Effect of MeV electron irradiation on Si-SiO2 structures

18th International Summer School on Vacuum, Electron and Ion Technologies

Kaschieva, S.^1 ; Gushterov, A.^1 ; Angelov, Ch^2 ; Dmitriev, S.N.^3

Acad. G. Nadjakov Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chaussee, 1784 Sofia, Bulgaria^1

Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, 72 Tsarigradsko Chaussee, 1784 Sofia, Bulgaria^2

Flerov Laboratory of Nuclear Reactions, Joint Institute of Nuclear Research, Moscow Region, 141980 Dubna, Russia^3

关键词: Cleaning procedures;    Defect generation;    Electron beam irradiation;    High-energy electron irradiation;    Radiation defects;    Si nanostructures;    Si-SiO2 interfaces;    Thermal oxidation;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/514/1/012039/pdf
DOI  :  10.1088/1742-6596/514/1/012039

来源: IOP

【 摘 要 】

The effect of 20-MeV electron-beam irradiation on Si-SiO2structures was studied. The Si-SiO2samples were fabricated on n-type -oriented Si wafers with resistivity of 4.7 Ω cm. Following a standard cleaning procedures, thermal oxidation in dry O2+ 8 % HCl ambient was performed at 900 °C to produce oxide layer with a thickness of 20-nm. After oxidation, the samples were cooled at a rate of 1oC s-1in the ambient where the oxidation was carried out. The samples were exposed to a beam of 20-MeV electrons with a flux of about 1.2×1015cm-2. The oxide thickness was measured by ellipsometry before and after electron irradiation, which showed that the SiO2thickness in the irradiated Si-SiO2structures increases. This result can be connected with the increase of the oxygen content at the Si-SiO2interface. If one takes into account the defect generation in the whole Si-SiO2structure, it is reasonable to expect that the oxygen motion through the SiO2oxide defects will be stimulated during MeV electron irradiation. The changes on the SiO2surface roughness induced by the high-energy electron irradiation of the Si-SiO2structures were observed by atomic force microscopy (AFM). It was seen that these changes consisted in the formation of nanocrystals at the SiO2surface. We assume that the MeV electron irradiation breaks the Si-O bonds, the free oxygen moves through the radiation defects and creates conditions whereby Si nanostructures are generated in the oxide SiO2and at the SiO2surface of the structures.