Irradiation effects of 6 MeV electron on electrical properties of Al/Al2O3/n-Si MOS capacitors

Abstract

The influence of 6 MeV electron irradiation on the electrical properties of Al/Al2O3/n-Si metal-oxide-semiconductor (MOS) capacitors has been investigated. Using rf magnetron sputtering deposition technique, Al/Al2O3/n-Si MOS capacitors were fabricated and such twelve capacitors were divided into four groups. The first group of MOS capacitors was not irradiated with 6 MeV electrons and treated as virgin. The second group, third group and fourth group of MOS capacitors were irradiated with 6 MeV electrons at 10 kGy, 20 kGy, and 30 kGy doses, respectively, keeping the dose rate similar to 1 kGy/min. The variations in crystallinity of the virgin and irradiated MOS capacitors have been compared from GIXRD (Grazing Incidence X-ray Diffraction) spectra. Thickness and in-depth elemental distributions of individual layers were performed using Secondary Ion Mass Spectrometry (SIMS). The device parameters like flat band voltage (V-FB) and interface trap density (D-it) of virgin and irradiated MOS capacitors have been calculated from C vs V and G/omega vs V curve, respectively. The electrical properties of the capacitors were investigated from the tan delta vs V graph. The device parameters were estimated using C-V and G/omega-V measurements. Poole-Frenkel coefficient (beta(PF)) of the MOS capacitors was determined from leakage current (I)-voltage (V) measurement. The leakage current mechanism was proposed from the beta(PF) value. (c) 2012 Elsevier Ltd. All rights reserved.