The Contrasting Impacts of the Al<sub>2</sub>O<sub>3</sub> and Y<sub>2</sub>O<sub>3</sub> Insertion Layers on the Crystallization of ZrO<sub>2</sub> Films for Dynamic Random Access Memory Capacitors
Haengha Seo, In Won Yeu, Dae Seon Kwon, Dong Gun Kim, Junil Lim, Tae Kyun Kim, Heewon Paik, Jung‐Hae Choi, Cheol Seong Hwang
Abstract
Abstract This study examines the influences of the Al 2 O 3 and Y 2 O 3 insertion layers (ILs) on the structural and electrical features of ZrO 2 thin films for their application to dynamic random access memory capacitors. The ultra‐thin Al 2 O 3 IL (0.1–0.2 nm) dissolves into the ZrO 2 layers, which causes the top and bottom portions of the ZrO 2 film to merge and have smaller lattice parameters. However, the thicker Al 2 O 3 IL ( >≈ 0.4 nm) forms a continuous layer and separates the top and bottom portions of the ZrO 2 film. Interestingly, the diffusion of Al does not occur in this case. Overall, the dielectric constant (κ) of the ZrO 2 /Al 2 O 3 /ZrO 2 film is lower than that of the undoped ZrO 2 film due to the involvement of the low‐κ Al 2 O 3 IL. In contrast, the Y 2 O 3 IL does not interfere with the grain growth of ZrO 2 , rendering the continuous ZrO 2 grain formation throughout the entire film thickness despite the presence of the continuous region with a higher Y‐concentration. The most crucial finding is that the Y‐doping significantly decreases the leakage current without sacrificing the dielectric constant. This leakage current decrease can be ascribed to the p‐type doping effect of Y ions in the n‐type ZrO 2 .