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US 2019/0155170 A1Published application
Lithography system bandwidth control
AssigneeCymer, Inc.
InventorTanuj Aggarwal
Life of this patent
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Abstract
Methods and apparatus for controlling laser firing timing and hence bandwidth in a laser capable of operating at any one of multiple repetition rates.
Claims22
Apparatus comprising:
- a laser configured to operate at any one of a plurality of repetition rates;
- a bandwidth controller configured to generate a control signal to at least partially control a bandwidth of the laser;
- a correlator comprising electronically stored feedforward correlation data correlating a value of the control signal to a repetition rate for each of the plurality of repetition rates;
- and
- a module configured to determine at least one operating parameter of the laser and for supplying the determined operating parameter to the correlator as a feedforward value,
- wherein the correlator is configured to generate an adjustment to the control signal based at least in part on the feedforward value.
3 more elements
A method comprising the steps of:
- determining a current repetition rate at which a laser is firing;
- determining if the current repetition rate is substantially the same as an immediately prior repetition rate;
- and
- altering an control parameter of the laser if it is determined that the current repetition rate is not substantially the same as the immediately prior repetition rate.
1 more element
A method comprising the steps of:
- detecting a change in a repetition rate for a laser capable of operating at any one of a plurality of repetition rates;
- computing a first operating parameter of the laser since the detected change in repetition rate;
- and
- updating, at least partially based on the computed first operating parameter, electronically stored correlation data correlating a value of a second operating parameter to a repetition rate for each of the plurality of repetition rates.
1 more element
A method comprising the steps of:
- determining whether a control parameter is sufficiently different from a saturation value of the control parameter;
- and
- adding an offset value to an operating parameter which adjusts the control parameter if it is determined that the control parameter is not sufficiently different from a saturation value of the control parameter to obtain an adjusted control parameter that is sufficiently different from the saturation value.
A method comprising the steps of:
- detecting the current repetition rate for a laser capable of operating at any one of a plurality of repetition rates;
- and
- adjusting an operating parameter such that a control parameter is close to a reference value for the current repetition rate.
Dependencies are inferred from the claim text.