Solid-state laser system and laser apparatus used for exposure apparatus

Patent metadata

Field	Value
Publication number	US-9929529-B2
Application number	US-201715672754-A
Country	US
Kind code	B2
Filing date	Aug 9, 2017
Priority date	Mar 6, 2015
Publication date	Mar 27, 2018
Grant date	Mar 27, 2018

Abstract

A solid-state laser system may include a first solid-state laser unit, a second solid-state laser unit, a wavelength conversion system, a wavelength detector, and a wavelength controller. The wavelength conversion system may receive a first pulsed laser light beam with a first wavelength and a second pulsed laser light beam with a second wavelength, and output a third pulsed laser light beam with a third wavelength converted from the first and second wavelengths. The wavelength controller may control the first solid-state laser unit to vary the first wavelength on a condition that an absolute value of a difference between a value of a target wavelength and a value of the third wavelength detected by the wavelength detector is equal to or less than a predetermined value, and control the second solid-state laser unit to vary the second wavelength on a condition that the absolute value exceeds the predetermined value.

First claim

What is claimed is:

1. A solid-state laser system, comprising:
a first solid-state laser unit configured to output a first pulsed laser light beam with a first wavelength generated on a basis of first seed light;
a second solid-state laser unit configured to output a second pulsed laser light beam with a second wavelength generated on a basis of second seed light;
a wavelength conversion system configured to receive the first pulsed laser light beam and the second pulsed laser light beam, and output a third pulsed laser light beam with a third wavelength that is converted from the first wavelength and the second wavelength;
a wavelength detector configured to detect a value of the third wavelength; and
a wavelength controller configured to control the first solid-state laser unit to vary the first wavelength on a condition that an absolute value of a difference between a value of a target wavelength and the value of the third wavelength detected by the wavelength detector is equal to or less than a predetermined value, and control the second solid-state laser unit to vary the second wavelength on a condition that the absolute value of the difference exceeds the predetermined value.

2. The solid-state laser system according to claim 1 , wherein the wavelength detector includes a wavelength monitor provided in an optical path of the third pulsed laser light beam.

3. The solid-state laser system according to claim 1 , wherein the wavelength detector includes:
a first wavelength monitor provided in an optical path of the first seed light;
a second wavelength monitor provided in an optical path of the second seed light; and
a calculation section configured to calculate the value of the third wavelength from a value measured by the first wavelength monitor and a value measured by the second wavelength monitor.

4. The solid-state laser system according to claim 1 , wherein a variation range of the first wavelength in the first solid-state laser unit is narrower than a variation range of the second wavelength in the second solid-state laser unit.

5. The solid-state laser system according to claim 1 , wherein the first wavelength is shorter than the second wavelength.

6. The solid-state laser system according to claim 1 , wherein a variation velocity of the first wavelength in the first solid-state laser unit is higher than a variation velocity of the second wavelength in the second solid-state laser unit.

7. The solid-state laser system according to claim 1 , wherein the first solid-state laser unit includes a nonlinear crystal provided in an optical path of the first seed light.

8. The solid-state laser system according to claim 1 , wherein the first solid-state laser unit includes an external cavity laser diode configured to output the first seed light.

9. The solid-state laser system according to claim 1 , wherein the second solid-state laser unit includes a distributed-feedback laser diode configured to output the second seed light.

10. The solid-state laser system according to claim 1 , wherein the wavelength conversion system includes:
a nonlinear crystal configured to output converted light with a predetermined wavelength converted on a basis of first entering light and second entering light; and
a rotation mechanism configured to vary an entry angle of each of the first entering light and the second entering light to the nonlinear crystal.

11. The solid-state laser system according to claim 10 , further comprising:
a photodetector; and
a rotation controller,
the nonlinear crystal being configured to output light with a wavelength different from the predetermined wavelength as well,
the photodetector being provided in an optical path of the light with the wavelength different from the predetermined wavelength, and
the rotation controller being configured to control the rotation mechanism to change a detection value derived from the photodetector smaller, the detection value being associated with the light with the wavelength different from the predetermined wavelength.

12. The solid-state laser system according to claim 10 , further comprising:
a photodetector provided in an optical path of the converted light; and
a rotation controller configured to control the rotation mechanism to change a detection value derived from the photodetector larger, the detection value being associated with the converted light.

13. The solid-state laser system according to claim 1 , wherein
a variation range of the first wavelength in the first solid-state laser unit includes a wavelength of 257.5 m, and
a variation range of the second wavelength in the second solid-state laser unit includes a wavelength of 1554 nm.

14. The solid-state laser system according to claim 1 , wherein the wavelength conversion system includes a CLBO crystal.

15. A laser apparatus used for an exposure apparatus, the laser apparatus comprising:
a first solid-state laser unit configured to output a first pulsed laser light beam with a first wavelength generated on a basis of first seed light;
a second solid-state laser unit configured to output a second pulsed laser light beam with a second wavelength generated on a basis of second seed light;
a wavelength conversion system configured to receive the first pulsed laser light beam and the second pulsed laser light beam, and output a third pulsed laser light beam with a third wavelength that is converted from the first wavelength and the second wavelength;
a wavelength detector configured to detect a value of the third wavelength;
a wavelength controller configured to control the first solid-state laser unit to vary the first wavelength on a condition that an absolute value of a difference between a value of a target wavelength and the value of the third wavelength detected by the wavelength detector is equal to or less than a predetermined value, and control the second solid-state laser unit to vary the second wavelength on a condition that the absolute value of the difference exceeds the predetermined value; and
an amplifier provided in an optical path of the third pulsed laser light beam.

16. The laser apparatus according to claim 15 , wherein the wavelength detector includes a wavelength monitor provided in the optical path of the third pulsed laser light beam amplified by the amplifier.

17. The laser apparatus according to claim 15 , wherein
a variation range of the first wavelength in the first solid-state laser unit includes a wavelength of 257.5 m, and
a variation range of the second wavelength in the second solid-state laser unit includes a wavelength of 1554 nm.

18. The laser apparatus according to claim 15 , wherein the wavelength conversion system includes a CLBO crystal.

Assignees

• Gigaphoton Inc

Inventors

• Onose Takashi
• Wakabayashi Osamu

Classifications

• H01S3/10 Primary

  Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating · CPC title

• G02F1/37

  for second-harmonic generation {(G02F1/3532 takes precedence)} · CPC title

• H01S3/23

  Arrangements of two or more lasers not provided for in groups H01S3/02 - H01S3/22, e.g. tandem arrangements of separate active media · CPC title

• H01S3/10015 Primary

  by monitoring or controlling, e.g. attenuating, the input signal · CPC title

• H01S3/1608

  erbium · CPC title