Feedback-Controlled Lithography (FCL)
Feedback-controlled lithography (FCL) is a technique that allows researchers to use the Scanning Tunneling Miscroscope (STM) to precisely and selectively build structures at the nanoscale.
Developed by Mark Hersam (Northwestern University) and Joseph Lyding (University of Illinois at Urbana-Champaign), FCL is conducted by first coating a silicon sample with hydrogen (otherwise known as hydrogen passivated silicon). Using the STM, researchers can then image (or see) the surface of the silicon sample. When an electric voltage is applied to the STM tip from an outside source, the silicon-hydrogen bonds are broken. By controlling the position of the STM tip, hydrogen atoms are thus removed with atomic precision.
This technique allows fundamental studies of chemistry at the single molecule level and has opened the door for building prototype electronic devices and other structures at the nanoscale.
(Jour. Vac. Sci. Tech.A, 18, 1349, 2000).