Atomic layer deposition of Y2O3 and yttrium-doped HfO2 using a newly synthesized Y(iPrCp)2(N-iPr-amd) precursor for a high permittivity gate dielectric

We systematically investigated the effects of Y doping in HfO2 dielectric layer, focusing on structural phase transformation and the dielectric properties of the resultant films. Y doping was carried out using atomic layer deposition (ALD) with a novel Y(iPrCp)2(N-iPr-amd) precursor, which exhibits good thermal stability without any decomposition and clean evaporation. As a result, the ALD process of the Y2O3 films showed well-saturated and linear growth characteristics of ∼0.45 Å/cycle without significant incubation delays and produced pure Y2O3 films. Then, yttrium-doped HfO2 films with various Y/(Y + Hf) compositions (yttrium content: 0.6- 4.8 mol%) were prepared by alternating Y2O3 and HfO2 growth cycles. Structural and electrical characterization revealed that the addition of yttrium to HfO2 induced phase transformations from the monoclinic to the cubic or tetragonal phases, even at low post-annealing temperatures of 600 °C, and improved leakage current densities by inducing oxygen vacancy-related complex defects. A maximum relative dielectric constant of ∼33.4 was obtained for films with a yttrium content of ∼1.2 mol%. Excellent EOT scalability was observed down to ∼1 nm without dielectric constant degradation.