Electrical characterization of metal-oxide-high-κ dielectric-oxide-semiconductor (MOHOS) structures for memory applications

摘要

Conventional SONOS (polysilicon-oxide-nitride-oxide-silicon) non-volatile memory devices use silicon nitride as the charge storage layer. In this work, metal-oxide-high-κ dielectric-oxide-silicon (MOHOS) structures are fabricated using HfO_2 and Dy_2O_3 high-κ dielectrics as the charge storage layer. The Al/SiO_2/Dy_2O_3/SiO_2/Si capacitors have a C-V memory window of 1.88 V and a leakage current density of 10~(-8) A/cm~2. This leakage current is lower than those of Al/SiO_2/HfO_2/SiO_2/Si capacitors and other similar capacitors reported in the literature. A minimum detection window of 0.5 V for MOHOS capacitors can be maintained up to 2 × 10~8 s using as-deposited Dy_2O_3. The better performance of the Al/SiO_2/Dy_2O_3/SiO_2/Si structure over Al/SiO_2/HfO_2/SiO_2/Si is attributed to the larger conduction band offset at the Dy_2O_3/SiO_2 interface (2.3 eV) versus 1.6 eV at the HfO_2/SiO_2 interface.