Laser system

• US 8,144,740 B1
• Filed: 12/16/2009
• Issued: 03/27/2012
• Est. Priority Date: 11/01/2005
• Status: Active Grant

• Current Assignee: Cymer Incorporated (ASML Holding NV)
• Original Assignee: Cymer Incorporated (ASML Holding NV)
• Inventors: Brown, Daniel J. W., Partlo, William N., Sandstrom, Richard L.
• Primary Examiner(s): NGUYEN, DUNG T
• Application Number:
  US12/639,339
• Publication Number:
  US 20120087386A1
• Time in Patent Office: 832 Days
• Field of Search: 372/32, 372/55, 372/57, 372/61
• US Class Current: 372/32
• CPC Class Codes: G03F 7/70025 by lasers
• CPC Class Codes: G03F 7/70041 by pulsed sources, e.g. multiplexing, pulse duration, interval control or intensity control
• CPC Class Codes: G03F 7/70341 Details of immersion lithography aspects, e.g. exposure media or control of immersion liquid supply chemical composition of immersion liquids G03F7/2041
• CPC Class Codes: G03F 7/7055 Exposure light control in all parts of the microlithographic apparatus, e.g. pulse length control or light interruption
• CPC Class Codes: H01S 2301/02 ASE (amplified spontaneous emission), noise; Reduction thereof
• 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 3/0057 Temporal shaping, e.g. pulse compression, frequency chirping soliton generation and propagation G02F1/3513, H01S3/063 and H01S3/108
• CPC Class Codes: H01S 3/08004 incorporating a dispersive element, e.g. a prism for wavelength selection H01S3/0811, H01S3/08022 take precedence
• CPC Class Codes: H01S 3/08009 using a diffraction grating
• CPC Class Codes: H01S 3/083 Ring lasers fibre ring lasers H01S3/06791
• CPC Class Codes: H01S 3/10092 Coherent seed, e.g. injection locking
• CPC Class Codes: H01S 3/225 comprising an excimer or exciplex
• CPC Class Codes: H01S 3/2251 ArF, i.e. argon fluoride is comprised for lasing around 193 nm
• CPC Class Codes: H01S 3/2258 F2, i.e. molecular fluoride is comprised for lasing around 157 nm
• CPC Class Codes: H01S 3/2333 Double-pass amplifiers
• CPC Class Codes: H01S 3/2383 Parallel arrangements

Abstract

An apparatus/method may comprise a line narrowed pulsed lithography laser light source which may comprise: a seed pulse providing laser system which may comprise: a first pulsed seed laser producing seed pulses at a rate of X kHz; a second pulsed seed laser producing seed pulses at a rate of X kHz; an amplification system which may comprise: a first amplifier gain system which may comprise a first and a second pulsed gas discharge amplifier gain medium, each with a nominal center wavelength in the UV range, and each operating at ½X kHz on output pulses from the first seed laser; a second amplifier gain system which may comprise a first and a second pulsed amplifier gain medium, each with a nominal center wavelength in the UV range, and each operating at ½X kHz on output pulses from the second seed laser.

Claims

1. An apparatus comprising:

a plurality of pulsed laser light sources, each comprising;

a seed pulse providing laser system comprising a pulsed seed laser system producing a beam of seed pulses, and a beam splitter receiving the output of the seed laser system and providing a split output of every pulse from the beam splitter; and

an amplifier gain system comprising a first gas discharge amplifier gain medium operating at Y kHz on a respective output from the beam splitter and a second gas discharge amplifier gain medium operating at Z kHz on a respective output from the beam splitter, where Y+Z=X; and

at least one pulse combiner providing an output of laser pulses from the pulsed laser light sources at a pulse repetition rate of NX, where N is the total number of pulsed laser light sources in the apparatus.

2. An apparatus comprising:

a pulsed laser light source comprising;

a seed pulse providing laser system comprising a pulsed seed laser system producing a beam of seed pulses; and

a beam splitter receiving the output of the seed laser system and providing a split output of every pulse from the beam splitter; and

an amplifier gain system comprising a first gas discharge amplifier gain medium operating at Y kHz on a respective output from the beam splitter and a second gas discharge amplifier gain medium operating at Z kHz on a respective output from the beam splitter, where Y+Z=X; and

a pulse combiner combining the output pulses from the first and second amplifier gain systems to produce an output laser light pulse beam at a pulse repetition rate of X kHz;

wherein the beam splitter comprises a partially reflective optic reflecting a portion of each pulse in the pulse beam on one path and transmitting a portion of each pulse in the pulse beam on a second path.

3. The apparatus of claim 2 wherein the seed pulse providing system comprises an excimer gas discharge laser and a line narrowing module.

4. The apparatus of claim 2 wherein the beam splitter comprises a geometric beam splitter transmitting at least one spatial portion of the pulse beam on one path and at least a second portion of the pulse beam on a second path.

5. The apparatus of claim 2 wherein each gas discharge amplifier gain medium comprises a power amplifier.

6. The apparatus of claim 2 wherein each gas discharge amplification gain medium comprises a power oscillator.

7. The apparatus of claim 2 wherein each gas discharge amplification gain medium comprises a ring power amplification stage.

8. The apparatus of claim 2 wherein the pulse combiner comprises a beam combining optical element forming a laser light source output beam comprising a first spatially defined component from the first amplifier gain medium and a second spatially defined component from the second amplifier gain medium.

9. The apparatus of claim 2 wherein the pulse combiner comprises a beam combining optical element forming a laser light source output beam comprising a first component from the first amplifier gain medium and a second component from the second amplifier gain medium each exiting the pulse combiner along a path comprising a single optical axis.

10. The apparatus of claim 2 wherein each amplification stage is alternatively seeded by the pulsed seed laser system.

11. An apparatus comprising:

a pulsed laser light source comprising;

a seed pulse providing laser system comprising a pulsed seed laser system producing a beam of seed pulses; and

a beam splitter receiving the output of the seed laser system and providing a split output of every pulse from the beam splitter; and

an amplifier gain system comprising a first gas discharge amplifier gain medium operating at Y kHz on a respective output from the beam splitter and a second gas discharge amplifier gain medium operating at Z kHz on a respective output from the beam splitter, where Y+Z=X; and

a pulse combiner combining the output pulses from the first and second amplifier gain systems to produce an output laser light pulse beam at a pulse repetition rate of X kHz;

wherein the beam splitter comprises a stimulated optical path modulator that directs a first portion of a pulse in the pulse beam in a first path during a first time period and a second portion of a pulse on a second path during a second time period, or that directs alternating pulses on alternating ones of the first path and the second path in alternating time periods.

12. The apparatus of claim 11 wherein each gas discharge amplifier gain medium comprises a power amplifier.

13. The apparatus of claim 11 wherein each gas discharge amplification gain medium comprises a power oscillator.

14. The apparatus of claim 11 wherein each gas discharge amplification gain medium comprises a ring power amplification stage.

15. The apparatus of claim 11 wherein the pulse combiner comprises a beam combining optical element forming a laser light source output beam comprising a first spatially defined component from the first amplifier gain medium and a second spatially defined component from the second amplifier gain medium.

16. The apparatus of claim 11 wherein the pulse combiner comprises a beam combining optical element forming a laser light source output beam comprising a first component from the first amplifier gain medium and a second component from the second amplifier gain medium each exiting the pulse combiner along a path comprising a single optical axis.