Growth of heavy ion-induced nanodots at the SiO2–Si interface: Correlation with ultrathin gate oxide reliability

Abstract

Scaling-down the oxide thickness induces weakness influencing its intrinsic reliability. Even unbiased, swift heavy ions irradiated devices clearly show oxide alteration. Despite numerous studies on oxide reliability, some results are not yet well understood. In this paper, we focus on the structural degradation induced in thin silicon oxide films on silicon substrate after a 210MeV low fluence gold ion irradiation and on its effect on the reliability of MOS devices in radiation-harsh environments. We describe such degradation as a local silicon growth in the SiO2 layer, near the SiO2–Si interface. Experimental results can bring some emergent elements to explain earlier works in the field of oxide reliability. Based on the specific behavior of heavy ion-irradiated oxides, this paper aims to link together thermal spike model, heavy ion-induced nanodots and reliability of ultrathin gate oxides. We propose to evaluate the possible sensitivity of some high-k materials in radiation-harsh environments with respect to their thermal conductivity property.