Lithographic method
AssigneeASML Netherlands B.V.
InventorsWouter Joep Engelen, Otger Jan Luiten, Andrey Alexandrovich Nikipelov, Vadim Yevgenyevich Banine, Pieter Willem Herman De Jager, Erik Roelof Loopstra
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Abstract
A method of patterning lithographic substrates, the method including using a free electron laser to generate EUV radiation and delivering the EUV radiation to a lithographic apparatus which projects the EUV radiation onto lithographic substrates, wherein the method further includes reducing fluctuations in the power of EUV radiation delivered to the lithographic substrates by using a feedback-based control loop to monitor the free electron laser and adjust operation of the free electron laser accordingly.
Claims27
A free electron laser, comprising:
- an electron source configured to produce an electron beam comprising a plurality of bunches of relativistic electrons;
- an undulator arranged to receive the electron beam and guide it along a periodic path so that the electron beam interacts with radiation within the undulator, stimulating emission of radiation and providing a radiation beam;
- and
- an adjustable compressor configured to control at least one selected from:
- (i) a charge density distribution of one or more electron bunches of the plurality of electron bunches along a direction of propagation of the electron beam before it enters the undulator;
- or (ii) an average energy of one or more electron bunches of the plurality of electron bunches before it enters the undulator.
An apparatus comprising:
- a radiation source configured to produce radiation, the radiation source comprising an adjustment mechanism configured to control a wavelength of the radiation;
- an optical system arranged to guide the radiation from the radiation source to a target location for receipt of the radiation, the optical system having a wavelength dependent transmittance or reflectance;
- a controller;
- and
- a sensor configured to determine a value indicative of a power of the radiation, or indicative of a dose of radiation delivered to the target location by the radiation, and to output a signal indicative thereof to the controller,
- wherein the controller is configured to vary the wavelength of the radiation using the adjustment mechanism in response to the signal output by the sensor.
A free electron laser, comprising:
- an electron source configured to produce an electron beam comprising a plurality of bunches of relativistic electrons, the electron beam having a first frequency;
- an undulator arranged to receive the electron beam and guide it along a periodic path so that the electron beam interacts with radiation within the undulator, stimulating emission of radiation and providing a radiation beam;
- and
- an adjustable resonant cavity arranged between the electron source and the undulator and arranged to operate at a second frequency such that a chirp of electron bunches of the plurality of the electron bunches and/or an average energy of electrons in electron bunches of the plurality of electron bunches, varies with time.
Dependencies are inferred from the claim text.