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Avco Research Laboratories

Malcolm W McGeoch

A rectangular electrical pulse enters a transmission line structure with single pass transit time equal to ½ the duration of the pulse, open circuit at the extreme end and a switch at its center. After a delay equal to ¾ of the rectangular pulse duration the central switch is closed to couple the contents of the transmission line structure into another transmission line of half impedance. The output pulse maintains the initial voltage, but is of half the initial duration, and double the initial power.

Electrical pulse compression circuit

A laser-produced plasma extreme ultraviolet source has a buffer gas to slow ions down and thermalize them in a low-temperature plasma. The plasma is initially trapped in a mirror magnetic field configuration with a low magnetic field barrier to axial motion. Plasma overflows axially at each end of the mirror into magnetic cusps and is conducted by radial magnetic field lines to annular beam dumps disposed around the waist of each cusp.

Extreme ultraviolet source with dual magnetic cusp particle catchers

A laser-produced plasma extreme ultraviolet source has a buffer gas to slow ions down and thermalize them in a low temperature plasma. The plasma is initially trapped in a symmetrical cusp magnetic field configuration with a low magnetic field barrier to radial motion. Plasma overflows in a full range of radial directions and is conducted within a cone-shaped sheet to an annular beam dump.

Extreme ultraviolet source with magnetic cusp plasma control

A laser-produced plasma extreme ultraviolet source has a buffer gas to slow ions down and thermalize them in a low temperature plasma. The plasma is initially trapped in a symmetrical cusp magnetic field configuration with a low magnetic field barrier to radial motion. Plasma overflows in a full range of radial directions and is conducted by radial field lines to a large area annular array of beam dumps.

A plasma pinch extreme ultraviolet source using lithium vapor requires surrounding surfaces that are heated or cooled in order to evaporate the desired quantity of lithium, typically setting the vapor pressure of lithium at a pressure of a few torr. Two distinct surfaces within the whole set are designated as the electrodes that emit and receive the high current of the plasma pinch. A method is described whereby the temperature of these designated electrode surfaces is manipulated in order to condense lithium and provide a liquid metal protective layer to absorb both plasma and extreme ultraviolet heat thereby controlling electrode erosion. A further method is described that provides a protective flow of liquid lithium exactly on the axis of the pair of discharge electrodes.

Lithium extreme ultraviolet source and operating method

The successful use of lithium vapor in an extreme ultraviolet (EUV) light source depends upon an intense localized heat source at the center of conical structures that evaporate, condense and re-supply liquid lithium. Induction heating of a hollow structure with toroidal topology via an internal helical field coil, can supply intense heat at its innermost radius. The resulting slim radio frequency heated structure has high optical transmission from a central EUV producing plasma to collection mirrors outside of the structure, improving EUV source efficiency and reliability.

Induction heated buffer gas heat pipe for use in an extreme ultraviolet source

A magnetically shielded, efficient plasma generation configuration for a pulsed discharge extreme ultraviolet (EUV) light source comprises two opposed convex electrodes mounted with axes parallel to a static magnetic field. A limiter aperture disposed between the electrodes, in conjunction with the field lines, defines a hollow plasma cylinder connecting the electrodes. A high pulsed voltage and current compresses the plasma cylinder and its interior magnetic field onto the electrode surfaces to create a magnetic insulating layer at the same time as propelling the working gas from each side toward the space between the electrode tips. The plasma then collapses radially in a three-dimensional compression to form a dense plasma on the axis of the device with radiation of extreme ultraviolet light.

Pulsed discharge extreme ultraviolet source with magnetic shield

A self-magnetically confined lithium plasma which also may have an applied axial magnetic field is irradiated at sub-critical density by a carbon dioxide laser to generate extreme ultraviolet photons at the wavelength of 13.5 nm with high efficiency, high power and small source size.

Laser heated discharge plasma EUV source

Small, high velocity liquid metal droplets are produced for applications that require the accurate and remote placement of small quantities of a metal. The magnetic pressure of current flowing through liquid metal is used to force small quantities of liquid metal through an orifice. Examples of applications are to feed metal fuel into plasma extreme ultraviolet sources, and to place solder bumps on an integrated circuit prior to the attachment of connections.

Liquid metal droplet generator

An extreme ultraviolet source with wide-angle vapor containment and reflux is described. In the optical output directions radiating from the source plasma there is an array of tapered buffer gas heat pipes, with wick structures in the walls. In directions toward the insulators separating the discharge electrodes there are disc-shaped buffered gas heat pipes that prevent metal vapor from condensing on these insulators. A preferred electrode configuration has three electrode discs that operate in the star pinch mode. Another electrode configuration comprises two electrode discs and supports a pseudospark discharge. The star pinch variant of this source has efficiently generated 13.5 nm radiation with lithium vapor and helium buffer gas.

Extreme ultraviolet source with wide angle vapor containment and reflux

An optically addressed extreme ultraviolet (EUV) modulator in which a spatial amplitude or phase pattern is provided to an EUV beam that is reflected from, or transmitted through the modulator. The modulator includes a modulator structure that includes a material with a high coefficient of thermal expansion. When a thermal impulse is incident on one part of the modulator, the resulting expansion changes the reflected phase or amplitude of the EUV beam from that part. A thermal pattern is imprinted on the modulator by absorption of a visible or ultraviolet pattern, resulting in a corresponding modulation of the EUV beam. A lithography system is based on the optically addressed EUV modulator.

Optically addressed extreme ultraviolet modulator and lithography system incorporating modulator

A source of extreme ultraviolet or soft X-ray photon source includes discharge chamber containing a buffer gas, first and second electrodes in the discharge chamber configured to deliver a heating current to a plasma discharge region, and an injector to project a particle of a working substance into the plasma discharge region. The particle is evaporated and ionized by the heating current to form a hot plasma that radiates extreme ultraviolet or soft X-ray photons.

Injection pinch discharge extreme ultraviolet source

A source of photons or neutrons includes a housing that defines a discharge chamber, a first group of ion beam sources directed toward a plasma discharge region in the discharge chamber, the first group of ion beam sources including a first electrode and an inner shell, and a second electrode spaced from the plasma discharge region. The source of photons or neutrons further includes a first power supply for energizing the first group of ion beam sources to electrostatically accelerate toward the plasma discharge region ion beams which are at least partially neutralized before they enter the plasma discharge region, and a second power supply coupled between the first and second electrodes for delivering a heating current to the plasma discharge region. The ion beams and the heating current form a hot plasma that radiates photons or neutrons. The source of photons or neutrons may further include a second group of ion beam sources. The photons may be in the soft X-ray or extreme ultraviolet wavelength range and, in one embodiment, have wavelengths in a range of about 10-15 nanometers.

Star pinch plasma source of photons or neutrons

A source of photons includes a discharge chamber, first and second groups of ion beam sources in the discharge chamber and a neutralizing mechanism. Each of the ion beam sources electrostatically accelerates a beam of ions of a working gas toward a plasma discharge region. The first group of ion beam sources acts as a cathode and the second group of ion beam sources acts as an anode for delivering a heating current to the plasma discharge region. The neutralizing mechanism at least partially neutralizes the ion beams before they enter the plasma discharge region. The neutralized beams and the heating current form a hot plasma that radiates photons. The photons may be in the soft x-ray or extreme ultraviolet wavelength range and, in one embodiment, have wavelengths in a range of about 10-15 nanometers.

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Little Compton, RI, United States of America

Malcolm W McGeoch