Shrinkage Control of Photoresist for Large‐Area Fabrication of Sub‐30 nm Periodic Nanocolumns

A method to fabricate large‐area arrays of nanocolumns without a deep‐UV laser source is reported. This method allows high‐yield fabrication of 3 × 3 cm² arrays of sub‐30 nm nanocolumns made of bottom antireflection layer coating (BARC) by combining displacement Talbot lithography (DTL) using a monochromatic UV beam (365 nm wavelength) with plasma etching techniques. DTL is used to manufacture an initial pattern of periodic photoresist nanocolumns with a diameter of ≈110 nm. N₂ plasma can transfer this pattern at a 1:1 ratio to BARC nanocolumns. It is found that reactive O₂/N₂ plasma etching on the other hand can shrink the BARC nanocolumns to sub‐30 nm dimensions. The shrink‐etching process can be reproducibly controlled by tuning the gas flow ratio and the etching time. It is highly remarkable that the verticality of these BARC nanocolumns remains during O₂/N₂ plasma shrink etching. Combining the etching of O₂/N₂ plasma with N₂ plasma allows to produce BARC nanocolumns over the entire diameter range from 110 to sub‐30 nm. The fabrication approach enables large‐footprint fabrication of size‐tunable periodic nanostructures that have many potential applications in photonics, electronics, biosensors, smart surfaces, catalysis, and biomedical analysis.