Imaging interferometric lithography for arbitrary patterns

Conventional optical lithography (OL) is limited by the spatial frequency coverage (similar to NA/lambda) of the optical system. Interferometric lithography (IL), which approaches the ultimate linear system spatial frequency coverage limit of optics (2/lambda), provides a simple technique to produce periodic patterns at the requisite scale for the next several ULSI generations. imaging interferometric lithography (IIL), a true integration of optical and interferometric lithography, extends this capability to arbitrary pattern fabrication. Modeling and simulation results show that arbitrary patterns with dense CDs extending to 120-nm at I-line and to 65-nm at a 193-nm exposure wavelength are possible. Initial experiments demonstrate that the coverage in frequency space is increased up to (similar to 3NA/lambda) for a 3-exposure IIL configuration and the resolution is concomitantly increased by a factor of 3. Development of IIL may extend the life of optical lithography to sub-100-nm CD generations.