Near Field X-ray Lithography to 15 nm.

It is time to revisit X-ray. By enhancing, in the Near Field, Proximity X-ray Lithography (PXL), the technique is demonstrated that extends to 15 nm printed feature size with 2:1 ratio of pitch to line width. “Demagnification by bias” of clear mask features is positively used in Fresnel diffraction together with rapid, multiple exposures of sharp peaks. Pitch is kept small by multiple, stepped exposures of the intense image followed by single development. The optical field is kept compact at the mask. Since the mask-wafer gap scales as the square of the mask feature size, mask feature sizes and mask-wafer gaps are comparatively large. A Critical Condition has been identified which is typically used for the highest resolution. Many devices, including batches of microprocessors, have been demonstrated previously by traditional 1X PXL which is the most mature of the Next Generation Lithographies and which is now further extended. Throughput and cost are conventional