Spatial modulation of nanopattern dimensions by combining interference lithography and grayscale-patterned secondary exposure

Functional nanostructures are exploited for a variety of cutting-edge fields including plasmonics,metasurfaces,and biosensors,just to name a few.Some applications require nanostructures with uniform feature sizes while others rely on spatially varying morphologies.However,fine manipulation of the feature size over a large area remains a substantial challenge because mainstream approaches to precise nanopatterning are based on low-throughput pixel-by-pixel processing,such as those utilizing focused beams of photons,electrons,or ions.In this work,we provide a solution toward wafer-scale,arbitrary modulation of feature size distribution by introducing a lithographic portfolio combining interference lithography(IL)and grayscale-patterned secondary exposure(SE).Employed after the high-throughput IL,a SE with patterned intensity distribution spatially modulates the dimensions of photoresist nanostructures.Based on this approach,we successfully fabricated 4-inch wafer-scale nanogratings with uniform linewidths of＜5％variation,using grayscale-patterned SE to compensate for the linewidth difference caused by the Gaussian distribution of the laser beams in the IL.Besides,we also demonstrated a wafer-scale structural color painting by spatially modulating the filling ratio to achieve gradient grayscale color using SE.