Enhanced zirconia oxide dielectric quality of germanium p-channel metal oxide semiconductor field effect transistor by in-situ low temperature treatment in atomic layer deposition process

Abstract

The gate dielectric quality of germanium (Ge) p-channel metal oxide semiconductor field effect transistor (MOSFET) is enhanced by using an in-situ low temperature treatment in atomic layer deposition (ALD) process in this work. With additional oxygen flow or remote oxygen-based plasma, the dangling bond, oxygen vacancy, and oxide traps in the ALD-formed zirconia oxide gate dielectric can be effectively passivated. Unlike the traditional post deposition annealing process that generally causes an increased equivalent oxide thickness (EOT) significantly, the in-situ low temperature treatment can lower the EOT value, reduce the gate leakage current, and improve the gate dielectric quality at the same time. As a result, the sample with an additional oxygen gas flow can exhibit a lower hysteresis value, better frequency dispersion characteristics, higher on/off current ratio, lower sub-threshold swing value, higher transconductance value, higher field effect mobility value, and better uniformity, simultaneously. This dielectric quality enhancement technique with in-situ low temperature process is promising to overcome the trade-off between EOT and gate leakage for the future Ge MOSFET devices.