Abstract
A scanning probe microscope (SPM) was used as a tool for nanolithography. Silicon oxide (SiOx) patterns were formed on silicon (100) and (111) surfaces by means of scanning probe anodization, that is, localized anodization induced by an SPM tip. These anodic SiOx patterns could serve as masks for the chemical etching of Si in alkaline solution. Tetramethylammonium hydroxide (TMAH, (CH3)4NOH) containing no alkaline metal was used as the etching reagent. The roughness of the etched surface in this solution was one tenth that of the Si surface etched in an aqueous solution of potassium hydroxide which was used in our preliminary study. Consequently, on the Si(100) surfaces, we were able to fabricate grooves 40 nm deep and less than 50 nm wide and walls 30 nm high and 40 nm wide. Due to side etching, the aspect ratios of the structures which could be fabricated on the Si(111) surfaces were much lower than those fabricated on Si(100).