Hf-aluminate films with and without an interfacial layer during growth and postannealing - Structural and electrical characteristics

The structural and electrical characteristics resulting from an interfacial layer of Hf-aluminate films grown by atomic layer deposition were investigated using medium energy ion scattering spectroscopy and electrical measurements. The Hf-aluminate films with an interfacial layer of SiO2 grew with higher Hf contents and lower interdiffusion of Si than the film without an interfacial SiO2 layer. In Hf-aluminate films with an interfacial layer of SiO2, the thickness of HfO2 decreased slightly after postannealing as a result of crystallization. In films without an interfacial layer of SiO2, the structural rearrangement was observed due to the interdiffusion of Si with no change in thickness. The structural changes affected electrical properties such as the oxide trap charge and the interfacial trap charge. Moreover, reoxidation of the Hf-aluminate films without an interfacial layer of SiO2 caused a dramatic increase in the thickness of the interfacial region. This resulted in a positive shift of flatband voltage. (c) 2005 The Electrochemical Society.