Chemical states and electrical properties of a high-k metal oxide/silicon interface with oxygen-gettering titanium-metal-overlayer

Abstract

The authors report on the chemical bonding structure of the HfO2∕Si (001) stack after the SiO2 interfacial layer (IL) is partially removed by a reactive titanium metal overlayer. Using synchrotron photoelectron spectroscopy, they found that ultrathin SiO2-like IL ∼6.5Å thick, which is significantly less than the initial SiO2 IL thickness of ∼15Å, exists at the HfO2∕Si interface with an overlying Ti electrode. The dissociated Si from SiO2 IL is believed to go onto Si substrate where it regrows epitaxially. The interfacial trap density of the Ti-electrode sample was extracted to be ∼1.6×1011eV−1cm−2 near the midgap of Si, which was comparable to that of the control sample with W electrode.

Hf O 2 gate dielectric on (NH4)2S passivated (100) GaAs grown by atomic layer deposition

“…In the SRPES technique, the monitored offsets in the valence-band spectra can be utilized to map out the energy-band alignment 22,23 for the interface between deposited ALD HfO 2 and the passivated GaAs. In order to have an accurate valence-band edge measurement, the energy shift induced by the surface charging during photoemission should be corrected by aligning to the Ga 3d core level peak.…”

Bulk and Interfacial Oxygen Defects in HfO2 Gate Dielectric Stacks: A Critical Assessment

“…Under transient re-oxidation conditions, oxygen loss from the HfO 2 film will be negligible; the right hand side of equation [5] . [9] The connection between interstitial concentration and fixed charge is established by assuming equilibrium between oxygen interstitials in the HfO 2 film bulk and oxygen interstitials which passivate the HfO 2 /SiO 2 interface.…”

“…, [5] where 1 and 1 are chemical reaction rate constants for the forward (oxygen incorporation) and reverse (oxygen loss) reactions at the electrode/HfO 2 interface; 2 and 2 are the same for the HfO 2 /SiO 2 interface; and a is an effective inter-atomic spacing. The solution of equation [5] [7] if oxygen incorporation from the SiO 2 interface layer into the HfO 2 layer is assumed to be negligible compared to the incorporation from the gas phase during steady state reoxidation (as also assumed by Guha and Narayanan).…”

Formation characteristics and photoluminescence of Ge nanocrystals in HfO2

“…5 Hf-based oxides are one of the most attractive high-k dielectrics due to their high permittivity and compatibility with CMOS processing. 6 This has led to an interest in the formation of NCs within HfO 2 , including Ge NCs, for advanced CMOS technology. 7 The size and density of Ge NCs or SiGe nanodots ͑NDs͒ are known to be distributed nonuniformly within amorphous SiO 2 matrix due to the high diffusivity of Ge atoms.…”