Disilane-based stacked structures were first proposed to demonstrate that the nitrogen incorporation was enhanced in the RTN2O annealed tetraethylorthosilicate (TEOS) oxide fabricated on disilane-based polysilicon films. Compared with the oxide fabricated on the silane-based polysilicon film, the nitrogen incorporation in the disilane-based oxides is six times higher. To study the nitrogen incorporation effects on the RTN2O annealed TEOS oxides, the disilane-based polysilicon stacked on the silane-based polysilicon film structure was proposed. We found that the oxide quality was largely improved by the same surface morphology of bottom polysilicon films. We think the this approach could be used in fabricating dynamic random access memory (DRAM) to have better data retention characteristics and to improve the reliability of DRAM and flash memory devices.