0167-9317/$ - see front matter Ó 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.mee.2007.04.102 www.elsevier.com/locate/mee Microelectronic Engineering 84 (2007) 2412–2415 Modeling HfO 2 /SiO 2 /Si interface J. L. Gavartin a,* , A. L. Shluger b a Accelrys, 334 Cambridge Science Park, Cambridge, CB4 0WN, UK b London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London WC1H 0AH Abstract We present ab inito calculations of a realistic HfO 2 /SiO 2 /Si interface and discuss its structural and electronic properties. Calculations reveal a variety of possible non-epitaxial atomic arrangements at the interface, associated with a substantial atomic disorder in the SiO 2 and HfO 2 region. Calculated band alignment, although predictably smaller than experimental values, allows for instructive analysis of band gap variation, dipole formation and defects near the interface. Keywords: high-k; disorder; interface; ab initio; band alignment. 1. Introduction Electronic properties of thin oxide films on silicon vary widely with their morphology and with the morphology of the interface. The morphology in turn is very sensitive to small variations in chemical composition and to deposition and post deposition processes. Atomistic modeling proved to be very instrumental in understanding complex ‘process- structure-properties’ relationships, both in Oxide/Silicon and Oxide/Metal interfaces. Early modeling [1-3] considered various epitaxial arrangements of the cubic or tetragonal HfO 2 on Si(100) and invoked simple valency arguments for explanation of the electronic properties of prototype structures. Subsequent work concentrating on the Corresponding author: E-mail address: jgavartin@accelrys.com (J. Gavartin) interface growth kinetics [2-7] had suggested that film growth may be substantially non-epitaxial, and would strongly depend on precursor chemistry. It was also later realized that, although engineering of the abrupt HfO 2 /Si interfaces is possible [8], it usually results in carrier mobility degradation in the channel. It remains a matter of debate whether mobility degradation is intrinsic to abrupt high-k/Si interfaces. However, most practically viable interfaces between HfO 2 and Si contain the interlayer of SiO x (where x 2). In view of this, an effect of an interface dipole on band alignment in HfO 2 /SiO 2 systems had been also investigated [9,10]. Although atomistic modeling to date had established several important structure-property dependencies, the main challenge remains in identification and characterization of the realistic interface models as opposed to simplified (and possibly even unstable)