Hafnium oxide (HfO 2 ) and zirconium oxide (ZrO 2 ) are two high-materials having the potential to replace silicon oxide (SiO 2 ) as the gate dielectric. Atmospheric molecular contamination can affect the quality of the new gate dielectric film in a manner similar to SiO 2 . Characterization of contaminant adsorption behavior of these high-films should assist in deciding their potential for successful integration in silicon metal oxide semiconductor technology. The interaction of moisture and organics ͑in particular, isopropanol, IPA͒ as common interfacial contaminants with a 5 nm HfO 2 film deposited by atomic layer chemical vapor deposition ͑ALCVD͒, which is a trademark of ASM International͒ is investigated using atmospheric pressure ionization mass spectrometry ͑APIMS͒; the kinetics and mechanism are compared to that of ZrO 2 and SiO 2 . HfO 2 and ZrO 2 have similar moisture adsorption loading, but are significantly higher than that of SiO 2 . However, almost all the adsorbed moisture can be removed from SiO 2 and HfO 2 after a 300°C bake under nitrogen purge, whereas ZrO 2 surfaces retain 20-30% of the adsorbed moisture. Experiments with IPA show that the adsorption loading on the three surfaces has the following order: ZrO 2 Ͼ HfO 2 Ͼ SiO 2 . A multilayer model for adsorption of water and IPA is developed to understand the mechanism of interactions of contaminants with the three surfaces. Results from the application of this multilayer model to the experimental data indicate that ZrO 2 forms the strongest surfacehydroxyl ͑X-OH͒ bond.

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Thermal stability of gate stack structures composed of ZrO2 gate dielectrics and silicon electrodes was investigated. The ZrO2 films were deposited by atomic layer deposition, while the polycrystalline silicon electrodes were deposited using different variants of chemical (CVD) and physical vapor deposition (PVD). Zirconium silicide formation was noted in all CVD-electroded samples after subsequent annealing treatments at temperatures above 750 °C, but not in the room temperature PVD-electroded samples, even after gate annealing at 1050 °C. The dependence of zirconium silicide formation on the Si deposition process was explained using thermodynamic arguments which explicitly include the effects of oxygen deficiency of the metal oxide films.

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It has recently been reported that nitrogen oxide species (e.g., N2O5, NO2, NO3, and/or N2O) can have an impact on ozone based atomic layer deposition (ALD) of metal oxides when ozone is generated by dielectric barrier discharge (DBD) in O2/N2 mixtures. In this work, we further investigate the effect of the O2/N2 ratio in the DBD for HfO2 ALD using HfCl4 as metal precursor. Using O3 in the absence of nitrogen oxides, uniform HfO2 layers are obtained between 200 and 250 C in a hot wall cross flow reactor. The self-limiting nature of the O3 and HfCl4 reaction is demonstrated at 225 C and the growth-per-cycle is 0.12 nm. At higher temperature, O3 decomposes at the HfO2 coated reactor walls, resulting in a decreasing HfO2 thickness over Si substrates in the direction of the gas flow. Using O3 in combination with nitrogen oxides by DBD in N2/O2 mixtures, we obtained uniform HfO2 layers in the 200–300C temperature range. At 300C, the GPC is 0.14 nm and the HfO2 films show a low impurity content. Both processes produce high quality dielectric layers in Pt gated capacitors. VC 2011 The Electrochemical Society. [DOI: 10.1149/1.3561423] All rights reserved. Manuscript submitted November 18, 2010; revised manuscript received February 1, 2011. Published March 17, 2011. Atomic Layer Deposition (ALD) is a thin film deposition tech-nique with a number of unique capabilities, such as growth contro