Electrical properties of atomic-layer-deposited La2O3 films using a novel La formamidinate precursor and ozone

Abstract

La2O3 films were grown by atomic layer deposition technique using a novel formamidinate precursor, tris(N,N′-diisopropylformamidinato) lanthanum [La(iPrfAMD)3], with H2O and O3 as an oxidant. La2O3 films grown with H2O in the film exhibited a parasitic chemical vapor deposition type growth possibly due to a La(OH)x component. However, the use of O3 as the oxidant revealed a stable ALD process window. A post-deposition annealing (PDA) of the deposited La2O3 films using O3 significantly reduces leakage current density by four orders of magnitude relative to as-deposited samples. The dielectric constant of La2O3 films with a TaN metal gate is found to be ∼29, which is higher than reported values for CVD and ALD La2O3 films.