Gate-width dependence of radiation-induced interface traps in metal/SiO2/Si devices

The density of radiation-induced interface traps in a post-metal-annealed (PMA) Al-gate metal-oxide-semiconductor (metal/SiO2/Si) depends strongly on the linewidth of the metal gate over a wide range (1–750 μm) of linewidths studied, although there is no discernible dependence prior to the irradiation. The dependence is such that the narrower the linewidth, the fewer the radiation-induced interface traps. Such dependence has been generally observed for both p- and n-type Si samples, for oxides grown in dry O2 or steam at temperatures over a wide range (900–1000 °C), and for PMA treatment either in dry N2 or in forming gas (10% H2+90% N2). The results can be qualitatively explained by a model based on the gate linewidth dependence of the SiO2/Si interfacial stress prior to irradiation, which affects the radiation sensitivity in accordance with the strained bond model.