Formation of silicon nanocrystals embedded in high- κ dielectric HfO₂ and their application for charge storage

Annealing thin films of silicon containing HfO₂ films deposited by an electron-beam coevaporation produces silicon nanocrystals embedded in high- κ dielectric HfO₂. Such films can be used to fabricate nonvolatile memory devices. By changing the Si content in the precursor HfSi_x O₂ (x=1, 2, 3, or 4) film, the size and density of silicon nanocrystal could be controlled and high-density of silicon nanocrystals could be obtained. Transmission electron microscopy observations showed that the maximum density of silicon nanocrystals was as high as 1.3× 1013 cm-2 for HfSi₄ O₂ and the average nanocrystal diameter was 4.3 nm. The metal-oxide semiconductor capacitor memory structure with embedded silicon nanocrystals in HfSi₄ O₂ exhibited the largest memory window, 3.94 V under ±5 V sweep voltage.