Memory characteristics of cobalt-silicide nanocrystals embedded in HfO2 gate oxide for nonvolatile nanocrystal flash devices

Cobalt-silicide (CoSi2) nanocrystals (NCs) were investigated for use in charge storage for metal oxide semiconductor (MOS) devices with thin HfO2 tunneling and control oxide layers. CoSi2 NCs were synthesized by exposure of Co/Si/HfO2 tunneling oxide/Si stacks to an external UV laser. Observations from transmission electron microscopy and x-ray photoelectron spectroscopy clearly confirm the formation of CoSi2 NCs and the values of Co-Si bonding energies that are shifted 0.3 eV from original values, respectively. The CoSi2 NCs in MOS devices exhibited a large memory window of 3.4 V as well as efficient programming/erasing speeds, good retention, and endurance times. (c) 2008 American Institute of Physics.