Correlation between fixed positive charge and hot-electron immunity for nitridized oxides

Nitrogen in the gate oxide of a 3.3-V, 0.4-μm CMOS technology was modulated in a variety of ways, including treatments with N₂O, NO, oxidation at elevated pressure, and post-oxidation annealing. A direct correlation was observed between the fixed positive charge and the hot-electron immunity, regardless of the means by which the nitrogen was incorporated, or subsequently annealed. The implication is that one benefit and one drawback of nitrided-oxide gate oxides are inextricably linked, with significant effects on the transistor design.