Electronic structure of high-k transition metal oxides and their silicate and aluminate alloys

This article addresses differences between the electronic structure of: (i) alternative high-k transition metal (TM) rare earth dielectrics and (ii) SiO2 and Si oxynitride alloys by presenting a systematic x-ray absorption spectroscopy study of transitions between TM n p-core states and TM metal n + 1 - d* and n + 2 s * antibonding/conduction band states (n = 2, 3, and 4) that is complemented by studies of O atom K-1 edge absorption spectra. Ab initio calculations based on small clusters establish the localization of the n + 1 d* states on the TM metals. Ab initio electronic structure calculations are also used to interpret other aspects of the optical, ultraviolet, x-ray, and electron spectroscopies, and also provide a basis for interpretation of electrical results, thereby narrowing the field of possible replacement dielectrics for advanced semiconductor devices. (C) 2002 American Vacuum Society.