the beam diameter of the laser light beam is adjusted.

5 . The laser unit according to claim 1 , further comprising:
a detecting section disposed at a downstream of the adjuster in the light path of the laser light beam, and configured to detect the beam cross-sectional shape at the beam waist or in the vicinity of the beam waist; and a controller configured to control the adjuster, based on a result of the detection by the detecting section.

6 . The laser unit according to claim 5 , wherein the adjuster includes a movable optical member that varies a beam diameter of the laser light beam in one direction that is orthogonal to the light path axis.

7 . The laser unit according to claim 5 , further comprising a rotary mechanism,
wherein the adjuster includes a movable optical member that varies a beam diameter of the laser light beam in one direction that is orthogonal to the light path axis, and the rotary mechanism is configured to rotate the movable optical member around the light path axis of the laser light beam.

8 . The laser unit according to claim 7 , wherein
the controller measures, based on the result of the detection by the detecting section, a first direction in which the beam diameter is maximized in the plane orthogonal to the light path axis and a second direction in which the beam diameter is minimized in the plane orthogonal to the light path axis, and the controller controls the rotary mechanism to allow the direction in which the beam diameter of the laser light beam is varied by the adjuster to be substantially the same as one of the first direction and the second direction.

9 . The laser unit according to claim 6 , wherein
the detecting section includes a detector and a light concentrator, the detector being configured to detect the beam cross-sectional shape, and the light concentrator being configured to concentrate the laser light beam onto the detector, and one or both of the detector and the light concentrator are disposed movably in a direction of the light path axis.

10 . An extreme ultraviolet light generating system comprising:
a chamber in which a pulsed laser light beam is to be applied to a target to generate extreme ultraviolet light; a target feeder configured to supply the target into the chamber; a master oscillator configured to output a laser light beam serving as a seed of the pulsed laser light beam; a laser amplifier disposed in a light path of the laser light beam outputted from the master oscillator; a laser concentrating optical system configured to concentrate the laser light beam amplified by the laser amplifier into the chamber; and an adjuster disposed in the light path of the laser light beam between the master oscillator and the laser concentrating optical system, and configured to adjust a beam cross-sectional shape of the laser light beam concentrated by the laser concentrating optical system to be a substantially circular shape, the beam cross-sectional shape being at a beam waist of the laser light beam or in the vicinity of the beam waist of the laser light beam, and being in a plane orthogonal to a light path axis.

11 . The extreme ultraviolet light generating system according to claim 10 , wherein the target feeder supplies the target to a location at the beam waist of the laser light beam or in the vicinity of the beam waist of the laser light beam.

12 . The extreme ultraviolet light generating system according to claim 10 , further comprising:
a detecting section disposed in the light path of the laser light beam between the adjuster and the laser concentrating optical system, and configured to detect the beam cross-sectional shape at the beam waist or in the vicinity of the beam waist; and a controller configured to control the adjuster, based on a result of the detection by the detecting section.

Assignees

• Gigaphoton Inc

Inventors

• Suganuma Takashi
• Yabu Takayuki
• Wakabayashi Osamu
• Nogiwa Seiji

Classifications

• H05G2/0086

  Optical arrangements for conveying the laser beam to the plasma generation location · CPC title

• H05G2/0084

  Control of the laser beam · CPC title

• H01S3/2232

  Carbon dioxide (CO2) or monoxide [CO] · CPC title

• H01S3/2366

  comprising a gas as the active medium (H01S3/10092, H01S3/2383 take precedence) · CPC title

• H01S3/2316

  Cascaded amplifiers · CPC title