Influence of hydrogen incorporation on the reliability of gate oxide formed by using low-temperature plasma selective oxidation applicable to sub-50-nm W-polymetal gate devices

This letter reveals the physical and electrical properties of silicon dioxide (SiO₂ formed by the plasma selective oxidation (plasma selox) using O₂ and H₂ gas mixture, which is applicable to sub-50-nm tungsten-polymetal gate memory devices without capping nitride film. Metal-oxide-semiconductor capacitors with gate oxide formed by the plasma selox at the process temperature in the range of 400 °C-700 °C showed much better time-dependent dielectric-breakdown characteristics than those formed by the conventional thermal selox at 850 °C. On the other hand, in the case of very low temperature (25 °C) plasma selox, the gate oxide degradation such as initial breakdown was found. It turned out to be due to the excessive hydrogen and water incorporation into the SiO₂ layer through thermal desorption spectroscopy measurements.