Abstract

Nanostructures are defined to be ultrasmall structures and devices with dimensions less than or equal to 100 nm. Conventional methods for making thin film structures involve exposure of a thin layer of a polymer resist on a suitable substrate to define a pattern, which is than developed and used to fabricate the structures either by deposition, or by etching [1]. The feature sizes of the structures depend both on the resolution of the resist and the imaging method used to expose the resist [1,2]. The materials quality of nanostrustures is also an important factor. In many cases the nanostructures must be crystallographically perfect. Resistless methods of patterning, followed by epitaxial growth could significantly simplify nanofabrication by eliminating a number of processing steps associated with the application, exposure, development, and removal of the resist. The advantage of epitaxial growth is that unlike etching, it is less prone to produce damage in the regions adjacent to the structures. The molecular size effect with polymer based resists such as PMMA is believed to be a significant factor in limiting the resolution (“grain size”) in electron beam lithography (EBL) to 10 nm. Surface adsorption layers such as the hydride layer on the Si surface are characterized by relatively strong chemical bonding which produces a highly uniform coverage that terminates at a single monolayer. Because of these properties surface adsorption layers are attractive candidates as ultrathin, ultrahigh resolution resists for electron beam patterning.

© 1997 Optical Society of America