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 &mgr;m) 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 bothp‐ andn‐type Si samples, for oxides grown in dry O2or steam at temperatures over a wide range (900–1000 °C), and for PMA treatment either in dry N2or 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.