Nanopillar and nanohole fabrication via mixed lithography

We report a fabrication method for the production of nanopillar (NP) or nanohole (NH) arrays together with a micrometer-sized structure within a single layer. On a 200 mm silicon wafer, we produced 200-400 nm NP or NH arrays using electron beam lithography (EBL). The EBL patterns on a positive-tone EB resist - either a poly(methyl methacrylate) or chemically semi-amplified resist - were transferred to a hard mask oxide (HMO) layer using reactive-ion etching (RIE), as the first etching step. We used the HMO as an intermediate layer to connect the EB patterns to photolithography patterns. On the EB-patterned HMO layer, large-scale photolithography patterns were produced on a photoresist (PR), and transferred to the HMO layer using the second RIE step. After removing the PR, the mixed EB and photolithography patterns in the HMO layer were transferred to the target layer in the third RIE step. Our method offers an efficient way to combine nanometer-sized EBL patterns with high-throughput photolithography patterns in a single layer.