Improvement of charge retention in flash memory devices by very light doping of lanthanum into an aluminum-oxide blocking layer

It is demonstrated that the dielectric constant of Al ₂O ₃ is significantly increased through the addition of a very small amount of La into Al ₂O ₃ followed by a high-temperature post-deposition annealing (PDA). The retention property and reliability of the charge trap flash memory devices fabricated through the proposed method are greatly improved due to the increased κ-value of the Al ₂O ₃ blocking oxide with no sacrifice of the bandgap, as well as a reduced low-field leakage component and improved dielectric relaxation effect.