Electron irradiation induced SiO₂ growth at Al₂O₃/Si interface

Medium energy e- or X-ray irradiation can cause structural, chemical changes or defect formation in the surface close region of the irradiated materials. These phenomena in surface sensitive electron spectroscopies such as AES or XPS can cause evaluation problems however they could be harnessed for various purposes.

Electron induced migration has been observed and electron beam irradiation has been used to accelerate chemical reaction; oxygen being on the surface of Al could be excited by low energy electrons to form oxide at room temperature. Irradiation of properly chosen precursor molecules adsorbed to a surface by electron beam results in well-defined thin films growth according to a desired template.

These changes that occur mainly in the surface region of the material e.g. defect formation or structural changes caused by the irradiation explained by bond breaking or atomic movements respectively.

We have observed electron irradiation induced transport and chemical reaction at the Al2O3/Si interface. This interface has been thoroughly studied in the quest of high-k materials.

Thin Al oxide covered Si substrate was irradiated by 5 keV electrons at various temperatures. AES depth profiling revealed drastic change at the interface region; Si oxide layer growth in expense of Al oxide was observed at ambient temperature irradiation, while metallic Al appeared if the temperature of the sample is around 500o C during irradiation.