Nonvolatile memory devices with AlOx embedded Zr-doped HfO2 high-k gate dielectric stack

Abstract

MOS capacitors with the ZrHfO-AlOx-ZrHfO gate dielectric structure have been fabricated and studied for memory functions. Without the embedded AlOx film, the capacitor traps negligible amount of charges. With the embedded AlOx layer, the sample traps a large amount of holes or negligible amount of electrons depending on the polarity of the applied gate voltage. The charge retention and frequency dispersion measurements show that some of the holes are loosely retained at the tunnel ZrHfO/AlOx interface and some are deeply retained to the AlOx related sites. The leakage current–voltage curve further confirms the charge trapping capability of the AlOx embedded sample. Nearly half of the originally trapped holes can be retained in the memory device for more than 10 years. The AlOx embedded ZrHfO high-k stack is a good gate dielectric for the nonvolatile memory device.