Conductance transient, capacitance–voltage and deep-level transient spectroscopy characterization of atomic layer deposited hafnium and zirconium oxide thin films S. Due~ nas a, * , H. Cast an a , J. Barbolla a , K. Kukli b,c , M. Ritala b , M. Leskel€ a b a Departamento de Electricidad y Electr onica, E.T.S.I. Telecomunicaci on, Universidad de Valladolid, Campus ‘‘Miguel Delibes’’, 47011 Valladolid, Spain b Department of Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 Univ. Helsinki, Finland c Institute of Experimental Physics and Technology, University of Tartu, T€ ahe 4, EE-51010 Tartu, Estonia Abstract High-permittivity HfO 2 and ZrO 2 based oxides grown by atomic layer deposition are investigated. Both ZrO 2 and HfO 2 are materials of high chemical stability and may form relatively stable interface with silicon substrate. To amorphize the structure and increase the resistivity of the dielectric layer, the high-permittivity material was mixed with another high band-gap material such as Al 2 O 3 . This work presents experimental results obtained from electrical characterization of metal–insulator–semiconductor structures based on these dielectrics. Capacitance–voltage, deep- level transient spectroscopy and conductance transient analysis have been used to prove the promising performances of these advanced materials to obtain good interface quality in the incoming CMOS technology. Mixtures of nanolayers of zirconium or hafnium oxide and aluminium oxide yield the best behaviour. They show acceptable density levels of disordered-induced gap states in the insulator level and interface state densities similar to those of stoichiometric oxides. Ó 2003 Elsevier Ltd. All rights reserved. Keywords: High k dielectrics; Metal–insulator–semiconductor (MIS); Interface states; Disordered-induced gap states 1. Introduction HfO 2 and ZrO 2 are considered as perspective high- permittivity (high-k) materials for silicon-based metal– oxide–semiconductor (MOS) devices [1–6]. Suitable deposition techniques must provide films with uniform structures and thickness controlled at the level of a few atomic layers. Preferred growth technologies are those based on chemical vapour deposition (CVD) in a strictly surface-controlled regime. Uniform growth in CVD is related to relatively low-sticking probability of precursor molecules which is achieved at low temperatures and/or by modest reactivity. Another way is to make use of the atomic layer deposition (ALD) technique [7], where the alternate saturative adsorption and reaction of two precursors results in self-limiting submonolayer-by- submonolayer film growth. Since precursors do not meet in the gas phase in the ALD process, they can be chosen as reactive as possible, thus lowering the growth tem- peratures in comparison with CVD. In the present study, 9–12 nm thick films, nanolayered mixtures of HfO 2 or ZrO 2 and Al 2 O 3 (Hf(Zr)–Al–O), and mixtures of HfO 2 or ZrO 2 , Al 2 O 3 and Nb 2 O 5 (Hf(Zr)–Al–Nb–O) were grown in order to investigate the electrical characteristics of MIS capacitors on p-type silicon substrates. The interface states as well as de- fects inside the insulator bulks were measured by using capacitance–voltage (C–V), deep-level transient spec- troscopy (DLTS) and conductance transient (G-t) * Corresponding author. Tel.: +34-98-342-3679; fax: +34-98- 342-3675. E-mail address: sduenas@ele.uva.es (S. Due~ nas). 0038-1101/$ - see front matter Ó 2003 Elsevier Ltd. All rights reserved. doi:10.1016/S0038-1101(03)00172-2 Solid-State Electronics 47 (2003) 1623–1629 www.elsevier.com/locate/sse