Evaluation of $DyScOx$ as an alternative blocking dielectric in TANOS memories with $Si3N4$ or Si-rich SiN charge trapping layers

Dysprosium scandate $DyScOx$ with a $κ$ value of $∼20$ has been investigated as blocking dielectric in charge trapping memory capacitors. $DyScOx$ films with 28 and 18 nm thicknesses are deposited by atomic layer deposition on two different kinds of silicon nitride used as charge trapping layer, while $SiO2$ is used as tunnel oxide and TaN is used as metal gate. Memory capacitors with $Al2O3$ as blocking layer with similar equivalent oxide thickness (EOT) to $DyScOx$ are also characterized as benchmarks. $DyScOx$ thermal stability on both $Si3N4$ and Si-rich SiN at annealing temperatures up to $900°C$ demonstrates the complementary metal-oxide semiconductor process compatibility of the oxide. Especially when deposited on Si-rich SiN, comparable program and slightly better retention performance with $Al2O3$ are observed for $DyScOx$⁠, whereas erase still needs to be improved. Some variations in the electrical performance are found between the $DyScOx$-based stacks with different charge trapping layer and have been discussed. Scaling the total stack EOT by reducing $DyScOx$ thickness from 28 to 18 nm allows a large program/erase window, but with the penalty of an increased charge loss during retention. Our results suggest that the key factors in further improvement of $DyScOx$ as blocking dielectric are the dielectric quality and leakage current.