Investigation on Molybdenum and Its Conductive Oxides as p-Type Metal Gate Candidates

In this work, we studied molybdenum (Mo) and its conductive oxides (MoO x ) for p-type metal gate application. Three compositions of MoO x have been investigated. The resistivity of Mo/MoO x was found to significantly increase with the oxygen incorporation. A clear phase separation of all MoO x compositions was observed after high-temperature thermal treatment. The incorporation of oxygen was found to be effective to increase the work function (WF) of Mo. However, after full device integration, a significant WF decrease of MoO x was observed, which may be induced during the high-temperature junction activation process. This high-temperature process also led to a significant interfacial silicon oxide layer growth for MoO x gated stacks. The equivalent oxide thickness dependent flatband voltage roll-off behavior and gate leakage will also be discussed.