Polarity asymmetry of stress and charge trapping behavior of thin Hf- and Zr-silicate layers

In this paper, reliability aspects of thin Zr- and Hf-silicate layers are addressed by analyzing the stress induced leakage current (SILC) and charge trapping during constant voltage stress (CVS) and constant current stress (CCS). Voltage polarity and temperature effects on the degradation of the layers are also studied. SILC in silicate layers is found to be strongly polarity dependent and it is suggested that the damage causing it is near silicate/Si interface. SILC has a transient component and its recovery is explained by the trapping/detrapping of traps participating in Poole–Frenkel conduction. Unlike SiO2, hot carrier induced damage is not the main mechanism for SILC creation. Therefore, the origin of SILC in silicate layers is distinctly different to SiO2.