Improved Performance of Yttrium-Doped $\hbox {Al}_{2}\hbox {O}_{3}$ as Inter-Poly Dielectric for Flash-Memory Applications

Yttrium-doped Al₂O₃ (Y_xAI_yO) 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 sup pressed by Y doping through the transformation of silica into silicate. Compared with Al₂O₃ and Y₂O₃ films, the optimized Y_xAI_yO 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 Y_xAI_yO film is a promising candidate as the IPD for flash memory.