X-ray lithography — A review and assessment of future applications

Abstract

The radiation used in x-ray lithography spans a rather broad range, from about 4 to 50 Å. At the short wavelength end, transmission through mask membranes and vacuum windows is high, and minimum linewidth is of the order of 1/2 μm. At the long wavelength end, mask selection is limited, exposure is done in vacuum and minimum linewidth is about 100 Å. At intermediate wavelengths, one can make numerous tradeoffs among resolution, system configuration, masks and resists. X-ray lithography at the AlK wavelength (8.34 Å) is compared with scanning electron beam lithography from the point of view of exposure time, assuming a step-and-repeat strategy. The use of gap adjustment to compensate for homogeneous substrate distortion may be an important advantage of x-ray lithography relative to other parallel exposure techniques.