Physicochemical properties of HfO2 in response to rapid thermal anneal

Abstract

Changes in the composition of atomic layer deposited, uncapped hafnium dioxide films, as a function of anneal temperature, have been evaluated by several advanced analytical techniques including; x-ray reflectivity, high-resolution transmission electron microscopy, and medium energy ion scattering. It is shown that such measurements of the high-k/Si interface layer are inconclusive and may be misinterpreted to suggest the presence of an HfxSi1−xO2 (x∼0.5) transition layer. It is also demonstrated that high-temperature anneal of uncapped films may result in the formation of voids which propagate through the dielectric layer into the silicon substrate. Trends associated with defect generation, interfacial oxide growth, and the low probability of material intermixing during anneal processing are discussed.