Abstract:
An EUV light source apparatus and method are disclosed, which may comprise a pulsed laser providing laser pulses at a selected pulse repetition rate focused at a desired target ignition site; a target formation system providing discrete targets at a selected interval coordinated with the laser pulse repetition rate; a target steering system intermediate the target formation system and the desired target ignition site; and a target tracking system providing information about the movement of target between the target formation system and the target steering system, enabling the target steering system to direct the target to the desired target ignition site. The target tracking system may provide information enabling the creation of a laser firing control signal, and may comprise a droplet detector comprising a collimated light source directed to intersect a point on a projected delivery path of the target, having a respective oppositely disposed light detector detecting the passage of the target through the respective point, or a detector comprising a linear array of a plurality of photo-sensitive elements aligned to a coordinate axis, the light from the light source intersecting a projected delivery path of the target, at least one of the which may comprise a plane-intercept detection device. The droplet detectors may comprise a plurality of droplet detectors each operating at a different light frequency, or a camera having a field of view and a two dimensional array of pixels imaging the field of view. The apparatus and method may comprise an electrostatic plasma containment apparatus providing an electric plasma confinement field at or near a target ignition site at the time of ignition, with the target tracking system providing a signal enabling control of the electrostatic plasma containment apparatus. The apparatus and method may comprise a vessel having and intermediate wall with a low pressure trap allowing passage of EUV light and maintaining a differential pressure across the low pressure trap. The apparatus and method may comprise a magnetic plasma confinement mechanism creating a magnetic field in the vicinity of the target ignition site to confine the plasma to the target ignition site, which may be pulsed and may be controlled using outputs from the target tracking system.
Abstract:
The present invention provides a reliable, high-repetition rate, production line compatible high energy photon source. A very hot plasma containing an active material is produced in vacuum chamber. The active material is an atomic element having an emission line within a desired extreme ultraviolet (EUV) range. A pulse power source comprising a charging capacitor and a magnetic compression circuit comprising a pulse transformer, provides electrical pulses having sufficient energy and electrical potential sufficient to produce the EUV light at an intermediate focus at rates in excess of 5 Watts. In preferred embodiments designed by Applicants in-band, EUV light energy at the intermediate focus is 45 Watts extendable to 105.8 Watts.
Abstract:
An apparatus and method is described which may comprise a plasma produced extreme ultraviolet (“EUV”) light source multilayer collector which may comprise a plasma formation chamber; a shell within the plasma formation chamber in the form of a collector shape having a focus; the shell having a sufficient size and thermal mass to carry operating heat away from the multilayer reflector and to radiate the heat from the surface of the shell on a side of the shell opposite from the focus. The material of the shell may comprise a material selected from a group which may comprise silicon carbide, silicon, Zerodur or ULE glass, aluminum, beryllium, molybdenum, copper and nickel. The apparatus and method may comprise at least one radiative heater directed at the shell to maintain the steady state temperature of the shell within a selected range of operating temperatures.
Abstract:
An apparatus/method may comprise, a multi-layer reflecting coating forming an EUV reflective surface which may comprise an inter-diffusion barrier layer which may comprise a carbide selected from the group ZrC and NbC or a boride selected from the group ZrB2 and NbB2 or a disilicide selected from the group ZrSi2 and NbSi2 or a nitride selected from the group BN, ZrN, NbN, BN, ScN and Si3N4. The apparatus and method may comprise an EUV light source collector which may comprise a collecting mirror which may comprise a normal angle of incidence multi-layer reflecting coating; an inter-diffusion barrier layer comprising a material selected from the group comprising a carbide selected from the group ZrC and NbC, or a boride selected from the group ZrB2 and NbB2 or a disilicide selected from the group ZrSi2 and NbSi2 a nitride selected from the group BN, ZrN, NbN, BN, ScN and Si3N4.
Abstract:
Systems and methods are disclosed for protecting an EUV light source plasma production chamber optical element surface from debris generated by plasma formation. In one aspect of an embodiment of the present invention, a shield is disclosed which comprises at least one hollow tube positioned between the optical element and a plasma formation site. The tube is oriented to capture debris while allowing light to pass through the tube's lumen via reflection at relatively small angles of grazing incidence. In another aspect of an embodiment of the present invention, a shield is disclosed which is heated to a temperature sufficient to remove one or more species of debris material that has deposited on the shield. In yet another aspect of an embodiment of the present invention, a system is disclosed which a shield is moved from a light source plasma chamber to a cleaning chamber where the shield is cleaned.
Abstract:
Systems and methods for EUV Light Source metrology are disclosed. In a first aspect, a system for measuring an EUV light source power output may include a photoelectron source material disposed along an EUV light pathway to expose the material and generate a quantity of photoelectrons. The system may further include a detector for detecting the photoelectrons and producing an output indicative of EUV power. In another aspect, a system for measuring an EUV light intensity may include a multi-layer mirror, e.g., Mo/Si, disposable along an EUV light pathway to expose the mirror and generate a photocurrent in the mirror. A current monitor may be connected to the mirror to measure the photocurrent and produce an output indicative of EUV power. In yet another aspect, an off-line EUV metrology system may include an instrument for measuring a light characteristic and MoSi2/Si multi-layer mirror.
Abstract:
The present invention provides a high energy photon source. A pair of plasma pinch electrodes are located in a vacuum chamber. The chamber contains a working gas which includes a noble buffer gas and an active gas chosen to provide a desired spectral line. A pulse power source provides electrical pulses at voltages high enough to create electrical discharges between the electrodes to produce very high temperature, high density plasma pinches in the working gas providing radiation at the spectral line of the source or active gas. Preferably the electrodes are configured co-axially. The central electrode is preferably hollow and the active gas is introduced out of the hollow electrode. This permits an optimization of the spectral line source and a separate optimization of the buffer gas. In preferred embodiments the central electrode is pulsed with a high negative electrical pulse so that the central electrode functions as a hollow cathode. Preferred embodiments present optimization of capacitance values, anode length and shape and preferred active gas delivery systems are disclosed. Preferred embodiments also include a pulse power system comprising a charging capacitor and a magnetic compression circuit comprising a pulse transformer. Special techniques are described for cooling the central electrode. In one example, water is circulated through the walls of the hollow electrode. In another example, a heat pipe cooling system is described for cooling the central electrode.
Abstract:
A device is disclosed which may comprise a system generating a plasma at a plasma site, the plasma producing EUV radiation and ions exiting the plasma. The device may also include an optic, e.g., a multi-layer mirror, distanced from the site by a distance, d, and a flowing gas disposed between the plasma and optic, the gas establishing a gas pressure sufficient to operate over the distance, d, to reduce ion energy below a pre-selected value before the ions reach the optic. In one embodiment, the gas may comprise hydrogen and in a particular embodiment, the gas may comprise greater than 50 percent hydrogen by volume.
Abstract:
An apparatus for generating EUV radiation is disclosed which may include a target material, a system generating a laser beam for interaction with the target material and a pair of electrodes. A pulse power electrical circuit may be provided for generating a discharge between said electrodes to produce EUV radiation from said target material.
Abstract:
Systems and methods are disclosed for reducing the influence of plasma generated debris on internal components of an EUV light source. In one aspect, an EUV metrology monitor is provided which may have a heater to heat an internal multi-layer filtering mirror to a temperature sufficient to remove deposited debris from the mirror. In another aspect, a device is disclosed for removing plasma generated debris from an EUV light source collector mirror having a different debris deposition rate at different zones on the collector mirror. In a particular aspect, an EUV collector mirror system may comprise a source of hydrogen to combine with Li debris to create LiH on a collector surface; and a sputtering system to sputter LiH from the collector surface. In another aspect, an apparatus for etching debris from a surface of a EUV light source collector mirror with a controlled plasma etch rate is disclosed.