# US 9,882,340 B2 · Laser device, and exposure device and inspection device provided with the laser device

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 9,882,340 B2
- Document ID: US9882340B2
- Status: Granted
- Kind: B2
- Application number: 15/137,630
- Filed: 2016-04-25
- Published: 2016-08-18
- Granted: 2018-01-30
- Earliest claimed: 2013-10-25
- Assignees: Nikon Corporation
- Applicants: Nikon Corporation
- Inventors: Akira Tokuhisa
- Web page: https://patentgrep.com/patent/US9882340B2

## CPC

- H01S 3/06754: {Fibre amplifiers (H01S3/06708 takes precedence)}
- G02F 1/353: {Frequency conversion, i.e. wherein a light beam is generated with frequency components different from those of the incident light beams}
- G03F 7/70025: {by lasers}
- H01S 3/10015: {by monitoring or controlling, e.g. attenuating, the input signal}
- H01S 3/1003: {tunable optical elements, e.g. acousto-optic filters, tunable gratings}
- H01S 3/2391: {emitting at different wavelengths}
- G02F 1/354: {Third or higher harmonic generation}
- H01S 3/0085: {Modulating the output, i.e. the laser beam is modulated outside the laser cavity}
- 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)}
- H01S 3/1618: {ytterbium}
- H01S: DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G03F: PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR; (phototypographic composing devices B41B; photosensitive materials or processes for photographic purposes G03C; electrophotography, sensitive layers or processes therefor G03G)

## Abstract

A laser device includes: a laser light source which generates a laser light in a pulse waveform of preset predetermined frequency; intensity modulator which is driven with a transmittance waveform wherein transmittance changes at either the predetermined frequency or an integer-multiple frequency thereof and which extracts and outputs the laser light which is outputted from the laser light source; control unit which controls an operation of the intensity modulator; an amplifier which amplifies the laser light which is outputted from the intensity modulator; and a wavelength conversion optical element which converts a wavelength of the laser light which is amplified by the amplifier, wherein the control unit changes relative timing of the transmittance waveform with respect to the pulse waveform, thereby changing the pulse waveform of the laser light which is emitted from the intensity modulator, to output a pulse light of predetermined waveform from the wavelength conversion optical element.

## Claims

### Claim 1

A laser device comprising:
a laser light source which generates a laser light in a pulse waveform of a preset predetermined frequency;
an intensity modulator which is driven with a transmittance waveform wherein transmittance changes at either the predetermined frequency or an integer-multiple frequency thereof and which modulates the laser light which is outputted from the laser light source based on the transmittance waveform;
a control unit which controls an operation of the intensity modulator;
an amplifier which amplifies the laser light which is outputted from the intensity modulator; and
a wavelength conversion optical element which converts a wavelength of the laser light which has been amplified by the amplifier, wherein
the control unit changes relative timing of the transmittance waveform with respect to the pulse waveform, thereby changing the pulse waveform of the laser light which is emitted from the intensity modulator, so that the wavelength conversion optical element converts the wavelength of the laser light which has been amplified by the amplifier to have a different efficiency of wavelength conversion based on the relative timing and outputs a pulse light of a predetermined waveform from the wavelength conversion optical element.

### Claim 2 (depends on 1)

The laser device according to claim 1, wherein
the laser light which is outputted from the intensity modulator includes either a laser light in a first pulse waveform of the predetermined frequency or a laser light in a second pulse waveform of the predetermined frequency which has different timing with respect to that of the laser light in the first pulse waveform,
the laser light in the first pulse waveform is a light which is set so that an efficiency of wavelength conversion at the wavelength conversion optical element is relatively high so as to generate the pulse light,
the laser light in the second pulse waveform is a light which is set to have energy substantially the same as that of the laser light in the first pulse waveform and a relatively low efficiency of wavelength conversion at the wavelength conversion optical element so as not to generate the pulse light.

### Claim 3 (depends on 2)

The laser device according to claim 2, wherein
the laser light source includes a first laser light source that generates a laser light in the first pulse waveform of the predetermined frequency and a second laser light source which generates a laser light in a second pulse waveform of the predetermined frequency at timing different from timing at which the laser light in the first pulse waveform is generated,
the laser light in the first pulse waveform which is outputted from the first laser light source and the laser light in the second pulse waveform which is outputted from the second laser light source are multiplexed and inputted into the intensity modulator,
the transmittance waveform is an on/off gate-like waveform which is switched between a transmission state in which the laser light is transmitted at the predetermined frequency and a shutoff state in which the laser light is shutoff, and
the control unit changes relative timing of the transmittance waveform with respect to the first pulse waveform and the second pulse waveform, thereby changing the pulse waveform of the laser light which is transmitted through the intensity modulator.

### Claim 4 (depends on 3)

The laser device according to claim 3, wherein
the laser light in the first pulse waveform and the laser light in the second pulse waveform differ in peak intensity from each other.

### Claim 5 (depends on 3)

The laser device according to claim 3, wherein
the laser light in the first pulse waveform and the laser light in the second pulse waveform differ in wavelength from each other.

### Claim 6 (depends on 3)

The laser device according to claim 3, wherein
the laser light in the first pulse waveform and the laser light in the second pulse waveform differ in a state of polarization upon entering the wavelength conversion optical element from each other.

### Claim 7 (depends on 3)

The laser device according to claim 3, wherein
the first laser light source and the second laser light source are each a semiconductor laser.

### Claim 8 (depends on 3)

The laser device according to claim 3, wherein
the first laser light source is a mode-locked laser which generates the laser light in the first pulse waveform at the predetermined frequency and
the second laser light source is a semiconductor laser,
the laser device comprises
a photodetector which detects the laser light in the first pulse waveform which is outputted from the mode-locked laser; and
a synchronization circuit which, based on the first pulse waveform which is detected by the photodetector, outputs a synchronization signal to a drive power source of the second laser light source and to the control unit.

### Claim 9 (depends on 3)

The laser device according to claim 3, wherein
the laser light in the first pulse waveform which is outputted from the first laser light source and the laser light in the second pulse waveform which is outputted from the second laser light source are once multiplexed and then divided into a plurality of branch optical paths,
each of the intensity modulator, the wavelength conversion optical element, and the amplifier is provided at each of the plurality of branch optical paths,
the control unit changes the relative timing of the transmittance waveform with respect to the first pulse waveform and the second pulse waveform for each branch optical path, thereby enabling each of the waveform conversion optical elements to output a plurality of pulse lights of different pulse waveforms.

### Claim 10 (depends on 2)

The laser device according to claim 2, wherein
the laser light source is a light source that generates a laser light of a base waveform at the predetermined frequency,
the transmittance waveform is a high and low gate-like waveform in which a first transmittance waveform which has a relatively high transmittance and with which the laser light in the first pulse waveform is extracted from the laser light of the base waveform and a second transmittance waveform which has a relatively low transmittance and with which the laser light in the second pulse waveform is extracted from the laser light of the base waveform are alternately repeated each at the predetermined frequency, and
the control unit changes relative timing of the transmittance waveform with respect to the base waveform, thereby changing the pulse waveform of the laser light that is transmitted through the intensity modulator.

### Claim 11 (depends on 2)

The laser device according to claim 2, wherein
the laser light source includes a first laser light source that generates a laser light of a first base waveform at the predetermined frequency and a second laser light source that generates a laser light of a second base waveform at the predetermined frequency and at different timing from that at which the laser light of the first base waveform is generated,
the laser light of the first base waveform which is outputted from the first laser light source and the laser light of the second base waveform which is outputted from the second laser light source are multiplexed and inputted into the intensity modulator,
the transmittance waveform is a gate-like waveform in which a first transmittance waveform with which the laser light in the first pulse waveform is extracted from the laser light of the first base waveform and a second transmittance waveform with which the laser light in the second pulse waveform is extracted from the laser light of the second base waveform are alternately repeated each at the predetermined frequency,
the control unit changes relative timing of the transmittance waveform with respect to the first base waveform and the second base waveform, thereby changing the pulse waveform of the laser light that is transmitted through the intensity modulator.

### Claim 12 (depends on 11)

The laser device according to claim 11, wherein
the laser light in the first pulse waveform and the laser light in the second pulse waveform differ in peak intensity from each other.

### Claim 13 (depends on 11)

The laser device according to claim 11, wherein
the laser light of the first base waveform and the laser light of the second base waveform differ in wavelength from each other.

### Claim 14 (depends on 11)

The laser device according to claim 11, wherein
the laser light of the first base waveform and the laser light of the second base waveform differ from each other in a state of polarization upon entering the wavelength conversion optical element.

### Claim 15 (depends on 11)

The laser device according to claim 11, wherein
the laser light of the first base waveform which is outputted from the first laser light source and the laser light of the second base waveform which is outputted from the second laser light source are once multiplexed with each other and then divided into a plurality of branch optical paths,
each of the intensity modulator, the amplifier, and the wavelength conversion optical element is provided at each of the plurality of branch optical paths,
the control unit changes the relative timing of the transmittance waveform with respect to the first base waveform and the second base waveform for each branch optical path, thereby enabling each of the wavelength conversion optical elements to output a plurality of pulse lights of different pulse waveforms.

### Claim 16 (depends on 1)

An exposure device comprising:
the laser device according to claim 1;
a mask support unit that holds a photomask on which a predetermined exposure pattern is formed;
an exposure target support unit that holds an exposure target;
an illumination optical system that illuminates the photomask held by the mask support unit with the laser light outputted from the laser device; and
a projection optical system that projects the light which has been transmitted through the photomask onto the exposure target which is held by the exposure target support unit.

### Claim 17 (depends on 1)

An exposure device comprising:
the laser device according to claim 1;
a variable forming mask which has a plurality of movable mirrors and generates a light of any desired pattern;
an exposure target support unit which holds an exposure target;
an illumination optical system which illuminates the variable forming mask with the laser light outputted from the laser device; and
a projection optical system that projects the light of any desired pattern generated via the variable forming mask onto the exposure target which is held by the exposure target support unit.

### Claim 18 (depends on 1)

An exposure device comprising:
the laser device according to claim 1;
an exposure target support unit which holds an exposure target;
a deflection unit which deflects the laser light which is outputted from the laser device to scan the exposure target which is held on the exposure target support unit; and
an objective optical system which forms an image of the light deflected by the deflection unit on the exposure target.

### Claim 19 (depends on 1)

An inspection device comprising:
the laser device according to claim 1;
an inspection target support unit which holds an inspection target;
an illumination optical system which illuminates the inspection target which is held by the inspection target support unit with the laser light which is outputted from the laser device; and
a projection optical system that projects the light from the inspection target onto a detector.