Incorporation effect of thin Al2O3 layers on ZrO2-Al2O3 nanolaminates in a composite oxide-high-κ-oxide stack for floating-gate flash memory devices

We demonstrate the electrical properties and reliability of ZrO2-Al2O3 nanolaminates as high-kappa dielectric materials in a composite oxide-high-kappa-oxide (OKO) stack for floating-gate flash memory devices with 40 nm technology nodes and beyond. The effects of incorporating thin Al2O3 layers into ZrO2 films as an inserting layer and a capping layer on the electrical properties and reliability are discussed. The incorporation of Al2O3 layers significantly improves the leakage current versus the capacitive-equivalent thickness (CET) and TDDB characteristics of the ZrO2-Al2O3 nanolaminate compared with those of the pure ZrO2 owing to the mismatch of the grain boundaries, improved resistance to silicon diffusion, and enhanced energetic-electron hardness of the high-K film.