Silicon micro/nanofabrication using metastable helium atom beam lithography

We utilize metastable helium (He*) atom beam lithography to pattern silicon substrates by using self-assembled monolayer (SAM) of octadecyltrichlorosilane (OTS) grown directly on silicon surface as resist. An improved wet-chemical etching method was used to transfer the resist pattern into silicon substrate. Negative and positive pattern formations with well-defined edges were observed for silicon(100) substrate with SAM after exposure to the He* atom beam followed by the etching. Results indicate a clear transition from positive to negative patterns relies on the He* dosage. The pattern sizes on silicon were successfully decreased to the order of 100 nm, even less than 50 nm.