Scanning probe lithography. 1. Scanning tunneling microscope induced lithography of self-assembled n-alkanethiol monolayer resists

The tip of a scanning tunneling microscope was used to fabricate geometrically well structures within organized, self-assembled monolayer resist that have critical dimensions ranging from 60 nm to 5 micrometers. To achieve nanometer-scale lithography, a Au(111) substrate was coated with a self- assembled monolayer of HS(CH2)17CH3, which functions as an ultrathin (approx. 2. 5 nm) resist, and then the resist was etched by an STM tip. This treatment results in window-like features that penetrate the organic monolayer. Nanolithographically defined features have been characterized by scanning tunneling microscopy, scanning electron microscopy, and electrochemical methods. For example, since mass and electron transfer to the conductive Au substrate are blocked by the monolayer everywhere except in the STM-etched regions, the windows serve as ultramicroelectrodes. The limiting current that results from radial diffusion of a bulk-phase redox species to the etched window is in close agreement with that predicted by theory.