Low energy electron beam stimulated surface reaction:: Selective etching of SiO2/Si using scanning tunneling microscope

We report here an experimental study of the low energy electron stimulated reaction (LEESR) carried out on a SiO2/Si surface using a scanning tunneling microscope (STM). By applying 100-150 V bias voltage and about 5 nA to below 1 mu A current to the SiO2/Si surface, while the surface was kept at 700 degrees C and 100-200 nm away from the STM tip, a surface reaction was induced by the low energy e-beam exposure. A surface of the Si substrate with clear atomic steps was observed within the exposed area, which indicates selective etching of SiO2 by which windows as small as 70 nm in diameter were cut through the SiO2 layer. This result demonstrates the possibility of fabricating a SiO2/Si surface by the LEESR etching and of performing a new type of well-controlled nanofabrication using STM.