ULTRAHIGH-VACUUM SCANNING TUNNELING MICROSCOPE-BASED NANOLITHOGRAPHY AND SELECTIVE CHEMISTRY ON SILICON SURFACES

Nanofabrication on silicon surfaces has been achieved in a manner simi lar to e-beam/resist technology, in which hydrogen serves as a monolay er resist for exposure by the electron beam from an ultrahigh vacuum ( UHV) scanning tunneling microscope (STM). Ln this scheme, hydrogen is selectively desorbed from Si(100)2x1:H surfaces that have been prepare d by atomic hydrogen dosing under UHV background conditions. To remove hydrogen, the tip bias is raised, under feedback control, and then th e desired pattern is drawn. Two regimes of hydrogen desorption are obs erved: at higher energies, above similar to 6.0 V, direct electron-sti mulated desorption occurs, whereas at lower biases, desorption occurs via a multiple excitation vibrational heating mechanism and exhibits a strong current dependence. Patterning linewidth down to a single dime r row has been achieved in the vibrational heating regime. The selecti ve removal of hydrogen suggests many possibilities for subsequent chem ical treatments in which the hydrogen-terminated silicon remains inert . We have performed experiments which demonstrate selective oxidation of, and nitrogen incorporation into, the STM-patterned regions.