Electron irradiation induced amorphous SiO2 formation at metal oxide/Si interface at room temperature; electron beam writing on interfaces

Abstract

Al2O3 (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 SiO2 around the interface was observed. The oxygen for the silicon dioxide growth was provided by the electron bombardment induced bond breaking in Al2O3 and the subsequent production of neutral and/or charged oxygen. The amorphous SiO2 rich layer has grown into the Al2O3 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.

Interface Induced Diffusion; Area Selective Interface Patterning

“…The excitation of defects in the present circumstances has been discussed in our previous paper 5 . Its essence is the following.…”

“…Here we note that Si movement was also observed at room temperature since SiO2 formation occurred, that movement was, however, not thermally activated diffusion but by the Cabrera-Mott process; see also ref. 5. To explain the observed diffusion, we recall that defect production is temperature independent thus defect formation occurs during irradiation at 700 o C. According to eq.…”

“…In our previous paper 5 we have studied effect of electron bombardment on the Al2O3 / Si substrate system since this structure is frequently applied in photovoltaic applications 6,7 . It was observed that due to room temperature electron bombardment, a SiO2 layer had grown on the Al2O3 / Si interface.…”

Interface induced diffusion

“…In this study similar samples have been used as in the previous study 8 , where the initial state of the samples had been carefully characterized and published. In short: the in-depth composition has been determined by AES depth profiling (see depth profiles in Figs.…”

“…In our previous paper 8 we have studied effect of electron bombardment on the Al 2 O 3 /Si substrate system at room temperature; in this paper we study the same system at various elevated temperature. A great variety of alterations occur when varying the sample temperature during irradiation, ranging from serious degradation of the sample (at 500 °C) to slight metallic Si diffusion to the nearly perfect Al 2 O 3 layer (at 700 °C).…”