ASET

Association of Super-advanced Electronics Technologies

has been taking the initiative in developing EUV lithography technology in Japan for the past three years. The aspherical mirror metrology using a visible light point diffraction interferometer (PDI)

the wave front measurement using an at-wavelength PDI

and an at wavelength reflectometry for multilayers

various imaging simulations

multilayer coatings for the mask

the development of absorber materials for mask patterning

the mask substrate cleaning technique

and various photoresist processes have been developed. The visible light PDI employs a 0.5-μm pinhole as an aperture to generate an ideal spherical wave front and can measure a 0.3-N A mirror maximum. The at-wavelength PDI can measure the wave front error of the projection optics. The at-wavelength reflectometer can measure the reflectivity of multilayers and the round-robin test is taking place among ASET

the ALS in Lawrence Berkeley

and BESSY in Germany. The mask cleaning technique employs a supersonic hydro-cleaning technique. We have confirmed that the single layer resists can be used for EUV lithography.