Cluster beam targets for laser plasma extreme ultraviolet and soft x-ray sources
OwnerGlenn D. Kublak, Martin C. Richardsoninventors
Life of this patent
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Abstract
Method and apparatus for producing extreme ultra violet (EUV) and soft x-ray radiation from an ultra-low debris plasma source are disclosed. Targets are produced by the free jet expansion of various gases through a temperature controlled nozzle to form molecular clusters. These target clusters are subsequently irradiated with commercially available lasers of moderate intensity (10.sup.11 -10.sup.12 watts/cm.sup.2) to produce a plasma radiating in the region of 0.5 to 100 nanometers. By appropriate adjustment of the experimental conditions the laser focus can be moved 10-30 mm from the nozzle thereby eliminating debris produced by plasma erosion of the nozzle.
Claims37
A method for producing extreme ultra-violet and soft x-ray radiation, comprising the steps of:
- flowing a gas mixture, said gas mixture comprising a cluster forming gas, a diluent gas and a ternary gas, into a pressurizable valve, said valve comprising;
- a housing that defines a chamber,
- an input channel that communicates with said chamber, said gas flowing through said input channel into said chamber,
- an output channel communicating with said chamber, and
- a temperature controlled nozzle, said nozzle having a gas entrance end, said gas entrance end being fixedly attached to said output channel and an opposite gas exit end, said nozzle having an orifice disposed within,
- said valve being contained within a vacuum chamber;
- pressurizing said gas mixture contained in said valve;
- reducing the pressure in said vacuum chamber;
- adjusting the temperature of said temperature controlled nozzle to a temperature appropriate for forming molecular gas clusters from the selected cluster forming gas;
- forming molecular gas clusters by expanding said high pressure gas contained within said valve through said orifice into said vacuum chamber;
- and
- irradiating said molecular clusters with a laser beam brought to a focus onto said clusters to produce radiation of a selected wavelength.
A method for producing 13 nm radiation comprising the steps of:
- producing molecular clusters of the form (H.sub.2 O).sub.n, where n is equal to at least 100, by supersonically expanding a mixture of water vapor, He and Ar,
- wherein the pressure of water vapor is from about 20 to about 1000 torr, the concentration of Ar is about 10 vol % and the pressure of He is about 5 to 10 atm. through an orifice having a diameter of about 0.1 mm into a chamber having a pressure of less than about 1 Torr;
- and
- irradiating said clusters with a Nd:YAG or KrF eximer pulsed laser, wherein said laser operates at a power of about1 J for about 10 nanoseconds.
An apparatus for producing an ultra-low debris generating laser plasma source of extreme ultra-violet and soft x-ray radiation by irradiating target materials made of large clusters of gas molecules with a laser, said clusters of gas molecules being produced by the supersonic expansion of a cluster forming gas through an orifice, comprising;
- a pressurizable valve, said valve comprising;
- a housing that defines a chamber,
- an input channel that communicates with said chamber, said cluster forming gas flowing through said input channel into said chamber,
- an output channel communicating with said chamber, and
- a temperature controlled nozzle, said nozzle having a gas entrance end, said gas entrance end being fixedly attached to said output channel and an opposite gas exit end, said nozzle having an orifice disposed within, said orifice being configured to maximize the size of gas clusters produced by release of said gas from said chamber through said orifice;
- a means for releasing said gas from said valve, said valve being contained within a vacuum chamber, said vacuum chamber being maintained at a lower
- pressure than said pressurization chamber;
- means for pressuring said gas in said valve;
- a laser for irradiating said clusters;
- and
- means for focusing said laser onto said molecular gas clusters.
Dependencies are inferred from the claim text.