Multiscale hierarchical microstructures fabricated by combining direct laser writing and laser interference lithography for direction-dependent patterning

We investigate how laser interference lithography (LIL) can be combined with direct laser writing (DLW) to pattern periodic gratings on inclined and faceted resist geometries. DLW defines planar, sloped, and multi-facet shapes, while LIL introduces controllable periodic structures by adjusting the sample’s rotation and tilt during exposure. Systematic experiments show that surface inclination governs both the recorded period and groove morphology, and that appropriate sample tilting enables facet-selective illumination, leaving non-addressed slopes unexposed. Using this strategy, we fabricate heteroperiodic prisms carrying two distinct periods and four-facet pyramids carrying four distinct periods, leading to heteroperiodic hierarchical surfaces within a single resist layer. The combined DLW–LIL process thus provides a practical route to achieve spatially varied periodicity on inclined and multi-facet structures, supporting the design of multiscale surfaces with direction-dependent optical or wetting responses.