Interfacial reactions of Gd- and Nb-oxide based high-k layers deposited by aqueous chemical solution deposition

In this work, ultrathin layers of GdOx, NbOx and GdNbOx, deposited with ACSD have been investigated. Because of the high temperature anneals utilized in the process flow of electronic devices, interactions of the deposited high-k materials and the substrate are analyzed. The deposited layers of GdOx, NbOx and GdNbOx on SiO2 and Al2O3 are annealed in an oxidizing and inert atmosphere and studied by XRD, GATR–FTIR and ellipsometry to assess layer-substrate interactions and crystallization behavior. With temperatures up to 900 °C, some minor interactions with the SiO2/Si substrates and no interaction with the Al2O3 substrate were observed. At 1000 °C, however, more intense interactions with both substrates in both ambients are observed (severe silicate formation, interlayer regrowth and interaction with Al2O3). HT–XRD on the deposited layers shows that all the layers crystallized well below 900 °C. It is concluded that GdNbOx could be a more advantageous high-k material, compared to its monometal counterparts, based on its limited interaction with the substrate at high temperatures and in oxidative ambient.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights► GdOx, NbOx and GdNbOx deposited on SiO2/Si and Al2O3/Si substrates are investigated. ► Annealing shows low interaction of GdNbOx in contrast to GdOx and NbOx with substrates. ► GdNbOx gives lower thickness variations after annealing indicating high stability. ► Crystallization in inert atmosphere is delayed up to 850 °C.