NANOMETER-SCALE LOCAL OXIDATION OF SILICON USING SILICON-NITRIDE ISLANDS FORMED IN THE EARLY STAGES OF NITRIDATION

We have studied the silicon nitride (SiN) nucleation on the Si(111) 7X 7 surface dye to thermal nitridation with scanning tunneling microscop y (STM), and applied the resultant small SiN islands to oxidation mask s in local oxidation of Si (LOCOS) process for fabrication of nanomete r-scale Si structures. The nitrides appear as dark regions in STM imag es and the average size increases (the density decreases) with increas ing nitridation temperature. When the nitrided surface is successively oxidized in the etching mode with a reaction of Si+O-2-->SiO up arrow , the nitrides turn to bright regions by selective etching of the clea n 7X7 regions and the brightness (height) increases with increasing et ching time. Thus, the microscopic LOCOS process is demonstrated and na nometer-scale Si pillars are fabricated. (C) 1996 American Institute o f Physics.