Light-source apparatus, inspection apparatus, and adjustment method

Patent metadata

Field	Value
Publication number	US-12259339-B2
Application number	US-202318154679-A
Country	US
Kind code	B2
Filing date	Jan 13, 2023
Priority date	Jun 28, 2022
Publication date	Mar 25, 2025
Grant date	Mar 25, 2025

Abstract

A light-source apparatus, an inspection apparatus, and an adjustment method capable of facilitating the adjustment of the temperature of a BBO crystal are provided. A light-source apparatus according to the present disclosure includes a first light source configured to generate visible light, a first external resonator including a plurality of optical mirrors, a BBO crystal disposed in the first external resonator, capable of generating UV light in a wavelength range of 233 nm to 236 nm, the UV light being a second harmonic of the visible light, a one- or two-dimensional semiconductor sensor disposed near a far-field image plane formed through an optical element provided on an optical path of the UV light, and a calculation unit configured to calculate a representative position of a light intensity distribution detected by the semiconductor sensor.

First claim

What is claimed is:

1. A light-source apparatus comprising:
a first light source configured to generate visible light in a wavelength range of 466 nm to 472 nm;
a first external resonator including a plurality of optical mirrors;
a BBO crystal disposed in the first external resonator, capable of generating UV (UltraViolet) light in a wavelength range of 233 nm to 236 nm, the UV light being a second harmonic of the visible light;
a one- or two-dimensional semiconductor sensor disposed near a far-field image plane formed through an optical element provided on an optical path of the UV light;
a calculation unit configured to calculate a representative position of a light intensity distribution detected by the semiconductor sensor;
a temperature control unit configured to adjust a temperature of the BBO crystal so that the representative position is confined within a predetermined range;
a second light source configured to generate IR (InfraRed) light in a wavelength range of 1,071 nm to 1,138 nm;
a second external resonator including a plurality of optical mirrors;
a CLBO crystal disposed in the second external resonator and capable of generating deep UV light having a wavelength of about 193 nm, the deep UV light being sum-frequency-mixed light of the UV light and the IR light;
a condensing lens configured to concentrate the UV light in the CLBO crystal; and
a beam splitter disposed between the condensing lens and the CLBO crystal, configured to take out UV light incident on the semiconductor sensor, wherein
an initial value of the representative position is set so that an output of the deep UV light is maximized.

2. The light-source apparatus according to claim 1 , wherein
the temperature control unit determines a temperature correction amount of the BBO crystal based on a linear equation representing a relationship between the representative position and the temperature of the BBO crystal,
the semiconductor sensor is a CCD sensor,
the BBO crystal is spatially translated as optical damages occurs, and
the temperature control unit determines the temperature correction amount based on a difference between the initial value set before the BBO crystal is spatially translated and the representative position after the BBO crystal is spatially translated.

3. The light-source apparatus according to claim 1 , wherein the representative position is a position of the center of gravity of the light intensity distribution.

4. An inspection apparatus wherein the deep UV light generated by the light-source apparatus according to claim 1 is used as irradiation light.

5. An adjustment method for adjusting a temperature of a BBO crystal disposed in a first external resonator including a plurality of optical mirrors, the BBO crystal being capable of generating UV light in a wavelength range of 233 nm to 236 nm, the UV light being a second harmonic of visible light in a wavelength range of 466 nm to 472 nm,
the adjustment method comprising:
calculating a representative position of a light intensity distribution detected by a one- or two-dimensional semiconductor sensor disposed near a far-field image plane formed through an optical element provided on an optical path of the UV light;
adjusting a temperature of the BBO crystal so that the representative position is confined within a predetermined range;
generating IR light in a wavelength range of 1,071 nm to 1,138 nm;
generating, by a CLBO crystal disposed in a second external resonator including a plurality of optical mirrors, deep UV light having a wavelength of about 193 nm, the deep UV light being sum-frequency-mixed light of the UV light and the IR light;
concentrating, by a condensing lens, the UV light in the CLBO crystal; and
taking out, by a beam splitter disposed between the condensing lens and the CLBO crystal, UV light incident on the semiconductor sensor, wherein
an initial value of the representative position is set so that an output of the deep UV light is maximized.

Assignees

• Lasertec Corp

Inventors

• Sakuma Jun
• Mori Ryotaro

Classifications

• G01N2201/0636

  Reflectors · CPC title

• G02F1/3551

  Crystals · CPC title

• G02F1/37

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

• H01S3/005

  Optical devices external to the laser cavity, specially adapted for lasers, e.g. for homogenisation of the beam or for manipulating laser pulses, e.g. pulse shaping (shaping laser beam for working metal or other materials B23K26/06; optical elements, systems or apparatus in general G02B) · CPC title

• H01S3/0071

  Beam steering, e.g. whereby a mirror outside the cavity is present to change the beam direction · CPC title