Reducing speckle in an excimer light source
First Claim
Patent Images
1. A method comprising:
- producing a light beam made up of pulses having a wavelength in a deep ultraviolet range, each pulse having a first temporal coherence defined by a first temporal coherence length and each pulse being defined by a pulse duration;
for each pulse in a plurality of pulses in the light beam, modulating an optical phase over the pulse duration of the pulse to produce a modified pulse having a second temporal coherence defined by a second temporal coherence length that is less than the first temporal coherence length of the pulse;
forming a light beam of pulses at least from the produced modified pulses; and
directing the formed light beam of pulses toward a substrate within a lithography exposure apparatus.
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Abstract
A method includes: producing a light beam made up of pulses having a wavelength in the deep ultraviolet range, each pulse having a first temporal coherence defined by a first temporal coherence length and each pulse being defined by a pulse duration; for one or more pulses, modulating the optical phase over the pulse duration of the pulse to produce a modified pulse having a second temporal coherence defined by a second temporal coherence length that is less than the first temporal coherence length of the pulse; forming a light beam of pulses at least from the modified pulses; and directing the formed light beam of pulses toward a substrate within a lithography exposure apparatus.
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Citations
42 Claims
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1. A method comprising:
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producing a light beam made up of pulses having a wavelength in a deep ultraviolet range, each pulse having a first temporal coherence defined by a first temporal coherence length and each pulse being defined by a pulse duration; for each pulse in a plurality of pulses in the light beam, modulating an optical phase over the pulse duration of the pulse to produce a modified pulse having a second temporal coherence defined by a second temporal coherence length that is less than the first temporal coherence length of the pulse; forming a light beam of pulses at least from the produced modified pulses; and directing the formed light beam of pulses toward a substrate within a lithography exposure apparatus. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. An apparatus comprising:
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a light source configured to produce a light beam made up of pulses having a wavelength in a deep ultraviolet range, each pulse having a first temporal coherence defined by a first temporal coherence length and each pulse being defined by a pulse duration; a phase modulator system in a path of the light beam of pulses, configured to, for each pulse in a plurality of pulses in the light beam, modulate an optical phase over the pulse duration of the pulse to produce a modified pulse having a second temporal coherence defined by a second temporal coherence length that is less than the first temporal coherence length; a measurement apparatus configured to measure a characteristic of a test pulse, wherein the test pulse is either a pulse having the first temporal coherence or the modified pulse having the second temporal coherence; and a control system in communication with the measurement apparatus and the phase modulator system, the control system configured to; receive the measured characteristic of the test pulse from the measurement apparatus; determine whether a bandwidth of the modified pulse is within a range of a target bandwidth based on the received measured characteristic; and if it is determined that the bandwidth of the modified pulse is outside the range of the target bandwidth, then adjust a frequency at which the optical phase over the pulse duration of the pulse that produces the modified pulse is modulated. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41)
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42. An apparatus comprising:
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a phase modulator system in a path of a light beam of pulses having a wavelength in a deep ultraviolet range, the phase modulator system is configured to, for each pulse in a plurality of pulses of the light beam, modulate an optical phase over a pulse duration of the pulse to produce a modified pulse having a second temporal coherence length that is less than a first temporal coherence length of the pulse before it has been modulated; a measurement apparatus configured to measure a characteristic of a test pulse, wherein the test pulse is either a pulse having the first temporal coherence or the modified pulse having the second temporal coherence; and a control system in communication with the measurement apparatus and the phase modulator system, the control system configured to; receive the measured characteristic of the test pulse from the measurement apparatus; determine whether a bandwidth of the modified pulse is within a range of a target bandwidth based on the received measured characteristic; and if it is determined that the bandwidth of the modified pulse is outside the range of the target bandwidth, then adjust a frequency at which the optical phase over the pulse duration of the pulse that produces the modified pulse is modulated.
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Specification