Electron irradiation induced amorphous SiO 2 formation at metal oxide/Si interface at room temperature; electron beam writing on interfaces

Al 2 O 3 (5 nm)/Si (bulk) sample was subjected to irradiation of 5 keV electrons at room temperature, in a vacuum chamber (pressure 1 × 10 −9 mbar) and formation of amorphous SiO 2 around the interface was observed. The oxygen for the silicon dioxide growth was provided by the electron bombardment induced bond breaking in Al 2 O 3 and the subsequent production of neutral and/or charged oxygen. The amorphous SiO 2 rich layer has grown into the Al 2 O 3 layer showing that oxygen as well as silicon transport occurred during irradiation at room temperature. We propose that both transports are mediated by local electric field and charged and/or uncharged defects created by the electron irradiation. The direct modification of metal oxide/silicon interface by electron-beam irradiation is a promising method of accomplishing direct write electron-beam lithography at buried interfaces.