Approaches to nanofabrication on Si(100) surfaces: Selective area chemical vapor deposition of metals and selective chemisorption of organic molecules

The selective removal of hydrogen from a passivated Si(100) surface with an ultrahigh vacuum scanning tunneling microscope (STM) allows nanometer-sized “templates” of clean Si(100) to be defined on an otherwise unreactive surface. Such depassivated areas have already been shown to react selectively with O2 and NH3 in preference to the surrounding H-terminated surface. This selectivity suggests two more sophisticated approaches to fabricating nanostructures with this technique: (1) selective metallization by thermal chemical vapor deposition, and (2) formation of ordered organic monolayers by reaction with specific organic molecules. In the first case, an intrinsic difference in the reaction rate of a metal precursor with the clean and H-terminated Si(100) surface results in selective deposition of a metal on the STM-patterned area. In order to prevent hydrogen desorption and loss of selectivity, the metal precursor must dissociate its ligands at relatively low temperatures. In the second case, the pattern...