SOQUEL, Calif., Feb. 26 -- Actinix researchers Andrew Merriam and James JacobActinix have been granted US Patent No. 6,525,868 for a system and method to generate coherent radiation at vacuum ultraviolet (UV) wavelengths using efficient four-wave mixing. The patent is applicable to 157 nm semiconductor microlithography, photomask metrology and inspection, atomic physics research and nanotechnology.
Actiniex said the method described in the patent involves preparing a special "atomic cocktail" of xenon and mercury atoms. The xenon atoms provide the nonlinear effect that actually creates the vacuum UV light while the mercury atoms increase the strength of the interaction through a process called phasematching. Actinix uses two beams from a compact solid-state laser system to drive the xenon/mercury "four wave mixer." High power (up to one watt) and high spectral purity vacuum UV radiation in the wavelength range of 100 to 200 nm will be possible with this system, the company said.
For example, starting with ten watts of green laser power, Actinix expects to generate over one-tenth of a watt at 157 nm. This highly coherent vacuum ultraviolet light could then be injected into larger excimer laser amplifiers, resulting in improved photolithography exposure tools. Lower power embodiments will be used for metrology and inspection tools for advanced 157 nm phase shift photomasks. The UV source will also replace excimer lasers in applications where higher spatial and spectral quality is required, Actinix said.
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