Cymer, Inc.

George J Everage

Igor Vladimirovich Fomenkov

Richard L Sandstrom

Palash P Das

William N Partlo

John Martin Algots

Frederick G Erie

Daniel J W Brown

Robert N Jacques

Stuart L Anderson

Ronald L Spangler

Frederick A Palenschat

Electric discharge laser with active chirp correction. This application discloses techniques for moderating and dispensing these pressure waves. In some lasers small predictable patterns remain which can be substantially corrected with active wavelength control using relatively slow wavelength control instruments of the prior art. In a preferred embodiment a simple learning algorithm is described to allow advance tuning mirror adjustment in anticipation of the learned chirp pattern. Embodiments include stepper motors having very fine adjustments so that size of tuning steps are substantially reduced for more precise tuning. However, complete elimination of wavelength chirp is normally not feasible with structural changes in the laser chamber and advance tuning; therefore, Applicants have developed equipment and techniques for very fast active chirp correction. Improved techniques include a combination of a relatively slow stepper motor and a very fast piezoelectric driver. In another preferred embodiment chirp correction is made on a pulse-to-pulse basis where the wavelength of one pulse is measured and the wavelength of the next pulse is corrected based on the measurement. This correction technique is able to function at repetition rates as rapid as 2000 Hz and greater.

Electric discharge laser with active wavelength chirp correction

An electric discharge laser with fast wavelength correction. Fast wavelength correction equipment includes at least one piezoelectric drive and a fast wavelength measurement system and fast feedback response times. In a preferred embodiment, equipment is provided to control wavelength on a slow time frame of several milliseconds, on a intermediate time from of about one to three millisecond and on a very fast time frame of a few microseconds. Techniques include a combination of a relatively slow stepper motor and a very fast piezoelectric driver for tuning the laser wavelength using a tuning mirror. A preferred control technique is described (utilizing a very fast wavelength monitor) to provide the slow and intermediate wavelength control and a piezoelectric load cell in combination with the piezoelectric driver to provide the very fast (few microseconds) wavelength control.

Laser wavelength control unit with piezoelectric driver

Electric discharge laser with fast chirp correction. Fast wavelength chirp correction equipment includes at least one piezoelectric drive and a fast wavelength detection means and has a feedback response time of less than 1.0 millisecond. In a preferred embodiment a simple learning algorithm is described to allow advance tuning mirror adjustment in anticipation of the learned chirp pattern. Techniques include a combination of a relatively slow stepper motor and a very fast piezoelectric driver. In another preferred embodiment chirp correction is made on a pulse-to-pulse basis where the wavelength of one pulse is measured and the wavelength of the next pulse is corrected based on the measurement. This correction technique is able to function at repetition rates as rapid as 2000 Hz and greater.

Fast wavelength correction technique for a laser

A wavelength shift correction system for a laser system is provided for correcting wavelength chirps. This wavelength shift correction system includes a learning algorithm that learns characteristics of a wavelength chirp from a laser and a computer system that executes the learning algorithm and provides wavelength correction control signals based on the learned characteristics to reduce the magnitude of the wavelength shift of the present wavelength chirp and subsequent wavelength chirps.

Wavelength shift correction technique for a laser

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Escondido, CA, United States of America

George J Everage