Evaluation of DyScO(x) as an alternative blocking dielectric in TANOS memories with Si(3)N(4) or Si-rich SiN charge trapping layers

Dysprosium scandate DyScO x with a κ value of ∼20 has been investigated as blocking dielectric in charge trapping memory capacitors. DyScO x 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 SiO 2 is used as tunnel oxide and TaN is used as metal gate. Memory capacitors with Al 2 O 3 as blocking layer with similar equivalent oxide thickness (EOT) to DyScO x are also characterized as benchmarks. DyScO x thermal stability on both Si 3 N 4 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 Al 2 O 3 are observed for DyScO x , whereas erase still needs to be improved. Some variations in the electrical performance are found between the DyScO x -based stacks with different charge trapping layer and have been discussed. Scaling the total stack EOT by reducing DyScO x 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 DyScO x as blocking dielectric are the dielectric quality and leakage current