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 x 3 cm(2) 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 photo-resist nanocolumns with a diameter of similar or equal to 110 nm. N-2 plasma can transfer this pattern at a 1: 1 ratio to BARC nanocolumns. It is found that reactive O-2/N-2 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 O-2/N-2 plasma shrink etching. Combining the etching of O-2/N-2 plasma with N-2 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