Analysis of high- k HfO 2 and HfSiO 4 dielectric films

Abstract

The impact of primary ion bombardment conditions on SIMS depth profiles through HfO 2 high- k films was investigated. Independent of the sputter beam conditions, Hf depth profiles show the apparent presence of Hf throughout the film, as well as tailing of the Hf signal into the substrate. A long tail region of decay length ∼10 nm seen for reactive and inert sputter beams, largely independent of the energy, is inconsistent with simple ion beam-induced mixing. Chemical state depth profiles by XPS show that Hf transforms into metallic Hf 0 in the Si substrate, corresponding to the tail regions of SIMS profiles. SIMS and XPS backside profiles confirm that Hf is not initially present in the Si substrate. Hf chemical state changes observed in XPS sputter depth profiles depend on the film stoichiometry, as seen with HfSi x O y films of different composition.