Cymer, Inc.

Asml Netherlands B.v.

Tanuj Aggarwal

Kevin M O'Brien

Herman Philip Godfried

Joshua Jon Thornes

Frank Everts

Russell Allen Burdt

Rahul Ahlawat

Wilhelmus Patrick Elisabeth Maria Op 't Root

Leon Pieter Paul Saanen

Methods and apparatus for controlling laser firing timing and hence bandwidth in a laser capable of operating at any one of multiple repetition rates.

Lithography system bandwidth control

Online calibration of laser performance as a function of the repetition rate at which the laser is operated is disclosed. The calibration can be periodic and carried out during a scheduled during a non-exposure period. Various criteria can be used to automatically select the repetition rates that result in reliable in-spec performance. The reliable values of repetition rates are then made available to the scanner as allowed values and the laser/scanner system is then permitted to use those allowed repetition rates.

Online calibration for repetition rate dependent performance variables

In a method, energy is supplied to a first gas discharge chamber of a first stage until a pulsed amplified light beam is output from the first stage and directed toward a second stage. While the energy is supplied to the first gas discharge chamber: a value of an operating parameter of the first gas discharge chamber is measured; it is determined whether to adjust an operating characteristic of the first gas discharge chamber based on the measured value; and, the operating characteristic of the first gas discharge chamber is adjusted if it is determined that the operating characteristic of the first gas discharge chamber should be adjusted. After it is determined that the operating characteristic of the first gas discharge chamber no longer should be adjusted, then an adjustment procedure is applied to an operating characteristic of a second gas discharge chamber of the second stage.

Gas optimization in a gas discharge light source

A method of controlling output of a radiation source, the method including: periodically monitoring an output energy of the radiation source; determining a difference between a reference energy signal and the monitored output energy; determining a feedback value; determining a desired output energy of the radiation source for a subsequent time period; and controlling an input parameter of the radiation source in dependence on the determined desired output energy during the subsequent time period. If the magnitude of the determined difference between the monitored output energy of the radiation source and the reference energy signal exceeds a threshold value: the determined difference does not contribute to the feedback value; and the determined difference is spread over the subsequent time period according to a reference energy signal adjustment profile and the reference energy signal adjustment profile is added to the reference energy signal for the subsequent time period.

Lithographic apparatus and method

A method and apparatus for controlling a dose of radiation generated by a laser light source is disclosed. In one embodiment, a dose controller receives measurements of the deviation of output energy from an expected output energy, or 'energy sigma,' and the standard deviation of the error in the dose received by the item being processed from the desired dose. The ratio of the energy sigma to the standard deviation of dose error is calculated, and the laser controller adjusts the controller gain based upon the calculated ratio so as to adjust the voltage determined by the controller, and consequently the output energy and thus the dose to the item. This is an improvement over the prior art, in which the controller gain is adjusted based upon sending a voltage dither to the laser and correlating it to its response in energy at only one frequency.

Method for dither free adaptive and robust dose control for photolithography

A gas discharge light source includes a gas discharge system that includes one or more gas discharge chambers. Each of the gas discharge chambers in the gas discharge system is filled with a respective gas mixture. For each gas discharge chamber, a pulsed energy is supplied to the respective gas mixture by activating its associated energy source to thereby produce a pulsed amplified light beam from the gas discharge chamber. One or more properties of the gas discharge system are determined. A gas maintenance scheme is selected from among a plurality of possible schemes based on the determined one or more properties of the gas discharge system. The selected gas maintenance scheme is applied to the gas discharge system. A gas maintenance scheme includes one or more parameters related to adding one or more supplemental gas mixtures to the gas discharge chambers of the gas discharge system.

Gas mixture control in a gas discharge light source

An indication of an output of an optical source of a photolithography system is accessed; an indication of an input provided to the optical source is accessed, the provided input being associated with the accessed indication of the output of the optical source; an output error is determined from an expected amount of output and the accessed indication of the output of the optical source; a local gain associated with the accessed indication of the input provided to the optical source is estimated; a gain error is determined from the estimated local gain and an expected local gain; a current value of one or more operating metrics of the optical source is estimated based on one or more of the output error and the gain error; and a gain relationship for the optical source is updated based on the estimated current value of the one or more operating metrics.

Estimating a gain relationship of an optical source

A lithography system includes an optical source configured to emit a pulsed light beam; a lithography apparatus including an optical system, the optical system being positioned to receive the pulsed light beam from the optical source at a first side of the optical system and to emit the pulsed light beam at a second side of the optical system; and a control system coupled to the optical source and the optical lithography apparatus, the control system configured to: receive an indication of an amount of energy in the pulsed light beam at the second side of the optical system, determine an energy error, access an initial control sequence, the initial control sequence being associated with the optical source, determine a second control sequence based on the determined energy error and the initial control sequence, and apply the second control sequence to the optical source.

Controller for an optical system

One or more operating characteristics of a light source are adjusted by estimating a plurality of extreme values of operating parameters of the light source while operating the light source under a set of extreme test conditions. For each extreme test condition, a group of pulses of energy is supplied to a first gas discharge chamber of the light source while operating the first gas discharge chamber under the extreme test condition to produce a first pulsed amplified light beam; a group of pulses of energy is supplied to a second gas discharge chamber of the light source while operating the second gas discharge chamber under the extreme test condition to produce a second pulsed amplified light beam. An extreme value of an operating parameter for the extreme test condition is measured to thereby estimate the extreme value of the operating parameter.

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San Diego, CA, United States of America

Tanuj Aggarwal