Hydrogen induced positive charge generation in gate oxides

This article investigates the H2-anneal induced positive charge generation in the gate oxide of metal-oxide-semiconductor field-effect transistors fabricated by a submicron complementary metal-oxide-semiconductor process. A significant number (∼1012 cm−2) of fixed and mobile positive charges are generated at 450 °C. Properties (reactivity, electrical and thermal stability) of these positive charges are compared with the positive charges observed in the buried oxide of silicon-on-insulator devices. The differences in these two are investigated, in terms of their transportation time across the oxide, uniformity and sources of hydrogen. Attention is paid to the role played by boron in the generation and the possible connection between the positive species observed here and the defects responsible for the positive bias temperature instability. Efforts are made to explain the difference in reactivity between the H2-anneal induced positive species and the hydrogenous species released by irradiation or electrical stresses.