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) 7X7 surface dye to thermal nitridation with scanning tunneling microscopy (STM), and applied the resultant small SiN islands to oxidation masks in local oxidation of Si (LOCOS) process for fabrication of nanometer-scale Si structures. The nitrides appear as dark regions in STM images and the average size increases (the density decreases) with increasing 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 clean 7X7 regions and the brightness (height) increases with increasing etching time. Thus, the microscopic LOCOS process is demonstrated and nanometer-scale Si pillars are fabricated. (C) 1996 American Institute of Physics.