Characteristics of high-k dielectric ECR-ALD lanthanum hafnium oxide (LHO) films

In this study, we investigated the characteristics of various lanthanum hafnium oxide (LHO) films with different lanthanum (La) concentrations deposited by an electron cyclotron resonance plasma-enhanced atomic layer deposition (ECR-ALD). Tris(isopropyl-cyclopentadienyl)lanthanum (La(iPrCp)3) and tetrakis(ethylmethylamino)hafnium (TEMAHf) were utilized as the La and hafnium (Hf) precursors, respectively. When the La/(La + Hf) atomic percent ratio was 49.1%, the growth rate of the LHO film was 0.5 Å/cycle, with a dielectric constant of 16.3. As the La concentration was increased, the dielectric constant decreased. In addition, we found that a La-hydrate phase (La–O–H) can be easily formed when the La/(La + Hf) is over about 50%.