X-ray lens may reduce feature size in proximity lithography applications
Scientists at the University of Leicester (Leicester, England) have developed an x-ray lens that may allow fabrication of microcircuit components hundreds of times smaller than the current record of 0.18 ?m. OThe immediate aim is to enable fabrication of transistors less than 0.10 ?m across,O explains researcher Adam Brunton. X-rays cause less diffraction than the longer-wavelength UV light currently used to expose microcircuit masks so shadows are less blurred and circuit features can be smaller. The lens, similar to a Olobster eyeO polycapillary x-ray astronomy lens, is made by Nova Scientific (Sturbridge, MA) and collimates x-rays from a hot-plasma point source. The optic is fabricated from a glass blank comprising millions of circular microchannels. Microchannel core glass is removed with acid, a process that can take several days, according to Nova Scientific chief scientist Bruce Feller. Microchannel walls must be smooth, with less than 1-nm roughness, for proper x-ray grazing incidence for collimating. After etching, the lens is heated on a form for its final contour. A proof-of-principle demonstration of the lens will take place next month at the Lawrence Livermore National Laboratory (Livermore, CA) where an x-ray source will mimic an x-ray stepper used for lithography.