High performance nonvolatile memory using SiO2/SiOx/SiOxNy stack on excimer laser-annealed polysilicon and the effect of blocking thickness on operation voltage

Abstract

Silicon-rich SiOx material is a good charge storage candidate for memory applications that promise a large memory window and low operation voltage. Nonvolatile memory (NVM) devices fabricated on excimer laser-annealed polysilicon using SiO2/SiOx/SiOxNy (OOxOn) structure are investigated with SiO2 blocking thicknesses changing from 15 to 20 to 30 nm. The Si-rich SiOx material exposed numerous non-bridging oxygen hole-centre defect sources and a rich silicon phase in the base material. These defects, as well as amorphous silicon clusters existing in the SiOx layer, enhance the charge storage capacity of the device. Retention properties were ensured by 3.2 nm SiOxNy tunnelling layer growth via N2O plasma-assisted oxynitridation. NVM characteristics showed a retention exceeding 85% of the threshold voltage shift after 104 s and greater than 70% after 10 years. Depending on the blocking thickness of 15, 20 or 30 nm, operating voltages varied from ±9 to ±13 V at a programming/erasing duration of only 1 ms. These excellent operating properties of the OOxOn structure make it a potential competitor among the new generation of memory structures on glass.