Northrop Grumman Systems Corporation

University of Central Florida Research Foundation Inc

Trw Limited

Rocco A Orsini

Michael B Petach

Roy D McGregor

Steven W Fornaca

Henry Shields

Mark E Michaelian

Robert A Bunnell

A laser-plasma EUV radiation source () that employs one or more approaches for preventing vaporization of material from a nozzle assembly () of the source () by electrical discharge from the plasma (). The first approach includes employing an electrically isolating nozzle end, such as a glass capillary tube (). The tube () extends beyond all of the conductive surfaces of the nozzle assembly () by a suitable distance so that the pressure around the closest conducting portion of the nozzle assembly () is low enough not to support arcing. A second approach includes providing electrical isolation of the conductive portions of the source () from the vacuum chamber wall. A third approach includes applying a bias potential () to the nozzle assembly () to raise the potential of the nozzle assembly () to the potential of the arc.

Erosion reduction for EUV laser produced plasma target sources

An EUV radiation source that creates a stable solid target filament. The source includes a nozzle assembly having a condenser chamber for cryogenically cooling a gaseous target material into a liquid state. The liquid target material is forced through an orifice of a target filament generator into an evaporation chamber as a liquid target stream. The evaporation chamber has a higher pressure than a vacuum process chamber of the source to allow the liquid target material to freeze into a target filament in a stable manner. The frozen target filament is emitted from the evaporation chamber into the process chamber as a stable target filament towards a target area. The higher pressure in the evaporation chamber can be the result of the evaporative cooling of the target material alone or in combination with a supplemental gas.

Droplet and filament target stabilizer for EUV source nozzles

An EUV radiation source that creates a stable solid filament target. The source includes a nozzle assembly having a condenser chamber for cryogenically cooling a gaseous target material into a liquid state. The liquid target material is filtered by a filter and sent to a holding chamber under pressure. The holding chamber allows entrained gas bubbles in the target material to be condensed into liquid prior to the filament target being emitted from the nozzle assembly. The target material is forced through a nozzle outlet tube to be emitted from the nozzle assembly as a liquid target stream. A thermal shield is provided around the outlet tube to maintain the liquid target material in the cryogenic state. The liquid target stream freezes and is vaporized by a laser beam from a laser source to generate the EUV radiation.

Low vapor pressure, low debris solid target for EUV production

An EUV radiation source ( ) that employs a steering device ( ) for steering a stream ( ) of droplets ( ) generated by a droplet generator ( ) so that the droplet ( ) are directed towards a target location ( ) to be vaporized by a laser beam ( ). The direction of the stream ( ) of droplets ( ) is sensed by a sensing device ( ). The sensing device ( ) sends a signal to an actuator ( ) that controls the orientation of the steering device ( ) so that the droplets ( ) are directed to the target location ( ).

Target steering system for EUV droplet generators

An EUV radiation source ( ) that generates a sheet ( ) of a liquid target material that has a width that matches the desired laser spot size ( ) for good conversion efficiency and a thickness that matches the laser beam/target interaction depth. The EUV source ( ) includes a reservoir ( ) containing a pressurized cryogenic liquid target material, such as liquid Xenon. The reservoir ( ) also includes an array ( ) of closely spaced orifices ( ). The liquid target material is forced through the orifices ( ) into a vacuum chamber as separated liquid stream filaments ( ) of the target material that define the sheet ( ). The liquid streams freeze to form an array of frozen target filaments ( ). A laser beam ( ) is directed to a target area ( ) in the vacuum chamber where it irradiates the stream of filaments ( ) to create a plasma ( ) that emits EUV radiation ( ).

Linear filament array sheet for EUV production

A target material delivery system in the form of a nozzle ( ) for an EUV radiation source ( ). The nozzle ( ) includes a target material supply line ( ) having an orifice ( ) through which droplets ( ) of a liquid target material ( ) are emitted, where the droplets ( ) have a predetermined size, speed and spacing therebetween. The droplets ( ) are mixed with a carrier gas ( ) in a mixing chamber ( ) enclosing the target material chamber ( ) and the mixture of the droplets ( ) and the carrier gas ( ) enter a drift tube ( ) from the mixing chamber ( ). The droplets ( ) are emitted into an accelerator chamber ( ) from the drift tube ( ) where the speed of the droplets ( ) is increased to control the spacing therebetween. A vapor extractor ( ) can be mounted to the accelerator chamber ( ) or the drift tube ( ) to remove the carrier gas ( ) and target material vapor, which would otherwise adversely affect the EUV radiation generation.

Gasdynamically-controlled droplets as the target in a laser-plasma extreme ultraviolet light source

A nozzle ( ) for a laser-plasma EUV radiation source that provides thermal isolation between the nozzle body ( ) and the target material flowing therethrough. A target delivery tube ( ) is provided that extends through the nozzle body ( ). The delivery tube ( ) has an expansion aperture ( ) positioned behind an exit collimator ( ) of the nozzle body ( ). The delivery tube ( ) is made of a low thermal conductivity material, such as stainless steel, and is in limited contact with the nozzle body ( ) so that heating of the nozzle body ( ) from the plasma does not heat the liquid target material being delivered through the delivery tube ( ). The expansion aperture ( ) has a smaller diameter than the exit collimator ( ).

High temperature EUV source nozzle

An EUV source ( ) that delivers a laser beam ( ) asymmetrical relative to first collection optics ( ). The first collection optics ( ) has an opening ( ) for the laser beam ( ) that is positioned so that the laser beam ( ) is directed towards the plasma off-axis relative to the collection optics ( ). Thus, the strongest EUV radiation ( ) is not blocked by the target production hardware ( ).

High output extreme ultraviolet source

A laser-plasma EUV radiation source (,) that generates larger liquid droplets (,) for the plasma target material. The EUV source (,) forces a liquid (,), preferably Xenon, through a nozzle (,), instead of forcing a gas through the nozzle. The geometry of the nozzle (,) and the pressure of the liquid (,) through the nozzle (,) atomizes the liquid (,) to form a dense spray (,) of droplets (,). Because the droplets (,) are formed from a liquid, they are larger in size, and are more conducive to generating EUV radiation. A condenser (,) is used to convert gaseous Xenon (,) to the liquid (,) prior to being forced through the nozzle (,).

Growing community of inventors

Long Beach, CA, United States of America

Rocco A Orsini