Formation of dual-phase HfO2–HfxSi1−xO2 dielectric and its application in memory devices

In this paper, we studied the phase-separation phenomenon of Hf0.5Si0.5O2 film deposited on SiO2 or sandwiched by SiO2, by x-ray photoelectron spectroscopy and transmission electron microscopy. The Hf0.5Si0.5O2 film underwent phase separation to form a doublet-phase HfO2–HfxSi1−xO2 (x<0.5) film, and was used as a trapping layer in a metal-blocking oxide-silicon nitride-tunnel oxide-silicon-type memory structure, where the dual-phase HfO2–HfxSi1−xO2 (DPHSO) film replaces the conventional silicon nitride (Si3N4) trapping layer. The charge storage properties of the DPHSO film were investigated and compared with HfO2 and Si3N4. It was found that for a given electric field applied to the tunnel oxide, the programming speed of memory devices using a DPHSO or HfO2 film as a trapping layer is faster than that using Si3N4. This indicates the higher electron-capture efficiency of the DPHSO and HfO2 films. In addition, the double-phase microstructure of the DPHSO film also provided better retention property than pur...