Improved Performance of Yttrium-Doped Al2O3 as Inter-Poly Dielectric for Flash-Memory Applications

Yttrium-doped Al2O3 (YxAlyO) with different yttrium contents prepared by co-sputtering method is investigated as the inter-poly dielectric (IPD) for flash memory applications. A poor SiO2-like interlayer formed at the IPD/Si interface is confirmed by X-ray photoelectron spectroscopy, and can be suppressed by Y doping through the transformation of silica into silicate. Compared with Al2O3 and Y2O3 films, the optimized YxAlyO film shows lower interface-state density, lower bulk charge-trapping density, higher dielectric constant, and smaller gate leakage, due to the suppressed interlayer and good thermal property ascribed to appropriate Y and Al contents in the film. Therefore, the optimized YxAlyO film is a promising candidate as the IPD for flash memory.