X-ray lithography for the 1990s?

X-ray lithography Is a proximity printing process using ~10-Å x rays. Resolutions of 0.1 µm have been demonstrated in a number of laboratories around the world, and a large, relative to optical lithography, depth of focus has been observed as well as 100% process latitude. This process latitude is an excellent attribute and has a significant role in the apparent insensitivity of x rays to defects and excellent linewidth control achieved with x rays. X-ray lithography employs no optical elements between mask and wafer which could limit the field size as in optical lithography. Chip or field size is limited by mask defect density and overlay. Intrinsic exposing rates, determined by the ratio of x-ray power to resist sensitivity, is of the order of 10 cm2/s—a very suitable rate of exposure for manufacturing.