Cymer, Inc.

Holger K Glatzel

John T Melchior

Rajasekhar Rao

R Kyle Webb

Xiaojiang Jason Pan

Alexander Igorevich Ershov

Richard L Sandstrom

Palash P Das

Richard G Morton

Richard C Ujazdowski

David J Warkentin

John Martin Algots

Thomas A Yager

Walter Dale Gillespie

Vladimir B Fleurov

Raymond F Cybulski

Alexei Lukashev

William N Partio

Leonard Lublin

Khurshid Ahmed

Gregory Francis

Elizabeth Marsh

Jeremy Tyler

Matthew Ball

A wavemeter and method for measuring bandwidth for a high repetition rate gas discharge laser having an output laser bean comprising a pulsed output of greater than or equal to 15 mJ per pulse, sub-nanometer bandwidth tuning range pulses having a femptometer bandwidth precision and tens of femptometers bandwidth accuracy range, for measuring bandwidth on a pulse to pulse basis at pulse repetition rates of 4000 Hz and above, is disclosed which may comprise a focusing lens having a focal length; an optical interferometer creating an interference fringe pattern; an optical detection means positioned at the focal length from the focusing lens; and a bandwidth calculator calculating bandwidth from the position of interference fringes in the interference fringe pattern incident on the optical detection means, defining a Dand a D, the respective distances between a pair of first fringe borders and between a pair of second fringe borders in the interference pattern on an axis of the interference pattern, and according to the formula &#x394;&#x3bb;=&#x3bb;[D&#x2212;D]/[8f&#x2212;D], where &#x3bb;is an assumed constant wavelength and D=(D&#x2212;D)/2, and f is the focal length. The optical detector may be a photodiode array. The wavemeter may have an optical interferometer having a slit function; the slit function and the focal length being selected to deliver to the optical detector the two innermost fringes of the optical interference ring pattern. The optical detector may comprise an array of pixels each having a height and width and the array having a total width; and an aperture at the optical input to the optical interferometer may selectively input to the optical interferometer a portion of a beam of light sufficient for the output of the etalon to illuminate the optical detector over the height of each respective pixel height and the total width. The optical interferometer may comprise an etalon having a slit function of 3 pm or less and a finesses of 25 or greater; and the focal length may be 1.5 meters. A second stage diffuser may be placed between the first stage diffuser and the etalon delivering a narrow cone of light to the etalon, and an aperture between the second stage diffuser and the etalon may deliver to the etalon a thin strip of the narrow cone of light.

Gas discharge MOPA laser spectral analysis module

A beam delivery unit and method of delivering a laser beam from a laser light source for excimer or molecular fluorine gas discharge laser systems in the DUV and smaller wavelengths is disclosed, which may comprise: a beam delivery enclosure defining an output laser light pulse beam delivery pat from an output of a gas discharge laser to an input of a working apparatus employing the light contained in the output laser light pulse beam; a purge mechanism operatively connected to the beam delivery enclosure; an in-situ beam parameter monitor and adjustment mechanism within the enclosure, comprising a retractable bean redirecting optic; a beam analysis mechanism external to the enclosure; and, a retraction mechanism within the enclosure and operable from outside the enclosure and operative to move the retractable beam redirecting optic from a retracted position out of the beam path to an operative position in the beam path. The BDU may also include a beam attenuator unit contained within the enclosure adjustably mounted within the enclosure for positioning within the beam delivery pat. The BDU may have at least two enclosure isolation mechanisms comprising a first enclosure isolation mechanism on a first side of the enclosure from the at least one optic module and a second enclosure isolation mechanism on a second side of the enclosure from the at least one optic module, each respective enclosure isolation mechanism comprising a flapper valve having a metal to metal seating mechanism and a locking pin assembly. A precision offset ratchet driver operative to manipulate actuator mechanisms in difficult to reach locations may be provided. An external kinematic alignment tool may be provided. A method of contamination control for a BDU is disclosed comprising selection of allowable materials and fabrication processes.

Gas discharge laser light source beam delivery unit

A wavemeter and method for measuring bandwidth for a high repetition rate gas discharge laser having an output laser bean comprising a pulsed output of greater than or equal to 15 mJ per pulse, sub-nanometer bandwidth tuning range pulses having a femptometer bandwidth precision and tens of femptometers bandwidth accuracy range, for measuring bandwidth on a pulse to pulse basis at pulse repetition rates of 4000Hz and above, is disclosed which may comprise a focusing lens having a focal length; an optical interferometer creating an interference fringe pattern; an optical detection means positioned at the focal length from the focusing lens; and a bandwidth calculator calculating bandwidth from the position of interference fringes in the interference fringe pattern incident on the optical detection means, defining a Dand a DO, the respective distances between a pair of first fringe borders and between a pair of second fringe borders in the interference pattern on an axis of the interference pattern, and according to the formula &#x394;&#x3bb;=&#x3bb;[D&#x2212;D]/[8f&#x2212;D], where &#x3bb;is an assumed constant wavelength and D=(D&#x2212;D)/and f is the focal length. The optical detector may be a photodiode array. The wavemember may have an optical interferometer having a slit function; the slit function and the focal length being selected to deliver to the optical detector the two innermost fringes of the optical interference ring pattern. The optical detector may comprise an array of pixels each having a height and width and the array having a total width; and an aperture at the optical input to the optical interferometer may selectively input to the optical interferometer a portion of a beam of light sufficient for the output of the etalon to illuminate the optical detector over the height of each respective pixel height and the total width. The optical interferometer may comprise an etalon having a slit function of 3 pm or less and a finesses of 25 or greater; and the focal length may be 1.5 meters. A second stage diffuser may be placed between the first stage diffuser and the etalon delivering a narrow cone of light to the etalon, and an aperture between the second stage diffuser and the etalon may deliver to the etalon a thin strip of the narrow cone of light.

The present invention provides long life optics for a modular, high repetition rate, ultraviolet gas discharge laser systems producing a high repetition rate high power output beam. The invention includes solutions to a surface damage problem discovered by Applicants on CaFoptics located in high pulse intensity sections of the output beam of prototype laser systems. Embodiments include an enclosed and purged beam path with beam pointing control for beam delivery of billions of output laser pulses. Optical components and modules described herein are capable of controlling ultraviolet laser output pulses with wavelength less than 200 nm with average output pulse intensities greater than 1.75&#xd7;10Watts/cmand with peak intensity or greater 3.5&#xd7;10Watts/cmfor many billions of pulses as compared to prior art components and modules which failed after only a few minutes in these pulse intensities. Techniques and components are disclosed for minimizing the potential for optical damage and for reducing the pulse energy density to less than 100&#xd7;10J/cm. Important improvements described in this specification have been grouped into the following subject matter categories: (1) Solution to CaFsurface damage discovered by Applicants, (2) description of a high power ArF MOPA laser system, (3) description of beam delivery units, (4) polarization considerations (5) a high speed water-cooled auto shutter energy detector module and (6) other improvements.

High power deep ultraviolet laser with long life optics

A spectral analysis module, including a wavemeter, for a high repetition rate gas discharge laser having a laser output beam comprising a pulsed output of greater than or equal to 15 mJ per pulse, sub-nanometer bandwidth tuning range pulses having a femptometer bandwidth precision and tens of femptometers bandwidth accuracy range, for measuring bandwidth on a pulse to pulse basis at pulse repetition rates of 4000 Hz and above, is disclosed which may comprise a primary beam-splitter in the path of the laser output laser of the gas discharge laser operative to pass the vast majority of the output beam and to reflect a first small portion of the output beam, the primary beam splitter oriented at an angle to sufficiently reduce the fluence on the primary beam-splitter, and creating overlapping fresnel reflections in the first small portion of the laser output beam; a secondary beam splitter made from a material having a damage threshold sufficiently high to tolerate the fluence created by the overlapping portion of the fresnel reflections in the first small portion of the output laser beam, the secondary beam splitter reflecting the vast majority of the first small portion of the output laser beam and passing a second small portion of the output laser beam; a telescoping optic in the path of the second small portion of the output beam operative to demagnify the second small portion of the output beam onto a first stage diffuser receiving the demagnified second small portion of the output laser beam, the demagnification selected to keep the fluence in the overlapping fresnel reflections in the second small portion of the output laser beam below the damage threshold of the first stage diffuser. The telescoping optic may demagnify a long axis of the second small portion of the output laser beam more than a short axis of the second small portion of the output laser beam, redistributing the fluence of the second small portion of the laser output beam across the first stage diffuser to keep any portion of the first stage diffuser from exceeding the damage threshold for the material from which the first stage diffuser is made. The vast majority of the first small portion of the laser output beam may be reflected into a power detection module. A second stage diffuser may creating a narrow cone of a focused second small portion of the laser output beam before the beam enters an interferometer.

The present invention provides a gas discharge ultraviolet laser capable of producing a high quality pulsed ultraviolet laser beam at pulse rates greater than 2000 Hz at pulse energies at 5 mJ or greater and having an enclosed beam path at least a portion of which comprises an oxidation agent. In a preferred embodiment a portion of the beam path comprises a sealed chamber containing a gas comprising a small concentration of oxygen. In one preferred embodiment the sealed chamber is an etalon chamber and the contained gas is nitrogen with an oxygen concentration of between 1.6 and 2.4 percent. In another preferred embodiments a small concentration of oxygen is added to the purge gas of a special purge compartment containing optical components exposed to high intensity output laser beam.

Gas discharge ultraviolet laser with enclosed beam path with added oxidizer

Growing community of inventors

San Diego, CA, United States of America

Holger K Glatzel