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

摘要

This letter reveals the physical and electrical properties of silicon dioxide $(hbox{SiO}_{2})$ formed by the plasma selective oxidation (plasma selox) using $hbox{O}_{2}$ and $ hbox{H}_{2}$ 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 $^{circ}hbox{C}$ –700 $^{circ}hbox{C}$ showed much better time-dependent dielectric-breakdown characteristics than those formed by the conventional thermal selox at 850 $^{circ}hbox{C}$. On the other hand, in the case of very low temperature (25 $^{circ}hbox{C}$) 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 $hbox{SiO}_{2}$ layer through thermal desorption spectroscopy measurements.