Thickness Scaling and Reliability Comparison for the Inter-Poly High- κ Dielectrics

In this letter, the inter-poly dielectric (IPD) thickness, scaling, and reliability characteristics of Al₂O₃ and HfO₂ IPDs are studied, which are then compared with conventional oxide/nitride/oxide (ONO) IPD. Regardless of deposition tools, drastic leakage current reduction and reliability improvement have been demonstrated by replacing ONO IPD with high-permittivity (high-kappa) IPDs, which is suitable for mass production applications in the future. Moreover, metal-organic chemical vapor deposition (MOCVD) can be used to further promote dielectric reliability when compared to reactive-sputtering deposition. By using the MOCVD, the charge-to-breakdown (Q_BD) can be significantly improved, in addition to enhanced breakdown voltage and effective breakdown field. Our results clearly demonstrate that high- IPD, particularly deposited by MOCVD, possesses great potential for next-generation stacked-gate Flash memories.