Nano-optical CVD and nanophotolithography using an optical near-field nonresonant to electronic transition

In near-field optical chemical vapor deposition (NFO-CVD), photo dissociation can take place under nonresonant conditions, i.e., with visible light, due to the inherent properties of the optical near field. We succeeded the deposition of the nanometric Zn dots 70 nm wide and 24 nm high by NFO-CVD using the metal-organic gas Zn(acac)₂, which is not usually used for conventional optical CVD due to its low optical activity. This technique makes it possible to use various light and gas sources to deposit a variety of nanometric materials. This peculiar photochemical reaction of an optical near field is not limited to optical CVD, but can be applied to general photochemical reactions. We demonstrate near-field photolithography using a 532 nm laser. The pattern fabricated on photoresist was 150 nm wide and 25 nm deep.