LIGHT SOURCE APPARATUS AND INSPECTION APPARATUS

• US 20160334652A1
• Filed: 05/12/2016
• Published: 11/17/2016
• Est. Priority Date: 05/13/2015
• Status: Active Grant

• Current Assignee: Lasertec Corporation
• Original Assignee: Lasertec Corporation
• Inventors: Sakuma, Jun
• Granted Patent: US 9,696,568 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01J 1/0407 Optical elements not provided otherwise, e.g. manifolds, windows, holograms, gratings
• CPC Class Codes: G01J 3/1256 using acousto-optic tunable filter; acousto-optic elements or systems G02F1/11, G02F1/33
• CPC Class Codes: G01N 2021/95676 Masks, reticles, shadow masks
• CPC Class Codes: G01N 21/1702 with opto-acoustic detection, e.g. for gases or analysing solids
• CPC Class Codes: G01N 21/636 using an arrangement of pump beam and probe beam; using the measurement of optical non-linear properties; non-linear optics per se G02F1/35
• CPC Class Codes: G01N 21/9501 Semiconductor wafers manufacturing processes per se of semiconductor devices implementing a measuring step H01L22/10
• CPC Class Codes: G01N 21/956 Inspecting patterns on the surface of objects contactless testing of electronic circuits G01R31/308; testing currency G07D; manufacturing processes per se of semiconductor devices implementing a measuring step H01L22/10
• CPC Class Codes: G01N 2201/06113 Coherent sources; lasers
• CPC Class Codes: G01N 2201/068 Optics, miscellaneous
• CPC Class Codes: G02B 27/141 using dichroic mirrors
• CPC Class Codes: G02F 1/113 Circuit or control arrangements
• CPC Class Codes: G02F 1/116 using an optically anisotropic medium, wherein the incident and the diffracted light waves have different polarizations, e.g. acousto-optic tunable filter [AOTF] G02F1/125 takes precedence
• CPC Class Codes: G02F 1/3534 Three-wave interaction, e.g. sum-difference frequency generation G02F1/3532 takes precedence
• CPC Class Codes: G02F 1/3551 Crystals
• CPC Class Codes: H01S 3/005 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 Class Codes: H01S 3/0085 Modulating the output, i.e. the laser beam is modulated outside the laser cavity
• CPC Class Codes: H01S 3/0092 Nonlinear frequency conversion, e.g. second harmonic generation [SHG] or sum- or difference-frequency generation outside the laser cavity nonlinear frequency conversion per se G02F1/35
• CPC Class Codes: H01S 3/1306 Stabilisation of the amplitude
• CPC Class Codes: H01S 3/2391 emitting at different wavelengths

Abstract

Provided are a light source apparatus and an inspection apparatus that can stably output a wavelength converted light beam. A light source apparatus includes a laser light source that generates a first fundamental light beam, at least one nonlinear optical crystal that generates a wavelength converted light beam using the fundamental light beam or a harmonic laser beam of the fundamental light beam as an incident light beam, a detector that detects the wavelength converted light beam, an acousto-optic modulator that is disposed in an optical path of the incident light beam in such a way that a zero-order light beam enters the nonlinear optical crystal, and a controller that controls an output intensity of the wavelength converted light beam according to a detection signal from the detector.

Claims

1. A light source apparatus comprising:

a first laser light source that generates a first fundamental light beam;

a second laser light source that generates a second fundamental light beam, the second fundamental light beam having a wavelength different from that of the first fundamental light beam;

an at least one nonlinear optical crystal that generates a wavelength converted light beam by sum-frequency mixing, the sum frequency mixing using the first fundamental light beam and a harmonic light beam of the second fundamental light beam as incident light beams;

a detector that detects the wavelength converted light beam;

an acousto-optic modulator that is disposed in an optical path between the first laser light source and the nonlinear optical crystal or an optical path between the second laser light source and the nonlinear optical crystal, the acousto-optic modulator being disposed in such a way that a zero-order light beam enters the nonlinear optical crystal;

a coupling mirror that is disposed in an optical path between the acousto-optic modulator and the nonlinear optical crystal and is disposed in such a way that the harmonic laser beam of the second fundamental light beam will become coaxial with the first fundamental light beam; and

a controller configured to output a control signal that changes a diffraction efficiency of the acousto-optic modulator and to control an output intensity of the wavelength converted light beam according to a detection signal from the detector.

2. The light source apparatus according to claim 1, wherein

a wavelength of the first fundamental light beam is in a range of 1000 to 1200 nm,

an incident light beam with a wavelength in a range of 200 to 280 nm by fourth-order or fifth-order harmonic generation of the second fundamental light beam enters the nonlinear optical crystal, and

the acousto-optic modulator is disposed in an optical path of the first fundamental light beam.

3. The light source apparatus according to claim 1, wherein

a wavelength of the first fundamental light beam is in a range of 1000 to 1200 nm,

an incident light beam with a wavelength in a range of 200 to 280 nm by fourth-order or fifth-order harmonic generation of the second fundamental light beam enters the nonlinear optical crystal, and

the acousto-optic modulator is disposed in an optical path of the second fundamental light beam.

4. The light source apparatus according to claim 1, wherein

a wavelength of the first fundamental light beam is in a range of 1000 to 1200 nm,

an incident light beam with a wavelength in a range of 200 to 280 nm by fourth-order or fifth-order harmonic generation of the second fundamental light beam enters the nonlinear optical crystal, and

the acousto-optic modulator is disposed in an optical path of a second harmonic laser beam of the second fundamental light beam.

5. An inspection apparatus comprising:

the light source apparatus according to claim 1; and

an optical element configured to reduce coherence in an optical path of the wavelength converted light beam.

6. The inspection apparatus according to claim 5, wherein the detector is configured to detect a wavelength converted light beam output that has passed through the optical element.